rfc9112.original.xml   rfc9112.xml 
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
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submissionType="IETF"
category="std" category="std"
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ipr="pre5378Trust200902" ipr="pre5378Trust200902"
obsoletes="7230" obsoletes="7230"
docName="draft-ietf-httpbis-messaging-19"> updates=""
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<?v3xml2rfc silence="Warning: Setting consensus="true" for IETF STD document"?> number="9112"
<?v3xml2rfc silence="Warning: Expected a valid submissionType (stream) setting"? xmlns:xi="http://www.w3.org/2001/XInclude"
> xml:lang="en">
<front> <front>
<title>HTTP/1.1</title> <title>HTTP/1.1</title>
<seriesInfo name="RFC" value="9112"/>
<seriesInfo name="STD" value="99"/>
<author fullname="Roy T. Fielding" <author fullname="Roy T. Fielding"
initials="R." initials="R."
surname="Fielding" surname="Fielding"
role="editor"> role="editor">
<organization>Adobe</organization> <organization>Adobe</organization>
<address> <address>
<postal> <postal>
<postalLine>345 Park Ave</postalLine> <postalLine>345 Park Ave</postalLine>
<postalLine>San Jose, CA 95110</postalLine> <postalLine>San Jose, CA 95110</postalLine>
<postalLine>United States of America</postalLine> <postalLine>United States of America</postalLine>
skipping to change at line 53 skipping to change at line 54
<uri>https://roy.gbiv.com/</uri> <uri>https://roy.gbiv.com/</uri>
</address> </address>
</author> </author>
<author fullname="Mark Nottingham" <author fullname="Mark Nottingham"
initials="M." initials="M."
surname="Nottingham" surname="Nottingham"
role="editor"> role="editor">
<organization>Fastly</organization> <organization>Fastly</organization>
<address> <address>
<postal> <postal>
<postalLine>Prahran VIC</postalLine> <postalLine>Prahran</postalLine>
<postalLine>Australia</postalLine> <postalLine>Australia</postalLine>
</postal> </postal>
<email>mnot@mnot.net</email> <email>mnot@mnot.net</email>
<uri>https://www.mnot.net/</uri> <uri>https://www.mnot.net/</uri>
</address> </address>
</author> </author>
<author fullname="Julian Reschke" <author fullname="Julian Reschke"
initials="J." initials="J."
surname="Reschke" surname="Reschke"
role="editor"> role="editor">
skipping to change at line 75 skipping to change at line 76
<address> <address>
<postal> <postal>
<postalLine>Hafenweg 16</postalLine> <postalLine>Hafenweg 16</postalLine>
<postalLine>48155 Münster</postalLine> <postalLine>48155 Münster</postalLine>
<postalLine>Germany</postalLine> <postalLine>Germany</postalLine>
</postal> </postal>
<email>julian.reschke@greenbytes.de</email> <email>julian.reschke@greenbytes.de</email>
<uri>https://greenbytes.de/tech/webdav/</uri> <uri>https://greenbytes.de/tech/webdav/</uri>
</address> </address>
</author> </author>
<date year="2021" month="September" day="10"/> <date year="2022" month="June"/>
<area>Applications and Real-Time</area> <area>Applications and Real-Time</area>
<workgroup>HTTP Working Group</workgroup> <workgroup>HTTP Working Group</workgroup>
<keyword>Hypertext Transfer Protocol</keyword> <keyword>Hypertext Transfer Protocol</keyword>
<keyword>HTTP</keyword> <keyword>HTTP</keyword>
<keyword>HTTP message format</keyword> <keyword>HTTP message format</keyword>
<abstract> <abstract>
<t> <t>
The Hypertext Transfer Protocol (HTTP) is a stateless application-level The Hypertext Transfer Protocol (HTTP) is a stateless application-level
protocol for distributed, collaborative, hypertext information systems. protocol for distributed, collaborative, hypertext information systems.
This document specifies the HTTP/1.1 message syntax, message parsing, This document specifies the HTTP/1.1 message syntax, message parsing,
connection management, and related security concerns. connection management, and related security concerns.
</t> </t>
<t> <t>
This document obsoletes portions of RFC 7230. This document obsoletes portions of RFC 7230.
</t> </t>
</abstract> </abstract>
<note title="Editorial Note">
<t>This note is to be removed before publishing as an RFC.</t>
<t>
Discussion of this draft takes place on the HTTP working group
mailing list (ietf-http-wg@w3.org), which is archived at
<eref target="https://lists.w3.org/Archives/Public/ietf-http-wg/"
brackets="angle"/>.
</t>
<t>
Working Group information can be found at <eref target="https://httpwg.org/"
brackets="angle"/>;
source code and issues list for this draft can be found at
<eref target="https://github.com/httpwg/http-core" brackets="angle"/>.
</t>
<t>
The changes in this draft are summarized in <xref target="changes.since.18"/
>.
</t>
</note>
</front> </front>
<middle> <middle>
<section anchor="introduction" title="Introduction"> <section anchor="introduction" title="Introduction">
<t> <t>
The Hypertext Transfer Protocol (HTTP) is a stateless application-level The Hypertext Transfer Protocol (HTTP) is a stateless application-level
request/response protocol that uses extensible semantics and request/response protocol that uses extensible semantics and
self-descriptive messages for flexible interaction with network-based self-descriptive messages for flexible interaction with network-based
hypertext information systems. HTTP/1.1 is defined by: hypertext information systems. HTTP/1.1 is defined by:
</t> </t>
<ul> <ul>
<li>This document</li> <li>This document</li>
<li>"HTTP Semantics" <xref target="HTTP"/> <li>"HTTP Semantics" <xref target="HTTP"/>
</li> </li>
<li>"HTTP Caching" <xref target="CACHING"/> <li>"HTTP Caching" <xref target="CACHING"/>
</li> </li>
</ul> </ul>
<t> <t>
This document specifies how HTTP semantics are conveyed using the This document specifies how HTTP semantics are conveyed using the
HTTP/1.1 message syntax, framing and connection management mechanisms. HTTP/1.1 message syntax, framing, and connection management mechanisms.
Its goal is to define the complete set of requirements for HTTP/1.1 Its goal is to define the complete set of requirements for HTTP/1.1
message parsers and message-forwarding intermediaries. message parsers and message-forwarding intermediaries.
</t> </t>
<t> <t>
This document obsoletes the portions of This document obsoletes the portions of
<xref target="RFC7230" format="none">RFC 7230</xref> related to HTTP/1.1 <xref target="RFC7230" format="none">RFC 7230</xref> related to HTTP/1.1
messaging and connection management, with the changes being summarized in messaging and connection management, with the changes being summarized in
<xref target="changes.from.rfc.7230"/>. The other parts of <xref target="changes.from.rfc.7230"/>. The other parts of
<xref target="RFC7230" format="none">RFC 7230</xref> are obsoleted by <xref target="RFC7230" format="none">RFC 7230</xref> are obsoleted by
"HTTP Semantics" <xref target="HTTP"/>. "HTTP Semantics" <xref target="HTTP"/>.
</t> </t>
<section anchor="requirements.notation" title="Requirements Notation"> <section anchor="requirements.notation" title="Requirements Notation">
<t> <t>
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL The key words "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>", "<bcp14>REQU
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", IRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL
"MAY", and "OPTIONAL" in this document are to be interpreted as NOT</bcp14>", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>", "<bcp14>
described in BCP 14 <xref target="RFC2119"/> RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>",
<xref target="RFC8174"/> when, and only when, they "<bcp14>MAY</bcp14>", and "<bcp14>OPTIONAL</bcp14>" in this document are to
appear in all capitals, as shown here. be interpreted as
</t> described in BCP&nbsp;14 <xref target="RFC2119"/> <xref target="RFC8174"/>
when, and only when, they appear in all capitals, as shown here.
</t>
<t> <t>
Conformance criteria and considerations regarding error handling Conformance criteria and considerations regarding error handling
are defined in <xref target="HTTP" section="2"/>. are defined in <xref target="HTTP" section="2"/>.
</t> </t>
</section> </section>
<section anchor="notation" title="Syntax Notation"> <section anchor="notation" title="Syntax Notation">
<iref primary="true" item="Grammar" subitem="ALPHA"/> <iref primary="true" item="Grammar" subitem="ALPHA"/>
<iref primary="true" item="Grammar" subitem="CR"/> <iref primary="true" item="Grammar" subitem="CR"/>
<iref primary="true" item="Grammar" subitem="CRLF"/> <iref primary="true" item="Grammar" subitem="CRLF"/>
<iref primary="true" item="Grammar" subitem="CTL"/> <iref primary="true" item="Grammar" subitem="CTL"/>
skipping to change at line 173 skipping to change at line 156
<iref primary="true" item="Grammar" subitem="OCTET"/> <iref primary="true" item="Grammar" subitem="OCTET"/>
<iref primary="true" item="Grammar" subitem="SP"/> <iref primary="true" item="Grammar" subitem="SP"/>
<iref primary="true" item="Grammar" subitem="VCHAR"/> <iref primary="true" item="Grammar" subitem="VCHAR"/>
<t> <t>
This specification uses the Augmented Backus-Naur Form (ABNF) notation of This specification uses the Augmented Backus-Naur Form (ABNF) notation of
<xref target="RFC5234"/>, extended with the notation for case-sensitivity <xref target="RFC5234"/>, extended with the notation for case-sensitivity
in strings defined in <xref target="RFC7405"/>. in strings defined in <xref target="RFC7405"/>.
</t> </t>
<t> <t>
It also uses a list extension, defined in <xref target="HTTP" section="5.6.1" />, It also uses a list extension, defined in <xref target="HTTP" section="5.6.1" />,
that allows for compact definition of comma-separated lists using a '#' that allows for compact definition of comma-separated lists using a "#"
operator (similar to how the '*' operator indicates repetition). <xref target operator (similar to how the "*" operator indicates repetition). <xref target
="collected.abnf"/> shows the collected grammar with all list ="collected.abnf"/> shows the collected grammar with all list
operators expanded to standard ABNF notation. operators expanded to standard ABNF notation.
</t> </t>
<t> <t>
As a convention, ABNF rule names prefixed with "obs-" denote As a convention, ABNF rule names prefixed with "obs-" denote
"obsolete" grammar rules that appear for historical reasons. obsolete grammar rules that appear for historical reasons.
</t> </t>
<t anchor="core.rules"> <t anchor="core.rules">
The following core rules are included by The following core rules are included by
reference, as defined in <xref target="RFC5234" sectionFormat="comma" section ="B.1"/>: reference, as defined in <xref target="RFC5234" sectionFormat="comma" section ="B.1"/>:
ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls), ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),
DIGIT (decimal 0-9), DQUOTE (double quote), DIGIT (decimal 0-9), DQUOTE (double quote),
HEXDIG (hexadecimal 0-9/A-F/a-f), HTAB (horizontal tab), LF (line feed), HEXDIG (hexadecimal 0-9/A-F/a-f), HTAB (horizontal tab), LF (line feed),
OCTET (any 8-bit sequence of data), SP (space), and OCTET (any 8-bit sequence of data), SP (space), and
VCHAR (any visible <xref target="USASCII"/> character). VCHAR (any visible <xref target="USASCII"/> character).
</t> </t>
<t anchor="imported.rules"> <t anchor="imported.rules">
The rules below are defined in <xref target="HTTP"/>: The rules below are defined in <xref target="HTTP"/>:
</t> </t>
<sourcecode type="abnf7230"><![CDATA[ BWS = <BWS, see [HT TP], Section 5.6.3> <sourcecode type="abnf9110"><![CDATA[ BWS = <BWS, see [HT TP], Section 5.6.3>
OWS = <OWS, see [HTTP], Section 5.6.3> OWS = <OWS, see [HTTP], Section 5.6.3>
RWS = <RWS, see [HTTP], Section 5.6.3> RWS = <RWS, see [HTTP], Section 5.6.3>
absolute-path = <absolute-path, see [HTTP], Section 4.1> absolute-path = <absolute-path, see [HTTP], Section 4.1>
field-name = <field-name, see [HTTP], Section 5.1> field-name = <field-name, see [HTTP], Section 5.1>
field-value = <field-value, see [HTTP], Section 5.5> field-value = <field-value, see [HTTP], Section 5.5>
obs-text = <obs-text, see [HTTP], Section 5.6.4> obs-text = <obs-text, see [HTTP], Section 5.6.4>
quoted-string = <quoted-string, see [HTTP], Section 5.6.4> quoted-string = <quoted-string, see [HTTP], Section 5.6.4>
token = <token, see [HTTP], Section 5.6.2> token = <token, see [HTTP], Section 5.6.2>
transfer-coding = transfer-coding =
<transfer-coding, see [HTTP], Section 10.1.4> <transfer-coding, see [HTTP], Section 10.1.4>
skipping to change at line 208 skipping to change at line 190
absolute-path = <absolute-path, see [HTTP], Section 4.1> absolute-path = <absolute-path, see [HTTP], Section 4.1>
field-name = <field-name, see [HTTP], Section 5.1> field-name = <field-name, see [HTTP], Section 5.1>
field-value = <field-value, see [HTTP], Section 5.5> field-value = <field-value, see [HTTP], Section 5.5>
obs-text = <obs-text, see [HTTP], Section 5.6.4> obs-text = <obs-text, see [HTTP], Section 5.6.4>
quoted-string = <quoted-string, see [HTTP], Section 5.6.4> quoted-string = <quoted-string, see [HTTP], Section 5.6.4>
token = <token, see [HTTP], Section 5.6.2> token = <token, see [HTTP], Section 5.6.2>
transfer-coding = transfer-coding =
<transfer-coding, see [HTTP], Section 10.1.4> <transfer-coding, see [HTTP], Section 10.1.4>
]]></sourcecode> ]]></sourcecode>
<t anchor="imported.uri.rules"> <t anchor="imported.uri.rules">
The rules below are defined in <xref target="URI"/>: The rules below are defined in <xref target="URI"/>:
</t> </t>
<sourcecode type="abnf7230"><![CDATA[ absolute-URI = <absolute-URI , see [URI], Section 4.3> <sourcecode type="abnf9110"><![CDATA[ absolute-URI = <absolute-URI , see [URI], Section 4.3>
authority = <authority, see [URI], Section 3.2> authority = <authority, see [URI], Section 3.2>
uri-host = <host, see [URI], Section 3.2.2> uri-host = <host, see [URI], Section 3.2.2>
port = <port, see [URI], Section 3.2.3> port = <port, see [URI], Section 3.2.3>
query = <query, see [URI], Section 3.4> query = <query, see [URI], Section 3.4>
]]></sourcecode> ]]></sourcecode>
</section> </section>
</section> </section>
<section anchor="http.message" title="Message"> <section anchor="http.message" title="Message">
<t> <t>
HTTP/1.1 clients and servers communicate by sending messages. HTTP/1.1 clients and servers communicate by sending messages.
skipping to change at line 238 skipping to change at line 219
<iref item="header line"/> <iref item="header line"/>
<t> <t>
An HTTP/1.1 message consists of a start-line followed by a CRLF and a An HTTP/1.1 message consists of a start-line followed by a CRLF and a
sequence of sequence of
octets in a format similar to the Internet Message Format octets in a format similar to the Internet Message Format
<xref target="RFC5322"/>: zero or more header field lines (collectively <xref target="RFC5322"/>: zero or more header field lines (collectively
referred to as the "headers" or the "header section"), an empty line referred to as the "headers" or the "header section"), an empty line
indicating the end of the header section, and an optional message body. indicating the end of the header section, and an optional message body.
</t> </t>
<iref primary="true" item="Grammar" subitem="HTTP-message"/> <iref primary="true" item="Grammar" subitem="HTTP-message"/>
<sourcecode type="abnf7230"><![CDATA[ HTTP-message = start-line C RLF <sourcecode type="abnf9110"><![CDATA[ HTTP-message = start-line C RLF
*( field-line CRLF ) *( field-line CRLF )
CRLF CRLF
[ message-body ] [ message-body ]
]]></sourcecode> ]]></sourcecode>
<t> <t>
A message can be either a request from client to server or a A message can be either a request from client to server or a
response from server to client. Syntactically, the two types of message response from server to client. Syntactically, the two types of messages
differ only in the start-line, which is either a request-line (for requests) differ only in the start-line, which is either a request-line (for requests)
or a status-line (for responses), and in the algorithm for determining or a status-line (for responses), and in the algorithm for determining
the length of the message body (<xref target="message.body"/>). the length of the message body (<xref target="message.body"/>).
</t> </t>
<iref primary="true" item="Grammar" subitem="start-line"/> <iref primary="true" item="Grammar" subitem="start-line"/>
<sourcecode type="abnf7230"><![CDATA[ start-line = request-line / status-line <sourcecode type="abnf9110"><![CDATA[ start-line = request-line / status-line
]]></sourcecode> ]]></sourcecode>
<t> <t>
In theory, a client could receive requests and a server could receive In theory, a client could receive requests and a server could receive
responses, distinguishing them by their different start-line formats. responses, distinguishing them by their different start-line formats.
In practice, servers are implemented to only expect a request In practice, servers are implemented to only expect a request
(a response is interpreted as an unknown or invalid request method) (a response is interpreted as an unknown or invalid request method),
and clients are implemented to only expect a response. and clients are implemented to only expect a response.
</t> </t>
<t> <t>
HTTP makes use of some protocol elements similar to the HTTP makes use of some protocol elements similar to
Multipurpose Internet Mail Extensions (MIME) <xref target="RFC2045"/>. the Multipurpose Internet Mail Extensions (MIME) <xref target="RFC2045"/>.
See <xref target="differences.between.http.and.mime"/> for the See <xref target="differences.between.http.and.mime"/> for the
differences between HTTP and MIME messages. differences between HTTP and MIME messages.
</t> </t>
</section> </section>
<section anchor="message.parsing" title="Message Parsing"> <section anchor="message.parsing" title="Message Parsing">
<t> <t>
The normal procedure for parsing an HTTP message is to read the The normal procedure for parsing an HTTP message is to read the
start-line into a structure, read each header field line into a hash start-line into a structure, read each header field line into a hash
table by field name until the empty line, and then use the parsed table by field name until the empty line, and then use the parsed
data to determine if a message body is expected. If a message body data to determine if a message body is expected. If a message body
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versions of the protocol. This specification defines version "1.1". versions of the protocol. This specification defines version "1.1".
<xref target="HTTP" section="2.5"/> specifies the semantics of HTTP version <xref target="HTTP" section="2.5"/> specifies the semantics of HTTP version
numbers. numbers.
</t> </t>
<t> <t>
The version of an HTTP/1.x message is indicated by an HTTP-version field The version of an HTTP/1.x message is indicated by an HTTP-version field
in the <xref target="message.format" format="none">start-line</xref>. HTTP-ve rsion is case-sensitive. in the <xref target="message.format" format="none">start-line</xref>. HTTP-ve rsion is case-sensitive.
</t> </t>
<iref primary="true" item="Grammar" subitem="HTTP-version"/> <iref primary="true" item="Grammar" subitem="HTTP-version"/>
<iref primary="true" item="Grammar" subitem="HTTP-name"/> <iref primary="true" item="Grammar" subitem="HTTP-name"/>
<sourcecode type="abnf7230"><![CDATA[ HTTP-version = HTTP-name "/" DIGIT "." DIGIT <sourcecode type="abnf9110"><![CDATA[ HTTP-version = HTTP-name "/" DIGIT "." DIGIT
HTTP-name = %s"HTTP" HTTP-name = %s"HTTP"
]]></sourcecode> ]]></sourcecode>
<t> <t>
When an HTTP/1.1 message is sent to an HTTP/1.0 recipient When an HTTP/1.1 message is sent to an HTTP/1.0 recipient
<xref target="HTTP10"/> or a recipient whose version is unknown, <xref target="HTTP10"/> or a recipient whose version is unknown,
the HTTP/1.1 message is constructed such that it can be interpreted the HTTP/1.1 message is constructed such that it can be interpreted
as a valid HTTP/1.0 message if all of the newer features are ignored. as a valid HTTP/1.0 message if all of the newer features are ignored.
This specification places recipient-version requirements on some This specification places recipient-version requirements on some
new features so that a conformant sender will only use compatible new features so that a conformant sender will only use compatible
features until it has determined, through configuration or the features until it has determined, through configuration or the
skipping to change at line 394 skipping to change at line 375
number correctly or when an intermediary is known to blindly forward number correctly or when an intermediary is known to blindly forward
the HTTP-version even when it doesn't conform to the given minor the HTTP-version even when it doesn't conform to the given minor
version of the protocol. Such protocol downgrades <bcp14>SHOULD NOT</bcp14> b e version of the protocol. Such protocol downgrades <bcp14>SHOULD NOT</bcp14> b e
performed unless triggered by specific client attributes, such as when performed unless triggered by specific client attributes, such as when
one or more of the request header fields (e.g., User-Agent) one or more of the request header fields (e.g., User-Agent)
uniquely match the values sent by a client known to be in error. uniquely match the values sent by a client known to be in error.
</t> </t>
</section> </section>
</section> </section>
<section anchor="request.line" title="Request Line"> <section anchor="request.line" title="Request Line">
<t> <t>
A request-line begins with a method token, followed by a single A request-line begins with a method token, followed by a single
space (SP), the request-target, another single space (SP), and ends space (SP), the request-target, and another single space (SP), and ends
with the protocol version. with the protocol version.
</t> </t>
<iref primary="true" item="Grammar" subitem="request-line"/> <iref primary="true" item="Grammar" subitem="request-line"/>
<sourcecode type="abnf7230"><![CDATA[ request-line = method SP reque st-target SP HTTP-version <sourcecode type="abnf9110"><![CDATA[ request-line = method SP reque st-target SP HTTP-version
]]></sourcecode> ]]></sourcecode>
<t> <t>
Although the request-line grammar rule requires that each of the component Although the request-line grammar rule requires that each of the component
elements be separated by a single SP octet, recipients <bcp14>MAY</bcp14> ins tead parse elements be separated by a single SP octet, recipients <bcp14>MAY</bcp14> ins tead parse
on whitespace-delimited word boundaries and, aside from the CRLF on whitespace-delimited word boundaries and, aside from the CRLF
terminator, treat any form of whitespace as the SP separator while terminator, treat any form of whitespace as the SP separator while
ignoring preceding or trailing whitespace; such whitespace includes one or ignoring preceding or trailing whitespace; such whitespace includes one or
more of the following octets: SP, HTAB, VT (%x0B), FF (%x0C), or bare CR. more of the following octets: SP, HTAB, VT (%x0B), FF (%x0C), or bare CR.
However, lenient parsing can result in request smuggling security However, lenient parsing can result in request smuggling security
vulnerabilities if there are multiple recipients of the message and each vulnerabilities if there are multiple recipients of the message and each
skipping to change at line 435 skipping to change at line 416
It is <bcp14>RECOMMENDED</bcp14> that all HTTP senders and recipients support , at a It is <bcp14>RECOMMENDED</bcp14> that all HTTP senders and recipients support , at a
minimum, request-line lengths of 8000 octets. minimum, request-line lengths of 8000 octets.
</t> </t>
<section anchor="request.method" title="Method"> <section anchor="request.method" title="Method">
<iref primary="true" item="method"/> <iref primary="true" item="method"/>
<t> <t>
The method token indicates the request method to be performed on the The method token indicates the request method to be performed on the
target resource. The request method is case-sensitive. target resource. The request method is case-sensitive.
</t> </t>
<iref primary="true" item="Grammar" subitem="method"/> <iref primary="true" item="Grammar" subitem="method"/>
<sourcecode type="abnf7230"><![CDATA[ method = token <sourcecode type="abnf9110"><![CDATA[ method = token
]]></sourcecode> ]]></sourcecode>
<t> <t>
The request methods defined by this specification can be found in The request methods defined by this specification can be found in
<xref target="HTTP" section="9"/>, along with information regarding the HTTP method <xref target="HTTP" section="9"/>, along with information regarding the HTTP method
registry and considerations for defining new methods. registry and considerations for defining new methods.
</t> </t>
</section> </section>
<section anchor="request.target" title="Request Target"> <section anchor="request.target" title="Request Target">
<iref primary="true" item="request-target"/> <iref primary="true" item="request-target"/>
<t> <t>
The request-target identifies the target resource upon which to apply the The request-target identifies the target resource upon which to apply the
request. The client derives a request-target from its desired target URI. request. The client derives a request-target from its desired target URI.
There are four distinct formats for the request-target, depending on both There are four distinct formats for the request-target, depending on both
the method being requested and whether the request is to a proxy. the method being requested and whether the request is to a proxy.
</t> </t>
<iref primary="true" item="Grammar" subitem="request-target"/> <iref primary="true" item="Grammar" subitem="request-target"/>
<iref primary="false" item="Grammar" subitem="origin-form"/> <iref primary="false" item="Grammar" subitem="origin-form"/>
<iref primary="false" item="Grammar" subitem="absolute-form"/> <iref primary="false" item="Grammar" subitem="absolute-form"/>
<iref primary="false" item="Grammar" subitem="authority-form"/> <iref primary="false" item="Grammar" subitem="authority-form"/>
<iref primary="false" item="Grammar" subitem="asterisk-form"/> <iref primary="false" item="Grammar" subitem="asterisk-form"/>
<sourcecode type="abnf7230"><![CDATA[ request-target = origin-form <sourcecode type="abnf9110"><![CDATA[ request-target = origin-form
/ absolute-form / absolute-form
/ authority-form / authority-form
/ asterisk-form / asterisk-form
]]></sourcecode> ]]></sourcecode>
<t> <t>
No whitespace is allowed in the request-target. No whitespace is allowed in the request-target.
Unfortunately, some user agents fail to properly encode or exclude Unfortunately, some user agents fail to properly encode or exclude
whitespace found in hypertext references, resulting in those disallowed whitespace found in hypertext references, resulting in those disallowed
characters being sent as the request-target in a malformed request-line. characters being sent as the request-target in a malformed request-line.
</t> </t>
<t> <t>
Recipients of an invalid request-line <bcp14>SHOULD</bcp14> respond with eith er a Recipients of an invalid request-line <bcp14>SHOULD</bcp14> respond with eith er a
400 (Bad Request) error or a 301 (Moved Permanently) 400 (Bad Request) error or a 301 (Moved Permanently)
redirect with the request-target properly encoded. A recipient <bcp14>SHOULD NOT</bcp14> redirect with the request-target properly encoded. A recipient <bcp14>SHOULD NOT</bcp14>
attempt to autocorrect and then process the request without a redirect, attempt to autocorrect and then process the request without a redirect,
since the invalid request-line might be deliberately crafted to bypass since the invalid request-line might be deliberately crafted to bypass
security filters along the request chain. security filters along the request chain.
</t> </t>
<t> <t>
A client <bcp14>MUST</bcp14> send a Host header field (<xref target="HTTP" se ction="7.2"/>) A client <bcp14>MUST</bcp14> send a Host header field (<xref target="HTTP" se ction="7.2"/>)
in all HTTP/1.1 request messages. in all HTTP/1.1 request messages. If the target URI includes an authority com
If the target URI includes an authority component, then a client <bcp14>MUST< ponent, then a client <bcp14>MUST</bcp14>
/bcp14>
send a field value for Host that is identical to that authority send a field value for Host that is identical to that authority
component, excluding any userinfo subcomponent and its "@" delimiter component, excluding any userinfo subcomponent and its "@" delimiter
(<xref target="HTTP" section="4.2.1"/>). (<xref target="HTTP" section="4.2"/>).
If the authority component is missing or undefined for the target URI, If the authority component is missing or undefined for the target URI,
then a client <bcp14>MUST</bcp14> send a Host header field with an empty fiel d value. then a client <bcp14>MUST</bcp14> send a Host header field with an empty fiel d value.
</t> </t>
<t> <t>
A server <bcp14>MUST</bcp14> respond with a 400 (Bad Request) status code A server <bcp14>MUST</bcp14> respond with a 400 (Bad Request) status code
to any HTTP/1.1 request message that lacks a Host header field and to any HTTP/1.1 request message that lacks a Host header field and
to any request message that contains more than one Host header field line to any request message that contains more than one Host header field line
or a Host header field with an invalid field value. or a Host header field with an invalid field value.
</t> </t>
<section anchor="origin-form" title="origin-form">
<iref item="origin-form (of request-target)"/> <section anchor="origin-form" title="origin-form">
<iref item="origin-form (of request-target)"/>
<t> <t>
The most common form of request-target is the <em>origin-form</em>. The most common form of request-target is the "origin-form".
</t> </t>
<iref primary="true" item="Grammar" subitem="origin-form"/> <iref primary="true" item="Grammar" subitem="origin-form"/>
<sourcecode type="abnf7230"><![CDATA[ origin-form = absolute- path [ "?" query ] <sourcecode type="abnf9110"><![CDATA[ origin-form = absolute- path [ "?" query ]
]]></sourcecode> ]]></sourcecode>
<t> <t>
When making a request directly to an origin server, other than a CONNECT When making a request directly to an origin server, other than a CONNECT
or server-wide OPTIONS request (as detailed below), or server-wide OPTIONS request (as detailed below),
a client <bcp14>MUST</bcp14> send only the absolute path and query components of a client <bcp14>MUST</bcp14> send only the absolute path and query components of
the target URI as the request-target. the target URI as the request-target.
If the target URI's path component is empty, the client <bcp14>MUST</bcp14> s end If the target URI's path component is empty, the client <bcp14>MUST</bcp14> s end
"/" as the path within the origin-form of request-target. "/" as the path within the origin-form of request-target.
A Host header field is also sent, as defined in A Host header field is also sent, as defined in
<xref target="HTTP" section="7.2"/>. <xref target="HTTP" section="7.2"/>.
</t> </t>
<t> <t>
For example, a client wishing to retrieve a representation of the resource For example, a client wishing to retrieve a representation of the resource
identified as identified as
</t> </t>
<artwork type="example"><![CDATA[ <artwork><![CDATA[
http://www.example.org/where?q=now http://www.example.org/where?q=now
]]></artwork> ]]></artwork>
<t> <t>
directly from the origin server would open (or reuse) a TCP connection directly from the origin server would open (or reuse) a TCP connection
to port 80 of the host "www.example.org" and send the lines: to port 80 of the host "www.example.org" and send the lines:
</t> </t>
<sourcecode type="http-message"><![CDATA[GET /where?q=now HTTP/1. 1 <sourcecode type="http-message"><![CDATA[GET /where?q=now HTTP/1. 1
Host: www.example.org Host: www.example.org
]]></sourcecode> ]]></sourcecode>
<t> <t>
followed by the remainder of the request message. followed by the remainder of the request message.
</t> </t>
</section> </section>
<section anchor="absolute-form" title="absolute-form"> <section anchor="absolute-form" title="absolute-form">
<iref item="absolute-form (of request-target)"/> <iref item="absolute-form (of request-target)"/>
<t> <t>
When making a request to a proxy, other than a CONNECT or server-wide When making a request to a proxy, other than a CONNECT or server-wide
OPTIONS request (as detailed below), a client <bcp14>MUST</bcp14> send the ta rget URI OPTIONS request (as detailed below), a client <bcp14>MUST</bcp14> send the ta rget URI
in <em>absolute-form</em> as the request-target. in "absolute-form" as the request-target.
</t> </t>
<iref primary="true" item="Grammar" subitem="absolute-form"/> <iref primary="true" item="Grammar" subitem="absolute-form"/>
<sourcecode type="abnf7230"><![CDATA[ absolute-form = absolute- URI <sourcecode type="abnf9110"><![CDATA[ absolute-form = absolute- URI
]]></sourcecode> ]]></sourcecode>
<t> <t>
The proxy is requested to either service that request from a valid cache, The proxy is requested to either service that request from a valid cache,
if possible, or make the same request on the client's behalf to either if possible, or make the same request on the client's behalf either to
the next inbound proxy server or directly to the origin server indicated the next inbound proxy server or directly to the origin server indicated
by the request-target. Requirements on such "forwarding" of messages are by the request-target. Requirements on such "forwarding" of messages are
defined in <xref target="HTTP" section="7.6"/>. defined in <xref target="HTTP" section="7.6"/>.
</t> </t>
<t> <t>
An example absolute-form of request-line would be: An example absolute-form of request-line would be:
</t> </t>
<sourcecode type="http-message"><![CDATA[GET http://www.example.o rg/pub/WWW/TheProject.html HTTP/1.1 <sourcecode type="http-message"><![CDATA[GET http://www.example.o rg/pub/WWW/TheProject.html HTTP/1.1
]]></sourcecode> ]]></sourcecode>
<t> <t>
skipping to change at line 578 skipping to change at line 559
empty Host header field will be sent in this case. empty Host header field will be sent in this case.
</t> </t>
<t> <t>
A server <bcp14>MUST</bcp14> accept the absolute-form in requests even though most A server <bcp14>MUST</bcp14> accept the absolute-form in requests even though most
HTTP/1.1 clients will only send the absolute-form to a proxy. HTTP/1.1 clients will only send the absolute-form to a proxy.
</t> </t>
</section> </section>
<section anchor="authority-form" title="authority-form"> <section anchor="authority-form" title="authority-form">
<iref item="authority-form (of request-target)"/> <iref item="authority-form (of request-target)"/>
<t> <t>
The <em>authority-form</em> of request-target is only used for The "authority-form" of request-target is only used for
CONNECT requests (<xref target="HTTP" section="9.3.6"/>). It consists of only the CONNECT requests (<xref target="HTTP" section="9.3.6"/>). It consists of only the
uri-host and port number of the tunnel uri-host and port number of the tunnel
destination, separated by a colon (":"). destination, separated by a colon (":").
</t> </t>
<iref primary="true" item="Grammar" subitem="authority-form"/> <iref primary="true" item="Grammar" subitem="authority-form"/>
<sourcecode type="abnf7230"><![CDATA[ authority-form = uri-host ":" port <sourcecode type="abnf9110"><![CDATA[ authority-form = uri-host ":" port
]]></sourcecode> ]]></sourcecode>
<t> <t>
When making a CONNECT request to establish a tunnel through one or more When making a CONNECT request to establish a tunnel through one or more
proxies, a client <bcp14>MUST</bcp14> send only the host and port of the tunn el proxies, a client <bcp14>MUST</bcp14> send only the host and port of the tunn el
destination as the request-target. The client obtains the host and port destination as the request-target. The client obtains the host and port
from the target URI's <xref target="imported.uri.rules" format="none">authori ty</xref> component, except that it from the target URI's <xref target="imported.uri.rules" format="none">authori ty</xref> component, except that it
sends the scheme's default port if the target URI elides the port. sends the scheme's default port if the target URI elides the port.
For example, a CONNECT request to "http://www.example.com" looks like For example, a CONNECT request to "http://www.example.com" looks like the fol lowing:
</t> </t>
<sourcecode type="http-message"><![CDATA[CONNECT www.example.com: 80 HTTP/1.1 <sourcecode type="http-message"><![CDATA[CONNECT www.example.com: 80 HTTP/1.1
Host: www.example.com Host: www.example.com
]]></sourcecode> ]]></sourcecode>
</section> </section>
<section anchor="asterisk-form" title="asterisk-form"> <section anchor="asterisk-form" title="asterisk-form">
<iref item="asterisk-form (of request-target)"/> <iref item="asterisk-form (of request-target)"/>
<t> <t>
The <em>asterisk-form</em> of request-target is only used for a server-wide The "asterisk-form" of request-target is only used for a server-wide
OPTIONS request (<xref target="HTTP" section="9.3.7"/>). OPTIONS request (<xref target="HTTP" section="9.3.7"/>).
</t> </t>
<iref primary="true" item="Grammar" subitem="asterisk-form"/> <iref primary="true" item="Grammar" subitem="asterisk-form"/>
<sourcecode type="abnf7230"><![CDATA[ asterisk-form = "*" <sourcecode type="abnf9110"><![CDATA[ asterisk-form = "*"
]]></sourcecode> ]]></sourcecode>
<t> <t>
When a client wishes to request OPTIONS When a client wishes to request OPTIONS
for the server as a whole, as opposed to a specific named resource of for the server as a whole, as opposed to a specific named resource of
that server, the client <bcp14>MUST</bcp14> send only "*" (%x2A) as the reque st-target. that server, the client <bcp14>MUST</bcp14> send only "*" (%x2A) as the reque st-target.
For example, For example,
</t> </t>
<sourcecode type="http-message"><![CDATA[OPTIONS * HTTP/1.1 <sourcecode type="http-message"><![CDATA[OPTIONS * HTTP/1.1
]]></sourcecode> ]]></sourcecode>
<t> <t>
skipping to change at line 683 skipping to change at line 664
Otherwise, the target URI's combined path and Otherwise, the target URI's combined path and
<xref target="imported.uri.rules" format="none">query</xref> component is the request-target. <xref target="imported.uri.rules" format="none">query</xref> component is the request-target.
</li> </li>
<li> <li>
The components of a reconstructed target URI, once determined as above, The components of a reconstructed target URI, once determined as above,
can be recombined into <xref target="imported.uri.rules" format="none">absolu te-URI</xref> form by concatenating can be recombined into <xref target="imported.uri.rules" format="none">absolu te-URI</xref> form by concatenating
the scheme, "://", authority, and combined path and query component. the scheme, "://", authority, and combined path and query component.
</li> </li>
</ul> </ul>
<t> <t>
Example 1: the following message received over a secure connection Example 1: The following message received over a secure connection
</t> </t>
<sourcecode type="http-message"><![CDATA[GET /pub/WWW/TheProject.htm l HTTP/1.1 <sourcecode type="http-message"><![CDATA[GET /pub/WWW/TheProject.htm l HTTP/1.1
Host: www.example.org Host: www.example.org
]]></sourcecode> ]]></sourcecode>
<t> <t>
has a target URI of has a target URI of
</t> </t>
<artwork type="example"><![CDATA[ <artwork><![CDATA[
https://www.example.org/pub/WWW/TheProject.html https://www.example.org/pub/WWW/TheProject.html
]]></artwork> ]]></artwork>
<t> <t>
Example 2: the following message received over an insecure connection Example 2: The following message received over an insecure connection
</t> </t>
<sourcecode type="http-message"><![CDATA[OPTIONS * HTTP/1.1 <sourcecode type="http-message"><![CDATA[OPTIONS * HTTP/1.1
Host: www.example.org:8080 Host: www.example.org:8080
]]></sourcecode> ]]></sourcecode>
<t> <t>
has a target URI of has a target URI of
</t> </t>
<artwork type="example"><![CDATA[ <artwork><![CDATA[
http://www.example.org:8080 http://www.example.org:8080
]]></artwork> ]]></artwork>
<t> <t>
If the target URI's authority component is empty and its URI scheme If the target URI's authority component is empty and its URI scheme
requires a non-empty authority (as is the case for "http" and "https"), requires a non-empty authority (as is the case for "http" and "https"),
the server can reject the request or determine whether a configured the server can reject the request or determine whether a configured
default applies that is consistent with the incoming connection's context. default applies that is consistent with the incoming connection's context.
Context might include connection details like address and port, what Context might include connection details like address and port, what
security has been applied, and locally-defined information specific to security has been applied, and locally defined information specific to
that server's configuration. An empty authority is replaced with the that server's configuration. An empty authority is replaced with the
configured default before further processing of the request. configured default before further processing of the request.
</t> </t>
<t> <t>
Supplying a default name for authority within the context of a secured Supplying a default name for authority within the context of a secured
connection is inherently unsafe if there is any chance that the user connection is inherently unsafe if there is any chance that the user
agent's intended authority might differ from the default. agent's intended authority might differ from the default.
A server that can uniquely identify an authority from the request A server that can uniquely identify an authority from the request
context <bcp14>MAY</bcp14> use that identity as a default without this risk. context <bcp14>MAY</bcp14> use that identity as a default without this risk.
Alternatively, it might be better to redirect the request to a safe Alternatively, it might be better to redirect the request to a safe
skipping to change at line 735 skipping to change at line 716
<t> <t>
Note that reconstructing the client's target URI is only half of the Note that reconstructing the client's target URI is only half of the
process for identifying a target resource. The other half is determining process for identifying a target resource. The other half is determining
whether that target URI identifies a resource for which the server is whether that target URI identifies a resource for which the server is
willing and able to send a response, as defined in willing and able to send a response, as defined in
<xref target="HTTP" section="7.4"/>. <xref target="HTTP" section="7.4"/>.
</t> </t>
</section> </section>
</section> </section>
<section anchor="status.line" title="Status Line"> <section anchor="status.line" title="Status Line">
<t> <t>
The first line of a response message is the status-line, consisting The first line of a response message is the status-line, consisting
of the protocol version, a space (SP), the status code, another space, of the protocol version, a space (SP), the status code, and another space
and ending with an <bcp14>OPTIONAL</bcp14> textual phrase describing the stat us code. and ending with an <bcp14>OPTIONAL</bcp14> textual phrase describing the stat us code.
</t> </t>
<iref primary="true" item="Grammar" subitem="status-line"/> <iref primary="true" item="Grammar" subitem="status-line"/>
<sourcecode type="abnf7230"><![CDATA[ status-line = HTTP-version SP st atus-code SP [reason-phrase] <sourcecode type="abnf9110"><![CDATA[ status-line = HTTP-version SP st atus-code SP [ reason-phrase ]
]]></sourcecode> ]]></sourcecode>
<t> <t>
Although the status-line grammar rule requires that each of the component Although the status-line grammar rule requires that each of the component
elements be separated by a single SP octet, recipients <bcp14>MAY</bcp14> ins tead parse elements be separated by a single SP octet, recipients <bcp14>MAY</bcp14> ins tead parse
on whitespace-delimited word boundaries and, aside from the line on whitespace-delimited word boundaries and, aside from the line
terminator, treat any form of whitespace as the SP separator while terminator, treat any form of whitespace as the SP separator while
ignoring preceding or trailing whitespace; such whitespace includes one or ignoring preceding or trailing whitespace; such whitespace includes one or
more of the following octets: SP, HTAB, VT (%x0B), FF (%x0C), or bare CR. more of the following octets: SP, HTAB, VT (%x0B), FF (%x0C), or bare CR.
However, lenient parsing can result in response splitting security However, lenient parsing can result in response splitting security
vulnerabilities if there are multiple recipients of the message and each vulnerabilities if there are multiple recipients of the message and each
skipping to change at line 765 skipping to change at line 747
<t> <t>
The status-code element is a 3-digit integer code describing the The status-code element is a 3-digit integer code describing the
result of the server's attempt to understand and satisfy the client's result of the server's attempt to understand and satisfy the client's
corresponding request. A recipient parses and interprets the remainder corresponding request. A recipient parses and interprets the remainder
of the response message in light of the semantics defined for that of the response message in light of the semantics defined for that
status code, if the status code is recognized by that recipient, status code, if the status code is recognized by that recipient,
or in accordance with the class of that status code when the specific or in accordance with the class of that status code when the specific
code is unrecognized. code is unrecognized.
</t> </t>
<iref primary="true" item="Grammar" subitem="status-code"/> <iref primary="true" item="Grammar" subitem="status-code"/>
<sourcecode type="abnf7230"><![CDATA[ status-code = 3DIGIT <sourcecode type="abnf9110"><![CDATA[ status-code = 3DIGIT
]]></sourcecode> ]]></sourcecode>
<t> <t>
HTTP's core status codes are defined in <xref target="HTTP" section="15"/>, HTTP's core status codes are defined in <xref target="HTTP" section="15"/>,
along with the classes of status codes, considerations for the along with the classes of status codes, considerations for the
definition of new status codes, and the IANA registry for collecting definition of new status codes, and the IANA registry for collecting
such definitions. such definitions.
</t> </t>
<t> <t>
The reason-phrase element exists for the sole purpose of providing a The reason-phrase element exists for the sole purpose of providing a
textual description associated with the numeric status code, mostly out of textual description associated with the numeric status code, mostly out of
deference to earlier Internet application protocols that were more deference to earlier Internet application protocols that were more
frequently used with interactive text clients. frequently used with interactive text clients.
</t> </t>
<iref primary="true" item="Grammar" subitem="reason-phrase"/> <iref primary="true" item="Grammar" subitem="reason-phrase"/>
<sourcecode type="abnf7230"><![CDATA[ reason-phrase = 1*( HTAB / SP / VCHAR / obs-text ) <sourcecode type="abnf9110"><![CDATA[ reason-phrase = 1*( HTAB / SP / VCHAR / obs-text )
]]></sourcecode> ]]></sourcecode>
<t> <t>
A client <bcp14>SHOULD</bcp14> ignore the reason-phrase content because it is not a A client <bcp14>SHOULD</bcp14> ignore the reason-phrase content because it is not a
reliable channel for information (it might be translated for a given locale, reliable channel for information (it might be translated for a given locale,
overwritten by intermediaries, or discarded when the message is forwarded overwritten by intermediaries, or discarded when the message is forwarded
via other versions of HTTP). via other versions of HTTP).
A server <bcp14>MUST</bcp14> send the space that separates status-code from t he A server <bcp14>MUST</bcp14> send the space that separates the status-code fr om the
reason-phrase even when the reason-phrase is absent (i.e., the status-line reason-phrase even when the reason-phrase is absent (i.e., the status-line
would end with the three octets SP CR LF). would end with the space).
</t> </t>
</section> </section>
<section anchor="header.field.syntax" title="Field Syntax"> <section anchor="header.field.syntax" title="Field Syntax">
<t> <t>
Each field line consists of a case-insensitive field name Each field line consists of a case-insensitive field name
followed by a colon (":"), optional leading whitespace, the field line value, followed by a colon (":"), optional leading whitespace, the field line value,
and optional trailing whitespace. and optional trailing whitespace.
</t> </t>
<iref primary="true" item="Grammar" subitem="field-line"/> <iref primary="true" item="Grammar" subitem="field-line"/>
<iref primary="false" item="Grammar" subitem="field-name"/> <iref primary="false" item="Grammar" subitem="field-name"/>
<iref primary="false" item="Grammar" subitem="field-value"/> <iref primary="false" item="Grammar" subitem="field-value"/>
<sourcecode type="abnf7230"><![CDATA[ field-line = field-name ":" OW S field-value OWS <sourcecode type="abnf9110"><![CDATA[ field-line = field-name ":" OW S field-value OWS
]]></sourcecode> ]]></sourcecode>
<t> <t>
Most HTTP field names and the rules for parsing within field values are Rules for parsing within field values are
defined in <xref target="HTTP" section="6.3"/>. This section covers the defined in <xref target="HTTP" section="5.5"/>. This section covers the
generic syntax for header field inclusion within, and extraction from, generic syntax for header field inclusion within, and extraction from,
HTTP/1.1 messages. HTTP/1.1 messages.
</t> </t>
<section anchor="field.parsing" title="Field Line Parsing"> <section anchor="field.parsing" title="Field Line Parsing">
<t> <t>
Messages are parsed using a generic algorithm, independent of the Messages are parsed using a generic algorithm, independent of the
individual field names. The contents within a given field line value are individual field names. The contents within a given field line value are
not parsed until a later stage of message interpretation (usually after the not parsed until a later stage of message interpretation (usually after the
message's entire field section has been processed). message's entire field section has been processed).
</t> </t>
skipping to change at line 841 skipping to change at line 823
occurring before the first non-whitespace octet of the field line value, occurring before the first non-whitespace octet of the field line value,
or after the last non-whitespace octet of the field line value, is excluded b y or after the last non-whitespace octet of the field line value, is excluded b y
parsers when extracting the field line value from a field line. parsers when extracting the field line value from a field line.
</t> </t>
</section> </section>
<section anchor="line.folding" title="Obsolete Line Folding"> <section anchor="line.folding" title="Obsolete Line Folding">
<t> <t>
Historically, HTTP/1.x field values could be extended over multiple Historically, HTTP/1.x field values could be extended over multiple
lines by preceding each extra line with at least one space or horizontal lines by preceding each extra line with at least one space or horizontal
tab (obs-fold). This specification deprecates such line folding except tab (obs-fold). This specification deprecates such line folding except
within the message/http media type within the "message/http" media type
(<xref target="media.type.message.http"/>). (<xref target="media.type.message.http"/>).
</t> </t>
<iref primary="true" item="Grammar" subitem="obs-fold"/> <iref primary="true" item="Grammar" subitem="obs-fold"/>
<sourcecode type="abnf7230"><![CDATA[ obs-fold = OWS CRLF RWS <sourcecode type="abnf9110"><![CDATA[ obs-fold = OWS CRLF RWS
; obsolete line folding ; obsolete line folding
]]></sourcecode> ]]></sourcecode>
<t> <t>
A sender <bcp14>MUST NOT</bcp14> generate a message that includes line foldin g A sender <bcp14>MUST NOT</bcp14> generate a message that includes line foldin g
(i.e., that has any field line value that contains a match to the (i.e., that has any field line value that contains a match to the
<xref target="line.folding" format="none">obs-fold</xref> rule) unless the me ssage is intended for packaging <xref target="line.folding" format="none">obs-fold</xref> rule) unless the me ssage is intended for packaging
within the message/http media type. within the "message/http" media type.
</t> </t>
<t> <t>
A server that receives an <xref target="line.folding" format="none">obs-fold< /xref> in a request message that A server that receives an <xref target="line.folding" format="none">obs-fold< /xref> in a request message that
is not within a message/http container <bcp14>MUST</bcp14> either reject the message by is not within a "message/http" container <bcp14>MUST</bcp14> either reject th e message by
sending a 400 (Bad Request), preferably with a sending a 400 (Bad Request), preferably with a
representation explaining that obsolete line folding is unacceptable, or representation explaining that obsolete line folding is unacceptable, or
replace each received <xref target="line.folding" format="none">obs-fold</xre f> with one or more replace each received <xref target="line.folding" format="none">obs-fold</xre f> with one or more
<xref target="core.rules" format="none">SP</xref> octets prior to interpretin g the field value or <xref target="core.rules" format="none">SP</xref> octets prior to interpretin g the field value or
forwarding the message downstream. forwarding the message downstream.
</t> </t>
<t> <t>
A proxy or gateway that receives an <xref target="line.folding" format="none" >obs-fold</xref> in a response A proxy or gateway that receives an <xref target="line.folding" format="none" >obs-fold</xref> in a response
message that is not within a message/http container <bcp14>MUST</bcp14> eithe r discard message that is not within a "message/http" container <bcp14>MUST</bcp14> eit her discard
the message and replace it with a 502 (Bad Gateway) the message and replace it with a 502 (Bad Gateway)
response, preferably with a representation explaining that unacceptable response, preferably with a representation explaining that unacceptable
line folding was received, or replace each received <xref target="line.foldin g" format="none">obs-fold</xref> line folding was received, or replace each received <xref target="line.foldin g" format="none">obs-fold</xref>
with one or more <xref target="core.rules" format="none">SP</xref> octets pri or to interpreting the field with one or more <xref target="core.rules" format="none">SP</xref> octets pri or to interpreting the field
value or forwarding the message downstream. value or forwarding the message downstream.
</t> </t>
<t> <t>
A user agent that receives an <xref target="line.folding" format="none">obs-f old</xref> in a response message A user agent that receives an <xref target="line.folding" format="none">obs-f old</xref> in a response message
that is not within a message/http container <bcp14>MUST</bcp14> replace each received that is not within a "message/http" container <bcp14>MUST</bcp14> replace eac h received
<xref target="line.folding" format="none">obs-fold</xref> with one or more <x ref target="core.rules" format="none">SP</xref> octets prior to <xref target="line.folding" format="none">obs-fold</xref> with one or more <x ref target="core.rules" format="none">SP</xref> octets prior to
interpreting the field value. interpreting the field value.
</t> </t>
</section> </section>
</section> </section>
<section anchor="message.body" title="Message Body"> <section anchor="message.body" title="Message Body">
<t> <t>
The message body (if any) of an HTTP/1.1 message is used to carry content The message body (if any) of an HTTP/1.1 message is used to carry content
(<xref target="HTTP" section="6.4"/>) for the request or response. The (<xref target="HTTP" section="6.4"/>) for the request or response. The
message body is identical to the content unless a transfer coding has message body is identical to the content unless a transfer coding has
been applied, as described in <xref target="field.transfer-encoding"/>. been applied, as described in <xref target="field.transfer-encoding"/>.
</t> </t>
<iref primary="true" item="Grammar" subitem="message-body"/> <iref primary="true" item="Grammar" subitem="message-body"/>
<sourcecode type="abnf7230"><![CDATA[ message-body = *OCTET <sourcecode type="abnf9110"><![CDATA[ message-body = *OCTET
]]></sourcecode> ]]></sourcecode>
<t> <t>
The rules for determining when a message body is present in an HTTP/1.1 The rules for determining when a message body is present in an HTTP/1.1
message differ for requests and responses. message differ for requests and responses.
</t> </t>
<t> <t>
The presence of a message body in a request is signaled by a The presence of a message body in a request is signaled by a
<xref target="body.content-length" format="none">Content-Length</xref> or <xr ef target="field.transfer-encoding" format="none">Transfer-Encoding</xref> heade r <xref target="body.content-length" format="none">Content-Length</xref> or <xr ef target="field.transfer-encoding" format="none">Transfer-Encoding</xref> heade r
field. Request message framing is independent of method semantics. field. Request message framing is independent of method semantics.
</t> </t>
<t> <t>
The presence of a message body in a response depends on both the request The presence of a message body in a response, as detailed in
method to which it is responding and the response status code (<xref target=" <xref target="message.body.length"/>, depends on both the request
status.line"/>), and corresponds to when content is method to which it is responding and the response status code.
allowed; see <xref target="HTTP" section="6.4"/>. This corresponds to when response content is
allowed by HTTP semantics (<xref target="HTTP" section="6.4.1"/>).
</t> </t>
<section anchor="field.transfer-encoding" title="Transfer-Encoding"> <section anchor="field.transfer-encoding" title="Transfer-Encoding">
<iref primary="true" item="Fields" subitem="Transfer-Encoding"/> <iref primary="true" item="Fields" subitem="Transfer-Encoding"/>
<iref primary="true" item="Header Fields" subitem="Transfer-Encoding "/> <iref primary="true" item="Header Fields" subitem="Transfer-Encoding "/>
<iref primary="true" item="Transfer-Encoding header field"/> <iref primary="true" item="Transfer-Encoding header field"/>
<iref item="chunked (Coding Format)"/> <iref item="chunked (Coding Format)"/>
<t> <t>
The Transfer-Encoding header field lists the transfer coding names The Transfer-Encoding header field lists the transfer coding names
corresponding to the sequence of transfer codings that have been corresponding to the sequence of transfer codings that have been
(or will be) applied to the content in order to form the message body. (or will be) applied to the content in order to form the message body.
Transfer codings are defined in <xref target="transfer.codings"/>. Transfer codings are defined in <xref target="transfer.codings"/>.
</t> </t>
<iref primary="true" item="Grammar" subitem="Transfer-Encoding"/> <iref primary="true" item="Grammar" subitem="Transfer-Encoding"/>
<sourcecode type="abnf7230"><![CDATA[ Transfer-Encoding = #transfer -coding <sourcecode type="abnf9110"><![CDATA[ Transfer-Encoding = #transfer -coding
; defined in [HTTP], Section 10.1.4 ; defined in [HTTP], Section 10.1.4
]]></sourcecode> ]]></sourcecode>
<t> <t>
Transfer-Encoding is analogous to the Content-Transfer-Encoding field of Transfer-Encoding is analogous to the Content-Transfer-Encoding field of
MIME, which was designed to enable safe transport of binary data over a MIME, which was designed to enable safe transport of binary data over a
7-bit transport service (<xref target="RFC2045" sectionFormat="comma" section ="6"/>). 7-bit transport service (<xref target="RFC2045" sectionFormat="comma" section ="6"/>).
However, safe transport has a different focus for an 8bit-clean transfer However, safe transport has a different focus for an 8bit-clean transfer
protocol. In HTTP's case, Transfer-Encoding is primarily intended to protocol. In HTTP's case, Transfer-Encoding is primarily intended to
accurately delimit dynamically generated content. It also serves to accurately delimit dynamically generated content. It also serves to
distinguish encodings that are only applied in transit from the encodings distinguish encodings that are only applied in transit from the encodings
skipping to change at line 954 skipping to change at line 938
</t> </t>
<sourcecode type="http-message"><![CDATA[Transfer-Encoding: gzip, ch unked <sourcecode type="http-message"><![CDATA[Transfer-Encoding: gzip, ch unked
]]></sourcecode> ]]></sourcecode>
<t> <t>
indicates that the content has been compressed using the gzip indicates that the content has been compressed using the gzip
coding and then chunked using the chunked coding while forming the coding and then chunked using the chunked coding while forming the
message body. message body.
</t> </t>
<t> <t>
Unlike Content-Encoding (<xref target="HTTP" section="8.4.1"/>), Unlike Content-Encoding (<xref target="HTTP" section="8.4.1"/>),
Transfer-Encoding is a property of the message, not of the representation, an Transfer-Encoding is a property of the message, not of the representation.
d Any recipient along the request/response chain <bcp14>MAY</bcp14> decode the
any recipient along the request/response chain <bcp14>MAY</bcp14> decode the received
received
transfer coding(s) or apply additional transfer coding(s) to the message transfer coding(s) or apply additional transfer coding(s) to the message
body, assuming that corresponding changes are made to the Transfer-Encoding body, assuming that corresponding changes are made to the Transfer-Encoding
field value. Additional information about the encoding parameters can be field value. Additional information about the encoding parameters can be
provided by other header fields not defined by this specification. provided by other header fields not defined by this specification.
</t> </t>
<t> <t>
Transfer-Encoding <bcp14>MAY</bcp14> be sent in a response to a HEAD request or in a Transfer-Encoding <bcp14>MAY</bcp14> be sent in a response to a HEAD request or in a
304 (Not Modified) response (<xref target="HTTP" section="15.4.5"/>) to a GET request, 304 (Not Modified) response (<xref target="HTTP" section="15.4.5"/>) to a GET request,
neither of which includes a message body, neither of which includes a message body,
to indicate that the origin server would have applied a transfer coding to indicate that the origin server would have applied a transfer coding
skipping to change at line 987 skipping to change at line 971
</t> </t>
<t> <t>
A server that receives a request message with a transfer coding it does A server that receives a request message with a transfer coding it does
not understand <bcp14>SHOULD</bcp14> respond with 501 (Not Implemented). not understand <bcp14>SHOULD</bcp14> respond with 501 (Not Implemented).
</t> </t>
<t> <t>
Transfer-Encoding was added in HTTP/1.1. It is generally assumed that Transfer-Encoding was added in HTTP/1.1. It is generally assumed that
implementations advertising only HTTP/1.0 support will not understand implementations advertising only HTTP/1.0 support will not understand
how to process transfer-encoded content, and that an HTTP/1.0 message how to process transfer-encoded content, and that an HTTP/1.0 message
received with a Transfer-Encoding is likely to have been forwarded received with a Transfer-Encoding is likely to have been forwarded
without proper handling of the chunked encoding in transit. without proper handling of the chunked transfer coding in transit.
</t> </t>
<t> <t>
A client <bcp14>MUST NOT</bcp14> send a request containing Transfer-Encoding unless it A client <bcp14>MUST NOT</bcp14> send a request containing Transfer-Encoding unless it
knows the server will handle HTTP/1.1 requests (or later minor revisions); knows the server will handle HTTP/1.1 requests (or later minor revisions);
such knowledge might be in the form of specific user configuration or by such knowledge might be in the form of specific user configuration or by
remembering the version of a prior received response. remembering the version of a prior received response.
A server <bcp14>MUST NOT</bcp14> send a response containing Transfer-Encoding unless A server <bcp14>MUST NOT</bcp14> send a response containing Transfer-Encoding unless
the corresponding request indicates HTTP/1.1 (or later minor revisions). the corresponding request indicates HTTP/1.1 (or later minor revisions).
</t> </t>
<t> <t>
Early implementations of Transfer-Encoding would occasionally send both Early implementations of Transfer-Encoding would occasionally send both
a chunked encoding for message framing and an estimated Content-Length a chunked transfer coding for message framing and an estimated Content-Length
header field for use by progress bars. This is why Transfer-Encoding is header field for use by progress bars. This is why Transfer-Encoding is
defined as overriding Content-Length, as opposed to them being mutually defined as overriding Content-Length, as opposed to them being mutually
incompatible. Unfortunately, forwarding such a message can lead to incompatible. Unfortunately, forwarding such a message can lead to
vulnerabilities regarding vulnerabilities regarding
request smuggling (<xref target="request.smuggling"/>) or request smuggling (<xref target="request.smuggling"/>) or
response splitting (<xref target="response.splitting"/>) attacks response splitting (<xref target="response.splitting"/>) attacks
if any downstream recipient fails to parse the message according to this if any downstream recipient fails to parse the message according to this
specification, particularly when a downstream recipient only implements specification, particularly when a downstream recipient only implements
HTTP/1.0. HTTP/1.0.
</t> </t>
skipping to change at line 1040 skipping to change at line 1024
as a decimal number of octets, for potential content. as a decimal number of octets, for potential content.
For messages that do include content, the Content-Length field value For messages that do include content, the Content-Length field value
provides the framing information necessary for determining where the data provides the framing information necessary for determining where the data
(and message) ends. For messages that do not include content, the (and message) ends. For messages that do not include content, the
Content-Length indicates the size of the selected representation Content-Length indicates the size of the selected representation
(<xref target="HTTP" section="8.6"/>). (<xref target="HTTP" section="8.6"/>).
</t> </t>
<t> <t>
A sender <bcp14>MUST NOT</bcp14> send a Content-Length header field in any me ssage that A sender <bcp14>MUST NOT</bcp14> send a Content-Length header field in any me ssage that
contains a <xref target="field.transfer-encoding" format="none">Transfer-Enco ding</xref> header field. contains a <xref target="field.transfer-encoding" format="none">Transfer-Enco ding</xref> header field.
</t> </t>
<aside>
<t> <aside>
<strong>Note:</strong> HTTP's use of Content-Length for messag <t>
e framing differs <strong>Note:</strong> HTTP's use of Content-Length for message framing differs
significantly from the same field's use in MIME, where it is an optional significantly from the same field's use in MIME, where it is an optional
field used only within the "message/external-body" media-type. field used only within the "message/external-body" media-type.
</t> </t>
</aside> </aside>
</section> </section>
<section anchor="message.body.length" title="Message Body Length"> <section anchor="message.body.length" title="Message Body Length">
<iref item="chunked (Coding Format)"/> <iref item="chunked (Coding Format)"/>
<t> <t>
The length of a message body is determined by one of the following The length of a message body is determined by one of the following
(in order of precedence): (in order of precedence):
</t> </t>
<ol> <ol>
<li> <li>
<t>
Any response to a HEAD request and any response with a Any response to a HEAD request and any response with a
1xx (Informational), 204 (No Content), or 1xx (Informational), 204 (No Content), or
304 (Not Modified) status code is always 304 (Not Modified) status code is always
terminated by the first empty line after the header fields, regardless of terminated by the first empty line after the header fields, regardless of
the header fields present in the message, and thus cannot contain a the header fields present in the message, and thus cannot contain a
message body or trailer section. message body or trailer section.
</t>
</li> </li>
<li> <li>
<t>
Any 2xx (Successful) response to a CONNECT request implies that the Any 2xx (Successful) response to a CONNECT request implies that the
connection will become a tunnel immediately after the empty line that connection will become a tunnel immediately after the empty line that
concludes the header fields. A client <bcp14>MUST</bcp14> ignore any concludes the header fields. A client <bcp14>MUST</bcp14> ignore any
<xref target="body.content-length" format="none">Content-Length</xref> or <xr ef target="field.transfer-encoding" format="none">Transfer-Encoding</xref> heade r <xref target="body.content-length" format="none">Content-Length</xref> or <xr ef target="field.transfer-encoding" format="none">Transfer-Encoding</xref> heade r
fields received in such a message. fields received in such a message.
</t>
</li> </li>
<li> <li>
<t>
If a message is received with both a <xref target="field.transfer-encoding" f ormat="none">Transfer-Encoding</xref> If a message is received with both a <xref target="field.transfer-encoding" f ormat="none">Transfer-Encoding</xref>
and a <xref target="body.content-length" format="none">Content-Length</xref> header field, the Transfer-Encoding and a <xref target="body.content-length" format="none">Content-Length</xref> header field, the Transfer-Encoding
overrides the Content-Length. Such a message might indicate an attempt to overrides the Content-Length. Such a message might indicate an attempt to
perform request smuggling (<xref target="request.smuggling"/>) or perform request smuggling (<xref target="request.smuggling"/>) or
response splitting (<xref target="response.splitting"/>) and ought to be response splitting (<xref target="response.splitting"/>) and ought to be
handled as an error. handled as an error.
An intermediary that chooses to forward the message <bcp14>MUST</bcp14> first remove the An intermediary that chooses to forward the message <bcp14>MUST</bcp14> first remove the
received Content-Length field and process the Transfer-Encoding received Content-Length field and process the Transfer-Encoding
(as described below) prior to forwarding the message downstream. (as described below) prior to forwarding the message downstream.
</t>
</li> </li>
<li> <li>
<t> <t>
If a <xref target="field.transfer-encoding" format="none">Transfer-Encoding</ xref> header field is present If a <xref target="field.transfer-encoding" format="none">Transfer-Encoding</ xref> header field is present
and the chunked transfer coding (<xref target="chunked.encoding"/>) and the chunked transfer coding (<xref target="chunked.encoding"/>)
is the final encoding, the message body length is determined by reading is the final encoding, the message body length is determined by reading
and decoding the chunked data until the transfer coding indicates the and decoding the chunked data until the transfer coding indicates the
data is complete. data is complete.
</t> </t>
<t> <t>
If a <xref target="field.transfer-encoding" format="none">Transfer-Encoding</ xref> header field is present in a If a <xref target="field.transfer-encoding" format="none">Transfer-Encoding</ xref> header field is present in a
response and the chunked transfer coding is not the final encoding, the response and the chunked transfer coding is not the final encoding, the
message body length is determined by reading the connection until it is message body length is determined by reading the connection until it is
skipping to change at line 1111 skipping to change at line 1090
</t> </t>
<t> <t>
If a <xref target="field.transfer-encoding" format="none">Transfer-Encoding</ xref> header field is present in a request If a <xref target="field.transfer-encoding" format="none">Transfer-Encoding</ xref> header field is present in a request
and the chunked transfer coding is not the final encoding, the message body and the chunked transfer coding is not the final encoding, the message body
length cannot be determined reliably; the server <bcp14>MUST</bcp14> respond with length cannot be determined reliably; the server <bcp14>MUST</bcp14> respond with
the 400 (Bad Request) status code and then close the the 400 (Bad Request) status code and then close the
connection. connection.
</t> </t>
</li> </li>
<li> <li>
<t>
If a message is received without <xref target="field.transfer-encoding" forma t="none">Transfer-Encoding</xref> and with If a message is received without <xref target="field.transfer-encoding" forma t="none">Transfer-Encoding</xref> and with
an invalid <xref target="body.content-length" format="none">Content-Length</x ref> header field, then the message an invalid <xref target="body.content-length" format="none">Content-Length</x ref> header field, then the message
framing is invalid and the recipient <bcp14>MUST</bcp14> treat it as an unrec overable framing is invalid and the recipient <bcp14>MUST</bcp14> treat it as an unrec overable
error, unless the field value can be successfully parsed as a error, unless the field value can be successfully parsed as a
comma-separated list (<xref target="HTTP" section="5.6.1"/>), all values in t he comma-separated list (<xref target="HTTP" section="5.6.1"/>), all values in t he
list are valid, and all values in the list are the same (in which case the list are valid, and all values in the list are the same (in which case, the
message is processed with that single value used as the Content-Length field message is processed with that single value used as the Content-Length field
value). value).
If the unrecoverable error is in a request message, If the unrecoverable error is in a request message,
the server <bcp14>MUST</bcp14> respond with the server <bcp14>MUST</bcp14> respond with
a 400 (Bad Request) status code and then close the connection. a 400 (Bad Request) status code and then close the connection.
If it is in a response message received by a proxy, If it is in a response message received by a proxy,
the proxy <bcp14>MUST</bcp14> close the connection to the server, discard the received the proxy <bcp14>MUST</bcp14> close the connection to the server, discard the received
response, and send a 502 (Bad Gateway) response to the response, and send a 502 (Bad Gateway) response to the
client. client.
If it is in a response message received by a user agent, If it is in a response message received by a user agent,
the user agent <bcp14>MUST</bcp14> close the connection to the server and dis card the the user agent <bcp14>MUST</bcp14> close the connection to the server and dis card the
received response. received response.
</t>
</li> </li>
<li> <li>
<t>
If a valid <xref target="body.content-length" format="none">Content-Length</x ref> header field is present without If a valid <xref target="body.content-length" format="none">Content-Length</x ref> header field is present without
<xref target="field.transfer-encoding" format="none">Transfer-Encoding</xref> , its decimal value defines the <xref target="field.transfer-encoding" format="none">Transfer-Encoding</xref> , its decimal value defines the
expected message body length in octets. expected message body length in octets.
If the sender closes the connection or the recipient times out before the If the sender closes the connection or the recipient times out before the
indicated number of octets are received, the recipient <bcp14>MUST</bcp14> co nsider indicated number of octets are received, the recipient <bcp14>MUST</bcp14> co nsider
the message to be incomplete and close the connection. the message to be incomplete and close the connection.
</t>
</li> </li>
<li> <li>
<t>
If this is a request message and none of the above are true, then the If this is a request message and none of the above are true, then the
message body length is zero (no message body is present). message body length is zero (no message body is present).
</t>
</li> </li>
<li> <li>
<t>
Otherwise, this is a response message without a declared message body Otherwise, this is a response message without a declared message body
length, so the message body length is determined by the number of octets length, so the message body length is determined by the number of octets
received prior to the server closing the connection. received prior to the server closing the connection.
</t>
</li> </li>
</ol> </ol>
<t> <t>
Since there is no way to distinguish a successfully completed, Since there is no way to distinguish a successfully completed,
close-delimited response message from a partially received message interrupte d close-delimited response message from a partially received message interrupte d
by network failure, a server <bcp14>SHOULD</bcp14> generate encoding or by network failure, a server <bcp14>SHOULD</bcp14> generate encoding or
length-delimited messages whenever possible. The close-delimiting length-delimited messages whenever possible. The close-delimiting
feature exists primarily for backwards compatibility with HTTP/1.0. feature exists primarily for backwards compatibility with HTTP/1.0.
</t> </t>
<aside> <aside>
<t> <t>
<strong>Note:</strong> Request messages are never close-delimi <strong>Note:</strong> Request messages are never close-delimited because they a
ted because they are always re always
explicitly framed by length or transfer coding, with the absence of both im plying explicitly framed by length or transfer coding, with the absence of both im plying
the request ends immediately after the header section. the request ends immediately after the header section.
</t> </t>
</aside> </aside>
<t> <t>
A server <bcp14>MAY</bcp14> reject a request that contains a message body but A server <bcp14>MAY</bcp14> reject a request that contains a message body but
not a <xref target="body.content-length" format="none">Content-Length</xref> by responding with not a <xref target="body.content-length" format="none">Content-Length</xref> by responding with
411 (Length Required). 411 (Length Required).
</t> </t>
<t> <t>
Unless a transfer coding other than chunked has been applied, Unless a transfer coding other than chunked has been applied,
a client that sends a request containing a message body <bcp14>SHOULD</bcp14> a client that sends a request containing a message body <bcp14>SHOULD</bcp14>
use a valid <xref target="body.content-length" format="none">Content-Length</ xref> header field if the message body use a valid <xref target="body.content-length" format="none">Content-Length</ xref> header field if the message body
length is known in advance, rather than the chunked transfer coding, since so me length is known in advance, rather than the chunked transfer coding, since so me
existing services respond to chunked with a 411 (Length Required) existing services respond to chunked with a 411 (Length Required)
status code even though they understand the chunked transfer coding. This status code even though they understand the chunked transfer coding. This
is typically because such services are implemented via a gateway that is typically because such services are implemented via a gateway that
requires a content-length in advance of being called and the server requires a content length in advance of being called, and the server
is unable or unwilling to buffer the entire request before processing. is unable or unwilling to buffer the entire request before processing.
</t> </t>
<t> <t>
A user agent that sends a request that contains a message body <bcp14>MUST</b cp14> send A user agent that sends a request that contains a message body <bcp14>MUST</b cp14> send
either a valid <xref target="body.content-length" format="none">Content-Lengt h</xref> header field or use the either a valid <xref target="body.content-length" format="none">Content-Lengt h</xref> header field or use the
chunked transfer coding. A client <bcp14>MUST NOT</bcp14> use the chunked tra nsfer chunked transfer coding. A client <bcp14>MUST NOT</bcp14> use the chunked tra nsfer
encoding unless it knows the server will handle HTTP/1.1 (or later) coding unless it knows the server will handle HTTP/1.1 (or later)
requests; such knowledge can be in the form of specific user configuration requests; such knowledge can be in the form of specific user configuration
or by remembering the version of a prior received response. or by remembering the version of a prior received response.
</t> </t>
<t> <t>
If the final response to the last request on a connection has been If the final response to the last request on a connection has been
completely received and there remains additional data to read, a user agent completely received and there remains additional data to read, a user agent
<bcp14>MAY</bcp14> discard the remaining data or attempt to determine if that data <bcp14>MAY</bcp14> discard the remaining data or attempt to determine if that data
belongs as part of the prior message body, which might be the case if the belongs as part of the prior message body, which might be the case if the
prior message's Content-Length value is incorrect. A client <bcp14>MUST NOT</ bcp14> prior message's Content-Length value is incorrect. A client <bcp14>MUST NOT</ bcp14>
process, cache, or forward such extra data as a separate response, since process, cache, or forward such extra data as a separate response, since
skipping to change at line 1240 skipping to change at line 1211
buffers, which enables the sender to retain connection persistence and the buffers, which enables the sender to retain connection persistence and the
recipient to know when it has received the entire message. recipient to know when it has received the entire message.
</t> </t>
<iref primary="true" item="Grammar" subitem="chunked-body"/> <iref primary="true" item="Grammar" subitem="chunked-body"/>
<iref primary="true" item="Grammar" subitem="chunk"/> <iref primary="true" item="Grammar" subitem="chunk"/>
<iref primary="true" item="Grammar" subitem="chunk-size"/> <iref primary="true" item="Grammar" subitem="chunk-size"/>
<iref primary="true" item="Grammar" subitem="last-chunk"/> <iref primary="true" item="Grammar" subitem="last-chunk"/>
<iref primary="false" item="Grammar" subitem="trailer-section"/> <iref primary="false" item="Grammar" subitem="trailer-section"/>
<iref primary="false" item="Grammar" subitem="chunk-ext"/> <iref primary="false" item="Grammar" subitem="chunk-ext"/>
<iref primary="true" item="Grammar" subitem="chunk-data"/> <iref primary="true" item="Grammar" subitem="chunk-data"/>
<sourcecode type="abnf7230"><![CDATA[ chunked-body = *chunk <sourcecode type="abnf9110"><![CDATA[ chunked-body = *chunk
last-chunk last-chunk
trailer-section trailer-section
CRLF CRLF
chunk = chunk-size [ chunk-ext ] CRLF chunk = chunk-size [ chunk-ext ] CRLF
chunk-data CRLF chunk-data CRLF
chunk-size = 1*HEXDIG chunk-size = 1*HEXDIG
last-chunk = 1*("0") [ chunk-ext ] CRLF last-chunk = 1*("0") [ chunk-ext ] CRLF
chunk-data = 1*OCTET ; a sequence of chunk-size octets chunk-data = 1*OCTET ; a sequence of chunk-size octets
skipping to change at line 1272 skipping to change at line 1243
HTTP/1.1 does not define any means to limit the size of a HTTP/1.1 does not define any means to limit the size of a
chunked response such that an intermediary can be assured of buffering the chunked response such that an intermediary can be assured of buffering the
entire response. Additionally, very large chunk sizes may cause overflows entire response. Additionally, very large chunk sizes may cause overflows
or loss of precision if their values are not represented accurately in a or loss of precision if their values are not represented accurately in a
receiving implementation. Therefore, recipients <bcp14>MUST</bcp14> anticipat e receiving implementation. Therefore, recipients <bcp14>MUST</bcp14> anticipat e
potentially large hexadecimal numerals and prevent parsing errors due to potentially large hexadecimal numerals and prevent parsing errors due to
integer conversion overflows or precision loss due to integer integer conversion overflows or precision loss due to integer
representation. representation.
</t> </t>
<t> <t>
The chunked encoding does not define any parameters. Their presence The chunked coding does not define any parameters. Their presence
<bcp14>SHOULD</bcp14> be treated as an error. <bcp14>SHOULD</bcp14> be treated as an error.
</t> </t>
<section anchor="chunked.extension" title="Chunk Extensions"> <section anchor="chunked.extension" title="Chunk Extensions">
<t> <t>
The chunked encoding allows each chunk to include zero or more chunk The chunked coding allows each chunk to include zero or more chunk
extensions, immediately following the <xref target="chunked.encoding" format= "none">chunk-size</xref>, for the extensions, immediately following the <xref target="chunked.encoding" format= "none">chunk-size</xref>, for the
sake of supplying per-chunk metadata (such as a signature or hash), sake of supplying per-chunk metadata (such as a signature or hash),
mid-message control information, or randomization of message body size. mid-message control information, or randomization of message body size.
</t> </t>
<iref primary="true" item="Grammar" subitem="chunk-ext"/> <iref primary="true" item="Grammar" subitem="chunk-ext"/>
<iref primary="true" item="Grammar" subitem="chunk-ext-name"/> <iref primary="true" item="Grammar" subitem="chunk-ext-name"/>
<iref primary="true" item="Grammar" subitem="chunk-ext-val"/> <iref primary="true" item="Grammar" subitem="chunk-ext-val"/>
<sourcecode type="abnf7230"><![CDATA[ chunk-ext = *( BWS "; " BWS chunk-ext-name <sourcecode type="abnf9110"><![CDATA[ chunk-ext = *( BWS "; " BWS chunk-ext-name
[ BWS "=" BWS chunk-ext-val ] ) [ BWS "=" BWS chunk-ext-val ] )
chunk-ext-name = token chunk-ext-name = token
chunk-ext-val = token / quoted-string chunk-ext-val = token / quoted-string
]]></sourcecode> ]]></sourcecode>
<t> <t>
The chunked encoding is specific to each connection and is likely to be The chunked coding is specific to each connection and is likely to be
removed or recoded by each recipient (including intermediaries) before any removed or recoded by each recipient (including intermediaries) before any
higher-level application would have a chance to inspect the extensions. higher-level application would have a chance to inspect the extensions.
Hence, use of chunk extensions is generally limited to specialized HTTP Hence, the use of chunk extensions is generally limited to specialized HTTP
services such as "long polling" (where client and server can have shared services such as "long polling" (where client and server can have shared
expectations regarding the use of chunk extensions) or for padding within expectations regarding the use of chunk extensions) or for padding within
an end-to-end secured connection. an end-to-end secured connection.
</t> </t>
<t> <t>
A recipient <bcp14>MUST</bcp14> ignore unrecognized chunk extensions. A recipient <bcp14>MUST</bcp14> ignore unrecognized chunk extensions.
A server ought to limit the total length of chunk extensions received in a A server ought to limit the total length of chunk extensions received in a
request to an amount reasonable for the services provided, in the same way request to an amount reasonable for the services provided, in the same way
that it applies length limitations and timeouts for other parts of a that it applies length limitations and timeouts for other parts of a
message, and generate an appropriate 4xx (Client Error) message, and generate an appropriate 4xx (Client Error)
skipping to change at line 1319 skipping to change at line 1290
<section anchor="chunked.trailer.section" title="Chunked Trailer Sec tion"> <section anchor="chunked.trailer.section" title="Chunked Trailer Sec tion">
<t> <t>
A trailer section allows the sender to include additional fields at the end A trailer section allows the sender to include additional fields at the end
of a chunked message in order to supply metadata that might be dynamically of a chunked message in order to supply metadata that might be dynamically
generated while the content is sent, such as a message integrity generated while the content is sent, such as a message integrity
check, digital signature, or post-processing status. The proper use and check, digital signature, or post-processing status. The proper use and
limitations of trailer fields are defined in <xref target="HTTP" section="6.5 "/>. limitations of trailer fields are defined in <xref target="HTTP" section="6.5 "/>.
</t> </t>
<iref primary="true" item="Grammar" subitem="trailer-section"/> <iref primary="true" item="Grammar" subitem="trailer-section"/>
<iref primary="false" item="Grammar" subitem="field-line"/> <iref primary="false" item="Grammar" subitem="field-line"/>
<sourcecode type="abnf7230"><![CDATA[ trailer-section = *( fie ld-line CRLF ) <sourcecode type="abnf9110"><![CDATA[ trailer-section = *( fie ld-line CRLF )
]]></sourcecode> ]]></sourcecode>
<t> <t>
A recipient that removes the chunked encoding from a message <bcp14>MAY</bcp1 4> A recipient that removes the chunked coding from a message <bcp14>MAY</bcp14>
selectively retain or discard the received trailer fields. A recipient selectively retain or discard the received trailer fields. A recipient
that retains a received trailer field <bcp14>MUST</bcp14> either store/forwar d the that retains a received trailer field <bcp14>MUST</bcp14> either store/forwar d the
trailer field separately from the received header fields or merge the trailer field separately from the received header fields or merge the
received trailer field into the header section. received trailer field into the header section.
A recipient <bcp14>MUST NOT</bcp14> merge a received trailer field into the A recipient <bcp14>MUST NOT</bcp14> merge a received trailer field into the
header section unless its corresponding header field definition header section unless its corresponding header field definition
explicitly permits and instructs how the trailer field value can be explicitly permits and instructs how the trailer field value can be
safely merged. safely merged.
</t> </t>
</section> </section>
skipping to change at line 1410 skipping to change at line 1381
<li>Pointer to specification text</li> <li>Pointer to specification text</li>
</ul> </ul>
<t> <t>
Names of transfer codings <bcp14>MUST NOT</bcp14> overlap with names of conte nt codings Names of transfer codings <bcp14>MUST NOT</bcp14> overlap with names of conte nt codings
(<xref target="HTTP" section="8.4.1"/>) unless the encoding transformation is identical, as (<xref target="HTTP" section="8.4.1"/>) unless the encoding transformation is identical, as
is the case for the compression codings defined in is the case for the compression codings defined in
<xref target="compression.codings"/>. <xref target="compression.codings"/>.
</t> </t>
<t> <t>
The TE header field (<xref target="HTTP" section="10.1.4"/>) uses a The TE header field (<xref target="HTTP" section="10.1.4"/>) uses a
pseudo parameter named "q" as rank value when multiple transfer codings pseudo-parameter named "q" as the rank value when multiple transfer codings
are acceptable. Future registrations of transfer codings <bcp14>SHOULD NOT</b cp14> are acceptable. Future registrations of transfer codings <bcp14>SHOULD NOT</b cp14>
define parameters called "q" (case-insensitively) in order to avoid define parameters called "q" (case-insensitively) in order to avoid
ambiguities. ambiguities.
</t> </t>
<t> <t>
Values to be added to this namespace require IETF Review (see Values to be added to this namespace require IETF Review (see
<xref target="RFC8126" section="4.8"/>), and <bcp14>MUST</bcp14> <xref target="RFC8126" section="4.8"/>) and <bcp14>MUST</bcp14>
conform to the purpose of transfer coding defined in this specification. conform to the purpose of transfer coding defined in this specification.
</t> </t>
<t> <t>
Use of program names for the identification of encoding formats Use of program names for the identification of encoding formats
is not desirable and is discouraged for future encodings. is not desirable and is discouraged for future encodings.
</t> </t>
</section> </section>
<section anchor="transfer.coding.negotiation" <section anchor="transfer.coding.negotiation"
title="Negotiating Transfer Codings"> title="Negotiating Transfer Codings">
<t> <t>
The TE field (<xref target="HTTP" section="10.1.4"/>) is used in HTTP/1.1 to i ndicate The TE field (<xref target="HTTP" section="10.1.4"/>) is used in HTTP/1.1 to i ndicate
what transfer-codings, besides chunked, the client is willing to accept what transfer codings, besides chunked, the client is willing to accept
in the response, and whether the client is willing to preserve in the response and whether the client is willing to preserve
trailer fields in a chunked transfer coding. trailer fields in a chunked transfer coding.
</t> </t>
<t> <t>
A client <bcp14>MUST NOT</bcp14> send the chunked transfer coding name in TE; A client <bcp14>MUST NOT</bcp14> send the chunked transfer coding name in TE;
chunked is always acceptable for HTTP/1.1 recipients. chunked is always acceptable for HTTP/1.1 recipients.
</t> </t>
<t> <t>
Three examples of TE use are below. Three examples of TE use are below.
</t> </t>
<sourcecode type="http-message"><![CDATA[TE: deflate <sourcecode type="http-message"><![CDATA[TE: deflate
TE: TE:
TE: trailers, deflate;q=0.5 TE: trailers, deflate;q=0.5
]]></sourcecode> ]]></sourcecode>
<t> <t>
When multiple transfer codings are acceptable, the client <bcp14>MAY</bcp14> rank the When multiple transfer codings are acceptable, the client <bcp14>MAY</bcp14> rank the
codings by preference using a case-insensitive "q" parameter (similar to codings by preference using a case-insensitive "q" parameter (similar to
the qvalues used in content negotiation fields, <xref target="HTTP" section=" 12.4.2"/>). The rank value the qvalues used in content negotiation fields; see <xref target="HTTP" secti on="12.4.2"/>). The rank value
is a real number in the range 0 through 1, where 0.001 is the least is a real number in the range 0 through 1, where 0.001 is the least
preferred and 1 is the most preferred; a value of 0 means "not acceptable". preferred and 1 is the most preferred; a value of 0 means "not acceptable".
</t> </t>
<t> <t>
If the TE field value is empty or if no TE field is present, the only If the TE field value is empty or if no TE field is present, the only
acceptable transfer coding is chunked. A message with no transfer coding acceptable transfer coding is chunked. A message with no transfer coding
is always acceptable. is always acceptable.
</t> </t>
<t> <t>
The keyword "trailers" indicates that the sender will not discard trailer The keyword "trailers" indicates that the sender will not discard trailer
skipping to change at line 1475 skipping to change at line 1446
that do not support its semantics. that do not support its semantics.
</t> </t>
</section> </section>
</section> </section>
<section anchor="incomplete.messages" title="Handling Incomplete Messages" > <section anchor="incomplete.messages" title="Handling Incomplete Messages" >
<t> <t>
A server that receives an incomplete request message, usually due to a A server that receives an incomplete request message, usually due to a
canceled request or a triggered timeout exception, <bcp14>MAY</bcp14> send an error canceled request or a triggered timeout exception, <bcp14>MAY</bcp14> send an error
response prior to closing the connection. response prior to closing the connection.
</t> </t>
<t> <t>
A client that receives an incomplete response message, which can occur A client that receives an incomplete response message, which can occur
when a connection is closed prematurely or when decoding a supposedly when a connection is closed prematurely or when decoding a supposedly
chunked transfer coding fails, <bcp14>MUST</bcp14> record the message as inco mplete. chunked transfer coding fails, <bcp14>MUST</bcp14> record the message as inco mplete.
Cache requirements for incomplete responses are defined in Cache requirements for incomplete responses are defined in
<xref target="CACHING" section="3"/>. <xref target="CACHING" section="3.3"/>.
</t> </t>
<t> <t>
If a response terminates in the middle of the header section (before the If a response terminates in the middle of the header section (before the
empty line is received) and the status code might rely on header fields to empty line is received) and the status code might rely on header fields to
convey the full meaning of the response, then the client cannot assume convey the full meaning of the response, then the client cannot assume
that meaning has been conveyed; the client might need to repeat the that meaning has been conveyed; the client might need to repeat the
request in order to determine what action to take next. request in order to determine what action to take next.
</t> </t>
<t> <t>
A message body that uses the chunked transfer coding is A message body that uses the chunked transfer coding is
skipping to change at line 1547 skipping to change at line 1518
</t> </t>
</section> </section>
<section anchor="associating.response.to.request" <section anchor="associating.response.to.request"
title="Associating a Response to a Request"> title="Associating a Response to a Request">
<t> <t>
HTTP/1.1 does not include a request identifier for associating a given HTTP/1.1 does not include a request identifier for associating a given
request message with its corresponding one or more response messages. request message with its corresponding one or more response messages.
Hence, it relies on the order of response arrival to correspond exactly Hence, it relies on the order of response arrival to correspond exactly
to the order in which requests are made on the same connection. to the order in which requests are made on the same connection.
More than one response message per request only occurs when one or more More than one response message per request only occurs when one or more
informational responses (1xx, see <xref target="HTTP" section="15.2"/>) prece de a informational responses (1xx; see <xref target="HTTP" section="15.2"/>) prece de a
final response to the same request. final response to the same request.
</t> </t>
<t> <t>
A client that has more than one outstanding request on a connection <bcp14>MU ST</bcp14> A client that has more than one outstanding request on a connection <bcp14>MU ST</bcp14>
maintain a list of outstanding requests in the order sent and <bcp14>MUST</bc p14> maintain a list of outstanding requests in the order sent and <bcp14>MUST</bc p14>
associate each received response message on that connection to the associate each received response message on that connection to the
first outstanding request that has not yet received a final first outstanding request that has not yet received a final
(non-1xx) response. (non-1xx) response.
</t> </t>
<t> <t>
If a client receives data on a connection that doesn't have If a client receives data on a connection that doesn't have
outstanding requests, the client <bcp14>MUST NOT</bcp14> consider that data t o be a outstanding requests, the client <bcp14>MUST NOT</bcp14> consider that data t o be a
valid response; the client <bcp14>SHOULD</bcp14> close the connection, since message valid response; the client <bcp14>SHOULD</bcp14> close the connection, since message
delimitation is now ambiguous, unless the data consists only of one or delimitation is now ambiguous, unless the data consists only of one or
more CRLF (which can be discarded, as per more CRLF (which can be discarded per
<xref target="message.parsing"/>). <xref target="message.parsing"/>).
</t> </t>
</section> </section>
<section anchor="persistent.connections" title="Persistence"> <section anchor="persistent.connections" title="Persistence">
<iref primary="false" item="close"/> <iref primary="false" item="close"/>
<t> <t>
HTTP/1.1 defaults to the use of <em>persistent connections</em>, HTTP/1.1 defaults to the use of "persistent connections",
allowing multiple requests and responses to be carried over a single allowing multiple requests and responses to be carried over a single
connection. HTTP implementations <bcp14>SHOULD</bcp14> support persistent con nections. connection. HTTP implementations <bcp14>SHOULD</bcp14> support persistent con nections.
</t> </t>
<t> <t>
A recipient determines whether a connection is persistent or not based on A recipient determines whether a connection is persistent or not based on
the protocol version and Connection header field the protocol version and Connection header field
(<xref target="HTTP" section="7.6.1"/>) in the (<xref target="HTTP" section="7.6.1"/>) in the
most recently received message, if any: most recently received message, if any:
</t> </t>
<ul> <ul>
<li>If the <xref target="persistent.tear-down" format="none">clos e</xref> connection option is present <li>If the "<xref target="persistent.tear-down" format="none">clo se</xref>" connection option is present
(<xref target="persistent.tear-down"/>), the (<xref target="persistent.tear-down"/>), the
connection will not persist after the current response; else,</li> connection will not persist after the current response; else,</li>
<li>If the received protocol is HTTP/1.1 (or later), the connecti on will <li>If the received protocol is HTTP/1.1 (or later), the connecti on will
persist after the current response; else,</li> persist after the current response; else,</li>
<li>If the received protocol is HTTP/1.0, the "keep-alive" connec tion <li>If the received protocol is HTTP/1.0, the "keep-alive" connec tion
option is present, either the recipient is not a proxy or the option is present, either the recipient is not a proxy or the
message is a response, and the recipient wishes to honor the message is a response, and the recipient wishes to honor the
HTTP/1.0 "keep-alive" mechanism, the connection will persist after HTTP/1.0 "keep-alive" mechanism, the connection will persist after
the current response; otherwise,</li> the current response; otherwise,</li>
<li>The connection will close after the current response.</li> <li>The connection will close after the current response.</li>
</ul> </ul>
<t> <t>
A client that does not support <xref target="persistent.connections" format=" none">persistent connections</xref> A client that does not support <xref target="persistent.connections" format=" none">persistent connections</xref>
<bcp14>MUST</bcp14> <bcp14>MUST</bcp14>
send the <xref target="persistent.tear-down" format="none">close</xref> conne ction option in every request message. send the "<xref target="persistent.tear-down" format="none">close</xref>" con nection option in every request message.
</t> </t>
<t> <t>
A server that does not support <xref target="persistent.connections" format=" none">persistent connections</xref> A server that does not support <xref target="persistent.connections" format=" none">persistent connections</xref>
<bcp14>MUST</bcp14> <bcp14>MUST</bcp14>
send the <xref target="persistent.tear-down" format="none">close</xref> conne ction option in every response message send the "<xref target="persistent.tear-down" format="none">close</xref>" con nection option in every response message
that does not have a 1xx (Informational) status code. that does not have a 1xx (Informational) status code.
</t> </t>
<t> <t>
A client <bcp14>MAY</bcp14> send additional requests on a persistent connecti on until it A client <bcp14>MAY</bcp14> send additional requests on a persistent connecti on until it
sends or receives a <xref target="persistent.tear-down" format="none">close</ xref> connection option or receives an sends or receives a "<xref target="persistent.tear-down" format="none">close< /xref>" connection option or receives an
HTTP/1.0 response without a "keep-alive" connection option. HTTP/1.0 response without a "keep-alive" connection option.
</t> </t>
<t> <t>
In order to remain persistent, all messages on a connection need to In order to remain persistent, all messages on a connection need to
have a self-defined message length (i.e., one not defined by closure have a self-defined message length (i.e., one not defined by closure
of the connection), as described in <xref target="message.body"/>. of the connection), as described in <xref target="message.body"/>.
A server <bcp14>MUST</bcp14> read the entire request message body or close A server <bcp14>MUST</bcp14> read the entire request message body or close
the connection after sending its response, since otherwise the the connection after sending its response; otherwise, the
remaining data on a persistent connection would be misinterpreted remaining data on a persistent connection would be misinterpreted
as the next request. Likewise, as the next request. Likewise,
a client <bcp14>MUST</bcp14> read the entire response message body if it inte nds a client <bcp14>MUST</bcp14> read the entire response message body if it inte nds
to reuse the same connection for a subsequent request. to reuse the same connection for a subsequent request.
</t> </t>
<t> <t>
A proxy server <bcp14>MUST NOT</bcp14> maintain a persistent connection with an A proxy server <bcp14>MUST NOT</bcp14> maintain a persistent connection with an
HTTP/1.0 client (see <xref target="RFC2068" section="19.7.1"/> for HTTP/1.0 client (see <xref target="compatibility.with.http.1.0.persistent.con nections"/> for
information and discussion of the problems with the Keep-Alive header field information and discussion of the problems with the Keep-Alive header field
implemented by many HTTP/1.0 clients). implemented by many HTTP/1.0 clients).
</t> </t>
<t> <t>
See <xref target="compatibility.with.http.1.0.persistent.connections"/> See <xref target="compatibility.with.http.1.0.persistent.connections"/>
for more information on backwards compatibility with HTTP/1.0 clients. for more information on backwards compatibility with HTTP/1.0 clients.
</t> </t>
<section anchor="persistent.retrying.requests" title="Retrying Reque sts"> <section anchor="persistent.retrying.requests" title="Retrying Reque sts">
<t> <t>
Connections can be closed at any time, with or without intention. Connections can be closed at any time, with or without intention.
Implementations ought to anticipate the need to recover Implementations ought to anticipate the need to recover
from asynchronous close events. The conditions under which a client can from asynchronous close events. The conditions under which a client can
automatically retry a sequence of outstanding requests are defined in automatically retry a sequence of outstanding requests are defined in
<xref target="HTTP" section="9.2.2"/>. <xref target="HTTP" section="9.2.2"/>.
</t> </t>
</section> </section>
<section anchor="pipelining" title="Pipelining"> <section anchor="pipelining" title="Pipelining">
<t> <t>
A client that supports persistent connections <bcp14>MAY</bcp14> A client that supports persistent connections <bcp14>MAY</bcp14> "pipeline"
<em>pipeline</em>
its requests (i.e., send multiple requests without waiting for each its requests (i.e., send multiple requests without waiting for each
response). A server <bcp14>MAY</bcp14> process a sequence of pipelined reques ts in response). A server <bcp14>MAY</bcp14> process a sequence of pipelined reques ts in
parallel if they all have safe methods (<xref target="HTTP" section="9.2.1"/> ), but it <bcp14>MUST</bcp14> send parallel if they all have safe methods (<xref target="HTTP" section="9.2.1"/> ), but it <bcp14>MUST</bcp14> send
the corresponding responses in the same order that the requests were the corresponding responses in the same order that the requests were
received. received.
</t> </t>
<t> <t>
A client that pipelines requests <bcp14>SHOULD</bcp14> retry unanswered reque sts if the A client that pipelines requests <bcp14>SHOULD</bcp14> retry unanswered reque sts if the
connection closes before it receives all of the corresponding responses. connection closes before it receives all of the corresponding responses.
When retrying pipelined requests after a failed connection (a connection When retrying pipelined requests after a failed connection (a connection
skipping to change at line 1739 skipping to change at line 1709
<t> <t>
A client, server, or proxy <bcp14>MAY</bcp14> close the transport connection at any A client, server, or proxy <bcp14>MAY</bcp14> close the transport connection at any
time. For example, a client might have started to send a new request time. For example, a client might have started to send a new request
at the same time that the server has decided to close the "idle" at the same time that the server has decided to close the "idle"
connection. From the server's point of view, the connection is being connection. From the server's point of view, the connection is being
closed while it was idle, but from the client's point of view, a closed while it was idle, but from the client's point of view, a
request is in progress. request is in progress.
</t> </t>
<t> <t>
A server <bcp14>SHOULD</bcp14> sustain persistent connections, when possible, and allow A server <bcp14>SHOULD</bcp14> sustain persistent connections, when possible, and allow
the underlying transport's flow-control mechanisms to resolve temporary overl oads, rather the underlying transport's flow-control mechanisms to resolve temporary overl oads rather
than terminate connections with the expectation that clients will retry. than terminate connections with the expectation that clients will retry.
The latter technique can exacerbate network congestion or server load. The latter technique can exacerbate network congestion or server load.
</t> </t>
<t> <t>
A client sending a message body <bcp14>SHOULD</bcp14> monitor A client sending a message body <bcp14>SHOULD</bcp14> monitor
the network connection for an error response while it is transmitting the network connection for an error response while it is transmitting
the request. If the client sees a response that indicates the server does the request. If the client sees a response that indicates the server does
not wish to receive the message body and is closing the connection, the not wish to receive the message body and is closing the connection, the
client <bcp14>SHOULD</bcp14> immediately cease transmitting the body and clos e its side client <bcp14>SHOULD</bcp14> immediately cease transmitting the body and clos e its side
of the connection. of the connection.
</t> </t>
</section> </section>
<section anchor="persistent.tear-down" title="Tear-down"> <section anchor="persistent.tear-down" title="Tear-down">
<iref primary="false" item="Connection header field"/> <iref primary="false" item="Connection header field"/>
<iref primary="true" item="close"/> <iref primary="true" item="close"/>
<t> <t>
The "close" connection option is defined as a signal that the sender The "close" connection option is defined as a signal that the sender
will close this connection after completion of the response. will close this connection after completion of the response.
A sender <bcp14>SHOULD</bcp14> send a Connection header field A sender <bcp14>SHOULD</bcp14> send a Connection header field
(<xref target="HTTP" section="7.6.1"/>) containing the close connection optio n (<xref target="HTTP" section="7.6.1"/>) containing the "close" connection opt ion
when it intends to close a connection. For example, when it intends to close a connection. For example,
</t> </t>
<sourcecode type="http-message"><![CDATA[Connection: close <sourcecode type="http-message"><![CDATA[Connection: close
]]></sourcecode> ]]></sourcecode>
<t> <t>
as a request header field indicates that this is the last request that as a request header field indicates that this is the last request that
the client will send on this connection, while in a response the same the client will send on this connection, while in a response, the same
field indicates that the server is going to close this connection after field indicates that the server is going to close this connection after
the response message is complete. the response message is complete.
</t> </t>
<t anchor="field.close"> <t anchor="field.close">
<iref primary="true" item="Fields" subitem="Close"/> <iref primary="true" item="Fields" subitem="Close"/>
Note that the field name "Close" is reserved, since using that name as a Note that the field name "Close" is reserved, since using that name as a
header field might conflict with the close connection option. header field might conflict with the "close" connection option.
</t> </t>
<t> <t>
A client that sends a close connection option <bcp14>MUST NOT</bcp14> A client that sends a "close" connection option <bcp14>MUST NOT</bcp14>
send further requests on that connection (after the one containing the send further requests on that connection (after the one containing the
close) and <bcp14>MUST</bcp14> close the connection after reading the "close") and <bcp14>MUST</bcp14> close the connection after reading the
final response message corresponding to this request. final response message corresponding to this request.
</t> </t>
<t> <t>
A server that receives a close connection option <bcp14>MUST</bcp14> A server that receives a "close" connection option <bcp14>MUST</bcp14>
initiate closure of the connection (see below) after it sends the initiate closure of the connection (see below) after it sends the
final response to the request that contained the close connection option. final response to the request that contained the "close" connection option.
The server <bcp14>SHOULD</bcp14> send a close connection option in its final The server <bcp14>SHOULD</bcp14> send a "close" connection option in its fina
response l response
on that connection. The server <bcp14>MUST NOT</bcp14> process any further re quests on that connection. The server <bcp14>MUST NOT</bcp14> process any further re quests
received on that connection. received on that connection.
</t> </t>
<t> <t>
A server that sends a close connection option <bcp14>MUST</bcp14> A server that sends a "close" connection option <bcp14>MUST</bcp14>
initiate closure of the connection (see below) after it sends the initiate closure of the connection (see below) after it sends the
response containing the close connection option. The server <bcp14>MUST NOT</ bcp14> process response containing the "close" connection option. The server <bcp14>MUST NOT </bcp14> process
any further requests received on that connection. any further requests received on that connection.
</t> </t>
<t> <t>
A client that receives a close connection option <bcp14>MUST</bcp14> A client that receives a "close" connection option <bcp14>MUST</bcp14>
cease sending requests on that connection and close the connection cease sending requests on that connection and close the connection
after reading the response message containing the close connection option; after reading the response message containing the "close" connection option;
if additional pipelined requests had been sent on the connection, if additional pipelined requests had been sent on the connection,
the client <bcp14>SHOULD NOT</bcp14> assume that they will be processed by th e server. the client <bcp14>SHOULD NOT</bcp14> assume that they will be processed by th e server.
</t> </t>
<t> <t>
If a server performs an immediate close of a TCP connection, there is a If a server performs an immediate close of a TCP connection, there is a
significant risk that the client will not be able to read the last HTTP significant risk that the client will not be able to read the last HTTP
response. If the server receives additional data from the client on a response. If the server receives additional data from the client on a
fully closed connection, such as another request sent by the fully closed connection, such as another request sent by the
client before receiving the server's response, the server's TCP stack will client before receiving the server's response, the server's TCP stack will
send a reset packet to the client; unfortunately, the reset packet might send a reset packet to the client; unfortunately, the reset packet might
skipping to change at line 1843 skipping to change at line 1813
<section anchor="tls.connection.initiation" title="TLS Connection Initi ation"> <section anchor="tls.connection.initiation" title="TLS Connection Initi ation">
<t> <t>
Conceptually, HTTP/TLS is simply sending HTTP messages over a connection Conceptually, HTTP/TLS is simply sending HTTP messages over a connection
secured via TLS <xref target="TLS13"/>. secured via TLS <xref target="TLS13"/>.
</t> </t>
<t> <t>
The HTTP client also acts as the TLS client. It initiates a connection to The HTTP client also acts as the TLS client. It initiates a connection to
the server on the appropriate port and sends the TLS ClientHello to begin the server on the appropriate port and sends the TLS ClientHello to begin
the TLS handshake. When the TLS handshake has finished, the client may then the TLS handshake. When the TLS handshake has finished, the client may then
initiate the first HTTP request. All HTTP data <bcp14>MUST</bcp14> be sent as TLS initiate the first HTTP request. All HTTP data <bcp14>MUST</bcp14> be sent as TLS
"application data", but is otherwise treated like a normal connection for "application data" but is otherwise treated like a normal connection for
HTTP (including potential reuse as a persistent connection). HTTP (including potential reuse as a persistent connection).
</t> </t>
</section> </section>
<section anchor="tls.connection.closure" title="TLS Connection Closure" > <section anchor="tls.connection.closure" title="TLS Connection Closure" >
<t> <t>
TLS uses an exchange of closure alerts prior to (non-error) connection TLS uses an exchange of closure alerts prior to (non-error) connection
closure to provide secure connection closure; see <xref target="TLS13" sectio n="6.1"/>. When a closure to provide secure connection closure; see <xref target="TLS13" sectio n="6.1"/>. When a
valid closure alert is received, an implementation can be assured that no valid closure alert is received, an implementation can be assured that no
further data will be received on that connection. further data will be received on that connection.
</t> </t>
skipping to change at line 1865 skipping to change at line 1835
When an implementation knows that it has sent or received all the When an implementation knows that it has sent or received all the
message data that it cares about, typically by detecting HTTP message message data that it cares about, typically by detecting HTTP message
boundaries, it might generate an "incomplete close" by sending a boundaries, it might generate an "incomplete close" by sending a
closure alert and then closing the connection without waiting to closure alert and then closing the connection without waiting to
receive the corresponding closure alert from its peer. receive the corresponding closure alert from its peer.
</t> </t>
<t> <t>
An incomplete close does not call into question the security of the data An incomplete close does not call into question the security of the data
already received, but it could indicate that subsequent data might have been already received, but it could indicate that subsequent data might have been
truncated. As TLS is not directly aware of HTTP message framing, it is truncated. As TLS is not directly aware of HTTP message framing, it is
necessary to examine the HTTP data itself to determine whether messages were necessary to examine the HTTP data itself to determine whether messages are
complete. Handling of incomplete messages is defined in complete. Handling of incomplete messages is defined in
<xref target="incomplete.messages"/>. <xref target="incomplete.messages"/>.
</t> </t>
<t> <t>
When encountering an incomplete close, a client <bcp14>SHOULD</bcp14> treat a s completed When encountering an incomplete close, a client <bcp14>SHOULD</bcp14> treat a s completed
all requests for which it has received as much data as specified in the all requests for which it has received either
<xref target="body.content-length" format="none">Content-Length</xref> header </t>
or, when a <ol>
<xref target="field.transfer-encoding" format="none">Transfer-Encoding</xref> <li>
of chunked is used, for which the terminal as much data as specified in the <xref target="body.content-length" format="
zero-length chunk has been received. A response that has neither chunked none">Content-Length</xref> header
field or
</li>
<li>
the terminal zero-length chunk (when <xref target="field.transfer-encoding"
format="none">Transfer-Encoding</xref> of chunked is used).
</li>
</ol>
<t>
A response that has neither chunked
transfer coding nor Content-Length is complete only if a valid closure alert transfer coding nor Content-Length is complete only if a valid closure alert
has been received. Treating an incomplete message as complete could expose has been received. Treating an incomplete message as complete could expose
implementations to attack. implementations to attack.
</t> </t>
<t> <t>
A client detecting an incomplete close <bcp14>SHOULD</bcp14> recover graceful ly. A client detecting an incomplete close <bcp14>SHOULD</bcp14> recover graceful ly.
</t> </t>
<t> <t>
Clients <bcp14>MUST</bcp14> send a closure alert before closing the connectio n. Clients <bcp14>MUST</bcp14> send a closure alert before closing the connectio n.
Clients that do not expect to receive any more data <bcp14>MAY</bcp14> choose not Clients that do not expect to receive any more data <bcp14>MAY</bcp14> choose not
to wait for the server's closure alert and simply close the to wait for the server's closure alert and simply close the
connection, thus generating an incomplete close on the server side. connection, thus generating an incomplete close on the server side.
</t> </t>
<t> <t>
Servers <bcp14>SHOULD</bcp14> be prepared to receive an incomplete close from the client, Servers <bcp14>SHOULD</bcp14> be prepared to receive an incomplete close from the client,
since the client can often determine when the end of server data is. since the client can often locate the end of server data.
</t> </t>
<t> <t>
Servers <bcp14>MUST</bcp14> attempt to initiate an exchange of closure alerts with Servers <bcp14>MUST</bcp14> attempt to initiate an exchange of closure alerts with
the client before closing the connection. Servers <bcp14>MAY</bcp14> close th e the client before closing the connection. Servers <bcp14>MAY</bcp14> close th e
connection after sending the closure alert, thus generating an connection after sending the closure alert, thus generating an
incomplete close on the client side. incomplete close on the client side.
</t> </t>
</section> </section>
</section> </section>
<section anchor="enclosing.messages" title="Enclosing Messages as Data"> <section anchor="enclosing.messages" title="Enclosing Messages as Data">
<section anchor="media.type.message.http" title="Media Type message/htt p"> <section anchor="media.type.message.http" title="Media Type message/htt p">
<iref item="Media Type" subitem="message/http" primary="true"/> <iref item="Media Type" subitem="message/http" primary="true"/>
<iref item="message/http Media Type" primary="true"/> <iref item="message/http Media Type" primary="true"/>
<t> <t>
The message/http media type can be used to enclose a single HTTP request or The "message/http" media type can be used to enclose a single HTTP request or
response message, provided that it obeys the MIME restrictions for all response message, provided that it obeys the MIME restrictions for all
"message" types regarding line length and encodings. Because of the line "message" types regarding line length and encodings. Because of the line leng
length limitations, field values within message/http are allowed to use th
limitations, field values within "message/http" are allowed to use
line folding (<xref target="line.folding" format="none">obs-fold</xref>), as described in line folding (<xref target="line.folding" format="none">obs-fold</xref>), as described in
<xref target="line.folding"/>, to convey the field value over multiple <xref target="line.folding"/>, to convey the field value over multiple
lines. A recipient of message/http data <bcp14>MUST</bcp14> replace any obsol ete line lines. A recipient of "message/http" data <bcp14>MUST</bcp14> replace any obs olete line
folding with one or more SP characters when the message is consumed. folding with one or more SP characters when the message is consumed.
</t> </t>
<dl> <dl>
<dt>Type name:</dt> <dt>Type name:</dt>
<dd>message</dd> <dd>message</dd>
<dt>Subtype name:</dt> <dt>Subtype name:</dt>
<dd>http</dd> <dd>http</dd>
<dt>Required parameters:</dt> <dt>Required parameters:</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Optional parameters:</dt> <dt>Optional parameters:</dt>
skipping to change at line 1933 skipping to change at line 1912
<t>version, msgtype</t> <t>version, msgtype</t>
<dl> <dl>
<dt>version:</dt> <dt>version:</dt>
<dd> <dd>
The HTTP-version number of the enclosed message The HTTP-version number of the enclosed message
(e.g., "1.1"). If not present, the version can be (e.g., "1.1"). If not present, the version can be
determined from the first line of the body. determined from the first line of the body.
</dd> </dd>
<dt>msgtype:</dt> <dt>msgtype:</dt>
<dd> <dd>
The message type — "request" or "response". If not The message type -- "request" or "response". If not
present, the type can be determined from the first present, the type can be determined from the first
line of the body. line of the body.
</dd> </dd>
</dl> </dl>
</dd> </dd>
<dt>Encoding considerations:</dt> <dt>Encoding considerations:</dt>
<dd>only "7bit", "8bit", or "binary" are permitted</dd> <dd>only "7bit", "8bit", or "binary" are permitted</dd>
<dt>Security considerations:</dt> <dt>Security considerations:</dt>
<dd>see <xref target="security.considerations"/> <dd>see <xref target="security.considerations"/>
</dd> </dd>
<dt>Interoperability considerations:</dt> <dt>Interoperability considerations:</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Published specification:</dt> <dt>Published specification:</dt>
<dd>This specification (see <xref target="media.type.message.http "/>).</dd> <dd>RFC 9112 (see <xref target="media.type.message.http"/>).</dd>
<dt>Applications that use this media type:</dt> <dt>Applications that use this media type:</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Fragment identifier considerations:</dt> <dt>Fragment identifier considerations:</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Additional information:</dt> <dt>Additional information:</dt>
<dd> <dd>
<dl> <dl>
<dt>Magic number(s):</dt> <dt>Magic number(s):</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Deprecated alias names for this type:</dt> <dt>Deprecated alias names for this type:</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>File extension(s):</dt> <dt>File extension(s):</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Macintosh file type code(s):</dt> <dt>Macintosh file type code(s):</dt>
<dd>N/A</dd> <dd>N/A</dd>
</dl> </dl>
</dd> </dd>
<dt>Person and email address to contact for further information:< /dt> <dt>Person and email address to contact for further information:< /dt>
<dd>See Authors' Addresses section.</dd> <dd>See Authors' Addresses section.</dd>
<dt>Intended usage:</dt> <dt>Intended usage:</dt>
<dd>COMMON</dd> <dd>COMMON</dd>
<dt>Restrictions on usage:</dt> <dt>Restrictions on usage:</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Author:</dt> <dt>Author:</dt>
<dd>See Authors' Addresses section.</dd> <dd>See Authors' Addresses section.</dd>
<dt>Change controller:</dt> <dt>Change controller:</dt>
<dd>IESG</dd> <dd>IESG</dd>
</dl> </dl>
</section> </section>
<section anchor="media.type.application.http" <section anchor="media.type.application.http"
title="Media Type application/http"> title="Media Type application/http">
<iref item="Media Type" subitem="application/http" primary="true"/> <iref item="Media Type" subitem="application/http" primary="true"/>
<iref item="application/http Media Type" primary="true"/> <iref item="application/http Media Type" primary="true"/>
<t> <t>
The application/http media type can be used to enclose a pipeline of one or m ore The "application/http" media type can be used to enclose a pipeline of one or more
HTTP request or response messages (not intermixed). HTTP request or response messages (not intermixed).
</t> </t>
<dl> <dl>
<dt>Type name:</dt> <dt>Type name:</dt>
<dd>application</dd> <dd>application</dd>
<dt>Subtype name:</dt> <dt>Subtype name:</dt>
<dd>http</dd> <dd>http</dd>
<dt>Required parameters:</dt> <dt>Required parameters:</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Optional parameters:</dt> <dt>Optional parameters:</dt>
skipping to change at line 2006 skipping to change at line 1985
</t> </t>
<dl> <dl>
<dt>version:</dt> <dt>version:</dt>
<dd> <dd>
The HTTP-version number of the enclosed messages The HTTP-version number of the enclosed messages
(e.g., "1.1"). If not present, the version can be (e.g., "1.1"). If not present, the version can be
determined from the first line of the body. determined from the first line of the body.
</dd> </dd>
<dt>msgtype:</dt> <dt>msgtype:</dt>
<dd> <dd>
The message type — "request" or "response". If not The message type -- "request" or "response". If not
present, the type can be determined from the first present, the type can be determined from the first
line of the body. line of the body.
</dd> </dd>
</dl> </dl>
</dd> </dd>
<dt>Encoding considerations:</dt> <dt>Encoding considerations:</dt>
<dd> <dd>
HTTP messages enclosed by this type HTTP messages enclosed by this type
are in "binary" format; use of an appropriate are in "binary" format; use of an appropriate
Content-Transfer-Encoding is required when Content-Transfer-Encoding is required when
transmitted via email. transmitted via email.
</dd> </dd>
<dt>Security considerations:</dt> <dt>Security considerations:</dt>
<dd> <dd>
see <xref target="security.considerations"/> see <xref target="security.considerations"/>
</dd> </dd>
<dt>Interoperability considerations:</dt> <dt>Interoperability considerations:</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Published specification:</dt> <dt>Published specification:</dt>
<dd> <dd>
This specification (see <xref target="media.type.application.http"/>). RFC 9112 (see <xref target="media.type.application.http"/>).
</dd> </dd>
<dt>Applications that use this media type:</dt> <dt>Applications that use this media type:</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Fragment identifier considerations:</dt> <dt>Fragment identifier considerations:</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Additional information:</dt> <dt>Additional information:</dt>
<dd> <dd>
<dl> <dl>
<dt>Deprecated alias names for this type:</dt> <dt>Deprecated alias names for this type:</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Magic number(s):</dt> <dt>Magic number(s):</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>File extension(s):</dt> <dt>File extension(s):</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Macintosh file type code(s):</dt> <dt>Macintosh file type code(s):</dt>
<dd>N/A</dd> <dd>N/A</dd>
</dl> </dl>
</dd> </dd>
<dt>Person and email address to contact for further information:< /dt> <dt>Person and email address to contact for further information:< /dt>
<dd>See Authors' Addresses section.</dd> <dd>See Authors' Addresses section.</dd>
<dt>Intended usage:</dt> <dt>Intended usage:</dt>
<dd>COMMON</dd> <dd>COMMON</dd>
<dt>Restrictions on usage:</dt> <dt>Restrictions on usage:</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Author:</dt> <dt>Author:</dt>
<dd>See Authors' Addresses section.</dd> <dd>See Authors' Addresses section.</dd>
<dt>Change controller:</dt> <dt>Change controller:</dt>
<dd>IESG</dd> <dd>IESG</dd>
</dl> </dl>
</section> </section>
</section> </section>
<section anchor="security.considerations" title="Security Considerations"> <section anchor="security.considerations" title="Security Considerations">
<t> <t>
This section is meant to inform developers, information providers, and This section is meant to inform developers, information providers, and
users about known security considerations relevant to HTTP message syntax users about known security considerations relevant to HTTP message syntax
and parsing. Security considerations about HTTP semantics, and parsing. Security considerations about HTTP semantics,
content, and routing are addressed in <xref target="HTTP"/>. content, and routing are addressed in <xref target="HTTP"/>.
</t> </t>
<section anchor="response.splitting" title="Response Splitting"> <section anchor="response.splitting" title="Response Splitting">
<t> <t>
Response splitting (a.k.a., CRLF injection) is a common technique, used in Response splitting (a.k.a.&nbsp;CRLF injection) is a common technique, used i n
various attacks on Web usage, that exploits the line-based nature of HTTP various attacks on Web usage, that exploits the line-based nature of HTTP
message framing and the ordered association of requests to responses on message framing and the ordered association of requests to responses on
persistent connections <xref target="Klein"/>. This technique can be persistent connections <xref target="Klein"/>. This technique can be
particularly damaging when the requests pass through a shared cache. particularly damaging when the requests pass through a shared cache.
</t> </t>
<t> <t>
Response splitting exploits a vulnerability in servers (usually within an Response splitting exploits a vulnerability in servers (usually within an
application server) where an attacker can send encoded data within some application server) where an attacker can send encoded data within some
parameter of the request that is later decoded and echoed within any of the parameter of the request that is later decoded and echoed within any of the
response header fields of the response. If the decoded data is crafted to response header fields of the response. If the decoded data is crafted to
look like the response has ended and a subsequent response has begun, the look like the response has ended and a subsequent response has begun, the
response has been split and the content within the apparent second response response has been split, and the content within the apparent second response
is controlled by the attacker. The attacker can then make any other request is controlled by the attacker. The attacker can then make any other request
on the same persistent connection and trick the recipients (including on the same persistent connection and trick the recipients (including
intermediaries) into believing that the second half of the split is an intermediaries) into believing that the second half of the split is an
authoritative answer to the second request. authoritative answer to the second request.
</t> </t>
<t> <t>
For example, a parameter within the request-target might be read by an For example, a parameter within the request-target might be read by an
application server and reused within a redirect, resulting in the same application server and reused within a redirect, resulting in the same
parameter being echoed in the Location header field of the parameter being echoed in the Location header field of the
response. If the parameter is decoded by the application and not properly response. If the parameter is decoded by the application and not properly
encoded when placed in the response field, the attacker can send encoded encoded when placed in the response field, the attacker can send encoded
CRLF octets and other content that will make the application's single CRLF octets and other content that will make the application's single
response look like two or more responses. response look like two or more responses.
</t> </t>
<t> <t>
A common defense against response splitting is to filter requests for data A common defense against response splitting is to filter requests for data
that looks like encoded CR and LF (e.g., "%0D" and "%0A"). However, that that looks like encoded CR and LF (e.g., "%0D" and "%0A"). However, that
assumes the application server is only performing URI decoding, rather assumes the application server is only performing URI decoding rather
than more obscure data transformations like charset transcoding, XML entity than more obscure data transformations like charset transcoding, XML entity
translation, base64 decoding, sprintf reformatting, etc. A more effective translation, base64 decoding, sprintf reformatting, etc. A more effective
mitigation is to prevent anything other than the server's core protocol mitigation is to prevent anything other than the server's core protocol
libraries from sending a CR or LF within the header section, which means libraries from sending a CR or LF within the header section, which means
restricting the output of header fields to APIs that filter for bad octets restricting the output of header fields to APIs that filter for bad octets
and not allowing application servers to write directly to the protocol and not allowing application servers to write directly to the protocol
stream. stream.
</t> </t>
</section> </section>
<section anchor="request.smuggling" title="Request Smuggling"> <section anchor="request.smuggling" title="Request Smuggling">
skipping to change at line 2137 skipping to change at line 2116
protocols and the use of length or chunk-delimited framing to detect protocols and the use of length or chunk-delimited framing to detect
completeness. Historically, the lack of completeness. Historically, the lack of
a single integrity mechanism has been justified by the informal nature of a single integrity mechanism has been justified by the informal nature of
most HTTP communication. However, the prevalence of HTTP as an information most HTTP communication. However, the prevalence of HTTP as an information
access mechanism has resulted in its increasing use within environments access mechanism has resulted in its increasing use within environments
where verification of message integrity is crucial. where verification of message integrity is crucial.
</t> </t>
<t> <t>
The mechanisms provided with the "https" scheme, such as authenticated The mechanisms provided with the "https" scheme, such as authenticated
encryption, provide protection against modification of messages. Care encryption, provide protection against modification of messages. Care
is needed however to ensure that connection closure cannot be used to is needed, however, to ensure that connection closure cannot be used to
truncate messages (see <xref target="tls.connection.closure"/>). User agents truncate messages (see <xref target="tls.connection.closure"/>). User agents
might refuse to accept incomplete messages or treat them specially. For might refuse to accept incomplete messages or treat them specially. For
example, a browser being used to view medical history or drug interaction example, a browser being used to view medical history or drug interaction
information needs to indicate to the user when such information is detected information needs to indicate to the user when such information is detected
by the protocol to be incomplete, expired, or corrupted during transfer. by the protocol to be incomplete, expired, or corrupted during transfer.
Such mechanisms might be selectively enabled via user agent extensions or Such mechanisms might be selectively enabled via user agent extensions or
the presence of message integrity metadata in a response. the presence of message integrity metadata in a response.
</t> </t>
<t> <t>
The "http" scheme provides no protection against accidental or malicious The "http" scheme provides no protection against accidental or malicious
skipping to change at line 2167 skipping to change at line 2146
</t> </t>
</section> </section>
<section anchor="message.confidentiality" title="Message Confidentialit y"> <section anchor="message.confidentiality" title="Message Confidentialit y">
<t> <t>
HTTP relies on underlying transport protocols to provide message HTTP relies on underlying transport protocols to provide message
confidentiality when that is desired. HTTP has been specifically designed confidentiality when that is desired. HTTP has been specifically designed
to be independent of the transport protocol, such that it can be used to be independent of the transport protocol, such that it can be used
over many forms of encrypted connection, with the selection of over many forms of encrypted connection, with the selection of
such transports being identified by the choice of URI scheme or within such transports being identified by the choice of URI scheme or within
user agent configuration. user agent configuration.
</t> </t>
<t> <t>
The "https" scheme can be used to identify resources that require a The "https" scheme can be used to identify resources that require a
confidential connection, as described in <xref target="HTTP" section="4.2.2"/ >. confidential connection, as described in <xref target="HTTP" section="4.2.2"/ >.
</t> </t>
</section> </section>
</section> </section>
<section anchor="IANA.considerations" title="IANA Considerations"> <section anchor="IANA.considerations" title="IANA Considerations">
<t> <t>
The change controller for the following registrations is: The change controller for the following registrations is:
"IETF (iesg@ietf.org) - Internet Engineering Task Force". "IETF (iesg@ietf.org) - Internet Engineering Task Force".
</t> </t>
<section anchor="field.name.registration" title="Field Name Registratio n"> <section anchor="field.name.registration" title="Field Name Registratio n">
<t> <t>
First, introduce the new "Hypertext Transfer Protocol (HTTP) Field IANA has added the following field names to the "Hypertext Transfer Protocol
Name Registry" at <eref target="https://www.iana.org/assignments/http-fields" (HTTP) Field
brackets="angle"/> Name Registry" at <eref target="https://www.iana.org/assignments/http-fields"
as described in brackets="angle"/>,
<xref target="HTTP" section="18.4"/>. as described in <xref target="HTTP" section="18.4"/>.
</t>
<t>
Then, please update the registry with the field names listed in the table
below:
</t> </t>
<!--AUTOGENERATED FROM extract-header-defs.xslt, do not edit manuall y-->
<table align="left" anchor="iana.header.registration.table"> <table align="left" anchor="iana.header.registration.table">
<thead> <thead>
<tr> <tr>
<th>Field Name</th> <th>Field Name</th>
<th>Status</th> <th>Status</th>
<th>Ref.</th> <th>Section</th>
<th>Comments</th> <th>Comments</th>
</tr> </tr>
</thead> </thead>
<tbody> <tbody>
<tr> <tr>
<td>Close</td> <td>Close</td>
<td>standard</td> <td>permanent</td>
<td> <td>
<xref target="persistent.tear-down" format="counter"/> <xref target="persistent.tear-down" format="counter"/>
</td> </td>
<td>(reserved)</td> <td>(reserved)</td>
</tr> </tr>
<tr> <tr>
<td>MIME-Version</td> <td>MIME-Version</td>
<td>standard</td> <td>permanent</td>
<td> <td>
<xref target="mime-version" format="counter"/> <xref target="mime-version" format="counter"/>
</td> </td>
<td/> <td/>
</tr> </tr>
<tr> <tr>
<td>Transfer-Encoding</td> <td>Transfer-Encoding</td>
<td>standard</td> <td>permanent</td>
<td> <td>
<xref target="field.transfer-encoding" format="counter"/ > <xref target="field.transfer-encoding" format="counter"/ >
</td> </td>
<td/> <td/>
</tr> </tr>
</tbody> </tbody>
</table> </table>
<!--(END)-->
</section> </section>
<section anchor="media.type.http" title="Media Type Registration"> <section anchor="media.type.http" title="Media Type Registration">
<t> <t>
Please update the "Media Types" registry at IANA has updated the "Media Types" registry at
<eref target="https://www.iana.org/assignments/media-types" brackets="angle"/ > <eref target="https://www.iana.org/assignments/media-types" brackets="angle"/ >
with the registration information in with the registration information in Sections
<xref target="media.type.message.http"/> and <xref target="media.type.message.http" format="counter"/> and
<xref target="media.type.application.http"/> for the media types <xref target="media.type.application.http" format="counter"/> for the media t
ypes
"message/http" and "application/http", respectively. "message/http" and "application/http", respectively.
</t> </t>
</section> </section>
<section anchor="transfer.coding.registration" <section anchor="transfer.coding.registration"
title="Transfer Coding Registration"> title="Transfer Coding Registration">
<t> <t>
Please update the "HTTP Transfer Coding Registry" at IANA has updated the "HTTP Transfer Coding Registry" at
<eref target="https://www.iana.org/assignments/http-parameters/" <eref target="https://www.iana.org/assignments/http-parameters/"
brackets="angle"/> brackets="angle"/>
with the registration procedure of <xref target="transfer.coding.registry"/> with the registration procedure of <xref target="transfer.coding.registry"/>
and the content coding names summarized in the table below. and the content coding names summarized in the table below.
</t> </t>
<table align="left" anchor="iana.transfer.coding.registration.table" > <table align="left" anchor="iana.transfer.coding.registration.table" >
<thead> <thead>
<tr> <tr>
<th>Name</th> <th>Name</th>
<th>Description</th> <th>Description</th>
<th>Reference</th> <th>Section</th>
</tr> </tr>
</thead> </thead>
<tbody> <tbody>
<tr> <tr>
<td>chunked</td> <td>chunked</td>
<td>Transfer in a series of chunks</td> <td>Transfer in a series of chunks</td>
<td> <td>
<xref target="chunked.encoding"/> <xref target="chunked.encoding" format="counter"/>
</td> </td>
</tr> </tr>
<tr> <tr>
<td>compress</td> <td>compress</td>
<td>UNIX "compress" data format <xref target="Welch"/> <td>UNIX "compress" data format <xref target="Welch"/>
</td> </td>
<td> <td>
<xref target="compression.codings"/> <xref target="compression.codings" format="counter"/>
</td> </td>
</tr> </tr>
<tr> <tr>
<td>deflate</td> <td>deflate</td>
<td>"deflate" compressed data (<xref target="RFC1951"/>) in side <td>"deflate" compressed data (<xref target="RFC1951"/>) in side
the "zlib" data format (<xref target="RFC1950"/>)</td> the "zlib" data format (<xref target="RFC1950"/>)
</td>
<td> <td>
<xref target="compression.codings"/> <xref target="compression.codings" format="counter"/>
</td> </td>
</tr> </tr>
<tr> <tr>
<td>gzip</td> <td>gzip</td>
<td>GZIP file format <xref target="RFC1952"/> <td>GZIP file format <xref target="RFC1952"/>
</td> </td>
<td> <td>
<xref target="compression.codings"/> <xref target="compression.codings" format="counter"/>
</td> </td>
</tr> </tr>
<tr> <tr>
<td>trailers</td> <td>trailers</td>
<td>(reserved)</td> <td>(reserved)</td>
<td> <td>
<xref target="transfer.coding.registration"/> <xref target="transfer.coding.registration" format="coun ter"/>
</td> </td>
</tr> </tr>
<tr> <tr>
<td>x-compress</td> <td>x-compress</td>
<td>Deprecated (alias for compress)</td> <td>Deprecated (alias for compress)</td>
<td> <td>
<xref target="compression.codings"/> <xref target="compression.codings" format="counter"/>
</td> </td>
</tr> </tr>
<tr> <tr>
<td>x-gzip</td> <td>x-gzip</td>
<td>Deprecated (alias for gzip)</td> <td>Deprecated (alias for gzip)</td>
<td> <td>
<xref target="compression.codings"/> <xref target="compression.codings" format="counter"/>
</td> </td>
</tr> </tr>
</tbody> </tbody>
</table> </table>
<aside> <aside>
<t> <t>
<strong>Note:</strong> the coding name "trailers" is reserved <strong>Note:</strong> the coding name "trailers" is reserved because its use
because its use would would
conflict with the keyword "trailers" in the TE conflict with the keyword "trailers" in the TE
header field (<xref target="HTTP" section="10.1.4"/>). header field (<xref target="HTTP" section="10.1.4"/>).
</t> </t>
</aside> </aside>
</section> </section>
<section anchor="alpn.registration" title="ALPN Protocol ID Registratio n"> <section anchor="alpn.registration" title="ALPN Protocol ID Registratio n">
<t> <t>
Please update the IANA has updated the
"TLS Application-Layer Protocol Negotiation (ALPN) Protocol IDs" registry at "TLS Application-Layer Protocol Negotiation (ALPN) Protocol IDs" registry at
<eref target="https://www.iana.org/assignments/tls-extensiontype-values/tls-e xtensiontype-values.xhtml" <eref target="https://www.iana.org/assignments/tls-extensiontype-values/"
brackets="angle"/> brackets="angle"/>
with the registration below: with the registration below:
</t> </t>
<table> <table>
<thead> <thead>
<tr> <tr>
<th>Protocol</th> <th>Protocol</th>
<th>Identification Sequence</th> <th>Identification Sequence</th>
<th>Reference</th> <th>Reference</th>
</tr> </tr>
</thead> </thead>
<tbody> <tbody>
<tr> <tr>
<td>HTTP/1.1</td> <td>HTTP/1.1</td>
<td>0x68 0x74 0x74 0x70 0x2f 0x31 0x2e 0x31 ("http/1.1")</t d> <td>0x68 0x74 0x74 0x70 0x2f 0x31 0x2e 0x31 ("http/1.1")</t d>
<td>(this specification)</td> <td>RFC 9112</td>
</tr> </tr>
</tbody> </tbody>
</table> </table>
</section> </section>
</section> </section>
</middle> </middle>
<back> <back>
<displayreference xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:x="http://purl.org/net/xml2rfc/ext" <displayreference target="HTTP10" to="HTTP/1.0"/>
target="HTTP10"
to="HTTP/1.0"/>
<references> <references>
<name>References</name> <name>References</name>
<references> <references>
<name>Normative References</name> <name>Normative References</name>
<reference anchor="HTTP"><!--included from draft-ietf-httpbis-semant
ics-latest.xml--> <!-- [HTTP][I-D.ietf-httpbis-semantics]; companion document RFC 9110 -->
<front> <reference anchor='HTTP' target='https://www.rfc-editor.org/info/rfc9110'>
<title>HTTP Semantics</title> <front>
<author fullname="Roy T. Fielding" <title>HTTP Semantics</title>
initials="R." <author initials='R' surname='Fielding' fullname='Roy T. Fielding' role='editor'
surname="Fielding" >
role="editor"> <organization />
<organization>Adobe</organization> </author>
<address> <author initials='M' surname='Nottingham' fullname='Mark Nottingham' role='edito
<postal> r'>
<postalLine>345 Park Ave</postalLine> <organization />
<postalLine>San Jose, CA 95110</postalLine> </author>
<postalLine>United States of America</postalLine> <author initials='J' surname='Reschke' fullname='Julian Reschke' role='editor'>
</postal> <organization />
<email>fielding@gbiv.com</email> </author>
<uri>https://roy.gbiv.com/</uri> <date year='2022' month='June'/>
</address> </front>
</author> <seriesInfo name="STD" value="97"/>
<author fullname="Mark Nottingham" <seriesInfo name="RFC" value="9110"/>
initials="M." <seriesInfo name="DOI" value="10.17487/RFC9110"/>
surname="Nottingham" </reference>
role="editor">
<organization>Fastly</organization> <!-- [CACHING][I-D.ietf-httpbis-cache]; companion document RFC 9111 -->
<address> <reference anchor='CACHING' target='https://www.rfc-editor.org/info/
<postal> rfc9111'>
<postalLine>Prahran VIC</postalLine>
<postalLine>Australia</postalLine>
</postal>
<email>mnot@mnot.net</email>
<uri>https://www.mnot.net/</uri>
</address>
</author>
<author fullname="Julian Reschke"
initials="J."
surname="Reschke"
role="editor">
<organization abbrev="greenbytes">greenbytes GmbH</organiza
tion>
<address>
<postal>
<postalLine>Hafenweg 16</postalLine>
<postalLine>48155 Münster</postalLine>
<postalLine>Germany</postalLine>
</postal>
<email>julian.reschke@greenbytes.de</email>
<uri>https://greenbytes.de/tech/webdav/</uri>
</address>
</author>
<date year="2021" month="September" day="10"/>
</front>
<seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-seman
tics-19"/>
</reference>
<reference anchor="CACHING"><!--included from draft-ietf-httpbis-cac
he-latest.xml-->
<front> <front>
<title>HTTP Caching</title> <title>HTTP Caching</title>
<author fullname="Roy T. Fielding" <author initials='R' surname='Fielding' fullname='Roy Fielding
initials="R." ' role='editor'>
surname="Fielding" <organization />
role="editor">
<organization>Adobe</organization>
<address>
<postal>
<postalLine>345 Park Ave</postalLine>
<postalLine>San Jose, CA 95110</postalLine>
<postalLine>United States of America</postalLine>
</postal>
<email>fielding@gbiv.com</email>
<uri>https://roy.gbiv.com/</uri>
</address>
</author> </author>
<author fullname="Mark Nottingham" <author initials='M' surname='Nottingham' fullname='Mark Notti
initials="M." ngham' role='editor'>
surname="Nottingham" <organization />
role="editor">
<organization>Fastly</organization>
<address>
<postal>
<postalLine>Prahran VIC</postalLine>
<postalLine>Australia</postalLine>
</postal>
<email>mnot@mnot.net</email>
<uri>https://www.mnot.net/</uri>
</address>
</author> </author>
<author fullname="Julian Reschke" <author initials='J' surname='Reschke' fullname='Julian Reschk
initials="J." e' role='editor'>
surname="Reschke" <organization />
role="editor">
<organization abbrev="greenbytes">greenbytes GmbH</organiza
tion>
<address>
<postal>
<postalLine>Hafenweg 16</postalLine>
<postalLine>48155 Münster</postalLine>
<postalLine>Germany</postalLine>
</postal>
<email>julian.reschke@greenbytes.de</email>
<uri>https://greenbytes.de/tech/webdav/</uri>
</address>
</author> </author>
<date year="2021" month="September" day="10"/> <date year='2022' month='June'/>
</front> </front>
<seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-cache <seriesInfo name="STD" value="98"/>
-19"/> <seriesInfo name="RFC" value="9111"/>
<seriesInfo name="DOI" value="10.17487/RFC9111"/>
</reference> </reference>
<reference anchor="URI" target="https://www.rfc-editor.org/info/rfc3 986"> <reference anchor="URI" target="https://www.rfc-editor.org/info/rfc3 986">
<front> <front>
<title abbrev="URI Generic Syntax">Uniform Resource Identifier (URI): Generic Syntax</title> <title abbrev="URI Generic Syntax">Uniform Resource Identifier (URI): Generic Syntax</title>
<author initials="T." surname="Berners-Lee" fullname="Tim Bern ers-Lee"/> <author initials="T." surname="Berners-Lee" fullname="Tim Bern ers-Lee"/>
<author initials="R." surname="Fielding" fullname="Roy T. Fiel ding"/> <author initials="R." surname="Fielding" fullname="Roy T. Fiel ding"/>
<author initials="L." surname="Masinter" fullname="Larry Masin ter"/> <author initials="L." surname="Masinter" fullname="Larry Masin ter"/>
<date month="January" year="2005"/> <date month="January" year="2005"/>
</front> </front>
<seriesInfo name="STD" value="66"/> <seriesInfo name="STD" value="66"/>
<seriesInfo name="RFC" value="3986"/> <seriesInfo name="RFC" value="3986"/>
<seriesInfo name="DOI" value="10.17487/RFC3986"/> <seriesInfo name="DOI" value="10.17487/RFC3986"/>
</reference> </reference>
<reference anchor="RFC5234" target="https://www.rfc-editor.org/info/ <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.5234.
rfc5234"> xml"/>
<front> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7405.
<title abbrev="ABNF for Syntax Specifications">Augmented BNF f xml"/>
or Syntax Specifications: ABNF</title> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.2119.
<author initials="D." xml"/>
surname="Crocker" <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8174.
fullname="Dave Crocker" xml"/>
role="editor"/>
<author initials="P." surname="Overell" fullname="Paul Overell
"/>
<date month="January" year="2008"/>
</front>
<seriesInfo name="STD" value="68"/>
<seriesInfo name="RFC" value="5234"/>
<seriesInfo name="DOI" value="10.17487/RFC5234"/>
</reference>
<reference anchor="RFC7405" target="https://www.rfc-editor.org/info/
rfc7405">
<front>
<title>Case-Sensitive String Support in ABNF</title>
<author initials="P." surname="Kyzivat" fullname="Dave Kyzivat
"/>
<date month="December" year="2014"/>
</front>
<seriesInfo name="RFC" value="7405"/>
<seriesInfo name="DOI" value="10.17487/RFC7405"/>
</reference>
<reference anchor="RFC2119" target="https://www.rfc-editor.org/info/
rfc2119">
<front>
<title>Key words for use in RFCs to Indicate Requirement Level
s</title>
<author initials="S." surname="Bradner" fullname="Scott Bradne
r"/>
<date month="March" year="1997"/>
</front>
<seriesInfo name="BCP" value="14"/>
<seriesInfo name="RFC" value="2119"/>
<seriesInfo name="DOI" value="10.17487/RFC2119"/>
</reference>
<reference anchor="RFC8174" target="https://www.rfc-editor.org/info/
rfc8174">
<front>
<title>Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Wor
ds</title>
<author initials="B." surname="Leiba" fullname="Barry Leiba"/>
<date year="2017" month="May"/>
</front>
<seriesInfo name="BCP" value="14"/>
<seriesInfo name="RFC" value="8174"/>
<seriesInfo name="DOI" value="10.17487/RFC8174"/>
</reference>
<reference anchor="USASCII"> <reference anchor="USASCII">
<front> <front>
<title>Coded Character Set -- 7-bit American Standard Code for Information Interchange</title> <title>Coded Character Set -- 7-bit American Standard Code for Information Interchange</title>
<author> <author>
<organization>American National Standards Institute</organi zation> <organization>American National Standards Institute</organi zation>
</author> </author>
<date year="1986"/> <date year="1986"/>
</front> </front>
<seriesInfo name="ANSI" value="X3.4"/> <seriesInfo name="ANSI" value="X3.4"/>
</reference> </reference>
<reference anchor="RFC1950" target="https://www.rfc-editor.org/info/
rfc1950"> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.1950.
<front> xml"/>
<title>ZLIB Compressed Data Format Specification version 3.3</ <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.1951.
title> xml"/>
<author initials="L.P." surname="Deutsch" fullname="L. Peter D <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.1952.
eutsch"/> xml"/>
<author initials="J-L." surname="Gailly" fullname="Jean-Loup G
ailly"/>
<date month="May" year="1996"/>
</front>
<seriesInfo name="RFC" value="1950"/>
<seriesInfo name="DOI" value="10.17487/RFC1950"/>
</reference>
<reference anchor="RFC1951" target="https://www.rfc-editor.org/info/
rfc1951">
<front>
<title>DEFLATE Compressed Data Format Specification version 1.
3</title>
<author initials="P." surname="Deutsch" fullname="L. Peter Deu
tsch"/>
<date month="May" year="1996"/>
</front>
<seriesInfo name="RFC" value="1951"/>
<seriesInfo name="DOI" value="10.17487/RFC1951"/>
</reference>
<reference anchor="RFC1952" target="https://www.rfc-editor.org/info/
rfc1952">
<front>
<title>GZIP file format specification version 4.3</title>
<author initials="P." surname="Deutsch" fullname="L. Peter Deu
tsch"/>
<author initials="J-L." surname="Gailly" fullname="Jean-Loup G
ailly"/>
<author initials="M." surname="Adler" fullname="Mark Adler"/>
<author initials="L.P." surname="Deutsch" fullname="L. Peter D
eutsch"/>
<author initials="G."
surname="Randers-Pehrson"
fullname="Glenn Randers-Pehrson"/>
<date month="May" year="1996"/>
</front>
<seriesInfo name="RFC" value="1952"/>
<seriesInfo name="DOI" value="10.17487/RFC1952"/>
</reference>
<reference anchor="TLS13" target="https://www.rfc-editor.org/info/rf c8446"> <reference anchor="TLS13" target="https://www.rfc-editor.org/info/rf c8446">
<front> <front>
<title>The Transport Layer Security (TLS) Protocol Version 1.3 </title> <title>The Transport Layer Security (TLS) Protocol Version 1.3 </title>
<author initials="E." surname="Rescorla" fullname="E. Rescorla "/> <author initials="E." surname="Rescorla" fullname="Eric Rescor la"/>
<date year="2018" month="August"/> <date year="2018" month="August"/>
</front> </front>
<seriesInfo name="RFC" value="8446"/> <seriesInfo name="RFC" value="8446"/>
<seriesInfo name="DOI" value="10.17487/RFC8446"/> <seriesInfo name="DOI" value="10.17487/RFC8446"/>
</reference> </reference>
<reference anchor="Welch"> <reference anchor="Welch" target="https://ieeexplore.ieee.org/docume nt/1659158/">
<front> <front>
<title>A Technique for High-Performance Data Compression</titl e> <title>A Technique for High-Performance Data Compression</titl e>
<author initials="T. A." surname="Welch" fullname="Terry A. We lch"/> <author initials="T." surname="Welch" fullname="Terry A. Welch "/>
<date month="June" year="1984"/> <date month="June" year="1984"/>
</front> </front>
<seriesInfo name="IEEE Computer" value="17(6)"/> <seriesInfo name="DOI" value="10.1109/MC.1984.1659158"/>
<refcontent>IEEE Computer 17(6)</refcontent>
</reference> </reference>
</references> </references>
<references> <references>
<name>Informative References</name> <name>Informative References</name>
<reference anchor="HTTP10" target="https://www.rfc-editor.org/info/r fc1945"> <reference anchor="HTTP10" target="https://www.rfc-editor.org/info/r fc1945">
<front> <front>
<title abbrev="HTTP/1.0">Hypertext Transfer Protocol -- HTTP/1 .0</title> <title abbrev="HTTP/1.0">Hypertext Transfer Protocol -- HTTP/1 .0</title>
<author initials="T." surname="Berners-Lee" fullname="Tim Bern <author initials="T." surname="Berners-Lee" fullname="T. Berne
ers-Lee"/> rs-Lee"/>
<author initials="R.T." surname="Fielding" fullname="Roy T. Fi <author initials="R." surname="Fielding" fullname="R. Fielding
elding"/> "/>
<author initials="H.F." surname="Nielsen" fullname="Henrik Fry <author initials="H." surname="Frystyk" fullname="H. Frystyk"/
styk Nielsen"/> >
<date month="May" year="1996"/> <date month="May" year="1996"/>
</front> </front>
<seriesInfo name="RFC" value="1945"/> <seriesInfo name="RFC" value="1945"/>
<seriesInfo name="DOI" value="10.17487/RFC1945"/> <seriesInfo name="DOI" value="10.17487/RFC1945"/>
</reference> </reference>
<reference anchor="RFC2045" target="https://www.rfc-editor.org/info/ <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.2045.
rfc2045"> xml"/>
<front> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.2046.
<title abbrev="Internet Message Bodies">Multipurpose Internet xml"/>
Mail Extensions (MIME) Part One: Format of Internet Message Bodies</title> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.2049.
<author initials="N." surname="Freed" fullname="Ned Freed"/> xml"/>
<author initials="N.S." <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.2068.
surname="Borenstein" xml"/>
fullname="Nathaniel S. Borenstein"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.2557.
<date month="November" year="1996"/> xml"/>
</front> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.5322.
<seriesInfo name="RFC" value="2045"/> xml"/>
<seriesInfo name="DOI" value="10.17487/RFC2045"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7230.
</reference> xml"/>
<reference anchor="RFC2046" target="https://www.rfc-editor.org/info/ <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8126.
rfc2046"> xml"/>
<front>
<title abbrev="Media Types">Multipurpose Internet Mail Extensi <reference anchor="Klein" target="https://packetstormsecurity.com/pa
ons (MIME) Part Two: Media Types</title> pers/general/whitepaper_httpresponse.pdf">
<author initials="N." surname="Freed" fullname="Ned Freed"/>
<author initials="N."
surname="Borenstein"
fullname="Nathaniel S. Borenstein"/>
<date month="November" year="1996"/>
</front>
<seriesInfo name="RFC" value="2046"/>
<seriesInfo name="DOI" value="10.17487/RFC2046"/>
</reference>
<reference anchor="RFC2049" target="https://www.rfc-editor.org/info/
rfc2049">
<front>
<title abbrev="MIME Conformance">Multipurpose Internet Mail Ex
tensions (MIME) Part Five: Conformance Criteria and Examples</title>
<author initials="N." surname="Freed" fullname="Ned Freed"/>
<author initials="N.S."
surname="Borenstein"
fullname="Nathaniel S. Borenstein"/>
<date month="November" year="1996"/>
</front>
<seriesInfo name="RFC" value="2049"/>
<seriesInfo name="DOI" value="10.17487/RFC2049"/>
</reference>
<reference anchor="RFC2068" target="https://www.rfc-editor.org/info/
rfc2068">
<front>
<title>Hypertext Transfer Protocol -- HTTP/1.1</title>
<author initials="R." surname="Fielding" fullname="Roy T. Fiel
ding"/>
<author initials="J." surname="Gettys" fullname="Jim Gettys"/>
<author initials="J." surname="Mogul" fullname="Jeffrey C. Mog
ul"/>
<author initials="H." surname="Nielsen" fullname="Henrik Fryst
yk Nielsen"/>
<author initials="T." surname="Berners-Lee" fullname="Tim Bern
ers-Lee"/>
<date month="January" year="1997"/>
</front>
<seriesInfo name="RFC" value="2068"/>
<seriesInfo name="DOI" value="10.17487/RFC2068"/>
</reference>
<reference anchor="RFC2557" target="https://www.rfc-editor.org/info/
rfc2557">
<front>
<title abbrev="MIME Encapsulation of Aggregate Documents">MIME
Encapsulation of Aggregate Documents, such as HTML (MHTML)</title>
<author initials="F." surname="Palme" fullname="Jacob Palme"/>
<author initials="A." surname="Hopmann" fullname="Alex Hopmann
"/>
<author initials="N." surname="Shelness" fullname="Nick Shelne
ss"/>
<author initials="E." surname="Stefferud" fullname="Einar Stef
ferud"/>
<date year="1999" month="March"/>
</front>
<seriesInfo name="RFC" value="2557"/>
<seriesInfo name="DOI" value="10.17487/RFC2557"/>
</reference>
<reference anchor="RFC5322" target="https://www.rfc-editor.org/info/
rfc5322">
<front>
<title>Internet Message Format</title>
<author initials="P." surname="Resnick" fullname="P. Resnick"/
>
<date year="2008" month="October"/>
</front>
<seriesInfo name="RFC" value="5322"/>
<seriesInfo name="DOI" value="10.17487/RFC5322"/>
</reference>
<reference anchor="RFC7230" target="https://www.rfc-editor.org/info/
rfc7230">
<front>
<title>Hypertext Transfer Protocol (HTTP/1.1): Message Syntax
and Routing</title>
<author initials="R."
surname="Fielding"
fullname="Roy T. Fielding"
role="editor"/>
<author initials="J. F."
surname="Reschke"
fullname="Julian F. Reschke"
role="editor"/>
<date month="June" year="2014"/>
</front>
<seriesInfo name="RFC" value="7230"/>
<seriesInfo name="DOI" value="10.17487/RFC7230"/>
</reference>
<reference anchor="RFC8126" target="https://www.rfc-editor.org/info/
rfc8126">
<front>
<title>Guidelines for Writing an IANA Considerations Section i
n RFCs</title>
<author initials="M." surname="Cotton" fullname="M. Cotton"/>
<author initials="B." surname="Leiba" fullname="B. Leiba"/>
<author initials="T." surname="Narten" fullname="T. Narten"/>
<date year="2017" month="June"/>
</front>
<seriesInfo name="BCP" value="26"/>
<seriesInfo name="RFC" value="8126"/>
<seriesInfo name="DOI" value="10.17487/RFC8126"/>
</reference>
<reference anchor="Klein"
target="https://packetstormsecurity.com/papers/general/wh
itepaper_httpresponse.pdf">
<front> <front>
<title>Divide and Conquer - HTTP Response Splitting, Web Cache Poisoning Attacks, and Related Topics</title> <title>Divide and Conquer - HTTP Response Splitting, Web Cache Poisoning Attacks, and Related Topics</title>
<author initials="A." surname="Klein" fullname="Amit Klein"/> <author initials="A." surname="Klein" fullname="Amit Klein"/>
<date year="2004" month="March"/> <date year="2004" month="March"/>
</front> </front>
</reference> </reference>
<reference anchor="Linhart" <reference anchor="Linhart"
target="https://www.cgisecurity.com/lib/HTTP-Request-Smug gling.pdf"> target="https://www.cgisecurity.com/lib/HTTP-Request-Smug gling.pdf">
<front> <front>
<title>HTTP Request Smuggling</title> <title>HTTP Request Smuggling</title>
<author initials="C." surname="Linhart" fullname="Chaim Linhar t"/> <author initials="C." surname="Linhart" fullname="Chaim Linhar t"/>
<author initials="A." surname="Klein" fullname="Amit Klein"/> <author initials="A." surname="Klein" fullname="Amit Klein"/>
<author initials="R." surname="Heled" fullname="Ronen Heled"/> <author initials="R." surname="Heled" fullname="Ronen Heled"/>
<author initials="S." surname="Orrin" fullname="Steve Orrin"/> <author initials="S." surname="Orrin" fullname="Steve Orrin"/>
<date year="2005" month="June"/> <date year="2005" month="June"/>
</front> </front>
</reference> </reference>
<reference anchor="Err4667"
quote-title="false"
target="https://www.rfc-editor.org/errata/eid4667">
<front>
<title>Erratum ID 4667</title>
<author>
<organization>RFC Errata</organization>
</author>
<date/>
</front>
<seriesInfo name="RFC" value="7230"/>
</reference>
</references> </references>
</references> </references>
<section anchor="collected.abnf" title="Collected ABNF"> <section anchor="collected.abnf" title="Collected ABNF">
<t>In the collected ABNF below, list rules are expanded as per <xref ta <t>In the collected ABNF below, list rules are expanded per <xref target
rget="HTTP" section="5.6.1"/>.</t> ="HTTP" section="5.6.1"/>.</t>
<sourcecode type="abnf" name="draft-ietf-httpbis-messaging-latest.parse <sourcecode type="abnf" name="rfc9112.parsed-abnf"><![CDATA[
d-abnf"><![CDATA[BWS = <BWS, see [HTTP], Section 5.6.3> BWS = <BWS, see [HTTP], Section 5.6.3>
HTTP-message = start-line CRLF *( field-line CRLF ) CRLF [ HTTP-message = start-line CRLF *( field-line CRLF ) CRLF [
message-body ] message-body ]
HTTP-name = %x48.54.54.50 ; HTTP HTTP-name = %x48.54.54.50 ; HTTP
HTTP-version = HTTP-name "/" DIGIT "." DIGIT HTTP-version = HTTP-name "/" DIGIT "." DIGIT
OWS = <OWS, see [HTTP], Section 5.6.3> OWS = <OWS, see [HTTP], Section 5.6.3>
RWS = <RWS, see [HTTP], Section 5.6.3> RWS = <RWS, see [HTTP], Section 5.6.3>
skipping to change at line 2788 skipping to change at line 2535
trailer-section = *( field-line CRLF ) trailer-section = *( field-line CRLF )
transfer-coding = <transfer-coding, see [HTTP], Section 10.1.4> transfer-coding = <transfer-coding, see [HTTP], Section 10.1.4>
uri-host = <host, see [URI], Section 3.2.2> uri-host = <host, see [URI], Section 3.2.2>
]]></sourcecode> ]]></sourcecode>
</section> </section>
<section anchor="differences.between.http.and.mime" <section anchor="differences.between.http.and.mime"
title="Differences between HTTP and MIME"> title="Differences between HTTP and MIME">
<t> <t>
HTTP/1.1 uses many of the constructs defined for the HTTP/1.1 uses many of the constructs defined for the
Internet Message Format <xref target="RFC5322"/> and the Multipurpose Internet Message Format <xref target="RFC5322"/> and Multipurpose
Internet Mail Extensions (MIME) <xref target="RFC2045"/> to Internet Mail Extensions (MIME) <xref target="RFC2045"/> to
allow a message body to be transmitted in an open variety of allow a message body to be transmitted in an open variety of
representations and with extensible fields. However, RFC 2045 representations and with extensible fields. However, some
is focused only on email; applications of HTTP have many characteristics of these constructs have been reinterpreted to better fit the needs
that differ from email; hence, HTTP has features that differ from MIME. of interactive communication, leading to some differences in how MIME
These differences were carefully chosen to optimize performance over binary constructs are used within HTTP. These differences were carefully
connections, to allow greater freedom in the use of new media types, to chosen to optimize performance over binary connections, allow
make date comparisons easier, and to acknowledge the practice of some early greater freedom in the use of new media types, ease date comparisons,
HTTP servers and clients. and accommodate common implementations.
</t> </t>
<t> <t>
This appendix describes specific areas where HTTP differs from MIME. This appendix describes specific areas where HTTP differs from MIME.
Proxies and gateways to and from strict MIME environments need to be Proxies and gateways to and from strict MIME environments need to be
aware of these differences and provide the appropriate conversions aware of these differences and provide the appropriate conversions
where necessary. where necessary.
</t> </t>
<section anchor="mime-version" title="MIME-Version"> <section anchor="mime-version" title="MIME-Version">
<iref primary="true" item="Fields" subitem="MIME-Version"/> <iref primary="true" item="Fields" subitem="MIME-Version"/>
<iref primary="true" item="Header Fields" subitem="MIME-Version"/> <iref primary="true" item="Header Fields" subitem="MIME-Version"/>
<iref primary="true" item="MIME-Version header field"/> <iref primary="true" item="MIME-Version header field"/>
<t> <t>
HTTP is not a MIME-compliant protocol. However, messages can HTTP is not a MIME-compliant protocol. However, messages can
include a single MIME-Version header field to indicate what include a single MIME-Version header field to indicate what
version of the MIME protocol was used to construct the message. Use version of the MIME protocol was used to construct the message. Use
of the MIME-Version header field indicates that the message is in of the MIME-Version header field indicates that the message is in
full conformance with the MIME protocol (as defined in <xref target="RFC2045" />). full conformance with the MIME protocol (as defined in <xref target="RFC2045" />).
Senders are responsible for ensuring full conformance (where Senders are responsible for ensuring full conformance (where
possible) when exporting HTTP messages to strict MIME environments. possible) when exporting HTTP messages to strict MIME environments.
</t> </t>
</section> </section>
<section anchor="conversion.to.canonical.form" <section anchor="conversion.to.canonical.form"
title="Conversion to Canonical Form"> title="Conversion to Canonical Form">
<t> <t>
MIME requires that an Internet mail body part be converted to canonical MIME requires that an Internet mail body part be converted to canonical
form prior to being transferred, as described in <xref target="RFC2049" secti on="4"/>, and that content with a type of "text" represent form prior to being transferred, as described in <xref target="RFC2049" secti on="4"/>, and that content with a type of "text" represents
line breaks as CRLF, forbidding the use of CR or LF outside of line break line breaks as CRLF, forbidding the use of CR or LF outside of line break
sequences <xref target="RFC2046"/>. In contrast, HTTP does not care whether sequences <xref target="RFC2046"/>. In contrast, HTTP does not care whether
CRLF, bare CR, or bare LF are used to indicate a line break within content. CRLF, bare CR, or bare LF are used to indicate a line break within content.
</t> </t>
<t> <t>
A proxy or gateway from HTTP to a strict MIME A proxy or gateway from HTTP to a strict MIME
environment ought to translate all line breaks within text media environment ought to translate all line breaks within text media
types to the RFC 2049 canonical form of CRLF. Note, however, types to the RFC 2049 canonical form of CRLF. Note, however,
this might be complicated by the presence of a Content-Encoding this might be complicated by the presence of a Content-Encoding
and by the fact that HTTP allows the use of some charsets and by the fact that HTTP allows the use of some charsets
skipping to change at line 2855 skipping to change at line 2602
HTTP/1.1 uses a restricted set of date formats (<xref target="HTTP" section=" 5.6.7"/>) to HTTP/1.1 uses a restricted set of date formats (<xref target="HTTP" section=" 5.6.7"/>) to
simplify the process of date comparison. Proxies and gateways from simplify the process of date comparison. Proxies and gateways from
other protocols ought to ensure that any Date header field other protocols ought to ensure that any Date header field
present in a message conforms to one of the HTTP/1.1 formats and rewrite present in a message conforms to one of the HTTP/1.1 formats and rewrite
the date if necessary. the date if necessary.
</t> </t>
</section> </section>
<section anchor="conversion.of.content-encoding" <section anchor="conversion.of.content-encoding"
title="Conversion of Content-Encoding"> title="Conversion of Content-Encoding">
<t> <t>
MIME does not include any concept equivalent to HTTP/1.1's MIME does not include any concept equivalent to HTTP's
Content-Encoding header field. Since this acts as a modifier Content-Encoding header field. Since this acts as a modifier
on the media type, proxies and gateways from HTTP to MIME-compliant on the media type, proxies and gateways from HTTP to MIME-compliant
protocols ought to either change the value of the Content-Type protocols ought to either change the value of the Content-Type
header field or decode the representation before forwarding the message. header field or decode the representation before forwarding the message.
(Some experimental applications of Content-Type for Internet mail have used (Some experimental applications of Content-Type for Internet mail have used
a media-type parameter of ";conversions=&lt;content-coding&gt;" to perform a media-type parameter of ";conversions=&lt;content-coding&gt;" to perform
a function equivalent to Content-Encoding. However, this parameter is a function equivalent to Content-Encoding. However, this parameter is
not part of the MIME standards). not part of the MIME standards.)
</t> </t>
</section> </section>
<section anchor="conversion.of.content-transfer-encoding" <section anchor="conversion.of.content-transfer-encoding"
title="Conversion of Content-Transfer-Encoding"> title="Conversion of Content-Transfer-Encoding">
<iref item="Content-Transfer-Encoding header field"/> <iref item="Content-Transfer-Encoding header field"/>
<t> <t>
HTTP does not use the Content-Transfer-Encoding field of MIME. HTTP does not use the Content-Transfer-Encoding field of MIME.
Proxies and gateways from MIME-compliant protocols to HTTP need to remove Proxies and gateways from MIME-compliant protocols to HTTP need to remove
any Content-Transfer-Encoding prior to delivering the response message to any Content-Transfer-Encoding prior to delivering the response message to
an HTTP client. an HTTP client.
skipping to change at line 2886 skipping to change at line 2633
Proxies and gateways from HTTP to MIME-compliant protocols are Proxies and gateways from HTTP to MIME-compliant protocols are
responsible for ensuring that the message is in the correct format responsible for ensuring that the message is in the correct format
and encoding for safe transport on that protocol, where "safe and encoding for safe transport on that protocol, where "safe
transport" is defined by the limitations of the protocol being used. transport" is defined by the limitations of the protocol being used.
Such a proxy or gateway ought to transform and label the data with an Such a proxy or gateway ought to transform and label the data with an
appropriate Content-Transfer-Encoding if doing so will improve the appropriate Content-Transfer-Encoding if doing so will improve the
likelihood of safe transport over the destination protocol. likelihood of safe transport over the destination protocol.
</t> </t>
</section> </section>
<section anchor="mhtml.line.length" title="MHTML and Line Length Limita tions"> <section anchor="mhtml.line.length" title="MHTML and Line Length Limita tions">
<t> <t>
HTTP implementations that share code with MHTML <xref target="RFC2557"/> HTTP implementations that share code with MHTML <xref target="RFC2557"/>
implementations need to be aware of MIME line length limitations. implementations need to be aware of MIME line length limitations.
Since HTTP does not have this limitation, HTTP does not fold long lines. Since HTTP does not have this limitation, HTTP does not fold long lines.
MHTML messages being transported by HTTP follow all conventions of MHTML, MHTML messages being transported by HTTP follow all conventions of MHTML,
including line length limitations and folding, canonicalization, etc., including line length limitations and folding, canonicalization, etc.,
since HTTP transfers message-bodies without modification and, aside from the since HTTP transfers message-bodies without modification and, aside from the
"multipart/byteranges" type (<xref target="HTTP" section="14.6"/>), "multipart/byteranges" type (<xref target="HTTP" section="14.6"/>),
does not interpret does not interpret
the content or any MIME header lines that might be contained therein. the content or any MIME header lines that might be contained therein.
</t> </t>
</section> </section>
</section> </section>
<section anchor="changes" title="Changes from previous RFCs"> <section anchor="changes" title="Changes from Previous RFCs">
<section anchor="changes.from.0.9" title="Changes from HTTP/0.9"> <section anchor="changes.from.0.9" title="Changes from HTTP/0.9">
<t> <t>
Since HTTP/0.9 did not support header fields in a request, there is no Since HTTP/0.9 did not support header fields in a request, there is no
mechanism for it to support name-based virtual hosts (selection of resource mechanism for it to support name-based virtual hosts (selection of resource
by inspection of the Host header field). by inspection of the Host header field).
Any server that implements name-based virtual hosts ought to disable Any server that implements name-based virtual hosts ought to disable
support for HTTP/0.9. Most requests that appear to be HTTP/0.9 are, in support for HTTP/0.9. Most requests that appear to be HTTP/0.9 are, in
fact, badly constructed HTTP/1.x requests caused by a client failing to fact, badly constructed HTTP/1.x requests caused by a client failing to
properly encode the request-target. properly encode the request-target.
</t> </t>
skipping to change at line 2923 skipping to change at line 2670
title="Multihomed Web Servers"> title="Multihomed Web Servers">
<t> <t>
The requirements that clients and servers support the Host The requirements that clients and servers support the Host
header field (<xref target="HTTP" section="7.2"/>), report an error if it is header field (<xref target="HTTP" section="7.2"/>), report an error if it is
missing from an HTTP/1.1 request, and accept absolute URIs missing from an HTTP/1.1 request, and accept absolute URIs
(<xref target="request.target"/>) (<xref target="request.target"/>)
are among the most important changes defined by HTTP/1.1. are among the most important changes defined by HTTP/1.1.
</t> </t>
<t> <t>
Older HTTP/1.0 clients assumed a one-to-one relationship of IP Older HTTP/1.0 clients assumed a one-to-one relationship of IP
addresses and servers; there was no other established mechanism for addresses and servers; there was no established mechanism for
distinguishing the intended server of a request than the IP address distinguishing the intended server of a request other than the IP address
to which that request was directed. The Host header field was to which that request was directed. The Host header field was
introduced during the development of HTTP/1.1 and, though it was introduced during the development of HTTP/1.1 and, though it was
quickly implemented by most HTTP/1.0 browsers, additional requirements quickly implemented by most HTTP/1.0 browsers, additional requirements
were placed on all HTTP/1.1 requests in order to ensure complete were placed on all HTTP/1.1 requests in order to ensure complete
adoption. At the time of this writing, most HTTP-based services adoption. At the time of this writing, most HTTP-based services
are dependent upon the Host header field for targeting requests. are dependent upon the Host header field for targeting requests.
</t> </t>
</section> </section>
<section anchor="compatibility.with.http.1.0.persistent.connections" <section anchor="compatibility.with.http.1.0.persistent.connections"
title="Keep-Alive Connections"> title="Keep-Alive Connections">
skipping to change at line 2961 skipping to change at line 2708
One attempted solution was the introduction of a Proxy-Connection header One attempted solution was the introduction of a Proxy-Connection header
field, targeted specifically at proxies. In practice, this was also field, targeted specifically at proxies. In practice, this was also
unworkable, because proxies are often deployed in multiple layers, bringing unworkable, because proxies are often deployed in multiple layers, bringing
about the same problem discussed above. about the same problem discussed above.
</t> </t>
<t> <t>
As a result, clients are encouraged not to send the Proxy-Connection header As a result, clients are encouraged not to send the Proxy-Connection header
field in any requests. field in any requests.
</t> </t>
<t> <t>
Clients are also encouraged to consider the use of Connection: keep-alive Clients are also encouraged to consider the use of "Connection: keep-alive"
in requests carefully; while they can enable persistent connections with in requests carefully; while they can enable persistent connections with
HTTP/1.0 servers, clients using them will need to monitor the HTTP/1.0 servers, clients using them will need to monitor the
connection for "hung" requests (which indicate that the client ought to stop connection for "hung" requests (which indicate that the client ought to stop
sending the header field), and this mechanism ought not be used by clients sending the header field), and this mechanism ought not be used by clients
at all when a proxy is being used. at all when a proxy is being used.
</t> </t>
</section> </section>
<section anchor="introduction.of.transfer-encoding" <section anchor="introduction.of.transfer-encoding"
title="Introduction of Transfer-Encoding"> title="Introduction of Transfer-Encoding">
<t> <t>
skipping to change at line 2998 skipping to change at line 2745
Bare CRs have been prohibited outside of content. Bare CRs have been prohibited outside of content.
(<xref target="message.parsing"/>) (<xref target="message.parsing"/>)
</t> </t>
<t> <t>
The ABNF definition of <xref target="authority-form" format="none">authority- form</xref> has changed from the The ABNF definition of <xref target="authority-form" format="none">authority- form</xref> has changed from the
more general authority component of a URI (in which port is optional) to more general authority component of a URI (in which port is optional) to
the specific host:port format that is required by CONNECT. the specific host:port format that is required by CONNECT.
(<xref target="authority-form"/>) (<xref target="authority-form"/>)
</t> </t>
<t> <t>
Required recipients to avoid smuggling/splitting attacks when processing an Recipients are required to avoid smuggling/splitting attacks when processing an
ambiguous message framing. ambiguous message framing.
(<xref target="field.transfer-encoding"/>) (<xref target="field.transfer-encoding"/>)
</t> </t>
<t> <t>
In the ABNF for chunked extensions, re-introduced (bad) whitespace around In the ABNF for chunked extensions, (bad) whitespace around
";" and "=". Whitespace was removed ";" and "=" has been reintroduced. Whitespace was removed
in <xref target="RFC7230"/>, but that change was found to break existing in <xref target="RFC7230"/>, but that change was found to break existing
implementations (see <xref target="Err4667"/>). implementations. (<xref target="chunked.extension"/>)
(<xref target="chunked.extension"/>)
</t> </t>
<t> <t>
Trailer field semantics now transcend the specifics of chunked encoding. Trailer field semantics now transcend the specifics of chunked transfer codin g.
The decoding algorithm for chunked (<xref target="decoding.chunked"/>) has The decoding algorithm for chunked (<xref target="decoding.chunked"/>) has
been updated to encourage storage/forwarding of trailer fields separately been updated to encourage storage/forwarding of trailer fields separately
from the header section, to only allow merging into the header section if from the header section, to only allow merging into the header section if
the recipient knows the corresponding field definition permits and defines the recipient knows the corresponding field definition permits and defines
how to merge, and otherwise to discard the trailer fields instead of how to merge, and otherwise to discard the trailer fields instead of
merging. The trailer part is now called the trailer section to be more merging. The trailer part is now called the trailer section to be more
consistent with the header section and more distinct from a body part. consistent with the header section and more distinct from a body part.
(<xref target="chunked.trailer.section"/>) (<xref target="chunked.trailer.section"/>)
</t> </t>
<t> <t>
Disallowed transfer coding parameters called "q" in order to avoid Transfer coding parameters called "q" are disallowed in order to avoid
conflicts with the use of ranks in the TE header field. conflicts with the use of ranks in the TE header field.
(<xref target="transfer.coding.registry"/>) (<xref target="transfer.coding.registry"/>)
</t> </t>
</section> </section>
</section> </section>
<section anchor="change.log" title="Change Log">
<t>This section is to be removed before publishing as an RFC.</t>
<section anchor="changes.since.publication.as.rfc"
title="Between RFC7230 and draft 00">
<t>
The changes were purely editorial:
</t>
<ul>
<li>Change boilerplate and abstract to indicate the "draft" statu
s, and update references to ancestor specifications.</li>
<li>Adjust historical notes.</li>
<li>Update links to sibling specifications.</li>
<li>Replace sections listing changes from RFC 2616 by new empty s
ections referring to RFC 723x.</li>
<li>Remove acknowledgements specific to RFC 723x.</li>
<li>Move "Acknowledgements" to the very end and make them unnumbe
red.</li>
</ul>
</section>
<section anchor="changes.since.00" title="Since draft-ietf-httpbis-mess
aging-00">
<t>
The changes in this draft are editorial, with respect to HTTP as a whole,
to move all core HTTP semantics into <xref target="HTTP"/>:
</t>
<ul>
<li>Moved introduction, architecture, conformance, and ABNF exten
sions from
<xref target="RFC7230" format="none">RFC 7230 (Messaging)</xref> to
semantics <xref target="HTTP"/>.</li>
<li>Moved discussion of MIME differences from RFC 7231 (Semantics
) to
<xref target="differences.between.http.and.mime"/>
since they mostly cover transforming 1.1 messages.</li>
<li>Moved all extensibility tips, registration procedures, and re
gistry
tables from the IANA considerations to normative sections, reducing the
IANA considerations to just instructions that will be removed prior to
publication as an RFC.</li>
</ul>
</section>
<section anchor="changes.since.01" title="Since draft-ietf-httpbis-mess
aging-01">
<ul>
<li>Cite RFC 8126 instead of RFC 5226 (<eref target="https://gith
ub.com/httpwg/http-core/issues/75" brackets="angle"/>)</li>
<li>Resolved erratum 4779, no change needed here (<eref target="h
ttps://github.com/httpwg/http-core/issues/87" brackets="angle"/>, <eref target="
https://www.rfc-editor.org/errata/eid4779" brackets="angle"/>)</li>
<li>In <xref target="transfer.codings"/>, fixed prose claiming tr
ansfer parameters allow bare names (<eref target="https://github.com/httpwg/http
-core/issues/88" brackets="angle"/>, <eref target="https://www.rfc-editor.org/er
rata/eid4839" brackets="angle"/>)</li>
<li>Resolved erratum 4225, no change needed here (<eref target="h
ttps://github.com/httpwg/http-core/issues/90" brackets="angle"/>, <eref target="
https://www.rfc-editor.org/errata/eid4225" brackets="angle"/>)</li>
<li>Replace "response code" with "response status code" (<eref ta
rget="https://github.com/httpwg/http-core/issues/94" brackets="angle"/>, <eref t
arget="https://www.rfc-editor.org/errata/eid4050" brackets="angle"/>)</li>
<li>In <xref target="persistent.connections"/>, clarify statement
about HTTP/1.0 keep-alive (<eref target="https://github.com/httpwg/http-core/is
sues/96" brackets="angle"/>, <eref target="https://www.rfc-editor.org/errata/eid
4205" brackets="angle"/>)</li>
<li>In <xref target="chunked.extension"/>, re-introduce (bad) whi
tespace around ";" and "=" (<eref target="https://github.com/httpwg/http-core/is
sues/101"
brackets="angle"/>,
<eref target="https://www.rfc-editor.org/errata/eid4667" brackets="angle"/>, <
eref target="https://www.rfc-editor.org/errata/eid4825" brackets="angle"/>)</li>
<li>In <xref target="transfer.coding.registry"/>, state that tran
sfer codings should not use parameters named "q" (<eref target="https://github.c
om/httpwg/http-core/issues/15" brackets="angle"/>, <eref target="https://www.rfc
-editor.org/errata/eid4683" brackets="angle"/>)</li>
<li>In <xref target="transfer.codings"/>, mark coding name "trail
ers" as reserved in the IANA registry (<eref target="https://github.com/httpwg/h
ttp-core/issues/108"
brackets="angle"/>)</li>
</ul>
</section>
<section anchor="changes.since.02" title="Since draft-ietf-httpbis-mess
aging-02">
<ul>
<li>In <xref target="status.line"/>, explain why the reason phras
e should be ignored by clients (<eref target="https://github.com/httpwg/http-cor
e/issues/60" brackets="angle"/>).</li>
<li>Add <xref target="associating.response.to.request"/> to expla
in how request/response correlation is performed (<eref target="https://github.c
om/httpwg/http-core/issues/145"
brackets="angle"/>)</li>
</ul>
</section>
<section anchor="changes.since.03" title="Since draft-ietf-httpbis-mess
aging-03">
<ul>
<li>In <xref target="associating.response.to.request"/>, caution
against treating data on a connection as part of a not-yet-issued request (<eref
target="https://github.com/httpwg/http-core/issues/26" brackets="angle"/>)</li>
<li>In <xref target="transfer.codings"/>, remove the predefined c
odings from the ABNF and make it generic instead (<eref target="https://github.c
om/httpwg/http-core/issues/66" brackets="angle"/>)</li>
<li>Use RFC 7405 ABNF notation for case-sensitive string constant
s (<eref target="https://github.com/httpwg/http-core/issues/133"
brackets="angle"/>)</li>
</ul>
</section>
<section anchor="changes.since.04" title="Since draft-ietf-httpbis-mess
aging-04">
<ul>
<li>In <xref target="HTTP" section="7.8"/>, clarify that protocol
-name is to be matched case-insensitively (<eref target="https://github.com/http
wg/http-core/issues/8" brackets="angle"/>)</li>
<li>In <xref target="line.folding"/>, add leading optional whites
pace to obs-fold ABNF (<eref target="https://github.com/httpwg/http-core/issues/
19" brackets="angle"/>, <eref target="https://www.rfc-editor.org/errata/eid4189"
brackets="angle"/>)</li>
<li>In <xref target="status.line"/>, add clarifications about emp
ty reason phrases (<eref target="https://github.com/httpwg/http-core/issues/197"
brackets="angle"/>)</li>
<li>Move discussion of retries from <xref target="persistent.retr
ying.requests"/> into <xref target="HTTP"/> (<eref target="https://github.com/ht
tpwg/http-core/issues/230"
brackets="angle"/>)</li>
</ul>
</section>
<section anchor="changes.since.05" title="Since draft-ietf-httpbis-mess
aging-05">
<ul>
<li>In <xref target="chunked.trailer.section"/>, the trailer part
has been renamed the trailer section (for consistency with the header section)
and trailers are no longer merged as header fields by default, but rather can be
discarded, kept separate from header fields, or merged with header fields only
if understood and defined as being mergeable (<eref target="https://github.com/h
ttpwg/http-core/issues/16" brackets="angle"/>)</li>
<li>In <xref target="message.format"/> and related Sections, move
the trailing CRLF from the line grammars into the message format (<eref target=
"https://github.com/httpwg/http-core/issues/62" brackets="angle"/>)</li>
<li>Moved <xref target="http.version"/> down (<eref target="https
://github.com/httpwg/http-core/issues/68" brackets="angle"/>)</li>
<li>In <xref target="HTTP" section="7.8"/>, use 'websocket' inste
ad of 'HTTP/2.0' in examples (<eref target="https://github.com/httpwg/http-core/
issues/112"
brackets="angle"/>)</li>
<li>Move version non-specific text from <xref target="message.bod
y"/> into semantics as "payload" (<eref target="https://github.com/httpwg/http-c
ore/issues/159"
brackets="angle"/>)</li>
<li>In <xref target="tls.connection.closure"/>, add text from RFC
2818 (<eref target="https://github.com/httpwg/http-core/issues/236"
brackets="angle"/>)</li>
</ul>
</section>
<section anchor="changes.since.06" title="Since draft-ietf-httpbis-mess
aging-06">
<ul>
<li>In <xref target="alpn.registration"/>, update the ALPN protoc
ol ID for HTTP/1.1 (<eref target="https://github.com/httpwg/http-core/issues/49"
brackets="angle"/>)</li>
<li>In <xref target="header.field.syntax"/>, align with updates t
o field terminology in semantics (<eref target="https://github.com/httpwg/http-c
ore/issues/111"
brackets="angle"/>)</li>
<li>In <xref target="HTTP" section="7.6.1"/>, clarify that new co
nnection options indeed need to be registered (<eref target="https://github.com/
httpwg/http-core/issues/285"
brackets="angle"/>)</li>
<li>In <xref target="requirements.notation"/>, reference RFC 8174
as well (<eref target="https://github.com/httpwg/http-core/issues/303"
brackets="angle"/>)</li>
</ul>
</section>
<section anchor="changes.since.07" title="Since draft-ietf-httpbis-mess
aging-07">
<ul>
<li>Move TE: trailers into <xref target="HTTP"/> (<eref target="h
ttps://github.com/httpwg/http-core/issues/18" brackets="angle"/>)</li>
<li>In <xref target="message.body.length"/>, adjust requirements
for handling multiple content-length values (<eref target="https://github.com/ht
tpwg/http-core/issues/59" brackets="angle"/>)</li>
<li>Throughout, replace "effective request URI" with "target URI"
(<eref target="https://github.com/httpwg/http-core/issues/259"
brackets="angle"/>)</li>
<li>In <xref target="field.transfer-encoding"/>, don't claim Tran
sfer-Encoding is supported by HTTP/2 or later (<eref target="https://github.com/
httpwg/http-core/issues/297"
brackets="angle"/>)</li>
</ul>
</section>
<section anchor="changes.since.08" title="Since draft-ietf-httpbis-mess
aging-08">
<ul>
<li>In <xref target="message.parsing"/>, disallow bare CRs (<eref
target="https://github.com/httpwg/http-core/issues/31" brackets="angle"/>)</li>
<li>
<xref target="collected.abnf"/> now uses the sender variant of
the "#" list expansion (<eref target="https://github.com/httpwg/http-core/issue
s/192"
brackets="angle"/>)</li>
<li>In <xref target="header.field.syntax"/>, adjust IANA "Close"
entry for new registry format (<eref target="https://github.com/httpwg/http-core
/issues/273"
brackets="angle"/>)</li>
</ul>
</section>
<section anchor="changes.since.09" title="Since draft-ietf-httpbis-mess
aging-09">
<ul>
<li>Switch to xml2rfc v3 mode for draft generation (<eref target=
"https://github.com/httpwg/http-core/issues/394"
brackets="angle"/>)</li>
</ul>
</section>
<section anchor="changes.since.10" title="Since draft-ietf-httpbis-mess
aging-10">
<ul>
<li>In <xref target="message.body.length"/>, note that TCP half-c
lose does not delimit a request; talk about corresponding server-side behaviour
in <xref target="persistent.tear-down"/> (<eref target="https://github.com/httpw
g/http-core/issues/22" brackets="angle"/>)</li>
<li>Moved requirements specific to HTTP/1.1 from <xref target="HT
TP"/> into <xref target="request.target"/> (<eref target="https://github.com/htt
pwg/http-core/issues/182"
brackets="angle"/>)</li>
<li>In <xref target="field.transfer-encoding"/> (<xref target="fi
eld.transfer-encoding" format="none">Transfer-Encoding</xref>), adjust ABNF to a
llow empty lists (<eref target="https://github.com/httpwg/http-core/issues/210"
brackets="angle"/>)</li>
<li>In <xref target="tls.connection.initiation"/>, add text from
RFC 2818 (<eref target="https://github.com/httpwg/http-core/issues/236"
brackets="angle"/>)</li>
<li>Moved definitions of "TE" and "Upgrade" into <xref target="HT
TP"/> (<eref target="https://github.com/httpwg/http-core/issues/392"
brackets="angle"/>)</li>
<li>Moved definition of "Connection" into <xref target="HTTP"/> (
<eref target="https://github.com/httpwg/http-core/issues/407"
brackets="angle"/>)</li>
</ul>
</section>
<section anchor="changes.since.11" title="Since draft-ietf-httpbis-mess
aging-11">
<ul>
<li>Move IANA Upgrade Token Registry instructions to <xref target
="HTTP"/> (<eref target="https://github.com/httpwg/http-core/issues/450"
brackets="angle"/>)</li>
</ul>
</section>
<section anchor="changes.since.12" title="Since draft-ietf-httpbis-mess
aging-12">
<ul>
<li>Moved content of history appendix to Semantics (<eref target=
"https://github.com/httpwg/http-core/issues/451"
brackets="angle"/>)</li>
<li>Moved note about "close" being reserved as field name to <xre
f target="persistent.connections"/> (<eref target="https://github.com/httpwg/htt
p-core/issues/500"
brackets="angle"/>)</li>
<li>Moved table of transfer codings into <xref target="transfer.c
oding.registration"/> (<eref target="https://github.com/httpwg/http-core/issues/
506"
brackets="angle"/>)</li>
<li>In Section 13.2, updated the URI for the <xref target="Linhar
t"/> paper (<eref target="https://github.com/httpwg/http-core/issues/517"
brackets="angle"/>)</li>
<li>Changed document title to just "HTTP/1.1" (<eref target="http
s://github.com/httpwg/http-core/issues/524"
brackets="angle"/>)</li>
<li>In <xref target="transfer.codings"/>, moved transfer-coding A
BNF to <xref target="HTTP" section="10.1.4"/> (<eref target="https://github.com/
httpwg/http-core/issues/531"
brackets="angle"/>)</li>
<li>Changed to using "payload data" when defining requirements ab
out the data being conveyed within a message, instead of the terms "payload body
" or "response body" or "representation body", since they often get confused wit
h the HTTP/1.1 message body (which includes transfer coding) (<eref target="http
s://github.com/httpwg/http-core/issues/553"
brackets="angle"/>)</li>
</ul>
</section>
<section anchor="changes.since.13" title="Since draft-ietf-httpbis-mess
aging-13">
<ul>
<li>In <xref target="message.body.length"/>, clarify that a messa
ge needs to be checked for both Content-Length and Transfer-Encoding, before pro
cessing Transfer-Encoding, and that ought to be treated as an error, but an inte
rmediary can choose to forward the message downstream after removing the Content
-Length and processing the Transfer-Encoding (<eref target="https://github.com/h
ttpwg/http-core/issues/617"
brackets="angle"/>)</li>
<li>Changed to using "content" instead of "payload" or "payload d
ata" to avoid confusion with the payload of version-specific messaging frames (<
eref target="https://github.com/httpwg/http-core/issues/654"
brackets="angle"/>)</li>
</ul>
</section>
<section anchor="changes.since.14" title="Since draft-ietf-httpbis-mess
aging-14">
<ul>
<li>In <xref target="persistent.tear-down"/>, define the close co
nnection option, since its definition was removed from the Connection header fie
ld for being specific to 1.1 (<eref target="https://github.com/httpwg/http-core/
issues/678"
brackets="angle"/>)</li>
<li>In <xref target="reconstructing.target.uri"/>, clarify how th
e target URI is reconstructed when the request-target is not in absolute-form an
d highlight risk in selecting a default host (<eref target="https://github.com/h
ttpwg/http-core/issues/722"
brackets="angle"/>)</li>
<li>In <xref target="chunked.encoding"/>, clarify large chunk han
dling issues (<eref target="https://github.com/httpwg/http-core/issues/749"
brackets="angle"/>)</li>
<li>In <xref target="message.parsing"/>, explicitly close the con
nection after sending a 400 (<eref target="https://github.com/httpwg/http-core/i
ssues/750"
brackets="angle"/>)</li>
<li>In <xref target="http.version"/>, refine version requirements
for intermediaries (<eref target="https://github.com/httpwg/http-core/issues/75
1"
brackets="angle"/>)</li>
<li>In <xref target="decoding.chunked"/>, don't remove the Traile
r header field (<eref target="https://github.com/httpwg/http-core/issues/793"
brackets="angle"/>)</li>
<li>In <xref target="authority-form"/>, changed the ABNF definiti
on of authority-form from the authority component (in which port is optional) to
the host:port format that has always been required by CONNECT (<eref target="ht
tps://github.com/httpwg/http-core/issues/806"
brackets="angle"/>)</li>
</ul>
</section>
<section anchor="changes.since.15" title="Since draft-ietf-httpbis-mess
aging-15">
<ul>
<li>None.</li>
</ul>
</section>
<section anchor="changes.since.16" title="Since draft-ietf-httpbis-mess
aging-16">
<t>
This draft addresses mostly editorial issues raised during or past IETF
Last Call; see <eref target="https://github.com/httpwg/http-core/issues?q=labe
l%3Ah1-messaging+created%3A%3E2021-05-26"
brackets="angle"/>
for a summary.
</t>
<t>
Furthermore:
</t>
<ul>
<li>In <xref target="field.transfer-encoding"/>, require recipien
ts to avoid smuggling/splitting attacks when processing an ambiguous message fra
ming (<eref target="https://github.com/httpwg/http-core/issues/879"
brackets="angle"/>)</li>
</ul>
</section>
<section anchor="changes.since.17" title="Since draft-ietf-httpbis-mess
aging-17">
<ul>
<li>In <xref target="status.line"/>, rephrase text about status c
ode definitions in <xref target="HTTP"/> (<eref target="https://github.com/httpw
g/http-core/issues/915"
brackets="angle"/>)</li>
<li>In <xref target="associating.response.to.request"/>, clarify
how to match responses to requests (<eref target="https://github.com/httpwg/http
-core/issues/915"
brackets="angle"/>)</li>
<li>Made reference to <xref target="RFC5322"/> normative, as it i
s referenced from the ABNF (for "From" header field) (<eref target="https://gith
ub.com/httpwg/http-core/issues/915"
brackets="angle"/>)</li>
<li>In <xref target="line.folding"/>, include text about message/
http that previously was in <xref target="HTTP"/> (<eref target="https://github.
com/httpwg/http-core/issues/923"
brackets="angle"/>)</li>
<li>Throughout, disambiguate "selected representation" and "selec
ted response" (now "chosen response") (<eref target="https://github.com/httpwg/h
ttp-core/issues/958"
brackets="angle"/>)</li>
</ul>
</section>
<section anchor="changes.since.18" title="Since draft-ietf-httpbis-mess
aging-18">
<ul>
<li>Improve a few crossrefs into <xref target="HTTP"/> (<eref tar
get="https://github.com/httpwg/http-core/issues/966"
brackets="angle"/>)</li>
<li>In <xref target="chunked.trailer.section"/>, improve readabil
ity of formerly overlong sentence (<eref target="https://github.com/httpwg/http-
core/issues/966"
brackets="angle"/>)</li>
<li>Slightly rephrase <xref target="tls.connection.closure"/> (<e
ref target="https://github.com/httpwg/http-core/pull/972" brackets="angle"/>)</l
i>
</ul>
</section>
</section>
<section anchor="acks" numbered="false" title="Acknowledgements"> <section anchor="acks" numbered="false" title="Acknowledgements">
<t> <t>
See Appendix "Acknowledgements" of <xref target="HTTP"/>. See Appendix "Acknowledgements" of <xref target="HTTP"/>, which applies to thi s document as well.
</t> </t>
</section> </section>
</back> </back>
</rfc> </rfc>
 End of changes. 208 change blocks. 
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