draft-ietf-httpbis-messaging-16.txt   draft-ietf-httpbis-messaging-17.txt 
HTTP Working Group R. Fielding, Ed. HTTP Working Group R. Fielding, Ed.
Internet-Draft Adobe Internet-Draft Adobe
Obsoletes: 7230 (if approved) M. Nottingham, Ed. Obsoletes: 7230 (if approved) M. Nottingham, Ed.
Intended status: Standards Track Fastly Intended status: Standards Track Fastly
Expires: 28 November 2021 J. Reschke, Ed. Expires: 27 January 2022 J. Reschke, Ed.
greenbytes greenbytes
27 May 2021 26 July 2021
HTTP/1.1 HTTP/1.1
draft-ietf-httpbis-messaging-16 draft-ietf-httpbis-messaging-17
Abstract Abstract
The Hypertext Transfer Protocol (HTTP) is a stateless application- The Hypertext Transfer Protocol (HTTP) is a stateless application-
level protocol for distributed, collaborative, hypertext information level protocol for distributed, collaborative, hypertext information
systems. This document specifies the HTTP/1.1 message syntax, systems. This document specifies the HTTP/1.1 message syntax,
message parsing, connection management, and related security message parsing, connection management, and related security
concerns. concerns.
This document obsoletes portions of RFC 7230. This document obsoletes portions of RFC 7230.
skipping to change at page 1, line 36 skipping to change at page 1, line 36
This note is to be removed before publishing as an RFC. This note is to be removed before publishing as an RFC.
Discussion of this draft takes place on the HTTP working group Discussion of this draft takes place on the HTTP working group
mailing list (ietf-http-wg@w3.org), which is archived at mailing list (ietf-http-wg@w3.org), which is archived at
<https://lists.w3.org/Archives/Public/ietf-http-wg/>. <https://lists.w3.org/Archives/Public/ietf-http-wg/>.
Working Group information can be found at <https://httpwg.org/>; Working Group information can be found at <https://httpwg.org/>;
source code and issues list for this draft can be found at source code and issues list for this draft can be found at
<https://github.com/httpwg/http-core>. <https://github.com/httpwg/http-core>.
The changes in this draft are summarized in Appendix D.17. The changes in this draft are summarized in Appendix D.18.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on 28 November 2021. This Internet-Draft will expire on 27 January 2022.
Copyright Notice Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/ Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document. license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
skipping to change at page 3, line 4 skipping to change at page 3, line 4
2. Message . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2. Message . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1. Message Format . . . . . . . . . . . . . . . . . . . . . 6 2.1. Message Format . . . . . . . . . . . . . . . . . . . . . 6
2.2. Message Parsing . . . . . . . . . . . . . . . . . . . . . 7 2.2. Message Parsing . . . . . . . . . . . . . . . . . . . . . 7
2.3. HTTP Version . . . . . . . . . . . . . . . . . . . . . . 8 2.3. HTTP Version . . . . . . . . . . . . . . . . . . . . . . 8
3. Request Line . . . . . . . . . . . . . . . . . . . . . . . . 9 3. Request Line . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1. Method . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.1. Method . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2. Request Target . . . . . . . . . . . . . . . . . . . . . 10 3.2. Request Target . . . . . . . . . . . . . . . . . . . . . 10
3.2.1. origin-form . . . . . . . . . . . . . . . . . . . . . 11 3.2.1. origin-form . . . . . . . . . . . . . . . . . . . . . 11
3.2.2. absolute-form . . . . . . . . . . . . . . . . . . . . 11 3.2.2. absolute-form . . . . . . . . . . . . . . . . . . . . 11
3.2.3. authority-form . . . . . . . . . . . . . . . . . . . 12 3.2.3. authority-form . . . . . . . . . . . . . . . . . . . 12
3.2.4. asterisk-form . . . . . . . . . . . . . . . . . . . . 13 3.2.4. asterisk-form . . . . . . . . . . . . . . . . . . . . 12
3.3. Reconstructing the Target URI . . . . . . . . . . . . . . 13 3.3. Reconstructing the Target URI . . . . . . . . . . . . . . 13
4. Status Line . . . . . . . . . . . . . . . . . . . . . . . . . 15 4. Status Line . . . . . . . . . . . . . . . . . . . . . . . . . 15
5. Field Syntax . . . . . . . . . . . . . . . . . . . . . . . . 16 5. Field Syntax . . . . . . . . . . . . . . . . . . . . . . . . 16
5.1. Field Line Parsing . . . . . . . . . . . . . . . . . . . 16 5.1. Field Line Parsing . . . . . . . . . . . . . . . . . . . 16
5.2. Obsolete Line Folding . . . . . . . . . . . . . . . . . . 17 5.2. Obsolete Line Folding . . . . . . . . . . . . . . . . . . 17
6. Message Body . . . . . . . . . . . . . . . . . . . . . . . . 17 6. Message Body . . . . . . . . . . . . . . . . . . . . . . . . 17
6.1. Transfer-Encoding . . . . . . . . . . . . . . . . . . . . 18 6.1. Transfer-Encoding . . . . . . . . . . . . . . . . . . . . 18
6.2. Content-Length . . . . . . . . . . . . . . . . . . . . . 19 6.2. Content-Length . . . . . . . . . . . . . . . . . . . . . 20
6.3. Message Body Length . . . . . . . . . . . . . . . . . . . 20 6.3. Message Body Length . . . . . . . . . . . . . . . . . . . 20
7. Transfer Codings . . . . . . . . . . . . . . . . . . . . . . 22 7. Transfer Codings . . . . . . . . . . . . . . . . . . . . . . 23
7.1. Chunked Transfer Coding . . . . . . . . . . . . . . . . . 23 7.1. Chunked Transfer Coding . . . . . . . . . . . . . . . . . 23
7.1.1. Chunk Extensions . . . . . . . . . . . . . . . . . . 23 7.1.1. Chunk Extensions . . . . . . . . . . . . . . . . . . 24
7.1.2. Chunked Trailer Section . . . . . . . . . . . . . . . 24 7.1.2. Chunked Trailer Section . . . . . . . . . . . . . . . 25
7.1.3. Decoding Chunked . . . . . . . . . . . . . . . . . . 24 7.1.3. Decoding Chunked . . . . . . . . . . . . . . . . . . 25
7.2. Transfer Codings for Compression . . . . . . . . . . . . 25 7.2. Transfer Codings for Compression . . . . . . . . . . . . 26
7.3. Transfer Coding Registry . . . . . . . . . . . . . . . . 25 7.3. Transfer Coding Registry . . . . . . . . . . . . . . . . 26
7.4. Negotiating Transfer Codings . . . . . . . . . . . . . . 26 7.4. Negotiating Transfer Codings . . . . . . . . . . . . . . 27
8. Handling Incomplete Messages . . . . . . . . . . . . . . . . 27 8. Handling Incomplete Messages . . . . . . . . . . . . . . . . 27
9. Connection Management . . . . . . . . . . . . . . . . . . . . 28 9. Connection Management . . . . . . . . . . . . . . . . . . . . 28
9.1. Establishment . . . . . . . . . . . . . . . . . . . . . . 28 9.1. Establishment . . . . . . . . . . . . . . . . . . . . . . 29
9.2. Associating a Response to a Request . . . . . . . . . . . 28 9.2. Associating a Response to a Request . . . . . . . . . . . 29
9.3. Persistence . . . . . . . . . . . . . . . . . . . . . . . 29 9.3. Persistence . . . . . . . . . . . . . . . . . . . . . . . 29
9.3.1. Retrying Requests . . . . . . . . . . . . . . . . . . 30 9.3.1. Retrying Requests . . . . . . . . . . . . . . . . . . 30
9.3.2. Pipelining . . . . . . . . . . . . . . . . . . . . . 30 9.3.2. Pipelining . . . . . . . . . . . . . . . . . . . . . 31
9.4. Concurrency . . . . . . . . . . . . . . . . . . . . . . . 31 9.4. Concurrency . . . . . . . . . . . . . . . . . . . . . . . 31
9.5. Failures and Timeouts . . . . . . . . . . . . . . . . . . 31 9.5. Failures and Timeouts . . . . . . . . . . . . . . . . . . 32
9.6. Tear-down . . . . . . . . . . . . . . . . . . . . . . . . 32 9.6. Tear-down . . . . . . . . . . . . . . . . . . . . . . . . 33
9.7. TLS Connection Initiation . . . . . . . . . . . . . . . . 34 9.7. TLS Connection Initiation . . . . . . . . . . . . . . . . 34
9.8. TLS Connection Closure . . . . . . . . . . . . . . . . . 34 9.8. TLS Connection Closure . . . . . . . . . . . . . . . . . 35
10. Enclosing Messages as Data . . . . . . . . . . . . . . . . . 35 10. Enclosing Messages as Data . . . . . . . . . . . . . . . . . 36
10.1. Media Type message/http . . . . . . . . . . . . . . . . 35 10.1. Media Type message/http . . . . . . . . . . . . . . . . 36
10.2. Media Type application/http . . . . . . . . . . . . . . 36 10.2. Media Type application/http . . . . . . . . . . . . . . 37
11. Security Considerations . . . . . . . . . . . . . . . . . . . 37 11. Security Considerations . . . . . . . . . . . . . . . . . . . 38
11.1. Response Splitting . . . . . . . . . . . . . . . . . . . 37 11.1. Response Splitting . . . . . . . . . . . . . . . . . . . 38
11.2. Request Smuggling . . . . . . . . . . . . . . . . . . . 38 11.2. Request Smuggling . . . . . . . . . . . . . . . . . . . 39
11.3. Message Integrity . . . . . . . . . . . . . . . . . . . 39 11.3. Message Integrity . . . . . . . . . . . . . . . . . . . 39
11.4. Message Confidentiality . . . . . . . . . . . . . . . . 39 11.4. Message Confidentiality . . . . . . . . . . . . . . . . 40
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 40 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 40
12.1. Field Name Registration . . . . . . . . . . . . . . . . 40 12.1. Field Name Registration . . . . . . . . . . . . . . . . 40
12.2. Media Type Registration . . . . . . . . . . . . . . . . 40 12.2. Media Type Registration . . . . . . . . . . . . . . . . 41
12.3. Transfer Coding Registration . . . . . . . . . . . . . . 40 12.3. Transfer Coding Registration . . . . . . . . . . . . . . 41
12.4. ALPN Protocol ID Registration . . . . . . . . . . . . . 41 12.4. ALPN Protocol ID Registration . . . . . . . . . . . . . 42
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 42 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 42
13.1. Normative References . . . . . . . . . . . . . . . . . . 42 13.1. Normative References . . . . . . . . . . . . . . . . . . 42
13.2. Informative References . . . . . . . . . . . . . . . . . 43 13.2. Informative References . . . . . . . . . . . . . . . . . 43
Appendix A. Collected ABNF . . . . . . . . . . . . . . . . . . . 44 Appendix A. Collected ABNF . . . . . . . . . . . . . . . . . . . 44
Appendix B. Differences between HTTP and MIME . . . . . . . . . 46 Appendix B. Differences between HTTP and MIME . . . . . . . . . 46
B.1. MIME-Version . . . . . . . . . . . . . . . . . . . . . . 46 B.1. MIME-Version . . . . . . . . . . . . . . . . . . . . . . 46
B.2. Conversion to Canonical Form . . . . . . . . . . . . . . 46 B.2. Conversion to Canonical Form . . . . . . . . . . . . . . 47
B.3. Conversion of Date Formats . . . . . . . . . . . . . . . 47 B.3. Conversion of Date Formats . . . . . . . . . . . . . . . 47
B.4. Conversion of Content-Encoding . . . . . . . . . . . . . 47 B.4. Conversion of Content-Encoding . . . . . . . . . . . . . 47
B.5. Conversion of Content-Transfer-Encoding . . . . . . . . . 47 B.5. Conversion of Content-Transfer-Encoding . . . . . . . . . 47
B.6. MHTML and Line Length Limitations . . . . . . . . . . . . 48 B.6. MHTML and Line Length Limitations . . . . . . . . . . . . 48
Appendix C. Changes from previous RFCs . . . . . . . . . . . . . 48 Appendix C. Changes from previous RFCs . . . . . . . . . . . . . 48
C.1. Changes from HTTP/0.9 . . . . . . . . . . . . . . . . . . 48 C.1. Changes from HTTP/0.9 . . . . . . . . . . . . . . . . . . 48
C.2. Changes from HTTP/1.0 . . . . . . . . . . . . . . . . . . 48 C.2. Changes from HTTP/1.0 . . . . . . . . . . . . . . . . . . 48
C.2.1. Multihomed Web Servers . . . . . . . . . . . . . . . 48 C.2.1. Multihomed Web Servers . . . . . . . . . . . . . . . 48
C.2.2. Keep-Alive Connections . . . . . . . . . . . . . . . 49 C.2.2. Keep-Alive Connections . . . . . . . . . . . . . . . 49
C.2.3. Introduction of Transfer-Encoding . . . . . . . . . . 49 C.2.3. Introduction of Transfer-Encoding . . . . . . . . . . 49
C.3. Changes from RFC 7230 . . . . . . . . . . . . . . . . . . 49 C.3. Changes from RFC 7230 . . . . . . . . . . . . . . . . . . 50
Appendix D. Change Log . . . . . . . . . . . . . . . . . . . . . 50 Appendix D. Change Log . . . . . . . . . . . . . . . . . . . . . 50
D.1. Between RFC7230 and draft 00 . . . . . . . . . . . . . . 50 D.1. Between RFC7230 and draft 00 . . . . . . . . . . . . . . 50
D.2. Since draft-ietf-httpbis-messaging-00 . . . . . . . . . . 51 D.2. Since draft-ietf-httpbis-messaging-00 . . . . . . . . . . 51
D.3. Since draft-ietf-httpbis-messaging-01 . . . . . . . . . . 51 D.3. Since draft-ietf-httpbis-messaging-01 . . . . . . . . . . 51
D.4. Since draft-ietf-httpbis-messaging-02 . . . . . . . . . . 52 D.4. Since draft-ietf-httpbis-messaging-02 . . . . . . . . . . 52
D.5. Since draft-ietf-httpbis-messaging-03 . . . . . . . . . . 52 D.5. Since draft-ietf-httpbis-messaging-03 . . . . . . . . . . 52
D.6. Since draft-ietf-httpbis-messaging-04 . . . . . . . . . . 52 D.6. Since draft-ietf-httpbis-messaging-04 . . . . . . . . . . 52
D.7. Since draft-ietf-httpbis-messaging-05 . . . . . . . . . . 52 D.7. Since draft-ietf-httpbis-messaging-05 . . . . . . . . . . 53
D.8. Since draft-ietf-httpbis-messaging-06 . . . . . . . . . . 53 D.8. Since draft-ietf-httpbis-messaging-06 . . . . . . . . . . 53
D.9. Since draft-ietf-httpbis-messaging-07 . . . . . . . . . . 53 D.9. Since draft-ietf-httpbis-messaging-07 . . . . . . . . . . 53
D.10. Since draft-ietf-httpbis-messaging-08 . . . . . . . . . . 54 D.10. Since draft-ietf-httpbis-messaging-08 . . . . . . . . . . 54
D.11. Since draft-ietf-httpbis-messaging-09 . . . . . . . . . . 54 D.11. Since draft-ietf-httpbis-messaging-09 . . . . . . . . . . 54
D.12. Since draft-ietf-httpbis-messaging-10 . . . . . . . . . . 54 D.12. Since draft-ietf-httpbis-messaging-10 . . . . . . . . . . 54
D.13. Since draft-ietf-httpbis-messaging-11 . . . . . . . . . . 54 D.13. Since draft-ietf-httpbis-messaging-11 . . . . . . . . . . 55
D.14. Since draft-ietf-httpbis-messaging-12 . . . . . . . . . . 55 D.14. Since draft-ietf-httpbis-messaging-12 . . . . . . . . . . 55
D.15. Since draft-ietf-httpbis-messaging-13 . . . . . . . . . . 55 D.15. Since draft-ietf-httpbis-messaging-13 . . . . . . . . . . 55
D.16. Since draft-ietf-httpbis-messaging-14 . . . . . . . . . . 55 D.16. Since draft-ietf-httpbis-messaging-14 . . . . . . . . . . 55
D.17. Since draft-ietf-httpbis-messaging-15 . . . . . . . . . . 56 D.17. Since draft-ietf-httpbis-messaging-15 . . . . . . . . . . 56
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 56 D.18. Since draft-ietf-httpbis-messaging-16 . . . . . . . . . . 56
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 56
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 59 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 59
1. Introduction 1. Introduction
The Hypertext Transfer Protocol (HTTP) is a stateless application- The Hypertext Transfer Protocol (HTTP) is a stateless application-
level request/response protocol that uses extensible semantics and level 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:
* This document * This document
* "HTTP Semantics" [Semantics] * "HTTP Semantics" [HTTP]
* "HTTP Caching" [Caching] * "HTTP Caching" [CACHING]
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 HTTP/1.1 message syntax, framing and connection management
mechanisms. Its goal is to define the complete set of requirements mechanisms. Its goal is to define the complete set of requirements
for HTTP/1.1 message parsers and message-forwarding intermediaries. for HTTP/1.1 message parsers and message-forwarding intermediaries.
This document obsoletes the portions of RFC 7230 related to HTTP/1.1 This document obsoletes the portions of RFC 7230 related to HTTP/1.1
messaging and connection management, with the changes being messaging and connection management, with the changes being
summarized in Appendix C.3. The other parts of RFC 7230 are summarized in Appendix C.3. The other parts of RFC 7230 are
obsoleted by "HTTP Semantics" [Semantics]. obsoleted by "HTTP Semantics" [HTTP].
1.1. Requirements Notation 1.1. Requirements Notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
Conformance criteria and considerations regarding error handling are Conformance criteria and considerations regarding error handling are
defined in Section 2 of [Semantics]. defined in Section 2 of [HTTP].
1.2. Syntax Notation 1.2. Syntax Notation
This specification uses the Augmented Backus-Naur Form (ABNF) This specification uses the Augmented Backus-Naur Form (ABNF)
notation of [RFC5234], extended with the notation for case- notation of [RFC5234], extended with the notation for case-
sensitivity in strings defined in [RFC7405]. sensitivity in strings defined in [RFC7405].
It also uses a list extension, defined in Section 5.6.1 of It also uses a list extension, defined in Section 5.6.1 of [HTTP],
[Semantics], that allows for compact definition of comma-separated that allows for compact definition of comma-separated lists using a
lists using a '#' operator (similar to how the '*' operator indicates '#' operator (similar to how the '*' operator indicates repetition).
repetition). Appendix A shows the collected grammar with all list Appendix A shows the collected grammar with all list operators
operators expanded to standard ABNF notation. expanded to standard ABNF notation.
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.
The following core rules are included by reference, as defined in The following core rules are included by reference, as defined in
[RFC5234], Appendix B.1: ALPHA (letters), CR (carriage return), CRLF [RFC5234], Appendix B.1: ALPHA (letters), CR (carriage return), CRLF
(CR LF), CTL (controls), DIGIT (decimal 0-9), DQUOTE (double quote), (CR LF), CTL (controls), DIGIT (decimal 0-9), DQUOTE (double quote),
HEXDIG (hexadecimal 0-9/A-F/a-f), HTAB (horizontal tab), LF (line HEXDIG (hexadecimal 0-9/A-F/a-f), HTAB (horizontal tab), LF (line
feed), OCTET (any 8-bit sequence of data), SP (space), and VCHAR (any feed), OCTET (any 8-bit sequence of data), SP (space), and VCHAR (any
visible [USASCII] character). visible [USASCII] character).
The rules below are defined in [Semantics]: The rules below are defined in [HTTP]:
BWS = <BWS, see [Semantics], Section 5.6.3> BWS = <BWS, see [HTTP], Section 5.6.3>
OWS = <OWS, see [Semantics], Section 5.6.3> OWS = <OWS, see [HTTP], Section 5.6.3>
RWS = <RWS, see [Semantics], Section 5.6.3> RWS = <RWS, see [HTTP], Section 5.6.3>
absolute-path = <absolute-path, see [Semantics], Section 4> absolute-path = <absolute-path, see [HTTP], Section 4>
field-name = <field-name, see [Semantics], Section 5.1> field-name = <field-name, see [HTTP], Section 5.1>
field-value = <field-value, see [Semantics], Section 5.5> field-value = <field-value, see [HTTP], Section 5.5>
obs-text = <obs-text, see [Semantics], Section 5.6.4> obs-text = <obs-text, see [HTTP], Section 5.6.4>
quoted-string = <quoted-string, see [Semantics], Section 5.6.4> quoted-string = <quoted-string, see [HTTP], Section 5.6.4>
token = <token, see [Semantics], Section 5.6.2> token = <token, see [HTTP], Section 5.6.2>
transfer-coding = transfer-coding =
<transfer-coding, see [Semantics], Section 10.1.4> <transfer-coding, see [HTTP], Section 10.1.4>
The rules below are defined in [RFC3986]: The rules below are defined in [URI]:
absolute-URI = <absolute-URI, see [RFC3986], Section 4.3> absolute-URI = <absolute-URI, see [URI], Section 4.3>
authority = <authority, see [RFC3986], Section 3.2> authority = <authority, see [URI], Section 3.2>
uri-host = <host, see [RFC3986], Section 3.2.2> uri-host = <host, see [URI], Section 3.2.2>
port = <port, see [RFC3986], Section 3.2.3> port = <port, see [URI], Section 3.2.3>
query = <query, see [RFC3986], Section 3.4> query = <query, see [URI], Section 3.4>
2. Message 2. Message
HTTP/1.1 communication consists of sending stateless request and
response messages across a connection. See Section 3 of [HTTP] for
the general terminology and core concepts of HTTP.
2.1. Message Format 2.1. Message Format
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 octets in a format similar to the Internet Message Format sequence of octets in a format similar to the Internet Message Format
[RFC5322]: zero or more header field lines (collectively referred to [RFC5322]: zero or more header field lines (collectively referred to
as the "headers" or the "header section"), an empty line indicating as the "headers" or the "header section"), an empty line indicating
the end of the header section, and an optional message body. the end of the header section, and an optional message body.
HTTP-message = start-line CRLF HTTP-message = start-line CRLF
*( field-line CRLF ) *( field-line CRLF )
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determining the length of the message body (Section 6). determining the length of the message body (Section 6).
start-line = request-line / status-line start-line = request-line / status-line
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 (a In practice, servers are implemented to only expect a request (a
response is interpreted as an unknown or invalid request method) and response is interpreted as an unknown or invalid request method) and
clients are implemented to only expect a response. clients are implemented to only expect a response.
Although HTTP makes use of some protocol elements similar to the HTTP makes use of some protocol elements similar to the Multipurpose
Multipurpose Internet Mail Extensions (MIME) [RFC2045], see Internet Mail Extensions (MIME) [RFC2045]. See Appendix B for the
Appendix B for the differences between HTTP and MIME messages. differences between HTTP and MIME messages.
2.2. Message Parsing 2.2. Message Parsing
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
has been indicated, then it is read as a stream until an amount of has been indicated, then it is read as a stream until an amount of
octets equal to the message body length is read or the connection is octets equal to the message body length is read or the connection is
closed. closed.
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what appears from the start-line to be an HTTP request message, what appears from the start-line to be an HTTP request message,
receives a sequence of octets that does not match the HTTP-message receives a sequence of octets that does not match the HTTP-message
grammar aside from the robustness exceptions listed above, the server grammar aside from the robustness exceptions listed above, the server
SHOULD respond with a 400 (Bad Request) response and close the SHOULD respond with a 400 (Bad Request) response and close the
connection. connection.
2.3. HTTP Version 2.3. HTTP Version
HTTP uses a "<major>.<minor>" numbering scheme to indicate versions HTTP uses a "<major>.<minor>" numbering scheme to indicate versions
of the protocol. This specification defines version "1.1". of the protocol. This specification defines version "1.1".
Section 2.5 of [Semantics] specifies the semantics of HTTP version Section 2.5 of [HTTP] specifies the semantics of HTTP version
numbers. numbers.
The version of an HTTP/1.x message is indicated by an HTTP-version The version of an HTTP/1.x message is indicated by an HTTP-version
field in the start-line. HTTP-version is case-sensitive. field in the start-line. HTTP-version is case-sensitive.
HTTP-version = HTTP-name "/" DIGIT "." DIGIT HTTP-version = HTTP-name "/" DIGIT "." DIGIT
HTTP-name = %s"HTTP" HTTP-name = %s"HTTP"
When an HTTP/1.1 message is sent to an HTTP/1.0 recipient [RFC1945] When an HTTP/1.1 message is sent to an HTTP/1.0 recipient [HTTP/1.0]
or a recipient whose version is unknown, the HTTP/1.1 message is or a recipient whose version is unknown, the HTTP/1.1 message is
constructed such that it can be interpreted as a valid HTTP/1.0 constructed such that it can be interpreted as a valid HTTP/1.0
message if all of the newer features are ignored. This specification message if all of the newer features are ignored. This specification
places recipient-version requirements on some new features so that a places recipient-version requirements on some new features so that a
conformant sender will only use compatible features until it has conformant sender will only use compatible features until it has
determined, through configuration or the receipt of a message, that determined, through configuration or the receipt of a message, that
the recipient supports HTTP/1.1. the recipient supports HTTP/1.1.
Intermediaries that process HTTP messages (i.e., all intermediaries Intermediaries that process HTTP messages (i.e., all intermediaries
other than those acting as tunnels) MUST send their own HTTP-version other than those acting as tunnels) MUST send their own HTTP-version
skipping to change at page 9, line 44 skipping to change at page 9, line 48
instead parse on whitespace-delimited word boundaries and, aside from instead parse on whitespace-delimited word boundaries and, aside from
the CRLF terminator, treat any form of whitespace as the SP separator the CRLF terminator, treat any form of whitespace as the SP separator
while ignoring preceding or trailing whitespace; such whitespace while ignoring preceding or trailing whitespace; such whitespace
includes one or more of the following octets: SP, HTAB, VT (%x0B), FF includes one or more of the following octets: SP, HTAB, VT (%x0B), FF
(%x0C), or bare CR. However, lenient parsing can result in request (%x0C), or bare CR. However, lenient parsing can result in request
smuggling security vulnerabilities if there are multiple recipients smuggling security vulnerabilities if there are multiple recipients
of the message and each has its own unique interpretation of of the message and each has its own unique interpretation of
robustness (see Section 11.2). robustness (see Section 11.2).
HTTP does not place a predefined limit on the length of a request- HTTP does not place a predefined limit on the length of a request-
line, as described in Section 2 of [Semantics]. A server that line, as described in Section 2 of [HTTP]. A server that receives a
receives a method longer than any that it implements SHOULD respond method longer than any that it implements SHOULD respond with a 501
with a 501 (Not Implemented) status code. A server that receives a (Not Implemented) status code. A server that receives a request-
request-target longer than any URI it wishes to parse MUST respond target longer than any URI it wishes to parse MUST respond with a 414
with a 414 (URI Too Long) status code (see Section 15.5.15 of (URI Too Long) status code (see Section 15.5.15 of [HTTP]).
[Semantics]).
Various ad hoc limitations on request-line length are found in Various ad hoc limitations on request-line length are found in
practice. It is RECOMMENDED that all HTTP senders and recipients practice. It is RECOMMENDED that all HTTP senders and recipients
support, at a minimum, request-line lengths of 8000 octets. support, at a minimum, request-line lengths of 8000 octets.
3.1. Method 3.1. Method
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.
method = token method = token
The request methods defined by this specification can be found in The request methods defined by this specification can be found in
Section 9 of [Semantics], along with information regarding the HTTP Section 9 of [HTTP], along with information regarding the HTTP method
method registry and considerations for defining new methods. registry and considerations for defining new methods.
3.2. Request Target 3.2. Request Target
The request-target identifies the target resource upon which to apply The request-target identifies the target resource upon which to apply
the request. The client derives a request-target from its desired the request. The client derives a request-target from its desired
target URI. There are four distinct formats for the request-target, target URI. There are four distinct formats for the request-target,
depending on both the method being requested and whether the request depending on both the method being requested and whether the request
is to a proxy. is to a proxy.
request-target = origin-form request-target = origin-form
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400 (Bad Request) error or a 301 (Moved Permanently) redirect with 400 (Bad Request) error or a 301 (Moved Permanently) redirect with
the request-target properly encoded. A recipient SHOULD NOT attempt the request-target properly encoded. A recipient SHOULD NOT attempt
to autocorrect and then process the request without a redirect, since to autocorrect and then process the request without a redirect, since
the invalid request-line might be deliberately crafted to bypass the invalid request-line might be deliberately crafted to bypass
security filters along the request chain. security filters along the request chain.
A client MUST send a Host header field in all HTTP/1.1 request A client MUST send a Host header field in all HTTP/1.1 request
messages. If the target URI includes an authority component, then a messages. If the target URI includes an authority component, then a
client MUST send a field value for Host that is identical to that client MUST send a field value for Host that is identical to that
authority component, excluding any userinfo subcomponent and its "@" authority component, excluding any userinfo subcomponent and its "@"
delimiter (Section 4.2.1 of [Semantics]). If the authority component delimiter (Section 4.2.1 of [HTTP]). If the authority component is
is missing or undefined for the target URI, then a client MUST send a missing or undefined for the target URI, then a client MUST send a
Host header field with an empty field value. Host header field with an empty field value.
A server MUST respond with a 400 (Bad Request) status code to any A server MUST 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 or request message that contains more than one Host header field line or
a Host header field with an invalid field value. a Host header field with an invalid field value.
3.2.1. origin-form 3.2.1. origin-form
The most common form of request-target is the _origin-form_. The most common form of request-target is the _origin-form_.
origin-form = absolute-path [ "?" query ] origin-form = absolute-path [ "?" query ]
When making a request directly to an origin server, other than a When making a request directly to an origin server, other than a
CONNECT or server-wide OPTIONS request (as detailed below), a client CONNECT or server-wide OPTIONS request (as detailed below), a client
MUST send only the absolute path and query components of the target MUST send only the absolute path and query components of the target
URI as the request-target. If the target URI's path component is URI as the request-target. If the target URI's path component is
empty, the client MUST send "/" as the path within the origin-form of empty, the client MUST send "/" as the path within the origin-form of
request-target. A Host header field is also sent, as defined in request-target. A Host header field is also sent, as defined in
Section 7.2 of [Semantics]. Section 7.2 of [HTTP].
For example, a client wishing to retrieve a representation of the For example, a client wishing to retrieve a representation of the
resource identified as resource identified as
http://www.example.org/where?q=now http://www.example.org/where?q=now
directly from the origin server would open (or reuse) a TCP directly from the origin server would open (or reuse) a TCP
connection to port 80 of the host "www.example.org" and send the connection to port 80 of the host "www.example.org" and send the
lines: lines:
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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 MUST send the target OPTIONS request (as detailed below), a client MUST send the target
URI in _absolute-form_ as the request-target. URI in _absolute-form_ as the request-target.
absolute-form = absolute-URI absolute-form = absolute-URI
The proxy is requested to either service that request from a valid 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 cache, if possible, or make the same request on the client's behalf
to either the next inbound proxy server or directly to the origin to either the next inbound proxy server or directly to the origin
server indicated by the request-target. Requirements on such server indicated by the request-target. Requirements on such
"forwarding" of messages are defined in Section 7.6 of [Semantics]. "forwarding" of messages are defined in Section 7.6 of [HTTP].
An example absolute-form of request-line would be: An example absolute-form of request-line would be:
GET http://www.example.org/pub/WWW/TheProject.html HTTP/1.1 GET http://www.example.org/pub/WWW/TheProject.html HTTP/1.1
A client MUST send a Host header field in an HTTP/1.1 request even if A client MUST send a Host header field in an HTTP/1.1 request even if
the request-target is in the absolute-form, since this allows the the request-target is in the absolute-form, since this allows the
Host information to be forwarded through ancient HTTP/1.0 proxies Host information to be forwarded through ancient HTTP/1.0 proxies
that might not have implemented Host. that might not have implemented Host.
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Host field value based on the received request-target rather than Host field value based on the received request-target rather than
forward the received Host field value. forward the received Host field value.
When an origin server receives a request with an absolute-form of When an origin server receives a request with an absolute-form of
request-target, the origin server MUST ignore the received Host request-target, the origin server MUST ignore the received Host
header field (if any) and instead use the host information of the header field (if any) and instead use the host information of the
request-target. Note that if the request-target does not have an request-target. Note that if the request-target does not have an
authority component, an empty Host header field will be sent in this authority component, an empty Host header field will be sent in this
case. case.
To allow for transition to the absolute-form for all requests in some A server MUST accept the absolute-form in requests even though most
future version of HTTP, a server MUST accept the absolute-form in HTTP/1.1 clients will only send the absolute-form to a proxy.
requests, even though HTTP/1.1 clients will only send them in
requests to proxies.
3.2.3. authority-form 3.2.3. authority-form
The _authority-form_ of request-target is only used for CONNECT The _authority-form_ of request-target is only used for CONNECT
requests (Section 9.3.6 of [Semantics]). It consists of only the requests (Section 9.3.6 of [HTTP]). It consists of only the uri-host
uri-host and port number of the tunnel destination, separated by a and port number of the tunnel destination, separated by a colon
colon (":"). (":").
authority-form = uri-host ":" port authority-form = uri-host ":" port
When making a CONNECT request to establish a tunnel through one or When making a CONNECT request to establish a tunnel through one or
more proxies, a client MUST send only the host and port of the tunnel more proxies, a client MUST send only the host and port of the tunnel
destination as the request-target. The client obtains the host and destination as the request-target. The client obtains the host and
port from the target URI's authority component, except that it sends port from the target URI's authority component, except that it sends
the scheme's default port if the target URI elides the port. For the scheme's default port if the target URI elides the port. For
example, a CONNECT request to "http://www.example.com" looks like example, a CONNECT request to "http://www.example.com" looks like
CONNECT www.example.com:80 HTTP/1.1 CONNECT www.example.com:80 HTTP/1.1
Host: www.example.com Host: www.example.com
3.2.4. asterisk-form 3.2.4. asterisk-form
The _asterisk-form_ 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 (Section 9.3.7 of [Semantics]). OPTIONS request (Section 9.3.7 of [HTTP]).
asterisk-form = "*" asterisk-form = "*"
When a client wishes to request OPTIONS for the server as a whole, as When a client wishes to request OPTIONS for the server as a whole, as
opposed to a specific named resource of that server, the client MUST opposed to a specific named resource of that server, the client MUST
send only "*" (%x2A) as the request-target. For example, send only "*" (%x2A) as the request-target. For example,
OPTIONS * HTTP/1.1 OPTIONS * HTTP/1.1
If a proxy receives an OPTIONS request with an absolute-form of If a proxy receives an OPTIONS request with an absolute-form of
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after connecting to port 8001 of host "www.example.org". after connecting to port 8001 of host "www.example.org".
3.3. Reconstructing the Target URI 3.3. Reconstructing the Target URI
The target URI is the request-target when the request-target is in The target URI is the request-target when the request-target is in
absolute-form. In that case, a server will parse the URI into its absolute-form. In that case, a server will parse the URI into its
generic components for further evaluation. generic components for further evaluation.
Otherwise, the server reconstructs the target URI from the connection Otherwise, the server reconstructs the target URI from the connection
context and various parts of the request message in order to identify context and various parts of the request message in order to identify
the target resource (Section 7.1 of [Semantics]): the target resource (Section 7.1 of [HTTP]):
* If the server's configuration provides for a fixed URI scheme, or * If the server's configuration provides for a fixed URI scheme, or
a scheme is provided by a trusted outbound gateway, that scheme is a scheme is provided by a trusted outbound gateway, that scheme is
used for the target URI. This is common in large-scale used for the target URI. This is common in large-scale
deployments because a gateway server will receive the client's deployments because a gateway server will receive the client's
connection context and replace that with their own connection to connection context and replace that with their own connection to
the inbound server. Otherwise, if the request is received over a the inbound server. Otherwise, if the request is received over a
secured connection, the target URI's scheme is "https"; if not, secured connection, the target URI's scheme is "https"; if not,
the scheme is "http". the scheme is "http".
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the user agent's intended authority might differ from the selected the user agent's intended authority might differ from the selected
default. A server that can uniquely identify an authority from the default. A server that can uniquely identify an authority from the
request context MAY use that identity as a default without this risk. request context MAY 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
resource that explains how to obtain a new client. resource that explains how to obtain a new client.
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 process for identifying a target resource. The other half is
determining whether that target URI identifies a resource for which determining whether that target URI identifies a resource for which
the server is willing and able to send a response, as defined in the server is willing and able to send a response, as defined in
Section 7.4 of [Semantics]. Section 7.4 of [HTTP].
4. Status Line 4. Status Line
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 of the protocol version, a space (SP), the status code, another
space, and ending with an OPTIONAL textual phrase describing the space, and ending with an OPTIONAL textual phrase describing the
status code. status code.
status-line = HTTP-version SP status-code SP [reason-phrase] status-line = HTTP-version SP status-code SP [reason-phrase]
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includes one or more of the following octets: SP, HTAB, VT (%x0B), FF includes one or more of the following octets: SP, HTAB, VT (%x0B), FF
(%x0C), or bare CR. However, lenient parsing can result in response (%x0C), or bare CR. However, lenient parsing can result in response
splitting security vulnerabilities if there are multiple recipients splitting security vulnerabilities if there are multiple recipients
of the message and each has its own unique interpretation of of the message and each has its own unique interpretation of
robustness (see Section 11.1). robustness (see Section 11.1).
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. The rest of the response message is to be corresponding request. The rest of the response message is to be
interpreted in light of the semantics defined for that status code. interpreted in light of the semantics defined for that status code.
See Section 15 of [Semantics] for information about the semantics of See Section 15 of [HTTP] for information about the semantics of
status codes, including the classes of status code (indicated by the status codes, including the classes of status code (indicated by the
first digit), the status codes defined by this specification, first digit), the status codes defined by this specification,
considerations for the definition of new status codes, and the IANA considerations for the definition of new status codes, and the IANA
registry. registry.
status-code = 3DIGIT status-code = 3DIGIT
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 textual description associated with the numeric status code, mostly
out of deference to earlier Internet application protocols that were out of deference to earlier Internet application protocols that were
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5. Field Syntax 5. Field Syntax
Each field line consists of a case-insensitive field name followed by Each field line consists of a case-insensitive field name followed by
a colon (":"), optional leading whitespace, the field line value, and a colon (":"), optional leading whitespace, the field line value, and
optional trailing whitespace. optional trailing whitespace.
field-line = field-name ":" OWS field-value OWS field-line = field-name ":" OWS field-value OWS
Most HTTP field names and the rules for parsing within field values Most HTTP field names and the rules for parsing within field values
are defined in Section 6.3 of [Semantics]. This section covers the are defined in Section 6.3 of [HTTP]. This section covers the
generic syntax for header field inclusion within, and extraction generic syntax for header field inclusion within, and extraction
from, HTTP/1.1 messages. from, HTTP/1.1 messages.
5.1. Field Line Parsing 5.1. Field Line Parsing
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 individual field names. The contents within a given field line value
are not parsed until a later stage of message interpretation (usually are not parsed until a later stage of message interpretation (usually
after the message's entire field section has been processed). after the message's entire field section has been processed).
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message downstream. message downstream.
A user agent that receives an obs-fold in a response message that is A user agent that receives an obs-fold in a response message that is
not within a message/http container MUST replace each received not within a message/http container MUST replace each received
obs-fold with one or more SP octets prior to interpreting the field obs-fold with one or more SP octets prior to interpreting the field
value. value.
6. Message Body 6. Message Body
The message body (if any) of an HTTP/1.1 message is used to carry The message body (if any) of an HTTP/1.1 message is used to carry
content (Section 6.4 of [Semantics]) for the request or response. content (Section 6.4 of [HTTP]) for the request or response. The
The message body is identical to the content unless a transfer coding message body is identical to the content unless a transfer coding has
has been applied, as described in Section 6.1. been applied, as described in Section 6.1.
message-body = *OCTET message-body = *OCTET
The rules for determining when a message body is present in an The rules for determining when a message body is present in an
HTTP/1.1 message differ for requests and responses. HTTP/1.1 message differ for requests and responses.
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
Content-Length or Transfer-Encoding header field. Request message Content-Length or Transfer-Encoding header field. Request message
framing is independent of method semantics. framing is independent of method semantics.
The presence of a message body in a response depends on both the The presence of a message body in a response depends on both the
request method to which it is responding and the response status code request method to which it is responding and the response status code
(Section 4), and corresponds to when content is allowed; see (Section 4), and corresponds to when content is allowed; see
Section 6.4 of [Semantics]. Section 6.4 of [HTTP].
6.1. Transfer-Encoding 6.1. Transfer-Encoding
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 (or corresponding to the sequence of transfer codings that have been (or
will be) applied to the content in order to form the message body. will be) applied to the content in order to form the message body.
Transfer codings are defined in Section 7. Transfer codings are defined in Section 7.
Transfer-Encoding = #transfer-coding Transfer-Encoding = #transfer-coding
; defined in [Semantics], Section 10.1.4 ; defined in [HTTP], Section 10.1.4
Transfer-Encoding is analogous to the Content-Transfer-Encoding field Transfer-Encoding is analogous to the Content-Transfer-Encoding field
of MIME, which was designed to enable safe transport of binary data of MIME, which was designed to enable safe transport of binary data
over a 7-bit transport service ([RFC2045], Section 6). However, safe over a 7-bit transport service ([RFC2045], Section 6). However, safe
transport has a different focus for an 8bit-clean transfer protocol. transport has a different focus for an 8bit-clean transfer protocol.
In HTTP's case, Transfer-Encoding is primarily intended to accurately In HTTP's case, Transfer-Encoding is primarily intended to accurately
delimit dynamically generated content and to distinguish encodings delimit dynamically generated content and to distinguish encodings
that are only applied for transport efficiency or security from those that are only applied for transport efficiency or security from those
that are characteristics of the selected resource. that are characteristics of the selected resource.
A recipient MUST be able to parse the chunked transfer coding A recipient MUST be able to parse the chunked transfer coding
(Section 7.1) because it plays a crucial role in framing messages (Section 7.1) because it plays a crucial role in framing messages
when the content size is not known in advance. A sender MUST NOT when the content size is not known in advance. A sender MUST NOT
apply chunked more than once to a message body (i.e., chunking an apply the chunked transfer coding more than once to a message body
already chunked message is not allowed). If any transfer coding (i.e., chunking an already chunked message is not allowed). If any
other than chunked is applied to a request's content, the sender MUST transfer coding other than chunked is applied to a request's content,
apply chunked as the final transfer coding to ensure that the message the sender MUST apply chunked as the final transfer coding to ensure
is properly framed. If any transfer coding other than chunked is that the message is properly framed. If any transfer coding other
applied to a response's content, the sender MUST either apply chunked than chunked is applied to a response's content, the sender MUST
as the final transfer coding or terminate the message by closing the either apply chunked as the final transfer coding or terminate the
connection. message by closing the connection.
For example, For example,
Transfer-Encoding: gzip, chunked Transfer-Encoding: gzip, chunked
indicates that the content has been compressed using the gzip coding indicates that the content has been compressed using the gzip coding
and then chunked using the chunked coding while forming the message and then chunked using the chunked coding while forming the message
body. body.
Unlike Content-Encoding (Section 8.4.1 of [Semantics]), Transfer- Unlike Content-Encoding (Section 8.4.1 of [HTTP]), Transfer-Encoding
Encoding is a property of the message, not of the representation, and is a property of the message, not of the representation, and any
any recipient along the request/response chain MAY decode the recipient along the request/response chain MAY decode the received
received transfer coding(s) or apply additional transfer coding(s) to transfer coding(s) or apply additional transfer coding(s) to the
the message body, assuming that corresponding changes are made to the message body, assuming that corresponding changes are made to the
Transfer-Encoding field value. Additional information about the Transfer-Encoding field value. Additional information about the
encoding parameters can be provided by other header fields not encoding parameters can be provided by other header fields not
defined by this specification. defined by this specification.
Transfer-Encoding MAY be sent in a response to a HEAD request or in a Transfer-Encoding MAY be sent in a response to a HEAD request or in a
304 (Not Modified) response (Section 15.4.5 of [Semantics]) to a GET 304 (Not Modified) response (Section 15.4.5 of [HTTP]) to a GET
request, neither of which includes a message body, to indicate that request, neither of which includes a message body, to indicate that
the origin server would have applied a transfer coding to the message the origin server would have applied a transfer coding to the message
body if the request had been an unconditional GET. This indication body if the request had been an unconditional GET. This indication
is not required, however, because any recipient on the response chain is not required, however, because any recipient on the response chain
(including the origin server) can remove transfer codings when they (including the origin server) can remove transfer codings when they
are not needed. are not needed.
A server MUST NOT send a Transfer-Encoding header field in any A server MUST NOT send a Transfer-Encoding header field in any
response with a status code of 1xx (Informational) or 204 (No response with a status code of 1xx (Informational) or 204 (No
Content). A server MUST NOT send a Transfer-Encoding header field in Content). A server MUST NOT send a Transfer-Encoding header field in
any 2xx (Successful) response to a CONNECT request (Section 9.3.6 of any 2xx (Successful) response to a CONNECT request (Section 9.3.6 of
[Semantics]). [HTTP]).
A server that receives a request message with a transfer coding it
does not understand SHOULD respond with 501 (Not Implemented).
Transfer-Encoding was added in HTTP/1.1. It is generally assumed Transfer-Encoding was added in HTTP/1.1. It is generally assumed
that implementations advertising only HTTP/1.0 support will not that implementations advertising only HTTP/1.0 support will not
understand how to process transfer-encoded content. A client MUST understand how to process transfer-encoded content, and that an
NOT send a request containing Transfer-Encoding unless it knows the HTTP/1.0 message received with a Transfer-Encoding is likely to have
server will handle HTTP/1.1 requests (or later minor revisions); such been forwarded without proper handling of the chunked encoding in
knowledge might be in the form of specific user configuration or by transit.
remembering the version of a prior received response. A server MUST
NOT send a response containing Transfer-Encoding unless the
corresponding request indicates HTTP/1.1 (or later minor revisions).
A server that receives a request message with a transfer coding it A client MUST NOT send a request containing Transfer-Encoding unless
does not understand SHOULD respond with 501 (Not Implemented). it 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 remembering the version of a prior received
response. A server MUST NOT send a response containing Transfer-
Encoding unless the corresponding request indicates HTTP/1.1 (or
later minor revisions).
Early implementations of Transfer-Encoding would occasionally send
both a chunked encoding for message framing and an estimated Content-
Length header field for use by progress bars. This is why Transfer-
Encoding is defined as overriding Content-Length, as opposed to them
being mutually incompatible. Unfortunately, forwarding such a
message can lead to vulnerabilities regarding request smuggling
(Section 11.2) or response splitting (Section 11.1) attacks if any
downstream recipient fails to parse the message according to this
specification, particularly when a downstream recipient only
implements HTTP/1.0.
A server MAY reject a request that contains both Content-Length and
Transfer-Encoding or process such a request in accordance with the
Transfer-Encoding alone. Regardless, the server MUST close the
connection after responding to such a request to avoid the potential
attacks.
A server or client that receives an HTTP/1.0 message containing a
Transfer-Encoding header field MUST treat the message as if the
framing is faulty, even if a Content-Length is present, and close the
connection after processing the message. The message sender might
have retained a portion of the message, in buffer, that could be
misinterpreted by further use of the connection.
6.2. Content-Length 6.2. Content-Length
When a message does not have a Transfer-Encoding header field, a When a message does not have a Transfer-Encoding header field, a
Content-Length header field (Section 8.6 of [Semantics]) can provide Content-Length header field (Section 8.6 of [HTTP]) can provide the
the anticipated size, as a decimal number of octets, for potential anticipated size, as a decimal number of octets, for potential
content. For messages that do include content, the Content-Length content. For messages that do include content, the Content-Length
field value provides the framing information necessary for field value provides the framing information necessary for
determining where the data (and message) ends. For messages that do determining where the data (and message) ends. For messages that do
not include content, the Content-Length indicates the size of the not include content, the Content-Length indicates the size of the
selected representation (Section 8.6 of [Semantics]). selected representation (Section 8.6 of [HTTP]).
A sender MUST NOT send a Content-Length header field in any message A sender MUST NOT send a Content-Length header field in any message
that contains a Transfer-Encoding header field. that contains a Transfer-Encoding header field.
| *Note:* HTTP's use of Content-Length for message framing | *Note:* HTTP's use of Content-Length for message framing
| differs significantly from the same field's use in MIME, where | differs significantly from the same field's use in MIME, where
| it is an optional field used only within the "message/external- | it is an optional field used only within the "message/external-
| body" media-type. | body" media-type.
6.3. Message Body Length 6.3. Message Body Length
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If a Transfer-Encoding header field is present in a request and If a Transfer-Encoding header field is present in a request and
the chunked transfer coding is not the final encoding, the the chunked transfer coding is not the final encoding, the
message body length cannot be determined reliably; the server message body length cannot be determined reliably; the server
MUST respond with the 400 (Bad Request) status code and then MUST respond with the 400 (Bad Request) status code and then
close the connection. close the connection.
5. If a message is received without Transfer-Encoding and with an 5. If a message is received without Transfer-Encoding and with an
invalid Content-Length header field, then the message framing is invalid Content-Length header field, then the message framing is
invalid and the recipient MUST treat it as an unrecoverable invalid and the recipient MUST treat it as an unrecoverable
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 (Section 5.6.1 of [Semantics]), all values comma-separated list (Section 5.6.1 of [HTTP]), all values in the
in the list are valid, and all values in the list are the same. list are valid, and all values in the list are the same (in which
If this is a request message, the server MUST respond with a 400 case the message is processed with that single value used as the
(Bad Request) status code and then close the connection. If this Content-Length field value). If the unrecoverable error is in a
is a response message received by a proxy, the proxy MUST close request message, the server MUST respond with a 400 (Bad Request)
the connection to the server, discard the received response, and status code and then close the connection. If it is in a
send a 502 (Bad Gateway) response to the client. If this is a response message received by a proxy, the proxy MUST close the
connection to the server, discard the received response, and send
a 502 (Bad Gateway) response to the client. If it is in a
response message received by a user agent, the user agent MUST response message received by a user agent, the user agent MUST
close the connection to the server and discard the received close the connection to the server and discard the received
response. response.
6. If a valid Content-Length header field is present without 6. If a valid Content-Length header field is present without
Transfer-Encoding, its decimal value defines the expected message Transfer-Encoding, its decimal value defines the expected message
body length in octets. If the sender closes the connection or body length in octets. If the sender closes the connection or
the recipient times out before the indicated number of octets are the recipient times out before the indicated number of octets are
received, the recipient MUST consider the message to be received, the recipient MUST consider the message to be
incomplete and close the connection. incomplete and close the connection.
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Transfer coding names are used to indicate an encoding transformation Transfer coding names are used to indicate an encoding transformation
that has been, can be, or might need to be applied to a message's that has been, can be, or might need to be applied to a message's
content in order to ensure "safe transport" through the network. content in order to ensure "safe transport" through the network.
This differs from a content coding in that the transfer coding is a This differs from a content coding in that the transfer coding is a
property of the message rather than a property of the representation property of the message rather than a property of the representation
that is being transferred. that is being transferred.
All transfer-coding names are case-insensitive and ought to be All transfer-coding names are case-insensitive and ought to be
registered within the HTTP Transfer Coding registry, as defined in registered within the HTTP Transfer Coding registry, as defined in
Section 7.3. They are used in the Transfer-Encoding (Section 6.1) Section 7.3. They are used in the Transfer-Encoding (Section 6.1)
and TE (Section 10.1.4 of [Semantics]) header fields (the latter also and TE (Section 10.1.4 of [HTTP]) header fields (the latter also
defining the "transfer-coding" grammar). defining the "transfer-coding" grammar).
7.1. Chunked Transfer Coding 7.1. Chunked Transfer Coding
The chunked transfer coding wraps content in order to transfer it as The chunked transfer coding wraps content in order to transfer it as
a series of chunks, each with its own size indicator, followed by an a series of chunks, each with its own size indicator, followed by an
OPTIONAL trailer section containing trailer fields. Chunked enables OPTIONAL trailer section containing trailer fields. Chunked enables
content streams of unknown size to be transferred as a sequence of content streams of unknown size to be transferred as a sequence of
length-delimited buffers, which enables the sender to retain length-delimited buffers, which enables the sender to retain
connection persistence and the recipient to know when it has received connection persistence and the recipient to know when it has received
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by a trailer section, and finally terminated by an empty line. by a trailer section, and finally terminated by an empty line.
A recipient MUST be able to parse and decode the chunked transfer A recipient MUST be able to parse and decode the chunked transfer
coding. coding.
HTTP/1.1 does not define any means to limit the size of a chunked 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 response such that an intermediary can be assured of buffering the
entire response. Additionally, very large chunk sizes may cause entire response. Additionally, very large chunk sizes may cause
overflows or loss of precision if their values are not represented overflows or loss of precision if their values are not represented
accurately in a receiving implementation. Therefore, recipients MUST accurately in a receiving implementation. Therefore, recipients MUST
anticipate potentially large decimal numerals and prevent parsing anticipate potentially large hexadecimal numerals and prevent parsing
errors due to integer conversion overflows or precision loss due to errors due to integer conversion overflows or precision loss due to
integer representation. integer representation.
The chunked encoding does not define any parameters. Their presence The chunked encoding does not define any parameters. Their presence
SHOULD be treated as an error. SHOULD be treated as an error.
7.1.1. Chunk Extensions 7.1.1. Chunk Extensions
The chunked encoding allows each chunk to include zero or more chunk The chunked encoding allows each chunk to include zero or more chunk
extensions, immediately following the chunk-size, for the sake of extensions, immediately following the chunk-size, for the sake of
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parts of a message, and generate an appropriate 4xx (Client Error) parts of a message, and generate an appropriate 4xx (Client Error)
response if that amount is exceeded. response if that amount is exceeded.
7.1.2. Chunked Trailer Section 7.1.2. Chunked Trailer Section
A trailer section allows the sender to include additional fields at A trailer section allows the sender to include additional fields at
the end of a chunked message in order to supply metadata that might the end of a chunked message in order to supply metadata that might
be dynamically generated while the content is sent, such as a message be dynamically generated while the content is sent, such as a message
integrity check, digital signature, or post-processing status. The integrity check, digital signature, or post-processing status. The
proper use and limitations of trailer fields are defined in proper use and limitations of trailer fields are defined in
Section 6.5 of [Semantics]. Section 6.5 of [HTTP].
trailer-section = *( field-line CRLF ) trailer-section = *( field-line CRLF )
A recipient that decodes and removes the chunked encoding from a A recipient that decodes and removes the chunked encoding from a
message (e.g., for storage or forwarding to a non-HTTP/1.1 peer) MUST message (e.g., for storage or forwarding to a non-HTTP/1.1 peer) MUST
discard any received trailer fields, store/forward them separately discard any received trailer fields, store/forward them separately
from the header fields, or selectively merge into the header section from the header fields, or selectively merge into the header section
only those trailer fields corresponding to header field definitions only those trailer fields corresponding to header field definitions
that are understood by the recipient to explicitly permit and define that are understood by the recipient to explicitly permit and define
how their corresponding trailer field value can be safely merged. how their corresponding trailer field value can be safely merged.
skipping to change at page 25, line 35 skipping to change at page 26, line 11
} }
Content-Length := length Content-Length := length
Remove "chunked" from Transfer-Encoding Remove "chunked" from Transfer-Encoding
7.2. Transfer Codings for Compression 7.2. Transfer Codings for Compression
The following transfer coding names for compression are defined by The following transfer coding names for compression are defined by
the same algorithm as their corresponding content coding: the same algorithm as their corresponding content coding:
compress (and x-compress) compress (and x-compress)
See Section 8.4.1.1 of [Semantics]. See Section 8.4.1.1 of [HTTP].
deflate deflate
See Section 8.4.1.2 of [Semantics]. See Section 8.4.1.2 of [HTTP].
gzip (and x-gzip) gzip (and x-gzip)
See Section 8.4.1.3 of [Semantics]. See Section 8.4.1.3 of [HTTP].
The compression codings do not define any parameters. Their presence The compression codings do not define any parameters. The presence
SHOULD be treated as an error. of parameters with any of these compression codings SHOULD be treated
as an error.
7.3. Transfer Coding Registry 7.3. Transfer Coding Registry
The "HTTP Transfer Coding Registry" defines the namespace for The "HTTP Transfer Coding Registry" defines the namespace for
transfer coding names. It is maintained at transfer coding names. It is maintained at
<https://www.iana.org/assignments/http-parameters>. <https://www.iana.org/assignments/http-parameters>.
Registrations MUST include the following fields: Registrations MUST include the following fields:
* Name * Name
* Description * Description
* Pointer to specification text * Pointer to specification text
Names of transfer codings MUST NOT overlap with names of content Names of transfer codings MUST NOT overlap with names of content
codings (Section 8.4.1 of [Semantics]) unless the encoding codings (Section 8.4.1 of [HTTP]) unless the encoding transformation
transformation is identical, as is the case for the compression is identical, as is the case for the compression codings defined in
codings defined in Section 7.2. Section 7.2.
The TE header field (Section 10.1.4 of [Semantics]) uses a pseudo The TE header field (Section 10.1.4 of [HTTP]) uses a pseudo
parameter named "q" as rank value when multiple transfer codings are parameter named "q" as rank value when multiple transfer codings are
acceptable. Future registrations of transfer codings SHOULD NOT acceptable. Future registrations of transfer codings SHOULD NOT
define parameters called "q" (case-insensitively) in order to avoid define parameters called "q" (case-insensitively) in order to avoid
ambiguities. ambiguities.
Values to be added to this namespace require IETF Review (see Values to be added to this namespace require IETF Review (see
Section 4.8 of [RFC8126]), and MUST conform to the purpose of Section 4.8 of [RFC8126]), and MUST conform to the purpose of
transfer coding defined in this specification. transfer coding defined in this specification.
Use of program names for the identification of encoding formats is Use of program names for the identification of encoding formats is
not desirable and is discouraged for future encodings. not desirable and is discouraged for future encodings.
7.4. Negotiating Transfer Codings 7.4. Negotiating Transfer Codings
The TE field (Section 10.1.4 of [Semantics]) is used in HTTP/1.1 to The TE field (Section 10.1.4 of [HTTP]) is used in HTTP/1.1 to
indicate what transfer-codings, besides chunked, the client is indicate what transfer-codings, besides chunked, the client is
willing to accept in the response, and whether or not the client is willing to accept in the response, and whether the client is willing
willing to preserve trailer fields in a chunked transfer coding. to preserve trailer fields in a chunked transfer coding.
A client MUST NOT send the chunked transfer coding name in TE; A client MUST NOT 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.
Three examples of TE use are below. Three examples of TE use are below.
TE: deflate TE: deflate
TE: TE:
TE: trailers, deflate;q=0.5 TE: trailers, deflate;q=0.5
When multiple transfer codings are acceptable, the client MAY rank When multiple transfer codings are acceptable, the client MAY rank
the codings by preference using a case-insensitive "q" parameter the codings by preference using a case-insensitive "q" parameter
(similar to the qvalues used in content negotiation fields, (similar to the qvalues used in content negotiation fields,
Section 12.4.2 of [Semantics]). The rank value is a real number in Section 12.4.2 of [HTTP]). The rank value is a real number in the
the range 0 through 1, where 0.001 is the least preferred and 1 is range 0 through 1, where 0.001 is the least preferred and 1 is the
the most preferred; a value of 0 means "not acceptable". most preferred; a value of 0 means "not acceptable".
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 acceptable transfer coding is chunked. A message with no transfer
coding is always acceptable. coding is always acceptable.
The keyword "trailers" indicates that the sender will not discard The keyword "trailers" indicates that the sender will not discard
trailer fields, as described in Section 6.5 of [Semantics]. trailer fields, as described in Section 6.5 of [HTTP].
Since the TE header field only applies to the immediate connection, a Since the TE header field only applies to the immediate connection, a
sender of TE MUST also send a "TE" connection option within the sender of TE MUST also send a "TE" connection option within the
Connection header field (Section 7.6.1 of [Semantics]) in order to Connection header field (Section 7.6.1 of [HTTP]) in order to prevent
prevent the TE header field from being forwarded by intermediaries the TE header field from being forwarded by intermediaries that do
that do not support its semantics. not support its semantics.
8. Handling Incomplete Messages 8. Handling Incomplete Messages
A server that receives an incomplete request message, usually due to A server that receives an incomplete request message, usually due to
a canceled request or a triggered timeout exception, MAY send an a canceled request or a triggered timeout exception, MAY send an
error response prior to closing the connection. error response prior to closing the connection.
A client that receives an incomplete response message, which can A client that receives an incomplete response message, which can
occur when a connection is closed prematurely or when decoding a occur when a connection is closed prematurely or when decoding a
supposedly chunked transfer coding fails, MUST record the message as supposedly chunked transfer coding fails, MUST record the message as
incomplete. Cache requirements for incomplete responses are defined incomplete. Cache requirements for incomplete responses are defined
in Section 3 of [Caching]. in Section 3 of [CACHING].
If a response terminates in the middle of the header section (before 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 the empty line is received) and the status code might rely on header
fields to convey the full meaning of the response, then the client fields to convey the full meaning of the response, then the client
cannot assume that meaning has been conveyed; the client might need cannot assume that meaning has been conveyed; the client might need
to repeat the request in order to determine what action to take next. to repeat the request in order to determine what action to take next.
A message body that uses the chunked transfer coding is incomplete if A message body that uses the chunked transfer coding is incomplete if
the zero-sized chunk that terminates the encoding has not been the zero-sized chunk that terminates the encoding has not been
received. A message that uses a valid Content-Length is incomplete received. A message that uses a valid Content-Length is incomplete
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9. Connection Management 9. Connection Management
HTTP messaging is independent of the underlying transport- or HTTP messaging is independent of the underlying transport- or
session-layer connection protocol(s). HTTP only presumes a reliable session-layer connection protocol(s). HTTP only presumes a reliable
transport with in-order delivery of requests and the corresponding transport with in-order delivery of requests and the corresponding
in-order delivery of responses. The mapping of HTTP request and in-order delivery of responses. The mapping of HTTP request and
response structures onto the data units of an underlying transport response structures onto the data units of an underlying transport
protocol is outside the scope of this specification. protocol is outside the scope of this specification.
As described in Section 7.3 of [Semantics], the specific connection As described in Section 7.3 of [HTTP], the specific connection
protocols to be used for an HTTP interaction are determined by client protocols to be used for an HTTP interaction are determined by client
configuration and the target URI. For example, the "http" URI scheme configuration and the target URI. For example, the "http" URI scheme
(Section 4.2.1 of [Semantics]) indicates a default connection of TCP (Section 4.2.1 of [HTTP]) indicates a default connection of TCP over
over IP, with a default TCP port of 80, but the client might be IP, with a default TCP port of 80, but the client might be configured
configured to use a proxy via some other connection, port, or to use a proxy via some other connection, port, or protocol.
protocol.
HTTP implementations are expected to engage in connection management, HTTP implementations are expected to engage in connection management,
which includes maintaining the state of current connections, which includes maintaining the state of current connections,
establishing a new connection or reusing an existing connection, establishing a new connection or reusing an existing connection,
processing messages received on a connection, detecting connection processing messages received on a connection, detecting connection
failures, and closing each connection. Most clients maintain failures, and closing each connection. Most clients maintain
multiple connections in parallel, including more than one connection multiple connections in parallel, including more than one connection
per server endpoint. Most servers are designed to maintain thousands per server endpoint. Most servers are designed to maintain thousands
of concurrent connections, while controlling request queues to enable of concurrent connections, while controlling request queues to enable
fair use and detect denial-of-service attacks. fair use and detect denial-of-service attacks.
9.1. Establishment 9.1. Establishment
It is beyond the scope of this specification to describe how It is beyond the scope of this specification to describe how
connections are established via various transport- or session-layer connections are established via various transport- or session-layer
protocols. Each connection applies to only one transport link. protocols. Each HTTP connection maps to one underlying transport
connection.
9.2. Associating a Response to a Request 9.2. Associating a Response to a Request
HTTP/1.1 does not include a request identifier for associating a HTTP/1.1 does not include a request identifier for associating a
given request message with its corresponding one or more response given request message with its corresponding one or more response
messages. Hence, it relies on the order of response arrival to messages. Hence, it relies on the order of response arrival to
correspond exactly to the order in which requests are made on the correspond exactly to the order in which requests are made on the
same connection. More than one response message per request only same connection. More than one response message per request only
occurs when one or more informational responses (1xx, see occurs when one or more informational responses (1xx, see
Section 15.2 of [Semantics]) precede a final response to the same Section 15.2 of [HTTP]) precede a final response to the same request.
request.
A client that has more than one outstanding request on a connection A client that has more than one outstanding request on a connection
MUST maintain a list of outstanding requests in the order sent and MUST maintain a list of outstanding requests in the order sent and
MUST associate each received response message on that connection to MUST associate each received response message on that connection to
the highest ordered request that has not yet received a final (non- the highest ordered request that has not yet received a final (non-
1xx) response. 1xx) response.
If an HTTP/1.1 client receives data on a connection that doesn't have If an HTTP/1.1 client receives data on a connection that doesn't have
any outstanding requests, it MUST NOT consider them to be a response any outstanding requests, it MUST NOT consider them to be a response
to a not-yet-issued request; it SHOULD close the connection, since to a not-yet-issued request; it SHOULD close the connection, since
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of one or more CRLF (which can be discarded, as per Section 2.2). of one or more CRLF (which can be discarded, as per Section 2.2).
9.3. Persistence 9.3. Persistence
HTTP/1.1 defaults to the use of _persistent connections_, allowing HTTP/1.1 defaults to the use of _persistent connections_, allowing
multiple requests and responses to be carried over a single multiple requests and responses to be carried over a single
connection. HTTP implementations SHOULD support persistent connection. HTTP implementations SHOULD support persistent
connections. connections.
A recipient determines whether a connection is persistent or not A recipient determines whether a connection is persistent or not
based on the most recently received message's protocol version and based on the protocol version and Connection header field
Connection header field (Section 7.6.1 of [Semantics]), if any: (Section 7.6.1 of [HTTP]) in the most recently received message, if
any:
* If the close connection option is present (Section 9.6), the * If the close connection option is present (Section 9.6), the
connection will not persist after the current response; else, connection will not persist after the current response; else,
* If the received protocol is HTTP/1.1 (or later), the connection * If the received protocol is HTTP/1.1 (or later), the connection
will persist after the current response; else, will persist after the current response; else,
* If the received protocol is HTTP/1.0, the "keep-alive" connection * If the received protocol is HTTP/1.0, the "keep-alive" connection
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
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See Appendix C.2.2 for more information on backwards compatibility See Appendix C.2.2 for more information on backwards compatibility
with HTTP/1.0 clients. with HTTP/1.0 clients.
9.3.1. Retrying Requests 9.3.1. Retrying Requests
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 from Implementations ought to anticipate the need to recover from
asynchronous close events. The conditions under which a client can 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
Section 9.2.2 of [Semantics]. Section 9.2.2 of [HTTP].
9.3.2. Pipelining 9.3.2. Pipelining
A client that supports persistent connections MAY _pipeline_ its A client that supports persistent connections MAY _pipeline_ its
requests (i.e., send multiple requests without waiting for each requests (i.e., send multiple requests without waiting for each
response). A server MAY process a sequence of pipelined requests in response). A server MAY process a sequence of pipelined requests in
parallel if they all have safe methods (Section 9.2.1 of parallel if they all have safe methods (Section 9.2.1 of [HTTP]), but
[Semantics]), but it MUST send the corresponding responses in the it MUST send the corresponding responses in the same order that the
same order that the requests were received. requests were received.
A client that pipelines requests SHOULD retry unanswered requests if A client that pipelines requests SHOULD retry unanswered requests if
the connection closes before it receives all of the corresponding the connection closes before it receives all of the corresponding
responses. When retrying pipelined requests after a failed responses. When retrying pipelined requests after a failed
connection (a connection not explicitly closed by the server in its connection (a connection not explicitly closed by the server in its
last complete response), a client MUST NOT pipeline immediately after last complete response), a client MUST NOT pipeline immediately after
connection establishment, since the first remaining request in the connection establishment, since the first remaining request in the
prior pipeline might have caused an error response that can be lost prior pipeline might have caused an error response that can be lost
again if multiple requests are sent on a prematurely closed again if multiple requests are sent on a prematurely closed
connection (see the TCP reset problem described in Section 9.6). connection (see the TCP reset problem described in Section 9.6).
Idempotent methods (Section 9.2.2 of [Semantics]) are significant to Idempotent methods (Section 9.2.2 of [HTTP]) are significant to
pipelining because they can be automatically retried after a pipelining because they can be automatically retried after a
connection failure. A user agent SHOULD NOT pipeline requests after connection failure. A user agent SHOULD NOT pipeline requests after
a non-idempotent method, until the final response status code for a non-idempotent method, until the final response status code for
that method has been received, unless the user agent has a means to that method has been received, unless the user agent has a means to
detect and recover from partial failure conditions involving the detect and recover from partial failure conditions involving the
pipelined sequence. pipelined sequence.
An intermediary that receives pipelined requests MAY pipeline those An intermediary that receives pipelined requests MAY pipeline those
requests when forwarding them inbound, since it can rely on the requests when forwarding them inbound, since it can rely on the
outbound user agent(s) to determine what requests can be safely outbound user agent(s) to determine what requests can be safely
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Previous revisions of HTTP gave a specific number of connections as a Previous revisions of HTTP gave a specific number of connections as a
ceiling, but this was found to be impractical for many applications. ceiling, but this was found to be impractical for many applications.
As a result, this specification does not mandate a particular maximum As a result, this specification does not mandate a particular maximum
number of connections but, instead, encourages clients to be number of connections but, instead, encourages clients to be
conservative when opening multiple connections. conservative when opening multiple connections.
Multiple connections are typically used to avoid the "head-of-line Multiple connections are typically used to avoid the "head-of-line
blocking" problem, wherein a request that takes significant server- blocking" problem, wherein a request that takes significant server-
side processing and/or transfers very large content would block side processing and/or transfers very large content would block
subsequent requests on the same connection. However, each connection subsequent requests on the same connection. However, each connection
consumes server resources. Furthermore, using multiple connections consumes server resources.
can cause undesirable side effects in congested networks.
Furthermore, using multiple connections can cause undesirable side
effects in congested networks. Using larger number of multiple
connections can also cause side effects in otherwise uncongested
networks, because their aggregate and initially synchronized sending
behavior can cause congestion that would not have been present if
fewer parallel connections had been used.
Note that a server might reject traffic that it deems abusive or Note that a server might reject traffic that it deems abusive or
characteristic of a denial-of-service attack, such as an excessive characteristic of a denial-of-service attack, such as an excessive
number of open connections from a single client. number of open connections from a single client.
9.5. Failures and Timeouts 9.5. Failures and Timeouts
Servers will usually have some timeout value beyond which they will Servers will usually have some timeout value beyond which they will
no longer maintain an inactive connection. Proxy servers might make no longer maintain an inactive connection. Proxy servers might make
this a higher value since it is likely that the client will be making this a higher value since it is likely that the client will be making
skipping to change at page 32, line 36 skipping to change at page 33, line 13
client sees a response that indicates the server does not wish to client sees a response that indicates the server does not wish to
receive the message body and is closing the connection, the client receive the message body and is closing the connection, the client
SHOULD immediately cease transmitting the body and close its side of SHOULD immediately cease transmitting the body and close its side of
the connection. the connection.
9.6. Tear-down 9.6. Tear-down
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. A will close this connection after completion of the response. A
sender SHOULD send a Connection header field (Section 7.6.1 of sender SHOULD send a Connection header field (Section 7.6.1 of
[Semantics]) containing the close connection option when it intends [HTTP]) containing the close connection option when it intends to
to close a connection. For example, close a connection. For example,
Connection: close Connection: close
as a request header field indicates that this is the last request 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 that the client will send on this connection, while in a response the
same field indicates that the server is going to close this same field indicates that the server is going to close this
connection after the response message is complete. connection after the response message is complete.
Note that the field name "Close" is reserved, since using that name Note that the field name "Close" is reserved, since using that name
as a header field might conflict with the close connection option. as a header field might conflict with the close connection option.
skipping to change at page 34, line 8 skipping to change at page 34, line 31
Note that a TCP connection that is half-closed by the client does not Note that a TCP connection that is half-closed by the client does not
delimit a request message, nor does it imply that the client is no delimit a request message, nor does it imply that the client is no
longer interested in a response. In general, transport signals longer interested in a response. In general, transport signals
cannot be relied upon to signal edge cases, since HTTP/1.1 is cannot be relied upon to signal edge cases, since HTTP/1.1 is
independent of transport. independent of transport.
9.7. TLS Connection Initiation 9.7. TLS Connection Initiation
Conceptually, HTTP/TLS is simply sending HTTP messages over a Conceptually, HTTP/TLS is simply sending HTTP messages over a
connection secured via TLS [RFC8446]. connection secured via TLS [TLS13].
The HTTP client also acts as the TLS client. It initiates a The HTTP client also acts as the TLS client. It initiates a
connection to the server on the appropriate port and sends the TLS connection to the server on the appropriate port and sends the TLS
ClientHello to begin the TLS handshake. When the TLS handshake has ClientHello to begin the TLS handshake. When the TLS handshake has
finished, the client may then initiate the first HTTP request. All finished, the client may then initiate the first HTTP request. All
HTTP data MUST be sent as TLS "application data", but is otherwise HTTP data MUST be sent as TLS "application data", but is otherwise
treated like a normal connection for HTTP (including potential reuse treated like a normal connection for HTTP (including potential reuse
as a persistent connection). as a persistent connection).
9.8. TLS Connection Closure 9.8. TLS Connection Closure
skipping to change at page 37, line 31 skipping to change at page 38, line 20
Restrictions on usage: N/A Restrictions on usage: N/A
Author: See Authors' Addresses section. Author: See Authors' Addresses section.
Change controller: IESG Change controller: IESG
11. Security Considerations 11. Security Considerations
This section is meant to inform developers, information providers, This section is meant to inform developers, information providers,
and users of known security considerations relevant to HTTP message and users about known security considerations relevant to HTTP
syntax and parsing. Security considerations about HTTP semantics, message syntax and parsing. Security considerations about HTTP
content, and routing are addressed in [Semantics]. semantics, content, and routing are addressed in [HTTP].
11.1. Response Splitting 11.1. Response Splitting
Response splitting (a.k.a, CRLF injection) is a common technique, Response splitting (a.k.a., CRLF injection) is a common technique,
used in various attacks on Web usage, that exploits the line-based used in various attacks on Web usage, that exploits the line-based
nature of HTTP message framing and the ordered association of nature of HTTP message framing and the ordered association of
requests to responses on persistent connections [Klein]. This requests to responses on persistent connections [Klein]. This
technique can be particularly damaging when the requests pass through technique can be particularly damaging when the requests pass through
a shared cache. a shared cache.
Response splitting exploits a vulnerability in servers (usually Response splitting exploits a vulnerability in servers (usually
within an application server) where an attacker can send encoded data within an application server) where an attacker can send encoded data
within some parameter of the request that is later decoded and echoed within some parameter of the request that is later decoded and echoed
within any of the response header fields of the response. If the within any of the response header fields of the response. If the
skipping to change at page 39, line 34 skipping to change at page 40, line 10
information is detected by the protocol to be incomplete, expired, or information is detected by the protocol to be incomplete, expired, or
corrupted during transfer. Such mechanisms might be selectively corrupted during transfer. Such mechanisms might be selectively
enabled via user agent extensions or the presence of message enabled via user agent extensions or the presence of message
integrity metadata in a response. integrity metadata in a response.
The "http" scheme provides no protection against accidental or The "http" scheme provides no protection against accidental or
malicious modification of messages. malicious modification of messages.
Extensions to the protocol might be used to mitigate the risk of Extensions to the protocol might be used to mitigate the risk of
unwanted modification of messages by intermediaries, even when the unwanted modification of messages by intermediaries, even when the
"https" scheme is used. Integrity might be assured by using hash "https" scheme is used. Integrity might be assured by using message
functions or digital signatures that are selectively added to authentication codes or digital signatures that are selectively added
messages via extensible metadata fields. to messages via extensible metadata fields.
11.4. Message Confidentiality 11.4. Message Confidentiality
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 confidentiality when that is desired. HTTP has been specifically
designed to be independent of the transport protocol, such that it designed to be independent of the transport protocol, such that it
can be used over many different forms of encrypted connection, with can be used over many forms of encrypted connection, with the
the selection of such transports being identified by the choice of selection of such transports being identified by the choice of URI
URI scheme or within user agent configuration. scheme or within user agent configuration.
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 Section 4.2.2 of confidential connection, as described in Section 4.2.2 of [HTTP].
[Semantics].
12. IANA Considerations 12. IANA Considerations
The change controller for the following registrations is: "IETF The change controller for the following registrations is: "IETF
(iesg@ietf.org) - Internet Engineering Task Force". (iesg@ietf.org) - Internet Engineering Task Force".
12.1. Field Name Registration 12.1. Field Name Registration
First, introduce the new "Hypertext Transfer Protocol (HTTP) Field First, introduce the new "Hypertext Transfer Protocol (HTTP) Field
Name Registry" at <https://www.iana.org/assignments/http-fields> as Name Registry" at <https://www.iana.org/assignments/http-fields> as
described in Section 18.4 of [Semantics]. described in Section 18.4 of [HTTP].
Then, please update the registry with the field names listed in the Then, please update the registry with the field names listed in the
table below: table below:
+===================+==========+======+============+ +===================+==========+======+============+
| Field Name | Status | Ref. | Comments | | Field Name | Status | Ref. | Comments |
+===================+==========+======+============+ +===================+==========+======+============+
| Close | standard | 9.6 | (reserved) | | Close | standard | 9.6 | (reserved) |
+-------------------+----------+------+------------+ +-------------------+----------+------+------------+
| MIME-Version | standard | B.1 | | | MIME-Version | standard | B.1 | |
skipping to change at page 41, line 35 skipping to change at page 41, line 49
| | compress) | 7.2 | | | compress) | 7.2 |
+------------+-------------------------------+-----------+ +------------+-------------------------------+-----------+
| x-gzip | Deprecated (alias for gzip) | Section | | x-gzip | Deprecated (alias for gzip) | Section |
| | | 7.2 | | | | 7.2 |
+------------+-------------------------------+-----------+ +------------+-------------------------------+-----------+
Table 2 Table 2
| *Note:* the coding name "trailers" is reserved because its use | *Note:* the coding name "trailers" is reserved because its use
| would conflict with the keyword "trailers" in the TE header | would conflict with the keyword "trailers" in the TE header
| field (Section 10.1.4 of [Semantics]). | field (Section 10.1.4 of [HTTP]).
12.4. ALPN Protocol ID Registration 12.4. ALPN Protocol ID Registration
Please update the "TLS Application-Layer Protocol Negotiation (ALPN) Please update the "TLS Application-Layer Protocol Negotiation (ALPN)
Protocol IDs" registry at <https://www.iana.org/assignments/tls- Protocol IDs" registry at <https://www.iana.org/assignments/tls-
extensiontype-values/tls-extensiontype-values.xhtml> with the extensiontype-values/tls-extensiontype-values.xhtml> with the
registration below: registration below:
+==========+=============================+================+ +==========+=============================+================+
| Protocol | Identification Sequence | Reference | | Protocol | Identification Sequence | Reference |
skipping to change at page 42, line 9 skipping to change at page 42, line 25
| HTTP/1.1 | 0x68 0x74 0x74 0x70 0x2f | (this | | HTTP/1.1 | 0x68 0x74 0x74 0x70 0x2f | (this |
| | 0x31 0x2e 0x31 ("http/1.1") | specification) | | | 0x31 0x2e 0x31 ("http/1.1") | specification) |
+----------+-----------------------------+----------------+ +----------+-----------------------------+----------------+
Table 3 Table 3
13. References 13. References
13.1. Normative References 13.1. Normative References
[Caching] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, [CACHING] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Caching", Work in Progress, Internet-Draft, Ed., "HTTP Caching", Work in Progress, Internet-Draft,
draft-ietf-httpbis-cache-16, 27 May 2021, draft-ietf-httpbis-cache-17, 26 July 2021,
<https://tools.ietf.org/html/draft-ietf-httpbis-cache-16>. <https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-
cache-17>.
[HTTP] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Semantics", Work in Progress, Internet-Draft,
draft-ietf-httpbis-semantics-17, 26 July 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-
semantics-17>.
[RFC1950] Deutsch, L.P. and J-L. Gailly, "ZLIB Compressed Data [RFC1950] Deutsch, L.P. and J-L. Gailly, "ZLIB Compressed Data
Format Specification version 3.3", RFC 1950, Format Specification version 3.3", RFC 1950,
DOI 10.17487/RFC1950, May 1996, DOI 10.17487/RFC1950, May 1996,
<https://www.rfc-editor.org/info/rfc1950>. <https://www.rfc-editor.org/info/rfc1950>.
[RFC1951] Deutsch, P., "DEFLATE Compressed Data Format Specification [RFC1951] Deutsch, P., "DEFLATE Compressed Data Format Specification
version 1.3", RFC 1951, DOI 10.17487/RFC1951, May 1996, version 1.3", RFC 1951, DOI 10.17487/RFC1951, May 1996,
<https://www.rfc-editor.org/info/rfc1951>. <https://www.rfc-editor.org/info/rfc1951>.
[RFC1952] Deutsch, P., Gailly, J-L., Adler, M., Deutsch, L.P., and [RFC1952] Deutsch, P., Gailly, J-L., Adler, M., Deutsch, L.P., and
G. Randers-Pehrson, "GZIP file format specification G. Randers-Pehrson, "GZIP file format specification
version 4.3", RFC 1952, DOI 10.17487/RFC1952, May 1996, version 4.3", RFC 1952, DOI 10.17487/RFC1952, May 1996,
<https://www.rfc-editor.org/info/rfc1952>. <https://www.rfc-editor.org/info/rfc1952>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008, DOI 10.17487/RFC5234, January 2008,
<https://www.rfc-editor.org/info/rfc5234>. <https://www.rfc-editor.org/info/rfc5234>.
[RFC7405] Kyzivat, P., "Case-Sensitive String Support in ABNF", [RFC7405] Kyzivat, P., "Case-Sensitive String Support in ABNF",
RFC 7405, DOI 10.17487/RFC7405, December 2014, RFC 7405, DOI 10.17487/RFC7405, December 2014,
<https://www.rfc-editor.org/info/rfc7405>. <https://www.rfc-editor.org/info/rfc7405>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol [TLS13] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>. <https://www.rfc-editor.org/info/rfc8446>.
[Semantics] [URI] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, Resource Identifier (URI): Generic Syntax", STD 66,
Ed., "HTTP Semantics", Work in Progress, Internet-Draft, RFC 3986, DOI 10.17487/RFC3986, January 2005,
draft-ietf-httpbis-semantics-16, 27 May 2021, <https://www.rfc-editor.org/info/rfc3986>.
<https://tools.ietf.org/html/draft-ietf-httpbis-semantics-
16>.
[USASCII] American National Standards Institute, "Coded Character [USASCII] American National Standards Institute, "Coded Character
Set -- 7-bit American Standard Code for Information Set -- 7-bit American Standard Code for Information
Interchange", ANSI X3.4, 1986. Interchange", ANSI X3.4, 1986.
[Welch] Welch, T. A., "A Technique for High-Performance Data [Welch] Welch, T. A., "A Technique for High-Performance Data
Compression", IEEE Computer 17(6), June 1984. Compression", IEEE Computer 17(6), June 1984.
13.2. Informative References 13.2. Informative References
[Err4667] RFC Errata, Erratum ID 4667, RFC 7230, [Err4667] RFC Errata, Erratum ID 4667, RFC 7230,
<https://www.rfc-editor.org/errata/eid4667>. <https://www.rfc-editor.org/errata/eid4667>.
[HTTP/1.0] Berners-Lee, T., Fielding, R.T., and H.F. Nielsen,
"Hypertext Transfer Protocol -- HTTP/1.0", RFC 1945,
DOI 10.17487/RFC1945, May 1996,
<https://www.rfc-editor.org/info/rfc1945>.
[Klein] Klein, A., "Divide and Conquer - HTTP Response Splitting, [Klein] Klein, A., "Divide and Conquer - HTTP Response Splitting,
Web Cache Poisoning Attacks, and Related Topics", March Web Cache Poisoning Attacks, and Related Topics", March
2004, <http://packetstormsecurity.com/papers/general/ 2004, <https://packetstormsecurity.com/papers/general/
whitepaper_httpresponse.pdf>. whitepaper_httpresponse.pdf>.
[Linhart] Linhart, C., Klein, A., Heled, R., and S. Orrin, "HTTP [Linhart] Linhart, C., Klein, A., Heled, R., and S. Orrin, "HTTP
Request Smuggling", June 2005, Request Smuggling", June 2005,
<https://www.cgisecurity.com/lib/HTTP-Request- <https://www.cgisecurity.com/lib/HTTP-Request-
Smuggling.pdf>. Smuggling.pdf>.
[RFC1945] Berners-Lee, T., Fielding, R.T., and H.F. Nielsen,
"Hypertext Transfer Protocol -- HTTP/1.0", RFC 1945,
DOI 10.17487/RFC1945, May 1996,
<https://www.rfc-editor.org/info/rfc1945>.
[RFC2045] Freed, N. and N.S. Borenstein, "Multipurpose Internet Mail [RFC2045] Freed, N. and N.S. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part One: Format of Internet Message Extensions (MIME) Part One: Format of Internet Message
Bodies", RFC 2045, DOI 10.17487/RFC2045, November 1996, Bodies", RFC 2045, DOI 10.17487/RFC2045, November 1996,
<https://www.rfc-editor.org/info/rfc2045>. <https://www.rfc-editor.org/info/rfc2045>.
[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail [RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046, Extensions (MIME) Part Two: Media Types", RFC 2046,
DOI 10.17487/RFC2046, November 1996, DOI 10.17487/RFC2046, November 1996,
<https://www.rfc-editor.org/info/rfc2046>. <https://www.rfc-editor.org/info/rfc2046>.
skipping to change at page 44, line 29 skipping to change at page 44, line 44
[RFC5322] Resnick, P., "Internet Message Format", RFC 5322, [RFC5322] Resnick, P., "Internet Message Format", RFC 5322,
DOI 10.17487/RFC5322, October 2008, DOI 10.17487/RFC5322, October 2008,
<https://www.rfc-editor.org/info/rfc5322>. <https://www.rfc-editor.org/info/rfc5322>.
[RFC7230] Fielding, R., Ed. and J. F. Reschke, Ed., "Hypertext [RFC7230] Fielding, R., Ed. and J. F. Reschke, Ed., "Hypertext
Transfer Protocol (HTTP/1.1): Message Syntax and Routing", Transfer Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014, RFC 7230, DOI 10.17487/RFC7230, June 2014,
<https://www.rfc-editor.org/info/rfc7230>. <https://www.rfc-editor.org/info/rfc7230>.
[RFC7231] Fielding, R., Ed. and J. F. Reschke, Ed., "Hypertext
Transfer Protocol (HTTP/1.1): Semantics and Content",
RFC 7231, DOI 10.17487/RFC7231, June 2014,
<https://www.rfc-editor.org/info/rfc7231>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26, Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017, RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>. <https://www.rfc-editor.org/info/rfc8126>.
Appendix A. Collected ABNF Appendix A. Collected ABNF
In the collected ABNF below, list rules are expanded as per In the collected ABNF below, list rules are expanded as per
Section 5.6.1.1 of [Semantics]. Section 5.6.1.1 of [HTTP].
BWS = <BWS, see [Semantics], 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 [Semantics], Section 5.6.3> OWS = <OWS, see [HTTP], Section 5.6.3>
RWS = <RWS, see [Semantics], Section 5.6.3>
RWS = <RWS, see [HTTP], Section 5.6.3>
Transfer-Encoding = [ transfer-coding *( OWS "," OWS transfer-coding Transfer-Encoding = [ transfer-coding *( OWS "," OWS transfer-coding
) ] ) ]
absolute-URI = <absolute-URI, see [RFC3986], Section 4.3> absolute-URI = <absolute-URI, see [URI], Section 4.3>
absolute-form = absolute-URI absolute-form = absolute-URI
absolute-path = <absolute-path, see [Semantics], Section 4> absolute-path = <absolute-path, see [HTTP], Section 4>
asterisk-form = "*" asterisk-form = "*"
authority = <authority, see [RFC3986], Section 3.2> authority = <authority, see [URI], Section 3.2>
authority-form = uri-host ":" port authority-form = uri-host ":" port
chunk = chunk-size [ chunk-ext ] CRLF chunk-data CRLF chunk = chunk-size [ chunk-ext ] CRLF chunk-data CRLF
chunk-data = 1*OCTET chunk-data = 1*OCTET
chunk-ext = *( BWS ";" BWS chunk-ext-name [ BWS "=" BWS chunk-ext-val chunk-ext = *( BWS ";" BWS chunk-ext-name [ 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
chunk-size = 1*HEXDIG chunk-size = 1*HEXDIG
chunked-body = *chunk last-chunk trailer-section CRLF chunked-body = *chunk last-chunk trailer-section CRLF
field-line = field-name ":" OWS field-value OWS field-line = field-name ":" OWS field-value OWS
field-name = <field-name, see [Semantics], Section 5.1> field-name = <field-name, see [HTTP], Section 5.1>
field-value = <field-value, see [Semantics], Section 5.5> field-value = <field-value, see [HTTP], Section 5.5>
last-chunk = 1*"0" [ chunk-ext ] CRLF last-chunk = 1*"0" [ chunk-ext ] CRLF
message-body = *OCTET message-body = *OCTET
method = token method = token
obs-fold = OWS CRLF RWS obs-fold = OWS CRLF RWS
obs-text = <obs-text, see [Semantics], Section 5.6.4> obs-text = <obs-text, see [HTTP], Section 5.6.4>
origin-form = absolute-path [ "?" query ] origin-form = absolute-path [ "?" query ]
port = <port, see [RFC3986], Section 3.2.3> port = <port, see [URI], Section 3.2.3>
query = <query, see [RFC3986], Section 3.4>
quoted-string = <quoted-string, see [Semantics], Section 5.6.4>
query = <query, see [URI], Section 3.4>
quoted-string = <quoted-string, see [HTTP], Section 5.6.4>
reason-phrase = 1*( HTAB / SP / VCHAR / obs-text ) reason-phrase = 1*( HTAB / SP / VCHAR / obs-text )
request-line = method SP request-target SP HTTP-version request-line = method SP request-target SP HTTP-version
request-target = origin-form / absolute-form / authority-form / request-target = origin-form / absolute-form / authority-form /
asterisk-form asterisk-form
start-line = request-line / status-line start-line = request-line / status-line
status-code = 3DIGIT status-code = 3DIGIT
status-line = HTTP-version SP status-code SP [ reason-phrase ] status-line = HTTP-version SP status-code SP [ reason-phrase ]
token = <token, see [Semantics], Section 5.6.2>
token = <token, see [HTTP], Section 5.6.2>
trailer-section = *( field-line CRLF ) trailer-section = *( field-line CRLF )
transfer-coding = <transfer-coding, see [Semantics], Section 10.1.4> transfer-coding = <transfer-coding, see [HTTP], Section 10.1.4>
uri-host = <host, see [RFC3986], Section 3.2.2> uri-host = <host, see [URI], Section 3.2.2>
Appendix B. Differences between HTTP and MIME Appendix B. Differences between HTTP and MIME
HTTP/1.1 uses many of the constructs defined for the Internet Message HTTP/1.1 uses many of the constructs defined for the Internet Message
Format [RFC5322] and the Multipurpose Internet Mail Extensions (MIME) Format [RFC5322] and the Multipurpose Internet Mail Extensions (MIME)
[RFC2045] to allow a message body to be transmitted in an open [RFC2045] to allow a message body to be transmitted in an open
variety of representations and with extensible fields. However, RFC variety of representations and with extensible fields. However, RFC
2045 is focused only on email; applications of HTTP have many 2045 is focused only on email; applications of HTTP have many
characteristics that differ from email; hence, HTTP has features that characteristics that differ from email; hence, HTTP has features that
differ from MIME. These differences were carefully chosen to differ from MIME. These differences were carefully chosen to
skipping to change at page 47, line 20 skipping to change at page 47, line 29
represent CR and LF, respectively. represent CR and LF, respectively.
Conversion will break any cryptographic checksums applied to the Conversion will break any cryptographic checksums applied to the
original content unless the original content is already in canonical original content unless the original content is already in canonical
form. Therefore, the canonical form is recommended for any content form. Therefore, the canonical form is recommended for any content
that uses such checksums in HTTP. that uses such checksums in HTTP.
B.3. Conversion of Date Formats B.3. Conversion of Date Formats
HTTP/1.1 uses a restricted set of date formats (Section 5.6.7 of HTTP/1.1 uses a restricted set of date formats (Section 5.6.7 of
[Semantics]) to simplify the process of date comparison. Proxies and [HTTP]) to simplify the process of date comparison. Proxies and
gateways from other protocols ought to ensure that any Date header gateways from other protocols ought to ensure that any Date header
field present in a message conforms to one of the HTTP/1.1 formats field present in a message conforms to one of the HTTP/1.1 formats
and rewrite the date if necessary. and rewrite the date if necessary.
B.4. Conversion of Content-Encoding B.4. Conversion of Content-Encoding
MIME does not include any concept equivalent to HTTP/1.1's Content- MIME does not include any concept equivalent to HTTP/1.1's Content-
Encoding header field. Since this acts as a modifier on the media Encoding header field. Since this acts as a modifier on the media
type, proxies and gateways from HTTP to MIME-compliant protocols type, proxies and gateways from HTTP to MIME-compliant protocols
ought to either change the value of the Content-Type header field or ought to either change the value of the Content-Type header field or
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B.6. MHTML and Line Length Limitations B.6. MHTML and Line Length Limitations
HTTP implementations that share code with MHTML [RFC2557] HTTP implementations that share code with MHTML [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 Since HTTP does not have this limitation, HTTP does not fold long
lines. MHTML messages being transported by HTTP follow all lines. MHTML messages being transported by HTTP follow all
conventions of MHTML, including line length limitations and folding, conventions of MHTML, including line length limitations and folding,
canonicalization, etc., since HTTP transfers message-bodies without canonicalization, etc., since HTTP transfers message-bodies without
modification and, aside from the "multipart/byteranges" type modification and, aside from the "multipart/byteranges" type
(Section 14.6 of [Semantics]), does not interpret the content or any (Section 14.6 of [HTTP]), does not interpret the content or any MIME
MIME header lines that might be contained therein. header lines that might be contained therein.
Appendix C. Changes from previous RFCs Appendix C. Changes from previous RFCs
C.1. Changes from HTTP/0.9 C.1. Changes from HTTP/0.9
Since HTTP/0.9 did not support header fields in a request, there is 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 no mechanism for it to support name-based virtual hosts (selection of
resource by inspection of the Host header field). Any server that resource by inspection of the Host header field). Any server that
implements name-based virtual hosts ought to disable support for implements name-based virtual hosts ought to disable support for
HTTP/0.9. Most requests that appear to be HTTP/0.9 are, in fact, 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 badly constructed HTTP/1.x requests caused by a client failing to
properly encode the request-target. properly encode the request-target.
C.2. Changes from HTTP/1.0 C.2. Changes from HTTP/1.0
C.2.1. Multihomed Web Servers C.2.1. Multihomed Web Servers
The requirements that clients and servers support the Host header The requirements that clients and servers support the Host header
field (Section 7.2 of [Semantics]), report an error if it is missing field (Section 7.2 of [HTTP]), report an error if it is missing from
from an HTTP/1.1 request, and accept absolute URIs (Section 3.2) are an HTTP/1.1 request, and accept absolute URIs (Section 3.2) are among
among the most important changes defined by HTTP/1.1. the most important changes defined by HTTP/1.1.
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 other established mechanism for
distinguishing the intended server of a request than the IP address distinguishing the intended server of a request 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 quickly implemented by most HTTP/1.0 browsers, additional
requirements were placed on all HTTP/1.1 requests in order to ensure requirements were placed on all HTTP/1.1 requests in order to ensure
complete adoption. At the time of this writing, most HTTP-based complete adoption. At the time of this writing, most HTTP-based
services are dependent upon the Host header field for targeting services are dependent upon the Host header field for targeting
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was also unworkable, because proxies are often deployed in multiple was also unworkable, because proxies are often deployed in multiple
layers, bringing about the same problem discussed above. layers, bringing about the same problem discussed above.
As a result, clients are encouraged not to send the Proxy-Connection As a result, clients are encouraged not to send the Proxy-Connection
header field in any requests. header field in any requests.
Clients are also encouraged to consider the use of Connection: keep- Clients are also encouraged to consider the use of Connection: keep-
alive in requests carefully; while they can enable persistent alive in requests carefully; while they can enable persistent
connections with HTTP/1.0 servers, clients using them will need to connections with HTTP/1.0 servers, clients using them will need to
monitor the connection for "hung" requests (which indicate that the monitor the connection for "hung" requests (which indicate that the
client ought stop sending the header field), and this mechanism ought client ought to stop sending the header field), and this mechanism
not be used by clients at all when a proxy is being used. ought not be used by clients at all when a proxy is being used.
C.2.3. Introduction of Transfer-Encoding C.2.3. Introduction of Transfer-Encoding
HTTP/1.1 introduces the Transfer-Encoding header field (Section 6.1). HTTP/1.1 introduces the Transfer-Encoding header field (Section 6.1).
Transfer codings need to be decoded prior to forwarding an HTTP Transfer codings need to be decoded prior to forwarding an HTTP
message over a MIME-compliant protocol. message over a MIME-compliant protocol.
C.3. Changes from RFC 7230 C.3. Changes from RFC 7230
Most of the sections introducing HTTP's design goals, history, Most of the sections introducing HTTP's design goals, history,
architecture, conformance criteria, protocol versioning, URIs, architecture, conformance criteria, protocol versioning, URIs,
message routing, and header fields have been moved to [Semantics]. message routing, and header fields have been moved to [HTTP]. This
This document has been reduced to just the messaging syntax and document has been reduced to just the messaging syntax and connection
connection management requirements specific to HTTP/1.1. management requirements specific to HTTP/1.1.
Bare CRs have been prohibited outside of content. (Section 2.2)
Prohibited generation of bare CRs outside of content. (Section 2.2)
The ABNF definition of authority-form has changed from the more The ABNF definition of authority-form has changed from the more
general authority component of a URI (in which port is optional) to 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.
(Section 3.2.3) (Section 3.2.3)
Required recipients to avoid smuggling/splitting attacks when
processing an ambiguous message framing. (Section 6.1)
In the ABNF for chunked extensions, re-introduced (bad) whitespace In the ABNF for chunked extensions, re-introduced (bad) whitespace
around ";" and "=". Whitespace was removed in [RFC7230], but that around ";" and "=". Whitespace was removed in [RFC7230], but that
change was found to break existing implementations (see [Err4667]). change was found to break existing implementations (see [Err4667]).
(Section 7.1.1) (Section 7.1.1)
Trailer field semantics now transcend the specifics of chunked Trailer field semantics now transcend the specifics of chunked
encoding. The decoding algorithm for chunked (Section 7.1.3) has encoding. The decoding algorithm for chunked (Section 7.1.3) has
been updated to encourage storage/forwarding of trailer fields been updated to encourage storage/forwarding of trailer fields
separately from the header section, to only allow merging into the separately from the header section, to only allow merging into the
header section if the recipient knows the corresponding field header section if the recipient knows the corresponding field
skipping to change at page 51, line 8 skipping to change at page 51, line 19
* Replace sections listing changes from RFC 2616 by new empty * Replace sections listing changes from RFC 2616 by new empty
sections referring to RFC 723x. sections referring to RFC 723x.
* Remove acknowledgements specific to RFC 723x. * Remove acknowledgements specific to RFC 723x.
* Move "Acknowledgements" to the very end and make them unnumbered. * Move "Acknowledgements" to the very end and make them unnumbered.
D.2. Since draft-ietf-httpbis-messaging-00 D.2. Since draft-ietf-httpbis-messaging-00
The changes in this draft are editorial, with respect to HTTP as a The changes in this draft are editorial, with respect to HTTP as a
whole, to move all core HTTP semantics into [Semantics]: whole, to move all core HTTP semantics into [HTTP]:
* Moved introduction, architecture, conformance, and ABNF extensions * Moved introduction, architecture, conformance, and ABNF extensions
from RFC 7230 (Messaging) to semantics [Semantics]. from RFC 7230 (Messaging) to semantics [HTTP].
* Moved discussion of MIME differences from RFC 7231 (Semantics) to * Moved discussion of MIME differences from RFC 7231 (Semantics) to
Appendix B since they mostly cover transforming 1.1 messages. Appendix B since they mostly cover transforming 1.1 messages.
* Moved all extensibility tips, registration procedures, and * Moved all extensibility tips, registration procedures, and
registry tables from the IANA considerations to normative registry tables from the IANA considerations to normative
sections, reducing the IANA considerations to just instructions sections, reducing the IANA considerations to just instructions
that will be removed prior to publication as an RFC. that will be removed prior to publication as an RFC.
D.3. Since draft-ietf-httpbis-messaging-01 D.3. Since draft-ietf-httpbis-messaging-01
skipping to change at page 52, line 35 skipping to change at page 52, line 44
* In Section 7, remove the predefined codings from the ABNF and make * In Section 7, remove the predefined codings from the ABNF and make
it generic instead (<https://github.com/httpwg/http-core/ it generic instead (<https://github.com/httpwg/http-core/
issues/66>) issues/66>)
* Use RFC 7405 ABNF notation for case-sensitive string constants * Use RFC 7405 ABNF notation for case-sensitive string constants
(<https://github.com/httpwg/http-core/issues/133>) (<https://github.com/httpwg/http-core/issues/133>)
D.6. Since draft-ietf-httpbis-messaging-04 D.6. Since draft-ietf-httpbis-messaging-04
* In Section 7.8 of [Semantics], clarify that protocol-name is to be * In Section 7.8 of [HTTP], clarify that protocol-name is to be
matched case-insensitively (<https://github.com/httpwg/http-core/ matched case-insensitively (<https://github.com/httpwg/http-core/
issues/8>) issues/8>)
* In Section 5.2, add leading optional whitespace to obs-fold ABNF * In Section 5.2, add leading optional whitespace to obs-fold ABNF
(<https://github.com/httpwg/http-core/issues/19>, (<https://github.com/httpwg/http-core/issues/19>,
<https://www.rfc-editor.org/errata/eid4189>) <https://www.rfc-editor.org/errata/eid4189>)
* In Section 4, add clarifications about empty reason phrases * In Section 4, add clarifications about empty reason phrases
(<https://github.com/httpwg/http-core/issues/197>) (<https://github.com/httpwg/http-core/issues/197>)
* Move discussion of retries from Section 9.3.1 into [Semantics] * Move discussion of retries from Section 9.3.1 into [HTTP]
(<https://github.com/httpwg/http-core/issues/230>) (<https://github.com/httpwg/http-core/issues/230>)
D.7. Since draft-ietf-httpbis-messaging-05 D.7. Since draft-ietf-httpbis-messaging-05
* In Section 7.1.2, the trailer part has been renamed the trailer * In Section 7.1.2, the trailer part has been renamed the trailer
section (for consistency with the header section) and trailers are section (for consistency with the header section) and trailers are
no longer merged as header fields by default, but rather can be no longer merged as header fields by default, but rather can be
discarded, kept separate from header fields, or merged with header discarded, kept separate from header fields, or merged with header
fields only if understood and defined as being mergeable fields only if understood and defined as being mergeable
(<https://github.com/httpwg/http-core/issues/16>) (<https://github.com/httpwg/http-core/issues/16>)
* In Section 2.1 and related Sections, move the trailing CRLF from * In Section 2.1 and related Sections, move the trailing CRLF from
the line grammars into the message format the line grammars into the message format
(<https://github.com/httpwg/http-core/issues/62>) (<https://github.com/httpwg/http-core/issues/62>)
skipping to change at page 53, line 18 skipping to change at page 53, line 27
fields only if understood and defined as being mergeable fields only if understood and defined as being mergeable
(<https://github.com/httpwg/http-core/issues/16>) (<https://github.com/httpwg/http-core/issues/16>)
* In Section 2.1 and related Sections, move the trailing CRLF from * In Section 2.1 and related Sections, move the trailing CRLF from
the line grammars into the message format the line grammars into the message format
(<https://github.com/httpwg/http-core/issues/62>) (<https://github.com/httpwg/http-core/issues/62>)
* Moved Section 2.3 down (<https://github.com/httpwg/http-core/ * Moved Section 2.3 down (<https://github.com/httpwg/http-core/
issues/68>) issues/68>)
* In Section 7.8 of [Semantics], use 'websocket' instead of * In Section 7.8 of [HTTP], use 'websocket' instead of 'HTTP/2.0' in
'HTTP/2.0' in examples (<https://github.com/httpwg/http-core/ examples (<https://github.com/httpwg/http-core/issues/112>)
issues/112>)
* Move version non-specific text from Section 6 into semantics as * Move version non-specific text from Section 6 into semantics as
"payload" (<https://github.com/httpwg/http-core/issues/159>) "payload" (<https://github.com/httpwg/http-core/issues/159>)
* In Section 9.8, add text from RFC 2818 * In Section 9.8, add text from RFC 2818
(<https://github.com/httpwg/http-core/issues/236>) (<https://github.com/httpwg/http-core/issues/236>)
D.8. Since draft-ietf-httpbis-messaging-06 D.8. Since draft-ietf-httpbis-messaging-06
* In Section 12.4, update the APLN protocol id for HTTP/1.1 * In Section 12.4, update the ALPN protocol ID for HTTP/1.1
(<https://github.com/httpwg/http-core/issues/49>) (<https://github.com/httpwg/http-core/issues/49>)
* In Section 5, align with updates to field terminology in semantics * In Section 5, align with updates to field terminology in semantics
(<https://github.com/httpwg/http-core/issues/111>) (<https://github.com/httpwg/http-core/issues/111>)
* In Section 7.6.1 of [Semantics], clarify that new connection * In Section 7.6.1 of [HTTP], clarify that new connection options
options indeed need to be registered (<https://github.com/httpwg/ indeed need to be registered (<https://github.com/httpwg/http-
http-core/issues/285>) core/issues/285>)
* In Section 1.1, reference RFC 8174 as well * In Section 1.1, reference RFC 8174 as well
(<https://github.com/httpwg/http-core/issues/303>) (<https://github.com/httpwg/http-core/issues/303>)
D.9. Since draft-ietf-httpbis-messaging-07 D.9. Since draft-ietf-httpbis-messaging-07
* Move TE: trailers into [HTTP] (<https://github.com/httpwg/http-
* Move TE: trailers into [Semantics] (<https://github.com/httpwg/ core/issues/18>)
http-core/issues/18>)
* In Section 6.3, adjust requirements for handling multiple content- * In Section 6.3, adjust requirements for handling multiple content-
length values (<https://github.com/httpwg/http-core/issues/59>) length values (<https://github.com/httpwg/http-core/issues/59>)
* Throughout, replace "effective request URI" with "target URI" * Throughout, replace "effective request URI" with "target URI"
(<https://github.com/httpwg/http-core/issues/259>) (<https://github.com/httpwg/http-core/issues/259>)
* In Section 6.1, don't claim Transfer-Encoding is supported by * In Section 6.1, don't claim Transfer-Encoding is supported by
HTTP/2 or later (<https://github.com/httpwg/http-core/issues/297>) HTTP/2 or later (<https://github.com/httpwg/http-core/issues/297>)
skipping to change at page 54, line 33 skipping to change at page 54, line 38
* Switch to xml2rfc v3 mode for draft generation * Switch to xml2rfc v3 mode for draft generation
(<https://github.com/httpwg/http-core/issues/394>) (<https://github.com/httpwg/http-core/issues/394>)
D.12. Since draft-ietf-httpbis-messaging-10 D.12. Since draft-ietf-httpbis-messaging-10
* In Section 6.3, note that TCP half-close does not delimit a * In Section 6.3, note that TCP half-close does not delimit a
request; talk about corresponding server-side behaviour in request; talk about corresponding server-side behaviour in
Section 9.6 (<https://github.com/httpwg/http-core/issues/22>) Section 9.6 (<https://github.com/httpwg/http-core/issues/22>)
* Moved requirements specific to HTTP/1.1 from [Semantics] into * Moved requirements specific to HTTP/1.1 from [HTTP] into
Section 3.2 (<https://github.com/httpwg/http-core/issues/182>) Section 3.2 (<https://github.com/httpwg/http-core/issues/182>)
* In Section 6.1 (Transfer-Encoding), adjust ABNF to allow empty * In Section 6.1 (Transfer-Encoding), adjust ABNF to allow empty
lists (<https://github.com/httpwg/http-core/issues/210>) lists (<https://github.com/httpwg/http-core/issues/210>)
* In Section 9.7, add text from RFC 2818 * In Section 9.7, add text from RFC 2818
(<https://github.com/httpwg/http-core/issues/236>) (<https://github.com/httpwg/http-core/issues/236>)
* Moved definitions of "TE" and "Upgrade" into [Semantics] * Moved definitions of "TE" and "Upgrade" into [HTTP]
(<https://github.com/httpwg/http-core/issues/392>) (<https://github.com/httpwg/http-core/issues/392>)
* Moved definition of "Connection" into [Semantics] * Moved definition of "Connection" into [HTTP]
(<https://github.com/httpwg/http-core/issues/407>) (<https://github.com/httpwg/http-core/issues/407>)
D.13. Since draft-ietf-httpbis-messaging-11 D.13. Since draft-ietf-httpbis-messaging-11
* Move IANA Upgrade Token Registry instructions to [Semantics] * Move IANA Upgrade Token Registry instructions to [HTTP]
(<https://github.com/httpwg/http-core/issues/450>) (<https://github.com/httpwg/http-core/issues/450>)
D.14. Since draft-ietf-httpbis-messaging-12 D.14. Since draft-ietf-httpbis-messaging-12
* Moved content of history appendix to Semantics * Moved content of history appendix to Semantics
(<https://github.com/httpwg/http-core/issues/451>) (<https://github.com/httpwg/http-core/issues/451>)
* Moved note about "close" being reserved as field name to * Moved note about "close" being reserved as field name to
Section 9.3 (<https://github.com/httpwg/http-core/issues/500>) Section 9.3 (<https://github.com/httpwg/http-core/issues/500>)
* Moved table of transfer codings into Section 12.3 * Moved table of transfer codings into Section 12.3
(<https://github.com/httpwg/http-core/issues/506>) (<https://github.com/httpwg/http-core/issues/506>)
* In Section 13.2, updated the URI for the [Linhart] paper * In Section 13.2, updated the URI for the [Linhart] paper
(<https://github.com/httpwg/http-core/issues/517>) (<https://github.com/httpwg/http-core/issues/517>)
* Changed document title to just "HTTP/1.1" * Changed document title to just "HTTP/1.1"
(<https://github.com/httpwg/http-core/issues/524>) (<https://github.com/httpwg/http-core/issues/524>)
* In Section 7, moved transfer-coding ABNF to Section 10.1.4 of * In Section 7, moved transfer-coding ABNF to Section 10.1.4 of
[Semantics] (<https://github.com/httpwg/http-core/issues/531>) [HTTP] (<https://github.com/httpwg/http-core/issues/531>)
* Changed to using "payload data" when defining requirements about * Changed to using "payload data" when defining requirements about
the data being conveyed within a message, instead of the terms the data being conveyed within a message, instead of the terms
"payload body" or "response body" or "representation body", since "payload body" or "response body" or "representation body", since
they often get confused with the HTTP/1.1 message body (which they often get confused with the HTTP/1.1 message body (which
includes transfer coding) (<https://github.com/httpwg/http-core/ includes transfer coding) (<https://github.com/httpwg/http-core/
issues/553>) issues/553>)
D.15. Since draft-ietf-httpbis-messaging-13 D.15. Since draft-ietf-httpbis-messaging-13
skipping to change at page 56, line 31 skipping to change at page 56, line 34
* In Section 3.2.3, changed the ABNF definition of authority-form * In Section 3.2.3, changed the ABNF definition of authority-form
from the authority component (in which port is optional) to the from the authority component (in which port is optional) to the
host:port format that has always been required by CONNECT host:port format that has always been required by CONNECT
(<https://github.com/httpwg/http-core/issues/806>) (<https://github.com/httpwg/http-core/issues/806>)
D.17. Since draft-ietf-httpbis-messaging-15 D.17. Since draft-ietf-httpbis-messaging-15
* None. * None.
Acknowledgments D.18. Since draft-ietf-httpbis-messaging-16
See Appendix "Acknowledgments" of [Semantics]. This draft addresses mostly editorial issues raised during or past
IETF Last Call; see <https://github.com/httpwg/http-core/
issues?q=label%3Ah1-messaging+created%3A%3E2021-05-26> for a summary.
Furthermore:
* In Section 6.1, require recipients to avoid smuggling/splitting
attacks when processing an ambiguous message framing
(<https://github.com/httpwg/http-core/issues/879>)
Acknowledgements
See Appendix "Acknowledgements" of [HTTP].
Index Index
A C D F G H M O R T X A C D F G H M O R T X
A A
absolute-form (of request-target) Section 3.2.2 absolute-form (of request-target) Section 3.2.2
application/http Media Type Section 10.2 application/http Media Type Section 10.2
asterisk-form (of request-target) Section 3.2.4 asterisk-form (of request-target) Section 3.2.4
 End of changes. 136 change blocks. 
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