draft-ietf-httpbis-cice-03.txt   draft-ietf-httpbis-cice-latest.txt 
HTTP Working Group J. Reschke HTTP Working Group J. Reschke
Internet-Draft greenbytes Internet-Draft greenbytes
Intended status: Standards Track September 8, 2015 Intended status: Standards Track March 24, 2017
Expires: March 11, 2016 Expires: September 25, 2017
Hypertext Transfer Protocol (HTTP) Client-Initiated Content-Encoding Hypertext Transfer Protocol (HTTP) Client-Initiated Content-Encoding
draft-ietf-httpbis-cice-03 draft-ietf-httpbis-cice-latest
Abstract Abstract
In HTTP, content codings allow for payload encodings such as for In HTTP, content codings allow for payload encodings such as for
compression or integrity checks. In particular, the "gzip" content compression or integrity checks. In particular, the "gzip" content
coding is widely used for payload data sent in response messages. coding is widely used for payload data sent in response messages.
Content codings can be used in request messages as well, however Content codings can be used in request messages as well; however,
discoverability is not on par with response messages. This document discoverability is not on par with response messages. This document
extends the HTTP "Accept-Encoding" header field for use in responses, extends the HTTP "Accept-Encoding" header field for use in responses,
to indicate the content codings that are supported in requests. to indicate the content codings that are supported in requests.
Editorial Note (To be removed by RFC Editor before publication) Editorial Note (To be removed by RFC Editor before publication)
Discussion of this draft takes place on the HTTPBIS working group Discussion of this draft takes place on the HTTPBIS 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 Working Group information can be found at <https://tools.ietf.org/wg/
<https://tools.ietf.org/wg/httpbis/> and <http://httpwg.github.io/>; httpbis/> and <http://httpwg.github.io/>; source code and issues list
source code and issues list for this draft can be found at for this draft can be found at <https://github.com/httpwg/http-
<https://github.com/httpwg/http-extensions>. extensions>.
The changes in this draft are summarized in Appendix A.6.
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
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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 March 11, 2016.
This Internet-Draft will expire on September 25, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2017 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 Provisions Relating to IETF Documents
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3 2. Notational Conventions . . . . . . . . . . . . . . . . . . . 3
3. Using the 'Accept-Encoding' Header Field in Responses . . . . . 3 3. Using the 'Accept-Encoding' Header Field in Responses . . . . 3
4. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Deployment Considerations . . . . . . . . . . . . . . . . . . . 5 5. Deployment Considerations . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7.1. Header Field Registry . . . . . . . . . . . . . . . . . . . 5 7.1. Header Field Registry . . . . . . . . . . . . . . . . . . 5
7.2. Status Code Registry . . . . . . . . . . . . . . . . . . . 6 7.2. Status Code Registry . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . . 6 8.1. Normative References . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . . 7 8.2. Informative References . . . . . . . . . . . . . . . . . 6
Appendix A. Change Log (to be removed by RFC Editor before Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 8
publication) . . . . . . . . . . . . . . . . . . . . . 7 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8
A.1. Since draft-reschke-http-cice-00 . . . . . . . . . . . . . 7
A.2. Since draft-reschke-http-cice-01 . . . . . . . . . . . . . 7
A.3. Since draft-reschke-http-cice-02 . . . . . . . . . . . . . 7
A.4. Since draft-ietf-httpbis-cice-00 . . . . . . . . . . . . . 7
A.5. Since draft-ietf-httpbis-cice-01 . . . . . . . . . . . . . 8
A.6. Since draft-ietf-httpbis-cice-02 . . . . . . . . . . . . . 8
Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
In HTTP, content codings allow for payload encodings such as for In HTTP, content codings allow for payload encodings such as for
compression or integrity checks ([RFC7231], Section 3.1.2). In compression or integrity checks ([RFC7231], Section 3.1.2). In
particular, the "gzip" content coding ([RFC7230], Section 4.2) is particular, the "gzip" content coding ([RFC7230], Section 4.2) is
widely used for payload data sent in response messages. widely used for payload data sent in response messages.
Content codings can be used in request messages as well, however Content codings can be used in request messages as well; however,
discoverability is not on par with response messages. This document discoverability is not on par with response messages. This document
extends the HTTP "Accept-Encoding" header field ([RFC7231], Section extends the HTTP "Accept-Encoding" header field ([RFC7231],
5.3.4) for use in responses, to indicate the content codings that are Section 5.3.4) for use in responses, to indicate the content codings
supported in requests. It furthermore updates the definition of that are supported in requests. It furthermore updates the
status code 415 (Unsupported Media Type) ([RFC7231], Section 6.5.13), definition of status code 415 (Unsupported Media Type) ([RFC7231],
recommending to include the "Accept-Encoding" header field when Section 6.5.13), recommending that the "Accept-Encoding" header field
appropriate. be included when appropriate.
2. Notational Conventions 2. Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
This document reuses terminology defined in the base HTTP This document reuses terminology defined in the base HTTP
specifications, namely Section 2 of [RFC7230] and Section 3.1.2 of specifications, namely Section 2 of [RFC7230] and Section 3.1.2 of
[RFC7231]. [RFC7231].
skipping to change at page 3, line 44 skipping to change at page 3, line 28
header field only. header field only.
This specification expands that definition to allow "Accept-Encoding" This specification expands that definition to allow "Accept-Encoding"
as a response header field as well. When present in a response, it as a response header field as well. When present in a response, it
indicates what content codings the resource was willing to accept in indicates what content codings the resource was willing to accept in
the associated request. A field value that only contains "identity" the associated request. A field value that only contains "identity"
implies that no content codings were supported. implies that no content codings were supported.
Note that this information is specific to the associated request; the Note that this information is specific to the associated request; the
set of supported encodings might be different for other resources on set of supported encodings might be different for other resources on
the same server, and could change over time or depend on other the same server and could change over time or depend on other aspects
aspects of the request (such as the request method). of the request (such as the request method).
Section 6.5.13 of [RFC7231] defines status code 415 (Unsupported Section 6.5.13 of [RFC7231] defines status code 415 (Unsupported
Media Type) to apply to both media type and content coding related Media Type) to apply to problems related to both media types and
problems. content codings.
Servers that fail a request due to an unsupported content coding Servers that fail a request due to an unsupported content coding
ought to respond with a 415 status and ought to include an "Accept- ought to respond with a 415 status and ought to include an "Accept-
Encoding" header field in that response, allowing clients to Encoding" header field in that response, allowing clients to
distinguish between content coding related issues and media type distinguish between issues related to content codings and media
related issues. In order to avoid confusion with media type related types. In order to avoid confusion with issues related to media
problems, servers that fail a request with a 415 status for reasons types, servers that fail a request with a 415 status for reasons
unrelated to content codings MUST NOT include the "Accept-Encoding" unrelated to content codings MUST NOT include the "Accept-Encoding"
header field. header field.
It is expected that the most common use of "Accept-Encoding" in It is expected that the most common use of "Accept-Encoding" in
responses will have the 415 (Unsupported Media Type) status code, in responses will have the 415 (Unsupported Media Type) status code, in
response to optimistic use of a content coding by clients. However, response to optimistic use of a content coding by clients. However,
the header field can also be used to indicate to clients that content the header field can also be used to indicate to clients that content
codings are supported, to optimize future interactions. For example, codings are supported, to optimize future interactions. For example,
a resource might include it in a 2xx response when the request a resource might include it in a 2xx response when the request
payload was big enough to justify use of a compression coding, but payload was big enough to justify use of a compression coding but the
the client failed do so. client failed do so.
4. Example 4. Example
A client submits a POST request using the "compress" content coding A client submits a POST request using the "compress" content coding
([RFC7231], Section 3.1.2.1): ([RFC7231], Section 3.1.2.1):
POST /edit/ HTTP/1.1 POST /edit/ HTTP/1.1
Host: example.org Host: example.org
Content-Type: application/atom+xml;type=entry Content-Type: application/atom+xml;type=entry
Content-Encoding: compress Content-Encoding: compress
...compressed payload... ...compressed payload...
The server rejects request because it only allows the "gzip" content The server rejects the request because it only allows the "gzip"
coding: content coding:
HTTP/1.1 415 Unsupported Media Type HTTP/1.1 415 Unsupported Media Type
Date: Fri, 09 May 2014 11:43:53 GMT Date: Fri, 09 May 2014 11:43:53 GMT
Accept-Encoding: gzip Accept-Encoding: gzip
Content-Length: 68 Content-Length: 68
Content-Type: text/plain Content-Type: text/plain
This resource only supports the "gzip" content coding in requests. This resource only supports the "gzip" content coding in requests.
...at which point the client can retry the request with the supported At this point, the client can retry the request with the supported
"gzip" content coding. "gzip" content coding.
Alternatively, a server that does not support any content codings in Alternatively, a server that does not support any content codings in
requests could answer with: requests could answer with:
HTTP/1.1 415 Unsupported Media Type HTTP/1.1 415 Unsupported Media Type
Date: Fri, 09 May 2014 11:43:53 GMT Date: Fri, 09 May 2014 11:43:53 GMT
Accept-Encoding: identity Accept-Encoding: identity
Content-Length: 61 Content-Length: 61
Content-Type: text/plain Content-Type: text/plain
This resource does not support content codings in requests. This resource does not support content codings in requests.
5. Deployment Considerations 5. Deployment Considerations
Servers that do not support content codings in requests already are Servers that do not support content codings in requests already are
required to fail a request that uses a content coding. Section required to fail a request that uses a content coding.
6.5.13 of [RFC7231] defines the status code 415 (Unsupported Media Section 6.5.13 of [RFC7231] defines the status code 415 (Unsupported
Type) for this purpose, so the only change needed is to include the Media Type) for this purpose, so the only change needed is to include
"Accept-Encoding" header field with value "identity" in that the "Accept-Encoding" header field with the value "identity" in that
response. response.
Servers that do support some content codings are required to fail Servers that do support some content codings are required to fail
requests with unsupported content codings as well. To be compliant requests with unsupported content codings as well. To be compliant
with this specification, servers will need to use the status code 415 with this specification, servers will need to use the status code 415
(Unsupported Media Type) to signal the problem, and will have to (Unsupported Media Type) to signal the problem and will have to
include an "Accept-Encoding" header field that enumerates the content include an "Accept-Encoding" header field that enumerates the content
codings that are supported. As the set of supported content codings codings that are supported. As the set of supported content codings
is usually static and small, adding the header field ought to be is usually static and small, adding the header field ought to be
trivial. trivial.
6. Security Considerations 6. Security Considerations
This specification only adds discovery of supported content codings This specification only adds discovery of supported content codings
and diagnostics for requests failing due to unsupported content and diagnostics for requests failing due to unsupported content
codings. As such, it doesn't introduce any new security codings. As such, it doesn't introduce any new security
skipping to change at page 5, line 52 skipping to change at page 5, line 32
of [RFC7230]), which, when used over a secure channel, can enable of [RFC7230]), which, when used over a secure channel, can enable
side-channel attacks such as BREACH (see Section 10.6 of [RFC7540] side-channel attacks such as BREACH (see Section 10.6 of [RFC7540]
and [BREACH]). At the time of publication, it was unclear how and [BREACH]). At the time of publication, it was unclear how
BREACH-like attacks can be applied to compression in HTTP requests. BREACH-like attacks can be applied to compression in HTTP requests.
7. IANA Considerations 7. IANA Considerations
7.1. Header Field Registry 7.1. Header Field Registry
HTTP header fields are registered within the "Message Headers" HTTP header fields are registered within the "Message Headers"
registry located at registry located at <http://www.iana.org/assignments/message-
<http://www.iana.org/assignments/message-headers>, as defined by headers>, as defined by [BCP90].
[BCP90].
This document updates the definition of the "Accept-Encoding" header This document updates the definition of the "Accept-Encoding" header
field, so the "Permanent Message Header Field Names" registry ought field. The "Permanent Message Header Field Names" registry has been
to be updated accordingly: updated as follows:
+-----------------+----------+----------+---------------------------+ +-----------------+----------+----------+---------------------------+
| Header Field | Protocol | Status | Reference | | Header Field | Protocol | Status | Reference |
| Name | | | | | Name | | | |
+-----------------+----------+----------+---------------------------+ +-----------------+----------+----------+---------------------------+
| Accept-Encoding | http | standard | [RFC7231], Section 5.3.4, | | Accept-Encoding | http | standard | Section 5.3.4 of |
| | | | and Section 3 of this | | | | | [RFC7231] and Section 3 |
| | | | document | | | | | of this document |
+-----------------+----------+----------+---------------------------+ +-----------------+----------+----------+---------------------------+
7.2. Status Code Registry 7.2. Status Code Registry
HTTP status codes are registered within the "Status Code" registry HTTP status codes are registered within the "HTTP Status Codes"
located at <http://www.iana.org/assignments/http-status-codes>. registry located at <http://www.iana.org/assignments/http-status-
codes>.
This document updates the definition of the status code 415 This document updates the definition of the status code 415
(Unsupported Media Type), so the "Status Code" registry ought to be (Unsupported Media Type). The "HTTP Status Codes" registry has been
updated accordingly: updated as follows:
+-------+------------------+----------------------------------------+ +-------+-----------------+-----------------------------------------+
| Value | Description | Reference | | Value | Description | Reference |
+-------+------------------+----------------------------------------+ +-------+-----------------+-----------------------------------------+
| 415 | Unsupported | [RFC7231], Section 6.5.13, and | | 415 | Unsupported | Section 6.5.13 of [RFC7231] and Section |
| | Media Type | Section 3 of this document | | | Media Type | 3 of this document |
+-------+------------------+----------------------------------------+ +-------+-----------------+-----------------------------------------+
8. References 8. References
8.1. Normative References 8.1. Normative References
[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, DOI 10.17487/ Requirement Levels", BCP 14, RFC 2119,
RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing", Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014, RFC 7230, DOI 10.17487/RFC7230, June 2014,
<http://www.rfc-editor.org/info/rfc7230>. <http://www.rfc-editor.org/info/rfc7230>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231, Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
DOI 10.17487/RFC7231, June 2014, DOI 10.17487/RFC7231, June 2014,
<http://www.rfc-editor.org/info/rfc7231>. <http://www.rfc-editor.org/info/rfc7231>.
8.2. Informative References 8.2. Informative References
[BCP90] Klyne, G., Nottingham, M., and J. Mogul, "Registration [BCP90] Klyne, G., Nottingham, M., and J. Mogul, "Registration
Procedures for Message Header Fields", BCP 90, RFC 3864, Procedures for Message Header Fields", BCP 90, RFC 3864,
September 2004, <http://www.rfc-editor.org/info/bcp90>. September 2004, <http://www.rfc-editor.org/info/bcp90>.
[BREACH] Gluck, Y., Harris, N., and A. Prado, "BREACH: Reviving the [BREACH] Gluck, Y., Harris, N., and A. Prado, "BREACH: Reviving the
CRIME Attack", July 2013, <http://breachattack.com/ CRIME Attack", July 2013,
resources/ <http://breachattack.com/resources/
BREACH%20-%20SSL,%20gone%20in%2030%20seconds.pdf>. BREACH%20-%20SSL,%20gone%20in%2030%20seconds.pdf>.
[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext [RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540, Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015, DOI 10.17487/RFC7540, May 2015,
<http://www.rfc-editor.org/info/rfc7540>. <http://www.rfc-editor.org/info/rfc7540>.
Appendix A. Change Log (to be removed by RFC Editor before publication) Acknowledgements
A.1. Since draft-reschke-http-cice-00
Clarified that the information returned in Accept-Encoding is per
resource, not per server.
Added some deployment considerations.
Updated HTTP/1.1 references.
A.2. Since draft-reschke-http-cice-01
Restrict the scope of A-E from "future requests" to "at the time of
this request".
Mention use of A-E in responses other than 415.
Recommend not to include A-E in a 415 response unless there was
actually a problem related to content coding.
A.3. Since draft-reschke-http-cice-02
First Working Group draft; updated boilerplate accordingly.
A.4. Since draft-ietf-httpbis-cice-00
Apply editorial improvements suggested by Mark Nottingham.
A.5. Since draft-ietf-httpbis-cice-01
Clarify that we're also extending the definition of status code 415
(so update that IANA registry entry as well).
A.6. Since draft-ietf-httpbis-cice-02
Removed normative language that required used of Accept-Encoding in
responses (which would have made existing servers non-compliant).
Add BREACH like attacks to security considerations
(<https://github.com/httpwg/http-extensions/issues/94>).
Appendix B. Acknowledgements
Thanks go to the members of the and HTTPbis Working Group, namely Thanks go to the Hypertext Transfer Protocol Working Group
Amos Jeffries, Ben Campbell, Mark Nottingham, Pete Resnick, Stephen participants, namely Amos Jeffries, Ben Campbell, Mark Nottingham,
Farrell, and Ted Hardie. Pete Resnick, Stephen Farrell, and Ted Hardie.
Author's Address Author's Address
Julian F. Reschke Julian F. Reschke
greenbytes GmbH greenbytes GmbH
Hafenweg 16 Hafenweg 16
Muenster, NW 48155 Muenster, NW 48155
Germany Germany
EMail: julian.reschke@greenbytes.de EMail: julian.reschke@greenbytes.de
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