INTERNET-DRAFT M. Yevstifeyev
Intended Status: Experimental December 31, 2010
Expires: July 4, 2011
HTTP 'Headers-Not-Recognized' Header Field
<draft-yevstifeyev-http-headers-not-recognized-10>
Abstract
This document defines mechanism which allows HTTP hosts to notify
another hosts about not supported headers - 'Headers-Not-Recognized'
HTTP header field.
Status of this Memo
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document authors. All rights reserved.
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INTERNET DRAFT Headers-Not-Recognized for HTTP December 31, 2010
include Simplified BSD License text as described in Section 4.e of
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2.1. Conformance Criteria . . . . . . . . . . . . . . . . . 3
1.2.2. Syntax Notation . . . . . . . . . . . . . . . . . . . 3
1.2.3. Terminology . . . . . . . . . . . . . . . . . . . . . 3
2. Technical Overview . . . . . . . . . . . . . . . . . . . . . . . 4
2.1 Model of Work . . . . . . . . . . . . . . . . . . . . . . . 4
2.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
5. Normative References . . . . . . . . . . . . . . . . . . . . . . 5
Author's Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5
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1. Introduction
1.1. Motivation
HTTP is one of the most widely-used protocols in the Internet. One of
the things which made it so popular is extensibility. One can easily
add any header field to the HTTP message. However, all hosts are not
able to support all the header fields. Generally, if a it host does
not support the header field, it is simply ignored. The another side
of exchange is not notified about not processed header fields.
This document proposes mechanism which allows HTTP hosts to notify
another hosts about not recognized headers.
The proposal is to send a message with definite header field to the
host if one or more header fields of its request are not supported.
This document defines 'Headers-Not-Recognized' HTTP header field to
be used in such occasion.
1.2. Conventions
1.2.1. Conformance Criteria
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
1.2.2. Syntax Notation
This specification uses the Augmented Backus-Naur Form (ABNF)
notation of [RFC5234].
The construction <n>#<m>element is used as defined in RFC 2616
[RFC2616], Section 2.1.
1.2.3. Terminology
HTTP refers to protocol, defined in RFC 2616 [RFC2616]
The terms client, server, proxy, gateway and tunnel have the same
meaning as in the HTTP/1.1 specification ([RFC2616], Section 1.3).
The term host means client or server.
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2. Technical Overview
2.1 Model of Work
If the HTTP host receives HTTP message which contains some header
fields which are not supported by it, it is RECOMMENDED for it to
include the Headers-Not-Recognized header field in the response to
the host that sent message with not supported header fields.
Information about not supported header fields is to be put in the
'Headers-Not-Recognized' header field following the rules of Section
2.2 of this document. The 'Headers-Not-Recognized' header field MUST
contain information only about not supported header fields - i.e.
header fields which are not able to be processed anyway. It MUST NOT
contain information about header fields, which are partly supported,
whose entity cannot be processed while the header field is supported
at all etc.
When HTTP host receives HTTP message with Headers-Not-Recognized
header field, it is RECOMMENDED that it avoids sending messages with
header fields with mentioned in it names to source (for message with
this header field) host or tries to change them so that hat host is
able to recognize and process them.
Intermediate systems (also called middle-boxes), such as proxies,
tunnels, gateways etc. MUST transfer the messages with Headers-Not-
Recognized header field to the destination host without changing the
entity of this header field if the not supported header field was
present in the initial HTTP request (i. e. request which intermediate
system received before transferring it to destination node), but MUST
omit it if Headers-Not-Recognized header field's entity concerns only
to headers added to initial request by middle-box. If the
aforementioned header concerns added header fields partly, middle-box
MUST change the entity so that it concerns only initial request
header field.
2.2 Syntax
'Headers-Not-Recognized' header field has the following format:
headers_not_recognized = 1#header_name
header_name = 1*VCHAR
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3. IANA Considerations
The permanent message header field registry should be updated with
the following registration:
Header field name
Headers-Not-Recognized
Applicable protocol
http
Status
experimental
Specification document
RFC xxxx
[RFC Editor: replace xxxx with assigned RFC number]
[Note: This registration should take place at
http://www.iana.org/assignments/message-headers/perm-headers.html
This note is to be deleted upon publication.]
4. Security Considerations
This extension to HTTP is not believed to add any additional security
concerns not already present in RFC 2616 [RFC2616].
5. Normative References
[RFC2119] S. Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC5234] Crocker, D., Ed., and P. Overell, "Augmented BNF for
Syntax Specifications: ABNF", STD 68, RFC 5234, January
2008.
Author's Addresses
Mykyta Yevstifeyev
Kotovsk, Ukraine
EMail: evnikita2@gmail.com
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