Network Working Group J. Reschke

Internet-Draft greenbytes

Updates: 2616 (if approved) July 27, 2010

Intended status: Standards Track

Expires: January 28, 2011

Use of the Content-Disposition Header Field in the Hypertext Transfer Protocol (HTTP)

Abstract

HTTP/1.1 defines the Content-Disposition <ed:replace>2009年11月16日<ed:del>Response Header</ed:del><ed:ins>response header field</ed:ins></ed:replace>, but points out that it is not part of the HTTP/1.1 Standard. This specification takes over the definition and registration of Content-Disposition, as used in HTTP, and clarifies internationalization considerations.¶

Status of this Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.¶

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/.¶

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This Internet-Draft will expire on January 28, 2011.¶

Copyright Notice

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.¶

Editorial Note (To be removed by RFC Editor before publication)

This specification is expected to replace the definition of Content-Disposition in the HTTP/1.1 specification, as currently revised by the IETF HTTPbis working group. See also <http://www3.tools.ietf.org/wg/httpbis/trac/ticket/123>.¶

Distribution of this document is unlimited. Although this is not a work item of the HTTPbis Working Group, comments should be sent to the Hypertext Transfer Protocol (HTTP) mailing list at ietf-http-wg@w3.org, which may be joined by sending a message with subject "subscribe" to ietf-http-wg-request@w3.org.¶

Discussions of the HTTPbis Working Group are archived at <http://lists.w3.org/Archives/Public/ietf-http-wg/>.¶

XML versions, latest edits and the issues list for this document are available from <http://greenbytes.de/tech/webdav/#draft-reschke-rfc2183-in-http>. A collection of test cases is available at <http://greenbytes.de/tech/tc2231/>.¶

1. Introduction

HTTP/1.1 defines the Content-Disposition <ed:replace>2009年11月16日<ed:del>response header</ed:del><ed:ins>response header field</ed:ins></ed:replace> in Section 19.5.1 of [RFC2616], but points out that <ed:replace>2009年11月04日<ed:ins>it</ed:ins></ed:replace>is not part of the HTTP/1.1 Standard (Section 15.5):¶

[引用]

Content-Disposition is not part of the HTTP standard, but since it is widely implemented, we are documenting its use and risks for implementors.¶

This specification takes over the definition and registration of Content-Disposition, as used in HTTP. Based on interoperability testing with existing User Agents, it defines a profile of the features defined in the MIME variant ([RFC2183]) of the <ed:replace>2009年11月16日<ed:del>header</ed:del><ed:ins>header field</ed:ins></ed:replace>, and also clarifies internationalization considerations.¶

2. Notational Conventions

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 [RFC2119].¶

This specification uses the augmented BNF notation defined in Section 2.1 of [RFC2616], including its rules for linear whitespace (LWS).¶

3. Header Field Definitions

3.1. Grammar

 content-disposition = "Content-Disposition" ":"
 disposition-type *( ";" disposition-parm )
 disposition-type = "inline" | "attachment" | disp-ext-type
 ; case-insensitive
 disp-ext-type = token
 disposition-parm = filename-parm | disp-ext-parm
 filename-parm = "filename" "=" value
 | "filename*" "=" ext-value
 
 disp-ext-parm = token "=" value
 | ext-token "=" ext-value
 ext-token = <the characters in token, followed by "*">

Defined in [RFC2616]:

 token = <token, defined in [RFC2616], Section 2.2>
 value = <value, defined in [RFC2616], Section 3.6>

Defined in [draft-reschke-rfc2231-in-http]:

 ext-value = <ext-value, defined in [draft-reschke-rfc2231-in-http], Section 3.2>

3.2. Disposition Type

If the disposition type matches "attachment" (case-insensitively), the implied suggestion is that the user agent should not display the response, but directly enter a "save response as..." dialog.¶

On the other hand, if it matches "inline", this implies regular processing. Note that this type may be used when it is desirable to transport filename information for the case of a subsequent, user-initiated, save operation.¶

Other disposition types SHOULD be handled the same way as "attachment" ([RFC2183], Section 2.8).¶

3.3. Disposition Parameter: 'Filename'

[rfc.comment.1: Talk about expected behavior, mention security considerations.] ¶

3.4. Disposition Parameter: Extensions

Parameters other <ed:replace>2009年10月16日<ed:del>then</ed:del><ed:ins>than</ed:ins></ed:replace> "filename" SHOULD be ignored ([RFC2183], Section 2.8).¶

4. Examples

Direct UA to show "save as" dialog, with a filename of "foo.html":

Content-Disposition: Attachment; filename=foo.html

Direct UA to behave as if the Content-Disposition <ed:replace>2009年11月16日<ed:del>header</ed:del><ed:ins>header field</ed:ins></ed:replace> wasn't present, but to remember the filename "foo.html" for a subsequent save operation:

Content-Disposition: INLINE; FILENAME= "foo.html"

5. Security Considerations

[csec: Both refer to 2183, and also mention: long filenames, dot and dotdot, absolute paths, mismatches between media type and extension] ¶

6. IANA Considerations

6.1. Registry for Disposition Values and Parameter

<ed:replace>2009年11月16日<ed:del>Section 9 of [RFC2183] defines the registration procedure for new disposition values and parameters.</ed:del> <ed:ins>This specification does not introduce any changes to the registration procedures for disposition values and parameters that are defined in Section 9 of [RFC2183].</ed:ins></ed:replace> ¶

7. Acknowledgements

[rfc.comment.2: TBD.] ¶

8. References

8.1. Normative References

[RFC2119]: Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels”, BCP 14, RFC 2119, March 1997.
[RFC2183]: Troost, R., Dorner, S., and K. Moore, “Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field”, RFC 2183, August 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.

8.2. Informative References

[RFC3864]: Klyne, G., Nottingham, M., and J. Mogul, “Registration Procedures for Message Header Fields”, BCP 90, RFC 3864, September 2004.

Appendix A. Changes from the RFC 2616 Definition

Compared to Section 19.5.1 of [RFC2616], the following normative changes reflecting actual implementations have been made: ¶

According to RFC 2616, the disposition type "attachment" only applies to content of type "application/octet-stream". This restriction has been removed, because user agents in practice do not check the content type, and it also discourages properly declaring the media type.
The definition for the disposition type "inline" ([RFC2183], Section 2.1) has been re-added with a suggestion for its processing.
This specification requires support for the extended parameter encoding defined in [draft-reschke-rfc2231-in-http].

C
- Content-Disposition header 3, 6.2
H
- Headers
  - Content-Disposition 3, 6.2
R
- RFC2119 2, 8.1
- RFC2183 1, 3.2, 3.4, 6.1, 6.1, 8.1, A, B
  - Section 2 B
  - Section 2.1 A
  - Section 2.8 3.2, 3.4
  - Section 9 6.1, 6.1
- RFC2616 1, 1, 2, 3.1, 3.1, 3.1, 8.1, A
  - Section 2.1 2
  - Section 2.2 3.1
  - Section 3.6 3.1
  - Section 15.5 1
  - Section 19.5.1 1, A
- RFC3864 6.2, 8.2

Author's Address

Julian F. Reschke
greenbytes GmbH
Hafenweg 16
Muenster, NW 48155
Germany
EMail: julian.reschke@greenbytes.de
URI: http://greenbytes.de/tech/webdav/