TOC 
Network Working GroupJ. Reschke
Internet-Draftgreenbytes
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)
draft-reschke-rfc2183-in-http-01

Abstract

HTTP/1.1 defines the Content-Disposition response header field, 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.

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/.

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

Copyright (c) 2010 IETF Trust and the persons identified as the document authors. All rights reserved.

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.



Table of Contents

1.  Introduction
2.  Notational Conventions
3.  Header Field Definitions
    3.1.  Grammar
    3.2.  Disposition Type
    3.3.  Disposition Parameter: 'Filename'
    3.4.  Disposition Parameter: Extensions
4.  Examples
5.  Security Considerations
6.  IANA Considerations
    6.1.  Registry for Disposition Values and Parameter
    6.2.  Header Field Registration
7.  Acknowledgements
8.  References
    8.1.  Normative References
    8.2.  Informative References
Appendix A.  Changes from the RFC 2616 Definition
Appendix B.  Differences compared to RFC 2183
Appendix C.  Alternative Approaches to Filename Escaping
Appendix D.  Change Log (to be removed by RFC Editor before publication)
    D.1.  Since draft-reschke-rfc2183-in-http-00
Appendix E.  Open issues (to be removed by RFC Editor prior to publication)
    E.1.  edit
§  Index
§  Author's Address




 TOC 

1.  Introduction

HTTP/1.1 defines the Content-Disposition response header field in Section 19.5.1 of [RFC2616] (Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., Leach, P., and T. Berners-Lee, “Hypertext Transfer Protocol -- HTTP/1.1,” June 1999.), but points out that it is not part of the HTTP/1.1 Standard (Section 15.5):

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] (Troost, R., Dorner, S., and K. Moore, “Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field,” August 1997.)) of the header field, and also clarifies internationalization considerations.



 TOC 

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] (Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.).

This specification uses the augmented BNF notation defined in Section 2.1 of [RFC2616] (Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., Leach, P., and T. Berners-Lee, “Hypertext Transfer Protocol -- HTTP/1.1,” June 1999.), including its rules for linear whitespace (LWS).



 TOC 

3.  Header Field Definitions



 TOC 

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] (Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., Leach, P., and T. Berners-Lee, “Hypertext Transfer Protocol -- HTTP/1.1,” June 1999.):

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

Defined in [draft‑reschke‑rfc2231‑in‑http] (Reschke, J., “Applicability of RFC 2231 Encoding to Hypertext Transfer Protocol (HTTP) Headers,” April 2010.):

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


 TOC 

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] (Troost, R., Dorner, S., and K. Moore, “Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field,” August 1997.), Section 2.8).



 TOC 

3.3.  Disposition Parameter: 'Filename'

[anchor3] (Talk about expected behavior, mention security considerations.)



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3.4.  Disposition Parameter: Extensions

Parameters other than "filename" SHOULD be ignored ([RFC2183] (Troost, R., Dorner, S., and K. Moore, “Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field,” August 1997.), Section 2.8).



 TOC 

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 header field wasn't present, but to remember the filename "foo.html" for a subsequent save operation:

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


 TOC 

5.  Security Considerations

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



 TOC 

6.  IANA Considerations



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6.1.  Registry for Disposition Values and Parameter

This specification does not introduce any changes to the registration procedures for disposition values and parameters that are defined in Section 9 of [RFC2183] (Troost, R., Dorner, S., and K. Moore, “Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field,” August 1997.).



 TOC 

6.2.  Header Field Registration

This document updates the definition of the Content-Disposition HTTP header field in the permanent HTTP header field registry (see [RFC3864] (Klyne, G., Nottingham, M., and J. Mogul, “Registration Procedures for Message Header Fields,” September 2004.)).

Header field name:
Content-Disposition
Applicable protocol:
http
Status:
standard
Author/Change controller:
IETF
Specification document:
this specification (Section 3 (Header Field Definitions))



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7.  Acknowledgements

[anchor6] (TBD.)



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8.  References



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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.
[draft-reschke-rfc2231-in-http] Reschke, J., “Applicability of RFC 2231 Encoding to Hypertext Transfer Protocol (HTTP) Headers,” draft-reschke-rfc2231-in-http-12 (work in progress), April 2010.


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8.2. Informative References

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


 TOC 

Appendix A.  Changes from the RFC 2616 Definition

Compared to Section 19.5.1 of [RFC2616] (Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., Leach, P., and T. Berners-Lee, “Hypertext Transfer Protocol -- HTTP/1.1,” June 1999.), the following normative changes reflecting actual implementations have been made:



 TOC 

Appendix B.  Differences compared to RFC 2183

Section 2 of [RFC2183] (Troost, R., Dorner, S., and K. Moore, “Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field,” August 1997.) defines several additional disposition parameters: "creation-date", "modification-date", "quoted-date-time", and "size". These do not appear to be implemented by any user agent, thus have been ommitted from this specification.



 TOC 

Appendix C.  Alternative Approaches to Filename Escaping

[anchor10] (Mention: RFC 2047, IE, Safari)



 TOC 

Appendix D.  Change Log (to be removed by RFC Editor before publication)



 TOC 

D.1.  Since draft-reschke-rfc2183-in-http-00

Adjust terminology ("header" -> "header field"). Update rfc2231-in-http reference.



 TOC 

Appendix E.  Open issues (to be removed by RFC Editor prior to publication)



 TOC 

E.1.  edit

Type: edit

julian.reschke@greenbytes.de (2009-10-16): Umbrella issue for editorial fixes/enhancements.



 TOC 

Index

C 
 Content-Disposition header
H 
 Headers
   Content-Disposition


 TOC 

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/