|Network Working Group||J. Reschke|
|Updates: 2616 (if approved)||October 16, 2009|
|Intended status: Standards Track|
|Expires: April 19, 2010|
Use of the Content-Disposition Header Field in the Hypertext Transfer Protocol (HTTP)
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HTTP/1.1 defines the Content-Disposition Response Header, 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.
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 email@example.com, which may be joined by sending a message with subject "subscribe" to firstname.lastname@example.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/>.
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 header, and also clarifies internationalization considerations.
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].
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>
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.
[rfc.comment.1: Talk about expected behavior, mention security considerations.]
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 wasn't present, but to remember the filename "foo.html" for a subsequent save operation:
Content-Disposition: INLINE; FILENAME= "foo.html"
[csec: Both refer to 2183, and also mention: long filenames, dot and dotdot, absolute paths, mismatches between media type and extension]
This document updates the definition of the Content-Disposition HTTP header in the permanent HTTP header registry (see [RFC3864]).
|[draft-reschke-rfc2231-in-http]||Reschke, J., “Applicability of RFC 2231 Encoding to Hypertext Transfer Protocol (HTTP) Headers”, Internet-Draft draft-reschke-rfc2231-in-http-05 (work in progress), October 2009.|
|[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.|
|[RFC3864]||Klyne, G., Nottingham, M., and J. Mogul, “Registration Procedures for Message Header Fields”, BCP 90, RFC 3864, September 2004.|
Section 2 of [RFC2183] 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.