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) 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 . Distribution of this document is unlimited. 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Reschke Expires January 28, 2011 [Page 2] Internet-Draft Content-Disposition in HTTP July 2010 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 4 3. Header Field Definitions . . . . . . . . . . . . . . . . . . . 4 3.1. Grammar . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.2. Disposition Type . . . . . . . . . . . . . . . . . . . . . 5 3.3. Disposition Parameter: 'Filename' . . . . . . . . . . . . . 5 3.4. Disposition Parameter: Extensions . . . . . . . . . . . . . 5 4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 6.1. Registry for Disposition Values and Parameter . . . . . . . 6 6.2. Header Field Registration . . . . . . . . . . . . . . . . . 6 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 8.1. Normative References . . . . . . . . . . . . . . . . . . . 6 8.2. Informative References . . . . . . . . . . . . . . . . . . 7 Appendix A. Changes from the RFC 2616 Definition . . . . . . . . . 7 Appendix B. Differences compared to RFC 2183 . . . . . . . . . . . 7 Appendix C. Alternative Approaches to Filename Escaping . . . . . 8 Appendix D. Change Log (to be removed by RFC Editor before publication) . . . . . . . . . . . . . . . . . . . . . 8 D.1. Since draft-reschke-rfc2183-in-http-00 . . . . . . . . . . 8 Appendix E. Open issues (to be removed by RFC Editor prior to publication) . . . . . . . . . . . . . . . . . . . . . 8 E.1. edit . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 8 Reschke Expires January 28, 2011 [Page 3] Internet-Draft Content-Disposition in HTTP July 2010 1. Introduction HTTP/1.1 defines the Content-Disposition response header field in Section 19.5.1 of [RFC2616], 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]) of the header field, 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 = Reschke Expires January 28, 2011 [Page 4] Internet-Draft Content-Disposition in HTTP July 2010 Defined in [RFC2616]: token = value = Defined in [draft-reschke-rfc2231-in-http]: ext-value = 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' [[anchor3: Talk about expected behavior, mention security considerations.]] 3.4. Disposition Parameter: Extensions Parameters other than "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 header field wasn't present, but to remember the filename "foo.html" for a subsequent save operation: Content-Disposition: INLINE; FILENAME= "foo.html" Reschke Expires January 28, 2011 [Page 5] Internet-Draft Content-Disposition in HTTP July 2010 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 This specification does not introduce any changes to the registration procedures for disposition values and parameters that are defined in Section 9 of [RFC2183]. 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]). Header field name: Content-Disposition Applicable protocol: http Status: standard Author/Change controller: IETF Specification document: this specification (Section 3) 7. Acknowledgements [[anchor6: 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., Reschke Expires January 28, 2011 [Page 6] Internet-Draft Content-Disposition in HTTP July 2010 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. 8.2. Informative References [RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration Procedures for Message Header Fields", BCP 90, RFC 3864, September 2004. URIs [1] [2] 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: o 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. o The definition for the disposition type "inline" ([RFC2183], Section 2.1) has been re-added with a suggestion for its processing. o This specification requires support for the extended parameter encoding defined in [draft-reschke-rfc2231-in-http]. Appendix B. Differences compared to RFC 2183 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. Reschke Expires January 28, 2011 [Page 7] Internet-Draft Content-Disposition in HTTP July 2010 Appendix C. Alternative Approaches to Filename Escaping [[anchor10: Mention: RFC 2047, IE, Safari]] Appendix D. Change Log (to be removed by RFC Editor before publication) D.1. Since draft-reschke-rfc2183-in-http-00 Adjust terminology ("header" -> "header field"). Update rfc2231-in- http reference. Appendix E. Open issues (to be removed by RFC Editor prior to publication) E.1. edit Type: edit julian.reschke@greenbytes.de (2009-10-16): Umbrella issue for editorial fixes/enhancements. Index C Content-Disposition header 4 H Headers Content-Disposition 4 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/ Reschke Expires January 28, 2011 [Page 8]