draft-ietf-httpbis-content-disp-04.txt   draft-ietf-httpbis-content-disp-05.txt 
HTTPbis Working Group J. Reschke HTTPbis Working Group J. Reschke
Internet-Draft greenbytes Internet-Draft greenbytes
Updates: 2616 (if approved) November 12, 2010 Updates: 2616 (if approved) February 17, 2011
Intended status: Standards Track Intended status: Standards Track
Expires: May 16, 2011 Expires: August 21, 2011
Use of the Content-Disposition Header Field in the Use of the Content-Disposition Header Field in the
Hypertext Transfer Protocol (HTTP) Hypertext Transfer Protocol (HTTP)
draft-ietf-httpbis-content-disp-04 draft-ietf-httpbis-content-disp-05
Abstract Abstract
HTTP/1.1 defines the Content-Disposition response header field, but 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 points out that it is not part of the HTTP/1.1 Standard. This
specification takes over the definition and registration of Content- specification takes over the definition and registration of Content-
Disposition, as used in HTTP, and clarifies internationalization Disposition, as used in HTTP, and clarifies internationalization
aspects. aspects.
Editorial Note (To be removed by RFC Editor before publication) Editorial Note (To be removed by RFC Editor before publication)
skipping to change at page 1, line 34 skipping to change at page 1, line 34
Disposition in the HTTP/1.1 specification, as currently revised by Disposition in the HTTP/1.1 specification, as currently revised by
the IETF HTTPbis working group. See also the IETF HTTPbis working group. See also
<http://trac.tools.ietf.org/wg/httpbis/trac/ticket/123>. <http://trac.tools.ietf.org/wg/httpbis/trac/ticket/123>.
Discussion of this draft should take place on the HTTPBIS working Discussion of this draft should take place on the HTTPBIS working
group mailing list (ietf-http-wg@w3.org). The current issues list is group mailing list (ietf-http-wg@w3.org). The current issues list is
at <http://trac.tools.ietf.org/wg/httpbis/trac/ at <http://trac.tools.ietf.org/wg/httpbis/trac/
query?component=content-disp> and related documents (including fancy query?component=content-disp> and related documents (including fancy
diffs) can be found at <http://tools.ietf.org/wg/httpbis/>. diffs) can be found at <http://tools.ietf.org/wg/httpbis/>.
The changes in this draft are summarized in Appendix D.8. The changes in this draft are summarized in Appendix D.9.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 16, 2011. This Internet-Draft will expire on August 21, 2011.
Copyright Notice Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 4 2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 4
3. Header Field Definition . . . . . . . . . . . . . . . . . . . 4 3. Conformance and Error Handling . . . . . . . . . . . . . . . . 4
3.1. Grammar . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Header Field Definition . . . . . . . . . . . . . . . . . . . 5
3.2. Disposition Type . . . . . . . . . . . . . . . . . . . . . 5 4.1. Grammar . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.3. Disposition Parameter: 'Filename' . . . . . . . . . . . . 6 4.2. Disposition Type . . . . . . . . . . . . . . . . . . . . . 6
3.4. Disposition Parameter: Extensions . . . . . . . . . . . . 7 4.3. Disposition Parameter: 'Filename' . . . . . . . . . . . . 6
3.5. Extensibility . . . . . . . . . . . . . . . . . . . . . . 7 4.4. Disposition Parameter: Extensions . . . . . . . . . . . . 7
4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 4.5. Extensibility . . . . . . . . . . . . . . . . . . . . . . 7
5. Internationalization Considerations . . . . . . . . . . . . . 8 5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 6. Internationalization Considerations . . . . . . . . . . . . . 8
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 7. Security Considerations . . . . . . . . . . . . . . . . . . . 8
7.1. Registry for Disposition Values and Parameter . . . . . . 8 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7.2. Header Field Registration . . . . . . . . . . . . . . . . 9 8.1. Registry for Disposition Values and Parameter . . . . . . 9
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9 8.2. Header Field Registration . . . . . . . . . . . . . . . . 9
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
9.1. Normative References . . . . . . . . . . . . . . . . . . . 9 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
9.2. Informative References . . . . . . . . . . . . . . . . . . 9 10.1. Normative References . . . . . . . . . . . . . . . . . . . 9
10.2. Informative References . . . . . . . . . . . . . . . . . . 10
Appendix A. Changes from the RFC 2616 Definition . . . . . . . . 10 Appendix A. Changes from the RFC 2616 Definition . . . . . . . . 10
Appendix B. Differences compared to RFC 2183 . . . . . . . . . . 11 Appendix B. Differences compared to RFC 2183 . . . . . . . . . . 11
Appendix C. Alternative Approaches to Internationalization . . . 11 Appendix C. Alternative Approaches to Internationalization . . . 11
C.1. RFC 2047 Encoding . . . . . . . . . . . . . . . . . . . . 11 C.1. RFC 2047 Encoding . . . . . . . . . . . . . . . . . . . . 11
C.2. Percent Encoding . . . . . . . . . . . . . . . . . . . . . 11 C.2. Percent Encoding . . . . . . . . . . . . . . . . . . . . . 12
C.3. Encoding Sniffing . . . . . . . . . . . . . . . . . . . . 12 C.3. Encoding Sniffing . . . . . . . . . . . . . . . . . . . . 12
C.4. Implementations (to be removed by RFC Editor before C.4. Implementations (to be removed by RFC Editor before
publication) . . . . . . . . . . . . . . . . . . . . . . . 12 publication) . . . . . . . . . . . . . . . . . . . . . . . 12
Appendix D. Change Log (to be removed by RFC Editor before Appendix D. Change Log (to be removed by RFC Editor before
publication) . . . . . . . . . . . . . . . . . . . . 12 publication) . . . . . . . . . . . . . . . . . . . . 13
D.1. Since draft-reschke-rfc2183-in-http-00 . . . . . . . . . . 13 D.1. Since draft-reschke-rfc2183-in-http-00 . . . . . . . . . . 13
D.2. Since draft-reschke-rfc2183-in-http-01 . . . . . . . . . . 13 D.2. Since draft-reschke-rfc2183-in-http-01 . . . . . . . . . . 13
D.3. Since draft-reschke-rfc2183-in-http-02 . . . . . . . . . . 13 D.3. Since draft-reschke-rfc2183-in-http-02 . . . . . . . . . . 13
D.4. Since draft-reschke-rfc2183-in-http-03 . . . . . . . . . . 13 D.4. Since draft-reschke-rfc2183-in-http-03 . . . . . . . . . . 13
D.5. Since draft-ietf-httpbis-content-disp-00 . . . . . . . . . 13 D.5. Since draft-ietf-httpbis-content-disp-00 . . . . . . . . . 13
D.6. Since draft-ietf-httpbis-content-disp-01 . . . . . . . . . 13 D.6. Since draft-ietf-httpbis-content-disp-01 . . . . . . . . . 13
D.7. Since draft-ietf-httpbis-content-disp-02 . . . . . . . . . 13 D.7. Since draft-ietf-httpbis-content-disp-02 . . . . . . . . . 13
D.8. Since draft-ietf-httpbis-content-disp-03 . . . . . . . . . 14 D.8. Since draft-ietf-httpbis-content-disp-03 . . . . . . . . . 14
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 D.9. Since draft-ietf-httpbis-content-disp-04 . . . . . . . . . 14
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction 1. Introduction
HTTP/1.1 defines the Content-Disposition response header field in 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 Section 19.5.1 of [RFC2616], but points out that it is not part of
the HTTP/1.1 Standard (Section 15.5): the HTTP/1.1 Standard (Section 15.5):
Content-Disposition is not part of the HTTP standard, but since it Content-Disposition is not part of the HTTP standard, but since it
is widely implemented, we are documenting its use and risks for is widely implemented, we are documenting its use and risks for
implementers. implementers.
skipping to change at page 4, line 36 skipping to change at page 4, line 36
2. Notational Conventions 2. Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
This specification uses the augmented BNF notation defined in Section This specification uses the augmented BNF notation defined in Section
2.1 of [RFC2616], including its rules for implied linear whitespace 2.1 of [RFC2616], including its rules for implied linear whitespace
(LWS). (LWS).
3. Header Field Definition 3. Conformance and Error Handling
This specification defines conformance criteria for both senders
(usually, HTTP origin servers) and recipients (usually, HTTP user
agents) of the Content-Location header field. An implementation is
considered conformant if it complies with all of the requirements
associated with its role.
This specification also defines certain forms of the header field-
value to be invalid, using both ABNF and prose requirements, but it
does not define special handling of these invalid field-values.
Sending implementations MUST NOT generate Content-Location header
fields that are invalid.
Consuming implementations MAY take steps to recover a usable field-
value from an invalid header field, but SHOULD NOT reject the message
outright, unless this is explicitly desirable behaviour (e.g., the
implementation is a validator). As such, the default handling of
invalid fields is to ignore them.
4. Header Field Definition
The Content-Disposition response header field is used to convey The Content-Disposition response header field is used to convey
additional information about how to process the response payload, and additional information about how to process the response payload, and
also can be used to attach additional metadata, such as the filename also can be used to attach additional metadata, such as the filename
to use when saving the response payload locally. to use when saving the response payload locally.
3.1. Grammar 4.1. Grammar
content-disposition = "Content-Disposition" ":" content-disposition = "Content-Disposition" ":"
disposition-type *( ";" disposition-parm ) disposition-type *( ";" disposition-parm )
disposition-type = "inline" | "attachment" | disp-ext-type disposition-type = "inline" | "attachment" | disp-ext-type
; case-insensitive ; case-insensitive
disp-ext-type = token disp-ext-type = token
disposition-parm = filename-parm | disp-ext-parm disposition-parm = filename-parm | disp-ext-parm
skipping to change at page 5, line 34 skipping to change at page 5, line 44
token = <token, defined in [RFC2616], Section 2.2> token = <token, defined in [RFC2616], Section 2.2>
quoted-string = <quoted-string, defined in [RFC2616], Section 2.2> quoted-string = <quoted-string, defined in [RFC2616], Section 2.2>
value = <value, defined in [RFC2616], Section 3.6> value = <value, defined in [RFC2616], Section 3.6>
; token | quoted-string ; token | quoted-string
Defined in [RFC5987]: Defined in [RFC5987]:
ext-value = <ext-value, defined in [RFC5987], Section 3.2> ext-value = <ext-value, defined in [RFC5987], Section 3.2>
Senders MUST NOT generate header field values with multiple instances Header field values with multiple instances of the same parameter
of the same parameter name. Recipients SHOULD treat these values as name are invalid.
invalid.
Note that due to the rules for implied linear whitespace (Section 2.1 Note that due to the rules for implied linear whitespace (Section 2.1
of [RFC2616]), OPTIONAL whitespace can appear between words (token or of [RFC2616]), OPTIONAL whitespace can appear between words (token or
quoted-string) and separator characters. quoted-string) and separator characters.
Furthermore note that the format used for ext-value allows specifying Furthermore note that the format used for ext-value allows specifying
a natural language; this is of limited use for filenames and is a natural language; this is of limited use for filenames and is
likely to be ignored by recipients. likely to be ignored by recipients.
3.2. Disposition Type 4.2. Disposition Type
If the disposition type matches "attachment" (case-insensitively), If the disposition type matches "attachment" (case-insensitively),
this indicates that the user agent should prompt the user to save the this indicates that the user agent should prompt the user to save the
response locally, rather than process it normally (as per its media response locally, rather than process it normally (as per its media
type). type).
On the other hand, if it matches "inline" (case-insensitively), this On the other hand, if it matches "inline" (case-insensitively), this
implies default processing. implies default processing.
Unknown or unhandled disposition types SHOULD be handled the same way Unknown or unhandled disposition types SHOULD be handled by
as "attachment" (see also [RFC2183], Section 2.8). recipients the same way as "attachment" (see also [RFC2183], Section
2.8).
3.3. Disposition Parameter: 'Filename' 4.3. Disposition Parameter: 'Filename'
The parameters "filename" and "filename*", to be matched case- The parameters "filename" and "filename*", to be matched case-
insensitively, provide information on how to construct a filename for insensitively, provide information on how to construct a filename for
storing the message payload. storing the message payload.
Depending on the disposition type, this information might be used Depending on the disposition type, this information might be used
right away (in the "save as..." interaction caused for the right away (in the "save as..." interaction caused for the
"attachment" disposition type), or later on (for instance, when the "attachment" disposition type), or later on (for instance, when the
user decides to save the contents of the current page being user decides to save the contents of the current page being
displayed). displayed).
skipping to change at page 6, line 34 skipping to change at page 6, line 46
"filename*" uses the encoding defined in [RFC5987], allowing the use "filename*" uses the encoding defined in [RFC5987], allowing the use
of characters not present in the ISO-8859-1 character set of characters not present in the ISO-8859-1 character set
([ISO-8859-1]). ([ISO-8859-1]).
Many user agent implementations predating this specification do not Many user agent implementations predating this specification do not
understand the "filename*" parameter. Therefore, when both understand the "filename*" parameter. Therefore, when both
"filename" and "filename*" are present in a single header field "filename" and "filename*" are present in a single header field
value, recipients SHOULD pick "filename*" and ignore "filename". value, recipients SHOULD pick "filename*" and ignore "filename".
This way, senders can avoid special-casing specific user agents by This way, senders can avoid special-casing specific user agents by
sending both the more expressive "filename*" parameter, and the sending both the more expressive "filename*" parameter, and the
"filename" parameter as fallback for legacy recipients (see Section 4 "filename" parameter as fallback for legacy recipients (see Section 5
for an example). for an example).
It is essential that user agents treat the specified filename as It is essential that user agents treat the specified filename as
advisory only, thus be very careful in extracting the desired advisory only, thus be very careful in extracting the desired
information. In particular: information. In particular:
o When the value contains path separator characters, all but the o When the value contains path separator characters ("\" or "/"),
last segment SHOULD be ignored. This prevents unintentional recipients SHOULD ignore all but the last path segment. This
overwriting of well-known file system location (such as "/etc/ prevents unintentional overwriting of well-known file system
passwd"). locations (such as "/etc/passwd").
o Many platforms do not use Internet Media Types ([RFC2046]) to hold o Many platforms do not use Internet Media Types ([RFC2046]) to hold
type information in the file system, but rely on filename type information in the file system, but rely on filename
extensions instead. Trusting the server-provided file extension extensions instead. Trusting the server-provided file extension
could introduce a privilege escalation when the saved file is could introduce a privilege escalation when the saved file is
later opened (consider ".exe"). Thus, recipients need to ensure later opened (consider ".exe"). Thus, recipients need to ensure
that a file extension is used that is safe, optimally matching the that a file extension is used that is safe, optimally matching the
media type of the received payload. media type of the received payload.
o Recipients are advised to strip or replace character sequences o Recipients are advised to strip or replace character sequences
skipping to change at page 7, line 20 skipping to change at page 7, line 33
o Other aspects recipients need to be aware of are names that have a o Other aspects recipients need to be aware of are names that have a
special meaning in the file system or in shell commands, such as special meaning in the file system or in shell commands, such as
"." and "..", "~", "|", and also device names. "." and "..", "~", "|", and also device names.
Note: Many user agents do not properly handle escape characters Note: Many user agents do not properly handle escape characters
when using the quoted-string form. Furthermore, some user agents when using the quoted-string form. Furthermore, some user agents
erroneously try to perform unescaping of "percent" escapes (see erroneously try to perform unescaping of "percent" escapes (see
Appendix C.2), and thus might misinterpret filenames containing Appendix C.2), and thus might misinterpret filenames containing
the percent character followed by two hex digits. the percent character followed by two hex digits.
3.4. Disposition Parameter: Extensions 4.4. Disposition Parameter: Extensions
To enable future extensions, unknown parameters SHOULD be ignored To enable future extensions, recipients SHOULD ignore unrecognized
(see also [RFC2183], Section 2.8). parameters (see also [RFC2183], Section 2.8).
3.5. Extensibility 4.5. Extensibility
Note that Section 9 of [RFC2183] defines IANA registries both for Note that Section 9 of [RFC2183] defines IANA registries both for
disposition types and disposition parameters. This registry is disposition types and disposition parameters. This registry is
shared by different protocols using Content-Disposition, such as MIME shared by different protocols using Content-Disposition, such as MIME
and HTTP. Therefore, not all registered values may make sense in the and HTTP. Therefore, not all registered values may make sense in the
context of HTTP. context of HTTP.
4. Examples 5. Examples
Direct UA to show "save as" dialog, with a filename of Direct UA to show "save as" dialog, with a filename of
"example.html": "example.html":
Content-Disposition: Attachment; filename=example.html Content-Disposition: Attachment; filename=example.html
Direct UA to behave as if the Content-Disposition header field wasn't Direct UA to behave as if the Content-Disposition header field wasn't
present, but to remember the filename "an example.html" for a present, but to remember the filename "an example.html" for a
subsequent save operation: subsequent save operation:
Content-Disposition: INLINE; FILENAME= "an example.html" Content-Disposition: INLINE; FILENAME= "an example.html"
Note: this uses the quoted-string form so that the space character Note: this uses the quoted-string form so that the space character
can be included. can be included.
Direct UA to show "save as" dialog, with a filename containing the Direct UA to show "save as" dialog, with a filename containing the
skipping to change at page 8, line 21 skipping to change at page 8, line 29
Here, the encoding defined in [RFC5987] is also used to encode the Here, the encoding defined in [RFC5987] is also used to encode the
non-ISO-8859-1 character. non-ISO-8859-1 character.
Same as above, but adding the "filename" parameter for compatibility Same as above, but adding the "filename" parameter for compatibility
with user agents not implementing RFC 5987: with user agents not implementing RFC 5987:
Content-Disposition: attachment; Content-Disposition: attachment;
filename="EURO rates"; filename="EURO rates";
filename*=utf-8''%e2%82%ac%20rates filename*=utf-8''%e2%82%ac%20rates
Note: as of November 2010, those user agents that do not support the Note: as of February 2011, those user agents that do not support the
RFC 5987 encoding ignore "filename*" when it occurs after "filename". RFC 5987 encoding ignore "filename*" when it occurs after "filename".
Unfortunately, some user agents that do support RFC 5987 do pick the Unfortunately, some user agents that do support RFC 5987 do pick the
"filename" rather than the "filename*" parameter when it occurs "filename" rather than the "filename*" parameter when it occurs
first; it is expected that this situation is going to improve soon. first; it is expected that this situation is going to improve soon.
5. Internationalization Considerations 6. Internationalization Considerations
The "filename*" parameter (Section 3.3), using the encoding defined The "filename*" parameter (Section 4.3), using the encoding defined
in [RFC5987], allows the server to transmit characters outside the in [RFC5987], allows the server to transmit characters outside the
ISO-8859-1 character set, and also to optionally specify the language ISO-8859-1 character set, and also to optionally specify the language
in use. in use.
Future parameters might also require internationalization, in which Future parameters might also require internationalization, in which
case the same encoding can be used. case the same encoding can be used.
6. Security Considerations 7. Security Considerations
Using server-supplied information for constructing local filenames Using server-supplied information for constructing local filenames
introduces many risks. These are summarized in Section 3.3. introduces many risks. These are summarized in Section 4.3.
Furthermore, implementers also ought to be aware of the Security Furthermore, implementers also ought to be aware of the Security
Considerations applying to HTTP (see Section 15 of [RFC2616]), and Considerations applying to HTTP (see Section 15 of [RFC2616]), and
also the parameter encoding defined in [RFC5987] (see Section 5). also the parameter encoding defined in [RFC5987] (see Section 5).
7. IANA Considerations 8. IANA Considerations
7.1. Registry for Disposition Values and Parameter 8.1. Registry for Disposition Values and Parameter
This specification does not introduce any changes to the registration This specification does not introduce any changes to the registration
procedures for disposition values and parameters that are defined in procedures for disposition values and parameters that are defined in
Section 9 of [RFC2183]. Section 9 of [RFC2183].
7.2. Header Field Registration 8.2. Header Field Registration
This document updates the definition of the Content-Disposition HTTP This document updates the definition of the Content-Disposition HTTP
header field in the permanent HTTP header field registry (see header field in the permanent HTTP header field registry (see
[RFC3864]). [RFC3864]).
Header field name: Content-Disposition Header field name: Content-Disposition
Applicable protocol: http Applicable protocol: http
Status: standard Status: standard
Author/Change controller: IETF Author/Change controller: IETF
Specification document: this specification (Section 3) Specification document: this specification (Section 4)
8. Acknowledgements 9. Acknowledgements
Thanks to Adam Barth, Rolf Eike Beer, Bjoern Hoehrmann, Alfred Thanks to Adam Barth, Rolf Eike Beer, Bjoern Hoehrmann, Alfred
Hoenes, Roar Lauritzsen, Henrik Nordstrom, and Mark Nottingham for Hoenes, Roar Lauritzsen, Henrik Nordstrom, and Mark Nottingham for
their valuable feedback. their valuable feedback.
9. References 10. References
9.1. Normative References 10.1. Normative References
[ISO-8859-1] International Organization for Standardization, [ISO-8859-1] International Organization for Standardization,
"Information technology -- 8-bit single-byte coded "Information technology -- 8-bit single-byte coded
graphic character sets -- Part 1: Latin alphabet No. graphic character sets -- Part 1: Latin alphabet No.
1", ISO/IEC 8859-1:1998, 1998. 1", ISO/IEC 8859-1:1998, 1998.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC5987] Reschke, J., "Character Set and Language Encoding for [RFC5987] Reschke, J., "Character Set and Language Encoding for
Hypertext Transfer Protocol (HTTP) Header Field Hypertext Transfer Protocol (HTTP) Header Field
Parameters", RFC 5987, August 2010. Parameters", RFC 5987, August 2010.
9.2. Informative References 10.2. Informative References
[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet [RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet
Mail Extensions (MIME) Part Two: Media Types", Mail Extensions (MIME) Part Two: Media Types",
RFC 2046, November 1996. RFC 2046, November 1996.
[RFC2047] Moore, K., "MIME (Multipurpose Internet Mail [RFC2047] Moore, K., "MIME (Multipurpose Internet Mail
Extensions) Part Three: Message Header Extensions for Extensions) Part Three: Message Header Extensions for
Non-ASCII Text", RFC 2047, November 1996. Non-ASCII Text", RFC 2047, November 1996.
[RFC2183] Troost, R., Dorner, S., and K. Moore, "Communicating [RFC2183] Troost, R., Dorner, S., and K. Moore, "Communicating
skipping to change at page 12, line 21 skipping to change at page 12, line 29
Some user agents inspect the value (which defaults to ISO-8859-1 for Some user agents inspect the value (which defaults to ISO-8859-1 for
the quoted-string form) and switch to UTF-8 when it seems to be more the quoted-string form) and switch to UTF-8 when it seems to be more
likely to be the correct interpretation. likely to be the correct interpretation.
As with the approaches above, this is not interoperable and As with the approaches above, this is not interoperable and
furthermore risks misinterpreting the actual value. furthermore risks misinterpreting the actual value.
C.4. Implementations (to be removed by RFC Editor before publication) C.4. Implementations (to be removed by RFC Editor before publication)
Unfortunately, as of November 2010, neither the encoding defined in Unfortunately, as of February 2011, neither the encoding defined in
RFCs 2231 and 5987, nor any of the alternate approaches discussed RFCs 2231 and 5987, nor any of the alternate approaches discussed
above was implemented interoperably. Thus, this specification above was implemented interoperably. Thus, this specification
recommends the approach defined in RFC 5987, which at least has the recommends the approach defined in RFC 5987, which at least has the
advantage of actually being specified properly. advantage of actually being specified properly.
The table below shows the implementation support for the various The table below shows the implementation support for the various
approaches: approaches:
+---------------+------------+--------+--------------+--------------+ +---------------+------------+--------+--------------+--------------+
| User Agent | RFC | RFC | Percent | Encoding | | User Agent | RFC | RFC | Percent | Encoding |
| | 2231/5987 | 2047 | Encoding | Sniffing | | | 2231/5987 | 2047 | Encoding | Sniffing |
+---------------+------------+--------+--------------+--------------+ +---------------+------------+--------+--------------+--------------+
| Chrome | no (*) | yes | yes | yes | | Chrome | yes | yes | yes | yes |
| Firefox | yes (**) | yes | no | yes | | Firefox | yes (*) | yes | no | yes |
| Internet | no | no | yes | no | | Internet | yes (**) | no | yes | no |
| Explorer | | | | | | Explorer | | | | |
| Konqueror | yes | no | no | no | | Konqueror | yes | no | no | no |
| Opera | yes | no | no | no | | Opera | yes | no | no | no |
| Safari | no | no | no | yes | | Safari | no | no | no | yes |
+---------------+------------+--------+--------------+--------------+ +---------------+------------+--------+--------------+--------------+
(*) But currently being implemented. (*) Does not implement the fallback behavior to "filename" described
in Section 4.3.
(**) Does not implement the fallback behavior to "filename" described (**) Starting with IE9RC, but only implements UTF-8.
in Section 3.3.
Appendix D. Change Log (to be removed by RFC Editor before publication) Appendix D. Change Log (to be removed by RFC Editor before publication)
Note: the issues names in the change log entries for Note: the issues names in the change log entries for
draft-reschke-rfc2183-in-http refer to <http://greenbytes.de/tech/ draft-reschke-rfc2183-in-http refer to <http://greenbytes.de/tech/
webdav/draft-reschke-rfc2183-in-http-issues.html>. webdav/draft-reschke-rfc2183-in-http-issues.html>.
D.1. Since draft-reschke-rfc2183-in-http-00 D.1. Since draft-reschke-rfc2183-in-http-00
Adjust terminology ("header" -> "header field"). Update rfc2231-in- Adjust terminology ("header" -> "header field"). Update rfc2231-in-
skipping to change at page 14, line 31 skipping to change at page 14, line 40
o <http://tools.ietf.org/wg/httpbis/trac/ticket/263>: "text about o <http://tools.ietf.org/wg/httpbis/trac/ticket/263>: "text about
historical percent-decoding unclear" historical percent-decoding unclear"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/264>: "add o <http://tools.ietf.org/wg/httpbis/trac/ticket/264>: "add
explanation of language tagging" explanation of language tagging"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/265>: "Clarify that o <http://tools.ietf.org/wg/httpbis/trac/ticket/265>: "Clarify that
C-D spec does not apply to multipart upload" C-D spec does not apply to multipart upload"
D.9. Since draft-ietf-httpbis-content-disp-04
Updated implementation information (Chrome 9 implements RFC 5987, IE
9 RC implements it for UTF-8 only).
Clarify who requirements are on, add a section discussing conformance
and handling of invalid field values in general.
Closed issues:
o <http://tools.ietf.org/wg/httpbis/trac/ticket/272>: "Path
Separator Characters"
Index Index
C C
Content-Disposition header 4 Content-Disposition header 5
H H
Headers Headers
Content-Disposition 4 Content-Disposition 5
Author's Address Author's Address
Julian F. Reschke Julian F. Reschke
greenbytes GmbH greenbytes GmbH
Hafenweg 16 Hafenweg 16
Muenster, NW 48155 Muenster, NW 48155
Germany Germany
EMail: julian.reschke@greenbytes.de EMail: julian.reschke@greenbytes.de
 End of changes. 43 change blocks. 
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