223584 - unknown XML media types not recognised as XML

Status: VERIFIED DUPLICATE of bug 155730

(Core Graveyard :: File Handling, defect)

Description

[Alan Plum]

User-Agent:       Mozilla/5.0 (Windows; U; Win98; en-US; rv:1.5) Gecko/20031007 Firebird/0.7
Build Identifier: Mozilla/5.0 (Windows; U; Win98; en-US; rv:1.5) Gecko/20031007 Firebird/0.7

Unknown or unregistered MIME media types with the +xml suffix are downloaded,
which is not the expected behavior for XML media types.

From RFC 3023:
"  It was thought that '+' expressed the semantics that a MIME type can
   be treated (for example) as both scalable vector graphics AND ALSO as
   XML; it is both simultaneously."
"A.15 Why must I use the '+xml' suffix for my new XML-based media type?
   You don't have to, but unless you have a good reason to explicitly
   disallow generic XML processing, you should use the suffix so as not
   to curtail the options of future users and developers."

It is expected that application/foo+xml is handled as XML file if no proper
treatment is available (eg. image/svg+xml should be rendered as XML if SVG is
not supported by the browser).

Reproducible: Always

Steps to Reproduce:
1. Upload an XML file with any unregistered extension (eg .foo) to a webserver
2. Set the file extension to be served as application/x-foo+xml
3. Open the URI of the file in Mozilla
Actual Results:  
Mozilla prompts with a download/open-with dialog.

Expected Results:  
Any unknown media type with the +xml suffix should be treated as application/xml
and handled apropriately.
If the media type uses the application top level type and no +xml suffix is
present, it should prompt for download or use of an external application.
If the media type uses the text top level type and no +xml suffix is present, it
should be rendered as text/plain.

RFC 3023 specifies the XML media types and treatment of media types using the
+xml suffix. It also obsoletes RFC 2376.

RFC 3023 specifies that media types using the +xml suffix conform to the XML
syntax as definied in the W3C XML1.0 Recommendation.

The only work around is using only MIME media types recognized by Mozilla, even
if there would be more specific standardized or registered media types.
Commonly used ('standardized') unregistered XML media types are (among others):
application/rdf+xml
application/rss+xml

RFC 3023: ftp://ftp.rfc-editor.org/in-notes/rfc3023.txt
RFC 2376: ftp://ftp.rfc-editor.org/in-notes/rfc2376.txt
XML1.0: http://www.w3.org/TR/2000/REC-xml-20001006

Comment 1

[Boris Zbarsky [:bzbarsky]]

*** This bug has been marked as a duplicate of 155730 ***

Comment 2

[timeless]

vrfy dupe