Python library to get filename of content downloaded with HTTP

I download a file using the get function of Python requests library. For storing the file, I'd like to determine the filename they way a web browser would for its 'save' or 'save as . ' dialog. Easy, right? I can just get it from the Content-Disposition HTTP header, accessible on the response object:

import re d = r.headers['content-disposition'] fname = re.findall("filename=(.+)", d) 

But looking more closely at this topic, it isn't that easy: According to RFC 6266 section 4.3, and the grammar in the section 4.1, the value can be an unquoted token (e.g. the_report.pdf ) or a quoted string that can also contain whitespace (e.g. "the report.pdf" ) and escape sequences (the latter are discouraged, though, thus their handling isn't a hard requirement for me). Further,

when both "filename" and "filename*" are present in a single header field value, [we] SHOULD pick "filename*" and ignore "filename".

The value of filename* , though, is yet a bit more complicated than the one of filename . Also, the RFC seems to allow for additional whitespace around the = . Thus, for the examples listed in the RFC, I'd want the following results:

- Content-Disposition: Attachment; filename=example.html filename: example.html

 Content-Disposition: INLINE; FILENAME= "an example.html" 

filename: an example.html

 Content-Disposition: attachment; filename*= UTF-8''%e2%82%ac%20rates 

filename: € rates

 Content-Disposition: attachment; filename="EURO rates"; filename*=utf-8''%e2%82%ac%20rates 

filename: € rates here, too (not EURO rates , as filename* takes precedence) I could implement the parsing of the Content-Disposition header I get from requests accordingly myself, but if I can avoid it and use an existing proven implementation instead, I'd prefer that. Is there a Python library that can do this?

Requirements

• provide a function that extracts and returns the proper filename (if there is one) from a passed requests response
  or
• provide a function that extracts and returns the proper filename (if there is one) from a passed Content-Disposition header field value (a string)
  or
• provide a function accepting the all the same parameters as requests.get that performs the request, and returns the response as well as the filename (if there is one)
  or
• provides something similarly practical

Non-requirements

What it doesn't have to handle (but if it does, even better) as I can do that myself:

• sanitize values so that they don't contain directory names or other path elements except for a single filename, so storing with that name won't cause files to be created or overwritten at arbitrary locations
• produce "save" filename extensions "optimally matching the media type of the received payload" (see section 4.3)
• sanitize filenames to prevent user confusion (section 4.3 mentions replacing "control characters and leading and trailing whitespace")
• provide a fall-back
  • for when neither the filename nor the filename* disposition parameter are present or
  • for when the ones that are present cannot be parsed or
  • for when the complete Content-Disposition header is missing

  Though it should report that consistently (be it by raising or by returning None or '' ), so that I can let my own fall-back kick in.