[Bug 8101] DecodeShortURLs fails to resolve chained relative location paths

[bu...@spamassassin.apache.org]

https://bz.apache.org/SpamAssassin/show_bug.cgi?id=8101

Sidney Markowitz <si...@sidney.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sidney@sidney.com
           Hardware|PC                          |All
                 OS|Linux                       |All

--- Comment #1 from Sidney Markowitz <si...@sidney.com> ---
Thanks for catching the problem. On analysis, I don't think the problem is in
how SpamAssassin handles parsing of the URL as in RFC 3986. The server at bitly
gets it and provides a redirect result based on what it thinks the URL means,
and SpamAssassin uses whatever is handed back.

When it has a URL that looks like https://bit.ly//1Zmfo8z DecodeShortURL.pm
gets to line 853

  # Check if we are being redirected to a local page                            
  # Don't recurse in this case...                                               

and at line 864

    $location = "$short_url/$location";
    dbg("looks like a local redirection: $orig_short_url => $location
($orig_location)");
    $pms->add_uri_detail_list($location) if
!$pms->{uri_detail_list}->{$location};
    return;

In this case, as you can see from the output of

  curl -I https://bit.ly//1Zmfo8z

the bitly server handles the parsing and returns a redirect to /1Zmfo8z which
the above code handles as a redirect to a local page.

That's the bug, as RFC 7231 says

"Location = URI-reference

The field value consists of a single URI-reference. When it has the form of a
relative reference ([RFC3986], Section 4.2), the final value is computed by
resolving it against the effective request URI ([RFC3986], Section 5)."

So when the code determines that the redirect location is a relative URL like
/1Zmfo8z it should change it to https://bit.ly/1Zmfo8z and recurse.

I'll work up a patch and add a test case.

-- 
You are receiving this mail because:
You are the assignee for the bug.