[Regression fix] [Data URI parser] Accept data URI with invalid mediatype data

net/base/data_url.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // NOTE: based loosely on mozilla's nsDataChannel.cpp
 
 #include <algorithm>
 
 #include "net/base/data_url.h"
 
@@ skipping 47 matching lines @@
     } else if (charset->empty() &&
                iter->compare(0, kCharsetTagLength, kCharsetTag) == 0) {
       charset->assign(iter->substr(kCharsetTagLength));
       // The grammar for charset is not specially defined in RFC2045 and
       // RFC2397. It just needs to be a token.
       if (!net::HttpUtil::IsToken(*charset))
         return false;
     }
   }
 
-  if (mime_type->empty()) {
-    // fallback to defaults if nothing specified in the URL:
+  if (mime_type->empty() ||
+      !ParseMimeTypeWithoutParameter(*mime_type, NULL, NULL)) {
+    // Fallback to the default if nothing specified in the mediatype part as
+    // specified in RFC2045. We also fallback to the default when the mediatype
+    // value is invalid as recommended in the RFC.
     mime_type->assign("text/plain");

[asanka, 2014/09/30 18:35:51]

If you are setting the mime_type, also set the charset here. We don't want to
accept one but not the other. This will be a slight behavior change for the
empty MIME type case, but is correct according to the spec.

[tyoshino (SeeGerritForStatus), 2014/10/01 01:03:54]

As specified in RFC2397, when the mime type is empty, we still need to parse the
input and use charset parameter in it.

For invalid mime type case, I've added charset->assign("US-ASCII") as you
suggested.

-  } else if (!ParseMimeTypeWithoutParameter(*mime_type, NULL, NULL)) {
-    return false;
   }
   if (charset->empty())
     charset->assign("US-ASCII");
 
   // The caller may not be interested in receiving the data.
   if (!data)
     return true;
 
   // Preserve spaces if dealing with text or xml input, same as mozilla:
   //   https://bugzilla.mozilla.org/show_bug.cgi?id=138052
@@ skipping 40 matching lines @@
       temp_data.resize(length + padding_needed, '=');
     }
     return base::Base64Decode(temp_data, data);
   }
 
   temp_data.swap(*data);
   return true;
 }
 
 }  // namespace net