id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
23397	Multipart base64 file decoding of fails with large files when the encoded string contains newlines.	jhobbs	nobody	"Large files are files larger than the chunk size in MultiPartParser.parse().

parse() tries to process base64 encoded files in chunks with lengths a multiple of 4. The base64 encoded string can contain newline characters, which aren't significant in base64 and should be ignored, but are counted toward's a chunk's length in parse(). This means when whitespace is stripped from the string, the count of base64 encoded characters may not be a multiple of 4, leading to an ""Incorrect padding"" error.

Here's a testcase for creating this failure:

https://github.com/jhobbs/django/commit/98347e396133990b82b596310e4490369ba676d5

Stacktrace:
{{{
Traceback (most recent call last):
  File ""/home/jason/canonical/code/django/tests/file_uploads/tests.py"", line 109, in test_big_base64_newlines_upload
    ""Big data"" * 68000, encode=base64.encodestring)
  File ""/home/jason/canonical/code/django/tests/file_uploads/tests.py"", line 96, in _test_base64_upload
    response = self.client.request(**r)
  File ""/home/jason/canonical/code/django/django/test/client.py"", line 443, in request
    six.reraise(*exc_info)
  File ""/home/jason/canonical/code/django/django/core/handlers/base.py"", line 121, in get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File ""/home/jason/canonical/code/django/tests/file_uploads/views.py"", line 103, in file_upload_echo_content
    r = dict((k, f.read().decode('utf-8')) for k, f in request.FILES.items())
  File ""/home/jason/canonical/code/django/django/core/handlers/wsgi.py"", line 152, in _get_files
    self._load_post_and_files()
  File ""/home/jason/canonical/code/django/django/http/request.py"", line 249, in _load_post_and_files
    self._post, self._files = self.parse_file_upload(self.META, data)
  File ""/home/jason/canonical/code/django/django/http/request.py"", line 214, in parse_file_upload
    return parser.parse()
  File ""/home/jason/canonical/code/django/django/http/multipartparser.py"", line 220, in parse
    six.reraise(MultiPartParserError, MultiPartParserError(msg), sys.exc_info()[2])
  File ""/home/jason/canonical/code/django/django/http/multipartparser.py"", line 216, in parse
    chunk = base64.b64decode(chunk)
  File ""/usr/lib/python2.7/base64.py"", line 76, in b64decode
    raise TypeError(msg)
MultiPartParserError: Could not decode base64 data: TypeError(Error('Incorrect padding',),)
}}}"	Bug	new	HTTP handling	1.6	Normal				Unreviewed	0	0	0	0	0	0