forked from MirrorHub/synapse
Fix parsing of Content-Disposition headers (#4763)
* Fix parsing of Content-Disposition headers TIL: filenames in content-dispostion headers can contain semicolons, and aren't %-encoded. * fix python2 incompatibility * Fix docstrings
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3 changed files with 111 additions and 20 deletions
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changelog.d/4763.bugfix
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changelog.d/4763.bugfix
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Fix parsing of Content-Disposition headers on remote media requests and URL previews.
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@ -1,5 +1,6 @@
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# -*- coding: utf-8 -*-
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# Copyright 2014-2016 OpenMarket Ltd
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# Copyright 2019 New Vector Ltd.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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@ -213,8 +214,7 @@ def get_filename_from_headers(headers):
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Content-Disposition HTTP header.
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Args:
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headers (twisted.web.http_headers.Headers): The HTTP
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request headers.
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headers (dict[bytes, list[bytes]]): The HTTP request headers.
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Returns:
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A Unicode string of the filename, or None.
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@ -225,23 +225,12 @@ def get_filename_from_headers(headers):
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if not content_disposition[0]:
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return
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# dict of unicode: bytes, corresponding to the key value sections of the
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# Content-Disposition header.
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params = {}
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parts = content_disposition[0].split(b";")
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for i in parts:
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# Split into key-value pairs, if able
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# We don't care about things like `inline`, so throw it out
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if b"=" not in i:
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continue
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key, value = i.strip().split(b"=")
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params[key.decode('ascii')] = value
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_, params = _parse_header(content_disposition[0])
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upload_name = None
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# First check if there is a valid UTF-8 filename
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upload_name_utf8 = params.get("filename*", None)
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upload_name_utf8 = params.get(b"filename*", None)
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if upload_name_utf8:
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if upload_name_utf8.lower().startswith(b"utf-8''"):
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upload_name_utf8 = upload_name_utf8[7:]
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@ -267,12 +256,68 @@ def get_filename_from_headers(headers):
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# If there isn't check for an ascii name.
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if not upload_name:
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upload_name_ascii = params.get("filename", None)
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upload_name_ascii = params.get(b"filename", None)
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if upload_name_ascii and is_ascii(upload_name_ascii):
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# Make sure there's no %-quoted bytes. If there is, reject it as
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# non-valid ASCII.
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if b"%" not in upload_name_ascii:
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upload_name = upload_name_ascii.decode('ascii')
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upload_name = upload_name_ascii.decode('ascii')
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# This may be None here, indicating we did not find a matching name.
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return upload_name
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def _parse_header(line):
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"""Parse a Content-type like header.
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Cargo-culted from `cgi`, but works on bytes rather than strings.
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Args:
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line (bytes): header to be parsed
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Returns:
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Tuple[bytes, dict[bytes, bytes]]:
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the main content-type, followed by the parameter dictionary
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"""
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parts = _parseparam(b';' + line)
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key = next(parts)
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pdict = {}
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for p in parts:
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i = p.find(b'=')
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if i >= 0:
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name = p[:i].strip().lower()
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value = p[i + 1:].strip()
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# strip double-quotes
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if len(value) >= 2 and value[0:1] == value[-1:] == b'"':
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value = value[1:-1]
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value = value.replace(b'\\\\', b'\\').replace(b'\\"', b'"')
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pdict[name] = value
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return key, pdict
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def _parseparam(s):
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"""Generator which splits the input on ;, respecting double-quoted sequences
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Cargo-culted from `cgi`, but works on bytes rather than strings.
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Args:
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s (bytes): header to be parsed
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Returns:
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Iterable[bytes]: the split input
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"""
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while s[:1] == b';':
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s = s[1:]
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# look for the next ;
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end = s.find(b';')
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# if there is an odd number of " marks between here and the next ;, skip to the
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# next ; instead
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while end > 0 and (s.count(b'"', 0, end) - s.count(b'\\"', 0, end)) % 2:
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end = s.find(b';', end + 1)
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if end < 0:
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end = len(s)
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f = s[:end]
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yield f.strip()
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s = s[end:]
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45
tests/rest/media/v1/test_base.py
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tests/rest/media/v1/test_base.py
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# -*- coding: utf-8 -*-
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# Copyright 2019 New Vector Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from synapse.rest.media.v1._base import get_filename_from_headers
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from tests import unittest
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class GetFileNameFromHeadersTests(unittest.TestCase):
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# input -> expected result
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TEST_CASES = {
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b"inline; filename=abc.txt": u"abc.txt",
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b'inline; filename="azerty"': u"azerty",
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b'inline; filename="aze%20rty"': u"aze%20rty",
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b'inline; filename="aze\"rty"': u'aze"rty',
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b'inline; filename="azer;ty"': u"azer;ty",
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b"inline; filename*=utf-8''foo%C2%A3bar": u"foo£bar",
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}
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def tests(self):
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for hdr, expected in self.TEST_CASES.items():
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res = get_filename_from_headers(
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{
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b'Content-Disposition': [hdr],
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},
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)
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self.assertEqual(
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res, expected,
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"expected output for %s to be %s but was %s" % (
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hdr, expected, res,
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)
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)
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