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Fix URL preview errors when previewing XML documents. (#11196)

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Patrick Cloke 2021-10-27 10:48:02 -04:00 committed by GitHub
parent e0ef8fe58d
commit b3e843be88
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3 changed files with 22 additions and 3 deletions
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1
changelog.d/11196.bugfix Normal file
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@ -0,0 +1 @@
Fix a bug introduced in v1.46.0rc1 where URL previews of some XML documents would fail.

9
synapse/rest/media/v1/preview_url_resource.py
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@ -718,9 +718,12 @@ def decode_body(
if not body:
return None
# The idea here is that multiple encodings are tried until one works.
# Unfortunately the result is never used and then LXML will decode the string
# again with the found encoding.
for encoding in get_html_media_encodings(body, content_type):
try:
body_str = body.decode(encoding)
body.decode(encoding)
except Exception:
pass
else:
@ -732,11 +735,11 @@ def decode_body(
from lxml import etree
# Create an HTML parser.
parser = etree.HTMLParser(recover=True, encoding="utf-8")
parser = etree.HTMLParser(recover=True, encoding=encoding)
# Attempt to parse the body. Returns None if the body was successfully
# parsed, but no tree was found.
return etree.fromstring(body_str, parser)
return etree.fromstring(body, parser)
def _calc_og(tree: "etree.Element", media_uri: str) -> Dict[str, Optional[str]]:

15
tests/test_preview.py
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@ -277,6 +277,21 @@ class CalcOgTestCase(unittest.TestCase):
tree = decode_body(html, "http://example.com/test.html")
self.assertIsNone(tree)
def test_xml(self):
"""Test decoding XML and ensure it works properly."""
# Note that the strip() call is important to ensure the xml tag starts
# at the initial byte.
html = b"""
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head><title>Foo</title></head><body>Some text.</body></html>
""".strip()
tree = decode_body(html, "http://example.com/test.html")
og = _calc_og(tree, "http://example.com/test.html")
self.assertEqual(og, {"og:title": "Foo", "og:description": "Some text."})
def test_invalid_encoding(self):
"""An invalid character encoding should be ignored and treated as UTF-8, if possible."""
html = b"""