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bpo-39040: Fix parsing of email mime headers with whitespace between encoded-words. #17620

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Merged
bitdancer merged 4 commits into from
May 29, 2020
Merged

bpo-39040: Fix parsing of email mime headers with whitespace between encoded-words. #17620

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9da6ddf
bpo-39040: Fix parsing of email headers with whitespace between encod…
maxking Dec 16, 2019
bf2cb76
Remove empty lines, add a new test and update the news entry.
maxking Dec 17, 2019
004f37d
Update test to include spaces around an encoded word.
maxking Dec 18, 2019
016ceb3
Fix the encoded word syntax and resultant error.
maxking Dec 18, 2019
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bpo-39040: Fix parsing of email headers with whitespace between encod… 
…ed-words.

In certain malformed content-disposition headers, parameter values are quoted
and split as encoded words on two lines with extra whitespaces. This fixes the
issue by removing the extra whitespace between the two encoded words.
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@maxking
maxking committed Dec 16, 2019
commit 9da6ddfd98454f2c287d46396e3b1a2563ffd7a1
11 changes: 11 additions & 0 deletions Lib/email/_header_value_parser.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1218,12 +1218,23 @@ def get_bare_quoted_string(value):
if value[0] in WSP:
token, value = get_fws(value)
elif value[:2] == '=?':
valid_ew = False
try:
token, value = get_encoded_word(value)
bare_quoted_string.defects.append(errors.InvalidHeaderDefect(
"encoded word inside quoted string"))
valid_ew = True
except errors.HeaderParseError:
token, value = get_qcontent(value)

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# Collapse the whitespace between two encoded words that occur in a
# bare-quoted-string.
if valid_ew and len(bare_quoted_string) > 1:
if (bare_quoted_string[-1].token_type == 'fws' and
bare_quoted_string[-2].token_type == 'encoded-word'):

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bare_quoted_string[-1] = EWWhiteSpaceTerminal(
bare_quoted_string[-1], 'fws')
else:
token, value = get_qcontent(value)
bare_quoted_string.append(token)
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10 changes: 10 additions & 0 deletions Lib/test/test_email/test_headerregistry.py
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Expand Up @@ -873,6 +873,16 @@ def content_disp_as_value(self,
{'filename': 'foo'},
[errors.InvalidHeaderDefect]),

'invalid_value_with_fws_bw_ew': (
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'attachment; filename="=?UTF-8?Q?Schulbesuchsbest=C3=A4ttigung=2E?='
' =?UTF-8?Q?pdf?="',
'attachment',
{'filename': 'Schulbesuchsbestättigung.pdf'},
[errors.InvalidHeaderDefect]*3,
('attachment; filename="Schulbesuchsbestättigung.pdf"'),
('Content-Disposition: attachment;\n'
' filename*=utf-8\'\'Schulbesuchsbest%C3%A4ttigung.pdf\n'),
)
}


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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2019-12-15-18-47-20.bpo-39040.tKa0Qs.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Fix parsing of invalid Content-Disposition email headers by collapsing
whitespace between encoded words in a bare-quote-string.
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