[issue33476] String index out of range in get_group(), email/_header_value_parser.py

[Enrique Perez-Terron]

New submission from Enrique Perez-Terron :

When address group is missing final ';', 'value' will be an empty string. I 
suggest the following patch

$ diff -u _save_header_value_parser.py _header_value_parser.py
--- _save_header_value_parser.py2018-03-14 01:07:54.0 +0100
+++ _header_value_parser.py 2018-05-13 02:17:13.830053600 +0200
@@ -1876,7 +1876,7 @@
 if not value:
 group.defects.append(errors.InvalidHeaderDefect(
 "end of header in group"))
-if value[0] != ';':
+elif value[0] != ';':
 raise errors.HeaderParseError(
 "expected ';' at end of group but found {}".format(value))
 group.append(ValueTerminal(';', 'group-terminator'))

--
components: email
messages: 316440
nosy: Cacadril, barry, r.david.murray
priority: normal
severity: normal
status: open
title: String index out of range in get_group(), email/_header_value_parser.py
type: crash
versions: Python 3.6

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[issue33476] String index out of range in get_group(), email/_header_value_parser.py

[Enrique Perez-Terron]

Enrique Perez-Terron  added the comment:

Unsure how to issue a "PR" (Problem Report?) with a test case.

Here is my best effort:

Create a file "email.eml" in the current directory, as attached.
(The contents were lifted from RFC2822 section A.1.3, but I deleted the ";" at 
the end of the "To" header. The file has CRLF line endings.)

Then run the following test program (It appears that I can only attach one file 
to this ).

$ cat test-bug.py
from email.policy import default
import email

with open('email.eml', 'rb') as f:
msg = email.message_from_binary_file(f, policy=default)
toheader = msg['To']
for addr in toheader.addresses:
print(addr)

#
# Output without the fix:

$ python3.6.5 test-bug.py
Traceback (most recent call last):
  File "test-bug.py", line 6, in 
toheader = msg['To']
  File "C:\Program Files\Python36\lib\email\message.py", line 391, in 
__getitem__
return self.get(name)
  File "C:\Program Files\Python36\lib\email\message.py", line 471, in get
return self.policy.header_fetch_parse(k, v)
  File "C:\Program Files\Python36\lib\email\policy.py", line 162, in 
header_fetch_parse
return self.header_factory(name, value)
  File "C:\Program Files\Python36\lib\email\headerregistry.py", line 589, in 
__call__
return self[name](name, value)
  File "C:\Program Files\Python36\lib\email\headerregistry.py", line 197, in 
__new__
cls.parse(value, kwds)
  File "C:\Program Files\Python36\lib\email\headerregistry.py", line 340, in 
parse
kwds['parse_tree'] = address_list = cls.value_parser(value)
  File "C:\Program Files\Python36\lib\email\headerregistry.py", line 331, in 
value_parser
address_list, value = parser.get_address_list(value)
  File "C:\Program Files\Python36\lib\email\_header_value_parser.py", line 
1931, in get_address_list
token, value = get_address(value)
  File "C:\Program Files\Python36\lib\email\_header_value_parser.py", line 
1908, in get_address
token, value = get_group(value)
  File "C:\Program Files\Python36\lib\email\_header_value_parser.py", line 
1879, in get_group
if value[0] != ';':
IndexError: string index out of range

#-
# Output with the fix:

$ test-bug.py
Chris Jones 
j...@where.test
John 

--
Added file: https://bugs.python.org/file47606/email.eml

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