parse_message_id() was improperly using a token defined inside an exception
handler, which was raising `UnboundLocalError` on parsing an invalid value.
https://bugs.python.org/issue38698
Fixes a case in which email._header_value_parser.get_unstructured hangs the system for some invalid headers. This covers the cases in which the header contains either:
- a case without trailing whitespace
- an invalid encoded word
https://bugs.python.org/issue37764
This fix should also be backported to 3.7 and 3.8
https://bugs.python.org/issue37764
This should fix the IndexError trying to retrieve `DisplayName.display_name` and `DisplayName.value` when the `value` is basically an empty string.
https://bugs.python.org/issue32178
* bpo-37461: Fix infinite loop in parsing of specially crafted email headers.
Some crafted email header would cause the get_parameter method to run in an
infinite loop causing a DoS attack surface when parsing those headers. This
patch fixes that by making sure the DQUOTE character is handled to prevent
going into an infinite loop.
* patched string index out of range error in get_word function of _header_value_parser.py and created tests in test__header_value_parser.py for CFWS.
* Raise HeaderParseError instead of continuing when parsing a word.
* bpo-21315: Fix parsing of encoded words with missing leading ws.
Because of missing leading whitespace, encoded word would get parsed as
unstructured token. This patch fixes that by looking for encoded words when
splitting tokens with whitespace.
Missing trailing whitespace around encoded word now register a defect
instead.
Original patch suggestion by David R. Murray on bpo-21315.
* bpo-35805: Add parser for Message-ID header.
This parser is based on the definition of Identification Fields from RFC 5322
Sec 3.6.4.
This should also prevent folding of Message-ID header using RFC 2047 encoded
words and hence fix bpo-35805.
* Prevent folding of non-ascii message-id headers.
* Add fold method to MsgID token to prevent folding.
When attempting to base64-decode a payload of invalid length (1 mod 4),
properly recognize and handle it. The given data will be returned as-is,
i.e. not decoded, along with a new defect, InvalidBase64LengthDefect.
The original algorithm tried to delegate the folding to the tokens so
that those tokens whose folding rules differed could specify the
differences. However, this resulted in a lot of duplicated code because
most of the rules were the same.
The new algorithm moves all folding logic into a set of functions
external to the token classes, but puts the information about which
tokens can be folded in which ways on the tokens...with the exception of
mime-parameters, which are a special case (which was not even
implemented in the old folder).
This algorithm can still probably be improved and hopefully simplified
somewhat.
Note that some of the test expectations are changed. I believe the
changes are toward more desirable and consistent behavior: in general
when (re) folding a line the canonical version of the tokens is
generated, rather than preserving errors or extra whitespace.
Leading whitespace was incorrectly dropped during folding of certain lines in the _header_value_parser's folding algorithm. This makes the whitespace handling code consistent.
This mimics get_param's error handling for the most part. It is slightly
better in some regards as get_param can produce some really weird results for
duplicate *0* parts. It departs from get_param slightly in that if we have a
mix of non-extended and extended pieces for the same parameter name, the new
parser assumes they were all supposed to be extended and concatenates all the
values, whereas get_param always picks the non-extended parameter value. All
of this error recovery is pretty much arbitrary decisions...
This applies only to the new parser. The old parser decodes encoded words
inside quoted strings already, although it gets the whitespace wrong
when it does so.
This version of the patch only handles the most common case (a single encoded
word surrounded by quotes), but I haven't seen any other variations of this in
the wild yet, so its good enough for now.
There is more to be done here in terms of accepting RFC invalid
input that some mailers accept, but this covers the valid
RFC places where encoded words can occur in structured headers.
The problem was I was only checking for decimal digits after the third '?',
not for *hex* digits :(.
This changeset also fixes a couple of comment typos, deletes an unused
function relating to encoded word parsing, and removed an invalid
'if' test from the folding function that was revealed by the tests
written to validate this issue.
This code passes all the same tests that the existing RFC mime header
parser passes, plus a bunch of additional ones.
There are a couple of commented out tests where there are issues with the
folding. The folding doesn't normally get invoked for headers parsed from
source, and the cases are marginal anyway (headers with invalid binary data)
so I'm not worried about them, but will fix them after the beta.
There are things that can be done to make this API even more convenient, but I
think this is a solid foundation worth having. And the parser is a full RFC
parser, so it handles cases that the current parser doesn't. (There are also
probably cases where it fails when the current parser doesn't, but I haven't
found them yet ;)
Oh, yeah, and there are some really ugly bits in the parser for handling some
'postel' cases that are unfortunately common.
I hope/plan to to eventually refactor a lot of the code in the parser which
should reduce the line count...but there is no escaping the fact that the
error recovery is welter of special cases.
Although '<>' is invalid according to RFC 5322, SMTP uses it for various
things, and it sometimes ends up in email headers. This patch changes
get_angle_addr to recognize it and just register a Defect instead of raising a
parsing error.
When the new policies are used (and only when the new policies are explicitly
used) headers turn into objects that have attributes based on their parsed
values, and can be set using objects that encapsulate the values, as well as
set directly from unicode strings. The folding algorithm then takes care of
encoding unicode where needed, and folding according to the highest level
syntactic objects.
With this patch only date and time headers are parsed as anything other than
unstructured, but that is all the helper methods in the existing API handle.
I do plan to add more parsers, and complete the set specified in the RFC
before the package becomes stable.
Nikita Sobolev
Abhilash Raj
Claudiu Popa
Andrei Troie
Ashwin Ramaswami
Min ho Kim
jpic
Dong-hee Na
Tal Einat
jayyyin
R. David Murray
Joel Hillacre
Martin Panter
Ezio Melotti