objectGUID contains "5c" makes the filter parser fails to parse

[krizex]

ldap3 version: 2.9.1
Python: 3.8.10

When I trying to search with filter "(objectguid=db6ffb06-5c7e-432d-a899-7eda79866582)" I got the following error:

adagent.domains.connection Operation on LDAP connection[TMP-windows-i3i4uf5.ucc.local] failed Severity=ERROR	Traceback (most recent call last):	  File "/opt/ad-service/adagent/domains/connection.py", line 120, in get_connection	    yield conn	  File "/opt/ad-service/adagent/domains/connection.py", line 134, in get_tmp_connection	    yield c	  File "/opt/ad-service/adagent/ldap/cmd.py", line 160, in _get_connection	    yield conn	  File "/opt/ad-service/adagent/ldap/cmd.py", line 165, in search_objects    await run_in_default_executor(lambda: conn.search(args.search_base, args.s_filter, attributes=['distinguishedName']))	  File "/opt/ad-service/adagent/utils/executor.py", line 19, in run_in_default_executor	    return await run_in_executor(None, func, *args)	  File "/opt/ad-service/adagent/utils/executor.py", line 15, in run_in_executor	    return await loop.run_in_executor(executor, runner)	  File "/usr/lib/python3.8/concurrent/futures/thread.py", line 57, in run	    result = self.fn(*self.args, **self.kwargs)	  File "/opt/ad-service/adagent/ldap/cmd.py", line 165, in <lambda>	    await run_in_default_executor(lambda: conn.search(args.search_base, args.s_filter, attributes=['distinguishedName']))	  File "/usr/local/lib/python3.8/dist-packages/ldap3/core/connection.py", line 838, in search	    request = search_operation(search_base,	  File "/usr/local/lib/python3.8/dist-packages/ldap3/operation/search.py", line 371, in search_operation	    request['filter'] = compile_filter(parse_filter(search_filter, schema, auto_escape, auto_encode, validator, check_names).elements[0])  # parse the searchFilter string and compile it starting from the root node	  File "/usr/local/lib/python3.8/dist-packages/ldap3/operation/search.py", line 290, in compile_filter	    matching_filter['assertionValue'] = AssertionValue(prepare_filter_for_sending(filter_node.assertion['value']))  File "/usr/local/lib/python3.8/dist-packages/ldap3/protocol/convert.py", line 215, in prepare_filter_for_sending	    return bytes(ints)	ValueError: bytes must be in range(0, 256) TransactionId=cf2bcf8b-5683-40da-a68a-cbbea6680880

It should be a regression of #762

[krizex]

The fix (08ff836) mentioned in #894 looks incomplete. I think we also have to remove the check https://github.com/cannatag/ldap3/blob/master/ldap3/protocol/convert.py#L201
@cannatag any insights?

Update:
The fix (08ff836) mentioned in #894 could fix the issue in the mock server but will trigger the failure in #762 again.
The function check_backslash should be paired use with prepare_filter_for_sending. However, before the fix of 08ff836, only check_backslash is called in the mock server but not prepare_filter_for_sending.

The correct fix should be:
paired call check_backslash and prepare_filter_for_sending in the mock server.

[plettich]

We have the same issue when using a search filter like (objectGUID=\\26\\17\\2d\\b9\\ea\\5c\\42\\40\\aa\\c1\\ed\\d9\\49\\c1\\1a\\bc).

[marconfus]

I can confirm, that the bug was fixed in 2.8 and 2.8.1.
But it reappeared in 2.9 (and was there in 2.7)