MS-NEGOEX Phase 3 Implementation

[ThatTotallyRealMyth]

Hey Hey, opening this PR to begin tracking work on the phase 3 of the ms-negoex implementation. So far the helper functions have been implemented, the proposed testcases from PR1/2 have been integrated and they all pass:

┌──(kali㉿kali)-[~/personalprojects/impacket-contributions]
└─$ python3 test_spnego_negoex.py -v   
test_malformed_negoex_payload_raises_clear_error_when_selected (__main__.SPNEGONegoExTests.test_malformed_negoex_payload_raises_clear_error_when_selected) ... ok
test_neg_token_init_detects_negoex_offered (__main__.SPNEGONegoExTests.test_neg_token_init_detects_negoex_offered) ... ok
test_neg_token_init_does_not_parse_ntlm_as_negoex (__main__.SPNEGONegoExTests.test_neg_token_init_does_not_parse_ntlm_as_negoex) ... ok
test_neg_token_init_parses_negoex_mech_token_messages (__main__.SPNEGONegoExTests.test_neg_token_init_parses_negoex_mech_token_messages) ... ok
test_neg_token_resp_detects_negoex_selected (__main__.SPNEGONegoExTests.test_neg_token_resp_detects_negoex_selected) ... ok
test_neg_token_resp_does_not_parse_ntlm_response_as_negoex (__main__.SPNEGONegoExTests.test_neg_token_resp_does_not_parse_ntlm_response_as_negoex) ... ok
test_neg_token_resp_parses_negoex_response_token_messages (__main__.SPNEGONegoExTests.test_neg_token_resp_parses_negoex_response_token_messages) ... ok

----------------------------------------------------------------------
Ran 7 tests in 0.002s

OK
                                                                                                                                                  

I wasnt sure how to handle as I noticed in the provided test cases you have a function called getNegoExMessages() but you didnt mention it in #2195 so I assumed that since you gave it to me in a proposed testcase that you wanted it. Happy to remove it as well if it was not intended

[ThatTotallyRealMyth]

Hey @anadrianmanrique you mentioned smb and ldap for updating to handle NEGOEX but you never mentioned DCERPC. Should I add the same the same thing in kerberosv5.py, here

################################################################################
# DCE RPC Helpers
################################################################################
def getKerberosType3(cipher, sessionKey, auth_data):
    negTokenResp = SPNEGO_NegTokenResp(auth_data)

Or should I leave that out?