Error in do_handshake()

[LeviPesin]

Please look into fortra/impacket#866 and fortra/impacket#856. I think that problem is not in impacket, but in pyOpenSSL.

[LeviPesin]

For example, if you run following code (require installed impacket) you get [('SSL routines', 'state_machine', 'internal error')]:
import impacket.tds
from OpenSSL import SSL
ms_sql = impacket.tds.MSSQL('10.10.10.27', 1433)
ms_sql.connect()
ms_sql.preLogin()
ctx = SSL.Context(SSL.TLSv1_METHOD)
ctx.set_cipher_list('RC4, AES256') (you get warning here)
tls = SSL.Connection(ctx, None)
tls.set_connect_state()
tls.do_handshake() (here you get error)

[LeviPesin]

Actually, it is not working even without impacket and without warning :-) For example, this code does not work:
from OpenSSL import SSL
ctx = SSL.Context(SSL.TLSv1_METHOD)
ctx.set_cipher_list('RC4, AES256'.encode())
tls = SSL.Connection(ctx, None)
tls.set_connect_state()
tls.do_handshake()

[qbit]

I can hit a similar issue with this:

import socket
import OpenSSL
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.settimeout(100)
ctx = OpenSSL.SSL.Context( OpenSSL.SSL.TLSv1_2_METHOD)

def print_chain(context, hostname, port):
    print('Connecting to {0}'.format(hostname))
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock = OpenSSL.SSL.Connection(context=context, socket=sock)
    sock.settimeout(5)
    sock.connect((hostname, port))
    sock.setblocking(1)
    sock.do_handshake()
    for cert in sock.get_peer_cert_chain():
        print('   s:{0}'.format(cert.get_subject()))
        print('   i:{0}'.format(cert.get_issuer()))
    sock.shutdown()
    sock.close()

Servers that are checking ServerName error while servers that don't work fine. For example, things that use Go's autocert will fail with the above script. (thanks to @jrick for tracking that bit down!)

[qbit]

I have confirmed this happens on:

OS	Library
OpenBSD-current	LibreSSL 3.2.1
macOS 11.0 Big Sur	LibreSSL 2.8.3
NixOS 20.3.2625	OpenSSL 1.1.1g 21 Apr 2020

[LeviPesin]

In my example issue happens on last Ubuntu, OpenSSL 1.1.1g 21 Apr 2020, and Python 3.8 (on Python 3.7 there is no issue).

[qbit]

Turns out my issue looked very much like this one, and my test script was not quite exercising the full issue.

Currently on LibreSSL (on OpenBSD-current as of 2020-07-01ish) TLS 1.3 does not support the info callback. This caused the same result as seen in the script I posted earlier. In the example script if one sets sock.set_tlsext_host_name(hostname.encode()) it will work as expected.

I was mistaken in my assumption that sock.set_tlsext_host_name(hostname.encode()) should happen by default.

[alex]

I'm sorry we've been slow to triage this. Can someone please provide a complete and self-contained example for reproducing this?