How to set timeout for do_handshake()?

Hello, I met a weird connection problem.

TCP connection is ok to establish with my target IP. However, it hangs for a long time at do_handshake().

Here is my code. conn.settimeout(3) and conn.setblocking(True) is used for TCP connection timeout.

import socket
from OpenSSL import crypto, SSL

ssl_context = SSL.Context(method=SSL.SSLv23_METHOD)
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
conn = SSL.Connection(ssl_context, sock)
conn.settimeout(3)
conn.connect(("some_ip", 443))
print('> connected')
conn.setblocking(True)
print('> set to blocking')
conn.do_handshake()
print('> done handshake')

Sometimes it just resets when calls do_handshake(). This is good, which I can ignore it and continue to proceed other targets.

$ python xxx.py
> connected
> set to blocking
Traceback (most recent call last):
  File "xxx.py", line 15, in <module>
    conn.do_handshake()
  File "/usr/local/lib/python3.7/site-packages/OpenSSL/SSL.py", line 1934, in do_handshake
    self._raise_ssl_error(self._ssl, result)
  File "/usr/local/lib/python3.7/site-packages/OpenSSL/SSL.py", line 1663, in _raise_ssl_error
    raise SysCallError(errno, errorcode.get(errno))
OpenSSL.SSL.SysCallError: (104, 'ECONNRESET')

It hangs! This is the worst situation. I have to interrupt it.

$ python xxx.py
> connected
> set to blocking
^CTraceback (most recent call last):
  File "xxx.py", line 15, in <module>
    conn.do_handshake()
  File "/usr/local/lib/python3.7/site-packages/OpenSSL/SSL.py", line 1933, in do_handshake
    result = _lib.SSL_do_handshake(self._ssl)
KeyboardInterrupt

I did a test. do_handshake() raises exception after 300 seconds. It surprises me that it's not due to timeout.

$ time python xxx.py
> connected
> set to blocking
Traceback (most recent call last):
  File "xxx.py", line 15, in <module>
    conn.do_handshake()
  File "/usr/local/lib/python3.7/site-packages/OpenSSL/SSL.py", line 1934, in do_handshake
    self._raise_ssl_error(self._ssl, result)
  File "/usr/local/lib/python3.7/site-packages/OpenSSL/SSL.py", line 1663, in _raise_ssl_error
    raise SysCallError(errno, errorcode.get(errno))
OpenSSL.SSL.SysCallError: (104, 'ECONNRESET')

real	5m3.233s
user	0m0.355s
sys	0m0.028s

300 seconds is not acceptable. There are thousands of targets to scan. I cannot wait for N*300 seconds, although it's a small portion.

python:3.7.9-slim
PyOpenSSL==19.1.0

How can it make do_handshake() succeed or fail within a small amount of time?

Thanks.

Start by reproducing the reported behavior with the Python script using PyOpenSSL 19.1.0 and inspect the call to conn.do_handshake(). The issue names no source file, test, or concrete change, so the expected timeout and a suitable implementation location would need to be established before work can be considered done.