Code needed to reproduce libssl bug on python3.6 on mac

libssl_bug.py

#!/usr/bin/env python3.6

"""
Code needed to reproduce a libssl segfault with python3.6 on mac.

To run:
    brew upgrade python3
    pip3 install websocket-client
    python3.6 libssl_bug.py

    > 'python3.6 libssl_bug.py' terminated by signal SIGSEGV (Address boundary error)

Full crash dump: https://gist.github.com/pirate/e1485110093d2d9fc49596e6ff481777
"""

import threading
from time import sleep
from websocket import create_connection     # pip install websocket-client

URL = 'wss://echo.websocket.org/'           # simple echo server, with SSL
SSL_OPTS = {'cert_reqs': 0}                 # the 0 is equivalent to ssl.CERT_NONE
NUM_THREADS = 4


class SocketThread(threading.Thread):
    keep_running = True

    def run(self):
        self.ws = create_connection(URL, sslopt=SSL_OPTS)
        self.ws.send('{"type": "Test Message"}')
        self.ws.recv()
        while self.keep_running:
            try:
                self.ws.send('{"type": "Test Message"}')
                self.ws.recv()
            except Exception:
                if self.keep_running:
                    raise


def single_thread_test():
    # works fine
    sock = create_connection('wss://localhost', sslopt=SSL_OPTS)
    sock.send('{"type": "Test Message"}')
    sock.recv()
    sleep(3)
    sock.close()


def multi_thread_test(close_after):
    # causes segfault when closing websockets, somewhere in a libssl destructor

    threads = []
    for _ in range(NUM_THREADS):
        t = SocketThread()
        t.start()
        threads.append(t)

    sleep(4)

    for t in threads:
        t.keep_running = False
        if close_after:
            t.ws.close()  # libssl segfaults on python3.6 when closing a wss:// connection with VERIFY_SSL=False
        t.join()


if __name__ == '__main__':
    # single_thread_test()                  # works fine
    # multi_thread_test(close_after=False)  # works fine
    multi_thread_test(close_after=True)   # 'python3.6 libssl_bug.py' terminated by signal SIGSEGV (Address boundary error)