I have a C++ app, that embeds a Python script.
The C++ app sends cv::Mat images to the Py script, that in turn runs some image recognition (via a CNN). Basic idea can be found in my gist.

Then my Python script wants to send the results of the CNN-prediction to another app (in Unity I believe) via secure WebSockets with SSL.

I don't have access to the actual Unity app at the moment, so I have to test the actual "sending" part using a simple Python server-app.

I don't have much experience (or knowledge) with sockets and SSL in Python, so I'm hoping for some help.

Everything works if I just use a non-secure HTTP connection, but when I try to introduce HTTPS and SSL, I get problems.

SERVER SIDE:

In the last attempt, I was using the following server script (taken from here):

import asyncio

import pathlib

import ssl

import websockets



async def hello(websocket, path):

    name = await websocket.recv()

    print(f"< {name}")



    ssl_context = ssl.SSLContext(ssl.PROTOCOL_TLSv1)

    ssl_context.load_cert_chain(

        pathlib.Path(__file__).with_name('cert.pem'), 

        pathlib.Path(__file__).with_name('key_wopasswd.pem'))



start_server = websockets.serve(hello, 'localhost', 443, ssl=ssl_context)



asyncio.get_event_loop().run_until_complete(start_server)

asyncio.get_event_loop().run_forever()

The certificate and key files were given to me by a colleague, who's in charge of the actual receiving Unity app.

CLIENT SIDE:

After that I tried to connect and send messages either like this (fragment 1):

import json

import http.client, ssl

import time



ws = None

def send(msg="lol"):

    global ws

    if ws is None:

        ssl_context = ssl.SSLContext(ssl.PROTOCOL_TLSv1)

        ssl_context.load_cert_chain('cert.pem', 'key_wopasswd.pem')

        ws = http.client.HTTPSConnection("localhost", 443, context=ssl_context)

        ws.connect()

        print("connected successfully!")

    else:

        jsonString = json.dumps({"Time":int(time.time()), "Message":msg})

        ws.send(jsonString.encode('utf-8'))  

In which case, simply nothing happens.

Or like this (fragment 2):

import websocket, ssl

import time



ws = None

def send(msg="lol"):

    global ws

    if ws is None: 

        ws = websocket.WebSocket(sslopt={"cert_reqs": ssl.CERT_REQUIRED,

                                         "ssl_version": ssl.PROTOCOL_TLSv1, 

                                         "certfile": "cert.pem", 

                                         "keyfile": "key_wopasswd.pem"})

        ws.connect("wss://localhost:443")        

    else:

        jsonString = json.dumps({"Time":int(time.time()), "Message":msg})        

        ws.send(jsonString.encode('utf-8'))  

In which case, I get the following error:

Traceback (most recent call last):

  File ".client2.py", line 21, in send

    ws.connect("wss://localhost:443")

  File "C:Program FilesPython36libsite-packageswebsocket_core.py", line 220, in connect

    options.pop('socket', None))

  File "C:Program FilesPython36libsite-packageswebsocket_http.py", line 126, in connect

    sock = _ssl_socket(sock, options.sslopt, hostname)

  File "C:Program FilesPython36libsite-packageswebsocket_http.py", line 253, in _ssl_socket

    sock = _wrap_sni_socket(sock, sslopt, hostname, check_hostname)

  File "C:Program FilesPython36libsite-packageswebsocket_http.py", line 232, in _wrap_sni_socket

    server_hostname=hostname,

  File "C:Program FilesPython36libssl.py", line 401, in wrap_socket

    _context=self, _session=session)

  File "C:Program FilesPython36libssl.py", line 808, in __init__

    self.do_handshake()

  File "C:Program FilesPython36libssl.py", line 1061, in do_handshake

    self._sslobj.do_handshake()

  File "C:Program FilesPython36libssl.py", line 683, in do_handshake

    self._sslobj.do_handshake()

ssl.SSLError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:749)

I also tried a simple http.server.HTTPServer, but the only difference was that with the first client (Fragment 1), it did not print the messages after every send, but instead accumulated all the received messages and printed all of them together after I stop the client, with the error: code 400, message Bad request syntax.

tl;dr
Basically, what I need, is a good example of how I can connect to a secure HTTPS server with SSL once, and then continue sending string-messages, until the app stops.

A small update:

It works, if I write the client like this, but only if I close and reopen the connection after every message:

import json

import websocket, ssl

import time



ws = None

def send(msg="..."):

    global ws

    if ws is None:

        ws = websocket.WebSocket(sslopt={"cert_reqs": ssl.CERT_NONE,

                                         "ssl_version": ssl.PROTOCOL_TLSv1, 

                                         "certfile": "cert.pem", 

                                         "keyfile": "key_wopasswd.pem"})

        ws.connect("wss://localhost:443")



    jsonString = json.dumps({"Time":int(time.time()), "Message":msg})

    ws.send(jsonString.encode('utf-8'))         

    ws.close()       

    ws = None 



########################

i = 0

while i < 10:

    i = i + 1

    send("i = %d" % i)