Python websocket client close connection

Question

websocket_client.py

#!/usr/bin/env python

# WS client example

import asyncio
import websockets
import json
import sys
import os
import time

from aiortc import RTCPeerConnection, RTCSessionDescription

pcs = []
peer_connections = 0
local_username = "epalxeis"
websocket = None

async def open_websocket():
    global websocket
    uri = "ws://192.168.1.5:8080"
    async with websockets.connect(uri) as websocket:
        #send username
        await websocket.send(json.dumps({"type":"register","username":local_username}))
        async for message in websocket:
            message = json.loads(message)
            if(message["type"]=="create_peer"):
                await create_peer(message["username"],websocket)
            elif(message["type"]=="offer"):
                await receive_offer(message,websocket)
            elif(message["type"]=="answer"):
                receive_answer(message,websocket)
            elif(message["type"]=="unregister"):
                unregister(message,websocket)
        

                
                
async def create_peer(username,websocket):
    global pcs
    global peer_connections
    global local_username
    pc = RTCPeerConnection()
    pc_index = peer_connections
    pcs.append([username,pc])
    
    peer_connections = peer_connections+1
    
    '''
        add stream (video-audio to pc)
    '''
    
    @pc.on("track")
    def on_track(track):
        '''
            play track with PyQt5
        '''
        
    offer = await pcs[pc_index].createOffer()
    pcs[pc_index][1].setLocalDescription(offer)
    
    
    data = {"type":"offer","from":local_username,"to":username,"offer":offer}
    
    await websocket.send(json.dumps(data))
    
async def receive_offer(message,websocket):
    global pcs
    global peer_connections
    global local_username
    username = message["username"]
    offer = RTCSessionDescription(sdp=message["offer"]["sdp"], type=message["offer"]["type"])
    
    pc = RTCPeerConnection()
    pc_index = peer_connections
    pcs.append([username,pc])
    
    peer_connections = peer_connections+1
    
    '''
        add stream (video-audio to pc)
    '''
    
    @pc.on("track")
    def on_track(track):
        '''
            play track with PyQt5
        '''
    
    await pcs[pc_index][1].setRemoteDescription(offer)
    answer = await pcs[pc_index][1].createAnswer()
    await pcs[pc_index][1].setLocalDescription(answer)
    answer_json = {"sdp":answer.sdp,"type":"answer"}
    data = {"type":"answer","from":local_username,"to":username,"answer":answer_json}
    await websocket.send(json.dumps(data))
    
async def receive_answer(message,websocket):
    global pcs
    username = message["username"]
    answer = message["answer"]
    for pc in pcs:
        if(pc[0]==username):
            pc[1].setRemoteDescription(answer)
            
async def unregister(message,websocket):
    global pcs
    global peer_connections
    username = message["username"]
    index = 0
    counter = 0
    for pc in pcs:
        if(pc[0]==username):
            pc[1].close()
            '''
                PyQt5 manage for closing Output Device
            '''
            index = counter
            break
        counter = counter + 1
    del pcs[index]
    peer_connections = peer_connections-1
    
asyncio.get_event_loop().run_until_complete(open_websocket())

websocket_server.py

import asyncio
import websockets
import json
import ssl

peers = ()
    
async def on_open(websocket,path):
    async for message in websocket:
        message = json.loads(message)
        if(message["type"]=="register"):
            await register(websocket,message["username"])
        elif(message["type"]=="offer"):
            await send_offer(websocket,message)
        elif(message["type"]=="answer"):
            await send_answer(websocket,message)
        elif(message["type"]=="candidate"):
            await send_candidate(websocket,message)
    await unregister(websocket)
            
async def register(websocket,username):
    global peers
    print(username+" logged in.")
    peers = peers + ((websocket,username),)
    for peer in peers:
        if peer[0] is not websocket:
            await websocket.send(json.dumps({"type": "create_peer","username":peer[1]}))

async def send_offer(websocket,message):
    global peers
    offer_creator = message["from"]
    offer_receiver = message["to"]
    offer = message["offer"]
    print(offer_creator+" creates and sends offer to "+offer_receiver)
    for peer in peers:
        if(peer[1]==offer_receiver):
            await peer[0].send(json.dumps({"type": "offer","username":offer_creator,"offer":offer}))
            
async def send_answer(websocket,message):
    global peers
    answer_creator = message["from"]
    answer_receiver = message["to"]
    answer = message["answer"]
    print(answer_creator+" creates and sends answer to "+answer_receiver)
    for peer in peers:
        if(peer[1]==answer_receiver):
            await peer[0].send(json.dumps({"type": "answer","username":answer_creator,"answer":answer}))
            
async def send_candidate(websocket,message):
    global peers
    candidate_creator = message["from"]
    candidate_receiver = message["to"]
    candidate = message["candidate"]
    print(candidate_creator+" send candidate packet to "+candidate_receiver)
    for peer in peers:
        if(peer[1]==candidate_receiver):
            await peer[0].send(json.dumps({"type": "candidate","username":candidate_creator,"candidate":candidate}))
            
async def unregister(websocket):
    global peers
    for peer_1 in peers:
        if(peer_1[0]==websocket):
            username = peer_1[1]
            print(username+" logged out.")
            for peer_2 in peers:
                if(peer_2[0] is not websocket):
                    await peer_2[0].send(json.dumps({"type": "unregister","username":username}))
                    
    peers_list = list(peers)
    peers_list.remove((websocket,username))
    peers = tuple(peers_list)
        
        
ssl_context = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
ssl_context.load_cert_chain(r'C:\xampp\crt\localhost\server.crt',r'C:\xampp\crt\localhost\server.key')
ssl_context = None
start_server = websockets.serve(on_open, "192.168.1.5", 8080, ssl=ssl_context)
asyncio.get_event_loop().run_until_complete(start_server)
asyncio.get_event_loop().run_forever()

First i run the websocket_server.py (this code is handling the websocket requests)

Second i run the websocket_client.py

After that i saw in the first cmd: epalxeis logged in. So the connection is correct. But if i close the second cmd (with the x button or with the ctr-c), i saw this error in the server's cmd:

Error in connection handler
Traceback (most recent call last):
  File "C:\Users\Χρήστος\AppData\Local\Programs\Python\Python38\lib\asyncio\windows_events.py", line 453, in finish_recv
    return ov.getresult()
OSError: [WinError 64] Το καθορισμένο όνομα δικτύου δεν είναι πια διαθέσιμο

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\Users\Χρήστος\AppData\Local\Programs\Python\Python38\lib\site-packages\websockets\protocol.py", line 827, in transfer_data
    message = await self.read_message()
  File "C:\Users\Χρήστος\AppData\Local\Programs\Python\Python38\lib\site-packages\websockets\protocol.py", line 895, in read_message
    frame = await self.read_data_frame(max_size=self.max_size)
  File "C:\Users\Χρήστος\AppData\Local\Programs\Python\Python38\lib\site-packages\websockets\protocol.py", line 971, in read_data_frame
    frame = await self.read_frame(max_size)
  File "C:\Users\Χρήστος\AppData\Local\Programs\Python\Python38\lib\site-packages\websockets\protocol.py", line 1047, in read_frame
    frame = await Frame.read(
  File "C:\Users\Χρήστος\AppData\Local\Programs\Python\Python38\lib\site-packages\websockets\framing.py", line 105, in read
    data = await reader(2)
  File "C:\Users\Χρήστος\AppData\Local\Programs\Python\Python38\lib\asyncio\streams.py", line 723, in readexactly
    await self._wait_for_data('readexactly')
  File "C:\Users\Χρήστος\AppData\Local\Programs\Python\Python38\lib\asyncio\streams.py", line 517, in _wait_for_data
    await self._waiter
  File "C:\Users\Χρήστος\AppData\Local\Programs\Python\Python38\lib\asyncio\proactor_events.py", line 280, in _loop_reading
    data = fut.result()
  File "C:\Users\Χρήστος\AppData\Local\Programs\Python\Python38\lib\asyncio\windows_events.py", line 808, in _poll
    value = callback(transferred, key, ov)
  File "C:\Users\Χρήστος\AppData\Local\Programs\Python\Python38\lib\asyncio\windows_events.py", line 457, in finish_recv
    raise ConnectionResetError(*exc.args)
ConnectionResetError: [WinError 64] Το καθορισμένο όνομα δικτύου δεν είναι πια διαθέσιμο

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "C:\Users\Χρήστος\AppData\Local\Programs\Python\Python38\lib\site-packages\websockets\server.py", line 191, in handler
    await self.ws_handler(self, path)
  File "websocket_server.py", line 9, in on_open
    async for message in websocket:
  File "C:\Users\Χρήστος\AppData\Local\Programs\Python\Python38\lib\site-packages\websockets\protocol.py", line 439, in __aiter__
    yield await self.recv()
  File "C:\Users\Χρήστος\AppData\Local\Programs\Python\Python38\lib\site-packages\websockets\protocol.py", line 509, in recv
    await self.ensure_open()
  File "C:\Users\Χρήστος\AppData\Local\Programs\Python\Python38\lib\site-packages\websockets\protocol.py", line 803, in ensure_open
    raise self.connection_closed_exc()
websockets.exceptions.ConnectionClosedError: code = 1006 (connection closed abnormally [internal]), no reason

The proccess don't stop. How can i resolve the issue?

Thanks in advance,

Chris Pappas

Answer 1

This post helps you.

The reason program couldn't stop is that sub threads continue to run even if main thread catches an exception and stop. Note that asyncio is implemented by thread (I pursued codes). There are two kinds of thread in Python, normal thread and daemon thread. The former continues to run if parent thread dies, the latter stops. asyncio is implemented with the former, therefore such this problem happens.