Server now closes all client connections after keyboard interrupt

server.py

 import socket
 import logging
 from traceback import format_exc
+from threading import Thread
 
 from websocket import WebSocket
 from exceptions import InvalidRequest
+from frame import CLOSE_NORMAL
 
 
 class Server(object):
@@ -26,10 +28,14 @@ class Server(object):
             try:
                 sock, address = self.sock.accept()
                 client = Client(self, sock, address)
-                client.handshake()
+
+                client.server_handshake()
                 self.clients.append(client)
                 logging.info('Registered client %s', client)
-                client.run_threaded()
+
+                thread = Thread(target=client.receive_forever)
+                thread.daemon = True
+                thread.start()
             except InvalidRequest as e:
                 logging.error('Invalid request: %s', e.message)
             except KeyboardInterrupt:
@@ -38,6 +44,12 @@ class Server(object):
             except Exception as e:
                 logging.error(format_exc(e))
 
+        self.quit_gracefully()
+
+    def quit_gracefully(self):
+        for client in self.clients:
+            client.close(CLOSE_NORMAL)
+
     def remove_client(self, client, code, reason):
         self.clients.remove(client)
         self.onclose(client, code, reason)
@@ -71,6 +83,7 @@ class Client(WebSocket):
         super(Client, self).__init__(sock)
         self.server = server
         self.address = address
+        self.send_lock = Lock()
 
     def onopen(self):
         self.server.onopen(self)

websocket.py

 import re
 import struct
 from hashlib import sha1
-from threading import Thread
 
 from frame import ControlFrame, receive_fragments, receive_frame, \
         OPCODE_CLOSE, OPCODE_PING, OPCODE_PONG
@@ -65,10 +64,10 @@ class WebSocket(object):
         payload = ''.join([f.payload for f in frames])
         return create_message(frames[0].opcode, payload)
 
-    def handshake(self):
+    def server_handshake(self):
         """
-        Execute a handshake with the other end point of the socket. If the HTTP
-        request headers read from the socket are invalid, an InvalidRequest
+        Execute a handshake as the server end point of the socket. If the HTTP
+        request headers sent by the client are invalid, an InvalidRequest
         exception is raised.
         """
         raw_headers = self.sock.recv(512).decode('utf-8', 'ignore')
@@ -141,15 +140,6 @@ class WebSocket(object):
             except Exception as e:
                 self.onexception(e)
 
-    def run_threaded(self, daemon=True):
-        """
-        Spawn a new thread that receives messages in an endless loop.
-        """
-        thread = Thread(target=self.receive_forever)
-        thread.daemon = daemon
-        thread.start()
-        return thread
-
     def send_close(self, code, reason):
         """
         Send a close control frame.
@@ -193,7 +183,7 @@ class WebSocket(object):
         self.sock.close()
 
         if frame.opcode != OPCODE_CLOSE:
-            raise ValueError('Expected close frame, got %s instead' % frame)
+            raise ValueError('expected close frame, got %s instead' % frame)
 
     def onopen(self):
         """