September Morn Update

Task/Echo-server/Python/echo-server-3.py

@@ -0,0 +1,64 @@
+    #!usr/bin/env python
+    import socket
+    import threading
+
+    HOST = 'localhost'
+    PORT = 12321
+    SOCKET_TIMEOUT = 30
+
+    # This function handles reading data sent by a client, echoing it back
+    # and closing the connection in case of timeout (30s) or "quit" command
+    # This function is meant to be started in a separate thread
+    # (one thread per client)
+    def handle_echo(client_connection, client_address):
+        client_connection.settimeout(SOCKET_TIMEOUT)
+        try:
+            while True:
+                data = client_connection.recv(1024)
+                # Close connection if "quit" received from client
+                if data == b'quit\r\n' or data == b'quit\n':
+                    print('{} disconnected'.format(client_address))
+                    client_connection.shutdown(1)
+                    client_connection.close()
+                    break
+                # Echo back to client
+                elif data:
+                    print('FROM {} : {}'.format(client_address,data))
+                    client_connection.send(data)
+        # Timeout and close connection after 30s of inactivity
+        except socket.timeout:
+            print('{} timed out'.format(client_address))
+            client_connection.shutdown(1)
+            client_connection.close()
+
+    # This function opens a socket and listens on specified port. As soon as a
+    # connection is received, it is transfered to another socket so that the main
+    # socket is not blocked and can accept new clients.
+    def listen(host, port):
+        # Create the main socket (IPv4, TCP)
+        connection = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        connection.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+        connection.bind((host, port))
+        # Listen for clients (max 10 clients in waiting)
+        connection.listen(10)
+        # Every time a client connects, allow a dedicated socket and a dedicated
+        # thread to handle communication with that client without blocking others.
+        # Once the new thread has taken over, wait for the next client.
+        while True:
+            current_connection, client_address = connection.accept()
+            print('{} connected'.format(client_address))
+            handler_thread = threading.Thread( \
+                target = handle_echo, \
+                args = (current_connection,client_address) \
+            )
+            # daemon makes sure all threads are killed if the main server process
+            # gets killed
+            handler_thread.daemon = True
+            handler_thread.start()
+
+    if __name__ == "__main__":
+        try:
+            listen(HOST, PORT)
+        except KeyboardInterrupt:
+            print('exiting')
+            pass