can't close socket on KeyboardInterrupt

1. To break to get out the while loop. Without break, the loop will not end.
2. To be safe, check whether connection is set.

---

from socket import socket, AF_INET, SOCK_STREAM

sock = socket(AF_INET, SOCK_STREAM)
sock.bind(("localhost", 7777))
sock.listen(1)
while True:
    connection = None # <---
    try:
        connection, address = sock.accept()
        print("connected from ", address)
        received_message = connection.recv(300)
        if not received_message:
            break
        connection.sendall(b"hello")
    except KeyboardInterrupt:
        if connection:  # <---
            connection.close()
        break  # <---

UPDATE

• There was a typo: KeyBoardInterrupt should be KeyboardInterrupt.
• sock.recv should be connection.recv.

Try adding a timeout to the socket, like so:

from socket import socket, AF_INET, SOCK_STREAM
sock = socket(AF_INET, SOCK_STREAM)
sock.bind(("localhost", 7777))
sock.settimeout(1.0)
sock.listen(1)
while True:
    try:
        connection, address = sock.accept()
        print("connected from " + address)
        received_message = sock.recv(300)
        if not received_message:
            break
        connection.sendall(b"hello")
    except IOError as msg:
        print(msg)
        continue    
    except KeyboardInterrupt:
        try:
            if connection:
                connection.close()
        except: pass
        break
sock.shutdown
sock.close()

I had this issue on Windows. Here's how I handle stopping the process:

    try:
        while self.running:
            try:
                c, addr = self.socket.accept()
                print("Connection accepted from " + repr(addr[1]))
                # do special stuff here...
                print("sending...")
                continue
            except (SystemExit, KeyboardInterrupt):
                print("Exiting....")
                service.stop_service()
                break
            except Exception as ex:
                print("======> Fatal Error....\n" + str(ex))
                print(traceback.format_exc())
                self.running = False
                service.stop_service()
                raise
    except (SystemExit, KeyboardInterrupt):
        print("Force Exiting....")
        service.stop_service()
        raise

def stop_service(self):
    """
    properly kills the process: https://stackoverflow.com/a/16736227/4225229
    """
    self.running = False
    socket.socket(socket.AF_INET,
                  socket.SOCK_STREAM).connect((self.hostname, self.port))
    self.socket.close()

Note that in order to trigger a KeyboardInterrupt exception, use:

Ctrl+Fn+PageUp(Pause/Break)