echo_server.py

"""
    Echo Server
"""

import socket
import sys
import traceback


def server(log_buffer=sys.stderr):
    """
        Create Server socket
    """
    # Set an address for our server
    address = ('127.0.0.1', 10000)

    # Instantiate a TCP socket with IPv4 Addressing
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM, socket.IPPROTO_TCP)

    # Set up option on socket if server script fails because port is already used
    sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

    # Log that we are building a server
    print("making a server on {0}:{1}".format(*address), file=log_buffer)

    # Bind your new sock 'sock' to the address above and begin to listen
    # for incoming connections
    sock.bind(address)
    sock.listen(1)

    try:
        # the outer loop controls the creation of new connection sockets. The
        # server will handle each incoming connection one at a time.
        while True:
            print('waiting for a connection', file=log_buffer)

            # make a new socket when a client connects, call it 'conn',
            conn, addr = sock.accept()
            try:
                print('connection - {0}:{1}'.format(*addr), file=log_buffer)

                # the inner loop will receive messages sent by the client in
                # buffers.  When a complete message has been received, the
                # loop will exit
                while True:
                    # Receive 16 bytes of data from the client.
                    data = conn.recv(16)
                    print('received "{0}"'.format(data.decode('utf8')))

                    # Send the data you received back to the client
                    conn.sendall(data)
                    print('sent "{0}"'.format(data.decode('utf8')))

                    # Check to see whether you have received the end of the message.
                    if len(data) < 16:
                        break

            except Exception as e:
                traceback.print_exc()
                sys.exit(1)

            finally:
                # Close the socket
                conn.close()
                print(
                    'echo complete, client connection closed', file=log_buffer
                )

    except KeyboardInterrupt:
        # TODO: Use the python KeyboardInterrupt exception as a signal to
        #       close the server socket and exit from the server function.
        #       Replace the call to `pass` below, which is only there to
        #       prevent syntax problems
        print('quitting echo server', file=log_buffer)
        raise


if __name__ == '__main__':
    server()
    sys.exit(0)