一、环境

    windows10 + python3.6

二、code

#!/usr/bin/env python3# coding=utf-8import argparse, random, socket, sysMAX_BYTES = 65535def server(interface, port):    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)    sock.bind((interface, port))    print('Listening at', sock.getsockname())    while True:        data, address = sock.recvfrom(MAX_BYTES)        if random.random() < 0.5:            print('Pretending to drop packet from {}'.format(address))            continue        text = data.decode('ascii')        print('The client at {} says {!r}'.format(address, text))        message = 'You data was {} bytes long'.format(len(data))        sock.sendto(message.encode('ascii'), address)def client(hostname, port):    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)    hostname = sys.argv[2]    sock.connect((hostname, port))    print('Client socket name is {}'.format(sock.getsockname()))    delay = 0.1  # seconds    text = 'This is another message'    data = text.encode('ascii')    while True:        sock.send(data)        print('Waiting up to {} seconds for a reply'.format(delay))        sock.settimeout(delay)        try:            data = sock.recv(MAX_BYTES)     # recv() is block        except socket.timeout:            '''exponential backoff(指数退避)'''            delay *= 2  # wait even longer for the next request            if delay > 2.0:                raise RuntimeError('I think the server is down')        else:            break   # we are done, and can stop looping    print('The server says {!r}'.format(data.decode('ascii')))if __name__ == '__main__':    choices = {'client': client, 'server': server}    parser = argparse.ArgumentParser(description='Send and receive UDP,'                                     'pretending packets are often dropped')    parser.add_argument('role', choices=choices, help='Which role to take')    parser.add_argument('host', help='interface the server listens at;'                        'host the client sends to')    parser.add_argument('-p', metavar='PORT', type=int, default=1060,                        help="UDP port (default 1060)")    args = parser.parse_args()    function = choices[args.role]    function(args.host, args.p)

udp广播

#!/usr/bin/env python3# coding=utf-8import argparse, socketBUFSIZE = 65535def server(interface, port):    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)    sock.bind((interface, port))    print('Listening for datagrams at {}'.format(sock.getsockname()))    while True:        data, address = sock.recvfrom(BUFSIZE)        text = data.decode('ascii')        print('The client at {} says: {!r}'.format(address, text))def client(network, port):    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)    sock.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)    text = 'Broadcast datagram!'    sock.sendto(text.encode('ascii'), (network, port))if __name__ == '__main__':    choices = {'client': client, 'server': server}    parser = argparse.ArgumentParser(description='Send,receive UDP broadcast')    parser.add_argument('role', choices=choices, help='wich role to take')    parser.add_argument('host', help='interface the server listens at;'                                     'network the client sends to')    parser.add_argument('-p', metavar='port', type=int, default=1060,                        help='UDP port (default 1060)')    args = parser.parse_args()    function = choices[args.role]    function(args.host, args.p)