【Socket編程】Python用udp實現簡易ping

用Python實現一個簡易的ping程序，客戶端發送一個簡易的ping報文，接收到該信息的服務器返回對應的pong報文，然後客戶端計算RTT。由於UDP不是可靠協議，需要爲該程序設置超時機制，超時1秒後將假設報文沒有收到，並打印出超時提示。

服務器實現如下：

import socket
import errno
import os

HOST, PORT = "", 8888

def serve_forever():
    listen_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    listen_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

    listen_socket.bind((HOST, PORT))
    print "Serving on port %s ..." % PORT

    while True:
        request, addr = listen_socket.recvfrom(2048)
        response = "Wrong CMD"
        if request == "Ping":					#保證是Ping指令，否則返回Wrong CMD
            response = "Pong"

        listen_socket.sendto(response, addr)


if __name__ == '__main__':
    serve_forever()

客戶端如下：

import socket
import datetime					#使用datetime計算時間差


SERVER_ADDRESS = 'localhost', 8888
REQUEST = "Ping"

def main():
    i = 10
    while i > 0:
        sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        sock.settimeout(1)
        try:
            begin_time = datetime.datetime.now()
            sock.sendto(REQUEST, (SERVER_ADDRESS))
            while True:
                data, addr = sock.recvfrom(2048)
                if data == "Pong":
                    end_time = datetime.datetime.now()
                    i = i - 1
                    break
                else:
                    print(data)
                    continue

        except socket.timeout:
            print "time out"
        else:
            msec = (end_time - begin_time).microseconds / 1000.0
            print "rtt: %f msec" % msec

if __name__ == '__main__':
    main()

這裏使用 settimeout() 設定超時時間，使用當 ping-pong 的過程超過1秒後會出現 socket.timeout 異常，此時會進入 socket.timeout 分支。