python - Python 中的 UDP 客户端/服务器套接字

Question

我是 python 和套接字的新手，正在尝试编写一个回显客户端/服务器套接字。我已经编写了服务器，以便丢失 30% 的数据包。我将我的客户端编程为在一秒后超时，因为数据包可能会丢失。但是，每当我运行我的客户端套接字时，我的输出都是 100% REQUEST TIMED OUT。我假设我得到这个输出是因为我的服务器从未收到消息。我已经多次查看我的代码，但无法弄清楚为什么我会不断收到此输出。下面是我的服务器和客户端套接字代码。任何帮助，将不胜感激。

服务器套接字:

 # We will need the following module to generate randomized lost packets
    import random
    from socket import *

    # Create a UDP socket
    # Notice the use of SOCK_DGRAM for UDP packets
    serverSocket = socket(AF_INET, SOCK_DGRAM)

    # Assign IP address and port number to socket
    serverSocket.bind(('', 12000))

    while True:
        # Generate random number in the range of 0 to 10
        rand = random.randint(0, 10)

        # Receive the client packet along with the address it is coming from
        message, address = serverSocket.recvfrom(1024)

        # Capitalize the message from the client
        message = message.upper()

        # If rand is less is than 4, we consider the packet lost and do notrespond
        if rand < 4:
            continue

        # Otherwise, the server responds
        serverSocket.sendto(message, address) 

客户端套接字:

import time
from socket import *

pings = 1

#Send ping 10 times 
while pings < 11:  

    #Create a UDP socket
    clientSocket = socket(AF_INET, SOCK_DGRAM)

    #Set a timeout value of 1 second
    clientSocket.settimeout(1)

    #Ping to server
    message = 'test'

    addr = ("127.0.0.1", 12000)

    #Send ping
    start = time.time()
    clientSocket.sendto(message, addr)

    #If data is received back from server, print 
    try:
        data, server = clientSocket.recvfrom(1024)
        end = time.time()
        elapsed = end - start
        print data + " " + pings + " "+ elapsed        

    #If data is not received back from server, print it has timed out  
    except timeout:
        print 'REQUEST TIMED OUT'

    pings = pings - 1

Answer 1

我测试了您的代码，它在我的机器上按预期工作。您的问题可能不是您的代码。它可能是防火墙或其他阻止环回接口(interface) (127.0.0.1) 上所有数据包的东西。根据您的操作系统，尝试使用 Wireshark 等数据包监视器进行测试。

此外，这里有一些关于如何改进代码以使其更符合 Pythonic 的建议:

服务器

import random
import socket

server_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
server_socket.bind(('', 12000))

while True:
    rand = random.randint(0, 10)
    message, address = server_socket.recvfrom(1024)
    message = message.upper()
    if rand >= 4:
        server_socket.sendto(message, address)

客户端

import time
import socket

for pings in range(10):
    client_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    client_socket.settimeout(1.0)
    message = b'test'
    addr = ("127.0.0.1", 12000)

    start = time.time()
    client_socket.sendto(message, addr)
    try:
        data, server = client_socket.recvfrom(1024)
        end = time.time()
        elapsed = end - start
        print(f'{data} {pings} {elapsed}')
    except socket.timeout:
        print('REQUEST TIMED OUT')