套接字编程作业2：UDPping程序

from socket import *
import time

serverName = '191.101.232.165' # 服务器地址，本例中使用一台远程主机
serverPort = 12000 # 服务器指定的端口
clientSocket = socket(AF_INET, SOCK_DGRAM) # 创建UDP套接字，使用IPv4协议
clientSocket.settimeout(1) # 设置套接字超时值1秒

for i in range(0, 10):
	sendTime = time.time()
	message = ('Ping %d %s' % (i+1, sendTime)).encode() # 生成数据报，编码为bytes以便发送
	try:
		clientSocket.sendto(message, (serverName, serverPort)) # 将信息发送到服务器
		modifiedMessage, serverAddress = clientSocket.recvfrom(1024) # 从服务器接收信息，同时也能得到服务器地址
		rtt = time.time() - sendTime # 计算往返时间
		print('Sequence %d: Reply from %s    RTT = %.3fs' % (i+1, serverName, rtt)) # 显示信息
	except Exception as e:
		print('Sequence %d: Request timed out' % (i+1))
		
clientSocket.close() # 关闭套接字

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

# 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 not respond
	if rand < 4:
		continue
	# Otherwise, the server responds
	serverSocket.sendto(message, address)