1 import argparse,socket
2 from datetime import datetime
3
4 MAX_BYTES = 65535
5
6 def server(port):
7 sock = socket.socket(socket.AF_INET,socket.SOCK_DGRAM) #协议族AF_INET以及数据报类型SOCK_DGRAM.SOCK_DGRAM表示在IP网络上使用UDP协议
8 #要注意的是数据报datagram而不是数据包packet,用了表示应用层数据块传输的官方术语
9 sock.bind(('127.0.0.1',port)) #绑定一个UDP网络地址:一个二元组,包含一个IP地址和一个整形的UDP端口号
10 #端口号要大于1023,否则要管理员权限
11 print('Listening at {}'.format(sock.getsockname())) #查询套接字当前绑定的IP地址和端口号
12 while True: #会进入一个循环不断运行recvfromO
13 data,adress = sock.recvfrom(MAX_BYTES) #最长可接收65535字节的信息,也是UDP数据报可包含的最大长度,没有接收到永远等待
14 #一旦接收到数据报,返回两个值。1 发送该数据报的客户端地址 2 以字节表示数据报的内容
15 text = data.decode('ascii')
16 print('The client at {} says {!r}'.format(adress,text))
17 text = 'Your data was {} bytes long'.format(len(data))
18 data = text.encode('ascii')
19 sock.sendto(data,adress)
20
21 def client(port):
22 sock = socket.socket(socket.AF_INET,socket.SOCK_DGRAM)
23 text = 'The time is {}'.format(datetime.now())
24 data = text.encode('ascii')
25 sock.sendto(data,('127.0.0.1',port)) #两个信息:要发送的信息和目标地址。这是向服务器发送数据报的唯一调用
26 print('The OS assigned me the adress {}'.format(sock.getsockname()))
27 data,adress = sock.recvfrom(MAX_BYTES)
28 text = data.decode('asicc')
29 print('The serve {} replied {!r}'.format(adress,text))
30 if __name__ == '__main__':
31 choices = {'client':client,'server':server}
32 parser = argparse.ArgmentParser(description='Send and receive UDP locally')
33 parser.add_argument('role',choices = choices ,help = 'which role to play')
34 parser.add_argument('-p',metavar = 'PORT',type = int ,default = 1060,
35 help = 'UDP port (default 1060)')
36 args = parser.parse_args()
37 function = choices[args.role]
38 function(args.p)