晚上跟着书上教程写了一些 socket 收发的代码，记下来当作备忘吧：

原生 socket 的 TCP 收发：

#!/usr/bin/env python

from socket import *
from time import ctime

HOST = ''
PORT = 21567
BUFSIZ = 1024
ADDR = (HOST, PORT)

tcpSerSock = socket(AF_INET, SOCK_STREAM)
tcpSerSock.bind(ADDR)
tcpSerSock.listen(5)

while True:
    print 'waiting for connection...'
    tcpCliSock, addr = tcpSerSock.accept()
    print '...connected from: ', addr

    while True:
        data = tcpCliSock.recv(BUFSIZ)
        if not data:
            break
        print 'received: ' + data
        tcpCliSock.send('[%s] %s ' % (ctime(), data))
    tcpCliSock.close()
tcpSerSock.close()

其他都好懂，解释一下 13 行，文档是这么说的：

listen(backlog)

Enable a server to accept connections. The backlog argument must be at least 0 (if it is lower, it is set to 0); it specifies the number of unaccepted connections that the system will allow before refusing new connections.

也就是缓冲区大小，能暂存的连接数的意思了。

还有 17 行，返回了一个元组，文档的解释：

accept() -> (socket object, address info)

Wait for an incoming connection. Return a new socket representing the connection, and the address of the client. For IP sockets, the address info is a pair (hostaddr, port).

下面是客户端的代码：

#!/usr/bin/env python

from socket import *

HOST = 'localhost'
PORT = 21567
BUFSIZ = 1024
ADDR = (HOST, PORT)

tcpCliSock = socket(AF_INET, SOCK_STREAM)
tcpCliSock.connect(ADDR)

while True:
    data = raw_input('> ')
    if not data:
        break
    tcpCliSock.send(data)
    data = tcpCliSock.recv(BUFSIZ)
    if not data:
        break
    print data
tcpCliSock.close()

原生 socket 的 UDP 收发

#!/usr/bin/env python

from socket import *
from time import ctime

HOST = ''
PORT = 21567
BUFSIZ = 1024
ADDR = (HOST, PORT)

udpSerSock = socket(AF_INET, SOCK_DGRAM)
udpSerSock.bind(ADDR)

while True:
    print 'waiting for message...'
    data, addr = udpSerSock.recvfrom(BUFSIZ)
    udpSerSock.sendto('[%s] %s' % (ctime(), data), addr)
    print '...received from and returned to:', addr

udpSerSock.close()

#!/usr/bin/env python

from socket import *

HOST = 'localhost'
PORT = 21567
BUFSIZ = 1024
ADDR = (HOST, PORT)

udpCliSock = socket(AF_INET, SOCK_DGRAM)

while True:
    data = raw_input('> ')
    if not data:
        break
    udpCliSock.sendto(data, ADDR)
    data, ADDR = udpCliSock.recvfrom(BUFSIZ)
    if not data:
        break
    print data

udpCliSock.close()