Python socket 函数 getaddrinfo

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# -*- coding: cp936 -*-
socket.getaddrinfo(host,  port, family=0, socktype=0, proto=0, flags=0)
#根据给定的参数host/port，相应的转换成一个包含用于创建socket对象的五元组，
#参数host为域名，以字符串形式给出代表一个IPV4/IPV6地址或者None.
#参数port如果字符串形式就代表一个服务名，比如“http”"ftp""email"等，或者为数字，或者为None
#参数family为地主族，可以为AF_INET  ，AF_INET6 ，AF_UNIX.
#参数socketype可以为SOCK_STREAM(TCP)或者SOCK_DGRAM(UDP)
#参数proto通常为0可以直接忽略
#参数flags为AI_*的组合，比如AI_NUMERICHOST，它会影响函数的返回值
#附注：给参数host,port传递None时建立在C基础，通过传递NULL。
#该函数返回一个五元组(family, socktype, proto, canonname, sockaddr)，同时第五个参数sockaddr也是一个二元组(address, port)
# Echo server program
import socket
import sys
HOST = None               # Symbolic name meaning all available interfaces
PORT = 50007              # Arbitrary non-privileged port
s = None
for res in socket.getaddrinfo(HOST, PORT, socket.AF_UNSPEC,
socket.SOCK_STREAM, 0, socket.AI_PASSIVE):
af, socktype, proto, canonname, sa = res
try:
#根据getaddrinfo()的返回信息初始化socket
s = socket.socket(af, socktype, proto)
except socket.error, err_msg:
print err_msg #回显异常信息
s = None
continue
try:
#sa是(host,port)的二元组
s.bind(sa)
#监听客户端请求
s.listen(1)
except socket.error, err_msg:
print err_msg
s.close()
s = None
continue
break
if s is None:
print 'could not open socket'
sys.exit(1)
conn, addr = s.accept()
print 'Connected by', addr
while 1:
data = conn.recv(1024)# 2）接受数据
if not data: break
conn.send(data)# 3）并返回2中接受到得数据
conn.close()

# Echo client program
import socket
import sys
HOST = 'daring.cwi.nl'    # The remote host
PORT = 50007              # The same port as used by the server
s = None
for res in socket.getaddrinfo(HOST, PORT, socket.AF_UNSPEC, socket.SOCK_STREAM):
af, socktype, proto, canonname, sa = res
try:
s = socket.socket(af, socktype, proto)
except socket.error, msg:
s = None
continue
try:
s.connect(sa)
except socket.error, msg:
s.close()
s = None
continue
break
if s is None:
print 'could not open socket'
sys.exit(1)
s.sendall('Hello, world')# 1）发送数据
data = s.recv(1024)# 4）接受服务器回显的数据
s.close()
print 'Received', repr(data) #打印输出