【转】python中getaddrinfo详解

1. getaddrinfo简介

getaddrinfo可解析得到IPv6地址，而gethostbyname仅能得到IPv4地址。getaddrinfo在Python的socket包中，以下为python官网对getaddrinfo的解释：

转自：http://docs.python.org/2/library/socket.html

socket.getaddrinfo(host, port[, family[, socktype[, proto[, flags]]]])

Translate the host/port argument into a sequence of 5-tuples that contain all the necessary arguments for creating a socket connected to that service. host is a domain name, a string representation of an IPv4/v6 address or None. port is a string service name such as 'http', a numeric port number or None. By passing None as the value of host and port, you can pass NULL to the underlying C API.

The family, socktype and proto arguments can be optionally specified in order to narrow the list of addresses returned. By default, their value is 0, meaning that the full range of results is selected. The flags argument can be one or several of the AI_* constants, and will influence how results are computed and returned. Its default value is 0. For example, AI_NUMERICHOST will disable domain name resolution and will raise an error if host is a domain name.

The function returns a list of 5-tuples with the following structure:

(family, socktype, proto, canonname, sockaddr)

In these tuples, family, socktype, proto are all integers and are meant to be passed to the socket() function. canonname will be a string representing the canonical name of the host if AI_CANONNAME is part of the flags argument; else canonname will be empty. sockaddr is a tuple describing a socket address, whose format depends on the returned family (a (address, port) 2-tuple for AF_INET, a (address, port, flow info, scope id) 4-tuple for AF_INET6), and is meant to be passed to the socket.connect() method.

The following example fetches address information for a hypothetical TCP connection to www.python.org on port 80 (results may differ on your system if IPv6 isn’t enabled):

>>> socket.getaddrinfo("www.python.org", 80, 0, 0, socket.SOL_TCP)
[(2, 1, 6, '', ('82.94.164.162', 80)),
(10, 1, 6, '', ('2001:888:2000:d::a2', 80, 0, 0)

 2. socekt.getaddrinfo的返回值介绍

• family: 表示socket使用的协议簇。常用的协议簇包括AF_UNIX(本机通信）/AF_INET（TCP/IP协议簇中的IPv4协议）/AF_INET6（TCP/IP协议簇中的IPv4协议）。在python的socket包中，用1表示AF_UNIX，2表示AF_INET，10表示AF_INET6。
• sockettype：表示socket的类型。常见的socket类型包括SOCK_STREAM（TCP流）/SOCK_DGRAM（UDP数据报）/SOCK_RAW（原始套接字）。其中，SOCK_STREAM=1，SOCK_DGRAM=2，SOCK_RAW=3
• proto：顾名思义，就是指定协议。套接口所用的协议。如调用者不想指定，可用0。常用的协议有，IPPROTO_TCP(=6)和IPPTOTO_UDP(=17)，它们分别对应TCP传输协议、UDP传输协议。