如何在Python中进行DNS查找，包括引用/ etc/hosts？

Question

dnspython会很好地完成我的DNS查找，但它完全忽略/etc/hosts的内容。

是否有一个python库调用会做正确的事情？即首先检查etc/hosts，然后才回退到DNS查找。

Answer 1

我不确定你是否想要自己做DNS查找你自己或者你只是想要一个主机的IP。如果你想要后者，

import socket 
print socket.gethostbyname('localhost') # result from hosts file 
print socket.gethostbyname('google.com') # your os sends out a dns query 

Answer 2

Python中的正常名称解析工作正常。为什么你需要DNSpython呢。只要使用socket的getaddrinfo跟随配置为您的操作系统的规则（Debian的，它遵循​​：

>>> print socket.getaddrinfo('google.com', 80) 
[(10, 1, 6, '', ('2a00:1450:8006::63', 80, 0, 0)), (10, 2, 17, '', ('2a00:1450:8006::63', 80, 0, 0)), (10, 3, 0, '', ('2a00:1450:8006::63', 80, 0, 0)), (10, 1, 6, '', ('2a00:1450:8006::68', 80, 0, 0)), (10, 2, 17, '', ('2a00:1450:8006::68', 80, 0, 0)), (10, 3, 0, '', ('2a00:1450:8006::68', 80, 0, 0)), (10, 1, 6, '', ('2a00:1450:8006::93', 80, 0, 0)), (10, 2, 17, '', ('2a00:1450:8006::93', 80, 0, 0)), (10, 3, 0, '', ('2a00:1450:8006::93', 80, 0, 0)), (2, 1, 6, '', ('209.85.229.104', 80)), (2, 2, 17, '', ('209.85.229.104', 80)), (2, 3, 0, '', ('209.85.229.104', 80)), (2, 1, 6, '', ('209.85.229.99', 80)), (2, 2, 17, '', ('209.85.229.99', 80)), (2, 3, 0, '', ('209.85.229.99', 80)), (2, 1, 6, '', ('209.85.229.147', 80)), (2, 2, 17, '', ('209.85.229.147', 80)), (2, 3, 0, '', ('209.85.229.147', 80))] 

Answer 3

我发现这种方式来扩展DNS RR主机名扩展到IP地址的列表，进成员的主机名列表：

#!/usr/bin/python 

def expand_dnsname(dnsname): 
    from socket import getaddrinfo 
    from dns import reversename, resolver 
    namelist = [ ] 
    # expand hostname into dict of ip addresses 
    iplist = dict() 
    for answer in getaddrinfo(dnsname, 80): 
     ipa = str(answer[4][0]) 
     iplist[ipa] = 0 
    # run through the list of IP addresses to get hostnames 
    for ipaddr in sorted(iplist): 
     rev_name = reversename.from_address(ipaddr) 
     # run through all the hostnames returned, ignoring the dnsname 
     for answer in resolver.query(rev_name, "PTR"): 
      name = str(answer) 
      if name != dnsname: 
       # add it to the list of answers 
       namelist.append(name) 
       break 
    # if no other choice, return the dnsname 
    if len(namelist) == 0: 
     namelist.append(dnsname) 
    # return the sorted namelist 
    namelist = sorted(namelist) 
    return namelist 

namelist = expand_dnsname('google.com.') 
for name in namelist: 
    print name 

，当我运行它，列出了一些1e100.net主机名：

Answer 4

list(map(lambda x: x[4][0], socket.getaddrinfo(\ 
    'www.example.com.',22,type=socket.SOCK_STREAM))) 

为您提供www.example.com的地址列表。 （ipv4和ipv6）