python - DNS 解析器不包含答案

Question

我正在尝试使用 python 自动执行一些任务。我必须检查某些域是否仍在我们的 DNS 服务器中。因此，通过堆栈搜索，我找到了带有 dns.resolver 的脚本，并尝试使其满足我的需求。因此，脚本如下所示:

import socket
import dns.resolver


mylist=[]
with open('domainfile.txt') as file:
    for line in file:
        mylist.append(line)
length = len(mylist)


resolver = dns.resolver.Resolver()
resolver.nameservers=[socket.gethostbyname('dns.example.com')]

for i in range(length):
    for rdata in resolver.query(mylist[i], 'CNAME') :
        print(rdata.target)

我的domainfile.txt看起来像这样:

domain1
domain2
domain3
[...]

我收到的错误消息是:

Traceback (most recent call last): File "dnspython.py", line 20, in for rdata in resolver.query(lista[i], 'CNAME') : File "/usr/local/lib/python3.7/dist-packages/dns/resolver.py", line 1053, in query raise_on_no_answer) File "/usr/local/lib/python3.7/dist-packages/dns/resolver.py", line 236, in init raise NoAnswer(response=response) dns.resolver.NoAnswer: The DNS response does not contain an answer to the question: domain1\010.example.com. IN CNAME

如果我只是将我的域插入到if语句中，而不是遍历mylist，我就会得到我需要的东西。但是，当我尝试通过列表执行此操作时，它会添加到我的域\010，然后什么也没有发生。你能帮我解决这个问题吗？谢谢!

Answer 1

根据文档，这似乎是预期的:http://www.dnspython.org/docs/1.14.0/dns.resolver.Resolver-class.html#query

Raises:

...

• NoAnswer - the response did not contain an answer and raise_on_no_answer is True.

发生这种情况的原因可能是因为您尚未从域中删除行结尾。

<小时/>

这就是我的做法。

import socket
import dns.resolver


with open('domainlist.txt') as f:
    my_list = [line.strip() for line in f.readlines()]

resolver = dns.resolver.Resolver()
resolver.nameservers=[socket.gethostbyname('dns.example.com')]

for domain in my_list:
    try:
        q = resolver.query(domain, 'CNAME')
        for rdata in q:
            print(f'{domain}: {rdata.target}')
    except dns.resolver.NoAnswer:
        print(f'{domain}: No answer')