Twisted Names is both a domain name server as well as a client resolver library. Twisted Names comes with an "out of the box" nameserver which can read most BIND-syntax zone files as well as a simple Python-based configuration format. Twisted Names can act as an authoritative server, perform zone transfers from a master to act as a secondary, act as a caching nameserver, or any combination of these. Twisted Names' client resolver library provides functions to query for all commonly used record types as well as a replacement for the blocking gethostbyname() function provided by the Python stdlib socket module.
Running a caching DNS server is as easy as running twistd. See twistd dns --help for more details
$ twistd -n dns --port 5354 --recursive --cache
This is how you can do some name resolution with Twisted Names.
$ python -m twisted.conch.stdio >>> from twisted.names import client >>> client.getHostByName('twistedmatrix.com') <Deferred at 0x9dcfbac current result: '220.127.116.11'> >>> client.lookupMailExchange('twistedmatrix.com') <Deferred at 0x90eb0ec current result: ([<RR name=twistedmatrix.com type=MX class=IN ttl=86303s auth=False>], , [<RR name=mail.twistedmatrix.com type=A class=IN ttl=86304s auth=False>])>
Twisted has pluggable resolvers, the default resolver reads /etc/resolv.conf (Or C:\windows\system\hosts.txt on windows), /etc/hosts and has a cache. You can create an alternate resolver to resolve names. Such as in the following example.
$ python -m twisted.conch.stdio >>> from twisted.names import client >>> resolver = client.createResolver(servers=[('18.104.22.168', 53), ('22.214.171.124', 53)], hosts='alternate_hosts_file') >>> resolver.getHostByName('example.com') <Deferred at 0x9dcfbac current result: '126.96.36.199'>
You can affect all future name resolution in the reactor and from the twisted.names.client by installing a custom resolver into the reactor.
from twisted.internet import reactor from twisted.names import client reactor.installResolver(client.createResolver(servers=[('188.8.131.52', 53), ('184.108.40.206', 53)], hosts='alternate_hosts_file'))
See the Downloads page.
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