doc/names/examples/dns-service.py

   1 #!/usr/bin/env python
   2
   3 # Copyright (c) Twisted Matrix Laboratories.
   4 # See LICENSE for details.
   5
   6 """
   7 Sample app to lookup SRV records in DNS.
   8 To run this script:
   9 $ python dns-service.py <service> <proto> <domain>
  10 where,
  11 service = the symbolic name of the desired service.
  12 proto = the transport protocol of the desired service; this is usually either TCP or UDP.
  13 domain =  the domain name for which this record is valid.
  14 e.g.:
  15 $ python dns-service.py sip udp yahoo.com
  16 $ python dns-service.py xmpp-client tcp gmail.com
  17 """
  18
  19 from twisted.names import client
  20 from twisted.internet import reactor
  21 import sys
  22
  23 def printAnswer((answers, auth, add)):
  24     if not len(answers):
  25         print 'No answers'
  26     else:
  27         print '\n'.join([str(x.payload) for x in answers])
  28     reactor.stop()
  29
  30 def printFailure(arg):
  31     print "error: could not resolve:", arg
  32     reactor.stop()
  33
  34 try:
  35     service, proto, domain = sys.argv[1:]
  36 except ValueError:
  37     sys.stderr.write('%s: usage:\n' % sys.argv[0] +
  38                      '  %s SERVICE PROTO DOMAIN\n' % sys.argv[0])
  39     sys.exit(1)
  40
  41 resolver = client.Resolver('/etc/resolv.conf')
  42 d = resolver.lookupService('_%s._%s.%s' % (service, proto, domain), [1])
  43 d.addCallbacks(printAnswer, printFailure)
  44
  45 reactor.run()