selftest/target/dns_hub.py

   1 #!/usr/bin/env python
   2 #
   3 # Unix SMB/CIFS implementation.
   4 # Copyright (C) Volker Lendecke 2017
   5 #
   6 # This program is free software; you can redistribute it and/or modify
   7 # it under the terms of the GNU General Public License as published by
   8 # the Free Software Foundation; either version 3 of the License, or
   9 # (at your option) any later version.
  10 #
  11 # This program is distributed in the hope that it will be useful,
  12 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 # GNU General Public License for more details.
  15 #
  16 # You should have received a copy of the GNU General Public License
  17 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 #
  19 # Based on the EchoServer example from python docs
  20
  21 import threading
  22 import sys
  23 import select
  24 import socket
  25 from samba.dcerpc import dns
  26 import samba.ndr as ndr
  27
  28 if sys.version_info[0] < 3:
  29     import SocketServer
  30     sserver = SocketServer
  31 else:
  32     import socketserver
  33     sserver = socketserver
  34
  35
  36 class DnsHandler(sserver.BaseRequestHandler):
  37     def dns_transaction_udp(self, packet, host):
  38         "send a DNS query and read the reply"
  39         s = None
  40         try:
  41             send_packet = ndr.ndr_pack(packet)
  42             s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, 0)
  43             s.settimeout(5)
  44             s.connect((host, 53))
  45             s.sendall(send_packet, 0)
  46             recv_packet = s.recv(2048, 0)
  47             return ndr.ndr_unpack(dns.name_packet, recv_packet)
  48         except socket.error as err:
  49             print("Error sending to host %s for name %s: %s\n" %
  50                   (host, packet.questions[0].name, err.errno))
  51             raise
  52         finally:
  53             if s is not None:
  54                 s.close()
  55         return None
  56
  57     def forwarder(self, name):
  58         lname = name.lower()
  59
  60         if lname.endswith('an-address-that-will-not-resolve'):
  61             return 'ignore'
  62         if lname.endswith('dsfsdfs'):
  63             return 'fail'
  64         if lname.endswith('adnonssdom.samba.example.com'):
  65             return '127.0.0.17'
  66         if lname.endswith('adnontlmdom.samba.example.com'):
  67             return '127.0.0.18'
  68         if lname.endswith('samba2000.example.com'):
  69             return '127.0.0.25'
  70         if lname.endswith('samba2003.example.com'):
  71             return '127.0.0.26'
  72         if lname.endswith('samba2008r2.example.com'):
  73             return '127.0.0.27'
  74         if lname.endswith('addom.samba.example.com'):
  75             return '127.0.0.30'
  76         if lname.endswith('sub.samba.example.com'):
  77             return '127.0.0.31'
  78         if lname.endswith('chgdcpassword.samba.example.com'):
  79             return '127.0.0.32'
  80         if lname.endswith('backupdom.samba.example.com'):
  81             return '127.0.0.40'
  82         if lname.endswith('renamedom.samba.example.com'):
  83             return '127.0.0.42'
  84         if lname.endswith('labdom.samba.example.com'):
  85             return '127.0.0.43'
  86         if lname.endswith('samba.example.com'):
  87             return '127.0.0.21'
  88         return None
  89
  90     def handle(self):
  91         data, sock = self.request
  92         query = ndr.ndr_unpack(dns.name_packet, data)
  93         name = query.questions[0].name
  94         forwarder = self.forwarder(name)
  95         response = None
  96
  97         if forwarder is 'ignore':
  98             return
  99         elif forwarder is 'fail':
 100             pass
 101         elif forwarder is not None:
 102             response = self.dns_transaction_udp(query, forwarder)
 103         else:
 104             response = query
 105             response.operation |= dns.DNS_FLAG_REPLY
 106             response.operation |= dns.DNS_FLAG_RECURSION_AVAIL
 107             response.operation |= dns.DNS_RCODE_NXDOMAIN
 108
 109         if response is None:
 110             response = query
 111             response.operation |= dns.DNS_FLAG_REPLY
 112             response.operation |= dns.DNS_FLAG_RECURSION_AVAIL
 113             response.operation |= dns.DNS_RCODE_SERVFAIL
 114
 115         send_packet = ndr.ndr_pack(response)
 116
 117         print("dns_hub: sending %s to address %s for name %s\n" %
 118             (forwarder, self.client_address, name))
 119
 120         try:
 121             sock.sendto(send_packet, self.client_address)
 122         except socket.error as err:
 123             print("Error sending %s to address %s for name %s: %s\n" %
 124                 (forwarder, self.client_address, name, err))
 125
 126
 127 class server_thread(threading.Thread):
 128     def __init__(self, server):
 129         threading.Thread.__init__(self)
 130         self.server = server
 131
 132     def run(self):
 133         self.server.serve_forever()
 134         print("dns_hub: after serve_forever()")
 135
 136
 137 def main():
 138     timeout = int(sys.argv[1]) * 1000
 139     timeout = min(timeout, 2**31 - 1)  # poll with 32-bit int can't take more
 140     host = sys.argv[2]
 141     server = sserver.UDPServer((host, int(53)), DnsHandler)
 142     t = server_thread(server)
 143     t.start()
 144     p = select.poll()
 145     stdin = sys.stdin.fileno()
 146     p.register(stdin, select.POLLIN)
 147     p.poll(timeout)
 148     print("dns_hub: after poll()")
 149     server.shutdown()
 150     t.join()
 151     print("dns_hub: before exit()")
 152     sys.exit(0)
 153
 154 main()