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#!/usr/bin/env python
#
# Unix SMB/CIFS implementation.
# Copyright (C) Volker Lendecke 2017
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
# Based on the EchoServer example from python docs
import threading
import sys
import os
import select
import socket
from samba.dcerpc import dns
from samba.tests.dns_base import DNSTest
import samba.ndr as ndr
if sys.version_info[0] < 3:
import SocketServer
sserver = SocketServer
else:
import socketserver
sserver = socketserver
class DnsHandler(sserver.BaseRequestHandler):
def dns_transaction_udp(self, packet, host):
"send a DNS query and read the reply"
s = None
try:
send_packet = ndr.ndr_pack(packet)
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, 0)
s.settimeout(5)
s.connect((host, 53))
s.sendall(send_packet, 0)
recv_packet = s.recv(2048, 0)
return ndr.ndr_unpack(dns.name_packet, recv_packet)
except socket.error as err:
print("Error sending to host %s for name %s: %s\n" %
(host, packet.questions[0].name, err.errno))
raise
finally:
if s is not None:
s.close()
return None
def forwarder(self, name):
lname = name.lower()
if lname.endswith('an-address-that-will-not-resolve'):
return 'ignore'
if lname.endswith('dsfsdfs'):
return 'fail'
if lname.endswith('adnonssdom.samba.example.com'):
return '127.0.0.17'
if lname.endswith('adnontlmdom.samba.example.com'):
return '127.0.0.18'
if lname.endswith('samba2000.example.com'):
return '127.0.0.25'
if lname.endswith('samba2003.example.com'):
return '127.0.0.26'
if lname.endswith('samba2008r2.example.com'):
return '127.0.0.27'
if lname.endswith('addom.samba.example.com'):
return '127.0.0.30'
if lname.endswith('sub.samba.example.com'):
return '127.0.0.31'
if lname.endswith('chgdcpassword.samba.example.com'):
return '127.0.0.32'
if lname.endswith('backupdom.samba.example.com'):
return '127.0.0.40'
if lname.endswith('renamedom.samba.example.com'):
return '127.0.0.42'
if lname.endswith('labdom.samba.example.com'):
return '127.0.0.43'
if lname.endswith('samba.example.com'):
return '127.0.0.21'
return None
def handle(self):
data, socket = self.request
query = ndr.ndr_unpack(dns.name_packet, data);
name = query.questions[0].name
forwarder = self.forwarder(name)
response = None
if forwarder is 'ignore':
return
elif forwarder is 'fail':
pass
elif forwarder is not None:
response = self.dns_transaction_udp(query, forwarder)
else:
response = query
response.operation |= dns.DNS_FLAG_REPLY
response.operation |= dns.DNS_FLAG_RECURSION_AVAIL
response.operation |= dns.DNS_RCODE_NXDOMAIN
if response is None:
response = query
response.operation |= dns.DNS_FLAG_REPLY
response.operation |= dns.DNS_FLAG_RECURSION_AVAIL
response.operation |= dns.DNS_RCODE_SERVFAIL
send_packet = ndr.ndr_pack(response)
print("dns_hub: sending %s to address %s for name %s\n" %
(forwarder, self.client_address, name))
try:
socket.sendto(send_packet, self.client_address)
except socket.error as err:
print("Error sending %s to address %s for name %s: %s\n" %
(forwarder, self.client_address, name, err.errno))
raise
class server_thread(threading.Thread):
def __init__(self, server):
threading.Thread.__init__(self)
self.server = server
def run(self):
self.server.serve_forever()
print("dns_hub: after serve_forever()")
def main():
timeout = int(sys.argv[1])*1000
timeout = min(timeout, 2**31-1) # poll with 32-bit int can't take more
host = sys.argv[2]
server = sserver.UDPServer((host, int(53)), DnsHandler)
t = server_thread(server)
t.start()
p = select.poll()
stdin = sys.stdin.fileno()
p.register(stdin, select.POLLIN)
p.poll(timeout)
print("dns_hub: after poll()")
server.shutdown()
t.join()
print("dns_hub: before exit()")
sys.exit(0)
main()
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