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https://github.com/samba-team/samba.git
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77d69ab820
Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz> Reviewed-by: Andrew Bartlett <abartlet@samba.org>
198 lines
6.6 KiB
Python
Executable File
198 lines
6.6 KiB
Python
Executable File
#!/usr/bin/env python3
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#
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# Unix SMB/CIFS implementation.
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# Copyright (C) Volker Lendecke 2017
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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#
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# Used by selftest to proxy DNS queries to the correct testenv DC.
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# See selftest/target/README for more details.
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# Based on the EchoServer example from python docs
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import threading
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import sys
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import select
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import socket
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import time
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from samba.dcerpc import dns
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import samba.ndr as ndr
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if sys.version_info[0] < 3:
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import SocketServer
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sserver = SocketServer
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else:
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import socketserver
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sserver = socketserver
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DNS_REQUEST_TIMEOUT = 10
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class DnsHandler(sserver.BaseRequestHandler):
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dns_qtype_strings = dict((v, k) for k, v in vars(dns).items() if k.startswith('DNS_QTYPE_'))
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def dns_qtype_string(self, qtype):
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"Return a readable qtype code"
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return self.dns_qtype_strings[qtype]
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dns_rcode_strings = dict((v, k) for k, v in vars(dns).items() if k.startswith('DNS_RCODE_'))
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def dns_rcode_string(self, rcode):
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"Return a readable error code"
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return self.dns_rcode_strings[rcode]
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def dns_transaction_udp(self, packet, host):
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"send a DNS query and read the reply"
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s = None
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try:
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send_packet = ndr.ndr_pack(packet)
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s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, 0)
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s.settimeout(DNS_REQUEST_TIMEOUT)
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s.connect((host, 53))
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s.sendall(send_packet, 0)
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recv_packet = s.recv(2048, 0)
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return ndr.ndr_unpack(dns.name_packet, recv_packet)
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except socket.error as err:
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print("Error sending to host %s for name %s: %s\n" %
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(host, packet.questions[0].name, err.errno))
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raise
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finally:
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if s is not None:
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s.close()
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return None
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def get_pdc_ipv4_addr(self, lookup_name):
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"""Maps a DNS realm to the IPv4 address of the PDC for that testenv"""
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realm_to_ip_mappings = self.server.realm_to_ip_mappings
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# sort the realms so we find the longest-match first
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testenv_realms = sorted(realm_to_ip_mappings.keys(), key=len)
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testenv_realms.reverse()
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for realm in testenv_realms:
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if lookup_name.endswith(realm):
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# return the corresponding IP address for this realm's PDC
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return realm_to_ip_mappings[realm]
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return None
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def forwarder(self, name):
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lname = name.lower()
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# check for special cases used by tests (e.g. dns_forwarder.py)
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if lname.endswith('an-address-that-will-not-resolve'):
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return 'ignore'
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if lname.endswith('dsfsdfs'):
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return 'fail'
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if lname.endswith("torture1", 0, len(lname)-2):
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# CATCH TORTURE100, TORTURE101, ...
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return 'torture'
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if lname.endswith('_none_.example.com'):
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return 'torture'
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if lname.endswith('torturedom.samba.example.com'):
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return 'torture'
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# return the testenv PDC matching the realm being requested
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return self.get_pdc_ipv4_addr(lname)
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def handle(self):
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start = time.monotonic()
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data, sock = self.request
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query = ndr.ndr_unpack(dns.name_packet, data)
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name = query.questions[0].name
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forwarder = self.forwarder(name)
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response = None
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if forwarder is 'ignore':
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return
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elif forwarder is 'fail':
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pass
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elif forwarder in ['torture', None]:
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response = query
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response.operation |= dns.DNS_FLAG_REPLY
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response.operation |= dns.DNS_FLAG_RECURSION_AVAIL
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response.operation |= dns.DNS_RCODE_NXDOMAIN
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else:
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response = self.dns_transaction_udp(query, forwarder)
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if response is None:
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response = query
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response.operation |= dns.DNS_FLAG_REPLY
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response.operation |= dns.DNS_FLAG_RECURSION_AVAIL
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response.operation |= dns.DNS_RCODE_SERVFAIL
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send_packet = ndr.ndr_pack(response)
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end = time.monotonic()
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tdiff = end - start
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errcode = response.operation & dns.DNS_RCODE
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if tdiff > (DNS_REQUEST_TIMEOUT/5):
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debug = True
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else:
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debug = False
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if debug:
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print("dns_hub: forwarder[%s] client[%s] name[%s][%s] %s response.operation[0x%x] tdiff[%s]\n" %
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(forwarder, self.client_address, name,
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self.dns_qtype_string(query.questions[0].question_type),
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self.dns_rcode_string(errcode), response.operation, tdiff))
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try:
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sock.sendto(send_packet, self.client_address)
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except socket.error as err:
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print("dns_hub: Error sending response to client[%s] for name[%s] tdiff[%s]: %s\n" %
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(self.client_address, name, tdiff, err))
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class server_thread(threading.Thread):
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def __init__(self, server):
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threading.Thread.__init__(self)
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self.server = server
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def run(self):
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self.server.serve_forever()
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print("dns_hub: after serve_forever()")
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def main():
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if len(sys.argv) < 4:
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print("Usage: dns_hub.py TIMEOUT HOST MAPPING")
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sys.exit(1)
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timeout = int(sys.argv[1]) * 1000
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timeout = min(timeout, 2**31 - 1) # poll with 32-bit int can't take more
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host = sys.argv[2]
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server = sserver.UDPServer((host, int(53)), DnsHandler)
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# we pass in the realm-to-IP mappings as a comma-separated key=value
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# string. Convert this back into a dictionary that the DnsHandler can use
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realm_mapping = dict(kv.split('=') for kv in sys.argv[3].split(','))
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server.realm_to_ip_mappings = realm_mapping
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print("dns_hub will proxy DNS requests for the following realms:")
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for realm, ip in server.realm_to_ip_mappings.items():
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print(" {0} ==> {1}".format(realm, ip))
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t = server_thread(server)
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t.start()
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p = select.poll()
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stdin = sys.stdin.fileno()
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p.register(stdin, select.POLLIN)
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p.poll(timeout)
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print("dns_hub: after poll()")
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server.shutdown()
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t.join()
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print("dns_hub: before exit()")
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sys.exit(0)
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main()
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