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118 lines
3.3 KiB
Python
118 lines
3.3 KiB
Python
#!/usr/bin/python3
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import os, subprocess, socket, datetime, getopt, sys, re, atexit, yaml, logging as log
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from pathlib import Path
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import dns.flags
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import dns.message
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import dns.rdataclass
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import dns.rdatatype
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import dns.name
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from typing import cast
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def main(args):
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setupLogging(True)
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log.debug("Logging started")
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config = readConfig("config.yml")
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s = setupSocket(config['socket']['address'], config['socket']['port'])
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startListen(s)
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def setupSocket(address, port):
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s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
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s.bind((address, port))
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return s
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def startListen(s):
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log.debug(f'Now listening')
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while True:
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(address, dmsg) = receiveFromWire(s)
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if handleQuery(s, address, dmsg) != True:
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continue
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def receiveFromWire(s):
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(wire, address) = s.recvfrom(512)
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dmsg = dns.message.from_wire(wire)
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return (address, dmsg)
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def handleQuery(s, address, dmsg):
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log.info(f'{address[0]} |\tGot query')
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opcode = dmsg.opcode()
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if opcode != dns.opcode.NOTIFY:
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log.error(f"{address[0]} |\tExpected opcode=NOTIFY, but was {dns.opcode.to_text(opcode)}")
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makeResponseWithRCode(s, address, dmsg, dns.rcode.REFUSED)
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return False
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rcode = dmsg.rcode()
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if rcode != dns.rcode.NOERROR:
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log.error(f"{address[0]} |\tExpected rcode=NOERROR, but was {dns.rcode.to_text(rcode)}")
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makeResponseWithRCode(s, address, dmsg, dns.rcode.FORMERR)
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return False
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#flags = dmsg.flags
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#if flags != dns.flags.AA:
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# print('Expected flags=AA, but was', dns.flags.to_text(flags))
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# continue
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if len(dmsg.question) != 1:
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log.error(f'{address[0]} |\tExpected question-len=1, but was {len(dmsg.question)}')
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makeResponseWithRCode(s, address, dmsg, dns.rcode.FORMERR)
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return False
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# Check record in question
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record = dmsg.question[0]
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r_datatype = record.rdtype;
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if r_datatype != dns.rdatatype.SOA:
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log.error(f'{address[0]} |\tExpected record to be SOA, but was {r_datatype}')
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makeResponseWithRCode(s, address, dmsg, dns.rcode.FORMERR)
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return False
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log.info(f'{address[0]} |\tNOTIFY for {record.name}')
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response = dns.message.make_response(dmsg) # type: dns.message.Message
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response.flags |= dns.flags.AA
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sendResponse(s, address, response)
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log.debug(f'{address[0]} |\tSent response')
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return True
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def makeResponseWithRCode(socket, address, dmsg, rcode):
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response = dns.message.make_response(dmsg) # type: dns.message.Message
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response.set_rcode(rcode)
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sendResponse(socket, address, response)
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def sendResponse(socket, address, response):
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wire = response.to_wire(cast(dns.name.Name, response))
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socket.sendto(wire, address)
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def setupLogging(verbose: bool):
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level = log.INFO
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format = '%(asctime)s %(levelname)s:\t%(message)s'
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if verbose:
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level = log.DEBUG
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log.basicConfig(stream=sys.stdout, format=format, level=level)
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def readConfig(file: str):
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log.debug(f"Reading config '{file}'..")
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if not os.path.isfile(file):
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raise OSError(2, file)
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return readYamlFile(file)
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def readYamlFile(file: str):
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with open(file, "r") as f:
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return yaml.load(f, Loader=yaml.FullLoader)
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if __name__ == "__main__":
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sys.exit(main(sys.argv))
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