dns.py

#!/usr/bin/env python

"""
Copyright (c) 2006-2015 sqlmap developers (http://sqlmap.org/)
See the file 'doc/COPYING' for copying permission
"""

import os
import re
import socket
import threading
import time

class DNSQuery(object):
    """
    Used for making fake DNS resolution responses based on received
    raw request

    Reference(s):
        http://code.activestate.com/recipes/491264-mini-fake-dns-server/
        https://code.google.com/p/marlon-tools/source/browse/tools/dnsproxy/dnsproxy.py
    """

    def __init__(self, raw):
        self._raw = raw
        self._query = ""

        type_ = (ord(raw[2]) >> 3) & 15                 # Opcode bits

        if type_ == 0:                                  # Standard query
            i = 12
            j = ord(raw[i])

            while j != 0:
                self._query += raw[i + 1:i + j + 1] + '.'
                i = i + j + 1
                j = ord(raw[i])

    def response(self, resolution):
        """
        Crafts raw DNS resolution response packet
        """

        retVal = ""

        if self._query:
            retVal += self._raw[:2]                                             # Transaction ID
            retVal += "\x85\x80"                                                # Flags (Standard query response, No error)
            retVal += self._raw[4:6] + self._raw[4:6] + "\x00\x00\x00\x00"      # Questions and Answers Counts
            retVal += self._raw[12:(12 + self._raw[12:].find("\x00") + 5)]      # Original Domain Name Query
            retVal += "\xc0\x0c"                                                # Pointer to domain name
            retVal += "\x00\x01"                                                # Type A
            retVal += "\x00\x01"                                                # Class IN
            retVal += "\x00\x00\x00\x20"                                        # TTL (32 seconds)
            retVal += "\x00\x04"                                                # Data length
            retVal += "".join(chr(int(_)) for _ in resolution.split('.'))       # 4 bytes of IP

        return retVal

class DNSServer(object):
    def __init__(self):
        self._requests = []
        self._lock = threading.Lock()
        self._socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        self._socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        self._socket.bind(("", 53))
        self._running = False
        self._initialized = False

    def pop(self, prefix=None, suffix=None):
        """
        Returns received DNS resolution request (if any) that has given
        prefix/suffix combination (e.g. prefix.<query result>.suffix.domain)
        """

        retVal = None

        with self._lock:
            for _ in self._requests:
                if prefix is None and suffix is None or re.search("%s\..+\.%s" % (prefix, suffix), _, re.I):
                    retVal = _
                    self._requests.remove(_)
                    break

        return retVal

    def run(self):
        """
        Runs a DNSServer instance as a daemon thread (killed by program exit)
        """

        def _():
            try:
                self._running = True
                self._initialized = True

                while True:
                    data, addr = self._socket.recvfrom(1024)
                    _ = DNSQuery(data)
                    self._socket.sendto(_.response("127.0.0.1"), addr)

                    with self._lock:
                        self._requests.append(_._query)

            except KeyboardInterrupt:
                raise

            finally:
                self._running = False

        thread = threading.Thread(target=_)
        thread.daemon = True
        thread.start()

if __name__ == "__main__":
    server = None
    try:
        server = DNSServer()
        server.run()

        while not server._initialized:
            time.sleep(0.1)

        while server._running:
            while True:
                _ = server.pop()

                if _ is None:
                    break
                else:
                    print "[i] %s" % _

            time.sleep(1)

    except socket.error, ex:
        if 'Permission' in str(ex):
            print "[x] Please run with sudo/Administrator privileges"
        else:
            raise
    except KeyboardInterrupt:
        os._exit(0)
    finally:
        if server:
            server._running = False