#!/usr/bin/env python
# -*- coding: utf-8 -*-

# Copyright (c) 2014 clowwindy
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

import socket
import struct
import common


_request_count = 1

# rfc1035
#                                 1  1  1  1  1  1
#   0  1  2  3  4  5  6  7  8  9  0  1  2  3  4  5
# +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
# |                      ID                       |
# +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
# |QR|   Opcode  |AA|TC|RD|RA|   Z    |   RCODE   |
# +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
# |                    QDCOUNT                    |
# +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
# |                    ANCOUNT                    |
# +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
# |                    NSCOUNT                    |
# +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
# |                    ARCOUNT                    |
# +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+

QTYPE_ANY = 255
QTYPE_A = 1
QTYPE_AAAA = 28
QCLASS_IN = 1


def convert_address(address):
    address = address.strip('.')
    labels = address.split('.')
    results = []
    for label in labels:
        l = len(label)
        if l > 63:
            return None
        results.append(chr(l))
        results.append(label)
    results.append('\0')
    return ''.join(results)


def pack_request(address):
    global _request_count
    header = struct.pack('!HBBHHHH', _request_count, 1, 0, 1, 0, 0, 0)
    addr = convert_address(address)
    qtype_qclass = struct.pack('!HH', QTYPE_A, QCLASS_IN)
    _request_count += 1
    return header + addr + qtype_qclass


def unpack_response(data):
    if len(data) > 12:
        header = struct.unpack('!HBBHHHH', data[:12])
        res_id = header[0]
        res_qr = header[1] & 128
        res_tc = header[1] & 2
        res_ra = header[2] & 128
        res_rcode = header[2] & 15
        res_qdcount = header[3]
        res_ancount = header[4]
        res_nscount = header[5]
        res_arcount = header[6]
        print header
    # TODO detect address type
    print data
    print data.encode('hex')
    return data


def resolve(address, callback):
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.SOL_UDP)
    req = pack_request(address)
    if req is None:
        # TODO
        return
    sock.sendto(req, ('8.8.8.8', 53))
    res, addr = sock.recvfrom(1024)
    parsed_res = unpack_response(res)
    callback(parsed_res)


def test():
    def _callback(address):
        print address

    resolve('www.google.com', _callback)


if __name__ == '__main__':
    test()