#!/usr/bin/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 logging


def inet_ntop(family, ipstr):
    if family == socket.AF_INET:
        return socket.inet_ntoa(ipstr)
    elif family == socket.AF_INET6:
        v6addr = ':'.join(('%02X%02X' % (ord(i), ord(j)))
                          for i, j in zip(ipstr[::2], ipstr[1::2]))
        return v6addr


def inet_pton(family, addr):
    if family == socket.AF_INET:
        return socket.inet_aton(addr)
    elif family == socket.AF_INET6:
        if '.' in addr:  # a v4 addr
            v4addr = addr[addr.rindex(':') + 1:]
            v4addr = socket.inet_aton(v4addr)
            v4addr = map(lambda x: ('%02X' % ord(x)), v4addr)
            v4addr.insert(2, ':')
            newaddr = addr[:addr.rindex(':') + 1] + ''.join(v4addr)
            return inet_pton(family, newaddr)
        dbyts = [0] * 8  # 8 groups
        grps = addr.split(':')
        for i, v in enumerate(grps):
            if v:
                dbyts[i] = int(v, 16)
            else:
                for j, w in enumerate(grps[::-1]):
                    if w:
                        dbyts[7 - j] = int(w, 16)
                    else:
                        break
                break
        return ''.join((chr(i // 256) + chr(i % 256)) for i in dbyts)
    else:
        raise RuntimeError("What family?")


if not hasattr(socket, 'inet_pton'):
    socket.inet_pton = inet_pton

if not hasattr(socket, 'inet_ntop'):
    socket.inet_ntop = inet_ntop


ADDRTYPE_IPV4 = 1
ADDRTYPE_IPV6 = 4
ADDRTYPE_HOST = 3


def parse_header(data):
    addrtype = ord(data[0])
    dest_addr = None
    dest_port = None
    header_length = 0
    if addrtype == ADDRTYPE_IPV4:
        if len(data) >= 7:
            dest_addr = socket.inet_ntoa(data[1:5])
            dest_port = struct.unpack('>H', data[5:7])[0]
            header_length = 7
        else:
            logging.warn('header is too short')
    elif addrtype == ADDRTYPE_HOST:
        if len(data) > 2:
            addrlen = ord(data[1])
            if len(data) >= 2 + addrlen:
                dest_addr = data[2:2 + addrlen]
                dest_port = struct.unpack('>H', data[2 + addrlen:4 +
                                          addrlen])[0]
                header_length = 4 + addrlen
            else:
                logging.warn('header is too short')
        else:
            logging.warn('header is too short')
    elif addrtype == ADDRTYPE_IPV6:
        if len(data) >= 19:
            dest_addr = socket.inet_ntop(socket.AF_INET6, data[1:17])
            dest_port = struct.unpack('>H', data[17:19])[0]
            header_length = 19
        else:
            logging.warn('header is too short')
    else:
        logging.warn('unsupported addrtype %d, maybe wrong password' % addrtype)
    if dest_addr is None:
        return None
    return addrtype, dest_addr, dest_port, header_length