#!/usr/bin/python3
# -*- coding: utf-8 -*-

# MIT License
#
# Copyright (c) 2019 d0ller (https://github.com/D0ller)
#
# 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.

from scapy.layers.bluetooth import *

### RFCOMM is subset of ETSI TS 07.10 ###
### https://www.etsi.org/deliver/etsi_ts/101300_101399/101369/07.01.00_60/ts_101369v070100p.pdf
##
## RFCOMM Header [total 16 bit]
#
# channel   : RFCOMM Channel [5 bit]
# direction : direction [1 bit]
#
# CR        : Command / Response bit usage [1 bit]
#               0 : Initiator to Responder (Request)
#               1 : Responder to Initiator (Response)
#
# EA        : Extended Address bit [1 bit]
#               always set 1 (for future use)
#
# control   : type of frame [8 bit]
#       [MSB] --------[LSB]
#         0 0 1 * 1 1 1 1 : SABM (Set Asynchronous Balanced Mode)
#         0 1 1 * 0 0 1 1 : UA (Unnum bered Acknowledgement)
#         0 0 0 * 1 1 1 1 : DM (Disconnected Mode)'
#         0 1 0 * 0 0 1 1 : DISC (Disconnect)
#         1 1 1 * 1 1 1 1 : UIH (Unnumbered Information with header check)
#
#       The 5th bit is P/F(Poll Final) bit
#

class RFCOMM_Frame(Packet):
    name = "RFCOMM Frame"

    type_of_frame = {
                      0b00101111 : "SABM",
                      0b00111111 : "SABM P/F",
                      0b01100011 : "UA",
                      0b01110011 : "UA P/F",
                      0b00001111 : "DM",
                      0b00011111 : "DM P/F",
                      0b01000011 : "DISC",
                      0b01010011 : "DISC P/F",
                      0b11101111 : "UIH",
                      0b11111111 : "UIH P/F",
                    }

    crc_table = (0x00, 0x91, 0xe3, 0x72, 0x07, 0x96, 0xe4, 0x75,
                 0x0e, 0x9f, 0xed, 0x7c, 0x09, 0x98, 0xea, 0x7b,
                 0x1c, 0x8d, 0xff, 0x6e, 0x1b, 0x8a, 0xf8, 0x69,
                 0x12, 0x83, 0xf1, 0x60, 0x15, 0x84, 0xf6, 0x67,
                 0x38, 0xa9, 0xdb, 0x4a, 0x3f, 0xae, 0xdc, 0x4d,
                 0x36, 0xa7, 0xd5, 0x44, 0x31, 0xa0, 0xd2, 0x43,
                 0x24, 0xb5, 0xc7, 0x56, 0x23, 0xb2, 0xc0, 0x51,
                 0x2a, 0xbb, 0xc9, 0x58, 0x2d, 0xbc, 0xce, 0x5f,
                 0x70, 0xe1, 0x93, 0x02, 0x77, 0xe6, 0x94, 0x05,
                 0x7e, 0xef, 0x9d, 0x0c, 0x79, 0xe8, 0x9a, 0x0b,
                 0x6c, 0xfd, 0x8f, 0x1e, 0x6b, 0xfa, 0x88, 0x19,
                 0x62, 0xf3, 0x81, 0x10, 0x65, 0xf4, 0x86, 0x17,
                 0x48, 0xd9, 0xab, 0x3a, 0x4f, 0xde, 0xac, 0x3d,
                 0x46, 0xd7, 0xa5, 0x34, 0x41, 0xd0, 0xa2, 0x33,
                 0x54, 0xc5, 0xb7, 0x26, 0x53, 0xc2, 0xb0, 0x21,
                 0x5a, 0xcb, 0xb9, 0x28, 0x5d, 0xcc, 0xbe, 0x2f,
                 0xe0, 0x71, 0x03, 0x92, 0xe7, 0x76, 0x04, 0x95,
                 0xee, 0x7f, 0x0d, 0x9c, 0xe9, 0x78, 0x0a, 0x9b,
                 0xfc, 0x6d, 0x1f, 0x8e, 0xfb, 0x6a, 0x18, 0x89,
                 0xf2, 0x63, 0x11, 0x80, 0xf5, 0x64, 0x16, 0x87,
                 0xd8, 0x49, 0x3b, 0xaa, 0xdf, 0x4e, 0x3c, 0xad,
                 0xd6, 0x47, 0x35, 0xa4, 0xd1, 0x40, 0x32, 0xa3,
                 0xc4, 0x55, 0x27, 0xb6, 0xc3, 0x52, 0x20, 0xb1,
                 0xca, 0x5b, 0x29, 0xb8, 0xcd, 0x5c, 0x2e, 0xbf,
                 0x90, 0x01, 0x73, 0xe2, 0x97, 0x06, 0x74, 0xe5,
                 0x9e, 0x0f, 0x7d, 0xec, 0x99, 0x08, 0x7a, 0xeb,
                 0x8c, 0x1d, 0x6f, 0xfe, 0x8b, 0x1a, 0x68, 0xf9,
                 0x82, 0x13, 0x61, 0xf0, 0x85, 0x14, 0x66, 0xf7,
                 0xa8, 0x39, 0x4b, 0xda, 0xaf, 0x3e, 0x4c, 0xdd,
                 0xa6, 0x37, 0x45, 0xd4, 0xa1, 0x30, 0x42, 0xd3,
                 0xb4, 0x25, 0x57, 0xc6, 0xb3, 0x22, 0x50, 0xc1,
                 0xba, 0x2b, 0x59, 0xc8, 0xbd, 0x2c, 0x5e, 0xcf)

    fields_desc = [
        BitField("channel",0,5),
        BitField("direction",0,1),
        BitField("CR",0,1),
        BitField("EA",1,1),
        ByteEnumField("control",0x2f,type_of_frame),
        #BitField("control_U3bit",1,3),
        #BitField("PF",1,1),
        #BitField("control_L4bit",0,4),
        BitField("payload_length",0,7),
        BitField("payload_length_EA",1,1),
        PacketLenField("rfcomm_payload",None,Raw),
        XByteField("FCS",0),
    ]

    def pre_dissect(self, s):
        #default
        self.fields_desc[-2] = \
            PacketLenField("rfcomm_payload",None,RFCOMM_Payload,
                       length_from=lambda x: x.payload_length)

        if s[1] & 0xef == 0xef: # UIH
            if s[0] & 0b11111000 == 0: # MCC (channel 0)
                self.fields_desc[-2] = \
                    PacketLenField("rfcomm_payload",None,MCC_Hdr,
                                   length_from=lambda x: x.payload_length)
            elif s[1] & 0b00010000 == 0b00010000: # P/F is True
                self.fields_desc[-2] = \
                    PacketLenField("rfcomm_payload",None,RFCOMM_Credit_Based_Payload,
                                   length_from=lambda x: x.payload_length + 1)
        return s

    def post_build(self, pkt, pay):
        print(pkt)
        ## Calculate payload length and FCS
        pkt = list(pkt)

        if pkt[1] & 0xef == 0xef: #UIH
            if pkt[1] & 0b00010000 == 0b00010000: # P/F is True (use credits)
                pkt[2] = ((len(pkt[3:]) - 2) << 1) + pkt[2]
            else: # P/F is False (not use credits)
                pkt[2] = ((len(pkt[3:]) - 1) << 1) + pkt[2]

            pkt[-1] = self.crc8_atm(pkt[0:2])

        else: #SABM, DISC, UA, DM
            #pkt[2] = 1
            pkt[-1] = self.crc8_atm(pkt[0:3])

        pkt = bytes(pkt)

        return pkt + pay

    def crc8_atm(self, data):
        crc8 = 0xff
        for byte in data:
            crc8 = self.crc_table[(crc8 & 0xff) ^ (byte & 0xff)]

        return 0xff - crc8


class RFCOMM_Payload(Packet):
    name = "RFCOMM Payload"
    fields_desc = [
        StrField("data",""),
    ]

class RFCOMM_Credit_Based_Payload(Packet):
    name = "RFCOMM Credit Based Payload"
    fields_desc = [
        ByteField("credits",0x01),
        StrField("data",""),
    ]


class MCC_Hdr(Packet):
    name = "Multiplexer Control Command Header"

    fields_desc = [
        BitField("MCC_type",0x20,6),
        BitField("CR",1,1),
        BitField("EA",1,1),
        BitField("MCC_length",0,7),
        BitField("MCC_length_EA",1,1),
    ]

    def post_build(self, pkt, pay):
        pkt = list(pkt)
        pay = list(pay)
        pkt[-1] = (len(pay) << 1) + pkt[-1]

        pkt = bytes(pkt)
        pay = bytes(pay)

        return pkt + pay


class MCC_PN(Packet):
    name = "Multiplexer Control Command Parameter Negotiation"
    fields_desc = [
        BitField("padding",0,2),
        BitField("channel",0,5),
        BitField("direction",0,1),
        BitField("convergence",0xf,4),
        BitField("type_of_frame",0,4),
        ByteField("priority",0x7),
        ByteField("ack_timer",0),
        LEShortField("max_frame_size",127),
        ByteField("max_num_of_retransmissions",0),
        ByteField("error_recovery_mode",7)
    ]

class MCC_MSC(Packet):
    name = "Multiplexer Control Command Modem Status Command"
    fields_desc = [
        BitField("channel",0,5),
        BitField("direction",0,1),
        BitField("padding",0,1),
        BitField("EA",1,1),
        ByteField("signals",0x8d)
    ]

bind_layers(MCC_Hdr, MCC_PN, MCC_type=0x20)
bind_layers(MCC_Hdr, MCC_MSC, MCC_type=0x38)
