bluetooth_packet.h

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/* -*- c++ -*- */
/*
 * Copyright 2008, 2009 Dominic Spill, Michael Ossmann                                                                                            
 * Copyright 2007 Dominic Spill                                                                                                                   
 * Copyright 2005, 2006 Free Software Foundation, Inc.
 * 
 * This file is part of gr-bluetooth
 * 
 * gr-bluetooth is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 * 
 * gr-bluetooth is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with gr-bluetooth; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street,
 * Boston, MA 02110-1301, USA.
 */
//FIXME this file should not be here - copied from gr-bluetooth/src/lib
#ifndef INCLUDED_BLUETOOTH_PACKET_H
#define INCLUDED_BLUETOOTH_PACKET_H

#include <stdint.h>
#include <string>
#include <cstdio>
#include <boost/enable_shared_from_this.hpp>

using namespace std;

class bluetooth_packet;
typedef boost::shared_ptr<bluetooth_packet> bluetooth_packet_sptr;

/*!
 * \brief Return a shared_ptr to a new instance of bluetooth_packet.
 */
bluetooth_packet_sptr bluetooth_make_packet(char *stream, int length);

/* construct with known CLKN and channel */
bluetooth_packet_sptr bluetooth_make_packet(char *stream, int length,
                uint32_t clkn, int channel);


class bluetooth_packet
{
private:
        /* allow bluetooth_make_packet to access the private constructor. */
        friend bluetooth_packet_sptr bluetooth_make_packet(char *stream, int length);
        friend bluetooth_packet_sptr bluetooth_make_packet(char *stream, int length,
                        uint32_t clkn, int channel);

        /* constructor */
        bluetooth_packet(char *stream, int length);

        /* maximum number of symbols */
        static const int MAX_SYMBOLS = 3125;

        /* minimum header bit errors to indicate that this is an ID packet */
        static const int ID_THRESHOLD = 5;

        /* index into whitening data array */
        static const uint8_t INDICES[64];

        /* whitening data */
        static const uint8_t WHITENING_DATA[127];

        /* lookup table for preamble hamming distance */
        static const uint8_t PREAMBLE_DISTANCE[32];

        /* lookup table for trailer hamming distance */
        static const uint8_t TRAILER_DISTANCE[2048];

        /* string representations of packet type */
        static const string TYPE_NAMES[16];

        /* the raw symbol stream, one bit per char */
        //FIXME maybe this should be a vector so we can grow it only to the size
        //needed and later shrink it if we find we have more symbols than necessary
        char d_symbols[MAX_SYMBOLS];

        /* lower address part found in access code */
        uint32_t d_LAP;

        /* upper address part */
        uint8_t d_UAP;

        /* non-significant address part */
        uint16_t d_NAP;

        /* number of symbols */
        int d_length;

        /* packet type */
        int d_packet_type;

        /* packet header, one bit per char */
        char d_packet_header[18];

        /* payload header, one bit per char */
        /* the packet may have a payload header of 0, 1, or 2 bytes, reserving 2 */
        char d_payload_header[16];

        /* number of payload header bytes */
        /* set to 0, 1, 2, or -1 for unknown */
        int d_payload_header_length;

        /* LLID field of payload header (2 bits) */
        uint8_t d_payload_llid;

        /* flow field of payload header (1 bit) */
        uint8_t d_payload_flow;

        /* payload length: the total length of the asynchronous data in bytes.
         * This does not include the length of synchronous data, such as the voice
         * field of a DV packet.
         * If there is a payload header, this payload length is payload body length
         * (the length indicated in the payload header's length field) plus
         * d_payload_header_length plus 2 bytes CRC (if present).
         */
        int d_payload_length;

        /* The actual payload data in host format
         * Ready for passing to wireshark
         * 2744 is the maximum length, but most packets are shorter.
         * Dynamic allocation would probably be better in the long run but is
         * problematic in the short run.
         */
        char d_payload[2744];

        /* is the packet whitened? */
        bool d_whitened;

        /* do we know the UAP/NAP? */
        bool d_have_UAP;
        bool d_have_NAP;

        /* do we know the master clock? */
        bool d_have_clk6;
        bool d_have_clk27;

        bool d_have_payload;

        /* CLK1-27 of master */
        uint32_t d_clock;

        /* type-specific CRC checks and decoding */
        int fhs(int clock);
        int DM(int clock);
        int DH(int clock);
        int EV3(int clock);
        int EV4(int clock);
        int EV5(int clock);
        int HV(int clock);

        /* decode payload header, return value indicates success */
        bool decode_payload_header(char *stream, int clock, int header_bytes, int size, bool fec);

        /* Remove the whitening from an air order array */
        void unwhiten(char* input, char* output, int clock, int length, int skip);

        /* verify the payload CRC */
        bool payload_crc();

public:
        int d_channel;

        /* native (local) clock */
        uint32_t d_clkn;

        /* search a symbol stream to find a packet, return index */
        static int sniff_ac(char *stream, int stream_length);

        /* Error correction coding for Access Code */
        static uint8_t *lfsr(uint8_t *data, int length, int k, uint8_t *g);

        /* Reverse the bits in a byte */
        static uint8_t reverse(char byte);

        /* Generate Access Code from an LAP */
        static uint8_t *acgen(int LAP);

        /* Convert from normal bytes to one-LSB-per-byte format */
        static void convert_to_grformat(uint8_t input, uint8_t *output);

        /* Decode 1/3 rate FEC, three like symbols in a row */
        static bool unfec13(char *input, char *output, int length);

        /* Decode 2/3 rate FEC, a (15,10) shortened Hamming code */
        static char *unfec23(char *input, int length);

        /* When passed 10 bits of data this returns a pointer to a 5 bit hamming code */
        static char *fec23gen(char *data);

        /* Create an Access Code from LAP and check it against stream */
        static bool check_ac(char *stream, int LAP);

        /* Convert some number of bits of an air order array to a host order integer */
        static uint8_t air_to_host8(char *air_order, int bits);
        static uint16_t air_to_host16(char *air_order, int bits);
        static uint32_t air_to_host32(char *air_order, int bits);
        // hmmm, maybe these should have pointer output so they can be overloaded

        /* Convert some number of bits in a host order integer to an air order array */
        static void host_to_air(uint8_t host_order, char *air_order, int bits);

        /* Create the 16bit CRC for packet payloads - input air order stream */
        static uint16_t crcgen(char *payload, int length, int UAP);

        /* extract UAP by reversing the HEC computation */
        static int UAP_from_hec(uint16_t data, uint8_t hec);

        /* check if the packet's CRC is correct for a given clock (CLK1-6) */
        int crc_check(int clock);

        /* decode the packet header */
        bool decode_header();

        /* decode the packet header */
        void decode_payload();

        /* decode the whole packet */
        void decode();

        /* print packet information */
        void print();

        /* format payload for tun interface */
        char *tun_format();

        /* return the packet's LAP */
        uint32_t get_LAP();

        /* return the packet's UAP */
        uint8_t get_UAP();

        /* set the packet's UAP */
        void set_UAP(uint8_t UAP);

        /* set the packet's NAP */
        void set_NAP(uint16_t NAP);

        /* is the packet whitened? */
        bool get_whitened();

        /* set the packet's whitened flag */
        void set_whitened(bool whitened);

        /* have we decoded the payload yet? */
        bool got_payload();

        /* return the packet's clock (CLK1-27) */
        uint32_t get_clock();

        /* set the packet's clock */
        void set_clock(uint32_t clk6, bool have27);

        /* Retrieve the length of the payload data */
        int get_payload_length();

        int get_type();

        /* try a clock value (CLK1-6) to unwhiten packet header,
         * sets resultant d_packet_type and d_UAP, returns UAP.
         */
        uint8_t try_clock(int clock);

        /* check to see if the packet has a header */
        bool header_present();

        /* extract LAP from FHS payload */
        uint32_t lap_from_fhs();

        /* extract UAP from FHS payload */
        uint8_t uap_from_fhs();

        /* extract NAP from FHS payload */
        uint16_t nap_from_fhs();

        /* extract clock from FHS payload */
        uint32_t clock_from_fhs();

        /* destructor */
        ~bluetooth_packet();
};

#endif /* INCLUDED_BLUETOOTH_PACKET_H */