Demos/Host/Incomplete/BluetoothHost/Lib/RFCOMM.c

   1 /*
   2              LUFA Library
   3      Copyright (C) Dean Camera, 2010.
   4
   5   dean [at] fourwalledcubicle [dot] com
   6       www.fourwalledcubicle.com
   7 */
   8
   9 /*
  10   Copyright 2010  Dean Camera (dean [at] fourwalledcubicle [dot] com)
  11
  12   Permission to use, copy, modify, distribute, and sell this
  13   software and its documentation for any purpose is hereby granted
  14   without fee, provided that the above copyright notice appear in
  15   all copies and that both that the copyright notice and this
  16   permission notice and warranty disclaimer appear in supporting
  17   documentation, and that the name of the author not be used in
  18   advertising or publicity pertaining to distribution of the
  19   software without specific, written prior permission.
  20
  21   The author disclaim all warranties with regard to this
  22   software, including all implied warranties of merchantability
  23   and fitness.  In no event shall the author be liable for any
  24   special, indirect or consequential damages or any damages
  25   whatsoever resulting from loss of use, data or profits, whether
  26   in an action of contract, negligence or other tortious action,
  27   arising out of or in connection with the use or performance of
  28   this software.
  29 */
  30
  31 /** \file
  32  *
  33  *  RFCOMM layer module. This module manages the RFCOMM layer of the
  34  *  stack, providing virtual serial port channels on top of the lower
  35  *  L2CAP layer.
  36  */
  37
  38 #define  INCLUDE_FROM_RFCOMM_C
  39 #include "RFCOMM.h"
  40
  41 /** 8-Bit CRC table used by the FCS field of each RFCOMM encoded frame, sourced from the ETSI TS 101 369 V7.2.0
  42  *  specification document, upon which the RFCOMM specification is based.
  43  */
  44 const uint8_t CRC8_Table[256] PROGMEM =
  45         {
  46                 0x00, 0x91, 0xE3, 0x72, 0x07, 0x96, 0xE4, 0x75, 0x0E, 0x9F, 0xED, 0x7C, 0x09, 0x98, 0xEA, 0x7B,
  47                 0x1C, 0x8D, 0xFF, 0x6E, 0x1B, 0x8A, 0xF8, 0x69, 0x12, 0x83, 0xF1, 0x60, 0x15, 0x84, 0xF6, 0x67,
  48                 0x38, 0xA9, 0xDB, 0x4A, 0x3F, 0xAE, 0xDC, 0x4D, 0x36, 0xA7, 0xD5, 0x44, 0x31, 0xA0, 0xD2, 0x43,
  49                 0x24, 0xB5, 0xC7, 0x56, 0x23, 0xB2, 0xC0, 0x51, 0x2A, 0xBB, 0xC9, 0x58, 0x2D, 0xBC, 0xCE, 0x5F,
  50                 0x70, 0xE1, 0x93, 0x02, 0x77, 0xE6, 0x94, 0x05, 0x7E, 0xEF, 0x9D, 0x0C, 0x79, 0xE8, 0x9A, 0x0B,
  51                 0x6C, 0xFD, 0x8F, 0x1E, 0x6B, 0xFA, 0x88, 0x19, 0x62, 0xF3, 0x81, 0x10, 0x65, 0xF4, 0x86, 0x17,
  52                 0x48, 0xD9, 0xAB, 0x3A, 0x4F, 0xDE, 0xAC, 0x3D, 0x46, 0xD7, 0xA5, 0x34, 0x41, 0xD0, 0xA2, 0x33,
  53                 0x54, 0xC5, 0xB7, 0x26, 0x53, 0xC2, 0xB0, 0x21, 0x5A, 0xCB, 0xB9, 0x28, 0x5D, 0xCC, 0xBE, 0x2F,
  54                 0xE0, 0x71, 0x03, 0x92, 0xE7, 0x76, 0x04, 0x95, 0xEE, 0x7F, 0x0D, 0x9C, 0xE9, 0x78, 0x0A, 0x9B,
  55                 0xFC, 0x6D, 0x1F, 0x8E, 0xFB, 0x6A, 0x18, 0x89, 0xF2, 0x63, 0x11, 0x80, 0xF5, 0x64, 0x16, 0x87,
  56                 0xD8, 0x49, 0x3B, 0xAA, 0xDF, 0x4E, 0x3C, 0xAD, 0xD6, 0x47, 0x35, 0xA4, 0xD1, 0x40, 0x32, 0xA3,
  57                 0xC4, 0x55, 0x27, 0xB6, 0xC3, 0x52, 0x20, 0xB1, 0xCA, 0x5B, 0x29, 0xB8, 0xCD, 0x5C, 0x2E, 0xBF,
  58                 0x90, 0x01, 0x73, 0xE2, 0x97, 0x06, 0x74, 0xE5, 0x9E, 0x0F, 0x7D, 0xEC, 0x99, 0x08, 0x7A, 0xEB,
  59                 0x8C, 0x1D, 0x6F, 0xFE, 0x8B, 0x1A, 0x68, 0xF9, 0x82, 0x13, 0x61, 0xF0, 0x85, 0x14, 0x66, 0xF7,
  60                 0xA8, 0x39, 0x4B, 0xDA, 0xAF, 0x3E, 0x4C, 0xDD, 0xA6, 0x37, 0x45, 0xD4, 0xA1, 0x30, 0x42, 0xD3,
  61                 0xB4, 0x25, 0x57, 0xC6, 0xB3, 0x22, 0x50, 0xC1, 0xBA, 0x2B, 0x59, 0xC8, 0xBD, 0x2C, 0x5E, 0xCF
  62         };
  63
  64 /** RFCOMM channel state structure, to retain information about each open channel in the RFCOMM multiplexer. */
  65 RFCOMM_Channel_t RFCOMM_Channels[RFCOMM_MAX_OPEN_CHANNELS];
  66
  67
  68 /** Initializes the RFCOMM service, ready for new connections from a SDP client. */
  69 void RFCOMM_Initialize(void)
  70 {
  71         /* Reset the RFCOMM channel structures, to invalidate any confiured RFCOMM channels */
  72         for (uint8_t i = 0; i < RFCOMM_MAX_OPEN_CHANNELS; i++)
  73           RFCOMM_Channels[i].State = RFCOMM_Channel_Closed;
  74 }
  75
  76 void RFCOMM_ProcessPacket(void* Data, Bluetooth_Channel_t* const Channel)
  77 {
  78         const RFCOMM_Header_t* FrameHeader  = (const RFCOMM_Header_t*)Data;
  79         const uint8_t*         FrameData    = (const uint8_t*)Data + sizeof(RFCOMM_Header_t);
  80         uint16_t               FrameDataLen = RFCOMM_GetVariableFieldValue(&FrameData);
  81
  82         /* Decode the RFCOMM frame type from the header */
  83         switch (FrameHeader->Control & ~FRAME_POLL_FINAL)
  84         {
  85                 case RFCOMM_Frame_DM:
  86                         RFCOMM_ProcessDM(&FrameHeader->Address, Channel);
  87                         break;
  88                 case RFCOMM_Frame_DISC:
  89                         RFCOMM_ProcessDISC(&FrameHeader->Address, Channel);
  90                         break;
  91                 case RFCOMM_Frame_SABM:
  92                         RFCOMM_ProcessSABM(&FrameHeader->Address, Channel);
  93                         break;
  94                 case RFCOMM_Frame_UA:
  95                         RFCOMM_ProcessUA(&FrameHeader->Address, Channel);
  96                         break;
  97                 case RFCOMM_Frame_UIH:
  98                         RFCOMM_ProcessUIH(&FrameHeader->Address, FrameDataLen, FrameData, Channel);
  99                         break;
 100                 default:
 101                         BT_RFCOMM_DEBUG(1, "<< Unknown Frame Received");
 102                         break;
 103         }
 104 }
 105
 106 RFCOMM_Channel_t* RFCOMM_GetChannelData(const uint8_t DLCI)
 107 {
 108         /* Search through the RFCOMM channel list, looking for the specified channel */
 109         for (uint8_t i = 0; i < RFCOMM_MAX_OPEN_CHANNELS; i++)
 110         {
 111                 RFCOMM_Channel_t* CurrRFCOMMChannel = &RFCOMM_Channels[i];
 112
 113                 /* If the current non-closed channel's DLCI matches the search DLCI, return it to the caller */
 114                 if ((CurrRFCOMMChannel->DLCI == DLCI) && (CurrRFCOMMChannel->State != RFCOMM_Channel_Closed))
 115                   return CurrRFCOMMChannel;
 116         }
 117
 118         /* Channel not found in the channel state table, return failure */
 119         return NULL;
 120 }
 121
 122 uint16_t RFCOMM_GetVariableFieldValue(const uint8_t** BufferPos)
 123 {
 124         uint8_t FirstOctet;
 125         uint8_t SecondOctet = 0;
 126
 127         FirstOctet = **BufferPos;
 128         (*BufferPos)++;
 129
 130         /* If the field size is more than a single byte, fetch the next byte in the variable length field */
 131         if (!(FirstOctet & 0x01))
 132         {
 133                 SecondOctet = **BufferPos;
 134                 (*BufferPos)++;
 135
 136                 /* Discard any remaining bytes in the variable length field that won't fit in the return value */
 137                 while (!(**BufferPos & 0x01))
 138                   (*BufferPos)++;
 139         }
 140
 141         /* Bitshift the bytes that comprise the variable length field so that they form a single integer */
 142         return (((uint16_t)SecondOctet << 7) | FirstOctet >> 1);
 143 }
 144
 145 void RFCOMM_SendFrame(const uint8_t DLCI, const bool CommandResponse, const uint8_t Control, const uint16_t DataLen,
 146                       const void* Data, Bluetooth_Channel_t* const Channel)
 147 {
 148         struct
 149         {
 150                 RFCOMM_Header_t FrameHeader;
 151                 uint8_t         Size[(DataLen < 128) ? 1 : 2];
 152                 uint8_t         Data[DataLen];
 153                 uint8_t         FCS;
 154         } ResponsePacket;
 155
 156         /* Set the frame header values to the specified address and frame type */
 157         ResponsePacket.FrameHeader.Control = Control;
 158         ResponsePacket.FrameHeader.Address = (RFCOMM_Address_t)
 159                 {
 160                         .EA   = true,
 161                         .CR   = CommandResponse,
 162                         .DLCI = DLCI,
 163                 };
 164
 165         /* Set the lower 7 bits of the packet length */
 166         ResponsePacket.Size[0] = (DataLen << 1);
 167
 168         /* Terminate the size field if size is 7 bits or lower, otherwise set the upper 8 bits of the length */
 169         if (DataLen < 128)
 170           ResponsePacket.Size[0] |= 0x01;
 171         else
 172           ResponsePacket.Size[1]  = (DataLen >> 7);
 173
 174         /* Copy over the packet data from the source buffer to the response packet buffer */
 175         memcpy(ResponsePacket.Data, Data, DataLen);
 176
 177         /* Determine the length of the frame which is to be used to calculate the CRC value */
 178         uint8_t CRCLength = sizeof(ResponsePacket.FrameHeader);
 179
 180         /* UIH frames do not have the CRC calculated on the Size field in the response, all other frames do */
 181         if ((Control & ~FRAME_POLL_FINAL) != RFCOMM_Frame_UIH)
 182           CRCLength += sizeof(ResponsePacket.Size);
 183
 184         /* Calculate the frame checksum from the appropriate fields */
 185         ResponsePacket.FCS = RFCOMM_GetFCSValue(&ResponsePacket, CRCLength);
 186
 187         /* Send the completed response packet to the sender */
 188         Bluetooth_SendPacket(&ResponsePacket, sizeof(ResponsePacket), Channel);
 189 }
 190
 191 static uint8_t RFCOMM_GetFCSValue(const void* FrameStart, uint8_t Length)
 192 {
 193         uint8_t FCS = 0xFF;
 194
 195         for (uint8_t i = 0; i < Length; i++)
 196           FCS = pgm_read_byte(&CRC8_Table[FCS ^ ((uint8_t*)FrameStart)[i]]);
 197
 198         return ~FCS;
 199 }
 200
 201 static void RFCOMM_ProcessDM(const RFCOMM_Address_t* const FrameAddress, Bluetooth_Channel_t* const Channel)
 202 {
 203         BT_RFCOMM_DEBUG(1, "<< DM Received");
 204         BT_RFCOMM_DEBUG(2, "-- DLCI 0x%02X", FrameAddress->DLCI);
 205 }
 206
 207 static void RFCOMM_ProcessDISC(const RFCOMM_Address_t* const FrameAddress, Bluetooth_Channel_t* const Channel)
 208 {
 209         BT_RFCOMM_DEBUG(1, "<< DISC Received");
 210         BT_RFCOMM_DEBUG(2, "-- DLCI 0x%02X", FrameAddress->DLCI);
 211
 212         RFCOMM_Channel_t* RFCOMMChannel = RFCOMM_GetChannelData(FrameAddress->DLCI);
 213
 214         /* If the requested channel is currently open, destroy it */
 215         if (RFCOMMChannel != NULL)
 216           RFCOMMChannel->DLCI = 0x00;
 217
 218         BT_RFCOMM_DEBUG(1, ">> UA Sent");
 219         RFCOMM_SendFrame(FrameAddress->DLCI, true, (RFCOMM_Frame_UA | FRAME_POLL_FINAL), 0, NULL, Channel);
 220 }
 221
 222 static void RFCOMM_ProcessSABM(const RFCOMM_Address_t* const FrameAddress, Bluetooth_Channel_t* const Channel)
 223 {
 224         BT_RFCOMM_DEBUG(1, "<< SABM Received");
 225         BT_RFCOMM_DEBUG(2, "-- DLCI 0x%02X", FrameAddress->DLCI);
 226
 227         /* Find a free entry in the RFCOMM channel multiplexer state array */
 228         for (uint8_t i = 0; i < RFCOMM_MAX_OPEN_CHANNELS; i++)
 229         {
 230                 RFCOMM_Channel_t* CurrRFCOMMChannel = &RFCOMM_Channels[i];
 231
 232                 /* If the channel's DLCI is zero, the channel state entry is free */
 233                 if (!(CurrRFCOMMChannel->DLCI))
 234                 {
 235                         CurrRFCOMMChannel->DLCI         = FrameAddress->DLCI;
 236                         CurrRFCOMMChannel->State        = RFCOMM_Channel_Open;
 237                         CurrRFCOMMChannel->Priority     = 7 + (CurrRFCOMMChannel->DLCI >> 3) + ((CurrRFCOMMChannel->DLCI >> 3) * 7);
 238                         CurrRFCOMMChannel->UseUIFrames  = false;
 239                         CurrRFCOMMChannel->MTU          = 0xFFFF;
 240                         CurrRFCOMMChannel->Signals      = 0;
 241                         CurrRFCOMMChannel->BreakSignals = 0;
 242
 243                         BT_RFCOMM_DEBUG(1, ">> UA Sent");
 244                         RFCOMM_SendFrame(FrameAddress->DLCI, true, (RFCOMM_Frame_UA | FRAME_POLL_FINAL), 0, NULL, Channel);
 245                         return;
 246                 }
 247         }
 248
 249         BT_RFCOMM_DEBUG(1, ">> DM Sent");
 250
 251         /* No free channel in the multiplexer - decline the SABM by sending a DM frame */
 252         RFCOMM_SendFrame(FrameAddress->DLCI, true, (RFCOMM_Frame_DM | FRAME_POLL_FINAL), 0, NULL, Channel);
 253 }
 254
 255 static void RFCOMM_ProcessUA(const RFCOMM_Address_t* const FrameAddress, Bluetooth_Channel_t* const Channel)
 256 {
 257         BT_RFCOMM_DEBUG(1, "<< UA Received");
 258         BT_RFCOMM_DEBUG(2, "-- DLCI 0x%02X", FrameAddress->DLCI);
 259 }
 260
 261 static void RFCOMM_ProcessUIH(const RFCOMM_Address_t* const FrameAddress, const uint16_t FrameLength,
 262                               const uint8_t* FrameData, Bluetooth_Channel_t* const Channel)
 263 {
 264         if (FrameAddress->DLCI == RFCOMM_CONTROL_DLCI)
 265         {
 266                 RFCOMM_ProcessControlCommand(FrameData, Channel);
 267                 return;
 268         }
 269
 270         BT_RFCOMM_DEBUG(1, "<< UIH Received");
 271         BT_RFCOMM_DEBUG(2, "-- DLCI 0x%02X", FrameAddress->DLCI);
 272         BT_RFCOMM_DEBUG(2, "-- Length 0x%02X", FrameLength);
 273
 274         puts("RFCOMM Data: ");
 275
 276         for (uint8_t i = 0; i < FrameLength; i++)
 277           printf("0x%02X (%c) ", FrameData[i], FrameData[i]);
 278
 279         printf("\r\n");
 280 }