contiki/core/net/mac/frame802154.c

/*
 *
 *  Copyright (c) 2008, Swedish Institute of Computer Science
 *  All rights reserved.
 *
 *  Additional fixes for AVR contributed by:
 *
 *      Colin O'Flynn coflynn@newae.com
 *      Eric Gnoske egnoske@gmail.com
 *      Blake Leverett bleverett@gmail.com
 *      Mike Vidales mavida404@gmail.com
 *      Kevin Brown kbrown3@uccs.edu
 *      Nate Bohlmann nate@elfwerks.com
 *
 *  Additional fixes for MSP430 contributed by:
 *        Joakim Eriksson
 *        Niclas Finne
 *        Nicolas Tsiftes
 *
 *   All rights reserved.
 *
 *   Redistribution and use in source and binary forms, with or without
 *   modification, are permitted provided that the following conditions are met:
 *
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in
 *     the documentation and/or other materials provided with the
 *     distribution.
 *   * Neither the name of the copyright holders nor the names of
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 *  POSSIBILITY OF SUCH DAMAGE.
 *
*/
/*
 *  \brief This file is where the main functions that relate to frame
 *  manipulation will reside.
*/
/**
 *   \addtogroup frame802154
 *   @{
*/
/**
 *  \file
 *  \brief 802.15.4 frame creation and parsing functions
 *
 *  This file converts to and from a structure to a packed 802.15.4
 *  frame.
 */

#include "sys/cc.h"
#include "net/mac/frame802154.h"
#include <string.h>

/**
 *  \brief Structure that contains the lengths of the various addressing and security fields
 *  in the 802.15.4 header.  This structure is used in \ref frame802154_create()
 */
typedef struct {
  uint8_t dest_pid_len;    /**<  Length (in bytes) of destination PAN ID field */
  uint8_t dest_addr_len;   /**<  Length (in bytes) of destination address field */
  uint8_t src_pid_len;     /**<  Length (in bytes) of source PAN ID field */
  uint8_t src_addr_len;    /**<  Length (in bytes) of source address field */
  uint8_t aux_sec_len;     /**<  Length (in bytes) of aux security header field */
} field_length_t;

/*----------------------------------------------------------------------------*/
CC_INLINE static uint8_t
addr_len(uint8_t mode)
{
  switch(mode) {
  case FRAME802154_SHORTADDRMODE:  /* 16-bit address */
    return 2;
  case FRAME802154_LONGADDRMODE:   /* 64-bit address */
    return 8;
  default:
    return 0;
  }
}
/*----------------------------------------------------------------------------*/
static void
field_len(frame802154_t *p, field_length_t *flen)
{
  /* init flen to zeros */
  memset(flen, 0, sizeof(field_length_t));

  /* Determine lengths of each field based on fcf and other args */
  if(p->fcf.dest_addr_mode & 3) {
    flen->dest_pid_len = 2;
  }
  if(p->fcf.src_addr_mode & 3) {
    flen->src_pid_len = 2;
  }

  /* Set PAN ID compression bit if src pan id matches dest pan id. */
  if(p->fcf.dest_addr_mode & 3 && p->fcf.src_addr_mode & 3 &&
     p->src_pid == p->dest_pid) {
    p->fcf.panid_compression = 1;

    /* compressed header, only do dest pid */
    flen->src_pid_len = 0;
  } else {
    p->fcf.panid_compression = 0;
  }

  /* determine address lengths */
  flen->dest_addr_len = addr_len(p->fcf.dest_addr_mode & 3);
  flen->src_addr_len = addr_len(p->fcf.src_addr_mode & 3);

  /* Aux security header */
  if(p->fcf.security_enabled & 1) {
    /* TODO Aux security header not yet implemented */
#if 0
    switch(p->aux_hdr.security_control.key_id_mode) {
    case 0:
      flen->aux_sec_len = 5; /* minimum value */
      break;
    case 1:
      flen->aux_sec_len = 6;
      break;
    case 2:
      flen->aux_sec_len = 10;
      break;
    case 3:
      flen->aux_sec_len = 14;
      break;
    default:
      break;
    }
#endif
  }
}
/*----------------------------------------------------------------------------*/
/**
 *   \brief Calculates the length of the frame header.  This function is
 *   meant to be called by a higher level function, that interfaces to a MAC.
 *
 *   \param p Pointer to frame802154_t_t struct, which specifies the
 *   frame to send.
 *
 *   \return The length of the frame header.
*/
int
frame802154_hdrlen(frame802154_t *p)
{
  field_length_t flen;
  field_len(p, &flen);
  return 3 + flen.dest_pid_len + flen.dest_addr_len +
    flen.src_pid_len + flen.src_addr_len + flen.aux_sec_len;
}
/*----------------------------------------------------------------------------*/
/**
 *   \brief Creates a frame for transmission over the air.  This function is
 *   meant to be called by a higher level function, that interfaces to a MAC.
 *
 *   \param p Pointer to frame802154_t struct, which specifies the
 *   frame to send.
 *
 *   \param buf Pointer to the buffer to use for the frame.
 *
 *   \param buf_len The length of the buffer to use for the frame.
 *
 *   \return The length of the frame header or 0 if there was
 *   insufficient space in the buffer for the frame headers.
*/
int
frame802154_create(frame802154_t *p, uint8_t *buf, int buf_len)
{
  int c;
  field_length_t flen;
  uint8_t *tx_frame_buffer;
  uint8_t pos;

  field_len(p, &flen);

  if(3 + flen.dest_pid_len + flen.dest_addr_len +
     flen.src_pid_len + flen.src_addr_len + flen.aux_sec_len > buf_len) {
    /* Too little space for headers. */
    return 0;
  }

  /* OK, now we have field lengths.  Time to actually construct */
  /* the outgoing frame, and store it in tx_frame_buffer */
  tx_frame_buffer = buf;
  tx_frame_buffer[0] = (p->fcf.frame_type & 7) |
    ((p->fcf.security_enabled & 1) << 3) |
    ((p->fcf.frame_pending & 1) << 4) |
    ((p->fcf.ack_required & 1) << 5) |
    ((p->fcf.panid_compression & 1) << 6);
  tx_frame_buffer[1] = ((p->fcf.dest_addr_mode & 3) << 2) |
    ((p->fcf.frame_version & 3) << 4) |
    ((p->fcf.src_addr_mode & 3) << 6);

  /* sequence number */
  tx_frame_buffer[2] = p->seq;
  pos = 3;

  /* Destination PAN ID */
  if(flen.dest_pid_len == 2) {
    tx_frame_buffer[pos++] = p->dest_pid & 0xff;
    tx_frame_buffer[pos++] = (p->dest_pid >> 8) & 0xff;
  }

  /* Destination address */
  for(c = flen.dest_addr_len; c > 0; c--) {
    tx_frame_buffer[pos++] = p->dest_addr[c - 1];
  }

  /* Source PAN ID */
  if(flen.src_pid_len == 2) {
    tx_frame_buffer[pos++] = p->src_pid & 0xff;
    tx_frame_buffer[pos++] = (p->src_pid >> 8) & 0xff;
  }

  /* Source address */
  for(c = flen.src_addr_len; c > 0; c--) {
    tx_frame_buffer[pos++] = p->src_addr[c - 1];
  }

  /* Aux header */
  if(flen.aux_sec_len) {
    /* TODO Aux security header not yet implemented */
/*     pos += flen.aux_sec_len; */
  }

  return (int)pos;
}
/*----------------------------------------------------------------------------*/
/**
 *   \brief Parses an input frame.  Scans the input frame to find each
 *   section, and stores the information of each section in a
 *   frame802154_t structure.
 *
 *   \param data The input data from the radio chip.
 *   \param len The size of the input data
 *   \param pf The frame802154_t struct to store the parsed frame information.
 */
int
frame802154_parse(uint8_t *data, int len, frame802154_t *pf)
{
  uint8_t *p;
  frame802154_fcf_t fcf;
  int c;

  if(len < 3) {
    return 0;
  }

  p = data;

  /* decode the FCF */
  fcf.frame_type = p[0] & 7;
  fcf.security_enabled = (p[0] >> 3) & 1;
  fcf.frame_pending = (p[0] >> 4) & 1;
  fcf.ack_required = (p[0] >> 5) & 1;
  fcf.panid_compression = (p[0] >> 6) & 1;

  fcf.dest_addr_mode = (p[1] >> 2) & 3;
  fcf.frame_version = (p[1] >> 4) & 3;
  fcf.src_addr_mode = (p[1] >> 6) & 3;

  /* copy fcf and seqNum */
  memcpy(&pf->fcf, &fcf, sizeof(frame802154_fcf_t));
  pf->seq = p[2];
  p += 3;                             /* Skip first three bytes */

  /* Destination address, if any */
  if(fcf.dest_addr_mode) {
    /* Destination PAN */
    pf->dest_pid = p[0] + (p[1] << 8);
    p += 2;

    /* Destination address */
/*     l = addr_len(fcf.dest_addr_mode); */
/*     for(c = 0; c < l; c++) { */
/*       pf->dest_addr.u8[c] = p[l - c - 1]; */
/*     } */
/*     p += l; */
    if(fcf.dest_addr_mode == FRAME802154_SHORTADDRMODE) {
      linkaddr_copy((linkaddr_t *)&(pf->dest_addr), &linkaddr_null);
      pf->dest_addr[0] = p[1];
      pf->dest_addr[1] = p[0];
      p += 2;
    } else if(fcf.dest_addr_mode == FRAME802154_LONGADDRMODE) {
      for(c = 0; c < 8; c++) {
        pf->dest_addr[c] = p[7 - c];
      }
      p += 8;
    }
  } else {
    linkaddr_copy((linkaddr_t *)&(pf->dest_addr), &linkaddr_null);
    pf->dest_pid = 0;
  }

  /* Source address, if any */
  if(fcf.src_addr_mode) {
    /* Source PAN */
    if(!fcf.panid_compression) {
      pf->src_pid = p[0] + (p[1] << 8);
      p += 2;
    } else {
      pf->src_pid = pf->dest_pid;
    }

    /* Source address */
/*     l = addr_len(fcf.src_addr_mode); */
/*     for(c = 0; c < l; c++) { */
/*       pf->src_addr.u8[c] = p[l - c - 1]; */
/*     } */
/*     p += l; */
    if(fcf.src_addr_mode == FRAME802154_SHORTADDRMODE) {
      linkaddr_copy((linkaddr_t *)&(pf->src_addr), &linkaddr_null);
      pf->src_addr[0] = p[1];
      pf->src_addr[1] = p[0];
      p += 2;
    } else if(fcf.src_addr_mode == FRAME802154_LONGADDRMODE) {
      for(c = 0; c < 8; c++) {
        pf->src_addr[c] = p[7 - c];
      }
      p += 8;
    }
  } else {
    linkaddr_copy((linkaddr_t *)&(pf->src_addr), &linkaddr_null);
    pf->src_pid = 0;
  }

  if(fcf.security_enabled) {
    /* TODO aux security header, not yet implemented */
/*     return 0; */
  }

  /* header length */
  c = p - data;
  /* payload length */
  pf->payload_len = (len - c);
  /* payload */
  pf->payload = p;

  /* return header length if successful */
  return c > len ? 0 : c;
}
/** \}   */