/* ethernet.c */
/* 
 * Routines for taking ethernet packets apart.
 */

#include "ethernet.h"
#include <string.h>
#include "misc_fns.h"

int ethernet_packet_from_pcap(pcaprec_hdr_t *hdr,
			      const uint8_t *data,
			      const uint32_t len,
			      ethernet_packet_t *pkt,
			      uint32_t *out_st,
			      uint32_t *out_len)
{
  // 14 bytes of src,dest,type .. 
  if (len < 14)
    {
      return ETHERNET_ERR_PKT_TOO_SHORT;
    }

  // PCap doesn't store CRCs - it stores [dst] [src] [type]
  memcpy(pkt->dst_addr, &data[0], 6);
  memcpy(pkt->src_addr, &data[6], 6);

  // Type/Length is big-endian.
  pkt->typeorlen = uint_16_be(&data[12]);

  // 0x5DC is the maximum frame length in IEEE 802.3 - anything
  // above that here is a type.
  // 
  // Length is just the data length.
  if (pkt->typeorlen <= 0x5DC)
    {
      (*out_len) = pkt->typeorlen;
    }
  else
    {
      // pcap doesn't store the checksum or pad .. 
      (*out_len) = len - 14;
    }
	
  (*out_st) = 14;

  return 0;
}

/* End file */