Quick and dirty PCAP parser

gistfile1.c

#include <pcap.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/time.h>

#define IP_SRC_OFFSET 34-8
#define IP_DST_OFFSET 38-8

void dump(char *name);

int main(int argc, char **argv) {
  if (argc < 2) {
    printf("Usage: pppoe-ip <file>\n");
    exit(1);
  }

  dump(argv[1]);
  return EXIT_SUCCESS;
}

void dump(char *fname) {
  char errbuf[PCAP_ERRBUF_SIZE];
  pcap_t *pcap = pcap_open_offline(fname, errbuf);

  unsigned long long sum = 0;
  struct pcap_pkthdr hdr;
  const u_char *packet;
  while ((packet = pcap_next(pcap, &hdr)) != NULL) {
    if (packet[IP_DST_OFFSET + 0] == 217 &&
        packet[IP_DST_OFFSET + 1] == 30 &&
        packet[IP_DST_OFFSET + 2] == 184 &&
        packet[IP_DST_OFFSET + 3] == 161 )
    {
    sum += hdr.len;
      printf("%d\t%d.%d.%d.%d > %d.%d.%d.%d\n",
    hdr.ts.tv_sec,
    packet[IP_SRC_OFFSET + 0],
    packet[IP_SRC_OFFSET + 1],
    packet[IP_SRC_OFFSET + 2],
    packet[IP_SRC_OFFSET + 3],
    packet[IP_DST_OFFSET + 0],
    packet[IP_DST_OFFSET + 1],
    packet[IP_DST_OFFSET + 2],
    packet[IP_DST_OFFSET + 3]);
    }
  }

printf("Total traffic: %lld bytes\n", sum);

}