printf("-------Ethernet Protocol (Link Layer)---------\n");
/* get ethernet header */
ethernet = (struct db_ethernet*)(packet);
printf("Mac Source Address is:\n");
mac_string=(u_char*)ethernet->ether_shost;
printf("%02x:%02x:%02x:%02x:%02x:%02x\n",*mac_string,*(mac_string+1),*(mac_string+2),*(mac_string+3),*(mac_string+4),*(mac_string+5));
printf("Mac Destination Address is:\n");
mac_string=(u_char*)ethernet->ether_dhost;
printf("%02x:%02x:%02x:%02x:%02x:%02x\n",*mac_string,*(mac_string+1),*(mac_string+2),*(mac_string+3),*(mac_string+4),*(mac_string+5));
ethernet_type=ntohs(ethernet ->ether_type);
switch(ethernet_type)
{
case 0x0800: got_ip_package(args,header,packet);break;
case 0x0806: printf("The network layer is ARP protocol\n");break;
case 0x0835: printf("The network layer is RARP protocol\n");break;
default:break;
}
return;
}
/*function implement end*/
/*main function,entrance for system*/
int main(int argc, char **argv)
{
char *dev = NULL; /* capture device name */
char errbuf[PCAP_ERRBUF_SIZE]; /* error buffer */
pcap_t *handle; /* packet capture handle */
char filter_exp[] = "ip";
//char filter_exp[] = "ip host 127.0.0.1";/*port 3306*//* filter expression [3] */
struct bpf_program fp; /* compiled filter program (expression) */
bpf_u_int32 mask; /* subnet mask */
bpf_u_int32 net; /* ip */
int num_packets = -1; /* number of packets to capture ,-1 is loop*/
print_app_banner();
/* check for capture device name on command-line */
if (argc == 2) {
dev = argv[1];
}
else if (argc > 2) {
fprintf(stderr, "error: unrecognized command-line options\n\n");
print_app_usage();
exit(EXIT_FAILURE);
}
else {
/* find a capture device if not specified on command-line */
dev = pcap_lookupdev(errbuf);
if (dev == NULL) {
fprintf(stderr, "Couldn't find default device: %s\n",
errbuf);
exit(EXIT_FAILURE);
}
}
/* get network number and mask associated with capture device */
if (pcap_lookupnet(dev, &net, &mask, errbuf) == -1) {
fprintf(stderr, "Couldn't get netmask for device %s: %s\n",
dev, errbuf);
net = 0;
mask = 0;
}
/* print capture info */
printf("Device: %s\n", dev);
printf("Number of packets: %d\n", num_packets);
printf("Filter expression: %s\n", filter_exp);
#ifdef OFFLINE
handle=pcap_open_offline("tns.pcap",errbuf);//read offline file
#else
/* open capture device */
handle = pcap_open_live(dev, SNAP_LEN, 1, 1000, errbuf);
#endif
if (handle == NULL) {
fprintf(stderr, "Couldn't open device %s: %s\n", dev, errbuf);
exit(EXIT_FAILURE);
}
/* make sure we're capturing on an Ethernet device [2] */
if (pcap_datalink(handle) != DLT_EN10MB) {
fprintf(stderr, "%s is not an Ethernet\n", dev);
exit(EXIT_FAILURE);
}
/* compile the filter expression */
if (pcap_compile(handle, &fp, filter_exp, 0, net) == -1) {
fprintf(stderr, "Couldn't parse filter %s: %s\n",
filter_exp, pcap_geterr(handle));
exit(EXIT_FAILURE);
}
/* apply the compiled filter */
if (pcap_setfilter(handle, &fp) == -1) {
fprintf(stderr, "Couldn't install filter %s: %s\n",
filter_exp, pcap_geterr(handle));
exit(EXIT_FAILURE);
}
/* now we can set our callback function */
pcap_loop(handle, num_packets, got_ethernet_packet, NULL);
/* cleanup */
pcap_freecode(&fp);
pcap_close(handle);
printf("\nCapture complete.\n");
return 0;
}