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/* Trivial libtrace program that counts the number of MPLS packets in a trace.
* Designed to demonstrate the use of trace_get_payload_from_layer2()
*/
#include "libtrace.h"
#include <stdio.h>
#include <inttypes.h>
#include <assert.h>
#include <getopt.h>
uint64_t count = 0;
static void per_packet(libtrace_packet_t *packet)
{
void *l2 = NULL;
void *l2_payload = NULL;
libtrace_linktype_t link_type;
uint16_t ethertype;
uint32_t remaining;
/* Jump straight to the link layer header */
l2 = trace_get_layer2(packet, &link_type, &remaining);
/* No layer 2 header */
if (l2 == NULL)
return;
/* XXX We could check if link_type is ethernet here, but this won't
* affect our results in any way */
/* Skip past the initial layer 2 header to look for an MPLS header */
l2_payload = trace_get_payload_from_layer2(l2, link_type, ðertype,
&remaining);
/* Incomplete layer 2 header */
if (l2_payload == NULL)
return;
/* Zero bytes of payload remaining so there is no useful header
* available */
if (remaining == 0)
return;
/* If the returned header is not an MPLS header, we want to return
* without incrementing our counter */
if (ethertype != 0x8847)
return;
/* Otherwise, we must have an MPLS tag - increment the counter */
count += 1;
}
static void libtrace_cleanup(libtrace_t *trace, libtrace_packet_t *packet) {
/* It's very important to ensure that we aren't trying to destroy
* a NULL structure, so each of the destroy calls will only occur
* if the structure exists */
if (trace)
trace_destroy(trace);
if (packet)
trace_destroy_packet(packet);
}
int main(int argc, char *argv[])
{
/* This is essentially the same main function from readdemo.c */
libtrace_t *trace = NULL;
libtrace_packet_t *packet = NULL;
/* Ensure we have at least one argument after the program name */
if (argc < 2) {
fprintf(stderr, "Usage: %s inputURI\n", argv[0]);
return 1;
}
packet = trace_create_packet();
if (packet == NULL) {
perror("Creating libtrace packet");
libtrace_cleanup(trace, packet);
return 1;
}
trace = trace_create(argv[1]);
if (trace_is_err(trace)) {
trace_perror(trace,"Opening trace file");
libtrace_cleanup(trace, packet);
return 1;
}
if (trace_start(trace) == -1) {
trace_perror(trace,"Starting trace");
libtrace_cleanup(trace, packet);
return 1;
}
while (trace_read_packet(trace,packet)>0) {
per_packet(packet);
}
if (trace_is_err(trace)) {
trace_perror(trace,"Reading packets");
libtrace_cleanup(trace, packet);
return 1;
}
printf("Packet Count = %" PRIu64 "\n", count);
libtrace_cleanup(trace, packet);
return 0;
}
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