source: test/test-layer2-headers.c

#include "libtrace.h"
#include <stdio.h>
#include <stdlib.h>

void iferr(libtrace_t *trace)
{
        libtrace_err_t err = trace_get_err(trace);
        if (err.err_num==0)
                return;
        printf("Error: %s\n",err.problem);
        exit(1);
}


int main(int argc, char *argv[]) {

        libtrace_t *trace = NULL;
        libtrace_packet_t *packet = NULL;
        int i = 0;
        uint16_t mplslabel;
        uint8_t *mplsptr;
        uint32_t remaining;
        int error = 0;

        packet = trace_create_packet();

        trace = trace_create("pcapfile:traces/mpls.pcap");
        iferr(trace);

        trace_start(trace);
        iferr(trace);

        /* read a packet, get its layer2 headers and test they are correct */
        trace_read_packet(trace, packet);
        libtrace_layer2_headers_t *hdr = trace_get_layer2_headers(packet);
        if (hdr != NULL) {
                trace_destroy_layer2_headers(hdr);
        }

        trace_read_packet(trace, packet);
        hdr = trace_get_layer2_headers(packet);
        if (hdr != NULL) {
                printf("Found unexpected layer2 header\n");
                trace_destroy_layer2_headers(hdr);
                error = 1;
        }

        trace_read_packet(trace, packet);
        hdr = trace_get_layer2_headers(packet);
        if (hdr == NULL) {
                printf("Was expecting to find MPLS header\n");
                error = 1;
        } else {
                if (hdr->num != 1) {
                        printf("Found unexpected number of layer2 headers\n");
                        error = 1;
                } else {
                        if ((hdr->bitmask & TRACE_BITMASK_MPLS) != TRACE_BITMASK_MPLS) {
                                printf("Found unexpected bitmask for layer2 headers\n");
                                error = 1;
                        }
                }
                trace_destroy_layer2_headers(hdr);
        }

        if (error == 0) {
                printf("success\n");
        } else {
                iferr(trace);
        }

        trace_destroy(trace);
        trace_destroy_packet(packet);

        return error;
}