/*
 * to compile type:
 * gcc -lpcap bpf_comp.c -o bpf_comp
 */
 
#include <err.h>
#include <pcap.h>
#include <stdio.h>
#include <sysexits.h>
 
int main(int argc, char *argv[])
 
{
        struct bpf_program bp;
        unsigned int i;
 
        if (argc != 2)
                errx(EX_USAGE, "Usage %s 'filter expression'", argv[0]);
 
        if(pcap_compile_nopcap(65535, DLT_RAW, &bp, argv[1], 1, 0)) {
                errx(EX_USAGE, "filter syntax error");
        }
 
        printf("bpf_prog_len=%d bpf_prog=[ ", bp.bf_len);
 
        for (i = 0; i < bp.bf_len; i ++) {
                printf("{ code=%d jt=%d jf=%d k=%d } ",
                        bp.bf_insns[i].code, bp.bf_insns[i].jt, bp.bf_insns[i].jf, bp.bf_insns[i].k);
        }
 
        printf("]\n");
 
        return 0;
}