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@benjojo /bpf-gen.c Secret
Created Jan 7, 2018

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/*
* BPF program compilation tool
*
* Generates decimal output, similar to `tcpdump -ddd ...`.
* Unlike tcpdump, will generate for any given link layer type.
*
* Written by Willem de Bruijn (willemb@google.com)
* Copyright Google, Inc. 2013
* Licensed under the GNU General Public License version 2 (GPLv2)
*/
#include <pcap.h>
#include <stdio.h>
int main(int argc, char **argv)
{
struct bpf_program program;
struct bpf_insn *ins;
int i, dlt = DLT_RAW;
if (argc < 2 || argc > 3) {
fprintf(stderr, "Usage: %s [link] '<program>'\n\n"
" link is a pcap linklayer type:\n"
" one of EN10MB, RAW, SLIP, ...\n\n"
"Examples: %s RAW 'tcp and greater 100'\n"
" %s EN10MB 'ip proto 47'\n'",
argv[0], argv[0], argv[0]);
return 1;
}
if (argc == 3) {
dlt = pcap_datalink_name_to_val(argv[1]);
if (dlt == -1) {
fprintf(stderr, "Unknown datalinktype: %s\n", argv[1]);
return 1;
}
}
if (pcap_compile_nopcap(65535, dlt, &program, argv[argc - 1], 1,
PCAP_NETMASK_UNKNOWN)) {
fprintf(stderr, "Compilation error\n");
return 1;
}
printf("%d,", program.bf_len);
ins = program.bf_insns;
for (i = 0; i < program.bf_len-1; ++ins, ++i)
printf("%u %u %u %u,", ins->code, ins->jt, ins->jf, ins->k);
printf("%u %u %u %u\n", ins->code, ins->jt, ins->jf, ins->k);
pcap_freecode(&program);
return 0;
}
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