bpf_comp.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * Copyright 2013 Daniel Borkmann.
   4  * Subject to the GPL, version 2.
   5  */
   6
   7 #include <pcap.h>
   8 #include <linux/filter.h>
   9
  10 #include "xmalloc.h"
  11 #include "config.h"
  12 #include "bpf.h"
  13 #include "die.h"
  14
  15 void bpf_try_compile(const char *rulefile, struct sock_fprog *bpf, uint32_t link_type)
  16 {
  17         int i, ret;
  18         const struct bpf_insn *ins;
  19         struct sock_filter *out;
  20         struct bpf_program _bpf;
  21
  22         ret = pcap_compile_nopcap(65535, link_type, &_bpf, rulefile, 1, 0xffffffff);
  23         if (ret < 0)
  24                 panic("Cannot compile filter %s\n", rulefile);
  25
  26         bpf->len = _bpf.bf_len;
  27         bpf->filter = xrealloc(bpf->filter, 1, bpf->len * sizeof(*out));
  28
  29         for (i = 0, ins = _bpf.bf_insns, out = bpf->filter; i < bpf->len;
  30              ++i, ++ins, ++out) {
  31                 out->code = ins->code;
  32                 out->jt = ins->jt;
  33                 out->jf = ins->jf;
  34                 out->k = ins->k;
  35
  36                 if (out->code == 0x06 && out->k > 0)
  37                         out->k = 0xFFFFFFFF;
  38         }
  39
  40         pcap_freecode(&_bpf);
  41
  42         if (__bpf_validate(bpf) == 0)
  43                 panic("This is not a valid BPF program!\n");
  44 }