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/*
Copyright (C) 2008 Free Software Foundation, Inc.
Written by Zheng Da.
This file is part of the GNU Hurd.
The GNU Hurd is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
The GNU Hurd is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with the GNU Hurd; see the file COPYING. If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
/*
* This file translates a string into a bpf program.
* The BPF structures are defined in both of bpf.h and pcap-bpf.h
* Hopefully, there is no conflict between them.
* This file uses the BPF definition in pcap-bpf.h.
*/
#include <pcap.h>
#include <stdlib.h>
#include <string.h>
#include "util.h"
#define NETF_IN 0x1
#define NETF_OUT 0x2
#define NETF_NBPA 10
#define NETF_BPF (1 << NETF_NBPA)
/* This function translates the bpf program
* from the string into the instructions. */
struct bpf_insn *trans_filter_program (char *str, int send, int *filter_len)
{
struct bpf_program program;
struct bpf_insn *insn;
pcap_t *pcap;
int err;
debug ("Compiling the bpf program: %s.\n", str);
pcap = pcap_open_dead (DLT_EN10MB, 1500);
if (pcap == NULL)
return NULL;
err = pcap_compile (pcap, &program, str, 1, 0);
if (err < 0)
{
debug ("pcap_compile: %s\n", pcap_geterr (pcap));
pcap_close (pcap);
return NULL;
}
debug ("Finish compiling the bpf program, get %d bpf instructions.\n",
program.bf_len);
insn = (struct bpf_insn *) malloc ((program.bf_len + 1) * sizeof (*insn));
/* Clear the first instruction. */
memset (insn, 0, sizeof (*insn));
if (send)
insn->code = NETF_OUT | NETF_BPF;
else
insn->code = NETF_IN | NETF_BPF;
memcpy (insn + 1, program.bf_insns, program.bf_len * sizeof (*insn));
*filter_len = ((program.bf_len + 1) * sizeof (*insn)) / sizeof (short);
debug ("%d bpf instructions, the length of filters is %d words\n",
program.bf_len, *filter_len);
pcap_freecode (&program);
pcap_close (pcap);
return insn;
}
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