53 lines
1.2 KiB
C
Executable file
53 lines
1.2 KiB
C
Executable file
/*
|
|
* Minimal BPF assembler
|
|
*
|
|
* Instead of libpcap high-level filter expressions, it can be quite
|
|
* useful to define filters in low-level BPF assembler (that is kept
|
|
* close to Steven McCanne and Van Jacobson's original BPF paper).
|
|
* In particular for BPF JIT implementors, JIT security auditors, or
|
|
* just for defining BPF expressions that contain extensions which are
|
|
* not supported by compilers.
|
|
*
|
|
* How to get into it:
|
|
*
|
|
* 1) read Documentation/networking/filter.txt
|
|
* 2) Run `bpf_asm [-c] <filter-prog file>` to translate into binary
|
|
* blob that is loadable with xt_bpf, cls_bpf et al. Note: -c will
|
|
* pretty print a C-like construct.
|
|
*
|
|
* Copyright 2013 Daniel Borkmann <borkmann@redhat.com>
|
|
* Licensed under the GNU General Public License, version 2.0 (GPLv2)
|
|
*/
|
|
|
|
#include <stdbool.h>
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
|
|
extern void bpf_asm_compile(FILE *fp, bool cstyle);
|
|
|
|
int main(int argc, char **argv)
|
|
{
|
|
FILE *fp = stdin;
|
|
bool cstyle = false;
|
|
int i;
|
|
|
|
for (i = 1; i < argc; i++) {
|
|
if (!strncmp("-c", argv[i], 2)) {
|
|
cstyle = true;
|
|
continue;
|
|
}
|
|
|
|
fp = fopen(argv[i], "r");
|
|
if (!fp) {
|
|
fp = stdin;
|
|
continue;
|
|
}
|
|
|
|
break;
|
|
}
|
|
|
|
bpf_asm_compile(fp, cstyle);
|
|
|
|
return 0;
|
|
}
|