src/bpfc.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * By Daniel Borkmann <daniel@netsniff-ng.org>
   4  * Copyright 2011 Daniel Borkmann <dborkma@tik.ee.ethz.ch>,
   5  * Swiss federal institute of technology (ETH Zurich)
   6  * Subject to the GPL, version 2.
   7  *
   8  * This is a tiny Berkeley Packet Filter compiler that understands the
   9  * Syntax / Semantic from the USENIX paper {"The BSD Packet Filter: A New
  10  * Architecture for User-level Packet Capture", McCanne, Steven and
  11  * Jacobson, Van, Lawrence Berkeley Laboratory}. With this, BPFs can be
  12  * written the good old way and understood by the Linux kernel and *BSD
  13  * kernels where Berkeley Packet Filters are used.
  14  *
  15  *   The one small garden of a free gardener was all his need and due, not
  16  *   a garden swollen to a realm; his own hands to use, not the hands of
  17  *   others to command.
  18  *
  19  *     -- The Lord of the Rings, Sam, Chapter 'The Tower of Cirith Ungol'.
  20  */
  21
  22 /*
  23
  24 =head1 NAME
  25
  26 bpfc - compile a BPF expression into BPF opcode
  27
  28 =head1 SYNOPSIS
  29
  30 bpfc -i|--input <program> [-V|--verbose][-v|--version][-h|--help]
  31
  32 =head1 DESCRIPTION
  33
  34 bpfc is a tool to generate BPF opcode from a literal expression.
  35 The generated BPF opcode then can be used to filter out the
  36 corresponding traffic.
  37
  38 =head1 OPTIONS
  39
  40 =over
  41
  42 =item bpfc --input example.bpf
  43
  44 Transform the literal expression in example.bpf into BPF opcodes
  45
  46 =back
  47
  48 =head1 OPTIONS
  49
  50 =over
  51
  52 =item -i|--input <program>
  53
  54 Path to Berkeley Packet Filter file.
  55
  56 =item -V|--verbose
  57
  58 Increase program verbosity
  59
  60 =item -v|--version
  61
  62 Print version.
  63
  64 =item -h|--help
  65
  66 Print help text and lists all options.
  67
  68 =back
  69
  70 =head1 AUTHOR
  71
  72 Written by Daniel Borkmann <daniel@netsniff-ng.org>
  73
  74 =head1 DOCUMENTATION
  75
  76 Documentation by Emmanuel Roullit <emmanuel@netsniff-ng.org>
  77
  78 =head1 BUGS
  79
  80 Please report bugs to <bugs@netsniff-ng.org>
  81
  82 =cut
  83
  84 */
  85
  86 #include <stdio.h>
  87 #include <stdlib.h>
  88 #include <getopt.h>
  89 #include <ctype.h>
  90
  91 #include "xmalloc.h"
  92 #include "die.h"
  93
  94 static const char *short_options = "vhi:V";
  95
  96 static struct option long_options[] = {
  97         {"input", required_argument, 0, 'i'},
  98         {"verbose", no_argument, 0, 'V'},
  99         {"version", no_argument, 0, 'v'},
 100         {"help", no_argument, 0, 'h'},
 101         {0, 0, 0, 0}
 102 };
 103
 104 extern int compile_filter(char *file, int verbose);
 105
 106 static void help(void)
 107 {
 108         printf("\nbpfc %s, a tiny BPF compiler\n", VERSION_STRING);
 109         printf("http://www.netsniff-ng.org\n\n");
 110         printf("Usage: bpfc [options] || bpfc <program>\n");
 111         printf("Options:\n");
 112         printf("  -i|--input <program>   Berkeley Packet Filter file\n");
 113         printf("  -V|--verbose           Be more verbose\n");
 114         printf("  -v|--version           Print version\n");
 115         printf("  -h|--help              Print this help\n");
 116         printf("\n");
 117         printf("Examples:\n");
 118         printf("  bpfc -i fubar.bpf\n\n");
 119         printf("Please report bugs to <bugs@netsniff-ng.org>\n");
 120         printf("Copyright (C) 2011 Daniel Borkmann <dborkma@tik.ee.ethz.ch>,\n");
 121         printf("Swiss federal institute of technology (ETH Zurich)\n");
 122         printf("License: GNU GPL version 2\n");
 123         printf("This is free software: you are free to change and redistribute it.\n");
 124         printf("There is NO WARRANTY, to the extent permitted by law.\n\n");
 125
 126         die();
 127 }
 128
 129 static void version(void)
 130 {
 131         printf("\nbpfc %s, a tiny BPF compiler\n", VERSION_STRING);
 132         printf("http://www.netsniff-ng.org\n\n");
 133         printf("Please report bugs to <bugs@netsniff-ng.org>\n");
 134         printf("Copyright (C) 2011 Daniel Borkmann <dborkma@tik.ee.ethz.ch>,\n");
 135         printf("Swiss federal institute of technology (ETH Zurich)\n");
 136         printf("License: GNU GPL version 2\n");
 137         printf("This is free software: you are free to change and redistribute it.\n");
 138         printf("There is NO WARRANTY, to the extent permitted by law.\n\n");
 139
 140         die();
 141 }
 142
 143 int main(int argc, char **argv)
 144 {
 145         int ret, verbose = 0, c, opt_index;
 146         char *file = NULL;
 147
 148         if (argc == 1)
 149                 help();
 150         while (argc > 2 && (c = getopt_long(argc, argv, short_options,
 151                 long_options, &opt_index)) != EOF) {
 152                 switch (c) {
 153                 case 'h':
 154                         help();
 155                         break;
 156                 case 'v':
 157                         version();
 158                         break;
 159                 case 'V':
 160                         verbose = 1;
 161                         break;
 162                 case 'i':
 163                         file = xstrdup(optarg);
 164                         break;
 165                 case '?':
 166                         switch (optopt) {
 167                         case 'i':
 168                                 panic("Option -%c requires an argument!\n",
 169                                       optopt);
 170                         default:
 171                                 if (isprint(optopt))
 172                                         whine("Unknown option character "
 173                                               "`0x%X\'!\n", optopt);
 174                                 die();
 175                         }
 176                 default:
 177                         break;
 178                 }
 179         }
 180         if (argc == 2)
 181                 file = xstrdup(argv[1]);
 182         if (!file)
 183                 panic("No Berkeley Packet Filter program specified!\n");
 184         ret = compile_filter(file, verbose);
 185         xfree(file);
 186
 187         return ret;
 188 }