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 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <getopt.h>
  25 #include <ctype.h>
  26 #include <unistd.h>
  27 #include <sys/fsuid.h>
  28
  29 #include "xmalloc.h"
  30 #include "xutils.h"
  31 #include "die.h"
  32 #include "bpf.h"
  33
  34 static const char *short_options = "vhi:Vdb";
  35 static const struct option long_options[] = {
  36         {"input",       required_argument,      NULL, 'i'},
  37         {"verbose",     no_argument,            NULL, 'V'},
  38         {"bypass",      no_argument,            NULL, 'b'},
  39         {"dump",        no_argument,            NULL, 'd'},
  40         {"version",     no_argument,            NULL, 'v'},
  41         {"help",        no_argument,            NULL, 'h'},
  42         {NULL, 0, NULL, 0}
  43 };
  44
  45 extern int compile_filter(char *file, int verbose, int bypass);
  46
  47 static void help(void)
  48 {
  49         printf("\nbpfc %s, a tiny BPF compiler\n", VERSION_STRING);
  50         puts("http://www.netsniff-ng.org\n\n"
  51              "Usage: bpfc [options] || bpfc <program>\n"
  52              "Options:\n"
  53              "  -i|--input <program/->  Berkeley Packet Filter file/stdin\n"
  54              "  -V|--verbose            Be more verbose\n"
  55              "  -b|--bypass             Bypass filter validation (e.g. for bug testing)\n"
  56              "  -d|--dump               Dump supported instruction table\n"
  57              "  -v|--version            Print version\n"
  58              "  -h|--help               Print this help\n\n"
  59              "Examples:\n"
  60              "  bpfc fubar\n"
  61              "  bpfc -bi fubar\n"
  62              "  bpfc -   (read from stdin)\n\n"
  63              "Please report bugs to <bugs@netsniff-ng.org>\n"
  64              "Copyright (C) 2011-2013 Daniel Borkmann <dborkma@tik.ee.ethz.ch>,\n"
  65              "Swiss federal institute of technology (ETH Zurich)\n"
  66              "License: GNU GPL version 2.0\n"
  67              "This is free software: you are free to change and redistribute it.\n"
  68              "There is NO WARRANTY, to the extent permitted by law.\n");
  69         die();
  70 }
  71
  72 static void version(void)
  73 {
  74         printf("\nbpfc %s, a tiny BPF compiler\n", VERSION_STRING);
  75         puts("http://www.netsniff-ng.org\n\n"
  76              "Please report bugs to <bugs@netsniff-ng.org>\n"
  77              "Copyright (C) 2011-2013 Daniel Borkmann <dborkma@tik.ee.ethz.ch>,\n"
  78              "Swiss federal institute of technology (ETH Zurich)\n"
  79              "License: GNU GPL version 2.0\n"
  80              "This is free software: you are free to change and redistribute it.\n"
  81              "There is NO WARRANTY, to the extent permitted by law.\n");
  82         die();
  83 }
  84
  85 int main(int argc, char **argv)
  86 {
  87         int ret, verbose = 0, c, opt_index, bypass = 0;
  88         char *file = NULL;
  89
  90         setfsuid(getuid());
  91         setfsgid(getgid());
  92
  93         if (argc == 1)
  94                 help();
  95
  96         while ((c = getopt_long(argc, argv, short_options,
  97                                 long_options, &opt_index)) != EOF) {
  98                 switch (c) {
  99                 case 'h':
 100                         help();
 101                         break;
 102                 case 'v':
 103                         version();
 104                         break;
 105                 case 'V':
 106                         verbose = 1;
 107                         break;
 108                 case 'b':
 109                         bypass = 1;
 110                         break;
 111                 case 'd':
 112                         bpf_dump_op_table();
 113                         die();
 114                 case 'i':
 115                         file = xstrdup(optarg);
 116                         break;
 117                 case '?':
 118                         switch (optopt) {
 119                         case 'i':
 120                                 panic("Option -%c requires an argument!\n",
 121                                       optopt);
 122                         default:
 123                                 if (isprint(optopt))
 124                                         printf("Unknown option character `0x%X\'!\n", optopt);
 125                                 die();
 126                         }
 127                 default:
 128                         break;
 129                 }
 130         }
 131
 132         if (argc == 2)
 133                 file = xstrdup(argv[1]);
 134         if (!file)
 135                 panic("No Berkeley Packet Filter program specified!\n");
 136
 137         ret = compile_filter(file, verbose, bypass);
 138
 139         xfree(file);
 140         return ret;
 141 }