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 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <getopt.h>
  25 #include <ctype.h>
  26 #include <unistd.h>
  27
  28 #include "xmalloc.h"
  29 #include "xutils.h"
  30 #include "die.h"
  31 #include "bpf.h"
  32
  33 static const char *short_options = "vhi:VdbHLg";
  34 static const struct option long_options[] = {
  35         {"input",       required_argument,      NULL, 'i'},
  36         {"verbose",     no_argument,            NULL, 'V'},
  37         {"hla",         no_argument,            NULL, 'H'},
  38         {"lla",         no_argument,            NULL, 'L'},
  39         {"hla-debug",   no_argument,            NULL, 'g'},
  40         {"bypass",      no_argument,            NULL, 'b'},
  41         {"dump",        no_argument,            NULL, 'd'},
  42         {"version",     no_argument,            NULL, 'v'},
  43         {"help",        no_argument,            NULL, 'h'},
  44         {NULL, 0, NULL, 0}
  45 };
  46
  47 extern int compile_filter(char *file, int verbose, int bypass);
  48 extern int compile_hla_filter(char *file, int verbose, int debug);
  49
  50 static void help(void)
  51 {
  52         printf("\n%s %s, a tiny BPF compiler\n",
  53                PROGNAME_STRING, VERSION_STRING);
  54         puts("http://www.netsniff-ng.org\n\n"
  55              "Usage: bpfc [options] || bpfc <program>\n"
  56              "Options:\n"
  57              "  -i|--input <program/-> Berkeley Packet Filter file/stdin\n"
  58              "  -H|--hla               Compile high-level BPF\n"
  59              "  -L|--lla               Compile low-level BPF\n"
  60              "  -V|--verbose           Be more verbose\n"
  61              "  -b|--bypass            Bypass filter validation (e.g. for bug testing)\n"
  62              "  -g|--hla-debug         Print BPF expressions to stdout\n"
  63              "  -d|--dump              Dump supported instruction table\n"
  64              "  -v|--version           Print version\n"
  65              "  -h|--help              Print this help\n\n"
  66              "Examples:\n"
  67              "  bpfc -Hi fubar\n"
  68              "  bpfc -Hgi fubar\n"
  69              "  bpfc -Li fubar\n"
  70              "  bpfc -Lbi fubar\n"
  71              "  bpfc -Li -    (read from stdin)\n\n"
  72              "Please report bugs to <bugs@netsniff-ng.org>\n"
  73              "Copyright (C) 2011-2012 Daniel Borkmann <dborkma@tik.ee.ethz.ch>,\n"
  74              "Swiss federal institute of technology (ETH Zurich)\n"
  75              "License: GNU GPL version 2.0\n"
  76              "This is free software: you are free to change and redistribute it.\n"
  77              "There is NO WARRANTY, to the extent permitted by law.\n");
  78         die();
  79 }
  80
  81 static void version(void)
  82 {
  83         printf("\n%s %s, a tiny BPF compiler\n",
  84                PROGNAME_STRING, VERSION_STRING);
  85         puts("http://www.netsniff-ng.org\n\n"
  86              "Please report bugs to <bugs@netsniff-ng.org>\n"
  87              "Copyright (C) 2011-2012 Daniel Borkmann <dborkma@tik.ee.ethz.ch>,\n"
  88              "Swiss federal institute of technology (ETH Zurich)\n"
  89              "License: GNU GPL version 2.0\n"
  90              "This is free software: you are free to change and redistribute it.\n"
  91              "There is NO WARRANTY, to the extent permitted by law.\n");
  92         die();
  93 }
  94
  95 int main(int argc, char **argv)
  96 {
  97         int ret, verbose = 0, c, opt_index, bypass = 0, hla = 0, debug = 0;
  98         char *file = NULL;
  99
 100         if (argc == 1)
 101                 help();
 102
 103         while ((c = getopt_long(argc, argv, short_options,
 104                                 long_options, &opt_index)) != EOF) {
 105                 switch (c) {
 106                 case 'h':
 107                         help();
 108                         break;
 109                 case 'v':
 110                         version();
 111                         break;
 112                 case 'H':
 113                         hla = 1;
 114                         break;
 115                 case 'L':
 116                         hla = 0;
 117                         break;
 118                 case 'g':
 119                         debug = 1;
 120                         break;
 121                 case 'V':
 122                         verbose = 1;
 123                         break;
 124                 case 'b':
 125                         bypass = 1;
 126                         break;
 127                 case 'd':
 128                         bpf_dump_op_table();
 129                         die();
 130                 case 'i':
 131                         file = xstrdup(optarg);
 132                         break;
 133                 case '?':
 134                         switch (optopt) {
 135                         case 'i':
 136                                 panic("Option -%c requires an argument!\n",
 137                                       optopt);
 138                         default:
 139                                 if (isprint(optopt))
 140                                         whine("Unknown option character "
 141                                               "`0x%X\'!\n", optopt);
 142                                 die();
 143                         }
 144                 default:
 145                         break;
 146                 }
 147         }
 148         if (argc == 2)
 149                 file = xstrdup(argv[1]);
 150
 151         if (!file)
 152                 panic("No Berkeley Packet Filter program specified!\n");
 153
 154         if (hla) {
 155                 ret = compile_hla_filter(file, verbose, debug);
 156                 if (!ret) {
 157                         char file_tmp[128];
 158
 159                         slprintf(file_tmp, sizeof(file_tmp), ".%s", file);
 160                         ret = compile_filter(file_tmp, verbose, bypass);
 161                         unlink(file_tmp);
 162                 }
 163         } else {
 164                 ret = compile_filter(file, verbose, bypass);
 165         }
 166
 167         xfree(file);
 168         return ret;
 169 }