bpfc.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * Copyright 2011 Daniel Borkmann <dborkma@tik.ee.ethz.ch>,
   4  * Swiss federal institute of technology (ETH Zurich)
   5  * Subject to the GPL, version 2.
   6  */
   7
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <getopt.h>
  11 #include <ctype.h>
  12 #include <unistd.h>
  13 #include <sys/fsuid.h>
  14
  15 #include "xmalloc.h"
  16 #include "xutils.h"
  17 #include "die.h"
  18 #include "bpf.h"
  19
  20 static const char *short_options = "vhi:Vdbf:";
  21 static const struct option long_options[] = {
  22         {"input",       required_argument,      NULL, 'i'},
  23         {"format",      required_argument,      NULL, 'f'},
  24         {"verbose",     no_argument,            NULL, 'V'},
  25         {"bypass",      no_argument,            NULL, 'b'},
  26         {"dump",        no_argument,            NULL, 'd'},
  27         {"version",     no_argument,            NULL, 'v'},
  28         {"help",        no_argument,            NULL, 'h'},
  29         {NULL, 0, NULL, 0}
  30 };
  31
  32 extern int compile_filter(char *file, int verbose, int bypass, int format);
  33
  34 static void help(void)
  35 {
  36         printf("\nbpfc %s, a tiny BPF compiler\n", VERSION_STRING);
  37         puts("http://www.netsniff-ng.org\n\n"
  38              "Usage: bpfc [options] || bpfc <program>\n"
  39              "Options:\n"
  40              "  -i|--input <program/->  Berkeley Packet Filter file/stdin\n"
  41              "  -f|--format <format>    Output format: C|netsniff-ng|xt_bpf|tcpdump\n"
  42              "  -b|--bypass             Bypass filter validation (e.g. for bug testing)\n"
  43              "  -V|--verbose            Be more verbose\n"
  44              "  -d|--dump               Dump supported instruction table\n"
  45              "  -v|--version            Print version and exit\n"
  46              "  -h|--help               Print this help and exit\n\n"
  47              "Examples:\n"
  48              "  bpfc fubar\n"
  49              "  bpfc fubar > foo (bpfc -f C -i fubar > foo) -->  netsniff-ng -f foo ...\n"
  50              "  bpfc -f tcpdump -i fubar > foo -->  tcpdump -ddd like ...\n"
  51              "  bpfc -f xt_bpf -b -i fubar\n"
  52              "  iptables -A INPUT -m bpf --bytecode \"`./bpfc -f xt_bpf -i fubar`\" -j LOG\n"
  53              "  bpfc -   (read from stdin)\n\n"
  54              "Please report bugs to <bugs@netsniff-ng.org>\n"
  55              "Copyright (C) 2011-2013 Daniel Borkmann <dborkma@tik.ee.ethz.ch>,\n"
  56              "Swiss federal institute of technology (ETH Zurich)\n"
  57              "License: GNU GPL version 2.0\n"
  58              "This is free software: you are free to change and redistribute it.\n"
  59              "There is NO WARRANTY, to the extent permitted by law.\n");
  60         die();
  61 }
  62
  63 static void version(void)
  64 {
  65         printf("\nbpfc %s, a tiny BPF compiler\n", VERSION_STRING);
  66         puts("http://www.netsniff-ng.org\n\n"
  67              "Please report bugs to <bugs@netsniff-ng.org>\n"
  68              "Copyright (C) 2011-2013 Daniel Borkmann <dborkma@tik.ee.ethz.ch>,\n"
  69              "Swiss federal institute of technology (ETH Zurich)\n"
  70              "License: GNU GPL version 2.0\n"
  71              "This is free software: you are free to change and redistribute it.\n"
  72              "There is NO WARRANTY, to the extent permitted by law.\n");
  73         die();
  74 }
  75
  76 int main(int argc, char **argv)
  77 {
  78         int ret, verbose = 0, c, opt_index, bypass = 0, format = 0;
  79         char *file = NULL;
  80
  81         setfsuid(getuid());
  82         setfsgid(getgid());
  83
  84         if (argc == 1)
  85                 help();
  86
  87         while ((c = getopt_long(argc, argv, short_options,
  88                                 long_options, &opt_index)) != EOF) {
  89                 switch (c) {
  90                 case 'h':
  91                         help();
  92                         break;
  93                 case 'v':
  94                         version();
  95                         break;
  96                 case 'V':
  97                         verbose = 1;
  98                         break;
  99                 case 'f':
 100                         if (!strncmp(optarg, "C", 1) ||
 101                             !strncmp(optarg, "netsniff-ng", 11))
 102                                 format = 0;
 103                         else if (!strncmp(optarg, "xt_bpf", 6))
 104                                 format = 1;
 105                         else if (!strncmp(optarg, "tcpdump", 7))
 106                                 format = 2;
 107                         else
 108                                 help();
 109                         break;
 110                 case 'b':
 111                         bypass = 1;
 112                         break;
 113                 case 'd':
 114                         bpf_dump_op_table();
 115                         die();
 116                 case 'i':
 117                         file = xstrdup(optarg);
 118                         break;
 119                 case '?':
 120                         switch (optopt) {
 121                         case 'i':
 122                         case 'f':
 123                                 panic("Option -%c requires an argument!\n",
 124                                       optopt);
 125                         default:
 126                                 if (isprint(optopt))
 127                                         printf("Unknown option character `0x%X\'!\n", optopt);
 128                                 die();
 129                         }
 130                 default:
 131                         break;
 132                 }
 133         }
 134
 135         if (argc == 2)
 136                 file = xstrdup(argv[1]);
 137         if (!file)
 138                 panic("No Berkeley Packet Filter program specified!\n");
 139
 140         ret = compile_filter(file, verbose, bypass, format);
 141
 142         xfree(file);
 143         return ret;
 144 }