release/src/router/iptables/extensions/libip6t_nth.c

   1 /*
   2    Shared library add-on to iptables to add match support for every Nth packet
   3
   4    This file is distributed under the terms of the GNU General Public
   5    License (GPL). Copies of the GPL can be obtained from:
   6    ftp://prep.ai.mit.edu/pub/gnu/GPL
   7
   8    2001-07-17 Fabrice MARIE <fabrice@netfilter.org> : initial development.
   9    2001-09-20 Richard Wagner (rwagner@cloudnet.com)
  10         * added support for multiple counters
  11         * added support for matching on individual packets
  12           in the counter cycle
  13 */
  14
  15 #include <stdio.h>
  16 #include <netdb.h>
  17 #include <string.h>
  18 #include <stdlib.h>
  19 #include <syslog.h>
  20 #include <getopt.h>
  21 #include <ip6tables.h>
  22 #include <linux/netfilter_ipv6/ip6_tables.h>
  23 #include <linux/netfilter_ipv6/ip6t_nth.h>
  24
  25
  26 /* Function which prints out usage message. */
  27 static void
  28 help(void)
  29 {
  30         printf(
  31 "nth v%s options:\n"
  32 "   --every     Nth              Match every Nth packet\n"
  33 "  [--counter]  num              Use counter 0-%u (default:0)\n"
  34 "  [--start]    num              Initialize the counter at the number 'num'\n"
  35 "                                instead of 0. Must be between 0 and Nth-1\n"
  36 "  [--packet]   num              Match on 'num' packet. Must be between 0\n"
  37 "                                and Nth-1.\n\n"
  38 "                                If --packet is used for a counter than\n"
  39 "                                there must be Nth number of --packet\n"
  40 "                                rules, covering all values between 0 and\n"
  41 "                                Nth-1 inclusively.\n",
  42 IPTABLES_VERSION, IP6T_NTH_NUM_COUNTERS-1);
  43 }
  44
  45 static struct option opts[] = {
  46         { "every", 1, 0, '1' },
  47         { "start", 1, 0, '2' },
  48         { "counter", 1, 0, '3' },
  49         { "packet", 1, 0, '4' },
  50         { 0 }
  51 };
  52
  53 #define IP6T_NTH_OPT_EVERY      0x01
  54 #define IP6T_NTH_OPT_NOT_EVERY  0x02
  55 #define IP6T_NTH_OPT_START      0x04
  56 #define IP6T_NTH_OPT_COUNTER     0x08
  57 #define IP6T_NTH_OPT_PACKET      0x10
  58
  59 /* Function which parses command options; returns true if it
  60    ate an option */
  61 static int
  62 parse(int c, char **argv, int invert, unsigned int *flags,
  63       const struct ip6t_entry *entry,
  64       unsigned int *nfcache,
  65       struct ip6t_entry_match **match)
  66 {
  67         struct ip6t_nth_info *nthinfo = (struct ip6t_nth_info *)(*match)->data;
  68         unsigned int num;
  69
  70         switch (c) {
  71         case '1':
  72                 /* check for common mistakes... */
  73                 if ((!invert) && (*flags & IP6T_NTH_OPT_EVERY))
  74                         exit_error(PARAMETER_PROBLEM,
  75                                    "Can't specify --every twice");
  76                 if (invert && (*flags & IP6T_NTH_OPT_NOT_EVERY))
  77                         exit_error(PARAMETER_PROBLEM,
  78                                    "Can't specify ! --every twice");
  79                 if ((!invert) && (*flags & IP6T_NTH_OPT_NOT_EVERY))
  80                         exit_error(PARAMETER_PROBLEM,
  81                                    "Can't specify --every with ! --every");
  82                 if (invert && (*flags & IP6T_NTH_OPT_EVERY))
  83                         exit_error(PARAMETER_PROBLEM,
  84                                    "Can't specify ! --every with --every");
  85
  86                 /* Remember, this function will interpret a leading 0 to be
  87                    Octal, a leading 0x to be hexdecimal... */
  88                 if (string_to_number(optarg, 2, 100, &num) == -1 || num < 2)
  89                         exit_error(PARAMETER_PROBLEM,
  90                                    "bad --every `%s', must be between 2 and 100", optarg);
  91
  92                 /* assign the values */
  93                 nthinfo->every = num-1;
  94                 nthinfo->startat = 0;
  95                 nthinfo->packet = 0xFF;
  96                 if(!(*flags & IP6T_NTH_OPT_EVERY))
  97                 {
  98                         nthinfo->counter = 0;
  99                 }
 100                 if (invert)
 101                 {
 102                         *flags |= IP6T_NTH_OPT_NOT_EVERY;
 103                         nthinfo->not = 1;
 104                 }
 105                 else
 106                 {
 107                         *flags |= IP6T_NTH_OPT_EVERY;
 108                         nthinfo->not = 0;
 109                 }
 110                 break;
 111         case '2':
 112                 /* check for common mistakes... */
 113                 if (!((*flags & IP6T_NTH_OPT_EVERY) ||
 114                       (*flags & IP6T_NTH_OPT_NOT_EVERY)))
 115                         exit_error(PARAMETER_PROBLEM,
 116                                    "Can't specify --start before --every");
 117                 if (invert)
 118                         exit_error(PARAMETER_PROBLEM,
 119                                    "Can't specify with ! --start");
 120                 if (*flags & IP6T_NTH_OPT_START)
 121                         exit_error(PARAMETER_PROBLEM,
 122                                    "Can't specify --start twice");
 123                 if (string_to_number(optarg, 0, nthinfo->every, &num) == -1)
 124                         exit_error(PARAMETER_PROBLEM,
 125                                    "bad --start `%s', must between 0 and %u", optarg, nthinfo->every);
 126                 *flags |= IP6T_NTH_OPT_START;
 127                 nthinfo->startat = num;
 128                 break;
 129         case '3':
 130                 /* check for common mistakes... */
 131                 if (invert)
 132                         exit_error(PARAMETER_PROBLEM,
 133                                    "Can't specify with ! --counter");
 134                 if (*flags & IP6T_NTH_OPT_COUNTER)
 135                         exit_error(PARAMETER_PROBLEM,
 136                                    "Can't specify --counter twice");
 137                 if (string_to_number(optarg, 0, IP6T_NTH_NUM_COUNTERS-1, &num) == -1)
 138                         exit_error(PARAMETER_PROBLEM,
 139                                    "bad --counter `%s', must between 0 and %u", optarg, IP6T_NTH_NUM_COUNTERS-1);
 140                 /* assign the values */
 141                 *flags |= IP6T_NTH_OPT_COUNTER;
 142                 nthinfo->counter = num;
 143                 break;
 144         case '4':
 145                 /* check for common mistakes... */
 146                 if (!((*flags & IP6T_NTH_OPT_EVERY) ||
 147                       (*flags & IP6T_NTH_OPT_NOT_EVERY)))
 148                         exit_error(PARAMETER_PROBLEM,
 149                                    "Can't specify --packet before --every");
 150                 if ((*flags & IP6T_NTH_OPT_NOT_EVERY))
 151                         exit_error(PARAMETER_PROBLEM,
 152                                    "Can't specify --packet with ! --every");
 153                 if (invert)
 154                         exit_error(PARAMETER_PROBLEM,
 155                                    "Can't specify with ! --packet");
 156                 if (*flags & IP6T_NTH_OPT_PACKET)
 157                         exit_error(PARAMETER_PROBLEM,
 158                                    "Can't specify --packet twice");
 159                 if (string_to_number(optarg, 0, nthinfo->every, &num) == -1)
 160                         exit_error(PARAMETER_PROBLEM,
 161                                    "bad --packet `%s', must between 0 and %u", optarg, nthinfo->every);
 162                 *flags |= IP6T_NTH_OPT_PACKET;
 163                 nthinfo->packet = num;
 164                 break;
 165         default:
 166                 return 0;
 167         }
 168         return 1;
 169 }
 170
 171 /* Final check; nothing. */
 172 static void final_check(unsigned int flags)
 173 {
 174 }
 175
 176 /* Prints out the targinfo. */
 177 static void
 178 print(const struct ip6t_ip6 *ip,
 179       const struct ip6t_entry_match *match,
 180       int numeric)
 181 {
 182         const struct ip6t_nth_info *nthinfo
 183                 = (const struct ip6t_nth_info *)match->data;
 184
 185         if (nthinfo->not == 1)
 186                 printf(" !");
 187         printf("every %uth ", (nthinfo->every +1));
 188         if (nthinfo->counter != 0)
 189                 printf("counter #%u ", (nthinfo->counter));
 190         if (nthinfo->packet != 0xFF)
 191                 printf("packet #%u ", nthinfo->packet);
 192         if (nthinfo->startat != 0)
 193                 printf("start at %u ", nthinfo->startat);
 194 }
 195
 196 /* Saves the union ip6t_targinfo in parsable form to stdout. */
 197 static void
 198 save(const struct ip6t_ip6 *ip, const struct ip6t_entry_match *match)
 199 {
 200         const struct ip6t_nth_info *nthinfo
 201                 = (const struct ip6t_nth_info *)match->data;
 202
 203         if (nthinfo->not == 1)
 204                 printf("! ");
 205         printf("--every %u ", (nthinfo->every +1));
 206         printf("--counter %u ", (nthinfo->counter));
 207         if (nthinfo->startat != 0)
 208                 printf("--start %u ", nthinfo->startat );
 209         if (nthinfo->packet != 0xFF)
 210                 printf("--packet %u ", nthinfo->packet );
 211 }
 212
 213 struct ip6tables_match nth = {
 214         .name           = "nth",
 215         .version        = IPTABLES_VERSION,
 216         .size           = IP6T_ALIGN(sizeof(struct ip6t_nth_info)),
 217         .userspacesize  = IP6T_ALIGN(sizeof(struct ip6t_nth_info)),
 218         .help           = &help,
 219         .parse          = &parse,
 220         .final_check    = &final_check,
 221         .print          = &print,
 222         .save           = &save,
 223         .extra_opts     = opts,
 224 };
 225
 226 void _init(void)
 227 {
 228         register_match6(&nth);
 229 }