extensions/libipt_statistic.c

   1 #include <stdio.h>
   2 #include <netdb.h>
   3 #include <string.h>
   4 #include <stdlib.h>
   5 #include <stddef.h>
   6 #include <getopt.h>
   7
   8 #include <iptables.h>
   9 #include <linux/netfilter/xt_statistic.h>
  10
  11 static void
  12 help(void)
  13 {
  14         printf(
  15 "statistic match v%s options:\n"
  16 " --mode mode                    Match mode (random, nth)\n"
  17 " random mode:\n"
  18 " --probability p                Probability\n"
  19 " nth mode:\n"
  20 " --every n                      Match every nth packet\n"
  21 " --packet p                     Initial counter value (0 <= p <= n-1, default 0)\n"
  22 "\n",
  23 IPTABLES_VERSION);
  24 }
  25
  26 static struct option opts[] = {
  27         { "mode", 1, 0, '1' },
  28         { "probability", 1, 0, '2' },
  29         { "every", 1, 0, '3' },
  30         { "packet", 1, 0, '4' },
  31         { 0 }
  32 };
  33
  34 static struct xt_statistic_info *info;
  35
  36 static int
  37 parse(int c, char **argv, int invert, unsigned int *flags,
  38       const struct ipt_entry *entry,
  39       unsigned int *nfcache,
  40       struct ipt_entry_match **match)
  41 {
  42         double prob;
  43
  44         info = (void *)(*match)->data;
  45
  46         if (invert)
  47                 info->flags |= XT_STATISTIC_INVERT;
  48
  49         switch (c) {
  50         case '1':
  51                 if (*flags & 0x1)
  52                         exit_error(PARAMETER_PROBLEM, "double --mode");
  53                 if (!strcmp(optarg, "random"))
  54                         info->mode = XT_STATISTIC_MODE_RANDOM;
  55                 else if (!strcmp(optarg, "nth"))
  56                         info->mode = XT_STATISTIC_MODE_NTH;
  57                 else
  58                         exit_error(PARAMETER_PROBLEM, "Bad mode `%s'", optarg);
  59                 *flags |= 0x1;
  60                 break;
  61         case '2':
  62                 if (*flags & 0x2)
  63                         exit_error(PARAMETER_PROBLEM, "double --probability");
  64                 prob = atof(optarg);
  65                 if (prob < 0 || prob > 1)
  66                         exit_error(PARAMETER_PROBLEM,
  67                                    "--probability must be between 0 and 1");
  68                 info->u.random.probability = 0x80000000 * prob;
  69                 *flags |= 0x2;
  70                 break;
  71         case '3':
  72                 if (*flags & 0x4)
  73                         exit_error(PARAMETER_PROBLEM, "double --every");
  74                 if (string_to_number(optarg, 0, 0xFFFFFFFF,
  75                                      &info->u.nth.every) == -1)
  76                         exit_error(PARAMETER_PROBLEM,
  77                                    "cannot parse --every `%s'", optarg);
  78                 if (info->u.nth.every == 0)
  79                         exit_error(PARAMETER_PROBLEM, "--every cannot be 0");
  80                 info->u.nth.every--;
  81                 *flags |= 0x4;
  82                 break;
  83         case '4':
  84                 if (*flags & 0x8)
  85                         exit_error(PARAMETER_PROBLEM, "double --packet");
  86                 if (string_to_number(optarg, 0, 0xFFFFFFFF,
  87                                      &info->u.nth.packet) == -1)
  88                         exit_error(PARAMETER_PROBLEM,
  89                                    "cannot parse --packet `%s'", optarg);
  90                 *flags |= 0x8;
  91                 break;
  92         default:
  93                 return 0;
  94         }
  95         return 1;
  96 }
  97
  98 /* Final check; must have specified --mark. */
  99 static void
 100 final_check(unsigned int flags)
 101 {
 102         if (!(flags & 0x1))
 103                 exit_error(PARAMETER_PROBLEM, "no mode specified");
 104         if ((flags & 0x2) && (flags & (0x4 | 0x8)))
 105                 exit_error(PARAMETER_PROBLEM,
 106                            "both nth and random parameters given");
 107         if (flags & 0x2 && info->mode != XT_STATISTIC_MODE_RANDOM)
 108                 exit_error(PARAMETER_PROBLEM,
 109                            "--probability can only be used in random mode");
 110         if (flags & 0x4 && info->mode != XT_STATISTIC_MODE_NTH)
 111                 exit_error(PARAMETER_PROBLEM,
 112                            "--every can only be used in nth mode");
 113         if (flags & 0x8 && info->mode != XT_STATISTIC_MODE_NTH)
 114                 exit_error(PARAMETER_PROBLEM,
 115                            "--packet can only be used in nth mode");
 116         info->u.nth.count = info->u.nth.every - info->u.nth.packet;
 117 }
 118
 119 /* Prints out the matchinfo. */
 120 static void print_match(const struct xt_statistic_info *info, char *prefix)
 121 {
 122         if (info->flags & XT_STATISTIC_INVERT)
 123                 printf("! ");
 124
 125         switch (info->mode) {
 126         case XT_STATISTIC_MODE_RANDOM:
 127                 printf("%smode random %sprobability %f ", prefix, prefix,
 128                        1.0 * info->u.random.probability / 0x80000000);
 129                 break;
 130         case XT_STATISTIC_MODE_NTH:
 131                 printf("%smode nth %severy %u ", prefix, prefix,
 132                        info->u.nth.every + 1);
 133                 if (info->u.nth.packet)
 134                         printf("%spacket %u ", prefix, info->u.nth.packet);
 135                 break;
 136         }
 137 }
 138
 139 static void
 140 print(const struct ipt_ip *ip,
 141       const struct ipt_entry_match *match,
 142       int numeric)
 143 {
 144         struct xt_statistic_info *info = (struct xt_statistic_info *)match->data;
 145
 146         printf("statistic ");
 147         print_match(info, "");
 148 }
 149
 150 /* Saves the union ipt_matchinfo in parsable form to stdout. */
 151 static void
 152 save(const struct ipt_ip *ip, const struct ipt_entry_match *match)
 153 {
 154         struct xt_statistic_info *info = (struct xt_statistic_info *)match->data;
 155
 156         print_match(info, "--");
 157 }
 158
 159 static struct iptables_match statistic = {
 160         .name           = "statistic",
 161         .version        = IPTABLES_VERSION,
 162         .size           = IPT_ALIGN(sizeof(struct xt_statistic_info)),
 163         .userspacesize  = offsetof(struct xt_statistic_info, u.nth.count),
 164         .help           = help,
 165         .parse          = parse,
 166         .final_check    = final_check,
 167         .print          = print,
 168         .save           = save,
 169         .extra_opts     = opts
 170 };
 171
 172 void _init(void)
 173 {
 174         register_match(&statistic);
 175 }