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

   1 /* Shared library add-on to iptables to add limit support.
   2  *
   3  * Jérôme de Vivie   <devivie@info.enserb.u-bordeaux.fr>
   4  * Hervé Eychenne    <rv@wallfire.org>
   5  */
   6
   7 #include <stdio.h>
   8 #include <string.h>
   9 #include <stdlib.h>
  10 #include <getopt.h>
  11 #include <iptables.h>
  12 #include <stddef.h>
  13 #include <linux/netfilter_ipv4/ip_tables.h>
  14 /* For 64bit kernel / 32bit userspace */
  15 #include "../include/linux/netfilter_ipv4/ipt_limit.h"
  16
  17 #define IPT_LIMIT_AVG   "3/hour"
  18 #define IPT_LIMIT_BURST 5
  19
  20 /* Function which prints out usage message. */
  21 static void
  22 help(void)
  23 {
  24         printf(
  25 "limit v%s options:\n"
  26 "--limit avg                    max average match rate: default "IPT_LIMIT_AVG"\n"
  27 "                                [Packets per second unless followed by \n"
  28 "                                /sec /minute /hour /day postfixes]\n"
  29 "--limit-burst number           number to match in a burst, default %u\n"
  30 "\n", IPTABLES_VERSION, IPT_LIMIT_BURST);
  31 }
  32
  33 static struct option opts[] = {
  34         { "limit", 1, 0, '%' },
  35         { "limit-burst", 1, 0, '$' },
  36         { 0 }
  37 };
  38
  39 static
  40 int parse_rate(const char *rate, u_int32_t *val)
  41 {
  42         const char *delim;
  43         u_int32_t r;
  44         u_int32_t mult = 1;  /* Seconds by default. */
  45
  46         delim = strchr(rate, '/');
  47         if (delim) {
  48                 if (strlen(delim+1) == 0)
  49                         return 0;
  50
  51                 if (strncasecmp(delim+1, "second", strlen(delim+1)) == 0)
  52                         mult = 1;
  53                 else if (strncasecmp(delim+1, "minute", strlen(delim+1)) == 0)
  54                         mult = 60;
  55                 else if (strncasecmp(delim+1, "hour", strlen(delim+1)) == 0)
  56                         mult = 60*60;
  57                 else if (strncasecmp(delim+1, "day", strlen(delim+1)) == 0)
  58                         mult = 24*60*60;
  59                 else
  60                         return 0;
  61         }
  62         r = atoi(rate);
  63         if (!r)
  64                 return 0;
  65
  66         /* This would get mapped to infinite (1/day is minimum they
  67            can specify, so we're ok at that end). */
  68         if (r / mult > IPT_LIMIT_SCALE)
  69                 exit_error(PARAMETER_PROBLEM, "Rate too fast `%s'\n", rate);
  70
  71         *val = IPT_LIMIT_SCALE * mult / r;
  72         return 1;
  73 }
  74
  75 /* Initialize the match. */
  76 static void
  77 init(struct ipt_entry_match *m, unsigned int *nfcache)
  78 {
  79         struct ipt_rateinfo *r = (struct ipt_rateinfo *)m->data;
  80
  81         parse_rate(IPT_LIMIT_AVG, &r->avg);
  82         r->burst = IPT_LIMIT_BURST;
  83
  84 }
  85
  86 /* FIXME: handle overflow:
  87         if (r->avg*r->burst/r->burst != r->avg)
  88                 exit_error(PARAMETER_PROBLEM,
  89                            "Sorry: burst too large for that avg rate.\n");
  90 */
  91
  92 /* Function which parses command options; returns true if it
  93    ate an option */
  94 static int
  95 parse(int c, char **argv, int invert, unsigned int *flags,
  96       const struct ipt_entry *entry,
  97       unsigned int *nfcache,
  98       struct ipt_entry_match **match)
  99 {
 100         struct ipt_rateinfo *r = (struct ipt_rateinfo *)(*match)->data;
 101         unsigned int num;
 102
 103         switch(c) {
 104         case '%':
 105                 if (check_inverse(argv[optind-1], &invert, &optind, 0)) break;
 106                 if (!parse_rate(optarg, &r->avg))
 107                         exit_error(PARAMETER_PROBLEM,
 108                                    "bad rate `%s'", optarg);
 109                 break;
 110
 111         case '$':
 112                 if (check_inverse(argv[optind-1], &invert, &optind, 0)) break;
 113                 if (string_to_number(optarg, 0, 10000, &num) == -1)
 114                         exit_error(PARAMETER_PROBLEM,
 115                                    "bad --limit-burst `%s'", optarg);
 116                 r->burst = num;
 117                 break;
 118
 119         default:
 120                 return 0;
 121         }
 122
 123         if (invert)
 124                 exit_error(PARAMETER_PROBLEM,
 125                            "limit does not support invert");
 126
 127         return 1;
 128 }
 129
 130 /* Final check; nothing. */
 131 static void final_check(unsigned int flags)
 132 {
 133 }
 134
 135 static struct rates
 136 {
 137         const char *name;
 138         u_int32_t mult;
 139 } rates[] = { { "day", IPT_LIMIT_SCALE*24*60*60 },
 140               { "hour", IPT_LIMIT_SCALE*60*60 },
 141               { "min", IPT_LIMIT_SCALE*60 },
 142               { "sec", IPT_LIMIT_SCALE } };
 143
 144 static void print_rate(u_int32_t period)
 145 {
 146         unsigned int i;
 147
 148         for (i = 1; i < sizeof(rates)/sizeof(struct rates); i++) {
 149                 if (period > rates[i].mult
 150             || rates[i].mult/period < rates[i].mult%period)
 151                         break;
 152         }
 153
 154         printf("%u/%s ", rates[i-1].mult / period, rates[i-1].name);
 155 }
 156
 157 /* Prints out the matchinfo. */
 158 static void
 159 print(const struct ipt_ip *ip,
 160       const struct ipt_entry_match *match,
 161       int numeric)
 162 {
 163         struct ipt_rateinfo *r = (struct ipt_rateinfo *)match->data;
 164         printf("limit: avg "); print_rate(r->avg);
 165         printf("burst %u ", r->burst);
 166 }
 167
 168 /* FIXME: Make minimalist: only print rate if not default --RR */
 169 static void save(const struct ipt_ip *ip, const struct ipt_entry_match *match)
 170 {
 171         struct ipt_rateinfo *r = (struct ipt_rateinfo *)match->data;
 172
 173         printf("--limit "); print_rate(r->avg);
 174         if (r->burst != IPT_LIMIT_BURST)
 175                 printf("--limit-burst %u ", r->burst);
 176 }
 177
 178 static struct iptables_match limit = {
 179         .next           = NULL,
 180         .name           = "limit",
 181         .version        = IPTABLES_VERSION,
 182         .size           = IPT_ALIGN(sizeof(struct ipt_rateinfo)),
 183         .userspacesize  = offsetof(struct ipt_rateinfo, prev),
 184         .help           = &help,
 185         .init           = &init,
 186         .parse          = &parse,
 187         .final_check    = &final_check,
 188         .print          = &print,
 189         .save           = &save,
 190         .extra_opts     = opts
 191 };
 192
 193 void _init(void)
 194 {
 195         register_match(&limit);
 196 }