1 /* 2 * Copyright (c) 2006-2013 Patrick McHardy <kaber (at) trash.net> 3 */ 4 5 #include <math.h> 6 #include <stdio.h> 7 #include <string.h> 8 #include <xtables.h> 9 #include <linux/netfilter/xt_statistic.h> 10 11 enum { 12 O_MODE = 0, 13 O_PROBABILITY, 14 O_EVERY, 15 O_PACKET, 16 F_PROBABILITY = 1 << O_PROBABILITY, 17 F_EVERY = 1 << O_EVERY, 18 F_PACKET = 1 << O_PACKET, 19 }; 20 21 static void statistic_help(void) 22 { 23 printf( 24 "statistic match options:\n" 25 " --mode mode Match mode (random, nth)\n" 26 " random mode:\n" 27 "[!] --probability p Probability\n" 28 " nth mode:\n" 29 "[!] --every n Match every nth packet\n" 30 " --packet p Initial counter value (0 <= p <= n-1, default 0)\n"); 31 } 32 33 #define s struct xt_statistic_info 34 static const struct xt_option_entry statistic_opts[] = { 35 {.name = "mode", .id = O_MODE, .type = XTTYPE_STRING, 36 .flags = XTOPT_MAND}, 37 {.name = "probability", .id = O_PROBABILITY, .type = XTTYPE_DOUBLE, 38 .flags = XTOPT_INVERT, .min = 0, .max = 1, 39 .excl = F_EVERY | F_PACKET}, 40 {.name = "every", .id = O_EVERY, .type = XTTYPE_UINT32, .min = 1, 41 .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, u.nth.every), 42 .excl = F_PROBABILITY, .also = F_PACKET}, 43 {.name = "packet", .id = O_PACKET, .type = XTTYPE_UINT32, 44 .flags = XTOPT_PUT, XTOPT_POINTER(s, u.nth.packet), 45 .excl = F_PROBABILITY, .also = F_EVERY}, 46 XTOPT_TABLEEND, 47 }; 48 #undef s 49 50 static void statistic_parse(struct xt_option_call *cb) 51 { 52 struct xt_statistic_info *info = cb->data; 53 54 if (cb->invert) 55 info->flags |= XT_STATISTIC_INVERT; 56 57 xtables_option_parse(cb); 58 switch (cb->entry->id) { 59 case O_MODE: 60 if (strcmp(cb->arg, "random") == 0) 61 info->mode = XT_STATISTIC_MODE_RANDOM; 62 else if (strcmp(cb->arg, "nth") == 0) 63 info->mode = XT_STATISTIC_MODE_NTH; 64 else 65 xtables_error(PARAMETER_PROBLEM, "Bad mode \"%s\"", 66 cb->arg); 67 break; 68 case O_PROBABILITY: 69 info->u.random.probability = lround(0x80000000 * cb->val.dbl); 70 break; 71 case O_EVERY: 72 --info->u.nth.every; 73 break; 74 } 75 } 76 77 static void statistic_check(struct xt_fcheck_call *cb) 78 { 79 struct xt_statistic_info *info = cb->data; 80 81 if (info->mode == XT_STATISTIC_MODE_RANDOM && 82 !(cb->xflags & F_PROBABILITY)) 83 xtables_error(PARAMETER_PROBLEM, 84 "--probability must be specified when using " 85 "random mode"); 86 if (info->mode == XT_STATISTIC_MODE_NTH && 87 !(cb->xflags & (F_EVERY | F_PACKET))) 88 xtables_error(PARAMETER_PROBLEM, 89 "--every and --packet must be specified when " 90 "using nth mode"); 91 92 /* at this point, info->u.nth.every have been decreased. */ 93 if (info->u.nth.packet > info->u.nth.every) 94 xtables_error(PARAMETER_PROBLEM, 95 "the --packet p must be 0 <= p <= n-1"); 96 97 info->u.nth.count = info->u.nth.every - info->u.nth.packet; 98 } 99 100 static void print_match(const struct xt_statistic_info *info, char *prefix) 101 { 102 switch (info->mode) { 103 case XT_STATISTIC_MODE_RANDOM: 104 printf(" %smode random%s %sprobability %.11f", prefix, 105 (info->flags & XT_STATISTIC_INVERT) ? " !" : "", 106 prefix, 107 1.0 * info->u.random.probability / 0x80000000); 108 break; 109 case XT_STATISTIC_MODE_NTH: 110 printf(" %smode nth%s %severy %u", prefix, 111 (info->flags & XT_STATISTIC_INVERT) ? " !" : "", 112 prefix, 113 info->u.nth.every + 1); 114 if (info->u.nth.packet || *prefix) 115 printf(" %spacket %u", prefix, info->u.nth.packet); 116 break; 117 } 118 } 119 120 static void 121 statistic_print(const void *ip, const struct xt_entry_match *match, int numeric) 122 { 123 const struct xt_statistic_info *info = (const void *)match->data; 124 125 printf(" statistic"); 126 print_match(info, ""); 127 } 128 129 static void statistic_save(const void *ip, const struct xt_entry_match *match) 130 { 131 const struct xt_statistic_info *info = (const void *)match->data; 132 133 print_match(info, "--"); 134 } 135 136 static int statistic_xlate(struct xt_xlate *xl, 137 const struct xt_xlate_mt_params *params) 138 { 139 const struct xt_statistic_info *info = 140 (struct xt_statistic_info *)params->match->data; 141 142 switch (info->mode) { 143 case XT_STATISTIC_MODE_RANDOM: 144 return 0; 145 case XT_STATISTIC_MODE_NTH: 146 xt_xlate_add(xl, "numgen inc mod %u %s%u", 147 info->u.nth.every + 1, 148 info->flags & XT_STATISTIC_INVERT ? "!= " : "", 149 info->u.nth.packet); 150 break; 151 } 152 153 return 1; 154 } 155 156 static struct xtables_match statistic_match = { 157 .family = NFPROTO_UNSPEC, 158 .name = "statistic", 159 .version = XTABLES_VERSION, 160 .size = XT_ALIGN(sizeof(struct xt_statistic_info)), 161 .userspacesize = offsetof(struct xt_statistic_info, u.nth.count), 162 .help = statistic_help, 163 .x6_parse = statistic_parse, 164 .x6_fcheck = statistic_check, 165 .print = statistic_print, 166 .save = statistic_save, 167 .x6_options = statistic_opts, 168 .xlate = statistic_xlate, 169 }; 170 171 void _init(void) 172 { 173 xtables_register_match(&statistic_match); 174 } 175
