1 /*
2 * Copyright (c) 2006-2013 Patrick McHardy <kaber@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
statistic_help(void)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
statistic_parse(struct xt_option_call * cb)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
statistic_check(struct xt_fcheck_call * cb)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
print_match(const struct xt_statistic_info * info,char * prefix)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
statistic_print(const void * ip,const struct xt_entry_match * match,int numeric)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
statistic_save(const void * ip,const struct xt_entry_match * match)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 struct xtables_match statistic_match = {
137 .family = NFPROTO_UNSPEC,
138 .name = "statistic",
139 .version = XTABLES_VERSION,
140 .size = XT_ALIGN(sizeof(struct xt_statistic_info)),
141 .userspacesize = offsetof(struct xt_statistic_info, u.nth.count),
142 .help = statistic_help,
143 .x6_parse = statistic_parse,
144 .x6_fcheck = statistic_check,
145 .print = statistic_print,
146 .save = statistic_save,
147 .x6_options = statistic_opts,
148 };
149
_init(void)150 void _init(void)
151 {
152 xtables_register_match(&statistic_match);
153 }
154