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