libxt_statistic.c revision 5f2922cfc0bbfbeb878f5c12e9fb3eb602ae5507 
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 <xtables.h>
9#include <linux/netfilter/xt_statistic.h>
10
11static void statistic_help(void)
12{
13	printf(
14"statistic match options:\n"
15" --mode mode                    Match mode (random, nth)\n"
16" random mode:\n"
17" --probability p		 Probability\n"
18" nth mode:\n"
19" --every n			 Match every nth packet\n"
20" --packet p			 Initial counter value (0 <= p <= n-1, default 0)\n");
21}
22
23static const struct option statistic_opts[] = {
24	{ "mode", 1, NULL, '1' },
25	{ "probability", 1, NULL, '2' },
26	{ "every", 1, NULL, '3' },
27	{ "packet", 1, NULL, '4' },
28	{ .name = NULL }
29};
30
31static struct xt_statistic_info *global_info;
32
33static void statistic_mt_init(struct xt_entry_match *match)
34{
35	global_info = (void *)match->data;
36}
37
38static int
39statistic_parse(int c, char **argv, int invert, unsigned int *flags,
40                const void *entry, struct xt_entry_match **match)
41{
42	struct xt_statistic_info *info = (void *)(*match)->data;
43	unsigned int val;
44	double prob;
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 (!xtables_strtoui(optarg, NULL, &val, 0, UINT32_MAX))
75			exit_error(PARAMETER_PROBLEM,
76				   "cannot parse --every `%s'", optarg);
77		info->u.nth.every = val;
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 (!xtables_strtoui(optarg, NULL, &val, 0, UINT32_MAX))
87			exit_error(PARAMETER_PROBLEM,
88				   "cannot parse --packet `%s'", optarg);
89		info->u.nth.packet = val;
90		*flags |= 0x8;
91		break;
92	default:
93		return 0;
94	}
95	return 1;
96}
97
98static void statistic_check(unsigned int flags)
99{
100	if (!(flags & 0x1))
101		exit_error(PARAMETER_PROBLEM, "no mode specified");
102	if ((flags & 0x2) && (flags & (0x4 | 0x8)))
103		exit_error(PARAMETER_PROBLEM,
104			   "both nth and random parameters given");
105	if (flags & 0x2 && global_info->mode != XT_STATISTIC_MODE_RANDOM)
106		exit_error(PARAMETER_PROBLEM,
107			   "--probability can only be used in random mode");
108	if (flags & 0x4 && global_info->mode != XT_STATISTIC_MODE_NTH)
109		exit_error(PARAMETER_PROBLEM,
110			   "--every can only be used in nth mode");
111	if (flags & 0x8 && global_info->mode != XT_STATISTIC_MODE_NTH)
112		exit_error(PARAMETER_PROBLEM,
113			   "--packet can only be used in nth mode");
114	if ((flags & 0x8) && !(flags & 0x4))
115		exit_error(PARAMETER_PROBLEM,
116			   "--packet can only be used with --every");
117	/* at this point, info->u.nth.every have been decreased. */
118	if (global_info->u.nth.packet > global_info->u.nth.every)
119		exit_error(PARAMETER_PROBLEM,
120			  "the --packet p must be 0 <= p <= n-1");
121
122
123	global_info->u.nth.count = global_info->u.nth.every -
124	                           global_info->u.nth.packet;
125}
126
127static void print_match(const struct xt_statistic_info *info, char *prefix)
128{
129	if (info->flags & XT_STATISTIC_INVERT)
130		printf("! ");
131
132	switch (info->mode) {
133	case XT_STATISTIC_MODE_RANDOM:
134		printf("%smode random %sprobability %f ", prefix, prefix,
135		       1.0 * info->u.random.probability / 0x80000000);
136		break;
137	case XT_STATISTIC_MODE_NTH:
138		printf("%smode nth %severy %u ", prefix, prefix,
139		       info->u.nth.every + 1);
140		if (info->u.nth.packet)
141			printf("%spacket %u ", prefix, info->u.nth.packet);
142		break;
143	}
144}
145
146static void
147statistic_print(const void *ip, const struct xt_entry_match *match, int numeric)
148{
149	struct xt_statistic_info *info = (struct xt_statistic_info *)match->data;
150
151	printf("statistic ");
152	print_match(info, "");
153}
154
155static void statistic_save(const void *ip, const struct xt_entry_match *match)
156{
157	struct xt_statistic_info *info = (struct xt_statistic_info *)match->data;
158
159	print_match(info, "--");
160}
161
162static struct xtables_match statistic_match = {
163	.family		= AF_UNSPEC,
164	.name		= "statistic",
165	.version	= XTABLES_VERSION,
166	.size		= XT_ALIGN(sizeof(struct xt_statistic_info)),
167	.userspacesize	= offsetof(struct xt_statistic_info, u.nth.count),
168	.init		= statistic_mt_init,
169	.help		= statistic_help,
170	.parse		= statistic_parse,
171	.final_check	= statistic_check,
172	.print		= statistic_print,
173	.save		= statistic_save,
174	.extra_opts	= statistic_opts,
175};
176
177void _init(void)
178{
179	xtables_register_match(&statistic_match);
180}
181