libxt_length.c revision 6944f2c8190f1c4319aeac748470c71b0ba45025 
1#include <stdio.h>
2#include <xtables.h>
3#include <linux/netfilter/xt_length.h>
4
5enum {
6	O_LENGTH = 0,
7};
8
9static void length_help(void)
10{
11	printf(
12"length match options:\n"
13"[!] --length length[:length]    Match packet length against value or range\n"
14"                                of values (inclusive)\n");
15}
16
17static const struct xt_option_entry length_opts[] = {
18	{.name = "length", .id = O_LENGTH, .type = XTTYPE_UINT16RC,
19	 .flags = XTOPT_MAND | XTOPT_INVERT},
20	XTOPT_TABLEEND,
21};
22
23static void length_parse(struct xt_option_call *cb)
24{
25	struct xt_length_info *info = cb->data;
26
27	xtables_option_parse(cb);
28	info->min = cb->val.u16_range[0];
29	info->max = cb->val.u16_range[0];
30	if (cb->nvals >= 2)
31		info->max = cb->val.u16_range[1];
32	if (cb->invert)
33		info->invert = 1;
34}
35
36static void
37length_print(const void *ip, const struct xt_entry_match *match, int numeric)
38{
39	const struct xt_length_info *info = (void *)match->data;
40
41	printf(" length %s", info->invert ? "!" : "");
42	if (info->min == info->max)
43		printf("%u", info->min);
44	else
45		printf("%u:%u", info->min, info->max);
46}
47
48static void length_save(const void *ip, const struct xt_entry_match *match)
49{
50	const struct xt_length_info *info = (void *)match->data;
51
52	printf("%s --length ", info->invert ? " !" : "");
53	if (info->min == info->max)
54		printf("%u", info->min);
55	else
56		printf("%u:%u", info->min, info->max);
57}
58
59static struct xtables_match length_match = {
60	.family		= NFPROTO_UNSPEC,
61	.name		= "length",
62	.version	= XTABLES_VERSION,
63	.size		= XT_ALIGN(sizeof(struct xt_length_info)),
64	.userspacesize	= XT_ALIGN(sizeof(struct xt_length_info)),
65	.help		= length_help,
66	.print		= length_print,
67	.save		= length_save,
68	.x6_parse	= length_parse,
69	.x6_options	= length_opts,
70};
71
72void _init(void)
73{
74	xtables_register_match(&length_match);
75}
76