libip6t_hl.c revision 8115e5425721cd610b6390c3d4c24540773b0520 
1/*
2 * IPv6 Hop Limit matching module
3 * Maciej Soltysiak <solt@dns.toxicfilms.tv>
4 * Based on HW's ttl match
5 * This program is released under the terms of GNU GPL
6 * Cleanups by Stephane Ouellette <ouellettes@videotron.ca>
7 */
8
9#include <stdio.h>
10#include <stdlib.h>
11#include <string.h>
12#include <getopt.h>
13#include <ip6tables.h>
14
15#include <linux/netfilter_ipv6/ip6_tables.h>
16#include <linux/netfilter_ipv6/ip6t_hl.h>
17
18static void help(void)
19{
20	printf(
21"HL match v%s options:\n"
22"  --hl-eq [!] value	Match hop limit value\n"
23"  --hl-lt value	Match HL < value\n"
24"  --hl-gt value	Match HL > value\n"
25, IPTABLES_VERSION);
26}
27
28static int parse(int c, char **argv, int invert, unsigned int *flags,
29		const struct ip6t_entry *entry, unsigned int *nfcache,
30		struct ip6t_entry_match **match)
31{
32	struct ip6t_hl_info *info = (struct ip6t_hl_info *) (*match)->data;
33	u_int8_t value;
34
35	check_inverse(optarg, &invert, &optind, 0);
36	value = atoi(argv[optind-1]);
37
38	if (*flags)
39		exit_error(PARAMETER_PROBLEM,
40				"Can't specify HL option twice");
41
42	if (!optarg)
43		exit_error(PARAMETER_PROBLEM,
44				"hl: You must specify a value");
45	switch (c) {
46		case '2':
47			if (invert)
48				info->mode = IP6T_HL_NE;
49			else
50				info->mode = IP6T_HL_EQ;
51
52			/* is 0 allowed? */
53			info->hop_limit = value;
54			*flags = 1;
55
56			break;
57		case '3':
58			if (invert)
59				exit_error(PARAMETER_PROBLEM,
60						"hl: unexpected `!'");
61
62			info->mode = IP6T_HL_LT;
63			info->hop_limit = value;
64			*flags = 1;
65
66			break;
67		case '4':
68			if (invert)
69				exit_error(PARAMETER_PROBLEM,
70						"hl: unexpected `!'");
71
72			info->mode = IP6T_HL_GT;
73			info->hop_limit = value;
74			*flags = 1;
75
76			break;
77		default:
78			return 0;
79	}
80
81	return 1;
82}
83
84static void final_check(unsigned int flags)
85{
86	if (!flags)
87		exit_error(PARAMETER_PROBLEM,
88			"HL match: You must specify one of "
89			"`--hl-eq', `--hl-lt', `--hl-gt'");
90}
91
92static void print(const struct ip6t_ip6 *ip,
93		const struct ip6t_entry_match *match,
94		int numeric)
95{
96	static const char *op[] = {
97		[IP6T_HL_EQ] = "==",
98		[IP6T_HL_NE] = "!=",
99		[IP6T_HL_LT] = "<",
100		[IP6T_HL_GT] = ">" };
101
102	const struct ip6t_hl_info *info =
103		(struct ip6t_hl_info *) match->data;
104
105	printf("HL match HL %s %u ", op[info->mode], info->hop_limit);
106}
107
108static void save(const struct ip6t_ip6 *ip,
109		const struct ip6t_entry_match *match)
110{
111	static const char *op[] = {
112		[IP6T_HL_EQ] = "eq",
113		[IP6T_HL_NE] = "eq !",
114		[IP6T_HL_LT] = "lt",
115		[IP6T_HL_GT] = "gt" };
116
117	const struct ip6t_hl_info *info =
118		(struct ip6t_hl_info *) match->data;
119
120	printf("--hl-%s %u ", op[info->mode], info->hop_limit);
121}
122
123static struct option opts[] = {
124	{ .name = "hl",    .has_arg = 1, .flag = 0, .val = '2' },
125	{ .name = "hl-eq", .has_arg = 1, .flag = 0, .val = '2' },
126	{ .name = "hl-lt", .has_arg = 1, .flag = 0, .val = '3' },
127	{ .name = "hl-gt", .has_arg = 1, .flag = 0, .val = '4' },
128	{ 0 }
129};
130
131static
132struct ip6tables_match hl = {
133	.name          = "hl",
134	.version       = IPTABLES_VERSION,
135	.size          = IP6T_ALIGN(sizeof(struct ip6t_hl_info)),
136	.userspacesize = IP6T_ALIGN(sizeof(struct ip6t_hl_info)),
137	.help          = &help,
138	.parse         = &parse,
139	.final_check   = &final_check,
140	.print         = &print,
141	.save          = &save,
142	.extra_opts    = opts
143};
144
145
146void _init(void)
147{
148	register_match6(&hl);
149}
150