libip6t_hl.c revision 9ee386a1b6d7704b259460152c959ab0e79e02aa 
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 hl_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 hl_parse(int c, char **argv, int invert, unsigned int *flags,
29                    const void *entry, struct xt_entry_match **match)
30{
31	struct ip6t_hl_info *info = (struct ip6t_hl_info *) (*match)->data;
32	u_int8_t value;
33
34	check_inverse(optarg, &invert, &optind, 0);
35	value = atoi(argv[optind-1]);
36
37	if (*flags)
38		exit_error(PARAMETER_PROBLEM,
39				"Can't specify HL option twice");
40
41	if (!optarg)
42		exit_error(PARAMETER_PROBLEM,
43				"hl: You must specify a value");
44	switch (c) {
45		case '2':
46			if (invert)
47				info->mode = IP6T_HL_NE;
48			else
49				info->mode = IP6T_HL_EQ;
50
51			/* is 0 allowed? */
52			info->hop_limit = value;
53			*flags = 1;
54
55			break;
56		case '3':
57			if (invert)
58				exit_error(PARAMETER_PROBLEM,
59						"hl: unexpected `!'");
60
61			info->mode = IP6T_HL_LT;
62			info->hop_limit = value;
63			*flags = 1;
64
65			break;
66		case '4':
67			if (invert)
68				exit_error(PARAMETER_PROBLEM,
69						"hl: unexpected `!'");
70
71			info->mode = IP6T_HL_GT;
72			info->hop_limit = value;
73			*flags = 1;
74
75			break;
76		default:
77			return 0;
78	}
79
80	return 1;
81}
82
83static void hl_check(unsigned int flags)
84{
85	if (!flags)
86		exit_error(PARAMETER_PROBLEM,
87			"HL match: You must specify one of "
88			"`--hl-eq', `--hl-lt', `--hl-gt'");
89}
90
91static void hl_print(const void *ip, const struct xt_entry_match *match,
92                     int numeric)
93{
94	static const char *op[] = {
95		[IP6T_HL_EQ] = "==",
96		[IP6T_HL_NE] = "!=",
97		[IP6T_HL_LT] = "<",
98		[IP6T_HL_GT] = ">" };
99
100	const struct ip6t_hl_info *info =
101		(struct ip6t_hl_info *) match->data;
102
103	printf("HL match HL %s %u ", op[info->mode], info->hop_limit);
104}
105
106static void hl_save(const void *ip, const struct xt_entry_match *match)
107{
108	static const char *op[] = {
109		[IP6T_HL_EQ] = "eq",
110		[IP6T_HL_NE] = "eq !",
111		[IP6T_HL_LT] = "lt",
112		[IP6T_HL_GT] = "gt" };
113
114	const struct ip6t_hl_info *info =
115		(struct ip6t_hl_info *) match->data;
116
117	printf("--hl-%s %u ", op[info->mode], info->hop_limit);
118}
119
120static const struct option hl_opts[] = {
121	{ .name = "hl",    .has_arg = 1, .val = '2' },
122	{ .name = "hl-eq", .has_arg = 1, .val = '2' },
123	{ .name = "hl-lt", .has_arg = 1, .val = '3' },
124	{ .name = "hl-gt", .has_arg = 1, .val = '4' },
125	{ .name = NULL }
126};
127
128static struct ip6tables_match hl_match6 = {
129	.name          = "hl",
130	.version       = IPTABLES_VERSION,
131	.size          = IP6T_ALIGN(sizeof(struct ip6t_hl_info)),
132	.userspacesize = IP6T_ALIGN(sizeof(struct ip6t_hl_info)),
133	.help          = hl_help,
134	.parse         = hl_parse,
135	.final_check   = hl_check,
136	.print         = hl_print,
137	.save          = hl_save,
138	.extra_opts    = hl_opts,
139};
140
141
142void _init(void)
143{
144	register_match6(&hl_match6);
145}
146