libip6t_hl.c revision 46525cd3880d2b1aad0b049122a67c9e626ec6d9 
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 void init(struct ip6t_entry_match *m, unsigned int *nfcache)
29{
30	/* caching not yet implemented */
31	*nfcache |= NFC_UNKNOWN;
32}
33
34static int parse(int c, char **argv, int invert, unsigned int *flags,
35		const struct ip6t_entry *entry, unsigned int *nfcache,
36		struct ip6t_entry_match **match)
37{
38	struct ip6t_hl_info *info = (struct ip6t_hl_info *) (*match)->data;
39	u_int8_t value;
40
41	check_inverse(optarg, &invert, &optind, 0);
42	value = atoi(argv[optind-1]);
43
44	if (*flags)
45		exit_error(PARAMETER_PROBLEM,
46				"Can't specify HL option twice");
47
48	if (!optarg)
49		exit_error(PARAMETER_PROBLEM,
50				"hl: You must specify a value");
51	switch (c) {
52		case '2':
53			if (invert)
54				info->mode = IP6T_HL_NE;
55			else
56				info->mode = IP6T_HL_EQ;
57
58			/* is 0 allowed? */
59			info->hop_limit = value;
60			*flags = 1;
61
62			break;
63		case '3':
64			if (invert)
65				exit_error(PARAMETER_PROBLEM,
66						"hl: unexpected `!'");
67
68			info->mode = IP6T_HL_LT;
69			info->hop_limit = value;
70			*flags = 1;
71
72			break;
73		case '4':
74			if (invert)
75				exit_error(PARAMETER_PROBLEM,
76						"hl: unexpected `!'");
77
78			info->mode = IP6T_HL_GT;
79			info->hop_limit = value;
80			*flags = 1;
81
82			break;
83		default:
84			return 0;
85	}
86
87	return 1;
88}
89
90static void final_check(unsigned int flags)
91{
92	if (!flags)
93		exit_error(PARAMETER_PROBLEM,
94			"HL match: You must specify one of "
95			"`--hl-eq', `--hl-lt', `--hl-gt'");
96}
97
98static void print(const struct ip6t_ip6 *ip,
99		const struct ip6t_entry_match *match,
100		int numeric)
101{
102	static const char *op[] = {
103		[IP6T_HL_EQ] = "==",
104		[IP6T_HL_NE] = "!=",
105		[IP6T_HL_LT] = "<",
106		[IP6T_HL_GT] = ">" };
107
108	const struct ip6t_hl_info *info =
109		(struct ip6t_hl_info *) match->data;
110
111	printf("HL match HL %s %u ", op[info->mode], info->hop_limit);
112}
113
114static void save(const struct ip6t_ip6 *ip,
115		const struct ip6t_entry_match *match)
116{
117	static const char *op[] = {
118		[IP6T_HL_EQ] = "eq",
119		[IP6T_HL_NE] = "eq !",
120		[IP6T_HL_LT] = "lt",
121		[IP6T_HL_GT] = "gt" };
122
123	const struct ip6t_hl_info *info =
124		(struct ip6t_hl_info *) match->data;
125
126	printf("--hl-%s %u ", op[info->mode], info->hop_limit);
127}
128
129static struct option opts[] = {
130	{ .name = "hl",    .has_arg = 1, .flag = 0, .val = '2' },
131	{ .name = "hl-eq", .has_arg = 1, .flag = 0, .val = '2' },
132	{ .name = "hl-lt", .has_arg = 1, .flag = 0, .val = '3' },
133	{ .name = "hl-gt", .has_arg = 1, .flag = 0, .val = '4' },
134	{ 0 }
135};
136
137static
138struct ip6tables_match hl = {
139	.name          = "hl",
140	.version       = IPTABLES_VERSION,
141	.size          = IP6T_ALIGN(sizeof(struct ip6t_hl_info)),
142	.userspacesize = IP6T_ALIGN(sizeof(struct ip6t_hl_info)),
143	.help          = &help,
144	.init          = &init,
145	.parse         = &parse,
146	.final_check   = &final_check,
147	.print         = &print,
148	.save          = &save,
149	.extra_opts    = opts
150};
151
152
153void _init(void)
154{
155	register_match6(&hl);
156}
157