libip6t_HL.c revision 0463ee1f28946cc49815737daa0ced0c68f39f0b 
1/*
2 * IPv6 Hop Limit Target module
3 * Maciej Soltysiak <solt@dns.toxicfilms.tv>
4 * Based on HW's ttl target
5 * This program is distributed under the terms of GNU GPL
6 */
7
8#include <stdio.h>
9#include <string.h>
10#include <stdlib.h>
11#include <getopt.h>
12#include <ip6tables.h>
13
14#include <linux/netfilter_ipv6/ip6_tables.h>
15#include <linux/netfilter_ipv6/ip6t_HL.h>
16
17#define IP6T_HL_USED	1
18
19static void help(void)
20{
21	printf(
22"HL target v%s options\n"
23"  --hl-set value		Set HL to <value 0-255>\n"
24"  --hl-dec value		Decrement HL by <value 1-255>\n"
25"  --hl-inc value		Increment HL by <value 1-255>\n"
26, IPTABLES_VERSION);
27}
28
29static int parse(int c, char **argv, int invert, unsigned int *flags,
30		const void *entry,
31		struct xt_entry_target **target)
32{
33	struct ip6t_HL_info *info = (struct ip6t_HL_info *) (*target)->data;
34	unsigned int value;
35
36	if (*flags & IP6T_HL_USED) {
37		exit_error(PARAMETER_PROBLEM,
38				"Can't specify HL option twice");
39	}
40
41	if (!optarg)
42		exit_error(PARAMETER_PROBLEM,
43				"HL: You must specify a value");
44
45	if (check_inverse(optarg, &invert, NULL, 0))
46		exit_error(PARAMETER_PROBLEM,
47				"HL: unexpected `!'");
48
49	if (string_to_number(optarg, 0, 255, &value) == -1)
50		exit_error(PARAMETER_PROBLEM,
51		           "HL: Expected value between 0 and 255");
52
53	switch (c) {
54
55		case '1':
56			info->mode = IP6T_HL_SET;
57			break;
58
59		case '2':
60			if (value == 0) {
61				exit_error(PARAMETER_PROBLEM,
62					"HL: decreasing by 0?");
63			}
64
65			info->mode = IP6T_HL_DEC;
66			break;
67
68		case '3':
69			if (value == 0) {
70				exit_error(PARAMETER_PROBLEM,
71					"HL: increasing by 0?");
72			}
73
74			info->mode = IP6T_HL_INC;
75			break;
76
77		default:
78			return 0;
79
80	}
81
82	info->hop_limit = value;
83	*flags |= IP6T_HL_USED;
84
85	return 1;
86}
87
88static void final_check(unsigned int flags)
89{
90	if (!(flags & IP6T_HL_USED))
91		exit_error(PARAMETER_PROBLEM,
92				"HL: You must specify an action");
93}
94
95static void save(const void *ip,
96		const struct xt_entry_target *target)
97{
98	const struct ip6t_HL_info *info =
99		(struct ip6t_HL_info *) target->data;
100
101	switch (info->mode) {
102		case IP6T_HL_SET:
103			printf("--hl-set ");
104			break;
105		case IP6T_HL_DEC:
106			printf("--hl-dec ");
107			break;
108
109		case IP6T_HL_INC:
110			printf("--hl-inc ");
111			break;
112	}
113	printf("%u ", info->hop_limit);
114}
115
116static void print(const void *ip,
117		const struct xt_entry_target *target, int numeric)
118{
119	const struct ip6t_HL_info *info =
120		(struct ip6t_HL_info *) target->data;
121
122	printf("HL ");
123	switch (info->mode) {
124		case IP6T_HL_SET:
125			printf("set to ");
126			break;
127		case IP6T_HL_DEC:
128			printf("decrement by ");
129			break;
130		case IP6T_HL_INC:
131			printf("increment by ");
132			break;
133	}
134	printf("%u ", info->hop_limit);
135}
136
137static const struct option opts[] = {
138	{ "hl-set", 1, NULL, '1' },
139	{ "hl-dec", 1, NULL, '2' },
140	{ "hl-inc", 1, NULL, '3' },
141	{ }
142};
143
144static
145struct ip6tables_target HL = {
146	.name 		= "HL",
147	.version	= IPTABLES_VERSION,
148	.size		= IP6T_ALIGN(sizeof(struct ip6t_HL_info)),
149	.userspacesize	= IP6T_ALIGN(sizeof(struct ip6t_HL_info)),
150	.help		= &help,
151	.parse		= &parse,
152	.final_check	= &final_check,
153	.print		= &print,
154	.save		= &save,
155	.extra_opts	= opts
156};
157
158void _init(void)
159{
160	register_target6(&HL);
161}
162