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gerrit-public.fairphone.software / fp2-dev / platform / external / iptables / e0072945b57dc499327567640648050563b19a5e / . / extensions / libipt_TTL.c
blob: 985b914685be6c7a954569d2cd6036add60b77de [file] [log] [blame]
Harald Welte703828f2000-10-04 15:27:07 +0000[diff] [blame]1/* Shared library add-on to iptables for the TTL target
2 * (C) 2000 by Harald Welte <laforge@gnumonks.org>
3 *
Harald Welte1441c422000-11-13 12:32:50 +0000[diff] [blame]4 * libipt_TTL.c,v 1.3 2000/11/13 11:16:08 laforge Exp
Harald Welte703828f2000-10-04 15:27:07 +0000[diff] [blame]5 *
6 * This program is distributed under the terms of GNU GPL
7 */
8#include <stdio.h>
9#include <string.h>
10#include <stdlib.h>
11#include <getopt.h>
12#include <iptables.h>
13
14#include <linux/netfilter_ipv4/ip_tables.h>
15#include <linux/netfilter_ipv4/ipt_TTL.h>
16
17#define IPT_TTL_USED 1
18
19static void init(struct ipt_entry_target *t, unsigned int *nfcache)
20{
21}
22
23static void help(void)
24{
25 printf(
26"TTL target v%s options\n"
27" --ttl-set value Set TTL to <value>\n"
28" --ttl-dec value Decrement TTL by <value>\n"
29" --ttl-inc value Increment TTL by <value>\n"
30, NETFILTER_VERSION);
31}
32
33static int parse(int c, char **argv, int invert, unsigned int *flags,
34 const struct ipt_entry *entry,
35 struct ipt_entry_target **target)
36{
37 struct ipt_TTL_info *info = (struct ipt_TTL_info *) (*target)->data;
38 u_int8_t value;
39
40 if (*flags & IPT_TTL_USED) {
41 exit_error(PARAMETER_PROBLEM,
42 "Can't specify TTL option twice");
43 }
44
45 if (!optarg)
46 exit_error(PARAMETER_PROBLEM,
47 "TTL: You must specify a value");
48
49 if (check_inverse(optarg, &invert))
50 exit_error(PARAMETER_PROBLEM,
51 "TTL: unexpected `!'");
52
53 value = atoi(optarg);
54
55 switch (c) {
56
57 case '1':
58 info->mode = IPT_TTL_SET;
59 break;
60
61 case '2':
62 if (value == 0) {
63 exit_error(PARAMETER_PROBLEM,
64 "TTL: decreasing by 0?");
65 }
66
67 info->mode = IPT_TTL_DEC;
68 break;
69
70 case '3':
71 if (value == 0) {
72 exit_error(PARAMETER_PROBLEM,
73 "TTL: increasing by 0?");
74 }
75
76 info->mode = IPT_TTL_INC;
77 break;
78
79 default:
80 return 0;
81
82 }
83
84 info->ttl = value;
85 *flags |= IPT_TTL_USED;
86
87 return 1;
88}
89
90static void final_check(unsigned int flags)
91{
92 if (!(flags & IPT_TTL_USED))
93 exit_error(PARAMETER_PROBLEM,
94 "TTL: You must specify an action");
95}
96
97static void save(const struct ipt_ip *ip,
98 const struct ipt_entry_target *target)
99{
100 const struct ipt_TTL_info *info =
101 (struct ipt_TTL_info *) target->data;
102
103 switch (info->mode) {
104 case IPT_TTL_SET:
105 printf("--ttl-set ");
106 break;
107 case IPT_TTL_DEC:
108 printf("--ttl-dec ");
109 break;
110
111 case IPT_TTL_INC:
112 printf("--ttl-inc ");
113 break;
114 }
115 printf("%u ", info->ttl);
116}
117
118static void print(const struct ipt_ip *ip,
119 const struct ipt_entry_target *target, int numeric)
120{
121 const struct ipt_TTL_info *info =
122 (struct ipt_TTL_info *) target->data;
123
124 printf("TTL ");
125 switch (info->mode) {
126 case IPT_TTL_SET:
127 printf("set to ");
128 break;
129 case IPT_TTL_DEC:
130 printf("decrement by ");
131 break;
132 case IPT_TTL_INC:
133 printf("increment by ");
134 break;
135 }
136 printf("%u ", info->ttl);
137}
138
139static struct option opts[] = {
140 { "ttl-set", 1, 0, '1' },
141 { "ttl-dec", 1, 0, '2' },
142 { "ttl-inc", 1, 0, '3' },
143 { 0 }
144};
145
146struct iptables_target TTL = { NULL,
147 "TTL",
148 NETFILTER_VERSION,
149 IPT_ALIGN(sizeof(struct ipt_TTL_info)),
150 IPT_ALIGN(sizeof(struct ipt_TTL_info)),
151 &help,
152 &init,
153 &parse,
154 &final_check,
155 &print,
156 &save,
157 opts
158};
159
160void _init(void)
161{
162 register_target(&TTL);
163}