libxt_helper.c revision f8137b1b4cc18d4ff528ac40b83345260bb644ae 
1/* Shared library add-on to iptables to add related packet matching support. */
2#include <stdio.h>
3#include <netdb.h>
4#include <string.h>
5#include <stdlib.h>
6#include <getopt.h>
7
8#include <xtables.h>
9#include <linux/netfilter/xt_helper.h>
10
11/* Function which prints out usage message. */
12static void
13help(void)
14{
15	printf(
16"helper match v%s options:\n"
17"[!] --helper string        Match helper identified by string\n"
18"\n",
19IPTABLES_VERSION);
20}
21
22static const struct option opts[] = {
23	{ "helper", 1, 0, '1' },
24	{0}
25};
26
27/* Function which parses command options; returns true if it
28   ate an option */
29static int
30parse(int c, char **argv, int invert, unsigned int *flags,
31      const void *entry,
32      unsigned int *nfcache,
33      struct xt_entry_match **match)
34{
35	struct xt_helper_info *info = (struct xt_helper_info *)(*match)->data;
36
37	switch (c) {
38	case '1':
39		if (*flags)
40			exit_error(PARAMETER_PROBLEM,
41					"helper match: Only use --helper ONCE!");
42		check_inverse(optarg, &invert, &invert, 0);
43		strncpy(info->name, optarg, 29);
44		info->name[29] = '\0';
45		if (invert)
46			info->invert = 1;
47		*flags = 1;
48		break;
49
50	default:
51		return 0;
52	}
53	return 1;
54}
55
56/* Final check; must have specified --helper. */
57static void
58final_check(unsigned int flags)
59{
60	if (!flags)
61		exit_error(PARAMETER_PROBLEM,
62			   "helper match: You must specify `--helper'");
63}
64
65/* Prints out the info. */
66static void
67print(const void *ip,
68      const struct xt_entry_match *match,
69      int numeric)
70{
71	struct xt_helper_info *info = (struct xt_helper_info *)match->data;
72
73	printf("helper match %s\"%s\" ", info->invert ? "! " : "", info->name);
74}
75
76/* Saves the union ipt_info in parsable form to stdout. */
77static void
78save(const void *ip, const struct xt_entry_match *match)
79{
80	struct xt_helper_info *info = (struct xt_helper_info *)match->data;
81
82	printf("%s--helper \"%s\" ",info->invert ? "! " : "", info->name);
83}
84
85static struct xtables_match helper = {
86	.family		= AF_INET,
87	.name		= "helper",
88	.version	= IPTABLES_VERSION,
89	.size		= XT_ALIGN(sizeof(struct xt_helper_info)),
90	.help		= &help,
91	.parse		= &parse,
92	.final_check	= &final_check,
93	.print		= &print,
94	.save		= &save,
95	.extra_opts	= opts,
96};
97
98static struct xtables_match helper6 = {
99	.family		= AF_INET6,
100	.name		= "helper",
101	.version	= IPTABLES_VERSION,
102	.size		= XT_ALIGN(sizeof(struct xt_helper_info)),
103	.help		= &help,
104	.parse		= &parse,
105	.final_check	= &final_check,
106	.print		= &print,
107	.save		= &save,
108	.extra_opts	= opts,
109};
110
111void _init(void)
112{
113	xtables_register_match(&helper);
114	xtables_register_match(&helper6);
115}
116