libxt_helper.c revision d09b6d591ca7d7d7575cb6aa20384c9830f777ab 
1/* Shared library add-on to iptables to add related packet matching support. */
2#include <stdbool.h>
3#include <stdio.h>
4#include <netdb.h>
5#include <string.h>
6#include <stdlib.h>
7#include <getopt.h>
8
9#include <xtables.h>
10#include <linux/netfilter/xt_helper.h>
11
12static void helper_help(void)
13{
14	printf(
15"helper match options:\n"
16"[!] --helper string        Match helper identified by string\n");
17}
18
19static const struct option helper_opts[] = {
20	{.name = "helper", .has_arg = true, .val = '1'},
21	XT_GETOPT_TABLEEND,
22};
23
24static int
25helper_parse(int c, char **argv, int invert, unsigned int *flags,
26             const void *entry, struct xt_entry_match **match)
27{
28	struct xt_helper_info *info = (struct xt_helper_info *)(*match)->data;
29
30	switch (c) {
31	case '1':
32		if (*flags)
33			xtables_error(PARAMETER_PROBLEM,
34					"helper match: Only use --helper ONCE!");
35		xtables_check_inverse(optarg, &invert, &optind, 0, argv);
36		strncpy(info->name, optarg, 29);
37		info->name[29] = '\0';
38		if (invert)
39			info->invert = 1;
40		*flags = 1;
41		break;
42	}
43	return 1;
44}
45
46static void helper_check(unsigned int flags)
47{
48	if (!flags)
49		xtables_error(PARAMETER_PROBLEM,
50			   "helper match: You must specify `--helper'");
51}
52
53static void
54helper_print(const void *ip, const struct xt_entry_match *match, int numeric)
55{
56	const struct xt_helper_info *info = (const void *)match->data;
57
58	printf("helper match %s\"%s\" ", info->invert ? "! " : "", info->name);
59}
60
61static void helper_save(const void *ip, const struct xt_entry_match *match)
62{
63	const struct xt_helper_info *info = (const void *)match->data;
64
65	printf("%s--helper ",info->invert ? "! " : "");
66	xtables_save_string(info->name);
67}
68
69static struct xtables_match helper_match = {
70	.family		= NFPROTO_UNSPEC,
71	.name		= "helper",
72	.version	= XTABLES_VERSION,
73	.size		= XT_ALIGN(sizeof(struct xt_helper_info)),
74	.help		= helper_help,
75	.parse		= helper_parse,
76	.final_check	= helper_check,
77	.print		= helper_print,
78	.save		= helper_save,
79	.extra_opts	= helper_opts,
80};
81
82void _init(void)
83{
84	xtables_register_match(&helper_match);
85}
86