extensions/libipt_condition.c

/* Shared library add-on to iptables for condition match */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>
#include <iptables.h>

#include<linux/netfilter_ipv4/ip_tables.h>
#include<linux/netfilter_ipv4/ipt_condition.h>


static void
help(void)
{
	printf("condition match v%s options:\n"
	       "--condition [!] filename       "
	       "Match on boolean value stored in /proc file\n",
	       IPTABLES_VERSION);
}


static struct option opts[] = {
	{ .name = "condition", .has_arg = 1, .flag = 0, .val = 'X' },
	{ .name = 0 }
};


static void
init(struct ipt_entry_match *m, unsigned int *nfcache)
{
	*nfcache |= NFC_UNKNOWN;
}


static int
parse(int c, char **argv, int invert, unsigned int *flags,
      const struct ipt_entry *entry, unsigned int *nfcache,
      struct ipt_entry_match **match)
{
	struct condition_info *info =
	    (struct condition_info *) (*match)->data;

	if (c == 'X') {
		if (*flags)
			exit_error(PARAMETER_PROBLEM,
				   "Can't specify multiple conditions");

		check_inverse(optarg, &invert, &optind, 0);

		if (strlen(argv[optind - 1]) < CONDITION_NAME_LEN)
			strcpy(info->name, argv[optind - 1]);
		else
			exit_error(PARAMETER_PROBLEM,
				   "File name too long");

		info->invert = invert;
		*flags = 1;
		return 1;
	}

	return 0;
}


static void
final_check(unsigned int flags)
{
	if (!flags)
		exit_error(PARAMETER_PROBLEM,
			   "Condition match: must specify --condition");
}


static void
print(const struct ipt_ip *ip,
		  const struct ipt_entry_match *match, int numeric)
{
	const struct condition_info *info =
	    (const struct condition_info *) match->data;

	printf("condition %s%s ", (info->invert) ? "!" : "", info->name);
}


static void
save(const struct ipt_ip *ip,
		 const struct ipt_entry_match *match)
{
	const struct condition_info *info =
	    (const struct condition_info *) match->data;

	printf("--condition %s\"%s\" ", (info->invert) ? "! " : "", info->name);
}


static struct iptables_match condition = {
	.name = "condition",
	.version = IPTABLES_VERSION,
	.size = IPT_ALIGN(sizeof(struct condition_info)),
	.userspacesize = IPT_ALIGN(sizeof(struct condition_info)),
	.help = &help,
	.init = &init,
	.parse = &parse,
	.final_check = &final_check,
	.print = &print,
	.save = &save,
	.extra_opts = opts
};


void
_init(void)
{
	register_match(&condition);
}