1 files changed, 87 insertions, 0 deletions
diff --git a/extensions/libxt_helper.c b/extensions/libxt_helper.c
new file mode 100644
index 0000000..35b5f15
--- /dev/null
+++ b/extensions/libxt_helper.c
@@ -0,0 +1,87 @@
+/* Shared library add-on to iptables to add related packet matching support. */
+#include <stdio.h>
+#include <netdb.h>
+#include <string.h>
+#include <stdlib.h>
+#include <getopt.h>
+
+#include <xtables.h>
+#include <linux/netfilter/xt_helper.h>
+
+static void helper_help(void)
+{
+	printf(
+"helper match options:\n"
+"[!] --helper string        Match helper identified by string\n");
+}
+
+static const struct option helper_opts[] = {
+	{ "helper", 1, NULL, '1' },
+	{ .name = NULL }
+};
+
+static int
+helper_parse(int c, char **argv, int invert, unsigned int *flags,
+             const void *entry, struct xt_entry_match **match)
+{
+	struct xt_helper_info *info = (struct xt_helper_info *)(*match)->data;
+
+	switch (c) {
+	case '1':
+		if (*flags)
+			xtables_error(PARAMETER_PROBLEM,
+					"helper match: Only use --helper ONCE!");
+		xtables_check_inverse(optarg, &invert, &optind, 0, argv);
+		strncpy(info->name, optarg, 29);
+		info->name[29] = '\0';
+		if (invert)
+			info->invert = 1;
+		*flags = 1;
+		break;
+
+	default:
+		return 0;
+	}
+	return 1;
+}
+
+static void helper_check(unsigned int flags)
+{
+	if (!flags)
+		xtables_error(PARAMETER_PROBLEM,
+			   "helper match: You must specify `--helper'");
+}
+
+static void
+helper_print(const void *ip, const struct xt_entry_match *match, int numeric)
+{
+	const struct xt_helper_info *info = (const void *)match->data;
+
+	printf("helper match %s\"%s\" ", info->invert ? "! " : "", info->name);
+}
+
+static void helper_save(const void *ip, const struct xt_entry_match *match)
+{
+	const struct xt_helper_info *info = (const void *)match->data;
+
+	printf("%s--helper ",info->invert ? "! " : "");
+	xtables_save_string(info->name);
+}
+
+static struct xtables_match helper_match = {
+	.family		= NFPROTO_UNSPEC,
+	.name		= "helper",
+	.version	= XTABLES_VERSION,
+	.size		= XT_ALIGN(sizeof(struct xt_helper_info)),
+	.help		= helper_help,
+	.parse		= helper_parse,
+	.final_check	= helper_check,
+	.print		= helper_print,
+	.save		= helper_save,
+	.extra_opts	= helper_opts,
+};
+
+void _init(void)
+{
+	xtables_register_match(&helper_match);
+}