1 files changed, 157 insertions, 0 deletions
diff --git a/extensions/libipt_TTL.c b/extensions/libipt_TTL.c
new file mode 100644
index 0000000..4db9bbe
--- /dev/null
+++ b/extensions/libipt_TTL.c
@@ -0,0 +1,157 @@
+/* Shared library add-on to iptables for the TTL target
+ * (C) 2000 by Harald Welte <laforge@gnumonks.org>
+ *
+ * $Id$
+ *
+ * This program is distributed under the terms of GNU GPL
+ */
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <getopt.h>
+#include <xtables.h>
+
+#include <linux/netfilter_ipv4/ipt_TTL.h>
+
+#define IPT_TTL_USED	1
+
+static void TTL_help(void)
+{
+	printf(
+"TTL target options\n"
+"  --ttl-set value		Set TTL to <value 0-255>\n"
+"  --ttl-dec value		Decrement TTL by <value 1-255>\n"
+"  --ttl-inc value		Increment TTL by <value 1-255>\n");
+}
+
+static int TTL_parse(int c, char **argv, int invert, unsigned int *flags,
+                     const void *entry, struct xt_entry_target **target)
+{
+	struct ipt_TTL_info *info = (struct ipt_TTL_info *) (*target)->data;
+	unsigned int value;
+
+	if (*flags & IPT_TTL_USED) {
+		xtables_error(PARAMETER_PROBLEM,
+				"Can't specify TTL option twice");
+	}
+
+	if (!optarg) 
+		xtables_error(PARAMETER_PROBLEM,
+				"TTL: You must specify a value");
+
+	if (xtables_check_inverse(optarg, &invert, NULL, 0, argv))
+		xtables_error(PARAMETER_PROBLEM,
+				"TTL: unexpected `!'");
+	
+	if (!xtables_strtoui(optarg, NULL, &value, 0, UINT8_MAX))
+		xtables_error(PARAMETER_PROBLEM,
+		           "TTL: Expected value between 0 and 255");
+
+	switch (c) {
+
+		case '1':
+			info->mode = IPT_TTL_SET;
+			break;
+
+		case '2':
+			if (value == 0) {
+				xtables_error(PARAMETER_PROBLEM,
+					"TTL: decreasing by 0?");
+			}
+
+			info->mode = IPT_TTL_DEC;
+			break;
+
+		case '3':
+			if (value == 0) {
+				xtables_error(PARAMETER_PROBLEM,
+					"TTL: increasing by 0?");
+			}
+
+			info->mode = IPT_TTL_INC;
+			break;
+
+		default:
+			return 0;
+
+	}
+	
+	info->ttl = value;
+	*flags |= IPT_TTL_USED;
+
+	return 1;
+}
+
+static void TTL_check(unsigned int flags)
+{
+	if (!(flags & IPT_TTL_USED))
+		xtables_error(PARAMETER_PROBLEM,
+				"TTL: You must specify an action");
+}
+
+static void TTL_save(const void *ip, const struct xt_entry_target *target)
+{
+	const struct ipt_TTL_info *info = 
+		(struct ipt_TTL_info *) target->data;
+
+	switch (info->mode) {
+		case IPT_TTL_SET:
+			printf("--ttl-set ");
+			break;
+		case IPT_TTL_DEC:
+			printf("--ttl-dec ");
+			break;
+
+		case IPT_TTL_INC:
+			printf("--ttl-inc ");
+			break;
+	}
+	printf("%u ", info->ttl);
+}
+
+static void TTL_print(const void *ip, const struct xt_entry_target *target,
+                      int numeric)
+{
+	const struct ipt_TTL_info *info =
+		(struct ipt_TTL_info *) target->data;
+
+	printf("TTL ");
+	switch (info->mode) {
+		case IPT_TTL_SET:
+			printf("set to ");
+			break;
+		case IPT_TTL_DEC:
+			printf("decrement by ");
+			break;
+		case IPT_TTL_INC:
+			printf("increment by ");
+			break;
+	}
+	printf("%u ", info->ttl);
+}
+
+static const struct option TTL_opts[] = {
+	{ "ttl-set", 1, NULL, '1' },
+	{ "ttl-dec", 1, NULL, '2' },
+	{ "ttl-inc", 1, NULL, '3' },
+	{ .name = NULL }
+};
+
+static struct xtables_target ttl_tg_reg = {
+	.name		= "TTL",
+	.version	= XTABLES_VERSION,
+	.family		= NFPROTO_IPV4,
+	.size		= XT_ALIGN(sizeof(struct ipt_TTL_info)),
+	.userspacesize	= XT_ALIGN(sizeof(struct ipt_TTL_info)),
+	.help		= TTL_help,
+	.parse		= TTL_parse,
+	.final_check	= TTL_check,
+	.print		= TTL_print,
+	.save		= TTL_save,
+	.extra_opts	= TTL_opts,
+};
+
+void _init(void)
+{
+	xtables_register_target(&ttl_tg_reg);
+}