From 703828fffcbcefa7adf1b835ffe930d91dcb75d7 Mon Sep 17 00:00:00 2001
From: Harald Welte <laforge@gnumonks.org>
Date: Wed, 4 Oct 2000 15:27:07 +0000
Subject: Harald Welte's ttl stuff. This patch adds two new modules to the
 netfilter CVS patch-o-matic system:

A TTL match and a TTL target for setting/incrementing/decrementing the TTL.
---
 extensions/libipt_TTL.c | 163 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 163 insertions(+)
 create mode 100644 extensions/libipt_TTL.c

(limited to 'extensions/libipt_TTL.c')

diff --git a/extensions/libipt_TTL.c b/extensions/libipt_TTL.c
new file mode 100644
index 00000000..c125bdf8
--- /dev/null
+++ b/extensions/libipt_TTL.c
@@ -0,0 +1,163 @@
+/* Shared library add-on to iptables for the TTL target
+ * (C) 2000 by Harald Welte <laforge@gnumonks.org>
+ *
+ * Version: 1.2
+ *
+ * This program is distributed under the terms of GNU GPL
+ */
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <getopt.h>
+#include <iptables.h>
+
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter_ipv4/ipt_TTL.h>
+
+#define IPT_TTL_USED	1
+
+static void init(struct ipt_entry_target *t, unsigned int *nfcache) 
+{
+}
+
+static void help(void) 
+{
+	printf(
+"TTL target v%s options\n"
+"  --ttl-set value		Set TTL to <value>\n"
+"  --ttl-dec value		Decrement TTL by <value>\n"
+"  --ttl-inc value		Increment TTL by <value>\n"
+, NETFILTER_VERSION);
+}
+
+static int parse(int c, char **argv, int invert, unsigned int *flags,
+		const struct ipt_entry *entry,
+		struct ipt_entry_target **target)
+{
+	struct ipt_TTL_info *info = (struct ipt_TTL_info *) (*target)->data;
+	u_int8_t value;
+
+	if (*flags & IPT_TTL_USED) {
+		exit_error(PARAMETER_PROBLEM, 
+				"Can't specify TTL option twice");
+	}
+
+	if (!optarg) 
+		exit_error(PARAMETER_PROBLEM, 
+				"TTL: You must specify a value");
+
+	if (check_inverse(optarg, &invert))
+		exit_error(PARAMETER_PROBLEM,
+				"TTL: unexpected `!'");
+	
+	value = atoi(optarg);
+
+	switch (c) {
+
+		case '1':
+			info->mode = IPT_TTL_SET;
+			break;
+
+		case '2':
+			if (value == 0) {
+				exit_error(PARAMETER_PROBLEM,
+					"TTL: decreasing by 0?");
+			}
+
+			info->mode = IPT_TTL_DEC;
+			break;
+
+		case '3':
+			if (value == 0) {
+				exit_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 final_check(unsigned int flags)
+{
+	if (!(flags & IPT_TTL_USED))
+		exit_error(PARAMETER_PROBLEM,
+				"TTL: You must specify an action");
+}
+
+static void save(const struct ipt_ip *ip,
+		const struct ipt_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 print(const struct ipt_ip *ip,
+		const struct ipt_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 struct option opts[] = {
+	{ "ttl-set", 1, 0, '1' },
+	{ "ttl-dec", 1, 0, '2' },
+	{ "ttl-inc", 1, 0, '3' },
+	{ 0 }
+};
+
+struct iptables_target TTL = { NULL, 
+	"TTL",
+	NETFILTER_VERSION,
+	IPT_ALIGN(sizeof(struct ipt_TTL_info)),
+	IPT_ALIGN(sizeof(struct ipt_TTL_info)),
+	&help,
+	&init,
+	&parse,
+	&final_check,
+	&print,
+	&save,
+	opts 
+};
+
+void _init(void)
+{
+	register_target(&TTL);
+}
-- 
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