From 4aca87515a5083ae0e31ce3177189fd43b6d05ac Mon Sep 17 00:00:00 2001
From: Andreas Baumann <mail@andreasbaumann.cc>
Date: Sat, 3 Jan 2015 13:58:15 +0100
Subject: patch to Vanilla Tomato 1.28

---
 .../src/linux/linux/net/ipv4/netfilter/ipt_TTL.c   | 110 +++++++++++++++++++++
 1 file changed, 110 insertions(+)
 create mode 100644 release/src/linux/linux/net/ipv4/netfilter/ipt_TTL.c

(limited to 'release/src/linux/linux/net/ipv4/netfilter/ipt_TTL.c')

diff --git a/release/src/linux/linux/net/ipv4/netfilter/ipt_TTL.c b/release/src/linux/linux/net/ipv4/netfilter/ipt_TTL.c
new file mode 100644
index 00000000..2f0a4e7a
--- /dev/null
+++ b/release/src/linux/linux/net/ipv4/netfilter/ipt_TTL.c
@@ -0,0 +1,110 @@
+/* TTL modification target for IP tables
+ * (C) 2000 by Harald Welte <laforge@gnumonks.org>
+ *
+ * Version: 1.8
+ *
+ * This software is distributed under the terms of GNU GPL
+ */
+
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/ip.h>
+#include <net/checksum.h>
+
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter_ipv4/ipt_TTL.h>
+
+MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
+MODULE_DESCRIPTION("IP tables TTL modification module");
+MODULE_LICENSE("GPL");
+
+static unsigned int ipt_ttl_target(struct sk_buff **pskb, unsigned int hooknum,
+		const struct net_device *in, const struct net_device *out,
+		const void *targinfo, void *userinfo)
+{
+	struct iphdr *iph = (*pskb)->nh.iph;
+	const struct ipt_TTL_info *info = targinfo;
+	u_int16_t diffs[2];
+	int new_ttl;
+			 
+	switch (info->mode) {
+		case IPT_TTL_SET:
+			new_ttl = info->ttl;
+			break;
+		case IPT_TTL_INC:
+			new_ttl = iph->ttl + info->ttl;
+			if (new_ttl > 255)
+				new_ttl = 255;
+			break;
+		case IPT_TTL_DEC:
+			new_ttl = iph->ttl - info->ttl;
+			if (new_ttl < 0)
+				new_ttl = 0;
+			break;
+		default:
+			new_ttl = iph->ttl;
+			break;
+	}
+
+	if (new_ttl != iph->ttl) {
+		diffs[0] = htons(((unsigned)iph->ttl) << 8) ^ 0xFFFF;
+		iph->ttl = new_ttl;
+		diffs[1] = htons(((unsigned)iph->ttl) << 8);
+		iph->check = csum_fold(csum_partial((char *)diffs,
+						    sizeof(diffs),
+				 	            iph->check^0xFFFF));
+									                	(*pskb)->nfcache |= NFC_ALTERED;
+	}
+
+	return IPT_CONTINUE;
+}
+
+static int ipt_ttl_checkentry(const char *tablename,
+		const struct ipt_entry *e,
+		void *targinfo,
+		unsigned int targinfosize,
+		unsigned int hook_mask)
+{
+	struct ipt_TTL_info *info = targinfo;
+
+	if (targinfosize != IPT_ALIGN(sizeof(struct ipt_TTL_info))) {
+		printk(KERN_WARNING "TTL: targinfosize %u != %Zu\n",
+				targinfosize,
+				IPT_ALIGN(sizeof(struct ipt_TTL_info)));
+		return 0;	
+	}	
+
+	if (strcmp(tablename, "mangle")) {
+		printk(KERN_WARNING "TTL: can only be called from \"mangle\" table, not \"%s\"\n", tablename);
+		return 0;
+	}
+
+	if (info->mode > IPT_TTL_MAXMODE) {
+		printk(KERN_WARNING "TTL: invalid or unknown Mode %u\n", 
+			info->mode);
+		return 0;
+	}
+
+	if ((info->mode != IPT_TTL_SET) && (info->ttl == 0)) {
+		printk(KERN_WARNING "TTL: increment/decrement doesn't make sense with value 0\n");
+		return 0;
+	}
+	
+	return 1;
+}
+
+static struct ipt_target ipt_TTL = { { NULL, NULL }, "TTL", 
+	ipt_ttl_target, ipt_ttl_checkentry, NULL, THIS_MODULE };
+
+static int __init init(void)
+{
+	return ipt_register_target(&ipt_TTL);
+}
+
+static void __exit fini(void)
+{
+	ipt_unregister_target(&ipt_TTL);
+}
+
+module_init(init);
+module_exit(fini);
-- 
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