1 files changed, 117 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/ipt_NETMAP.c b/net/ipv4/netfilter/ipt_NETMAP.c
new file mode 100644
index 00000000000..06254b29d03
--- /dev/null
+++ b/net/ipv4/netfilter/ipt_NETMAP.c
@@ -0,0 +1,117 @@
+/* NETMAP - static NAT mapping of IP network addresses (1:1).
+ * The mapping can be applied to source (POSTROUTING),
+ * destination (PREROUTING), or both (with separate rules).
+ */
+
+/* (C) 2000-2001 Svenning Soerensen <svenning@post5.tele.dk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/config.h>
+#include <linux/ip.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/netfilter_ipv4/ip_nat_rule.h>
+
+#define MODULENAME "NETMAP"
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Svenning Soerensen <svenning@post5.tele.dk>");
+MODULE_DESCRIPTION("iptables 1:1 NAT mapping of IP networks target");
+
+#if 0
+#define DEBUGP printk
+#else
+#define DEBUGP(format, args...)
+#endif
+
+static int
+check(const char *tablename,
+      const struct ipt_entry *e,
+      void *targinfo,
+      unsigned int targinfosize,
+      unsigned int hook_mask)
+{
+	const struct ip_nat_multi_range_compat *mr = targinfo;
+
+	if (strcmp(tablename, "nat") != 0) {
+		DEBUGP(MODULENAME":check: bad table `%s'.\n", tablename);
+		return 0;
+	}
+	if (targinfosize != IPT_ALIGN(sizeof(*mr))) {
+		DEBUGP(MODULENAME":check: size %u.\n", targinfosize);
+		return 0;
+	}
+	if (hook_mask & ~((1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_POST_ROUTING))) {
+		DEBUGP(MODULENAME":check: bad hooks %x.\n", hook_mask);
+		return 0;
+	}
+	if (!(mr->range[0].flags & IP_NAT_RANGE_MAP_IPS)) {
+		DEBUGP(MODULENAME":check: bad MAP_IPS.\n");
+		return 0;
+	}
+	if (mr->rangesize != 1) {
+		DEBUGP(MODULENAME":check: bad rangesize %u.\n", mr->rangesize);
+		return 0;
+	}
+	return 1;
+}
+
+static unsigned int
+target(struct sk_buff **pskb,
+       const struct net_device *in,
+       const struct net_device *out,
+       unsigned int hooknum,
+       const void *targinfo,
+       void *userinfo)
+{
+	struct ip_conntrack *ct;
+	enum ip_conntrack_info ctinfo;
+	u_int32_t new_ip, netmask;
+	const struct ip_nat_multi_range_compat *mr = targinfo;
+	struct ip_nat_range newrange;
+
+	IP_NF_ASSERT(hooknum == NF_IP_PRE_ROUTING
+		     || hooknum == NF_IP_POST_ROUTING);
+	ct = ip_conntrack_get(*pskb, &ctinfo);
+
+	netmask = ~(mr->range[0].min_ip ^ mr->range[0].max_ip);
+
+	if (hooknum == NF_IP_PRE_ROUTING)
+		new_ip = (*pskb)->nh.iph->daddr & ~netmask;
+	else
+		new_ip = (*pskb)->nh.iph->saddr & ~netmask;
+	new_ip |= mr->range[0].min_ip & netmask;
+
+	newrange = ((struct ip_nat_range)
+		{ mr->range[0].flags | IP_NAT_RANGE_MAP_IPS,
+		  new_ip, new_ip,
+		  mr->range[0].min, mr->range[0].max });
+
+	/* Hand modified range to generic setup. */
+	return ip_nat_setup_info(ct, &newrange, hooknum);
+}
+
+static struct ipt_target target_module = { 
+	.name 		= MODULENAME,
+	.target 	= target, 
+	.checkentry 	= check,
+    	.me 		= THIS_MODULE 
+};
+
+static int __init init(void)
+{
+	return ipt_register_target(&target_module);
+}
+
+static void __exit fini(void)
+{
+	ipt_unregister_target(&target_module);
+}
+
+module_init(init);
+module_exit(fini);