From 5b1158e909ecbe1a052203e0d8df15633f829930 Mon Sep 17 00:00:00 2001
From: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Date: Sat, 2 Dec 2006 22:07:13 -0800
Subject: [NETFILTER]: Add NAT support for nf_conntrack

Add NAT support for nf_conntrack. Joint work of Jozsef Kadlecsik,
Yasuyuki Kozakai, Martin Josefsson and myself.

Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/ipv4/netfilter/nf_nat_proto_icmp.c | 86 ++++++++++++++++++++++++++++++++++
 1 file changed, 86 insertions(+)
 create mode 100644 net/ipv4/netfilter/nf_nat_proto_icmp.c

(limited to 'net/ipv4/netfilter/nf_nat_proto_icmp.c')

diff --git a/net/ipv4/netfilter/nf_nat_proto_icmp.c b/net/ipv4/netfilter/nf_nat_proto_icmp.c
new file mode 100644
index 000000000000..dcfd772972d7
--- /dev/null
+++ b/net/ipv4/netfilter/nf_nat_proto_icmp.c
@@ -0,0 +1,86 @@
+/* (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
+ *
+ * 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/types.h>
+#include <linux/init.h>
+#include <linux/ip.h>
+#include <linux/icmp.h>
+
+#include <linux/netfilter.h>
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/nf_nat_core.h>
+#include <net/netfilter/nf_nat_rule.h>
+#include <net/netfilter/nf_nat_protocol.h>
+
+static int
+icmp_in_range(const struct nf_conntrack_tuple *tuple,
+	      enum nf_nat_manip_type maniptype,
+	      const union nf_conntrack_man_proto *min,
+	      const union nf_conntrack_man_proto *max)
+{
+	return ntohs(tuple->src.u.icmp.id) >= ntohs(min->icmp.id) &&
+	       ntohs(tuple->src.u.icmp.id) <= ntohs(max->icmp.id);
+}
+
+static int
+icmp_unique_tuple(struct nf_conntrack_tuple *tuple,
+		  const struct nf_nat_range *range,
+		  enum nf_nat_manip_type maniptype,
+		  const struct nf_conn *ct)
+{
+	static u_int16_t id;
+	unsigned int range_size;
+	unsigned int i;
+
+	range_size = ntohs(range->max.icmp.id) - ntohs(range->min.icmp.id) + 1;
+	/* If no range specified... */
+	if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED))
+		range_size = 0xFFFF;
+
+	for (i = 0; i < range_size; i++, id++) {
+		tuple->src.u.icmp.id = htons(ntohs(range->min.icmp.id) +
+		                             (id % range_size));
+		if (!nf_nat_used_tuple(tuple, ct))
+			return 1;
+	}
+	return 0;
+}
+
+static int
+icmp_manip_pkt(struct sk_buff **pskb,
+	       unsigned int iphdroff,
+	       const struct nf_conntrack_tuple *tuple,
+	       enum nf_nat_manip_type maniptype)
+{
+	struct iphdr *iph = (struct iphdr *)((*pskb)->data + iphdroff);
+	struct icmphdr *hdr;
+	unsigned int hdroff = iphdroff + iph->ihl*4;
+
+	if (!skb_make_writable(pskb, hdroff + sizeof(*hdr)))
+		return 0;
+
+	hdr = (struct icmphdr *)((*pskb)->data + hdroff);
+	nf_proto_csum_replace2(&hdr->checksum, *pskb,
+			       hdr->un.echo.id, tuple->src.u.icmp.id, 0);
+	hdr->un.echo.id = tuple->src.u.icmp.id;
+	return 1;
+}
+
+struct nf_nat_protocol nf_nat_protocol_icmp = {
+	.name			= "ICMP",
+	.protonum		= IPPROTO_ICMP,
+	.me			= THIS_MODULE,
+	.manip_pkt		= icmp_manip_pkt,
+	.in_range		= icmp_in_range,
+	.unique_tuple		= icmp_unique_tuple,
+#if defined(CONFIG_IP_NF_CONNTRACK_NETLINK) || \
+    defined(CONFIG_IP_NF_CONNTRACK_NETLINK_MODULE)
+	.range_to_nfattr	= nf_nat_port_range_to_nfattr,
+	.nfattr_to_range	= nf_nat_port_nfattr_to_range,
+#endif
+};
-- 
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