netfilter: add protocol independent NAT core
Convert the IPv4 NAT implementation to a protocol independent core and
address family specific modules.
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/netfilter/nf_nat_proto_udp.c b/net/netfilter/nf_nat_proto_udp.c
new file mode 100644
index 0000000..7df613f
--- /dev/null
+++ b/net/netfilter/nf_nat_proto_udp.c
@@ -0,0 +1,76 @@
+/* (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/export.h>
+#include <linux/init.h>
+#include <linux/udp.h>
+
+#include <linux/netfilter.h>
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/nf_nat_core.h>
+#include <net/netfilter/nf_nat_l3proto.h>
+#include <net/netfilter/nf_nat_l4proto.h>
+
+static u16 udp_port_rover;
+
+static void
+udp_unique_tuple(const struct nf_nat_l3proto *l3proto,
+ struct nf_conntrack_tuple *tuple,
+ const struct nf_nat_range *range,
+ enum nf_nat_manip_type maniptype,
+ const struct nf_conn *ct)
+{
+ nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
+ &udp_port_rover);
+}
+
+static bool
+udp_manip_pkt(struct sk_buff *skb,
+ const struct nf_nat_l3proto *l3proto,
+ unsigned int iphdroff, unsigned int hdroff,
+ const struct nf_conntrack_tuple *tuple,
+ enum nf_nat_manip_type maniptype)
+{
+ struct udphdr *hdr;
+ __be16 *portptr, newport;
+
+ if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
+ return false;
+ hdr = (struct udphdr *)(skb->data + hdroff);
+
+ if (maniptype == NF_NAT_MANIP_SRC) {
+ /* Get rid of src port */
+ newport = tuple->src.u.udp.port;
+ portptr = &hdr->source;
+ } else {
+ /* Get rid of dst port */
+ newport = tuple->dst.u.udp.port;
+ portptr = &hdr->dest;
+ }
+ if (hdr->check || skb->ip_summed == CHECKSUM_PARTIAL) {
+ l3proto->csum_update(skb, iphdroff, &hdr->check,
+ tuple, maniptype);
+ inet_proto_csum_replace2(&hdr->check, skb, *portptr, newport,
+ 0);
+ if (!hdr->check)
+ hdr->check = CSUM_MANGLED_0;
+ }
+ *portptr = newport;
+ return true;
+}
+
+const struct nf_nat_l4proto nf_nat_l4proto_udp = {
+ .l4proto = IPPROTO_UDP,
+ .manip_pkt = udp_manip_pkt,
+ .in_range = nf_nat_l4proto_in_range,
+ .unique_tuple = udp_unique_tuple,
+#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
+ .nlattr_to_range = nf_nat_l4proto_nlattr_to_range,
+#endif
+};