[NETFILTER]: nf_conntrack/nf_nat: add amanda helper port
Add IPv4 and IPv6 capable nf_conntrack port of the Amanda conntrack/NAT helper.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/netfilter/nf_nat_amanda.c b/net/ipv4/netfilter/nf_nat_amanda.c
new file mode 100644
index 0000000..0f17098
--- /dev/null
+++ b/net/ipv4/netfilter/nf_nat_amanda.c
@@ -0,0 +1,78 @@
+/* Amanda extension for TCP NAT alteration.
+ * (C) 2002 by Brian J. Murrell <netfilter@interlinx.bc.ca>
+ * based on a copy of HW's ip_nat_irc.c as well as other modules
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/udp.h>
+
+#include <net/netfilter/nf_nat_helper.h>
+#include <net/netfilter/nf_nat_rule.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <net/netfilter/nf_conntrack_expect.h>
+#include <linux/netfilter/nf_conntrack_amanda.h>
+
+MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>");
+MODULE_DESCRIPTION("Amanda NAT helper");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ip_nat_amanda");
+
+static unsigned int help(struct sk_buff **pskb,
+ enum ip_conntrack_info ctinfo,
+ unsigned int matchoff,
+ unsigned int matchlen,
+ struct nf_conntrack_expect *exp)
+{
+ char buffer[sizeof("65535")];
+ u_int16_t port;
+ unsigned int ret;
+
+ /* Connection comes from client. */
+ exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
+ exp->dir = IP_CT_DIR_ORIGINAL;
+
+ /* When you see the packet, we need to NAT it the same as the
+ * this one (ie. same IP: it will be TCP and master is UDP). */
+ exp->expectfn = nf_nat_follow_master;
+
+ /* Try to get same port: if not, try to change it. */
+ for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) {
+ exp->tuple.dst.u.tcp.port = htons(port);
+ if (nf_conntrack_expect_related(exp) == 0)
+ break;
+ }
+
+ if (port == 0)
+ return NF_DROP;
+
+ sprintf(buffer, "%u", port);
+ ret = nf_nat_mangle_udp_packet(pskb, exp->master, ctinfo,
+ matchoff, matchlen,
+ buffer, strlen(buffer));
+ if (ret != NF_ACCEPT)
+ nf_conntrack_unexpect_related(exp);
+ return ret;
+}
+
+static void __exit nf_nat_amanda_fini(void)
+{
+ rcu_assign_pointer(nf_nat_amanda_hook, NULL);
+ synchronize_rcu();
+}
+
+static int __init nf_nat_amanda_init(void)
+{
+ BUG_ON(rcu_dereference(nf_nat_amanda_hook));
+ rcu_assign_pointer(nf_nat_amanda_hook, help);
+ return 0;
+}
+
+module_init(nf_nat_amanda_init);
+module_exit(nf_nat_amanda_fini);