udp_diag: Basic skeleton

Introduce the transport level diag handler module for UDP (and UDP-lite)
sockets and register (empty for now) callbacks in the inet_diag module.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/udp_diag.c

+/*
+ * udp_diag.c	Module for monitoring UDP transport protocols sockets.
+ *
+ * Authors:	Pavel Emelyanov, <xemul@parallels.com>
+ *
+ *	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/module.h>
+#include <linux/inet_diag.h>
+#include <linux/udp.h>
+#include <net/udp.h>
+#include <net/udplite.h>
+#include <linux/inet_diag.h>
+#include <linux/sock_diag.h>
+
+static int udp_dump_one(struct udp_table *tbl, struct sk_buff *in_skb,
+		const struct nlmsghdr *nlh, struct inet_diag_req *req)
+{
+	return 0;
+}
+
+static void udp_dump(struct udp_table *table, struct sk_buff *skb, struct netlink_callback *cb,
+		struct inet_diag_req *r, struct nlattr *bc)
+{
+}
+
+static void udp_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
+		struct inet_diag_req *r, struct nlattr *bc)
+{
+	udp_dump(&udp_table, skb, cb, r, bc);
+}
+
+static int udp_diag_dump_one(struct sk_buff *in_skb, const struct nlmsghdr *nlh,
+		struct inet_diag_req *req)
+{
+	return udp_dump_one(&udp_table, in_skb, nlh, req);
+}
+
+static const struct inet_diag_handler udp_diag_handler = {
+	.dump		 = udp_diag_dump,
+	.dump_one	 = udp_diag_dump_one,
+	.idiag_type	 = IPPROTO_UDP,
+};
+
+static void udplite_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
+		struct inet_diag_req *r, struct nlattr *bc)
+{
+	udp_dump(&udplite_table, skb, cb, r, bc);
+}
+
+static int udplite_diag_dump_one(struct sk_buff *in_skb, const struct nlmsghdr *nlh,
+		struct inet_diag_req *req)
+{
+	return udp_dump_one(&udplite_table, in_skb, nlh, req);
+}
+
+static const struct inet_diag_handler udplite_diag_handler = {
+	.dump		 = udplite_diag_dump,
+	.dump_one	 = udplite_diag_dump_one,
+	.idiag_type	 = IPPROTO_UDPLITE,
+};
+
+static int __init udp_diag_init(void)
+{
+	int err;
+
+	err = inet_diag_register(&udp_diag_handler);
+	if (err)
+		goto out;
+	err = inet_diag_register(&udplite_diag_handler);
+	if (err)
+		goto out_lite;
+out:
+	return err;
+out_lite:
+	inet_diag_unregister(&udp_diag_handler);
+	goto out;
+}
+
+static void __exit udp_diag_exit(void)
+{
+	inet_diag_unregister(&udplite_diag_handler);
+	inet_diag_unregister(&udp_diag_handler);
+}
+
+module_init(udp_diag_init);
+module_exit(udp_diag_exit);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 17);
+MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 136);