[DCCP]: Move the IPv4 specific bits from proto.c to ipv4.c

With this patch in place we can break down the complexity by better
compartmentalizing the code that is common to ipv6 and ipv4.

Now we have these modules:
Module                  Size  Used by
dccp_diag               1344  0
inet_diag               9448  1 dccp_diag
dccp_ccid3             15856  0
dccp_tfrc_lib          12320  1 dccp_ccid3
dccp_ccid2              5764  0
dccp_ipv4              16996  2
dccp                   48208  4 dccp_diag,dccp_ccid3,dccp_ccid2,dccp_ipv4

dccp_ipv6 still requires dccp_ipv4 due to dccp_ipv6_mapped, that is
the next target to work on the "hey, ipv4 is legacy, I only want ipv6
dude!" direction.

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dccp/Makefile

@@ -2,10 +2,11 @@ obj-$(CONFIG_IPV6) += dccp_ipv6.o
 
 dccp_ipv6-y := ipv6.o
 
-obj-$(CONFIG_IP_DCCP) += dccp.o
+obj-$(CONFIG_IP_DCCP) += dccp.o dccp_ipv4.o
 
-dccp-y := ccid.o feat.o input.o ipv4.o minisocks.o options.o output.o proto.o \
-	  timer.o
+dccp-y := ccid.o feat.o input.o minisocks.o options.o output.o proto.o timer.o
+
+dccp_ipv4-y := ipv4.o
 
 dccp-$(CONFIG_IP_DCCP_ACKVEC) += ackvec.o
 

net/dccp/dccp.h

@@ -59,8 +59,6 @@ extern void dccp_time_wait(struct sock *sk, int state, int timeo);
 
 #define DCCP_RTO_MAX ((unsigned)(120 * HZ)) /* FIXME: using TCP value */
 
-extern struct proto dccp_prot;
-
 /* is seq1 < seq2 ? */
 static inline int before48(const u64 seq1, const u64 seq2)
 {
@@ -209,10 +207,6 @@ extern struct sock *dccp_create_openreq_child(struct sock *sk,
 
 extern int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
 
-extern void dccp_v4_err(struct sk_buff *skb, u32);
-
-extern int dccp_v4_rcv(struct sk_buff *skb);
-
 extern struct sock *dccp_v4_request_recv_sock(struct sock *sk,
 					      struct sk_buff *skb,
 					      struct request_sock *req,

net/dccp/ipv4.c

@@ -18,8 +18,10 @@
 #include <linux/random.h>
 
 #include <net/icmp.h>
+#include <net/inet_common.h>
 #include <net/inet_hashtables.h>
 #include <net/inet_sock.h>
+#include <net/protocol.h>
 #include <net/sock.h>
 #include <net/timewait_sock.h>
 #include <net/tcp_states.h>
@@ -285,7 +287,7 @@ static int dccp_v4_send_response(struct sock *sk, struct request_sock *req,
  * check at all. A more general error queue to queue errors for later handling
  * is probably better.
  */
-void dccp_v4_err(struct sk_buff *skb, u32 info)
+static void dccp_v4_err(struct sk_buff *skb, u32 info)
 {
 	const struct iphdr *iph = (struct iphdr *)skb->data;
 	const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data +
@@ -639,6 +641,8 @@ int dccp_v4_checksum(const struct sk_buff *skb, const __be32 saddr,
 				 IPPROTO_DCCP, tmp);
 }
 
+EXPORT_SYMBOL_GPL(dccp_v4_checksum);
+
 static int dccp_v4_verify_checksum(struct sk_buff *skb,
 				   const __be32 saddr, const __be32 daddr)
 {
@@ -871,7 +875,7 @@ int dccp_invalid_packet(struct sk_buff *skb)
 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
 
 /* this is called when real data arrives */
-int dccp_v4_rcv(struct sk_buff *skb)
+static int dccp_v4_rcv(struct sk_buff *skb)
 {
 	const struct dccp_hdr *dh;
 	struct sock *sk;
@@ -978,7 +982,7 @@ int dccp_v4_rcv(struct sk_buff *skb)
 	goto no_dccp_socket;
 }
 
-struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
+static struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
 	.queue_xmit	= ip_queue_xmit,
 	.send_check	= dccp_v4_send_check,
 	.rebuild_header	= inet_sk_rebuild_header,
@@ -1018,7 +1022,7 @@ static struct timewait_sock_ops dccp_timewait_sock_ops = {
 	.twsk_obj_size	= sizeof(struct inet_timewait_sock),
 };
 
-struct proto dccp_prot = {
+struct proto dccp_v4_prot = {
 	.name			= "DCCP",
 	.owner			= THIS_MODULE,
 	.close			= dccp_close,
@@ -1044,4 +1048,130 @@ struct proto dccp_prot = {
 	.twsk_prot		= &dccp_timewait_sock_ops,
 };
 
-EXPORT_SYMBOL_GPL(dccp_prot);
+static struct net_protocol dccp_v4_protocol = {
+	.handler	= dccp_v4_rcv,
+	.err_handler	= dccp_v4_err,
+	.no_policy	= 1,
+};
+
+static const struct proto_ops inet_dccp_ops = {
+	.family		= PF_INET,
+	.owner		= THIS_MODULE,
+	.release	= inet_release,
+	.bind		= inet_bind,
+	.connect	= inet_stream_connect,
+	.socketpair	= sock_no_socketpair,
+	.accept		= inet_accept,
+	.getname	= inet_getname,
+	/* FIXME: work on tcp_poll to rename it to inet_csk_poll */
+	.poll		= dccp_poll,
+	.ioctl		= inet_ioctl,
+	/* FIXME: work on inet_listen to rename it to sock_common_listen */
+	.listen		= inet_dccp_listen,
+	.shutdown	= inet_shutdown,
+	.setsockopt	= sock_common_setsockopt,
+	.getsockopt	= sock_common_getsockopt,
+	.sendmsg	= inet_sendmsg,
+	.recvmsg	= sock_common_recvmsg,
+	.mmap		= sock_no_mmap,
+	.sendpage	= sock_no_sendpage,
+};
+
+static struct inet_protosw dccp_v4_protosw = {
+	.type		= SOCK_DCCP,
+	.protocol	= IPPROTO_DCCP,
+	.prot		= &dccp_v4_prot,
+	.ops		= &inet_dccp_ops,
+	.capability	= -1,
+	.no_check	= 0,
+	.flags		= INET_PROTOSW_ICSK,
+};
+
+/*
+ * This is the global socket data structure used for responding to
+ * the Out-of-the-blue (OOTB) packets. A control sock will be created
+ * for this socket at the initialization time.
+ */
+struct socket *dccp_ctl_socket;
+
+static char dccp_ctl_socket_err_msg[] __initdata =
+	KERN_ERR "DCCP: Failed to create the control socket.\n";
+
+static int __init dccp_ctl_sock_init(void)
+{
+	int rc = sock_create_kern(PF_INET, SOCK_DCCP, IPPROTO_DCCP,
+				  &dccp_ctl_socket);
+	if (rc < 0)
+		printk(dccp_ctl_socket_err_msg);
+	else {
+		dccp_ctl_socket->sk->sk_allocation = GFP_ATOMIC;
+		inet_sk(dccp_ctl_socket->sk)->uc_ttl = -1;
+
+		/* Unhash it so that IP input processing does not even
+		 * see it, we do not wish this socket to see incoming
+		 * packets.
+		 */
+		dccp_ctl_socket->sk->sk_prot->unhash(dccp_ctl_socket->sk);
+	}
+
+	return rc;
+}
+
+#ifdef CONFIG_IP_DCCP_UNLOAD_HACK
+void dccp_ctl_sock_exit(void)
+{
+	if (dccp_ctl_socket != NULL) {
+		sock_release(dccp_ctl_socket);
+		dccp_ctl_socket = NULL;
+	}
+}
+
+EXPORT_SYMBOL_GPL(dccp_ctl_sock_exit);
+#endif
+
+static int __init dccp_v4_init(void)
+{
+	int err = proto_register(&dccp_v4_prot, 1);
+
+	if (err != 0)
+		goto out;
+
+	err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
+	if (err != 0)
+		goto out_proto_unregister;
+
+	inet_register_protosw(&dccp_v4_protosw);
+
+	err = dccp_ctl_sock_init();
+	if (err)
+		goto out_unregister_protosw;
+out:
+	return err;
+out_unregister_protosw:
+	inet_unregister_protosw(&dccp_v4_protosw);
+	inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
+out_proto_unregister:
+	proto_unregister(&dccp_v4_prot);
+	goto out;
+}
+
+static void __exit dccp_v4_exit(void)
+{
+	inet_unregister_protosw(&dccp_v4_protosw);
+	inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
+	proto_unregister(&dccp_v4_prot);
+}
+
+module_init(dccp_v4_init);
+module_exit(dccp_v4_exit);
+
+/*
+ * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
+ * values directly, Also cover the case where the protocol is not specified,
+ * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
+ */
+MODULE_ALIAS("net-pf-" __stringify(PF_INET) "-proto-33-type-6");
+MODULE_ALIAS("net-pf-" __stringify(PF_INET) "-proto-0-type-6");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
+MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");

net/dccp/options.c

@@ -258,6 +258,8 @@ int dccp_parse_options(struct sock *sk, struct sk_buff *skb)
 	return -1;
 }
 
+EXPORT_SYMBOL_GPL(dccp_parse_options);
+
 static void dccp_encode_value_var(const u32 value, unsigned char *to,
 				  const unsigned int len)
 {

net/dccp/output.c

@@ -526,6 +526,8 @@ void dccp_send_sync(struct sock *sk, const u64 seq,
 	dccp_transmit_skb(sk, skb);
 }
 
+EXPORT_SYMBOL_GPL(dccp_send_sync);
+
 /*
  * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This
  * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under