[INET]: Introduce inet_sk_rebuild_header

From tcp_v4_rebuild_header, that already was pretty generic, I only
needed to use sk->sk_protocol instead of the hardcoded IPPROTO_TCP and
establish the requirement that INET transport layer protocols that
want to use this function map TCP_SYN_SENT to its equivalent state.

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

include/linux/ip.h

@@ -196,6 +196,8 @@ static inline void inet_sk_copy_descendant(struct sock *sk_to,
 #endif
 #endif
 
+extern int inet_sk_rebuild_header(struct sock *sk);
+
 struct iphdr {
 #if defined(__LITTLE_ENDIAN_BITFIELD)
 	__u8	ihl:4,

include/net/tcp.h

@@ -799,8 +799,6 @@ extern void			tcp_parse_options(struct sk_buff *skb,
  *	TCP v4 functions exported for the inet6 API
  */
 
-extern int		       	tcp_v4_rebuild_header(struct sock *sk);
-
 extern int		       	tcp_v4_build_header(struct sock *sk, 
 						    struct sk_buff *skb);
 

net/ipv4/af_inet.c

@@ -951,6 +951,119 @@ void inet_unregister_protosw(struct inet_protosw *p)
 	}
 }
 
+/*
+ *      Shall we try to damage output packets if routing dev changes?
+ */
+
+int sysctl_ip_dynaddr;
+
+static int inet_sk_reselect_saddr(struct sock *sk)
+{
+	struct inet_sock *inet = inet_sk(sk);
+	int err;
+	struct rtable *rt;
+	__u32 old_saddr = inet->saddr;
+	__u32 new_saddr;
+	__u32 daddr = inet->daddr;
+
+	if (inet->opt && inet->opt->srr)
+		daddr = inet->opt->faddr;
+
+	/* Query new route. */
+	err = ip_route_connect(&rt, daddr, 0,
+			       RT_CONN_FLAGS(sk),
+			       sk->sk_bound_dev_if,
+			       sk->sk_protocol,
+			       inet->sport, inet->dport, sk);
+	if (err)
+		return err;
+
+	sk_setup_caps(sk, &rt->u.dst);
+
+	new_saddr = rt->rt_src;
+
+	if (new_saddr == old_saddr)
+		return 0;
+
+	if (sysctl_ip_dynaddr > 1) {
+		printk(KERN_INFO "%s(): shifting inet->"
+				 "saddr from %d.%d.%d.%d to %d.%d.%d.%d\n",
+		       __FUNCTION__,
+		       NIPQUAD(old_saddr),
+		       NIPQUAD(new_saddr));
+	}
+
+	inet->saddr = inet->rcv_saddr = new_saddr;
+
+	/*
+	 * XXX The only one ugly spot where we need to
+	 * XXX really change the sockets identity after
+	 * XXX it has entered the hashes. -DaveM
+	 *
+	 * Besides that, it does not check for connection
+	 * uniqueness. Wait for troubles.
+	 */
+	__sk_prot_rehash(sk);
+	return 0;
+}
+
+int inet_sk_rebuild_header(struct sock *sk)
+{
+	struct inet_sock *inet = inet_sk(sk);
+	struct rtable *rt = (struct rtable *)__sk_dst_check(sk, 0);
+	u32 daddr;
+	int err;
+
+	/* Route is OK, nothing to do. */
+	if (rt)
+		return 0;
+
+	/* Reroute. */
+	daddr = inet->daddr;
+	if (inet->opt && inet->opt->srr)
+		daddr = inet->opt->faddr;
+{
+	struct flowi fl = {
+		.oif = sk->sk_bound_dev_if,
+		.nl_u = {
+			.ip4_u = {
+				.daddr	= daddr,
+				.saddr	= inet->saddr,
+				.tos	= RT_CONN_FLAGS(sk),
+			},
+		},
+		.proto = sk->sk_protocol,
+		.uli_u = {
+			.ports = {
+				.sport = inet->sport,
+				.dport = inet->dport,
+			},
+		},
+	};
+						
+	err = ip_route_output_flow(&rt, &fl, sk, 0);
+}
+	if (!err)
+		sk_setup_caps(sk, &rt->u.dst);
+	else {
+		/* Routing failed... */
+		sk->sk_route_caps = 0;
+		/*
+		 * Other protocols have to map its equivalent state to TCP_SYN_SENT.
+		 * DCCP maps its DCCP_REQUESTING state to TCP_SYN_SENT. -acme
+		 */
+		if (!sysctl_ip_dynaddr ||
+		    sk->sk_state != TCP_SYN_SENT ||
+		    (sk->sk_userlocks & SOCK_BINDADDR_LOCK) ||
+		    (err = inet_sk_reselect_saddr(sk)) != 0)
+			sk->sk_err_soft = -err;
+	}
+
+	return err;
+}
+
+EXPORT_SYMBOL(inet_sk_rebuild_header);
+
 #ifdef CONFIG_IP_MULTICAST
 static struct net_protocol igmp_protocol = {
 	.handler =	igmp_rcv,

net/ipv4/ip_output.c

@@ -83,11 +83,6 @@
 #include <linux/netlink.h>
 #include <linux/tcp.h>
 
-/*
- *      Shall we try to damage output packets if routing dev changes?
- */
-
-int sysctl_ip_dynaddr;
 int sysctl_ip_default_ttl = IPDEFTTL;
 
 /* Generate a checksum for an outgoing IP datagram. */

net/ipv4/tcp_ipv4.c

@@ -1832,101 +1832,6 @@ do_time_wait:
 	goto discard_it;
 }
 
-static int tcp_v4_reselect_saddr(struct sock *sk)
-{
-	struct inet_sock *inet = inet_sk(sk);
-	int err;
-	struct rtable *rt;
-	__u32 old_saddr = inet->saddr;
-	__u32 new_saddr;
-	__u32 daddr = inet->daddr;
-
-	if (inet->opt && inet->opt->srr)
-		daddr = inet->opt->faddr;
-
-	/* Query new route. */
-	err = ip_route_connect(&rt, daddr, 0,
-			       RT_CONN_FLAGS(sk),
-			       sk->sk_bound_dev_if,
-			       IPPROTO_TCP,
-			       inet->sport, inet->dport, sk);
-	if (err)
-		return err;
-
-	sk_setup_caps(sk, &rt->u.dst);
-
-	new_saddr = rt->rt_src;
-
-	if (new_saddr == old_saddr)
-		return 0;
-
-	if (sysctl_ip_dynaddr > 1) {
-		printk(KERN_INFO "tcp_v4_rebuild_header(): shifting inet->"
-				 "saddr from %d.%d.%d.%d to %d.%d.%d.%d\n",
-		       NIPQUAD(old_saddr),
-		       NIPQUAD(new_saddr));
-	}
-
-	inet->saddr = new_saddr;
-	inet->rcv_saddr = new_saddr;
-
-	/* XXX The only one ugly spot where we need to
-	 * XXX really change the sockets identity after
-	 * XXX it has entered the hashes. -DaveM
-	 *
-	 * Besides that, it does not check for connection
-	 * uniqueness. Wait for troubles.
-	 */
-	__sk_prot_rehash(sk);
-	return 0;
-}
-
-int tcp_v4_rebuild_header(struct sock *sk)
-{
-	struct inet_sock *inet = inet_sk(sk);
-	struct rtable *rt = (struct rtable *)__sk_dst_check(sk, 0);
-	u32 daddr;
-	int err;
-
-	/* Route is OK, nothing to do. */
-	if (rt)
-		return 0;
-
-	/* Reroute. */
-	daddr = inet->daddr;
-	if (inet->opt && inet->opt->srr)
-		daddr = inet->opt->faddr;
-
-	{
-		struct flowi fl = { .oif = sk->sk_bound_dev_if,
-				    .nl_u = { .ip4_u =
-					      { .daddr = daddr,
-						.saddr = inet->saddr,
-						.tos = RT_CONN_FLAGS(sk) } },
-				    .proto = IPPROTO_TCP,
-				    .uli_u = { .ports =
-					       { .sport = inet->sport,
-						 .dport = inet->dport } } };
-						
-		err = ip_route_output_flow(&rt, &fl, sk, 0);
-	}
-	if (!err) {
-		sk_setup_caps(sk, &rt->u.dst);
-		return 0;
-	}
-
-	/* Routing failed... */
-	sk->sk_route_caps = 0;
-
-	if (!sysctl_ip_dynaddr ||
-	    sk->sk_state != TCP_SYN_SENT ||
-	    (sk->sk_userlocks & SOCK_BINDADDR_LOCK) ||
-	    (err = tcp_v4_reselect_saddr(sk)) != 0)
-		sk->sk_err_soft = -err;
-
-	return err;
-}
-
 static void v4_addr2sockaddr(struct sock *sk, struct sockaddr * uaddr)
 {
 	struct sockaddr_in *sin = (struct sockaddr_in *) uaddr;
@@ -1998,7 +1903,7 @@ int tcp_v4_tw_remember_stamp(struct tcp_tw_bucket *tw)
 struct tcp_func ipv4_specific = {
 	.queue_xmit	=	ip_queue_xmit,
 	.send_check	=	tcp_v4_send_check,
-	.rebuild_header	=	tcp_v4_rebuild_header,
+	.rebuild_header	=	inet_sk_rebuild_header,
 	.conn_request	=	tcp_v4_conn_request,
 	.syn_recv_sock	=	tcp_v4_syn_recv_sock,
 	.remember_stamp	=	tcp_v4_remember_stamp,
@@ -2630,7 +2535,6 @@ EXPORT_SYMBOL(tcp_unhash);
 EXPORT_SYMBOL(tcp_v4_conn_request);
 EXPORT_SYMBOL(tcp_v4_connect);
 EXPORT_SYMBOL(tcp_v4_do_rcv);
-EXPORT_SYMBOL(tcp_v4_rebuild_header);
 EXPORT_SYMBOL(tcp_v4_remember_stamp);
 EXPORT_SYMBOL(tcp_v4_send_check);
 EXPORT_SYMBOL(tcp_v4_syn_recv_sock);

net/ipv6/tcp_ipv6.c

@@ -1983,7 +1983,7 @@ static struct tcp_func ipv6_specific = {
 static struct tcp_func ipv6_mapped = {
 	.queue_xmit	=	ip_queue_xmit,
 	.send_check	=	tcp_v4_send_check,
-	.rebuild_header	=	tcp_v4_rebuild_header,
+	.rebuild_header	=	inet_sk_rebuild_header,
 	.conn_request	=	tcp_v6_conn_request,
 	.syn_recv_sock	=	tcp_v6_syn_recv_sock,
 	.remember_stamp	=	tcp_v4_remember_stamp,