l2tp: Use ip4_datagram_connect() in l2tp_ip_connect()

Cleanup the l2tp_ip code to make use of an existing ipv4 support function.
Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/l2tp/l2tp_ip.c

@@ -299,67 +299,27 @@ static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len
 {
 	struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *) uaddr;
 	struct inet_sock *inet = inet_sk(sk);
-	struct flowi4 *fl4;
-	struct rtable *rt;
-	__be32 saddr;
-	int oif, rc;
+	int rc;
 
-	rc = -EINVAL;
 	if (addr_len < sizeof(*lsa))
-		goto out;
-
-	rc = -EAFNOSUPPORT;
-	if (lsa->l2tp_family != AF_INET)
-		goto out;
+		return -EINVAL;
 
-	lock_sock(sk);
-
-	sk_dst_reset(sk);
-
-	oif = sk->sk_bound_dev_if;
-	saddr = inet->inet_saddr;
-
-	rc = -EINVAL;
 	if (ipv4_is_multicast(lsa->l2tp_addr.s_addr))
-		goto out;
+		return -EINVAL;
 
-	fl4 = &inet->cork.fl.u.ip4;
-	rt = ip_route_connect(fl4, lsa->l2tp_addr.s_addr, saddr,
-			      RT_CONN_FLAGS(sk), oif,
-			      IPPROTO_L2TP,
-			      0, 0, sk, true);
-	if (IS_ERR(rt)) {
-		rc = PTR_ERR(rt);
-		if (rc == -ENETUNREACH)
-			IP_INC_STATS_BH(&init_net, IPSTATS_MIB_OUTNOROUTES);
-		goto out;
-	}
+	rc = ip4_datagram_connect(sk, uaddr, addr_len);
+	if (rc < 0)
+		return rc;
 
-	rc = -ENETUNREACH;
-	if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
-		ip_rt_put(rt);
-		goto out;
-	}
+	lock_sock(sk);
 
 	l2tp_ip_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
 
-	if (!inet->inet_saddr)
-		inet->inet_saddr = fl4->saddr;
-	if (!inet->inet_rcv_saddr)
-		inet->inet_rcv_saddr = fl4->saddr;
-	inet->inet_daddr = fl4->daddr;
-	sk->sk_state = TCP_ESTABLISHED;
-	inet->inet_id = jiffies;
-
-	sk_dst_set(sk, &rt->dst);
-
 	write_lock_bh(&l2tp_ip_lock);
 	hlist_del_init(&sk->sk_bind_node);
 	sk_add_bind_node(sk, &l2tp_ip_bind_table);
 	write_unlock_bh(&l2tp_ip_lock);
 
-	rc = 0;
-out:
 	release_sock(sk);
 	return rc;
 }