udp: Stop using RTO_ONLINK.

Use ip_sendmsg_scope() to properly initialise the scope in
flowi4_init_output(), instead of overriding tos with the RTO_ONLINK
flag. The objective is to eventually remove RTO_ONLINK, which will
allow converting .flowi4_tos to dscp_t.

Now that the scope is determined by ip_sendmsg_scope(), we need to
check its result to set the 'connected' variable.

Signed-off-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/udp.c

@@ -1062,8 +1062,8 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	int free = 0;
 	int connected = 0;
 	__be32 daddr, faddr, saddr;
+	u8 tos, scope;
 	__be16 dport;
-	u8  tos;
 	int err, is_udplite = IS_UDPLITE(sk);
 	int corkreq = READ_ONCE(up->corkflag) || msg->msg_flags&MSG_MORE;
 	int (*getfrag)(void *, char *, int, int, int, struct sk_buff *);
@@ -1183,12 +1183,9 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 		connected = 0;
 	}
 	tos = get_rttos(&ipc, inet);
-	if (sock_flag(sk, SOCK_LOCALROUTE) ||
-	    (msg->msg_flags & MSG_DONTROUTE) ||
-	    (ipc.opt && ipc.opt->opt.is_strictroute)) {
-		tos |= RTO_ONLINK;
+	scope = ip_sendmsg_scope(inet, &ipc, msg);
+	if (scope == RT_SCOPE_LINK)
 		connected = 0;
-	}
 
 	if (ipv4_is_multicast(daddr)) {
 		if (!ipc.oif || netif_index_is_l3_master(sock_net(sk), ipc.oif))
@@ -1221,11 +1218,9 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 
 		fl4 = &fl4_stack;
 
-		flowi4_init_output(fl4, ipc.oif, ipc.sockc.mark, tos,
-				   RT_SCOPE_UNIVERSE, sk->sk_protocol,
-				   flow_flags,
-				   faddr, saddr, dport, inet->inet_sport,
-				   sk->sk_uid);
+		flowi4_init_output(fl4, ipc.oif, ipc.sockc.mark, tos, scope,
+				   sk->sk_protocol, flow_flags, faddr, saddr,
+				   dport, inet->inet_sport, sk->sk_uid);
 
 		security_sk_classify_flow(sk, flowi4_to_flowi_common(fl4));
 		rt = ip_route_output_flow(net, fl4, sk);