net: add helpers checking if socket can be bound to nonlocal address

The construction "net->ipv4.sysctl_ip_nonlocal_bind || inet->freebind
|| inet->transparent" is present three times and its IPv6 counterpart
is also present three times. We introduce two small helpers to
characterize these tests uniformly.

Signed-off-by: Vincent Bernat <vincent@bernat.im>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index 314be48..e03b933 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -359,4 +359,12 @@ static inline bool inet_get_convert_csum(struct sock *sk)
 	return !!inet_sk(sk)->convert_csum;
 }
 
+
+static inline bool inet_can_nonlocal_bind(struct net *net,
+					  struct inet_sock *inet)
+{
+	return net->ipv4.sysctl_ip_nonlocal_bind ||
+		inet->freebind || inet->transparent;
+}
+
 #endif	/* _INET_SOCK_H */