network: loc_network_subnets: Use correct prefix

The prefix is being stored as a total number of bits now since it is
easier for any bitwise maths later. This is however causing an incorrect
prefix being computed when splitting a network into two subnets for
IPv4.

To get the correct prefix, loc_network_prefix must be called.

Introduced in 1fd09d0bReported-by: Valter Jansons <valter.jansons@gmail.com>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>

src/network.c

@@ -312,7 +312,7 @@ LOC_EXPORT int loc_network_subnets(struct loc_network* network,
 	*subnet2 = NULL;
 
 	// New prefix length
-	unsigned int prefix = network->prefix + 1;
+	unsigned int prefix = loc_network_prefix(network) + 1;
 
 	// Check if the new prefix is valid
 	if (!loc_address_valid_prefix(&network->first_address, prefix)) {