Make it easy to check if an address is locally usable via changed get_interface() method

src/libhydra/kernel/kernel_interface.c

@@ -291,14 +291,14 @@ METHOD(kernel_interface_t, get_nexthop, host_t*,
 	return this->net->get_nexthop(this->net, dest, src);
 }
 
-METHOD(kernel_interface_t, get_interface, char*,
-	private_kernel_interface_t *this, host_t *host)
+METHOD(kernel_interface_t, get_interface, bool,
+	private_kernel_interface_t *this, host_t *host, char **name)
 {
 	if (!this->net)
 	{
 		return NULL;
 	}
-	return this->net->get_interface(this->net, host);
+	return this->net->get_interface(this->net, host, name);
 }
 
 METHOD(kernel_interface_t, create_address_enumerator, enumerator_t*,

src/libhydra/kernel/kernel_interface.h

@@ -308,9 +308,10 @@ struct kernel_interface_t {
 	 * Get the interface name of a local address.
 	 *
 	 * @param host			address to get interface name from
-	 * @return				allocated interface name, or NULL if not found
+	 * @param name			allocated interface name (optional)
+	 * @return				TRUE if interface found and usable
 	 */
-	char* (*get_interface) (kernel_interface_t *this, host_t *host);
+	bool (*get_interface) (kernel_interface_t *this, host_t *host, char **name);
 
 	/**
 	 * Creates an enumerator over all local addresses.

src/libhydra/kernel/kernel_net.h

@@ -68,9 +68,10 @@ struct kernel_net_t {
 	 * Get the interface name of a local address.
 	 *
 	 * @param host			address to get interface name from
-	 * @return				allocated interface name, or NULL if not found
+	 * @param name			allocated interface name (optional)
+	 * @return				TRUE if interface found and usable
 	 */
-	char* (*get_interface) (kernel_net_t *this, host_t *host);
+	bool (*get_interface) (kernel_net_t *this, host_t *host, char **name);
 
 	/**
 	 * Creates an enumerator over all local addresses.