-extern config_t *lookup_config(avl_tree_t *, char *);
-extern config_t *lookup_config_next(avl_tree_t *, config_t *);
-extern int get_config_bool(config_t *, int *);
-extern int get_config_int(config_t *, int *);
-extern int get_config_port(config_t *, port_t *);
-extern int get_config_string(config_t *, char **);
-extern int get_config_address(config_t *, struct addrinfo **);
-struct subnet_t; /* Needed for next line. */
-extern int get_config_subnet(config_t *, struct subnet_t **);
+extern config_t *lookup_config(const avl_tree_t *, char *);
+extern config_t *lookup_config_next(const avl_tree_t *, const config_t *);
+extern bool get_config_bool(const config_t *, bool *);
+extern bool get_config_int(const config_t *, int *);
+extern bool get_config_string(const config_t *, char **);
+extern bool get_config_address(const config_t *, struct addrinfo **);
+extern bool get_config_subnet(const config_t *, struct subnet_t **);