Fix #3636: enforce Wildcard Subscription Available gate on client side

lib/actions_subscribe.c

@@ -90,6 +90,11 @@ int mosquitto_subscribe_multiple(struct mosquitto *mosq, int *mid, int sub_count
 		if(mosquitto_validate_utf8(sub[i], slen)){
 			return MOSQ_ERR_MALFORMED_UTF8;
 		}
+		if(!mosq->wildcard_sub_available){
+			if(strchr(sub[i], '+') || strchr(sub[i], '#')){
+				return MOSQ_ERR_WILDCARD_SUBS_NOT_SUPPORTED;
+			}
+		}
 		remaining_length += 2+(uint32_t)slen + 1;
 	}
 

lib/connect.c

@@ -94,6 +94,7 @@ static int mosquitto__connect_init(struct mosquitto *mosq, const char *host, int
 	mosq->msgs_in.inflight_quota = mosq->msgs_in.inflight_maximum;
 	mosq->msgs_out.inflight_quota = mosq->msgs_out.inflight_maximum;
 	mosq->retain_available = 1;
+	mosq->wildcard_sub_available = 1;
 	mosquitto__set_request_disconnect(mosq, false);
 
 	return MOSQ_ERR_SUCCESS;

lib/handle_connack.c

@@ -102,6 +102,7 @@ int handle__connack(struct mosquitto *mosq)
 	}
 
 	mosquitto_property_read_byte(properties, MQTT_PROP_RETAIN_AVAILABLE, &mosq->retain_available, false);
+	mosquitto_property_read_byte(properties, MQTT_PROP_WILDCARD_SUB_AVAILABLE, &mosq->wildcard_sub_available, false);
 	mosquitto_property_read_byte(properties, MQTT_PROP_MAXIMUM_QOS, &mosq->max_qos, false);
 	mosquitto_property_read_int16(properties, MQTT_PROP_RECEIVE_MAXIMUM, &mosq->msgs_out.inflight_maximum, false);
 	mosquitto_property_read_int16(properties, MQTT_PROP_SERVER_KEEP_ALIVE, &mosq->keepalive, false);

lib/libmosquitto.c

@@ -206,6 +206,7 @@ int mosquitto_reinitialise(struct mosquitto *mosq, const char *id, bool clean_st
 	mosq->last_mid = 0;
 	mosq->state = mosq_cs_new;
 	mosq->max_qos = 2;
+	mosq->wildcard_sub_available = 1;
 	mosq->msgs_in.inflight_maximum = 20;
 	mosq->msgs_out.inflight_maximum = 20;
 	mosq->msgs_in.inflight_quota = 20;

lib/mosquitto_internal.h

@@ -451,6 +451,7 @@ struct mosquitto {
 #endif
 	uint8_t max_qos;
 	uint8_t retain_available;
+	uint8_t wildcard_sub_available;
 	bool tcp_nodelay;
 #if defined(WITH_WEBSOCKETS) && WITH_WEBSOCKETS == WS_IS_BUILTIN
 	char *http_request;

test/lib/c/02-subscribe-wildcard-unavailable-v5.c

@@ -0,0 +1,92 @@
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <mosquitto.h>
+
+static int run = -1;
+
+
+static void on_connect(struct mosquitto *mosq, void *obj, int rc)
+{
+	(void)obj;
+
+	if(rc){
+		exit(1);
+	}else{
+		/* Wildcard subscribe must be rejected client-side: CONNACK said = 0 */
+		rc = mosquitto_subscribe(mosq, NULL, "wildcard/+/rejected", 0);
+		if(rc != MOSQ_ERR_WILDCARD_SUBS_NOT_SUPPORTED){
+			run = 1;
+			return;
+		}
+		rc = mosquitto_subscribe(mosq, NULL, "wildcard/#", 0);
+		if(rc != MOSQ_ERR_WILDCARD_SUBS_NOT_SUPPORTED){
+			run = 1;
+			return;
+		}
+		/* Plain topic must succeed */
+		rc = mosquitto_subscribe(mosq, NULL, "plain/topic", 0);
+		if(rc != MOSQ_ERR_SUCCESS){
+			run = 1;
+		}
+	}
+}
+
+
+static void on_subscribe(struct mosquitto *mosq, void *obj, int mid, int qos_count, const int *granted_qos)
+{
+	(void)obj;
+	(void)mid;
+	(void)qos_count;
+	(void)granted_qos;
+
+	mosquitto_disconnect(mosq);
+}
+
+
+static void on_disconnect(struct mosquitto *mosq, void *obj, int rc)
+{
+	(void)mosq;
+	(void)obj;
+	(void)rc;
+
+	run = 0;
+}
+
+
+int main(int argc, char *argv[])
+{
+	int rc;
+	struct mosquitto *mosq;
+	int port;
+
+	if(argc < 2){
+		return 1;
+	}
+	port = atoi(argv[1]);
+
+	mosquitto_lib_init();
+
+	mosq = mosquitto_new("subscribe-wildcard-unavailable-test", true, NULL);
+	if(mosq == NULL){
+		return 1;
+	}
+	mosquitto_int_option(mosq, MOSQ_OPT_PROTOCOL_VERSION, MQTT_PROTOCOL_V5);
+	mosquitto_connect_callback_set(mosq, on_connect);
+	mosquitto_subscribe_callback_set(mosq, on_subscribe);
+	mosquitto_disconnect_callback_set(mosq, on_disconnect);
+
+	rc = mosquitto_connect(mosq, "localhost", port, 60);
+	if(rc != MOSQ_ERR_SUCCESS){
+		return rc;
+	}
+
+	while(run == -1){
+		mosquitto_loop(mosq, 50, 1);
+	}
+
+	mosquitto_destroy(mosq);
+	mosquitto_lib_cleanup();
+	return run;
+}