Fix persistent_client_expiration not being used

Closes #1494. Thanks to Christoph Krey.

ChangeLog.txt

@@ -15,6 +15,9 @@ Broker:
   property just before they were expired. Closes #1464.
 - Fix TLS Websockets clients not receiving messages after taking over a
   previous connection. Closes #1489.
+- Fix MQTT 3.1.1 clients using clean session false, or MQTT 5.0 clients using
+  session-expiry-interval set to infinity never expiring, even when the global
+  `persistent_client_expiration` option was set. Closes #1494.
 
 Client library:
 - Fix publish properties not being passed to on_message_v5 callback for QoS 2

src/context.c

@@ -230,7 +230,7 @@ void context__disconnect(struct mosquitto_db *db, struct mosquitto *context)
 
 	context__send_will(db, context);
 	if(context->session_expiry_interval == 0){
-
+		/* Client session is due to be expired now */
 #ifdef WITH_BRIDGE
 		if(!context->bridge)
 #endif

src/session_expiry.c

@@ -38,17 +38,32 @@ int session_expiry__add(struct mosquitto_db *db, struct mosquitto *context)
 {
 	struct session_expiry_list *item;
 
+	if(db->config->persistent_client_expiration == 0){
+		if(context->session_expiry_interval == UINT32_MAX){
+			/* There isn't a global expiry set, and the client has asked to
+			 * never expire, so we don't add it to the list. */
+			return MOSQ_ERR_SUCCESS;
+		}
+	}
+
 	item = mosquitto__calloc(1, sizeof(struct session_expiry_list));
 	if(!item) return MOSQ_ERR_NOMEM;
 
 	item->context = context;
 	item->context->session_expiry_time = time(NULL);
-	if(db->config->persistent_client_expiration == 0 || 
-			db->config->persistent_client_expiration < item->context->session_expiry_interval){
 
+	if(db->config->persistent_client_expiration == 0){
+		/* No global expiry, so use the client expiration interval */
 		item->context->session_expiry_time += item->context->session_expiry_interval;
 	}else{
-		item->context->session_expiry_time += db->config->persistent_client_expiration;
+		/* We have a global expiry interval */
+		if(db->config->persistent_client_expiration < item->context->session_expiry_interval){
+			/* The client expiry is longer than the global expiry, so use the global */
+			item->context->session_expiry_time += db->config->persistent_client_expiration;
+		}else{
+			/* The global expiry is longer than the client expiry, so use the client */
+			item->context->session_expiry_time += item->context->session_expiry_interval;
+		}
 	}
 	context->expiry_list_item = item;
 
@@ -95,8 +110,7 @@ void session_expiry__check(struct mosquitto_db *db, time_t now)
 	last_check = now;
 
 	DL_FOREACH_SAFE(expiry_list, item, tmp){
-		if(item->context->session_expiry_interval != UINT32_MAX
-				&& item->context->session_expiry_time < now){
+		if(item->context->session_expiry_time < now){
 
 			context = item->context;
 			session_expiry__remove(context);