Fix minor Coverity issues

1400727 - unused value
1400726 - dereference after null check
1400728 - derefence before null check

lib/send_mosq.c

@@ -58,9 +58,9 @@ int send__pingreq(struct mosquitto *mosq)
 int send__pingresp(struct mosquitto *mosq)
 {
 #ifdef WITH_BROKER
-	if(mosq) log__printf(NULL, MOSQ_LOG_DEBUG, "Sending PINGRESP to %s", mosq->id);
+	log__printf(NULL, MOSQ_LOG_DEBUG, "Sending PINGRESP to %s", mosq->id);
 #else
-	if(mosq) log__printf(mosq, MOSQ_LOG_DEBUG, "Client %s sending PINGRESP", mosq->id);
+	log__printf(mosq, MOSQ_LOG_DEBUG, "Client %s sending PINGRESP", mosq->id);
 #endif
 	return send__simple_command(mosq, CMD_PINGRESP);
 }
@@ -93,9 +93,9 @@ int send__pubcomp(struct mosquitto *mosq, uint16_t mid)
 int send__pubrec(struct mosquitto *mosq, uint16_t mid, uint8_t reason_code)
 {
 #ifdef WITH_BROKER
-	if(mosq) log__printf(NULL, MOSQ_LOG_DEBUG, "Sending PUBREC to %s (m%d, rc%d)", mosq->id, mid, reason_code);
+	log__printf(NULL, MOSQ_LOG_DEBUG, "Sending PUBREC to %s (m%d, rc%d)", mosq->id, mid, reason_code);
 #else
-	if(mosq) log__printf(mosq, MOSQ_LOG_DEBUG, "Client %s sending PUBREC (m%d, rc%d)", mosq->id, mid, reason_code);
+	log__printf(mosq, MOSQ_LOG_DEBUG, "Client %s sending PUBREC (m%d, rc%d)", mosq->id, mid, reason_code);
 #endif
 	if(reason_code >= 0x80 && mosq->protocol == mosq_p_mqtt5){
 		util__increment_receive_quota(mosq);
@@ -107,9 +107,9 @@ int send__pubrec(struct mosquitto *mosq, uint16_t mid, uint8_t reason_code)
 int send__pubrel(struct mosquitto *mosq, uint16_t mid)
 {
 #ifdef WITH_BROKER
-	if(mosq) log__printf(NULL, MOSQ_LOG_DEBUG, "Sending PUBREL to %s (m%d)", mosq->id, mid);
+	log__printf(NULL, MOSQ_LOG_DEBUG, "Sending PUBREL to %s (m%d)", mosq->id, mid);
 #else
-	if(mosq) log__printf(mosq, MOSQ_LOG_DEBUG, "Client %s sending PUBREL (m%d)", mosq->id, mid);
+	log__printf(mosq, MOSQ_LOG_DEBUG, "Client %s sending PUBREL (m%d)", mosq->id, mid);
 #endif
 	/* We don't use Reason String or User Property yet. */
 	return send__command_with_mid(mosq, CMD_PUBREL|2, mid, false, 0, NULL);

src/database.c

@@ -941,7 +941,7 @@ int db__message_write(struct mosquitto_db *db, struct mosquitto *context)
 	int msg_count = 0;
 	mosquitto_property *cmsg_props = NULL, *store_props = NULL;
 	time_t now = 0;
-	uint32_t expiry_interval = 0;
+	uint32_t expiry_interval;
 
 	if(!context || context->sock == INVALID_SOCKET
 			|| (context->state == mosq_cs_connected && !context->id)){

src/handle_publish.c

@@ -164,7 +164,7 @@ int handle__publish(struct mosquitto_db *db, struct mosquitto *context)
 	}
 	mosquitto_property_free_all(&properties);
 
-	if(topic_alias == 0 || topic_alias > context->listener->max_topic_alias){
+	if(topic_alias == 0 || (context->listener && topic_alias > context->listener->max_topic_alias)){
 		mosquitto__free(topic);
 		send__disconnect(context, MQTT_RC_TOPIC_ALIAS_INVALID, NULL);
 		return MOSQ_ERR_PROTOCOL;