Added retain flag for publishing

Adafruit_MQTT.cpp

@@ -293,13 +293,13 @@ bool Adafruit_MQTT::disconnect() {
 }
 
 
-bool Adafruit_MQTT::publish(const char *topic, const char *data, uint8_t qos) {
+bool Adafruit_MQTT::publish(const char *topic, const char *data, uint8_t qos, uint8_t retain) {
-    return publish(topic, (uint8_t*)(data), strlen(data), qos);
+    return publish(topic, (uint8_t*)(data), strlen(data), qos, retain);
 }
 
-bool Adafruit_MQTT::publish(const char *topic, uint8_t *data, uint16_t bLen, uint8_t qos) {
+bool Adafruit_MQTT::publish(const char *topic, uint8_t *data, uint16_t bLen, uint8_t qos, uint8_t retain) {
   // Construct and send publish packet.
-  uint16_t len = publishPacket(buffer, topic, data, bLen, qos);
+  uint16_t len = publishPacket(buffer, topic, data, bLen, qos, retain);
   if (!sendPacket(buffer, len))
     return false;
 
@@ -634,7 +634,7 @@ uint8_t Adafruit_MQTT::connectPacket(uint8_t *packet) {
 
 // as per http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Toc398718040
 uint16_t Adafruit_MQTT::publishPacket(uint8_t *packet, const char *topic,
-                                     uint8_t *data, uint16_t bLen, uint8_t qos) {
+                                     uint8_t *data, uint16_t bLen, uint8_t qos, uint8_t retain) {
   uint8_t *p = packet;
   uint16_t len=0;
 
@@ -647,7 +647,7 @@ uint16_t Adafruit_MQTT::publishPacket(uint8_t *packet, const char *topic,
   len += bLen; // payload length
 
   // Now you can start generating the packet!
-  p[0] = MQTT_CTRL_PUBLISH << 4 | qos << 1;
+  p[0] = MQTT_CTRL_PUBLISH << 4 | qos << 1 | (retain ? 1 : 0);
   p++;
 
   // fill in packet[1] last
@@ -770,37 +770,38 @@ uint8_t Adafruit_MQTT::disconnectPacket(uint8_t *packet) {
 // Adafruit_MQTT_Publish Definition ////////////////////////////////////////////
 
 Adafruit_MQTT_Publish::Adafruit_MQTT_Publish(Adafruit_MQTT *mqttserver,
-                                             const char *feed, uint8_t q) {
+                                             const char *feed, uint8_t q, uint8_t r) {
   mqtt = mqttserver;
   topic = feed;
   qos = q;
+  retain = r;
 }
 bool Adafruit_MQTT_Publish::publish(int32_t i) {
   char payload[12];
   ltoa(i, payload, 10);
-  return mqtt->publish(topic, payload, qos);
+  return mqtt->publish(topic, payload, qos, retain);
 }
 
 bool Adafruit_MQTT_Publish::publish(uint32_t i) {
   char payload[11];
   ultoa(i, payload, 10);
-  return mqtt->publish(topic, payload, qos);
+  return mqtt->publish(topic, payload, qos, retain);
 }
 
 bool Adafruit_MQTT_Publish::publish(double f, uint8_t precision) {
   char payload[41];  // Need to technically hold float max, 39 digits and minus sign.
   dtostrf(f, 0, precision, payload);
-  return mqtt->publish(topic, payload, qos);
+  return mqtt->publish(topic, payload, qos, retain);
 }
 
 bool Adafruit_MQTT_Publish::publish(const char *payload) {
-  return mqtt->publish(topic, payload, qos);
+  return mqtt->publish(topic, payload, qos, retain);
 }
 
 //publish buffer of arbitrary length
 bool Adafruit_MQTT_Publish::publish(uint8_t *payload, uint16_t bLen) {
 
-  return mqtt->publish(topic, payload, bLen, qos);
+  return mqtt->publish(topic, payload, bLen, qos, retain);
 }
 
 

Adafruit_MQTT.h

@@ -178,8 +178,8 @@ class Adafruit_MQTT {
 
   // Publish a message to a topic using the specified QoS level.  Returns true
   // if the message was published, false otherwise.
-  bool publish(const char *topic, const char *payload, uint8_t qos = 0);
+  bool publish(const char *topic, const char *payload, uint8_t qos = 0, uint8_t retrain = 0);
-  bool publish(const char *topic, uint8_t *payload, uint16_t bLen, uint8_t qos = 0);
+  bool publish(const char *topic, uint8_t *payload, uint16_t bLen, uint8_t qos = 0, uint8_t retrain = 0);
 
   // Add a subscription to receive messages for a topic.  Returns true if the
   // subscription could be added or was already present, false otherwise.
@@ -244,7 +244,7 @@ class Adafruit_MQTT {
   // Functions to generate MQTT packets.
   uint8_t connectPacket(uint8_t *packet);
   uint8_t disconnectPacket(uint8_t *packet);
-  uint16_t publishPacket(uint8_t *packet, const char *topic, uint8_t *payload, uint16_t bLen, uint8_t qos);
+  uint16_t publishPacket(uint8_t *packet, const char *topic, uint8_t *payload, uint16_t bLen, uint8_t qos, uint8_t retain);
   uint8_t subscribePacket(uint8_t *packet, const char *topic, uint8_t qos);
   uint8_t unsubscribePacket(uint8_t *packet, const char *topic);
   uint8_t pingPacket(uint8_t *packet);
@@ -254,7 +254,7 @@ class Adafruit_MQTT {
 
 class Adafruit_MQTT_Publish {
  public:
-  Adafruit_MQTT_Publish(Adafruit_MQTT *mqttserver, const char *feed, uint8_t qos = 0);
+  Adafruit_MQTT_Publish(Adafruit_MQTT *mqttserver, const char *feed, uint8_t qos = 0, uint8_t retain = 0);
 
   bool publish(const char *s);
   bool publish(double f, uint8_t precision=2);  // Precision controls the minimum number of digits after decimal.
@@ -268,6 +268,7 @@ private:
   Adafruit_MQTT *mqtt;
   const char *topic;
   uint8_t qos;
+  uint8_t retain;
 };
 
 class Adafruit_MQTT_Subscribe {