Refactor Adafruit_MQTT to have a simple interface for packet sending & receiving that subclasses implement.

Adafruit_MQTT.h

@@ -7,6 +7,23 @@
  #include "WProgram.h"
 #endif
 
+// Uncomment/comment to turn on/off debug output messages.
+//#define MQTT_DEBUG
+
+// Set where debug messages will be printed.
+#define DEBUG_PRINTER Serial
+
+// Define actual debug output functions when necessary.
+#ifdef MQTT_DEBUG
+  #define DEBUG_PRINT(...) { DEBUG_PRINTER.print(__VA_ARGS__); }
+  #define DEBUG_PRINTLN(...) { DEBUG_PRINTER.println(__VA_ARGS__); }
+  #define DEBUG_PRINTBUFFER(buffer, len) { printBuffer(buffer, len); }
+#else
+  #define DEBUG_PRINT(...) {}
+  #define DEBUG_PRINTLN(...) {}
+  #define DEBUG_PRINTBUFFER(buffer, len) {}
+#endif
+
 #define MQTT_PROTOCOL_LEVEL 3
 
 #define MQTT_CTRL_CONNECT 0x01
@@ -22,13 +39,12 @@
 
 #define SERVERNAME_SIZE  25
 
-#define PASSWORD_SIZE  25
+#define PASSWORD_SIZE  50  // Need to be able to store an AIO key which is 41 chars.
 #define USERNAME_SIZE  41
-#define CLIENTID_SIZE 23
+#define CLIENTID_SIZE  23
 
 #define FEEDNAME_SIZE  40
 
-
 #define CONNECT_TIMEOUT_MS 3000
 #define PUBLISH_TIMEOUT_MS 500
 #define PING_TIMEOUT_MS 500
@@ -41,49 +57,90 @@
 #define MQTT_CONN_CLEANSESSION   0x02
 #define MQTT_CONN_KEEPALIVE 15  // in seconds
 
-#define MAXBUFFERSIZE (85)
+#define MAXBUFFERSIZE (105)  // Need to be able to store at least ~90 chars
+                             // for a connect packet with full 23 char client ID.
 #define MAXSUBSCRIPTIONS 5
 #define SUBSCRIPTIONDATALEN 20
 
 
-//#define DEBUG_MQTT_CONNECT
-//#define DEBUG_MQTT_SUBSCRIBE
-//#define DEBUG_MQTT_READSUB
-//#define DEBUG_MQTT_PUBLISH
-//#define DEBUG_MQTT_PACKETREAD
+extern void printBuffer(uint8_t *buffer, uint8_t len);
 
 class Adafruit_MQTT_Subscribe;  // forward decl
 
 class Adafruit_MQTT {
  public:
-  Adafruit_MQTT(const char *server, uint16_t port, const PROGMEM char *cid, const PROGMEM char *user, const PROGMEM char *pass);
+  Adafruit_MQTT(const char *server, uint16_t port, const PROGMEM char *cid, 
+                const PROGMEM char *user, const PROGMEM char *pass);
+  virtual ~Adafruit_MQTT() {}
 
-  uint8_t connectPacket(uint8_t *packet);
+  // Connect to the MQTT server.  Returns 0 on success, otherwise an error code
+  // that indicates something went wrong:
+  //   -1 = Error connecting to server
+  //    1 = Wrong protocol
+  //    2 = ID rejected
+  //    3 = Server unavailable
+  //    4 = Bad username or password
+  //    5 = Not authenticated
+  //    6 = Failed to subscribe
+  int8_t connect();
 
-  virtual boolean publish(const char *topic, char *payload, uint8_t qos) {}
-  uint8_t publishPacket(uint8_t *packet, const char *topic, char *payload, uint8_t qos);
+  // Disconnect from the MQTT server.  Returns true if disconnected, false
+  // otherwise.
+  virtual bool disconnect() = 0;  // Subclasses need to fill this in!
 
-  virtual boolean ping(uint8_t t) {}
-  uint8_t pingPacket(uint8_t *packet);
+  // 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, char *payload, uint8_t qos);
+  
+  // Add a subscription to receive messages for a topic.  Returns true if the
+  // subscription could be added, false otherwise.
+  bool subscribe(Adafruit_MQTT_Subscribe *sub);
 
-  virtual boolean subscribe(Adafruit_MQTT_Subscribe *sub) {}
-  uint8_t subscribePacket(uint8_t *packet, const char *topic, uint8_t qos);
+  // Check if any subscriptions have new messages.  Will return a reference to
+  // an Adafruit_MQTT_Subscribe object which has a new message.  Should be called
+  // in the sketch's loop function to ensure new messages are recevied.  Note
+  // that subscribe should be called first for each topic that receives messages!
+  Adafruit_MQTT_Subscribe *readSubscription(int16_t timeout=0);
 
-  virtual Adafruit_MQTT_Subscribe *readSubscription(int16_t timeout = 0) {};
+  // Ping the server to ensure the connection is still alive.  Returns true if
+  // successful, otherwise false.
+  bool ping(uint8_t t);
 
  protected:
-  int8_t errno;
+  // Interface that subclasses need to implement:
+
+  // Connect to the server and return true if successful, false otherwise.
+  virtual bool connectServer() = 0;
+
+  // Send data to the server specified by the buffer and length of data.
+  virtual bool sendPacket(uint8_t *buffer, uint8_t len) = 0;
+
+  // Read MQTT packet from the server.  Will read up to maxlen bytes and store
+  // the data in the provided buffer.  Waits up to the specified timeout (in
+  // milliseconds) for data to be available.  If checkForValidPubPacket is true
+  // then the received data is verified to make sure it's a complete packet.
+  virtual uint16_t readPacket(uint8_t *buffer, uint8_t maxlen, int16_t timeout,
+                              bool checkForValidPubPacket = false) = 0;
+
+  // Shared state that subclasses can use:
   const char *servername;
-  uint32_t serverip;
   int16_t portnum;
   const char *clientid;
   const char *username;
   const char *password;
-
-  Adafruit_MQTT_Subscribe *subscriptions[MAXSUBSCRIPTIONS];
   uint8_t buffer[MAXBUFFERSIZE];
+
+ private:
+  Adafruit_MQTT_Subscribe *subscriptions[MAXSUBSCRIPTIONS];
+
+  // Functions to generate MQTT packets.
+  uint8_t connectPacket(uint8_t *packet);
+  uint8_t publishPacket(uint8_t *packet, const char *topic, char *payload, uint8_t qos);
+  uint8_t subscribePacket(uint8_t *packet, const char *topic, uint8_t qos);
+  uint8_t pingPacket(uint8_t *packet);
 };
 
+
 class Adafruit_MQTT_Publish {
  public:
   Adafruit_MQTT_Publish(Adafruit_MQTT *mqttserver, const char *feed, uint8_t qos = 0);
@@ -114,4 +171,4 @@ class Adafruit_MQTT_Subscribe {
 };
 
 
-#endif /* header guard */
+#endif