mqtt: begin subscription support

src/mqtt/MQTT.cpp

@@ -9,13 +9,29 @@
 MQTT *mqtt;
 
 String statusTopic = "mesh/stat/";
+String cryptTopic = "mesh/crypt/"; // mesh/crypt/CHANNELID/NODEID
 
-void mqttCallback(char *topic, byte *payload, unsigned int length)
+void MQTT::mqttCallback(char *topic, byte *payload, unsigned int length)
 {
-    DEBUG_MSG("MQTT topic %s\n", topic);
+    mqtt->onPublish(topic, payload, length);
+}
 
-    // After parsing ServiceEnvelope
-    // FIXME - make sure to free both strings and the MeshPacket
+void MQTT::onPublish(char *topic, byte *payload, unsigned int length)
+{
+    // parsing ServiceEnvelope
+    ServiceEnvelope e = ServiceEnvelope_init_default;
+    if (!pb_decode_from_bytes(payload, length, ServiceEnvelope_fields, &e)) {
+        DEBUG_MSG("Invalid MQTT service envelope, topic %s, len %u!\n", topic, length);
+    } else {
+        DEBUG_MSG("Received MQTT topic %s, len=%u\n", topic, length);
+
+        // FIXME, ignore messages sent by us (requires decryption) or if we don't have the channel key
+
+        // make sure to free both strings and the MeshPacket (passing in NULL is acceptable)
+        free(e.channel_id);
+        free(e.gateway_id);
+        free(e.packet);
+    }
 }
 
 void mqttInit()
@@ -53,15 +69,30 @@ void MQTT::reconnect()
         static char subsStr[64]; /* We keep this static because the mqtt lib
                                     might not be copying it */
         // snprintf(subsStr, sizeof(subsStr), "/ezd/todev/%s/#", clientId);
-        // mqtt.subscribe(subsStr, 1); // we use qos 1 because we don't want to miss messages
+        // pubSub.subscribe(subsStr, 1); // we use qos 1 because we don't want to miss messages
 
         /// FIXME, include more information in the status text
         bool ok = pubSub.publish(myStatus.c_str(), "online", true);
         DEBUG_MSG("published %d\n", ok);
+
+        sendSubscriptions();
     } else
         DEBUG_MSG("Failed to contact MQTT server...\n");
 }
 
+void MQTT::sendSubscriptions()
+{
+    size_t numChan = channels.getNumChannels();
+    for (size_t i = 0; i < numChan; i++) {
+        auto &ch = channels.getByIndex(i);
+        if (ch.settings.uplink_enabled) {
+            String topic = cryptTopic + channels.getGlobalId(i) + "/#";
+            DEBUG_MSG("Subscribing to %s\n", topic.c_str());
+            pubSub.subscribe(topic.c_str(), 1); // FIXME, is QOS 1 right?
+        }
+    }
+}
+
 bool MQTT::wantsLink() const
 {
     bool hasChannel = false;
@@ -124,18 +155,9 @@ void MQTT::onSend(const MeshPacket &mp, ChannelIndex chIndex)
         static uint8_t bytes[MeshPacket_size + 64];
         size_t numBytes = pb_encode_to_bytes(bytes, sizeof(bytes), ServiceEnvelope_fields, &env);
 
-        const char *topic = getCryptTopic(channelId);
-        DEBUG_MSG("publish %s, %u bytes\n", topic, numBytes);
+        String topic = cryptTopic + channelId + "/" + owner.id;
+        DEBUG_MSG("publish %s, %u bytes\n", topic.c_str(), numBytes);
 
-        pubSub.publish(topic, bytes, numBytes, false);
+        pubSub.publish(topic.c_str(), bytes, numBytes, false);
     }
 }
-
-const char *MQTT::getCryptTopic(const char *channelId)
-{
-    static char buf[128];
-
-    // "mesh/crypt/CHANNELID/NODEID/PORTID"
-    snprintf(buf, sizeof(buf), "mesh/crypt/%s/%s", channelId, owner.id);
-    return buf;
-}

src/mqtt/MQTT.h

@@ -36,8 +36,6 @@ class MQTT : private concurrency::OSThread
     virtual int32_t runOnce();
 
   private:
-    const char *getCryptTopic(const char *channelId);
-
     /** return true if we have a channel that wants uplink/downlink
      */
     bool wantsLink() const;
@@ -45,6 +43,16 @@ class MQTT : private concurrency::OSThread
     /** Attempt to connect to server if necessary
      */
     void reconnect();
+
+    /** Tell the server what subscriptions we want (based on channels.downlink_enabled)
+     */
+    void sendSubscriptions();
+
+    /// Just C glue to call onPublish
+    static void mqttCallback(char *topic, byte *payload, unsigned int length);
+
+    /// Called when a new publish arrives from the MQTT server
+    void onPublish(char *topic, byte *payload, unsigned int length);
 };
 
 void mqttInit();