From 5228f04b19a3ab116cbf399f43ef37865b19df8c Mon Sep 17 00:00:00 2001
From: ksaye <ksaye@saye.org>
Date: Mon, 26 Apr 2021 18:02:38 -0500
Subject: [PATCH] Adding support for Azure IoT Hub

Simple testing documentation here: https://kevinsaye.wordpress.com/2021/04/26/using-tasmota-with-azure-iot-hub/ until I can contribute tot the Tasmota documentation site.
---
 tasmota/xdrv_02_mqtt.ino | 64 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 61 insertions(+), 3 deletions(-)

diff --git a/tasmota/xdrv_02_mqtt.ino b/tasmota/xdrv_02_mqtt.ino
index b72cc671c..48aa65d9d 100644
--- a/tasmota/xdrv_02_mqtt.ino
+++ b/tasmota/xdrv_02_mqtt.ino
@@ -23,6 +23,12 @@
 #define MQTT_WIFI_CLIENT_TIMEOUT   200    // Wifi TCP connection timeout (default is 5000 mSec)
 #endif
 
+#if defined(USE_MQTT_AZURE_IOT)
+  #include <JsonParser.h>
+  #undef  MQTT_PORT
+  #define MQTT_PORT         8883
+#endif //USE_MQTT_AZURE_IOT
+
 #define USE_MQTT_NEW_PUBSUBCLIENT
 
 // #define DEBUG_DUMP_TLS    // allow dumping of TLS Flash keys
@@ -225,7 +231,14 @@ void MqttDisconnect(void) {
 }
 
 void MqttSubscribeLib(const char *topic) {
-  MqttClient.subscribe(topic);
+  #if defined(USE_MQTT_AZURE_IOT)
+    // Azure IoT Hub currently does not support custom topics: https://docs.microsoft.com/en-us/azure/iot-hub/iot-hub-mqtt-support
+    String realTopicString = "devices/" + String(SettingsText(SET_MQTT_CLIENT));
+    realTopicString += "/messages/devicebound/#";
+    MqttClient.subscribe(realTopicString.c_str());
+  #else //USE_MQTT_AZURE_IOT
+    MqttClient.subscribe(topic);
+  #endif //USE_MQTT_AZURE_IOT
   MqttClient.loop();  // Solve LmacRxBlk:1 messages
 }
 
@@ -244,7 +257,25 @@ bool MqttPublishLib(const char* topic, bool retained) {
     }
   }
 
-  bool result = MqttClient.publish(topic, TasmotaGlobal.mqtt_data, retained);
+  bool result;
+  #if defined(USE_MQTT_AZURE_IOT)
+    String sourceTopicString = String(topic);
+    sourceTopicString.replace("/", "%2F");
+    String topicString = "devices/" + String(SettingsText(SET_MQTT_CLIENT));
+    topicString+= "/messages/events/topic=" + sourceTopicString;
+
+    JsonParser mqtt_message((char*) String(TasmotaGlobal.mqtt_data).c_str());
+    JsonParserObject message_object = mqtt_message.getRootObject();
+    if (message_object.isValid()) {   // only sending valid JSON, yet this is optional
+      result = MqttClient.publish(topicString.c_str(), TasmotaGlobal.mqtt_data, retained);
+      AddLog(LOG_LEVEL_INFO, PSTR(D_LOG_MQTT "Sending '%s'"), TasmotaGlobal.mqtt_data);
+    } else {
+      AddLog(LOG_LEVEL_INFO, PSTR(D_LOG_MQTT "Invalid JSON, '%s' for topic '%s', not sending to Azure IoT Hub"), TasmotaGlobal.mqtt_data, topic);
+      result = true;
+    }
+  #else //USE_MQTT_AZURE_IOT
+    result = MqttClient.publish(topic, TasmotaGlobal.mqtt_data, retained);
+  #endif //USE_MQTT_AZURE_IOT
   yield();  // #3313
   return result;
 }
@@ -276,7 +307,24 @@ void MqttDataHandler(char* mqtt_topic, uint8_t* mqtt_data, unsigned int data_len
 
   // Save MQTT data ASAP as it's data is discarded by PubSubClient with next publish as used in MQTTlog
   char topic[TOPSZ];
-  strlcpy(topic, mqtt_topic, sizeof(topic));
+  #if defined(USE_MQTT_AZURE_IOT)
+    // for Azure, we read the topic from the property of the message
+    String fullTopicString = String(mqtt_topic);
+    int startOfTopic = fullTopicString.indexOf("TOPIC=");
+    if (startOfTopic == -1){
+      AddLog(LOG_LEVEL_ERROR, PSTR(D_LOG_MQTT "Azure IoT message without the property TOPIC, case sensitive."));
+      return;
+    }
+    String newTopic = fullTopicString.substring(startOfTopic + 6);
+    newTopic.replace("%2F", "/");
+    if (newTopic.indexOf("/") == -1){
+      AddLog(LOG_LEVEL_ERROR, PSTR(D_LOG_MQTT "Invalid Topic %s"), newTopic.c_str());
+      return;
+    }
+    strlcpy(topic, newTopic.c_str(), sizeof(topic));
+  #else //USE_MQTT_AZURE_IOT
+    strlcpy(topic, mqtt_topic, sizeof(topic));
+  #endif //USE_MQTT_AZURE_IOT
   mqtt_data[data_len] = 0;
   char data[data_len +1];
   memcpy(data, mqtt_data, sizeof(data));
@@ -698,7 +746,17 @@ void MqttReconnect(void) {
   }
 #endif
 
+#ifdef USE_MQTT_AZURE_IOT
+  if (String(mqtt_pwd).indexOf("SharedAccessSignature") == -1) {
+    AddLog(LOG_LEVEL_ERROR, PSTR(D_LOG_MQTT "Azure IoT incorrect SAS Token format. Refer to https://docs.microsoft.com/en-us/azure/iot-hub/iot-hub-mqtt-support"));
+    return;
+  }
+  String azureMqtt_userString = String(SettingsText(SET_MQTT_HOST)) + "/" + String(SettingsText(SET_MQTT_CLIENT)); + "/?api-version=2018-06-30";
+  if (MqttClient.connect(TasmotaGlobal.mqtt_client, azureMqtt_userString.c_str(), mqtt_pwd, stopic, 1, lwt_retain, TasmotaGlobal.mqtt_data, MQTT_CLEAN_SESSION)) {
+#else //USE_MQTT_AZURE_IOT
   if (MqttClient.connect(TasmotaGlobal.mqtt_client, mqtt_user, mqtt_pwd, stopic, 1, lwt_retain, TasmotaGlobal.mqtt_data, MQTT_CLEAN_SESSION)) {
+#endif //USE_MQTT_AZURE_IOT
+	  
 #ifdef USE_MQTT_TLS
     if (Mqtt.mqtt_tls) {
 #ifdef ESP8266