V1.8.46: Flexible MQTT topic path

README.md

@@ -277,7 +277,11 @@ Many thanks to David Brooke for coding this feature and the AFC.
 Change History
 ==============
 
-## 14/02/2022 - V1.8.45
+16/02/2022 - V1.8.46
+
+	Added flexible MQTT topic - $GATEWAY$ gets replaced by gateway callsign; $PAYLOAD$ gets replaced by payload callsign
+
+14/02/2022 - V1.8.45
 
 	Added MQTT support (coded by David Johnson G4DPZ)
 

gateway-sample.txt

@@ -68,6 +68,7 @@ AFC_1=Y
 #MQTTPass=mqtt_password
 #MQTTClient=mqtt_client_name
 #MQTTTopic=topic_name
+# example MQTTTopic=incoming/payloads/$PAYLOAD$/$GATEWAY$/sentence
 
 # Dump config
 #DumpBuffer=Y

gateway.c

@@ -47,7 +47,7 @@
 #include "udpclient.h"
 #include "lifo_buffer.h"
 
-#define VERSION	"V1.8.45"
+#define VERSION	"V1.8.46"
 bool run = TRUE;
 
 // RFM98

global.h

@@ -151,7 +151,7 @@ struct TConfig
 	char MQTTUser[16];
 	char MQTTPass[32];
 	char MQTTClient[16];
-	char MQTTTopic[32];
+	char MQTTTopic[128];
 };
 
 typedef struct {
@@ -236,7 +236,7 @@ typedef struct {
     char user[16];
     char pass[32];
     char clientId[16];
-    char topic[32];
+    char topic[128];
 } mqtt_connect_t;
 
 struct TServerInfo

mqtt.c

@@ -49,6 +49,54 @@ void connlost(void *context, char *cause)
     LogMessage("     cause: %s\n", cause);
 }
 
+void InsertSubstring(char *topic, char *field, char *value)
+{
+	char *position;
+	char temp[256];
+	
+	strcpy(temp, topic);
+	position = strstr(temp, field);
+	
+	if (position != NULL)
+	{
+		strcpy(position, value);
+		position = strstr(topic, field);
+		strcat(temp, position + strlen(field));
+		// LogMessage("topic is now <%s>\n", temp);
+		strcpy(topic, temp);
+	}
+}
+
+void BuildMQTTPath(char *topic, mqtt_connect_t * mqttConnection, received_t * t)
+{
+	int i;
+	char GatewayID[32], Payload[32];
+	
+	// Get gateway callsign and remove any slashes as they would mess up the MQTT topic path
+	strcpy(GatewayID, Config.Tracker);
+	for (i=0; i<strlen(GatewayID); i++)
+	{
+		if (GatewayID[i] == '/')
+		{
+			GatewayID[i] = '_';
+		}
+	}
+	
+	// Get the payload ID
+	sscanf(t->Message + 2, "%31[^,]", Payload);
+
+	// Example: MQTTTopic=incoming/payloads/$PAYLOAD$/$GATEWAY$/sentence
+    strcpy(topic, mqttConnection->topic);
+
+	// Insert the payload ID if required by the config
+	InsertSubstring(topic, "$PAYLOAD$", Payload);
+
+	// Insert the callsign if required by the config
+	InsertSubstring(topic, "$GATEWAY$", GatewayID);
+	
+    // sprintf(topic, "%s/%s/%s/sentence", mqttConnection->topic, Payload, GatewayID);
+}
+
 bool UploadMQTTPacket(mqtt_connect_t * mqttConnection, received_t * t )
 {
     MQTTClient client;
@@ -56,9 +104,11 @@ bool UploadMQTTPacket(mqtt_connect_t * mqttConnection, received_t * t )
     MQTTClient_message pubmsg = MQTTClient_message_initializer;
     MQTTClient_deliveryToken token;
     int rc;
-
-    char address[256];
+    char address[256], topic[256];
+	
     sprintf(address, "tcp://%s:%s", mqttConnection->host,mqttConnection->port);
+	
+	BuildMQTTPath(topic,  mqttConnection, t);
 
     MQTTClient_create(&client, address, mqttConnection->clientId,
         MQTTCLIENT_PERSISTENCE_NONE, NULL);
@@ -70,7 +120,7 @@ bool UploadMQTTPacket(mqtt_connect_t * mqttConnection, received_t * t )
     // LogMessage("Attempting publication on host: %s\n",
 	// address);
             //"on topic %s for client with ClientID: %s\n",
-            //t->Message, address, mqttConnection->topic, mqttConnection->clientId);
+            //t->Message, address, topic, mqttConnection->clientId);
     if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS)
     {
         LogMessage("MQTT: Failed to connect, return code %d\n", rc);
@@ -81,7 +131,7 @@ bool UploadMQTTPacket(mqtt_connect_t * mqttConnection, received_t * t )
     pubmsg.qos = QOS;
     pubmsg.retained = 0;
     deliveredtoken = 0;
-    MQTTClient_publishMessage(client, mqttConnection->topic, &pubmsg, &token);
+    MQTTClient_publishMessage(client, topic, &pubmsg, &token);
     while(deliveredtoken != token);
     MQTTClient_disconnect(client, 10000);
     MQTTClient_destroy(&client);