Add ability to force a device disconnect

Fix #116

README.md

@@ -298,6 +298,7 @@ You can also connect to a device using MQTT packets:
 * `/ble/notify/DEVICE/SERVICE/CHARACTERISTIC` connects and starts notifications on the characteristic, which
 send data back on `/ble/data/DEVICE/SERVICE/CHARACTERISTIC`
 * `/ble/ping/DEVICE` connects, or maintains a connection to the device, and sends `/ble/pong/DEVICE` on success
+* `/ble/disconnect/DEVICE` will force a disconnect and send `/ble/disconnected/DEVICE` on completion. This is not normally required as EspruinoHub will automatically disconnect after a period of inactivity (see `connection_timeout` and `connection_alive_on_notify` in the config file)
 
 `SERVICE` and `CHARACTERISTIC` are either known names from [attributes.js](https://github.com/espruino/EspruinoHub/blob/master/lib/attributes.js)
 such as `nus` and `nus_tx` or are of the form `6e400001b5a3f393e0a9e50e24dcca9e` for 128 bit uuids or `abcd` for 16 bit UUIDs.

lib/mqttclient.js

@@ -58,6 +58,7 @@ client.on("connect", function () {
   client.subscribe(config.mqtt_prefix + "/read/#");
   client.subscribe(config.mqtt_prefix + "/notify/#");
   client.subscribe(config.mqtt_prefix + "/ping/#");
+  client.subscribe(config.mqtt_prefix + "/disconnect/#");
   client.publish(`${config.mqtt_prefix}/state`, "online", {retain: true});
   // Push out updated presence info
   discovery.sendMQTTPresence();
@@ -156,5 +157,16 @@ client.on("message", function (topic, message) {
         log("Ping " + id + " but not in range");
       }
     }
+    if (path[1] === "disconnect") { // disconnect device
+      var id = devices.deviceToAddr(path[2]);
+      if (discovery.inRange[id]) {
+        var device = discovery.inRange[id].peripheral;
+        connect.disconnect(device, function () {
+          client.publish(config.mqtt_prefix + "/disconnected/" + path[2], message);
+        });
+      } else {
+        log("Disconnect " + id + " but not in range");
+      }
+    }
   }
 });