Multicast downlink

package.json

@@ -10,7 +10,8 @@
  "node-red": {
   "nodes": {
    "device-event": "src/device-event.js",
-   "device-downlink": "src/device-downlink.js"
+   "device-downlink": "src/device-downlink.js",
+   "multicast-downlink": "src/multicastGroup-downlink.js"
   }
  }
 }

src/multicastGroup-downlink.html

@@ -0,0 +1,74 @@
+<script type="text/javascript">
+    RED.nodes.registerType('multicast group downlink',{
+        category: 'ChirpStack',
+        color: '#a6bbcf',
+        defaults: {
+            name: {value:""},
+            server: {value: ""},
+            useTls: {value: false},
+            apiToken: {value: ""},
+            encoding: {value: "hex"}
+        },
+        inputs:1,
+        outputs:1,
+        icon: "bridge.svg",
+        label: function() {
+            return this.name || "multicast group downlink";
+        }
+    });
+</script>
+
+<script type="text/html" data-template-name="multicast group downlink">
+    <div class="form-row">
+        <label for="node-input-server"><i class="fa fa-server"></i> Server</label>
+        <input type="text" id="node-input-server" placeholder="hostname:port, e.g. localhost:8080 or example.com:443">
+    </div>
+    <div class="form-row">
+        <label for="node-input-useTls"><i class="fa fa-lock"></i> Use TLS</label>
+        <input type="checkbox" id="node-input-useTls">
+    </div>
+    <div class="form-row">
+        <label for="node-input-apiToken"><i class="fa fa-key"></i> API Token</label>
+        <input type="password" id="node-input-apiToken" placeholder="API Token">
+    </div>
+    <div class="form-row">
+        <label for="node-input-encoding"><i class="fa fa-file-code-o"></i> Payload Encoding</label>
+        <select id="node-input-encoding">
+          <option value="hex">HEX</option>
+          <option value="base64">Base64</option>
+        </select>
+    </div>
+    <div class="form-row">
+        <label for="node-input-name"><i class="fa fa-tag"></i> Name</label>
+        <input type="text" id="node-input-name" placeholder="Name">
+    </div>
+</script>
+
+<script type="text/html" data-help-name="multicast group downlink">
+    <p>
+      Node to enqueue a multicast group downlink payload for the given <code>multicastGroupId</code>.
+    </p>
+
+    <h3>Details</h3>
+    <p>
+      This node enqueues the input payload using the ChirpStack gRPC API.
+      This requires access to the ChirpStack gRPC endpoint and an API token,
+      which can be retrieved using the ChirpStack web-interface.
+    </p>
+
+    <h3>Input</h3>
+    <dl class="message-properties">
+      <dt>multicastGroupId <span class="property-type">string</span></dt>
+      <dd>Multicast group Id (e.g. <code>81d5545f-973f-4c45-87f2-f917d509581d</code>).</dd>
+      <dt>fPort <span class="property-type">number</span></dt>
+      <dd>Downlink FPort.</dd>
+      <dt>payload <span class="property-type">string</span></dt>
+      <dd>HEX or BASE64 encoded payload (select the encoding in the node settings). If <code>payload</code> is <code>undefined</code>, then an empty downlink will be enqueued.</dd>
+    </dl>
+
+    <h3>Output</h3>
+    <dl class="message-properties">
+      <dt>fCnt <span class="property-type">string</span></dt>
+      <dd>Frame counter.</dd>
+    </dl>
+</script>

src/multicastGroup-downlink.js

@@ -0,0 +1,64 @@
+module.exports = function(RED) {
+  "use strict";
+  var multicastGroup = require("@chirpstack/chirpstack-api/api/multicast_group_grpc_pb");
+  var multicastGroup_pb = require("@chirpstack/chirpstack-api/api/multicast_group_pb");
+  var grpc = require("@grpc/grpc-js");
+
+  function MulticastGroupDownlink(config) {
+    RED.nodes.createNode(this, config);
+    var node = this;
+    var client = null;
+
+    if (config.useTls) {
+      client = new multicastGroup.MulticastGroupServiceClient(config.server, grpc.credentials.createSsl());
+    } else {
+      client = new multicastGroup.MulticastGroupServiceClient(config.server, grpc.credentials.createInsecure());
+    }
+
+
+    var meta = new grpc.Metadata();
+    meta.add('authorization', 'Bearer ' + config.apiToken);
+
+
+    node.on("input", function(msg) {
+
+      var item = new multicastGroup_pb.MulticastGroupQueueItem();
+      var req = new multicastGroup_pb.EnqueueMulticastGroupQueueItemRequest();
+
+      if (msg.multicastGroupId === undefined) {
+        node.error("multicastGroupId is undefined");
+        return;
+      } else {
+        item.setMulticastGroupId(msg.multicastGroupId);
+      }
+
+      if (msg.fPort === undefined) {
+        node.error("fPort is undefined");
+        return;
+      } else {
+        item.setFPort(msg.fPort);
+      }
+
+      if (msg.payload !== undefined) {
+        item.setData(Buffer.from(msg.payload, config.encoding).toString("base64"));
+      } else {
+        node.log("payload is undefined, assuming empty downlink frame");
+      }
+
+      req.setQueueItem(item);
+      client.enqueue(req, meta, function(err, resp) {
+        if (err !== null) {
+          node.error("Enqueue error: ", err);
+        } else {
+          node.log("Downlink enqueued");
+
+          node.send({
+            fCnt: resp.getFCnt()
+          });
+        }
+      });
+    });
+  }
+
+  RED.nodes.registerType("multicast group downlink", MulticastGroupDownlink);
+}