Fix #6

lib/lwm2m-common.js

@@ -874,18 +874,15 @@ class Observe extends RequestHandler {
 class Discover extends Read {
   buildResponse() {
     let buf = [];
-    let len = 0;
-    Object.keys(this.resources).forEach((key) => {
-      let r = this.resources[key];
-      if (r instanceof Resource) {
-        buf.push(r.id & 0xff);         // ResourceId LSB
-        buf.push((r.id >> 8) & 0xff);  // ResourceId MSB
-        ++len;
-      }
+    this.resources.map((r) => {
+      return parseInt(r.uri.split('/')[3]);
+    }).sort((a, b) => a - b).forEach((id) => {
+      buf.push(id & 0xff);         // ResourceId LSB
+      buf.push((id >> 8) & 0xff);  // ResourceId MSB
     });
     if (this.getStatus() < COAP_ERROR.COAP_400_BAD_REQUEST) {
       this.response = Buffer.concat([this.response, Buffer.from(buf)]);
-      this.setResourceLen(len);
+      this.setResourceLen(this.resources.length);
     }
   }
 }