Stop processing message when it is empty

libtextsecure/message_receiver.js

@@ -1250,6 +1250,15 @@ MessageReceiver.prototype.extend({
           return this.removeFromCache(envelope);
         }
 
+        if (!friendRequest && this.isMessageEmpty(message)) {
+          window.log.warn(
+            `Message ${this.getEnvelopeId(
+              envelope
+            )} ignored; it was empty`
+          );
+          return this.removeFromCache(envelope);
+        }
+
         const ev = new Event('message');
         ev.confirm = this.removeFromCache.bind(this, envelope);
         ev.data = {
@@ -1265,6 +1274,9 @@ MessageReceiver.prototype.extend({
       })
     );
   },
+  isMessageEmpty({ body, attachments, group, flags, quote, contact, preview, groupInvitation }) {
+    return !flags && _.isEmpty(body) && _.isEmpty(attachments) && _.isEmpty(group) && _.isEmpty(quote) && _.isEmpty(contact) && _.isEmpty(preview) && _.isEmpty(groupInvitation)
+  },
   handleLegacyMessage(envelope) {
     return this.decrypt(envelope, envelope.legacyMessage).then(plaintext => {
       if (!plaintext) {