From 07b2425ff9464fc40ac324b735c67dbdd3a69192 Mon Sep 17 00:00:00 2001
From: JC Brand <jc@opkode.com>
Date: Sat, 20 Nov 2021 12:54:33 +0100
Subject: [PATCH] Don't show unnecessary errors for undecryptable OMEMO
 messages

As mentioned in the XEP, don't show error messages for OMEMO messages
that can't be decrypted because they were already decrypted before or
because they weren't encrypted for this device.
---
 src/headless/plugins/muc/muc.js | 12 +++++++++-
 src/plugins/omemo/utils.js      | 42 ++++++++++++++++++++-------------
 2 files changed, 36 insertions(+), 18 deletions(-)

diff --git a/src/headless/plugins/muc/muc.js b/src/headless/plugins/muc/muc.js
index 47af6ff7f..883c00719 100644
--- a/src/headless/plugins/muc/muc.js
+++ b/src/headless/plugins/muc/muc.js
@@ -1928,7 +1928,14 @@ const ChatRoomMixin = {
      * @returns {Promise<boolean>}
      */
     async shouldShowErrorMessage (attrs) {
-        if (attrs['error_condition'] === 'not-acceptable' && (await this.rejoinIfNecessary())) {
+        if (attrs.error_type === 'Decryption') {
+            if (attrs.error_message === "Message key not found. The counter was repeated or the key was not filled.") {
+                // OMEMO message which we already decrypted before
+                return false;
+            } else if ( attrs.error_condition === 'not-encrypted-for-this-device') {
+                return false;
+            }
+        } else if (attrs.error_condition === 'not-acceptable' && (await this.rejoinIfNecessary())) {
             return false;
         }
         return _converse.ChatBox.prototype.shouldShowErrorMessage.call(this, attrs);
@@ -2198,7 +2205,10 @@ const ChatRoomMixin = {
         if (u.isErrorObject(attrs)) {
             attrs.stanza && log.error(attrs.stanza);
             return log.error(attrs.message);
+        } else if (attrs.type === 'error' && !(await this.shouldShowErrorMessage(attrs))) {
+            return;
         }
+
         const message = this.getDuplicateMessage(attrs);
         if (message) {
             (message.get('type') === 'groupchat') && this.updateMessage(message, attrs);
diff --git a/src/plugins/omemo/utils.js b/src/plugins/omemo/utils.js
index afd94e074..3a4c8fde2 100644
--- a/src/plugins/omemo/utils.js
+++ b/src/plugins/omemo/utils.js
@@ -204,12 +204,22 @@ export function handleEncryptedFiles (richtext) {
 }
 
 export function parseEncryptedMessage (stanza, attrs) {
-    if (attrs.is_encrypted && attrs.encrypted.key) {
-        // https://xmpp.org/extensions/xep-0384.html#usecases-receiving
-        if (attrs.encrypted.prekey === true) {
-            return decryptPrekeyWhisperMessage(attrs);
+    if (attrs.is_encrypted) {
+        if (!attrs.encrypted.key) {
+            return Object.assign(attrs, {
+                'error_condition': 'not-encrypted-for-this-device',
+                'error_type': 'Decryption',
+                'is_ephemeral': true,
+                'is_error': true,
+                'type': 'error'
+            });
         } else {
-            return decryptWhisperMessage(attrs);
+            // https://xmpp.org/extensions/xep-0384.html#usecases-receiving
+            if (attrs.encrypted.prekey === true) {
+                return decryptPrekeyWhisperMessage(attrs);
+            } else {
+                return decryptWhisperMessage(attrs);
+            }
         }
     } else {
         return attrs;
@@ -287,18 +297,16 @@ async function handleDecryptedWhisperMessage (attrs, key_and_tag) {
 }
 
 function getDecryptionErrorAttributes (e) {
-    if (api.settings.get('loglevel') === 'debug') {
-        return {
-            'error_text':
-                __('Sorry, could not decrypt a received OMEMO message due to an error.') + ` ${e.name} ${e.message}`,
-            'error_type': 'Decryption',
-            'is_ephemeral': true,
-            'is_error': true,
-            'type': 'error'
-        };
-    } else {
-        return {};
-    }
+    return {
+        'error_text':
+            __('Sorry, could not decrypt a received OMEMO message due to an error.') + ` ${e.name} ${e.message}`,
+        'error_condition': e.name,
+        'error_message': e.message,
+        'error_type': 'Decryption',
+        'is_ephemeral': true,
+        'is_error': true,
+        'type': 'error'
+    };
 }
 
 async function decryptPrekeyWhisperMessage (attrs) {