From f04806669381c28f8aed07adbfc1ed1f8c3cd35f Mon Sep 17 00:00:00 2001
From: Scott Nonnenberg <scott@signal.org>
Date: Tue, 3 Aug 2021 18:02:35 -0700
Subject: [PATCH] Sender Key: Flags to disable, send to unrestricted

---
 ts/RemoteConfig.ts     |  3 ++-
 ts/util/handleRetry.ts | 12 +++++++++++-
 ts/util/sendToGroup.ts | 19 ++++++++++++++-----
 3 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/ts/RemoteConfig.ts b/ts/RemoteConfig.ts
index 640be65bf..4eac88bdf 100644
--- a/ts/RemoteConfig.ts
+++ b/ts/RemoteConfig.ts
@@ -11,13 +11,14 @@ export type ConfigKeyType =
   | 'desktop.disableGV1'
   | 'desktop.groupCalling'
   | 'desktop.gv2'
-  | 'desktop.internalUser'
   | 'desktop.mandatoryProfileSharing'
   | 'desktop.mediaQuality.levels'
   | 'desktop.messageRequests'
   | 'desktop.retryReceiptLifespan'
   | 'desktop.retryRespondMaxAge'
   | 'desktop.screensharing2'
+  | 'desktop.senderKey.send'
+  | 'desktop.senderKey.retry'
   | 'desktop.storage'
   | 'desktop.storageWrite3'
   | 'desktop.worksAtSignal'
diff --git a/ts/util/handleRetry.ts b/ts/util/handleRetry.ts
index 67e9733d5..403419eed 100644
--- a/ts/util/handleRetry.ts
+++ b/ts/util/handleRetry.ts
@@ -41,6 +41,13 @@ export async function onRetryRequest(event: RetryRequestEvent): Promise<void> {
 
   window.log.info(`onRetryRequest/${logId}: Starting...`);
 
+  if (!RemoteConfig.isEnabled('desktop.senderKey.retry')) {
+    window.log.warn(
+      `onRetryRequest/${logId}: Feature flag disabled, returning early.`
+    );
+    return;
+  }
+
   if (window.RETRY_DELAY) {
     window.log.warn(
       `onRetryRequest/${logId}: Delaying because RETRY_DELAY is set...`
@@ -145,7 +152,10 @@ export async function onDecryptionError(
     await conversation.getProfiles();
   }
 
-  if (conversation.get('capabilities')?.senderKey) {
+  if (
+    conversation.get('capabilities')?.senderKey &&
+    RemoteConfig.isEnabled('desktop.senderKey.retry')
+  ) {
     await requestResend(decryptionError);
   } else {
     await startAutomaticSessionReset(decryptionError);
diff --git a/ts/util/sendToGroup.ts b/ts/util/sendToGroup.ts
index 88ecedd50..d5f993dc8 100644
--- a/ts/util/sendToGroup.ts
+++ b/ts/util/sendToGroup.ts
@@ -12,6 +12,7 @@ import {
   UnidentifiedSenderMessageContent,
 } from '@signalapp/signal-client';
 import { typedArrayToArrayBuffer as toArrayBuffer } from '../Crypto';
+import * as Bytes from '../Bytes';
 import { senderCertificateService } from '../services/senderCertificate';
 import {
   padMessage,
@@ -42,6 +43,7 @@ import {
   multiRecipient410ResponseSchema,
 } from '../textsecure/WebAPI';
 import { SignalService as Proto } from '../protobuf';
+import * as RemoteConfig from '../RemoteConfig';
 
 import { strictAssert } from './assert';
 import { isGroupV2 } from './whatTypeOfConversation';
@@ -57,6 +59,9 @@ const MAX_CONCURRENCY = 5;
 // sendWithSenderKey is recursive, but we don't want to loop back too many times.
 const MAX_RECURSION = 10;
 
+const ACCESS_KEY_LENGTH = 16;
+const ZERO_ACCESS_KEY = Bytes.toBase64(new Uint8Array(ACCESS_KEY_LENGTH));
+
 // TODO: remove once we move away from ArrayBuffers
 const FIXMEU8 = Uint8Array;
 
@@ -142,6 +147,7 @@ export async function sendContentMessageToGroup({
 
   if (
     ourConversation?.get('capabilities')?.senderKey &&
+    RemoteConfig.isEnabled('desktop.senderKey.send') &&
     isGroupV2(conversation.attributes)
   ) {
     try {
@@ -744,7 +750,6 @@ async function handle410Response(
 }
 
 function getXorOfAccessKeys(devices: Array<DeviceType>): Buffer {
-  const ACCESS_KEY_LENGTH = 16;
   const uuids = getUuidsFromDevices(devices);
 
   const result = Buffer.alloc(ACCESS_KEY_LENGTH);
@@ -1008,13 +1013,17 @@ function getAccessKey(
 ): string | undefined {
   const { sealedSender, accessKey } = attributes;
 
-  if (
-    sealedSender === SEALED_SENDER.ENABLED ||
-    sealedSender === SEALED_SENDER.UNKNOWN
-  ) {
+  if (sealedSender === SEALED_SENDER.ENABLED) {
     return accessKey || undefined;
   }
 
+  if (
+    sealedSender === SEALED_SENDER.UNKNOWN ||
+    sealedSender === SEALED_SENDER.UNRESTRICTED
+  ) {
+    return ZERO_ACCESS_KEY;
+  }
+
   return undefined;
 }