From 44e7e456caafee643d7d64df59df2fd034e14128 Mon Sep 17 00:00:00 2001
From: Michelle Linington <michelle@signal.org>
Date: Fri, 21 Aug 2020 16:42:26 -0700
Subject: [PATCH] IOS-797: Configuration sync messages incorrectly updating
 local config on nil message fields

Configuration sync messages use proto2, so the value for a given field
may or may not exist. When we receive an incoming sync message, we
should only adopt any properties if they're already set. Otherwise we
risk interpreting an unset field as set NO.
---
 SignalMessaging/contacts/OWSSyncManager.m | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/SignalMessaging/contacts/OWSSyncManager.m b/SignalMessaging/contacts/OWSSyncManager.m
index 6aa4432c4a..9de0c9105f 100644
--- a/SignalMessaging/contacts/OWSSyncManager.m
+++ b/SignalMessaging/contacts/OWSSyncManager.m
@@ -252,12 +252,23 @@ NSString *const kSyncManagerLastContactSyncKey = @"kTSStorageManagerOWSSyncManag
 
 - (void)processIncomingConfigurationSyncMessage:(SSKProtoSyncMessageConfiguration *)syncMessage transaction:(SDSAnyWriteTransaction *)transaction
 {
-    [SSKEnvironment.shared.readReceiptManager setAreReadReceiptsEnabled:syncMessage.readReceipts transaction:transaction];
-    [Environment.shared.preferences
-        setShouldShowUnidentifiedDeliveryIndicators:syncMessage.unidentifiedDeliveryIndicators
-                                        transaction:transaction];
-    [self.typingIndicators setTypingIndicatorsEnabledWithValue:syncMessage.typingIndicators transaction:transaction];
-    [SSKPreferences setAreLinkPreviewsEnabled:syncMessage.linkPreviews transaction:transaction];
+    if (syncMessage.hasReadReceipts) {
+        [SSKEnvironment.shared.readReceiptManager setAreReadReceiptsEnabled:syncMessage.readReceipts
+                                                                transaction:transaction];
+    }
+    if (syncMessage.hasUnidentifiedDeliveryIndicators) {
+        BOOL updatedValue = syncMessage.unidentifiedDeliveryIndicators;
+        [Environment.shared.preferences setShouldShowUnidentifiedDeliveryIndicators:updatedValue
+                                                                        transaction:transaction];
+    }
+    if (syncMessage.hasTypingIndicators) {
+        [self.typingIndicators setTypingIndicatorsEnabledWithValue:syncMessage.typingIndicators
+                                                       transaction:transaction];
+    }
+    if (syncMessage.hasLinkPreviews) {
+        [SSKPreferences setAreLinkPreviewsEnabled:syncMessage.linkPreviews
+                                      transaction:transaction];
+    }
 
     [transaction addAsyncCompletion:^{
         [[NSNotificationCenter defaultCenter] postNotificationNameAsync:OWSSyncManagerConfigurationSyncDidCompleteNotification