From 02877a01646fd5f4e6d61de69d623e68e91e1a32 Mon Sep 17 00:00:00 2001
From: Niels Andriesse <andriesseniels@gmail.com>
Date: Fri, 8 Nov 2019 14:59:36 +1100
Subject: [PATCH] Re-enable sync message validation

---
 SignalServiceKit/src/Messages/OWSMessageManager.m | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/SignalServiceKit/src/Messages/OWSMessageManager.m b/SignalServiceKit/src/Messages/OWSMessageManager.m
index 1686ea842..709b74bd7 100644
--- a/SignalServiceKit/src/Messages/OWSMessageManager.m
+++ b/SignalServiceKit/src/Messages/OWSMessageManager.m
@@ -901,12 +901,14 @@ NS_ASSUME_NONNULL_BEGIN
         return;
     }
 
-    NSString *localNumber = self.tsAccountManager.localNumber;
-//    if (![localNumber isEqualToString:envelope.source]) {
-//        // Sync messages should only come from linked devices.
-//        OWSProdErrorWEnvelope([OWSAnalyticsEvents messageManagerErrorSyncMessageFromUnknownSource], envelope);
-//        return;
-//    }
+    NSString *userHexEncodedPublicKey = OWSIdentityManager.sharedManager.identityKeyPair.hexEncodedPublicKey;
+    NSSet<NSString *> *linkedDeviceHexEncodedPublicKeys = [LKDatabaseUtilities getLinkedDeviceHexEncodedPublicKeysFor:userHexEncodedPublicKey in:transaction];
+    if (![linkedDeviceHexEncodedPublicKeys contains:^BOOL(NSString *hexEncodedPublicKey) {
+        return [hexEncodedPublicKey isEqual:envelope.source];
+    }]) {
+        OWSProdErrorWEnvelope([OWSAnalyticsEvents messageManagerErrorSyncMessageFromUnknownSource], envelope);
+        return;
+    }
 
     if (syncMessage.sent) {
         OWSIncomingSentMessageTranscript *transcript =