Fix SSK encryption

SignalServiceKit/src/Loki/Protocol/Session Management/SessionManagementProtocol.swift

@@ -60,9 +60,18 @@ public final class SessionManagementProtocol : NSObject {
 
     // MARK: - Sending
 
+    @objc(isSessionRequiredForMessage:recipientID:transaction:)
+    public static func isSessionRequired(for message: TSOutgoingMessage, recipientID: String, transaction: YapDatabaseReadWriteTransaction) -> Bool {
+        if SharedSenderKeysImplementation.shared.isClosedGroup(recipientID) {
+            return false
+        } else {
+            return !shouldUseFallbackEncryption(for: message, recipientID: recipientID, transaction: transaction)
+        }
+    }
+
     @objc(shouldUseFallbackEncryptionForMessage:recipientID:transaction:)
     public static func shouldUseFallbackEncryption(for message: TSOutgoingMessage, recipientID: String, transaction: YapDatabaseReadWriteTransaction) -> Bool {
-        if SharedSenderKeysImplementation.shared.isClosedGroup(recipientID) { return true } // We don't actually use fallback encryption but this indicates that we don't need a session
+        if SharedSenderKeysImplementation.shared.isClosedGroup(recipientID) { return false }
         else if message is SessionRequestMessage { return true }
         else if let message = message as? DeviceLinkMessage, message.kind == .request { return true }
         else if message is OWSOutgoingNullMessage { return false }

SignalServiceKit/src/Messages/OWSMessageSender.m

@@ -1077,7 +1077,10 @@ NSString *const OWSMessageSenderRateLimitedException = @"RateLimitedException";
         [self.dbConnection readWithBlock:^(YapDatabaseReadTransaction *transaction) {
             isUserLinkedDevice = [LKDatabaseUtilities isUserLinkedDevice:targetPublicKey in:transaction];
         }];
-        if ([targetPublicKey isEqual:userPublicKey]) {
+        BOOL isSSKBasedClosedGroup = [messageSend.thread isKindOfClass:TSGroupThread.class] && ((TSGroupThread *)messageSend.thread).usesSharedSenderKeys;
+        if (isSSKBasedClosedGroup) {
+            [LKLogger print:[NSString stringWithFormat:@"[Loki] Sending %@ to SSK based closed group.", message.class]];
+        } else if ([targetPublicKey isEqual:userPublicKey]) {
             [LKLogger print:[NSString stringWithFormat:@"[Loki] Sending %@ to self.", message.class]];
         } else if (isUserLinkedDevice) {
             [LKLogger print:[NSString stringWithFormat:@"[Loki] Sending %@ to %@ (one of the current user's linked devices).", message.class, recipient.recipientId]];
@@ -1086,14 +1089,17 @@ NSString *const OWSMessageSenderRateLimitedException = @"RateLimitedException";
         }
         NSDictionary *signalMessageInfo = deviceMessages.firstObject;
         SSKProtoEnvelopeType type = ((NSNumber *)signalMessageInfo[@"type"]).integerValue;
-        if ([messageSend.thread isKindOfClass:TSGroupThread.class] && ((TSGroupThread *)messageSend.thread).usesSharedSenderKeys) {
+        if (isSSKBasedClosedGroup) {
             type = SSKProtoEnvelopeTypeClosedGroupCiphertext;
         }
         uint64_t timestamp = message.timestamp;
-        NSString *senderID = (type == SSKProtoEnvelopeTypeUnidentifiedSender) ? @"" : userPublicKey;
-        if ([messageSend.thread isKindOfClass:TSGroupThread.class] && ((TSGroupThread *)messageSend.thread).usesSharedSenderKeys) {
+        NSString *senderID;
+        if (isSSKBasedClosedGroup) {
             senderID = [LKGroupUtilities getDecodedGroupID:((TSGroupThread *)messageSend.thread).groupModel.groupId];
+        } else if (type == SSKProtoEnvelopeTypeUnidentifiedSender) {
+            senderID = @"";
         } else {
+            senderID = userPublicKey;
             [LKLogger print:@"[Loki] Non-UD send"];
         }
         uint32_t senderDeviceID = type == SSKProtoEnvelopeTypeUnidentifiedSender ? 0 : OWSDevicePrimaryDeviceId;
@@ -1385,7 +1391,7 @@ NSString *const OWSMessageSenderRateLimitedException = @"RateLimitedException";
     @try {
         __block BOOL isSessionRequired;
         [LKStorage writeSyncWithBlock:^(YapDatabaseReadWriteTransaction *transaction) {
-            isSessionRequired = ![LKSessionManagementProtocol shouldUseFallbackEncryptionForMessage:messageSend.message recipientID:recipientID transaction:transaction];
+            isSessionRequired = [LKSessionManagementProtocol isSessionRequiredForMessage:messageSend.message recipientID:recipientID transaction:transaction];
         } error:nil];
         if (isSessionRequired) {
             BOOL hasSession = [self throws_ensureRecipientHasSessionForMessageSend:messageSend recipientID:recipientID deviceId:@(OWSDevicePrimaryDeviceId)];