All sync messages should have 1-512 random padding

// FREEBIE

src/Devices/OWSBlockedPhoneNumbersMessage.m

@@ -27,7 +27,7 @@ NS_ASSUME_NONNULL_BEGIN
     return self;
 }
 
-- (OWSSignalServiceProtosSyncMessage *)buildSyncMessage
+- (OWSSignalServiceProtosSyncMessageBuilder *)syncMessageBuilder
 {
     OWSSignalServiceProtosSyncMessageBlockedBuilder *blockedPhoneNumbersBuilder =
         [OWSSignalServiceProtosSyncMessageBlockedBuilder new];
@@ -35,7 +35,7 @@ NS_ASSUME_NONNULL_BEGIN
     OWSSignalServiceProtosSyncMessageBuilder *syncMessageBuilder = [OWSSignalServiceProtosSyncMessageBuilder new];
     [syncMessageBuilder setBlocked:[blockedPhoneNumbersBuilder build]];
 
-    return [syncMessageBuilder build];
+    return syncMessageBuilder;
 }
 
 @end

src/Devices/OWSReadReceiptsMessage.m

@@ -1,4 +1,6 @@
-//  Copyright © 2016 Open Whisper Systems. All rights reserved.
+//
+//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//
 
 #import "OWSReadReceiptsMessage.h"
 #import "OWSReadReceipt.h"
@@ -26,7 +28,7 @@ NS_ASSUME_NONNULL_BEGIN
     return self;
 }
 
-- (OWSSignalServiceProtosSyncMessage *)buildSyncMessage
+- (OWSSignalServiceProtosSyncMessageBuilder *)syncMessageBuilder
 {
     OWSSignalServiceProtosSyncMessageBuilder *syncMessageBuilder = [OWSSignalServiceProtosSyncMessageBuilder new];
     for (OWSReadReceipt *readReceipt in self.readReceipts) {
@@ -37,7 +39,7 @@ NS_ASSUME_NONNULL_BEGIN
         [syncMessageBuilder addRead:[readProtoBuilder build]];
     }
 
-    return [syncMessageBuilder build];
+    return syncMessageBuilder;
 }
 
 @end

src/Devices/OWSVerificationStateSyncMessage.m

@@ -69,13 +69,14 @@ NS_ASSUME_NONNULL_BEGIN
     _identityKey = identityKey;
     _verificationForRecipientId = verificationForRecipientId;
     
-    // Add 1-512 bytes of random padding bytes.
+    // This sync message should be 1-512 bytes longer than the corresponding NullMessage
+    // we store this values so the corresponding NullMessage can subtract it from the total length.
     _paddingBytesLength = arc4random_uniform(512) + 1;
 
     return self;
 }
 
-- (OWSSignalServiceProtosSyncMessage *)buildSyncMessage
+- (OWSSignalServiceProtosSyncMessageBuilder *)syncMessageBuilder
 {
     //    OWSAssert(self.tuples.count > 0);
 
@@ -101,6 +102,7 @@ NS_ASSUME_NONNULL_BEGIN
     //
 
     OWSSignalServiceProtosVerifiedBuilder *verifiedBuilder = [OWSSignalServiceProtosVerifiedBuilder new];
+    
     verifiedBuilder.destination = self.verificationForRecipientId;
     verifiedBuilder.identityKey = self.identityKey;
     verifiedBuilder.state = ^{
@@ -115,9 +117,11 @@ NS_ASSUME_NONNULL_BEGIN
     }();
     
     OWSAssert(self.paddingBytesLength != 0);
-    syncMessageBuilder.padding = [Cryptography generateRandomBytes:self.paddingBytesLength];
+    verifiedBuilder.nullMessage = [Cryptography generateRandomBytes:self.paddingBytesLength];
+    
+    syncMessageBuilder.verifiedBuilder = verifiedBuilder;
     
-    return [syncMessageBuilder build];
+    return syncMessageBuilder;
 }
 
 //- (NSArray<NSString *> *)recipientIds

src/Messages/DeviceSyncing/OWSOutgoingSentMessageTranscript.m

@@ -1,4 +1,6 @@
-//  Copyright © 2016 Open Whisper Systems. All rights reserved.
+//
+//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//
 
 #import "OWSOutgoingSentMessageTranscript.h"
 #import "OWSSignalServiceProtos.pb.h"
@@ -37,7 +39,7 @@ NS_ASSUME_NONNULL_BEGIN
     return self;
 }
 
-- (OWSSignalServiceProtosSyncMessage *)buildSyncMessage
+- (OWSSignalServiceProtosSyncMessageBuilder *)syncMessageBuilder
 {
     OWSSignalServiceProtosSyncMessageBuilder *syncMessageBuilder = [OWSSignalServiceProtosSyncMessageBuilder new];
 
@@ -49,7 +51,7 @@ NS_ASSUME_NONNULL_BEGIN
 
     [syncMessageBuilder setSentBuilder:sentBuilder];
 
-    return [syncMessageBuilder build];
+    return syncMessageBuilder;
 }
 
 @end

src/Messages/DeviceSyncing/OWSOutgoingSyncMessage.m

@@ -4,6 +4,7 @@
 
 #import "OWSOutgoingSyncMessage.h"
 #import "OWSSignalServiceProtos.pb.h"
+#import "Cryptography.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
@@ -21,19 +22,29 @@ NS_ASSUME_NONNULL_BEGIN
     return NO;
 }
 
+// This method should not be overridden, since we want to add random padding to *every* sync message
 - (OWSSignalServiceProtosSyncMessage *)buildSyncMessage
 {
-    NSAssert(NO, @"buildSyncMessage must be overridden in subclass");
+    OWSSignalServiceProtosSyncMessageBuilder *builder = [self syncMessageBuilder];
+    
+    // Add a random 1-512 bytes to obscure sync message type
+    size_t paddingBytesLength = arc4random_uniform(512) + 1;
+    builder.padding = [Cryptography generateRandomBytes:paddingBytesLength];
+    
+    return [builder build];
+}
 
-    // e.g.
-    OWSSignalServiceProtosSyncMessageBuilder *syncMessageBuilder = [OWSSignalServiceProtosSyncMessageBuilder new];
-    return [syncMessageBuilder build];
+- (OWSSignalServiceProtosSyncMessageBuilder *)syncMessageBuilder
+{
+    OWSFail(@"Abstract method should be overridden in subclass.");
+    return [OWSSignalServiceProtosSyncMessageBuilder new];
 }
 
 - (NSData *)buildPlainTextData
 {
     OWSSignalServiceProtosContentBuilder *contentBuilder = [OWSSignalServiceProtosContentBuilder new];
-    [contentBuilder setSyncMessage:[self buildSyncMessage]];
+    contentBuilder.syncMessage = [self buildSyncMessage];
+    
 
     return [[contentBuilder build] data];
 }

src/Messages/DeviceSyncing/OWSSyncContactsMessage.m

@@ -38,7 +38,7 @@ NS_ASSUME_NONNULL_BEGIN
     return self;
 }
 
-- (OWSSignalServiceProtosSyncMessage *)buildSyncMessage
+- (OWSSignalServiceProtosSyncMessageBuilder *)syncMessageBuilder
 {
     if (self.attachmentIds.count != 1) {
         DDLogError(@"expected sync contact message to have exactly one attachment, but found %lu",
@@ -57,7 +57,7 @@ NS_ASSUME_NONNULL_BEGIN
     OWSSignalServiceProtosSyncMessageBuilder *syncMessageBuilder = [OWSSignalServiceProtosSyncMessageBuilder new];
     [syncMessageBuilder setContactsBuilder:contactsBuilder];
 
-    return [syncMessageBuilder build];
+    return syncMessageBuilder;
 }
 
 - (NSData *)buildPlainTextAttachmentData

src/Messages/DeviceSyncing/OWSSyncGroupsMessage.m

@@ -19,7 +19,7 @@ NS_ASSUME_NONNULL_BEGIN
     return [super initWithTimestamp:[NSDate ows_millisecondTimeStamp]];
 }
 
-- (OWSSignalServiceProtosSyncMessage *)buildSyncMessage
+- (OWSSignalServiceProtosSyncMessageBuilder *)syncMessageBuilder
 {
 
     if (self.attachmentIds.count != 1) {
@@ -37,7 +37,7 @@ NS_ASSUME_NONNULL_BEGIN
     OWSSignalServiceProtosSyncMessageBuilder *syncMessageBuilder = [OWSSignalServiceProtosSyncMessageBuilder new];
     [syncMessageBuilder setGroupsBuilder:groupsBuilder];
 
-    return [syncMessageBuilder build];
+    return syncMessageBuilder;
 }
 
 - (NSData *)buildPlainTextAttachmentData

src/Messages/OWSMessageSender.m

@@ -1173,7 +1173,9 @@ NSString *const OWSMessageSenderRateLimitedException = @"RateLimitedException";
                                    inThread:(TSThread *)thread
 {
     NSMutableArray *messagesArray = [NSMutableArray arrayWithCapacity:recipient.devices.count];
+    
     NSData *plainText = [message buildPlainTextData];
+    DDLogDebug(@"%@ message: %@ plainTextData.length: %lu", self.tag, [message class], plainText.length);
 
     for (NSNumber *deviceNumber in recipient.devices) {
         @try {

src/Messages/OWSOutgoingNullMessage.m

@@ -40,15 +40,11 @@ NS_ASSUME_NONNULL_BEGIN
     OWSSignalServiceProtosContentBuilder *contentBuilder = [OWSSignalServiceProtosContentBuilder new];
     OWSSignalServiceProtosNullMessageBuilder *nullMessageBuilder = [OWSSignalServiceProtosNullMessageBuilder new];
 
-    // TODO padding size.
     NSUInteger contentLength = self.verificationStateSyncMessage.buildPlainTextData.length;
     contentLength -= self.verificationStateSyncMessage.paddingBytesLength;
     
     OWSAssert(contentLength > 0)
     
-    // Add 1-512 bytes of random padding bytes.
-    contentLength += arc4random_uniform(512) + 1;
-    
     nullMessageBuilder.padding = [Cryptography generateRandomBytes:contentLength];
     
     contentBuilder.nullMessage = [nullMessageBuilder build];
@@ -56,6 +52,11 @@ NS_ASSUME_NONNULL_BEGIN
     return [contentBuilder build].data;
 }
 
+- (BOOL)shouldSyncTranscript
+{
+    return NO;
+}
+
 - (void)saveWithTransaction:(YapDatabaseReadWriteTransaction *)transaction
 {
     // No-op as we don't want to actually display this as an outgoing message in our thread.