102 lines
3.3 KiB
Objective-C
102 lines
3.3 KiB
Objective-C
//
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// Copyright (c) 2021 Open Whisper Systems. All rights reserved.
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//
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#import "OWSOutgoingNullMessage.h"
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#import "OWSVerificationStateSyncMessage.h"
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#import "TSContactThread.h"
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#import <SignalCoreKit/Cryptography.h>
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#import <SignalCoreKit/NSDate+OWS.h>
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#import <SignalServiceKit/SignalServiceKit-Swift.h>
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NS_ASSUME_NONNULL_BEGIN
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@interface OWSOutgoingNullMessage ()
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@property (nonatomic, nullable, readonly) OWSVerificationStateSyncMessage *verificationStateSyncMessage;
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@end
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#pragma mark -
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@implementation OWSOutgoingNullMessage
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- (instancetype)initWithContactThread:(TSContactThread *)contactThread
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{
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TSOutgoingMessageBuilder *messageBuilder =
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[TSOutgoingMessageBuilder outgoingMessageBuilderWithThread:contactThread];
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return [super initOutgoingMessageWithBuilder:messageBuilder];
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}
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- (instancetype)initWithContactThread:(TSContactThread *)contactThread
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verificationStateSyncMessage:(OWSVerificationStateSyncMessage *)verificationStateSyncMessage
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{
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TSOutgoingMessageBuilder *messageBuilder =
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[TSOutgoingMessageBuilder outgoingMessageBuilderWithThread:contactThread];
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self = [super initOutgoingMessageWithBuilder:messageBuilder];
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if (!self) {
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return self;
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}
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_verificationStateSyncMessage = verificationStateSyncMessage;
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return self;
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}
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#pragma mark - override TSOutgoingMessage
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- (nullable NSData *)buildPlainTextData:(SignalServiceAddress *)address
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thread:(TSThread *)thread
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transaction:(SDSAnyReadTransaction *)transaction
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{
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SSKProtoNullMessageBuilder *nullMessageBuilder = [SSKProtoNullMessage builder];
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if (self.verificationStateSyncMessage) {
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NSUInteger contentLength = self.verificationStateSyncMessage.unpaddedVerifiedLength;
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OWSAssertDebug(self.verificationStateSyncMessage.paddingBytesLength > 0);
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// We add the same amount of padding in the VerificationStateSync message and it's coresponding NullMessage so
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// that the sync message is indistinguishable from an outgoing Sent transcript corresponding to the NullMessage.
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// We pad the NullMessage so as to obscure it's content. The sync message (like all sync messages) will be
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// *additionally* padded by the superclass while being sent. The end result is we send a NullMessage of a
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// non-distinct size, and a verification sync which is ~1-512 bytes larger then that.
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contentLength += self.verificationStateSyncMessage.paddingBytesLength;
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OWSAssertDebug(contentLength > 0);
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nullMessageBuilder.padding = [Cryptography generateRandomBytes:contentLength];
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}
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NSError *error;
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SSKProtoNullMessage *_Nullable nullMessage = [nullMessageBuilder buildAndReturnError:&error];
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if (error || !nullMessage) {
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OWSFailDebug(@"could not build protobuf: %@", error);
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return nil;
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}
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SSKProtoContentBuilder *contentBuilder = [SSKProtoContent builder];
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contentBuilder.nullMessage = nullMessage;
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NSData *_Nullable contentData = [contentBuilder buildSerializedDataAndReturnError:&error];
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if (error || !contentData) {
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OWSFailDebug(@"could not serialize protobuf: %@", error);
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return nil;
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}
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return contentData;
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}
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- (BOOL)shouldSyncTranscript
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{
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return NO;
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}
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- (BOOL)shouldBeSaved
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{
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return NO;
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}
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@end
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NS_ASSUME_NONNULL_END
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