98 lines
3.2 KiB
Objective-C
98 lines
3.2 KiB
Objective-C
//
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// Copyright (c) 2018 Open Whisper Systems. All rights reserved.
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//
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#import "OWSOutgoingNullMessage.h"
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#import "Cryptography.h"
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#import "OWSVerificationStateSyncMessage.h"
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#import "TSContactThread.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, 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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verificationStateSyncMessage:(OWSVerificationStateSyncMessage *)verificationStateSyncMessage
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{
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self = [super initOutgoingMessageWithTimestamp:[NSDate ows_millisecondTimeStamp]
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inThread:contactThread
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messageBody:nil
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attachmentIds:[NSMutableArray new]
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expiresInSeconds:0
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expireStartedAt:0
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isVoiceMessage:NO
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groupMetaMessage:TSGroupMetaMessageUnspecified
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quotedMessage:nil
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contactShare:nil];
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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:(SignalRecipient *)recipient
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{
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SSKProtoNullMessageBuilder *nullMessageBuilder = [SSKProtoNullMessageBuilder new];
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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 that
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// the sync message is indistinguishable from an outgoing Sent transcript corresponding to the NullMessage. We pad
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// the NullMessage so as to obscure it's content. The sync message (like all sync messages) will be *additionally*
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// padded by the superclass while being sent. The end result is we send a NullMessage of a non-distinct size, and a
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// 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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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 = [SSKProtoContentBuilder new];
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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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