Sync EndSession messages to linked devices

Alternatively, I considered deleting *only* the session with the device
which sent the message, but since other clients are deleting *all*
sessions associated with the contact, it will be less disruptive to get
in line with their behavior.

Fixes the scenario wherein:

* Alice.1 has a session with Bob.1 and Bob.2
* Bob.1 sends an EndSession to Alice
* Thus Alice.1 deletes her sessions with Bob.1 and Bob.2
* Bob.2 sends Alice1 "hi" (with the existing session - as a regular WM,
not a PKWM)
* Alice has no session with Bob.2 so cannot decrypt the message.

// FREEBIE

src/Devices/OWSRecordTranscriptJob.m

@@ -7,8 +7,9 @@
 #import "OWSDisappearingMessagesJob.h"
 #import "OWSIncomingSentMessageTranscript.h"
 #import "OWSMessageSender.h"
+#import "TSInfoMessage.h"
 #import "TSOutgoingMessage.h"
-#import "TSStorageManager.h"
+#import "TSStorageManager+SessionStore.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
@@ -17,6 +18,7 @@ NS_ASSUME_NONNULL_BEGIN
 @property (nonatomic, readonly) OWSIncomingSentMessageTranscript *incomingSentMessageTranscript;
 @property (nonatomic, readonly) OWSMessageSender *messageSender;
 @property (nonatomic, readonly) TSNetworkManager *networkManager;
+@property (nonatomic, readonly) TSStorageManager *storageManager;
 
 @end
 
@@ -34,6 +36,7 @@ NS_ASSUME_NONNULL_BEGIN
     _incomingSentMessageTranscript = incomingSentMessageTranscript;
     _messageSender = messageSender;
     _networkManager = networkManager;
+    _storageManager = [TSStorageManager sharedManager];
 
     return self;
 }
@@ -42,6 +45,18 @@ NS_ASSUME_NONNULL_BEGIN
 {
     OWSIncomingSentMessageTranscript *transcript = self.incomingSentMessageTranscript;
     DDLogDebug(@"%@ Recording transcript: %@", self.tag, transcript);
+
+    if (transcript.isEndSessionMessage) {
+        DDLogInfo(@"%@ EndSession was sent to recipient: %@.", self.tag, transcript.recipientId);
+        [self.storageManager deleteAllSessionsForContact:transcript.recipientId];
+        [[[TSInfoMessage alloc] initWithTimestamp:transcript.timestamp
+                                         inThread:transcript.thread
+                                      messageType:TSInfoMessageTypeSessionDidEnd] save];
+
+        // Don't continue processing lest we print a bubble for the session reset.
+        return;
+    }
+
     TSThread *thread = transcript.thread;
     OWSAttachmentsProcessor *attachmentsProcessor =
         [[OWSAttachmentsProcessor alloc] initWithAttachmentProtos:transcript.attachmentPointerProtos

src/Messages/DeviceSyncing/OWSIncomingSentMessageTranscript.h

@@ -1,4 +1,6 @@
-//  Copyright © 2016 Open Whisper Systems. All rights reserved.
+//
+//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//
 
 NS_ASSUME_NONNULL_BEGIN
 
@@ -24,6 +26,7 @@ NS_ASSUME_NONNULL_BEGIN
 @property (nonatomic, readonly) TSThread *thread;
 @property (nonatomic, readonly) BOOL isGroupUpdate;
 @property (nonatomic, readonly) BOOL isExpirationTimerUpdate;
+@property (nonatomic, readonly) BOOL isEndSessionMessage;
 @property (nullable, nonatomic, readonly) NSData *groupId;
 @property (nonatomic, readonly) NSString *body;
 @property (nonatomic, readonly) NSArray<OWSSignalServiceProtosAttachmentPointer *> *attachmentPointerProtos;

src/Messages/DeviceSyncing/OWSIncomingSentMessageTranscript.m

@@ -1,4 +1,6 @@
-//  Copyright © 2016 Open Whisper Systems. All rights reserved.
+//
+//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//
 
 #import "OWSIncomingSentMessageTranscript.h"
 #import "OWSAttachmentsProcessor.h"
@@ -33,6 +35,7 @@ NS_ASSUME_NONNULL_BEGIN
     _groupId = _dataMessage.group.id;
     _isGroupUpdate = _dataMessage.hasGroup && (_dataMessage.group.type == OWSSignalServiceProtosGroupContextTypeUpdate);
     _isExpirationTimerUpdate = (_dataMessage.flags & OWSSignalServiceProtosDataMessageFlagsExpirationTimerUpdate) != 0;
+    _isEndSessionMessage = (_dataMessage.flags & OWSSignalServiceProtosDataMessageFlagsEndSession) != 0;
 
     return self;
 }