Prevent session corruption by using a single serial queue for encrypt and decrypt

coordinate SignalProtocol encryption/decryption on a single serial
queue. Previously message sending encrypted on the sending thread, while
message receiving decrypted on the main thread.

// FREEBIE

Podfile

@@ -3,8 +3,9 @@ source 'https://github.com/CocoaPods/Specs.git'
 
 target 'Signal' do
     pod 'SocketRocket',               :git => 'https://github.com/facebook/SocketRocket.git'
-    pod 'AxolotlKit', git: 'https://github.com/WhisperSystems/SignalProtocolKit.git'
-    pod 'SignalServiceKit',           git: 'https://github.com/WhisperSystems/SignalServiceKit.git', branch: 'master'
+    pod 'AxolotlKit',                 git: 'https://github.com/WhisperSystems/SignalProtocolKit.git', branch: 'mkirk/session-corruption'
+    #pod 'AxolotlKit',                 path: '../SignalProtocolKit'
+    pod 'SignalServiceKit',           git: 'https://github.com/WhisperSystems/SignalServiceKit.git'
     #pod 'SignalServiceKit',           path: '../SignalServiceKit'
     pod 'OpenSSL'
     pod 'PastelogKit',                '~> 1.3'

Podfile.lock

@@ -115,31 +115,31 @@ PODS:
   - ZXingObjC/All (3.1.0)
 
 DEPENDENCIES:
-  - AxolotlKit (from `https://github.com/WhisperSystems/SignalProtocolKit.git`)
+  - AxolotlKit (from `https://github.com/WhisperSystems/SignalProtocolKit.git`, branch `mkirk/session-corruption`)
   - FFCircularProgressView (~> 0.5)
   - JSQMessagesViewController
   - OpenSSL
   - PastelogKit (~> 1.3)
   - SCWaveformView (~> 1.0)
-  - SignalServiceKit (from `https://github.com/WhisperSystems/SignalServiceKit.git`, branch `master`)
+  - SignalServiceKit (from `https://github.com/WhisperSystems/SignalServiceKit.git`)
   - SocketRocket (from `https://github.com/facebook/SocketRocket.git`)
   - ZXingObjC
 
 EXTERNAL SOURCES:
   AxolotlKit:
+    :branch: mkirk/session-corruption
     :git: https://github.com/WhisperSystems/SignalProtocolKit.git
   SignalServiceKit:
-    :branch: master
     :git: https://github.com/WhisperSystems/SignalServiceKit.git
   SocketRocket:
     :git: https://github.com/facebook/SocketRocket.git
 
 CHECKOUT OPTIONS:
   AxolotlKit:
-    :commit: 714f5ebe199ecc999b33c6f97a4bb57e2db90e75
+    :commit: 55630ef62403de7eee31ac42b8827e390b6194f3
     :git: https://github.com/WhisperSystems/SignalProtocolKit.git
   SignalServiceKit:
-    :commit: a112930277890f78676ae32632e9e1ed44034c45
+    :commit: 32aad85a7861433571c70622fe720098275cad56
     :git: https://github.com/WhisperSystems/SignalServiceKit.git
   SocketRocket:
     :commit: 41b57bb2fc292a814f758441a05243eb38457027
@@ -170,6 +170,6 @@ SPEC CHECKSUMS:
   YapDatabase: b1e43555a34a5298e23a045be96817a5ef0da58f
   ZXingObjC: bf15b3814f7a105b6d99f47da2333c93a063650a
 
-PODFILE CHECKSUM: cb24c78080551874a45d1a20de4a1bef7427b41f
+PODFILE CHECKSUM: 0b9f2a480586a683632948584eb8eba8ab0f4283
 
 COCOAPODS: 1.0.1

Signal/src/AppDelegate.m

@@ -21,9 +21,11 @@
 #import "TSSocketManager.h"
 #import "TextSecureKitEnv.h"
 #import "VersionMigrations.h"
+#import <AxolotlKit/SessionCipher.h>
 #import <PastelogKit/Pastelog.h>
 #import <PromiseKit/AnyPromise.h>
 #import <SignalServiceKit/OWSDisappearingMessagesJob.h>
+#import <SignalServiceKit/OWSDispatch.h>
 #import <SignalServiceKit/OWSIncomingMessageReadObserver.h>
 #import <SignalServiceKit/OWSMessageSender.h>
 #import <SignalServiceKit/TSAccountManager.h>
@@ -175,6 +177,9 @@ static NSString *const kURLHostVerifyPrefix             = @"verify";
 }
 
 - (void)setupTSKitEnv {
+    // Encryption/Descryption mutates session state and must be synchronized on a serial queue.
+    [SessionCipher setSessionCipherDispatchQueue:[OWSDispatch sessionCipher]];
+
     [TextSecureKitEnv sharedEnv].contactsManager = [Environment getCurrent].contactsManager;
     [[TSStorageManager sharedManager] setupDatabase];
     [TextSecureKitEnv sharedEnv].notificationsManager = [[NotificationsManager alloc] init];