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1 files changed, 711 insertions, 0 deletions

diff --git a/Firebase/Messaging/FIRMessagingConnection.m b/Firebase/Messaging/FIRMessagingConnection.m
new file mode 100644
index 0000000..afbd0ba
--- /dev/null
+++ b/Firebase/Messaging/FIRMessagingConnection.m
@@ -0,0 +1,711 @@
+/*
+ * Copyright 2017 Google
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#import "FIRMessagingConnection.h"
+
+#import "Protos/GtalkCore.pbobjc.h"
+#import "Protos/GtalkExtensions.pbobjc.h"
+
+#import "FIRMessaging.h"
+#import "FIRMessagingDataMessageManager.h"
+#import "FIRMessagingDefines.h"
+#import "FIRMessagingLogger.h"
+#import "FIRMessagingRmqManager.h"
+#import "FIRMessagingSecureSocket.h"
+#import "FIRMessagingUtilities.h"
+#import "FIRMessagingVersionUtilities.h"
+#import "FIRMessaging_Private.h"
+
+static NSInteger const kIqSelectiveAck = 12;
+static NSInteger const kIqStreamAck = 13;
+static int const kInvalidStreamId = -1;
+// Threshold for number of messages removed that we will ack, for short lived connections
+static int const kMessageRemoveAckThresholdCount = 5;
+
+static NSTimeInterval const kHeartbeatInterval = 30.0;
+static NSTimeInterval const kConnectionTimeout = 20.0;
+static int32_t const kAckingInterval = 10;
+
+static NSString *const kUnackedS2dIdKey = @"FIRMessagingUnackedS2dIdKey";
+static NSString *const kAckedS2dIdMapKey = @"FIRMessagingAckedS2dIdMapKey";
+
+static NSString *const kRemoteFromAddress = @"from";
+
+@interface FIRMessagingD2SInfo : NSObject
+
+@property(nonatomic, readwrite, assign) int streamId;
+@property(nonatomic, readwrite, strong) NSString *d2sID;
+- (instancetype)initWithStreamId:(int)streamId d2sId:(NSString *)d2sID;
+
+@end
+
+@implementation FIRMessagingD2SInfo
+
+- (instancetype)initWithStreamId:(int)streamId d2sId:(NSString *)d2sID {
+  self = [super init];
+  if (self) {
+    _streamId = streamId;
+    _d2sID = [d2sID copy];
+  }
+  return self;
+}
+
+- (BOOL)isEqual:(id)object {
+  if ([object isKindOfClass:[self class]]) {
+    FIRMessagingD2SInfo *other = (FIRMessagingD2SInfo *)object;
+    return self.streamId == other.streamId && [self.d2sID isEqualToString:other.d2sID];
+  }
+  return NO;
+}
+
+- (NSUInteger)hash {
+  return [self.d2sID hash];
+}
+
+@end
+
+@interface FIRMessagingConnection ()<FIRMessagingSecureSocketDelegate>
+
+@property(nonatomic, readwrite, weak) FIRMessagingRmqManager *rmq2Manager;
+@property(nonatomic, readwrite, weak) FIRMessagingDataMessageManager *dataMessageManager;
+
+@property(nonatomic, readwrite, assign) FIRMessagingConnectionState state;
+@property(nonatomic, readwrite, copy) NSString *host;
+@property(nonatomic, readwrite, assign) NSUInteger port;
+
+@property(nonatomic, readwrite, strong) NSString *authId;
+@property(nonatomic, readwrite, strong) NSString *token;
+
+@property(nonatomic, readwrite, strong) FIRMessagingSecureSocket *socket;
+
+@property(nonatomic, readwrite, assign) int64_t lastLoginServerTimestamp;
+@property(nonatomic, readwrite, assign) int lastStreamIdAcked;
+@property(nonatomic, readwrite, assign) int inStreamId;
+@property(nonatomic, readwrite, assign) int outStreamId;
+
+@property(nonatomic, readwrite, strong) NSMutableArray *unackedS2dIds;
+@property(nonatomic, readwrite, strong) NSMutableDictionary *ackedS2dMap;
+@property(nonatomic, readwrite, strong) NSMutableArray *d2sInfos;
+// ttl=0 messages that need to be sent as soon as we establish a connection
+@property(nonatomic, readwrite, strong) NSMutableArray *sendOnConnectMessages;
+
+@property(nonatomic, readwrite, strong) NSRunLoop *runLoop;
+
+@end
+
+
+@implementation FIRMessagingConnection;
+
+- (instancetype)initWithAuthID:(NSString *)authId
+                         token:(NSString *)token
+                          host:(NSString *)host
+                          port:(NSUInteger)port
+                       runLoop:(NSRunLoop *)runLoop
+                   rmq2Manager:(FIRMessagingRmqManager *)rmq2Manager
+                    fcmManager:(FIRMessagingDataMessageManager *)dataMessageManager {
+  self = [super init];
+  if (self) {
+    _authId = [authId copy];
+    _token = [token copy];
+    _host = [host copy];
+    _port = port;
+    _runLoop = runLoop;
+    _rmq2Manager = rmq2Manager;
+    _dataMessageManager = dataMessageManager;
+
+    _d2sInfos = [NSMutableArray array];
+
+    _unackedS2dIds = [NSMutableArray arrayWithArray:[_rmq2Manager unackedS2dRmqIds]];
+    _ackedS2dMap = [NSMutableDictionary dictionary];
+    _sendOnConnectMessages = [NSMutableArray array];
+  }
+  return self;
+}
+
+- (NSString *)description {
+  return [NSString stringWithFormat:@"host: %@, port: %lu, stream id in: %d, stream id out: %d",
+          self.host,
+          _FIRMessaging_UL(self.port),
+          self.inStreamId,
+          self.outStreamId];
+}
+
+- (void)signIn {
+  _FIRMessagingDevAssert(self.state == kFIRMessagingConnectionNotConnected, @"Invalid connection state.");
+  if (self.state != kFIRMessagingConnectionNotConnected) {
+    return;
+  }
+
+  // break it up for testing
+  [self setupConnectionSocket];
+  [self connectToSocket:self.socket];
+}
+
+- (void)setupConnectionSocket {
+  self.socket = [[FIRMessagingSecureSocket alloc] init];
+  self.socket.delegate = self;
+}
+
+- (void)connectToSocket:(FIRMessagingSecureSocket *)socket {
+  self.state = kFIRMessagingConnectionConnecting;
+  FIRMessagingLoggerDebug(kFIRMessagingMessageCodeConnection000,
+                          @"Start connecting to FIRMessaging service.");
+  [socket connectToHost:self.host port:self.port onRunLoop:self.runLoop];
+}
+
+- (void)signOut {
+  // Clear the list of messages to be sent on connect. This will only
+  // have messages in it if an error happened before receiving the LoginResponse.
+  [self.sendOnConnectMessages removeAllObjects];
+
+  if (self.state == kFIRMessagingConnectionSignedIn) {
+    [self sendClose];
+  }
+  if (self.state != kFIRMessagingConnectionNotConnected) {
+    [self disconnect];
+  }
+}
+
+- (void)teardown {
+  if (self.state != kFIRMessagingConnectionNotConnected) {
+    [self disconnect];
+  }
+}
+
+#pragma mark - FIRMessagingSecureSocketDelegate
+
+- (void)secureSocketDidConnect:(FIRMessagingSecureSocket *)socket {
+  self.state = kFIRMessagingConnectionConnected;
+  self.lastStreamIdAcked = 0;
+  self.inStreamId = 0;
+  self.outStreamId = 0;
+
+  FIRMessagingLoggerDebug(kFIRMessagingMessageCodeConnection001,
+                          @"Connected to FIRMessaging service.");
+  [self resetUnconfirmedAcks];
+  [self sendLoginRequest:self.authId token:self.token];
+}
+
+- (void)didDisconnectWithSecureSocket:(FIRMessagingSecureSocket *)socket {
+  _FIRMessagingDevAssert(self.socket == socket, @"Invalid socket");
+  _FIRMessagingDevAssert(self.socket.state == kFIRMessagingSecureSocketClosed, @"Socket already closed");
+
+  FIRMessagingLoggerDebug(kFIRMessagingMessageCodeConnection002,
+                          @"Secure socket disconnected from FIRMessaging service.");
+  [self disconnect];
+  [self.delegate connection:self didCloseForReason:kFIRMessagingConnectionCloseReasonSocketDisconnected];
+}
+
+- (void)secureSocket:(FIRMessagingSecureSocket *)socket
+      didReceiveData:(NSData *)data
+             withTag:(int8_t)tag {
+  if (tag < 0) {
+    // Invalid proto tag
+    return;
+  }
+
+  Class klassForTag = FIRMessagingGetClassForTag((FIRMessagingProtoTag)tag);
+  if ([klassForTag isSubclassOfClass:[NSNull class]]) {
+    FIRMessagingLoggerError(kFIRMessagingMessageCodeConnection003, @"Invalid tag %d for proto",
+                            tag);
+    return;
+  }
+
+  GPBMessage *proto = [klassForTag parseFromData:data error:NULL];
+  if (tag == kFIRMessagingProtoTagLoginResponse && self.state != kFIRMessagingConnectionConnected) {
+    FIRMessagingLoggerDebug(
+        kFIRMessagingMessageCodeConnection004,
+        @"Should not receive generated message when the connection is not connected.");
+    return;
+  } else if (tag != kFIRMessagingProtoTagLoginResponse && self.state != kFIRMessagingConnectionSignedIn) {
+    FIRMessagingLoggerDebug(
+        kFIRMessagingMessageCodeConnection005,
+        @"Should not receive generated message when the connection is not signed in.");
+    return;
+  }
+
+  // If traffic is received after a heartbeat it is safe to assume the connection is healthy.
+  [self cancelConnectionTimeoutTask];
+  [self performSelector:@selector(sendHeartbeatPing)
+             withObject:nil
+             afterDelay:kHeartbeatInterval];
+
+  [self willProcessProto:proto];
+  switch (tag) {
+    case kFIRMessagingProtoTagLoginResponse:
+      [self didReceiveLoginResponse:(GtalkLoginResponse *)proto];
+      break;
+    case kFIRMessagingProtoTagDataMessageStanza:
+      [self didReceiveDataMessageStanza:(GtalkDataMessageStanza *)proto];
+      break;
+    case kFIRMessagingProtoTagHeartbeatPing:
+      [self didReceiveHeartbeatPing:(GtalkHeartbeatPing *)proto];
+      break;
+    case kFIRMessagingProtoTagHeartbeatAck:
+      [self didReceiveHeartbeatAck:(GtalkHeartbeatAck *)proto];
+      break;
+    case kFIRMessagingProtoTagClose:
+      [self didReceiveClose:(GtalkClose *)proto];
+      break;
+    case kFIRMessagingProtoTagIqStanza:
+      [self handleIqStanza:(GtalkIqStanza *)proto];
+      break;
+    default:
+      [self didReceiveUnhandledProto:proto];
+      break;
+  }
+}
+
+// Called from secure socket once we have send the proto with given rmqId over the wire
+// since we are mostly concerned with user facing messages which certainly have a rmqId
+// we can retrieve them from the Rmq if necessary to look at stuff but for now we just
+// log it.
+- (void)secureSocket:(FIRMessagingSecureSocket *)socket
+ didSendProtoWithTag:(int8_t)tag
+               rmqId:(NSString *)rmqId {
+  // log the message
+  [self logMessage:rmqId messageType:tag isOut:YES];
+}
+
+#pragma mark - FIRMessagingTestConnection
+
+- (void)sendProto:(GPBMessage *)proto {
+  FIRMessagingProtoTag tag = FIRMessagingGetTagForProto(proto);
+  if (tag == kFIRMessagingProtoTagLoginRequest && self.state != kFIRMessagingConnectionConnected) {
+    FIRMessagingLoggerDebug(kFIRMessagingMessageCodeConnection006,
+                            @"Cannot send generated message when the connection is not connected.");
+    return;
+  } else if (tag != kFIRMessagingProtoTagLoginRequest && self.state != kFIRMessagingConnectionSignedIn) {
+    FIRMessagingLoggerDebug(kFIRMessagingMessageCodeConnection007,
+                            @"Cannot send generated message when the connection is not signed in.");
+    return;
+  }
+
+  _FIRMessagingDevAssert(self.socket != nil, @"Socket shouldn't be nil");
+  if (self.socket == nil) {
+    return;
+  }
+
+  [self willSendProto:proto];
+
+  [self.socket sendData:proto.data withTag:tag rmqId:FIRMessagingGetRmq2Id(proto)];
+}
+
+- (void)sendOnConnectOrDrop:(GPBMessage *)message {
+  if (self.state == kFIRMessagingConnectionSignedIn) {
+    // If a connection has already been established, send normally
+    [self sendProto:message];
+  } else {
+    // Otherwise add them to the list of messages to send after login
+    [self.sendOnConnectMessages addObject:message];
+  }
+}
+
++ (GtalkLoginRequest *)loginRequestWithToken:(NSString *)token authID:(NSString *)authID {
+  GtalkLoginRequest *login = [[GtalkLoginRequest alloc] init];
+  login.accountId = 1000000;
+  login.authService = GtalkLoginRequest_AuthService_AndroidId;
+  login.authToken = token;
+  login.id_p = [NSString stringWithFormat:@"%@-%@", @"ios", FIRMessagingCurrentLibraryVersion()];
+  login.domain = @"mcs.android.com";
+  login.deviceId = [NSString stringWithFormat:@"android-%llx", authID.longLongValue];
+  login.networkType = [self currentNetworkType];
+  login.resource = authID;
+  login.user = authID;
+  login.useRmq2 = YES;
+  login.lastRmqId = 1; // Sending not enabled yet so this stays as 1.
+  return login;
+}
+
++ (int32_t)currentNetworkType {
+  // http://developer.android.com/reference/android/net/ConnectivityManager.html
+  int32_t fcmNetworkType;
+  FIRMessagingNetworkStatus type = [[FIRMessaging messaging] networkType];
+  switch (type) {
+    case kFIRMessagingReachabilityReachableViaWiFi:
+      fcmNetworkType = 1;
+      break;
+
+    case kFIRMessagingReachabilityReachableViaWWAN:
+      fcmNetworkType = 0;
+      break;
+
+    default:
+      fcmNetworkType = -1;
+      break;
+  }
+  return fcmNetworkType;
+}
+
+- (void)sendLoginRequest:(NSString *)authId
+                   token:(NSString *)token {
+  GtalkLoginRequest *login = [[self class] loginRequestWithToken:token authID:authId];
+
+  // clear the messages sent during last connection
+  if ([self.d2sInfos count]) {
+    [self.d2sInfos removeAllObjects];
+  }
+
+  if (self.unackedS2dIds.count > 0) {
+    FIRMessagingLoggerDebug(
+        kFIRMessagingMessageCodeConnection008,
+        @"There are unacked persistent Ids in the login request: %@",
+        [self.unackedS2dIds.description stringByReplacingOccurrencesOfString:@"%"
+                                                                  withString:@"%%"]);
+  }
+  // Send out acks.
+  for (NSString *unackedPersistentS2dId in self.unackedS2dIds) {
+    [login.receivedPersistentIdArray addObject:unackedPersistentS2dId];
+  }
+
+  GtalkSetting *setting = [[GtalkSetting alloc] init];
+  setting.name = @"new_vc";
+  setting.value = @"1";
+  [login.settingArray addObject:setting];
+
+  [self sendProto:login];
+}
+
+- (void)sendHeartbeatAck {
+  [self sendProto:[[GtalkHeartbeatAck alloc] init]];
+}
+
+- (void)sendHeartbeatPing {
+  // cancel the previous heartbeat request.
+  [NSObject cancelPreviousPerformRequestsWithTarget:self
+                                           selector:@selector(sendHeartbeatPing)
+                                             object:nil];
+  [self scheduleConnectionTimeoutTask];
+  [self sendProto:[[GtalkHeartbeatPing alloc] init]];
+}
+
++ (GtalkIqStanza *)createStreamAck {
+  GtalkIqStanza *iq = [[GtalkIqStanza alloc] init];
+  iq.type = GtalkIqStanza_IqType_Set;
+  iq.id_p = @"";
+  GtalkExtension *ext = [[GtalkExtension alloc] init];
+  ext.id_p = kIqStreamAck;
+  ext.data_p = @"";
+  iq.extension = ext;
+  return iq;
+}
+
+- (void)sendStreamAck {
+  GtalkIqStanza *iq = [[self class] createStreamAck];
+  [self sendProto:iq];
+}
+
+- (void)sendClose {
+  [self sendProto:[[GtalkClose alloc] init]];
+}
+
+- (void)handleIqStanza:(GtalkIqStanza *)iq {
+  if (iq.hasExtension) {
+    if (iq.extension.id_p == kIqStreamAck) {
+      [self didReceiveStreamAck:iq];
+      return;
+    }
+    if (iq.extension.id_p == kIqSelectiveAck) {
+      [self didReceiveSelectiveAck:iq];
+      return;
+    }
+    FIRMessagingLoggerDebug(kFIRMessagingMessageCodeConnection009, @"Unknown ack extension id %d.",
+                            iq.extension.id_p);
+  } else {
+    FIRMessagingLoggerDebug(kFIRMessagingMessageCodeConnection010, @"Ip stanza without extension.");
+  }
+  [self didReceiveUnhandledProto:iq];
+}
+
+- (void)didReceiveLoginResponse:(GtalkLoginResponse *)loginResponse {
+  if (loginResponse.hasError) {
+    FIRMessagingLoggerDebug(kFIRMessagingMessageCodeConnection011,
+                            @"Login error with type: %@, message: %@.", loginResponse.error.type,
+                            loginResponse.error.message);
+    return;
+  }
+  FIRMessagingLoggerDebug(kFIRMessagingMessageCodeConnection012, @"Logged onto MCS service.");
+  // We sent the persisted list of unack'd messages with login so we can assume they have been ack'd
+  // by the server.
+  _FIRMessagingDevAssert(self.unackedS2dIds.count == 0, @"No ids present");
+  _FIRMessagingDevAssert(self.outStreamId == 1, @"Login should be the first stream id");
+
+  self.state = kFIRMessagingConnectionSignedIn;
+  self.lastLoginServerTimestamp = loginResponse.serverTimestamp;
+  [self.delegate didLoginWithConnection:self];
+  [self sendHeartbeatPing];
+
+  // Add all the TTL=0 messages on connect
+  for (GPBMessage *message in self.sendOnConnectMessages) {
+    [self sendProto:message];
+  }
+  [self.sendOnConnectMessages removeAllObjects];
+}
+
+- (void)didReceiveHeartbeatPing:(GtalkHeartbeatPing *)heartbeatPing {
+  [self sendHeartbeatAck];
+}
+
+- (void)didReceiveHeartbeatAck:(GtalkHeartbeatAck *)heartbeatAck {
+#if FIRMessaging_PROBER
+  self.lastHeartbeatPingTimestamp = FIRMessagingCurrentTimestampInSeconds();
+#endif
+}
+
+- (void)didReceiveDataMessageStanza:(GtalkDataMessageStanza *)dataMessageStanza {
+  // TODO: Maybe add support raw data later
+  [self.delegate connectionDidRecieveMessage:dataMessageStanza];
+}
+
+- (void)didReceiveUnhandledProto:(GPBMessage *)proto {
+  FIRMessagingLoggerDebug(kFIRMessagingMessageCodeConnection013, @"Received unhandled proto");
+}
+
+- (void)didReceiveStreamAck:(GtalkIqStanza *)iq {
+  // Server received some stuff from us we don't really need to do anything special
+}
+
+- (void)didReceiveSelectiveAck:(GtalkIqStanza *)iq {
+  GtalkExtension *extension = iq.extension;
+  if (extension) {
+    int extensionId = extension.id_p;
+    if (extensionId == kIqSelectiveAck) {
+
+      NSString *dataString = extension.data_p;
+      GtalkSelectiveAck *selectiveAck = [[GtalkSelectiveAck alloc] init];
+      [selectiveAck mergeFromData:[dataString dataUsingEncoding:NSUTF8StringEncoding]
+                extensionRegistry:nil];
+
+      NSArray <NSString *>*acks = [selectiveAck idArray];
+
+      // we've received ACK's
+      [self.delegate connectionDidReceiveAckForRmqIds:acks];
+
+      // resend unacked messages
+      [self.dataMessageManager resendMessagesWithConnection:self];
+    }
+  }
+}
+
+- (void)didReceiveClose:(GtalkClose *)close {
+  [self disconnect];
+}
+
+- (void)willProcessProto:(GPBMessage *)proto {
+  self.inStreamId++;
+
+  if ([proto isKindOfClass:GtalkDataMessageStanza.class]) {
+    FIRMessagingLoggerDebug(kFIRMessagingMessageCodeConnection014,
+                            @"RMQ: Receiving %@ with rmq_id: %@ incoming stream Id: %d",
+                            proto.class, FIRMessagingGetRmq2Id(proto), self.inStreamId);
+  } else {
+    FIRMessagingLoggerDebug(kFIRMessagingMessageCodeConnection015,
+                            @"RMQ: Receiving %@ with incoming stream Id: %d.", proto.class,
+                            self.inStreamId);
+  }
+  int streamId = FIRMessagingGetLastStreamId(proto);
+  if (streamId != kInvalidStreamId) {
+    // confirm the D2S messages that were sent by us
+    [self confirmAckedD2sIdsWithStreamId:streamId];
+
+    // We can now confirm that our ack was received by the server and start our unack'd list fresh
+    // with the proto we just received.
+    [self confirmAckedS2dIdsWithStreamId:streamId];
+  }
+  NSString *rmq2Id = FIRMessagingGetRmq2Id(proto);
+  if (rmq2Id != nil) {
+    FIRMessagingLoggerDebug(kFIRMessagingMessageCodeConnection016,
+                            @"RMQ: Add unacked persistent Id: %@.",
+                            [rmq2Id stringByReplacingOccurrencesOfString:@"%" withString:@"%%"]);
+    [self.unackedS2dIds addObject:rmq2Id];
+    [self.rmq2Manager saveS2dMessageWithRmqId:rmq2Id]; // RMQ save
+  }
+  BOOL explicitAck = ([proto isKindOfClass:[GtalkDataMessageStanza class]] &&
+                      [(GtalkDataMessageStanza *)proto immediateAck]);
+  // If we have not sent anything and the ack threshold has been reached then explicitly send one
+  // to notify the server that we have received messages.
+  if (self.inStreamId - self.lastStreamIdAcked >= kAckingInterval || explicitAck) {
+    [self sendStreamAck];
+  }
+}
+
+- (void)willSendProto:(GPBMessage *)proto {
+  self.outStreamId++;
+
+  NSString *rmq2Id = FIRMessagingGetRmq2Id(proto);
+  if ([rmq2Id length]) {
+    FIRMessagingD2SInfo *d2sInfo = [[FIRMessagingD2SInfo alloc] initWithStreamId:self.outStreamId d2sId:rmq2Id];
+    [self.d2sInfos addObject:d2sInfo];
+  }
+
+  // each time we send a d2s message, it acks previously received
+  // s2d messages via the last (s2d) stream id received.
+
+  FIRMessagingLoggerDebug(kFIRMessagingMessageCodeConnection017,
+                          @"RMQ: Sending %@ with outgoing stream Id: %d.", proto.class,
+                          self.outStreamId);
+  // We have received messages since last time we sent something - send ack info to server.
+  if (self.inStreamId > self.lastStreamIdAcked) {
+    FIRMessagingSetLastStreamId(proto, self.inStreamId);
+    self.lastStreamIdAcked = self.inStreamId;
+  }
+
+  if (self.unackedS2dIds.count > 0) {
+    // Move all 'unack'd' messages to the ack'd map so they can be removed once the
+    // ack is confirmed.
+    NSArray *ackedS2dIds = [NSArray arrayWithArray:self.unackedS2dIds];
+    FIRMessagingLoggerDebug(
+        kFIRMessagingMessageCodeConnection018, @"RMQ: Mark persistent Ids as acked: %@.",
+        [ackedS2dIds.description stringByReplacingOccurrencesOfString:@"%" withString:@"%%"]);
+    [self.unackedS2dIds removeAllObjects];
+    self.ackedS2dMap[[@(self.outStreamId) stringValue]] = ackedS2dIds;
+  }
+}
+
+#pragma mark - Private
+
+/**
+ * This processes the s2d message received in reference to the d2s messages
+ * that we have sent before.
+ */
+- (void)confirmAckedD2sIdsWithStreamId:(int)lastReceivedStreamId {
+  NSMutableArray *d2sIdsAcked = [NSMutableArray array];
+  for (FIRMessagingD2SInfo *d2sInfo in self.d2sInfos) {
+    if (lastReceivedStreamId < d2sInfo.streamId) {
+      break;
+    }
+    [d2sIdsAcked addObject:d2sInfo];
+  }
+
+  NSMutableArray *rmqIds = [NSMutableArray arrayWithCapacity:[d2sIdsAcked count]];
+  // remove ACK'ed messages
+  for (FIRMessagingD2SInfo *d2sInfo in d2sIdsAcked) {
+    if ([d2sInfo.d2sID length]) {
+      [rmqIds addObject:d2sInfo.d2sID];
+    }
+    [self.d2sInfos removeObject:d2sInfo];
+  }
+  [self.delegate connectionDidReceiveAckForRmqIds:rmqIds];
+  int count = [self.delegate connectionDidReceiveAckForRmqIds:rmqIds];
+  if (kMessageRemoveAckThresholdCount > 0 && count >= kMessageRemoveAckThresholdCount) {
+    // For short lived connections, if a large number of messages are removed, send an
+    // ack straight away so the server knows that this message was received.
+    [self sendStreamAck];
+  }
+}
+
+/**
+ * Called when a stream ACK or a selective ACK are received - this indicates the message has
+ * been received by MCS.
+ */
+- (void)didReceiveAckForRmqIds:(NSArray *)rmqIds {
+  // TODO: let the user know that the following messages were received by the server
+}
+
+- (void)confirmAckedS2dIdsWithStreamId:(int)lastReceivedStreamId {
+  // If the server hasn't received the streamId yet.
+  FIRMessagingLoggerDebug(kFIRMessagingMessageCodeConnection019,
+                          @"RMQ: Server last received stream Id: %d.", lastReceivedStreamId);
+  if (lastReceivedStreamId < self.outStreamId) {
+    // TODO: This could be a good indicator that we need to re-send something (acks)?
+    FIRMessagingLoggerDebug(kFIRMessagingMessageCodeConnection020,
+                            @"RMQ: There are unsent messages that should be send...\n"
+                             "server received: %d\nlast stream id sent: %d",
+                            lastReceivedStreamId, self.outStreamId);
+  }
+
+  NSSet *ackedStreamIds =
+    [self.ackedS2dMap keysOfEntriesPassingTest:^BOOL(id key, id obj, BOOL *stop) {
+      NSString *streamId = key;
+      return streamId.intValue <= lastReceivedStreamId;
+    }];
+  NSMutableArray *s2dIdsToDelete = [NSMutableArray array];
+
+  for (NSString *streamId in ackedStreamIds) {
+    NSArray *ackedS2dIds = self.ackedS2dMap[streamId];
+    if (ackedS2dIds.count > 0) {
+      FIRMessagingLoggerDebug(
+          kFIRMessagingMessageCodeConnection021,
+          @"RMQ: Mark persistent Ids as confirmed by stream id %@: %@.", streamId,
+          [ackedS2dIds.description stringByReplacingOccurrencesOfString:@"%" withString:@"%%"]);
+      [self.ackedS2dMap removeObjectForKey:streamId];
+    }
+
+    [s2dIdsToDelete addObjectsFromArray:ackedS2dIds];
+  }
+
+  // clean up s2d ids that the server knows we've received.
+  // we let the server know via a s2d last stream id received in a
+  // d2s message. the server lets us know it has received our d2s
+  // message via a d2s last stream id received in a s2d message.
+  [self.rmq2Manager removeS2dIds:s2dIdsToDelete];
+}
+
+- (void)resetUnconfirmedAcks {
+  [self.ackedS2dMap enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
+    [self.unackedS2dIds addObjectsFromArray:obj];
+  }];
+  [self.ackedS2dMap removeAllObjects];
+}
+
+- (void)disconnect {
+  _FIRMessagingDevAssert(self.state != kFIRMessagingConnectionNotConnected, @"Connection already not connected");
+  // cancel pending timeout tasks.
+  [self cancelConnectionTimeoutTask];
+  // cancel pending heartbeat.
+  [NSObject cancelPreviousPerformRequestsWithTarget:self
+                                           selector:@selector(sendHeartbeatPing)
+                                             object:nil];
+  // Unset the delegate. FIRMessagingConnection will not receive further events from the socket from now on.
+  self.socket.delegate = nil;
+  [self.socket disconnect];
+  self.state = kFIRMessagingConnectionNotConnected;
+}
+
+- (void)connectionTimedOut {
+  FIRMessagingLoggerDebug(kFIRMessagingMessageCodeConnection022,
+                          @"Connection to FIRMessaging service timed out.");
+  [self disconnect];
+  [self.delegate connection:self didCloseForReason:kFIRMessagingConnectionCloseReasonTimeout];
+}
+
+- (void)scheduleConnectionTimeoutTask {
+  // cancel the previous heartbeat timeout event and schedule a new one.
+  [self cancelConnectionTimeoutTask];
+  [self performSelector:@selector(connectionTimedOut)
+             withObject:nil
+             afterDelay:[self connectionTimeoutInterval]];
+}
+
+- (void)cancelConnectionTimeoutTask {
+  // cancel pending timeout tasks.
+  [NSObject cancelPreviousPerformRequestsWithTarget:self
+                                           selector:@selector(connectionTimedOut)
+                                             object:nil];
+}
+
+- (void)logMessage:(NSString *)description messageType:(int)messageType isOut:(BOOL)isOut {
+  messageType = isOut ? -messageType : messageType;
+  FIRMessagingLoggerDebug(kFIRMessagingMessageCodeConnection023,
+                          @"Send msg: %@ type: %d inStreamId: %d outStreamId: %d", description,
+                          messageType, self.inStreamId, self.outStreamId);
+}
+
+- (NSTimeInterval)connectionTimeoutInterval {
+  return kConnectionTimeout;
+}
+
+@end