From b442075205800eb730bd7b14a3a7e02607cbbbd0 Mon Sep 17 00:00:00 2001
From: Ryan Huffman <ryanhuffman@gmail.com>
Date: Mon, 29 Feb 2016 14:22:08 -0800
Subject: [PATCH] Add initial seq number to handshake

---
 libraries/networking/src/udt/Connection.cpp | 14 ++++++++++---
 libraries/networking/src/udt/SendQueue.cpp  | 22 +++++++++++++--------
 libraries/networking/src/udt/SendQueue.h    |  2 +-
 3 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/libraries/networking/src/udt/Connection.cpp b/libraries/networking/src/udt/Connection.cpp
index 1ab8441ba3..cb197f15c7 100644
--- a/libraries/networking/src/udt/Connection.cpp
+++ b/libraries/networking/src/udt/Connection.cpp
@@ -731,15 +731,20 @@ void Connection::processNAK(std::unique_ptr<ControlPacket> controlPacket) {
 }
 
 void Connection::processHandshake(std::unique_ptr<ControlPacket> controlPacket) {
+    SequenceNumber initialSequenceNumber;
+    controlPacket->readPrimitive(&initialSequenceNumber);
     
-    if (!_hasReceivedHandshake || _hasReceivedData) {
+    if (!_hasReceivedHandshake || initialSequenceNumber != _initialReceiveSequenceNumber) {
         // server sent us a handshake - we need to assume this means state should be reset
         // as long as we haven't received a handshake yet or we have and we've received some data
         resetReceiveState();
+        _initialReceiveSequenceNumber = initialSequenceNumber;
     }
     
     // immediately respond with a handshake ACK
-    static auto handshakeACK = ControlPacket::create(ControlPacket::HandshakeACK, 0);
+    static auto handshakeACK = ControlPacket::create(ControlPacket::HandshakeACK, sizeof(SequenceNumber));
+    handshakeACK->seek(0);
+    handshakeACK->writePrimitive(initialSequenceNumber);
     _parentSocket->writeBasePacket(*handshakeACK, _destination);
     
     // indicate that handshake has been received
@@ -749,8 +754,11 @@ void Connection::processHandshake(std::unique_ptr<ControlPacket> controlPacket)
 void Connection::processHandshakeACK(std::unique_ptr<ControlPacket> controlPacket) {
     // if we've decided to clean up the send queue then this handshake ACK should be ignored, it's useless
     if (_sendQueue) {
+        SequenceNumber initialSequenceNumber;
+        controlPacket->readPrimitive(&initialSequenceNumber);
+
         // hand off this handshake ACK to the send queue so it knows it can start sending
-        getSendQueue().handshakeACK();
+        getSendQueue().handshakeACK(initialSequenceNumber);
         
         // indicate that handshake ACK was received
         _hasReceivedHandshakeACK = true;
diff --git a/libraries/networking/src/udt/SendQueue.cpp b/libraries/networking/src/udt/SendQueue.cpp
index 77b0c53da7..5c6db5adf3 100644
--- a/libraries/networking/src/udt/SendQueue.cpp
+++ b/libraries/networking/src/udt/SendQueue.cpp
@@ -202,7 +202,11 @@ void SendQueue::sendHandshake() {
     std::unique_lock<std::mutex> handshakeLock { _handshakeMutex };
     if (!_hasReceivedHandshakeACK) {
         // we haven't received a handshake ACK from the client, send another now
-        static const auto handshakePacket = ControlPacket::create(ControlPacket::Handshake, 0);
+        static const auto handshakePacket = ControlPacket::create(ControlPacket::Handshake, sizeof(SequenceNumber));
+
+        handshakePacket->seek(0);
+
+        handshakePacket->writePrimitive(_initialSequenceNumber);
         _socket->writeBasePacket(*handshakePacket, _destination);
         
         // we wait for the ACK or the re-send interval to expire
@@ -211,14 +215,16 @@ void SendQueue::sendHandshake() {
     }
 }
 
-void SendQueue::handshakeACK() {
-    {
-        std::lock_guard<std::mutex> locker { _handshakeMutex };
-        _hasReceivedHandshakeACK = true;
+void SendQueue::handshakeACK(SequenceNumber initialSequenceNumber) {
+    if (initialSequenceNumber == _initialSequenceNumber) {
+        {
+            std::lock_guard<std::mutex> locker { _handshakeMutex };
+            _hasReceivedHandshakeACK = true;
+        }
+
+        // Notify on the handshake ACK condition
+        _handshakeACKCondition.notify_one();
     }
-    
-    // Notify on the handshake ACK condition
-    _handshakeACKCondition.notify_one();
 }
 
 SequenceNumber SendQueue::getNextSequenceNumber() {
diff --git a/libraries/networking/src/udt/SendQueue.h b/libraries/networking/src/udt/SendQueue.h
index 29ad7c6d73..0390f2ff1f 100644
--- a/libraries/networking/src/udt/SendQueue.h
+++ b/libraries/networking/src/udt/SendQueue.h
@@ -71,7 +71,7 @@ public slots:
     void ack(SequenceNumber ack);
     void nak(SequenceNumber start, SequenceNumber end);
     void overrideNAKListFromPacket(ControlPacket& packet);
-    void handshakeACK();
+    void handshakeACK(SequenceNumber initialSequenceNumber);
 
 signals:
     void packetSent(int dataSize, int payloadSize);