repairs for domain-server PacketList sending

domain-server/src/DomainServer.cpp

@@ -1007,6 +1007,9 @@ void DomainServer::sendDomainListToNode(const SharedNodePointer& node, const Hif
             });
         }
     }
+    
+    // send an empty list to the node, in case there were no other nodes
+    domainListPackets.closeCurrentPacket(true);
 
     // write the PacketList to this node
     limitedNodeList->sendPacketList(domainListPackets, *node);

libraries/networking/src/LimitedNodeList.cpp

@@ -263,15 +263,20 @@ qint64 LimitedNodeList::sendPacket(std::unique_ptr<NLPacket> packet, const HifiS
 }
 
 qint64 LimitedNodeList::sendPacketList(NLPacketList& packetList, const Node& destinationNode) {
-    if (!destinationNode.getActiveSocket()) {
+    const HifiSockAddr* activeSocket = destinationNode.getActiveSocket();
+    if (!activeSocket) {
         // we don't have a socket to send to, return 0
         return 0;
     }
-    return sendPacketList(packetList, *destinationNode.getActiveSocket());
+    return sendPacketList(packetList, *activeSocket);
 }
 
 qint64 LimitedNodeList::sendPacketList(NLPacketList& packetList, const HifiSockAddr& sockAddr) {
-    qint64 bytesSent{ 0 };
+    qint64 bytesSent { 0 };
+    
+    // close the last packet in the list
+    packetList.closeCurrentPacket();
+    
     while (!packetList._packets.empty()) {
         bytesSent += sendPacket(std::move(packetList.takeFront<NLPacket>()), sockAddr);
     }

libraries/networking/src/udt/PacketList.cpp

@@ -120,7 +120,13 @@ qint64 PacketList::writeData(const char* data, qint64 maxSize) {
     }
 }
 
-void PacketList::closeCurrentPacket() {
-    // move the current packet to our list of packets
-    _packets.push_back(std::move(_currentPacket));
+void PacketList::closeCurrentPacket(bool shouldSendEmpty) {
+    if (shouldSendEmpty && !_currentPacket) {
+        _currentPacket = createPacketWithExtendedHeader();
+    }
+    
+    if (_currentPacket) {
+        // move the current packet to our list of packets
+        _packets.push_back(std::move(_currentPacket));
+    }
 }

libraries/networking/src/udt/PacketList.h

@@ -31,7 +31,7 @@ public:
     PacketType::Value getType() const { return _packetType; }
     int getNumPackets() const { return _packets.size() + (_currentPacket ? 1 : 0); }
     
-    void closeCurrentPacket();
+    void closeCurrentPacket(bool shouldSendEmpty = false);
     
     void setExtendedHeader(const QByteArray& extendedHeader) { _extendedHeader = extendedHeader; }