diff -r d0fba0d7ad03 -r 0b0bc8045d28 sources/network/packetqueue.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sources/network/packetqueue.cpp	Wed Jan 27 12:34:56 2021 +0200
@@ -0,0 +1,154 @@
+/*
+	Copyright 2016 Teemu Piippo
+	All rights reserved.
+
+	Redistribution and use in source and binary forms, with or without
+	modification, are permitted provided that the following conditions
+	are met:
+
+	1. Redistributions of source code must retain the above copyright
+	   notice, this list of conditions and the following disclaimer.
+	2. Redistributions in binary form must reproduce the above copyright
+	   notice, this list of conditions and the following disclaimer in the
+	   documentation and/or other materials provided with the distribution.
+	3. Neither the name of the copyright holder nor the names of its
+	   contributors may be used to endorse or promote products derived from
+	   this software without specific prior written permission.
+
+	THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+	"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+	TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+	PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER
+	OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+	EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+	PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+	PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+	LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+	NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+	SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#include <algorithm>
+#include "packetqueue.h"
+BEGIN_ZFC_NAMESPACE
+
+/*!
+ * \brief Constructs an empty packet queue.
+ */
+PacketQueue::PacketQueue() :
+    m_currentSequenceNumber(0) {}
+
+/*!
+ * \brief Inserts the packet into the queue, unless the packet is the next packet to be processed.
+ * \param sequenceNumber Sequence number of the packet.
+ * \param data Payload of the packet.
+ * \return True, if the packet was stored, false if the packet should be processed immediately.
+ */
+bool PacketQueue::addPacket(unsigned int sequenceNumber, const ByteArray& data)
+{
+	// Check whether this packet is the one we're supposed to process next.
+	if (sequenceNumber != m_currentSequenceNumber)
+	{
+		// It is not, therefore store it for later.
+		m_queue[sequenceNumber] = data;
+		return true;
+	}
+	else
+	{
+		// It is, therefore the caller processes it, and we can advance to the next packet right away.
+		m_currentSequenceNumber = getNextSequenceNumber();
+		return false;
+	}
+}
+
+/*!
+ * \returns whether there are packets in queue that cannot be processed due to missing in-between packets. If true, the
+ * \returns caller should initiate packet recovery protocol.
+ */
+bool PacketQueue::isStuck() const
+{
+	return m_queue.size() > 0  and  m_queue.find(m_currentSequenceNumber) == m_queue.end();
+}
+
+/*!
+ * \returns whether or not there are packets awaiting processing.
+ */
+bool PacketQueue::hasPacketsToPop() const
+{
+	return m_queue.size() > 0  and  m_queue.find(m_currentSequenceNumber) != m_queue.end();
+}
+
+/*!
+ * \brief Retrieves the next packet to be processed, and removes it from the queue.
+ * \param packet Reference to a byte array to store the packet payload into.
+ * \returns whether the next packet was successfully popped from the queue, or not.
+ */
+bool PacketQueue::popNextPacket(ByteArray& packet)
+{
+	// Find the packet matching our current sequence number.
+	auto iterator = m_queue.find(m_currentSequenceNumber);
+
+	if (iterator != m_queue.end())
+	{
+		// We found the packet we were looking for. Pass it to the caller.
+		packet = iterator->second;
+		// Remove the packet from the queue.
+		m_queue.erase(iterator);
+		// We can now advance to the next packet.
+		m_currentSequenceNumber = getNextSequenceNumber();
+		return true;
+	}
+	else
+	{
+		// We did not find the next packet.
+		return false;
+	}
+}
+
+/*!
+ * \returns the sequence number for the next packet.
+ */
+int PacketQueue::getNextSequenceNumber() const
+{
+	return (m_currentSequenceNumber + 1) % 1024;
+}
+
+/*!
+ * \returns a list of packets that have to be requested from the server.
+ */
+std::set<int> PacketQueue::getLostPackets() const
+{
+	std::set<int> packetsNeeded;
+	std::set<int> packetsInQueue;
+
+	// Build the set of packet numbers we currently have.
+	for (auto pair : m_queue)
+		packetsInQueue.insert(pair.first);
+
+	// Build the set of packets we wish to process. To do this we need the smallest and largest numbers in
+	// packetsInQueue.
+	Range<int> packetRange(min(packetsInQueue), max(packetsInQueue));
+
+	for (int i : packetRange)
+		packetsNeeded.insert(i);
+
+	// The set of lost packets is now the set of packets we want, minus the packets we have.
+	std::set<int> packetsLost;
+	std::set_difference(packetsNeeded.begin(), packetsNeeded.end(),
+	                    packetsInQueue.begin(), packetsInQueue.end(),
+	                    std::inserter(packetsLost, packetsLost.begin()));
+	return packetsLost;
+}
+
+std::set<unsigned int> PacketQueue::getWaitingPackets() const
+{
+	std::set<unsigned int> packetsInQueue;
+
+	// Build the set of packet numbers we currently have.
+	for (auto pair : m_queue)
+		packetsInQueue.insert(pair.first);
+
+	return packetsInQueue;
+}
+
+END_ZFC_NAMESPACE