/*
 * Copyright (c) 2013 Universita' di Firenze, Italy
 *
 * SPDX-License-Identifier: GPL-2.0-only
 *
 * Author: Tommaso Pecorella <tommaso.pecorella@unifi.it>
 *         Michele Muccio <michelemuccio@virgilio.it>
 */

#include "sixlowpan-net-device.h"

#include "sixlowpan-header.h"

#include "ns3/boolean.h"
#include "ns3/channel.h"
#include "ns3/ipv6-extension-header.h"
#include "ns3/ipv6-l3-protocol.h"
#include "ns3/log.h"
#include "ns3/mac16-address.h"
#include "ns3/mac48-address.h"
#include "ns3/mac64-address.h"
#include "ns3/node.h"
#include "ns3/packet.h"
#include "ns3/pointer.h"
#include "ns3/simulator.h"
#include "ns3/string.h"
#include "ns3/udp-header.h"
#include "ns3/udp-l4-protocol.h"
#include "ns3/uinteger.h"

#include <algorithm>

NS_LOG_COMPONENT_DEFINE("SixLowPanNetDevice");

namespace ns3
{

NS_OBJECT_ENSURE_REGISTERED(SixLowPanNetDevice);

TypeId
SixLowPanNetDevice::GetTypeId()
{
    static TypeId tid =
        TypeId("ns3::SixLowPanNetDevice")
            .SetParent<NetDevice>()
            .SetGroupName("SixLowPan")
            .AddConstructor<SixLowPanNetDevice>()
            .AddAttribute("Rfc6282",
                          "Use RFC6282 (IPHC) if true, RFC4944 (HC1) otherwise.",
                          BooleanValue(true),
                          MakeBooleanAccessor(&SixLowPanNetDevice::m_useIphc),
                          MakeBooleanChecker())
            .AddAttribute("OmitUdpChecksum",
                          "Omit the UDP checksum in IPHC compression.",
                          BooleanValue(true),
                          MakeBooleanAccessor(&SixLowPanNetDevice::m_omitUdpChecksum),
                          MakeBooleanChecker())
            .AddAttribute(
                "FragmentReassemblyListSize",
                "The maximum size of the reassembly buffer (in packets). Zero meaning infinite.",
                UintegerValue(0),
                MakeUintegerAccessor(&SixLowPanNetDevice::m_fragmentReassemblyListSize),
                MakeUintegerChecker<uint16_t>())
            .AddAttribute(
                "FragmentExpirationTimeout",
                "When this timeout expires, the fragments will be cleared from the buffer.",
                TimeValue(Seconds(60)),
                MakeTimeAccessor(&SixLowPanNetDevice::m_fragmentExpirationTimeout),
                MakeTimeChecker())
            .AddAttribute("CompressionThreshold",
                          "The minimum MAC layer payload size.",
                          UintegerValue(0x0),
                          MakeUintegerAccessor(&SixLowPanNetDevice::m_compressionThreshold),
                          MakeUintegerChecker<uint32_t>())
            .AddAttribute("UseMeshUnder",
                          "Use a mesh-under routing protocol.",
                          BooleanValue(false),
                          MakeBooleanAccessor(&SixLowPanNetDevice::m_meshUnder),
                          MakeBooleanChecker())
            .AddAttribute("MeshUnderRadius",
                          "Hops Left to use in mesh-under.",
                          UintegerValue(10),
                          MakeUintegerAccessor(&SixLowPanNetDevice::m_meshUnderHopsLeft),
                          MakeUintegerChecker<uint8_t>())
            .AddAttribute("MeshCacheLength",
                          "Length of the cache for each source.",
                          UintegerValue(10),
                          MakeUintegerAccessor(&SixLowPanNetDevice::m_meshCacheLength),
                          MakeUintegerChecker<uint16_t>())
            .AddAttribute("MeshUnderJitter",
                          "The jitter in ms a node uses to forward mesh-under packets - used to "
                          "prevent collisions",
                          StringValue("ns3::UniformRandomVariable[Min=0.0|Max=10.0]"),
                          MakePointerAccessor(&SixLowPanNetDevice::m_meshUnderJitter),
                          MakePointerChecker<RandomVariableStream>())
            .AddTraceSource("Tx",
                            "Send - packet (including 6LoWPAN header), "
                            "SixLoWPanNetDevice Ptr, interface index.",
                            MakeTraceSourceAccessor(&SixLowPanNetDevice::m_txTrace),
                            "ns3::SixLowPanNetDevice::RxTxTracedCallback")
            .AddTraceSource("Rx",
                            "Receive - packet (including 6LoWPAN header), "
                            "SixLoWPanNetDevice Ptr, interface index.",
                            MakeTraceSourceAccessor(&SixLowPanNetDevice::m_rxTrace),
                            "ns3::SixLowPanNetDevice::RxTxTracedCallback")
            .AddTraceSource("Drop",
                            "Drop - DropReason, packet (including 6LoWPAN header), "
                            "SixLoWPanNetDevice Ptr, interface index.",
                            MakeTraceSourceAccessor(&SixLowPanNetDevice::m_dropTrace),
                            "ns3::SixLowPanNetDevice::DropTracedCallback");
    return tid;
}

SixLowPanNetDevice::SixLowPanNetDevice()
    : m_node(nullptr),
      m_netDevice(nullptr),
      m_ifIndex(0)
{
    NS_LOG_FUNCTION(this);
    m_netDevice = nullptr;
    m_rng = CreateObject<UniformRandomVariable>();
    m_bc0Serial = 0;
}

Ptr<NetDevice>
SixLowPanNetDevice::GetNetDevice() const
{
    NS_LOG_FUNCTION(this);
    return m_netDevice;
}

void
SixLowPanNetDevice::SetNetDevice(Ptr<NetDevice> device)
{
    NS_LOG_FUNCTION(this << device);
    m_netDevice = device;

    NS_LOG_DEBUG("RegisterProtocolHandler for " << device->GetInstanceTypeId().GetName());

    uint16_t protocolType = PROT_NUMBER;
    if (device->GetInstanceTypeId().GetName().find("LrWpanNetDevice") != std::string::npos)
    {
        // LrWpanNetDevice does not have a protocol number in the frame.
        // Hence, we must register for any protocol, and assume that any
        // packet is 6LoWPAN.
        protocolType = 0;
    }
    m_node->RegisterProtocolHandler(MakeCallback(&SixLowPanNetDevice::ReceiveFromDevice, this),
                                    protocolType,
                                    device,
                                    false);
}

int64_t
SixLowPanNetDevice::AssignStreams(int64_t stream)
{
    NS_LOG_FUNCTION(this << stream);
    m_rng->SetStream(stream);
    m_meshUnderJitter->SetStream(stream + 1);
    return 2;
}

void
SixLowPanNetDevice::DoDispose()
{
    NS_LOG_FUNCTION(this);

    m_netDevice = nullptr;
    m_node = nullptr;

    m_timeoutEventList.clear();
    if (m_timeoutEvent.IsPending())
    {
        m_timeoutEvent.Cancel();
    }

    for (auto iter = m_fragments.begin(); iter != m_fragments.end(); iter++)
    {
        iter->second = nullptr;
    }
    m_fragments.clear();

    NetDevice::DoDispose();
}

void
SixLowPanNetDevice::ReceiveFromDevice(Ptr<NetDevice> incomingPort,
                                      Ptr<const Packet> packet,
                                      uint16_t protocol,
                                      const Address& src,
                                      const Address& dst,
                                      PacketType packetType)
{
    NS_LOG_FUNCTION(this << incomingPort << packet << protocol << src << dst);

    uint8_t dispatchRawVal = 0;
    SixLowPanDispatch::Dispatch_e dispatchVal;
    Ptr<Packet> copyPkt = packet->Copy();

    m_rxTrace(copyPkt, this, GetIfIndex());

    copyPkt->CopyData(&dispatchRawVal, sizeof(dispatchRawVal));
    dispatchVal = SixLowPanDispatch::GetDispatchType(dispatchRawVal);
    bool isPktDecompressed = false;
    bool fragmented = false;

    NS_LOG_DEBUG("Packet received: " << *copyPkt);
    NS_LOG_DEBUG("Packet length: " << copyPkt->GetSize());
    NS_LOG_DEBUG("Dispatches: " << int(dispatchRawVal) << " - " << int(dispatchVal));

    SixLowPanMesh meshHdr;
    SixLowPanBc0 bc0Hdr;
    bool hasMesh = false;
    bool hasBc0 = false;

    if (dispatchVal == SixLowPanDispatch::LOWPAN_MESH)
    {
        hasMesh = true;
        copyPkt->RemoveHeader(meshHdr);
        copyPkt->CopyData(&dispatchRawVal, sizeof(dispatchRawVal));
        dispatchVal = SixLowPanDispatch::GetDispatchType(dispatchRawVal);
    }
    if (dispatchVal == SixLowPanDispatch::LOWPAN_BC0)
    {
        hasBc0 = true;
        copyPkt->RemoveHeader(bc0Hdr);
        copyPkt->CopyData(&dispatchRawVal, sizeof(dispatchRawVal));
        dispatchVal = SixLowPanDispatch::GetDispatchType(dispatchRawVal);
    }

    if (hasMesh)
    {
        if (!hasBc0)
        {
            NS_LOG_LOGIC("Dropped packet - we only support mesh if it is paired with a BC0");
            m_dropTrace(DROP_UNKNOWN_EXTENSION, copyPkt, this, GetIfIndex());
            return;
        }

        if (find(m_seenPkts[meshHdr.GetOriginator()].begin(),
                 m_seenPkts[meshHdr.GetOriginator()].end(),
                 bc0Hdr.GetSequenceNumber()) != m_seenPkts[meshHdr.GetOriginator()].end())
        {
            NS_LOG_LOGIC("We have already seen this, no further processing.");
            return;
        }

        m_seenPkts[meshHdr.GetOriginator()].push_back(bc0Hdr.GetSequenceNumber());
        if (m_seenPkts[meshHdr.GetOriginator()].size() > m_meshCacheLength)
        {
            m_seenPkts[meshHdr.GetOriginator()].pop_front();
        }

        NS_ABORT_MSG_IF(!Mac16Address::IsMatchingType(meshHdr.GetFinalDst()),
                        "SixLowPan mesh-under flooding can not currently handle extended address "
                        "final destinations: "
                            << meshHdr.GetFinalDst());
        NS_ABORT_MSG_IF(!Mac48Address::IsMatchingType(m_netDevice->GetAddress()),
                        "SixLowPan mesh-under flooding can not currently handle devices using "
                        "extended addresses: "
                            << m_netDevice->GetAddress());

        Mac16Address finalDst = Mac16Address::ConvertFrom(meshHdr.GetFinalDst());

        // See if the packet is for others than me. In case forward it.
        if (meshHdr.GetFinalDst() != Get16MacFrom48Mac(m_netDevice->GetAddress()) ||
            finalDst.IsBroadcast() || finalDst.IsMulticast())
        {
            uint8_t hopsLeft = meshHdr.GetHopsLeft();

            if (hopsLeft == 0)
            {
                NS_LOG_LOGIC("Not forwarding packet -- hop limit reached");
            }
            else if (meshHdr.GetOriginator() == Get16MacFrom48Mac(m_netDevice->GetAddress()))
            {
                NS_LOG_LOGIC("Not forwarding packet -- I am the originator");
            }
            else
            {
                meshHdr.SetHopsLeft(hopsLeft - 1);
                Ptr<Packet> sendPkt = copyPkt->Copy();
                sendPkt->AddHeader(bc0Hdr);
                sendPkt->AddHeader(meshHdr);
                Simulator::Schedule(MilliSeconds(m_meshUnderJitter->GetValue()),
                                    &NetDevice::Send,
                                    m_netDevice,
                                    sendPkt,
                                    m_netDevice->GetBroadcast(),
                                    protocol);
            }

            if (!finalDst.IsBroadcast() && !finalDst.IsMulticast())
            {
                return;
            }
        }
    }

    Address realDst = dst;
    Address realSrc = src;
    if (hasMesh)
    {
        realSrc = meshHdr.GetOriginator();
        realDst = meshHdr.GetFinalDst();
    }

    if (dispatchVal == SixLowPanDispatch::LOWPAN_FRAG1)
    {
        isPktDecompressed = ProcessFragment(copyPkt, realSrc, realDst, true);
        fragmented = true;
    }
    else if (dispatchVal == SixLowPanDispatch::LOWPAN_FRAGN)
    {
        isPktDecompressed = ProcessFragment(copyPkt, realSrc, realDst, false);
        fragmented = true;
    }
    if (fragmented)
    {
        if (!isPktDecompressed)
        {
            return;
        }
        else
        {
            copyPkt->CopyData(&dispatchRawVal, sizeof(dispatchRawVal));
            dispatchVal = SixLowPanDispatch::GetDispatchType(dispatchRawVal);
        }
    }

    switch (dispatchVal)
    {
    case SixLowPanDispatch::LOWPAN_IPv6:
        NS_LOG_DEBUG("Packet without compression. Length: " << copyPkt->GetSize());
        {
            SixLowPanIpv6 uncompressedHdr;
            copyPkt->RemoveHeader(uncompressedHdr);
            isPktDecompressed = true;
        }
        break;
    case SixLowPanDispatch::LOWPAN_HC1:
        if (m_useIphc)
        {
            m_dropTrace(DROP_DISALLOWED_COMPRESSION, copyPkt, this, GetIfIndex());
            return;
        }
        DecompressLowPanHc1(copyPkt, realSrc, realDst);
        isPktDecompressed = true;
        break;
    case SixLowPanDispatch::LOWPAN_IPHC:
        if (!m_useIphc)
        {
            m_dropTrace(DROP_DISALLOWED_COMPRESSION, copyPkt, this, GetIfIndex());
            return;
        }
        if (DecompressLowPanIphc(copyPkt, realSrc, realDst))
        {
            m_dropTrace(DROP_SATETFUL_DECOMPRESSION_PROBLEM, copyPkt, this, GetIfIndex());
        }
        else
        {
            isPktDecompressed = true;
        }
        break;
    default:
        NS_LOG_DEBUG("Unsupported 6LoWPAN encoding: dropping.");
        m_dropTrace(DROP_UNKNOWN_EXTENSION, copyPkt, this, GetIfIndex());
        break;
    }

    if (!isPktDecompressed)
    {
        return;
    }

    NS_LOG_DEBUG("Packet decompressed length: " << copyPkt->GetSize());
    NS_LOG_DEBUG("Packet decompressed received: " << *copyPkt);

    if (!m_promiscRxCallback.IsNull())
    {
        m_promiscRxCallback(this,
                            copyPkt,
                            Ipv6L3Protocol::PROT_NUMBER,
                            realSrc,
                            realDst,
                            packetType);
    }

    m_rxCallback(this, copyPkt, Ipv6L3Protocol::PROT_NUMBER, realSrc);
}

void
SixLowPanNetDevice::SetIfIndex(const uint32_t index)
{
    NS_LOG_FUNCTION(this << index);
    m_ifIndex = index;
}

uint32_t
SixLowPanNetDevice::GetIfIndex() const
{
    NS_LOG_FUNCTION(this);
    return m_ifIndex;
}

Ptr<Channel>
SixLowPanNetDevice::GetChannel() const
{
    NS_LOG_FUNCTION(this);
    NS_ASSERT_MSG(m_netDevice, "Sixlowpan: can't find any lower-layer protocol " << m_netDevice);

    return m_netDevice->GetChannel();
}

void
SixLowPanNetDevice::SetAddress(Address address)
{
    NS_LOG_FUNCTION(this << address);
    NS_ASSERT_MSG(m_netDevice, "Sixlowpan: can't find any lower-layer protocol " << m_netDevice);

    m_netDevice->SetAddress(address);
}

Address
SixLowPanNetDevice::GetAddress() const
{
    NS_LOG_FUNCTION(this);
    NS_ASSERT_MSG(m_netDevice, "Sixlowpan: can't find any lower-layer protocol " << m_netDevice);

    return m_netDevice->GetAddress();
}

bool
SixLowPanNetDevice::SetMtu(const uint16_t mtu)
{
    NS_LOG_FUNCTION(this << mtu);
    NS_ASSERT_MSG(m_netDevice, "Sixlowpan: can't find any lower-layer protocol " << m_netDevice);

    return m_netDevice->SetMtu(mtu);
}

uint16_t
SixLowPanNetDevice::GetMtu() const
{
    NS_LOG_FUNCTION(this);

    uint16_t mtu = m_netDevice->GetMtu();

    // RFC 4944, section 4.
    if (mtu < 1280)
    {
        mtu = 1280;
    }
    return mtu;
}

bool
SixLowPanNetDevice::IsLinkUp() const
{
    NS_LOG_FUNCTION(this);
    NS_ASSERT_MSG(m_netDevice, "Sixlowpan: can't find any lower-layer protocol " << m_netDevice);

    return m_netDevice->IsLinkUp();
}

void
SixLowPanNetDevice::AddLinkChangeCallback(Callback<void> callback)
{
    NS_LOG_FUNCTION(this);
    NS_ASSERT_MSG(m_netDevice, "Sixlowpan: can't find any lower-layer protocol " << m_netDevice);

    return m_netDevice->AddLinkChangeCallback(callback);
}

bool
SixLowPanNetDevice::IsBroadcast() const
{
    NS_LOG_FUNCTION(this);
    NS_ASSERT_MSG(m_netDevice, "Sixlowpan: can't find any lower-layer protocol " << m_netDevice);

    return m_netDevice->IsBroadcast();
}

Address
SixLowPanNetDevice::GetBroadcast() const
{
    NS_LOG_FUNCTION(this);
    NS_ASSERT_MSG(m_netDevice, "Sixlowpan: can't find any lower-layer protocol " << m_netDevice);

    return m_netDevice->GetBroadcast();
}

bool
SixLowPanNetDevice::IsMulticast() const
{
    NS_LOG_FUNCTION(this);
    NS_ASSERT_MSG(m_netDevice, "Sixlowpan: can't find any lower-layer protocol " << m_netDevice);

    return m_netDevice->IsMulticast();
}

Address
SixLowPanNetDevice::GetMulticast(Ipv4Address multicastGroup) const
{
    NS_LOG_FUNCTION(this << multicastGroup);
    NS_ASSERT_MSG(m_netDevice, "Sixlowpan: can't find any lower-layer protocol " << m_netDevice);

    return m_netDevice->GetMulticast(multicastGroup);
}

Address
SixLowPanNetDevice::GetMulticast(Ipv6Address addr) const
{
    NS_LOG_FUNCTION(this << addr);
    NS_ASSERT_MSG(m_netDevice, "Sixlowpan: can't find any lower-layer protocol " << m_netDevice);

    return m_netDevice->GetMulticast(addr);
}

bool
SixLowPanNetDevice::IsPointToPoint() const
{
    NS_LOG_FUNCTION(this);
    NS_ASSERT_MSG(m_netDevice, "Sixlowpan: can't find any lower-layer protocol " << m_netDevice);

    return m_netDevice->IsPointToPoint();
}

bool
SixLowPanNetDevice::IsBridge() const
{
    NS_LOG_FUNCTION(this);
    NS_ASSERT_MSG(m_netDevice, "Sixlowpan: can't find any lower-layer protocol " << m_netDevice);

    return m_netDevice->IsBridge();
}

bool
SixLowPanNetDevice::Send(Ptr<Packet> packet, const Address& dest, uint16_t protocolNumber)
{
    NS_LOG_FUNCTION(this << *packet << dest << protocolNumber);
    bool ret = false;
    Address src;

    ret = DoSend(packet, src, dest, protocolNumber, false);
    return ret;
}

bool
SixLowPanNetDevice::SendFrom(Ptr<Packet> packet,
                             const Address& src,
                             const Address& dest,
                             uint16_t protocolNumber)
{
    NS_LOG_FUNCTION(this << *packet << src << dest << protocolNumber);
    bool ret = false;

    ret = DoSend(packet, src, dest, protocolNumber, true);
    return ret;
}

bool
SixLowPanNetDevice::DoSend(Ptr<Packet> packet,
                           const Address& src,
                           const Address& dest,
                           uint16_t protocolNumber,
                           bool doSendFrom)
{
    NS_LOG_FUNCTION(this << *packet << src << dest << protocolNumber << doSendFrom);
    NS_ASSERT_MSG(m_netDevice, "Sixlowpan: can't find any lower-layer protocol " << m_netDevice);

    Ptr<Packet> origPacket = packet->Copy();
    uint32_t origHdrSize = 0;
    uint32_t origPacketSize = packet->GetSize();
    bool ret = false;

    Address destination = dest;

    bool useMesh = m_meshUnder;

    protocolNumber = PROT_NUMBER;

    if (m_useIphc)
    {
        NS_LOG_LOGIC("Compressing packet using IPHC");
        origHdrSize += CompressLowPanIphc(packet, m_netDevice->GetAddress(), destination);
    }
    else
    {
        NS_LOG_LOGIC("Compressing packet using HC1");
        origHdrSize += CompressLowPanHc1(packet, m_netDevice->GetAddress(), destination);
    }

    uint16_t pktSize = packet->GetSize();

    SixLowPanMesh meshHdr;
    SixLowPanBc0 bc0Hdr;
    uint32_t extraHdrSize = 0;

    if (useMesh)
    {
        Address source = src;
        if (!doSendFrom)
        {
            source = m_netDevice->GetAddress();
        }

        if (Mac48Address::IsMatchingType(source))
        {
            // We got a Mac48 pseudo-MAC. We need its original Mac16 here.
            source = Get16MacFrom48Mac(source);
        }
        if (Mac48Address::IsMatchingType(destination))
        {
            // We got a Mac48 pseudo-MAC. We need its original Mac16 here.
            destination = Get16MacFrom48Mac(destination);
        }

        meshHdr.SetOriginator(source);
        meshHdr.SetFinalDst(destination);
        meshHdr.SetHopsLeft(m_meshUnderHopsLeft);
        destination = m_netDevice->GetBroadcast();
        // We are storing sum of mesh and bc0 header sizes. We will need it if packet is fragmented.
        extraHdrSize = meshHdr.GetSerializedSize() + bc0Hdr.GetSerializedSize();
        pktSize += extraHdrSize;
    }

    if (pktSize < m_compressionThreshold)
    {
        NS_LOG_LOGIC("Compressed packet too short, using uncompressed one");
        packet = origPacket;
        SixLowPanIpv6 ipv6UncompressedHdr;
        packet->AddHeader(ipv6UncompressedHdr);
        pktSize = packet->GetSize();
        if (useMesh)
        {
            pktSize += meshHdr.GetSerializedSize() + bc0Hdr.GetSerializedSize();
        }
    }

    if (pktSize > m_netDevice->GetMtu())
    {
        NS_LOG_LOGIC("Fragmentation: Packet size " << packet->GetSize() << " - Mtu "
                                                   << m_netDevice->GetMtu());
        // fragment
        std::list<Ptr<Packet>> fragmentList;
        DoFragmentation(packet, origPacketSize, origHdrSize, extraHdrSize, fragmentList);
        bool success = true;
        for (auto it = fragmentList.begin(); it != fragmentList.end(); it++)
        {
            NS_LOG_DEBUG("SixLowPanNetDevice::Send (Fragment) " << **it);
            m_txTrace(*it, this, GetIfIndex());

            if (useMesh)
            {
                bc0Hdr.SetSequenceNumber(m_bc0Serial++);
                (*it)->AddHeader(bc0Hdr);
                (*it)->AddHeader(meshHdr);
            }
            if (doSendFrom)
            {
                success &= m_netDevice->SendFrom(*it, src, destination, protocolNumber);
            }
            else
            {
                success &= m_netDevice->Send(*it, destination, protocolNumber);
            }
        }
        ret = success;
    }
    else
    {
        m_txTrace(packet, this, GetIfIndex());

        if (useMesh)
        {
            bc0Hdr.SetSequenceNumber(m_bc0Serial++);
            packet->AddHeader(bc0Hdr);
            packet->AddHeader(meshHdr);
        }

        if (doSendFrom)
        {
            NS_LOG_DEBUG("SixLowPanNetDevice::SendFrom " << m_node->GetId() << " " << *packet);
            ret = m_netDevice->SendFrom(packet, src, destination, protocolNumber);
        }
        else
        {
            NS_LOG_DEBUG("SixLowPanNetDevice::Send " << m_node->GetId() << " " << *packet);
            ret = m_netDevice->Send(packet, destination, protocolNumber);
        }
    }

    return ret;
}

Ptr<Node>
SixLowPanNetDevice::GetNode() const
{
    NS_LOG_FUNCTION(this);
    return m_node;
}

void
SixLowPanNetDevice::SetNode(Ptr<Node> node)
{
    NS_LOG_FUNCTION(this << node);
    m_node = node;
}

bool
SixLowPanNetDevice::NeedsArp() const
{
    NS_LOG_FUNCTION(this);
    NS_ASSERT_MSG(m_netDevice, "Sixlowpan: can't find any lower-layer protocol " << m_netDevice);

    return m_netDevice->NeedsArp();
}

void
SixLowPanNetDevice::SetReceiveCallback(NetDevice::ReceiveCallback cb)
{
    NS_LOG_FUNCTION(this << &cb);
    m_rxCallback = cb;
}

void
SixLowPanNetDevice::SetPromiscReceiveCallback(NetDevice::PromiscReceiveCallback cb)
{
    NS_LOG_FUNCTION(this << &cb);
    m_promiscRxCallback = cb;
}

bool
SixLowPanNetDevice::SupportsSendFrom() const
{
    NS_LOG_FUNCTION(this);
    return true;
}

uint32_t
SixLowPanNetDevice::CompressLowPanHc1(Ptr<Packet> packet, const Address& src, const Address& dst)
{
    NS_LOG_FUNCTION(this << *packet << src << dst);

    Ipv6Header ipHeader;
    SixLowPanHc1 hc1Header;
    uint32_t size = 0;

    NS_LOG_DEBUG("Original packet: " << *packet << " Size " << packet->GetSize());

    if (packet->PeekHeader(ipHeader) != 0)
    {
        packet->RemoveHeader(ipHeader);
        size += ipHeader.GetSerializedSize();

        hc1Header.SetHopLimit(ipHeader.GetHopLimit());

        uint8_t bufOne[16];
        uint8_t bufTwo[16];
        Ipv6Address srcAddr = ipHeader.GetSource();
        srcAddr.GetBytes(bufOne);
        Ipv6Address mySrcAddr = Ipv6Address::MakeAutoconfiguredLinkLocalAddress(src);

        NS_LOG_LOGIC("Checking source compression: " << mySrcAddr << " - " << srcAddr);

        mySrcAddr.GetBytes(bufTwo);
        bool isSrcSrc = (memcmp(bufOne + 8, bufTwo + 8, 8) == 0);

        if (srcAddr.IsLinkLocal() && isSrcSrc)
        {
            hc1Header.SetSrcCompression(SixLowPanHc1::HC1_PCIC);
        }
        else if (srcAddr.IsLinkLocal())
        {
            hc1Header.SetSrcCompression(SixLowPanHc1::HC1_PCII);
            hc1Header.SetSrcInterface(bufOne + 8);
        }
        else if (isSrcSrc)
        {
            hc1Header.SetSrcCompression(SixLowPanHc1::HC1_PIIC);
            hc1Header.SetSrcPrefix(bufOne);
        }
        else
        {
            hc1Header.SetSrcCompression(SixLowPanHc1::HC1_PIII);
            hc1Header.SetSrcInterface(bufOne + 8);
            hc1Header.SetSrcPrefix(bufOne);
        }

        Ipv6Address dstAddr = ipHeader.GetDestination();
        dstAddr.GetBytes(bufOne);
        Ipv6Address myDstAddr = Ipv6Address::MakeAutoconfiguredLinkLocalAddress(dst);

        NS_LOG_LOGIC("Checking destination compression: " << myDstAddr << " - " << dstAddr);

        myDstAddr.GetBytes(bufTwo);
        bool isDstDst = (memcmp(bufOne + 8, bufTwo + 8, 8) == 0);

        if (dstAddr.IsLinkLocal() && isDstDst)
        {
            hc1Header.SetDstCompression(SixLowPanHc1::HC1_PCIC);
        }
        else if (dstAddr.IsLinkLocal())
        {
            hc1Header.SetDstCompression(SixLowPanHc1::HC1_PCII);
            hc1Header.SetDstInterface(bufOne + 8);
        }
        else if (isDstDst)
        {
            hc1Header.SetDstCompression(SixLowPanHc1::HC1_PIIC);
            hc1Header.SetDstPrefix(bufOne);
        }
        else
        {
            hc1Header.SetDstCompression(SixLowPanHc1::HC1_PIII);
            hc1Header.SetDstInterface(bufOne + 8);
            hc1Header.SetDstPrefix(bufOne);
        }

        if ((ipHeader.GetFlowLabel() == 0) && (ipHeader.GetTrafficClass() == 0))
        {
            hc1Header.SetTcflCompression(true);
        }
        else
        {
            hc1Header.SetTcflCompression(false);
            hc1Header.SetTrafficClass(ipHeader.GetTrafficClass());
            hc1Header.SetFlowLabel(ipHeader.GetFlowLabel());
        }

        uint8_t nextHeader = ipHeader.GetNextHeader();
        hc1Header.SetNextHeader(nextHeader);

        // \todo implement HC2 compression
        hc1Header.SetHc2HeaderPresent(false);

        NS_LOG_DEBUG("HC1 Compression - HC1 header size = " << hc1Header.GetSerializedSize());
        NS_LOG_DEBUG("HC1 Compression - packet size = " << packet->GetSize());

        packet->AddHeader(hc1Header);

        return size;
    }

    return 0;
}

void
SixLowPanNetDevice::DecompressLowPanHc1(Ptr<Packet> packet, const Address& src, const Address& dst)
{
    NS_LOG_FUNCTION(this << *packet << src << dst);

    Ipv6Header ipHeader;
    SixLowPanHc1 encoding;

    uint32_t ret [[maybe_unused]] = packet->RemoveHeader(encoding);
    NS_LOG_DEBUG("removed " << ret << " bytes - pkt is " << *packet);

    ipHeader.SetHopLimit(encoding.GetHopLimit());

    switch (encoding.GetSrcCompression())
    {
        const uint8_t* interface;
        const uint8_t* prefix;
        uint8_t address[16];

    case SixLowPanHc1::HC1_PIII:
        prefix = encoding.GetSrcPrefix();
        interface = encoding.GetSrcInterface();
        for (int j = 0; j < 8; j++)
        {
            address[j + 8] = interface[j];
            address[j] = prefix[j];
        }
        ipHeader.SetSource(Ipv6Address(address));
        break;
    case SixLowPanHc1::HC1_PIIC:
        prefix = encoding.GetSrcPrefix();
        for (int j = 0; j < 8; j++)
        {
            address[j + 8] = 0;
            address[j] = prefix[j];
        }
        ipHeader.SetSource(Ipv6Address::MakeAutoconfiguredAddress(src, Ipv6Address(address)));
        break;
    case SixLowPanHc1::HC1_PCII:
        interface = encoding.GetSrcInterface();
        address[0] = 0xfe;
        address[1] = 0x80;
        for (int j = 0; j < 8; j++)
        {
            address[j + 8] = interface[j];
        }
        ipHeader.SetSource(Ipv6Address(address));
        break;
    case SixLowPanHc1::HC1_PCIC:
        ipHeader.SetSource(Ipv6Address::MakeAutoconfiguredLinkLocalAddress(src));
        break;
    }

    switch (encoding.GetDstCompression())
    {
        const uint8_t* interface;
        const uint8_t* prefix;
        uint8_t address[16];

    case SixLowPanHc1::HC1_PIII:
        prefix = encoding.GetDstPrefix();
        interface = encoding.GetDstInterface();
        for (int j = 0; j < 8; j++)
        {
            address[j + 8] = interface[j];
            address[j] = prefix[j];
        }
        ipHeader.SetDestination(Ipv6Address(address));
        break;
    case SixLowPanHc1::HC1_PIIC:
        prefix = encoding.GetDstPrefix();
        for (int j = 0; j < 8; j++)
        {
            address[j + 8] = 0;
            address[j] = prefix[j];
        }
        ipHeader.SetDestination(Ipv6Address::MakeAutoconfiguredAddress(dst, Ipv6Address(address)));
        break;
    case SixLowPanHc1::HC1_PCII:
        interface = encoding.GetDstInterface();
        address[0] = 0xfe;
        address[1] = 0x80;
        for (int j = 0; j < 8; j++)
        {
            address[j + 8] = interface[j];
        }
        ipHeader.SetDestination(Ipv6Address(address));
        break;
    case SixLowPanHc1::HC1_PCIC:
        ipHeader.SetDestination(Ipv6Address::MakeAutoconfiguredLinkLocalAddress(dst));
        break;
    }

    if (!encoding.IsTcflCompression())
    {
        ipHeader.SetFlowLabel(encoding.GetFlowLabel());
        ipHeader.SetTrafficClass(encoding.GetTrafficClass());
    }
    else
    {
        ipHeader.SetFlowLabel(0);
        ipHeader.SetTrafficClass(0);
    }

    ipHeader.SetNextHeader(encoding.GetNextHeader());

    ipHeader.SetPayloadLength(packet->GetSize());

    NS_ASSERT_MSG(
        encoding.IsHc2HeaderPresent() == false,
        "6LoWPAN: error in decompressing HC1 encoding, unsupported L4 compressed header present.");

    packet->AddHeader(ipHeader);

    NS_LOG_DEBUG("Rebuilt packet:  " << *packet << " Size " << packet->GetSize());
}

uint32_t
SixLowPanNetDevice::CompressLowPanIphc(Ptr<Packet> packet, const Address& src, const Address& dst)
{
    NS_LOG_FUNCTION(this << *packet << src << dst);

    Ipv6Header ipHeader;
    SixLowPanIphc iphcHeader;
    uint32_t size = 0;

    NS_LOG_DEBUG("Original packet: " << *packet << " Size " << packet->GetSize() << " src: " << src
                                     << " dst: " << dst);

    if (packet->PeekHeader(ipHeader) != 0)
    {
        packet->RemoveHeader(ipHeader);
        size += ipHeader.GetSerializedSize();

        // Set the TF field
        if ((ipHeader.GetFlowLabel() == 0) && (ipHeader.GetTrafficClass() == 0))
        {
            iphcHeader.SetTf(SixLowPanIphc::TF_ELIDED);
        }
        else if ((ipHeader.GetFlowLabel() != 0) && (ipHeader.GetTrafficClass() != 0))
        {
            iphcHeader.SetTf(SixLowPanIphc::TF_FULL);
            iphcHeader.SetEcn((ipHeader.GetTrafficClass() & 0xC0) >> 6);
            iphcHeader.SetDscp(ipHeader.GetTrafficClass() & 0x3F);
            iphcHeader.SetFlowLabel(ipHeader.GetFlowLabel());
        }
        else if ((ipHeader.GetFlowLabel() == 0) && (ipHeader.GetTrafficClass() != 0))
        {
            iphcHeader.SetTf(SixLowPanIphc::TF_FL_ELIDED);
            iphcHeader.SetEcn((ipHeader.GetTrafficClass() & 0xC0) >> 6);
            iphcHeader.SetDscp(ipHeader.GetTrafficClass() & 0x3F);
        }
        else
        {
            iphcHeader.SetTf(SixLowPanIphc::TF_DSCP_ELIDED);
            iphcHeader.SetEcn((ipHeader.GetTrafficClass() & 0xC0) >> 6);
            iphcHeader.SetFlowLabel(ipHeader.GetFlowLabel());
        }

        // Set the NH field and NextHeader

        uint8_t nextHeader = ipHeader.GetNextHeader();
        if (CanCompressLowPanNhc(nextHeader))
        {
            if (nextHeader == Ipv6Header::IPV6_UDP)
            {
                iphcHeader.SetNh(true);
                size += CompressLowPanUdpNhc(packet, m_omitUdpChecksum);
            }
            else if (nextHeader == Ipv6Header::IPV6_IPV6)
            {
                iphcHeader.SetNh(true);
                size += CompressLowPanIphc(packet, src, dst);
            }
            else
            {
                uint32_t sizeNhc = CompressLowPanNhc(packet, nextHeader, src, dst);
                // the compression might fail due to Extension header size.
                if (sizeNhc)
                {
                    iphcHeader.SetNh(true);
                    size += sizeNhc;
                }
                else
                {
                    iphcHeader.SetNh(false);
                    iphcHeader.SetNextHeader(nextHeader);
                }
            }
        }
        else
        {
            iphcHeader.SetNh(false);
            iphcHeader.SetNextHeader(nextHeader);
        }

        // Set the HLIM field
        if (ipHeader.GetHopLimit() == 1)
        {
            iphcHeader.SetHlim(SixLowPanIphc::HLIM_COMPR_1);
        }
        else if (ipHeader.GetHopLimit() == 0x40)
        {
            iphcHeader.SetHlim(SixLowPanIphc::HLIM_COMPR_64);
        }
        else if (ipHeader.GetHopLimit() == 0xFF)
        {
            iphcHeader.SetHlim(SixLowPanIphc::HLIM_COMPR_255);
        }
        else
        {
            iphcHeader.SetHlim(SixLowPanIphc::HLIM_INLINE);
            // Set the HopLimit
            iphcHeader.SetHopLimit(ipHeader.GetHopLimit());
        }

        // Set the CID + SAC + DAC fields to their default value
        iphcHeader.SetCid(false);
        iphcHeader.SetSac(false);
        iphcHeader.SetDac(false);

        auto checker = Ipv6Address("fe80:0000:0000:0000:0000:00ff:fe00:1");
        uint8_t unicastAddrCheckerBuf[16];
        checker.GetBytes(unicastAddrCheckerBuf);
        uint8_t addressBuf[16];

        // This is just to limit the scope of some variables.
        {
            Ipv6Address srcAddr = ipHeader.GetSource();
            uint8_t srcContextId;

            // The "::" address is compressed as a fake stateful compression.
            if (srcAddr == Ipv6Address::GetAny())
            {
                // No context information is needed.
                iphcHeader.SetSam(SixLowPanIphc::HC_INLINE);
                iphcHeader.SetSac(true);
            }
            // Check if the address can be compressed with stateful compression
            else if (FindUnicastCompressionContext(srcAddr, srcContextId))
            {
                // We can do stateful compression.
                NS_LOG_LOGIC("Checking stateful source compression: " << srcAddr);

                iphcHeader.SetSac(true);
                if (srcContextId != 0)
                {
                    // the default context is zero, no need to explicit it if it's zero
                    iphcHeader.SetSrcContextId(srcContextId);
                    iphcHeader.SetCid(true);
                }

                // Note that a context might include parts of the EUI-64 (i.e., be as long as 128
                // bits).

                if (Ipv6Address::MakeAutoconfiguredAddress(
                        src,
                        m_contextTable[srcContextId].contextPrefix) == srcAddr)
                {
                    iphcHeader.SetSam(SixLowPanIphc::HC_COMPR_0);
                }
                else
                {
                    Ipv6Address cleanedAddr =
                        CleanPrefix(srcAddr, m_contextTable[srcContextId].contextPrefix);
                    uint8_t serializedCleanedAddress[16];
                    cleanedAddr.Serialize(serializedCleanedAddress);

                    if (serializedCleanedAddress[8] == 0x00 &&
                        serializedCleanedAddress[9] == 0x00 &&
                        serializedCleanedAddress[10] == 0x00 &&
                        serializedCleanedAddress[11] == 0xff &&
                        serializedCleanedAddress[12] == 0xfe &&
                        serializedCleanedAddress[13] == 0x00)
                    {
                        iphcHeader.SetSam(SixLowPanIphc::HC_COMPR_16);
                        iphcHeader.SetSrcInlinePart(serializedCleanedAddress + 14, 2);
                    }
                    else
                    {
                        iphcHeader.SetSam(SixLowPanIphc::HC_COMPR_64);
                        iphcHeader.SetSrcInlinePart(serializedCleanedAddress + 8, 8);
                    }
                }
            }
            else
            {
                // We must do stateless compression.
                NS_LOG_LOGIC("Checking stateless source compression: " << srcAddr);

                srcAddr.GetBytes(addressBuf);

                uint8_t serializedSrcAddress[16];
                srcAddr.Serialize(serializedSrcAddress);

                if (srcAddr == Ipv6Address::MakeAutoconfiguredLinkLocalAddress(src))
                {
                    iphcHeader.SetSam(SixLowPanIphc::HC_COMPR_0);
                }
                else if (memcmp(addressBuf, unicastAddrCheckerBuf, 14) == 0)
                {
                    iphcHeader.SetSrcInlinePart(serializedSrcAddress + 14, 2);
                    iphcHeader.SetSam(SixLowPanIphc::HC_COMPR_16);
                }
                else if (srcAddr.IsLinkLocal())
                {
                    iphcHeader.SetSrcInlinePart(serializedSrcAddress + 8, 8);
                    iphcHeader.SetSam(SixLowPanIphc::HC_COMPR_64);
                }
                else
                {
                    iphcHeader.SetSrcInlinePart(serializedSrcAddress, 16);
                    iphcHeader.SetSam(SixLowPanIphc::HC_INLINE);
                }
            }
        }

        // Set the M field
        if (ipHeader.GetDestination().IsMulticast())
        {
            iphcHeader.SetM(true);
        }
        else
        {
            iphcHeader.SetM(false);
        }

        // This is just to limit the scope of some variables.
        {
            Ipv6Address dstAddr = ipHeader.GetDestination();
            dstAddr.GetBytes(addressBuf);

            NS_LOG_LOGIC("Checking destination compression: " << dstAddr);

            uint8_t serializedDstAddress[16];
            dstAddr.Serialize(serializedDstAddress);

            if (!iphcHeader.GetM())
            {
                // Unicast address

                uint8_t dstContextId;
                if (FindUnicastCompressionContext(dstAddr, dstContextId))
                {
                    // We can do stateful compression.
                    NS_LOG_LOGIC("Checking stateful destination compression: " << dstAddr);

                    iphcHeader.SetDac(true);
                    if (dstContextId != 0)
                    {
                        // the default context is zero, no need to explicit it if it's zero
                        iphcHeader.SetDstContextId(dstContextId);
                        iphcHeader.SetCid(true);
                    }

                    // Note that a context might include parts of the EUI-64 (i.e., be as long as
                    // 128 bits).
                    if (Ipv6Address::MakeAutoconfiguredAddress(
                            dst,
                            m_contextTable[dstContextId].contextPrefix) == dstAddr)
                    {
                        iphcHeader.SetDam(SixLowPanIphc::HC_COMPR_0);
                    }
                    else
                    {
                        Ipv6Address cleanedAddr =
                            CleanPrefix(dstAddr, m_contextTable[dstContextId].contextPrefix);

                        uint8_t serializedCleanedAddress[16];
                        cleanedAddr.Serialize(serializedCleanedAddress);

                        if (serializedCleanedAddress[8] == 0x00 &&
                            serializedCleanedAddress[9] == 0x00 &&
                            serializedCleanedAddress[10] == 0x00 &&
                            serializedCleanedAddress[11] == 0xff &&
                            serializedCleanedAddress[12] == 0xfe &&
                            serializedCleanedAddress[13] == 0x00)
                        {
                            iphcHeader.SetDam(SixLowPanIphc::HC_COMPR_16);
                            iphcHeader.SetDstInlinePart(serializedCleanedAddress + 14, 2);
                        }
                        else
                        {
                            iphcHeader.SetDam(SixLowPanIphc::HC_COMPR_64);
                            iphcHeader.SetDstInlinePart(serializedCleanedAddress + 8, 8);
                        }
                    }
                }
                else
                {
                    NS_LOG_LOGIC("Checking stateless destination compression: " << dstAddr);

                    if (dstAddr == Ipv6Address::MakeAutoconfiguredLinkLocalAddress(dst))
                    {
                        iphcHeader.SetDam(SixLowPanIphc::HC_COMPR_0);
                    }
                    else if (memcmp(addressBuf, unicastAddrCheckerBuf, 14) == 0)
                    {
                        iphcHeader.SetDstInlinePart(serializedDstAddress + 14, 2);
                        iphcHeader.SetDam(SixLowPanIphc::HC_COMPR_16);
                    }
                    else if (dstAddr.IsLinkLocal())
                    {
                        iphcHeader.SetDstInlinePart(serializedDstAddress + 8, 8);
                        iphcHeader.SetDam(SixLowPanIphc::HC_COMPR_64);
                    }
                    else
                    {
                        iphcHeader.SetDstInlinePart(serializedDstAddress, 16);
                        iphcHeader.SetDam(SixLowPanIphc::HC_INLINE);
                    }
                }
            }
            else
            {
                // Multicast address

                uint8_t dstContextId;
                if (FindMulticastCompressionContext(dstAddr, dstContextId))
                {
                    // Stateful compression (only one possible case)

                    // ffXX:XXLL:PPPP:PPPP:PPPP:PPPP:XXXX:XXXX
                    uint8_t dstInlinePart[6] = {};
                    dstInlinePart[0] = serializedDstAddress[1];
                    dstInlinePart[1] = serializedDstAddress[2];
                    dstInlinePart[2] = serializedDstAddress[12];
                    dstInlinePart[3] = serializedDstAddress[13];
                    dstInlinePart[4] = serializedDstAddress[14];
                    dstInlinePart[5] = serializedDstAddress[15];

                    iphcHeader.SetDac(true);
                    if (dstContextId != 0)
                    {
                        // the default context is zero, no need to explicit it if it's zero
                        iphcHeader.SetDstContextId(dstContextId);
                        iphcHeader.SetCid(true);
                    }
                    iphcHeader.SetDstInlinePart(dstInlinePart, 6);
                    iphcHeader.SetDam(SixLowPanIphc::HC_INLINE);
                }
                else
                {
                    // Stateless compression

                    uint8_t multicastAddrCheckerBuf[16];
                    auto multicastCheckAddress = Ipv6Address("ff02::1");
                    multicastCheckAddress.GetBytes(multicastAddrCheckerBuf);

                    // The address takes the form ff02::00XX.
                    if (memcmp(addressBuf, multicastAddrCheckerBuf, 15) == 0)
                    {
                        iphcHeader.SetDstInlinePart(serializedDstAddress + 15, 1);
                        iphcHeader.SetDam(SixLowPanIphc::HC_COMPR_0);
                    }
                    // The address takes the form ffXX::00XX:XXXX.
                    //                            ffXX:0000:0000:0000:0000:0000:00XX:XXXX.
                    else if ((addressBuf[0] == multicastAddrCheckerBuf[0]) &&
                             (memcmp(addressBuf + 2, multicastAddrCheckerBuf + 2, 11) == 0))
                    {
                        uint8_t dstInlinePart[4] = {};
                        memcpy(dstInlinePart, serializedDstAddress + 1, 1);
                        memcpy(dstInlinePart + 1, serializedDstAddress + 13, 3);
                        iphcHeader.SetDstInlinePart(dstInlinePart, 4);
                        iphcHeader.SetDam(SixLowPanIphc::HC_COMPR_16);
                    }
                    // The address takes the form ffXX::00XX:XXXX:XXXX.
                    //                            ffXX:0000:0000:0000:0000:00XX:XXXX:XXXX.
                    else if ((addressBuf[0] == multicastAddrCheckerBuf[0]) &&
                             (memcmp(addressBuf + 2, multicastAddrCheckerBuf + 2, 9) == 0))
                    {
                        uint8_t dstInlinePart[6] = {};
                        memcpy(dstInlinePart, serializedDstAddress + 1, 1);
                        memcpy(dstInlinePart + 1, serializedDstAddress + 11, 5);
                        iphcHeader.SetDstInlinePart(dstInlinePart, 6);
                        iphcHeader.SetDam(SixLowPanIphc::HC_COMPR_64);
                    }
                    else
                    {
                        iphcHeader.SetDstInlinePart(serializedDstAddress, 16);
                        iphcHeader.SetDam(SixLowPanIphc::HC_INLINE);
                    }
                }
            }
        }

        NS_LOG_DEBUG("IPHC Compression - IPHC header size = " << iphcHeader.GetSerializedSize());
        NS_LOG_DEBUG("IPHC Compression - packet size = " << packet->GetSize());

        packet->AddHeader(iphcHeader);

        NS_LOG_DEBUG("Packet after IPHC compression: " << *packet);

        return size;
    }
    return 0;
}

bool
SixLowPanNetDevice::CanCompressLowPanNhc(uint8_t nextHeader)
{
    bool ret = false;

    switch (nextHeader)
    {
    case Ipv6Header::IPV6_UDP:
    case Ipv6Header::IPV6_EXT_HOP_BY_HOP:
    case Ipv6Header::IPV6_EXT_ROUTING:
    case Ipv6Header::IPV6_EXT_FRAGMENTATION:
    case Ipv6Header::IPV6_IPV6:
        ret = true;
        break;
    case Ipv6Header::IPV6_EXT_MOBILITY:
    default:
        ret = false;
    }
    return ret;
}

bool
SixLowPanNetDevice::DecompressLowPanIphc(Ptr<Packet> packet, const Address& src, const Address& dst)
{
    NS_LOG_FUNCTION(this << *packet << src << dst);

    Ipv6Header ipHeader;
    SixLowPanIphc encoding;

    uint32_t ret [[maybe_unused]] = packet->RemoveHeader(encoding);
    NS_LOG_DEBUG("removed " << ret << " bytes - pkt is " << *packet);

    // Hop Limit
    ipHeader.SetHopLimit(encoding.GetHopLimit());

    // Source address
    if (encoding.GetSac())
    {
        // Source address compression uses stateful, context-based compression.
        if (encoding.GetSam() == SixLowPanIphc::HC_INLINE)
        {
            ipHeader.SetSource(Ipv6Address::GetAny());
        }
        else
        {
            uint8_t contextId = encoding.GetSrcContextId();
            if (m_contextTable.find(contextId) == m_contextTable.end())
            {
                NS_LOG_LOGIC("Unknown Source compression context (" << +contextId
                                                                    << "), dropping packet");
                return true;
            }
            if (m_contextTable[contextId].validLifetime < Simulator::Now())
            {
                NS_LOG_LOGIC("Expired Source compression context (" << +contextId
                                                                    << "), dropping packet");
                return true;
            }

            uint8_t contextPrefix[16];
            m_contextTable[contextId].contextPrefix.GetBytes(contextPrefix);
            uint8_t contextLength = m_contextTable[contextId].contextPrefix.GetPrefixLength();

            uint8_t srcAddress[16] = {};
            if (encoding.GetSam() == SixLowPanIphc::HC_COMPR_64)
            {
                memcpy(srcAddress + 8, encoding.GetSrcInlinePart(), 8);
            }
            else if (encoding.GetSam() == SixLowPanIphc::HC_COMPR_16)
            {
                srcAddress[11] = 0xff;
                srcAddress[12] = 0xfe;
                memcpy(srcAddress + 14, encoding.GetSrcInlinePart(), 2);
            }
            else // SixLowPanIphc::HC_COMPR_0
            {
                Ipv6Address::MakeAutoconfiguredLinkLocalAddress(src).GetBytes(srcAddress);
            }

            uint8_t bytesToCopy = contextLength / 8;
            uint8_t bitsToCopy = contextLength % 8;

            // Do not combine the prefix - we want to override the bytes.
            for (uint8_t i = 0; i < bytesToCopy; i++)
            {
                srcAddress[i] = contextPrefix[i];
            }
            if (bitsToCopy)
            {
                uint8_t addressBitMask = (1 << (8 - bitsToCopy)) - 1;
                uint8_t prefixBitMask = ~addressBitMask;
                srcAddress[bytesToCopy] = (contextPrefix[bytesToCopy] & prefixBitMask) |
                                          (srcAddress[bytesToCopy] & addressBitMask);
            }
            ipHeader.SetSource(Ipv6Address::Deserialize(srcAddress));
        }
    }
    else
    {
        // Source address compression uses stateless compression.

        if (encoding.GetSam() == SixLowPanIphc::HC_INLINE)
        {
            uint8_t srcAddress[16] = {};
            memcpy(srcAddress, encoding.GetSrcInlinePart(), 16);
            ipHeader.SetSource(Ipv6Address::Deserialize(srcAddress));
        }
        else if (encoding.GetSam() == SixLowPanIphc::HC_COMPR_64)
        {
            uint8_t srcAddress[16] = {};
            memcpy(srcAddress + 8, encoding.GetSrcInlinePart(), 8);
            srcAddress[0] = 0xfe;
            srcAddress[1] = 0x80;
            ipHeader.SetSource(Ipv6Address::Deserialize(srcAddress));
        }
        else if (encoding.GetSam() == SixLowPanIphc::HC_COMPR_16)
        {
            uint8_t srcAddress[16] = {};
            memcpy(srcAddress + 14, encoding.GetSrcInlinePart(), 2);
            srcAddress[0] = 0xfe;
            srcAddress[1] = 0x80;
            srcAddress[11] = 0xff;
            srcAddress[12] = 0xfe;
            ipHeader.SetSource(Ipv6Address::Deserialize(srcAddress));
        }
        else // SixLowPanIphc::HC_COMPR_0
        {
            ipHeader.SetSource(Ipv6Address::MakeAutoconfiguredLinkLocalAddress(src));
        }
    }
    // Destination address
    if (encoding.GetDac())
    {
        // Destination address compression uses stateful, context-based compression.
        if ((encoding.GetDam() == SixLowPanIphc::HC_INLINE && !encoding.GetM()) ||
            (encoding.GetDam() == SixLowPanIphc::HC_COMPR_64 && encoding.GetM()) ||
            (encoding.GetDam() == SixLowPanIphc::HC_COMPR_16 && encoding.GetM()) ||
            (encoding.GetDam() == SixLowPanIphc::HC_COMPR_0 && encoding.GetM()))
        {
            NS_ABORT_MSG("Reserved code found");
        }

        uint8_t contextId = encoding.GetDstContextId();
        if (m_contextTable.find(contextId) == m_contextTable.end())
        {
            NS_LOG_LOGIC("Unknown Destination compression context (" << +contextId
                                                                     << "), dropping packet");
            return true;
        }
        if (m_contextTable[contextId].validLifetime < Simulator::Now())
        {
            NS_LOG_LOGIC("Expired Destination compression context (" << +contextId
                                                                     << "), dropping packet");
            return true;
        }

        uint8_t contextPrefix[16];
        m_contextTable[contextId].contextPrefix.GetBytes(contextPrefix);
        uint8_t contextLength = m_contextTable[contextId].contextPrefix.GetPrefixLength();

        if (!encoding.GetM())
        {
            // unicast
            uint8_t dstAddress[16] = {};
            if (encoding.GetDam() == SixLowPanIphc::HC_COMPR_64)
            {
                memcpy(dstAddress + 8, encoding.GetDstInlinePart(), 8);
            }
            else if (encoding.GetDam() == SixLowPanIphc::HC_COMPR_16)
            {
                dstAddress[11] = 0xff;
                dstAddress[12] = 0xfe;
                memcpy(dstAddress + 14, encoding.GetDstInlinePart(), 2);
            }
            else // SixLowPanIphc::HC_COMPR_0
            {
                Ipv6Address::MakeAutoconfiguredLinkLocalAddress(dst).GetBytes(dstAddress);
            }

            uint8_t bytesToCopy = m_contextTable[contextId].contextPrefix.GetPrefixLength() / 8;
            uint8_t bitsToCopy = contextLength % 8;

            // Do not combine the prefix - we want to override the bytes.
            for (uint8_t i = 0; i < bytesToCopy; i++)
            {
                dstAddress[i] = contextPrefix[i];
            }
            if (bitsToCopy)
            {
                uint8_t addressBitMask = (1 << (8 - bitsToCopy)) - 1;
                uint8_t prefixBitMask = ~addressBitMask;
                dstAddress[bytesToCopy] = (contextPrefix[bytesToCopy] & prefixBitMask) |
                                          (dstAddress[bytesToCopy] & addressBitMask);
            }
            ipHeader.SetDestination(Ipv6Address::Deserialize(dstAddress));
        }
        else
        {
            // multicast
            // Just one possibility: ffXX:XXLL:PPPP:PPPP:PPPP:PPPP:XXXX:XXXX
            uint8_t dstAddress[16] = {};
            dstAddress[0] = 0xff;
            memcpy(dstAddress + 1, encoding.GetDstInlinePart(), 2);
            dstAddress[3] = contextLength;
            memcpy(dstAddress + 4, contextPrefix, 8);
            memcpy(dstAddress + 12, encoding.GetDstInlinePart() + 2, 4);
            ipHeader.SetDestination(Ipv6Address::Deserialize(dstAddress));
        }
    }
    else
    {
        // Destination address compression uses stateless compression.
        if (!encoding.GetM())
        {
            // unicast
            if (encoding.GetDam() == SixLowPanIphc::HC_INLINE)
            {
                uint8_t dstAddress[16] = {};
                memcpy(dstAddress, encoding.GetDstInlinePart(), 16);
                ipHeader.SetDestination(Ipv6Address::Deserialize(dstAddress));
            }
            else if (encoding.GetDam() == SixLowPanIphc::HC_COMPR_64)
            {
                uint8_t dstAddress[16] = {};
                memcpy(dstAddress + 8, encoding.GetDstInlinePart(), 8);
                dstAddress[0] = 0xfe;
                dstAddress[1] = 0x80;
                ipHeader.SetDestination(Ipv6Address::Deserialize(dstAddress));
            }
            else if (encoding.GetDam() == SixLowPanIphc::HC_COMPR_16)
            {
                uint8_t dstAddress[16] = {};
                memcpy(dstAddress + 14, encoding.GetDstInlinePart(), 2);
                dstAddress[0] = 0xfe;
                dstAddress[1] = 0x80;
                dstAddress[11] = 0xff;
                dstAddress[12] = 0xfe;
                ipHeader.SetDestination(Ipv6Address::Deserialize(dstAddress));
            }
            else // SixLowPanIphc::HC_COMPR_0
            {
                ipHeader.SetDestination(Ipv6Address::MakeAutoconfiguredLinkLocalAddress(dst));
            }
        }
        else
        {
            // multicast
            if (encoding.GetDam() == SixLowPanIphc::HC_INLINE)
            {
                uint8_t dstAddress[16] = {};
                memcpy(dstAddress, encoding.GetDstInlinePart(), 16);
                ipHeader.SetDestination(Ipv6Address::Deserialize(dstAddress));
            }
            else if (encoding.GetDam() == SixLowPanIphc::HC_COMPR_64)
            {
                uint8_t dstAddress[16] = {};
                dstAddress[0] = 0xff;
                memcpy(dstAddress + 1, encoding.GetDstInlinePart(), 1);
                memcpy(dstAddress + 11, encoding.GetDstInlinePart() + 1, 5);
                ipHeader.SetDestination(Ipv6Address::Deserialize(dstAddress));
            }
            else if (encoding.GetDam() == SixLowPanIphc::HC_COMPR_16)
            {
                uint8_t dstAddress[16] = {};
                dstAddress[0] = 0xff;
                memcpy(dstAddress + 1, encoding.GetDstInlinePart(), 1);
                memcpy(dstAddress + 13, encoding.GetDstInlinePart() + 1, 3);
                ipHeader.SetDestination(Ipv6Address::Deserialize(dstAddress));
            }
            else // SixLowPanIphc::HC_COMPR_0
            {
                uint8_t dstAddress[16] = {};
                dstAddress[0] = 0xff;
                dstAddress[1] = 0x02;
                memcpy(dstAddress + 15, encoding.GetDstInlinePart(), 1);
                ipHeader.SetDestination(Ipv6Address::Deserialize(dstAddress));
            }
        }
    }

    // Traffic class and Flow Label
    uint8_t traf = 0x00;
    switch (encoding.GetTf())
    {
    case SixLowPanIphc::TF_FULL:
        traf |= encoding.GetEcn();
        traf = (traf << 6) | encoding.GetDscp();
        ipHeader.SetTrafficClass(traf);
        ipHeader.SetFlowLabel(encoding.GetFlowLabel() & 0xfff); // Add 4-bit pad
        break;
    case SixLowPanIphc::TF_DSCP_ELIDED:
        traf |= encoding.GetEcn();
        traf <<= 2; // Add 2-bit pad
        ipHeader.SetTrafficClass(traf);
        ipHeader.SetFlowLabel(encoding.GetFlowLabel());
        break;
    case SixLowPanIphc::TF_FL_ELIDED:
        traf |= encoding.GetEcn();
        traf = (traf << 6) | encoding.GetDscp();
        ipHeader.SetTrafficClass(traf);
        ipHeader.SetFlowLabel(0);
        break;
    case SixLowPanIphc::TF_ELIDED:
        ipHeader.SetFlowLabel(0);
        ipHeader.SetTrafficClass(0);
        break;
    }

    if (encoding.GetNh())
    {
        // Next Header
        uint8_t dispatchRawVal = 0;
        SixLowPanDispatch::NhcDispatch_e dispatchVal;

        packet->CopyData(&dispatchRawVal, sizeof(dispatchRawVal));
        dispatchVal = SixLowPanDispatch::GetNhcDispatchType(dispatchRawVal);

        if (dispatchVal == SixLowPanDispatch::LOWPAN_UDPNHC)
        {
            ipHeader.SetNextHeader(Ipv6Header::IPV6_UDP);
            DecompressLowPanUdpNhc(packet, ipHeader.GetSource(), ipHeader.GetDestination());
        }
        else
        {
            std::pair<uint8_t, bool> retval = DecompressLowPanNhc(packet,
                                                                  src,
                                                                  dst,
                                                                  ipHeader.GetSource(),
                                                                  ipHeader.GetDestination());
            if (retval.second)
            {
                return true;
            }
            else
            {
                ipHeader.SetNextHeader(retval.first);
            }
        }
    }
    else
    {
        ipHeader.SetNextHeader(encoding.GetNextHeader());
    }

    ipHeader.SetPayloadLength(packet->GetSize());

    packet->AddHeader(ipHeader);

    NS_LOG_DEBUG("Rebuilt packet:  " << *packet << " Size " << packet->GetSize());

    return false;
}

uint32_t
SixLowPanNetDevice::CompressLowPanNhc(Ptr<Packet> packet,
                                      uint8_t headerType,
                                      const Address& src,
                                      const Address& dst)
{
    NS_LOG_FUNCTION(this << *packet << int(headerType));

    SixLowPanNhcExtension nhcHeader;
    uint32_t size = 0;
    Buffer blob;

    if (headerType == Ipv6Header::IPV6_EXT_HOP_BY_HOP)
    {
        Ipv6ExtensionHopByHopHeader hopHeader;
        packet->PeekHeader(hopHeader);
        if (hopHeader.GetLength() >= 0xff)
        {
            NS_LOG_DEBUG(
                "LOWPAN_NHC MUST NOT be used to encode IPv6 Extension Headers "
                "that have more than 255 octets following the Length field after compression. "
                "Packet uncompressed.");
            return 0;
        }

        size += packet->RemoveHeader(hopHeader);
        nhcHeader.SetEid(SixLowPanNhcExtension::EID_HOPBYHOP_OPTIONS_H);

        // recursively compress other headers
        uint8_t nextHeader = hopHeader.GetNextHeader();
        if (CanCompressLowPanNhc(nextHeader))
        {
            if (nextHeader == Ipv6Header::IPV6_UDP)
            {
                nhcHeader.SetNh(true);
                size += CompressLowPanUdpNhc(packet, m_omitUdpChecksum);
            }
            else if (nextHeader == Ipv6Header::IPV6_IPV6)
            {
                nhcHeader.SetNh(true);
                size += CompressLowPanIphc(packet, src, dst);
            }
            else
            {
                uint32_t sizeNhc = CompressLowPanNhc(packet, nextHeader, src, dst);
                // the compression might fail due to Extension header size.
                if (sizeNhc)
                {
                    nhcHeader.SetNh(true);
                    size += sizeNhc;
                }
                else
                {
                    nhcHeader.SetNh(false);
                    nhcHeader.SetNextHeader(nextHeader);
                }
            }
        }
        else
        {
            nhcHeader.SetNh(false);
            nhcHeader.SetNextHeader(nextHeader);
        }

        uint32_t blobSize = hopHeader.GetSerializedSize();
        blob.AddAtStart(blobSize);
        hopHeader.Serialize(blob.Begin());
        blob.RemoveAtStart(2);
        blobSize = blob.GetSize();
        nhcHeader.SetBlob(blob.PeekData(), blobSize);
    }
    else if (headerType == Ipv6Header::IPV6_EXT_ROUTING)
    {
        Ipv6ExtensionRoutingHeader routingHeader;
        packet->PeekHeader(routingHeader);
        if (routingHeader.GetLength() >= 0xff)
        {
            NS_LOG_DEBUG(
                "LOWPAN_NHC MUST NOT be used to encode IPv6 Extension Headers "
                "that have more than 255 octets following the Length field after compression. "
                "Packet uncompressed.");
            return 0;
        }

        size += packet->RemoveHeader(routingHeader);
        nhcHeader.SetEid(SixLowPanNhcExtension::EID_ROUTING_H);

        // recursively compress other headers
        uint8_t nextHeader = routingHeader.GetNextHeader();
        if (CanCompressLowPanNhc(nextHeader))
        {
            if (nextHeader == Ipv6Header::IPV6_UDP)
            {
                nhcHeader.SetNh(true);
                size += CompressLowPanUdpNhc(packet, m_omitUdpChecksum);
            }
            else if (nextHeader == Ipv6Header::IPV6_IPV6)
            {
                nhcHeader.SetNh(true);
                size += CompressLowPanIphc(packet, src, dst);
            }
            else
            {
                uint32_t sizeNhc = CompressLowPanNhc(packet, nextHeader, src, dst);
                // the compression might fail due to Extension header size.
                if (sizeNhc)
                {
                    nhcHeader.SetNh(true);
                    size += sizeNhc;
                }
                else
                {
                    nhcHeader.SetNh(false);
                    nhcHeader.SetNextHeader(nextHeader);
                }
            }
        }
        else
        {
            nhcHeader.SetNh(false);
            nhcHeader.SetNextHeader(nextHeader);
        }

        uint32_t blobSize = routingHeader.GetSerializedSize();
        blob.AddAtStart(blobSize);
        routingHeader.Serialize(blob.Begin());
        blob.RemoveAtStart(2);
        blobSize = blob.GetSize();
        nhcHeader.SetBlob(blob.PeekData(), blobSize);
    }
    else if (headerType == Ipv6Header::IPV6_EXT_FRAGMENTATION)
    {
        Ipv6ExtensionFragmentHeader fragHeader;
        packet->PeekHeader(fragHeader);
        if (fragHeader.GetLength() >= 0xff)
        {
            NS_LOG_DEBUG(
                "LOWPAN_NHC MUST NOT be used to encode IPv6 Extension Headers "
                "that have more than 255 octets following the Length field after compression. "
                "Packet uncompressed.");
            return 0;
        }
        size += packet->RemoveHeader(fragHeader);
        nhcHeader.SetEid(SixLowPanNhcExtension::EID_FRAGMENTATION_H);

        // recursively compress other headers
        uint8_t nextHeader = fragHeader.GetNextHeader();
        if (CanCompressLowPanNhc(nextHeader))
        {
            if (nextHeader == Ipv6Header::IPV6_UDP)
            {
                nhcHeader.SetNh(true);
                size += CompressLowPanUdpNhc(packet, m_omitUdpChecksum);
            }
            else if (nextHeader == Ipv6Header::IPV6_IPV6)
            {
                nhcHeader.SetNh(true);
                size += CompressLowPanIphc(packet, src, dst);
            }
            else
            {
                uint32_t sizeNhc = CompressLowPanNhc(packet, nextHeader, src, dst);
                // the compression might fail due to Extension header size.
                if (sizeNhc)
                {
                    nhcHeader.SetNh(true);
                    size += sizeNhc;
                }
                else
                {
                    nhcHeader.SetNh(false);
                    nhcHeader.SetNextHeader(nextHeader);
                }
            }
        }
        else
        {
            nhcHeader.SetNh(false);
            nhcHeader.SetNextHeader(nextHeader);
        }

        uint32_t blobSize = fragHeader.GetSerializedSize();
        blob.AddAtStart(blobSize);
        fragHeader.Serialize(blob.Begin());
        blob.RemoveAtStart(2);
        blobSize = blob.GetSize();
        nhcHeader.SetBlob(blob.PeekData(), blobSize);
    }
    else if (headerType == Ipv6Header::IPV6_EXT_DESTINATION)
    {
        Ipv6ExtensionDestinationHeader destHeader;
        packet->PeekHeader(destHeader);
        if (destHeader.GetLength() >= 0xff)
        {
            NS_LOG_DEBUG(
                "LOWPAN_NHC MUST NOT be used to encode IPv6 Extension Headers "
                "that have more than 255 octets following the Length field after compression. "
                "Packet uncompressed.");
            return 0;
        }
        size += packet->RemoveHeader(destHeader);
        nhcHeader.SetEid(SixLowPanNhcExtension::EID_DESTINATION_OPTIONS_H);

        // recursively compress other headers
        uint8_t nextHeader = destHeader.GetNextHeader();
        if (CanCompressLowPanNhc(nextHeader))
        {
            if (nextHeader == Ipv6Header::IPV6_UDP)
            {
                nhcHeader.SetNh(true);
                size += CompressLowPanUdpNhc(packet, m_omitUdpChecksum);
            }
            else if (nextHeader == Ipv6Header::IPV6_IPV6)
            {
                nhcHeader.SetNh(true);
                size += CompressLowPanIphc(packet, src, dst);
            }
            else
            {
                uint32_t sizeNhc = CompressLowPanNhc(packet, nextHeader, src, dst);
                // the compression might fail due to Extension header size.
                if (sizeNhc)
                {
                    nhcHeader.SetNh(true);
                    size += sizeNhc;
                }
                else
                {
                    nhcHeader.SetNh(false);
                    nhcHeader.SetNextHeader(nextHeader);
                }
            }
        }
        else
        {
            nhcHeader.SetNh(false);
            nhcHeader.SetNextHeader(nextHeader);
        }

        uint32_t blobSize = destHeader.GetSerializedSize();
        blob.AddAtStart(blobSize);
        destHeader.Serialize(blob.Begin());
        blob.RemoveAtStart(2);
        blobSize = blob.GetSize();
        nhcHeader.SetBlob(blob.PeekData(), blobSize);
    }
    else if (headerType == Ipv6Header::IPV6_EXT_MOBILITY)
    {
        // \todo: IPv6 Mobility Header is not supported in ns-3
        NS_ABORT_MSG("IPv6 Mobility Header is not supported in ns-3 yet");
        return 0;
    }
    else
    {
        NS_ABORT_MSG("Unexpected Extension Header");
    }

    NS_LOG_DEBUG("NHC Compression - NHC header size = " << nhcHeader.GetSerializedSize());
    NS_LOG_DEBUG("NHC Compression - packet size = " << packet->GetSize());

    packet->AddHeader(nhcHeader);

    NS_LOG_DEBUG("Packet after NHC compression: " << *packet);
    return size;
}

std::pair<uint8_t, bool>
SixLowPanNetDevice::DecompressLowPanNhc(Ptr<Packet> packet,
                                        const Address& src,
                                        const Address& dst,
                                        Ipv6Address srcAddress,
                                        Ipv6Address dstAddress)
{
    NS_LOG_FUNCTION(this << *packet);

    SixLowPanNhcExtension encoding;

    uint32_t ret [[maybe_unused]] = packet->RemoveHeader(encoding);
    NS_LOG_DEBUG("removed " << ret << " bytes - pkt is " << *packet);

    Ipv6ExtensionHopByHopHeader hopHeader;
    Ipv6ExtensionRoutingHeader routingHeader;
    Ipv6ExtensionFragmentHeader fragHeader;
    Ipv6ExtensionDestinationHeader destHeader;

    uint32_t blobSize;
    uint8_t blobData[260];
    blobSize = encoding.CopyBlob(blobData + 2, 260 - 2);
    uint8_t paddingSize = 0;

    uint8_t actualEncodedHeaderType = encoding.GetEid();
    uint8_t actualHeaderType;
    Buffer blob;

    switch (actualEncodedHeaderType)
    {
    case SixLowPanNhcExtension::EID_HOPBYHOP_OPTIONS_H:
        actualHeaderType = Ipv6Header::IPV6_EXT_HOP_BY_HOP;
        if (encoding.GetNh())
        {
            // Next Header
            uint8_t dispatchRawVal = 0;
            SixLowPanDispatch::NhcDispatch_e dispatchVal;

            packet->CopyData(&dispatchRawVal, sizeof(dispatchRawVal));
            dispatchVal = SixLowPanDispatch::GetNhcDispatchType(dispatchRawVal);

            if (dispatchVal == SixLowPanDispatch::LOWPAN_UDPNHC)
            {
                blobData[0] = Ipv6Header::IPV6_UDP;
                DecompressLowPanUdpNhc(packet, srcAddress, dstAddress);
            }
            else
            {
                blobData[0] = DecompressLowPanNhc(packet, src, dst, srcAddress, dstAddress).first;
            }
        }
        else
        {
            blobData[0] = encoding.GetNextHeader();
        }

        // manually add some padding if needed
        if ((blobSize + 2) % 8 > 0)
        {
            paddingSize = 8 - (blobSize + 2) % 8;
        }
        if (paddingSize == 1)
        {
            blobData[blobSize + 2] = 0;
        }
        else if (paddingSize > 1)
        {
            blobData[blobSize + 2] = 1;
            blobData[blobSize + 2 + 1] = paddingSize - 2;
            for (uint8_t i = 0; i < paddingSize - 2; i++)
            {
                blobData[blobSize + 2 + 2 + i] = 0;
            }
        }
        blobData[1] = ((blobSize + 2 + paddingSize) >> 3) - 1;
        blob.AddAtStart(blobSize + 2 + paddingSize);
        blob.Begin().Write(blobData, blobSize + 2 + paddingSize);
        hopHeader.Deserialize(blob.Begin());

        packet->AddHeader(hopHeader);
        break;

    case SixLowPanNhcExtension::EID_ROUTING_H:
        actualHeaderType = Ipv6Header::IPV6_EXT_ROUTING;
        if (encoding.GetNh())
        {
            // Next Header
            uint8_t dispatchRawVal = 0;
            SixLowPanDispatch::NhcDispatch_e dispatchVal;

            packet->CopyData(&dispatchRawVal, sizeof(dispatchRawVal));
            dispatchVal = SixLowPanDispatch::GetNhcDispatchType(dispatchRawVal);

            if (dispatchVal == SixLowPanDispatch::LOWPAN_UDPNHC)
            {
                blobData[0] = Ipv6Header::IPV6_UDP;
                DecompressLowPanUdpNhc(packet, srcAddress, dstAddress);
            }
            else
            {
                blobData[0] = DecompressLowPanNhc(packet, src, dst, srcAddress, dstAddress).first;
            }
        }
        else
        {
            blobData[0] = encoding.GetNextHeader();
        }
        blobData[1] = ((blobSize + 2) >> 3) - 1;
        blob.AddAtStart(blobSize + 2);
        blob.Begin().Write(blobData, blobSize + 2);
        routingHeader.Deserialize(blob.Begin());
        packet->AddHeader(routingHeader);
        break;

    case SixLowPanNhcExtension::EID_FRAGMENTATION_H:
        actualHeaderType = Ipv6Header::IPV6_EXT_FRAGMENTATION;
        if (encoding.GetNh())
        {
            // Next Header
            uint8_t dispatchRawVal = 0;
            SixLowPanDispatch::NhcDispatch_e dispatchVal;

            packet->CopyData(&dispatchRawVal, sizeof(dispatchRawVal));
            dispatchVal = SixLowPanDispatch::GetNhcDispatchType(dispatchRawVal);

            if (dispatchVal == SixLowPanDispatch::LOWPAN_UDPNHC)
            {
                blobData[0] = Ipv6Header::IPV6_UDP;
                DecompressLowPanUdpNhc(packet, srcAddress, dstAddress);
            }
            else
            {
                blobData[0] = DecompressLowPanNhc(packet, src, dst, srcAddress, dstAddress).first;
            }
        }
        else
        {
            blobData[0] = encoding.GetNextHeader();
        }
        blobData[1] = 0;

        blob.AddAtStart(blobSize + 2);
        blob.Begin().Write(blobData, blobSize + 2);

        fragHeader.Deserialize(blob.Begin());
        packet->AddHeader(fragHeader);
        break;

    case SixLowPanNhcExtension::EID_DESTINATION_OPTIONS_H:
        actualHeaderType = Ipv6Header::IPV6_EXT_DESTINATION;
        if (encoding.GetNh())
        {
            // Next Header
            uint8_t dispatchRawVal = 0;
            SixLowPanDispatch::NhcDispatch_e dispatchVal;

            packet->CopyData(&dispatchRawVal, sizeof(dispatchRawVal));
            dispatchVal = SixLowPanDispatch::GetNhcDispatchType(dispatchRawVal);

            if (dispatchVal == SixLowPanDispatch::LOWPAN_UDPNHC)
            {
                blobData[0] = Ipv6Header::IPV6_UDP;
                DecompressLowPanUdpNhc(packet, srcAddress, dstAddress);
            }
            else
            {
                blobData[0] = DecompressLowPanNhc(packet, src, dst, srcAddress, dstAddress).first;
            }
        }
        else
        {
            blobData[0] = encoding.GetNextHeader();
        }

        // manually add some padding if needed
        if ((blobSize + 2) % 8 > 0)
        {
            paddingSize = 8 - (blobSize + 2) % 8;
        }
        if (paddingSize == 1)
        {
            blobData[blobSize + 2] = 0;
        }
        else if (paddingSize > 1)
        {
            blobData[blobSize + 2] = 1;
            blobData[blobSize + 2 + 1] = paddingSize - 2;
            for (uint8_t i = 0; i < paddingSize - 2; i++)
            {
                blobData[blobSize + 2 + 2 + i] = 0;
            }
        }
        blobData[1] = ((blobSize + 2 + paddingSize) >> 3) - 1;
        blob.AddAtStart(blobSize + 2 + paddingSize);
        blob.Begin().Write(blobData, blobSize + 2 + paddingSize);
        destHeader.Deserialize(blob.Begin());

        packet->AddHeader(destHeader);
        break;
    case SixLowPanNhcExtension::EID_MOBILITY_H:
        // \todo: IPv6 Mobility Header is not supported in ns-3
        NS_ABORT_MSG("IPv6 Mobility Header is not supported in ns-3 yet");
        break;
    case SixLowPanNhcExtension::EID_IPv6_H:
        actualHeaderType = Ipv6Header::IPV6_IPV6;
        if (DecompressLowPanIphc(packet, src, dst))
        {
            m_dropTrace(DROP_SATETFUL_DECOMPRESSION_PROBLEM, packet, this, GetIfIndex());
            return std::pair<uint8_t, bool>(0, true);
        }
        break;
    default:
        NS_ABORT_MSG("Trying to decode unknown Extension Header");
        break;
    }

    NS_LOG_DEBUG("Rebuilt packet: " << *packet << " Size " << packet->GetSize());
    return std::pair<uint8_t, bool>(actualHeaderType, false);
}

uint32_t
SixLowPanNetDevice::CompressLowPanUdpNhc(Ptr<Packet> packet, bool omitChecksum)
{
    NS_LOG_FUNCTION(this << *packet << int(omitChecksum));

    UdpHeader udpHeader;
    SixLowPanUdpNhcExtension udpNhcHeader;
    uint32_t size = 0;

    NS_ASSERT_MSG(packet->PeekHeader(udpHeader) != 0, "UDP header not found, abort");

    size += packet->RemoveHeader(udpHeader);

    // Set the C field and checksum
    udpNhcHeader.SetC(false);
    uint16_t checksum = udpHeader.GetChecksum();
    udpNhcHeader.SetChecksum(checksum);

    if (omitChecksum && udpHeader.IsChecksumOk())
    {
        udpNhcHeader.SetC(true);
    }

    // Set the value of the ports
    udpNhcHeader.SetSrcPort(udpHeader.GetSourcePort());
    udpNhcHeader.SetDstPort(udpHeader.GetDestinationPort());

    // Set the P field
    if ((udpHeader.GetSourcePort() >> 4) == 0xf0b && (udpHeader.GetDestinationPort() >> 4) == 0xf0b)
    {
        udpNhcHeader.SetPorts(SixLowPanUdpNhcExtension::PORTS_LAST_SRC_LAST_DST);
    }
    else if ((udpHeader.GetSourcePort() >> 8) == 0xf0 &&
             (udpHeader.GetDestinationPort() >> 8) != 0xf0)
    {
        udpNhcHeader.SetPorts(SixLowPanUdpNhcExtension::PORTS_LAST_SRC_ALL_DST);
    }
    else if ((udpHeader.GetSourcePort() >> 8) != 0xf0 &&
             (udpHeader.GetDestinationPort() >> 8) == 0xf0)
    {
        udpNhcHeader.SetPorts(SixLowPanUdpNhcExtension::PORTS_ALL_SRC_LAST_DST);
    }
    else
    {
        udpNhcHeader.SetPorts(SixLowPanUdpNhcExtension::PORTS_INLINE);
    }

    NS_LOG_DEBUG(
        "UDP_NHC Compression - UDP_NHC header size = " << udpNhcHeader.GetSerializedSize());
    NS_LOG_DEBUG("UDP_NHC Compression - packet size = " << packet->GetSize());

    packet->AddHeader(udpNhcHeader);

    NS_LOG_DEBUG("Packet after UDP_NHC compression: " << *packet);

    return size;
}

void
SixLowPanNetDevice::DecompressLowPanUdpNhc(Ptr<Packet> packet, Ipv6Address saddr, Ipv6Address daddr)
{
    NS_LOG_FUNCTION(this << *packet);

    UdpHeader udpHeader;
    SixLowPanUdpNhcExtension encoding;

    uint32_t ret [[maybe_unused]] = packet->RemoveHeader(encoding);
    NS_LOG_DEBUG("removed " << ret << " bytes - pkt is " << *packet);

    // Set the value of the ports
    switch (encoding.GetPorts())
    {
        uint16_t temp;
    case SixLowPanUdpNhcExtension::PORTS_INLINE:
        udpHeader.SetSourcePort(encoding.GetSrcPort());
        udpHeader.SetDestinationPort(encoding.GetDstPort());
        break;
    case SixLowPanUdpNhcExtension::PORTS_ALL_SRC_LAST_DST:
        udpHeader.SetSourcePort(encoding.GetSrcPort());
        temp = (0xf0 << 8) | encoding.GetDstPort();
        udpHeader.SetDestinationPort(temp);
        break;
    case SixLowPanUdpNhcExtension::PORTS_LAST_SRC_ALL_DST:
        temp = (0xf0 << 8) | encoding.GetSrcPort();
        udpHeader.SetSourcePort(temp);
        udpHeader.SetDestinationPort(encoding.GetDstPort());
        break;
    case SixLowPanUdpNhcExtension::PORTS_LAST_SRC_LAST_DST:
        temp = (0xf0b << 4) | encoding.GetSrcPort();
        udpHeader.SetSourcePort(temp);
        temp = (0xf0b << 4) | encoding.GetDstPort();
        udpHeader.SetDestinationPort(temp);
        break;
    }

    // Get the C field and checksum
    if (Node::ChecksumEnabled())
    {
        if (encoding.GetC())
        {
            NS_LOG_LOGIC("Recalculating UDP Checksum");
            udpHeader.EnableChecksums();
            udpHeader.InitializeChecksum(saddr, daddr, UdpL4Protocol::PROT_NUMBER);
            packet->AddHeader(udpHeader);
        }
        else
        {
            NS_LOG_LOGIC("Forcing UDP Checksum to " << encoding.GetChecksum());
            udpHeader.ForceChecksum(encoding.GetChecksum());
            packet->AddHeader(udpHeader);
            NS_LOG_LOGIC("UDP checksum is ok ? " << udpHeader.IsChecksumOk());
        }
    }
    else
    {
        packet->AddHeader(udpHeader);
    }

    NS_LOG_DEBUG("Rebuilt packet: " << *packet << " Size " << packet->GetSize());
}

void
SixLowPanNetDevice::DoFragmentation(Ptr<Packet> packet,
                                    uint32_t origPacketSize,
                                    uint32_t origHdrSize,
                                    uint32_t extraHdrSize,
                                    std::list<Ptr<Packet>>& listFragments)
{
    NS_LOG_FUNCTION(this << *packet);

    Ptr<Packet> p = packet->Copy();

    uint16_t offsetData = 0;
    uint16_t offset = 0;
    uint16_t l2Mtu = m_netDevice->GetMtu();
    uint32_t packetSize = packet->GetSize();
    uint32_t compressedHeaderSize = packetSize - (origPacketSize - origHdrSize);

    auto tag = static_cast<uint16_t>(m_rng->GetValue(0, 65535));
    NS_LOG_LOGIC("random tag " << tag << " - test " << packetSize);

    // first fragment
    SixLowPanFrag1 frag1Hdr;
    frag1Hdr.SetDatagramTag(tag);

    uint32_t size;
    NS_ASSERT_MSG(l2Mtu > frag1Hdr.GetSerializedSize(),
                  "6LoWPAN: can not fragment, 6LoWPAN headers are bigger than MTU");

    // All the headers are subtracted to get remaining units for data
    size = l2Mtu - frag1Hdr.GetSerializedSize() - compressedHeaderSize - extraHdrSize;
    size -= size % 8;
    size += compressedHeaderSize;

    frag1Hdr.SetDatagramSize(origPacketSize);

    Ptr<Packet> fragment1 = p->CreateFragment(offsetData, size);
    offset += size + origHdrSize - compressedHeaderSize;
    offsetData += size;

    fragment1->AddHeader(frag1Hdr);
    listFragments.push_back(fragment1);

    bool moreFrag = true;
    do
    {
        SixLowPanFragN fragNHdr;
        fragNHdr.SetDatagramTag(tag);
        fragNHdr.SetDatagramSize(origPacketSize);
        fragNHdr.SetDatagramOffset((offset) >> 3);

        size = l2Mtu - fragNHdr.GetSerializedSize() - extraHdrSize;
        size -= size % 8;

        if ((offsetData + size) > packetSize)
        {
            size = packetSize - offsetData;
            moreFrag = false;
        }

        if (size > 0)
        {
            NS_LOG_LOGIC("Fragment creation - " << offset << ", " << offset);
            Ptr<Packet> fragment = p->CreateFragment(offsetData, size);
            NS_LOG_LOGIC("Fragment created - " << offset << ", " << fragment->GetSize());

            offset += size;
            offsetData += size;

            fragment->AddHeader(fragNHdr);
            listFragments.push_back(fragment);
        }
    } while (moreFrag);
}

bool
SixLowPanNetDevice::ProcessFragment(Ptr<Packet>& packet,
                                    const Address& src,
                                    const Address& dst,
                                    bool isFirst)
{
    NS_LOG_FUNCTION(this << *packet);
    SixLowPanFrag1 frag1Header;
    SixLowPanFragN fragNHeader;
    FragmentKey_t key;
    uint16_t packetSize;
    key.first = std::pair<Address, Address>(src, dst);

    Ptr<Packet> p = packet->Copy();
    uint16_t offset = 0;

    /* Implementation note:
     *
     * The fragment offset is relative to the *uncompressed* packet.
     * On the other hand, the packet can not be uncompressed correctly without all
     * its fragments, as the UDP checksum can not be computed otherwise.
     *
     * As a consequence we must uncompress the packet twice, and save its first
     * fragment for the final one.
     */

    if (isFirst)
    {
        uint8_t dispatchRawValFrag1 = 0;
        SixLowPanDispatch::Dispatch_e dispatchValFrag1;

        p->RemoveHeader(frag1Header);
        packetSize = frag1Header.GetDatagramSize();
        p->CopyData(&dispatchRawValFrag1, sizeof(dispatchRawValFrag1));
        dispatchValFrag1 = SixLowPanDispatch::GetDispatchType(dispatchRawValFrag1);
        NS_LOG_DEBUG("Dispatches: " << int(dispatchRawValFrag1) << " - " << int(dispatchValFrag1));
        NS_LOG_DEBUG("Packet: " << *p);

        switch (dispatchValFrag1)
        {
        case SixLowPanDispatch::LOWPAN_IPv6: {
            SixLowPanIpv6 uncompressedHdr;
            p->RemoveHeader(uncompressedHdr);
        }
        break;
        case SixLowPanDispatch::LOWPAN_HC1:
            DecompressLowPanHc1(p, src, dst);
            break;
        case SixLowPanDispatch::LOWPAN_IPHC:
            if (DecompressLowPanIphc(p, src, dst))
            {
                m_dropTrace(DROP_SATETFUL_DECOMPRESSION_PROBLEM, p, this, GetIfIndex());
                return false;
            }
            break;
        default:
            NS_FATAL_ERROR("Unsupported 6LoWPAN encoding, exiting.");
            break;
        }

        key.second = std::pair<uint16_t, uint16_t>(frag1Header.GetDatagramSize(),
                                                   frag1Header.GetDatagramTag());
    }
    else
    {
        p->RemoveHeader(fragNHeader);
        packetSize = fragNHeader.GetDatagramSize();
        offset = fragNHeader.GetDatagramOffset() << 3;
        key.second = std::pair<uint16_t, uint16_t>(fragNHeader.GetDatagramSize(),
                                                   fragNHeader.GetDatagramTag());
    }

    std::shared_ptr<Fragments> fragments;

    auto it = m_fragments.find(key);
    if (it == m_fragments.end())
    {
        // erase the oldest packet.
        if (m_fragmentReassemblyListSize && (m_fragments.size() >= m_fragmentReassemblyListSize))
        {
            auto iter = m_timeoutEventList.begin();
            FragmentKey_t oldestKey = std::get<1>(*iter);

            std::list<Ptr<Packet>> storedFragments = m_fragments[oldestKey]->GetFragments();
            for (auto fragIter = storedFragments.begin(); fragIter != storedFragments.end();
                 fragIter++)
            {
                m_dropTrace(DROP_FRAGMENT_BUFFER_FULL, *fragIter, this, GetIfIndex());
            }

            m_timeoutEventList.erase(m_fragments[oldestKey]->GetTimeoutIter());
            m_fragments[oldestKey] = nullptr;
            m_fragments.erase(oldestKey);
        }
        fragments = std::make_shared<Fragments>();
        fragments->SetPacketSize(packetSize);
        m_fragments.insert(std::make_pair(key, fragments));
        uint32_t ifIndex = GetIfIndex();

        auto iter = SetTimeout(key, ifIndex);
        fragments->SetTimeoutIter(iter);
    }
    else
    {
        fragments = it->second;
    }

    fragments->AddFragment(p, offset);

    // add the very first fragment so we can correctly decode the packet once is rebuilt.
    // this is needed because otherwise the UDP header length and checksum can not be calculated.
    if (isFirst)
    {
        fragments->AddFirstFragment(packet);
    }

    if (fragments->IsEntire())
    {
        packet = fragments->GetPacket();
        NS_LOG_LOGIC("Reconstructed packet: " << *packet);

        SixLowPanFrag1 frag1Header;
        packet->RemoveHeader(frag1Header);

        NS_LOG_LOGIC("Rebuilt packet. Size " << packet->GetSize() << " - " << *packet);
        m_timeoutEventList.erase(fragments->GetTimeoutIter());
        fragments = nullptr;
        m_fragments.erase(key);
        return true;
    }

    return false;
}

SixLowPanNetDevice::Fragments::Fragments()
{
    NS_LOG_FUNCTION(this);
    m_packetSize = 0;
}

SixLowPanNetDevice::Fragments::~Fragments()
{
    NS_LOG_FUNCTION(this);
}

void
SixLowPanNetDevice::Fragments::AddFragment(Ptr<Packet> fragment, uint16_t fragmentOffset)
{
    NS_LOG_FUNCTION(this << fragmentOffset << *fragment);

    std::list<std::pair<Ptr<Packet>, uint16_t>>::iterator it;
    bool duplicate = false;

    for (it = m_fragments.begin(); it != m_fragments.end(); it++)
    {
        if (it->second > fragmentOffset)
        {
            break;
        }
        if (it->second == fragmentOffset)
        {
            duplicate = true;
            NS_ASSERT_MSG(fragment->GetSize() == it->first->GetSize(),
                          "Duplicate fragment size differs. Aborting.");
            break;
        }
    }
    if (!duplicate)
    {
        m_fragments.insert(it, std::make_pair(fragment, fragmentOffset));
    }
}

void
SixLowPanNetDevice::Fragments::AddFirstFragment(Ptr<Packet> fragment)
{
    NS_LOG_FUNCTION(this << *fragment);

    m_firstFragment = fragment;
}

bool
SixLowPanNetDevice::Fragments::IsEntire() const
{
    NS_LOG_FUNCTION(this);

    bool ret = !m_fragments.empty();
    uint16_t lastEndOffset = 0;

    if (ret)
    {
        for (auto it = m_fragments.begin(); it != m_fragments.end(); it++)
        {
            // overlapping fragments should not exist
            NS_LOG_LOGIC("Checking overlaps " << lastEndOffset << " - " << it->second);

            if (lastEndOffset < it->second)
            {
                ret = false;
                break;
            }
            // fragments might overlap in strange ways
            uint16_t fragmentEnd = it->first->GetSize() + it->second;
            lastEndOffset = std::max(lastEndOffset, fragmentEnd);
        }
    }

    return ret && lastEndOffset == m_packetSize;
}

Ptr<Packet>
SixLowPanNetDevice::Fragments::GetPacket() const
{
    NS_LOG_FUNCTION(this);

    auto it = m_fragments.begin();

    Ptr<Packet> p = Create<Packet>();
    uint16_t lastEndOffset = 0;

    p->AddAtEnd(m_firstFragment);
    it = m_fragments.begin();
    lastEndOffset = it->first->GetSize();

    for (it++; it != m_fragments.end(); it++)
    {
        if (lastEndOffset > it->second)
        {
            NS_ABORT_MSG("Overlapping fragments found, forbidden condition");
        }
        else
        {
            NS_LOG_LOGIC("Adding: " << *(it->first));
            p->AddAtEnd(it->first);
        }
        lastEndOffset += it->first->GetSize();
    }

    return p;
}

void
SixLowPanNetDevice::Fragments::SetPacketSize(uint32_t packetSize)
{
    NS_LOG_FUNCTION(this << packetSize);
    m_packetSize = packetSize;
}

std::list<Ptr<Packet>>
SixLowPanNetDevice::Fragments::GetFragments() const
{
    std::list<Ptr<Packet>> fragments;
    for (auto iter = m_fragments.begin(); iter != m_fragments.end(); iter++)
    {
        fragments.push_back(iter->first);
    }
    return fragments;
}

void
SixLowPanNetDevice::Fragments::SetTimeoutIter(FragmentsTimeoutsListI_t iter)
{
    m_timeoutIter = iter;
}

SixLowPanNetDevice::FragmentsTimeoutsListI_t
SixLowPanNetDevice::Fragments::GetTimeoutIter()
{
    return m_timeoutIter;
}

void
SixLowPanNetDevice::HandleFragmentsTimeout(FragmentKey_t key, uint32_t iif)
{
    NS_LOG_FUNCTION(this);

    auto it = m_fragments.find(key);
    std::list<Ptr<Packet>> storedFragments = it->second->GetFragments();
    for (auto fragIter = storedFragments.begin(); fragIter != storedFragments.end(); fragIter++)
    {
        m_dropTrace(DROP_FRAGMENT_TIMEOUT, *fragIter, this, iif);
    }
    // clear the buffers
    it->second = nullptr;

    m_fragments.erase(key);
}

Address
SixLowPanNetDevice::Get16MacFrom48Mac(Address addr)
{
    NS_ASSERT_MSG(Mac48Address::IsMatchingType(addr), "Need a Mac48Address" << addr);

    uint8_t buf[6];
    addr.CopyTo(buf);

    Mac16Address shortAddr;
    shortAddr.CopyFrom(buf + 4);

    return shortAddr;
}

SixLowPanNetDevice::FragmentsTimeoutsListI_t
SixLowPanNetDevice::SetTimeout(FragmentKey_t key, uint32_t iif)
{
    if (m_timeoutEventList.empty())
    {
        m_timeoutEvent = Simulator::Schedule(m_fragmentExpirationTimeout,
                                             &SixLowPanNetDevice::HandleTimeout,
                                             this);
    }
    m_timeoutEventList.emplace_back(Simulator::Now() + m_fragmentExpirationTimeout, key, iif);

    auto iter = --m_timeoutEventList.end();

    return iter;
}

void
SixLowPanNetDevice::HandleTimeout()
{
    Time now = Simulator::Now();

    while (!m_timeoutEventList.empty() && std::get<0>(*m_timeoutEventList.begin()) == now)
    {
        HandleFragmentsTimeout(std::get<1>(*m_timeoutEventList.begin()),
                               std::get<2>(*m_timeoutEventList.begin()));
        m_timeoutEventList.pop_front();
    }

    if (m_timeoutEventList.empty())
    {
        return;
    }

    Time difference = std::get<0>(*m_timeoutEventList.begin()) - now;
    m_timeoutEvent = Simulator::Schedule(difference, &SixLowPanNetDevice::HandleTimeout, this);
}

void
SixLowPanNetDevice::AddContext(uint8_t contextId,
                               Ipv6Prefix contextPrefix,
                               bool compressionAllowed,
                               Time validLifetime)
{
    NS_LOG_FUNCTION(this << +contextId << Ipv6Address::GetOnes().CombinePrefix(contextPrefix)
                         << contextPrefix << compressionAllowed << validLifetime.As(Time::S));

    if (contextId > 15)
    {
        NS_LOG_LOGIC("Invalid context ID (" << +contextId << "), ignoring");
        return;
    }

    if (validLifetime.IsZero())
    {
        NS_LOG_LOGIC("Context (" << +contextId << "), removed (validity time is zero)");
        m_contextTable.erase(contextId);
        return;
    }

    m_contextTable[contextId].contextPrefix = contextPrefix;
    m_contextTable[contextId].compressionAllowed = compressionAllowed;
    m_contextTable[contextId].validLifetime = Simulator::Now() + validLifetime;
}

bool
SixLowPanNetDevice::GetContext(uint8_t contextId,
                               Ipv6Prefix& contextPrefix,
                               bool& compressionAllowed,
                               Time& validLifetime)
{
    NS_LOG_FUNCTION(this << +contextId);

    if (contextId > 15)
    {
        NS_LOG_LOGIC("Invalid context ID (" << +contextId << "), ignoring");
        return false;
    }

    if (m_contextTable.find(contextId) == m_contextTable.end())
    {
        NS_LOG_LOGIC("Context not found (" << +contextId << "), ignoring");
        return false;
    }

    contextPrefix = m_contextTable[contextId].contextPrefix;
    compressionAllowed = m_contextTable[contextId].compressionAllowed;
    validLifetime = m_contextTable[contextId].validLifetime;

    return true;
}

void
SixLowPanNetDevice::RenewContext(uint8_t contextId, Time validLifetime)
{
    NS_LOG_FUNCTION(this << +contextId << validLifetime.As(Time::S));

    if (contextId > 15)
    {
        NS_LOG_LOGIC("Invalid context ID (" << +contextId << "), ignoring");
        return;
    }

    if (m_contextTable.find(contextId) == m_contextTable.end())
    {
        NS_LOG_LOGIC("Context not found (" << +contextId << "), ignoring");
        return;
    }
    m_contextTable[contextId].compressionAllowed = true;
    m_contextTable[contextId].validLifetime = Simulator::Now() + validLifetime;
}

void
SixLowPanNetDevice::InvalidateContext(uint8_t contextId)
{
    NS_LOG_FUNCTION(this << +contextId);

    if (contextId > 15)
    {
        NS_LOG_LOGIC("Invalid context ID (" << +contextId << "), ignoring");
        return;
    }

    if (m_contextTable.find(contextId) == m_contextTable.end())
    {
        NS_LOG_LOGIC("Context not found (" << +contextId << "), ignoring");
        return;
    }
    m_contextTable[contextId].compressionAllowed = false;
}

void
SixLowPanNetDevice::RemoveContext(uint8_t contextId)
{
    NS_LOG_FUNCTION(this << +contextId);

    if (contextId > 15)
    {
        NS_LOG_LOGIC("Invalid context ID (" << +contextId << "), ignoring");
        return;
    }

    if (m_contextTable.find(contextId) == m_contextTable.end())
    {
        NS_LOG_LOGIC("Context not found (" << +contextId << "), ignoring");
        return;
    }

    m_contextTable.erase(contextId);
}

bool
SixLowPanNetDevice::FindUnicastCompressionContext(Ipv6Address address, uint8_t& contextId)
{
    NS_LOG_FUNCTION(this << address);

    for (const auto& iter : m_contextTable)
    {
        ContextEntry context = iter.second;

        if (context.compressionAllowed && context.validLifetime > Simulator::Now())
        {
            if (address.HasPrefix(context.contextPrefix))
            {
                NS_LOG_LOGIC("Found context "
                             << +contextId << " "
                             << Ipv6Address::GetOnes().CombinePrefix(context.contextPrefix)
                             << context.contextPrefix << " matching");

                contextId = iter.first;
                return true;
            }
        }
    }
    return false;
}

bool
SixLowPanNetDevice::FindMulticastCompressionContext(Ipv6Address address, uint8_t& contextId)
{
    NS_LOG_FUNCTION(this << address);

    // The only allowed context-based compressed multicast address is in the form
    // ffXX:XXLL:PPPP:PPPP:PPPP:PPPP:XXXX:XXXX

    for (const auto& iter : m_contextTable)
    {
        ContextEntry context = iter.second;

        if (context.compressionAllowed && context.validLifetime > Simulator::Now())
        {
            uint8_t contextLength = context.contextPrefix.GetPrefixLength();

            if (contextLength <= 64) // only 64-bit prefixes or less are allowed.
            {
                uint8_t contextBytes[16];
                uint8_t addressBytes[16];

                context.contextPrefix.GetBytes(contextBytes);
                address.GetBytes(addressBytes);

                if (addressBytes[3] == contextLength && addressBytes[4] == contextBytes[0] &&
                    addressBytes[5] == contextBytes[1] && addressBytes[6] == contextBytes[2] &&
                    addressBytes[7] == contextBytes[3] && addressBytes[8] == contextBytes[4] &&
                    addressBytes[9] == contextBytes[5] && addressBytes[10] == contextBytes[6] &&
                    addressBytes[11] == contextBytes[7])
                {
                    NS_LOG_LOGIC("Found context "
                                 << +contextId << " "
                                 << Ipv6Address::GetOnes().CombinePrefix(context.contextPrefix)
                                 << context.contextPrefix << " matching");

                    contextId = iter.first;
                    return true;
                }
            }
        }
    }
    return false;
}

Ipv6Address
SixLowPanNetDevice::CleanPrefix(Ipv6Address address, Ipv6Prefix prefix)
{
    uint8_t addressBytes[16];
    address.GetBytes(addressBytes);
    uint8_t prefixLength = prefix.GetPrefixLength();

    uint8_t bytesToClean = prefixLength / 8;
    uint8_t bitsToClean = prefixLength % 8;
    for (uint8_t i = 0; i < bytesToClean; i++)
    {
        addressBytes[i] = 0;
    }
    if (bitsToClean)
    {
        uint8_t cleanupMask = (1 << bitsToClean) - 1;
        addressBytes[bytesToClean] &= cleanupMask;
    }

    Ipv6Address cleanedAddress = Ipv6Address::Deserialize(addressBytes);

    return cleanedAddress;
}

} // namespace ns3

// namespace ns3
