/*
 * Copyright (c) 2007-2009 Strasbourg University
 *
 * SPDX-License-Identifier: GPL-2.0-only
 *
 * Author: Sebastien Vincent <vincent@clarinet.u-strasbg.fr>
 *         David Gross <gdavid.devel@gmail.com>
 *         Mehdi Benamor <benamor.mehdi@ensi.rnu.tn>
 *         Tommaso Pecorella <tommaso.pecorella@unifi.it>
 */

#include "icmpv6-l4-protocol.h"

#include "ipv4-interface.h"
#include "ipv6-interface.h"
#include "ipv6-l3-protocol.h"
#include "ipv6-route.h"
#include "ipv6-routing-protocol.h"

#include "ns3/assert.h"
#include "ns3/boolean.h"
#include "ns3/double.h"
#include "ns3/integer.h"
#include "ns3/log.h"
#include "ns3/node.h"
#include "ns3/packet.h"
#include "ns3/pointer.h"
#include "ns3/string.h"
#include "ns3/uinteger.h"

namespace ns3
{

NS_LOG_COMPONENT_DEFINE("Icmpv6L4Protocol");

NS_OBJECT_ENSURE_REGISTERED(Icmpv6L4Protocol);

const uint8_t Icmpv6L4Protocol::PROT_NUMBER = 58;

// const uint8_t Icmpv6L4Protocol::MAX_INITIAL_RTR_ADVERT_INTERVAL = 16; // max initial RA initial
// interval. const uint8_t Icmpv6L4Protocol::MAX_INITIAL_RTR_ADVERTISEMENTS = 3;   // max initial RA
// transmission. const uint8_t Icmpv6L4Protocol::MAX_FINAL_RTR_ADVERTISEMENTS = 3;     // max final
// RA transmission. const uint8_t Icmpv6L4Protocol::MIN_DELAY_BETWEEN_RAS = 3;            // min
// delay between RA. const uint32_t Icmpv6L4Protocol::MAX_RA_DELAY_TIME = 500;             //
// millisecond - max delay between RA.

// const uint8_t Icmpv6L4Protocol::MAX_RTR_SOLICITATION_DELAY = 1;       // max RS delay.
// const uint8_t Icmpv6L4Protocol::RTR_SOLICITATION_INTERVAL = 4;        // RS interval.
// const uint8_t Icmpv6L4Protocol::MAX_RTR_SOLICITATIONS = 3;            // max RS transmission.

// const uint8_t Icmpv6L4Protocol::MAX_ANYCAST_DELAY_TIME = 1;           // max anycast delay.
// const uint8_t Icmpv6L4Protocol::MAX_NEIGHBOR_ADVERTISEMENT = 3;       // max NA transmission.

// const double Icmpv6L4Protocol::MIN_RANDOM_FACTOR = 0.5;               // min random factor.
// const double Icmpv6L4Protocol::MAX_RANDOM_FACTOR = 1.5;               // max random factor.

TypeId
Icmpv6L4Protocol::GetTypeId()
{
    static TypeId tid =
        TypeId("ns3::Icmpv6L4Protocol")
            .SetParent<IpL4Protocol>()
            .SetGroupName("Internet")
            .AddConstructor<Icmpv6L4Protocol>()
            .AddAttribute("DAD",
                          "Always do DAD check.",
                          BooleanValue(true),
                          MakeBooleanAccessor(&Icmpv6L4Protocol::m_alwaysDad),
                          MakeBooleanChecker())
            .AddAttribute(
                "SolicitationJitter",
                "The jitter in ms a node is allowed to wait before sending any solicitation. Some "
                "jitter aims to prevent collisions. By default, the model will wait for a duration "
                "in ms defined by a uniform random-variable between 0 and SolicitationJitter",
                StringValue("ns3::UniformRandomVariable[Min=0.0|Max=10.0]"),
                MakePointerAccessor(&Icmpv6L4Protocol::m_solicitationJitter),
                MakePointerChecker<RandomVariableStream>())
            .AddAttribute("MaxMulticastSolicit",
                          "Neighbor Discovery node constants: max multicast solicitations.",
                          IntegerValue(3),
                          MakeIntegerAccessor(&Icmpv6L4Protocol::m_maxMulticastSolicit),
                          MakeIntegerChecker<uint8_t>())
            .AddAttribute("MaxUnicastSolicit",
                          "Neighbor Discovery node constants: max unicast solicitations.",
                          IntegerValue(3),
                          MakeIntegerAccessor(&Icmpv6L4Protocol::m_maxUnicastSolicit),
                          MakeIntegerChecker<uint8_t>())
            .AddAttribute("ReachableTime",
                          "Neighbor Discovery node constants: reachable time.",
                          TimeValue(Seconds(30)),
                          MakeTimeAccessor(&Icmpv6L4Protocol::m_reachableTime),
                          MakeTimeChecker())
            .AddAttribute("RetransmissionTime",
                          "Neighbor Discovery node constants: retransmission timer.",
                          TimeValue(Seconds(1)),
                          MakeTimeAccessor(&Icmpv6L4Protocol::m_retransmissionTime),
                          MakeTimeChecker())
            .AddAttribute("DelayFirstProbe",
                          "Neighbor Discovery node constants: delay for the first probe.",
                          TimeValue(Seconds(5)),
                          MakeTimeAccessor(&Icmpv6L4Protocol::m_delayFirstProbe),
                          MakeTimeChecker())
            .AddAttribute("DadTimeout",
                          "Duplicate Address Detection (DAD) timeout",
                          TimeValue(Seconds(1)),
                          MakeTimeAccessor(&Icmpv6L4Protocol::m_dadTimeout),
                          MakeTimeChecker())
            .AddAttribute("RsRetransmissionJitter",
                          "Multicast RS retransmission randomization quantity",
                          StringValue("ns3::UniformRandomVariable[Min=-0.1|Max=0.1]"),
                          MakePointerAccessor(&Icmpv6L4Protocol::m_rsRetransmissionJitter),
                          MakePointerChecker<RandomVariableStream>())
            .AddAttribute("RsInitialRetransmissionTime",
                          "Multicast RS initial retransmission time.",
                          TimeValue(Seconds(4)),
                          MakeTimeAccessor(&Icmpv6L4Protocol::m_rsInitialRetransmissionTime),
                          MakeTimeChecker())
            .AddAttribute("RsMaxRetransmissionTime",
                          "Multicast RS maximum retransmission time (0 means unbound).",
                          TimeValue(Seconds(3600)),
                          MakeTimeAccessor(&Icmpv6L4Protocol::m_rsMaxRetransmissionTime),
                          MakeTimeChecker())
            .AddAttribute(
                "RsMaxRetransmissionCount",
                "Multicast RS maximum retransmission count (0 means unbound). "
                "Note: RFC 7559 suggest a zero value (infinite). The default is 4 to avoid "
                "non-terminating simulations.",
                UintegerValue(4),
                MakeUintegerAccessor(&Icmpv6L4Protocol::m_rsMaxRetransmissionCount),
                MakeUintegerChecker<uint32_t>())
            .AddAttribute("RsMaxRetransmissionDuration",
                          "Multicast RS maximum retransmission duration (0 means unbound).",
                          TimeValue(Seconds(0)),
                          MakeTimeAccessor(&Icmpv6L4Protocol::m_rsMaxRetransmissionDuration),
                          MakeTimeChecker())
            .AddTraceSource("DadFailure",
                            "Duplicate Address detected during DAD, the address is now INVALID",
                            MakeTraceSourceAccessor(&Icmpv6L4Protocol::m_dadFailureAddressTrace),
                            "ns3::Ipv6Address::TracedCallback")
            .AddTraceSource(
                "DadSuccess",
                "Duplicate Address not detected during DAD, the address is now PREFERRED",
                MakeTraceSourceAccessor(&Icmpv6L4Protocol::m_dadSuccessAddressTrace),
                "ns3::Ipv6Address::TracedCallback");
    return tid;
}

Icmpv6L4Protocol::Icmpv6L4Protocol()
    : m_node(nullptr)
{
    NS_LOG_FUNCTION(this);
}

Icmpv6L4Protocol::~Icmpv6L4Protocol()
{
    NS_LOG_FUNCTION(this);
}

void
Icmpv6L4Protocol::DoDispose()
{
    NS_LOG_FUNCTION(this);
    for (auto it = m_cacheList.begin(); it != m_cacheList.end(); it++)
    {
        Ptr<NdiscCache> cache = *it;
        cache->Dispose();
        cache = nullptr;
    }
    m_cacheList.clear();
    m_downTarget.Nullify();
    m_startDhcpv6.Nullify();

    m_node = nullptr;
    IpL4Protocol::DoDispose();
}

int64_t
Icmpv6L4Protocol::AssignStreams(int64_t stream)
{
    NS_LOG_FUNCTION(this << stream);
    m_solicitationJitter->SetStream(stream);
    m_rsRetransmissionJitter->SetStream(stream + 1);
    return 2;
}

void
Icmpv6L4Protocol::NotifyNewAggregate()
{
    NS_LOG_FUNCTION(this);
    if (!m_node)
    {
        Ptr<Node> node = this->GetObject<Node>();
        if (node)
        {
            Ptr<Ipv6> ipv6 = this->GetObject<Ipv6>();
            if (ipv6 && m_downTarget.IsNull())
            {
                SetNode(node);
                ipv6->Insert(this);
                SetDownTarget6(MakeCallback(&Ipv6::Send, ipv6));
            }
        }
    }
    IpL4Protocol::NotifyNewAggregate();
}

void
Icmpv6L4Protocol::SetNode(Ptr<Node> node)
{
    NS_LOG_FUNCTION(this << node);
    m_node = node;
}

Ptr<Node>
Icmpv6L4Protocol::GetNode()
{
    NS_LOG_FUNCTION(this);
    return m_node;
}

uint16_t
Icmpv6L4Protocol::GetStaticProtocolNumber()
{
    NS_LOG_FUNCTION_NOARGS();
    return PROT_NUMBER;
}

int
Icmpv6L4Protocol::GetProtocolNumber() const
{
    NS_LOG_FUNCTION(this);
    return PROT_NUMBER;
}

int
Icmpv6L4Protocol::GetVersion() const
{
    NS_LOG_FUNCTION(this);
    return 1;
}

bool
Icmpv6L4Protocol::IsAlwaysDad() const
{
    NS_LOG_FUNCTION(this);
    return m_alwaysDad;
}

void
Icmpv6L4Protocol::DoDAD(Ipv6Address target, Ptr<Ipv6Interface> interface)
{
    NS_LOG_FUNCTION(this << target << interface);
    Ptr<Ipv6L3Protocol> ipv6 = m_node->GetObject<Ipv6L3Protocol>();

    NS_ASSERT(ipv6);

    if (!m_alwaysDad)
    {
        return;
    }

    /** @todo disable multicast loopback to prevent NS probing to be received by the sender */

    NdiscCache::Ipv6PayloadHeaderPair p = ForgeNS("::",
                                                  Ipv6Address::MakeSolicitedAddress(target),
                                                  target,
                                                  interface->GetDevice()->GetAddress());

    /* update last packet UID */
    interface->SetNsDadUid(target, p.first->GetUid());
    Simulator::Schedule(MilliSeconds(m_solicitationJitter->GetValue()),
                        &Ipv6Interface::Send,
                        interface,
                        p.first,
                        p.second,
                        Ipv6Address::MakeSolicitedAddress(target));
}

IpL4Protocol::RxStatus
Icmpv6L4Protocol::Receive(Ptr<Packet> packet,
                          const Ipv4Header& header,
                          Ptr<Ipv4Interface> interface)
{
    NS_LOG_FUNCTION(this << packet << header);
    return IpL4Protocol::RX_ENDPOINT_UNREACH;
}

IpL4Protocol::RxStatus
Icmpv6L4Protocol::Receive(Ptr<Packet> packet,
                          const Ipv6Header& header,
                          Ptr<Ipv6Interface> interface)
{
    NS_LOG_FUNCTION(this << packet << header.GetSource() << header.GetDestination() << interface);
    Ptr<Packet> p = packet->Copy();
    Ptr<Ipv6> ipv6 = m_node->GetObject<Ipv6>();

    /* very ugly! try to find something better in the future */
    uint8_t type;
    p->CopyData(&type, sizeof(type));

    switch (type)
    {
    case Icmpv6Header::ICMPV6_ND_ROUTER_SOLICITATION:
        if (ipv6->IsForwarding(ipv6->GetInterfaceForDevice(interface->GetDevice())))
        {
            HandleRS(p, header.GetSource(), header.GetDestination(), interface);
        }
        break;
    case Icmpv6Header::ICMPV6_ND_ROUTER_ADVERTISEMENT:
        if (!ipv6->IsForwarding(ipv6->GetInterfaceForDevice(interface->GetDevice())))
        {
            HandleRA(p, header.GetSource(), header.GetDestination(), interface);
        }
        break;
    case Icmpv6Header::ICMPV6_ND_NEIGHBOR_SOLICITATION:
        HandleNS(p, header.GetSource(), header.GetDestination(), interface);
        break;
    case Icmpv6Header::ICMPV6_ND_NEIGHBOR_ADVERTISEMENT:
        HandleNA(p, header.GetSource(), header.GetDestination(), interface);
        break;
    case Icmpv6Header::ICMPV6_ND_REDIRECTION:
        HandleRedirection(p, header.GetSource(), header.GetDestination(), interface);
        break;
    case Icmpv6Header::ICMPV6_ECHO_REQUEST:
        HandleEchoRequest(p, header.GetSource(), header.GetDestination(), interface);
        break;
    case Icmpv6Header::ICMPV6_ECHO_REPLY:
        // EchoReply does not contain any info about L4
        // so we can not forward it up.
        /// @todo implement request / reply consistency check.
        break;
    case Icmpv6Header::ICMPV6_ERROR_DESTINATION_UNREACHABLE:
        HandleDestinationUnreachable(p, header.GetSource(), header.GetDestination(), interface);
        break;
    case Icmpv6Header::ICMPV6_ERROR_PACKET_TOO_BIG:
        HandlePacketTooBig(p, header.GetSource(), header.GetDestination(), interface);
        break;
    case Icmpv6Header::ICMPV6_ERROR_TIME_EXCEEDED:
        HandleTimeExceeded(p, header.GetSource(), header.GetDestination(), interface);
        break;
    case Icmpv6Header::ICMPV6_ERROR_PARAMETER_ERROR:
        HandleParameterError(p, header.GetSource(), header.GetDestination(), interface);
        break;
    default:
        NS_LOG_LOGIC("Unknown ICMPv6 message type=" << type);
        break;
    }

    return IpL4Protocol::RX_OK;
}

void
Icmpv6L4Protocol::Forward(Ipv6Address source,
                          Icmpv6Header icmp,
                          uint32_t info,
                          Ipv6Header ipHeader,
                          const uint8_t payload[8])
{
    NS_LOG_FUNCTION(this << source << icmp << info << ipHeader << payload);

    Ptr<Ipv6L3Protocol> ipv6 = m_node->GetObject<Ipv6L3Protocol>();

    /// @todo assuming the ICMP is carrying a extensionless IP packet

    uint8_t nextHeader = ipHeader.GetNextHeader();

    if (nextHeader != Icmpv6L4Protocol::PROT_NUMBER)
    {
        Ptr<IpL4Protocol> l4 = ipv6->GetProtocol(nextHeader);
        if (l4)
        {
            l4->ReceiveIcmp(source,
                            ipHeader.GetHopLimit(),
                            icmp.GetType(),
                            icmp.GetCode(),
                            info,
                            ipHeader.GetSource(),
                            ipHeader.GetDestination(),
                            payload);
        }
    }
}

void
Icmpv6L4Protocol::HandleEchoRequest(Ptr<Packet> packet,
                                    const Ipv6Address& src,
                                    const Ipv6Address& dst,
                                    Ptr<Ipv6Interface> interface)
{
    NS_LOG_FUNCTION(this << packet << src << dst << interface);
    Icmpv6Echo request;
    auto buf = new uint8_t[packet->GetSize()];

    packet->RemoveHeader(request);
    /* XXX IPv6 extension: obtain a fresh copy of data otherwise it crash... */
    packet->CopyData(buf, packet->GetSize());
    Ptr<Packet> p = Create<Packet>(buf, packet->GetSize());

    /* if we send message from ff02::* (link-local multicast), we use our link-local address */
    SendEchoReply(dst.IsMulticast() ? interface->GetLinkLocalAddress().GetAddress() : dst,
                  src,
                  request.GetId(),
                  request.GetSeq(),
                  p);
    delete[] buf;
}

void
Icmpv6L4Protocol::HandleRA(Ptr<Packet> packet,
                           const Ipv6Address& src,
                           const Ipv6Address& dst,
                           Ptr<Ipv6Interface> interface)
{
    NS_LOG_FUNCTION(this << packet << src << dst << interface);

    if (m_handleRsTimeoutEvent.IsPending())
    {
        m_handleRsTimeoutEvent.Cancel();
        // We need to update this in case we need to restart RS retransmissions.
        m_rsRetransmissionCount = 0;
    }

    Ptr<Packet> p = packet->Copy();
    Icmpv6RA raHeader;
    Ptr<Ipv6L3Protocol> ipv6 = m_node->GetObject<Ipv6L3Protocol>();
    Icmpv6OptionPrefixInformation prefixHdr;
    Icmpv6OptionMtu mtuHdr;
    Icmpv6OptionLinkLayerAddress llaHdr;
    bool next = true;
    bool hasLla = false;
    bool hasMtu = false;
    Ipv6Address defaultRouter = Ipv6Address::GetZero();

    p->RemoveHeader(raHeader);

    // If 'M' flag is set, we need to start DHCPv6.
    if (raHeader.GetFlagM())
    {
        if (!m_startDhcpv6.IsNull())
        {
            m_startDhcpv6(ipv6->GetInterfaceForDevice(interface->GetDevice()));
        }
    }

    if (raHeader.GetLifeTime())
    {
        defaultRouter = src;
    }

    while (next)
    {
        uint8_t type = 0;
        p->CopyData(&type, sizeof(type));

        switch (type)
        {
        case Icmpv6Header::ICMPV6_OPT_PREFIX:
            p->RemoveHeader(prefixHdr);
            ipv6->AddAutoconfiguredAddress(ipv6->GetInterfaceForDevice(interface->GetDevice()),
                                           prefixHdr.GetPrefix(),
                                           prefixHdr.GetPrefixLength(),
                                           prefixHdr.GetFlags(),
                                           prefixHdr.GetValidTime(),
                                           prefixHdr.GetPreferredTime(),
                                           defaultRouter);
            break;
        case Icmpv6Header::ICMPV6_OPT_MTU:
            /* take in account the first MTU option */
            if (!hasMtu)
            {
                p->RemoveHeader(mtuHdr);
                hasMtu = true;
                /** @todo case of multiple prefix on single interface */
                /* interface->GetDevice ()->SetMtu (m.GetMtu ()); */
            }
            break;
        case Icmpv6Header::ICMPV6_OPT_LINK_LAYER_SOURCE:
            /* take in account the first LLA option */
            if (!hasLla)
            {
                p->RemoveHeader(llaHdr);
                ReceiveLLA(llaHdr, src, dst, interface);
                hasLla = true;
            }
            break;
        default:
            /* unknown option, quit */
            next = false;
        }
    }
}

void
Icmpv6L4Protocol::ReceiveLLA(Icmpv6OptionLinkLayerAddress lla,
                             const Ipv6Address& src,
                             const Ipv6Address& dst,
                             Ptr<Ipv6Interface> interface)
{
    NS_LOG_FUNCTION(this << lla << src << dst << interface);
    NdiscCache::Entry* entry = nullptr;
    Ptr<NdiscCache> cache = FindCache(interface->GetDevice());

    /* check if we have this address in our cache */
    entry = cache->Lookup(src);

    if (!entry)
    {
        entry = cache->Add(src);
        entry->SetRouter(true);
        entry->SetMacAddress(lla.GetAddress());
        entry->MarkReachable();
        entry->StartReachableTimer();
    }
    else
    {
        std::list<NdiscCache::Ipv6PayloadHeaderPair> waiting;
        switch (entry->m_state)
        {
        case NdiscCache::Entry::INCOMPLETE: {
            entry->StopNudTimer();
            // mark it to reachable
            waiting = entry->MarkReachable(lla.GetAddress());
            entry->StartReachableTimer();
            // send out waiting packet
            for (auto it = waiting.begin(); it != waiting.end(); it++)
            {
                cache->GetInterface()->Send(it->first, it->second, src);
            }
            entry->ClearWaitingPacket();
            return;
        }
        case NdiscCache::Entry::STALE:
        case NdiscCache::Entry::DELAY: {
            if (entry->GetMacAddress() != lla.GetAddress())
            {
                entry->SetMacAddress(lla.GetAddress());
                entry->MarkStale();
                entry->SetRouter(true);
            }
            else
            {
                entry->StopNudTimer();
                waiting = entry->MarkReachable(lla.GetAddress());
                entry->StartReachableTimer();
            }
            return;
        }
        case NdiscCache::Entry::PROBE: {
            if (entry->GetMacAddress() != lla.GetAddress())
            {
                entry->SetMacAddress(lla.GetAddress());
                entry->MarkStale();
                entry->SetRouter(true);
            }
            else
            {
                entry->StopNudTimer();
                waiting = entry->MarkReachable(lla.GetAddress());
                for (auto it = waiting.begin(); it != waiting.end(); it++)
                {
                    cache->GetInterface()->Send(it->first, it->second, src);
                }
                entry->StartReachableTimer();
            }
            return;
        }
        case NdiscCache::Entry::REACHABLE: {
            if (entry->GetMacAddress() != lla.GetAddress())
            {
                entry->SetMacAddress(lla.GetAddress());
                entry->MarkStale();
                entry->SetRouter(true);
            }
            entry->StartReachableTimer();
            return;
        }
        case NdiscCache::Entry::PERMANENT:
        case NdiscCache::Entry::STATIC_AUTOGENERATED: {
            if (entry->GetMacAddress() != lla.GetAddress())
            {
                entry->SetMacAddress(lla.GetAddress());
                entry->MarkStale();
                entry->SetRouter(true);
            }
            return;
        }
        }
        return; // Silence compiler warning
    }
}

void
Icmpv6L4Protocol::HandleRS(Ptr<Packet> packet,
                           const Ipv6Address& src,
                           const Ipv6Address& dst,
                           Ptr<Ipv6Interface> interface)
{
    NS_LOG_FUNCTION(this << packet << src << dst << interface);
    Ptr<Ipv6L3Protocol> ipv6 = m_node->GetObject<Ipv6L3Protocol>();
    Icmpv6RS rsHeader;
    packet->RemoveHeader(rsHeader);
    Icmpv6OptionLinkLayerAddress lla(true);
    NdiscCache::Entry* entry = nullptr;
    Ptr<NdiscCache> cache = FindCache(interface->GetDevice());

    if (src != Ipv6Address::GetAny())
    {
        /* XXX search all options following the RS header */
        /* test if the next option is SourceLinkLayerAddress */
        uint8_t type;
        packet->CopyData(&type, sizeof(type));

        if (type != Icmpv6Header::ICMPV6_OPT_LINK_LAYER_SOURCE)
        {
            return;
        }
        packet->RemoveHeader(lla);
        NS_LOG_LOGIC("Cache updated by RS");

        entry = cache->Lookup(src);
        if (!entry)
        {
            entry = cache->Add(src);
            entry->SetRouter(false);
            entry->MarkStale(lla.GetAddress());
        }
        else if (entry->GetMacAddress() != lla.GetAddress())
        {
            entry->MarkStale(lla.GetAddress());
        }
    }
}

void
Icmpv6L4Protocol::HandleNS(Ptr<Packet> packet,
                           const Ipv6Address& src,
                           const Ipv6Address& dst,
                           Ptr<Ipv6Interface> interface)
{
    NS_LOG_FUNCTION(this << packet << src << dst << interface);
    Icmpv6NS nsHeader("::");
    Ipv6InterfaceAddress ifaddr;
    uint32_t nb = interface->GetNAddresses();
    uint32_t i = 0;
    bool found = false;

    packet->RemoveHeader(nsHeader);

    Ipv6Address target = nsHeader.GetIpv6Target();

    for (i = 0; i < nb; i++)
    {
        ifaddr = interface->GetAddress(i);

        if (ifaddr.GetAddress() == target)
        {
            found = true;
            break;
        }
    }

    if (!found)
    {
        NS_LOG_LOGIC("Not a NS for us");
        return;
    }

    if (packet->GetUid() == ifaddr.GetNsDadUid())
    {
        /* don't process our own DAD probe */
        NS_LOG_LOGIC("Hey we receive our DAD probe!");
        return;
    }

    NdiscCache::Entry* entry = nullptr;
    Ptr<NdiscCache> cache = FindCache(interface->GetDevice());
    uint8_t flags = 0;

    /* search all options following the NS header */
    Icmpv6OptionLinkLayerAddress sllaoHdr(true);

    bool next = true;
    bool hasSllao = false;

    while (next)
    {
        uint8_t type;
        packet->CopyData(&type, sizeof(type));

        switch (type)
        {
        case Icmpv6Header::ICMPV6_OPT_LINK_LAYER_SOURCE:
            if (!hasSllao)
            {
                packet->RemoveHeader(sllaoHdr);
                hasSllao = true;
            }
            break;
        default:
            /* unknown option, quit */
            next = false;
        }
        if (packet->GetSize() == 0)
        {
            next = false;
        }
    }

    Address replyMacAddress;

    if (src != Ipv6Address::GetAny())
    {
        entry = cache->Lookup(src);
        if (!entry)
        {
            if (!hasSllao)
            {
                NS_LOG_LOGIC("Icmpv6L4Protocol::HandleNS: NS without SLLAO and we do not have a "
                             "NCE, discarding.");
                return;
            }
            entry = cache->Add(src);
            entry->SetRouter(false);
            entry->MarkStale(sllaoHdr.GetAddress());
            replyMacAddress = sllaoHdr.GetAddress();
        }
        else if (hasSllao && (entry->GetMacAddress() != sllaoHdr.GetAddress()))
        {
            entry->MarkStale(sllaoHdr.GetAddress());
            replyMacAddress = sllaoHdr.GetAddress();
        }
        else
        {
            replyMacAddress = entry->GetMacAddress();
        }

        flags = 3; /* S + O flags */
    }
    else
    {
        /* it's a DAD */
        flags = 1; /* O flag */
        replyMacAddress = interface->GetDevice()->GetMulticast(dst);
    }

    /* send a NA to src */
    Ptr<Ipv6L3Protocol> ipv6 = m_node->GetObject<Ipv6L3Protocol>();

    if (ipv6->IsForwarding(ipv6->GetInterfaceForDevice(interface->GetDevice())))
    {
        flags += 4; /* R flag */
    }

    Address hardwareAddress = interface->GetDevice()->GetAddress();
    NdiscCache::Ipv6PayloadHeaderPair p = ForgeNA(
        target.IsLinkLocal() ? interface->GetLinkLocalAddress().GetAddress() : ifaddr.GetAddress(),
        src.IsAny() ? dst : src, // DAD replies must go to the multicast group it was sent to.
        &hardwareAddress,
        flags);

    // We must bypass the IPv6 layer, as a NA must be sent regardless of the NCE status (and not
    // change it beyond what we did already).
    Ptr<Packet> pkt = p.first;
    pkt->AddHeader(p.second);
    interface->GetDevice()->Send(pkt, replyMacAddress, Ipv6L3Protocol::PROT_NUMBER);
}

NdiscCache::Ipv6PayloadHeaderPair
Icmpv6L4Protocol::ForgeRS(Ipv6Address src, Ipv6Address dst, Address hardwareAddress)
{
    NS_LOG_FUNCTION(this << src << dst << hardwareAddress);
    Ptr<Packet> p = Create<Packet>();
    Ipv6Header ipHeader;
    Icmpv6RS rs;

    NS_LOG_LOGIC("Forge RS (from " << src << " to " << dst << ")");
    // RFC 4861:
    // The link-layer address of the sender MUST NOT be included if the Source Address is the
    // unspecified address. Otherwise, it SHOULD be included on link layers that have addresses.
    if (!src.IsAny())
    {
        Icmpv6OptionLinkLayerAddress llOption(
            true,
            hardwareAddress); /* we give our mac address in response */
        p->AddHeader(llOption);
    }

    rs.CalculatePseudoHeaderChecksum(src, dst, p->GetSize() + rs.GetSerializedSize(), PROT_NUMBER);
    p->AddHeader(rs);

    ipHeader.SetSource(src);
    ipHeader.SetDestination(dst);
    ipHeader.SetNextHeader(PROT_NUMBER);
    ipHeader.SetPayloadLength(p->GetSize());
    ipHeader.SetHopLimit(255);

    return NdiscCache::Ipv6PayloadHeaderPair(p, ipHeader);
}

NdiscCache::Ipv6PayloadHeaderPair
Icmpv6L4Protocol::ForgeEchoRequest(Ipv6Address src,
                                   Ipv6Address dst,
                                   uint16_t id,
                                   uint16_t seq,
                                   Ptr<Packet> data)
{
    NS_LOG_FUNCTION(this << src << dst << id << seq << data);
    Ptr<Packet> p = data->Copy();
    Ipv6Header ipHeader;
    Icmpv6Echo req(true);

    req.SetId(id);
    req.SetSeq(seq);

    req.CalculatePseudoHeaderChecksum(src,
                                      dst,
                                      p->GetSize() + req.GetSerializedSize(),
                                      PROT_NUMBER);
    p->AddHeader(req);

    ipHeader.SetSource(src);
    ipHeader.SetDestination(dst);
    ipHeader.SetNextHeader(PROT_NUMBER);
    ipHeader.SetPayloadLength(p->GetSize());
    ipHeader.SetHopLimit(255);

    return NdiscCache::Ipv6PayloadHeaderPair(p, ipHeader);
}

void
Icmpv6L4Protocol::HandleNA(Ptr<Packet> packet,
                           const Ipv6Address& src,
                           const Ipv6Address& dst,
                           Ptr<Ipv6Interface> interface)
{
    NS_LOG_FUNCTION(this << packet << src << dst << interface);
    Icmpv6NA naHeader;
    Icmpv6OptionLinkLayerAddress lla(true);

    packet->RemoveHeader(naHeader);
    Ipv6Address target = naHeader.GetIpv6Target();

    NdiscCache::Entry* entry = nullptr;
    Ptr<NdiscCache> cache = FindCache(interface->GetDevice());
    std::list<NdiscCache::Ipv6PayloadHeaderPair> waiting;

    /* check if we have something in our cache */
    entry = cache->Lookup(target);

    if (!entry)
    {
        /* ouch!! we might be victim of a DAD */

        Ipv6InterfaceAddress ifaddr;
        bool found = false;
        uint32_t i = 0;
        uint32_t nb = interface->GetNAddresses();

        for (i = 0; i < nb; i++)
        {
            ifaddr = interface->GetAddress(i);
            if (ifaddr.GetAddress() == target)
            {
                found = true;
                break;
            }
        }

        if (found)
        {
            if (ifaddr.GetState() == Ipv6InterfaceAddress::TENTATIVE ||
                ifaddr.GetState() == Ipv6InterfaceAddress::TENTATIVE_OPTIMISTIC)
            {
                m_dadFailureAddressTrace(ifaddr.GetAddress());
                interface->SetState(ifaddr.GetAddress(), Ipv6InterfaceAddress::INVALID);
            }
        }

        /* we have not initiated any communication with the target so... discard the NA */
        return;
    }

    /* XXX search all options following the NA header */
    /* Get LLA */
    uint8_t type;
    packet->CopyData(&type, sizeof(type));

    if (type != Icmpv6Header::ICMPV6_OPT_LINK_LAYER_TARGET)
    {
        return;
    }
    packet->RemoveHeader(lla);

    /* we receive a NA so stop the probe timer or delay timer if any */
    entry->StopNudTimer();
    switch (entry->m_state)
    {
    case NdiscCache::Entry::INCOMPLETE: {
        /* we receive a NA so stop the retransmission timer */
        entry->StopNudTimer();

        if (naHeader.GetFlagS())
        {
            /* mark it to reachable */
            waiting = entry->MarkReachable(lla.GetAddress());
            entry->StartReachableTimer();
            /* send out waiting packet */
            for (auto it = waiting.begin(); it != waiting.end(); it++)
            {
                cache->GetInterface()->Send(it->first, it->second, src);
            }
            entry->ClearWaitingPacket();
        }
        else
        {
            entry->MarkStale(lla.GetAddress());
        }

        if (naHeader.GetFlagR())
        {
            entry->SetRouter(true);
        }
        return;
    }
    case NdiscCache::Entry::REACHABLE: {
        /* if the Flag O is clear and mac address differs from the cache */
        if (!naHeader.GetFlagO() && lla.GetAddress() != entry->GetMacAddress())
        {
            entry->MarkStale();
            return;
        }
        else
        {
            entry->SetMacAddress(lla.GetAddress());
            if (naHeader.GetFlagS())
            {
                entry->StartReachableTimer();
            }
            else if (lla.GetAddress() != entry->GetMacAddress())
            {
                entry->MarkStale();
            }
            entry->SetRouter(naHeader.GetFlagR());
        }
        break;
    }
    case NdiscCache::Entry::STALE:
    case NdiscCache::Entry::DELAY: {
        /* if the Flag O is clear and mac address differs from the cache */
        if (naHeader.GetFlagO() || lla.GetAddress() == entry->GetMacAddress())
        {
            entry->SetMacAddress(lla.GetAddress());
            if (naHeader.GetFlagS())
            {
                entry->MarkReachable(lla.GetAddress());
                entry->StartReachableTimer();
            }
            else if (lla.GetAddress() != entry->GetMacAddress())
            {
                entry->MarkStale();
            }
            entry->SetRouter(naHeader.GetFlagR());
        }
        return;
    }
    case NdiscCache::Entry::PROBE: {
        if (naHeader.GetFlagO() || lla.GetAddress() == entry->GetMacAddress())
        {
            entry->SetMacAddress(lla.GetAddress());
            if (naHeader.GetFlagS())
            {
                waiting = entry->MarkReachable(lla.GetAddress());
                for (auto it = waiting.begin(); it != waiting.end(); it++)
                {
                    cache->GetInterface()->Send(it->first, it->second, src);
                }
                entry->ClearWaitingPacket();
                entry->StartReachableTimer();
            }
            else if (lla.GetAddress() != entry->GetMacAddress())
            {
                entry->MarkStale();
            }
            entry->SetRouter(naHeader.GetFlagR());
        }
        return;
    }
    case NdiscCache::Entry::PERMANENT:
    case NdiscCache::Entry::STATIC_AUTOGENERATED: {
        if (naHeader.GetFlagO() || lla.GetAddress() == entry->GetMacAddress())
        {
            entry->SetMacAddress(lla.GetAddress());
            if (lla.GetAddress() != entry->GetMacAddress())
            {
                entry->MarkStale();
            }
            entry->SetRouter(naHeader.GetFlagR());
        }
        return;
    }
    }
    // Silence compiler warning
}

void
Icmpv6L4Protocol::HandleRedirection(Ptr<Packet> packet,
                                    const Ipv6Address& src,
                                    const Ipv6Address& dst,
                                    Ptr<Ipv6Interface> interface)
{
    NS_LOG_FUNCTION(this << packet << src << dst << interface);
    bool hasLla = false;
    Ptr<Packet> p = packet->Copy();
    Icmpv6OptionLinkLayerAddress llOptionHeader(false);

    Icmpv6Redirection redirectionHeader;
    p->RemoveHeader(redirectionHeader);

    /* little ugly try to find a better way */
    uint8_t type;
    p->CopyData(&type, sizeof(type));
    if (type == Icmpv6Header::ICMPV6_OPT_LINK_LAYER_TARGET)
    {
        hasLla = true;
        p->RemoveHeader(llOptionHeader);
    }

    Icmpv6OptionRedirected redirectedOptionHeader;
    p->RemoveHeader(redirectedOptionHeader);

    Ipv6Address redirTarget = redirectionHeader.GetTarget();
    Ipv6Address redirDestination = redirectionHeader.GetDestination();

    if (hasLla)
    {
        /* update the cache if needed */
        NdiscCache::Entry* entry = nullptr;
        Ptr<NdiscCache> cache = FindCache(interface->GetDevice());

        entry = cache->Lookup(redirTarget);
        if (!entry)
        {
            entry = cache->Add(redirTarget);
            /* destination and target different => necessarily a router */
            entry->SetRouter(redirTarget != redirDestination);
            entry->SetMacAddress(llOptionHeader.GetAddress());
            entry->MarkStale();
        }
        else
        {
            if (entry->IsIncomplete() || entry->GetMacAddress() != llOptionHeader.GetAddress())
            {
                /* update entry to STALE */
                if (entry->GetMacAddress() != llOptionHeader.GetAddress())
                {
                    entry->SetMacAddress(llOptionHeader.GetAddress());
                    entry->MarkStale();
                }
            }
            else
            {
                /* stay unchanged */
            }
        }
    }

    /* add redirection in routing table */
    Ptr<Ipv6> ipv6 = m_node->GetObject<Ipv6>();

    if (redirTarget == redirDestination)
    {
        ipv6->GetRoutingProtocol()->NotifyAddRoute(redirDestination,
                                                   Ipv6Prefix(128),
                                                   Ipv6Address("::"),
                                                   ipv6->GetInterfaceForAddress(dst));
    }
    else
    {
        uint32_t ifIndex = ipv6->GetInterfaceForAddress(dst);
        ipv6->GetRoutingProtocol()->NotifyAddRoute(redirDestination,
                                                   Ipv6Prefix(128),
                                                   redirTarget,
                                                   ifIndex);
    }
}

void
Icmpv6L4Protocol::HandleDestinationUnreachable(Ptr<Packet> p,
                                               const Ipv6Address& src,
                                               const Ipv6Address& dst,
                                               Ptr<Ipv6Interface> interface)
{
    NS_LOG_FUNCTION(this << *p << src << dst << interface);
    Ptr<Packet> pkt = p->Copy();

    Icmpv6DestinationUnreachable unreach;
    pkt->RemoveHeader(unreach);

    Ipv6Header ipHeader;
    if (pkt->GetSize() > ipHeader.GetSerializedSize())
    {
        pkt->RemoveHeader(ipHeader);
        uint8_t payload[8];
        pkt->CopyData(payload, 8);
        Forward(src, unreach, unreach.GetCode(), ipHeader, payload);
    }
}

void
Icmpv6L4Protocol::HandleTimeExceeded(Ptr<Packet> p,
                                     const Ipv6Address& src,
                                     const Ipv6Address& dst,
                                     Ptr<Ipv6Interface> interface)
{
    NS_LOG_FUNCTION(this << *p << src << dst << interface);
    Ptr<Packet> pkt = p->Copy();

    Icmpv6TimeExceeded timeexceeded;
    pkt->RemoveHeader(timeexceeded);

    Ipv6Header ipHeader;
    if (pkt->GetSize() > ipHeader.GetSerializedSize())
    {
        Ipv6Header ipHeader;
        pkt->RemoveHeader(ipHeader);
        uint8_t payload[8];
        pkt->CopyData(payload, 8);
        Forward(src, timeexceeded, timeexceeded.GetCode(), ipHeader, payload);
    }
}

void
Icmpv6L4Protocol::HandlePacketTooBig(Ptr<Packet> p,
                                     const Ipv6Address& src,
                                     const Ipv6Address& dst,
                                     Ptr<Ipv6Interface> interface)
{
    NS_LOG_FUNCTION(this << *p << src << dst << interface);
    Ptr<Packet> pkt = p->Copy();

    Icmpv6TooBig tooBig;
    pkt->RemoveHeader(tooBig);

    Ipv6Header ipHeader;
    if (pkt->GetSize() > ipHeader.GetSerializedSize())
    {
        pkt->RemoveHeader(ipHeader);
        uint8_t payload[8];
        pkt->CopyData(payload, 8);

        Ptr<Ipv6L3Protocol> ipv6 = m_node->GetObject<Ipv6L3Protocol>();
        ipv6->SetPmtu(ipHeader.GetDestination(), tooBig.GetMtu());

        Forward(src, tooBig, tooBig.GetMtu(), ipHeader, payload);
    }
}

void
Icmpv6L4Protocol::HandleParameterError(Ptr<Packet> p,
                                       const Ipv6Address& src,
                                       const Ipv6Address& dst,
                                       Ptr<Ipv6Interface> interface)
{
    NS_LOG_FUNCTION(this << *p << src << dst << interface);
    Ptr<Packet> pkt = p->Copy();

    Icmpv6ParameterError paramErr;
    pkt->RemoveHeader(paramErr);

    Ipv6Header ipHeader;
    if (pkt->GetSize() > ipHeader.GetSerializedSize())
    {
        pkt->RemoveHeader(ipHeader);
        uint8_t payload[8];
        pkt->CopyData(payload, 8);
        Forward(src, paramErr, paramErr.GetCode(), ipHeader, payload);
    }
}

void
Icmpv6L4Protocol::SendMessage(Ptr<Packet> packet, Ipv6Address src, Ipv6Address dst, uint8_t ttl)
{
    NS_LOG_FUNCTION(this << packet << src << dst << (uint32_t)ttl);
    Ptr<Ipv6L3Protocol> ipv6 = m_node->GetObject<Ipv6L3Protocol>();
    SocketIpv6HopLimitTag tag;
    NS_ASSERT(ipv6);

    tag.SetHopLimit(ttl);
    packet->AddPacketTag(tag);
    m_downTarget(packet, src, dst, PROT_NUMBER, nullptr);
}

void
Icmpv6L4Protocol::DelayedSendMessage(Ptr<Packet> packet,
                                     Ipv6Address src,
                                     Ipv6Address dst,
                                     uint8_t ttl)
{
    NS_LOG_FUNCTION(this << packet << src << dst << (uint32_t)ttl);
    SendMessage(packet, src, dst, ttl);
}

void
Icmpv6L4Protocol::SendMessage(Ptr<Packet> packet,
                              Ipv6Address dst,
                              Icmpv6Header& icmpv6Hdr,
                              uint8_t ttl)
{
    NS_LOG_FUNCTION(this << packet << dst << icmpv6Hdr << (uint32_t)ttl);
    Ptr<Ipv6L3Protocol> ipv6 = m_node->GetObject<Ipv6L3Protocol>();
    NS_ASSERT(ipv6 && ipv6->GetRoutingProtocol());
    Ipv6Header header;
    SocketIpv6HopLimitTag tag;
    Socket::SocketErrno err;
    Ptr<Ipv6Route> route;
    Ptr<NetDevice> oif(nullptr); // specify non-zero if bound to a source address

    header.SetDestination(dst);
    route = ipv6->GetRoutingProtocol()->RouteOutput(packet, header, oif, err);

    if (route)
    {
        NS_LOG_LOGIC("Route exists");
        tag.SetHopLimit(ttl);
        packet->AddPacketTag(tag);
        Ipv6Address src = route->GetSource();

        icmpv6Hdr.CalculatePseudoHeaderChecksum(src,
                                                dst,
                                                packet->GetSize() + icmpv6Hdr.GetSerializedSize(),
                                                PROT_NUMBER);
        packet->AddHeader(icmpv6Hdr);
        m_downTarget(packet, src, dst, PROT_NUMBER, route);
    }
    else
    {
        NS_LOG_WARN("drop icmp message");
    }
}

void
Icmpv6L4Protocol::SendNA(Ipv6Address src, Ipv6Address dst, Address* hardwareAddress, uint8_t flags)
{
    NS_LOG_FUNCTION(this << src << dst << hardwareAddress << static_cast<uint32_t>(flags));
    Ptr<Packet> p = Create<Packet>();
    Icmpv6NA na;
    Icmpv6OptionLinkLayerAddress llOption(false, *hardwareAddress); /* not a source link layer */

    NS_LOG_LOGIC("Send NA ( from " << src << " to " << dst << " target " << src << ")");
    na.SetIpv6Target(src);

    if (flags & 1)
    {
        na.SetFlagO(true);
    }
    if ((flags & 2) && src != Ipv6Address::GetAny())
    {
        na.SetFlagS(true);
    }
    if (flags & 4)
    {
        na.SetFlagR(true);
    }

    p->AddHeader(llOption);
    na.CalculatePseudoHeaderChecksum(src, dst, p->GetSize() + na.GetSerializedSize(), PROT_NUMBER);
    p->AddHeader(na);

    SendMessage(p, src, dst, 255);
}

void
Icmpv6L4Protocol::SendEchoReply(Ipv6Address src,
                                Ipv6Address dst,
                                uint16_t id,
                                uint16_t seq,
                                Ptr<Packet> data)
{
    NS_LOG_FUNCTION(this << src << dst << id << seq << data);
    Ptr<Packet> p = data->Copy();
    Icmpv6Echo reply(false); /* echo reply */

    reply.SetId(id);
    reply.SetSeq(seq);

    reply.CalculatePseudoHeaderChecksum(src,
                                        dst,
                                        p->GetSize() + reply.GetSerializedSize(),
                                        PROT_NUMBER);
    p->AddHeader(reply);
    SendMessage(p, src, dst, 64);
}

void
Icmpv6L4Protocol::SendNS(Ipv6Address src,
                         Ipv6Address dst,
                         Ipv6Address target,
                         Address hardwareAddress)
{
    NS_LOG_FUNCTION(this << src << dst << target << hardwareAddress);
    Ptr<Packet> p = Create<Packet>();
    /* Ipv6Header ipHeader; */
    Icmpv6NS ns(target);
    Icmpv6OptionLinkLayerAddress llOption(
        true,
        hardwareAddress); /* we give our mac address in response */

    /* if the source is unspec, multicast the NA to all-nodes multicast */
    if (src == Ipv6Address::GetAny())
    {
        dst = Ipv6Address::GetAllNodesMulticast();
    }

    NS_LOG_LOGIC("Send NS ( from " << src << " to " << dst << " target " << target << ")");

    p->AddHeader(llOption);
    ns.CalculatePseudoHeaderChecksum(src, dst, p->GetSize() + ns.GetSerializedSize(), PROT_NUMBER);
    p->AddHeader(ns);
    if (!dst.IsMulticast())
    {
        SendMessage(p, src, dst, 255);
    }
    else
    {
        NS_LOG_LOGIC("Destination is Multicast, using DelayedSendMessage");
        Simulator::Schedule(MilliSeconds(m_solicitationJitter->GetValue()),
                            &Icmpv6L4Protocol::DelayedSendMessage,
                            this,
                            p,
                            src,
                            dst,
                            255);
    }
}

void
Icmpv6L4Protocol::SendRS(Ipv6Address src, Ipv6Address dst, Address hardwareAddress)
{
    NS_LOG_FUNCTION(this << src << dst << hardwareAddress);
    Ptr<Packet> p = Create<Packet>();
    Icmpv6RS rs;

    // RFC 4861:
    // The link-layer address of the sender MUST NOT be included if the Source Address is the
    // unspecified address. Otherwise, it SHOULD be included on link layers that have addresses.
    if (!src.IsAny())
    {
        Icmpv6OptionLinkLayerAddress llOption(true, hardwareAddress);
        p->AddHeader(llOption);
    }

    if (!src.IsAny())
    {
        Ptr<Ipv6L3Protocol> ipv6 = m_node->GetObject<Ipv6L3Protocol>();
        if (ipv6->GetInterfaceForAddress(src) == -1)
        {
            NS_LOG_INFO("Preventing RS from being sent or rescheduled because the source address "
                        << src << " has been removed");
            return;
        }
    }

    NS_LOG_LOGIC("Send RS (from " << src << " to " << dst << ")");

    rs.CalculatePseudoHeaderChecksum(src, dst, p->GetSize() + rs.GetSerializedSize(), PROT_NUMBER);
    p->AddHeader(rs);
    if (!dst.IsMulticast())
    {
        SendMessage(p, src, dst, 255);
    }
    else
    {
        NS_LOG_LOGIC("Destination is Multicast, using DelayedSendMessage");
        Time rsDelay = Time(0);
        Time rsTimeout = Time(0);

        if (m_rsRetransmissionCount == 0)
        {
            // First RS transmission - also add some jitter to desynchronize nodes.
            m_rsInitialRetransmissionTime = Simulator::Now();
            rsTimeout = m_rsInitialRetransmissionTime * (1 + m_rsRetransmissionJitter->GetValue());
            rsDelay = MilliSeconds(m_solicitationJitter->GetValue());
        }
        else
        {
            // Following RS transmission - adding further jitter is unnecessary.
            rsTimeout = m_rsPrevRetransmissionTimeout * (2 + m_rsRetransmissionJitter->GetValue());
            if (rsTimeout > m_rsMaxRetransmissionTime)
            {
                rsTimeout = m_rsMaxRetransmissionTime * (1 + m_rsRetransmissionJitter->GetValue());
            }
        }
        m_rsPrevRetransmissionTimeout = rsTimeout;
        Simulator::Schedule(rsDelay, &Icmpv6L4Protocol::DelayedSendMessage, this, p, src, dst, 255);
        m_handleRsTimeoutEvent = Simulator::Schedule(rsDelay + m_rsPrevRetransmissionTimeout,
                                                     &Icmpv6L4Protocol::HandleRsTimeout,
                                                     this,
                                                     src,
                                                     dst,
                                                     hardwareAddress);
    }
}

void
Icmpv6L4Protocol::HandleRsTimeout(Ipv6Address src, Ipv6Address dst, Address hardwareAddress)
{
    NS_LOG_FUNCTION(this << src << dst << hardwareAddress);

    if (m_rsMaxRetransmissionCount == 0)
    {
        // Unbound number of retransmissions - just add one to signal that we're in retransmission
        // mode.
        m_rsRetransmissionCount = 1;
    }
    else
    {
        m_rsRetransmissionCount++;
        if (m_rsRetransmissionCount > m_rsMaxRetransmissionCount)
        {
            NS_LOG_LOGIC("Maximum number of multicast RS reached, giving up.");
            return;
        }
    }

    if (!m_rsMaxRetransmissionDuration.IsZero() &&
        Simulator::Now() - m_rsInitialRetransmissionTime > m_rsMaxRetransmissionDuration)
    {
        NS_LOG_LOGIC("Maximum RS retransmission time reached, giving up.");
        return;
    }

    SendRS(src, dst, hardwareAddress);
}

void
Icmpv6L4Protocol::SendErrorDestinationUnreachable(Ptr<Packet> malformedPacket,
                                                  Ipv6Address dst,
                                                  uint8_t code)
{
    NS_LOG_FUNCTION(this << malformedPacket << dst << (uint32_t)code);
    uint32_t malformedPacketSize = malformedPacket->GetSize();
    Icmpv6DestinationUnreachable header;
    header.SetCode(code);

    NS_LOG_LOGIC("Send Destination Unreachable ( to " << dst << " code " << (uint32_t)code << " )");

    /* 48 = sizeof IPv6 header + sizeof ICMPv6 error header */
    if (malformedPacketSize <= 1280 - 48)
    {
        header.SetPacket(malformedPacket);
        SendMessage(malformedPacket, dst, header, 255);
    }
    else
    {
        Ptr<Packet> fragment = malformedPacket->CreateFragment(0, 1280 - 48);
        header.SetPacket(fragment);
        SendMessage(fragment, dst, header, 255);
    }
}

void
Icmpv6L4Protocol::SendErrorTooBig(Ptr<Packet> malformedPacket, Ipv6Address dst, uint32_t mtu)
{
    NS_LOG_FUNCTION(this << malformedPacket << dst << mtu);
    uint32_t malformedPacketSize = malformedPacket->GetSize();
    Icmpv6TooBig header;
    header.SetCode(0);
    header.SetMtu(mtu);

    NS_LOG_LOGIC("Send Too Big ( to " << dst << " )");

    /* 48 = sizeof IPv6 header + sizeof ICMPv6 error header */
    if (malformedPacketSize <= 1280 - 48)
    {
        header.SetPacket(malformedPacket);
        SendMessage(malformedPacket, dst, header, 255);
    }
    else
    {
        Ptr<Packet> fragment = malformedPacket->CreateFragment(0, 1280 - 48);
        header.SetPacket(fragment);
        SendMessage(fragment, dst, header, 255);
    }
}

void
Icmpv6L4Protocol::SendErrorTimeExceeded(Ptr<Packet> malformedPacket, Ipv6Address dst, uint8_t code)
{
    NS_LOG_FUNCTION(this << malformedPacket << dst << static_cast<uint32_t>(code));
    uint32_t malformedPacketSize = malformedPacket->GetSize();
    Icmpv6TimeExceeded header;
    header.SetCode(code);

    NS_LOG_LOGIC("Send Time Exceeded ( to " << dst << " code " << (uint32_t)code << " )");

    /* 48 = sizeof IPv6 header + sizeof ICMPv6 error header */
    if (malformedPacketSize <= 1280 - 48)
    {
        header.SetPacket(malformedPacket);
        SendMessage(malformedPacket, dst, header, 255);
    }
    else
    {
        Ptr<Packet> fragment = malformedPacket->CreateFragment(0, 1280 - 48);
        header.SetPacket(fragment);
        SendMessage(fragment, dst, header, 255);
    }
}

void
Icmpv6L4Protocol::SendErrorParameterError(Ptr<Packet> malformedPacket,
                                          Ipv6Address dst,
                                          uint8_t code,
                                          uint32_t ptr)
{
    NS_LOG_FUNCTION(this << malformedPacket << dst << static_cast<uint32_t>(code) << ptr);
    uint32_t malformedPacketSize = malformedPacket->GetSize();
    Icmpv6ParameterError header;
    header.SetCode(code);
    header.SetPtr(ptr);

    NS_LOG_LOGIC("Send Parameter Error ( to " << dst << " code " << (uint32_t)code << " )");

    /* 48 = sizeof IPv6 header + sizeof ICMPv6 error header */
    if (malformedPacketSize <= 1280 - 48)
    {
        header.SetPacket(malformedPacket);
        SendMessage(malformedPacket, dst, header, 255);
    }
    else
    {
        Ptr<Packet> fragment = malformedPacket->CreateFragment(0, 1280 - 48);
        header.SetPacket(fragment);
        SendMessage(fragment, dst, header, 255);
    }
}

void
Icmpv6L4Protocol::SendRedirection(Ptr<Packet> redirectedPacket,
                                  Ipv6Address src,
                                  Ipv6Address dst,
                                  Ipv6Address redirTarget,
                                  Ipv6Address redirDestination,
                                  Address redirHardwareTarget)
{
    NS_LOG_FUNCTION(this << redirectedPacket << dst << redirTarget << redirDestination
                         << redirHardwareTarget);
    uint32_t llaSize = 0;
    Ptr<Packet> p = Create<Packet>();
    uint32_t redirectedPacketSize = redirectedPacket->GetSize();
    Icmpv6OptionLinkLayerAddress llOption(false);

    NS_LOG_LOGIC("Send Redirection ( to " << dst << " target " << redirTarget << " destination "
                                          << redirDestination << " )");

    Icmpv6OptionRedirected redirectedOptionHeader;

    if ((redirectedPacketSize % 8) != 0)
    {
        Ptr<Packet> pad = Create<Packet>(8 - (redirectedPacketSize % 8));
        redirectedPacket->AddAtEnd(pad);
    }

    if (redirHardwareTarget.GetLength())
    {
        llOption.SetAddress(redirHardwareTarget);
        llaSize = llOption.GetSerializedSize();
    }

    /* 56 = sizeof IPv6 header + sizeof ICMPv6 error header + sizeof redirected option */
    if (redirectedPacketSize <= (1280 - 56 - llaSize))
    {
        redirectedOptionHeader.SetPacket(redirectedPacket);
    }
    else
    {
        Ptr<Packet> fragment = redirectedPacket->CreateFragment(0, 1280 - 56 - llaSize);
        redirectedOptionHeader.SetPacket(fragment);
    }

    p->AddHeader(redirectedOptionHeader);

    if (llaSize)
    {
        p->AddHeader(llOption);
    }

    Icmpv6Redirection redirectionHeader;
    redirectionHeader.SetTarget(redirTarget);
    redirectionHeader.SetDestination(redirDestination);
    redirectionHeader.CalculatePseudoHeaderChecksum(src,
                                                    dst,
                                                    p->GetSize() +
                                                        redirectionHeader.GetSerializedSize(),
                                                    PROT_NUMBER);
    p->AddHeader(redirectionHeader);

    SendMessage(p, src, dst, 64);
}

NdiscCache::Ipv6PayloadHeaderPair
Icmpv6L4Protocol::ForgeNA(Ipv6Address src, Ipv6Address dst, Address* hardwareAddress, uint8_t flags)
{
    NS_LOG_FUNCTION(this << src << dst << hardwareAddress << (uint32_t)flags);
    Ptr<Packet> p = Create<Packet>();
    Ipv6Header ipHeader;
    Icmpv6NA na;
    Icmpv6OptionLinkLayerAddress llOption(
        false,
        *hardwareAddress); /* we give our mac address in response */

    NS_LOG_LOGIC("Send NA ( from " << src << " to " << dst << ")");

    /* forge the entire NA packet from IPv6 header to ICMPv6 link-layer option, so that the packet
     * does not pass by Icmpv6L4Protocol::Lookup again */

    p->AddHeader(llOption);
    na.SetIpv6Target(src);

    if (flags & 1)
    {
        na.SetFlagO(true);
    }
    if ((flags & 2) && src != Ipv6Address::GetAny())
    {
        na.SetFlagS(true);
    }
    if (flags & 4)
    {
        na.SetFlagR(true);
    }

    na.CalculatePseudoHeaderChecksum(src, dst, p->GetSize() + na.GetSerializedSize(), PROT_NUMBER);
    p->AddHeader(na);

    ipHeader.SetSource(src);
    ipHeader.SetDestination(dst);
    ipHeader.SetNextHeader(PROT_NUMBER);
    ipHeader.SetPayloadLength(p->GetSize());
    ipHeader.SetHopLimit(255);

    return NdiscCache::Ipv6PayloadHeaderPair(p, ipHeader);
}

NdiscCache::Ipv6PayloadHeaderPair
Icmpv6L4Protocol::ForgeNS(Ipv6Address src,
                          Ipv6Address dst,
                          Ipv6Address target,
                          Address hardwareAddress)
{
    NS_LOG_FUNCTION(this << src << dst << target << hardwareAddress);
    Ptr<Packet> p = Create<Packet>();
    Ipv6Header ipHeader;
    Icmpv6NS ns(target);
    Icmpv6OptionLinkLayerAddress llOption(
        true,
        hardwareAddress); /* we give our mac address in response */

    NS_LOG_LOGIC("Send NS ( from " << src << " to " << dst << " target " << target << ")");

    p->AddHeader(llOption);
    ns.CalculatePseudoHeaderChecksum(src, dst, p->GetSize() + ns.GetSerializedSize(), PROT_NUMBER);
    p->AddHeader(ns);

    ipHeader.SetSource(src);
    ipHeader.SetDestination(dst);
    ipHeader.SetNextHeader(PROT_NUMBER);
    ipHeader.SetPayloadLength(p->GetSize());
    ipHeader.SetHopLimit(255);

    return NdiscCache::Ipv6PayloadHeaderPair(p, ipHeader);
}

Ptr<NdiscCache>
Icmpv6L4Protocol::FindCache(Ptr<NetDevice> device)
{
    NS_LOG_FUNCTION(this << device);

    for (auto i = m_cacheList.begin(); i != m_cacheList.end(); i++)
    {
        if ((*i)->GetDevice() == device)
        {
            return *i;
        }
    }

    NS_ASSERT_MSG(false, "Icmpv6L4Protocol can not find a NDIS Cache for device " << device);
    /* quiet compiler */
    return nullptr;
}

Ptr<NdiscCache>
Icmpv6L4Protocol::CreateCache(Ptr<NetDevice> device, Ptr<Ipv6Interface> interface)
{
    NS_LOG_FUNCTION(this << device << interface);

    Ptr<NdiscCache> cache = CreateObject<NdiscCache>();

    cache->SetDevice(device, interface, this);
    device->AddLinkChangeCallback(MakeCallback(&NdiscCache::Flush, cache));
    m_cacheList.push_back(cache);
    return cache;
}

bool
Icmpv6L4Protocol::Lookup(Ipv6Address dst,
                         Ptr<NetDevice> device,
                         Ptr<NdiscCache> cache,
                         Address* hardwareDestination)
{
    NS_LOG_FUNCTION(this << dst << device << cache << hardwareDestination);

    if (!cache)
    {
        /* try to find the cache */
        cache = FindCache(device);
    }
    if (cache)
    {
        NdiscCache::Entry* entry = cache->Lookup(dst);
        if (entry)
        {
            if (entry->IsReachable() || entry->IsDelay() || entry->IsPermanent() ||
                entry->IsAutoGenerated())
            {
                *hardwareDestination = entry->GetMacAddress();
                return true;
            }
            else if (entry->IsStale())
            {
                entry->StartDelayTimer();
                entry->MarkDelay();
                *hardwareDestination = entry->GetMacAddress();
                return true;
            }
        }
    }
    return false;
}

bool
Icmpv6L4Protocol::Lookup(Ptr<Packet> p,
                         const Ipv6Header& ipHeader,
                         Ipv6Address dst,
                         Ptr<NetDevice> device,
                         Ptr<NdiscCache> cache,
                         Address* hardwareDestination)
{
    NS_LOG_FUNCTION(this << p << ipHeader << dst << device << cache << hardwareDestination);

    if (!cache)
    {
        /* try to find the cache */
        cache = FindCache(device);
    }
    if (!cache)
    {
        return false;
    }

    NdiscCache::Entry* entry = cache->Lookup(dst);
    if (entry)
    {
        if (entry->IsReachable() || entry->IsDelay() || entry->IsPermanent() ||
            entry->IsAutoGenerated())
        {
            /* XXX check reachability time */
            /* send packet */
            *hardwareDestination = entry->GetMacAddress();
            return true;
        }
        else if (entry->IsStale())
        {
            /* start delay timer */
            entry->StartDelayTimer();
            entry->MarkDelay();
            *hardwareDestination = entry->GetMacAddress();
            return true;
        }
        else /* INCOMPLETE or PROBE */
        {
            /* queue packet */
            entry->AddWaitingPacket(NdiscCache::Ipv6PayloadHeaderPair(p, ipHeader));
            return false;
        }
    }
    else
    {
        /* we contact this node for the first time
         * add it to the cache and send an NS
         */
        Ipv6Address addr;
        NdiscCache::Entry* entry = cache->Add(dst);
        entry->MarkIncomplete(NdiscCache::Ipv6PayloadHeaderPair(p, ipHeader));
        entry->SetRouter(false);

        if (dst.IsLinkLocal())
        {
            addr = cache->GetInterface()->GetLinkLocalAddress().GetAddress();
        }
        else if (cache->GetInterface()->GetNAddresses() ==
                 1) /* an interface have at least one address (link-local) */
        {
            /* try to resolve global address without having global address so return! */
            cache->Remove(entry);
            return false;
        }
        else
        {
            /* find source address that match destination */
            addr = cache->GetInterface()->GetAddressMatchingDestination(dst).GetAddress();
        }

        SendNS(addr, Ipv6Address::MakeSolicitedAddress(dst), dst, cache->GetDevice()->GetAddress());

        /* start retransmit timer */
        entry->StartRetransmitTimer();
        return false;
    }

    return false;
}

void
Icmpv6L4Protocol::FunctionDadTimeout(Ipv6Interface* interface, Ipv6Address addr)
{
    NS_LOG_FUNCTION(this << interface << addr);

    Ipv6InterfaceAddress ifaddr;
    bool found = false;
    uint32_t i = 0;
    uint32_t nb = interface->GetNAddresses();

    for (i = 0; i < nb; i++)
    {
        ifaddr = interface->GetAddress(i);

        if (ifaddr.GetAddress() == addr)
        {
            found = true;
            break;
        }
    }

    if (!found)
    {
        NS_LOG_LOGIC("Can not find the address in the interface.");
    }

    /* for the moment, this function is always called, if we was victim of a DAD the address is
     * INVALID and we do not set it to PREFERRED
     */
    if (found && ifaddr.GetState() != Ipv6InterfaceAddress::INVALID)
    {
        m_dadSuccessAddressTrace(ifaddr.GetAddress());
        interface->SetState(ifaddr.GetAddress(), Ipv6InterfaceAddress::PREFERRED);
        NS_LOG_LOGIC("DAD OK, interface in state PREFERRED");

        /* send an RS if our interface is not forwarding (router) and if address is a link-local
         * ones (because we will send RS with it)
         */
        Ptr<Ipv6> ipv6 = m_node->GetObject<Ipv6>();

        if (!ipv6->IsForwarding(ipv6->GetInterfaceForDevice(interface->GetDevice())) &&
            addr.IsLinkLocal())
        {
            /* \todo Add random delays before sending RS
             * because all nodes start at the same time, there will be many of RS around 1 second of
             * simulation time
             */
            NS_LOG_LOGIC("Scheduled a first Router Solicitation");
            m_rsRetransmissionCount = 0;
            Simulator::Schedule(Seconds(0),
                                &Icmpv6L4Protocol::SendRS,
                                this,
                                ifaddr.GetAddress(),
                                Ipv6Address::GetAllRoutersMulticast(),
                                interface->GetDevice()->GetAddress());
        }
        else
        {
            NS_LOG_LOGIC("Did not schedule a Router Solicitation because the interface is in "
                         "forwarding mode");
        }
    }
}

void
Icmpv6L4Protocol::SetDownTarget(IpL4Protocol::DownTargetCallback callback)
{
    NS_LOG_FUNCTION(this << &callback);
}

void
Icmpv6L4Protocol::SetDownTarget6(IpL4Protocol::DownTargetCallback6 callback)
{
    NS_LOG_FUNCTION(this << &callback);
    m_downTarget = callback;
}

IpL4Protocol::DownTargetCallback
Icmpv6L4Protocol::GetDownTarget() const
{
    NS_LOG_FUNCTION(this);
    return IpL4Protocol::DownTargetCallback();
}

IpL4Protocol::DownTargetCallback6
Icmpv6L4Protocol::GetDownTarget6() const
{
    NS_LOG_FUNCTION(this);
    return m_downTarget;
}

uint8_t
Icmpv6L4Protocol::GetMaxMulticastSolicit() const
{
    return m_maxMulticastSolicit;
}

uint8_t
Icmpv6L4Protocol::GetMaxUnicastSolicit() const
{
    return m_maxUnicastSolicit;
}

Time
Icmpv6L4Protocol::GetReachableTime() const
{
    return m_reachableTime;
}

Time
Icmpv6L4Protocol::GetRetransmissionTime() const
{
    return m_retransmissionTime;
}

Time
Icmpv6L4Protocol::GetDelayFirstProbe() const
{
    return m_delayFirstProbe;
}

Time
Icmpv6L4Protocol::GetDadTimeout() const
{
    return m_dadTimeout;
}

} /* namespace ns3 */
