/*
 * Copyright (c)2019 ZeroTier, Inc.
 *
 * Use of this software is governed by the Business Source License included
 * in the LICENSE.TXT file in the project's root directory.
 *
 * Change Date: 2026-01-01
 *
 * On the date above, in accordance with the Business Source License, use
 * of this software will be governed by version 2.0 of the Apache License.
 */
/****/

#include "Multicaster.hpp"

#include "CertificateOfMembership.hpp"
#include "Constants.hpp"
#include "Network.hpp"
#include "Node.hpp"
#include "Packet.hpp"
#include "Peer.hpp"
#include "RuntimeEnvironment.hpp"
#include "Switch.hpp"
#include "Topology.hpp"

#include <algorithm>

namespace ZeroTier {

Multicaster::Multicaster(const RuntimeEnvironment* renv) : RR(renv), _groups(32)
{
}

Multicaster::~Multicaster()
{
}

void Multicaster::addMultiple(void* tPtr, int64_t now, uint64_t nwid, const MulticastGroup& mg, const void* addresses, unsigned int count, unsigned int totalKnown)
{
    const unsigned char* p = (const unsigned char*)addresses;
    const unsigned char* e = p + (5 * count);
    Mutex::Lock _l(_groups_m);
    MulticastGroupStatus& gs = _groups[Multicaster::Key(nwid, mg)];
    while (p != e) {
        _add(tPtr, now, nwid, mg, gs, Address(p, 5));
        p += 5;
    }
}

void Multicaster::remove(uint64_t nwid, const MulticastGroup& mg, const Address& member)
{
    Mutex::Lock _l(_groups_m);
    MulticastGroupStatus* s = _groups.get(Multicaster::Key(nwid, mg));
    if (s) {
        for (std::vector<MulticastGroupMember>::iterator m(s->members.begin()); m != s->members.end(); ++m) {
            if (m->address == member) {
                s->members.erase(m);
                break;
            }
        }
    }
}

unsigned int Multicaster::gather(const Address& queryingPeer, uint64_t nwid, const MulticastGroup& mg, Buffer<ZT_PROTO_MAX_PACKET_LENGTH>& appendTo, unsigned int limit) const
{
    unsigned char* p;
    unsigned int added = 0, i, k, rptr, totalKnown = 0;
    uint64_t a, picked[(ZT_PROTO_MAX_PACKET_LENGTH / 5) + 2];

    if (! limit) {
        return 0;
    }
    else if (limit > 0xffff) {
        limit = 0xffff;
    }

    const unsigned int totalAt = appendTo.size();
    appendTo.addSize(4);   // sizeof(uint32_t)
    const unsigned int addedAt = appendTo.size();
    appendTo.addSize(2);   // sizeof(uint16_t)

    {   // Return myself if I am a member of this group
        SharedPtr<Network> network(RR->node->network(nwid));
        if ((network) && (network->subscribedToMulticastGroup(mg, true))) {
            RR->identity.address().appendTo(appendTo);
            ++totalKnown;
            ++added;
        }
    }

    Mutex::Lock _l(_groups_m);

    const MulticastGroupStatus* s = _groups.get(Multicaster::Key(nwid, mg));
    if ((s) && (! s->members.empty())) {
        totalKnown += (unsigned int)s->members.size();

        // Members are returned in random order so that repeated gather queries
        // will return different subsets of a large multicast group.
        k = 0;
        while ((added < limit) && (k < s->members.size()) && ((appendTo.size() + ZT_ADDRESS_LENGTH) <= ZT_PROTO_MAX_PACKET_LENGTH)) {
            rptr = (unsigned int)RR->node->prng();

        restart_member_scan:
            a = s->members[rptr % (unsigned int)s->members.size()].address.toInt();
            for (i = 0; i < k; ++i) {
                if (picked[i] == a) {
                    ++rptr;
                    goto restart_member_scan;
                }
            }
            picked[k++] = a;

            if (queryingPeer.toInt() != a) {   // do not return the peer that is making the request as a result
                p = (unsigned char*)appendTo.appendField(ZT_ADDRESS_LENGTH);
                *(p++) = (unsigned char)((a >> 32) & 0xff);
                *(p++) = (unsigned char)((a >> 24) & 0xff);
                *(p++) = (unsigned char)((a >> 16) & 0xff);
                *(p++) = (unsigned char)((a >> 8) & 0xff);
                *p = (unsigned char)(a & 0xff);
                ++added;
            }
        }
    }

    appendTo.setAt(totalAt, (uint32_t)totalKnown);
    appendTo.setAt(addedAt, (uint16_t)added);

    return added;
}

std::vector<Address> Multicaster::getMembers(uint64_t nwid, const MulticastGroup& mg, unsigned int limit) const
{
    std::vector<Address> ls;
    Mutex::Lock _l(_groups_m);
    const MulticastGroupStatus* s = _groups.get(Multicaster::Key(nwid, mg));
    if (! s) {
        return ls;
    }
    for (std::vector<MulticastGroupMember>::const_reverse_iterator m(s->members.rbegin()); m != s->members.rend(); ++m) {
        ls.push_back(m->address);
        if (ls.size() >= limit) {
            break;
        }
    }
    return ls;
}

void Multicaster::send(void* tPtr, int64_t now, const SharedPtr<Network>& network, const Address& origin, const MulticastGroup& mg, const MAC& src, unsigned int etherType, const void* data, unsigned int len)
{
    unsigned long idxbuf[4096];
    unsigned long* indexes = idxbuf;

    // If we're in hub-and-spoke designated multicast replication mode, see if we
    // have a multicast replicator active. If so, pick the best and send it
    // there. If we are a multicast replicator or if none are alive, fall back
    // to sender replication. Note that bridges do not do this since this would
    // break bridge route learning. This is sort of an edge case limitation of
    // the current protocol and could be fixed, but fixing it would add more
    // complexity than the fix is probably worth. Bridges are generally high
    // bandwidth nodes.
    if (! network->config().isActiveBridge(RR->identity.address())) {
        Address multicastReplicators[ZT_MAX_NETWORK_SPECIALISTS];
        const unsigned int multicastReplicatorCount = network->config().multicastReplicators(multicastReplicators);
        if (multicastReplicatorCount) {
            if (std::find(multicastReplicators, multicastReplicators + multicastReplicatorCount, RR->identity.address()) == (multicastReplicators + multicastReplicatorCount)) {
                SharedPtr<Peer> bestMulticastReplicator;
                SharedPtr<Path> bestMulticastReplicatorPath;
                unsigned int bestMulticastReplicatorLatency = 0xffff;
                for (unsigned int i = 0; i < multicastReplicatorCount; ++i) {
                    const SharedPtr<Peer> p(RR->topology->getPeerNoCache(multicastReplicators[i]));
                    if ((p) && (p->isAlive(now))) {
                        const SharedPtr<Path> pp(p->getAppropriatePath(now, false));
                        if ((pp) && (pp->latency() < bestMulticastReplicatorLatency)) {
                            bestMulticastReplicatorLatency = pp->latency();
                            bestMulticastReplicatorPath = pp;
                            bestMulticastReplicator = p;
                        }
                    }
                }
                if (bestMulticastReplicator) {
                    Packet outp(bestMulticastReplicator->address(), RR->identity.address(), Packet::VERB_MULTICAST_FRAME);
                    outp.append((uint64_t)network->id());
                    outp.append((uint8_t)0x0c);   // includes source MAC | please replicate
                    ((src) ? src : MAC(RR->identity.address(), network->id())).appendTo(outp);
                    mg.mac().appendTo(outp);
                    outp.append((uint32_t)mg.adi());
                    outp.append((uint16_t)etherType);
                    outp.append(data, len);
                    if (! network->config().disableCompression()) {
                        outp.compress();
                    }
                    outp.armor(bestMulticastReplicator->key(), true, false, bestMulticastReplicator->aesKeysIfSupported(), bestMulticastReplicator->identity());
                    Metrics::pkt_multicast_frame_out++;
                    bestMulticastReplicatorPath->send(RR, tPtr, outp.data(), outp.size(), now);
                    return;
                }
            }
        }
    }

    try {
        Mutex::Lock _l(_groups_m);
        MulticastGroupStatus& gs = _groups[Multicaster::Key(network->id(), mg)];

        if (! gs.members.empty()) {
            // Allocate a memory buffer if group is monstrous
            if (gs.members.size() > (sizeof(idxbuf) / sizeof(unsigned long))) {
                indexes = new unsigned long[gs.members.size()];
            }

            // Generate a random permutation of member indexes
            for (unsigned long i = 0; i < gs.members.size(); ++i) {
                indexes[i] = i;
            }
            for (unsigned long i = (unsigned long)gs.members.size() - 1; i > 0; --i) {
                unsigned long j = (unsigned long)RR->node->prng() % (i + 1);
                unsigned long tmp = indexes[j];
                indexes[j] = indexes[i];
                indexes[i] = tmp;
            }
        }

        Address activeBridges[ZT_MAX_NETWORK_SPECIALISTS];
        const unsigned int activeBridgeCount = network->config().activeBridges(activeBridges);
        const unsigned int limit = network->config().multicastLimit;

        if (gs.members.size() >= limit) {
            // Skip queue if we already have enough members to complete the send operation
            OutboundMulticast out;

            out.init(
                RR,
                now,
                network->id(),
                network->config().disableCompression(),
                limit,
                1,   // we'll still gather a little from peers to keep multicast list fresh
                src,
                mg,
                etherType,
                data,
                len);

            unsigned int count = 0;

            for (unsigned int i = 0; i < activeBridgeCount; ++i) {
                if ((activeBridges[i] != RR->identity.address()) && (activeBridges[i] != origin)) {
                    out.sendOnly(RR, tPtr, activeBridges[i]);   // optimization: don't use dedup log if it's a one-pass send
                    if (++count >= limit) {
                        break;
                    }
                }
            }

            unsigned long idx = 0;
            while ((count < limit) && (idx < gs.members.size())) {
                const Address ma(gs.members[indexes[idx++]].address);
                if ((std::find(activeBridges, activeBridges + activeBridgeCount, ma) == (activeBridges + activeBridgeCount)) && (ma != origin)) {
                    out.sendOnly(RR, tPtr, ma);   // optimization: don't use dedup log if it's a one-pass send
                    ++count;
                }
            }
        }
        else {
            while (gs.txQueue.size() >= ZT_TX_QUEUE_SIZE) {
                gs.txQueue.pop_front();
            }

            const unsigned int gatherLimit = (limit - (unsigned int)gs.members.size()) + 1;

            int timerScale = RR->node->lowBandwidthModeEnabled() ? 3 : 1;
            if ((gs.members.empty()) || ((now - gs.lastExplicitGather) >= (ZT_MULTICAST_EXPLICIT_GATHER_DELAY * timerScale))) {
                gs.lastExplicitGather = now;

                Address explicitGatherPeers[16];
                unsigned int numExplicitGatherPeers = 0;

                SharedPtr<Peer> bestRoot(RR->topology->getUpstreamPeer());
                if (bestRoot) {
                    explicitGatherPeers[numExplicitGatherPeers++] = bestRoot->address();
                }

                explicitGatherPeers[numExplicitGatherPeers++] = network->controller();

                Address ac[ZT_MAX_NETWORK_SPECIALISTS];
                const unsigned int accnt = network->config().alwaysContactAddresses(ac);
                unsigned int shuffled[ZT_MAX_NETWORK_SPECIALISTS];
                for (unsigned int i = 0; i < accnt; ++i) {
                    shuffled[i] = i;
                }
                for (unsigned int i = 0, k = accnt >> 1; i < k; ++i) {
                    const uint64_t x = RR->node->prng();
                    const unsigned int x1 = shuffled[(unsigned int)x % accnt];
                    const unsigned int x2 = shuffled[(unsigned int)(x >> 32) % accnt];
                    const unsigned int tmp = shuffled[x1];
                    shuffled[x1] = shuffled[x2];
                    shuffled[x2] = tmp;
                }
                for (unsigned int i = 0; i < accnt; ++i) {
                    explicitGatherPeers[numExplicitGatherPeers++] = ac[shuffled[i]];
                    if (numExplicitGatherPeers == 16) {
                        break;
                    }
                }

                std::vector<Address> anchors(network->config().anchors());
                for (std::vector<Address>::const_iterator a(anchors.begin()); a != anchors.end(); ++a) {
                    if (*a != RR->identity.address()) {
                        explicitGatherPeers[numExplicitGatherPeers++] = *a;
                        if (numExplicitGatherPeers == 16) {
                            break;
                        }
                    }
                }

                for (unsigned int k = 0; k < numExplicitGatherPeers; ++k) {
                    const CertificateOfMembership* com = (network) ? ((network->config().com) ? &(network->config().com) : (const CertificateOfMembership*)0) : (const CertificateOfMembership*)0;
                    Packet outp(explicitGatherPeers[k], RR->identity.address(), Packet::VERB_MULTICAST_GATHER);
                    outp.append(network->id());
                    outp.append((uint8_t)((com) ? 0x01 : 0x00));
                    mg.mac().appendTo(outp);
                    outp.append((uint32_t)mg.adi());
                    outp.append((uint32_t)gatherLimit);
                    if (com) {
                        com->serialize(outp);
                    }
                    RR->node->expectReplyTo(outp.packetId());
                    RR->sw->send(tPtr, outp, true);
                    Metrics::pkt_multicast_gather_out++;
                }
            }

            gs.txQueue.push_back(OutboundMulticast());
            OutboundMulticast& out = gs.txQueue.back();

            out.init(RR, now, network->id(), network->config().disableCompression(), limit, gatherLimit, src, mg, etherType, data, len);

            if (origin) {
                out.logAsSent(origin);
            }

            unsigned int count = 0;

            for (unsigned int i = 0; i < activeBridgeCount; ++i) {
                if (activeBridges[i] != RR->identity.address()) {
                    out.sendAndLog(RR, tPtr, activeBridges[i]);
                    if (++count >= limit) {
                        break;
                    }
                }
            }

            unsigned long idx = 0;
            while ((count < limit) && (idx < gs.members.size())) {
                Address ma(gs.members[indexes[idx++]].address);
                if (std::find(activeBridges, activeBridges + activeBridgeCount, ma) == (activeBridges + activeBridgeCount)) {
                    out.sendAndLog(RR, tPtr, ma);
                    ++count;
                }
            }
        }
    }
    catch (...) {
    }   // this is a sanity check to catch any failures and make sure indexes[] still gets deleted

    // Free allocated memory buffer if any
    if (indexes != idxbuf) {
        delete[] indexes;
    }
}

void Multicaster::clean(int64_t now)
{
    Mutex::Lock _l(_groups_m);
    Multicaster::Key* k = (Multicaster::Key*)0;
    MulticastGroupStatus* s = (MulticastGroupStatus*)0;
    Hashtable<Multicaster::Key, MulticastGroupStatus>::Iterator mm(_groups);
    while (mm.next(k, s)) {
        for (std::list<OutboundMulticast>::iterator tx(s->txQueue.begin()); tx != s->txQueue.end();) {
            if ((tx->expired(now)) || (tx->atLimit())) {
                s->txQueue.erase(tx++);
            }
            else {
                ++tx;
            }
        }

        unsigned long count = 0;
        {
            std::vector<MulticastGroupMember>::iterator reader(s->members.begin());
            std::vector<MulticastGroupMember>::iterator writer(reader);
            while (reader != s->members.end()) {
                if ((now - reader->timestamp) < ZT_MULTICAST_LIKE_EXPIRE) {
                    *writer = *reader;
                    ++writer;
                    ++count;
                }
                ++reader;
            }
        }

        if (count) {
            s->members.resize(count);
        }
        else if (s->txQueue.empty()) {
            _groups.erase(*k);
        }
        else {
            s->members.clear();
        }
    }
}

void Multicaster::_add(void* tPtr, int64_t now, uint64_t nwid, const MulticastGroup& mg, MulticastGroupStatus& gs, const Address& member)
{
    // assumes _groups_m is locked

    // Do not add self -- even if someone else returns it
    if (member == RR->identity.address()) {
        return;
    }

    std::vector<MulticastGroupMember>::iterator m(std::lower_bound(gs.members.begin(), gs.members.end(), member));
    if (m != gs.members.end()) {
        if (m->address == member) {
            m->timestamp = now;
            return;
        }
        gs.members.insert(m, MulticastGroupMember(member, now));
    }
    else {
        gs.members.push_back(MulticastGroupMember(member, now));
    }

    for (std::list<OutboundMulticast>::iterator tx(gs.txQueue.begin()); tx != gs.txQueue.end();) {
        if (tx->atLimit()) {
            gs.txQueue.erase(tx++);
        }
        else {
            tx->sendIfNew(RR, tPtr, member);
            if (tx->atLimit()) {
                gs.txQueue.erase(tx++);
            }
            else {
                ++tx;
            }
        }
    }
}

}   // namespace ZeroTier