ZeroTierOne/root/root.cpp

/*
 * 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: 2023-01-01
 *
 * 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.
 */
/****/

/*
 * This is a high-throughput minimal root server. It implements only
 * those functions of a ZT node that a root must perform and does so
 * using highly efficient multithreaded I/O code. It's only been
 * thoroughly tested on Linux but should also run on BSDs.
 *
 * Root configuration file format (JSON):
 *
 * {
 *   "name": Name of this root for documentation/UI purposes (string)
 *   "port": UDP port (int)
 *   "httpPort": Local HTTP port for basic stats (int)
 *   "relayMaxHops": Max hops (up to 7)
 *   "planetFile": Location of planet file for pre-2.x peers (string)
 *   "statsRoot": If present, path to periodically save stats files (string)
 *   "s_siblings": [
 *     {
 *       "name": Sibling name for UI/documentation purposes (string)
 *       "id": Full public identity of subling (string)
 *       "ip": IP address of sibling (string)
 *       "port": port of subling (for ZeroTier UDP) (int)
 *     }, ...
 *   ]
 * }
 *
 * The only required field is port. If statsRoot is present then files
 * are periodically written there containing the root's current state.
 * It should be a memory filesystem like /dev/shm on Linux as these
 * files are large and rewritten frequently and do not need to be
 * persisted.
 *
 * s_siblings are other root servers that should receive packets to peers
 * that we can't find. This can occur due to e.g. network topology
 * hiccups, IP blockages, etc. s_siblings are used in the order in which
 * they appear with the first alive sibling being used.
 */

#include "../ext/cpp-httplib/httplib.h"
#include "../ext/json/json.hpp"
#include "../node/Address.hpp"
#include "../node/CertificateOfMembership.hpp"
#include "../node/Constants.hpp"
#include "../node/Identity.hpp"
#include "../node/InetAddress.hpp"
#include "../node/Meter.hpp"
#include "../node/MulticastGroup.hpp"
#include "../node/Mutex.hpp"
#include "../node/Packet.hpp"
#include "../node/SharedPtr.hpp"
#include "../node/Utils.hpp"
#include "../node/AES.hpp"
#include "../osdep/BlockingQueue.hpp"
#include "../osdep/OSUtils.hpp"
#include "geoip-html.h"

#include <arpa/inet.h>
#include <atomic>
#include <errno.h>
#include <fcntl.h>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <mutex>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip6.h>
#include <netinet/tcp.h>
#include <netinet/udp.h>
#include <set>
#include <signal.h>
#include <sstream>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <string>
#include <sys/ioctl.h>
#include <sys/select.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/un.h>
#include <thread>
#include <unistd.h>
#include <unordered_map>
#include <unordered_set>
#include <vector>

using namespace ZeroTier;
using json = nlohmann::json;

#ifdef MSG_DONTWAIT
#define SENDTO_FLAGS   MSG_DONTWAIT
#define RECVFROM_FLAGS 0
#else
#define SENDTO_FLAGS   0
#define RECVFROM_FLAGS 0
#endif

//////////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////////

/**
 * RootPeer is a normal peer known to this root
 *
 * This struct must remain memcpy-able. Identity, InetAddress, and
 * AtomicCounter all satisfy this. Take care when adding fields that
 * this remains true.
 */
struct RootPeer {
    ZT_ALWAYS_INLINE RootPeer() : v4s(-1), v6s(-1), lastSend(0), lastReceive(0), lastReceiveV4(0), lastReceiveV6(0), lastEcho(0), lastHello(0), vProto(-1), vMajor(-1), vMinor(-1), vRev(-1), identityValidated(false)
    {
    }
    ZT_ALWAYS_INLINE ~RootPeer()
    {
        Utils::burn(key, sizeof(key));
    }

    Identity id;                // Identity
    uint8_t key[32];            // Shared secret key
    InetAddress ip4, ip6;       // IPv4 and IPv6 addresses
    int v4s, v6s;               // IPv4 and IPv6 sockets
    int64_t lastSend;           // Time of last send (any packet)
    int64_t lastReceive;        // Time of last receive (any packet)
    int64_t lastReceiveV4;      // Time of last IPv4 receive
    int64_t lastReceiveV6;      // Time of last IPv6 receive
    int64_t lastEcho;           // Time of last received ECHO
    int64_t lastHello;          // Time of last received HELLO
    int vProto;                 // Protocol version or -1 if unknown
    int vMajor, vMinor, vRev;   // Peer version or -1,-1,-1 if unknown
    bool identityValidated;     // Identity has been fully verified

    AtomicCounter __refCount;
};

// Hashers for std::unordered_map
struct IdentityHasher {
    ZT_ALWAYS_INLINE std::size_t operator()(const Identity& id) const
    {
        return (std::size_t)id.hashCode();
    }
};
struct AddressHasher {
    ZT_ALWAYS_INLINE std::size_t operator()(const Address& a) const
    {
        return (std::size_t)a.toInt();
    }
};
struct InetAddressHasher {
    ZT_ALWAYS_INLINE std::size_t operator()(const InetAddress& ip) const
    {
        return (std::size_t)ip.hashCode();
    }
};
struct MulticastGroupHasher {
    ZT_ALWAYS_INLINE std::size_t operator()(const MulticastGroup& mg) const
    {
        return (std::size_t)mg.hashCode();
    }
};

// An ordered tuple key representing an introduction of one peer to another
struct RendezvousKey {
    RendezvousKey(const Address& aa, const Address& bb)
    {
        if (aa > bb) {
            a = aa;
            b = bb;
        }
        else {
            a = bb;
            b = aa;
        }
    }
    Address a, b;
    ZT_ALWAYS_INLINE bool operator==(const RendezvousKey& k) const
    {
        return ((a == k.a) && (b == k.b));
    }
    ZT_ALWAYS_INLINE bool operator!=(const RendezvousKey& k) const
    {
        return ((a != k.a) || (b != k.b));
    }
    struct Hasher {
        ZT_ALWAYS_INLINE std::size_t operator()(const RendezvousKey& k) const
        {
            return (std::size_t)(k.a.toInt() ^ k.b.toInt());
        }
    };
};

struct RendezvousStats {
    RendezvousStats() : count(0), ts(0)
    {
    }
    int64_t count;
    int64_t ts;
};

// These fields are not locked as they're only initialized on startup or are atomic
static int64_t s_startTime;              // Time service was started
static std::vector<int> s_ports;         // Ports to bind for UDP traffic
static int s_relayMaxHops = 0;           // Max relay hops
static Identity s_self;                  // My identity (including secret)
static std::atomic_bool s_run;           // Remains true until shutdown is ordered
static json s_config;                    // JSON config file contents
static std::string s_statsRoot;          // Root to write stats, peers, etc.
static std::atomic_bool s_geoInit;       // True if geoIP data is initialized
static std::string s_googleMapsAPIKey;   // Google maps API key for GeoIP /map feature

// These are only modified during GeoIP database load (if enabled) and become static after s_geoInit is set to true.
static std::map<std::pair<uint32_t, uint32_t>, std::pair<float, float> > s_geoIp4;
static std::map<std::pair<std::array<uint64_t, 2>, std::array<uint64_t, 2> >, std::pair<float, float> > s_geoIp6;

// Rate meters for statistical purposes (locks are internal to Meter)
static Meter s_inputRate;
static Meter s_outputRate;
static Meter s_forwardRate;
static Meter s_discardedForwardRate;

// These fields are locked using mutexes below as they're modified during runtime
static std::string s_planet;
static std::vector<SharedPtr<RootPeer> > s_peers;
static std::vector<SharedPtr<RootPeer> > s_peersToValidate;
static std::unordered_map<uint64_t, std::unordered_map<MulticastGroup, std::unordered_map<Address, int64_t, AddressHasher>, MulticastGroupHasher> > s_multicastSubscriptions;
static std::unordered_map<Address, SharedPtr<RootPeer>, AddressHasher> s_peersByVirtAddr;
static std::unordered_map<RendezvousKey, RendezvousStats, RendezvousKey::Hasher> s_rendezvousTracking;

static std::mutex s_planet_l;
static std::mutex s_peers_l;
static std::mutex s_peersToValidate_l;
static std::mutex s_multicastSubscriptions_l;
static std::mutex s_peersByVirtAddr_l;
static std::mutex s_rendezvousTracking_l;

//////////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////////

// Construct GeoIP key for IPv4 IPs
static ZT_ALWAYS_INLINE uint32_t ip4ToH32(const InetAddress& ip)
{
    return Utils::ntoh((uint32_t)(((const struct sockaddr_in*)&ip)->sin_addr.s_addr));
}

// Construct GeoIP key for IPv6 IPs
static ZT_ALWAYS_INLINE std::array<uint64_t, 2> ip6ToH128(const InetAddress& ip)
{
    std::array<uint64_t, 2> i128;
    memcpy(i128.data(), ip.rawIpData(), 16);
    i128[0] = Utils::ntoh(i128[0]);
    i128[1] = Utils::ntoh(i128[1]);
    return i128;
}

#define ZT_PACKET_IDX_EXTENDED_ARMOR_START 19

static void handlePacket(const int sock, const InetAddress* const ip, Packet& pkt)
{
    char ipstr[128], ipstr2[128], astr[32], astr2[32], tmpstr[256];
    const bool fragment = pkt[ZT_PACKET_FRAGMENT_IDX_FRAGMENT_INDICATOR] == ZT_PACKET_FRAGMENT_INDICATOR;
    const Address source(pkt.source());
    const Address dest(pkt.destination());
    const int64_t now = OSUtils::now();

    s_inputRate.log(now, pkt.size());

    if ((! fragment) && (pkt.size() < ZT_PROTO_MIN_PACKET_LENGTH))
        return;

    if ((! fragment) && (! pkt.fragmented()) && (dest == s_self.address())) {
        SharedPtr<RootPeer> peer;

        if ((pkt.cipher() == ZT_PROTO_CIPHER_SUITE__POLY1305_NONE) && pkt.extendedArmor()) {
            if (pkt.size() < (ZT_PROTO_MIN_PACKET_LENGTH + 32)) {
                return;
            }
            uint8_t ephemeralSymmetric[64];
            C25519::agree(s_self.c25519SecretKey(), (const uint8_t *)pkt.data() + (pkt.size() - 32), ephemeralSymmetric);
            SHA512(ephemeralSymmetric, ephemeralSymmetric, 32);

            AES cipher(ephemeralSymmetric);
            uint32_t ctrIv[4];
            memcpy(ctrIv, pkt.data(), 12);
            ctrIv[3] = 0;
            cipher.ctr((const uint8_t *)ctrIv, (const uint8_t *)pkt.data() + ZT_PACKET_IDX_EXTENDED_ARMOR_START, (pkt.size() - ZT_PACKET_IDX_EXTENDED_ARMOR_START) - 32, (uint8_t *)pkt.data() + ZT_PACKET_IDX_EXTENDED_ARMOR_START);

            pkt.setSize(pkt.size() - 32);
        }

        // If this is an un-encrypted HELLO, either learn a new peer or verify
        // that this is a peer we already know.
        if ((pkt.cipher() == ZT_PROTO_CIPHER_SUITE__POLY1305_NONE) && (pkt.verb() == Packet::VERB_HELLO)) {
            Identity id;
            if (id.deserialize(pkt, ZT_PROTO_VERB_HELLO_IDX_IDENTITY)) {
                {
                    std::lock_guard<std::mutex> p_l(s_peersByVirtAddr_l);
                    auto p = s_peersByVirtAddr.find(source);
                    if (p != s_peersByVirtAddr.end()) {
                        peer = p->second;
                    }
                }

                if (peer) {
                    if (unlikely(peer->id != id)) {
                        printf("%s HELLO rejected: identity address collision!" ZT_EOL_S, ip->toString(ipstr));

                        uint8_t key[48];
                        if (s_self.agree(id, key)) {
                            const uint64_t origId = pkt.packetId();
                            pkt.reset(source, s_self.address(), Packet::VERB_ERROR);
                            pkt.append((uint8_t)Packet::VERB_HELLO);
                            pkt.append(origId);
                            pkt.append((uint8_t)Packet::ERROR_IDENTITY_COLLISION);
                            pkt.armor(key, true);
                            sendto(sock, pkt.data(), pkt.size(), SENDTO_FLAGS, (const struct sockaddr*)ip, (socklen_t)((ip->ss_family == AF_INET) ? sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6)));
                        }

                        return;
                    }
                }
                else {
                    peer.set(new RootPeer);
                    peer->identityValidated = false;

                    if (! s_self.agree(id, peer->key)) {
                        printf("%s HELLO rejected: key agreement failed" ZT_EOL_S, ip->toString(ipstr));
                        return;
                    }
                    if (! pkt.dearmor(peer->key)) {
                        printf("%s HELLO rejected: packet authentication failed" ZT_EOL_S, ip->toString(ipstr));
                        return;
                    }
                    if (! pkt.uncompress()) {
                        printf("%s HELLO rejected: decompression failed" ZT_EOL_S, ip->toString(ipstr));
                        return;
                    }

                    peer->id = id;
                    peer->lastReceive = now;

                    {
                        std::lock_guard<std::mutex> pbv_l(s_peersByVirtAddr_l);
                        s_peersByVirtAddr[id.address()] = peer;
                    }
                    {
                        std::lock_guard<std::mutex> pl(s_peers_l);
                        s_peers.emplace_back(peer);
                    }
                    {
                        std::lock_guard<std::mutex> pv(s_peersToValidate_l);
                        s_peersToValidate.emplace_back(peer);
                    }
                }
            }
        }

        if (! peer) {
            {
                std::lock_guard<std::mutex> pbv_l(s_peersByVirtAddr_l);
                auto p = s_peersByVirtAddr.find(source);
                if (p != s_peersByVirtAddr.end()) {
                    peer = p->second;
                }
            }
            if (peer) {
                if (! pkt.dearmor(peer->key)) {
                    printf("%s HELLO rejected: packet authentication failed" ZT_EOL_S, ip->toString(ipstr));
                    return;
                }
                if (! pkt.uncompress()) {
                    printf("%s packet rejected: decompression failed" ZT_EOL_S, ip->toString(ipstr));
                    return;
                }
            }
            else {
                return;
            }
        }

        const int64_t now = OSUtils::now();

        if (ip->isV4()) {
            peer->ip4 = ip;
            peer->v4s = sock;
            peer->lastReceiveV4 = now;
            if ((now - peer->lastReceiveV6) > ZT_PEER_ACTIVITY_TIMEOUT)
                peer->v6s = -1;
        }
        else if (ip->isV6()) {
            peer->ip6 = ip;
            peer->v6s = sock;
            peer->lastReceiveV6 = now;
            if ((now - peer->lastReceiveV4) > ZT_PEER_ACTIVITY_TIMEOUT)
                peer->v4s = -1;
        }
        peer->lastReceive = now;

        switch (pkt.verb()) {
            case Packet::VERB_HELLO:
                try {
                    if ((now - peer->lastHello) > 250) {
                        peer->lastHello = now;

                        peer->vProto = (int)pkt[ZT_PROTO_VERB_HELLO_IDX_PROTOCOL_VERSION];
                        peer->vMajor = (int)pkt[ZT_PROTO_VERB_HELLO_IDX_MAJOR_VERSION];
                        peer->vMinor = (int)pkt[ZT_PROTO_VERB_HELLO_IDX_MINOR_VERSION];
                        peer->vRev = (int)pkt.template at<uint16_t>(ZT_PROTO_VERB_HELLO_IDX_REVISION);
                        const uint64_t origId = pkt.packetId();
                        const uint64_t ts = pkt.template at<uint64_t>(ZT_PROTO_VERB_HELLO_IDX_TIMESTAMP);

                        pkt.reset(source, s_self.address(), Packet::VERB_OK);
                        pkt.append((uint8_t)Packet::VERB_HELLO);
                        pkt.append(origId);
                        pkt.append(ts);
                        pkt.append((uint8_t)ZT_PROTO_VERSION);
                        pkt.append((uint8_t)0);
                        pkt.append((uint8_t)0);
                        pkt.append((uint16_t)0);
                        ip->serialize(pkt);
                        if (peer->vProto < 20) {   // send planet file for pre-2.x peers
                            std::lock_guard<std::mutex> pl(s_planet_l);
                            if (s_planet.length() > 0) {
                                pkt.append((uint16_t)s_planet.size());
                                pkt.append((const uint8_t*)s_planet.data(), s_planet.size());
                            }
                        }
                        pkt.armor(peer->key, true);
                        sendto(sock, pkt.data(), pkt.size(), SENDTO_FLAGS, (const struct sockaddr*)ip, (socklen_t)((ip->ss_family == AF_INET) ? sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6)));

                        s_outputRate.log(now, pkt.size());
                        peer->lastSend = now;
                    }
                }
                catch (...) {
                    printf("* unexpected exception handling HELLO from %s" ZT_EOL_S, ip->toString(ipstr));
                }
                break;

            case Packet::VERB_ECHO:
                try {
                    if ((now - peer->lastEcho) > 500) {
                        peer->lastEcho = now;

                        Packet outp(source, s_self.address(), Packet::VERB_OK);
                        outp.append((uint8_t)Packet::VERB_ECHO);
                        outp.append(pkt.packetId());
                        outp.append(((const uint8_t*)pkt.data()) + ZT_PACKET_IDX_PAYLOAD, pkt.size() - ZT_PACKET_IDX_PAYLOAD);
                        outp.compress();
                        outp.armor(peer->key, true);
                        sendto(sock, outp.data(), outp.size(), SENDTO_FLAGS, (const struct sockaddr*)ip, (socklen_t)((ip->ss_family == AF_INET) ? sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6)));

                        s_outputRate.log(now, outp.size());
                        peer->lastSend = now;
                    }
                }
                catch (...) {
                    printf("* unexpected exception handling ECHO from %s" ZT_EOL_S, ip->toString(ipstr));
                }

            case Packet::VERB_WHOIS:
                try {
                    std::vector<SharedPtr<RootPeer> > results;
                    results.reserve(4);
                    {
                        std::lock_guard<std::mutex> l(s_peersByVirtAddr_l);
                        for (unsigned int ptr = ZT_PACKET_IDX_PAYLOAD; (ptr + ZT_ADDRESS_LENGTH) <= pkt.size(); ptr += ZT_ADDRESS_LENGTH) {
                            auto p = s_peersByVirtAddr.find(Address(pkt.field(ptr, ZT_ADDRESS_LENGTH), ZT_ADDRESS_LENGTH));
                            if (p != s_peersByVirtAddr.end()) {
                                results.push_back(p->second);
                            }
                        }
                    }

                    if (! results.empty()) {
                        const uint64_t origId = pkt.packetId();
                        pkt.reset(source, s_self.address(), Packet::VERB_OK);
                        pkt.append((uint8_t)Packet::VERB_WHOIS);
                        pkt.append(origId);
                        for (auto p = results.begin(); p != results.end(); ++p)
                            (*p)->id.serialize(pkt, false);
                        pkt.armor(peer->key, true);
                        sendto(sock, pkt.data(), pkt.size(), SENDTO_FLAGS, (const struct sockaddr*)ip, (socklen_t)((ip->ss_family == AF_INET) ? sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6)));

                        s_outputRate.log(now, pkt.size());
                        peer->lastSend = now;
                    }
                }
                catch (...) {
                    printf("* unexpected exception handling ECHO from %s" ZT_EOL_S, ip->toString(ipstr));
                }

            case Packet::VERB_MULTICAST_LIKE:
                try {
                    std::lock_guard<std::mutex> l(s_multicastSubscriptions_l);
                    for (unsigned int ptr = ZT_PACKET_IDX_PAYLOAD; (ptr + 18) <= pkt.size(); ptr += 18) {
                        const uint64_t nwid = pkt.template at<uint64_t>(ptr);
                        const MulticastGroup mg(MAC(pkt.field(ptr + 8, 6), 6), pkt.template at<uint32_t>(ptr + 14));
                        s_multicastSubscriptions[nwid][mg][source] = now;
                    }
                }
                catch (...) {
                    printf("* unexpected exception handling MULTICAST_LIKE from %s" ZT_EOL_S, ip->toString(ipstr));
                }
                break;

            case Packet::VERB_MULTICAST_GATHER:
                try {
                    const uint64_t nwid = pkt.template at<uint64_t>(ZT_PROTO_VERB_MULTICAST_GATHER_IDX_NETWORK_ID);
                    // const unsigned int flags = pkt[ZT_PROTO_VERB_MULTICAST_GATHER_IDX_FLAGS];
                    const MulticastGroup mg(MAC(pkt.field(ZT_PROTO_VERB_MULTICAST_GATHER_IDX_MAC, 6), 6), pkt.template at<uint32_t>(ZT_PROTO_VERB_MULTICAST_GATHER_IDX_ADI));
                    unsigned int gatherLimit = pkt.template at<uint32_t>(ZT_PROTO_VERB_MULTICAST_GATHER_IDX_GATHER_LIMIT);
                    if (gatherLimit > 255)
                        gatherLimit = 255;

                    const uint64_t origId = pkt.packetId();
                    pkt.reset(source, s_self.address(), Packet::VERB_OK);
                    pkt.append((uint8_t)Packet::VERB_MULTICAST_GATHER);
                    pkt.append(origId);
                    pkt.append(nwid);
                    mg.mac().appendTo(pkt);
                    pkt.append((uint32_t)mg.adi());

                    {
                        std::lock_guard<std::mutex> l(s_multicastSubscriptions_l);
                        auto forNet = s_multicastSubscriptions.find(nwid);
                        if (forNet != s_multicastSubscriptions.end()) {
                            auto forGroup = forNet->second.find(mg);
                            if (forGroup != forNet->second.end()) {
                                pkt.append((uint32_t)forGroup->second.size());
                                const unsigned int countAt = pkt.size();
                                pkt.addSize(2);

                                unsigned int l = 0;
                                for (auto g = forGroup->second.begin(); ((l < gatherLimit) && (g != forGroup->second.end())); ++g) {
                                    if (g->first != source) {
                                        ++l;
                                        g->first.appendTo(pkt);
                                    }
                                }

                                if (l > 0) {
                                    pkt.setAt<uint16_t>(countAt, (uint16_t)l);
                                    pkt.armor(peer->key, true);
                                    sendto(sock, pkt.data(), pkt.size(), SENDTO_FLAGS, (const struct sockaddr*)ip, (socklen_t)(ip->isV4() ? sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6)));

                                    s_outputRate.log(now, pkt.size());
                                    peer->lastSend = now;
                                }
                            }
                        }
                    }
                }
                catch (...) {
                    printf("* unexpected exception handling MULTICAST_GATHER from %s" ZT_EOL_S, ip->toString(ipstr));
                }
                break;

            default:
                break;
        }

        return;
    }

    // If we made it here, we are forwarding this packet to someone else and also possibly
    // sending a RENDEZVOUS message.

    int hops = 0;
    bool introduce = false;
    if (fragment) {
        if ((hops = (int)reinterpret_cast<Packet::Fragment*>(&pkt)->incrementHops()) > s_relayMaxHops) {
            // printf("%s refused to forward to %s: max hop count exceeded" ZT_EOL_S,ip->toString(ipstr),dest.toString(astr));
            s_discardedForwardRate.log(now, pkt.size());
            return;
        }
    }
    else {
        if ((hops = (int)pkt.incrementHops()) > s_relayMaxHops) {
            // printf("%s refused to forward to %s: max hop count exceeded" ZT_EOL_S,ip->toString(ipstr),dest.toString(astr));
            s_discardedForwardRate.log(now, pkt.size());
            return;
        }

        if (hops == 1) {
            RendezvousKey rk(source, dest);
            std::lock_guard<std::mutex> l(s_rendezvousTracking_l);
            RendezvousStats& lr = s_rendezvousTracking[rk];
            if ((now - lr.ts) >= 30000) {
                ++lr.count;
                lr.ts = now;
                introduce = true;
            }
        }
    }

    SharedPtr<RootPeer> forwardTo;
    {
        std::lock_guard<std::mutex> pbv_l(s_peersByVirtAddr_l);
        auto p = s_peersByVirtAddr.find(dest);
        if (p != s_peersByVirtAddr.end()) {
            forwardTo = p->second;
        }
    }

    if (unlikely(! forwardTo)) {
        s_discardedForwardRate.log(now, pkt.size());
        return;
    }

    if (introduce) {
        SharedPtr<RootPeer> sourcePeer;
        {
            std::lock_guard<std::mutex> l(s_peersByVirtAddr_l);
            auto sp = s_peersByVirtAddr.find(source);
            if (sp != s_peersByVirtAddr.end()) {
                sourcePeer = sp->second;
            }
        }
        if (likely(sourcePeer)) {
            if ((sourcePeer->v6s >= 0) && (forwardTo->v6s >= 0)) {
                Packet outp(dest, s_self.address(), Packet::VERB_RENDEZVOUS);
                outp.append((uint8_t)0);
                source.appendTo(outp);
                outp.append((uint16_t)sourcePeer->ip6.port());
                outp.append((uint8_t)16);
                outp.append((const uint8_t*)(sourcePeer->ip6.rawIpData()), 16);
                outp.armor(forwardTo->key, true);
                sendto(forwardTo->v6s, outp.data(), outp.size(), SENDTO_FLAGS, (const struct sockaddr*)&(forwardTo->ip6), (socklen_t)sizeof(struct sockaddr_in6));

                s_outputRate.log(now, outp.size());
                forwardTo->lastSend = now;

                outp.reset(source, s_self.address(), Packet::VERB_RENDEZVOUS);
                outp.append((uint8_t)0);
                dest.appendTo(outp);
                outp.append((uint16_t)forwardTo->ip6.port());
                outp.append((uint8_t)16);
                outp.append((const uint8_t*)(forwardTo->ip6.rawIpData()), 16);
                outp.armor(sourcePeer->key, true);
                sendto(sourcePeer->v6s, outp.data(), outp.size(), SENDTO_FLAGS, (const struct sockaddr*)&(sourcePeer->ip6), (socklen_t)sizeof(struct sockaddr_in6));

                s_outputRate.log(now, outp.size());
                sourcePeer->lastSend = now;
            }

            if ((sourcePeer->v4s >= 0) && (forwardTo->v4s >= 0)) {
                Packet outp(dest, s_self.address(), Packet::VERB_RENDEZVOUS);
                outp.append((uint8_t)0);
                source.appendTo(outp);
                outp.append((uint16_t)sourcePeer->ip4.port());
                outp.append((uint8_t)4);
                outp.append((const uint8_t*)sourcePeer->ip4.rawIpData(), 4);
                outp.armor(forwardTo->key, true);
                sendto(forwardTo->v4s, outp.data(), outp.size(), SENDTO_FLAGS, (const struct sockaddr*)&(forwardTo->ip4), (socklen_t)sizeof(struct sockaddr_in));

                s_outputRate.log(now, outp.size());
                forwardTo->lastSend = now;

                outp.reset(source, s_self.address(), Packet::VERB_RENDEZVOUS);
                outp.append((uint8_t)0);
                dest.appendTo(outp);
                outp.append((uint16_t)forwardTo->ip4.port());
                outp.append((uint8_t)4);
                outp.append((const uint8_t*)(forwardTo->ip4.rawIpData()), 4);
                outp.armor(sourcePeer->key, true);
                sendto(sourcePeer->v4s, outp.data(), outp.size(), SENDTO_FLAGS, (const struct sockaddr*)&(sourcePeer->ip4), (socklen_t)sizeof(struct sockaddr_in));

                s_outputRate.log(now, outp.size());
                sourcePeer->lastSend = now;
            }
        }
    }

    if (forwardTo->v6s >= 0) {
        if (sendto(forwardTo->v6s, pkt.data(), pkt.size(), SENDTO_FLAGS, (const struct sockaddr*)&(forwardTo->ip6), (socklen_t)sizeof(struct sockaddr_in6)) > 0) {
            s_outputRate.log(now, pkt.size());
            s_forwardRate.log(now, pkt.size());
            forwardTo->lastSend = now;
        }
    }
    else if (forwardTo->v4s >= 0) {
        if (sendto(forwardTo->v4s, pkt.data(), pkt.size(), SENDTO_FLAGS, (const struct sockaddr*)&(forwardTo->ip4), (socklen_t)sizeof(struct sockaddr_in)) > 0) {
            s_outputRate.log(now, pkt.size());
            s_forwardRate.log(now, pkt.size());
            forwardTo->lastSend = now;
        }
    }
}

//////////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////////

static int bindSocket(struct sockaddr* const bindAddr)
{
    const int s = socket(bindAddr->sa_family, SOCK_DGRAM, 0);
    if (s < 0) {
        close(s);
        return -1;
    }

    int f = 16777216;
    while (f > 65536) {
        if (setsockopt(s, SOL_SOCKET, SO_RCVBUF, (const char*)&f, sizeof(f)) == 0)
            break;
        f -= 65536;
    }
    f = 16777216;
    while (f > 65536) {
        if (setsockopt(s, SOL_SOCKET, SO_SNDBUF, (const char*)&f, sizeof(f)) == 0)
            break;
        f -= 65536;
    }

    if (bindAddr->sa_family == AF_INET6) {
        f = 1;
        setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY, (void*)&f, sizeof(f));
#ifdef IPV6_MTU_DISCOVER
        f = 0;
        setsockopt(s, IPPROTO_IPV6, IPV6_MTU_DISCOVER, &f, sizeof(f));
#endif
#ifdef IPV6_DONTFRAG
        f = 0;
        setsockopt(s, IPPROTO_IPV6, IPV6_DONTFRAG, &f, sizeof(f));
#endif
    }
#ifdef IP_DONTFRAG
    f = 0;
    setsockopt(s, IPPROTO_IP, IP_DONTFRAG, &f, sizeof(f));
#endif
#ifdef IP_MTU_DISCOVER
    f = IP_PMTUDISC_DONT;
    setsockopt(s, IPPROTO_IP, IP_MTU_DISCOVER, &f, sizeof(f));
#endif

    /*
    #ifdef SO_NO_CHECK
        if (bindAddr->sa_family == AF_INET) {
            f = 1; setsockopt(s,SOL_SOCKET,SO_NO_CHECK,(void *)&f,sizeof(f));
        }
    #endif
    */

#ifdef SO_REUSEPORT
    f = 1;
    setsockopt(s, SOL_SOCKET, SO_REUSEPORT, (void*)&f, sizeof(f));
#endif
#ifndef __LINUX__   // linux wants just SO_REUSEPORT
    f = 1;
    setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (void*)&f, sizeof(f));
#endif

#ifdef __LINUX__
    struct timeval tv;
    tv.tv_sec = 1;
    tv.tv_usec = 0;
    setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, (const void*)&tv, sizeof(tv));
#endif

    if (bind(s, bindAddr, (bindAddr->sa_family == AF_INET) ? sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6))) {
        close(s);
        // printf("%s\n",strerror(errno));
        return -1;
    }

    return s;
}

static void shutdownSigHandler(int sig)
{
    s_run = false;
}

int main(int argc, char** argv)
{
    std::vector<std::thread> threads;
    std::vector<int> sockets;
    int v4Sock = -1, v6Sock = -1;

    signal(SIGTERM, shutdownSigHandler);
    signal(SIGINT, shutdownSigHandler);
    signal(SIGQUIT, shutdownSigHandler);
    signal(SIGPIPE, SIG_IGN);
    signal(SIGUSR1, SIG_IGN);
    signal(SIGUSR2, SIG_IGN);
    signal(SIGCHLD, SIG_IGN);

    s_startTime = OSUtils::now();
    s_geoInit = false;

    if (argc < 3) {
        printf("Usage: zerotier-root <identity.secret> <config path>" ZT_EOL_S);
        return 1;
    }

    {
        std::string myIdStr;
        if (! OSUtils::readFile(argv[1], myIdStr)) {
            printf("FATAL: cannot read identity.secret at %s" ZT_EOL_S, argv[1]);
            return 1;
        }
        if (! s_self.fromString(myIdStr.c_str())) {
            printf("FATAL: cannot read identity.secret at %s (invalid identity)" ZT_EOL_S, argv[1]);
            return 1;
        }
        if (! s_self.hasPrivate()) {
            printf("FATAL: cannot read identity.secret at %s (missing secret key)" ZT_EOL_S, argv[1]);
            return 1;
        }
    }
    {
        std::string configStr;
        if (! OSUtils::readFile(argv[2], configStr)) {
            printf("FATAL: cannot read config file at %s" ZT_EOL_S, argv[2]);
            return 1;
        }
        try {
            s_config = json::parse(configStr);
        }
        catch (std::exception& exc) {
            printf("FATAL: config file at %s invalid: %s" ZT_EOL_S, argv[2], exc.what());
            return 1;
        }
        catch (...) {
            printf("FATAL: config file at %s invalid: unknown exception" ZT_EOL_S, argv[2]);
            return 1;
        }
        if (! s_config.is_object()) {
            printf("FATAL: config file at %s invalid: does not contain a JSON object" ZT_EOL_S, argv[2]);
            return 1;
        }
    }

    try {
        auto jport = s_config["port"];
        if (jport.is_array()) {
            for (long i = 0; i < (long)jport.size(); ++i) {
                int port = jport[i];
                if ((port <= 0) || (port > 65535)) {
                    printf("FATAL: invalid port in config file %d" ZT_EOL_S, port);
                    return 1;
                }
                s_ports.push_back(port);
            }
        }
        else {
            int port = jport;
            if ((port <= 0) || (port > 65535)) {
                printf("FATAL: invalid port in config file %d" ZT_EOL_S, port);
                return 1;
            }
            s_ports.push_back(port);
        }
    }
    catch (...) {
    }
    if (s_ports.empty())
        s_ports.push_back(ZT_DEFAULT_PORT);
    std::sort(s_ports.begin(), s_ports.end());

    int httpPort = ZT_DEFAULT_PORT;
    try {
        httpPort = s_config["httpPort"];
        if ((httpPort <= 0) || (httpPort > 65535)) {
            printf("FATAL: invalid HTTP port in config file %d" ZT_EOL_S, httpPort);
            return 1;
        }
    }
    catch (...) {
        httpPort = ZT_DEFAULT_PORT;
    }

    std::string planetFilePath;
    try {
        planetFilePath = s_config["planetFile"];
    }
    catch (...) {
        planetFilePath = "";
    }

    try {
        s_statsRoot = s_config["statsRoot"];
        while ((s_statsRoot.length() > 0) && (s_statsRoot[s_statsRoot.length() - 1] == ZT_PATH_SEPARATOR))
            s_statsRoot = s_statsRoot.substr(0, s_statsRoot.length() - 1);
        if (s_statsRoot.length() > 0)
            OSUtils::mkdir(s_statsRoot);
    }
    catch (...) {
        s_statsRoot = "";
    }

    s_relayMaxHops = ZT_RELAY_MAX_HOPS;
    try {
        s_relayMaxHops = s_config["relayMaxHops"];
        if (s_relayMaxHops > ZT_PROTO_MAX_HOPS)
            s_relayMaxHops = ZT_PROTO_MAX_HOPS;
        else if (s_relayMaxHops < 0)
            s_relayMaxHops = 0;
    }
    catch (...) {
        s_relayMaxHops = ZT_RELAY_MAX_HOPS;
    }

    try {
        s_googleMapsAPIKey = s_config["googleMapsAPIKey"];
        std::string geoIpPath = s_config["geoIp"];
        if (geoIpPath.length() > 0) {
            FILE* gf = fopen(geoIpPath.c_str(), "rb");
            if (gf) {
                threads.emplace_back(std::thread([gf]() {
                    try {
                        char line[1024];
                        line[1023] = 0;
                        while (fgets(line, sizeof(line) - 1, gf)) {
                            InetAddress start, end;
                            float lat = 0.0F, lon = 0.0F;
                            int field = 0;
                            for (char *saveptr = nullptr, *f = Utils::stok(line, ",\r\n", &saveptr); (f); f = Utils::stok(nullptr, ",\r\n", &saveptr)) {
                                switch (field++) {
                                    case 0:
                                        start.fromString(f);
                                        break;
                                    case 1:
                                        end.fromString(f);
                                        break;
                                    case 2:
                                        lat = strtof(f, nullptr);
                                        break;
                                    case 3:
                                        lon = strtof(f, nullptr);
                                        break;
                                }
                            }
                            if ((start) && (end) && (start.ss_family == end.ss_family) && (lat >= -90.0F) && (lat <= 90.0F) && (lon >= -180.0F) && (lon <= 180.0F)) {
                                if (start.ss_family == AF_INET) {
                                    s_geoIp4[std::pair<uint32_t, uint32_t>(ip4ToH32(start), ip4ToH32(end))] = std::pair<float, float>(lat, lon);
                                }
                                else if (start.ss_family == AF_INET6) {
                                    s_geoIp6[std::pair<std::array<uint64_t, 2>, std::array<uint64_t, 2> >(ip6ToH128(start), ip6ToH128(end))] = std::pair<float, float>(lat, lon);
                                }
                            }
                        }
                        s_geoInit = true;
                    }
                    catch (...) {
                    }
                    fclose(gf);
                }));
            }
        }
    }
    catch (...) {
    }

    unsigned int ncores = std::thread::hardware_concurrency();
    if (ncores == 0)
        ncores = 1;

    s_run = true;

    threads.push_back(std::thread([]() {
        std::vector<SharedPtr<RootPeer> > toValidate;
        while (s_run) {
            {
                std::lock_guard<std::mutex> l(s_peersToValidate_l);
                toValidate.swap(s_peersToValidate);
            }
            for (auto p = toValidate.begin(); p != toValidate.end(); ++p) {
                if (likely(! (*p)->identityValidated)) {
                    if (likely((*p)->id.locallyValidate())) {
                        (*p)->identityValidated = true;
                    }
                    else {
                        {
                            std::lock_guard<std::mutex> p_l(s_peersByVirtAddr_l);
                            auto pp = s_peersByVirtAddr.find((*p)->id.address());
                            if ((pp != s_peersByVirtAddr.end()) && (pp->second == *p)) {
                                s_peersByVirtAddr.erase(pp);
                            }
                        }
                        {
                            std::lock_guard<std::mutex> p_l(s_peers_l);
                            for (auto pp = s_peers.begin(); pp != s_peers.end(); ++pp) {
                                if (*p == *pp) {
                                    s_peers.erase(pp);
                                    break;
                                }
                            }
                        }
                    }
                }
            }
            toValidate.clear();
            usleep(1000);
        }
    }));

    for (auto port = s_ports.begin(); port != s_ports.end(); ++port) {
        for (unsigned int tn = 0; tn < ncores; ++tn) {
            struct sockaddr_in6 in6;
            memset(&in6, 0, sizeof(in6));
            in6.sin6_family = AF_INET6;
            in6.sin6_port = htons((uint16_t)*port);
            const int s6 = bindSocket((struct sockaddr*)&in6);
            if (s6 < 0) {
                std::cout << "ERROR: unable to bind to port " << *port << ZT_EOL_S;
                exit(1);
            }

            struct sockaddr_in in4;
            memset(&in4, 0, sizeof(in4));
            in4.sin_family = AF_INET;
            in4.sin_port = htons((uint16_t)*port);
            const int s4 = bindSocket((struct sockaddr*)&in4);
            if (s4 < 0) {
                std::cout << "ERROR: unable to bind to port " << *port << ZT_EOL_S;
                exit(1);
            }

            sockets.push_back(s6);
            sockets.push_back(s4);
            if (v4Sock < 0)
                v4Sock = s4;
            if (v6Sock < 0)
                v6Sock = s6;

            threads.push_back(std::thread([s6, s4]() {
                struct sockaddr_in6 in6;
                Packet* pkt = new Packet();
                for (;;) {
                    memset(&in6, 0, sizeof(in6));
                    socklen_t sl = sizeof(in6);
                    const int pl = (int)recvfrom(s6, pkt->unsafeData(), pkt->capacity(), RECVFROM_FLAGS, (struct sockaddr*)&in6, &sl);
                    if (pl > 0) {
                        if ((pl >= ZT_PROTO_MIN_FRAGMENT_LENGTH) && (pl <= ZT_PROTO_MAX_PACKET_LENGTH)) {
                            try {
                                pkt->setSize((unsigned int)pl);
                                handlePacket(s6, reinterpret_cast<const InetAddress*>(&in6), *pkt);
                            }
                            catch (std::exception& exc) {
                                char ipstr[128];
                                printf("WARNING: unexpected exception handling packet from %s: %s" ZT_EOL_S, reinterpret_cast<const InetAddress*>(&in6)->toString(ipstr), exc.what());
                            }
                            catch (int exc) {
                                char ipstr[128];
                                printf("WARNING: unexpected exception handling packet from %s: ZT exception code %d" ZT_EOL_S, reinterpret_cast<const InetAddress*>(&in6)->toString(ipstr), exc);
                            }
                            catch (...) {
                                char ipstr[128];
                                printf("WARNING: unexpected exception handling packet from %s: unknown exception" ZT_EOL_S, reinterpret_cast<const InetAddress*>(&in6)->toString(ipstr));
                            }
                        }
                    }
                    else if (! s_run) {
                        break;
                    }
                }
                delete pkt;
            }));

            threads.push_back(std::thread([s6, s4]() {
                struct sockaddr_in in4;
                Packet* pkt = new Packet();
                for (;;) {
                    memset(&in4, 0, sizeof(in4));
                    socklen_t sl = sizeof(in4);
                    const int pl = (int)recvfrom(s4, pkt->unsafeData(), pkt->capacity(), RECVFROM_FLAGS, (struct sockaddr*)&in4, &sl);
                    if (pl > 0) {
                        if ((pl >= ZT_PROTO_MIN_FRAGMENT_LENGTH) && (pl <= ZT_PROTO_MAX_PACKET_LENGTH)) {
                            try {
                                pkt->setSize((unsigned int)pl);
                                handlePacket(s4, reinterpret_cast<const InetAddress*>(&in4), *pkt);
                            }
                            catch (std::exception& exc) {
                                char ipstr[128];
                                printf("WARNING: unexpected exception handling packet from %s: %s" ZT_EOL_S, reinterpret_cast<const InetAddress*>(&in4)->toString(ipstr), exc.what());
                            }
                            catch (int exc) {
                                char ipstr[128];
                                printf("WARNING: unexpected exception handling packet from %s: ZT exception code %d" ZT_EOL_S, reinterpret_cast<const InetAddress*>(&in4)->toString(ipstr), exc);
                            }
                            catch (...) {
                                char ipstr[128];
                                printf("WARNING: unexpected exception handling packet from %s: unknown exception" ZT_EOL_S, reinterpret_cast<const InetAddress*>(&in4)->toString(ipstr));
                            }
                        }
                    }
                    else if (! s_run) {
                        break;
                    }
                }
                delete pkt;
            }));
        }
    }

    // A minimal read-only local API for monitoring and status queries
    httplib::Server apiServ;
    threads.push_back(std::thread([&apiServ, httpPort]() {
        // Human readable status page
        apiServ.Get("/", [](const httplib::Request& req, httplib::Response& res) {
            std::ostringstream o;
            o << "ZeroTier Root Server " << ZEROTIER_ONE_VERSION_MAJOR << '.' << ZEROTIER_ONE_VERSION_MINOR << '.' << ZEROTIER_ONE_VERSION_REVISION << ZT_EOL_S;
            o << "(c)2019 ZeroTier, Inc." ZT_EOL_S "Licensed under the ZeroTier BSL 1.1" ZT_EOL_S ZT_EOL_S;
            s_peersByVirtAddr_l.lock();
            o << "Peers Online:       " << s_peersByVirtAddr.size() << ZT_EOL_S;
            s_peersByVirtAddr_l.unlock();
            res.set_content(o.str(), "text/plain");
        });

        apiServ.Get("/metrics", [](const httplib::Request& req, httplib::Response& res) {
            std::ostringstream o;
            int64_t now = OSUtils::now();

            char buf[11];
            const char* root_id = s_self.address().toString(buf);
            o << "# HELP root_peers_online Number of active peers online" << ZT_EOL_S;
            o << "# TYPE root_peers_online gauge" << ZT_EOL_S;
            s_peersByVirtAddr_l.lock();
            o << "root_peers_online{root_id=\"" << root_id << "\"} " << s_peersByVirtAddr.size() << ZT_EOL_S;
            s_peersByVirtAddr_l.unlock();
            o << "# HELP root_input_rate Input rate MiB/s" << ZT_EOL_S;
            o << "# TYPE root_input_rate gauge" << ZT_EOL_S;
            o << "root_input_rate{root_id=\"" << root_id << "\"} " << std::setprecision(5) << (s_inputRate.perSecond(now) / 1048576.0) << ZT_EOL_S;
            o << "# HELP root_output_rate Output rate MiB/s" << ZT_EOL_S;
            o << "# TYPE root_output_rate gauge" << ZT_EOL_S;
            o << "root_output_rate{root_id=\"" << root_id << "\"} " << std::setprecision(5) << (s_outputRate.perSecond(now) / 1048576.0) << ZT_EOL_S;
            o << "# HELP root_forwarded_rate Forwarded packet rate MiB/s" << ZT_EOL_S;
            o << "# TYPE root_forwarded_rate gauge" << ZT_EOL_S;
            o << "root_forwarded_rate{root_id=\"" << root_id << "\"} " << std::setprecision(5) << (s_forwardRate.perSecond(now) / 1048576.0) << ZT_EOL_S;
            o << "# HELP root_discarded_rate Discarded forwards MiB/s" << ZT_EOL_S;
            o << "# TYPE root_discarded_rate gauge" << ZT_EOL_S;
            o << "root_discarded_rate{root_id=\"" << root_id << "\"} " << std::setprecision(5) << (s_discardedForwardRate.perSecond(now) / 1048576.0) << ZT_EOL_S;

            res.set_content(o.str(), "text/plain");
        });

        // Peer list for compatibility with software that monitors regular nodes
        apiServ.Get("/peer", [](const httplib::Request& req, httplib::Response& res) {
            char tmp[256];
            std::ostringstream o;
            o << '[';
            try {
                bool first = true;
                std::lock_guard<std::mutex> l(s_peers_l);
                for (auto p = s_peers.begin(); p != s_peers.end(); ++p) {
                    if (first)
                        first = false;
                    else
                        o << ',';
                    o << "{\"address\":\"" << (*p)->id.address().toString(tmp)
                      << "\""
                         ",\"latency\":-1"
                         ",\"paths\":[";
                    if ((*p)->v4s >= 0) {
                        o << "{\"active\":true"
                             ",\"address\":\""
                          << (*p)->ip4.toIpString(tmp) << "\\/" << (*p)->ip4.port()
                          << "\""
                             ",\"expired\":false"
                             ",\"lastReceive\":"
                          << (*p)->lastReceive << ",\"lastSend\":" << (*p)->lastSend
                          << ",\"preferred\":true"
                             ",\"trustedPathId\":0}";
                    }
                    if ((*p)->v6s >= 0) {
                        if ((*p)->v4s >= 0)
                            o << ',';
                        o << "{\"active\":true"
                             ",\"address\":\""
                          << (*p)->ip6.toIpString(tmp) << "\\/" << (*p)->ip6.port()
                          << "\""
                             ",\"expired\":false"
                             ",\"lastReceive\":"
                          << (*p)->lastReceive << ",\"lastSend\":" << (*p)->lastSend << ",\"preferred\":" << (((*p)->ip4) ? "false" : "true") << ",\"trustedPathId\":0}";
                    }
                    o << "]"
                         ",\"role\":\"LEAF\""
                         ",\"version\":\""
                      << (*p)->vMajor << '.' << (*p)->vMinor << '.' << (*p)->vRev
                      << "\""
                         ",\"versionMajor\":"
                      << (*p)->vMajor << ",\"versionMinor\":" << (*p)->vMinor << ",\"versionRev\":" << (*p)->vRev << "}";
                }
            }
            catch (...) {
            }
            o << ']';
            res.set_content(o.str(), "application/json");
        });

        // GeoIP map if enabled
        apiServ.Get("/map", [](const httplib::Request& req, httplib::Response& res) {
            char tmp[4096];
            if (! s_geoInit) {
                res.set_content("Not enabled or GeoIP CSV file not finished reading.", "text/plain");
                return;
            }
            std::ostringstream o;
            o << ZT_GEOIP_HTML_HEAD;
            try {
                bool firstCoord = true;
                std::pair<uint32_t, uint32_t> k4(0, 0xffffffff);
                std::pair<std::array<uint64_t, 2>, std::array<uint64_t, 2> > k6;
                k6.second[0] = 0xffffffffffffffffULL;
                k6.second[1] = 0xffffffffffffffffULL;

                std::unordered_map<InetAddress, std::set<Address>, InetAddressHasher> ips;
                {
                    std::lock_guard<std::mutex> l(s_peers_l);
                    for (auto p = s_peers.begin(); p != s_peers.end(); ++p) {
                        if ((*p)->v4s >= 0)
                            ips[(*p)->ip4].insert((*p)->id.address());
                        if ((*p)->v6s >= 0)
                            ips[(*p)->ip6].insert((*p)->id.address());
                    }
                }

                for (auto p = ips.begin(); p != ips.end(); ++p) {
                    if (p->first.isV4()) {
                        k4.first = ip4ToH32(p->first);
                        auto geo = std::map<std::pair<uint32_t, uint32_t>, std::pair<float, float> >::reverse_iterator(s_geoIp4.upper_bound(k4));
                        uint32_t bestRangeSize = 0xffffffff;
                        std::pair<float, float> bestRangeLatLon;
                        while (geo != s_geoIp4.rend()) {
                            if ((geo->first.first <= k4.first) && (geo->first.second >= k4.first)) {
                                uint32_t range = geo->first.second - geo->first.first;
                                if (range <= bestRangeSize) {
                                    bestRangeSize = range;
                                    bestRangeLatLon = geo->second;
                                }
                            }
                            else if ((geo->first.first < k4.first) && (geo->first.second < k4.first)) {
                                break;
                            }
                            ++geo;
                        }
                        if (bestRangeSize != 0xffffffff) {
                            if (! firstCoord)
                                o << ',';
                            firstCoord = false;
                            o << "{lat:" << bestRangeLatLon.first << ",lng:" << bestRangeLatLon.second << ",_l:\"";
                            bool firstAddr = true;
                            for (auto a = p->second.begin(); a != p->second.end(); ++a) {
                                if (! firstAddr)
                                    o << ',';
                                o << a->toString(tmp);
                                firstAddr = false;
                            }
                            o << "\"}";
                        }
                    }
                    else if (p->first.isV6()) {
                        k6.first = ip6ToH128(p->first);
                        auto geo = std::map<std::pair<std::array<uint64_t, 2>, std::array<uint64_t, 2> >, std::pair<float, float> >::reverse_iterator(s_geoIp6.upper_bound(k6));
                        while (geo != s_geoIp6.rend()) {
                            if ((geo->first.first <= k6.first) && (geo->first.second >= k6.first)) {
                                if (! firstCoord)
                                    o << ',';
                                firstCoord = false;
                                o << "{lat:" << geo->second.first << ",lng:" << geo->second.second << ",_l:\"";
                                bool firstAddr = true;
                                for (auto a = p->second.begin(); a != p->second.end(); ++a) {
                                    if (! firstAddr)
                                        o << ',';
                                    o << a->toString(tmp);
                                    firstAddr = false;
                                }
                                o << "\"}";
                                break;
                            }
                            else if ((geo->first.first < k6.first) && (geo->first.second < k6.first)) {
                                break;
                            }
                            ++geo;
                        }
                    }
                }
            }
            catch (...) {
                res.set_content("Internal error: unexpected exception resolving GeoIP locations", "text/plain");
                return;
            }
            OSUtils::ztsnprintf(tmp, sizeof(tmp), ZT_GEOIP_HTML_TAIL, s_googleMapsAPIKey.c_str());
            o << tmp;
            res.set_content(o.str(), "text/html");
        });

        apiServ.listen("127.0.0.1", httpPort, 0);
    }));

    // In the main thread periodically clean stuff up
    int64_t lastCleaned = 0;
    int64_t lastWroteStats = 0;
    while (s_run) {
        sleep(1);

        const int64_t now = OSUtils::now();

        if ((now - lastCleaned) > 300000) {
            lastCleaned = now;

            // Old multicast subscription cleanup
            {
                std::lock_guard<std::mutex> l(s_multicastSubscriptions_l);
                for (auto a = s_multicastSubscriptions.begin(); a != s_multicastSubscriptions.end();) {
                    for (auto b = a->second.begin(); b != a->second.end();) {
                        for (auto c = b->second.begin(); c != b->second.end();) {
                            if ((now - c->second) > ZT_MULTICAST_LIKE_EXPIRE)
                                b->second.erase(c++);
                            else
                                ++c;
                        }
                        if (b->second.empty())
                            a->second.erase(b++);
                        else
                            ++b;
                    }
                    if (a->second.empty())
                        s_multicastSubscriptions.erase(a++);
                    else
                        ++a;
                }
            }

            try {
                std::vector<SharedPtr<RootPeer> > toRemove;
                toRemove.reserve(1024);
                {
                    std::lock_guard<std::mutex> pbi_l(s_peers_l);
                    std::vector<SharedPtr<RootPeer> > newPeers;
                    newPeers.reserve(s_peers.size());
                    for (auto p = s_peers.begin(); p != s_peers.end(); ++p) {
                        if ((now - (*p)->lastReceive) > ZT_PEER_ACTIVITY_TIMEOUT) {
                            toRemove.emplace_back();
                            p->swap(toRemove.back());
                        }
                        else {
                            newPeers.emplace_back();
                            p->swap(newPeers.back());
                        }
                    }
                    newPeers.swap(s_peers);
                }
                for (auto p = toRemove.begin(); p != toRemove.end(); ++p) {
                    {
                        std::lock_guard<std::mutex> pbv_l(s_peersByVirtAddr_l);
                        auto pbv = s_peersByVirtAddr.find((*p)->id.address());
                        if ((pbv != s_peersByVirtAddr.end()) && (pbv->second == *p)) {
                            s_peersByVirtAddr.erase(pbv);
                        }
                    }
                }
            }
            catch (...) {
            }

            // Remove old rendezvous entries
            {
                std::lock_guard<std::mutex> l(s_rendezvousTracking_l);
                for (auto lr = s_rendezvousTracking.begin(); lr != s_rendezvousTracking.end();) {
                    if ((now - lr->second.ts) > ZT_PEER_ACTIVITY_TIMEOUT)
                        s_rendezvousTracking.erase(lr++);
                    else
                        ++lr;
                }
            }
        }

        // Write stats if configured to do so, and periodically refresh planet file (if any)
        if (((now - lastWroteStats) > 15000) && (s_statsRoot.length() > 0)) {
            lastWroteStats = now;

            try {
                if (planetFilePath.length() > 0) {
                    std::string planetData;
                    if ((OSUtils::readFile(planetFilePath.c_str(), planetData)) && (planetData.length() > 0)) {
                        std::lock_guard<std::mutex> pl(s_planet_l);
                        s_planet = planetData;
                    }
                }
            }
            catch (...) {
                std::lock_guard<std::mutex> pl(s_planet_l);
                s_planet.clear();
            }

            std::string peersFilePath(s_statsRoot);
            peersFilePath.append("/.peers.tmp");
            FILE* pf = fopen(peersFilePath.c_str(), "wb");
            if (pf) {
                std::vector<SharedPtr<RootPeer> > sp;
                {
                    std::lock_guard<std::mutex> pbi_l(s_peers_l);
                    sp.reserve(s_peers.size());
                    for (auto p = s_peers.begin(); p != s_peers.end(); ++p) {
                        sp.emplace_back(*p);
                    }
                }
                std::sort(sp.begin(), sp.end(), [](const SharedPtr<RootPeer>& a, const SharedPtr<RootPeer>& b) { return (a->id < b->id); });

                fprintf(pf, "Address    %21s %45s %10s %6s %10s" ZT_EOL_S, "IPv4", "IPv6", "Age(sec)", "Vers", "Fwd(KiB/s)");
                {
                    char ip4[128], ip6[128], ver[128];
                    for (auto p = sp.begin(); p != sp.end(); ++p) {
                        if ((*p)->v4s >= 0) {
                            (*p)->ip4.toString(ip4);
                        }
                        else {
                            ip4[0] = '-';
                            ip4[1] = 0;
                        }
                        if ((*p)->v6s >= 0) {
                            (*p)->ip6.toString(ip6);
                        }
                        else {
                            ip6[0] = '-';
                            ip6[1] = 0;
                        }
                        OSUtils::ztsnprintf(ver, sizeof(ver), "%d.%d.%d", (*p)->vMajor, (*p)->vMinor, (*p)->vRev);
                        fprintf(pf, "%.10llx %21s %45s %10.4f %6s" ZT_EOL_S, (unsigned long long)(*p)->id.address().toInt(), ip4, ip6, fabs((double)(now - (*p)->lastReceive) / 1000.0), ver);
                    }
                }

                fclose(pf);
                std::string peersFilePath2(s_statsRoot);
                peersFilePath2.append("/peers");
                OSUtils::rm(peersFilePath2);
                OSUtils::rename(peersFilePath.c_str(), peersFilePath2.c_str());
            }

            std::string statsFilePath(s_statsRoot);
            statsFilePath.append("/.stats.tmp");
            FILE* sf = fopen(statsFilePath.c_str(), "wb");
            if (sf) {
                fprintf(sf, "Uptime (seconds)           : %ld" ZT_EOL_S, (long)((now - s_startTime) / 1000));
                s_peersByVirtAddr_l.lock();
                fprintf(sf, "Peers                      : %llu" ZT_EOL_S, (unsigned long long)s_peersByVirtAddr.size());
                s_peersByVirtAddr_l.unlock();
                s_rendezvousTracking_l.lock();
                uint64_t unsuccessfulp2p = 0;
                for (auto lr = s_rendezvousTracking.begin(); lr != s_rendezvousTracking.end(); ++lr) {
                    if (lr->second.count > 6)   // 6 == two attempts per edge, one for each direction
                        ++unsuccessfulp2p;
                }
                fprintf(sf, "Recent P2P Graph Edges     : %llu" ZT_EOL_S, (unsigned long long)s_rendezvousTracking.size());
                if (s_rendezvousTracking.empty()) {
                    fprintf(sf, "Recent P2P Success Rate    : 100.0000%%" ZT_EOL_S);
                }
                else {
                    fprintf(sf, "Recent P2P Success Rate    : %.4f%%" ZT_EOL_S, (1.0 - ((double)unsuccessfulp2p / (double)s_rendezvousTracking.size())) * 100.0);
                }
                s_rendezvousTracking_l.unlock();
                fprintf(sf, "Input (MiB/s)              : %.4f" ZT_EOL_S, s_inputRate.perSecond(now) / 1048576.0);
                fprintf(sf, "Output (MiB/s)             : %.4f" ZT_EOL_S, s_outputRate.perSecond(now) / 1048576.0);
                fprintf(sf, "Forwarded (MiB/s)          : %.4f" ZT_EOL_S, s_forwardRate.perSecond(now) / 1048576.0);
                fprintf(sf, "Discarded Forward (MiB/s)  : %.4f" ZT_EOL_S, s_discardedForwardRate.perSecond(now) / 1048576.0);

                fclose(sf);
                std::string statsFilePath2(s_statsRoot);
                statsFilePath2.append("/stats");
                OSUtils::rm(statsFilePath2);
                OSUtils::rename(statsFilePath.c_str(), statsFilePath2.c_str());
            }
        }
    }

    // If we received a kill signal, close everything and wait
    // for threads to die before exiting.
    s_run = false;   // sanity check
    apiServ.stop();
    for (auto s = sockets.begin(); s != sockets.end(); ++s) {
        shutdown(*s, SHUT_RDWR);
        close(*s);
    }
    for (auto t = threads.begin(); t != threads.end(); ++t)
        t->join();

    return 0;
}