lokinet/llarp/service/endpoint.cpp

#include "endpoint.hpp"

#include "auth.hpp"
#include "endpoint_state.hpp"
#include "endpoint_util.hpp"
#include "info.hpp"
#include "outbound_context.hpp"
#include "protocol.hpp"
#include "protocol_type.hpp"

#include <llarp/dht/key.hpp>
#include <llarp/link/contacts.hpp>
#include <llarp/link/tunnel.hpp>
#include <llarp/net/ip.hpp>
#include <llarp/net/ip_range.hpp>
#include <llarp/nodedb.hpp>
#include <llarp/path/path.hpp>
#include <llarp/profiling.hpp>
#include <llarp/router/route_poker.hpp>
#include <llarp/router/router.hpp>
#include <llarp/util/logging.hpp>
#include <llarp/util/priority_queue.hpp>

#include <optional>
#include <type_traits>
#include <utility>
#include <variant>

namespace llarp::service
{
  static auto logcat = log::Cat("endpoint");

  Endpoint::Endpoint(Router* r, Context* parent)
      : path::Builder{r, 3, path::DEFAULT_LEN}
      , context{parent}
      , _inbound_queue{512}
      , _send_queue{512}
      , _recv_event_queue{512}
      , _introset_lookup_filter{5s}
  {
    _state = std::make_unique<EndpointState>();
    _state->router = r;
    _state->name = "endpoint";
    _recv_event_queue.enable();

    // if (Loop()->MaybeGetUVWLoop())
    //   _tunnel_manager = std::make_unique<link::TunnelManager>(*this);
  }

  bool
  Endpoint::Configure(const NetworkConfig& conf, [[maybe_unused]] const DnsConfig& dnsConf)
  {
    if (conf.m_Paths.has_value())
      numDesiredPaths = *conf.m_Paths;

    if (conf.m_Hops.has_value())
      numHops = *conf.m_Hops;

    conf.m_ExitMap.ForEachEntry(
        [&](const IPRange& range, const service::Address& addr) { MapExitRange(range, addr); });

    for (auto [exit, auth] : conf.m_ExitAuths)
    {
      SetAuthInfoForEndpoint(exit, auth);
    }

    conf.m_LNSExitMap.ForEachEntry([&](const IPRange& range, const std::string& name) {
      std::optional<AuthInfo> auth;
      const auto itr = conf.m_LNSExitAuths.find(name);
      if (itr != conf.m_LNSExitAuths.end())
        auth = itr->second;
      _startup_ons_mappings[name] = std::make_pair(range, auth);
    });

    return _state->Configure(conf);
  }

  bool
  Endpoint::HasPendingPathToService(const Address& addr) const
  {
    return _state->pending_service_lookups.find(addr) != _state->pending_service_lookups.end();
  }

  bool
  Endpoint::is_ready() const
  {
    const auto now = llarp::time_now_ms();
    if (intro_set().intros.empty())
      return false;
    if (intro_set().IsExpired(now))
      return false;
    return true;
  }

  bool
  Endpoint::HasPendingRouterLookup(const RouterID remote) const
  {
    const auto& routers = _state->pending_routers;
    return routers.find(remote) != routers.end();
  }

  std::optional<std::variant<Address, RouterID>>
  Endpoint::GetEndpointWithConvoTag(ConvoTag tag) const
  {
    auto itr = Sessions().find(tag);
    if (itr != Sessions().end())
    {
      return itr->second.remote.Addr();
    }

    for (const auto& item : _state->snode_sessions)
    {
      if (const auto maybe = item.second->CurrentPath())
      {
        if (ConvoTag{maybe->as_array()} == tag)
          return item.first;
      }
    }
    return std::nullopt;
  }

  void
  Endpoint::map_exit(
      std::string name,
      std::string token,
      std::vector<IPRange> ranges,
      std::function<void(bool, std::string)> result_handler)
  {
    if (ranges.empty())
    {
      result_handler(false, "no ranges provided");
      return;
    }

    lookup_name(
        name,
        [ptr = std::static_pointer_cast<Endpoint>(GetSelf()),
         name,
         auth = AuthInfo{token},
         ranges,
         result_handler,
         poker = router()->route_poker()](oxen::quic::message m) mutable {
          if (m)
          {
            std::string name;
            try
            {
              oxenc::bt_dict_consumer btdc{m.body()};
              name = btdc.require<std::string>("NAME");
            }
            catch (...)
            {
              log::warning(link_cat, "Failed to parse find name response!");
              throw;
            }

            if (auto saddr = service::Address(); saddr.FromString(name))
            {
              ptr->SetAuthInfoForEndpoint(saddr, auth);
              ptr->MarkAddressOutbound(saddr);

              auto result = ptr->EnsurePathToService(
                  saddr,
                  [ptr, name, ranges, result_handler, poker](auto addr, OutboundContext* ctx) {
                    if (ctx == nullptr)
                    {
                      result_handler(false, "could not establish flow to {}"_format(name));
                      return;
                    }

                    // make a lambda that sends the reply after doing auth
                    auto apply_result = [ptr, poker, addr, result_handler, ranges](
                                            std::string result, bool success) {
                      if (success)
                      {
                        for (const auto& range : ranges)
                          ptr->MapExitRange(range, addr);

                        if (poker)
                          poker->put_up();

                        result_handler(true, result);
                      }

                      result_handler(false, result);
                    };

                    ctx->send_auth_async(apply_result);
                  },
                  ptr->PathAlignmentTimeout());

              if (not result)
                result_handler(false, "Could not build path to {}"_format(name));
            }
          }
          else
          {
            result_handler(false, "Exit {} not found!"_format(name));
          }
        });
  }

  void
  Endpoint::LookupServiceAsync(
      std::string name,
      std::string service,
      std::function<void(std::vector<dns::SRVData>)> resultHandler)
  {
    // handles when we aligned to a loki address
    auto handleGotPathToService = [resultHandler, service, this](auto addr) {
      // we can probably get this info before we have a path to them but we do this after we
      // have a path so when we send the response back they can send shit to them immediately
      const auto& container = _state->remote_sessions;
      if (auto itr = container.find(addr); itr != container.end())
      {
        // parse the stuff we need from this guy
        resultHandler(itr->second->GetCurrentIntroSet().GetMatchingSRVRecords(service));
        return;
      }
      resultHandler({});
    };

    // handles when we resolved a .snode
    auto handleResolvedSNodeName = [resultHandler, nodedb = router()->node_db()](auto router_id) {
      std::vector<dns::SRVData> result{};

      if (auto maybe_rc = nodedb->get_rc(router_id))
      {
        result = maybe_rc->srvRecords;  // TODO: RouterContact has no SRV records
      }
      
      resultHandler(std::move(result));
    };

    // handles when we got a path to a remote thing
    auto handleGotPathTo = [handleGotPathToService, handleResolvedSNodeName, resultHandler](
                               auto maybe_tag, auto address) {
      if (not maybe_tag)
      {
        resultHandler({});
        return;
      }

      if (auto* addr = std::get_if<Address>(&address))
      {
        // .loki case
        handleGotPathToService(*addr);
      }
      else if (auto* router_id = std::get_if<RouterID>(&address))
      {
        // .snode case
        handleResolvedSNodeName(*router_id);
      }
      else
      {
        // fallback case
        // XXX: never should happen but we'll handle it anyways
        resultHandler({});
      }
    };

    // handles when we know a long address of a remote resource
    auto handleGotAddress = [resultHandler, handleGotPathTo, this](AddressVariant_t address) {
      // we will attempt a build to whatever we looked up
      const auto result = EnsurePathTo(
          address,
          [address, handleGotPathTo](auto maybe_tag) { handleGotPathTo(maybe_tag, address); },
          PathAlignmentTimeout());

      // on path build start fail short circuit
      if (not result)
        resultHandler({});
    };

    // look up this name async and start the entire chain of events
    lookup_name(name, [handleGotAddress, resultHandler](oxen::quic::message m) mutable {
      if (m)
      {
        std::string name;
        try
        {
          oxenc::bt_dict_consumer btdc{m.body()};
          name = btdc.require<std::string>("NAME");
        }
        catch (...)
        {
          log::warning(link_cat, "Failed to parse find name response!");
          throw;
        }

        if (auto saddr = service::Address(); saddr.FromString(name))
          handleGotAddress(saddr);

        if (auto rid = RouterID(); rid.FromString(name))
          handleGotAddress(rid);
      }
      else
      {
        resultHandler({});
      }
    });
  }

  bool
  Endpoint::IntrosetIsStale() const
  {
    return intro_set().HasExpiredIntros(llarp::time_now_ms());
  }

  util::StatusObject
  Endpoint::ExtractStatus() const
  {
    auto obj = path::Builder::ExtractStatus();
    obj["exitMap"] = _exit_map.ExtractStatus();
    obj["identity"] = _identity.pub.Addr().ToString();
    obj["networkReady"] = ReadyForNetwork();

    util::StatusObject authCodes;
    for (const auto& [service, info] : _remote_auth_infos)
    {
      authCodes[service.ToString()] = info.token;
    }
    obj["authCodes"] = authCodes;

    return _state->ExtractStatus(obj);
  }

  void
  Endpoint::Tick(llarp_time_t)
  {
    const auto now = llarp::time_now_ms();
    path::Builder::Tick(now);
    // publish descriptors
    if (ShouldPublishDescriptors(now))
    {
      regen_and_publish_introset();
    }
    // decay introset lookup filter
    _introset_lookup_filter.Decay(now);
    // expire name cache
    _state->nameCache.Decay(now);
    // expire snode sessions
    EndpointUtil::ExpireSNodeSessions(now, _state->snode_sessions);
    // expire pending router lookups
    EndpointUtil::ExpirePendingRouterLookups(now, _state->pending_routers);

    // deregister dead sessions
    EndpointUtil::DeregisterDeadSessions(now, _state->dead_sessions);
    // tick remote sessions
    EndpointUtil::TickRemoteSessions(
        now, _state->remote_sessions, _state->dead_sessions, Sessions());
    // expire convotags
    EndpointUtil::ExpireConvoSessions(now, Sessions());

    if (NumInStatus(path::ePathEstablished) > 1)
    {
      for (const auto& item : _startup_ons_mappings)
      {
        auto& name = item.first;

        lookup_name(name, [this, name, info = item.second](oxen::quic::message m) mutable {
          if (m)
          {
            std::string result;
            try
            {
              oxenc::bt_dict_consumer btdc{m.body()};
              result = btdc.require<std::string>("NAME");
            }
            catch (...)
            {
              log::warning(link_cat, "Failed to parse find name response!");
              throw;
            }

            const auto maybe_range = info.first;
            const auto maybe_auth = info.second;

            _startup_ons_mappings.erase(name);

            if (auto saddr = service::Address(); saddr.FromString(result))
            {
              if (maybe_range.has_value())
                _exit_map.Insert(*maybe_range, saddr);
              if (maybe_auth.has_value())
                SetAuthInfoForEndpoint(saddr, *maybe_auth);
            }
          }
        });
      }
    }
  }

  bool
  Endpoint::Stop()
  {
    // stop remote sessions
    log::debug(logcat, "Endpoint stopping remote sessions.");
    EndpointUtil::StopRemoteSessions(_state->remote_sessions);
    // stop snode sessions
    log::debug(logcat, "Endpoint stopping snode sessions.");
    EndpointUtil::StopSnodeSessions(_state->snode_sessions);
    log::debug(logcat, "Endpoint stopping its path builder.");
    return path::Builder::Stop();
  }

  uint64_t
  Endpoint::GenTXID()
  {
    return randint();
  }

  std::string
  Endpoint::Name() const
  {
    return _state->name + ":" + _identity.pub.Name();
  }

  bool
  Endpoint::HasInboundConvo(const Address& addr) const
  {
    for (const auto& item : Sessions())
    {
      if (item.second.remote.Addr() == addr and item.second.inbound)
        return true;
    }
    return false;
  }

  bool
  Endpoint::HasOutboundConvo(const Address& addr) const
  {
    for (const auto& item : Sessions())
    {
      if (item.second.remote.Addr() == addr && not item.second.inbound)
        return true;
    }
    return false;
  }

  void
  Endpoint::PutSenderFor(const ConvoTag& tag, const ServiceInfo& info, bool inbound)
  {
    if (info.Addr().IsZero())
    {
      LogError(Name(), " cannot put invalid service info ", info, " T=", tag);
      return;
    }
    auto itr = Sessions().find(tag);
    if (itr == Sessions().end())
    {
      if (WantsOutboundSession(info.Addr()) and inbound)
      {
        LogWarn(
            Name(),
            " not adding sender for ",
            info.Addr(),
            " session is inbound and we want outbound T=",
            tag);
        return;
      }
      itr = Sessions().emplace(tag, Session{}).first;
      itr->second.inbound = inbound;
      itr->second.remote = info;
    }
  }

  size_t
  Endpoint::RemoveAllConvoTagsFor(service::Address remote)
  {
    size_t removed = 0;
    auto& sessions = Sessions();
    auto itr = sessions.begin();
    while (itr != sessions.end())
    {
      if (itr->second.remote.Addr() == remote)
      {
        itr = sessions.erase(itr);
        removed++;
      }
      else
        ++itr;
    }
    return removed;
  }

  bool
  Endpoint::GetSenderFor(const ConvoTag& tag, ServiceInfo& si) const
  {
    auto itr = Sessions().find(tag);
    if (itr == Sessions().end())
      return false;
    si = itr->second.remote;
    si.UpdateAddr();
    return true;
  }

  void
  Endpoint::PutIntroFor(const ConvoTag& tag, const Introduction& intro)
  {
    auto& s = Sessions()[tag];
    s.intro = intro;
  }

  bool
  Endpoint::GetIntroFor(const ConvoTag& tag, Introduction& intro) const
  {
    auto itr = Sessions().find(tag);
    if (itr == Sessions().end())
      return false;
    intro = itr->second.intro;
    return true;
  }

  void
  Endpoint::PutReplyIntroFor(const ConvoTag& tag, const Introduction& intro)
  {
    auto itr = Sessions().find(tag);
    if (itr == Sessions().end())
    {
      return;
    }
    itr->second.replyIntro = intro;
  }

  bool
  Endpoint::GetReplyIntroFor(const ConvoTag& tag, Introduction& intro) const
  {
    auto itr = Sessions().find(tag);
    if (itr == Sessions().end())
      return false;
    intro = itr->second.replyIntro;
    return true;
  }

  bool
  Endpoint::GetConvoTagsForService(const Address& addr, std::set<ConvoTag>& tags) const
  {
    return EndpointUtil::GetConvoTagsForService(Sessions(), addr, tags);
  }

  bool
  Endpoint::GetCachedSessionKeyFor(const ConvoTag& tag, SharedSecret& secret) const
  {
    auto itr = Sessions().find(tag);
    if (itr == Sessions().end())
      return false;
    secret = itr->second.sharedKey;
    return true;
  }

  void
  Endpoint::PutCachedSessionKeyFor(const ConvoTag& tag, const SharedSecret& k)
  {
    auto itr = Sessions().find(tag);
    if (itr == Sessions().end())
    {
      itr = Sessions().emplace(tag, Session{}).first;
    }
    itr->second.sharedKey = k;
  }

  void
  Endpoint::ConvoTagTX(const ConvoTag& tag)
  {
    if (Sessions().count(tag))
      Sessions()[tag].TX();
  }

  void
  Endpoint::ConvoTagRX(const ConvoTag& tag)
  {
    if (Sessions().count(tag))
      Sessions()[tag].RX();
  }

  bool
  Endpoint::LoadKeyFile()
  {
    const auto& keyfile = _state->key_file;
    if (!keyfile.empty())
    {
      _identity.EnsureKeys(keyfile, router()->key_manager()->needBackup());
    }
    else
    {
      _identity.RegenerateKeys();
    }
    return true;
  }

  bool
  Endpoint::Start()
  {
    // this does network isolation
    while (_state->on_init_callbacks.size())
    {
      if (_state->on_init_callbacks.front()())
        _state->on_init_callbacks.pop_front();
      else
      {
        LogWarn("Can't call init of network isolation");
        return false;
      }
    }
    return true;
  }

  // Keep this here (rather than the header) so that we don't need to include endpoint_state.hpp
  // in endpoint.hpp for the unique_ptr member destructor.
  Endpoint::~Endpoint() = default;

  void
  Endpoint::regen_and_publish_introset()
  {
    const auto now = llarp::time_now_ms();
    _last_introset_regen_attempt = now;
    std::set<Introduction, CompareIntroTimestamp> intros;

    if (const auto maybe =
            GetCurrentIntroductionsWithFilter([now](const service::Introduction& intro) -> bool {
              return not intro.ExpiresSoon(now, path::INTRO_STALE_THRESHOLD);
            }))
    {
      intros.insert(maybe->begin(), maybe->end());
    }
    else
    {
      LogWarn(
          "could not publish descriptors for endpoint ",
          Name(),
          " because we couldn't get enough valid introductions");
      BuildOne();
      return;
    }

    intro_set().supported_protocols.clear();

    // add supported ethertypes
    if (HasIfAddr())
    {
      if (IPRange::V4MappedRange().Contains(GetIfAddr()))
      {
        intro_set().supported_protocols.push_back(ProtocolType::TrafficV4);
      }
      else
      {
        intro_set().supported_protocols.push_back(ProtocolType::TrafficV6);
      }

      // exit related stuffo
      if (_state->is_exit_enabled)
      {
        intro_set().supported_protocols.push_back(ProtocolType::Exit);
        intro_set().exit_policy = GetExitPolicy();
        intro_set().owned_ranges = GetOwnedRanges();
      }
    }
    // add quic ethertype if we have listeners set up
    // if (auto* quic = GetQUICTunnel())
    // {
    // TODO:
    // if (quic->hasListeners())
    //   intro_set().supported_protocols.push_back(ProtocolType::QUIC);
    // }

    intro_set().intros.clear();
    for (auto& intro : intros)
    {
      if (intro_set().intros.size() < numDesiredPaths)
        intro_set().intros.emplace_back(std::move(intro));
    }
    if (intro_set().intros.empty())
    {
      LogWarn("not enough intros to publish introset for ", Name());
      if (ShouldBuildMore(now))
        ManualRebuild(1);
      return;
    }
    auto maybe = _identity.encrypt_and_sign_introset(intro_set(), now);
    if (not maybe)
    {
      LogWarn("failed to generate introset for endpoint ", Name());
      return;
    }
    if (publish_introset(*maybe))
    {
      LogInfo("(re)publishing introset for endpoint ", Name());
    }
    else
    {
      LogWarn("failed to publish intro set for endpoint ", Name());
    }
  }

  bool
  Endpoint::publish_introset(const EncryptedIntroSet& introset)
  {
    const auto paths = GetManyPathsWithUniqueEndpoints(
        this, INTROSET_RELAY_REDUNDANCY, dht::Key_t{introset.derivedSigningKey.as_array()});

    if (paths.size() != INTROSET_RELAY_REDUNDANCY)
    {
      LogWarn(
          "Cannot publish intro set because we only have ",
          paths.size(),
          " paths, but need ",
          INTROSET_RELAY_REDUNDANCY);
      return false;
    }

    for (const auto& path : paths)
    {
      for (size_t i = 0; i < INTROSET_REQS_PER_RELAY; ++i)
      {
        router()->send_control_message(path->upstream(), "publish_intro", introset.bt_encode());
      }
    }

    return true;
  }

  size_t
  Endpoint::UniqueEndpoints() const
  {
    return _state->remote_sessions.size() + _state->snode_sessions.size();
  }

  [[maybe_unused]] constexpr auto PublishIntrosetTimeout = 20s;

  void
  Endpoint::ResetInternalState()
  {
    path::Builder::ResetInternalState();
    static auto resetState = [](auto& container, auto getter) {
      std::for_each(container.begin(), container.end(), [getter](auto& item) {
        getter(item)->ResetInternalState();
      });
    };
    resetState(_state->remote_sessions, [](const auto& item) { return item.second; });
    resetState(_state->snode_sessions, [](const auto& item) { return item.second; });
  }

  bool
  Endpoint::ShouldPublishDescriptors(llarp_time_t now) const
  {
    if (not _publish_introset)
      return false;

    const auto lastEventAt = std::max(_state->last_publish_attempt, _state->last_publish);
    const auto next_pub = lastEventAt
        + (_state->local_introset.HasStaleIntros(now, path::INTRO_STALE_THRESHOLD)
               ? IntrosetPublishRetryCooldown
               : IntrosetPublishInterval);

    return now >= next_pub;
  }

  std::optional<std::vector<RouterContact>>
  Endpoint::GetHopsForBuild()
  {
    std::unordered_set<RouterID> exclude;
    ForEachPath([&exclude](auto path) { exclude.insert(path->Endpoint()); });
    const auto maybe =
        router()->node_db()->GetRandom([exclude, r = router()](const auto& rc) -> bool {
          return exclude.count(rc.pubkey) == 0
              and not r->router_profiling().IsBadForPath(rc.pubkey);
        });
    if (not maybe.has_value())
      return std::nullopt;
    return GetHopsForBuildWithEndpoint(maybe->router_id());
  }

  std::optional<std::vector<RouterContact>>
  Endpoint::GetHopsForBuildWithEndpoint(RouterID endpoint)
  {
    return path::Builder::GetHopsAlignedToForBuild(endpoint, SnodeBlacklist());
  }

  constexpr auto MaxOutboundContextPerRemote = 1;

  void
  Endpoint::PutNewOutboundContext(const service::IntroSet& introset, llarp_time_t)
  {
    const Address addr{introset.address_keys.Addr()};

    auto& remoteSessions = _state->remote_sessions;

    if (remoteSessions.count(addr) < MaxOutboundContextPerRemote)
    {
      remoteSessions.emplace(addr, std::make_shared<OutboundContext>(introset, this));
      LogInfo("Created New outbound context for ", addr.ToString());
    }

    auto sessionRange = remoteSessions.equal_range(addr);
    for (auto itr = sessionRange.first; itr != sessionRange.second; ++itr)
    {
      // TODO:
      // itr->second->AddReadyHook(
      //     [addr, this](auto session) { InformPathToService(addr, session); }, left);
    }
  }

  bool
  Endpoint::HasExit() const
  {
    for (const auto& [name, info] : _startup_ons_mappings)
    {
      if (info.first.has_value())
        return true;
    }

    return not _exit_map.Empty();
  }

  auto
  Endpoint::GetUniqueEndpointsForLookup() const
  {
    path::UniqueEndpointSet_t paths;

    ForEachPath([&paths](auto path) {
      if (path and path->IsReady())
        paths.insert(path);
    });

    return paths;
  }

  bool
  Endpoint::ReadyForNetwork() const
  {
    return is_ready() and ReadyToDoLookup(GetUniqueEndpointsForLookup().size());
  }

  bool
  Endpoint::ReadyToDoLookup(size_t num_paths) const
  {
    // Currently just checks the number of paths, but could do more checks in the future.
    return num_paths >= MIN_ONS_LOOKUP_ENDPOINTS;
  }

  void
  Endpoint::lookup_name(std::string name, std::function<void(oxen::quic::message)> func)
  {
    // TODO: so fuck all this?

    // if (not is_valid_name(name))
    // {
    //   handler(parse_address(name));
    //   return;
    // }

    // auto& cache = _state->nameCache;
    // const auto maybe = cache.Get(name);
    // if (maybe.has_value())
    // {
    //   handler(maybe);
    //   return;
    // }

    log::info(link_cat, "{} looking up ONS name {}", Name(), name);
    auto paths = GetUniqueEndpointsForLookup();

    // // not enough paths
    // if (not ReadyToDoLookup(paths.size()))
    // {
    //   LogWarn(
    //       Name(),
    //       " not enough paths for lns lookup, have ",
    //       paths.size(),
    //       " need ",
    //       MIN_ONS_LOOKUP_ENDPOINTS);
    //   handler(std::nullopt);
    //   return;
    // }

    // pick up to max_unique_lns_endpoints random paths to do lookups from
    std::vector<path::Path_ptr> chosenpaths;
    chosenpaths.insert(chosenpaths.begin(), paths.begin(), paths.end());
    std::shuffle(chosenpaths.begin(), chosenpaths.end(), llarp::csrng);
    chosenpaths.resize(std::min(paths.size(), MAX_ONS_LOOKUP_ENDPOINTS));

    for (const auto& path : chosenpaths)
    {
      log::info(link_cat, "{} lookup {} from {}", Name(), name, path->Endpoint());
      path->find_name(name, func);
    }
  }

  void
  Endpoint::EnsureRouterIsKnown(const RouterID& rid)
  {
    if (rid.IsZero())
      return;
    if (!router()->node_db()->has_router(rid))
    {
      lookup_router(rid);
    }
  }

  bool
  Endpoint::lookup_router(RouterID rid, std::function<void(oxen::quic::message)> func)
  {
    const auto& routers = _state->pending_routers;

    if (routers.find(rid) == routers.end())
    {
      auto path = GetEstablishedPathClosestTo(rid);
      path->find_router("find_router", func);
      return true;
    }

    return false;
  }

  void
  Endpoint::HandlePathBuilt(path::Path_ptr p)
  {
    // p->SetDataHandler(util::memFn(&Endpoint::HandleHiddenServiceFrame, this));
    // p->SetDropHandler(util::memFn(&Endpoint::HandleDataDrop, this));
    // p->SetDeadChecker(util::memFn(&Endpoint::CheckPathIsDead, this));
    path::Builder::HandlePathBuilt(p);
  }

  bool
  Endpoint::HandleDataDrop(path::Path_ptr p, const PathID_t& dst, uint64_t seq)
  {
    LogWarn(Name(), " message ", seq, " dropped by endpoint ", p->Endpoint(), " via ", dst);
    return true;
  }

  std::unordered_map<std::string, std::string>
  Endpoint::NotifyParams() const
  {
    return {{"LOKINET_ADDR", _identity.pub.Addr().ToString()}};
  }

  void
  Endpoint::FlushRecvData()
  {
    while (auto maybe = _recv_event_queue.tryPopFront())
    {
      auto& ev = *maybe;
      ProtocolMessage::ProcessAsync(ev.fromPath, ev.pathid, ev.msg);
    }
  }

  void
  Endpoint::QueueRecvData(RecvDataEvent ev)
  {
    _recv_event_queue.tryPushBack(std::move(ev));
    router()->TriggerPump();
  }

  bool
  Endpoint::HandleDataMessage(
      path::Path_ptr p, const PathID_t from, std::shared_ptr<ProtocolMessage> msg)
  {
    PutSenderFor(msg->tag, msg->sender, true);
    Introduction intro = msg->introReply;

    if (HasInboundConvo(msg->sender.Addr()))
    {
      intro.path_id = from;
      intro.router = p->Endpoint();
    }

    PutReplyIntroFor(msg->tag, intro);
    ConvoTagRX(msg->tag);
    return ProcessDataMessage(msg);
  }

  bool
  Endpoint::HasPathToSNode(const RouterID ident) const
  {
    auto range = _state->snode_sessions.equal_range(ident);
    auto itr = range.first;
    while (itr != range.second)
    {
      if (itr->second->IsReady())
      {
        return true;
      }
      ++itr;
    }
    return false;
  }

  EndpointBase::AddressVariant_t
  Endpoint::LocalAddress() const
  {
    return _identity.pub.Addr();
  }

  std::optional<EndpointBase::SendStat>
  Endpoint::GetStatFor(AddressVariant_t) const
  {
    // TODO: implement me
    return std::nullopt;
  }

  std::unordered_set<EndpointBase::AddressVariant_t>
  Endpoint::AllRemoteEndpoints() const
  {
    std::unordered_set<AddressVariant_t> remote;
    for (const auto& item : Sessions())
    {
      remote.insert(item.second.remote.Addr());
    }
    for (const auto& item : _state->snode_sessions)
    {
      remote.insert(item.first);
    }
    return remote;
  }

  bool
  Endpoint::ProcessDataMessage(std::shared_ptr<ProtocolMessage> msg)
  {
    if ((msg->proto == ProtocolType::Exit
         && (_state->is_exit_enabled || _exit_map.ContainsValue(msg->sender.Addr())))
        || msg->proto == ProtocolType::TrafficV4 || msg->proto == ProtocolType::TrafficV6
        || (msg->proto == ProtocolType::QUIC and _tunnel_manager))
    {
      _inbound_queue.tryPushBack(std::move(msg));
      router()->TriggerPump();
      return true;
    }
    if (msg->proto == ProtocolType::Control)
    {
      // TODO: implement me (?)
      // right now it's just random noise
      return true;
    }
    return false;
  }

  void
  Endpoint::AsyncProcessAuthMessage(
      std::shared_ptr<ProtocolMessage> msg, std::function<void(std::string, bool)> hook)
  {
    if (_auth_policy)
    {
      if (not _auth_policy->AsyncAuthPending(msg->tag))
      {
        // do 1 authentication attempt and drop everything else
        _auth_policy->AuthenticateAsync(std::move(msg), std::move(hook));
      }
    }
    else
    {
      router()->loop()->call([h = std::move(hook)] { h("OK", true); });
    }
  }

  void
  Endpoint::SendAuthResult(
      path::Path_ptr path, PathID_t /* replyPath */, ConvoTag tag, std::string result, bool success)
  {
    // not applicable because we are not an exit or don't have an endpoint auth policy
    if ((not _state->is_exit_enabled) or _auth_policy == nullptr)
      return;

    ProtocolFrameMessage f{};
    f.flag = int(not success);
    f.convo_tag = tag;
    f.path_id = path->intro.path_id;
    f.nonce.Randomize();

    if (success)
    {
      ProtocolMessage msg;
      msg.put_buffer(result);

      if (_auth_policy)
        msg.proto = ProtocolType::Auth;
      else
        msg.proto = ProtocolType::Control;

      if (not GetReplyIntroFor(tag, msg.introReply))
      {
        LogError("Failed to send auth reply: no reply intro");
        return;
      }

      msg.sender = _identity.pub;
      SharedSecret sessionKey{};

      if (not GetCachedSessionKeyFor(tag, sessionKey))
      {
        LogError("failed to send auth reply: no cached session key");
        return;
      }

      if (not f.EncryptAndSign(msg, sessionKey, _identity))
      {
        LogError("Failed to encrypt and sign auth reply");
        return;
      }
    }
    else
    {
      if (not f.Sign(_identity))
      {
        LogError("failed to sign auth reply result");
        return;
      }
    }

    // TODO:
    // _send_queue.tryPushBack(
    //     SendEvent{std::make_shared<routing::PathTransferMessage>(f, replyPath), path});
  }

  void
  Endpoint::RemoveConvoTag(const ConvoTag& t)
  {
    Sessions().erase(t);
  }

  void
  Endpoint::ResetConvoTag(ConvoTag tag, path::Path_ptr p, PathID_t /* from */)
  {
    // send reset convo tag message
    ProtocolFrameMessage f{};
    f.flag = 1;
    f.convo_tag = tag;
    f.path_id = p->intro.path_id;
    f.Sign(_identity);
    {
      LogWarn("invalidating convotag T=", tag);
      RemoveConvoTag(tag);
      // TODO:
      // _send_queue.tryPushBack(
      //     SendEvent{std::make_shared<routing::PathTransferMessage>(f, from), p});
    }
  }

  bool
  Endpoint::HandleHiddenServiceFrame(path::Path_ptr p, const ProtocolFrameMessage& frame)
  {
    if (frame.flag)
    {
      // handle discard
      ServiceInfo si;
      if (!GetSenderFor(frame.convo_tag, si))
        return false;
      // verify source
      if (!frame.Verify(si))
        return false;
      // remove convotag it doesn't exist
      LogWarn("remove convotag T=", frame.convo_tag, " R=", frame.flag, " from ", si.Addr());
      RemoveConvoTag(frame.convo_tag);
      return true;
    }
    if (not frame.AsyncDecryptAndVerify(router()->loop(), p, _identity, this))
    {
      ResetConvoTag(frame.convo_tag, p, frame.path_id);
    }
    return true;
  }

  void
  Endpoint::HandlePathDied(path::Path_ptr p)
  {
    router()->router_profiling().MarkPathTimeout(p.get());
    ManualRebuild(1);
    path::Builder::HandlePathDied(p);
    regen_and_publish_introset();
  }

  bool
  Endpoint::CheckPathIsDead(path::Path_ptr, llarp_time_t dlt)
  {
    return dlt > path::ALIVE_TIMEOUT;
  }

  void
  Endpoint::MarkAddressOutbound(service::Address addr)
  {
    _state->m_OutboundSessions.insert(addr);
  }

  bool
  Endpoint::WantsOutboundSession(const Address& addr) const
  {
    return _state->m_OutboundSessions.count(addr) > 0;
  }

  void
  Endpoint::InformPathToService(const Address remote, OutboundContext* ctx)
  {
    auto& serviceLookups = _state->pending_service_lookups;
    auto range = serviceLookups.equal_range(remote);
    auto itr = range.first;
    while (itr != range.second)
    {
      itr->second(remote, ctx);
      ++itr;
    }
    serviceLookups.erase(remote);
  }

  bool
  Endpoint::EnsurePathTo(
      std::variant<Address, RouterID> addr,
      std::function<void(std::optional<ConvoTag>)> hook,
      llarp_time_t timeout)
  {
    if (auto ptr = std::get_if<Address>(&addr))
    {
      if (*ptr == _identity.pub.Addr())
      {
        ConvoTag tag{};

        if (auto maybe = GetBestConvoTagFor(*ptr))
          tag = *maybe;
        else
          tag.Randomize();
        PutSenderFor(tag, _identity.pub, true);
        ConvoTagTX(tag);
        Sessions()[tag].forever = true;
        Loop()->call_soon([tag, hook]() { hook(tag); });
        return true;
      }
      if (not WantsOutboundSession(*ptr))
      {
        // we don't want to connect back to inbound sessions
        hook(std::nullopt);
        return true;
      }

      return EnsurePathToService(
          *ptr,
          [hook](auto, auto* ctx) -> bool {
            if (ctx)
            {
              hook(ctx->get_current_tag());
              return true;
            }

            hook(std::nullopt);
            return false;
          },
          timeout);
    }
    if (auto ptr = std::get_if<RouterID>(&addr))
    {
      return EnsurePathToSNode(*ptr, [hook](auto, auto session, auto tag) {
        if (session)
        {
          hook(tag);
        }
        else
        {
          hook(std::nullopt);
        }
      });
    }
    return false;
  }

  bool
  Endpoint::EnsurePathToSNode(
      const RouterID snode,
      std::function<void(const RouterID, exit::BaseSession_ptr, ConvoTag)> hook)
  {
    auto& nodeSessions = _state->snode_sessions;

    using namespace std::placeholders;
    if (nodeSessions.count(snode) == 0)
    {
      const auto src = xhtonl(net::TruncateV6(GetIfAddr()));
      const auto dst = xhtonl(net::TruncateV6(ObtainIPForAddr(snode)));

      auto session = std::make_shared<exit::SNodeSession>(
          snode,
          [=](const llarp_buffer_t& buf) -> bool {
            net::IPPacket pkt;
            if (not pkt.Load(buf))
              return false;
            pkt.UpdateIPv4Address(src, dst);
            /// TODO: V6
            auto itr = _state->snode_sessions.find(snode);
            if (itr == _state->snode_sessions.end())
              return false;
            if (const auto maybe = itr->second->CurrentPath())
              return HandleInboundPacket(
                  ConvoTag{maybe->as_array()}, pkt.ConstBuffer(), ProtocolType::TrafficV4, 0);
            return false;
          },
          router(),
          1,
          numHops,
          false,
          this);
      _state->snode_sessions[snode] = session;
    }
    EnsureRouterIsKnown(snode);
    auto range = nodeSessions.equal_range(snode);
    auto itr = range.first;
    while (itr != range.second)
    {
      if (itr->second->IsReady())
        hook(snode, itr->second, ConvoTag{itr->second->CurrentPath()->as_array()});
      else
      {
        itr->second->AddReadyHook([hook, snode](auto session) {
          if (session)
          {
            hook(snode, session, ConvoTag{session->CurrentPath()->as_array()});
          }
          else
          {
            hook(snode, nullptr, ConvoTag{});
          }
        });
        if (not itr->second->BuildCooldownHit(Now()))
          itr->second->BuildOne();
      }
      ++itr;
    }
    return true;
  }

  bool
  Endpoint::EnsurePathToService(
      const Address remote,
      std::function<void(Address, OutboundContext*)> hook,
      [[maybe_unused]] llarp_time_t timeout)
  {
    if (not WantsOutboundSession(remote))
    {
      // we don't want to ensure paths to addresses that are inbound
      // inform fail right away in that case
      hook(remote, nullptr);
      return false;
    }

    /// how many routers to use for lookups
    static constexpr size_t NumParallelLookups = 2;

    // add response hook to list for address.
    _state->pending_service_lookups.emplace(remote, hook);

    auto& sessions = _state->remote_sessions;
    {
      auto range = sessions.equal_range(remote);
      auto itr = range.first;
      while (itr != range.second)
      {
        if (itr->second->ReadyToSend())
        {
          InformPathToService(remote, itr->second.get());
          return true;
        }
        ++itr;
      }
    }
    /// check replay filter
    if (not _introset_lookup_filter.Insert(remote))
      return true;

    const auto paths = GetManyPathsWithUniqueEndpoints(this, NumParallelLookups);

    const dht::Key_t location = remote.ToKey();

    // flag to only add callback to list of callbacks for
    // address once.
    bool hookAdded = false;

    for (const auto& path : paths)
    {
      path->find_intro(location, false, 0, [this, hook](oxen::quic::message m) mutable {
        if (m)
        {
          std::string introset;

          try
          {
            oxenc::bt_dict_consumer btdc{m.body()};
            introset = btdc.require<std::string>("INTROSET");
          }
          catch (...)
          {
            log::warning(link_cat, "Failed to parse find name response!");
            throw;
          }

          service::EncryptedIntroSet enc{introset};
          router()->contacts()->services()->PutNode(std::move(enc));

          // TODO: finish this
        }
      });
    }
    return hookAdded;
  }

  void
  Endpoint::SRVRecordsChanged()
  {
    auto& introset = intro_set();
    introset.SRVs.clear();
    for (const auto& srv : SRVRecords())
      introset.SRVs.emplace_back(srv.toTuple());

    regen_and_publish_introset();
  }

  bool
  Endpoint::send_to(ConvoTag tag, std::string payload)
  {
    if (tag.IsZero())
    {
      log::warning(link_cat, "SendToOrQueue failed: convo tag is zero");
      return false;
    }

    log::debug(link_cat, "{} sending {} bytes (Tag: {})", Name(), payload.size(), tag);

    if (auto maybe = GetEndpointWithConvoTag(tag))
    {
      if (auto rid = std::get_if<RouterID>(&*maybe))
      {
        return router()->send_data_message(*rid, payload);
      }
      if (auto saddr = std::get_if<Address>(&*maybe))
      {
        return router()->send_data_message(saddr->ToRouter(), payload);
      }
    }

    log::debug(link_cat, "SendToOrQueue failed: no endpoint for convo tag {}", tag);
    return false;
  }

  void
  Endpoint::Pump(llarp_time_t)
  {
    FlushRecvData();
    // send downstream packets to user for snode
    for (const auto& [router, session] : _state->snode_sessions)
      session->FlushDownstream();

    // handle inbound traffic sorted
    util::ascending_priority_queue<ProtocolMessage> queue;

    while (not _inbound_queue.empty())
    {
      // succ it out
      queue.emplace(std::move(*_inbound_queue.popFront()));
    }

    while (not queue.empty())
    {
      const auto& msg = queue.top();
      log::debug(
          logcat,
          "{} handling inbound packet (size {}B) on tag {}",
          Name(),
          msg.tag,
          msg.payload.size());

      // if (HandleInboundPacket(msg.tag, msg.payload, msg.proto, msg.seqno))
      // {
      //   ConvoTagRX(msg.tag);
      // }
      // else
      // {
      //   LogWarn("Failed to handle inbound message");
      // }

      queue.pop();
    }

    auto r = router();

    // TODO: locking on this container
    // for (const auto& [addr, outctx] : _state->remote_sessions)
    // {
    //   outctx->FlushUpstream();
    //   outctx->Pump(now);
    // }
    // // TODO: locking on this container
    // for (const auto& [r, session] : _state->snode_sessions)
    //   session->FlushUpstream();

    // // send queue flush
    // while (not _send_queue.empty())
    // {
    //   SendEvent item = _send_queue.popFront();
    //   item.first->sequence_number = item.second->NextSeqNo();
    //   if (item.second->SendRoutingMessage(*item.first, r))
    //     ConvoTagTX(item.first->protocol_frame_msg.convo_tag);
    // }

    UpstreamFlush(r);
  }

  std::optional<ConvoTag>
  Endpoint::GetBestConvoTagFor(std::variant<Address, RouterID> remote) const
  {
    // get convotag with lowest estimated RTT
    if (auto ptr = std::get_if<Address>(&remote))
    {
      llarp_time_t rtt = 30s;
      std::optional<ConvoTag> ret = std::nullopt;
      for (const auto& [tag, session] : Sessions())
      {
        if (tag.IsZero())
          continue;
        if (session.remote.Addr() == *ptr)
        {
          if (*ptr == _identity.pub.Addr())
          {
            return tag;
          }
          if (session.inbound)
          {
            auto path = GetPathByRouter(session.replyIntro.router);
            // if we have no path to the remote router that's fine still use it just in case this
            // is the ONLY one we have
            if (path == nullptr)
            {
              ret = tag;
              continue;
            }

            if (path and path->IsReady())
            {
              const auto rttEstimate = (session.replyIntro.latency + path->intro.latency) * 2;
              if (rttEstimate < rtt)
              {
                ret = tag;
                rtt = rttEstimate;
              }
            }
          }
          else
          {
            auto range = _state->remote_sessions.equal_range(*ptr);
            auto itr = range.first;
            while (itr != range.second)
            {
              // TODO:
              // if (itr->second->ReadyToSend() and itr->second->estimatedRTT > 0s)
              // {
              //   if (itr->second->estimatedRTT < rtt)
              //   {
              //     ret = tag;
              //     rtt = itr->second->estimatedRTT;
              //   }
              // }
              itr++;
            }
          }
        }
      }
      return ret;
    }
    if (auto* ptr = std::get_if<RouterID>(&remote))
    {
      auto itr = _state->snode_sessions.find(*ptr);
      if (itr == _state->snode_sessions.end())
        return std::nullopt;
      if (auto maybe = itr->second->CurrentPath())
        return ConvoTag{maybe->as_array()};
    }
    return std::nullopt;
  }

  bool
  Endpoint::HasConvoTag(const ConvoTag& t) const
  {
    return Sessions().find(t) != Sessions().end();
  }

  std::optional<uint64_t>
  Endpoint::GetSeqNoForConvo(const ConvoTag& tag)
  {
    auto itr = Sessions().find(tag);
    if (itr == Sessions().end())
      return std::nullopt;
    return itr->second.seqno++;
  }

  bool
  Endpoint::ShouldBuildMore(llarp_time_t now) const
  {
    if (BuildCooldownHit(now))
      return false;
    const auto requiredPaths = std::max(numDesiredPaths, path::MIN_INTRO_PATHS);
    if (NumInStatus(path::ePathBuilding) >= requiredPaths)
      return false;
    return NumPathsExistingAt(now + (path::DEFAULT_LIFETIME - path::INTRO_PATH_SPREAD))
        < requiredPaths;
  }

  Router*
  Endpoint::router()
  {
    return _state->router;
  }

  const EventLoop_ptr&
  Endpoint::Loop()
  {
    return router()->loop();
  }

  void
  Endpoint::BlacklistSNode(const RouterID snode)
  {
    _state->snode_blacklist.insert(snode);
  }

  const std::set<RouterID>&
  Endpoint::SnodeBlacklist() const
  {
    return _state->snode_blacklist;
  }

  const IntroSet&
  Endpoint::intro_set() const
  {
    return _state->local_introset;
  }

  IntroSet&
  Endpoint::intro_set()
  {
    return _state->local_introset;
  }

  const std::unordered_map<ConvoTag, Session>&
  Endpoint::Sessions() const
  {
    return _state->m_Sessions;
  }

  std::unordered_map<ConvoTag, Session>&
  Endpoint::Sessions()
  {
    return _state->m_Sessions;
  }

  void
  Endpoint::SetAuthInfoForEndpoint(Address addr, AuthInfo info)
  {
    if (info.token.empty())
    {
      _remote_auth_infos.erase(addr);
      return;
    }
    _remote_auth_infos[addr] = std::move(info);
  }

  void
  Endpoint::MapExitRange(IPRange range, Address exit)
  {
    if (not exit.IsZero())
      LogInfo(Name(), " map ", range, " to exit at ", exit);
    _exit_map.Insert(range, exit);
  }
  bool
  Endpoint::HasFlowToService(Address addr) const
  {
    return HasOutboundConvo(addr) or HasInboundConvo(addr);
  }

  void
  Endpoint::UnmapExitRange(IPRange range)
  {
    // unmap all ranges that fit in the range we gave
    _exit_map.RemoveIf([&](const auto& item) -> bool {
      if (not range.Contains(item.first))
        return false;
      LogInfo(Name(), " unmap ", item.first, " exit range mapping");
      return true;
    });

    if (_exit_map.Empty())
      router()->route_poker()->put_down();
  }

  void
  Endpoint::UnmapRangeByExit(IPRange range, std::string exit)
  {
    // unmap all ranges that match the given exit when hot swapping
    _exit_map.RemoveIf([&](const auto& item) -> bool {
      if ((range.Contains(item.first)) and (item.second.ToString() == exit))
      {
        log::info(logcat, "{} unmap {} range mapping to exit node {}", Name(), item.first, exit);
        return true;
      }
      return false;
    });

    if (_exit_map.Empty())
      router()->route_poker()->put_down();
  }

  std::optional<AuthInfo>
  Endpoint::MaybeGetAuthInfoForEndpoint(Address remote)
  {
    const auto itr = _remote_auth_infos.find(remote);

    if (itr == _remote_auth_infos.end())
      return std::nullopt;

    return itr->second;
  }

  link::TunnelManager*
  Endpoint::GetQUICTunnel()
  {
    return _tunnel_manager.get();
  }

}  // namespace llarp::service