lokinet/llarp/service/endpoint.cpp

#include <chrono>
#include <memory>
#include <service/endpoint.hpp>

#include <dht/context.hpp>
#include <dht/key.hpp>
#include <dht/messages/findintro.hpp>
#include <dht/messages/findname.hpp>
#include <dht/messages/findrouter.hpp>
#include <dht/messages/gotintro.hpp>
#include <dht/messages/gotname.hpp>
#include <dht/messages/gotrouter.hpp>
#include <dht/messages/pubintro.hpp>
#include <nodedb.hpp>
#include <profiling.hpp>
#include <router/abstractrouter.hpp>
#include <routing/dht_message.hpp>
#include <routing/path_transfer_message.hpp>
#include <service/endpoint_state.hpp>
#include <service/endpoint_util.hpp>
#include <service/hidden_service_address_lookup.hpp>
#include <service/outbound_context.hpp>
#include <service/protocol.hpp>
#include <util/thread/logic.hpp>
#include <util/str.hpp>
#include <util/buffer.hpp>
#include <util/meta/memfn.hpp>
#include <hook/shell.hpp>
#include <link/link_manager.hpp>
#include <tooling/dht_event.hpp>

#include <utility>

namespace llarp
{
  namespace service
  {
    Endpoint::Endpoint(AbstractRouter* r, Context* parent)
        : path::Builder(r, 3, path::default_len)
        , context(parent)
        , m_InboundTrafficQueue(512)
        , m_SendQueue(512)
        , m_RecvQueue(512)
    {
      m_state = std::make_unique<EndpointState>();
      m_state->m_Router = r;
      m_state->m_Name = "endpoint";
      m_RecvQueue.enable();
    }

    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;
        m_StartupLNSMappings[name] = std::make_pair(range, auth);
      });

      return m_state->Configure(conf);
    }

    llarp_ev_loop_ptr
    Endpoint::EndpointNetLoop()
    {
      if (m_state->m_IsolatedNetLoop)
        return m_state->m_IsolatedNetLoop;

      return Router()->netloop();
    }

    bool
    Endpoint::NetworkIsIsolated() const
    {
      return m_state->m_IsolatedLogic.get() != nullptr && m_state->m_IsolatedNetLoop != nullptr;
    }

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

    void
    Endpoint::RegenAndPublishIntroSet(bool forceRebuild)
    {
      const auto now = llarp::time_now_ms();
      std::set<Introduction> introset;
      if (!GetCurrentIntroductionsWithFilter(
              introset, [now](const service::Introduction& intro) -> bool {
                return not intro.ExpiresSoon(now, path::min_intro_lifetime);
              }))
      {
        LogWarn(
            "could not publish descriptors for endpoint ",
            Name(),
            " because we couldn't get enough valid introductions");
        if (ShouldBuildMore(now) || forceRebuild)
          ManualRebuild(1);
        return;
      }
      introSet().I.clear();
      for (auto& intro : introset)
      {
        introSet().I.emplace_back(std::move(intro));
      }
      if (introSet().I.size() == 0)
      {
        LogWarn("not enough intros to publish introset for ", Name());
        if (ShouldBuildMore(now) || forceRebuild)
          ManualRebuild(1);
        return;
      }
      auto maybe = m_Identity.EncryptAndSignIntroSet(introSet(), now);
      if (not maybe)
      {
        LogWarn("failed to generate introset for endpoint ", Name());
        return;
      }
      if (PublishIntroSet(*maybe, Router()))
      {
        LogInfo("(re)publishing introset for endpoint ", Name());
      }
      else
      {
        LogWarn("failed to publish intro set for endpoint ", Name());
      }
    }

    bool
    Endpoint::IsReady() const
    {
      const auto now = Now();
      if (introSet().I.size() == 0)
        return false;
      if (introSet().IsExpired(now))
        return false;
      return true;
    }

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

    bool
    Endpoint::GetEndpointWithConvoTag(
        const ConvoTag tag, llarp::AlignedBuffer<32>& addr, bool& snode) const
    {
      auto itr = Sessions().find(tag);
      if (itr != Sessions().end())
      {
        snode = false;
        addr = itr->second.remote.Addr();
        return true;
      }

      for (const auto& item : m_state->m_SNodeSessions)
      {
        if (item.second.second == tag)
        {
          snode = true;
          addr = item.first;
          return true;
        }
      }

      return false;
    }

    bool
    Endpoint::IntrosetIsStale() const
    {
      return introSet().HasExpiredIntros(Now());
    }

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

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

      return m_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))
      {
        RegenAndPublishIntroSet();
      }

      // expire name cache
      m_state->nameCache.Decay(now);
      // expire snode sessions
      EndpointUtil::ExpireSNodeSessions(now, m_state->m_SNodeSessions);
      // expire pending tx
      EndpointUtil::ExpirePendingTx(now, m_state->m_PendingLookups);
      // expire pending router lookups
      EndpointUtil::ExpirePendingRouterLookups(now, m_state->m_PendingRouters);

      // deregister dead sessions
      EndpointUtil::DeregisterDeadSessions(now, m_state->m_DeadSessions);
      // tick remote sessions
      EndpointUtil::TickRemoteSessions(
          now, m_state->m_RemoteSessions, m_state->m_DeadSessions, Sessions());
      // expire convotags
      EndpointUtil::ExpireConvoSessions(now, Sessions());

      if (NumInStatus(path::ePathEstablished) > 1)
      {
        for (const auto& item : m_StartupLNSMappings)
        {
          LookupNameAsync(
              item.first, [name = item.first, info = item.second, this](auto maybe_addr) {
                if (maybe_addr.has_value())
                {
                  const auto maybe_range = info.first;
                  const auto maybe_auth = info.second;

                  m_StartupLNSMappings.erase(name);

                  if (maybe_range.has_value())
                    m_ExitMap.Insert(*maybe_range, *maybe_addr);

                  if (maybe_auth.has_value())
                    SetAuthInfoForEndpoint(*maybe_addr, *maybe_auth);
                }
              });
        }
      }
    }

    bool
    Endpoint::Stop()
    {
      // stop remote sessions
      EndpointUtil::StopRemoteSessions(m_state->m_RemoteSessions);
      // stop snode sessions
      EndpointUtil::StopSnodeSessions(m_state->m_SNodeSessions);
      if (m_OnDown)
        m_OnDown->NotifyAsync(NotifyParams());
      return path::Builder::Stop();
    }

    uint64_t
    Endpoint::GenTXID()
    {
      uint64_t txid = randint();
      const auto& lookups = m_state->m_PendingLookups;
      while (lookups.find(txid) != lookups.end())
        ++txid;
      return txid;
    }

    std::string
    Endpoint::Name() const
    {
      return m_state->m_Name + ":" + m_Identity.pub.Name();
    }

    void
    Endpoint::PutLookup(IServiceLookup* lookup, uint64_t txid)
    {
      m_state->m_PendingLookups.emplace(txid, std::unique_ptr<IServiceLookup>(lookup));
    }

    bool
    Endpoint::HandleGotIntroMessage(dht::GotIntroMessage_constptr msg)
    {
      std::set<EncryptedIntroSet> remote;
      for (const auto& introset : msg->found)
      {
        if (not introset.Verify(Now()))
        {
          LogError(Name(), " got invalid introset");
          return false;
        }
        remote.insert(introset);
      }
      auto& lookups = m_state->m_PendingLookups;
      auto itr = lookups.find(msg->txid);
      if (itr == lookups.end())
      {
        LogWarn(
            "invalid lookup response for hidden service endpoint ", Name(), " txid=", msg->txid);
        return true;
      }
      std::unique_ptr<IServiceLookup> lookup = std::move(itr->second);
      lookups.erase(itr);
      lookup->HandleIntrosetResponse(remote);
      return true;
    }

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

    void
    Endpoint::PutSenderFor(const ConvoTag& tag, const ServiceInfo& info, bool inbound)
    {
      auto itr = Sessions().find(tag);
      if (itr == Sessions().end())
      {
        itr = Sessions().emplace(tag, Session{}).first;
        itr->second.inbound = inbound;
        itr->second.remote = info;
      }
      itr->second.lastUsed = Now();
    }

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

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

    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;
      itr->second.lastUsed = Now();
    }

    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;
      itr->second.lastUsed = Now();
    }

    void
    Endpoint::MarkConvoTagActive(const ConvoTag& tag)
    {
      auto itr = Sessions().find(tag);
      if (itr != Sessions().end())
      {
        itr->second.lastUsed = Now();
      }
    }

    bool
    Endpoint::LoadKeyFile()
    {
      const auto& keyfile = m_state->m_Keyfile;
      if (!keyfile.empty())
      {
        m_Identity.EnsureKeys(keyfile, Router()->keyManager()->needBackup());
      }
      else
      {
        m_Identity.RegenerateKeys();
      }
      return true;
    }

    bool
    Endpoint::Start()
    {
      // how can I tell if a m_Identity isn't loaded?
      if (!m_DataHandler)
      {
        m_DataHandler = this;
      }
      // this does network isolation
      while (m_state->m_OnInit.size())
      {
        if (m_state->m_OnInit.front()())
          m_state->m_OnInit.pop_front();
        else
        {
          LogWarn("Can't call init of network isolation");
          return false;
        }
      }
      return true;
    }

    Endpoint::~Endpoint()
    {
      if (m_OnUp)
        m_OnUp->Stop();
      if (m_OnDown)
        m_OnDown->Stop();
      if (m_OnReady)
        m_OnReady->Stop();
    }

    bool
    Endpoint::PublishIntroSet(const EncryptedIntroSet& introset, AbstractRouter* r)
    {
      const auto paths = GetManyPathsWithUniqueEndpoints(this, llarp::dht::IntroSetRelayRedundancy);

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

      // do publishing for each path selected
      size_t published = 0;

      for (const auto& path : paths)
      {
        for (size_t i = 0; i < llarp::dht::IntroSetRequestsPerRelay; ++i)
        {
          r->NotifyRouterEvent<tooling::PubIntroSentEvent>(
              r->pubkey(),
              llarp::dht::Key_t{introset.derivedSigningKey.as_array()},
              RouterID(path->hops[path->hops.size() - 1].rc.pubkey),
              published);
          if (PublishIntroSetVia(introset, r, path, published))
            published++;
        }
      }
      if (published != llarp::dht::IntroSetStorageRedundancy)
        LogWarn(
            "Publish introset failed: could only publish ",
            published,
            " copies but wanted ",
            llarp::dht::IntroSetStorageRedundancy);
      return published == llarp::dht::IntroSetStorageRedundancy;
    }

    struct PublishIntroSetJob : public IServiceLookup
    {
      EncryptedIntroSet m_IntroSet;
      Endpoint* m_Endpoint;
      uint64_t m_relayOrder;
      PublishIntroSetJob(
          Endpoint* parent, uint64_t id, EncryptedIntroSet introset, uint64_t relayOrder)
          : IServiceLookup(parent, id, "PublishIntroSet")
          , m_IntroSet(std::move(introset))
          , m_Endpoint(parent)
          , m_relayOrder(relayOrder)
      {}

      std::shared_ptr<routing::IMessage>
      BuildRequestMessage() override
      {
        auto msg = std::make_shared<routing::DHTMessage>();
        msg->M.emplace_back(
            std::make_unique<dht::PublishIntroMessage>(m_IntroSet, txid, true, m_relayOrder));
        return msg;
      }

      bool
      HandleIntrosetResponse(const std::set<EncryptedIntroSet>& response) override
      {
        if (not response.empty())
          m_Endpoint->IntroSetPublished();
        else
          m_Endpoint->IntroSetPublishFail();

        return true;
      }
    };

    void
    Endpoint::IntroSetPublishFail()
    {
      auto now = Now();
      if (ShouldPublishDescriptors(now))
      {
        RegenAndPublishIntroSet();
      }
      else if (NumInStatus(path::ePathEstablished) < 3)
      {
        if (introSet().HasExpiredIntros(now))
          ManualRebuild(1);
      }
    }

    bool
    Endpoint::PublishIntroSetVia(
        const EncryptedIntroSet& introset,
        AbstractRouter* r,
        path::Path_ptr path,
        uint64_t relayOrder)
    {
      auto job = new PublishIntroSetJob(this, GenTXID(), introset, relayOrder);
      if (job->SendRequestViaPath(path, r))
      {
        m_state->m_LastPublishAttempt = Now();
        return true;
      }
      return false;
    }

    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(m_state->m_RemoteSessions, [](const auto& item) { return item.second; });
      resetState(m_state->m_SNodeSessions, [](const auto& item) { return item.second.first; });
    }

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

      auto next_pub = m_state->m_LastPublishAttempt
          + (m_state->m_IntroSet.HasExpiredIntros(now) ? INTROSET_PUBLISH_RETRY_INTERVAL
                                                       : INTROSET_PUBLISH_INTERVAL);

      return now >= next_pub;
    }

    void
    Endpoint::IntroSetPublished()
    {
      const auto now = Now();
      // We usually get 4 confirmations back (one for each DHT location), which
      // is noisy: suppress this log message if we already had a confirmation in
      // the last second.
      if (m_state->m_LastPublish < now - 1s)
        LogInfo(Name(), " IntroSet publish confirmed");
      else
        LogDebug(Name(), " Additional IntroSet publish confirmed");

      m_state->m_LastPublish = now;
      if (m_OnReady)
        m_OnReady->NotifyAsync(NotifyParams());
      m_OnReady = nullptr;
    }

    void
    Endpoint::IsolatedNetworkMainLoop()
    {
      m_state->m_IsolatedNetLoop = llarp_make_ev_loop();
      m_state->m_IsolatedLogic = std::make_shared<llarp::Logic>();
      if (SetupNetworking())
        llarp_ev_loop_run_single_process(m_state->m_IsolatedNetLoop, m_state->m_IsolatedLogic);
      else
      {
        m_state->m_IsolatedNetLoop.reset();
        m_state->m_IsolatedLogic.reset();
      }
    }

    bool
    Endpoint::SelectHop(
        llarp_nodedb* db,
        const std::set<RouterID>& prev,
        RouterContact& cur,
        size_t hop,
        path::PathRole roles)

    {
      std::set<RouterID> exclude = prev;
      for (const auto& snode : SnodeBlacklist())
        exclude.insert(snode);
      if (hop == numHops - 1 and numHops > 1)
      {
        // diversify endpoints
        ForEachPath([&exclude](const path::Path_ptr& path) { exclude.insert(path->Endpoint()); });
      }
      return path::Builder::SelectHop(db, exclude, cur, hop, roles);
    }

    void
    Endpoint::PathBuildStarted(path::Path_ptr path)
    {
      path::Builder::PathBuildStarted(path);
    }

    void
    Endpoint::PutNewOutboundContext(const service::IntroSet& introset)
    {
      Address addr;
      introset.A.CalculateAddress(addr.as_array());

      auto& remoteSessions = m_state->m_RemoteSessions;
      auto& serviceLookups = m_state->m_PendingServiceLookups;

      if (remoteSessions.count(addr) >= MAX_OUTBOUND_CONTEXT_COUNT)
      {
        auto itr = remoteSessions.find(addr);

        auto range = serviceLookups.equal_range(addr);
        auto i = range.first;
        while (i != range.second)
        {
          i->second(addr, itr->second.get());
          ++i;
        }
        serviceLookups.erase(addr);
        return;
      }

      auto it = remoteSessions.emplace(addr, std::make_shared<OutboundContext>(introset, this));
      LogInfo("Created New outbound context for ", addr.ToString());

      // inform pending
      auto range = serviceLookups.equal_range(addr);
      auto itr = range.first;
      if (itr != range.second)
      {
        itr->second(addr, it->second.get());
        ++itr;
      }
      serviceLookups.erase(addr);
    }

    void
    Endpoint::HandleVerifyGotRouter(dht::GotRouterMessage_constptr msg, llarp_async_verify_rc* j)
    {
      auto& pendingRouters = m_state->m_PendingRouters;
      auto itr = pendingRouters.find(j->rc.pubkey);
      if (itr != pendingRouters.end())
      {
        if (j->valid)
          itr->second.InformResult(msg->foundRCs);
        else
          itr->second.InformResult({});
        pendingRouters.erase(itr);
      }
      delete j;
    }

    bool
    Endpoint::HandleGotRouterMessage(dht::GotRouterMessage_constptr msg)
    {
      if (not msg->foundRCs.empty())
      {
        for (const auto& rc : msg->foundRCs)
        {
          llarp_async_verify_rc* job = new llarp_async_verify_rc();
          job->nodedb = Router()->nodedb();
          job->worker = util::memFn(&AbstractRouter::QueueWork, Router());
          job->disk = util::memFn(&AbstractRouter::QueueDiskIO, Router());
          job->logic = Router()->logic();
          job->hook = std::bind(&Endpoint::HandleVerifyGotRouter, this, msg, std::placeholders::_1);
          job->rc = rc;
          llarp_nodedb_async_verify(job);
        }
      }
      else
      {
        auto& routers = m_state->m_PendingRouters;
        auto itr = routers.begin();
        while (itr != routers.end())
        {
          if (itr->second.txid == msg->txid)
          {
            itr->second.InformResult({});
            itr = routers.erase(itr);
          }
          else
            ++itr;
        }
      }
      return true;
    }

    struct LookupNameJob : public IServiceLookup
    {
      std::function<void(std::optional<Address>)> handler;
      ShortHash namehash;

      LookupNameJob(
          Endpoint* parent,
          uint64_t id,
          std::string lnsName,
          std::function<void(std::optional<Address>)> resultHandler)
          : IServiceLookup(parent, id, lnsName), handler(resultHandler)
      {
        CryptoManager::instance()->shorthash(
            namehash, llarp_buffer_t(lnsName.c_str(), lnsName.size()));
      }

      std::shared_ptr<routing::IMessage>
      BuildRequestMessage() override
      {
        auto msg = std::make_shared<routing::DHTMessage>();
        msg->M.emplace_back(std::make_unique<dht::FindNameMessage>(
            dht::Key_t{}, dht::Key_t{namehash.as_array()}, txid));
        return msg;
      }

      bool
      HandleNameResponse(std::optional<Address> addr) override
      {
        handler(addr);
        return true;
      }

      void
      HandleTimeout() override
      {
        HandleNameResponse(std::nullopt);
      }
    };

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

      return not m_ExitMap.Empty();
    }

    bool
    Endpoint::LookupNameAsync(std::string name, std::function<void(std::optional<Address>)> handler)
    {
      auto& cache = m_state->nameCache;
      const auto maybe = cache.Get(name);
      if (maybe.has_value())
      {
        handler(maybe);
        return true;
      }
      auto path = PickRandomEstablishedPath();
      if (path == nullptr)
        return false;
      LogInfo(Name(), " looking up LNS name: ", name);
      auto job = new LookupNameJob(this, GenTXID(), name, handler);
      return job->SendRequestViaPath(path, m_router);
    }

    bool
    Endpoint::HandleGotNameMessage(std::shared_ptr<const dht::GotNameMessage> msg)
    {
      auto& lookups = m_state->m_PendingLookups;
      auto itr = lookups.find(msg->TxID);
      if (itr == lookups.end())
        return false;

      // decrypt entry
      const auto maybe = msg->result.Decrypt(itr->second->name);

      if (maybe.has_value())
      {
        // put cache entry for result
        m_state->nameCache.Put(itr->second->name, *maybe);
      }
      // inform result
      itr->second->HandleNameResponse(maybe);
      lookups.erase(itr);
      return true;
    }

    void
    Endpoint::EnsureRouterIsKnown(const RouterID& router)
    {
      if (router.IsZero())
        return;
      if (!Router()->nodedb()->Has(router))
      {
        LookupRouterAnon(router, nullptr);
      }
    }

    bool
    Endpoint::LookupRouterAnon(RouterID router, RouterLookupHandler handler)
    {
      using llarp::dht::FindRouterMessage;

      auto& routers = m_state->m_PendingRouters;
      if (routers.find(router) == routers.end())
      {
        auto path = GetEstablishedPathClosestTo(router);
        routing::DHTMessage msg;
        auto txid = GenTXID();
        msg.M.emplace_back(std::make_unique<FindRouterMessage>(txid, router));

        if (path && path->SendRoutingMessage(msg, Router()))
        {
          RouterLookupJob job(this, handler);

          assert(msg.M.size() == 1);
          auto dhtMsg = dynamic_cast<FindRouterMessage*>(msg.M[0].get());
          assert(dhtMsg != nullptr);

          m_router->NotifyRouterEvent<tooling::FindRouterSentEvent>(m_router->pubkey(), *dhtMsg);

          routers.emplace(router, RouterLookupJob(this, handler));
          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", m_Identity.pub.Addr().ToString()}};
    }

    void
    Endpoint::FlushRecvData()
    {
      do
      {
        auto maybe = m_RecvQueue.tryPopFront();
        if (not maybe)
          return;
        auto ev = std::move(*maybe);
        ProtocolMessage::ProcessAsync(ev.fromPath, ev.pathid, ev.msg);
      } while (true);
    }

    void
    Endpoint::QueueRecvData(RecvDataEvent ev)
    {
      if (m_RecvQueue.full() || m_RecvQueue.empty())
      {
        auto self = this;
        LogicCall(m_router->logic(), [self]() { self->FlushRecvData(); });
      }
      m_RecvQueue.pushBack(std::move(ev));
    }

    bool
    Endpoint::HandleDataMessage(
        path::Path_ptr path, const PathID_t from, std::shared_ptr<ProtocolMessage> msg)
    {
      msg->sender.UpdateAddr();
      PutSenderFor(msg->tag, msg->sender, true);
      PutReplyIntroFor(msg->tag, path->intro);
      Introduction intro;
      intro.pathID = from;
      intro.router = PubKey(path->Endpoint());
      intro.expiresAt = std::min(path->ExpireTime(), msg->introReply.expiresAt);
      PutIntroFor(msg->tag, intro);
      return ProcessDataMessage(msg);
    }

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

    bool
    Endpoint::ProcessDataMessage(std::shared_ptr<ProtocolMessage> msg)
    {
      if ((msg->proto == eProtocolExit
           && (m_state->m_ExitEnabled || m_ExitMap.ContainsValue(msg->sender.Addr())))
          || msg->proto == eProtocolTrafficV4 || msg->proto == eProtocolTrafficV6)
      {
        m_InboundTrafficQueue.tryPushBack(std::move(msg));
        return true;
      }
      if (msg->proto == eProtocolControl)
      {
        // 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(AuthResult)> hook)
    {
      if (m_AuthPolicy)
      {
        m_AuthPolicy->AuthenticateAsync(std::move(msg), std::move(hook));
      }
      else
      {
        RouterLogic()->Call([hook]() { hook(AuthResult::eAuthAccepted); });
      }
    }

    void
    Endpoint::SendAuthReject(
        path::Path_ptr path, PathID_t replyPath, ConvoTag tag, AuthResult result)
    {
      if (result == AuthResult::eAuthAccepted)
        return;
      ProtocolFrame f;
      f.R = result;
      f.T = tag;
      f.F = path->intro.pathID;

      if (f.Sign(m_Identity))
      {
        m_SendQueue.tryPushBack(
            SendEvent_t{std::make_shared<const routing::PathTransferMessage>(f, replyPath), path});
      }
    }

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

    bool
    Endpoint::HandleHiddenServiceFrame(path::Path_ptr p, const ProtocolFrame& frame)
    {
      if (frame.R)
      {
        // handle discard
        ServiceInfo si;
        if (!GetSenderFor(frame.T, si))
          return false;
        // verify source
        if (!frame.Verify(si))
          return false;
        // remove convotag it doesn't exist
        LogWarn("remove convotag T=", frame.T);
        RemoveConvoTag(frame.T);
        return true;
      }
      if (not frame.AsyncDecryptAndVerify(EndpointLogic(), p, m_Identity, this))
      {
        // send reset convo tag message
        ProtocolFrame f;
        f.R = 1;
        f.T = frame.T;
        f.F = p->intro.pathID;

        f.Sign(m_Identity);
        {
          LogWarn("invalidating convotag T=", frame.T);
          RemoveConvoTag(frame.T);
          m_SendQueue.tryPushBack(
              SendEvent_t{std::make_shared<const routing::PathTransferMessage>(f, frame.F), p});
        }
      }
      return true;
    }

    void
    Endpoint::HandlePathDied(path::Path_ptr p)
    {
      RegenAndPublishIntroSet(true);
      path::Builder::HandlePathDied(p);
    }

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

    bool
    Endpoint::OnLookup(
        const Address& addr, std::optional<IntroSet> introset, const RouterID& endpoint)
    {
      const auto now = Router()->Now();
      auto& fails = m_state->m_ServiceLookupFails;
      auto& lookups = m_state->m_PendingServiceLookups;
      if (not introset or introset->IsExpired(now))
      {
        LogError(Name(), " failed to lookup ", addr.ToString(), " from ", endpoint);
        fails[endpoint] = fails[endpoint] + 1;
        // inform one
        auto range = lookups.equal_range(addr);
        auto itr = range.first;
        if (itr != range.second)
        {
          itr->second(addr, nullptr);
          itr = lookups.erase(itr);
        }
        return false;
      }
      // check for established outbound context

      if (m_state->m_RemoteSessions.count(addr) > 0)
        return true;

      PutNewOutboundContext(*introset);
      return true;
    }

    void
    Endpoint::MarkAddressOutbound(const Address& addr)
    {
      m_state->m_OutboundSessions.insert(addr);
    }

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

    bool
    Endpoint::EnsurePathToService(
        const Address remote, PathEnsureHook hook, llarp_time_t /*timeoutMS*/)
    {
      /// how many routers to use for lookups
      static constexpr size_t NumParallelLookups = 2;
      /// how many requests per router
      static constexpr size_t RequestsPerLookup = 2;

      MarkAddressOutbound(remote);

      auto& sessions = m_state->m_RemoteSessions;

      {
        auto itr = sessions.find(remote);
        if (itr != sessions.end())
        {
          hook(itr->first, itr->second.get());
          return true;
        }
      }

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

      auto& lookupTimes = m_state->m_LastServiceLookupTimes;
      const auto now = Now();

      // if most recent lookup was within last INTROSET_LOOKUP_RETRY_COOLDOWN
      // just add callback to the list and return
      if (lookupTimes.find(remote) != lookupTimes.end()
          && now < (lookupTimes[remote] + INTROSET_LOOKUP_RETRY_COOLDOWN))
        return true;

      const auto paths = GetManyPathsWithUniqueEndpoints(this, NumParallelLookups);

      using namespace std::placeholders;
      const dht::Key_t location = remote.ToKey();
      uint64_t order = 0;

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

      for (const auto& path : paths)
      {
        for (size_t count = 0; count < RequestsPerLookup; ++count)
        {
          HiddenServiceAddressLookup* job = new HiddenServiceAddressLookup(
              this,
              util::memFn(&Endpoint::OnLookup, this),
              location,
              PubKey{remote.as_array()},
              order,
              GenTXID());
          LogInfo(
              "doing lookup for ",
              remote,
              " via ",
              path->Endpoint(),
              " at ",
              location,
              " order=",
              order);
          order++;
          if (job->SendRequestViaPath(path, Router()))
          {
            if (not hookAdded)
            {
              // if any of the lookups is successful, set last lookup time
              lookupTimes[remote] = now;
              hookAdded = true;
            }
          }
          else
            LogError(Name(), " send via path failed for lookup");
        }
      }
      return hookAdded;
    }

    bool
    Endpoint::EnsurePathToSNode(const RouterID snode, SNodeEnsureHook h)
    {
      static constexpr size_t MaxConcurrentSNodeSessions = 16;
      auto& nodeSessions = m_state->m_SNodeSessions;
      if (nodeSessions.size() >= MaxConcurrentSNodeSessions)
      {
        // a quick client side work arround before we do proper limiting
        LogError(Name(), " has too many snode sessions");
        return false;
      }
      using namespace std::placeholders;
      if (nodeSessions.count(snode) == 0)
      {
        ConvoTag tag;
        // TODO: check for collision lol no we don't but maybe we will...
        // some day :DDDDD
        tag.Randomize();
        const auto src = xhtonl(net::TruncateV6(GetIfAddr()));
        const auto dst = xhtonl(net::TruncateV6(ObtainIPForAddr(snode, true)));

        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
              return HandleInboundPacket(tag, pkt.ConstBuffer(), eProtocolTrafficV4, 0);
            },
            Router(),
            numDesiredPaths,
            numHops,
            false,
            ShouldBundleRC());

        m_state->m_SNodeSessions.emplace(snode, std::make_pair(session, tag));
      }
      EnsureRouterIsKnown(snode);
      auto range = nodeSessions.equal_range(snode);
      auto itr = range.first;
      while (itr != range.second)
      {
        if (itr->second.first->IsReady())
          h(snode, itr->second.first);
        else
        {
          itr->second.first->AddReadyHook(std::bind(h, snode, _1));
          itr->second.first->BuildOne();
        }
        ++itr;
      }
      return true;
    }

    bool
    Endpoint::SendToSNodeOrQueue(const RouterID& addr, const llarp_buffer_t& buf)
    {
      auto pkt = std::make_shared<net::IPPacket>();
      if (!pkt->Load(buf))
        return false;
      EnsurePathToSNode(addr, [pkt](RouterID, exit::BaseSession_ptr s) {
        if (s)
          s->QueueUpstreamTraffic(*pkt, routing::ExitPadSize);
      });
      return true;
    }

    void Endpoint::Pump(llarp_time_t)
    {
      const auto& sessions = m_state->m_SNodeSessions;
      auto& queue = m_InboundTrafficQueue;

      auto epPump = [&]() {
        FlushRecvData();
        // send downstream packets to user for snode
        for (const auto& item : sessions)
          item.second.first->FlushDownstream();
        // send downstream traffic to user for hidden service
        while (not queue.empty())
        {
          auto msg = queue.popFront();
          const llarp_buffer_t buf(msg->payload);
          HandleInboundPacket(msg->tag, buf, msg->proto, msg->seqno);
        }
      };

      if (NetworkIsIsolated())
      {
        LogicCall(EndpointLogic(), epPump);
      }
      else
      {
        epPump();
      }
      auto router = Router();
      // TODO: locking on this container
      for (const auto& item : m_state->m_RemoteSessions)
        item.second->FlushUpstream();
      // TODO: locking on this container
      for (const auto& item : sessions)
        item.second.first->FlushUpstream();

      // send queue flush
      while (not m_SendQueue.empty())
      {
        auto item = m_SendQueue.popFront();
        item.second->SendRoutingMessage(*item.first, router);
        MarkConvoTagActive(item.first->T.T);
      }

      UpstreamFlush(router);
      router->linkManager().PumpLinks();
    }

    bool
    Endpoint::EnsureConvo(
        const AlignedBuffer<32> /*addr*/, bool snode, ConvoEventListener_ptr /*ev*/)
    {
      if (snode)
      {
      }

      // TODO: something meaningful
      return false;
    }

    bool
    Endpoint::SendToServiceOrQueue(
        const service::Address& remote, const llarp_buffer_t& data, ProtocolType t)
    {
      if (data.sz == 0)
        return false;
      // inbound converstation
      const auto now = Now();

      if (HasInboundConvo(remote))
      {
        auto transfer = std::make_shared<routing::PathTransferMessage>();
        ProtocolFrame& f = transfer->T;
        f.R = 0;
        std::shared_ptr<path::Path> p;
        std::set<ConvoTag> tags;
        if (GetConvoTagsForService(remote, tags))
        {
          // the remote guy's intro
          Introduction remoteIntro;
          Introduction replyPath;
          SharedSecret K;
          // pick tag
          for (const auto& tag : tags)
          {
            if (tag.IsZero())
              continue;
            if (!GetCachedSessionKeyFor(tag, K))
              continue;
            if (!GetReplyIntroFor(tag, replyPath))
              continue;
            if (!GetIntroFor(tag, remoteIntro))
              continue;
            // get path for intro
            ForEachPath([&](path::Path_ptr path) {
              if (path->intro == replyPath)
              {
                p = path;
                return;
              }
              if (p && p->ExpiresSoon(now) && path->IsReady()
                  && path->intro.router == replyPath.router)
              {
                p = path;
              }
            });
            if (p)
            {
              f.T = tag;
            }
          }
          if (p)
          {
            // TODO: check expiration of our end
            auto m = std::make_shared<ProtocolMessage>(f.T);
            m->PutBuffer(data);
            f.N.Randomize();
            f.C.Zero();
            transfer->Y.Randomize();
            m->proto = t;
            m->introReply = p->intro;
            PutReplyIntroFor(f.T, m->introReply);
            m->sender = m_Identity.pub;
            m->seqno = GetSeqNoForConvo(f.T);
            f.S = m->seqno;
            f.F = m->introReply.pathID;
            transfer->P = remoteIntro.pathID;
            auto self = this;
            Router()->QueueWork([transfer, p, m, K, self]() {
              if (not transfer->T.EncryptAndSign(*m, K, self->m_Identity))
              {
                LogError("failed to encrypt and sign");
                return;
              }
              self->m_SendQueue.pushBack(SendEvent_t{transfer, p});
              ;
            });
            return true;
          }
        }
      }
      else
      {
        auto& sessions = m_state->m_RemoteSessions;
        auto range = sessions.equal_range(remote);
        auto itr = range.first;
        while (itr != range.second)
        {
          if (itr->second->ReadyToSend())
          {
            itr->second->AsyncEncryptAndSendTo(data, t);
            return true;
          }
          ++itr;
        }
        // if we want to make an outbound session
        if (WantsOutboundSession(remote))
        {
          // add pending traffic
          auto& traffic = m_state->m_PendingTraffic;
          traffic[remote].emplace_back(data, t);
          return EnsurePathToService(
              remote,
              [self = this](Address addr, OutboundContext* ctx) {
                if (ctx)
                {
                  ctx->UpdateIntroSet();
                  for (auto& pending : self->m_state->m_PendingTraffic[addr])
                  {
                    ctx->AsyncEncryptAndSendTo(pending.Buffer(), pending.protocol);
                  }
                }
                self->m_state->m_PendingTraffic.erase(addr);
              },
              1500ms);
        }
      }
      return false;
    }

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

    uint64_t
    Endpoint::GetSeqNoForConvo(const ConvoTag& tag)
    {
      auto itr = Sessions().find(tag);
      if (itr == Sessions().end())
        return 0;
      itr->second.seqno += 1;
      return itr->second.seqno;
    }

    bool
    Endpoint::ShouldBuildMore(llarp_time_t now) const
    {
      if (not path::Builder::ShouldBuildMore(now))
        return false;
      return ((now - lastBuild) > path::intro_path_spread)
          || NumInStatus(path::ePathEstablished) < path::min_intro_paths;
    }

    std::shared_ptr<Logic>
    Endpoint::RouterLogic()
    {
      return Router()->logic();
    }

    std::shared_ptr<Logic>
    Endpoint::EndpointLogic()
    {
      return m_state->m_IsolatedLogic ? m_state->m_IsolatedLogic : Router()->logic();
    }

    AbstractRouter*
    Endpoint::Router()
    {
      return m_state->m_Router;
    }

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

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

    const IntroSet&
    Endpoint::introSet() const
    {
      return m_state->m_IntroSet;
    }

    IntroSet&
    Endpoint::introSet()
    {
      return m_state->m_IntroSet;
    }

    const ConvoMap&
    Endpoint::Sessions() const
    {
      return m_state->m_Sessions;
    }

    ConvoMap&
    Endpoint::Sessions()
    {
      return m_state->m_Sessions;
    }

    void
    Endpoint::SetAuthInfoForEndpoint(Address addr, AuthInfo info)
    {
      m_RemoteAuthInfos[addr] = std::move(info);
    }

    void
    Endpoint::MapExitRange(IPRange range, Address exit)
    {
      LogInfo(Name(), " map ", range, " to exit at ", exit);
      m_ExitMap.Insert(range, exit);
    }

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

    std::optional<AuthInfo>
    Endpoint::MaybeGetAuthInfoForEndpoint(Address remote)
    {
      const auto itr = m_RemoteAuthInfos.find(remote);
      if (itr == m_RemoteAuthInfos.end())
        return std::nullopt;
      return itr->second;
    }

  }  // namespace service
}  // namespace llarp