lokinet/llarp/utp/session.hpp

#ifndef LLARP_UTP_SESSION_HPP
#define LLARP_UTP_SESSION_HPP

#include <crypto/crypto.hpp>
#include <link/session.hpp>
#include <utp/inbound_message.hpp>

#include <utp.h>

namespace llarp
{
  namespace utp
  {
    struct LinkLayer;

    struct Session final : public ILinkSession
    {
      /// remote router's rc
      RouterContact remoteRC;
      /// underlying socket
      utp_socket* sock;
      /// link layer parent
      LinkLayer* parent;
      /// did we get a LIM from the remote yet?
      bool gotLIM;
      /// remote router's transport pubkey
      PubKey remoteTransportPubKey;
      /// remote router's transport ip
      Addr remoteAddr;
      /// rx session key
      SharedSecret rxKey;
      /// tx session key
      SharedSecret txKey;
      /// timestamp last active
      llarp_time_t lastActive;
      /// timestamp last send success
      llarp_time_t lastSend;
      /// session timeout (60s)
      const static llarp_time_t sessionTimeout = DefaultLinkSessionLifetime;

      /// send queue for utp
      std::deque< utp_iovec > vecq;
      /// tx fragment queue
      std::deque< FragmentBuffer > sendq;
      /// current rx fragment buffer
      FragmentBuffer recvBuf;
      /// current offset in current rx fragment buffer
      size_t recvBufOffset;
      /// rx fragment message body
      AlignedBuffer< FragmentBodySize > rxFragBody;

      /// the next message id for tx
      uint32_t m_NextTXMsgID;
      /// the next message id for rx
      uint32_t m_NextRXMsgID;
      /// messages we are recving right now
      std::unordered_map< uint32_t, InboundMessage > m_RecvMsgs;
      /// are we stalled or nah?
      bool stalled = false;

      uint64_t m_RXRate = 0;
      uint64_t m_TXRate = 0;

      /// mark session as alive
      void
      Alive();

      util::StatusObject
      ExtractStatus() const override;

      /// base
      Session(LinkLayer* p);

      /// outbound
      Session(LinkLayer* p, utp_socket* s, const RouterContact& rc,
              const AddressInfo& addr);

      /// inbound
      Session(LinkLayer* p, utp_socket* s, const Addr& remote);

      enum State
      {
        eInitial,          // initial state
        eConnecting,       // we are connecting
        eLinkEstablished,  // when utp connection is established
        eCryptoHandshake,  // crypto handshake initiated
        eSessionReady,     // session is ready
        eClose             // utp connection is closed
      };

      /// get router
      // Router*
      // Router();

      Crypto*
      OurCrypto();

      /// session state, call EnterState(State) to set
      State state;

      /// hook for utp for when we have established a connection
      void
      OnLinkEstablished(LinkLayer* p);

      /// switch states
      void
      EnterState(State st);

      Session();
      ~Session();

      /// handle LIM after handshake
      bool
      GotSessionRenegotiate(const LinkIntroMessage* msg);

      /// re negotiate session with our new local RC
      bool
      Rehandshake();

      /// pump tx queue
      void
      PumpWrite();

      void
      DoPump();

      /// verify a fragment buffer and the decrypt it
      /// buf is assumed to be FragmentBufferSize bytes long
      bool
      VerifyThenDecrypt(const byte_t* buf);

      /// encrypt a fragment then hash the ciphertext
      bool
      EncryptThenHash(const byte_t* ptr, uint32_t msgid, uint16_t sz,
                      uint16_t remain);

      /// queue a fully formed message
      bool
      QueueWriteBuffers(const llarp_buffer_t& buf);

      /// prune expired inbound messages
      void
      PruneInboundMessages(llarp_time_t now);

      /// do low level connect
      void
      Connect();

      /// handle outbound connection made
      void
      OutboundLinkEstablished(LinkLayer* p);

      // send first message
      void
      OutboundHandshake();

      // do key exchange for handshake
      bool
      DoKeyExchange(transport_dh_func dh, SharedSecret& K,
                    const KeyExchangeNonce& n, const PubKey& other,
                    const SecretKey& secret);

      /// does K = HS(K + A)
      bool
      MutateKey(SharedSecret& K, const AlignedBuffer< 24 >& A);

      void
      TickImpl(llarp_time_t now);

      /// close session
      void
      Close();

      /// low level read
      bool
      Recv(const byte_t* buf, size_t sz);

      /// handle inbound LIM
      bool
      InboundLIM(const LinkIntroMessage* msg);

      /// handle outbound LIM
      bool
      OutboundLIM(const LinkIntroMessage* msg);

      /// return true if timed out
      bool
      IsTimedOut(llarp_time_t now) const;

      /// get remote identity pubkey
      const PubKey&
      RemotePubKey() const;

      /// get remote address
      Addr
      RemoteEndpoint();

      /// get parent link
      ILinkLayer*
      GetParent();

      void
      MarkEstablished();
    };
  }  // namespace utp
}  // namespace llarp

#endif