text: // Copyright (c) 2012 The Chromium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  //
  // A QuicSession, which demuxes a single connection to individual streams.
  
  #ifndef NET_QUIC_QUIC_SESSION_H_
  #define NET_QUIC_QUIC_SESSION_H_
  
  #include <stddef.h>
  
  #include <map>
  #include <memory>
  #include <string>
  #include <unordered_map>
  #include <unordered_set>
  #include <vector>
  
  #include "base/compiler_specific.h"
  #include "base/containers/small_map.h"
  #include "base/macros.h"
  #include "base/strings/string_piece.h"
  #include "net/base/ip_endpoint.h"
  #include "net/quic/core/quic_connection.h"
  #include "net/quic/core/quic_crypto_stream.h"
  #include "net/quic/core/quic_packet_creator.h"
  #include "net/quic/core/quic_protocol.h"
  #include "net/quic/core/quic_write_blocked_list.h"
  #include "net/quic/core/reliable_quic_stream.h"
  
  namespace net {
  
  class QuicCryptoStream;
  class QuicFlowController;
  class ReliableQuicStream;
  
  namespace test {
  class QuicSessionPeer;
  }  // namespace test
  
  class NET_EXPORT_PRIVATE QuicSession : public QuicConnectionVisitorInterface {
   public:
    // CryptoHandshakeEvent enumerates the events generated by a QuicCryptoStream.
    enum CryptoHandshakeEvent {
      // ENCRYPTION_FIRST_ESTABLISHED indicates that a full client hello has been
      // sent by a client and that subsequent packets will be encrypted. (Client
      // only.)
      ENCRYPTION_FIRST_ESTABLISHED,
      // ENCRYPTION_REESTABLISHED indicates that a client hello was rejected by
      // the server and thus the encryption key has been updated. Therefore the
      // connection should resend any packets that were sent under
      // ENCRYPTION_INITIAL. (Client only.)
      ENCRYPTION_REESTABLISHED,
      // HANDSHAKE_CONFIRMED, in a client, indicates the the server has accepted
      // our handshake. In a server it indicates that a full, valid client hello
      // has been received. (Client and server.)
      HANDSHAKE_CONFIRMED,
    };
  
    // Does not take ownership of |connection|.
    QuicSession(QuicConnection* connection, const QuicConfig& config);
  
    ~QuicSession() override;
  
    virtual void Initialize();
  
    // QuicConnectionVisitorInterface methods:
    void OnStreamFrame(const QuicStreamFrame& frame) override;
    void OnRstStream(const QuicRstStreamFrame& frame) override;
    void OnGoAway(const QuicGoAwayFrame& frame) override;
    void OnWindowUpdateFrame(const QuicWindowUpdateFrame& frame) override;
    void OnBlockedFrame(const QuicBlockedFrame& frame) override;
    void OnConnectionClosed(QuicErrorCode error,
                            const std::string& error_details,
                            ConnectionCloseSource source) override;
    void OnWriteBlocked() override {}
    void OnSuccessfulVersionNegotiation(const QuicVersion& version) override;
    void OnCanWrite() override;
    void OnCongestionWindowChange(QuicTime /*now*/) override {}
    void OnConnectionMigration(PeerAddressChangeType type) override {}
    // Deletes streams that are safe to be deleted now that it's safe to do so (no
    // other operations are being done on the streams at this time).
    void PostProcessAfterData() override;
    bool WillingAndAbleToWrite() const override;
    bool HasPendingHandshake() const override;
    bool HasOpenDynamicStreams() const override;
    void OnPathDegrading() override;
  
    // Called on every incoming packet. Passes |packet| through to |connection_|.
    virtual void ProcessUdpPacket(const IPEndPoint& self_address,
                                  const IPEndPoint& peer_address,
                                  const QuicReceivedPacket& packet);
  
    // Called by streams when they want to write data to the peer.
    // Returns a pair with the number of bytes consumed from data, and a boolean
    // indicating if the fin bit was consumed.  This does not indicate the data
    // has been sent on the wire: it may have been turned into a packet and queued
    // if the socket was unexpectedly blocked.
    // If provided, |ack_notifier_delegate| will be registered to be notified when
    // we have seen ACKs for all packets resulting from this call.
    virtual QuicConsumedData WritevData(
        ReliableQuicStream* stream,
        QuicStreamId id,
        QuicIOVector iov,
        QuicStreamOffset offset,
        bool fin,
        QuicAckListenerInterface* ack_notifier_delegate);
  
    // Called by streams when they want to close the stream in both directions.
    virtual void SendRstStream(QuicStreamId id,
                               QuicRstStreamErrorCode error,
                               QuicStreamOffset bytes_written);
  
    // Called when the session wants to go away and not accept any new streams.
    void SendGoAway(QuicErrorCode error_code, const std::string& reason);
  
    // Removes the stream associated with 'stream_id' from the active stream map.
    virtual void CloseStream(QuicStreamId stream_id);
  
    // Returns true if outgoing packets will be encrypted, even if the server
    // hasn't confirmed the handshake yet.
    virtual bool IsEncryptionEstablished();
  
    // For a client, returns true if the server has confirmed our handshake. For
    // a server, returns true if a full, valid client hello has been received.
    virtual bool IsCryptoHandshakeConfirmed();
  
    // Called by the QuicCryptoStream when a new QuicConfig has been negotiated.
    virtual void OnConfigNegotiated();
  
    // Called by the QuicCryptoStream when the handshake enters a new state.
    //
    // Clients will call this function in the order:
    //   ENCRYPTION_FIRST_ESTABLISHED
    //   zero or more ENCRYPTION_REESTABLISHED
    //   HANDSHAKE_CONFIRMED
    //
    // Servers will simply call it once with HANDSHAKE_CONFIRMED.
    virtual void OnCryptoHandshakeEvent(CryptoHandshakeEvent event);
  
    // Called by the QuicCryptoStream when a handshake message is sent.
    virtual void OnCryptoHandshakeMessageSent(
        const CryptoHandshakeMessage& message);
  
    // Called by the QuicCryptoStream when a handshake message is received.
    virtual void OnCryptoHandshakeMessageReceived(
        const CryptoHandshakeMessage& message);
  
    // Returns mutable config for this session. Returned config is owned
    // by QuicSession.
    QuicConfig* config();
  
    // Returns true if the stream existed previously and has been closed.
    // Returns false if the stream is still active or if the stream has
    // not yet been created.
    bool IsClosedStream(QuicStreamId id);
  
    QuicConnection* connection() { return connection_; }
    const QuicConnection* connection() const { return connection_; }
    size_t num_active_requests() const { return dynamic_stream_map_.size(); }
    const IPEndPoint& peer_address() const { return connection_->peer_address(); }
    QuicConnectionId connection_id() const {
      return connection_->connection_id();
    }
  
    // Returns the number of currently open streams, excluding the reserved
    // headers and crypto streams, and never counting unfinished streams.
    virtual size_t GetNumActiveStreams() const;
  
    // Returns the number of currently open peer initiated streams, excluding the
    // reserved headers and crypto streams.
    virtual size_t GetNumOpenIncomingStreams() const;
  
    // Returns the number of currently open self initiated streams, excluding the
    // reserved headers and crypto streams.
    virtual size_t GetNumOpenOutgoingStreams() const;
  
    // Returns the number of "available" streams, the stream ids less than
    // largest_peer_created_stream_id_ that have not yet been opened.
    virtual size_t GetNumAvailableStreams() const;
  
    // Add the stream to the session's write-blocked list because it is blocked by
    // connection-level flow control but not by its own stream-level flow control.
    // The stream will be given a chance to write when a connection-level
    // WINDOW_UPDATE arrives.
    void MarkConnectionLevelWriteBlocked(QuicStreamId id);
  
    // Returns true if the session has data to be sent, either queued in the
    // connection, or in a write-blocked stream.
    bool HasDataToWrite() const;
  
    bool goaway_sent() const;
  
    bool goaway_received() const;
  
    QuicErrorCode error() const { return error_; }
  
    Perspective perspective() const { return connection_->perspective(); }
  
    QuicFlowController* flow_controller() { return &flow_controller_; }
  
    // Returns true if connection is flow controller blocked.
    bool IsConnectionFlowControlBlocked() const;
  
    // Returns true if any stream is flow controller blocked.
    bool IsStreamFlowControlBlocked();
  
    size_t max_open_incoming_streams() const {
      return max_open_incoming_streams_;
    }
  
    size_t max_open_outgoing_streams() const {
      return max_open_outgoing_streams_;
    }
  
    size_t MaxAvailableStreams() const;
  
    // Returns existing static or dynamic stream with id = |stream_id|. If no
    // such stream exists, and |stream_id| is a peer-created dynamic stream id,
    // then a new stream is created and returned. In all other cases, nullptr is
    // returned.
    ReliableQuicStream* GetOrCreateStream(const QuicStreamId stream_id);
  
    // Mark a stream as draining.
    virtual void StreamDraining(QuicStreamId id);
  
    // Returns true if this stream should yield writes to another blocked stream.
    bool ShouldYield(QuicStreamId stream_id);
  
   protected:
    using StaticStreamMap =
        base::SmallMap<std::unordered_map<QuicStreamId, ReliableQuicStream*>, 2>;
  
    using DynamicStreamMap =
        base::SmallMap<std::unordered_map<QuicStreamId, ReliableQuicStream*>, 10>;
  
    // Creates a new stream to handle a peer-initiated stream.
    // Caller does not own the returned stream.
    // Returns nullptr and does error handling if the stream can not be created.
    virtual ReliableQuicStream* CreateIncomingDynamicStream(QuicStreamId id) = 0;
  
    // Create a new stream to handle a locally-initiated stream.
    // Caller does not own the returned stream.
    // Returns nullptr if max streams have already been opened.
    virtual ReliableQuicStream* CreateOutgoingDynamicStream(
        SpdyPriority priority) = 0;
  
    // Return the reserved crypto stream.
    virtual QuicCryptoStream* GetCryptoStream() = 0;
  
    // Adds |stream| to the dynamic stream map.
    // Takes ownership of |stream|.
    virtual void ActivateStream(ReliableQuicStream* stream);
  
    // Returns the stream ID for a new outgoing stream, and increments the
    // underlying counter.
    QuicStreamId GetNextOutgoingStreamId();
  
    // Returns existing stream with id = |stream_id|. If no such stream exists,
    // and |stream_id| is a peer-created id, then a new stream is created and
    // returned. However if |stream_id| is a locally-created id and no such stream
    // exists, the connection is closed.
    // Caller does not own the returned stream.
    ReliableQuicStream* GetOrCreateDynamicStream(QuicStreamId stream_id);
  
    // Performs the work required to close |stream_id|.  If |locally_reset|
    // then the stream has been reset by this endpoint, not by the peer.
    virtual void CloseStreamInner(QuicStreamId stream_id, bool locally_reset);
  
    // When a stream is closed locally, it may not yet know how many bytes the
    // peer sent on that stream.
    // When this data arrives (via stream frame w. FIN, or RST) this method
    // is called, and correctly updates the connection level flow controller.
    void UpdateFlowControlOnFinalReceivedByteOffset(
        QuicStreamId id,
        QuicStreamOffset final_byte_offset);
  
    // Return true if given stream is peer initiated.
    bool IsIncomingStream(QuicStreamId id) const;
  
    StaticStreamMap& static_streams() { return static_stream_map_; }
    const StaticStreamMap& static_streams() const { return static_stream_map_; }
  
    DynamicStreamMap& dynamic_streams() { return dynamic_stream_map_; }
    const DynamicStreamMap& dynamic_streams() const {
      return dynamic_stream_map_;
    }
  
    std::vector<ReliableQuicStream*>* closed_streams() {
      return &closed_streams_;
    }
  
    void set_max_open_incoming_streams(size_t max_open_incoming_streams);
    void set_max_open_outgoing_streams(size_t max_open_outgoing_streams);
  
    void set_largest_peer_created_stream_id(
        QuicStreamId largest_peer_created_stream_id) {
      largest_peer_created_stream_id_ = largest_peer_created_stream_id;
    }
    void set_error(QuicErrorCode error) { error_ = error; }
    QuicWriteBlockedList* write_blocked_streams() {
      return &write_blocked_streams_;
    }
  
    size_t GetNumDynamicOutgoingStreams() const;
  
    size_t GetNumDrainingOutgoingStreams() const;
  
    size_t num_locally_closed_incoming_streams_highest_offset() const {
      return num_locally_closed_incoming_streams_highest_offset_;
    }
  
    size_t GetNumLocallyClosedOutgoingStreamsHighestOffset() const;
  
    // Returns true if the stream is still active.
    bool IsOpenStream(QuicStreamId id);
  
    QuicStreamId next_outgoing_stream_id() const {
      return next_outgoing_stream_id_;
    }
  
    // Close connection when receive a frame for a locally-created nonexistant
    // stream.
    // Prerequisite: IsClosedStream(stream_id) == false
    // Server session might need to override this method to allow server push
    // stream to be promised before creating an active stream.
    virtual void HandleFrameOnNonexistentOutgoingStream(QuicStreamId stream_id);
  
    bool MaybeIncreaseLargestPeerStreamId(const QuicStreamId stream_id);
  
    void InsertLocallyClosedStreamsHighestOffset(const QuicStreamId id,
                                                 QuicStreamOffset offset);
    // If stream is a locally closed stream, this RST will update FIN offset.
    // Otherwise stream is a preserved stream and the behavior of it depends on
    // derived class's own implementation.
    virtual void HandleRstOnValidNonexistentStream(
        const QuicRstStreamFrame& frame);
  
   private:
    friend class test::QuicSessionPeer;
  
    // Called in OnConfigNegotiated when we receive a new stream level flow
    // control window in a negotiated config. Closes the connection if invalid.
    void OnNewStreamFlowControlWindow(QuicStreamOffset new_window);
  
    // Called in OnConfigNegotiated when we receive a new connection level flow
    // control window in a negotiated config. Closes the connection if invalid.
    void OnNewSessionFlowControlWindow(QuicStreamOffset new_window);
  
    // Keep track of highest received byte offset of locally closed streams, while
    // waiting for a definitive final highest offset from the peer.
    std::map<QuicStreamId, QuicStreamOffset>
        locally_closed_streams_highest_offset_;
  
    QuicConnection* connection_;
  
    std::vector<ReliableQuicStream*> closed_streams_;
  
    QuicConfig config_;
  
    // The maximum number of outgoing streams this connection can open.
    size_t max_open_outgoing_streams_;
  
    // The maximum number of incoming streams this connection will allow.
    size_t max_open_incoming_streams_;
  
    // Static streams, such as crypto and header streams. Owned by child classes
    // that create these streams.
    StaticStreamMap static_stream_map_;
  
    // Map from StreamId to pointers to streams. Owns the streams.
    DynamicStreamMap dynamic_stream_map_;
  
    // The ID to use for the next outgoing stream.
    QuicStreamId next_outgoing_stream_id_;
  
    // Set of stream ids that are less than the largest stream id that has been
    // received, but are nonetheless available to be created.
    std::unordered_set<QuicStreamId> available_streams_;
  
    // Set of stream ids that are "draining" -- a FIN has been sent and received,
    // but the stream object still exists because not all the received data has
    // been consumed.
    std::unordered_set<QuicStreamId> draining_streams_;
  
    // A list of streams which need to write more data.
    QuicWriteBlockedList write_blocked_streams_;
  
    QuicStreamId largest_peer_created_stream_id_;
  
    // A counter for peer initiated streams which are in the dynamic_stream_map_.
    size_t num_dynamic_incoming_streams_;
  
    // A counter for peer initiated streams which are in the draining_streams_.
    size_t num_draining_incoming_streams_;
  
    // A counter for peer initiated streams which are in the
    // locally_closed_streams_highest_offset_.
    size_t num_locally_closed_incoming_streams_highest_offset_;
  
    // The latched error with which the connection was closed.
    QuicErrorCode error_;
  
    // Used for connection-level flow control.
    QuicFlowController flow_controller_;
  
    // The stream id which was last popped in OnCanWrite, or 0, if not under the
    // call stack of OnCanWrite.
    QuicStreamId currently_writing_stream_id_;
  
    DISALLOW_COPY_AND_ASSIGN(QuicSession);
  };
  
  }  // namespace net
  
  #endif  // NET_QUIC_QUIC_SESSION_H_
  