Implement an event-based simulator for QuicConnection

net/quic/core/congestion_control/simulation/quic_endpoint.h

+#ifndef NET_QUIC_CORE_CONGESTION_CONTROL_SIMULATION_QUIC_ENDPOINT_H_
+#define NET_QUIC_CORE_CONGESTION_CONTROL_SIMULATION_QUIC_ENDPOINT_H_
+
+#include "net/quic/core/congestion_control/simulation/link.h"
+#include "net/quic/core/congestion_control/simulation/queue.h"
+#include "net/quic/core/crypto/null_decrypter.h"
+#include "net/quic/core/crypto/null_encrypter.h"
+#include "net/quic/core/quic_connection.h"
+#include "net/quic/core/quic_default_packet_writer.h"
+#include "net/quic/core/quic_protocol.h"
+
+namespace net {
+namespace simulation {
+
+// Size of the TX queue used by the kernel/NIC.  1000 is the Linux
+// kernel default.
+const QuicByteCount kTxQueueSize = 1000;
+
+// Generate a random local network host-port tuple based on the name of the
+// endpoint.
+IPEndPoint GetAddressFromName(std::std::string name);
+
+// A QUIC connection endpoint.  Wraps around QuicConnection.  In order to
+// initiate a transfer, the caller has to call AddBytesToTransfer().  The data
+// transferred is always the same and is always transferred on a single stream.
+// The endpoint receives all packets addressed to it, and verifies that the data
+// received is what it's supposed to be.
+class QuicEndpoint : public Endpoint,
+                     public UnconstrainedPortInterface,
+                     public Queue::ListenerInterface,
+                     public QuicConnectionVisitorInterface {
+ public:
+  QuicEndpoint(Simulator* simulator,
+               std::std::string name,
+               std::std::string peer_name,
+               Perspective perspective,
+               QuicConnectionId connection_id);
+  ~QuicEndpoint() override {}
+
+  inline QuicConnection* connection() { return &connection_; }
+  inline QuicByteCount bytes_to_transfer() const { return bytes_to_transfer_; }
+  inline QuicByteCount bytes_transferred() const { return bytes_transferred_; }
+  inline QuicByteCount bytes_received() {
+    return connection_.GetStats().stream_bytes_received;
+  }
+  inline bool wrong_data_received() const { return wrong_data_received_; }
+
+  // Send |bytes| bytes.  Initiates the transfer if one is not already in
+  // progress.
+  void AddBytesToTransfer(QuicByteCount bytes);
+
+  // UnconstrainedPortInterface method.  Called whenever the endpoint receives a
+  // packet.
+  void AcceptPacket(std::unique_ptr<Packet> packet) override;
+
+  // Begin Endpoint implementation.
+  UnconstrainedPortInterface* GetRxPort() override;
+  void SetTxPort(ConstrainedPortInterface* port) override;
+  // End Endpoint implementation.
+
+  // Actor method.
+  void Act() override {}
+
+  // Queue::ListenerInterface method.
+  void OnPacketDequeued() override;
+
+  // Begin QuicConnectionVisitorInterface implementation.
+  void OnStreamFrame(const QuicStreamFrame& frame) override;
+  void OnCanWrite() override;
+  bool WillingAndAbleToWrite() const override;
+  bool HasPendingHandshake() const override;
+  bool HasOpenDynamicStreams() const override;
+
+  void OnWindowUpdateFrame(const QuicWindowUpdateFrame& frame) override {}
+  void OnBlockedFrame(const QuicBlockedFrame& frame) override {}
+  void OnRstStream(const QuicRstStreamFrame& frame) override {}
+  void OnGoAway(const QuicGoAwayFrame& frame) override {}
+  void OnConnectionClosed(QuicErrorCode error,
+                          const std::string& error_details,
+                          ConnectionCloseSource source) override {}
+  void OnWriteBlocked() override {}
+  void OnSuccessfulVersionNegotiation(const QuicVersion& version) override {}
+  void OnCongestionWindowChange(QuicTime now) override {}
+  void OnConnectionMigration(PeerAddressChangeType type) override {}
+  void OnPathDegrading() override {}
+  void PostProcessAfterData() override {}
+  // End QuicConnectionVisitorInterface implementation.
+
+ private:
+  // A Writer object that writes into the |nic_tx_queue_|.
+  class Writer : public QuicDefaultPacketWriter {
+   public:
+    explicit Writer(QuicEndpoint* endpoint);
+    ~Writer() override;
+
+    WriteResult WritePacket(const char* buffer,
+                            size_t buf_len,
+                            const IPAddress& self_address,
+                            const IPEndPoint& peer_address,
+                            PerPacketOptions* options) override;
+
+   private:
+    QuicEndpoint* endpoint_;
+  };
+
+  // Write stream data until |bytes_to_transfer_| is zero or the connection is
+  // write-blocked.
+  void WriteStreamData();
+
+  std::std::string peer_name_;
+
+  Writer writer_;
+  // The queue for the outgoing packets.  In reality, this might be either on
+  // the network card, or in the kernel, but for concreteness we assume it's on
+  // the network card.
+  Queue nic_tx_queue_;
+  QuicConnection connection_;
+
+  QuicByteCount bytes_to_transfer_;
+  QuicByteCount bytes_transferred_;
+
+  // Set to true if the endpoint receives stream data different from what it
+  // expects.
+  bool wrong_data_received_;
+
+  std::unique_ptr<char[]> transmission_buffer_;
+};
+
+// Multiplexes multiple connections at the same host on the network.
+class QuicEndpointMultiplexer : public Endpoint,
+                                public UnconstrainedPortInterface {
+ public:
+  QuicEndpointMultiplexer(std::std::string name,
+                          std::initializer_list<QuicEndpoint*> endpoints);
+  ~QuicEndpointMultiplexer() override {}
+
+  // Receives a packet and passes it to the specified endpoint if that endpoint
+  // is one of the endpoints being multiplexed, otherwise ignores the packet.
+  void AcceptPacket(std::unique_ptr<Packet> packet) override;
+  UnconstrainedPortInterface* GetRxPort() override;
+
+  // Sets the egress port for all the endpoints being multiplexed.
+  void SetTxPort(ConstrainedPortInterface* port) override;
+
+  void Act() override{};
+
+ private:
+  std::unordered_map<std::std::string, QuicEndpoint*> mapping_;
+};
+
+}  // namespace simulation
+}  // namespace net
+
+#endif  // NET_QUIC_CORE_CONGESTION_CONTROL_SIMULATION_QUIC_ENDPOINT_H_