diff --git a/quic/tools/quic_client_base.h b/quic/tools/quic_client_base.h
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+++ b/quic/tools/quic_client_base.h
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+// Copyright (c) 2015 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 base class for the toy client, which connects to a specified port and sends
+// QUIC request to that endpoint.
+
+#ifndef QUICHE_QUIC_TOOLS_QUIC_CLIENT_BASE_H_
+#define QUICHE_QUIC_TOOLS_QUIC_CLIENT_BASE_H_
+
+#include <string>
+
+#include "net/third_party/quiche/src/quic/core/crypto/crypto_handshake.h"
+#include "net/third_party/quiche/src/quic/core/http/quic_client_push_promise_index.h"
+#include "net/third_party/quiche/src/quic/core/http/quic_spdy_client_session.h"
+#include "net/third_party/quiche/src/quic/core/http/quic_spdy_client_stream.h"
+#include "net/third_party/quiche/src/quic/core/quic_config.h"
+#include "net/third_party/quiche/src/quic/platform/api/quic_macros.h"
+#include "net/third_party/quiche/src/quic/platform/api/quic_socket_address.h"
+#include "net/third_party/quiche/src/quic/platform/api/quic_string_piece.h"
+
+namespace quic {
+
+class ProofVerifier;
+class QuicServerId;
+
+// QuicClientBase handles establishing a connection to the passed in
+// server id, including ensuring that it supports the passed in versions
+// and config.
+// Subclasses derived from this class are responsible for creating the
+// actual QuicSession instance, as well as defining functions that
+// create and run the underlying network transport.
+class QuicClientBase {
+ public:
+  // An interface to various network events that the QuicClient will need to
+  // interact with.
+  class NetworkHelper {
+   public:
+    virtual ~NetworkHelper();
+
+    // Runs one iteration of the event loop.
+    virtual void RunEventLoop() = 0;
+
+    // Used during initialization: creates the UDP socket FD, sets socket
+    // options, and binds the socket to our address.
+    virtual bool CreateUDPSocketAndBind(QuicSocketAddress server_address,
+                                        QuicIpAddress bind_to_address,
+                                        int bind_to_port) = 0;
+
+    // Unregister and close all open UDP sockets.
+    virtual void CleanUpAllUDPSockets() = 0;
+
+    // If the client has at least one UDP socket, return address of the latest
+    // created one. Otherwise, return an empty socket address.
+    virtual QuicSocketAddress GetLatestClientAddress() const = 0;
+
+    // Creates a packet writer to be used for the next connection.
+    virtual QuicPacketWriter* CreateQuicPacketWriter() = 0;
+  };
+
+  QuicClientBase(const QuicServerId& server_id,
+                 const ParsedQuicVersionVector& supported_versions,
+                 const QuicConfig& config,
+                 QuicConnectionHelperInterface* helper,
+                 QuicAlarmFactory* alarm_factory,
+                 std::unique_ptr<NetworkHelper> network_helper,
+                 std::unique_ptr<ProofVerifier> proof_verifier);
+  QuicClientBase(const QuicClientBase&) = delete;
+  QuicClientBase& operator=(const QuicClientBase&) = delete;
+
+  virtual ~QuicClientBase();
+
+  // Initializes the client to create a connection. Should be called exactly
+  // once before calling StartConnect or Connect. Returns true if the
+  // initialization succeeds, false otherwise.
+  virtual bool Initialize();
+
+  // "Connect" to the QUIC server, including performing synchronous crypto
+  // handshake.
+  bool Connect();
+
+  // Start the crypto handshake.  This can be done in place of the synchronous
+  // Connect(), but callers are responsible for making sure the crypto handshake
+  // completes.
+  void StartConnect();
+
+  // Calls session()->Initialize(). Subclasses may override this if any extra
+  // initialization needs to be done. Subclasses should expect that session()
+  // is non-null and valid.
+  virtual void InitializeSession();
+
+  // Disconnects from the QUIC server.
+  void Disconnect();
+
+  // Returns true if the crypto handshake has yet to establish encryption.
+  // Returns false if encryption is active (even if the server hasn't confirmed
+  // the handshake) or if the connection has been closed.
+  bool EncryptionBeingEstablished();
+
+  // Wait for events until the stream with the given ID is closed.
+  void WaitForStreamToClose(QuicStreamId id);
+
+  // Wait for events until the handshake is confirmed.
+  // Returns true if the crypto handshake succeeds, false otherwise.
+  bool WaitForCryptoHandshakeConfirmed() QUIC_MUST_USE_RESULT;
+
+  // Wait up to 50ms, and handle any events which occur.
+  // Returns true if there are any outstanding requests.
+  bool WaitForEvents();
+
+  // Migrate to a new socket (new_host) during an active connection.
+  bool MigrateSocket(const QuicIpAddress& new_host);
+
+  // Migrate to a new socket (new_host, port) during an active connection.
+  bool MigrateSocketWithSpecifiedPort(const QuicIpAddress& new_host, int port);
+
+  // Open a new socket to change to a new ephemeral port.
+  bool ChangeEphemeralPort();
+
+  QuicSession* session();
+
+  bool connected() const;
+  bool goaway_received() const;
+
+  const QuicServerId& server_id() const { return server_id_; }
+
+  // This should only be set before the initial Connect()
+  void set_server_id(const QuicServerId& server_id) { server_id_ = server_id; }
+
+  void SetUserAgentID(const QuicString& user_agent_id) {
+    crypto_config_.set_user_agent_id(user_agent_id);
+  }
+
+  // SetChannelIDSource sets a ChannelIDSource that will be called, when the
+  // server supports channel IDs, to obtain a channel ID for signing a message
+  // proving possession of the channel ID. This object takes ownership of
+  // |source|.
+  void SetChannelIDSource(ChannelIDSource* source) {
+    crypto_config_.SetChannelIDSource(source);
+  }
+
+  const ParsedQuicVersionVector& supported_versions() const {
+    return supported_versions_;
+  }
+
+  void SetSupportedVersions(const ParsedQuicVersionVector& versions) {
+    supported_versions_ = versions;
+  }
+
+  QuicConfig* config() { return &config_; }
+
+  QuicCryptoClientConfig* crypto_config() { return &crypto_config_; }
+
+  // Change the initial maximum packet size of the connection.  Has to be called
+  // before Connect()/StartConnect() in order to have any effect.
+  void set_initial_max_packet_length(QuicByteCount initial_max_packet_length) {
+    initial_max_packet_length_ = initial_max_packet_length;
+  }
+
+  int num_stateless_rejects_received() const {
+    return num_stateless_rejects_received_;
+  }
+
+  // The number of client hellos sent, taking stateless rejects into
+  // account.  In the case of a stateless reject, the initial
+  // connection object may be torn down and a new one created.  The
+  // user cannot rely upon the latest connection object to get the
+  // total number of client hellos sent, and should use this function
+  // instead.
+  int GetNumSentClientHellos();
+
+  // Gather the stats for the last session and update the stats for the overall
+  // connection.
+  void UpdateStats();
+
+  // The number of server config updates received.  We assume no
+  // updates can be sent during a previously, statelessly rejected
+  // connection, so only the latest session is taken into account.
+  int GetNumReceivedServerConfigUpdates();
+
+  // Returns any errors that occurred at the connection-level (as
+  // opposed to the session-level).  When a stateless reject occurs,
+  // the error of the last session may not reflect the overall state
+  // of the connection.
+  QuicErrorCode connection_error() const;
+  void set_connection_error(QuicErrorCode connection_error) {
+    connection_error_ = connection_error;
+  }
+
+  bool connected_or_attempting_connect() const {
+    return connected_or_attempting_connect_;
+  }
+  void set_connected_or_attempting_connect(
+      bool connected_or_attempting_connect) {
+    connected_or_attempting_connect_ = connected_or_attempting_connect;
+  }
+
+  QuicPacketWriter* writer() { return writer_.get(); }
+  void set_writer(QuicPacketWriter* writer) {
+    if (writer_.get() != writer) {
+      writer_.reset(writer);
+    }
+  }
+
+  void reset_writer() { writer_.reset(); }
+
+  ProofVerifier* proof_verifier() const;
+
+  void set_bind_to_address(QuicIpAddress address) {
+    bind_to_address_ = address;
+  }
+
+  QuicIpAddress bind_to_address() const { return bind_to_address_; }
+
+  void set_local_port(int local_port) { local_port_ = local_port; }
+
+  int local_port() const { return local_port_; }
+
+  const QuicSocketAddress& server_address() const { return server_address_; }
+
+  void set_server_address(const QuicSocketAddress& server_address) {
+    server_address_ = server_address;
+  }
+
+  QuicConnectionHelperInterface* helper() { return helper_.get(); }
+
+  NetworkHelper* network_helper();
+  const NetworkHelper* network_helper() const;
+
+  bool initialized() const { return initialized_; }
+
+  void SetPreSharedKey(QuicStringPiece key) {
+    crypto_config_.set_pre_shared_key(key);
+  }
+
+ protected:
+  // TODO(rch): Move GetNumSentClientHellosFromSession and
+  // GetNumReceivedServerConfigUpdatesFromSession into a new/better
+  // QuicSpdyClientSession class. The current inherits dependencies from
+  // Spdy. When that happens this class and all its subclasses should
+  // work with QuicSpdyClientSession instead of QuicSession.
+  // That will obviate the need for the pure virtual functions below.
+
+  // Extract the number of sent client hellos from the session.
+  virtual int GetNumSentClientHellosFromSession() = 0;
+
+  // The number of server config updates received.  We assume no
+  // updates can be sent during a previously, statelessly rejected
+  // connection, so only the latest session is taken into account.
+  virtual int GetNumReceivedServerConfigUpdatesFromSession() = 0;
+
+  // If this client supports buffering data, resend it.
+  virtual void ResendSavedData() = 0;
+
+  // If this client supports buffering data, clear it.
+  virtual void ClearDataToResend() = 0;
+
+  // Takes ownership of |connection|. If you override this function,
+  // you probably want to call ResetSession() in your destructor.
+  // TODO(rch): Change the connection parameter to take in a
+  // std::unique_ptr<QuicConnection> instead.
+  virtual std::unique_ptr<QuicSession> CreateQuicClientSession(
+      const ParsedQuicVersionVector& supported_versions,
+      QuicConnection* connection) = 0;
+
+  // Generates the next ConnectionId for |server_id_|.  By default, if the
+  // cached server config contains a server-designated ID, that ID will be
+  // returned.  Otherwise, the next random ID will be returned.
+  QuicConnectionId GetNextConnectionId();
+
+  // Returns the next server-designated ConnectionId from the cached config for
+  // |server_id_|, if it exists.  Otherwise, returns 0.
+  QuicConnectionId GetNextServerDesignatedConnectionId();
+
+  // Generates a new, random connection ID (as opposed to a server-designated
+  // connection ID).
+  virtual QuicConnectionId GenerateNewConnectionId();
+
+  QuicAlarmFactory* alarm_factory() { return alarm_factory_.get(); }
+
+  // Subclasses may need to explicitly clear the session on destruction
+  // if they create it with objects that will be destroyed before this is.
+  // You probably want to call this if you override CreateQuicSpdyClientSession.
+  void ResetSession() { session_.reset(); }
+
+ private:
+  // Returns true and set |version| if client can reconnect with a different
+  // version.
+  bool CanReconnectWithDifferentVersion(ParsedQuicVersion* version) const;
+
+  // |server_id_| is a tuple (hostname, port, is_https) of the server.
+  QuicServerId server_id_;
+
+  // Tracks if the client is initialized to connect.
+  bool initialized_;
+
+  // Address of the server.
+  QuicSocketAddress server_address_;
+
+  // If initialized, the address to bind to.
+  QuicIpAddress bind_to_address_;
+
+  // Local port to bind to. Initialize to 0.
+  int local_port_;
+
+  // config_ and crypto_config_ contain configuration and cached state about
+  // servers.
+  QuicConfig config_;
+  QuicCryptoClientConfig crypto_config_;
+
+  // Helper to be used by created connections. Must outlive |session_|.
+  std::unique_ptr<QuicConnectionHelperInterface> helper_;
+
+  // Alarm factory to be used by created connections. Must outlive |session_|.
+  std::unique_ptr<QuicAlarmFactory> alarm_factory_;
+
+  // Writer used to actually send packets to the wire. Must outlive |session_|.
+  std::unique_ptr<QuicPacketWriter> writer_;
+
+  // Session which manages streams.
+  std::unique_ptr<QuicSession> session_;
+
+  // This vector contains QUIC versions which we currently support.
+  // This should be ordered such that the highest supported version is the first
+  // element, with subsequent elements in descending order (versions can be
+  // skipped as necessary). We will always pick supported_versions_[0] as the
+  // initial version to use.
+  ParsedQuicVersionVector supported_versions_;
+
+  // The initial value of maximum packet size of the connection.  If set to
+  // zero, the default is used.
+  QuicByteCount initial_max_packet_length_;
+
+  // The number of stateless rejects received during the current/latest
+  // connection.
+  // TODO(jokulik): Consider some consistent naming scheme (or other) for member
+  // variables that are kept per-request, per-connection, and over the client's
+  // lifetime.
+  int num_stateless_rejects_received_;
+
+  // The number of hellos sent during the current/latest connection.
+  int num_sent_client_hellos_;
+
+  // Used to store any errors that occurred with the overall connection (as
+  // opposed to that associated with the last session object).
+  QuicErrorCode connection_error_;
+
+  // True when the client is attempting to connect or re-connect the session (in
+  // the case of a stateless reject).  Set to false  between a call to
+  // Disconnect() and the subsequent call to StartConnect().  When
+  // connected_or_attempting_connect_ is false, the session object corresponds
+  // to the previous client-level connection.
+  bool connected_or_attempting_connect_;
+
+  // The network helper used to create sockets and manage the event loop.
+  // Not owned by this class.
+  std::unique_ptr<NetworkHelper> network_helper_;
+};
+
+}  // namespace quic
+
+#endif  // QUICHE_QUIC_TOOLS_QUIC_CLIENT_BASE_H_