// 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.

#ifndef NET_SOCKET_SOCKET_TEST_UTIL_H_
#define NET_SOCKET_SOCKET_TEST_UTIL_H_

#include <stddef.h>
#include <stdint.h>

#include <cstring>
#include <memory>
#include <string>
#include <utility>
#include <vector>

#include "base/callback.h"
#include "base/containers/span.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/memory/ptr_util.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "base/optional.h"
#include "base/strings/string16.h"
#include "build/build_config.h"
#include "net/base/address_list.h"
#include "net/base/completion_once_callback.h"
#include "net/base/io_buffer.h"
#include "net/base/net_errors.h"
#include "net/base/test_completion_callback.h"
#include "net/http/http_auth_controller.h"
#include "net/http/http_proxy_client_socket_pool.h"
#include "net/http/proxy_client_socket.h"
#include "net/log/net_log_with_source.h"
#include "net/socket/client_socket_factory.h"
#include "net/socket/client_socket_handle.h"
#include "net/socket/connection_attempts.h"
#include "net/socket/datagram_client_socket.h"
#include "net/socket/socket_performance_watcher.h"
#include "net/socket/socket_tag.h"
#include "net/socket/socks_client_socket_pool.h"
#include "net/socket/ssl_client_socket.h"
#include "net/socket/ssl_client_socket_pool.h"
#include "net/socket/transport_client_socket.h"
#include "net/socket/transport_client_socket_pool.h"
#include "net/ssl/ssl_config_service.h"
#include "net/traffic_annotation/network_traffic_annotation.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace base {
class RunLoop;
}

namespace net {

class NetLog;

const NetworkChangeNotifier::NetworkHandle kDefaultNetworkForTests = 1;
const NetworkChangeNotifier::NetworkHandle kNewNetworkForTests = 2;

enum {
  // A private network error code used by the socket test utility classes.
  // If the |result| member of a MockRead is
  // ERR_TEST_PEER_CLOSE_AFTER_NEXT_MOCK_READ, that MockRead is just a
  // marker that indicates the peer will close the connection after the next
  // MockRead.  The other members of that MockRead are ignored.
  ERR_TEST_PEER_CLOSE_AFTER_NEXT_MOCK_READ = -10000,
};

class AsyncSocket;
class ChannelIDService;
class MockClientSocket;
class SSLClientSocket;
class StreamSocket;

enum IoMode {
  ASYNC,
  SYNCHRONOUS
};

struct MockConnect {
  // Asynchronous connection success.
  // Creates a MockConnect with |mode| ASYC, |result| OK, and
  // |peer_addr| 192.0.2.33.
  MockConnect();
  // Creates a MockConnect with the specified mode and result, with
  // |peer_addr| 192.0.2.33.
  MockConnect(IoMode io_mode, int r);
  MockConnect(IoMode io_mode, int r, IPEndPoint addr);
  ~MockConnect();

  IoMode mode;
  int result;
  IPEndPoint peer_addr;
};

// MockRead and MockWrite shares the same interface and members, but we'd like
// to have distinct types because we don't want to have them used
// interchangably. To do this, a struct template is defined, and MockRead and
// MockWrite are instantiated by using this template. Template parameter |type|
// is not used in the struct definition (it purely exists for creating a new
// type).
//
// |data| in MockRead and MockWrite has different meanings: |data| in MockRead
// is the data returned from the socket when MockTCPClientSocket::Read() is
// attempted, while |data| in MockWrite is the expected data that should be
// given in MockTCPClientSocket::Write().
enum MockReadWriteType {
  MOCK_READ,
  MOCK_WRITE
};

template <MockReadWriteType type>
struct MockReadWrite {
  // Flag to indicate that the message loop should be terminated.
  enum {
    STOPLOOP = 1 << 31
  };

  // Default
  MockReadWrite()
      : mode(SYNCHRONOUS),
        result(0),
        data(NULL),
        data_len(0),
        sequence_number(0) {}

  // Read/write failure (no data).
  MockReadWrite(IoMode io_mode, int result)
      : mode(io_mode),
        result(result),
        data(NULL),
        data_len(0),
        sequence_number(0) {}

  // Read/write failure (no data), with sequence information.
  MockReadWrite(IoMode io_mode, int result, int seq)
      : mode(io_mode),
        result(result),
        data(NULL),
        data_len(0),
        sequence_number(seq) {}

  // Asynchronous read/write success (inferred data length).
  explicit MockReadWrite(const char* data)
      : mode(ASYNC),
        result(0),
        data(data),
        data_len(strlen(data)),
        sequence_number(0) {}

  // Read/write success (inferred data length).
  MockReadWrite(IoMode io_mode, const char* data)
      : mode(io_mode),
        result(0),
        data(data),
        data_len(strlen(data)),
        sequence_number(0) {}

  // Read/write success.
  MockReadWrite(IoMode io_mode, const char* data, int data_len)
      : mode(io_mode),
        result(0),
        data(data),
        data_len(data_len),
        sequence_number(0) {}

  // Read/write success (inferred data length) with sequence information.
  MockReadWrite(IoMode io_mode, int seq, const char* data)
      : mode(io_mode),
        result(0),
        data(data),
        data_len(strlen(data)),
        sequence_number(seq) {}

  // Read/write success with sequence information.
  MockReadWrite(IoMode io_mode, const char* data, int data_len, int seq)
      : mode(io_mode),
        result(0),
        data(data),
        data_len(data_len),
        sequence_number(seq) {}

  IoMode mode;
  int result;
  const char* data;
  int data_len;

  // For data providers that only allows reads to occur in a particular
  // sequence.  If a read occurs before the given |sequence_number| is reached,
  // an ERR_IO_PENDING is returned.
  int sequence_number;    // The sequence number at which a read is allowed
                          // to occur.
};

typedef MockReadWrite<MOCK_READ> MockRead;
typedef MockReadWrite<MOCK_WRITE> MockWrite;

struct MockWriteResult {
  MockWriteResult(IoMode io_mode, int result) : mode(io_mode), result(result) {}

  IoMode mode;
  int result;
};

// The SocketDataProvider is an interface used by the MockClientSocket
// for getting data about individual reads and writes on the socket.  Can be
// used with at most one socket at a time.
// TODO(mmenke):  Do these really need to be re-useable?
class SocketDataProvider {
 public:
  SocketDataProvider();
  virtual ~SocketDataProvider();

  // Returns the buffer and result code for the next simulated read.
  // If the |MockRead.result| is ERR_IO_PENDING, it informs the caller
  // that it will be called via the AsyncSocket::OnReadComplete()
  // function at a later time.
  virtual MockRead OnRead() = 0;
  virtual MockWriteResult OnWrite(const std::string& data) = 0;
  virtual bool AllReadDataConsumed() const = 0;
  virtual bool AllWriteDataConsumed() const = 0;
  virtual void CancelPendingRead() {}

  virtual void OnEnableTCPFastOpenIfSupported();

  // Returns true if the request should be considered idle, for the purposes of
  // IsConnectedAndIdle.
  virtual bool IsIdle() const;

  // Initializes the SocketDataProvider for use with |socket|.  Must be called
  // before use
  void Initialize(AsyncSocket* socket);
  // Detaches the socket associated with a SocketDataProvider.  Must be called
  // before |socket_| is destroyed, unless the SocketDataProvider has informed
  // |socket_| it was destroyed.  Must also be called before Initialize() may
  // be called again with a new socket.
  void DetachSocket();

  // Accessor for the socket which is using the SocketDataProvider.
  AsyncSocket* socket() { return socket_; }

  MockConnect connect_data() const { return connect_; }
  void set_connect_data(const MockConnect& connect) { connect_ = connect; }

 private:
  // Called to inform subclasses of initialization.
  virtual void Reset() = 0;

  MockConnect connect_;
  AsyncSocket* socket_;

  DISALLOW_COPY_AND_ASSIGN(SocketDataProvider);
};

// The AsyncSocket is an interface used by the SocketDataProvider to
// complete the asynchronous read operation.
class AsyncSocket {
 public:
  // If an async IO is pending because the SocketDataProvider returned
  // ERR_IO_PENDING, then the AsyncSocket waits until this OnReadComplete
  // is called to complete the asynchronous read operation.
  // data.async is ignored, and this read is completed synchronously as
  // part of this call.
  // TODO(rch): this should take a StringPiece since most of the fields
  // are ignored.
  virtual void OnReadComplete(const MockRead& data) = 0;
  // If an async IO is pending because the SocketDataProvider returned
  // ERR_IO_PENDING, then the AsyncSocket waits until this OnReadComplete
  // is called to complete the asynchronous read operation.
  virtual void OnWriteComplete(int rv) = 0;
  virtual void OnConnectComplete(const MockConnect& data) = 0;

  // Called when the SocketDataProvider associated with the socket is destroyed.
  // The socket may continue to be used after the data provider is destroyed,
  // so it should be sure not to dereference the provider after this is called.
  virtual void OnDataProviderDestroyed() = 0;
};

// StaticSocketDataHelper manages a list of reads and writes.
class StaticSocketDataHelper {
 public:
  StaticSocketDataHelper(base::span<const MockRead> reads,
                         base::span<const MockWrite> writes);
  ~StaticSocketDataHelper();

  // These functions get access to the next available read and write data. They
  // CHECK fail if there is no data available.
  const MockRead& PeekRead() const;
  const MockWrite& PeekWrite() const;

  // Returns the current read or write, and then advances to the next one.
  const MockRead& AdvanceRead();
  const MockWrite& AdvanceWrite();

  // Resets the read and write indexes to 0.
  void Reset();

  // Returns true if |data| is valid data for the next write. In order
  // to support short writes, the next write may be longer than |data|
  // in which case this method will still return true.
  bool VerifyWriteData(const std::string& data);

  size_t read_index() const { return read_index_; }
  size_t write_index() const { return write_index_; }
  size_t read_count() const { return reads_.size(); }
  size_t write_count() const { return writes_.size(); }

  bool AllReadDataConsumed() const { return read_index() >= read_count(); }
  bool AllWriteDataConsumed() const { return write_index() >= write_count(); }

 private:
  // Returns the next available read or write that is not a pause event. CHECK
  // fails if no data is available.
  const MockWrite& PeekRealWrite() const;

  const base::span<const MockRead> reads_;
  size_t read_index_;
  const base::span<const MockWrite> writes_;
  size_t write_index_;

  DISALLOW_COPY_AND_ASSIGN(StaticSocketDataHelper);
};

// SocketDataProvider which responds based on static tables of mock reads and
// writes.
class StaticSocketDataProvider : public SocketDataProvider {
 public:
  StaticSocketDataProvider();
  StaticSocketDataProvider(base::span<const MockRead> reads,
                           base::span<const MockWrite> writes);
  ~StaticSocketDataProvider() override;

  // Pause/resume reads from this provider.
  void Pause();
  void Resume();

  // From SocketDataProvider:
  MockRead OnRead() override;
  MockWriteResult OnWrite(const std::string& data) override;
  bool AllReadDataConsumed() const override;
  bool AllWriteDataConsumed() const override;

  size_t read_index() const { return helper_.read_index(); }
  size_t write_index() const { return helper_.write_index(); }
  size_t read_count() const { return helper_.read_count(); }
  size_t write_count() const { return helper_.write_count(); }

 private:
  // From SocketDataProvider:
  void Reset() override;

  StaticSocketDataHelper helper_;
  bool paused_ = false;

  DISALLOW_COPY_AND_ASSIGN(StaticSocketDataProvider);
};

// ProxyClientSocketDataProvider only need to keep track of the return code from
// calls to Connect().
struct ProxyClientSocketDataProvider {
  ProxyClientSocketDataProvider(IoMode mode, int result);
  ProxyClientSocketDataProvider(const ProxyClientSocketDataProvider& other);
  ~ProxyClientSocketDataProvider();

  // Result for Connect().
  MockConnect connect;
};

// SSLSocketDataProviders only need to keep track of the return code from calls
// to Connect().
struct SSLSocketDataProvider {
  SSLSocketDataProvider(IoMode mode, int result);
  SSLSocketDataProvider(const SSLSocketDataProvider& other);
  ~SSLSocketDataProvider();

  // Returns whether MockConnect data has been consumed.
  bool ConnectDataConsumed() const { return is_connect_data_consumed; }

  // Result for Connect().
  MockConnect connect;

  // Result for GetNegotiatedProtocol().
  NextProto next_proto;

  // Result for GetSSLInfo().
  SSLInfo ssl_info;

  // Result for GetSSLCertRequestInfo().
  SSLCertRequestInfo* cert_request_info;

  ChannelIDService* channel_id_service;
  base::Optional<NextProtoVector> next_protos_expected_in_ssl_config;

  uint16_t expected_ssl_version_min;
  uint16_t expected_ssl_version_max;

  bool is_connect_data_consumed = false;
};

// Uses the sequence_number field in the mock reads and writes to
// complete the operations in a specified order.
class SequencedSocketData : public SocketDataProvider {
 public:
  SequencedSocketData();

  // |reads| is the list of MockRead completions.
  // |writes| is the list of MockWrite completions.
  SequencedSocketData(base::span<const MockRead> reads,
                      base::span<const MockWrite> writes);

  // |connect| is the result for the connect phase.
  // |reads| is the list of MockRead completions.
  // |writes| is the list of MockWrite completions.
  SequencedSocketData(const MockConnect& connect,
                      base::span<const MockRead> reads,
                      base::span<const MockWrite> writes);

  ~SequencedSocketData() override;

  // From SocketDataProvider:
  MockRead OnRead() override;
  MockWriteResult OnWrite(const std::string& data) override;
  bool AllReadDataConsumed() const override;
  bool AllWriteDataConsumed() const override;
  void OnEnableTCPFastOpenIfSupported() override;
  bool IsIdle() const override;
  void CancelPendingRead() override;

  // An ASYNC read event with a return value of ERR_IO_PENDING will cause the
  // socket data to pause at that event, and advance no further, until Resume is
  // invoked.  At that point, the socket will continue at the next event in the
  // sequence.
  //
  // If a request just wants to simulate a connection that stays open and never
  // receives any more data, instead of pausing and then resuming a request, it
  // should use a SYNCHRONOUS event with a return value of ERR_IO_PENDING
  // instead.
  bool IsPaused() const;
  // Resumes events once |this| is in the paused state.  The next even will
  // occur synchronously with the call if it can.
  void Resume();
  void RunUntilPaused();

  bool IsUsingTCPFastOpen() const;

  // When true, IsConnectedAndIdle() will return false if the next event in the
  // sequence is a synchronous.  Otherwise, the socket claims to be idle as
  // long as it's connected.  Defaults to false.
  // TODO(mmenke):  See if this can be made the default behavior, and consider
  // removing this mehtod.  Need to make sure it doesn't change what code any
  // tests are targetted at testing.
  void set_busy_before_sync_reads(bool busy_before_sync_reads) {
    busy_before_sync_reads_ = busy_before_sync_reads;
  }

 private:
  // Defines the state for the read or write path.
  enum IoState {
    IDLE,        // No async operation is in progress.
    PENDING,     // An async operation in waiting for another opteration to
                 // complete.
    COMPLETING,  // A task has been posted to complete an async operation.
    PAUSED,      // IO is paused until Resume() is called.
  };

  // From SocketDataProvider:
  void Reset() override;

  void OnReadComplete();
  void OnWriteComplete();

  void MaybePostReadCompleteTask();
  void MaybePostWriteCompleteTask();

  StaticSocketDataHelper helper_;
  int sequence_number_;
  IoState read_state_;
  IoState write_state_;

  bool busy_before_sync_reads_;
  bool is_using_tcp_fast_open_;

  // Used by RunUntilPaused.  NULL at all other times.
  std::unique_ptr<base::RunLoop> run_until_paused_run_loop_;

  base::WeakPtrFactory<SequencedSocketData> weak_factory_;

  DISALLOW_COPY_AND_ASSIGN(SequencedSocketData);
};

// Holds an array of SocketDataProvider elements.  As Mock{TCP,SSL}StreamSocket
// objects get instantiated, they take their data from the i'th element of this
// array.
template <typename T>
class SocketDataProviderArray {
 public:
  SocketDataProviderArray() : next_index_(0) {}

  T* GetNext() {
    DCHECK_LT(next_index_, data_providers_.size());
    return data_providers_[next_index_++];
  }

  void Add(T* data_provider) {
    DCHECK(data_provider);
    data_providers_.push_back(data_provider);
  }

  size_t next_index() { return next_index_; }

  void ResetNextIndex() { next_index_ = 0; }

 private:
  // Index of the next |data_providers_| element to use. Not an iterator
  // because those are invalidated on vector reallocation.
  size_t next_index_;

  // SocketDataProviders to be returned.
  std::vector<T*> data_providers_;
};

class MockUDPClientSocket;
class MockTCPClientSocket;
class MockSSLClientSocket;
class MockProxyClientSocket;

// ClientSocketFactory which contains arrays of sockets of each type.
// You should first fill the arrays using AddMock{SSL,}Socket. When the factory
// is asked to create a socket, it takes next entry from appropriate array.
// You can use ResetNextMockIndexes to reset that next entry index for all mock
// socket types.
class MockClientSocketFactory : public ClientSocketFactory {
 public:
  MockClientSocketFactory();
  ~MockClientSocketFactory() override;

  void AddSocketDataProvider(SocketDataProvider* socket);
  void AddSSLSocketDataProvider(SSLSocketDataProvider* socket);
  void AddProxyClientSocketDataProvider(ProxyClientSocketDataProvider* socket);
  void ResetNextMockIndexes();

  SocketDataProviderArray<SocketDataProvider>& mock_data() {
    return mock_data_;
  }

  void set_enable_read_if_ready(bool enable_read_if_ready) {
    enable_read_if_ready_ = enable_read_if_ready;
  }

  // Uses mock ProxyClientSocket instead of the default ProxyClientSocket.
  void UseMockProxyClientSockets() { use_mock_proxy_client_sockets_ = true; }

  // ClientSocketFactory
  std::unique_ptr<DatagramClientSocket> CreateDatagramClientSocket(
      DatagramSocket::BindType bind_type,
      NetLog* net_log,
      const NetLogSource& source) override;
  std::unique_ptr<TransportClientSocket> CreateTransportClientSocket(
      const AddressList& addresses,
      std::unique_ptr<SocketPerformanceWatcher> socket_performance_watcher,
      NetLog* net_log,
      const NetLogSource& source) override;
  std::unique_ptr<SSLClientSocket> CreateSSLClientSocket(
      std::unique_ptr<ClientSocketHandle> transport_socket,
      const HostPortPair& host_and_port,
      const SSLConfig& ssl_config,
      const SSLClientSocketContext& context) override;
  std::unique_ptr<ProxyClientSocket> CreateProxyClientSocket(
      std::unique_ptr<ClientSocketHandle> transport_socket,
      const std::string& user_agent,
      const HostPortPair& endpoint,
      HttpAuthController* http_auth_controller,
      bool tunnel,
      bool using_spdy,
      NextProto negotiated_protocol,
      bool is_https_proxy,
      const NetworkTrafficAnnotationTag& traffic_annotation) override;
  void ClearSSLSessionCache() override;

  const std::vector<uint16_t>& udp_client_socket_ports() const {
    return udp_client_socket_ports_;
  }

 private:
  SocketDataProviderArray<SocketDataProvider> mock_data_;
  SocketDataProviderArray<SSLSocketDataProvider> mock_ssl_data_;
  SocketDataProviderArray<ProxyClientSocketDataProvider> mock_proxy_data_;
  std::vector<uint16_t> udp_client_socket_ports_;

  // If true, ReadIfReady() is enabled; otherwise ReadIfReady() returns
  // ERR_READ_IF_READY_NOT_IMPLEMENTED.
  bool enable_read_if_ready_;
  bool use_mock_proxy_client_sockets_ = false;

  DISALLOW_COPY_AND_ASSIGN(MockClientSocketFactory);
};

class MockClientSocket : public TransportClientSocket {
 public:
  // The NetLogWithSource is needed to test LoadTimingInfo, which uses NetLog
  // IDs as
  // unique socket IDs.
  explicit MockClientSocket(const NetLogWithSource& net_log);

  // Socket implementation.
  int Read(IOBuffer* buf,
           int buf_len,
           CompletionOnceCallback callback) override = 0;
  int Write(IOBuffer* buf,
            int buf_len,
            CompletionOnceCallback callback,
            const NetworkTrafficAnnotationTag& traffic_annotation) override = 0;
  int SetReceiveBufferSize(int32_t size) override;
  int SetSendBufferSize(int32_t size) override;

  // TransportClientSocket implementation.
  int Bind(const net::IPEndPoint& local_addr) override;
  bool SetNoDelay(bool no_delay) override;
  bool SetKeepAlive(bool enable, int delay) override;

  // StreamSocket implementation.
  int Connect(CompletionOnceCallback callback) override = 0;
  void Disconnect() override;
  bool IsConnected() const override;
  bool IsConnectedAndIdle() const override;
  int GetPeerAddress(IPEndPoint* address) const override;
  int GetLocalAddress(IPEndPoint* address) const override;
  const NetLogWithSource& NetLog() const override;
  bool WasAlpnNegotiated() const override;
  NextProto GetNegotiatedProtocol() const override;
  void GetConnectionAttempts(ConnectionAttempts* out) const override;
  void ClearConnectionAttempts() override {}
  void AddConnectionAttempts(const ConnectionAttempts& attempts) override {}
  int64_t GetTotalReceivedBytes() const override;
  void ApplySocketTag(const SocketTag& tag) override {}

 protected:
  ~MockClientSocket() override;
  void RunCallbackAsync(CompletionOnceCallback callback, int result);
  void RunCallback(CompletionOnceCallback callback, int result);

  // True if Connect completed successfully and Disconnect hasn't been called.
  bool connected_;

  IPEndPoint local_addr_;
  IPEndPoint peer_addr_;

  NetLogWithSource net_log_;

 private:
  base::WeakPtrFactory<MockClientSocket> weak_factory_;

  DISALLOW_COPY_AND_ASSIGN(MockClientSocket);
};

class MockTCPClientSocket : public MockClientSocket, public AsyncSocket {
 public:
  MockTCPClientSocket(const AddressList& addresses,
                      net::NetLog* net_log,
                      SocketDataProvider* socket);
  ~MockTCPClientSocket() override;

  const AddressList& addresses() const { return addresses_; }

  // Socket implementation.
  int Read(IOBuffer* buf,
           int buf_len,
           CompletionOnceCallback callback) override;
  int ReadIfReady(IOBuffer* buf,
                  int buf_len,
                  CompletionOnceCallback callback) override;
  int CancelReadIfReady() override;
  int Write(IOBuffer* buf,
            int buf_len,
            CompletionOnceCallback callback,
            const NetworkTrafficAnnotationTag& traffic_annotation) override;

  // StreamSocket implementation.
  int Connect(CompletionOnceCallback callback) override;
  void Disconnect() override;
  bool IsConnected() const override;
  bool IsConnectedAndIdle() const override;
  int GetPeerAddress(IPEndPoint* address) const override;
  bool WasEverUsed() const override;
  void EnableTCPFastOpenIfSupported() override;
  bool GetSSLInfo(SSLInfo* ssl_info) override;
  void GetConnectionAttempts(ConnectionAttempts* out) const override;
  void ClearConnectionAttempts() override;
  void AddConnectionAttempts(const ConnectionAttempts& attempts) override;

  // AsyncSocket:
  void OnReadComplete(const MockRead& data) override;
  void OnWriteComplete(int rv) override;
  void OnConnectComplete(const MockConnect& data) override;
  void OnDataProviderDestroyed() override;

  void set_enable_read_if_ready(bool enable_read_if_ready) {
    enable_read_if_ready_ = enable_read_if_ready;
  }

 private:
  void RetryRead(int rv);
  int ReadIfReadyImpl(IOBuffer* buf,
                      int buf_len,
                      CompletionOnceCallback callback);

  // Helper method to run |pending_read_if_ready_callback_| if it is not null.
  void RunReadIfReadyCallback(int result);

  AddressList addresses_;

  SocketDataProvider* data_;
  int read_offset_;
  MockRead read_data_;
  bool need_read_data_;

  // True if the peer has closed the connection.  This allows us to simulate
  // the recv(..., MSG_PEEK) call in the IsConnectedAndIdle method of the real
  // TCPClientSocket.
  bool peer_closed_connection_;

  // While an asynchronous read is pending, we save our user-buffer state.
  scoped_refptr<IOBuffer> pending_read_buf_;
  int pending_read_buf_len_;
  CompletionOnceCallback pending_read_callback_;

  // Non-null when a ReadIfReady() is pending.
  CompletionOnceCallback pending_read_if_ready_callback_;

  CompletionOnceCallback pending_connect_callback_;
  CompletionOnceCallback pending_write_callback_;
  bool was_used_to_convey_data_;

  // If true, ReadIfReady() is enabled; otherwise ReadIfReady() returns
  // ERR_READ_IF_READY_NOT_IMPLEMENTED.
  bool enable_read_if_ready_;

  ConnectionAttempts connection_attempts_;

  DISALLOW_COPY_AND_ASSIGN(MockTCPClientSocket);
};

class MockProxyClientSocket : public AsyncSocket, public ProxyClientSocket {
 public:
  MockProxyClientSocket(std::unique_ptr<ClientSocketHandle> transport_socket,
                        HttpAuthController* auth_controller,
                        ProxyClientSocketDataProvider* data);
  ~MockProxyClientSocket() override;
  // ProxyClientSocket implementation.
  const HttpResponseInfo* GetConnectResponseInfo() const override;
  std::unique_ptr<HttpStream> CreateConnectResponseStream() override;
  const scoped_refptr<HttpAuthController>& GetAuthController() const override;
  int RestartWithAuth(CompletionOnceCallback callback) override;
  bool IsUsingSpdy() const override;
  NextProto GetProxyNegotiatedProtocol() const override;

  // Socket implementation.
  int Read(IOBuffer* buf,
           int buf_len,
           CompletionOnceCallback callback) override;
  int ReadIfReady(IOBuffer* buf,
                  int buf_len,
                  CompletionOnceCallback callback) override;
  int Write(IOBuffer* buf,
            int buf_len,
            CompletionOnceCallback callback,
            const NetworkTrafficAnnotationTag& traffic_annotation) override;

  // StreamSocket implementation.
  int Connect(CompletionOnceCallback callback) override;
  void Disconnect() override;
  bool IsConnected() const override;
  bool IsConnectedAndIdle() const override;
  bool WasEverUsed() const override;
  int GetPeerAddress(IPEndPoint* address) const override;
  int GetLocalAddress(IPEndPoint* address) const override;
  bool WasAlpnNegotiated() const override;
  NextProto GetNegotiatedProtocol() const override;
  bool GetSSLInfo(SSLInfo* ssl_info) override;
  void ApplySocketTag(const SocketTag& tag) override;
  const NetLogWithSource& NetLog() const override;
  void GetConnectionAttempts(ConnectionAttempts* out) const override;
  void ClearConnectionAttempts() override {}
  void AddConnectionAttempts(const ConnectionAttempts& attempts) override {}
  int64_t GetTotalReceivedBytes() const override;
  int SetReceiveBufferSize(int32_t size) override;
  int SetSendBufferSize(int32_t size) override;

  // This MockSocket does not implement the manual async IO feature.
  void OnReadComplete(const MockRead& data) override;
  void OnWriteComplete(int rv) override;
  void OnConnectComplete(const MockConnect& data) override;
  void OnDataProviderDestroyed() override {}

 private:
  void RunCallback(CompletionOnceCallback callback, int result);
  void RunCallbackAsync(CompletionOnceCallback callback, int result);

  NetLogWithSource net_log_;
  std::unique_ptr<ClientSocketHandle> transport_;
  ProxyClientSocketDataProvider* data_;
  scoped_refptr<HttpAuthController> auth_controller_;

  base::WeakPtrFactory<MockProxyClientSocket> weak_factory_;

  DISALLOW_COPY_AND_ASSIGN(MockProxyClientSocket);
};

class MockSSLClientSocket : public AsyncSocket, public SSLClientSocket {
 public:
  MockSSLClientSocket(std::unique_ptr<ClientSocketHandle> transport_socket,
                      const HostPortPair& host_and_port,
                      const SSLConfig& ssl_config,
                      SSLSocketDataProvider* socket);
  ~MockSSLClientSocket() override;

  // Socket implementation.
  int Read(IOBuffer* buf,
           int buf_len,
           CompletionOnceCallback callback) override;
  int ReadIfReady(IOBuffer* buf,
                  int buf_len,
                  CompletionOnceCallback callback) override;
  int Write(IOBuffer* buf,
            int buf_len,
            CompletionOnceCallback callback,
            const NetworkTrafficAnnotationTag& traffic_annotation) override;
  int CancelReadIfReady() override;

  // StreamSocket implementation.
  int Connect(CompletionOnceCallback callback) override;
  void Disconnect() override;
  bool IsConnected() const override;
  bool IsConnectedAndIdle() const override;
  bool WasEverUsed() const override;
  int GetPeerAddress(IPEndPoint* address) const override;
  int GetLocalAddress(IPEndPoint* address) const override;
  bool WasAlpnNegotiated() const override;
  NextProto GetNegotiatedProtocol() const override;
  bool GetSSLInfo(SSLInfo* ssl_info) override;
  void GetSSLCertRequestInfo(
      SSLCertRequestInfo* cert_request_info) const override;
  Error GetTokenBindingSignature(crypto::ECPrivateKey* key,
                                 TokenBindingType tb_type,
                                 std::vector<uint8_t>* out) override;
  ChannelIDService* GetChannelIDService() const override;
  crypto::ECPrivateKey* GetChannelIDKey() const override;
  void ApplySocketTag(const SocketTag& tag) override;
  const NetLogWithSource& NetLog() const override;
  void GetConnectionAttempts(ConnectionAttempts* out) const override;
  void ClearConnectionAttempts() override {}
  void AddConnectionAttempts(const ConnectionAttempts& attempts) override {}
  int64_t GetTotalReceivedBytes() const override;
  int SetReceiveBufferSize(int32_t size) override;
  int SetSendBufferSize(int32_t size) override;

  // SSLSocket implementation.
  int ExportKeyingMaterial(const base::StringPiece& label,
                           bool has_context,
                           const base::StringPiece& context,
                           unsigned char* out,
                           unsigned int outlen) override;

  // This MockSocket does not implement the manual async IO feature.
  void OnReadComplete(const MockRead& data) override;
  void OnWriteComplete(int rv) override;
  void OnConnectComplete(const MockConnect& data) override;
  // SSL sockets don't need magic to deal with destruction of their data
  // provider.
  // TODO(mmenke):  Probably a good idea to support it, anyways.
  void OnDataProviderDestroyed() override {}

 private:
  static void ConnectCallback(MockSSLClientSocket* ssl_client_socket,
                              CompletionOnceCallback callback,
                              int rv);

  void RunCallbackAsync(CompletionOnceCallback callback, int result);
  void RunCallback(CompletionOnceCallback callback, int result);

  bool connected_ = false;
  NetLogWithSource net_log_;
  std::unique_ptr<ClientSocketHandle> transport_;
  SSLSocketDataProvider* data_;
  // Address of the "remote" peer we're connected to.
  IPEndPoint peer_addr_;

  base::WeakPtrFactory<MockSSLClientSocket> weak_factory_;

  DISALLOW_COPY_AND_ASSIGN(MockSSLClientSocket);
};

class MockUDPClientSocket : public DatagramClientSocket, public AsyncSocket {
 public:
  MockUDPClientSocket(SocketDataProvider* data, net::NetLog* net_log);
  ~MockUDPClientSocket() override;

  // Socket implementation.
  int Read(IOBuffer* buf,
           int buf_len,
           CompletionOnceCallback callback) override;
  int Write(IOBuffer* buf,
            int buf_len,
            CompletionOnceCallback callback,
            const NetworkTrafficAnnotationTag& traffic_annotation) override;
  int WriteAsync(
      DatagramBuffers buffers,
      CompletionOnceCallback callback,
      const NetworkTrafficAnnotationTag& traffic_annotation) override;
  int WriteAsync(
      const char* buffer,
      size_t buf_len,
      CompletionOnceCallback callback,
      const NetworkTrafficAnnotationTag& traffic_annotation) override;
  DatagramBuffers GetUnwrittenBuffers() override;

  int SetReceiveBufferSize(int32_t size) override;
  int SetSendBufferSize(int32_t size) override;
  int SetDoNotFragment() override;

  // DatagramSocket implementation.
  void Close() override;
  int GetPeerAddress(IPEndPoint* address) const override;
  int GetLocalAddress(IPEndPoint* address) const override;
  void UseNonBlockingIO() override;
  void SetWriteAsyncEnabled(bool enabled) override;
  void SetMaxPacketSize(size_t max_packet_size) override;
  bool WriteAsyncEnabled() override;
  void SetWriteMultiCoreEnabled(bool enabled) override;
  void SetSendmmsgEnabled(bool enabled) override;
  void SetWriteBatchingActive(bool active) override;
  const NetLogWithSource& NetLog() const override;

  // DatagramClientSocket implementation.
  int Connect(const IPEndPoint& address) override;
  int ConnectUsingNetwork(NetworkChangeNotifier::NetworkHandle network,
                          const IPEndPoint& address) override;
  int ConnectUsingDefaultNetwork(const IPEndPoint& address) override;
  NetworkChangeNotifier::NetworkHandle GetBoundNetwork() const override;
  void ApplySocketTag(const SocketTag& tag) override;
  void SetMsgConfirm(bool confirm) override {}

  // AsyncSocket implementation.
  void OnReadComplete(const MockRead& data) override;
  void OnWriteComplete(int rv) override;
  void OnConnectComplete(const MockConnect& data) override;
  void OnDataProviderDestroyed() override;

  void set_source_port(uint16_t port) { source_port_ = port; }
  uint16_t source_port() const { return source_port_; }

  // Returns last tag applied to socket.
  SocketTag tag() const { return tag_; }

  // Returns false if socket's tag was changed after the socket was used for
  // data transfer (e.g. Read/Write() called), otherwise returns true.
  bool tagged_before_data_transferred() const {
    return tagged_before_data_transferred_;
  }

 private:
  int CompleteRead();

  void RunCallbackAsync(CompletionOnceCallback callback, int result);
  void RunCallback(CompletionOnceCallback callback, int result);

  bool connected_;
  SocketDataProvider* data_;
  int read_offset_;
  MockRead read_data_;
  bool need_read_data_;
  uint16_t source_port_;  // Ephemeral source port.

  // Address of the "remote" peer we're connected to.
  IPEndPoint peer_addr_;

  // Network that the socket is bound to.
  NetworkChangeNotifier::NetworkHandle network_;

  // While an asynchronous IO is pending, we save our user-buffer state.
  scoped_refptr<IOBuffer> pending_read_buf_;
  int pending_read_buf_len_;
  CompletionOnceCallback pending_read_callback_;
  CompletionOnceCallback pending_write_callback_;

  NetLogWithSource net_log_;

  DatagramBuffers unwritten_buffers_;

  SocketTag tag_;
  bool data_transferred_ = false;
  bool tagged_before_data_transferred_ = true;

  base::WeakPtrFactory<MockUDPClientSocket> weak_factory_;

  DISALLOW_COPY_AND_ASSIGN(MockUDPClientSocket);
};

class TestSocketRequest : public TestCompletionCallbackBase {
 public:
  TestSocketRequest(std::vector<TestSocketRequest*>* request_order,
                    size_t* completion_count);
  ~TestSocketRequest() override;

  ClientSocketHandle* handle() { return &handle_; }

  CompletionOnceCallback callback() {
    return base::BindOnce(&TestSocketRequest::OnComplete,
                          base::Unretained(this));
  }

 private:
  void OnComplete(int result);

  ClientSocketHandle handle_;
  std::vector<TestSocketRequest*>* request_order_;
  size_t* completion_count_;

  DISALLOW_COPY_AND_ASSIGN(TestSocketRequest);
};

class ClientSocketPoolTest {
 public:
  enum KeepAlive {
    KEEP_ALIVE,

    // A socket will be disconnected in addition to handle being reset.
    NO_KEEP_ALIVE,
  };

  static const int kIndexOutOfBounds;
  static const int kRequestNotFound;

  ClientSocketPoolTest();
  ~ClientSocketPoolTest();

  template <typename PoolType>
  int StartRequestUsingPool(
      PoolType* socket_pool,
      const std::string& group_name,
      RequestPriority priority,
      ClientSocketPool::RespectLimits respect_limits,
      const scoped_refptr<typename PoolType::SocketParams>& socket_params) {
    DCHECK(socket_pool);
    TestSocketRequest* request(
        new TestSocketRequest(&request_order_, &completion_count_));
    requests_.push_back(base::WrapUnique(request));
    int rv = request->handle()->Init(
        group_name, socket_params, priority, SocketTag(), respect_limits,
        request->callback(), socket_pool, NetLogWithSource());
    if (rv != ERR_IO_PENDING)
      request_order_.push_back(request);
    return rv;
  }

  // Provided there were n requests started, takes |index| in range 1..n
  // and returns order in which that request completed, in range 1..n,
  // or kIndexOutOfBounds if |index| is out of bounds, or kRequestNotFound
  // if that request did not complete (for example was canceled).
  int GetOrderOfRequest(size_t index) const;

  // Resets first initialized socket handle from |requests_|. If found such
  // a handle, returns true.
  bool ReleaseOneConnection(KeepAlive keep_alive);

  // Releases connections until there is nothing to release.
  void ReleaseAllConnections(KeepAlive keep_alive);

  // Note that this uses 0-based indices, while GetOrderOfRequest takes and
  // returns 1-based indices.
  TestSocketRequest* request(int i) { return requests_[i].get(); }

  size_t requests_size() const { return requests_.size(); }
  std::vector<std::unique_ptr<TestSocketRequest>>* requests() {
    return &requests_;
  }
  size_t completion_count() const { return completion_count_; }

 private:
  std::vector<std::unique_ptr<TestSocketRequest>> requests_;
  std::vector<TestSocketRequest*> request_order_;
  size_t completion_count_;

  DISALLOW_COPY_AND_ASSIGN(ClientSocketPoolTest);
};

class MockTransportSocketParams
    : public base::RefCounted<MockTransportSocketParams> {
 private:
  friend class base::RefCounted<MockTransportSocketParams>;
  ~MockTransportSocketParams() {}

  DISALLOW_COPY_AND_ASSIGN(MockTransportSocketParams);
};

class MockTransportClientSocketPool : public TransportClientSocketPool {
 public:
  typedef MockTransportSocketParams SocketParams;

  class MockConnectJob {
   public:
    MockConnectJob(std::unique_ptr<StreamSocket> socket,
                   ClientSocketHandle* handle,
                   const SocketTag& socket_tag,
                   CompletionOnceCallback callback);
    ~MockConnectJob();

    int Connect();
    bool CancelHandle(const ClientSocketHandle* handle);

   private:
    void OnConnect(int rv);

    std::unique_ptr<StreamSocket> socket_;
    ClientSocketHandle* handle_;
    const SocketTag socket_tag_;
    CompletionOnceCallback user_callback_;

    DISALLOW_COPY_AND_ASSIGN(MockConnectJob);
  };

  MockTransportClientSocketPool(int max_sockets,
                                int max_sockets_per_group,
                                ClientSocketFactory* socket_factory);

  ~MockTransportClientSocketPool() override;

  RequestPriority last_request_priority() const {
    return last_request_priority_;
  }
  int release_count() const { return release_count_; }
  int cancel_count() const { return cancel_count_; }

  // TransportClientSocketPool implementation.
  int RequestSocket(const std::string& group_name,
                    const void* socket_params,
                    RequestPriority priority,
                    const SocketTag& socket_tag,
                    RespectLimits respect_limits,
                    ClientSocketHandle* handle,
                    CompletionOnceCallback callback,
                    const NetLogWithSource& net_log) override;
  void SetPriority(const std::string& group_name,
                   ClientSocketHandle* handle,
                   RequestPriority priority) override;
  void CancelRequest(const std::string& group_name,
                     ClientSocketHandle* handle) override;
  void ReleaseSocket(const std::string& group_name,
                     std::unique_ptr<StreamSocket> socket,
                     int id) override;

 private:
  ClientSocketFactory* client_socket_factory_;
  std::vector<std::unique_ptr<MockConnectJob>> job_list_;
  RequestPriority last_request_priority_;
  int release_count_;
  int cancel_count_;

  DISALLOW_COPY_AND_ASSIGN(MockTransportClientSocketPool);
};

class MockSOCKSClientSocketPool : public SOCKSClientSocketPool {
 public:
  MockSOCKSClientSocketPool(int max_sockets,
                            int max_sockets_per_group,
                            TransportClientSocketPool* transport_pool);

  ~MockSOCKSClientSocketPool() override;

  // SOCKSClientSocketPool implementation.
  int RequestSocket(const std::string& group_name,
                    const void* socket_params,
                    RequestPriority priority,
                    const SocketTag& socket_tag,
                    RespectLimits respect_limits,
                    ClientSocketHandle* handle,
                    CompletionOnceCallback callback,
                    const NetLogWithSource& net_log) override;
  void SetPriority(const std::string& group_name,
                   ClientSocketHandle* handle,
                   RequestPriority priority) override;
  void CancelRequest(const std::string& group_name,
                     ClientSocketHandle* handle) override;
  void ReleaseSocket(const std::string& group_name,
                     std::unique_ptr<StreamSocket> socket,
                     int id) override;

 private:
  TransportClientSocketPool* const transport_pool_;

  DISALLOW_COPY_AND_ASSIGN(MockSOCKSClientSocketPool);
};

// WrappedStreamSocket is a base class that wraps an existing StreamSocket,
// forwarding the Socket and StreamSocket interfaces to the underlying
// transport.
// This is to provide a common base class for subclasses to override specific
// StreamSocket methods for testing, while still communicating with a 'real'
// StreamSocket.
class WrappedStreamSocket : public TransportClientSocket {
 public:
  explicit WrappedStreamSocket(std::unique_ptr<StreamSocket> transport);
  ~WrappedStreamSocket() override;

  // StreamSocket implementation:
  int Bind(const net::IPEndPoint& local_addr) override;
  int Connect(CompletionOnceCallback callback) override;
  void Disconnect() override;
  bool IsConnected() const override;
  bool IsConnectedAndIdle() const override;
  int GetPeerAddress(IPEndPoint* address) const override;
  int GetLocalAddress(IPEndPoint* address) const override;
  const NetLogWithSource& NetLog() const override;
  bool WasEverUsed() const override;
  bool WasAlpnNegotiated() const override;
  NextProto GetNegotiatedProtocol() const override;
  bool GetSSLInfo(SSLInfo* ssl_info) override;
  void GetConnectionAttempts(ConnectionAttempts* out) const override;
  void ClearConnectionAttempts() override;
  void AddConnectionAttempts(const ConnectionAttempts& attempts) override;
  int64_t GetTotalReceivedBytes() const override;
  void ApplySocketTag(const SocketTag& tag) override;

  // Socket implementation:
  int Read(IOBuffer* buf,
           int buf_len,
           CompletionOnceCallback callback) override;
  int ReadIfReady(IOBuffer* buf,
                  int buf_len,
                  CompletionOnceCallback callback) override;
  int Write(IOBuffer* buf,
            int buf_len,
            CompletionOnceCallback callback,
            const NetworkTrafficAnnotationTag& traffic_annotation) override;
  int SetReceiveBufferSize(int32_t size) override;
  int SetSendBufferSize(int32_t size) override;

 protected:
  std::unique_ptr<StreamSocket> transport_;
};

// StreamSocket that wraps another StreamSocket, but keeps track of any
// SocketTag applied to the socket.
class MockTaggingStreamSocket : public WrappedStreamSocket {
 public:
  explicit MockTaggingStreamSocket(std::unique_ptr<StreamSocket> transport)
      : WrappedStreamSocket(std::move(transport)) {}
  ~MockTaggingStreamSocket() override {}

  // StreamSocket implementation.
  int Connect(CompletionOnceCallback callback) override;
  void ApplySocketTag(const SocketTag& tag) override;

  // Returns false if socket's tag was changed after the socket was connected,
  // otherwise returns true.
  bool tagged_before_connected() const { return tagged_before_connected_; }

  // Returns last tag applied to socket.
  SocketTag tag() const { return tag_; }

 private:
  bool connected_ = false;
  bool tagged_before_connected_ = true;
  SocketTag tag_;

  DISALLOW_COPY_AND_ASSIGN(MockTaggingStreamSocket);
};

// Extend MockClientSocketFactory to return MockTaggingStreamSockets and
// keep track of last socket produced for test inspection.
class MockTaggingClientSocketFactory : public MockClientSocketFactory {
 public:
  MockTaggingClientSocketFactory() = default;

  // ClientSocketFactory implementation.
  std::unique_ptr<DatagramClientSocket> CreateDatagramClientSocket(
      DatagramSocket::BindType bind_type,
      NetLog* net_log,
      const NetLogSource& source) override;
  std::unique_ptr<TransportClientSocket> CreateTransportClientSocket(
      const AddressList& addresses,
      std::unique_ptr<SocketPerformanceWatcher> socket_performance_watcher,
      NetLog* net_log,
      const NetLogSource& source) override;

  // These methods return pointers to last TCP and UDP sockets produced by this
  // factory. NOTE: Socket must still exist, or pointer will be to freed memory.
  MockTaggingStreamSocket* GetLastProducedTCPSocket() const {
    return tcp_socket_;
  }
  MockUDPClientSocket* GetLastProducedUDPSocket() const { return udp_socket_; }

 private:
  MockTaggingStreamSocket* tcp_socket_ = nullptr;
  MockUDPClientSocket* udp_socket_ = nullptr;

  DISALLOW_COPY_AND_ASSIGN(MockTaggingClientSocketFactory);
};

// Constants for a successful SOCKS v4 handshake (connecting to localhost on
// port 80, for the request).
extern const char kSOCKS4OkRequestLocalHostPort80[];
extern const int kSOCKS4OkRequestLocalHostPort80Length;

extern const char kSOCKS4OkReply[];
extern const int kSOCKS4OkReplyLength;

// Constants for a successful SOCKS v5 handshake.
extern const char kSOCKS5GreetRequest[];
extern const int kSOCKS5GreetRequestLength;

extern const char kSOCKS5GreetResponse[];
extern const int kSOCKS5GreetResponseLength;

extern const char kSOCKS5OkRequest[];
extern const int kSOCKS5OkRequestLength;

extern const char kSOCKS5OkResponse[];
extern const int kSOCKS5OkResponseLength;

// Helper function to get the total data size of the MockReads in |reads|.
int64_t CountReadBytes(base::span<const MockRead> reads);

// Helper function to get the total data size of the MockWrites in |writes|.
int64_t CountWriteBytes(base::span<const MockWrite> writes);

#if defined(OS_ANDROID)
// Query the system to find out how many bytes were received with tag
// |expected_tag| for our UID.  Return the count of recieved bytes.
uint64_t GetTaggedBytes(int32_t expected_tag);
#endif

}  // namespace net

#endif  // NET_SOCKET_SOCKET_TEST_UTIL_H_