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.
  
  #include "net/socket/socket_test_util.h"
  
  #include <algorithm>
  #include <utility>
  #include <vector>
  
  #include "base/bind.h"
  #include "base/bind_helpers.h"
  #include "base/compiler_specific.h"
  #include "base/location.h"
  #include "base/logging.h"
  #include "base/memory/ptr_util.h"
  #include "base/run_loop.h"
  #include "base/single_thread_task_runner.h"
  #include "base/threading/thread_task_runner_handle.h"
  #include "base/time/time.h"
  #include "net/base/address_family.h"
  #include "net/base/address_list.h"
  #include "net/base/auth.h"
  #include "net/base/ip_address.h"
  #include "net/base/load_timing_info.h"
  #include "net/http/http_network_session.h"
  #include "net/http/http_request_headers.h"
  #include "net/http/http_response_headers.h"
  #include "net/socket/socket.h"
  #include "net/socket/websocket_endpoint_lock_manager.h"
  #include "net/ssl/ssl_cert_request_info.h"
  #include "net/ssl/ssl_connection_status_flags.h"
  #include "net/ssl/ssl_failure_state.h"
  #include "net/ssl/ssl_info.h"
  #include "testing/gtest/include/gtest/gtest.h"
  
  #define NET_TRACE(level, s) VLOG(level) << s << __FUNCTION__ << "() "
  
  namespace net {
  namespace {
  
  inline char AsciifyHigh(char x) {
    char nybble = static_cast<char>((x >> 4) & 0x0F);
    return nybble + ((nybble < 0x0A) ? '0' : 'A' - 10);
  }
  
  inline char AsciifyLow(char x) {
    char nybble = static_cast<char>((x >> 0) & 0x0F);
    return nybble + ((nybble < 0x0A) ? '0' : 'A' - 10);
  }
  
  inline char Asciify(char x) {
    if ((x < 0) || !isprint(x))
      return '.';
    return x;
  }
  
  void DumpData(const char* data, int data_len) {
    if (logging::LOG_INFO < logging::GetMinLogLevel())
      return;
    DVLOG(1) << "Length:  " << data_len;
    const char* pfx = "Data:    ";
    if (!data || (data_len <= 0)) {
      DVLOG(1) << pfx << "<None>";
    } else {
      int i;
      for (i = 0; i <= (data_len - 4); i += 4) {
        DVLOG(1) << pfx
                 << AsciifyHigh(data[i + 0]) << AsciifyLow(data[i + 0])
                 << AsciifyHigh(data[i + 1]) << AsciifyLow(data[i + 1])
                 << AsciifyHigh(data[i + 2]) << AsciifyLow(data[i + 2])
                 << AsciifyHigh(data[i + 3]) << AsciifyLow(data[i + 3])
                 << "  '"
                 << Asciify(data[i + 0])
                 << Asciify(data[i + 1])
                 << Asciify(data[i + 2])
                 << Asciify(data[i + 3])
                 << "'";
        pfx = "         ";
      }
      // Take care of any 'trailing' bytes, if data_len was not a multiple of 4.
      switch (data_len - i) {
        case 3:
          DVLOG(1) << pfx
                   << AsciifyHigh(data[i + 0]) << AsciifyLow(data[i + 0])
                   << AsciifyHigh(data[i + 1]) << AsciifyLow(data[i + 1])
                   << AsciifyHigh(data[i + 2]) << AsciifyLow(data[i + 2])
                   << "    '"
                   << Asciify(data[i + 0])
                   << Asciify(data[i + 1])
                   << Asciify(data[i + 2])
                   << " '";
          break;
        case 2:
          DVLOG(1) << pfx
                   << AsciifyHigh(data[i + 0]) << AsciifyLow(data[i + 0])
                   << AsciifyHigh(data[i + 1]) << AsciifyLow(data[i + 1])
                   << "      '"
                   << Asciify(data[i + 0])
                   << Asciify(data[i + 1])
                   << "  '";
          break;
        case 1:
          DVLOG(1) << pfx
                   << AsciifyHigh(data[i + 0]) << AsciifyLow(data[i + 0])
                   << "        '"
                   << Asciify(data[i + 0])
                   << "   '";
          break;
      }
    }
  }
  
  template <MockReadWriteType type>
  void DumpMockReadWrite(const MockReadWrite<type>& r) {
    if (logging::LOG_INFO < logging::GetMinLogLevel())
      return;
    DVLOG(1) << "Async:   " << (r.mode == ASYNC)
             << "\nResult:  " << r.result;
    DumpData(r.data, r.data_len);
    const char* stop = (r.sequence_number & MockRead::STOPLOOP) ? " (STOP)" : "";
    DVLOG(1) << "Stage:   " << (r.sequence_number & ~MockRead::STOPLOOP) << stop;
  }
  
  }  // namespace
  
  MockConnect::MockConnect() : mode(ASYNC), result(OK) {
    peer_addr = IPEndPoint(IPAddress(192, 0, 2, 33), 0);
  }
  
  MockConnect::MockConnect(IoMode io_mode, int r) : mode(io_mode), result(r) {
    peer_addr = IPEndPoint(IPAddress(192, 0, 2, 33), 0);
  }
  
  MockConnect::MockConnect(IoMode io_mode, int r, IPEndPoint addr) :
      mode(io_mode),
      result(r),
      peer_addr(addr) {
  }
  
  MockConnect::~MockConnect() {}
  
  void SocketDataProvider::OnEnableTCPFastOpenIfSupported() {}
  
  bool SocketDataProvider::IsIdle() const {
    return true;
  }
  
  void SocketDataProvider::Initialize(AsyncSocket* socket) {
    CHECK(!socket_);
    CHECK(socket);
    socket_ = socket;
    Reset();
  }
  
  void SocketDataProvider::DetachSocket() {
    CHECK(socket_);
    socket_ = nullptr;
  }
  
  SocketDataProvider::SocketDataProvider() : socket_(nullptr) {}
  
  SocketDataProvider::~SocketDataProvider() {
    if (socket_)
      socket_->OnDataProviderDestroyed();
  }
  
  StaticSocketDataHelper::StaticSocketDataHelper(MockRead* reads,
                                                 size_t reads_count,
                                                 MockWrite* writes,
                                                 size_t writes_count)
      : reads_(reads),
        read_index_(0),
        read_count_(reads_count),
        writes_(writes),
        write_index_(0),
        write_count_(writes_count) {
  }
  
  StaticSocketDataHelper::~StaticSocketDataHelper() {
  }
  
  const MockRead& StaticSocketDataHelper::PeekRead() const {
    CHECK(!AllReadDataConsumed());
    return reads_[read_index_];
  }
  
  const MockWrite& StaticSocketDataHelper::PeekWrite() const {
    CHECK(!AllWriteDataConsumed());
    return writes_[write_index_];
  }
  
  const MockRead& StaticSocketDataHelper::AdvanceRead() {
    CHECK(!AllReadDataConsumed());
    return reads_[read_index_++];
  }
  
  const MockWrite& StaticSocketDataHelper::AdvanceWrite() {
    CHECK(!AllWriteDataConsumed());
    return writes_[write_index_++];
  }
  
  bool StaticSocketDataHelper::VerifyWriteData(const std::string& data) {
    CHECK(!AllWriteDataConsumed());
    // Check that what the actual data matches the expectations.
    const MockWrite& next_write = PeekWrite();
    if (!next_write.data)
      return true;
  
    // Note: Partial writes are supported here.  If the expected data
    // is a match, but shorter than the write actually written, that is legal.
    // Example:
    //   Application writes "foobarbaz" (9 bytes)
    //   Expected write was "foo" (3 bytes)
    //   This is a success, and the function returns true.
    std::string expected_data(next_write.data, next_write.data_len);
    std::string actual_data(data.substr(0, next_write.data_len));
    EXPECT_GE(data.length(), expected_data.length());
    EXPECT_EQ(expected_data, actual_data);
    return expected_data == actual_data;
  }
  
  void StaticSocketDataHelper::Reset() {
    read_index_ = 0;
    write_index_ = 0;
  }
  
  StaticSocketDataProvider::StaticSocketDataProvider()
      : StaticSocketDataProvider(nullptr, 0, nullptr, 0) {
  }
  
  StaticSocketDataProvider::StaticSocketDataProvider(MockRead* reads,
                                                     size_t reads_count,
                                                     MockWrite* writes,
                                                     size_t writes_count)
      : helper_(reads, reads_count, writes, writes_count) {
  }
  
  StaticSocketDataProvider::~StaticSocketDataProvider() {
  }
  
  MockRead StaticSocketDataProvider::OnRead() {
    CHECK(!helper_.AllReadDataConsumed());
    return helper_.AdvanceRead();
  }
  
  MockWriteResult StaticSocketDataProvider::OnWrite(const std::string& data) {
    if (helper_.write_count() == 0) {
      // Not using mock writes; succeed synchronously.
      return MockWriteResult(SYNCHRONOUS, data.length());
    }
    EXPECT_FALSE(helper_.AllWriteDataConsumed());
    if (helper_.AllWriteDataConsumed()) {
      // Show what the extra write actually consists of.
      EXPECT_EQ("<unexpected write>", data);
      return MockWriteResult(SYNCHRONOUS, ERR_UNEXPECTED);
    }
  
    // Check that what we are writing matches the expectation.
    // Then give the mocked return value.
    if (!helper_.VerifyWriteData(data))
      return MockWriteResult(SYNCHRONOUS, ERR_UNEXPECTED);
  
    const MockWrite& next_write = helper_.AdvanceWrite();
    // In the case that the write was successful, return the number of bytes
    // written. Otherwise return the error code.
    int result =
        next_write.result == OK ? next_write.data_len : next_write.result;
    return MockWriteResult(next_write.mode, result);
  }
  
  bool StaticSocketDataProvider::AllReadDataConsumed() const {
    return helper_.AllReadDataConsumed();
  }
  
  bool StaticSocketDataProvider::AllWriteDataConsumed() const {
    return helper_.AllWriteDataConsumed();
  }
  
  void StaticSocketDataProvider::Reset() {
    helper_.Reset();
  }
  
  SSLSocketDataProvider::SSLSocketDataProvider(IoMode mode, int result)
      : connect(mode, result),
        next_proto_status(SSLClientSocket::kNextProtoUnsupported),
        client_cert_sent(false),
        cert_request_info(NULL),
        channel_id_sent(false),
        connection_status(0),
        token_binding_negotiated(false) {
    SSLConnectionStatusSetVersion(SSL_CONNECTION_VERSION_TLS1_2,
                                  &connection_status);
    // Set to TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305
    SSLConnectionStatusSetCipherSuite(0xcc14, &connection_status);
  }
  
  SSLSocketDataProvider::SSLSocketDataProvider(
      const SSLSocketDataProvider& other) = default;
  
  SSLSocketDataProvider::~SSLSocketDataProvider() {
  }
  
  void SSLSocketDataProvider::SetNextProto(NextProto proto) {
    next_proto_status = SSLClientSocket::kNextProtoNegotiated;
    next_proto = SSLClientSocket::NextProtoToString(proto);
  }
  
  SequencedSocketData::SequencedSocketData(MockRead* reads,
                                           size_t reads_count,
                                           MockWrite* writes,
                                           size_t writes_count)
      : helper_(reads, reads_count, writes, writes_count),
        sequence_number_(0),
        read_state_(IDLE),
        write_state_(IDLE),
        busy_before_sync_reads_(false),
        is_using_tcp_fast_open_(false),
        weak_factory_(this) {
    // Check that reads and writes have a contiguous set of sequence numbers
    // starting from 0 and working their way up, with no repeats and skipping
    // no values.
    size_t next_read = 0;
    size_t next_write = 0;
    int next_sequence_number = 0;
    bool last_event_was_pause = false;
    while (next_read < reads_count || next_write < writes_count) {
      if (next_read < reads_count &&
          reads[next_read].sequence_number == next_sequence_number) {
        // Check if this is a pause.
        if (reads[next_read].mode == ASYNC &&
            reads[next_read].result == ERR_IO_PENDING) {
          CHECK(!last_event_was_pause) << "Two pauses in a row are not allowed: "
                                       << next_sequence_number;
          last_event_was_pause = true;
        } else if (last_event_was_pause) {
          CHECK_EQ(ASYNC, reads[next_read].mode)
              << "A sync event after a pause makes no sense: "
              << next_sequence_number;
          CHECK_NE(ERR_IO_PENDING, reads[next_read].result)
              << "A pause event after a pause makes no sense: "
              << next_sequence_number;
          last_event_was_pause = false;
        }
  
        ++next_read;
        ++next_sequence_number;
        continue;
      }
      if (next_write < writes_count &&
          writes[next_write].sequence_number == next_sequence_number) {
        // Check if this is a pause.
        if (writes[next_write].mode == ASYNC &&
            writes[next_write].result == ERR_IO_PENDING) {
          CHECK(!last_event_was_pause) << "Two pauses in a row are not allowed: "
                                       << next_sequence_number;
          last_event_was_pause = true;
        } else if (last_event_was_pause) {
          CHECK_EQ(ASYNC, writes[next_write].mode)
              << "A sync event after a pause makes no sense: "
              << next_sequence_number;
          CHECK_NE(ERR_IO_PENDING, writes[next_write].result)
              << "A pause event after a pause makes no sense: "
              << next_sequence_number;
          last_event_was_pause = false;
        }
  
        ++next_write;
        ++next_sequence_number;
        continue;
      }
      CHECK(false) << "Sequence number not found where expected: "
                   << next_sequence_number;
      return;
    }
  
    // Last event must not be a pause.  For the final event to indicate the
    // operation never completes, it should be SYNCHRONOUS and return
    // ERR_IO_PENDING.
    CHECK(!last_event_was_pause);
  
    CHECK_EQ(next_read, reads_count);
    CHECK_EQ(next_write, writes_count);
  }
  
  SequencedSocketData::SequencedSocketData(const MockConnect& connect,
                                           MockRead* reads,
                                           size_t reads_count,
                                           MockWrite* writes,
                                           size_t writes_count)
      : SequencedSocketData(reads, reads_count, writes, writes_count) {
    set_connect_data(connect);
  }
  
  MockRead SequencedSocketData::OnRead() {
    CHECK_EQ(IDLE, read_state_);
    CHECK(!helper_.AllReadDataConsumed());
  
    NET_TRACE(1, " *** ") << "sequence_number: " << sequence_number_;
    const MockRead& next_read = helper_.PeekRead();
    NET_TRACE(1, " *** ") << "next_read: " << next_read.sequence_number;
    CHECK_GE(next_read.sequence_number, sequence_number_);
  
    if (next_read.sequence_number <= sequence_number_) {
      if (next_read.mode == SYNCHRONOUS) {
        NET_TRACE(1, " *** ") << "Returning synchronously";
        DumpMockReadWrite(next_read);
        helper_.AdvanceRead();
        ++sequence_number_;
        MaybePostWriteCompleteTask();
        return next_read;
      }
  
      // If the result is ERR_IO_PENDING, then pause.
      if (next_read.result == ERR_IO_PENDING) {
        NET_TRACE(1, " *** ") << "Pausing read at: " << sequence_number_;
        read_state_ = PAUSED;
        if (run_until_paused_run_loop_)
          run_until_paused_run_loop_->Quit();
        return MockRead(SYNCHRONOUS, ERR_IO_PENDING);
      }
      base::ThreadTaskRunnerHandle::Get()->PostTask(
          FROM_HERE, base::Bind(&SequencedSocketData::OnReadComplete,
                                weak_factory_.GetWeakPtr()));
      CHECK_NE(COMPLETING, write_state_);
      read_state_ = COMPLETING;
    } else if (next_read.mode == SYNCHRONOUS) {
      ADD_FAILURE() << "Unable to perform synchronous IO while stopped";
      return MockRead(SYNCHRONOUS, ERR_UNEXPECTED);
    } else {
      NET_TRACE(1, " *** ") << "Waiting for write to trigger read";
      read_state_ = PENDING;
    }
  
    return MockRead(SYNCHRONOUS, ERR_IO_PENDING);
  }
  
  MockWriteResult SequencedSocketData::OnWrite(const std::string& data) {
    CHECK_EQ(IDLE, write_state_);
    CHECK(!helper_.AllWriteDataConsumed());
  
    NET_TRACE(1, " *** ") << "sequence_number: " << sequence_number_;
    const MockWrite& next_write = helper_.PeekWrite();
    NET_TRACE(1, " *** ") << "next_write: " << next_write.sequence_number;
    CHECK_GE(next_write.sequence_number, sequence_number_);
  
    if (!helper_.VerifyWriteData(data))
      return MockWriteResult(SYNCHRONOUS, ERR_UNEXPECTED);
  
    if (next_write.sequence_number <= sequence_number_) {
      if (next_write.mode == SYNCHRONOUS) {
        helper_.AdvanceWrite();
        ++sequence_number_;
        MaybePostReadCompleteTask();
        // In the case that the write was successful, return the number of bytes
        // written. Otherwise return the error code.
        int rv =
            next_write.result != OK ? next_write.result : next_write.data_len;
        NET_TRACE(1, " *** ") << "Returning synchronously";
        return MockWriteResult(SYNCHRONOUS, rv);
      }
  
      // If the result is ERR_IO_PENDING, then pause.
      if (next_write.result == ERR_IO_PENDING) {
        NET_TRACE(1, " *** ") << "Pausing write at: " << sequence_number_;
        write_state_ = PAUSED;
        if (run_until_paused_run_loop_)
          run_until_paused_run_loop_->Quit();
        return MockWriteResult(SYNCHRONOUS, ERR_IO_PENDING);
      }
  
      NET_TRACE(1, " *** ") << "Posting task to complete write";
      base::ThreadTaskRunnerHandle::Get()->PostTask(
          FROM_HERE, base::Bind(&SequencedSocketData::OnWriteComplete,
                                weak_factory_.GetWeakPtr()));
      CHECK_NE(COMPLETING, read_state_);
      write_state_ = COMPLETING;
    } else if (next_write.mode == SYNCHRONOUS) {
      ADD_FAILURE() << "Unable to perform synchronous IO while stopped";
      return MockWriteResult(SYNCHRONOUS, ERR_UNEXPECTED);
    } else {
      NET_TRACE(1, " *** ") << "Waiting for read to trigger write";
      write_state_ = PENDING;
    }
  
    return MockWriteResult(SYNCHRONOUS, ERR_IO_PENDING);
  }
  
  bool SequencedSocketData::AllReadDataConsumed() const {
    return helper_.AllReadDataConsumed();
  }
  
  bool SequencedSocketData::AllWriteDataConsumed() const {
    return helper_.AllWriteDataConsumed();
  }
  
  void SequencedSocketData::OnEnableTCPFastOpenIfSupported() {
    is_using_tcp_fast_open_ = true;
  }
  
  bool SequencedSocketData::IsIdle() const {
    // If |busy_before_sync_reads_| is not set, always considered idle.  If
    // no reads left, or the next operation is a write, also consider it idle.
    if (!busy_before_sync_reads_ || helper_.AllReadDataConsumed() ||
        helper_.PeekRead().sequence_number != sequence_number_) {
      return true;
    }
  
    // If the next operation is synchronous read, treat the socket as not idle.
    if (helper_.PeekRead().mode == SYNCHRONOUS)
      return false;
    return true;
  }
  
  bool SequencedSocketData::IsPaused() const {
    // Both states should not be paused.
    DCHECK(read_state_ != PAUSED || write_state_ != PAUSED);
    return write_state_ == PAUSED || read_state_ == PAUSED;
  }
  
  void SequencedSocketData::Resume() {
    if (!IsPaused()) {
      ADD_FAILURE() << "Unable to Resume when not paused.";
      return;
    }
  
    sequence_number_++;
    if (read_state_ == PAUSED) {
      read_state_ = PENDING;
      helper_.AdvanceRead();
    } else {  // write_state_ == PAUSED
      write_state_ = PENDING;
      helper_.AdvanceWrite();
    }
  
    if (!helper_.AllWriteDataConsumed() &&
        helper_.PeekWrite().sequence_number == sequence_number_) {
      // The next event hasn't even started yet.  Pausing isn't really needed in
      // that case, but may as well support it.
      if (write_state_ != PENDING)
        return;
      write_state_ = COMPLETING;
      OnWriteComplete();
      return;
    }
  
    CHECK(!helper_.AllReadDataConsumed());
  
    // The next event hasn't even started yet.  Pausing isn't really needed in
    // that case, but may as well support it.
    if (read_state_ != PENDING)
      return;
    read_state_ = COMPLETING;
    OnReadComplete();
  }
  
  void SequencedSocketData::RunUntilPaused() {
    CHECK(!run_until_paused_run_loop_);
  
    if (IsPaused())
      return;
  
    run_until_paused_run_loop_.reset(new base::RunLoop());
    run_until_paused_run_loop_->Run();
    run_until_paused_run_loop_.reset();
    DCHECK(IsPaused());
  }
  
  void SequencedSocketData::MaybePostReadCompleteTask() {
    NET_TRACE(1, " ****** ") << " current: " << sequence_number_;
    // Only trigger the next read to complete if there is already a read pending
    // which should complete at the current sequence number.
    if (read_state_ != PENDING ||
        helper_.PeekRead().sequence_number != sequence_number_) {
      return;
    }
  
    // If the result is ERR_IO_PENDING, then pause.
    if (helper_.PeekRead().result == ERR_IO_PENDING) {
      NET_TRACE(1, " *** ") << "Pausing read at: " << sequence_number_;
      read_state_ = PAUSED;
      if (run_until_paused_run_loop_)
        run_until_paused_run_loop_->Quit();
      return;
    }
  
    NET_TRACE(1, " ****** ") << "Posting task to complete read: "
                             << sequence_number_;
    base::ThreadTaskRunnerHandle::Get()->PostTask(
        FROM_HERE, base::Bind(&SequencedSocketData::OnReadComplete,
                              weak_factory_.GetWeakPtr()));
    CHECK_NE(COMPLETING, write_state_);
    read_state_ = COMPLETING;
  }
  
  bool SequencedSocketData::IsUsingTCPFastOpen() const {
    return is_using_tcp_fast_open_;
  }
  
  void SequencedSocketData::MaybePostWriteCompleteTask() {
    NET_TRACE(1, " ****** ") << " current: " << sequence_number_;
    // Only trigger the next write to complete if there is already a write pending
    // which should complete at the current sequence number.
    if (write_state_ != PENDING ||
        helper_.PeekWrite().sequence_number != sequence_number_) {
      return;
    }
  
    // If the result is ERR_IO_PENDING, then pause.
    if (helper_.PeekWrite().result == ERR_IO_PENDING) {
      NET_TRACE(1, " *** ") << "Pausing write at: " << sequence_number_;
      write_state_ = PAUSED;
      if (run_until_paused_run_loop_)
        run_until_paused_run_loop_->Quit();
      return;
    }
  
    NET_TRACE(1, " ****** ") << "Posting task to complete write: "
                             << sequence_number_;
    base::ThreadTaskRunnerHandle::Get()->PostTask(
        FROM_HERE, base::Bind(&SequencedSocketData::OnWriteComplete,
                              weak_factory_.GetWeakPtr()));
    CHECK_NE(COMPLETING, read_state_);
    write_state_ = COMPLETING;
  }
  
  void SequencedSocketData::Reset() {
    helper_.Reset();
    sequence_number_ = 0;
    read_state_ = IDLE;
    write_state_ = IDLE;
    is_using_tcp_fast_open_ = false;
    weak_factory_.InvalidateWeakPtrs();
  }
  
  void SequencedSocketData::OnReadComplete() {
    CHECK_EQ(COMPLETING, read_state_);
    NET_TRACE(1, " *** ") << "Completing read for: " << sequence_number_;
  
    MockRead data = helper_.AdvanceRead();
    DCHECK_EQ(sequence_number_, data.sequence_number);
    sequence_number_++;
    read_state_ = IDLE;
  
    // The result of this read completing might trigger the completion
    // of a pending write. If so, post a task to complete the write later.
    // Since the socket may call back into the SequencedSocketData
    // from socket()->OnReadComplete(), trigger the write task to be posted
    // before calling that.
    MaybePostWriteCompleteTask();
  
    if (!socket()) {
      NET_TRACE(1, " *** ") << "No socket available to complete read";
      return;
    }
  
    NET_TRACE(1, " *** ") << "Completing socket read for: "
                          << data.sequence_number;
    DumpMockReadWrite(data);
    socket()->OnReadComplete(data);
    NET_TRACE(1, " *** ") << "Done";
  }
  
  void SequencedSocketData::OnWriteComplete() {
    CHECK_EQ(COMPLETING, write_state_);
    NET_TRACE(1, " *** ") << " Completing write for: " << sequence_number_;
  
    const MockWrite& data = helper_.AdvanceWrite();
    DCHECK_EQ(sequence_number_, data.sequence_number);
    sequence_number_++;
    write_state_ = IDLE;
    int rv = data.result == OK ? data.data_len : data.result;
  
    // The result of this write completing might trigger the completion
    // of a pending read. If so, post a task to complete the read later.
    // Since the socket may call back into the SequencedSocketData
    // from socket()->OnWriteComplete(), trigger the write task to be posted
    // before calling that.
    MaybePostReadCompleteTask();
  
    if (!socket()) {
      NET_TRACE(1, " *** ") << "No socket available to complete write";
      return;
    }
  
    NET_TRACE(1, " *** ") << " Completing socket write for: "
                          << data.sequence_number;
    socket()->OnWriteComplete(rv);
    NET_TRACE(1, " *** ") << "Done";
  }
  
  SequencedSocketData::~SequencedSocketData() {
  }
  
  MockClientSocketFactory::MockClientSocketFactory() {}
  
  MockClientSocketFactory::~MockClientSocketFactory() {}
  
  void MockClientSocketFactory::AddSocketDataProvider(
      SocketDataProvider* data) {
    mock_data_.Add(data);
  }
  
  void MockClientSocketFactory::AddSSLSocketDataProvider(
      SSLSocketDataProvider* data) {
    mock_ssl_data_.Add(data);
  }
  
  void MockClientSocketFactory::ResetNextMockIndexes() {
    mock_data_.ResetNextIndex();
    mock_ssl_data_.ResetNextIndex();
  }
  
  std::unique_ptr<DatagramClientSocket>
  MockClientSocketFactory::CreateDatagramClientSocket(
      DatagramSocket::BindType bind_type,
      const RandIntCallback& rand_int_cb,
      NetLog* net_log,
      const NetLog::Source& source) {
    SocketDataProvider* data_provider = mock_data_.GetNext();
    std::unique_ptr<MockUDPClientSocket> socket(
        new MockUDPClientSocket(data_provider, net_log));
    if (bind_type == DatagramSocket::RANDOM_BIND)
      socket->set_source_port(
          static_cast<uint16_t>(rand_int_cb.Run(1025, 65535)));
    udp_client_socket_ports_.push_back(socket->source_port());
    return std::move(socket);
  }
  
  std::unique_ptr<StreamSocket>
  MockClientSocketFactory::CreateTransportClientSocket(
      const AddressList& addresses,
      std::unique_ptr<SocketPerformanceWatcher> socket_performance_watcher,
      NetLog* net_log,
      const NetLog::Source& source) {
    SocketDataProvider* data_provider = mock_data_.GetNext();
    std::unique_ptr<MockTCPClientSocket> socket(
        new MockTCPClientSocket(addresses, net_log, data_provider));
    return std::move(socket);
  }
  
  std::unique_ptr<SSLClientSocket> MockClientSocketFactory::CreateSSLClientSocket(
      std::unique_ptr<ClientSocketHandle> transport_socket,
      const HostPortPair& host_and_port,
      const SSLConfig& ssl_config,
      const SSLClientSocketContext& context) {
    SSLSocketDataProvider* next_ssl_data = mock_ssl_data_.GetNext();
    if (!next_ssl_data->next_protos_expected_in_ssl_config.empty()) {
      EXPECT_EQ(next_ssl_data->next_protos_expected_in_ssl_config.size(),
                ssl_config.alpn_protos.size());
      EXPECT_TRUE(
          std::equal(next_ssl_data->next_protos_expected_in_ssl_config.begin(),
                     next_ssl_data->next_protos_expected_in_ssl_config.end(),
                     ssl_config.alpn_protos.begin()));
    }
    return std::unique_ptr<SSLClientSocket>(new MockSSLClientSocket(
        std::move(transport_socket), host_and_port, ssl_config, next_ssl_data));
  }
  
  void MockClientSocketFactory::ClearSSLSessionCache() {
  }
  
  MockClientSocket::MockClientSocket(const BoundNetLog& net_log)
      : connected_(false),
        net_log_(net_log),
        weak_factory_(this) {
    peer_addr_ = IPEndPoint(IPAddress(192, 0, 2, 33), 0);
  }
  
  int MockClientSocket::SetReceiveBufferSize(int32_t size) {
    return OK;
  }
  
  int MockClientSocket::SetSendBufferSize(int32_t size) {
    return OK;
  }
  
  void MockClientSocket::Disconnect() {
    connected_ = false;
  }
  
  bool MockClientSocket::IsConnected() const {
    return connected_;
  }
  
  bool MockClientSocket::IsConnectedAndIdle() const {
    return connected_;
  }
  
  int MockClientSocket::GetPeerAddress(IPEndPoint* address) const {
    if (!IsConnected())
      return ERR_SOCKET_NOT_CONNECTED;
    *address = peer_addr_;
    return OK;
  }
  
  int MockClientSocket::GetLocalAddress(IPEndPoint* address) const {
    *address = IPEndPoint(IPAddress(192, 0, 2, 33), 123);
    return OK;
  }
  
  const BoundNetLog& MockClientSocket::NetLog() const {
    return net_log_;
  }
  
  void MockClientSocket::GetConnectionAttempts(ConnectionAttempts* out) const {
    out->clear();
  }
  
  int64_t MockClientSocket::GetTotalReceivedBytes() const {
    NOTIMPLEMENTED();
    return 0;
  }
  
  void MockClientSocket::GetSSLCertRequestInfo(
    SSLCertRequestInfo* cert_request_info) {
  }
  
  int MockClientSocket::ExportKeyingMaterial(const base::StringPiece& label,
                                             bool has_context,
                                             const base::StringPiece& context,
                                             unsigned char* out,
                                             unsigned int outlen) {
    memset(out, 'A', outlen);
    return OK;
  }
  
  ChannelIDService* MockClientSocket::GetChannelIDService() const {
    NOTREACHED();
    return NULL;
  }
  
  Error MockClientSocket::GetSignedEKMForTokenBinding(crypto::ECPrivateKey* key,
                                                      std::vector<uint8_t>* out) {
    NOTREACHED();
    return ERR_NOT_IMPLEMENTED;
  }
  
  crypto::ECPrivateKey* MockClientSocket::GetChannelIDKey() const {
    NOTREACHED();
    return NULL;
  }
  
  SSLFailureState MockClientSocket::GetSSLFailureState() const {
    return IsConnected() ? SSL_FAILURE_NONE : SSL_FAILURE_UNKNOWN;
  }
  
  SSLClientSocket::NextProtoStatus MockClientSocket::GetNextProto(
      std::string* proto) const {
    proto->clear();
    return SSLClientSocket::kNextProtoUnsupported;
  }
  
  MockClientSocket::~MockClientSocket() {}
  
  void MockClientSocket::RunCallbackAsync(const CompletionCallback& callback,
                                          int result) {
    base::ThreadTaskRunnerHandle::Get()->PostTask(
        FROM_HERE, base::Bind(&MockClientSocket::RunCallback,
                              weak_factory_.GetWeakPtr(), callback, result));
  }
  
  void MockClientSocket::RunCallback(const CompletionCallback& callback,
                                     int result) {
    if (!callback.is_null())
      callback.Run(result);
  }
  
  MockTCPClientSocket::MockTCPClientSocket(const AddressList& addresses,
                                           net::NetLog* net_log,
                                           SocketDataProvider* data)
      : MockClientSocket(BoundNetLog::Make(net_log, NetLog::SOURCE_NONE)),
        addresses_(addresses),
        data_(data),
        read_offset_(0),
        read_data_(SYNCHRONOUS, ERR_UNEXPECTED),
        need_read_data_(true),
        peer_closed_connection_(false),
        pending_read_buf_(NULL),
        pending_read_buf_len_(0),
        was_used_to_convey_data_(false) {
    DCHECK(data_);
    peer_addr_ = data->connect_data().peer_addr;
    data_->Initialize(this);
  }
  
  MockTCPClientSocket::~MockTCPClientSocket() {
    if (data_)
      data_->DetachSocket();
  }
  
  int MockTCPClientSocket::Read(IOBuffer* buf, int buf_len,
                                const CompletionCallback& callback) {
    if (!connected_ || !data_)
      return ERR_UNEXPECTED;
  
    // If the buffer is already in use, a read is already in progress!
    DCHECK(pending_read_buf_.get() == NULL);
  
    // Store our async IO data.
    pending_read_buf_ = buf;
    pending_read_buf_len_ = buf_len;
    pending_read_callback_ = callback;
  
    if (need_read_data_) {
      read_data_ = data_->OnRead();
      if (read_data_.result == ERR_CONNECTION_CLOSED) {
        // This MockRead is just a marker to instruct us to set
        // peer_closed_connection_.
        peer_closed_connection_ = true;
      }
      if (read_data_.result == ERR_TEST_PEER_CLOSE_AFTER_NEXT_MOCK_READ) {
        // This MockRead is just a marker to instruct us to set
        // peer_closed_connection_.  Skip it and get the next one.
        read_data_ = data_->OnRead();
        peer_closed_connection_ = true;
      }
      // ERR_IO_PENDING means that the SocketDataProvider is taking responsibility
      // to complete the async IO manually later (via OnReadComplete).
      if (read_data_.result == ERR_IO_PENDING) {
        // We need to be using async IO in this case.
        DCHECK(!callback.is_null());
        return ERR_IO_PENDING;
      }
      need_read_data_ = false;
    }
  
    return CompleteRead();
  }
  
  int MockTCPClientSocket::Write(IOBuffer* buf, int buf_len,
                                 const CompletionCallback& callback) {
    DCHECK(buf);
    DCHECK_GT(buf_len, 0);
  
    if (!connected_ || !data_)
      return ERR_UNEXPECTED;
  
    std::string data(buf->data(), buf_len);
    MockWriteResult write_result = data_->OnWrite(data);
  
    was_used_to_convey_data_ = true;
  
    // ERR_IO_PENDING is a signal that the socket data will call back
    // asynchronously later.
    if (write_result.result == ERR_IO_PENDING) {
      pending_write_callback_ = callback;
      return ERR_IO_PENDING;
    }
  
    if (write_result.mode == ASYNC) {
      RunCallbackAsync(callback, write_result.result);
      return ERR_IO_PENDING;
    }
  
    return write_result.result;
  }
  
  void MockTCPClientSocket::GetConnectionAttempts(ConnectionAttempts* out) const {
    *out = connection_attempts_;
  }
  
  void MockTCPClientSocket::ClearConnectionAttempts() {
    connection_attempts_.clear();
  }
  
  void MockTCPClientSocket::AddConnectionAttempts(
      const ConnectionAttempts& attempts) {
    connection_attempts_.insert(connection_attempts_.begin(), attempts.begin(),
                                attempts.end());
  }
  
  int MockTCPClientSocket::Connect(const CompletionCallback& callback) {
    if (!data_)
      return ERR_UNEXPECTED;
  
    if (connected_)
      return OK;
    connected_ = true;
    peer_closed_connection_ = false;
  
    int result = data_->connect_data().result;
    IoMode mode = data_->connect_data().mode;
  
    if (result != OK && result != ERR_IO_PENDING) {
      IPEndPoint address;
      if (GetPeerAddress(&address) == OK)
        connection_attempts_.push_back(ConnectionAttempt(address, result));
    }
  
    if (mode == SYNCHRONOUS)
      return result;
  
    if (result == ERR_IO_PENDING)
      pending_connect_callback_ = callback;
    else
      RunCallbackAsync(callback, result);
    return ERR_IO_PENDING;
  }
  
  void MockTCPClientSocket::Disconnect() {
    MockClientSocket::Disconnect();
    pending_connect_callback_.Reset();
    pending_read_callback_.Reset();
  }
  
  bool MockTCPClientSocket::IsConnected() const {
    if (!data_)
      return false;
    return connected_ && !peer_closed_connection_;
  }
  
  bool MockTCPClientSocket::IsConnectedAndIdle() const {
    if (!data_)
      return false;
    return IsConnected() && data_->IsIdle();
  }
  
  int MockTCPClientSocket::GetPeerAddress(IPEndPoint* address) const {
    if (addresses_.empty())
      return MockClientSocket::GetPeerAddress(address);
  
    *address = addresses_[0];
    return OK;
  }
  
  bool MockTCPClientSocket::WasEverUsed() const {
    return was_used_to_convey_data_;
  }
  
  void MockTCPClientSocket::EnableTCPFastOpenIfSupported() {
    EXPECT_FALSE(IsConnected()) << "Can't enable fast open after connect.";
  
    data_->OnEnableTCPFastOpenIfSupported();
  }
  
  bool MockTCPClientSocket::WasNpnNegotiated() const {
    return false;
  }
  
  bool MockTCPClientSocket::GetSSLInfo(SSLInfo* ssl_info) {
    return false;
  }
  
  void MockTCPClientSocket::OnReadComplete(const MockRead& data) {
    // If |data_| has been destroyed, safest to just do nothing.
    if (!data_)
      return;
  
    // There must be a read pending.
    DCHECK(pending_read_buf_.get());
    // You can't complete a read with another ERR_IO_PENDING status code.
    DCHECK_NE(ERR_IO_PENDING, data.result);
    // Since we've been waiting for data, need_read_data_ should be true.
    DCHECK(need_read_data_);
  
    read_data_ = data;
    need_read_data_ = false;
  
    // The caller is simulating that this IO completes right now.  Don't
    // let CompleteRead() schedule a callback.
    read_data_.mode = SYNCHRONOUS;
  
    CompletionCallback callback = pending_read_callback_;
    int rv = CompleteRead();
    RunCallback(callback, rv);
  }
  
  void MockTCPClientSocket::OnWriteComplete(int rv) {
    // If |data_| has been destroyed, safest to just do nothing.
    if (!data_)
      return;
  
    // There must be a read pending.
    DCHECK(!pending_write_callback_.is_null());
    CompletionCallback callback = pending_write_callback_;
    RunCallback(callback, rv);
  }
  
  void MockTCPClientSocket::OnConnectComplete(const MockConnect& data) {
    // If |data_| has been destroyed, safest to just do nothing.
    if (!data_)
      return;
  
    CompletionCallback callback = pending_connect_callback_;
    RunCallback(callback, data.result);
  }
  
  void MockTCPClientSocket::OnDataProviderDestroyed() {
    data_ = nullptr;
  }
  
  int MockTCPClientSocket::CompleteRead() {
    DCHECK(pending_read_buf_.get());
    DCHECK(pending_read_buf_len_ > 0);
  
    was_used_to_convey_data_ = true;
  
    // Save the pending async IO data and reset our |pending_| state.
    scoped_refptr<IOBuffer> buf = pending_read_buf_;
    int buf_len = pending_read_buf_len_;
    CompletionCallback callback = pending_read_callback_;
    pending_read_buf_ = NULL;
    pending_read_buf_len_ = 0;
    pending_read_callback_.Reset();
  
    int result = read_data_.result;
    DCHECK(result != ERR_IO_PENDING);
  
    if (read_data_.data) {
      if (read_data_.data_len - read_offset_ > 0) {
        result = std::min(buf_len, read_data_.data_len - read_offset_);
        memcpy(buf->data(), read_data_.data + read_offset_, result);
        read_offset_ += result;
        if (read_offset_ == read_data_.data_len) {
          need_read_data_ = true;
          read_offset_ = 0;
        }
      } else {
        result = 0;  // EOF
      }
    }
  
    if (read_data_.mode == ASYNC) {
      DCHECK(!callback.is_null());
      RunCallbackAsync(callback, result);
      return ERR_IO_PENDING;
    }
    return result;
  }
  
  // static
  void MockSSLClientSocket::ConnectCallback(
      MockSSLClientSocket* ssl_client_socket,
      const CompletionCallback& callback,
      int rv) {
    if (rv == OK)
      ssl_client_socket->connected_ = true;
    callback.Run(rv);
  }
  
  MockSSLClientSocket::MockSSLClientSocket(
      std::unique_ptr<ClientSocketHandle> transport_socket,
      const HostPortPair& host_port_pair,
      const SSLConfig& ssl_config,
      SSLSocketDataProvider* data)
      : MockClientSocket(
            // Have to use the right BoundNetLog for LoadTimingInfo regression
            // tests.
            transport_socket->socket()->NetLog()),
        transport_(std::move(transport_socket)),
        data_(data) {
    DCHECK(data_);
    peer_addr_ = data->connect.peer_addr;
  }
  
  MockSSLClientSocket::~MockSSLClientSocket() {
    Disconnect();
  }
  
  int MockSSLClientSocket::Read(IOBuffer* buf, int buf_len,
                                const CompletionCallback& callback) {
    return transport_->socket()->Read(buf, buf_len, callback);
  }
  
  int MockSSLClientSocket::Write(IOBuffer* buf, int buf_len,
                                 const CompletionCallback& callback) {
    return transport_->socket()->Write(buf, buf_len, callback);
  }
  
  int MockSSLClientSocket::Connect(const CompletionCallback& callback) {
    int rv = transport_->socket()->Connect(
        base::Bind(&ConnectCallback, base::Unretained(this), callback));
    if (rv == OK) {
      if (data_->connect.result == OK)
        connected_ = true;
      if (data_->connect.mode == ASYNC) {
        RunCallbackAsync(callback, data_->connect.result);
        return ERR_IO_PENDING;
      }
      return data_->connect.result;
    }
    return rv;
  }
  
  void MockSSLClientSocket::Disconnect() {
    MockClientSocket::Disconnect();
    if (transport_->socket() != NULL)
      transport_->socket()->Disconnect();
  }
  
  bool MockSSLClientSocket::IsConnected() const {
    return transport_->socket()->IsConnected();
  }
  
  bool MockSSLClientSocket::IsConnectedAndIdle() const {
    return transport_->socket()->IsConnectedAndIdle();
  }
  
  bool MockSSLClientSocket::WasEverUsed() const {
    return transport_->socket()->WasEverUsed();
  }
  
  int MockSSLClientSocket::GetPeerAddress(IPEndPoint* address) const {
    return transport_->socket()->GetPeerAddress(address);
  }
  
  bool MockSSLClientSocket::GetSSLInfo(SSLInfo* ssl_info) {
    ssl_info->Reset();
    ssl_info->cert = data_->cert;
    ssl_info->client_cert_sent = data_->client_cert_sent;
    ssl_info->channel_id_sent = data_->channel_id_sent;
    ssl_info->connection_status = data_->connection_status;
    ssl_info->token_binding_negotiated = data_->token_binding_negotiated;
    ssl_info->token_binding_key_param = data_->token_binding_key_param;
    return true;
  }
  
  void MockSSLClientSocket::GetSSLCertRequestInfo(
      SSLCertRequestInfo* cert_request_info) {
    DCHECK(cert_request_info);
    if (data_->cert_request_info) {
      cert_request_info->host_and_port =
          data_->cert_request_info->host_and_port;
      cert_request_info->client_certs = data_->cert_request_info->client_certs;
    } else {
      cert_request_info->Reset();
    }
  }
  
  SSLClientSocket::NextProtoStatus MockSSLClientSocket::GetNextProto(
      std::string* proto) const {
    *proto = data_->next_proto;
    return data_->next_proto_status;
  }
  
  ChannelIDService* MockSSLClientSocket::GetChannelIDService() const {
    return data_->channel_id_service;
  }
  
  Error MockSSLClientSocket::GetSignedEKMForTokenBinding(
      crypto::ECPrivateKey* key,
      std::vector<uint8_t>* out) {
    out->push_back('A');
    return OK;
  }
  
  void MockSSLClientSocket::OnReadComplete(const MockRead& data) {
    NOTIMPLEMENTED();
  }
  
  void MockSSLClientSocket::OnWriteComplete(int rv) {
    NOTIMPLEMENTED();
  }
  
  void MockSSLClientSocket::OnConnectComplete(const MockConnect& data) {
    NOTIMPLEMENTED();
  }
  
  MockUDPClientSocket::MockUDPClientSocket(SocketDataProvider* data,
                                           net::NetLog* net_log)
      : connected_(false),
        data_(data),
        read_offset_(0),
        read_data_(SYNCHRONOUS, ERR_UNEXPECTED),
        need_read_data_(true),
        source_port_(123),
        network_(NetworkChangeNotifier::kInvalidNetworkHandle),
        pending_read_buf_(NULL),
        pending_read_buf_len_(0),
        net_log_(BoundNetLog::Make(net_log, NetLog::SOURCE_NONE)),
        weak_factory_(this) {
    DCHECK(data_);
    data_->Initialize(this);
    peer_addr_ = data->connect_data().peer_addr;
  }
  
  MockUDPClientSocket::~MockUDPClientSocket() {
    if (data_)
      data_->DetachSocket();
  }
  
  int MockUDPClientSocket::Read(IOBuffer* buf,
                                int buf_len,
                                const CompletionCallback& callback) {
    if (!connected_ || !data_)
      return ERR_UNEXPECTED;
  
    // If the buffer is already in use, a read is already in progress!
    DCHECK(pending_read_buf_.get() == NULL);
  
    // Store our async IO data.
    pending_read_buf_ = buf;
    pending_read_buf_len_ = buf_len;
    pending_read_callback_ = callback;
  
    if (need_read_data_) {
      read_data_ = data_->OnRead();
      // ERR_IO_PENDING means that the SocketDataProvider is taking responsibility
      // to complete the async IO manually later (via OnReadComplete).
      if (read_data_.result == ERR_IO_PENDING) {
        // We need to be using async IO in this case.
        DCHECK(!callback.is_null());
        return ERR_IO_PENDING;
      }
      need_read_data_ = false;
    }
  
    return CompleteRead();
  }
  
  int MockUDPClientSocket::Write(IOBuffer* buf, int buf_len,
                                 const CompletionCallback& callback) {
    DCHECK(buf);
    DCHECK_GT(buf_len, 0);
  
    if (!connected_ || !data_)
      return ERR_UNEXPECTED;
  
    std::string data(buf->data(), buf_len);
    MockWriteResult write_result = data_->OnWrite(data);
  
    // ERR_IO_PENDING is a signal that the socket data will call back
    // asynchronously.
    if (write_result.result == ERR_IO_PENDING) {
      pending_write_callback_ = callback;
      return ERR_IO_PENDING;
    }
    if (write_result.mode == ASYNC) {
      RunCallbackAsync(callback, write_result.result);
      return ERR_IO_PENDING;
    }
    return write_result.result;
  }
  
  int MockUDPClientSocket::SetReceiveBufferSize(int32_t size) {
    return OK;
  }
  
  int MockUDPClientSocket::SetSendBufferSize(int32_t size) {
    return OK;
  }
  
  void MockUDPClientSocket::Close() {
    connected_ = false;
  }
  
  int MockUDPClientSocket::GetPeerAddress(IPEndPoint* address) const {
    *address = peer_addr_;
    return OK;
  }
  
  int MockUDPClientSocket::GetLocalAddress(IPEndPoint* address) const {
    *address = IPEndPoint(IPAddress(192, 0, 2, 33), source_port_);
    return OK;
  }
  
  const BoundNetLog& MockUDPClientSocket::NetLog() const {
    return net_log_;
  }
  
  int MockUDPClientSocket::Connect(const IPEndPoint& address) {
    if (!data_)
      return ERR_UNEXPECTED;
    connected_ = true;
    peer_addr_ = address;
    return data_->connect_data().result;
  }
  
  int MockUDPClientSocket::ConnectUsingNetwork(
      NetworkChangeNotifier::NetworkHandle network,
      const IPEndPoint& address) {
    DCHECK(!connected_);
    if (!data_)
      return ERR_UNEXPECTED;
    network_ = network;
    connected_ = true;
    peer_addr_ = address;
    return data_->connect_data().result;
  }
  
  int MockUDPClientSocket::ConnectUsingDefaultNetwork(const IPEndPoint& address) {
    DCHECK(!connected_);
    if (!data_)
      return ERR_UNEXPECTED;
    network_ = kDefaultNetworkForTests;
    connected_ = true;
    peer_addr_ = address;
    return data_->connect_data().result;
  }
  
  NetworkChangeNotifier::NetworkHandle MockUDPClientSocket::GetBoundNetwork()
      const {
    return network_;
  }
  
  void MockUDPClientSocket::OnReadComplete(const MockRead& data) {
    if (!data_)
      return;
  
    // There must be a read pending.
    DCHECK(pending_read_buf_.get());
    // You can't complete a read with another ERR_IO_PENDING status code.
    DCHECK_NE(ERR_IO_PENDING, data.result);
    // Since we've been waiting for data, need_read_data_ should be true.
    DCHECK(need_read_data_);
  
    read_data_ = data;
    need_read_data_ = false;
  
    // The caller is simulating that this IO completes right now.  Don't
    // let CompleteRead() schedule a callback.
    read_data_.mode = SYNCHRONOUS;
  
    CompletionCallback callback = pending_read_callback_;
    int rv = CompleteRead();
    RunCallback(callback, rv);
  }
  
  void MockUDPClientSocket::OnWriteComplete(int rv) {
    if (!data_)
      return;
  
    // There must be a read pending.
    DCHECK(!pending_write_callback_.is_null());
    CompletionCallback callback = pending_write_callback_;
    RunCallback(callback, rv);
  }
  
  void MockUDPClientSocket::OnConnectComplete(const MockConnect& data) {
    NOTIMPLEMENTED();
  }
  
  void MockUDPClientSocket::OnDataProviderDestroyed() {
    data_ = nullptr;
  }
  
  int MockUDPClientSocket::CompleteRead() {
    DCHECK(pending_read_buf_.get());
    DCHECK(pending_read_buf_len_ > 0);
  
    // Save the pending async IO data and reset our |pending_| state.
    scoped_refptr<IOBuffer> buf = pending_read_buf_;
    int buf_len = pending_read_buf_len_;
    CompletionCallback callback = pending_read_callback_;
    pending_read_buf_ = NULL;
    pending_read_buf_len_ = 0;
    pending_read_callback_.Reset();
  
    int result = read_data_.result;
    DCHECK(result != ERR_IO_PENDING);
  
    if (read_data_.data) {
      if (read_data_.data_len - read_offset_ > 0) {
        result = std::min(buf_len, read_data_.data_len - read_offset_);
        memcpy(buf->data(), read_data_.data + read_offset_, result);
        read_offset_ += result;
        if (read_offset_ == read_data_.data_len) {
          need_read_data_ = true;
          read_offset_ = 0;
        }
      } else {
        result = 0;  // EOF
      }
    }
  
    if (read_data_.mode == ASYNC) {
      DCHECK(!callback.is_null());
      RunCallbackAsync(callback, result);
      return ERR_IO_PENDING;
    }
    return result;
  }
  
  void MockUDPClientSocket::RunCallbackAsync(const CompletionCallback& callback,
                                             int result) {
    base::ThreadTaskRunnerHandle::Get()->PostTask(
        FROM_HERE, base::Bind(&MockUDPClientSocket::RunCallback,
                              weak_factory_.GetWeakPtr(), callback, result));
  }
  
  void MockUDPClientSocket::RunCallback(const CompletionCallback& callback,
                                        int result) {
    if (!callback.is_null())
      callback.Run(result);
  }
  
  TestSocketRequest::TestSocketRequest(
      std::vector<TestSocketRequest*>* request_order, size_t* completion_count)
      : request_order_(request_order),
        completion_count_(completion_count),
        callback_(base::Bind(&TestSocketRequest::OnComplete,
                             base::Unretained(this))) {
    DCHECK(request_order);
    DCHECK(completion_count);
  }
  
  TestSocketRequest::~TestSocketRequest() {
  }
  
  void TestSocketRequest::OnComplete(int result) {
    SetResult(result);
    (*completion_count_)++;
    request_order_->push_back(this);
  }
  
  // static
  const int ClientSocketPoolTest::kIndexOutOfBounds = -1;
  
  // static
  const int ClientSocketPoolTest::kRequestNotFound = -2;
  
  ClientSocketPoolTest::ClientSocketPoolTest() : completion_count_(0) {}
  ClientSocketPoolTest::~ClientSocketPoolTest() {}
  
  int ClientSocketPoolTest::GetOrderOfRequest(size_t index) const {
    index--;
    if (index >= requests_.size())
      return kIndexOutOfBounds;
  
    for (size_t i = 0; i < request_order_.size(); i++)
      if (requests_[index].get() == request_order_[i])
        return i + 1;
  
    return kRequestNotFound;
  }
  
  bool ClientSocketPoolTest::ReleaseOneConnection(KeepAlive keep_alive) {
    for (std::unique_ptr<TestSocketRequest>& it : requests_) {
      if (it->handle()->is_initialized()) {
        if (keep_alive == NO_KEEP_ALIVE)
          it->handle()->socket()->Disconnect();
        it->handle()->Reset();
        base::RunLoop().RunUntilIdle();
        return true;
      }
    }
    return false;
  }
  
  void ClientSocketPoolTest::ReleaseAllConnections(KeepAlive keep_alive) {
    bool released_one;
    do {
      released_one = ReleaseOneConnection(keep_alive);
    } while (released_one);
  }
  
  MockTransportClientSocketPool::MockConnectJob::MockConnectJob(
      std::unique_ptr<StreamSocket> socket,
      ClientSocketHandle* handle,
      const CompletionCallback& callback)
      : socket_(std::move(socket)), handle_(handle), user_callback_(callback) {}
  
  MockTransportClientSocketPool::MockConnectJob::~MockConnectJob() {}
  
  int MockTransportClientSocketPool::MockConnectJob::Connect() {
    int rv = socket_->Connect(base::Bind(&MockConnectJob::OnConnect,
                                         base::Unretained(this)));
    if (rv != ERR_IO_PENDING) {
      user_callback_.Reset();
      OnConnect(rv);
    }
    return rv;
  }
  
  bool MockTransportClientSocketPool::MockConnectJob::CancelHandle(
      const ClientSocketHandle* handle) {
    if (handle != handle_)
      return false;
    socket_.reset();
    handle_ = NULL;
    user_callback_.Reset();
    return true;
  }
  
  void MockTransportClientSocketPool::MockConnectJob::OnConnect(int rv) {
    if (!socket_.get())
      return;
    if (rv == OK) {
      handle_->SetSocket(std::move(socket_));
  
      // Needed for socket pool tests that layer other sockets on top of mock
      // sockets.
      LoadTimingInfo::ConnectTiming connect_timing;
      base::TimeTicks now = base::TimeTicks::Now();
      connect_timing.dns_start = now;
      connect_timing.dns_end = now;
      connect_timing.connect_start = now;
      connect_timing.connect_end = now;
      handle_->set_connect_timing(connect_timing);
    } else {
      socket_.reset();
  
      // Needed to test copying of ConnectionAttempts in SSL ConnectJob.
      ConnectionAttempts attempts;
      attempts.push_back(ConnectionAttempt(IPEndPoint(), rv));
      handle_->set_connection_attempts(attempts);
    }
  
    handle_ = NULL;
  
    if (!user_callback_.is_null()) {
      CompletionCallback callback = user_callback_;
      user_callback_.Reset();
      callback.Run(rv);
    }
  }
  
  MockTransportClientSocketPool::MockTransportClientSocketPool(
      int max_sockets,
      int max_sockets_per_group,
      ClientSocketFactory* socket_factory)
      : TransportClientSocketPool(max_sockets,
                                  max_sockets_per_group,
                                  NULL,
                                  NULL,
                                  NULL,
                                  NULL),
        client_socket_factory_(socket_factory),
        last_request_priority_(DEFAULT_PRIORITY),
        release_count_(0),
        cancel_count_(0) {}
  
  MockTransportClientSocketPool::~MockTransportClientSocketPool() {}
  
  int MockTransportClientSocketPool::RequestSocket(
      const std::string& group_name,
      const void* socket_params,
      RequestPriority priority,
      RespectLimits respect_limits,
      ClientSocketHandle* handle,
      const CompletionCallback& callback,
      const BoundNetLog& net_log) {
    last_request_priority_ = priority;
    std::unique_ptr<StreamSocket> socket =
        client_socket_factory_->CreateTransportClientSocket(
            AddressList(), NULL, net_log.net_log(), NetLog::Source());
    MockConnectJob* job = new MockConnectJob(std::move(socket), handle, callback);
    job_list_.push_back(base::WrapUnique(job));
    handle->set_pool_id(1);
    return job->Connect();
  }
  
  void MockTransportClientSocketPool::CancelRequest(const std::string& group_name,
                                                    ClientSocketHandle* handle) {
    for (std::unique_ptr<MockConnectJob>& it : job_list_) {
      if (it->CancelHandle(handle)) {
        cancel_count_++;
        break;
      }
    }
  }
  
  void MockTransportClientSocketPool::ReleaseSocket(
      const std::string& group_name,
      std::unique_ptr<StreamSocket> socket,
      int id) {
    EXPECT_EQ(1, id);
    release_count_++;
  }
  
  MockSOCKSClientSocketPool::MockSOCKSClientSocketPool(
      int max_sockets,
      int max_sockets_per_group,
      TransportClientSocketPool* transport_pool)
      : SOCKSClientSocketPool(max_sockets,
                              max_sockets_per_group,
                              NULL,
                              transport_pool,
                              NULL,
                              NULL),
        transport_pool_(transport_pool) {}
  
  MockSOCKSClientSocketPool::~MockSOCKSClientSocketPool() {}
  
  int MockSOCKSClientSocketPool::RequestSocket(const std::string& group_name,
                                               const void* socket_params,
                                               RequestPriority priority,
                                               RespectLimits respect_limits,
                                               ClientSocketHandle* handle,
                                               const CompletionCallback& callback,
                                               const BoundNetLog& net_log) {
    return transport_pool_->RequestSocket(group_name, socket_params, priority,
                                          respect_limits, handle, callback,
                                          net_log);
  }
  
  void MockSOCKSClientSocketPool::CancelRequest(
      const std::string& group_name,
      ClientSocketHandle* handle) {
    return transport_pool_->CancelRequest(group_name, handle);
  }
  
  void MockSOCKSClientSocketPool::ReleaseSocket(
      const std::string& group_name,
      std::unique_ptr<StreamSocket> socket,
      int id) {
    return transport_pool_->ReleaseSocket(group_name, std::move(socket), id);
  }
  
  ScopedWebSocketEndpointZeroUnlockDelay::
      ScopedWebSocketEndpointZeroUnlockDelay() {
    old_delay_ =
        WebSocketEndpointLockManager::GetInstance()->SetUnlockDelayForTesting(
            base::TimeDelta());
  }
  
  ScopedWebSocketEndpointZeroUnlockDelay::
      ~ScopedWebSocketEndpointZeroUnlockDelay() {
    base::TimeDelta active_delay =
        WebSocketEndpointLockManager::GetInstance()->SetUnlockDelayForTesting(
            old_delay_);
    EXPECT_EQ(active_delay, base::TimeDelta());
  }
  
  const char kSOCKS5GreetRequest[] = { 0x05, 0x01, 0x00 };
  const int kSOCKS5GreetRequestLength = arraysize(kSOCKS5GreetRequest);
  
  const char kSOCKS5GreetResponse[] = { 0x05, 0x00 };
  const int kSOCKS5GreetResponseLength = arraysize(kSOCKS5GreetResponse);
  
  const char kSOCKS5OkRequest[] =
      { 0x05, 0x01, 0x00, 0x03, 0x04, 'h', 'o', 's', 't', 0x00, 0x50 };
  const int kSOCKS5OkRequestLength = arraysize(kSOCKS5OkRequest);
  
  const char kSOCKS5OkResponse[] =
      { 0x05, 0x00, 0x00, 0x01, 127, 0, 0, 1, 0x00, 0x50 };
  const int kSOCKS5OkResponseLength = arraysize(kSOCKS5OkResponse);
  
  int64_t CountReadBytes(const MockRead reads[], size_t reads_size) {
    int64_t total = 0;
    for (const MockRead* read = reads; read != reads + reads_size; ++read)
      total += read->data_len;
    return total;
  }
  
  int64_t CountWriteBytes(const MockWrite writes[], size_t writes_size) {
    int64_t total = 0;
    for (const MockWrite* write = writes; write != writes + writes_size; ++write)
      total += write->data_len;
    return total;
  }
  
  }  // namespace net
  