// Copyright (c) 2017 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/quic/chromium/quic_connectivity_probing_manager.h"

#include "base/metrics/histogram_macros.h"
#include "base/strings/string_number_conversions.h"
#include "base/values.h"
#include "net/log/net_log.h"

namespace net {

namespace {

// Default to 2 seconds timeout as the maximum timeout.
const int64_t kMaxProbingTimeoutMs = 2000;

std::unique_ptr<base::Value> NetLogQuicConnectivityProbingTriggerCallback(
    NetworkChangeNotifier::NetworkHandle network,
    base::TimeDelta initial_timeout,
    NetLogCaptureMode capture_mode) {
  std::unique_ptr<base::DictionaryValue> dict(new base::DictionaryValue());
  dict->SetString("network", base::Int64ToString(network));
  dict->SetString("initial_timeout_ms",
                  base::Int64ToString(initial_timeout.InMilliseconds()));
  return std::move(dict);
}

std::unique_ptr<base::Value> NetLogQuicConnectivityProbingResponseCallback(
    NetworkChangeNotifier::NetworkHandle network,
    IPEndPoint* self_address,
    QuicSocketAddress* peer_address,
    NetLogCaptureMode capture_mode) {
  std::unique_ptr<base::DictionaryValue> dict(new base::DictionaryValue());
  dict->SetString("network", base::Int64ToString(network));
  dict->SetString("self address", self_address->ToString());
  dict->SetString("peer address", peer_address->ToString());
  return std::move(dict);
}

}  // namespace

QuicConnectivityProbingManager::QuicConnectivityProbingManager(
    Delegate* delegate,
    base::SequencedTaskRunner* task_runner)
    : delegate_(delegate),
      network_(NetworkChangeNotifier::kInvalidNetworkHandle),
      retry_count_(0),
      probe_start_time_(base::TimeTicks()),
      task_runner_(task_runner),
      weak_factory_(this) {
  retransmit_timer_.SetTaskRunner(task_runner_);
}

QuicConnectivityProbingManager::~QuicConnectivityProbingManager() {
  CancelProbingIfAny();
}

int QuicConnectivityProbingManager::HandleWriteError(
    int error_code,
    scoped_refptr<QuicChromiumPacketWriter::ReusableIOBuffer> packet) {
  // Write error on the probing network is not recoverable.
  DVLOG(1) << "Probing packet encounters write error";
  // Post a task to notify |delegate_| that this probe failed and cancel
  // undergoing probing, which will delete the packet writer.
  task_runner_->PostTask(
      FROM_HERE,
      base::Bind(&QuicConnectivityProbingManager::NotifyDelegateProbeFailed,
                 weak_factory_.GetWeakPtr()));
  return error_code;
}

void QuicConnectivityProbingManager::OnWriteError(int error_code) {
  // Write error on the probing network.
  NotifyDelegateProbeFailed();
}

void QuicConnectivityProbingManager::OnWriteUnblocked() {}

void QuicConnectivityProbingManager::CancelProbing(
    NetworkChangeNotifier::NetworkHandle network) {
  if (network == network_)
    CancelProbingIfAny();
}

void QuicConnectivityProbingManager::CancelProbingIfAny() {
  if (network_ != NetworkChangeNotifier::kInvalidNetworkHandle) {
    net_log_.AddEvent(
        NetLogEventType::QUIC_CONNECTION_CONNECTIVITY_PROBING_CANCELLED,
        NetLog::Int64Callback("network", network_));
  }
  network_ = NetworkChangeNotifier::kInvalidNetworkHandle;
  peer_address_ = QuicSocketAddress();
  socket_.reset();
  writer_.reset();
  reader_.reset();
  retry_count_ = 0;
  probe_start_time_ = base::TimeTicks();
  initial_timeout_ = base::TimeDelta();
  retransmit_timer_.Stop();
}

void QuicConnectivityProbingManager::StartProbing(
    NetworkChangeNotifier::NetworkHandle network,
    const QuicSocketAddress& peer_address,
    std::unique_ptr<DatagramClientSocket> socket,
    std::unique_ptr<QuicChromiumPacketWriter> writer,
    std::unique_ptr<QuicChromiumPacketReader> reader,
    base::TimeDelta initial_timeout,
    const NetLogWithSource& net_log) {
  DCHECK_NE(network, NetworkChangeNotifier::kInvalidNetworkHandle);
  if (network == network_ &&
      network_ != NetworkChangeNotifier::kInvalidNetworkHandle &&
      peer_address == peer_address_) {
    // |network| is already under probing.
    return;
  }
  // Start a new probe will always cancel the previous one.
  CancelProbingIfAny();

  network_ = network;
  peer_address_ = peer_address;
  socket_ = std::move(socket);
  writer_ = std::move(writer);
  net_log_ = net_log;
  probe_start_time_ = base::TimeTicks::Now();

  // |this| will listen to all socket write events for the probing
  // packet writer.
  writer_->set_delegate(this);
  reader_ = std::move(reader);
  initial_timeout_ = initial_timeout;
  net_log_.AddEvent(
      NetLogEventType::QUIC_CONNECTION_CONNECTIVITY_PROBING_TRIGGERED,
      base::Bind(&NetLogQuicConnectivityProbingTriggerCallback, network_,
                 initial_timeout_));

  reader_->StartReading();
  SendConnectivityProbingPacket(initial_timeout_);
}

void QuicConnectivityProbingManager::OnConnectivityProbingReceived(
    const QuicSocketAddress& self_address,
    const QuicSocketAddress& peer_address) {
  if (!socket_) {
    DVLOG(1) << "Probing response is ignored as probing was cancelled "
             << "or succeeded.";
    return;
  }

  IPEndPoint local_address;
  socket_->GetLocalAddress(&local_address);

  DVLOG(1) << "Current probing is live at self ip:port "
           << local_address.ToString() << ", to peer ip:port "
           << peer_address_.ToString();

  if (QuicSocketAddressImpl(local_address) != self_address.impl() ||
      peer_address_ != peer_address) {
    DVLOG(1) << "Received probing response from peer ip:port "
             << peer_address.ToString() << ", to self ip:port "
             << self_address.ToString() << ". Ignored.";
    return;
  }

  net_log_.AddEvent(
      NetLogEventType::QUIC_CONNECTION_CONNECTIVITY_PROBING_PACKET_RECEIVED,
      base::Bind(&NetLogQuicConnectivityProbingResponseCallback, network_,
                 &local_address, &peer_address_));

  UMA_HISTOGRAM_COUNTS_100("Net.QuicSession.ProbingRetryCountUntilSuccess",
                           retry_count_);

  UMA_HISTOGRAM_TIMES("Net.QuicSession.ProbingTimeInMillisecondsUntilSuccess",
                      base::TimeTicks::Now() - probe_start_time_);

  // Notify the delegate that the probe succeeds and reset everything.
  delegate_->OnProbeNetworkSucceeded(network_, self_address, std::move(socket_),
                                     std::move(writer_), std::move(reader_));
  CancelProbingIfAny();
}

void QuicConnectivityProbingManager::SendConnectivityProbingPacket(
    base::TimeDelta timeout) {
  net_log_.AddEvent(
      NetLogEventType::QUIC_CONNECTION_CONNECTIVITY_PROBING_PACKET_SENT,
      NetLog::Int64Callback("sent_count", retry_count_));
  if (!delegate_->OnSendConnectivityProbingPacket(writer_.get(),
                                                  peer_address_)) {
    NotifyDelegateProbeFailed();
    return;
  }
  retransmit_timer_.Start(
      FROM_HERE, timeout,
      base::Bind(
          &QuicConnectivityProbingManager::MaybeResendConnectivityProbingPacket,
          weak_factory_.GetWeakPtr()));
}

void QuicConnectivityProbingManager::NotifyDelegateProbeFailed() {
  if (network_ != NetworkChangeNotifier::kInvalidNetworkHandle) {
    delegate_->OnProbeNetworkFailed(network_);
    CancelProbingIfAny();
  }
}

void QuicConnectivityProbingManager::MaybeResendConnectivityProbingPacket() {
  // Use exponential backoff for the timeout
  retry_count_++;
  int64_t timeout_ms =
      (UINT64_C(1) << retry_count_) * initial_timeout_.InMilliseconds();
  if (timeout_ms > kMaxProbingTimeoutMs) {
    NotifyDelegateProbeFailed();
    return;
  }
  SendConnectivityProbingPacket(base::TimeDelta::FromMilliseconds(timeout_ms));
}

}  // namespace net