// 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 "quic/core/quic_connection_id_manager.h"
#include <cstdio>

#include "quic/core/quic_clock.h"
#include "quic/core/quic_connection_id.h"
#include "quic/core/quic_error_codes.h"
#include "quic/platform/api/quic_uint128.h"

namespace quic {

QuicConnectionIdData::QuicConnectionIdData(
    const QuicConnectionId& connection_id,
    uint64_t sequence_number,
    QuicUint128 stateless_reset_token)
    : connection_id(connection_id),
      sequence_number(sequence_number),
      stateless_reset_token(stateless_reset_token) {}

namespace {

class RetirePeerIssuedConnectionIdAlarm : public QuicAlarm::Delegate {
 public:
  explicit RetirePeerIssuedConnectionIdAlarm(
      QuicConnectionIdManagerVisitorInterface* visitor)
      : visitor_(visitor) {}
  RetirePeerIssuedConnectionIdAlarm(const RetirePeerIssuedConnectionIdAlarm&) =
      delete;
  RetirePeerIssuedConnectionIdAlarm& operator=(
      const RetirePeerIssuedConnectionIdAlarm&) = delete;

  void OnAlarm() override { visitor_->OnPeerIssuedConnectionIdRetired(); }

 private:
  QuicConnectionIdManagerVisitorInterface* visitor_;
};

std::vector<QuicConnectionIdData>::const_iterator FindConnectionIdData(
    const std::vector<QuicConnectionIdData>& cid_data_vector,
    const QuicConnectionId& cid) {
  return std::find_if(cid_data_vector.begin(), cid_data_vector.end(),
                      [&cid](const QuicConnectionIdData& cid_data) {
                        return cid == cid_data.connection_id;
                      });
}

}  // namespace

QuicPeerIssuedConnectionIdManager::QuicPeerIssuedConnectionIdManager(
    size_t active_connection_id_limit,
    const QuicConnectionId& initial_peer_issued_connection_id,
    const QuicClock* clock,
    QuicAlarmFactory* alarm_factory,
    QuicConnectionIdManagerVisitorInterface* visitor)
    : active_connection_id_limit_(active_connection_id_limit),
      clock_(clock),
      retire_connection_id_alarm_(alarm_factory->CreateAlarm(
          new RetirePeerIssuedConnectionIdAlarm(visitor))) {
  DCHECK(!initial_peer_issued_connection_id.IsEmpty());
  active_connection_id_data_.emplace_back(initial_peer_issued_connection_id,
                                          /*sequence_number=*/0u,
                                          QuicUint128());
  recent_new_connection_id_sequence_numbers_.Add(0u, 1u);
}

QuicPeerIssuedConnectionIdManager::~QuicPeerIssuedConnectionIdManager() {
  retire_connection_id_alarm_->Cancel();
}

bool QuicPeerIssuedConnectionIdManager::IsConnectionIdNew(
    const QuicNewConnectionIdFrame& frame) {
  auto is_old_connection_id = [&frame](const QuicConnectionIdData& cid_data) {
    return cid_data.connection_id == frame.connection_id;
  };
  if (std::any_of(active_connection_id_data_.begin(),
                  active_connection_id_data_.end(), is_old_connection_id)) {
    return false;
  }
  if (std::any_of(unused_connection_id_data_.begin(),
                  unused_connection_id_data_.end(), is_old_connection_id)) {
    return false;
  }
  if (std::any_of(to_be_retired_connection_id_data_.begin(),
                  to_be_retired_connection_id_data_.end(),
                  is_old_connection_id)) {
    return false;
  }
  return true;
}

void QuicPeerIssuedConnectionIdManager::PrepareToRetireConnectionIdPriorTo(
    uint64_t retire_prior_to,
    std::vector<QuicConnectionIdData>* cid_data_vector) {
  auto it2 = cid_data_vector->begin();
  for (auto it = cid_data_vector->begin(); it != cid_data_vector->end(); ++it) {
    if (it->sequence_number >= retire_prior_to) {
      *it2++ = *it;
    } else {
      to_be_retired_connection_id_data_.push_back(*it);
      if (!retire_connection_id_alarm_->IsSet()) {
        retire_connection_id_alarm_->Set(clock_->ApproximateNow());
      }
    }
  }
  cid_data_vector->erase(it2, cid_data_vector->end());
}

QuicErrorCode QuicPeerIssuedConnectionIdManager::OnNewConnectionIdFrame(
    const QuicNewConnectionIdFrame& frame,
    std::string* error_detail) {
  if (recent_new_connection_id_sequence_numbers_.Contains(
          frame.sequence_number)) {
    // This frame has a recently seen sequence number. Ignore.
    return QUIC_NO_ERROR;
  }
  if (!IsConnectionIdNew(frame)) {
    *error_detail =
        "Received a NEW_CONNECTION_ID frame that reuses a previously seen Id.";
    return IETF_QUIC_PROTOCOL_VIOLATION;
  }

  recent_new_connection_id_sequence_numbers_.AddOptimizedForAppend(
      frame.sequence_number, frame.sequence_number + 1);

  if (recent_new_connection_id_sequence_numbers_.Size() >
      kMaxNumConnectionIdSequenceNumberIntervals) {
    *error_detail =
        "Too many disjoint connection Id sequence number intervals.";
    return IETF_QUIC_PROTOCOL_VIOLATION;
  }

  // QuicFramer::ProcessNewConnectionIdFrame guarantees that
  // frame.sequence_number >= frame.retire_prior_to, and hence there is no need
  // to check that.
  if (frame.sequence_number < max_new_connection_id_frame_retire_prior_to_) {
    // Later frames have asked for retirement of the current frame.
    to_be_retired_connection_id_data_.emplace_back(frame.connection_id,
                                                   frame.sequence_number,
                                                   frame.stateless_reset_token);
    if (!retire_connection_id_alarm_->IsSet()) {
      retire_connection_id_alarm_->Set(clock_->ApproximateNow());
    }
    return QUIC_NO_ERROR;
  }
  if (frame.retire_prior_to > max_new_connection_id_frame_retire_prior_to_) {
    max_new_connection_id_frame_retire_prior_to_ = frame.retire_prior_to;
    PrepareToRetireConnectionIdPriorTo(frame.retire_prior_to,
                                       &active_connection_id_data_);
    PrepareToRetireConnectionIdPriorTo(frame.retire_prior_to,
                                       &unused_connection_id_data_);
  }

  if (active_connection_id_data_.size() + unused_connection_id_data_.size() >=
      active_connection_id_limit_) {
    *error_detail = "Peer provides more connection IDs than the limit.";
    return QUIC_CONNECTION_ID_LIMIT_ERROR;
  }

  unused_connection_id_data_.emplace_back(
      frame.connection_id, frame.sequence_number, frame.stateless_reset_token);
  return QUIC_NO_ERROR;
}

const QuicConnectionIdData*
QuicPeerIssuedConnectionIdManager::ConsumeOneUnusedConnectionId() {
  if (unused_connection_id_data_.empty()) {
    return nullptr;
  }
  active_connection_id_data_.push_back(unused_connection_id_data_.back());
  unused_connection_id_data_.pop_back();
  return &active_connection_id_data_.back();
}

void QuicPeerIssuedConnectionIdManager::PrepareToRetireActiveConnectionId(
    const QuicConnectionId& cid) {
  auto it = FindConnectionIdData(active_connection_id_data_, cid);
  if (it == active_connection_id_data_.end()) {
    // The cid has already been retired.
    return;
  }
  to_be_retired_connection_id_data_.push_back(*it);
  active_connection_id_data_.erase(it);
  if (!retire_connection_id_alarm_->IsSet()) {
    retire_connection_id_alarm_->Set(clock_->ApproximateNow());
  }
}

bool QuicPeerIssuedConnectionIdManager::IsConnectionIdActive(
    const QuicConnectionId& cid) const {
  return FindConnectionIdData(active_connection_id_data_, cid) !=
         active_connection_id_data_.end();
}

std::vector<uint64_t> QuicPeerIssuedConnectionIdManager::
    ConsumeToBeRetiredConnectionIdSequenceNumbers() {
  std::vector<uint64_t> result;
  for (auto const& cid_data : to_be_retired_connection_id_data_) {
    result.push_back(cid_data.sequence_number);
  }
  to_be_retired_connection_id_data_.clear();
  return result;
}

}  // namespace quic