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// 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.
// Handles packets for connection_ids in time wait state by discarding the
// packet and sending the clients a public reset packet with exponential
// backoff.
#include <stddef.h>
#include <memory>
#include "base/macros.h"
#include "net/quic/core/quic_blocked_writer_interface.h"
#include "net/quic/core/quic_connection.h"
#include "net/quic/core/quic_framer.h"
#include "net/quic/core/quic_packet_writer.h"
#include "net/quic/core/quic_packets.h"
#include "net/quic/core/quic_session.h"
#include "net/quic/platform/api/quic_containers.h"
#include "net/quic/platform/api/quic_flags.h"
namespace net {
namespace test {
class QuicDispatcherPeer;
class QuicTimeWaitListManagerPeer;
} // namespace test
// Maintains a list of all connection_ids that have been recently closed. A
// connection_id lives in this state for time_wait_period_. All packets received
// for connection_ids in this state are handed over to the
// QuicTimeWaitListManager by the QuicDispatcher. Decides whether to send a
// public reset packet, a copy of the previously sent connection close packet,
// or nothing to the client which sent a packet with the connection_id in time
// wait state. After the connection_id expires its time wait period, a new
// connection/session will be created if a packet is received for this
// connection_id.
class QuicTimeWaitListManager : public QuicBlockedWriterInterface {
class Visitor : public QuicSession::Visitor {
// Called after the given connection is added to the time-wait std::list.
virtual void OnConnectionAddedToTimeWaitList(
QuicConnectionId connection_id) = 0;
// writer - the entity that writes to the socket. (Owned by the dispatcher)
// visitor - the entity that manages blocked writers. (The dispatcher)
// helper - provides a clock (Owned by the dispatcher)
// alarm_factory - used to run clean up alarms. (Owned by the dispatcher)
QuicTimeWaitListManager(QuicPacketWriter* writer,
Visitor* visitor,
QuicConnectionHelperInterface* helper,
QuicAlarmFactory* alarm_factory);
~QuicTimeWaitListManager() override;
// Adds the given connection_id to time wait state for time_wait_period_.
// If |termination_packets| are provided, copies of these packets will be sent
// when a packet with this connection ID is processed. If no termination
// packets are provided, then a PUBLIC_RESET will be sent with the specified
// |version|. Any termination packets will be move from |termination_packets|
// and will become owned by the manager. If |connection_rejected_statelessly|
// is true, it means that the connection was closed due to a stateless reject,
// and termination packets are expected.
virtual void AddConnectionIdToTimeWait(
QuicConnectionId connection_id,
QuicVersion version,
bool connection_rejected_statelessly,
std::vector<std::unique_ptr<QuicEncryptedPacket>>* termination_packets);
// Returns true if the connection_id is in time wait state, false otherwise.
// Packets received for this connection_id should not lead to creation of new
// QuicSessions.
bool IsConnectionIdInTimeWait(QuicConnectionId connection_id) const;
// Called when a packet is received for a connection_id that is in time wait
// state. Sends a public reset packet to the client which sent this
// connection_id. Sending of the public reset packet is throttled by using
// exponential back off. DCHECKs for the connection_id to be in time wait
// state. virtual to override in tests.
virtual void ProcessPacket(const QuicSocketAddress& server_address,
const QuicSocketAddress& client_address,
QuicConnectionId connection_id);
// Called by the dispatcher when the underlying socket becomes writable again,
// since we might need to send pending public reset packets which we didn't
// send because the underlying socket was write blocked.
void OnBlockedWriterCanWrite() override;
// Used to delete connection_id entries that have outlived their time wait
// period.
void CleanUpOldConnectionIds();
// If necessary, trims the oldest connections from the time-wait list until
// the size is under the configured maximum.
void TrimTimeWaitListIfNeeded();
// Given a ConnectionId that exists in the time wait list, returns the
// QuicVersion associated with it.
QuicVersion GetQuicVersionFromConnectionId(QuicConnectionId connection_id);
// The number of connections on the time-wait list.
size_t num_connections() const { return connection_id_map_.size(); }
// Sends a version negotiation packet for |connection_id| announcing support
// for |supported_versions| to |client_address| from |server_address|.
virtual void SendVersionNegotiationPacket(
QuicConnectionId connection_id,
const QuicVersionVector& supported_versions,
const QuicSocketAddress& server_address,
const QuicSocketAddress& client_address);
virtual std::unique_ptr<QuicEncryptedPacket> BuildPublicReset(
const QuicPublicResetPacket& packet);
// Creates a public reset packet and sends it or queues it to be sent later.
virtual void SendPublicReset(const QuicSocketAddress& server_address,
const QuicSocketAddress& client_address,
QuicConnectionId connection_id);
friend class test::QuicDispatcherPeer;
friend class test::QuicTimeWaitListManagerPeer;
// Internal structure to store pending public reset packets.
class QueuedPacket;
// Decides if a packet should be sent for this connection_id based on the
// number of received packets.
bool ShouldSendResponse(int received_packet_count);
// Either sends the packet and deletes it or makes pending_packets_queue_ the
// owner of the packet.
void SendOrQueuePacket(std::unique_ptr<QueuedPacket> packet);
// Sends the packet out. Returns true if the packet was successfully consumed.
// If the writer got blocked and did not buffer the packet, we'll need to keep
// the packet and retry sending. In case of all other errors we drop the
// packet.
bool WriteToWire(QueuedPacket* packet);
// Register the alarm server to wake up at appropriate time.
void SetConnectionIdCleanUpAlarm();
// Removes the oldest connection from the time-wait list if it was added prior
// to "expiration_time". To unconditionally remove the oldest connection, use
// a QuicTime::Delta:Infinity(). This function modifies the
// connection_id_map_. If you plan to call this function in a loop, any
// iterators that you hold before the call to this function may be invalid
// afterward. Returns true if the oldest connection was expired. Returns
// false if the map is empty or the oldest connection has not expired.
bool MaybeExpireOldestConnection(QuicTime expiration_time);
// A map from a recently closed connection_id to the number of packets
// received after the termination of the connection bound to the
// connection_id.
struct ConnectionIdData {
ConnectionIdData(int num_packets_,
QuicVersion version_,
QuicTime time_added_,
bool connection_rejected_statelessly);
ConnectionIdData(const ConnectionIdData& other) = delete;
ConnectionIdData(ConnectionIdData&& other);
int num_packets;
QuicVersion version;
QuicTime time_added;
// These packets may contain CONNECTION_CLOSE frames, or SREJ messages.
std::vector<std::unique_ptr<QuicEncryptedPacket>> termination_packets;
bool connection_rejected_statelessly;
// QuicLinkedHashMap allows lookup by ConnectionId and traversal in add order.
typedef QuicLinkedHashMap<QuicConnectionId, ConnectionIdData> ConnectionIdMap;
ConnectionIdMap connection_id_map_;
// Pending public reset packets that need to be sent out to the client
// when we are given a chance to write by the dispatcher.
QuicDeque<std::unique_ptr<QueuedPacket>> pending_packets_queue_;
// Time period for which connection_ids should remain in time wait state.
const QuicTime::Delta time_wait_period_;
// Alarm to clean up connection_ids that have out lived their duration in
// time wait state.
std::unique_ptr<QuicAlarm> connection_id_clean_up_alarm_;
// Clock to efficiently measure approximate time.
const QuicClock* clock_;
// Interface that writes given buffer to the socket.
QuicPacketWriter* writer_;
// Interface that manages blocked writers.
Visitor* visitor_;
} // namespace net