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// Copyright 2013 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.
// Manages the packet entropy calculation for both sent and received packets
// for a connection.
#include <stddef.h>
#include <deque>
#include "base/macros.h"
#include "net/quic/quic_config.h"
#include "net/quic/quic_framer.h"
#include "net/quic/quic_protocol.h"
namespace net {
namespace test {
class EntropyTrackerPeer;
class QuicConnectionPeer;
class QuicReceivedPacketManagerPeer;
} // namespace test
struct QuicConnectionStats;
// Records all received packets by a connection and tracks their entropy.
// Also calculates the correct entropy for the framer when it truncates an ack
// frame being serialized.
class NET_EXPORT_PRIVATE QuicReceivedPacketManager
: public QuicReceivedEntropyHashCalculatorInterface {
class NET_EXPORT_PRIVATE EntropyTracker {
// Compute the XOR of the entropy of all received packets up to
// and including packet_number.
// Requires that either:
// packet_number == largest_observed_
// or:
// packet_number > first_gap_ &&
// packet_number < largest_observed_ &&
// packet_number in packets_entropy_
QuicPacketEntropyHash EntropyHash(QuicPacketNumber packet_number) const;
// Record the received entropy hash against |packet_number|.
// Performs garbage collection to advance first_gap_ if
// packet_number == first_gap_.
void RecordPacketEntropyHash(QuicPacketNumber packet_number,
QuicPacketEntropyHash entropy_hash);
// Sets the entropy hash up to but not including a packet number based
// on the hash provided by a StopWaiting frame. Clears older packet
// entropy entries and performs garbage collection up to the first gap.
void SetCumulativeEntropyUpTo(QuicPacketNumber packet_number,
QuicPacketEntropyHash entropy_hash);
size_t size() const { return packets_entropy_.size(); }
friend class test::EntropyTrackerPeer;
// A deque indexed by packet number storing the packet's hash and whether
// a hash was recorded for that packet number.
typedef std::deque<std::pair<QuicPacketEntropyHash, bool>>
// Recomputes first_gap_ and removes packets_entropy_ entries that are no
// longer needed to compute EntropyHash.
void AdvanceFirstGapAndGarbageCollectEntropyMap();
// Map of received packet numbers to their corresponding entropy.
// Stores an entry for every received packet whose packet_number is larger
// than first_gap_. Packets without the entropy bit set have an entropy
// value of 0.
ReceivedEntropyHashes packets_entropy_;
// Cumulative hash of entropy of all received packets.
QuicPacketEntropyHash packets_entropy_hash_;
// packet number of the first packet that we do not know the entropy of.
// If there are no gaps in the received packet sequence,
// packets_entropy_ will be empty and first_gap_ will be equal to
// 'largest_observed_ + 1' since that's the first packet for which
// entropy is unknown. If there are gaps, packets_entropy_ will
// contain entries for all received packets with packet_number >
// first_gap_.
QuicPacketNumber first_gap_;
// packet number of the largest observed packet.
QuicPacketNumber largest_observed_;
explicit QuicReceivedPacketManager(QuicConnectionStats* stats);
~QuicReceivedPacketManager() override;
// Updates the internal state concerning which packets have been received.
// bytes: the packet size in bytes including Quic Headers.
// header: the packet header.
// timestamp: the arrival time of the packet.
virtual void RecordPacketReceived(QuicByteCount bytes,
const QuicPacketHeader& header,
QuicTime receipt_time);
// Checks whether |packet_number| is missing and less than largest observed.
virtual bool IsMissing(QuicPacketNumber packet_number);
// Checks if we're still waiting for the packet with |packet_number|.
virtual bool IsAwaitingPacket(QuicPacketNumber packet_number);
// Retrieves a frame containing a QuicAckFrame. The ack frame may not be
// changed outside QuicReceivedPacketManager and must be serialized before
// another packet is received, or it will change.
const QuicFrame GetUpdatedAckFrame(QuicTime approximate_now);
// QuicReceivedEntropyHashCalculatorInterface
// Called by QuicFramer, when the outgoing ack gets truncated, to recalculate
// the received entropy hash for the truncated ack frame.
QuicPacketEntropyHash EntropyHash(
QuicPacketNumber packet_number) const override;
// Updates internal state based on |stop_waiting|.
virtual void UpdatePacketInformationSentByPeer(
const QuicStopWaitingFrame& stop_waiting);
// Returns true if there are any missing packets.
bool HasMissingPackets() const;
// Returns true when there are new missing packets to be reported within 3
// packets of the largest observed.
virtual bool HasNewMissingPackets() const;
// Returns the number of packets being tracked in the EntropyTracker.
size_t NumTrackedPackets() const;
// Sets the mode of packets set of ack_frame_ based on |version|.
void SetVersion(QuicVersion version);
QuicPacketNumber peer_least_packet_awaiting_ack() {
return peer_least_packet_awaiting_ack_;
virtual bool ack_frame_updated() const;
// For logging purposes.
const QuicAckFrame& ack_frame() const { return ack_frame_; }
friend class test::QuicConnectionPeer;
friend class test::QuicReceivedPacketManagerPeer;
// Deletes all missing packets before least unacked. The connection won't
// process any packets with packet number before |least_unacked| that it
// received after this call. Returns true if there were missing packets before
// |least_unacked| unacked, false otherwise.
bool DontWaitForPacketsBefore(QuicPacketNumber least_unacked);
// Tracks entropy hashes of received packets.
EntropyTracker entropy_tracker_;
// Least packet number of the the packet sent by the peer for which it
// hasn't received an ack.
QuicPacketNumber peer_least_packet_awaiting_ack_;
// Received packet information used to produce acks.
QuicAckFrame ack_frame_;
// True if |ack_frame_| has been updated since UpdateReceivedPacketInfo was
// last called.
bool ack_frame_updated_;
// The time we received the largest_observed packet number, or zero if
// no packet numbers have been received since UpdateReceivedPacketInfo.
// Needed for calculating ack_delay_time.
QuicTime time_largest_observed_;
QuicConnectionStats* stats_;
} // namespace net