Land Recent QUIC changes.

net/quic/quic_packet_entropy_manager.h

-// 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.
-//
-// Manages the packet entropy calculation for both sent and received packets
-// for a connection.
-
-#ifndef NET_QUIC_QUIC_PACKET_ENTROPY_MANAGER_H_
-#define NET_QUIC_QUIC_PACKET_ENTROPY_MANAGER_H_
-
-#include "net/base/linked_hash_map.h"
-#include "net/quic/quic_framer.h"
-#include "net/quic/quic_protocol.h"
-
-namespace net {
-
-// Records all sent and received packets by a connection to track the cumulative
-// entropy of both sent and received packets separately. It is used by the
-// connection to validate an ack frame sent by the peer as a preventive measure
-// against the optimistic ack attack. Also, called by the framer when it
-// truncates an ack frame to get the correct entropy value for the ack frame
-// being serialized.
-class NET_EXPORT_PRIVATE QuicPacketEntropyManager :
-    public QuicReceivedEntropyHashCalculatorInterface {
- public:
-  QuicPacketEntropyManager();
-  virtual ~QuicPacketEntropyManager();
-
-  // Record the received entropy hash against |sequence_number|.
-  void RecordReceivedPacketEntropyHash(QuicPacketSequenceNumber sequence_number,
-                                       QuicPacketEntropyHash entropy_hash);
-
-  // Record |entropy_hash| for sent packet corresponding to |sequence_number|.
-  void RecordSentPacketEntropyHash(QuicPacketSequenceNumber sequence_number,
-                                   QuicPacketEntropyHash entropy_hash);
-
-  // QuicReceivedEntropyHashCalculatorInterface
-  // Called by QuicFramer, when the outgoing ack gets truncated, to recalculate
-  // the received entropy hash for the truncated ack frame.
-  virtual QuicPacketEntropyHash ReceivedEntropyHash(
-      QuicPacketSequenceNumber sequence_number) const OVERRIDE;
-
-  QuicPacketEntropyHash SentEntropyHash(
-      QuicPacketSequenceNumber sequence_number) const;
-
-  QuicPacketSequenceNumber LargestReceivedSequenceNumber() const;
-
-  // Recalculate the received entropy hash and clears old packet entropies,
-  // now that the sender sent us the |entropy_hash| for packets up to,
-  // but not including, |peer_least_unacked|.
-  void RecalculateReceivedEntropyHash(
-      QuicPacketSequenceNumber peer_least_unacked,
-      QuicPacketEntropyHash entropy_hash);
-
-  // Returns true if |entropy_hash| matches the expected sent entropy hash
-  // up to |sequence_number| removing sequence numbers from |missing_packets|.
-  bool IsValidEntropy(QuicPacketSequenceNumber sequence_number,
-                      const SequenceNumberSet& missing_packets,
-                      QuicPacketEntropyHash entropy_hash) const;
-
-  // Removes not required entries from |sent_packets_entropy_| before
-  // |sequence_number|.
-  void ClearSentEntropyBefore(QuicPacketSequenceNumber sequence_number);
-
-  QuicPacketEntropyHash sent_packets_entropy_hash() const {
-    return sent_packets_entropy_hash_;
-  }
-
-  QuicPacketEntropyHash received_packets_entropy_hash() const {
-    return received_packets_entropy_hash_;
-  }
-
- private:
-  typedef linked_hash_map<QuicPacketSequenceNumber,
-                          std::pair<QuicPacketEntropyHash,
-                               QuicPacketEntropyHash> > SentEntropyMap;
-  typedef std::map<QuicPacketSequenceNumber,
-                   QuicPacketEntropyHash> ReceivedEntropyMap;
-
-  // Linked hash map from sequence numbers to the sent entropy hash up to the
-  // sequence number in the key.
-  SentEntropyMap sent_packets_entropy_;
-
-  // Cumulative hash of entropy of all sent packets.
-  QuicPacketEntropyHash sent_packets_entropy_hash_;
-
-  // TODO(satyamshekhar): Can be optimized using an interval set like data
-  // structure.
-  // Map of received sequence numbers to their corresponding entropy.
-  // Every received packet has an entry, and packets without the entropy bit set
-  // have an entropy value of 0.
-  // TODO(ianswett): When the entropy flag is off, the entropy should not be 0.
-  ReceivedEntropyMap received_packets_entropy_;
-
-  // Cumulative hash of entropy of all received packets.
-  QuicPacketEntropyHash received_packets_entropy_hash_;
-
-  // The largest sequence number cleared by RecalculateReceivedEntropyHash.
-  // Received entropy cannot be calculated for numbers less than it.
-  QuicPacketSequenceNumber largest_received_sequence_number_;
-};
-
-}  // namespace net
-
-#endif  // NET_QUIC_QUIC_PACKET_ENTROPY_MANAGER_H_