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;
+
+  // Recalculate the received entropy hash since we had some missing packets
+  // which the sender won't retransmit again and has sent us the |entropy_hash|
+  // for packets up to, but not including, |sequence_number|.
+  void RecalculateReceivedEntropyHash(
+      QuicPacketSequenceNumber sequence_number,
+      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);
+
+  // Removes not required entries from |received_packets_entropy_| before
+  // |sequence_number|.
+  void ClearReceivedEntropyBefore(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;
+
+  // TODO(satyamshekhar): Can be optimized using an interval set like data
+  // structure.
+  // Set of received sequence numbers that had the received entropy flag set.
+  ReceivedEntropyMap received_packets_entropy_;
+
+  // 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_;
+
+  // Cumulative hash of entropy of all received packets.
+  QuicPacketEntropyHash received_packets_entropy_hash_;
+
+  QuicPacketSequenceNumber largest_received_sequence_number_;
+};
+
+}  // namespace net
+
+#endif  // NET_QUIC_QUIC_PACKET_ENTROPY_MANAGER_H_