Land Recent QUIC changes.

net/quic/quic_sent_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_SENT_ENTROPY_MANAGER_H_
+#define NET_QUIC_QUIC_SENT_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 packets by a connection to track the cumulative entropy of
+// sent packets.  It is used by the connection to validate an ack
+// frame sent by the peer as a preventive measure against the optimistic ack
+// attack.
+class NET_EXPORT_PRIVATE QuicSentEntropyManager {
+ public:
+  QuicSentEntropyManager();
+  virtual ~QuicSentEntropyManager();
+
+  // Record |entropy_hash| for sent packet corresponding to |sequence_number|.
+  void RecordPacketEntropyHash(QuicPacketSequenceNumber sequence_number,
+                               QuicPacketEntropyHash entropy_hash);
+
+  QuicPacketEntropyHash EntropyHash(
+      QuicPacketSequenceNumber sequence_number) const;
+
+  // 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 |packets_entropy_| before
+  // |sequence_number|.
+  void ClearEntropyBefore(QuicPacketSequenceNumber sequence_number);
+
+  QuicPacketEntropyHash packets_entropy_hash() const {
+    return packets_entropy_hash_;
+  }
+
+ private:
+  typedef linked_hash_map<QuicPacketSequenceNumber,
+                          std::pair<QuicPacketEntropyHash,
+                               QuicPacketEntropyHash> > SentEntropyMap;
+
+  // Linked hash map from sequence numbers to the sent entropy hash up to the
+  // sequence number in the key.
+  SentEntropyMap packets_entropy_;
+
+  // Cumulative hash of entropy of all sent packets.
+  QuicPacketEntropyHash packets_entropy_hash_;
+};
+
+}  // namespace net
+
+#endif  // NET_QUIC_QUIC_SENT_ENTROPY_MANAGER_H_