net/quic/quic_time_wait_list_manager.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4 //
   5 // Handles packets for connection_ids in time wait state by discarding the
   6 // packet and sending the clients a public reset packet with exponential
   7 // backoff.
   8
   9 #ifndef NET_QUIC_QUIC_TIME_WAIT_LIST_MANAGER_H_
  10 #define NET_QUIC_QUIC_TIME_WAIT_LIST_MANAGER_H_
  11
  12 #include <deque>
  13
  14 #include "base/basictypes.h"
  15 #include "base/containers/hash_tables.h"
  16 #include "base/strings/string_piece.h"
  17 #include "net/base/linked_hash_map.h"
  18 #include "net/quic/quic_blocked_writer_interface.h"
  19 #include "net/quic/quic_connection_helper.h"
  20 #include "net/quic/quic_framer.h"
  21 #include "net/quic/quic_packet_writer.h"
  22 #include "net/quic/quic_protocol.h"
  23
  24 namespace net {
  25
  26 class ConnectionIdCleanUpAlarm;
  27 class QuicServerSessionVisitor;
  28
  29 namespace test {
  30 class QuicTimeWaitListManagerPeer;
  31 }  // namespace test
  32
  33 // Maintains a list of all connection_ids that have been recently closed. A
  34 // connection_id lives in this state for time_wait_period_. All packets received
  35 // for connection_ids in this state are handed over to the
  36 // QuicTimeWaitListManager by the QuicDispatcher.  Decides whether to send a
  37 // public reset packet, a copy of the previously sent connection close packet,
  38 // or nothing to the client which sent a packet with the connection_id in time
  39 // wait state.  After the connection_id expires its time wait period, a new
  40 // connection/session will be created if a packet is received for this
  41 // connection_id.
  42 class QuicTimeWaitListManager : public QuicBlockedWriterInterface {
  43  public:
  44   // writer - the entity that writes to the socket. (Owned by the dispatcher)
  45   // visitor - the entity that manages blocked writers. (The dispatcher)
  46   // helper - used to run clean up alarms. (Owned by the owner of the server)
  47   QuicTimeWaitListManager(QuicPacketWriter* writer,
  48                           QuicServerSessionVisitor* visitor,
  49                           QuicConnectionHelperInterface* helper,
  50                           const QuicVersionVector& supported_versions);
  51   ~QuicTimeWaitListManager() override;
  52
  53   // Adds the given connection_id to time wait state for time_wait_period_.
  54   // Henceforth, any packet bearing this connection_id should not be processed
  55   // while the connection_id remains in this list. If a non-nullptr
  56   // |close_packet| is provided, the TimeWaitListManager takes ownership of it
  57   // and sends it again when packets are received for added connection_ids. If
  58   // nullptr, a public reset packet is sent with the specified |version|.
  59   // DCHECKs that connection_id is not already on the list. "virtual" to
  60   // override in tests.
  61   virtual void AddConnectionIdToTimeWait(QuicConnectionId connection_id,
  62                                          QuicVersion version,
  63                                          QuicEncryptedPacket* close_packet);
  64
  65   // Returns true if the connection_id is in time wait state, false otherwise.
  66   // Packets received for this connection_id should not lead to creation of new
  67   // QuicSessions.
  68   bool IsConnectionIdInTimeWait(QuicConnectionId connection_id) const;
  69
  70   // Called when a packet is received for a connection_id that is in time wait
  71   // state. Sends a public reset packet to the client which sent this
  72   // connection_id. Sending of the public reset packet is throttled by using
  73   // exponential back off. DCHECKs for the connection_id to be in time wait
  74   // state. virtual to override in tests.
  75   virtual void ProcessPacket(const IPEndPoint& server_address,
  76                              const IPEndPoint& client_address,
  77                              QuicConnectionId connection_id,
  78                              QuicPacketSequenceNumber sequence_number,
  79                              const QuicEncryptedPacket& packet);
  80
  81   // Called by the dispatcher when the underlying socket becomes writable again,
  82   // since we might need to send pending public reset packets which we didn't
  83   // send because the underlying socket was write blocked.
  84   void OnCanWrite() override;
  85
  86   // Used to delete connection_id entries that have outlived their time wait
  87   // period.
  88   void CleanUpOldConnectionIds();
  89
  90   // If necessary, trims the oldest connections from the time-wait list until
  91   // the size is under the configured maximum.
  92   void TrimTimeWaitListIfNeeded();
  93
  94   // Given a ConnectionId that exists in the time wait list, returns the
  95   // QuicVersion associated with it.
  96   QuicVersion GetQuicVersionFromConnectionId(QuicConnectionId connection_id);
  97
  98   // The number of connections on the time-wait list.
  99   size_t num_connections() const { return connection_id_map_.size(); }
 100
 101  protected:
 102   virtual QuicEncryptedPacket* BuildPublicReset(
 103       const QuicPublicResetPacket& packet);
 104
 105  private:
 106   friend class test::QuicTimeWaitListManagerPeer;
 107
 108   // Internal structure to store pending public reset packets.
 109   class QueuedPacket;
 110
 111   // Decides if a packet should be sent for this connection_id based on the
 112   // number of received packets.
 113   bool ShouldSendResponse(int received_packet_count);
 114
 115   // Creates a public reset packet and sends it or queues it to be sent later.
 116   void SendPublicReset(const IPEndPoint& server_address,
 117                        const IPEndPoint& client_address,
 118                        QuicConnectionId connection_id,
 119                        QuicPacketSequenceNumber rejected_sequence_number);
 120
 121   // Either sends the packet and deletes it or makes pending_packets_queue_ the
 122   // owner of the packet.
 123   void SendOrQueuePacket(QueuedPacket* packet);
 124
 125   // Sends the packet out. Returns true if the packet was successfully consumed.
 126   // If the writer got blocked and did not buffer the packet, we'll need to keep
 127   // the packet and retry sending. In case of all other errors we drop the
 128   // packet.
 129   bool WriteToWire(QueuedPacket* packet);
 130
 131   // Register the alarm to wake up at appropriate time.
 132   void SetConnectionIdCleanUpAlarm();
 133
 134   // Removes the oldest connection from the time-wait list if it was added prior
 135   // to "expiration_time".  To unconditionally remove the oldest connection, use
 136   // a QuicTime::Delta:Infinity().  This function modifies the
 137   // connection_id_map_.  If you plan to call this function in a loop, any
 138   // iterators that you hold before the call to this function may be invalid
 139   // afterward.  Returns true if the oldest connection was expired.  Returns
 140   // false if the map is empty or the oldest connection has not expired.
 141   bool MaybeExpireOldestConnection(QuicTime expiration_time);
 142
 143   // A map from a recently closed connection_id to the number of packets
 144   // received after the termination of the connection bound to the
 145   // connection_id.
 146   struct ConnectionIdData {
 147     ConnectionIdData(int num_packets_,
 148                      QuicVersion version_,
 149                      QuicTime time_added_,
 150                      QuicEncryptedPacket* close_packet)
 151         : num_packets(num_packets_),
 152           version(version_),
 153           time_added(time_added_),
 154           close_packet(close_packet) {}
 155     int num_packets;
 156     QuicVersion version;
 157     QuicTime time_added;
 158     QuicEncryptedPacket* close_packet;
 159   };
 160
 161   // linked_hash_map allows lookup by ConnectionId and traversal in add order.
 162   typedef linked_hash_map<QuicConnectionId, ConnectionIdData> ConnectionIdMap;
 163   ConnectionIdMap connection_id_map_;
 164
 165   // Pending public reset packets that need to be sent out to the client
 166   // when we are given a chance to write by the dispatcher.
 167   std::deque<QueuedPacket*> pending_packets_queue_;
 168
 169   // Used to schedule alarms to delete old connection_ids which have been in the
 170   // list for too long.
 171   QuicConnectionHelperInterface* helper_;
 172
 173   // Time period for which connection_ids should remain in time wait state.
 174   const QuicTime::Delta time_wait_period_;
 175
 176   // Alarm registered with the connection helper to clean up connection_ids that
 177   // have out lived their duration in time wait state.
 178   scoped_ptr<QuicAlarm> connection_id_clean_up_alarm_;
 179
 180   // Interface that writes given buffer to the socket.
 181   QuicPacketWriter* writer_;
 182
 183   // Interface that manages blocked writers.
 184   QuicServerSessionVisitor* visitor_;
 185
 186   DISALLOW_COPY_AND_ASSIGN(QuicTimeWaitListManager);
 187 };
 188
 189 }  // namespace net
 190
 191 #endif  // NET_QUIC_QUIC_TIME_WAIT_LIST_MANAGER_H_