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 kTimeWaitPeriod. 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 kTimeWaitPeriod.
  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, it is sent again when packets are received for
  57   // added connection_ids. If nullptr, a public reset packet is sent with the
  58   // specified |version|. DCHECKs that connection_id is not already on the list.
  59   void AddConnectionIdToTimeWait(QuicConnectionId connection_id,
  60                                  QuicVersion version,
  61                                  QuicEncryptedPacket* close_packet);  // Owned.
  62
  63   // Returns true if the connection_id is in time wait state, false otherwise.
  64   // Packets received for this connection_id should not lead to creation of new
  65   // QuicSessions.
  66   bool IsConnectionIdInTimeWait(QuicConnectionId connection_id) const;
  67
  68   // Called when a packet is received for a connection_id that is in time wait
  69   // state. Sends a public reset packet to the client which sent this
  70   // connection_id. Sending of the public reset packet is throttled by using
  71   // exponential back off. DCHECKs for the connection_id to be in time wait
  72   // state. virtual to override in tests.
  73   virtual void ProcessPacket(const IPEndPoint& server_address,
  74                              const IPEndPoint& client_address,
  75                              QuicConnectionId connection_id,
  76                              QuicPacketSequenceNumber sequence_number,
  77                              const QuicEncryptedPacket& packet);
  78
  79   // Called by the dispatcher when the underlying socket becomes writable again,
  80   // since we might need to send pending public reset packets which we didn't
  81   // send because the underlying socket was write blocked.
  82   void OnCanWrite() override;
  83
  84   // Used to delete connection_id entries that have outlived their time wait
  85   // period.
  86   void CleanUpOldConnectionIds();
  87
  88   // Given a ConnectionId that exists in the time wait list, returns the
  89   // QuicVersion associated with it.
  90   QuicVersion GetQuicVersionFromConnectionId(QuicConnectionId connection_id);
  91
  92  protected:
  93   virtual QuicEncryptedPacket* BuildPublicReset(
  94       const QuicPublicResetPacket& packet);
  95
  96  private:
  97   friend class test::QuicTimeWaitListManagerPeer;
  98
  99   // Internal structure to store pending public reset packets.
 100   class QueuedPacket;
 101
 102   // Decides if a packet should be sent for this connection_id based on the
 103   // number of received packets.
 104   bool ShouldSendResponse(int received_packet_count);
 105
 106   // Creates a public reset packet and sends it or queues it to be sent later.
 107   void SendPublicReset(const IPEndPoint& server_address,
 108                        const IPEndPoint& client_address,
 109                        QuicConnectionId connection_id,
 110                        QuicPacketSequenceNumber rejected_sequence_number);
 111
 112   // Either sends the packet and deletes it or makes pending_packets_queue_ the
 113   // owner of the packet.
 114   void SendOrQueuePacket(QueuedPacket* packet);
 115
 116   // Sends the packet out. Returns true if the packet was successfully consumed.
 117   // If the writer got blocked and did not buffer the packet, we'll need to keep
 118   // the packet and retry sending. In case of all other errors we drop the
 119   // packet.
 120   bool WriteToWire(QueuedPacket* packet);
 121
 122   // Register the alarm to wake up at appropriate time.
 123   void SetConnectionIdCleanUpAlarm();
 124
 125   // A map from a recently closed connection_id to the number of packets
 126   // received after the termination of the connection bound to the
 127   // connection_id.
 128   struct ConnectionIdData {
 129     ConnectionIdData(int num_packets_,
 130                      QuicVersion version_,
 131                      QuicTime time_added_,
 132                      QuicEncryptedPacket* close_packet)
 133         : num_packets(num_packets_),
 134           version(version_),
 135           time_added(time_added_),
 136           close_packet(close_packet) {}
 137     int num_packets;
 138     QuicVersion version;
 139     QuicTime time_added;
 140     QuicEncryptedPacket* close_packet;
 141   };
 142
 143   // linked_hash_map allows lookup by ConnectionId and traversal in add order.
 144   typedef linked_hash_map<QuicConnectionId, ConnectionIdData> ConnectionIdMap;
 145   ConnectionIdMap connection_id_map_;
 146
 147   // Pending public reset packets that need to be sent out to the client
 148   // when we are given a chance to write by the dispatcher.
 149   std::deque<QueuedPacket*> pending_packets_queue_;
 150
 151   // Used to schedule alarms to delete old connection_ids which have been in the
 152   // list for too long.
 153   QuicConnectionHelperInterface* helper_;
 154
 155   // Time period for which connection_ids should remain in time wait state.
 156   const QuicTime::Delta kTimeWaitPeriod_;
 157
 158   // Alarm registered with the connection helper to clean up connection_ids that
 159   // have
 160   // out lived their duration in time wait state.
 161   scoped_ptr<QuicAlarm> connection_id_clean_up_alarm_;
 162
 163   // Interface that writes given buffer to the socket.
 164   QuicPacketWriter* writer_;
 165
 166   // Interface that manages blocked writers.
 167   QuicServerSessionVisitor* visitor_;
 168
 169   DISALLOW_COPY_AND_ASSIGN(QuicTimeWaitListManager);
 170 };
 171
 172 }  // namespace net
 173
 174 #endif  // NET_QUIC_QUIC_TIME_WAIT_LIST_MANAGER_H_