1 // Copyright (c) 2012 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 // Responsible for generating packets on behalf of a QuicConnection. 6 // Packets are serialized just-in-time. Control frames are queued. 7 // Ack and Feedback frames will be requested from the Connection 8 // just-in-time. When a packet needs to be sent, the Generator 9 // will serialize a packet and pass it to QuicConnection::SendOrQueuePacket() 10 // 11 // The Generator's mode of operation is controlled by two conditions: 12 // 13 // 1) Is the Delegate writable? 14 // 15 // If the Delegate is not writable, then no operations will cause 16 // a packet to be serialized. In particular: 17 // * SetShouldSendAck will simply record that an ack is to be sent. 18 // * AddControlFrame will enqueue the control frame. 19 // * ConsumeData will do nothing. 20 // 21 // If the Delegate is writable, then the behavior depends on the second 22 // condition: 23 // 24 // 2) Is the Generator in batch mode? 25 // 26 // If the Generator is NOT in batch mode, then each call to a write 27 // operation will serialize one or more packets. The contents will 28 // include any previous queued frames. If an ack should be sent 29 // but has not been sent, then the Delegate will be asked to create 30 // an Ack frame which will then be included in the packet. When 31 // the write call completes, the current packet will be serialized 32 // and sent to the Delegate, even if it is not full. 33 // 34 // If the Generator is in batch mode, then each write operation will 35 // add data to the "current" packet. When the current packet becomes 36 // full, it will be serialized and sent to the packet. When batch 37 // mode is ended via |FinishBatchOperations|, the current packet 38 // will be serialzied, even if it is not full. 39 // 40 // FEC behavior also depends on batch mode. In batch mode, FEC packets 41 // will be sent after |max_packets_per_group| have been sent, as well 42 // as after batch operations are complete. When not in batch mode, 43 // an FEC packet will be sent after each write call completes. 44 // 45 // TODO(rch): This behavior should probably be tuned. When not in batch 46 // mode, we should probably set a timer so that several independent 47 // operations can be grouped into the same FEC group. 48 // 49 // When an FEC packet is generated, it will be send to the Delegate, 50 // even if the Delegate has become unwritable after handling the 51 // data packet immediately proceeding the FEC packet. 52 53 #ifndef NET_QUIC_QUIC_PACKET_GENERATOR_H_ 54 #define NET_QUIC_QUIC_PACKET_GENERATOR_H_ 55 56 #include "net/quic/quic_packet_creator.h" 57 #include "net/quic/quic_sent_packet_manager.h" 58 #include "net/quic/quic_types.h" 59 60 namespace net { 61 62 namespace test { 63 class QuicPacketGeneratorPeer; 64 } // namespace test 65 66 class QuicAckNotifier; 67 68 class NET_EXPORT_PRIVATE QuicPacketGenerator { 69 public: 70 class NET_EXPORT_PRIVATE DelegateInterface { 71 public: 72 virtual ~DelegateInterface() {} 73 virtual bool ShouldGeneratePacket(TransmissionType transmission_type, 74 HasRetransmittableData retransmittable, 75 IsHandshake handshake) = 0; 76 virtual QuicAckFrame* CreateAckFrame() = 0; 77 virtual QuicCongestionFeedbackFrame* CreateFeedbackFrame() = 0; 78 virtual QuicStopWaitingFrame* CreateStopWaitingFrame() = 0; 79 // Takes ownership of |packet.packet| and |packet.retransmittable_frames|. 80 virtual void OnSerializedPacket(const SerializedPacket& packet) = 0; 81 virtual void CloseConnection(QuicErrorCode error, bool from_peer) = 0; 82 }; 83 84 // Interface which gets callbacks from the QuicPacketGenerator at interesting 85 // points. Implementations must not mutate the state of the generator 86 // as a result of these callbacks. 87 class NET_EXPORT_PRIVATE DebugDelegate { 88 public: 89 virtual ~DebugDelegate() {} 90 91 // Called when a frame has been added to the current packet. 92 virtual void OnFrameAddedToPacket(const QuicFrame& frame) {} 93 }; 94 95 QuicPacketGenerator(QuicConnectionId connection_id, 96 QuicFramer* framer, 97 QuicRandom* random_generator, 98 DelegateInterface* delegate); 99 100 virtual ~QuicPacketGenerator(); 101 102 // Called by the connection in the event of the congestion window changing. 103 void OnCongestionWindowChange(QuicByteCount congestion_window); 104 105 // Indicates that an ACK frame should be sent. If |also_send_feedback| is 106 // true, then it also indicates a CONGESTION_FEEDBACK frame should be sent. 107 // If |also_send_stop_waiting| is true, then it also indicates that a 108 // STOP_WAITING frame should be sent as well. 109 // The contents of the frame(s) will be generated via a call to the delegates 110 // CreateAckFrame() and CreateFeedbackFrame() when the packet is serialized. 111 void SetShouldSendAck(bool also_send_feedback, 112 bool also_send_stop_waiting); 113 114 // Indicates that a STOP_WAITING frame should be sent. 115 void SetShouldSendStopWaiting(); 116 117 void AddControlFrame(const QuicFrame& frame); 118 119 // Given some data, may consume part or all of it and pass it to the 120 // packet creator to be serialized into packets. If not in batch 121 // mode, these packets will also be sent during this call. Also 122 // attaches a QuicAckNotifier to any created stream frames, which 123 // will be called once the frame is ACKed by the peer. The 124 // QuicAckNotifier is owned by the QuicConnection. |notifier| may 125 // be NULL. 126 QuicConsumedData ConsumeData(QuicStreamId id, 127 const IOVector& data, 128 QuicStreamOffset offset, 129 bool fin, 130 FecProtection fec_protection, 131 QuicAckNotifier* notifier); 132 133 // Indicates whether batch mode is currently enabled. 134 bool InBatchMode(); 135 // Disables flushing. 136 void StartBatchOperations(); 137 // Enables flushing and flushes queued data which can be sent. 138 void FinishBatchOperations(); 139 140 // Flushes all queued frames, even frames which are not sendable. 141 void FlushAllQueuedFrames(); 142 143 bool HasQueuedFrames() const; 144 145 // Makes the framer not serialize the protocol version in sent packets. 146 void StopSendingVersion(); 147 148 // Creates a version negotiation packet which supports |supported_versions|. 149 // Caller owns the created packet. Also, sets the entropy hash of the 150 // serialized packet to a random bool and returns that value as a member of 151 // SerializedPacket. 152 QuicEncryptedPacket* SerializeVersionNegotiationPacket( 153 const QuicVersionVector& supported_versions); 154 155 156 // Re-serializes frames with the original packet's sequence number length. 157 // Used for retransmitting packets to ensure they aren't too long. 158 // Caller must ensure that any open FEC group is closed before calling this 159 // method. 160 SerializedPacket ReserializeAllFrames( 161 const QuicFrames& frames, 162 QuicSequenceNumberLength original_length); 163 164 // Update the sequence number length to use in future packets as soon as it 165 // can be safely changed. 166 void UpdateSequenceNumberLength( 167 QuicPacketSequenceNumber least_packet_awaited_by_peer, 168 QuicByteCount congestion_window); 169 170 // Sets the encryption level that will be applied to new packets. 171 void set_encryption_level(EncryptionLevel level); 172 173 // Sequence number of the last created packet, or 0 if no packets have been 174 // created. 175 QuicPacketSequenceNumber sequence_number() const; 176 177 size_t max_packet_length() const; 178 179 void set_max_packet_length(size_t length); 180 181 void set_debug_delegate(DebugDelegate* debug_delegate) { 182 debug_delegate_ = debug_delegate; 183 } 184 185 private: 186 friend class test::QuicPacketGeneratorPeer; 187 188 // Turn on FEC protection for subsequent packets in the generator. 189 // If no FEC group is currently open in the creator, this method flushes any 190 // queued frames in the generator and in the creator, and it then turns FEC on 191 // in the creator. This method may be called with an open FEC group in the 192 // creator, in which case, only the generator's state is altered. 193 void MaybeStartFecProtection(); 194 195 // Serializes and calls the delegate on an FEC packet if one was under 196 // construction in the creator. When |force| is false, it relies on the 197 // creator being ready to send an FEC packet, otherwise FEC packet is sent 198 // as long as one is under construction in the creator. Also tries to turn 199 // off FEC protection in the creator if it's off in the generator. 200 void MaybeSendFecPacketAndCloseGroup(bool force); 201 202 void SendQueuedFrames(bool flush); 203 204 // Test to see if we have pending ack, feedback, or control frames. 205 bool HasPendingFrames() const; 206 // Test to see if the addition of a pending frame (which might be 207 // retransmittable) would still allow the resulting packet to be sent now. 208 bool CanSendWithNextPendingFrameAddition() const; 209 // Add exactly one pending frame, preferring ack over feedback over control 210 // frames. 211 bool AddNextPendingFrame(); 212 213 bool AddFrame(const QuicFrame& frame); 214 215 void SerializeAndSendPacket(); 216 217 DelegateInterface* delegate_; 218 DebugDelegate* debug_delegate_; 219 220 QuicPacketCreator packet_creator_; 221 QuicFrames queued_control_frames_; 222 223 // True if batch mode is currently enabled. 224 bool batch_mode_; 225 226 // True if FEC protection is on. The creator may have an open FEC group even 227 // if this variable is false. 228 bool should_fec_protect_; 229 230 // Flags to indicate the need for just-in-time construction of a frame. 231 bool should_send_ack_; 232 bool should_send_feedback_; 233 bool should_send_stop_waiting_; 234 // If we put a non-retransmittable frame (namley ack or feedback frame) in 235 // this packet, then we have to hold a reference to it until we flush (and 236 // serialize it). Retransmittable frames are referenced elsewhere so that they 237 // can later be (optionally) retransmitted. 238 scoped_ptr<QuicAckFrame> pending_ack_frame_; 239 scoped_ptr<QuicCongestionFeedbackFrame> pending_feedback_frame_; 240 scoped_ptr<QuicStopWaitingFrame> pending_stop_waiting_frame_; 241 242 DISALLOW_COPY_AND_ASSIGN(QuicPacketGenerator); 243 }; 244 245 } // namespace net 246 247 #endif // NET_QUIC_QUIC_PACKET_GENERATOR_H_ 248