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// 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.
// Responsible for generating packets on behalf of a QuicConnection.
// Packets are serialized just-in-time. Control frames are queued.
// Ack and Feedback frames will be requested from the Connection
// just-in-time. When a packet needs to be sent, the Generator
// will serialize a packet and pass it to QuicConnection::SendOrQueuePacket()
// The Generator's mode of operation is controlled by two conditions:
// 1) Is the Delegate writable?
// If the Delegate is not writable, then no operations will cause
// a packet to be serialized. In particular:
// * SetShouldSendAck will simply record that an ack is to be sent.
// * AddControlFrame will enqueue the control frame.
// * ConsumeData will do nothing.
// If the Delegate is writable, then the behavior depends on the second
// condition:
// 2) Is the Generator in batch mode?
// If the Generator is NOT in batch mode, then each call to a write
// operation will serialize one or more packets. The contents will
// include any previous queued frames. If an ack should be sent
// but has not been sent, then the Delegate will be asked to create
// an Ack frame which will then be included in the packet. When
// the write call completes, the current packet will be serialized
// and sent to the Delegate, even if it is not full.
// If the Generator is in batch mode, then each write operation will
// add data to the "current" packet. When the current packet becomes
// full, it will be serialized and sent to the packet. When batch
// mode is ended via |FinishBatchOperations|, the current packet
// will be serialzied, even if it is not full.
// FEC behavior also depends on batch mode. In batch mode, FEC packets
// will be sent after |max_packets_per_group| have been sent, as well
// as after batch operations are complete. When not in batch mode,
// an FEC packet will be sent after each write call completes.
// TODO(rch): This behavior should probably be tuned. When not in batch
// mode, we should probably set a timer so that several independent
// operations can be grouped into the same FEC group.
// When an FEC packet is generated, it will be send to the Delegate,
// even if the Delegate has become unwritable after handling the
// data packet immediately proceeding the FEC packet.
#include "net/quic/quic_packet_creator.h"
#include "net/quic/quic_sent_packet_manager.h"
#include "net/quic/quic_types.h"
namespace net {
namespace test {
class QuicPacketGeneratorPeer;
} // namespace test
class QuicAckNotifier;
class NET_EXPORT_PRIVATE QuicPacketGenerator {
class NET_EXPORT_PRIVATE DelegateInterface {
virtual ~DelegateInterface() {}
virtual bool ShouldGeneratePacket(TransmissionType transmission_type,
HasRetransmittableData retransmittable,
IsHandshake handshake) = 0;
virtual QuicAckFrame* CreateAckFrame() = 0;
virtual QuicCongestionFeedbackFrame* CreateFeedbackFrame() = 0;
virtual QuicStopWaitingFrame* CreateStopWaitingFrame() = 0;
// Takes ownership of |packet.packet| and |packet.retransmittable_frames|.
virtual void OnSerializedPacket(const SerializedPacket& packet) = 0;
virtual void CloseConnection(QuicErrorCode error, bool from_peer) = 0;
// Interface which gets callbacks from the QuicPacketGenerator at interesting
// points. Implementations must not mutate the state of the generator
// as a result of these callbacks.
class NET_EXPORT_PRIVATE DebugDelegate {
virtual ~DebugDelegate() {}
// Called when a frame has been added to the current packet.
virtual void OnFrameAddedToPacket(const QuicFrame& frame) {}
QuicPacketGenerator(QuicConnectionId connection_id,
QuicFramer* framer,
QuicRandom* random_generator,
DelegateInterface* delegate);
virtual ~QuicPacketGenerator();
// Called by the connection in the event of the congestion window changing.
void OnCongestionWindowChange(QuicByteCount congestion_window);
// Indicates that an ACK frame should be sent. If |also_send_feedback| is
// true, then it also indicates a CONGESTION_FEEDBACK frame should be sent.
// If |also_send_stop_waiting| is true, then it also indicates that a
// STOP_WAITING frame should be sent as well.
// The contents of the frame(s) will be generated via a call to the delegates
// CreateAckFrame() and CreateFeedbackFrame() when the packet is serialized.
void SetShouldSendAck(bool also_send_feedback,
bool also_send_stop_waiting);
// Indicates that a STOP_WAITING frame should be sent.
void SetShouldSendStopWaiting();
void AddControlFrame(const QuicFrame& frame);
// Given some data, may consume part or all of it and pass it to the
// packet creator to be serialized into packets. If not in batch
// mode, these packets will also be sent during this call. Also
// attaches a QuicAckNotifier to any created stream frames, which
// will be called once the frame is ACKed by the peer. The
// QuicAckNotifier is owned by the QuicConnection. |notifier| may
// be NULL.
QuicConsumedData ConsumeData(QuicStreamId id,
const IOVector& data,
QuicStreamOffset offset,
bool fin,
FecProtection fec_protection,
QuicAckNotifier* notifier);
// Indicates whether batch mode is currently enabled.
bool InBatchMode();
// Disables flushing.
void StartBatchOperations();
// Enables flushing and flushes queued data which can be sent.
void FinishBatchOperations();
// Flushes all queued frames, even frames which are not sendable.
void FlushAllQueuedFrames();
bool HasQueuedFrames() const;
// Makes the framer not serialize the protocol version in sent packets.
void StopSendingVersion();
// Creates a version negotiation packet which supports |supported_versions|.
// Caller owns the created packet. Also, sets the entropy hash of the
// serialized packet to a random bool and returns that value as a member of
// SerializedPacket.
QuicEncryptedPacket* SerializeVersionNegotiationPacket(
const QuicVersionVector& supported_versions);
// Re-serializes frames with the original packet's sequence number length.
// Used for retransmitting packets to ensure they aren't too long.
// Caller must ensure that any open FEC group is closed before calling this
// method.
SerializedPacket ReserializeAllFrames(
const QuicFrames& frames,
QuicSequenceNumberLength original_length);
// Update the sequence number length to use in future packets as soon as it
// can be safely changed.
void UpdateSequenceNumberLength(
QuicPacketSequenceNumber least_packet_awaited_by_peer,
QuicByteCount congestion_window);
// Sets the encryption level that will be applied to new packets.
void set_encryption_level(EncryptionLevel level);
// Sequence number of the last created packet, or 0 if no packets have been
// created.
QuicPacketSequenceNumber sequence_number() const;
size_t max_packet_length() const;
void set_max_packet_length(size_t length);
void set_debug_delegate(DebugDelegate* debug_delegate) {
debug_delegate_ = debug_delegate;
friend class test::QuicPacketGeneratorPeer;
// Turn on FEC protection for subsequent packets in the generator.
// If no FEC group is currently open in the creator, this method flushes any
// queued frames in the generator and in the creator, and it then turns FEC on
// in the creator. This method may be called with an open FEC group in the
// creator, in which case, only the generator's state is altered.
void MaybeStartFecProtection();
// Serializes and calls the delegate on an FEC packet if one was under
// construction in the creator. When |force| is false, it relies on the
// creator being ready to send an FEC packet, otherwise FEC packet is sent
// as long as one is under construction in the creator. Also tries to turn
// off FEC protection in the creator if it's off in the generator.
void MaybeSendFecPacketAndCloseGroup(bool force);
void SendQueuedFrames(bool flush);
// Test to see if we have pending ack, feedback, or control frames.
bool HasPendingFrames() const;
// Test to see if the addition of a pending frame (which might be
// retransmittable) would still allow the resulting packet to be sent now.
bool CanSendWithNextPendingFrameAddition() const;
// Add exactly one pending frame, preferring ack over feedback over control
// frames.
bool AddNextPendingFrame();
bool AddFrame(const QuicFrame& frame);
void SerializeAndSendPacket();
DelegateInterface* delegate_;
DebugDelegate* debug_delegate_;
QuicPacketCreator packet_creator_;
QuicFrames queued_control_frames_;
// True if batch mode is currently enabled.
bool batch_mode_;
// True if FEC protection is on. The creator may have an open FEC group even
// if this variable is false.
bool should_fec_protect_;
// Flags to indicate the need for just-in-time construction of a frame.
bool should_send_ack_;
bool should_send_feedback_;
bool should_send_stop_waiting_;
// If we put a non-retransmittable frame (namley ack or feedback frame) in
// this packet, then we have to hold a reference to it until we flush (and
// serialize it). Retransmittable frames are referenced elsewhere so that they
// can later be (optionally) retransmitted.
scoped_ptr<QuicAckFrame> pending_ack_frame_;
scoped_ptr<QuicCongestionFeedbackFrame> pending_feedback_frame_;
scoped_ptr<QuicStopWaitingFrame> pending_stop_waiting_frame_;
} // namespace net