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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.
#include <stddef.h>
#include <stdint.h>
#include <list>
#include "base/macros.h"
#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 NET_EXPORT_PRIVATE QuicPacketGenerator {
class NET_EXPORT_PRIVATE DelegateInterface
: public QuicPacketCreator::DelegateInterface {
~DelegateInterface() override {}
// Consults delegate whether a packet should be generated.
virtual bool ShouldGeneratePacket(HasRetransmittableData retransmittable,
IsHandshake handshake) = 0;
virtual const QuicFrame GetUpdatedAckFrame() = 0;
virtual void PopulateStopWaitingFrame(
QuicStopWaitingFrame* stop_waiting) = 0;
QuicPacketGenerator(QuicConnectionId connection_id,
QuicFramer* framer,
QuicRandom* random_generator,
QuicBufferAllocator* buffer_allocator,
DelegateInterface* delegate);
// Indicates that an ACK 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 delegate
// CreateAckFrame() when the packet is serialized.
void SetShouldSendAck(bool also_send_stop_waiting);
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.
// |delegate| (if not nullptr) will be informed once all packets sent as a
// result of this call are ACKed by the peer.
QuicConsumedData ConsumeData(QuicStreamId id,
QuicIOVector iov,
QuicStreamOffset offset,
bool fin,
QuicAckListenerInterface* listener);
// Generates an MTU discovery packet of specified size.
void GenerateMtuDiscoveryPacket(QuicByteCount target_mtu,
QuicAckListenerInterface* listener);
// 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;
// Whether the pending packet has no frames in it at the moment.
bool IsPendingPacketEmpty() const;
// Makes the framer not serialize the protocol version in sent packets.
void StopSendingVersion();
// SetDiversificationNonce sets the nonce that will be sent in each public
// header of packets encrypted at the initial encryption level. Should only
// be called by servers.
void SetDiversificationNonce(const DiversificationNonce nonce);
// 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 packet number length.
// Used for retransmitting packets to ensure they aren't too long.
void ReserializeAllFrames(const PendingRetransmission& retransmission,
char* buffer,
size_t buffer_len);
// Update the packet number length to use in future packets as soon as it
// can be safely changed.
void UpdateSequenceNumberLength(QuicPacketNumber least_packet_awaited_by_peer,
QuicPacketCount max_packets_in_flight);
// Set the minimum number of bytes for the connection id length;
void SetConnectionIdLength(uint32_t length);
// Sets the encrypter to use for the encryption level.
void SetEncrypter(EncryptionLevel level, QuicEncrypter* encrypter);
// Sets the encryption level that will be applied to new packets.
void set_encryption_level(EncryptionLevel level);
// packet number of the last created packet, or 0 if no packets have been
// created.
QuicPacketNumber packet_number() const;
// Returns the maximum length a current packet can actually have.
QuicByteCount GetCurrentMaxPacketLength() const;
// Set maximum packet length in the creator immediately. May not be called
// when there are frames queued in the creator.
void SetMaxPacketLength(QuicByteCount length);
// Sets |path_id| to be the path on which next packet is generated.
void SetCurrentPath(QuicPathId path_id,
QuicPacketNumber least_packet_awaited_by_peer,
QuicPacketCount max_packets_in_flight);
void set_debug_delegate(QuicPacketCreator::DebugDelegate* debug_delegate) {
const QuicAckFrame& pending_ack_frame() const { return pending_ack_frame_; }
friend class test::QuicPacketGeneratorPeer;
void SendQueuedFrames(bool flush);
// Test to see if we have pending ack, or control frames.
bool HasPendingFrames() const;
// Returns true if 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 frames over control frames.
// Returns true if a pending frame is successfully added.
// Returns false and flushes current open packet if the pending frame cannot
// fit into current open packet.
bool AddNextPendingFrame();
DelegateInterface* delegate_;
QuicPacketCreator packet_creator_;
QuicFrames queued_control_frames_;
// True if batch mode is currently enabled.
bool batch_mode_;
// Flags to indicate the need for just-in-time construction of a frame.
bool should_send_ack_;
bool should_send_stop_waiting_;
// If we put a non-retransmittable 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.
QuicAckFrame pending_ack_frame_;
QuicStopWaitingFrame pending_stop_waiting_frame_;
} // namespace net