Let QUIC be able to add random padding of [1,256] bytes after fin is consumed for a stream. Random …

net/quic/core/quic_packet_generator.h

 // 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()
 //
@@ skipping 55 matching lines @@
     // 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);
 
   ~QuicPacketGenerator();
 
   // 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.
+  // When |state| is FIN_AND_PADDING, random padding of size [1, 256] will be
+  // added after stream frames. If current constructed packet cannot
+  // accommodate, the padding will overflow to the next packet(s).
   QuicConsumedData ConsumeData(
       QuicStreamId id,
       QuicIOVector iov,
       QuicStreamOffset offset,
-      bool fin,
+      StreamSendingState state,
       QuicReferenceCountedPointer<QuicAckListenerInterface> ack_listener);
 
   // Sends as many data only packets as allowed by the send algorithm and the
   // available iov.
   // This path does not support FEC, padding, or bundling pending frames.
   QuicConsumedData ConsumeDataFastPath(
       QuicStreamId id,
       const QuicIOVector& iov,
       QuicStreamOffset offset,
       bool fin,
@@ skipping 79 matching lines @@
   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();
 
+  // Adds a random amount of padding (between 1 to 256 bytes).
+  void AddRandomPadding();
+
+  // Sends remaining pending padding.
+  // Pending paddings should only be sent when there is nothing else to send.
+  void SendRemainingPendingPadding();
+
   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.
   QuicStopWaitingFrame pending_stop_waiting_frame_;
 
+  QuicRandom* random_generator_;
+
   DISALLOW_COPY_AND_ASSIGN(QuicPacketGenerator);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_CORE_QUIC_PACKET_GENERATOR_H_