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_test.cc

 // 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.
 
 #include "net/quic/core/quic_packet_generator.h"
 
 #include <cstdint>
 #include <memory>
 #include <string>
 
 #include "base/macros.h"
 #include "net/quic/core/crypto/crypto_protocol.h"
 #include "net/quic/core/crypto/null_encrypter.h"
 #include "net/quic/core/crypto/quic_decrypter.h"
 #include "net/quic/core/crypto/quic_encrypter.h"
 #include "net/quic/core/quic_simple_buffer_allocator.h"
 #include "net/quic/core/quic_utils.h"
 #include "net/quic/platform/api/quic_socket_address.h"
 #include "net/quic/platform/api/quic_string_piece.h"
+#include "net/quic/test_tools/mock_random.h"
 #include "net/quic/test_tools/quic_packet_creator_peer.h"
 #include "net/quic/test_tools/quic_packet_generator_peer.h"
 #include "net/quic/test_tools/quic_test_utils.h"
 #include "net/quic/test_tools/simple_quic_framer.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using std::string;
 using testing::InSequence;
 using testing::Return;
@@ skipping 48 matching lines @@
 // contains the expected frames.
 struct PacketContents {
   PacketContents()
       : num_ack_frames(0),
         num_connection_close_frames(0),
         num_goaway_frames(0),
         num_rst_stream_frames(0),
         num_stop_waiting_frames(0),
         num_stream_frames(0),
         num_ping_frames(0),
-        num_mtu_discovery_frames(0) {}
+        num_mtu_discovery_frames(0),
+        num_padding_frames(0) {}
 
   size_t num_ack_frames;
   size_t num_connection_close_frames;
   size_t num_goaway_frames;
   size_t num_rst_stream_frames;
   size_t num_stop_waiting_frames;
   size_t num_stream_frames;
   size_t num_ping_frames;
   size_t num_mtu_discovery_frames;
+  size_t num_padding_frames;
 };
 
 }  // namespace
 
 class QuicPacketGeneratorTest : public ::testing::Test {
  public:
   QuicPacketGeneratorTest()
       : framer_(AllSupportedVersions(),
                 QuicTime::Zero(),
                 Perspective::IS_CLIENT),
-        generator_(42, &framer_, &buffer_allocator_, &delegate_),
+        generator_(42,
+                   &framer_,
+                   &random_generator_,
+                   &buffer_allocator_,
+                   &delegate_),
         creator_(QuicPacketGeneratorPeer::GetPacketCreator(&generator_)) {
     creator_->SetEncrypter(ENCRYPTION_FORWARD_SECURE,
                            new NullEncrypter(Perspective::IS_CLIENT));
     creator_->set_encryption_level(ENCRYPTION_FORWARD_SECURE);
   }
 
   ~QuicPacketGeneratorTest() override {
     for (SerializedPacket& packet : packets_) {
       delete[] packet.encrypted_buffer;
       ClearSerializedPacket(&packet);
@@ skipping 19 matching lines @@
   void CheckPacketContains(const PacketContents& contents,
                            size_t packet_index) {
     ASSERT_GT(packets_.size(), packet_index);
     const SerializedPacket& packet = packets_[packet_index];
     size_t num_retransmittable_frames =
         contents.num_connection_close_frames + contents.num_goaway_frames +
         contents.num_rst_stream_frames + contents.num_stream_frames +
         contents.num_ping_frames;
     size_t num_frames =
         contents.num_ack_frames + contents.num_stop_waiting_frames +
-        contents.num_mtu_discovery_frames + num_retransmittable_frames;
+        contents.num_mtu_discovery_frames + contents.num_padding_frames +
+        num_retransmittable_frames;
 
     if (num_retransmittable_frames == 0) {
       ASSERT_TRUE(packet.retransmittable_frames.empty());
     } else {
       ASSERT_FALSE(packet.retransmittable_frames.empty());
       EXPECT_EQ(num_retransmittable_frames,
                 packet.retransmittable_frames.size());
     }
 
     ASSERT_TRUE(packet.encrypted_buffer != nullptr);
     ASSERT_TRUE(simple_framer_.ProcessPacket(
         QuicEncryptedPacket(packet.encrypted_buffer, packet.encrypted_length)));
     EXPECT_EQ(num_frames, simple_framer_.num_frames());
     EXPECT_EQ(contents.num_ack_frames, simple_framer_.ack_frames().size());
     EXPECT_EQ(contents.num_connection_close_frames,
               simple_framer_.connection_close_frames().size());
     EXPECT_EQ(contents.num_goaway_frames,
               simple_framer_.goaway_frames().size());
     EXPECT_EQ(contents.num_rst_stream_frames,
               simple_framer_.rst_stream_frames().size());
     EXPECT_EQ(contents.num_stream_frames,
               simple_framer_.stream_frames().size());
     EXPECT_EQ(contents.num_stop_waiting_frames,
               simple_framer_.stop_waiting_frames().size());
+    EXPECT_EQ(contents.num_padding_frames,
+              simple_framer_.padding_frames().size());
 
     // From the receiver's perspective, MTU discovery frames are ping frames.
     EXPECT_EQ(contents.num_ping_frames + contents.num_mtu_discovery_frames,
               simple_framer_.ping_frames().size());
   }
 
   void CheckPacketHasSingleStreamFrame(size_t packet_index) {
     ASSERT_GT(packets_.size(), packet_index);
     const SerializedPacket& packet = packets_[packet_index];
     ASSERT_FALSE(packet.retransmittable_frames.empty());
@@ skipping 17 matching lines @@
     iov_.iov_base = data_array_.get();
     iov_.iov_len = len;
     return QuicIOVector(&iov_, 1, len);
   }
 
   QuicIOVector MakeIOVectorFromStringPiece(QuicStringPiece s) {
     return MakeIOVector(s, &iov_);
   }
 
   QuicFramer framer_;
+  MockRandom random_generator_;
   SimpleBufferAllocator buffer_allocator_;
   StrictMock<MockDelegate> delegate_;
   QuicPacketGenerator generator_;
   QuicPacketCreator* creator_;
   SimpleQuicFramer simple_framer_;
   std::vector<SerializedPacket> packets_;
   QuicAckFrame ack_frame_;
 
  private:
   std::unique_ptr<char[]> data_array_;
@@ skipping 115 matching lines @@
 
   PacketContents contents;
   contents.num_rst_stream_frames = 1;
   CheckPacketContains(contents, 0);
 }
 
 TEST_F(QuicPacketGeneratorTest, ConsumeData_NotWritable) {
   delegate_.SetCanNotWrite();
 
   QuicConsumedData consumed = generator_.ConsumeData(
-      kHeadersStreamId, MakeIOVectorFromStringPiece("foo"), 2, true, nullptr);
+      kHeadersStreamId, MakeIOVectorFromStringPiece("foo"), 2, FIN, nullptr);
   EXPECT_EQ(0u, consumed.bytes_consumed);
   EXPECT_FALSE(consumed.fin_consumed);
   EXPECT_FALSE(generator_.HasQueuedFrames());
 }
 
 TEST_F(QuicPacketGeneratorTest, ConsumeData_WritableAndShouldNotFlush) {
   delegate_.SetCanWriteAnything();
   generator_.StartBatchOperations();
 
   QuicConsumedData consumed = generator_.ConsumeData(
-      kHeadersStreamId, MakeIOVectorFromStringPiece("foo"), 2, true, nullptr);
+      kHeadersStreamId, MakeIOVectorFromStringPiece("foo"), 2, FIN, nullptr);
   EXPECT_EQ(3u, consumed.bytes_consumed);
   EXPECT_TRUE(consumed.fin_consumed);
   EXPECT_TRUE(generator_.HasQueuedFrames());
 }
 
 TEST_F(QuicPacketGeneratorTest, ConsumeData_WritableAndShouldFlush) {
   delegate_.SetCanWriteAnything();
 
   EXPECT_CALL(delegate_, OnSerializedPacket(_))
       .WillOnce(Invoke(this, &QuicPacketGeneratorTest::SavePacket));
   QuicConsumedData consumed = generator_.ConsumeData(
-      kHeadersStreamId, MakeIOVectorFromStringPiece("foo"), 2, true, nullptr);
+      kHeadersStreamId, MakeIOVectorFromStringPiece("foo"), 2, FIN, nullptr);
   EXPECT_EQ(3u, consumed.bytes_consumed);
   EXPECT_TRUE(consumed.fin_consumed);
   EXPECT_FALSE(generator_.HasQueuedFrames());
 
   PacketContents contents;
   contents.num_stream_frames = 1;
   CheckPacketContains(contents, 0);
 }
 
 // Test the behavior of ConsumeData when the data consumed is for the crypto
 // handshake stream.  Ensure that the packet is always sent and padded even if
 // the generator operates in batch mode.
 TEST_F(QuicPacketGeneratorTest, ConsumeData_Handshake) {
   delegate_.SetCanWriteAnything();
   generator_.StartBatchOperations();
 
   EXPECT_CALL(delegate_, OnSerializedPacket(_))
       .WillOnce(Invoke(this, &QuicPacketGeneratorTest::SavePacket));
   QuicConsumedData consumed = generator_.ConsumeData(
-      kCryptoStreamId, MakeIOVectorFromStringPiece("foo"), 0, false, nullptr);
+      kCryptoStreamId, MakeIOVectorFromStringPiece("foo"), 0, NO_FIN, nullptr);
   EXPECT_EQ(3u, consumed.bytes_consumed);
   EXPECT_FALSE(generator_.HasQueuedFrames());
 
   PacketContents contents;
   contents.num_stream_frames = 1;
+  contents.num_padding_frames = 1;
   CheckPacketContains(contents, 0);
 
   ASSERT_EQ(1u, packets_.size());
   ASSERT_EQ(kDefaultMaxPacketSize, generator_.GetCurrentMaxPacketLength());
   EXPECT_EQ(kDefaultMaxPacketSize, packets_[0].encrypted_length);
 }
 
 TEST_F(QuicPacketGeneratorTest, ConsumeData_EmptyData) {
   EXPECT_QUIC_BUG(
       generator_.ConsumeData(kHeadersStreamId, MakeIOVectorFromStringPiece(""),
-                             0, false, nullptr),
+                             0, NO_FIN, nullptr),
       "Attempt to consume empty data without FIN.");
 }
 
 TEST_F(QuicPacketGeneratorTest,
        ConsumeDataMultipleTimes_WritableAndShouldNotFlush) {
   delegate_.SetCanWriteAnything();
   generator_.StartBatchOperations();
 
   generator_.ConsumeData(kHeadersStreamId, MakeIOVectorFromStringPiece("foo"),
-                         2, true, nullptr);
+                         2, FIN, nullptr);
   QuicConsumedData consumed = generator_.ConsumeData(
-      3, MakeIOVectorFromStringPiece("quux"), 7, false, nullptr);
+      3, MakeIOVectorFromStringPiece("quux"), 7, NO_FIN, nullptr);
   EXPECT_EQ(4u, consumed.bytes_consumed);
   EXPECT_FALSE(consumed.fin_consumed);
   EXPECT_TRUE(generator_.HasQueuedFrames());
 }
 
 TEST_F(QuicPacketGeneratorTest, ConsumeData_BatchOperations) {
   delegate_.SetCanWriteAnything();
   generator_.StartBatchOperations();
 
   generator_.ConsumeData(kHeadersStreamId, MakeIOVectorFromStringPiece("foo"),
-                         2, true, nullptr);
+                         2, FIN, nullptr);
   QuicConsumedData consumed = generator_.ConsumeData(
-      3, MakeIOVectorFromStringPiece("quux"), 7, false, nullptr);
+      3, MakeIOVectorFromStringPiece("quux"), 7, NO_FIN, nullptr);
   EXPECT_EQ(4u, consumed.bytes_consumed);
   EXPECT_FALSE(consumed.fin_consumed);
   EXPECT_TRUE(generator_.HasQueuedFrames());
 
   // Now both frames will be flushed out.
   EXPECT_CALL(delegate_, OnSerializedPacket(_))
       .WillOnce(Invoke(this, &QuicPacketGeneratorTest::SavePacket));
   generator_.FinishBatchOperations();
   EXPECT_FALSE(generator_.HasQueuedFrames());
 
@@ skipping 21 matching lines @@
     InSequence dummy;
     EXPECT_CALL(delegate_, OnSerializedPacket(_))
         .WillOnce(Invoke(this, &QuicPacketGeneratorTest::SavePacket));
     EXPECT_CALL(delegate_, OnSerializedPacket(_))
         .WillOnce(Invoke(this, &QuicPacketGeneratorTest::SavePacket));
   }
   generator_.StartBatchOperations();
   // Queue enough data to prevent a stream frame with a non-zero offset from
   // fitting.
   QuicConsumedData consumed = generator_.ConsumeData(
-      kHeadersStreamId, MakeIOVectorFromStringPiece("foo"), 0, false, nullptr);
+      kHeadersStreamId, MakeIOVectorFromStringPiece("foo"), 0, NO_FIN, nullptr);
   EXPECT_EQ(3u, consumed.bytes_consumed);
   EXPECT_FALSE(consumed.fin_consumed);
   EXPECT_TRUE(generator_.HasQueuedFrames());
 
   // This frame will not fit with the existing frame, causing the queued frame
   // to be serialized, and it will be added to a new open packet.
   consumed = generator_.ConsumeData(
-      kHeadersStreamId, MakeIOVectorFromStringPiece("bar"), 3, true, nullptr);
+      kHeadersStreamId, MakeIOVectorFromStringPiece("bar"), 3, FIN, nullptr);
   EXPECT_EQ(3u, consumed.bytes_consumed);
   EXPECT_TRUE(consumed.fin_consumed);
   EXPECT_TRUE(generator_.HasQueuedFrames());
 
   creator_->Flush();
   EXPECT_FALSE(generator_.HasQueuedFrames());
 
   PacketContents contents;
   contents.num_stream_frames = 1;
   CheckPacketContains(contents, 0);
@@ skipping 27 matching lines @@
 
   delegate_.SetCanWriteAnything();
 
   generator_.StartBatchOperations();
 
   // When the first write operation is invoked, the ack frame will be returned.
   EXPECT_CALL(delegate_, GetUpdatedAckFrame())
       .WillOnce(Return(QuicFrame(&ack_frame_)));
 
   // Send some data and a control frame
-  generator_.ConsumeData(3, MakeIOVectorFromStringPiece("quux"), 7, false,
+  generator_.ConsumeData(3, MakeIOVectorFromStringPiece("quux"), 7, NO_FIN,
                          nullptr);
   generator_.AddControlFrame(QuicFrame(CreateGoAwayFrame()));
 
   // All five frames will be flushed out in a single packet.
   EXPECT_CALL(delegate_, OnSerializedPacket(_))
       .WillOnce(Invoke(this, &QuicPacketGeneratorTest::SavePacket));
   generator_.FinishBatchOperations();
   EXPECT_FALSE(generator_.HasQueuedFrames());
 
   PacketContents contents;
@@ skipping 24 matching lines @@
     // All five frames will be flushed out in a single packet
     EXPECT_CALL(delegate_, OnSerializedPacket(_))
         .WillOnce(Invoke(this, &QuicPacketGeneratorTest::SavePacket));
     EXPECT_CALL(delegate_, OnSerializedPacket(_))
         .WillOnce(Invoke(this, &QuicPacketGeneratorTest::SavePacket));
   }
 
   // Send enough data to exceed one packet
   size_t data_len = kDefaultMaxPacketSize + 100;
   QuicConsumedData consumed =
-      generator_.ConsumeData(3, CreateData(data_len), 0, true, nullptr);
+      generator_.ConsumeData(3, CreateData(data_len), 0, FIN, nullptr);
   EXPECT_EQ(data_len, consumed.bytes_consumed);
   EXPECT_TRUE(consumed.fin_consumed);
   generator_.AddControlFrame(QuicFrame(CreateGoAwayFrame()));
 
   generator_.FinishBatchOperations();
   EXPECT_FALSE(generator_.HasQueuedFrames());
 
   // The first packet should have the queued data and part of the stream data.
   PacketContents contents;
   contents.num_ack_frames = 1;
@@ skipping 28 matching lines @@
   size_t packet_len = kDefaultMaxPacketSize + 100;
   ASSERT_LE(packet_len, kMaxPacketSize);
   generator_.SetMaxPacketLength(packet_len);
   EXPECT_EQ(packet_len, generator_.GetCurrentMaxPacketLength());
 
   EXPECT_CALL(delegate_, OnSerializedPacket(_))
       .Times(3)
       .WillRepeatedly(Invoke(this, &QuicPacketGeneratorTest::SavePacket));
   QuicConsumedData consumed =
       generator_.ConsumeData(kHeadersStreamId, CreateData(data_len),
-                             /*offset=*/2,
-                             /*fin=*/true, nullptr);
+                             /*offset=*/2, FIN, nullptr);
   EXPECT_EQ(data_len, consumed.bytes_consumed);
   EXPECT_TRUE(consumed.fin_consumed);
   EXPECT_FALSE(generator_.HasQueuedFrames());
 
   // We expect three packets, and first two of them have to be of packet_len
   // size.  We check multiple packets (instead of just one) because we want to
   // ensure that |max_packet_length_| does not get changed incorrectly by the
   // generator after first packet is serialized.
   ASSERT_EQ(3u, packets_.size());
   EXPECT_EQ(packet_len, packets_[0].encrypted_length);
@@ skipping 13 matching lines @@
   ASSERT_LE(packet_len, kMaxPacketSize);
 
   // We expect to see three packets in total.
   EXPECT_CALL(delegate_, OnSerializedPacket(_))
       .Times(3)
       .WillRepeatedly(Invoke(this, &QuicPacketGeneratorTest::SavePacket));
 
   // Send two packets before packet size change.
   QuicConsumedData consumed =
       generator_.ConsumeData(kHeadersStreamId, CreateData(data_len),
-                             /*offset=*/2,
-                             /*fin=*/false, nullptr);
+                             /*offset=*/2, NO_FIN, nullptr);
   EXPECT_EQ(data_len, consumed.bytes_consumed);
   EXPECT_FALSE(consumed.fin_consumed);
   EXPECT_FALSE(generator_.HasQueuedFrames());
 
   // Make sure we already have two packets.
   ASSERT_EQ(2u, packets_.size());
 
   // Increase packet size.
   generator_.SetMaxPacketLength(packet_len);
   EXPECT_EQ(packet_len, generator_.GetCurrentMaxPacketLength());
 
   // Send a packet after packet size change.
   consumed = generator_.ConsumeData(kHeadersStreamId, CreateData(data_len),
-                                    2 + data_len,
-                                    /*fin=*/true, nullptr);
+                                    2 + data_len, FIN, nullptr);
   EXPECT_EQ(data_len, consumed.bytes_consumed);
   EXPECT_TRUE(consumed.fin_consumed);
   EXPECT_FALSE(generator_.HasQueuedFrames());
 
   // We expect first data chunk to get fragmented, but the second one to fit
   // into a single packet.
   ASSERT_EQ(3u, packets_.size());
   EXPECT_EQ(kDefaultMaxPacketSize, packets_[0].encrypted_length);
   EXPECT_LE(kDefaultMaxPacketSize, packets_[2].encrypted_length);
   CheckAllPacketsHaveSingleStreamFrame();
 }
 
 // Test whether SetMaxPacketLength() works correctly when we force the change of
 // the packet size in the middle of the batched packet.
 TEST_F(QuicPacketGeneratorTest, SetMaxPacketLength_MidpacketFlush) {
   delegate_.SetCanWriteAnything();
   generator_.StartBatchOperations();
 
   size_t first_write_len = kDefaultMaxPacketSize / 2;
   size_t packet_len = kDefaultMaxPacketSize + 100;
   size_t second_write_len = packet_len + 1;
   ASSERT_LE(packet_len, kMaxPacketSize);
 
   // First send half of the packet worth of data.  We are in the batch mode, so
   // should not cause packet serialization.
   QuicConsumedData consumed =
       generator_.ConsumeData(kHeadersStreamId, CreateData(first_write_len),
-                             /*offset=*/2,
-                             /*fin=*/false, nullptr);
+                             /*offset=*/2, NO_FIN, nullptr);
   EXPECT_EQ(first_write_len, consumed.bytes_consumed);
   EXPECT_FALSE(consumed.fin_consumed);
   EXPECT_TRUE(generator_.HasQueuedFrames());
 
   // Make sure we have no packets so far.
   ASSERT_EQ(0u, packets_.size());
 
   // Expect a packet to be flushed.
   EXPECT_CALL(delegate_, OnSerializedPacket(_))
       .WillOnce(Invoke(this, &QuicPacketGeneratorTest::SavePacket));
 
   // Increase packet size after flushing all frames.
   // Ensure it's immediately enacted.
   generator_.FlushAllQueuedFrames();
   generator_.SetMaxPacketLength(packet_len);
   EXPECT_EQ(packet_len, generator_.GetCurrentMaxPacketLength());
   EXPECT_FALSE(generator_.HasQueuedFrames());
 
   // We expect to see exactly one packet serialized after that, because we send
   // a value somewhat exceeding new max packet size, and the tail data does not
   // get serialized because we are still in the batch mode.
   EXPECT_CALL(delegate_, OnSerializedPacket(_))
       .WillOnce(Invoke(this, &QuicPacketGeneratorTest::SavePacket));
 
   // Send a more than a packet worth of data to the same stream.  This should
   // trigger serialization of one packet, and queue another one.
   consumed =
       generator_.ConsumeData(kHeadersStreamId, CreateData(second_write_len),
-                             /*offset=*/2 + first_write_len,
-                             /*fin=*/true, nullptr);
+                             /*offset=*/2 + first_write_len, FIN, nullptr);
   EXPECT_EQ(second_write_len, consumed.bytes_consumed);
   EXPECT_TRUE(consumed.fin_consumed);
   EXPECT_TRUE(generator_.HasQueuedFrames());
 
   // We expect the first packet to be underfilled, and the second packet be up
   // to the new max packet size.
   ASSERT_EQ(2u, packets_.size());
   EXPECT_GT(kDefaultMaxPacketSize, packets_[0].encrypted_length);
   EXPECT_EQ(packet_len, packets_[1].encrypted_length);
 
@@ skipping 12 matching lines @@
       .WillOnce(Invoke(this, &QuicPacketGeneratorTest::SavePacket));
 
   generator_.GenerateMtuDiscoveryPacket(target_mtu, nullptr);
 
   EXPECT_FALSE(generator_.HasQueuedFrames());
   ASSERT_EQ(1u, packets_.size());
   EXPECT_EQ(target_mtu, packets_[0].encrypted_length);
 
   PacketContents contents;
   contents.num_mtu_discovery_frames = 1;
+  contents.num_padding_frames = 1;
   CheckPacketContains(contents, 0);
 }
 
 // Test sending an MTU probe.  Surround it with data, to ensure that it resets
 // the MTU to the value before the probe was sent.
 TEST_F(QuicPacketGeneratorTest, GenerateMtuDiscoveryPacket_SurroundedByData) {
   delegate_.SetCanWriteAnything();
 
   const size_t target_mtu = kDefaultMaxPacketSize + 100;
   static_assert(target_mtu < kMaxPacketSize,
                 "The MTU probe used by the test exceeds maximum packet size");
 
   // Send enough data so it would always cause two packets to be sent.
   const size_t data_len = target_mtu + 1;
 
   // Send a total of five packets: two packets before the probe, the probe
   // itself, and two packets after the probe.
   EXPECT_CALL(delegate_, OnSerializedPacket(_))
       .Times(5)
       .WillRepeatedly(Invoke(this, &QuicPacketGeneratorTest::SavePacket));
 
   // Send data before the MTU probe.
   QuicConsumedData consumed =
       generator_.ConsumeData(kHeadersStreamId, CreateData(data_len),
-                             /*offset=*/2,
-                             /*fin=*/false, nullptr);
+                             /*offset=*/2, NO_FIN, nullptr);
   EXPECT_EQ(data_len, consumed.bytes_consumed);
   EXPECT_FALSE(consumed.fin_consumed);
   EXPECT_FALSE(generator_.HasQueuedFrames());
 
   // Send the MTU probe.
   generator_.GenerateMtuDiscoveryPacket(target_mtu, nullptr);
   EXPECT_FALSE(generator_.HasQueuedFrames());
 
   // Send data after the MTU probe.
   consumed = generator_.ConsumeData(kHeadersStreamId, CreateData(data_len),
-                                    /*offset=*/2 + data_len,
-                                    /*fin=*/true, nullptr);
+                                    /*offset=*/2 + data_len, FIN, nullptr);
   EXPECT_EQ(data_len, consumed.bytes_consumed);
   EXPECT_TRUE(consumed.fin_consumed);
   EXPECT_FALSE(generator_.HasQueuedFrames());
 
   ASSERT_EQ(5u, packets_.size());
   EXPECT_EQ(kDefaultMaxPacketSize, packets_[0].encrypted_length);
   EXPECT_EQ(target_mtu, packets_[2].encrypted_length);
   EXPECT_EQ(kDefaultMaxPacketSize, packets_[3].encrypted_length);
 
   PacketContents probe_contents;
   probe_contents.num_mtu_discovery_frames = 1;
+  probe_contents.num_padding_frames = 1;
 
   CheckPacketHasSingleStreamFrame(0);
   CheckPacketHasSingleStreamFrame(1);
   CheckPacketContains(probe_contents, 2);
   CheckPacketHasSingleStreamFrame(3);
   CheckPacketHasSingleStreamFrame(4);
 }
 
 TEST_F(QuicPacketGeneratorTest, DontCrashOnInvalidStopWaiting) {
   // Test added to ensure the generator does not crash when an invalid frame is
@@ skipping 32 matching lines @@
   char buf[2000] = {};
   QuicStringPiece error_details(buf, 2000);
   frame->error_details = error_details.as_string();
   EXPECT_CALL(delegate_,
               OnUnrecoverableError(QUIC_FAILED_TO_SERIALIZE_PACKET,
                                    "Single frame cannot fit into a packet", _));
   EXPECT_QUIC_BUG(generator_.AddControlFrame(QuicFrame(frame)), "");
   EXPECT_TRUE(generator_.HasQueuedFrames());
 }
 
+TEST_F(QuicPacketGeneratorTest, RandomPaddingAfterFinSingleStreamSinglePacket) {
+  const QuicByteCount kStreamFramePayloadSize = 100u;
+  char buf[kStreamFramePayloadSize] = {};
+  const QuicStreamId kDataStreamId = 5;
+  // Set the packet size be enough for one stream frame with 0 stream offset and
+  // max size of random padding.
+  size_t length = NullEncrypter(Perspective::IS_CLIENT).GetCiphertextSize(0) +
+                  GetPacketHeaderSize(
+                      framer_.version(), creator_->connection_id_length(),
+                      kIncludeVersion, !kIncludeDiversificationNonce,
+                      QuicPacketCreatorPeer::GetPacketNumberLength(creator_)) +
+                  QuicFramer::GetMinStreamFrameSize(
+                      kDataStreamId, 0, /*last_frame_in_packet=*/false) +
+                  kStreamFramePayloadSize + kMaxNumRandomPaddingBytes;
+  generator_.SetMaxPacketLength(length);
+  delegate_.SetCanWriteAnything();
+  generator_.StartBatchOperations();
+  EXPECT_CALL(delegate_, OnSerializedPacket(_))
+      .WillOnce(Invoke(this, &QuicPacketGeneratorTest::SavePacket));
+  QuicConsumedData consumed =
+      generator_.ConsumeData(kDataStreamId,
+                             MakeIOVectorFromStringPiece(
+                                 QuicStringPiece(buf, kStreamFramePayloadSize)),
+                             0, FIN_AND_PADDING, nullptr);
+  generator_.FinishBatchOperations();
+  EXPECT_EQ(kStreamFramePayloadSize, consumed.bytes_consumed);
+  EXPECT_FALSE(generator_.HasQueuedFrames());
+
+  EXPECT_EQ(1u, packets_.size());
+  PacketContents contents;
+  // The packet has both stream and padding frames.
+  contents.num_padding_frames = 1;
+  contents.num_stream_frames = 1;
+  CheckPacketContains(contents, 0);
+}
+
+TEST_F(QuicPacketGeneratorTest,
+       RandomPaddingAfterFinSingleStreamMultiplePackets) {
+  const QuicByteCount kStreamFramePayloadSize = 100u;
+  char buf[kStreamFramePayloadSize] = {};
+  const QuicStreamId kDataStreamId = 5;
+  // Set the packet size be enough for one stream frame with 0 stream offset +
+  // 1. One or more packets will accommodate.
+  size_t length = NullEncrypter(Perspective::IS_CLIENT).GetCiphertextSize(0) +
+                  GetPacketHeaderSize(
+                      framer_.version(), creator_->connection_id_length(),
+                      kIncludeVersion, !kIncludeDiversificationNonce,
+                      QuicPacketCreatorPeer::GetPacketNumberLength(creator_)) +
+                  QuicFramer::GetMinStreamFrameSize(
+                      kDataStreamId, 0, /*last_frame_in_packet=*/false) +
+                  kStreamFramePayloadSize + 1;
+  generator_.SetMaxPacketLength(length);
+  delegate_.SetCanWriteAnything();
+  generator_.StartBatchOperations();
+  EXPECT_CALL(delegate_, OnSerializedPacket(_))
+      .WillRepeatedly(Invoke(this, &QuicPacketGeneratorTest::SavePacket));
+  QuicConsumedData consumed =
+      generator_.ConsumeData(kDataStreamId,
+                             MakeIOVectorFromStringPiece(
+                                 QuicStringPiece(buf, kStreamFramePayloadSize)),
+                             0, FIN_AND_PADDING, nullptr);
+  generator_.FinishBatchOperations();
+  EXPECT_EQ(kStreamFramePayloadSize, consumed.bytes_consumed);
+  EXPECT_FALSE(generator_.HasQueuedFrames());
+
+  EXPECT_LE(1u, packets_.size());
+  PacketContents contents;
+  // The first packet has both stream and padding frames.
+  contents.num_stream_frames = 1;
+  contents.num_padding_frames = 1;
+  CheckPacketContains(contents, 0);
+
+  for (size_t i = 1; i < packets_.size(); ++i) {
+    // Following packets only have paddings.
+    contents.num_stream_frames = 0;
+    contents.num_padding_frames = 1;
+    CheckPacketContains(contents, i);
+  }
+}
+
+TEST_F(QuicPacketGeneratorTest,
+       RandomPaddingAfterFinMultipleStreamsMultiplePackets) {
+  const QuicByteCount kStreamFramePayloadSize = 100u;
+  char buf[kStreamFramePayloadSize] = {};
+  const QuicStreamId kDataStreamId1 = 5;
+  const QuicStreamId kDataStreamId2 = 6;
+  // Set the packet size be enough for first frame with 0 stream offset + second
+  // frame + 1 byte payload. two or more packets will accommodate.
+  size_t length = NullEncrypter(Perspective::IS_CLIENT).GetCiphertextSize(0) +
+                  GetPacketHeaderSize(
+                      framer_.version(), creator_->connection_id_length(),
+                      kIncludeVersion, !kIncludeDiversificationNonce,
+                      QuicPacketCreatorPeer::GetPacketNumberLength(creator_)) +
+                  QuicFramer::GetMinStreamFrameSize(
+                      kDataStreamId1, 0, /*last_frame_in_packet=*/false) +
+                  kStreamFramePayloadSize +
+                  QuicFramer::GetMinStreamFrameSize(
+                      kDataStreamId1, 0, /*last_frame_in_packet=*/false) +
+                  1;
+  generator_.SetMaxPacketLength(length);
+  delegate_.SetCanWriteAnything();
+  generator_.StartBatchOperations();
+  EXPECT_CALL(delegate_, OnSerializedPacket(_))
+      .WillRepeatedly(Invoke(this, &QuicPacketGeneratorTest::SavePacket));
+  QuicConsumedData consumed =
+      generator_.ConsumeData(kDataStreamId1,
+                             MakeIOVectorFromStringPiece(
+                                 QuicStringPiece(buf, kStreamFramePayloadSize)),
+                             0, FIN_AND_PADDING, nullptr);
+  EXPECT_EQ(kStreamFramePayloadSize, consumed.bytes_consumed);
+  consumed = generator_.ConsumeData(kDataStreamId2,
+                                    MakeIOVectorFromStringPiece(QuicStringPiece(
+                                        buf, kStreamFramePayloadSize)),
+                                    0, FIN_AND_PADDING, nullptr);
+  EXPECT_EQ(kStreamFramePayloadSize, consumed.bytes_consumed);
+  generator_.FinishBatchOperations();
+  EXPECT_FALSE(generator_.HasQueuedFrames());
+
+  EXPECT_LE(2u, packets_.size());
+  PacketContents contents;
+  // The first packet has two stream frames.
+  contents.num_stream_frames = 2;
+  CheckPacketContains(contents, 0);
+
+  // The second packet has one stream frame and padding frames.
+  contents.num_stream_frames = 1;
+  contents.num_padding_frames = 1;
+  CheckPacketContains(contents, 1);
+
+  for (size_t i = 2; i < packets_.size(); ++i) {
+    // Following packets only have paddings.
+    contents.num_stream_frames = 0;
+    contents.num_padding_frames = 1;
+    CheckPacketContains(contents, i);
+  }
+}
+
 }  // namespace test
 }  // namespace net