Generalize FEC header formatting. (pt. 4)

webrtc/modules/rtp_rtcp/source/ulpfec_header_reader_writer_unittest.cc

+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include <string.h>
+
+#include <memory>
+#include <utility>
+
+#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/base/basictypes.h"
+#include "webrtc/base/checks.h"
+#include "webrtc/base/random.h"
+#include "webrtc/base/scoped_ref_ptr.h"
+#include "webrtc/modules/rtp_rtcp/source/byte_io.h"
+#include "webrtc/modules/rtp_rtcp/source/forward_error_correction.h"
+#include "webrtc/modules/rtp_rtcp/source/forward_error_correction_internal.h"
+#include "webrtc/modules/rtp_rtcp/source/ulpfec_header_reader_writer.h"
+
+namespace webrtc {
+
+namespace {
+
+using Packet = ::webrtc::ForwardErrorCorrection::Packet;
+using ReceivedFecPacket = ::webrtc::ForwardErrorCorrection::ReceivedFecPacket;
+
+constexpr uint32_t kMediaSsrc = 1254983;
+constexpr uint16_t kMediaStartSeqNum = 825;
+constexpr size_t kMediaPacketLength = 1234;
+
+constexpr size_t kUlpfecHeaderSizeLBitClear = 14;
+constexpr size_t kUlpfecHeaderSizeLBitSet = 18;
+constexpr size_t kUlpfecPacketMaskOffset = 12;
+
+std::unique_ptr<uint8_t[]> GeneratePacketMask(size_t packet_mask_size,
+                                              uint64_t seed) {
+  Random random(seed);
+  std::unique_ptr<uint8_t[]> packet_mask(new uint8_t[packet_mask_size]);
+  for (size_t i = 0; i < packet_mask_size; ++i) {
+    packet_mask[i] = random.Rand<uint8_t>();
+  }
+  return packet_mask;
+}
+
+std::unique_ptr<Packet> WriteHeader(const uint8_t* packet_mask,
+                                    size_t packet_mask_size) {
+  UlpfecHeaderWriter writer;
+  std::unique_ptr<Packet> written_packet(new Packet());
+  written_packet->length = kMediaPacketLength;
+  for (size_t i = 0; i < written_packet->length; ++i) {
+    written_packet->data[i] = i;  // Actual content doesn't matter.
+  }
+  writer.FinalizeFecHeader(kMediaStartSeqNum, packet_mask, packet_mask_size,
+                           written_packet.get());
+  return written_packet;
+}
+
+std::unique_ptr<ReceivedFecPacket> ReadHeader(const Packet& written_packet) {
+  UlpfecHeaderReader reader;
+  std::unique_ptr<ReceivedFecPacket> read_packet(new ReceivedFecPacket());
+  read_packet->ssrc = kMediaSsrc;
+  read_packet->pkt = rtc::scoped_refptr<Packet>(new Packet());
+  memcpy(read_packet->pkt->data, written_packet.data, written_packet.length);
+  read_packet->pkt->length = written_packet.length;
+  EXPECT_TRUE(reader.ReadFecHeader(read_packet.get()));
+  return read_packet;
+}
+
+void VerifyHeaders(size_t expected_fec_header_size,
+                   const uint8_t* expected_packet_mask,
+                   size_t expected_packet_mask_size,
+                   const Packet& written_packet,
+                   const ReceivedFecPacket& read_packet) {
+  EXPECT_EQ(kMediaSsrc, read_packet.ssrc);
+  EXPECT_EQ(expected_fec_header_size, read_packet.fec_header_size);
+  EXPECT_EQ(kMediaSsrc, read_packet.protected_ssrc);
+  EXPECT_EQ(kMediaStartSeqNum, read_packet.seq_num_base);
+  EXPECT_EQ(kUlpfecPacketMaskOffset, read_packet.packet_mask_offset);
+  ASSERT_EQ(expected_packet_mask_size, read_packet.packet_mask_size);
+  EXPECT_EQ(written_packet.length - expected_fec_header_size,
+            read_packet.protection_length);
+  EXPECT_EQ(0, memcmp(expected_packet_mask,
+                      &read_packet.pkt->data[read_packet.packet_mask_offset],
+                      read_packet.packet_mask_size));
+  // Verify that the call to ReadFecHeader did not tamper with the payload.
+  EXPECT_EQ(0, memcmp(&written_packet.data[expected_fec_header_size],
+                      &read_packet.pkt->data[expected_fec_header_size],
+                      written_packet.length - expected_fec_header_size));
+}
+
+}  // namespace
+
+TEST(UlpfecHeaderReaderTest, ReadsSmallHeader) {
+  const uint8_t packet[] = {
+      0x00, 0x12, 0xab, 0xcd,  // L bit clear, "random" payload type and SN base
+      0x12, 0x34, 0x56, 0x78,  // "random" TS recovery
+      0xab, 0xcd, 0x11, 0x22,  // "random" length recovery and protection length
+      0x33, 0x44,              // "random" packet mask
+      0x00, 0x00, 0x00, 0x00   // payload
+  };
+  const size_t packet_length = sizeof(packet);
+  ReceivedFecPacket read_packet;
+  read_packet.pkt = rtc::scoped_refptr<Packet>(new Packet());
+  memcpy(read_packet.pkt->data, packet, packet_length);
+  read_packet.pkt->length = packet_length;
+
+  UlpfecHeaderReader reader;
+  EXPECT_TRUE(reader.ReadFecHeader(&read_packet));
+
+  EXPECT_EQ(14U, read_packet.fec_header_size);
+  EXPECT_EQ(0xabcdU, read_packet.seq_num_base);
+  EXPECT_EQ(12U, read_packet.packet_mask_offset);
+  EXPECT_EQ(2U, read_packet.packet_mask_size);
+  EXPECT_EQ(0x1122U, read_packet.protection_length);
+}
+
+TEST(UlpfecHeaderReaderTest, ReadsLargeHeader) {
+  const uint8_t packet[] = {
+      0x40, 0x12, 0xab, 0xcd,  // L bit set, "random" payload type and SN base
+      0x12, 0x34, 0x56, 0x78,  // "random" TS recovery
+      0xab, 0xcd, 0x11, 0x22,  // "random" length recovery and protection length
+      0x33, 0x44, 0x55, 0x66,  // "random" packet mask
+      0x77, 0x88,              //
+      0x00, 0x00, 0x00, 0x00   // payload
+  };
+  const size_t packet_length = sizeof(packet);
+  ReceivedFecPacket read_packet;
+  read_packet.pkt = rtc::scoped_refptr<Packet>(new Packet());
+  memcpy(read_packet.pkt->data, packet, packet_length);
+  read_packet.pkt->length = packet_length;
+
+  UlpfecHeaderReader reader;
+  EXPECT_TRUE(reader.ReadFecHeader(&read_packet));
+
+  EXPECT_EQ(18U, read_packet.fec_header_size);
+  EXPECT_EQ(0xabcdU, read_packet.seq_num_base);
+  EXPECT_EQ(12U, read_packet.packet_mask_offset);
+  EXPECT_EQ(6U, read_packet.packet_mask_size);
+  EXPECT_EQ(0x1122U, read_packet.protection_length);
+}
+
+TEST(UlpfecHeaderWriterTest, FinalizesSmallHeader) {
+  const size_t packet_mask_size = kUlpfecPacketMaskSizeLBitClear;
+  auto packet_mask = GeneratePacketMask(packet_mask_size, 0xabcd);
+  Packet written_packet;
+  written_packet.length = kMediaPacketLength;
+  for (size_t i = 0; i < written_packet.length; ++i) {
+    written_packet.data[i] = i;
+  }
+
+  UlpfecHeaderWriter writer;
+  writer.FinalizeFecHeader(kMediaStartSeqNum, packet_mask.get(),
+                           packet_mask_size, &written_packet);
+
+  const uint8_t* packet = written_packet.data;
+  EXPECT_EQ(0x00, packet[0] & 0x80);  // E bit.
+  EXPECT_EQ(0x00, packet[0] & 0x40);  // L bit.
+  EXPECT_EQ(kMediaStartSeqNum, ByteReader<uint16_t>::ReadBigEndian(packet + 2));
+  EXPECT_EQ(
+      static_cast<uint16_t>(kMediaPacketLength - kUlpfecHeaderSizeLBitClear),
+      ByteReader<uint16_t>::ReadBigEndian(packet + 10));
+  EXPECT_EQ(0, memcmp(packet + kUlpfecPacketMaskOffset, packet_mask.get(),
+                      packet_mask_size));
+}
+
+TEST(UlpfecHeaderWriterTest, FinalizesLargeHeader) {
+  const size_t packet_mask_size = kUlpfecPacketMaskSizeLBitSet;
+  auto packet_mask = GeneratePacketMask(packet_mask_size, 0xabcd);
+  Packet written_packet;
+  written_packet.length = kMediaPacketLength;
+  for (size_t i = 0; i < written_packet.length; ++i) {
+    written_packet.data[i] = i;
+  }
+
+  UlpfecHeaderWriter writer;
+  writer.FinalizeFecHeader(kMediaStartSeqNum, packet_mask.get(),
+                           packet_mask_size, &written_packet);
+
+  const uint8_t* packet = written_packet.data;
+  EXPECT_EQ(0x00, packet[0] & 0x80);  // E bit.
+  EXPECT_EQ(0x40, packet[0] & 0x40);  // L bit.
+  EXPECT_EQ(kMediaStartSeqNum, ByteReader<uint16_t>::ReadBigEndian(packet + 2));
+  EXPECT_EQ(
+      static_cast<uint16_t>(kMediaPacketLength - kUlpfecHeaderSizeLBitSet),
+      ByteReader<uint16_t>::ReadBigEndian(packet + 10));
+  EXPECT_EQ(0, memcmp(packet + kUlpfecPacketMaskOffset, packet_mask.get(),
+                      packet_mask_size));
+}
+
+TEST(UlpfecHeaderWriterTest, CalculateSmallHeaderSize) {
+  const size_t packet_mask_size = kUlpfecPacketMaskSizeLBitClear;
+  auto packet_mask = GeneratePacketMask(packet_mask_size, 0xabcd);
+
+  UlpfecHeaderWriter writer;
+  size_t min_packet_mask_size =
+      writer.MinPacketMaskSize(packet_mask.get(), packet_mask_size);
+
+  EXPECT_EQ(kUlpfecPacketMaskSizeLBitClear, min_packet_mask_size);
+  EXPECT_EQ(kUlpfecHeaderSizeLBitClear,
+            writer.FecHeaderSize(min_packet_mask_size));
+}
+
+TEST(UlpfecHeaderWriterTest, CalculateLargeHeaderSize) {
+  const size_t packet_mask_size = kUlpfecPacketMaskSizeLBitSet;
+  auto packet_mask = GeneratePacketMask(packet_mask_size, 0xabcd);
+
+  UlpfecHeaderWriter writer;
+  size_t min_packet_mask_size =
+      writer.MinPacketMaskSize(packet_mask.get(), packet_mask_size);
+
+  EXPECT_EQ(kUlpfecPacketMaskSizeLBitSet, min_packet_mask_size);
+  EXPECT_EQ(kUlpfecHeaderSizeLBitSet,
+            writer.FecHeaderSize(min_packet_mask_size));
+}
+
+TEST(UlpfecHeaderReaderWriterTest, WriteAndReadSmallHeader) {
+  const size_t packet_mask_size = kUlpfecPacketMaskSizeLBitClear;
+  auto packet_mask = GeneratePacketMask(packet_mask_size, 0xabcd);
+
+  auto written_packet = WriteHeader(packet_mask.get(), packet_mask_size);
+  auto read_packet = ReadHeader(*written_packet);
+
+  VerifyHeaders(kUlpfecHeaderSizeLBitClear, packet_mask.get(), packet_mask_size,
+                *written_packet, *read_packet);
+}
+
+TEST(UlpfecHeaderReaderWriterTest, WriteAndReadLargeHeader) {
+  const size_t packet_mask_size = kUlpfecPacketMaskSizeLBitSet;
+  auto packet_mask = GeneratePacketMask(packet_mask_size, 0xabcd);
+
+  auto written_packet = WriteHeader(packet_mask.get(), packet_mask_size);
+  auto read_packet = ReadHeader(*written_packet);
+
+  VerifyHeaders(kUlpfecHeaderSizeLBitSet, packet_mask.get(), packet_mask_size,
+                *written_packet, *read_packet);
+}
+
+}  // namespace webrtc