rtt calculation handles time go backwards

webrtc/modules/rtp_rtcp/source/rtcp_receiver_unittest.cc

 /*
  *  Copyright (c) 2012 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.
  */
 
@@ skipping 166 matching lines @@
   rtc::Buffer packet = sr.Build();
   EXPECT_EQ(0, InjectRtcpPacket(packet.data(), packet.size()));
   EXPECT_EQ(kSenderSsrc, rtcp_packet_info_.remoteSSRC);
   EXPECT_EQ(kRtcpSr, rtcp_packet_info_.rtcpPacketTypeFlags);
 }
 
 TEST_F(RtcpReceiverTest, InjectSrPacketCalculatesRTT) {
   Random r(0x0123456789abcdef);
   const uint32_t kSenderSsrc = r.Rand(0x00000001u, 0xfffffffeu);
   const uint32_t kRemoteSsrc = r.Rand(0x00000001u, 0xfffffffeu);
-  const int64_t kRttMs = r.Rand(1, 18 * 3600 * 1000);
-  const uint32_t kDelayNtp = r.Rand<uint32_t>();
-  const uint32_t kDelayMs = CompactNtpIntervalToMs(kDelayNtp);
+  const int64_t kRttMs = r.Rand(1, 9 * 3600 * 1000);
+  const uint32_t kDelayNtp = r.Rand(0, 0x7fffffff);
+  const int64_t kDelayMs = CompactNtpRttToMs(kDelayNtp);
 
   rtcp_receiver_->SetRemoteSSRC(kSenderSsrc);
   std::set<uint32_t> ssrcs;
   ssrcs.insert(kRemoteSsrc);
   rtcp_receiver_->SetSsrcs(kRemoteSsrc, ssrcs);
 
   int64_t rtt_ms = 0;
   EXPECT_EQ(
       -1, rtcp_receiver_->RTT(kSenderSsrc, &rtt_ms, nullptr, nullptr, nullptr));
 
   uint32_t sent_ntp = CompactNtp(NtpTime(system_clock_));
   system_clock_.AdvanceTimeMilliseconds(kRttMs + kDelayMs);
 
   rtcp::SenderReport sr;
   sr.From(kSenderSsrc);
   rtcp::ReportBlock block;
   block.To(kRemoteSsrc);
   block.WithLastSr(sent_ntp);
   block.WithDelayLastSr(kDelayNtp);
   sr.WithReportBlock(block);
 
   rtc::Buffer packet = sr.Build();
   EXPECT_EQ(0, InjectRtcpPacket(packet.data(), packet.size()));
 
   EXPECT_EQ(
       0, rtcp_receiver_->RTT(kSenderSsrc, &rtt_ms, nullptr, nullptr, nullptr));
   EXPECT_NEAR(kRttMs, rtt_ms, 1);
 }
 
+TEST_F(RtcpReceiverTest, InjectSrPacketCalculatesNegativeRTTAsOne) {
+  Random r(0x0123456789abcdef);
+  const uint32_t kSenderSsrc = r.Rand(0x00000001u, 0xfffffffeu);
+  const uint32_t kRemoteSsrc = r.Rand(0x00000001u, 0xfffffffeu);
+  const int64_t kRttMs = r.Rand(-3600 * 1000, -1);
+  const uint32_t kDelayNtp = r.Rand(0, 0x7fffffff);
+  const int64_t kDelayMs = CompactNtpRttToMs(kDelayNtp);
+
+  rtcp_receiver_->SetRemoteSSRC(kSenderSsrc);
+  std::set<uint32_t> ssrcs;
+  ssrcs.insert(kRemoteSsrc);
+  rtcp_receiver_->SetSsrcs(kRemoteSsrc, ssrcs);
+
+  int64_t rtt_ms = 0;
+  EXPECT_EQ(
+      -1, rtcp_receiver_->RTT(kSenderSsrc, &rtt_ms, nullptr, nullptr, nullptr));
+
+  uint32_t sent_ntp = CompactNtp(NtpTime(system_clock_));
+  system_clock_.AdvanceTimeMilliseconds(kRttMs + kDelayMs);
+
+  rtcp::SenderReport sr;
+  sr.From(kSenderSsrc);
+  rtcp::ReportBlock block;
+  block.To(kRemoteSsrc);
+  block.WithLastSr(sent_ntp);
+  block.WithDelayLastSr(kDelayNtp);
+  sr.WithReportBlock(block);
+
+  rtc::Buffer packet = sr.Build();
+  EXPECT_EQ(0, InjectRtcpPacket(packet.data(), packet.size()));
+
+  EXPECT_EQ(
+      0, rtcp_receiver_->RTT(kSenderSsrc, &rtt_ms, nullptr, nullptr, nullptr));
+  EXPECT_EQ(1, rtt_ms);
+}
+
 TEST_F(RtcpReceiverTest, InjectRrPacket) {
   const uint32_t kSenderSsrc = 0x10203;
   rtcp::ReceiverReport rr;
   rr.From(kSenderSsrc);
   rtc::Buffer packet = rr.Build();
   EXPECT_EQ(0, InjectRtcpPacket(packet.data(), packet.size()));
   EXPECT_EQ(kSenderSsrc, rtcp_packet_info_.remoteSSRC);
   EXPECT_EQ(kRtcpRr, rtcp_packet_info_.rtcpPacketTypeFlags);
   ASSERT_EQ(0u, rtcp_packet_info_.report_blocks.size());
 }
@@ skipping 554 matching lines @@
                                       kRtcpXrVoipMetric),
             rtcp_packet_info_.rtcpPacketTypeFlags);
   EXPECT_FALSE(rtcp_packet_info_.xr_dlrr_item);
 }
 
 TEST_F(RtcpReceiverTest, TestXrRrRttInitiallyFalse) {
   int64_t rtt_ms;
   EXPECT_FALSE(rtcp_receiver_->GetAndResetXrRrRtt(&rtt_ms));
 }
 
-TEST_F(RtcpReceiverTest, RttCalculatedAfterXrDlrr) {
+TEST_F(RtcpReceiverTest, XrDlrrCalculatesRtt) {
   Random rand(0x0123456789abcdef);
   const uint32_t kSourceSsrc = rand.Rand(0x00000001u, 0xfffffffeu);
-  const uint32_t kRttMs = rand.Rand(1, 18 * 3600 * 1000);
-  const uint32_t kDelayNtp = rand.Rand<uint32_t>();
-  const uint32_t kDelayMs = CompactNtpIntervalToMs(kDelayNtp);
+  const int64_t kRttMs = rand.Rand(1, 9 * 3600 * 1000);
+  const uint32_t kDelayNtp = rand.Rand(0, 0x7fffffff);
+  const int64_t kDelayMs = CompactNtpRttToMs(kDelayNtp);
+  rtcp_receiver_->SetRtcpXrRrtrStatus(true);
   std::set<uint32_t> ssrcs;
   ssrcs.insert(kSourceSsrc);
   rtcp_receiver_->SetSsrcs(kSourceSsrc, ssrcs);
   NtpTime now(system_clock_);
   uint32_t sent_ntp = CompactNtp(now);
   system_clock_.AdvanceTimeMilliseconds(kRttMs + kDelayMs);
 
   rtcp::Dlrr dlrr;
   dlrr.WithDlrrItem(kSourceSsrc, sent_ntp, kDelayNtp);
   rtcp::ExtendedReports xr;
   xr.From(0x2345);
   xr.WithDlrr(dlrr);
   rtc::Buffer packet = xr.Build();
   EXPECT_EQ(0, InjectRtcpPacket(packet.data(), packet.size()));
 
   int64_t rtt_ms = 0;
   EXPECT_TRUE(rtcp_receiver_->GetAndResetXrRrRtt(&rtt_ms));
   EXPECT_NEAR(kRttMs, rtt_ms, 1);
 }
 
+TEST_F(RtcpReceiverTest, XrDlrrCalculatesNegativeRttAsOne) {
+  Random rand(0x0123456789abcdef);
+  const uint32_t kSourceSsrc = rand.Rand(0x00000001u, 0xfffffffeu);
+  const int64_t kRttMs = rand.Rand(-3600 * 1000, -1);
+  const uint32_t kDelayNtp = rand.Rand(0, 0x7fffffff);
+  const int64_t kDelayMs = CompactNtpRttToMs(kDelayNtp);
+  rtcp_receiver_->SetRtcpXrRrtrStatus(true);
+  std::set<uint32_t> ssrcs;
+  ssrcs.insert(kSourceSsrc);
+  rtcp_receiver_->SetSsrcs(kSourceSsrc, ssrcs);
+  NtpTime now(system_clock_);
+  uint32_t sent_ntp = CompactNtp(now);
+  system_clock_.AdvanceTimeMilliseconds(kRttMs + kDelayMs);
+
+  rtcp::Dlrr dlrr;
+  dlrr.WithDlrrItem(kSourceSsrc, sent_ntp, kDelayNtp);
+  rtcp::ExtendedReports xr;
+  xr.From(0x2345);
+  xr.WithDlrr(dlrr);
+  rtc::Buffer packet = xr.Build();
+  EXPECT_EQ(0, InjectRtcpPacket(packet.data(), packet.size()));
+
+  int64_t rtt_ms = 0;
+  EXPECT_TRUE(rtcp_receiver_->GetAndResetXrRrRtt(&rtt_ms));
+  EXPECT_EQ(1, rtt_ms);
+}
+
 TEST_F(RtcpReceiverTest, LastReceivedXrReferenceTimeInfoInitiallyFalse) {
   RtcpReceiveTimeInfo info;
   EXPECT_FALSE(rtcp_receiver_->LastReceivedXrReferenceTimeInfo(&info));
 }
 
 TEST_F(RtcpReceiverTest, GetLastReceivedExtendedReportsReferenceTimeInfo) {
   const uint32_t kSenderSsrc = 0x123456;
   const NtpTime kNtp(0x10203, 0x40506);
   const uint32_t kNtpMid = CompactNtp(kNtp);
 
@@ skipping 322 matching lines @@
 
   // Transport feedback should be ignored, but next packet should work.
   EXPECT_EQ(0u, rtcp_packet_info_.rtcpPacketTypeFlags & kRtcpTransportFeedback);
   EXPECT_NE(0u, rtcp_packet_info_.rtcpPacketTypeFlags & kRtcpRemb);
   EXPECT_EQ(kBitrateBps, rtcp_packet_info_.receiverEstimatedMaxBitrate);
 }
 
 }  // Anonymous namespace
 
 }  // namespace webrtc