cherry-pick-eef098d1c7d5.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Henrik=20Bostr=C3=B6m?= <hbos@webrtc.org>
Date: Mon, 19 Sep 2022 11:33:23 +0200
Subject: Avoid DCHECK crashing if SSRCs are not unique.
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To properly handle SSRC collisions in non-BUNDLE we need to change how
RTP stats IDs are generated, but that is a riskier change to be dealt
with in a separate CL.

For now, we just make sure that crashing is not a possibility during
SSRC collisions as a mitigation for https://crbug.com/1361612. This is
achieved by adding a TryAddStats() method to RTCStatsReport returning
whether successful.

(cherry picked from commit da6297dc53cb2eaae7b1c5381652de9d707a7d48)

Bug: chromium:1361612
Change-Id: I8577ae4c84a7c1eb3c7527e9efd8d1b0254269a3
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/275766
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Henrik Boström <hbos@webrtc.org>
Cr-Original-Commit-Position: refs/heads/main@{#38197}
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/277900
Reviewed-by: Evan Shrubsole <eshr@webrtc.org>
Cr-Commit-Position: refs/branch-heads/5304@{#4}
Cr-Branched-From: 024bd84ca1cf7d3650c27912a3b5bfbb54da152a-refs/heads/main@{#38083}

diff --git a/api/stats/rtc_stats_report.h b/api/stats/rtc_stats_report.h
index 2ced422370c79fab5ff3d95c24110b468a3eb9ee..f84272cb81f9e1ae1a8926f6627e221bbe456c2d 100644
--- a/api/stats/rtc_stats_report.h
+++ b/api/stats/rtc_stats_report.h
@@ -17,6 +17,7 @@
 #include <map>
 #include <memory>
 #include <string>
+#include <utility>
 #include <vector>
 
 #include "api/ref_counted_base.h"
@@ -68,6 +69,18 @@ class RTC_EXPORT RTCStatsReport final
 
   int64_t timestamp_us() const { return timestamp_us_; }
   void AddStats(std::unique_ptr<const RTCStats> stats);
+  // On success, returns a non-owning pointer to `stats`. If the stats ID is not
+  // unique, `stats` is not inserted and nullptr is returned.
+  template <typename T>
+  T* TryAddStats(std::unique_ptr<T> stats) {
+    T* stats_ptr = stats.get();
+    if (!stats_
+             .insert(std::make_pair(std::string(stats->id()), std::move(stats)))
+             .second) {
+      return nullptr;
+    }
+    return stats_ptr;
+  }
   const RTCStats* Get(const std::string& id) const;
   size_t size() const { return stats_.size(); }
 
diff --git a/pc/rtc_stats_collector.cc b/pc/rtc_stats_collector.cc
index be6c23e8430cb2b19839c5b2cb7eebaa576a92cb..10dfb1501984f9cc99fa04432abbd9c74bc7b708 100644
--- a/pc/rtc_stats_collector.cc
+++ b/pc/rtc_stats_collector.cc
@@ -1938,6 +1938,12 @@ void RTCStatsCollector::ProduceAudioRTPStreamStats_n(
       inbound_audio->track_identifier = audio_track->id();
     }
     inbound_audio->transport_id = transport_id;
+    auto* inbound_audio_ptr = report->TryAddStats(std::move(inbound_audio));
+    if (!inbound_audio_ptr) {
+      RTC_LOG(LS_ERROR)
+          << "Unable to add audio 'inbound-rtp' to report, ID is not unique.";
+      continue;
+    }
     // Remote-outbound.
     auto remote_outbound_audio = CreateRemoteOutboundAudioStreamStats(
         voice_receiver_info, mid, inbound_audio->id(), transport_id);
@@ -1945,10 +1951,15 @@ void RTCStatsCollector::ProduceAudioRTPStreamStats_n(
     if (remote_outbound_audio) {
       // When the remote outbound stats are available, the remote ID for the
       // local inbound stats is set.
-      inbound_audio->remote_id = remote_outbound_audio->id();
-      report->AddStats(std::move(remote_outbound_audio));
+      auto* remote_outbound_audio_ptr =
+          report->TryAddStats(std::move(remote_outbound_audio));
+      if (remote_outbound_audio_ptr) {
+        inbound_audio_ptr->remote_id = remote_outbound_audio_ptr->id();
+      } else {
+        RTC_LOG(LS_ERROR) << "Unable to add audio 'remote-outbound-rtp' to "
+                          << "report, ID is not unique.";
+      }
     }
-    report->AddStats(std::move(inbound_audio));
   }
   // Outbound.
   std::map<std::string, RTCOutboundRTPStreamStats*> audio_outbound_rtps;
@@ -1976,9 +1987,14 @@ void RTCStatsCollector::ProduceAudioRTPStreamStats_n(
                                                      attachment_id);
     }
     outbound_audio->transport_id = transport_id;
-    audio_outbound_rtps.insert(
-        std::make_pair(outbound_audio->id(), outbound_audio.get()));
-    report->AddStats(std::move(outbound_audio));
+    auto audio_outbound_pair =
+        std::make_pair(outbound_audio->id(), outbound_audio.get());
+    if (report->TryAddStats(std::move(outbound_audio))) {
+      audio_outbound_rtps.insert(std::move(audio_outbound_pair));
+    } else {
+      RTC_LOG(LS_ERROR)
+          << "Unable to add audio 'outbound-rtp' to report, ID is not unique.";
+    }
   }
   // Remote-inbound.
   // These are Report Block-based, information sent from the remote endpoint,
@@ -2031,7 +2047,10 @@ void RTCStatsCollector::ProduceVideoRTPStreamStats_n(
       inbound_video->track_identifier = video_track->id();
     }
     inbound_video->transport_id = transport_id;
-    report->AddStats(std::move(inbound_video));
+    if (!report->TryAddStats(std::move(inbound_video))) {
+      RTC_LOG(LS_ERROR)
+          << "Unable to add video 'inbound-rtp' to report, ID is not unique.";
+    }
   }
   // Outbound
   std::map<std::string, RTCOutboundRTPStreamStats*> video_outbound_rtps;
@@ -2059,9 +2078,14 @@ void RTCStatsCollector::ProduceVideoRTPStreamStats_n(
                                                      attachment_id);
     }
     outbound_video->transport_id = transport_id;
-    video_outbound_rtps.insert(
-        std::make_pair(outbound_video->id(), outbound_video.get()));
-    report->AddStats(std::move(outbound_video));
+    auto video_outbound_pair =
+        std::make_pair(outbound_video->id(), outbound_video.get());
+    if (report->TryAddStats(std::move(outbound_video))) {
+      video_outbound_rtps.insert(std::move(video_outbound_pair));
+    } else {
+      RTC_LOG(LS_ERROR)
+          << "Unable to add video 'outbound-rtp' to report, ID is not unique.";
+    }
   }
   // Remote-inbound
   // These are Report Block-based, information sent from the remote endpoint,
diff --git a/pc/rtc_stats_collector_unittest.cc b/pc/rtc_stats_collector_unittest.cc
index d3c4584555d7c467273c0f5fca9e6318f22d3b0b..61b1e1c0767e5b85f64d58134d7c46bd2e12e1f2 100644
--- a/pc/rtc_stats_collector_unittest.cc
+++ b/pc/rtc_stats_collector_unittest.cc
@@ -1011,6 +1011,82 @@ TEST_F(RTCStatsCollectorTest, CollectRTCCertificateStatsSingle) {
   ExpectReportContainsCertificateInfo(report, *remote_certinfo);
 }
 
+// These SSRC collisions are legal.
+TEST_F(RTCStatsCollectorTest, ValidSsrcCollisionDoesNotCrash) {
+  // BUNDLE audio/video inbound/outbound. Unique SSRCs needed within the BUNDLE.
+  cricket::VoiceMediaInfo mid1_info;
+  mid1_info.receivers.emplace_back();
+  mid1_info.receivers[0].add_ssrc(1);
+  mid1_info.senders.emplace_back();
+  mid1_info.senders[0].add_ssrc(2);
+  pc_->AddVoiceChannel("Mid1", "Transport1", mid1_info);
+  cricket::VideoMediaInfo mid2_info;
+  mid2_info.receivers.emplace_back();
+  mid2_info.receivers[0].add_ssrc(3);
+  mid2_info.senders.emplace_back();
+  mid2_info.senders[0].add_ssrc(4);
+  pc_->AddVideoChannel("Mid2", "Transport1", mid2_info);
+  // Now create a second BUNDLE group with SSRCs colliding with the first group
+  // (but again no collisions within the group).
+  cricket::VoiceMediaInfo mid3_info;
+  mid3_info.receivers.emplace_back();
+  mid3_info.receivers[0].add_ssrc(1);
+  mid3_info.senders.emplace_back();
+  mid3_info.senders[0].add_ssrc(2);
+  pc_->AddVoiceChannel("Mid3", "Transport2", mid3_info);
+  cricket::VideoMediaInfo mid4_info;
+  mid4_info.receivers.emplace_back();
+  mid4_info.receivers[0].add_ssrc(3);
+  mid4_info.senders.emplace_back();
+  mid4_info.senders[0].add_ssrc(4);
+  pc_->AddVideoChannel("Mid4", "Transport2", mid4_info);
+
+  // This should not crash (https://crbug.com/1361612).
+  rtc::scoped_refptr<const RTCStatsReport> report = stats_->GetStatsReport();
+  auto inbound_rtps = report->GetStatsOfType<RTCInboundRTPStreamStats>();
+  auto outbound_rtps = report->GetStatsOfType<RTCOutboundRTPStreamStats>();
+  // TODO(https://crbug.com/webrtc/14443): When valid SSRC collisions are
+  // handled correctly, we should expect to see 4 of each type of object here.
+  EXPECT_EQ(inbound_rtps.size(), 2u);
+  EXPECT_EQ(outbound_rtps.size(), 2u);
+}
+
+// These SSRC collisions are illegal, so it is not clear if this setup can
+// happen even when talking to a malicious endpoint, but simulate illegal SSRC
+// collisions just to make sure we don't crash in even the most extreme cases.
+TEST_F(RTCStatsCollectorTest, InvalidSsrcCollisionDoesNotCrash) {
+  // One SSRC to rule them all.
+  cricket::VoiceMediaInfo mid1_info;
+  mid1_info.receivers.emplace_back();
+  mid1_info.receivers[0].add_ssrc(1);
+  mid1_info.senders.emplace_back();
+  mid1_info.senders[0].add_ssrc(1);
+  pc_->AddVoiceChannel("Mid1", "BundledTransport", mid1_info);
+  cricket::VideoMediaInfo mid2_info;
+  mid2_info.receivers.emplace_back();
+  mid2_info.receivers[0].add_ssrc(1);
+  mid2_info.senders.emplace_back();
+  mid2_info.senders[0].add_ssrc(1);
+  pc_->AddVideoChannel("Mid2", "BundledTransport", mid2_info);
+  cricket::VoiceMediaInfo mid3_info;
+  mid3_info.receivers.emplace_back();
+  mid3_info.receivers[0].add_ssrc(1);
+  mid3_info.senders.emplace_back();
+  mid3_info.senders[0].add_ssrc(1);
+  pc_->AddVoiceChannel("Mid3", "BundledTransport", mid3_info);
+  cricket::VideoMediaInfo mid4_info;
+  mid4_info.receivers.emplace_back();
+  mid4_info.receivers[0].add_ssrc(1);
+  mid4_info.senders.emplace_back();
+  mid4_info.senders[0].add_ssrc(1);
+  pc_->AddVideoChannel("Mid4", "BundledTransport", mid4_info);
+
+  // This should not crash (https://crbug.com/1361612).
+  stats_->GetStatsReport();
+  // Because this setup is illegal, there is no "right answer" to how the report
+  // should look. We only care about not crashing.
+}
+
 TEST_F(RTCStatsCollectorTest, CollectRTCCodecStats) {
   // Audio
   cricket::VoiceMediaInfo voice_media_info;
diff --git a/stats/rtc_stats_report.cc b/stats/rtc_stats_report.cc
index 4fbd82508e7a2f415e12c2cc402b5630a53b1da1..187adadd7e928f45ddd727ad30d6ad6bfa81c32d 100644
--- a/stats/rtc_stats_report.cc
+++ b/stats/rtc_stats_report.cc
@@ -71,12 +71,15 @@ rtc::scoped_refptr<RTCStatsReport> RTCStatsReport::Copy() const {
 }
 
 void RTCStatsReport::AddStats(std::unique_ptr<const RTCStats> stats) {
+#if RTC_DCHECK_IS_ON
   auto result =
+#endif
       stats_.insert(std::make_pair(std::string(stats->id()), std::move(stats)));
+#if RTC_DCHECK_IS_ON
   RTC_DCHECK(result.second)
-      << "A stats object with ID " << result.first->second->id()
-      << " is already "
-         "present in this stats report.";
+      << "A stats object with ID \"" << result.first->second->id() << "\" is "
+      << "already present in this stats report.";
+#endif
 }
 
 const RTCStats* RTCStatsReport::Get(const std::string& id) const {