commit a2f5d45b81c6ae5632af0c4c45e8988f330af7f1
author Philipp Hancke <phancke@microsoft.com> Mon Dec 19 10:04:06 2022
committer WebRTC LUCI CQ <webrtc-scoped@luci-project-accounts.iam.gserviceaccount.com> Mon Dec 19 15:19:35 2022
tree c5a4c8d8070c0b9811c9e0bb367c93aa88ff879a
parent 91b62e0e8fd1788c1964403ed34160c47190aad0

Reland "sdp: measure rtp header extension collisions"

This is a reland of commit 6c27d56a2aeb2cff10a216d714552f4970d99d32
avoiding the Fuchsia/C++17 compilation issues.

Original change's description:
> sdp: measure rtp header extension collisions
>
> since extension ids are required to be unique in a BUNDLE group:
>   https://www.rfc-editor.org/rfc/rfc8843#name-rtp-header-extensions-consi
>
> Measure how much enforcing this would break in UMA first.
>
> BUG=webrtc:14782
>
> Change-Id: Ieaf7a436feea677032499e11ca14973eebda322e
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/288362
> Reviewed-by: Harald Alvestrand <hta@webrtc.org>
> Commit-Queue: Philipp Hancke <phancke@microsoft.com>
> Reviewed-by: Johannes Kron <kron@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#38914}

Bug: webrtc:14782
Change-Id: If9449b0381ebe33ba30eff0d733a1f3c94470d5d
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/288383
Reviewed-by: Johannes Kron <kron@webrtc.org>
Commit-Queue: Philipp Hancke <phancke@microsoft.com>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#38919}

pc/sdp_offer_answer.cc

diff --git a/pc/sdp_offer_answer.cc b/pc/sdp_offer_answer.cc
index 84a0756..ade3be7 100644
--- a/pc/sdp_offer_answer.cc
+++ b/pc/sdp_offer_answer.cc
@@ -491,6 +491,53 @@
   return RTCError::OK();
 }
 
+RTCError FindDuplicateHeaderExtensionIds(
+    const RtpExtension extension,
+    std::map<int, RtpExtension>& id_to_extension) {
+  auto existing_extension = id_to_extension.find(extension.id);
+  if (existing_extension != id_to_extension.end() &&
+      !(extension.uri == existing_extension->second.uri &&
+        extension.encrypt == existing_extension->second.encrypt)) {
+    return RTCError(
+        RTCErrorType::INVALID_PARAMETER,
+        "A BUNDLE group contains a codec collision for "
+        "header extension id='" +
+            rtc::ToString(extension.id) +
+            ". The id must be the same across all bundled media descriptions");
+  }
+  id_to_extension.insert(std::make_pair(extension.id, extension));
+  return RTCError::OK();
+}
+
+RTCError ValidateBundledRtpHeaderExtensions(
+    const cricket::SessionDescription& description) {
+  // https://www.rfc-editor.org/rfc/rfc8843#name-rtp-header-extensions-consi
+  // ... the identifier used for a given extension MUST identify the same
+  // extension across all the bundled media descriptions.
+  std::vector<const cricket::ContentGroup*> bundle_groups =
+      description.GetGroupsByName(cricket::GROUP_TYPE_BUNDLE);
+  for (const cricket::ContentGroup* bundle_group : bundle_groups) {
+    std::map<int, RtpExtension> id_to_extension;
+    for (const std::string& content_name : bundle_group->content_names()) {
+      const cricket::MediaContentDescription* media_description =
+          description.GetContentDescriptionByName(content_name);
+      if (!media_description) {
+        return RTCError(RTCErrorType::INVALID_PARAMETER,
+                        "A BUNDLE group contains a MID='" + content_name +
+                            "' matching no m= section.");
+      }
+      for (const auto& extension : media_description->rtp_header_extensions()) {
+        auto error =
+            FindDuplicateHeaderExtensionIds(extension, id_to_extension);
+        if (!error.ok()) {
+          return error;
+        }
+      }
+    }
+  }
+  return RTCError::OK();
+}
+
 bool IsValidOfferToReceiveMedia(int value) {
   typedef PeerConnectionInterface::RTCOfferAnswerOptions Options;
   return (value >= Options::kUndefined) &&
@@ -3371,12 +3418,18 @@
     return RTCError(RTCErrorType::INVALID_PARAMETER, kSdpWithoutIceUfragPwd);
   }
 
-  // Validate bundle, payload types and that there are no collisions.
+  // Validate that there are no collisions of bundled payload types.
   error = ValidateBundledPayloadTypes(*sdesc->description());
   // TODO(bugs.webrtc.org/14420): actually reject.
   RTC_HISTOGRAM_BOOLEAN("WebRTC.PeerConnection.ValidBundledPayloadTypes",
                         error.ok());
 
+  // Validate that there are no collisions of bundled header extensions ids.
+  error = ValidateBundledRtpHeaderExtensions(*sdesc->description());
+  // TODO(bugs.webrtc.org/14782): actually reject.
+  RTC_HISTOGRAM_BOOLEAN("WebRTC.PeerConnection.ValidBundledExtensionIds",
+                        error.ok());
+
   if (!pc_->ValidateBundleSettings(sdesc->description(),
                                    bundle_groups_by_mid)) {
     return RTCError(RTCErrorType::INVALID_PARAMETER, kBundleWithoutRtcpMux);