1 files changed, 153 insertions, 0 deletions
diff --git a/dom/media/webrtc/transportbridge/MediaPipelineFilter.cpp b/dom/media/webrtc/transportbridge/MediaPipelineFilter.cpp
new file mode 100644
index 0000000000..1acb73e9f2
--- /dev/null
+++ b/dom/media/webrtc/transportbridge/MediaPipelineFilter.cpp
@@ -0,0 +1,153 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: softtabstop=2:shiftwidth=2:expandtab
+ * */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Original author: bcampen@mozilla.com
+
+#include "MediaPipelineFilter.h"
+
+#include "api/rtp_headers.h"
+#include "api/rtp_parameters.h"
+#include "mozilla/Logging.h"
+
+// defined in MediaPipeline.cpp
+extern mozilla::LazyLogModule gMediaPipelineLog;
+
+#define DEBUG_LOG(x) MOZ_LOG(gMediaPipelineLog, LogLevel::Debug, x)
+
+namespace mozilla {
+MediaPipelineFilter::MediaPipelineFilter(
+    const std::vector<webrtc::RtpExtension>& aExtMap)
+    : mExtMap(aExtMap) {}
+
+void MediaPipelineFilter::SetRemoteMediaStreamId(
+    const Maybe<std::string>& aMid) {
+  if (aMid != mRemoteMid) {
+    DEBUG_LOG(("MediaPipelineFilter added new remote RTP MID: '%s'.",
+               aMid.valueOr("").c_str()));
+    mRemoteMid = aMid;
+    mRemoteMidBindings.clear();
+  }
+}
+
+bool MediaPipelineFilter::Filter(const webrtc::RTPHeader& header) {
+  DEBUG_LOG(("MediaPipelineFilter inspecting seq# %u SSRC: %u",
+             header.sequenceNumber, header.ssrc));
+
+  auto fromStreamId = [](const std::string& aId) {
+    return Maybe<std::string>(aId.empty() ? Nothing() : Some(aId));
+  };
+
+  //
+  //  MID Based Filtering
+  //
+
+  const auto mid = fromStreamId(header.extension.mid);
+
+  // Check to see if a bound SSRC is moved to a new MID
+  if (mRemoteMidBindings.count(header.ssrc) == 1 && mid && mRemoteMid != mid) {
+    mRemoteMidBindings.erase(header.ssrc);
+  }
+  // Bind an SSRC if a matching MID is found
+  if (mid && mRemoteMid == mid) {
+    DEBUG_LOG(("MediaPipelineFilter learned SSRC: %u for MID: '%s'",
+               header.ssrc, mRemoteMid.value().c_str()));
+    mRemoteMidBindings.insert(header.ssrc);
+  }
+  // Check for matching MID
+  if (!mRemoteMidBindings.empty()) {
+    MOZ_ASSERT(mRemoteMid != Nothing());
+    if (mRemoteMidBindings.count(header.ssrc) == 1) {
+      DEBUG_LOG(
+          ("MediaPipelineFilter SSRC: %u matched for MID: '%s'."
+           " passing packet",
+           header.ssrc, mRemoteMid.value().c_str()));
+      return true;
+    }
+    DEBUG_LOG(
+        ("MediaPipelineFilter SSRC: %u did not match bound SSRC(s) for"
+         " MID: '%s'. ignoring packet",
+         header.ssrc, mRemoteMid.value().c_str()));
+    for (const uint32_t ssrc : mRemoteMidBindings) {
+      DEBUG_LOG(("MID %s is associated with SSRC: %u",
+                 mRemoteMid.value().c_str(), ssrc));
+    }
+    return false;
+  }
+
+  //
+  // RTP-STREAM-ID based filtering (for tests only)
+  //
+
+  //
+  // Remote SSRC based filtering
+  //
+
+  if (remote_ssrc_set_.count(header.ssrc)) {
+    DEBUG_LOG(
+        ("MediaPipelineFilter SSRC: %u matched remote SSRC set."
+         " passing packet",
+         header.ssrc));
+    return true;
+  }
+  DEBUG_LOG(
+      ("MediaPipelineFilter SSRC: %u did not match any of %zu"
+       " remote SSRCS.",
+       header.ssrc, remote_ssrc_set_.size()));
+
+  //
+  // PT, payload type, last ditch effort filtering
+  //
+
+  if (payload_type_set_.count(header.payloadType)) {
+    DEBUG_LOG(
+        ("MediaPipelineFilter payload-type: %u matched %zu"
+         " unique payload type. learning ssrc. passing packet",
+         header.ssrc, remote_ssrc_set_.size()));
+    // Actual match. We need to update the ssrc map so we can route rtcp
+    // sender reports correctly (these use a different payload-type field)
+    AddRemoteSSRC(header.ssrc);
+    return true;
+  }
+  DEBUG_LOG(
+      ("MediaPipelineFilter payload-type: %u did not match any of %zu"
+       " unique payload-types.",
+       header.payloadType, payload_type_set_.size()));
+  DEBUG_LOG(
+      ("MediaPipelineFilter packet failed to match any criteria."
+       " ignoring packet"));
+  return false;
+}
+
+void MediaPipelineFilter::AddRemoteSSRC(uint32_t ssrc) {
+  remote_ssrc_set_.insert(ssrc);
+}
+
+void MediaPipelineFilter::AddUniquePT(uint8_t payload_type) {
+  payload_type_set_.insert(payload_type);
+}
+
+void MediaPipelineFilter::Update(const MediaPipelineFilter& filter_update) {
+  // We will not stomp the remote_ssrc_set_ if the update has no ssrcs,
+  // because we don't want to unlearn any remote ssrcs unless the other end
+  // has explicitly given us a new set.
+  if (!filter_update.remote_ssrc_set_.empty()) {
+    remote_ssrc_set_ = filter_update.remote_ssrc_set_;
+  }
+  // We don't want to overwrite the learned binding unless we have changed MIDs
+  // or the update contains a MID binding.
+  if (!filter_update.mRemoteMidBindings.empty() ||
+      (filter_update.mRemoteMid && filter_update.mRemoteMid != mRemoteMid)) {
+    mRemoteMid = filter_update.mRemoteMid;
+    mRemoteMidBindings = filter_update.mRemoteMidBindings;
+  }
+  payload_type_set_ = filter_update.payload_type_set_;
+
+  // Use extmapping from new filter
+  mExtMap = filter_update.mExtMap;
+}
+
+}  // end namespace mozilla