Support encrypted RTP extensions (RFC 6904)

webrtc/config.cc

Index: webrtc/config.cc
diff --git a/webrtc/config.cc b/webrtc/config.cc
index e0c490d1ecd8038d546b7298fc9a885ab02718df..07cf0767c84980a5429a969bce1a3b9eb6234f5b 100644
--- a/webrtc/config.cc
+++ b/webrtc/config.cc
@@ -41,6 +41,9 @@ std::string RtpExtension::ToString() const {
   std::stringstream ss;
   ss << "{uri: " << uri;
   ss << ", id: " << id;
+  if (encrypt) {
+    ss << ", encrypt";
+  }
   ss << '}';
   return ss.str();
 }
@@ -72,6 +75,9 @@ const char* RtpExtension::kPlayoutDelayUri =
     "http://www.webrtc.org/experiments/rtp-hdrext/playout-delay";
 const int RtpExtension::kPlayoutDelayDefaultId = 6;
 
+const char* RtpExtension::kEncryptHeaderExtensionsUri =
+    "urn:ietf:params:rtp-hdrext:encrypt";
+
 const int RtpExtension::kMinId = 1;
 const int RtpExtension::kMaxId = 14;
 
@@ -88,6 +94,62 @@ bool RtpExtension::IsSupportedForVideo(const std::string& uri) {
          uri == webrtc::RtpExtension::kPlayoutDelayUri;
 }
 
+bool RtpExtension::IsEncryptionSupported(const std::string& uri) {
+  // TODO(jbauch): Figure out a way to add "kTimestampOffsetUri" here
+  // and filter out later if external auth is used in srtpfilter.

[Taylor Brandstetter, 2017/04/19 06:48:39]

Does this TODO need to be addressed before landing?

[joachim, 2017/04/19 23:40:19]

Just noticed it should have been "kAbsSendTimeUri" in the comment. Only applies
if "ENABLE_EXTERNAL_AUTH" is defined, so I updated the code and comment
accordingly.

+  return uri == webrtc::RtpExtension::kAudioLevelUri ||
+         uri == webrtc::RtpExtension::kTimestampOffsetUri ||
+         uri == webrtc::RtpExtension::kVideoRotationUri ||
+         uri == webrtc::RtpExtension::kTransportSequenceNumberUri ||
+         uri == webrtc::RtpExtension::kPlayoutDelayUri;
+}
+
+const RtpExtension* RtpExtension::FindHeaderExtensionByUri(
+    const std::vector<RtpExtension>& extensions,
+    const std::string& uri) {
+  for (const auto& extension : extensions) {
+    if (extension.uri == uri) {
+      return &extension;
+    }
+  }
+  return nullptr;
+}
+
+std::vector<RtpExtension> RtpExtension::FilterDuplicateNonEncrypted(
+    const std::vector<RtpExtension>& extensions) {
+  std::vector<RtpExtension> filtered;
+  for (auto it = extensions.begin(); it != extensions.end(); ++it) {
+    if (it->encrypt) {
+      filtered.push_back(*it);
+    } else {
+      // Only add non-encrypted extension if no encrypted with the same URI
+      // is also present...
+      bool found = false;
+      for (auto it2 = it + 1; it2 != extensions.end(); ++it2) {
+        if (it->uri == it2->uri) {
+          found = true;
+          break;
+        }
+      }
+
+      if (!found) {
+        // ...and has not been added before.
+        for (const RtpExtension& existing : filtered) {
+          if (it->uri == existing.uri) {
+            found = true;
+            break;
+          }
+        }
+
+        if (!found) {
+          filtered.push_back(*it);
+        }
+      }
+    }
+  }
+  return filtered;
+}
+
 VideoStream::VideoStream()
     : width(0),
       height(0),