wip

Author: mickel8

lib/ex_webrtc/sdp_utils.ex

@@ -1,6 +1,7 @@
 defmodule ExWebRTC.SDPUtils do
   @moduledoc false
 
+  alias ExWebRTC.SDPUtils
   alias ExRTP.Packet.Extension
   alias ExSDP.Attribute.Extmap
 
@@ -44,9 +45,13 @@ defmodule ExWebRTC.SDPUtils do
 
     mline_mids =
       Enum.map(sdp.media, fn media ->
-        {:mid, mid} = ExSDP.get_attribute(media, :mid)
-        mid
+        # rejected m-lines are not included in the BUNDLE group
+        unless SDPUtils.rejected?(media) do
+          {:mid, mid} = ExSDP.get_attribute(media, :mid)
+          mid
+        end
       end)
+      |> Enum.reject(&(&1 == nil))
 
     case filter_groups(groups, "BUNDLE") do
       [%ExSDP.Attribute.Group{semantics: "BUNDLE", mids: group_mids}] ->
@@ -129,9 +134,21 @@ defmodule ExWebRTC.SDPUtils do
 
   @spec add_ice_candidates(ExSDP.t(), [String.t()]) :: ExSDP.t()
   def add_ice_candidates(sdp, candidates) do
+    # we only add candidates to the first mline
+    # as we don't support bundle-policies other than "max-bundle"
     candidates = Enum.map(candidates, &{"candidate", &1})
-    media = Enum.map(sdp.media, &ExSDP.add_attributes(&1, candidates))
-    %ExSDP{sdp | media: media}
+
+    if sdp.media != [] do
+      mline =
+        sdp.media
+        |> List.first()
+        |> ExSDP.add_attribute(candidates)
+
+      media = List.replace_at(sdp.media, 0, mline)
+      %ExSDP{sdp | media: media}
+    else
+      sdp
+    end
   end
 
   @spec get_dtls_role(ExSDP.t()) ::
@@ -284,7 +301,13 @@ defmodule ExWebRTC.SDPUtils do
   end
 
   @spec rejected?(ExSDP.Media.t()) :: boolean()
-  def rejected?(%ExSDP.Media{port: 0}), do: true
+  def rejected?(%ExSDP.Media{port: 0} = media) do
+    # An m-line is only rejected when the port is set to 0,
+    # and there is no `bundle-only` attribute.
+    # See RFC 8843, sec. 6.
+    "bundle-only" not in media.attributes
+  end
+
   def rejected?(%ExSDP.Media{}), do: false
 
   defp do_get_ice_credentials(sdp_or_mline) do

test/ex_webrtc/peer_connection_test.exs

@@ -276,7 +276,12 @@ defmodule ExWebRTC.PeerConnectionTest do
     test "BUNDLE group" do
       {:ok, pc} = PeerConnection.start_link()
 
-      sdp = ExSDP.add_media(ExSDP.new(), [@audio_mline, @video_mline])
+      rejected_mline =
+        %ExSDP.Media{@audio_mline | port: 0}
+        |> ExSDP.delete_attribute(:mid)
+        |> ExSDP.add_attribute({:mid, "2"})
+
+      sdp = ExSDP.add_media(ExSDP.new(), [@audio_mline, @video_mline, rejected_mline])
 
       [
         {[], {:error, :missing_bundle_group}},

test/ex_webrtc/sdp_utils_test.exs

@@ -9,5 +9,11 @@ defmodule ExWebRTC.SDPUtilsTest do
 
     mline = ExSDP.Media.new(:audio, 9, "UDP/TLS/RTP/SAVPF", [8])
     assert false == SDPUtils.rejected?(mline)
+
+    mline =
+      ExSDP.Media.new(:audio, 0, "UDP/TLS/RTP/SAVPF", [8])
+      |> ExSDP.add_attribute("bundle-only")
+
+    assert false == SDPUtils.rejected?(mline)
   end
 end