Update config on receiving remote SDP

Author: mickel8

test/ex_webrtc/peer_connection_test.exs

@@ -3,6 +3,8 @@ defmodule ExWebRTC.PeerConnectionTest do
 
   alias ExWebRTC.{MediaStreamTrack, PeerConnection, SessionDescription, SDPUtils, Utils}
 
+  alias ExSDP.Attribute.Extmap
+
   {_pkey, cert} = ExDTLS.generate_key_cert()
 
   @fingerprint cert
@@ -355,4 +357,43 @@ defmodule ExWebRTC.PeerConnectionTest do
 
     assert_receive {:ex_webrtc, ^pc2, {:rtp, ^id2, %ExRTP.Packet{payload: ^payload}}}
   end
+
+  test "updates rtp header extension ids" do
+    # check wheter we update our RTP header extension ids
+    # when we receive a remote offer with different ones
+    {:ok, pc1} = PeerConnection.start_link()
+    {:ok, _} = PeerConnection.add_transceiver(pc1, :audio)
+    {:ok, offer} = PeerConnection.create_offer(pc1)
+
+    sdp = ExSDP.parse!(offer.sdp)
+
+    # munge Extmap so that we use different id
+    [mline] = sdp.media
+
+    extmaps =
+      mline
+      |> ExSDP.get_attributes(Extmap)
+      |> Enum.map(fn extmap -> %{extmap | id: extmap.id + 1} end)
+
+    mline =
+      mline
+      |> SDPUtils.delete_attribute(Extmap)
+      |> ExSDP.add_attributes(extmaps)
+
+    sdp = %{sdp | media: [mline]}
+
+    offer = %SessionDescription{type: :offer, sdp: to_string(sdp)}
+
+    {:ok, pc2} = PeerConnection.start_link()
+    :ok = PeerConnection.set_remote_description(pc2, offer)
+    {:ok, answer} = PeerConnection.create_answer(pc2)
+    :ok = PeerConnection.set_local_description(pc2, answer)
+
+    {:ok, _} = PeerConnection.add_transceiver(pc2, :audio)
+    {:ok, offer} = PeerConnection.create_offer(pc2)
+
+    [audio1, audio2] = ExSDP.parse!(offer.sdp).media
+
+    assert ExSDP.get_attributes(audio1, Extmap) == ExSDP.get_attributes(audio2, Extmap)
+  end
 end