Correctly generate SSRC for RTPSender

Author: mickel8

lib/ex_webrtc/peer_connection.ex

@@ -7,6 +7,8 @@ defmodule ExWebRTC.PeerConnection do
 
   require Logger
 
+  import Bitwise
+
   alias __MODULE__.{Configuration, Demuxer}
 
   alias ExWebRTC.{
@@ -777,5 +779,17 @@ defmodule ExWebRTC.PeerConnection do
     %{state | conn_state: new_conn_state}
   end
 
+  defp generate_ssrc(demuxer, rtp_senders) do
+    rtp_sender_ssrcs = Enum.map(rtp_senders, & &1.ssrc)
+    ssrcs = Map.keys(demuxer.ssrc_to_mid) ++ rtp_sender_ssrcs
+    # TODO handle case when all ssrcs are taken
+    do_generate_ssrc(ssrcs) 
+  end
+
+  defp do_generate_ssrc(ssrcs) do
+    ssrc = Enum.random(0..((1<<<32) - 1))
+    if ssrc in ssrcs, do: do_generate_ssrc(ssrcs), else: ssrc
+  end
+
   defp notify(pid, msg), do: send(pid, {:ex_webrtc, self(), msg})
 end