[WebRTC] Allow stuns server URIs

https://bugs.webkit.org/show_bug.cgi?id=279976

Reviewed by Youenn Fablet.

According to RFC 7064:

> The "stuns" URI scheme is intended to be used by applications with
> a need to identify a STUN server to be used for NAT traversal over
> a secure connection.

LibWebRTC accepts this kind of URL but doesn't seem to make a difference when connecting, as
compared to stun URIs.

Based on patch from Mikolaj Staworzynski <mikolaj.staworzynski@redembedded.com>

* LayoutTests/webrtc/stun-server-filtering.html:
* Source/WebCore/Modules/mediastream/RTCPeerConnection.cpp:
(WebCore::RTCPeerConnection::iceServersFromConfiguration):

Canonical link: https://commits.webkit.org/284082@main

Author: philn

LayoutTests/webrtc/stun-server-filtering.html

@@ -3,12 +3,13 @@
 <script src='../resources/testharnessreport.js'></script>
 <script>
 promise_test(async (test) => {
-    let pc = new RTCPeerConnection({iceServers:[{urls:['stun:foo.com', 'stun:blabla.local']}]});
+    let pc = new RTCPeerConnection({iceServers:[{urls:['stun:foo.com', 'stun:blabla.local', 'stuns:bar.com']}]});
     let promise = new Promise(resolve => pc.onicecandidateerror = resolve);
     let configuration = pc.getConfiguration();
 
-    assert_equals(configuration.iceServers[0].urls.length, 1);
+    assert_equals(configuration.iceServers[0].urls.length, 2);
     assert_equals(configuration.iceServers[0].urls[0], 'stun:foo.com');
+    assert_equals(configuration.iceServers[0].urls[1], 'stuns:bar.com');
 
     const event = await promise;
     assert_equals(event.url, 'stun:blabla.local');

Source/WebCore/Modules/mediastream/RTCPeerConnection.cpp

@@ -495,7 +495,7 @@ ExceptionOr<Vector<MediaEndpointConfiguration::IceServerInfo>> RTCPeerConnection
                         if (server.credential.utf8().length() > MaxTurnUsernameLength || server.username.utf8().length() > MaxTurnUsernameLength)
                             return Exception { TypeError, "TURN/TURNS username and/or credential are too long"_s };
                     }
-                } else if (!serverURL.protocolIs("stun"_s))
+                } else if (!serverURL.protocolIs("stun"_s) && !serverURL.protocolIs("stuns"_s))
                     return Exception { NotSupportedError, "ICE server protocol not supported"_s };
             }
             if (serverURLs.size())