peer connection state not become connected while ice_connection_state and dtls_transport_state are all connected

[lfld287]

log:

webrtc-0.12.0\src\peer_connection\mod.rs:307 [INFO] 15:52:34.581448 - signaling state changed to have-local-offer
webrtc-ice-0.12.0\src\agent\agent_gather.rs:801 [WARN] 15:52:34.582244 - [controlled]: Unable to handle URL in gather_candidates_relay turn:172.31.2.27:3478?transport=tcp      
webrtc-0.12.0\src\peer_connection\mod.rs:307 [INFO] 15:52:34.658150 - signaling state changed to stable
webrtc-ice-0.12.0\src\agent\agent_internal.rs:312 [INFO] 15:52:34.659318 - [controlling]: Setting new connection state: Checking
webrtc-ice-0.12.0\src\agent\agent_internal.rs:374 [WARN] 15:52:34.659596 - [controlling]: pingAllCandidates called with no candidate pairs. Connection is not possible yet.     
webrtc-0.12.0\src\peer_connection\mod.rs:629 [INFO] 15:52:34.659593 - ICE connection state changed: checking
tests\offer_peer_test.rs:196 [INFO] 15:52:34.659863 - ICE connection state: Checking
webrtc-0.12.0\src\peer_connection\mod.rs:888 [INFO] 15:52:34.659959 - update_connection_state: ice=checking, dtls=new
webrtc-0.12.0\src\peer_connection\mod.rs:927 [INFO] 15:52:34.660055 - peer connection state changed: connecting
tests\offer_peer_test.rs:185 [INFO] 15:52:34.660165 - Peer connection state: Connecting
webrtc-ice-0.12.0\src\agent\agent_internal.rs:312 [INFO] 15:52:34.677261 - [controlling]: Setting new connection state: Connected
webrtc-0.12.0\src\peer_connection\mod.rs:629 [INFO] 15:52:34.677425 - ICE connection state changed: connected
tests\offer_peer_test.rs:206 [INFO] 15:52:34.677566 - DTLS transport state: Connecting
tests\offer_peer_test.rs:196 [INFO] 15:52:34.677883 - ICE connection state: Connected
webrtc-0.12.0\src\peer_connection\mod.rs:888 [INFO] 15:52:34.678245 - update_connection_state: ice=connected, dtls=connecting
tests\offer_peer_test.rs:206 [INFO] 15:52:34.686419 - DTLS transport state: Connected

test code:

#[tokio::test(flavor = "multi_thread")]
async fn test_pure_offer_peer() {
    //init env logger
    env_logger::Builder::new()
        .format(|buf, record| {
            writeln!(
                buf,
                "{}:{} [{}] {} - {}",
                record.file().unwrap_or("unknown").trim_start_matches("D:\\runtime\\rust_cargo\\registry\\src\\index.crates.io-6f17d22bba15001f\\"),
                record.line().unwrap_or(0),
                record.level(),
                chrono::Local::now().format("%H:%M:%S.%6f"),
                record.args()
            )
        })
        .filter(None, log::LevelFilter::Info)
        .init();

    let ctx = Context::new(None);
    let server_url = "my_test_signaling_server"; 
    let client_id = "remote_peer_id"; 
    let bitrate = 3000000;
    let frame_rate = 30;
    let i_frame_interval = 3;

    let room_id = create_room(&ctx, server_url).await.unwrap();

    let ice_servers = get_ice_servers(&ctx, server_url, "test").await.unwrap();

    let wrtc_api = create_api(Default::default()).unwrap();
    let mut config = RTCConfiguration::default();
    config.ice_transport_policy = RTCIceTransportPolicy::Relay;
    config.ice_servers = ice_servers;

    let pc = wrtc_api.new_peer_connection(config).await.unwrap();

    let pc = Arc::new(pc);

    let offer_handshake_handler = OfferHandshakeHandler::new(
        DiscardLogger {},
        pc.clone(),
        Arc::new(server_url.to_string()),
        room_id,
    );

    pc.on_ice_candidate({
        let handler = offer_handshake_handler.clone();
        Box::new(move |candidate| {
            let handler = handler.clone();
            Box::pin(async move {
                if let Some(candidate) = candidate {
                    match candidate.to_json() {
                        Ok(candidate_init) => {
                            handler.on_ice_candidate(candidate_init).await;
                        }
                        Err(_err) => {
                            //todo log
                        }
                    }
                }
            })
        })
    });

    pc.on_peer_connection_state_change({
        let handler = offer_handshake_handler.clone();
        Box::new(move |state| {
            Box::pin({
                let handler = handler.clone();
                async move {
                    log::info!("Peer connection state: {:?}", state);
                    handler.on_state(state).await;
                }
            })
        })
    });

    pc.on_ice_connection_state_change({
        Box::new(move |state| {
            Box::pin({
                async move {
                    log::info!("ICE connection state: {:?}", state);
                }
            })
        })
    });

    pc.dtls_transport().on_state_change({
        Box::new(move |state| {
            Box::pin({
                async move {
                    log::info!("DTLS transport state: {:?}", state);
                }
            })
        })
    });

    pc.add_transceiver_from_kind(Video, None).await.unwrap();
    pc.add_transceiver_from_kind(Audio, None).await.unwrap();

    let offer = pc.create_offer(None).await.unwrap();

    pc.set_local_description(offer.clone()).await.unwrap();

    let offer_str: String = serde_json::to_string(&offer).unwrap();

    let answer_str = send_offer_for_answer(
        &ctx,
        server_url,
        client_id,
        room_id,
        &offer_str,
        1280,
        bitrate,
        frame_rate,
        i_frame_interval,
    )
        .await
        .unwrap();

    let answer: RTCSessionDescription = serde_json::from_str(&answer_str).unwrap();

    pc.set_remote_description(answer).await.unwrap();

    tokio::time::sleep(tokio::time::Duration::from_secs(40)).await;
}

(remote peer can work with chrome and pion)

[lfld287]

after some debug, I find out it stuck at start_srtp()

[lfld287]

after some more debug , I found out it stuck at webrtc-srtp\src\Context\mod.rs Context::new()

[lfld287]

Add code from #649 (comment) solved the problem, no idea what's happening