Segfault on gstreamer_sdp::SDPMessage::parse_buffer

[maxmcd]

Example code:

let ret = gstreamer_sdp::SDPMessage::parse_buffer(b"t=0 0\r\n").unwrap();

Valgrind output:

==5178== Invalid read of size 4
==5178==    at 0x58E94D9: gst_sdp_message_emails_len (gstsdpmessage.c:897)
==5178==    by 0x58ED356: gst_sdp_message_as_text (gstsdpmessage.c:499)
==5178==    by 0x2D2920: gstreamer_sdp::sdp_message::SDPMessage::as_text (sdp_message.rs:134)
==5178==    by 0x19A9CA: <gst_rust::WsClient as ws::handler::Handler>::on_message (main.rs:239)
==5178==    by 0x146C75: <ws::connection::Connection<H>>::read_frames (connection.rs:658)
==5178==    by 0x150020: <ws::connection::Connection<H>>::read (connection.rs:602)
==5178==    by 0x16BECB: <ws::io::Handler<F>>::handle_event (io.rs:548)
==5178==    by 0x169A46: <ws::io::Handler<F>>::event_loop (io.rs:429)
==5178==    by 0x175502: <ws::io::Handler<F>>::run (io.rs:396)
==5178==    by 0x120042: <ws::WebSocket<F>>::run (lib.rs:331)
==5178==    by 0x11FC73: ws::connect (lib.rs:121)
==5178==    by 0x19ACA3: gst_rust::connect_to_websocket_server_async (main.rs:264)
==5178==  Address 0x8 is not stack'd, malloc'd or (recently) free'd

Digging into this a little bit more now, but hoping I might be missing something obvious.

I simplified the buffer value to hopefully provide a more concise failure example, but it also segfaults with a full SDP offer.

[maxmcd]

This works for me:

fn gst_sdp_message_parse_buffer(data: &[u8]) -> gstreamer_sdp::SDPMessage {
    unsafe {
        let mut sdp = mem::zeroed();
        gstreamer_sdp_sys::gst_sdp_message_new(&mut sdp);
        gstreamer_sdp_sys::gst_sdp_message_parse_buffer(
            data.to_glib_none().0 as *mut u8,
            data.len() as u32,
            sdp,
        );
        from_glib_full(sdp)
    }
}

[sdroege]

Good catch! A call to gst_sdp_message_init is needed here after the allocation, or as you do simply calling gst_sdp_message_new which does the same.
Exactly the same problem in parse_uri

Do you want to send a PR?

[maxmcd]

Yep!

On a somewhat related topic. SdpMessage isn't easily extractable from a WebRTCSessionDescription, I've had to resort too:

fn sdp_message_as_text(offer: gstreamer_webrtc::WebRTCSessionDescription) -> Option<String> {
    unsafe {
        from_glib_full(gstreamer_sdp_sys::gst_sdp_message_as_text(
            (*offer.to_glib_none().0).sdp,
        ))
    }
}

Should sdp be available as an attribute?

[sdroege]

Yes, there should be a getter for taking it from the struct field. I expect that there are more things missing for the webrtc and sdp library as nobody wrote an application with those in Rust yet, but all of them should be trivial to fix.

[sdroege]

There should also be a getter for the type field btw

[maxmcd]

Cool will likely tackle those in the coming days/weeks. Thanks for the help!

[sdroege]

Let me know if you need some help or have any questions, I'd be happy to help with all this :)

[maxmcd]

Absolutely! :)