UDP Socket

[isaac-asdf]

I'm trying to create a udp socket so that I can request the current time from an NTP time server on an esp-32. Is there an example of how to construct a udp socket? I have been struggling with setting up the rx_meta: &'a mut [smoltcp::socket::udp::PacketMetadata] input variable for this:

    // get udp socket for ntp time stamps
    let rx_meta = PacketMetadata::from(endpoint);
    let mut udp_rx_meta = [rx_meta];
    let mut udp_tx_meta = todo!();
    let mut udp_rx_buffer = [0u8; 1536];
    let mut udp_tx_buffer = [0u8; 1536];
    let udp_socket = wifi_stack.get_udp_socket(
        &mut udp_rx_meta,
        &mut udp_rx_buffer,
        &mut udp_tx_meta,
        &mut udp_tx_buffer,
    );

[bjoernQ]

Maybe this might help:

https://github.com/bjoernQ/matter-rs-experiment/blob/8be0e5546b6e79565f17cb7f62c29c796ba4f867/src/main.rs#L184

[isaac-asdf]

Very helpful, thanks. I'm able to compile and run, but I'm getting an error when receiving, UdpRecvError(Exhausted) - any idea what would cause this? I tried playing with the buffer size but can't get that error to go away. It looks like in your example you are always using an if let so you can set a default to 0 - is there a specific reason for that?

[bjoernQ]

The underlying implementation (smoltcp) returns Exhausted when trying to read from an UdpSocket and there is no data to read. Our implementation just pipes that error through.

So, it's not really a serious error but just an indication that currently there is no data available - so you probably need a similar if let to handle this error appropriately

[isaac-asdf]

That make sense, thanks for the help