trust-dns-server 0.23.2

Trust-DNS is a safe and secure DNS server with DNSSEC support. Eventually this could be a replacement for BIND9. The DNSSEC support allows for live signing of all records, in it does not currently support records signed offline. The server supports dynamic DNS with SIG0 authenticated requests. Trust-DNS is based on the Tokio and Futures libraries, which means it should be easily integrated into other software that also use those libraries.
Documentation 
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// Copyright 2015-2022 Benjamin Fry <benjaminfry@me.com>
//
// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
// http://opensource.org/licenses/MIT>, at your option. This file may not be
// copied, modified, or distributed except according to those terms.

use std::{io, net::SocketAddr, sync::Arc};

use bytes::{Bytes, BytesMut};
use drain::Watch;
use futures_util::lock::Mutex;
use tracing::{debug, warn};
use trust_dns_proto::{
    error::ProtoError,
    quic::{DoqErrorCode, QuicStream},
    rr::Record,
};

use crate::{
    authority::MessageResponse,
    proto::quic::QuicStreams,
    server::{
        request_handler::RequestHandler, response_handler::ResponseHandler, server_future,
        Protocol, ResponseInfo,
    },
};

pub(crate) async fn quic_handler<T>(
    handler: Arc<T>,
    mut quic_streams: QuicStreams,
    src_addr: SocketAddr,
    _dns_hostname: Option<Arc<str>>,
    shutdown: Watch,
) -> Result<(), ProtoError>
where
    T: RequestHandler,
{
    // TODO: we should make this configurable
    let mut max_requests = 100u32;

    // Accept all inbound quic streams sent over the connection.
    loop {
        let mut request_stream = tokio::select! {
            result = quic_streams.next() => match result {
                Some(Ok(next_request)) => next_request,
                Some(Err(err)) => {
                    warn!("error accepting request {}: {}", src_addr, err);
                    return Err(err);
                }
                None => {
                    break;
                }
            },
            _ = shutdown.clone().signaled() => {
                // A graceful shutdown was initiated.
                break;
            },
        };

        let request = request_stream.receive_bytes().await?;

        debug!(
            "Received bytes {} from {src_addr} {request:?}",
            request.len()
        );
        let handler = handler.clone();
        let stream = Arc::new(Mutex::new(request_stream));
        let responder = QuicResponseHandle(stream.clone());

        handle_request(request, src_addr, handler, responder).await;

        max_requests -= 1;
        if max_requests == 0 {
            warn!("exceeded request count, shutting down quic conn: {src_addr}");
            // DOQ_NO_ERROR (0x0): No error. This is used when the connection or stream needs to be closed, but there is no error to signal.
            stream.lock().await.stop(DoqErrorCode::NoError)?;
            break;
        }
        // we'll continue handling requests from here.
    }

    Ok(())
}

async fn handle_request<T>(
    bytes: BytesMut,
    src_addr: SocketAddr,
    handler: Arc<T>,
    responder: QuicResponseHandle,
) where
    T: RequestHandler,
{
    server_future::handle_request(&bytes, src_addr, Protocol::Quic, handler, responder).await
}

#[derive(Clone)]
struct QuicResponseHandle(Arc<Mutex<QuicStream>>);

#[async_trait::async_trait]
impl ResponseHandler for QuicResponseHandle {
    // TODO: rethink this entire interface
    async fn send_response<'a>(
        &mut self,
        mut response: MessageResponse<
            '_,
            'a,
            impl Iterator<Item = &'a Record> + Send + 'a,
            impl Iterator<Item = &'a Record> + Send + 'a,
            impl Iterator<Item = &'a Record> + Send + 'a,
            impl Iterator<Item = &'a Record> + Send + 'a,
        >,
    ) -> io::Result<ResponseInfo> {
        use crate::proto::serialize::binary::BinEncoder;

        // The id should always be 0 in DoQ
        response.header_mut().set_id(0);

        let mut bytes = Vec::with_capacity(512);
        let info = {
            let mut encoder = BinEncoder::new(&mut bytes);
            response.destructive_emit(&mut encoder)?
        };
        let bytes = Bytes::from(bytes);

        debug!("sending quic response: {}", bytes.len());
        let mut lock = self.0.lock().await;
        lock.send_bytes(bytes).await?;
        lock.finish().await?;

        Ok(info)
    }
}