DNSSEC resolver initialization

Signed-off-by: Luca Fulchir <luca.fulchir@runesauth.com>

Cargo.toml

@@ -23,12 +23,16 @@ publish = false
 crate_type = [ "lib", "cdylib", "staticlib" ]
 
 [dependencies]
+# please keep these in alphabetical order
 
+futures = { version = "^0.3" }
 thiserror = { version = "^1.0" }
 tokio = { version = "^1", features = ["full"] }
 # PERF: todo linux-only, behind "iouring" feature
 #tokio-uring = { version = "^0.4" }
 tracing = { version = "^0.1" }
+trust-dns-client = { version = "^0.22" }
+trust-dns-proto = { version = "^0.22" }
 
 [profile.dev]
 

src/config/mod.rs

@@ -1,7 +1,12 @@
 //!
 //! Configuration to initialize the Fenrir networking library
 
-use ::std::{net::SocketAddr, num::NonZeroUsize, option::Option, vec::Vec};
+use ::std::{
+    net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr},
+    num::NonZeroUsize,
+    option::Option,
+    vec,
+};
 
 /// Main config for libFenrir
 #[derive(Clone, Debug)]
@@ -11,13 +16,24 @@ pub struct Config {
     /// List of ipv4 or ipv6 UDP inet socket to listen on
     /// If empty, libFenrir will listen on a random UDP port on `0.0.0.0`
     pub listen: Vec<SocketAddr>,
+    /// List of DNS resolvers to use
+    pub resolvers: Vec<SocketAddr>,
 }
 
 impl Default for Config {
     fn default() -> Self {
         Config {
             threads: None,
-            listen: Vec::new(),
+            listen: vec![
+                // ipv4 random port
+                SocketAddr::new(IpAddr::V4(Ipv4Addr::new(0, 0, 0, 0)), 0),
+                // ipv6 random port
+                SocketAddr::new(
+                    IpAddr::V6(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 0)),
+                    0,
+                ),
+            ],
+            resolvers: Vec::new(),
         }
     }
 }

src/lib.rs

@@ -13,12 +13,11 @@
 //!
 //! libFenrir is the official rust library implementing the Fenrir protocol
 
-use ::std::{
-    io::Result,
-    net::{IpAddr, Ipv4Addr, SocketAddr},
+use ::std::{io::Result, net::SocketAddr, result, sync::Arc};
+use ::tokio::{net::UdpSocket, runtime, task::JoinHandle};
+use trust_dns_client::client::{
+    AsyncClient as DnssecClient, ClientHandle as DnssecHandle,
 };
-use ::tokio::{net::UdpSocket, runtime};
-use ::tracing::error;
 
 mod config;
 pub use config::Config;
@@ -30,20 +29,28 @@ pub struct Fenrir {
     cfg: Config,
     /// internal runtime
     rt: ::tokio::runtime::Runtime,
+    /// listening udp sockets
+    sockets: Vec<(Arc<UdpSocket>, JoinHandle<Result<()>>)>,
+    /// DNSSEC resolvers. multiple for failover
+    resolvers: Vec<(
+        DnssecClient,
+        JoinHandle<result::Result<(), ::trust_dns_proto::error::ProtoError>>,
+    )>,
+    /// Broadcast channel to tell workers to stop working
+    stop_working: ::tokio::sync::broadcast::Sender<bool>,
 }
 
-/// Initialize a new Fenrir endpoint
-pub fn init(config: &Config) -> Result<Fenrir> {
-    // PERF: linux iouring
-    // PERF: multithread pinning with hwloc2 for topology
-    let f = Fenrir::new(config.clone())?;
-    f.add_listener();
-    Ok(f)
+// TODO: graceful vs immediate stop
+
+impl Drop for Fenrir {
+    fn drop(&mut self) {
+        self.stop_sync()
+    }
 }
 
 impl Fenrir {
     /// Create a new Fenrir endpoint
-    fn new(config: Config) -> Result<Self> {
+    pub fn new(config: &Config) -> Result<Self> {
         let mut builder = runtime::Builder::new_multi_thread();
         if let Some(threads) = config.threads {
             builder.worker_threads(threads.get());
@@ -55,27 +62,178 @@ impl Fenrir {
                 return Err(e);
             }
         };
-        Ok(Fenrir {
-            cfg: config,
+        // start listening
+        let listen_num = config.listen.len();
+        let resolvers_num = config.resolvers.len();
+        let (sender, _) = ::tokio::sync::broadcast::channel(1);
+        let endpoint = Fenrir {
+            cfg: config.clone(),
             rt: rt,
-        })
+            sockets: Vec::with_capacity(listen_num),
+            resolvers: Vec::with_capacity(resolvers_num),
+            stop_working: sender,
+        };
+        Ok(endpoint)
     }
-    /// Add an UDP listener
-    fn add_listener(&self) {
-        if self.cfg.listen.len() == 0 {
-            self.rt.spawn(listen_udp(SocketAddr::new(
-                IpAddr::V4(Ipv4Addr::new(0, 0, 0, 0)),
-                0, // 0 means random port
-            )));
-        } else {
-            for sock in self.cfg.listen.iter() {
-                self.rt.spawn(listen_udp(sock.clone()));
-            }
+    /// Start all workers, listeners
+    pub async fn start(&mut self) -> Result<()> {
+        if let Err(e) = self.add_sockets().await {
+            self.stop().await;
+            return Err(e);
+        }
+        if let Err(e) = self.setup_dnssec().await {
+            self.stop().await;
+            return Err(e);
+        }
+        Ok(())
+    }
+    /// Stop all workers, listeners
+    /// asyncronous version for Drop
+    fn stop_sync(&mut self) {
+        let mut toempty_resolv = Vec::new();
+        let mut toempty_socket = Vec::new();
+        ::std::mem::swap(&mut self.resolvers, &mut toempty_resolv);
+        ::std::mem::swap(&mut self.sockets, &mut toempty_socket);
+        self.rt
+            .block_on(Self::real_stop(toempty_socket, toempty_resolv));
+    }
+    /// Stop all workers, listeners
+    pub async fn stop(&mut self) {
+        // TODO
+        let _ = self.stop_working.send(true);
+        let mut toempty_resolv = Vec::new();
+        let mut toempty_socket = Vec::new();
+        ::std::mem::swap(&mut self.resolvers, &mut toempty_resolv);
+        ::std::mem::swap(&mut self.sockets, &mut toempty_socket);
+        Self::real_stop(toempty_socket, toempty_resolv).await;
+    }
+    /// actually do the work of stopping resolvers and listeners
+    async fn real_stop(
+        sockets: Vec<(Arc<UdpSocket>, JoinHandle<Result<()>>)>,
+        resolvers: Vec<(
+            DnssecClient,
+            JoinHandle<
+                result::Result<(), ::trust_dns_proto::error::ProtoError>,
+            >,
+        )>,
+    ) {
+        for r in resolvers.into_iter() {
+            let _ = r.1.await;
+        }
+        for s in sockets.into_iter() {
+            let _ = s.1.await;
         }
     }
+    /// Add all UDP sockets found in config
+    /// and start listening for packets
+    async fn add_sockets(&mut self) -> Result<()> {
+        let sockets = self.cfg.listen.iter().map(|s_addr| async {
+            //let socket = self.rt.block_on(bind_udp(s_addr.clone()))?;
+            let socket = self.rt.spawn(bind_udp(s_addr.clone())).await??;
+            Ok(Arc::new(socket))
+        });
+        let sockets = ::futures::future::join_all(sockets).await;
+        for s_res in sockets.into_iter() {
+            match s_res {
+                Ok(s) => {
+                    let stop_working = self.stop_working.subscribe();
+                    let join =
+                        self.rt.spawn(listen_udp(stop_working, s.clone()));
+                    self.sockets.push((s, join));
+                }
+                Err(e) => {
+                    return Err(e);
+                }
+            }
+        }
+        Ok(())
+    }
+    /// Add and initialize the DNSSEC resolvers to the endpoint
+    async fn setup_dnssec(&mut self) -> Result<()> {
+        // use a TCP connection to the DNS.
+        // the records we need are big, will not fit in a UDP packet
+        use tokio::net::TcpStream;
+        use trust_dns_client::{
+            client::AsyncClient, proto::iocompat::AsyncIoTokioAsStd,
+            tcp::TcpClientStream,
+        };
+
+        for resolver in self.cfg.resolvers.iter() {
+            let (stream, sender) = TcpClientStream::<
+                AsyncIoTokioAsStd<TcpStream>,
+            >::new(resolver.clone());
+            let client_tostart = AsyncClient::new(stream, sender, None);
+            // await the connection to be established
+            let (client, bg) = client_tostart.await?;
+
+            let handle = self.rt.spawn(bg);
+            self.resolvers.push((client, handle));
+        }
+        Ok(())
+    }
+    /// get the fenrir data for a domain
+    pub async fn resolv(&mut self, domain: &str) -> Result<String> {
+        use std::str::FromStr;
+        use trust_dns_client::rr::{DNSClass, Name, RData, RecordType};
+
+        let fullname = "_fenrir".to_owned() + domain;
+        for client in self.resolvers.iter_mut() {
+            let query = client.0.query(
+                Name::from_str(&fullname).unwrap(),
+                DNSClass::IN,
+                RecordType::TXT,
+            );
+
+            // wait for its response
+            let response = query.await?;
+
+            // validate it's what we expected
+            match response.answers()[0].data() {
+                Some(RData::TXT(text)) => return Ok(text.to_string()),
+                _ => {
+                    return Err(::std::io::Error::new(
+                        ::std::io::ErrorKind::NotFound,
+                        "No TXT record found",
+                    ))
+                }
+            }
+        }
+        Err(::std::io::Error::new(
+            ::std::io::ErrorKind::NotConnected,
+            "No DNS server usable",
+        ))
+    }
 }
+
 /// Add an async udp listener
-async fn listen_udp(sock: SocketAddr) -> Result<()> {
-    UdpSocket::bind(sock).await?;
+async fn bind_udp(sock: SocketAddr) -> Result<UdpSocket> {
+    let socket = UdpSocket::bind(sock).await?;
+    // PERF: SO_REUSEADDR/REUSEPORT
+    Ok(socket)
+}
+
+/// Run a dedicated loop to read packets on the listening socket
+async fn listen_udp(
+    mut stop_working: ::tokio::sync::broadcast::Receiver<bool>,
+    socket: Arc<UdpSocket>,
+) -> Result<()> {
+    // jumbo frames are 9K max
+    let mut buffer: [u8; 9000] = [0; 9000];
+    loop {
+        let (bytes, sock_from) = ::tokio::select! {
+            _done = stop_working.recv() => {
+                break;
+            }
+            result = socket.recv_from(&mut buffer) => {
+                result?
+            }
+        };
+        work(&buffer[0..bytes], sock_from).await;
+    }
     Ok(())
 }
+
+/// Read and do stuff with the udp packet
+async fn work(_buffer: &[u8], _sock_from: SocketAddr) {
+    // Do nothing for now
+}