dependency: use mio to replace polling (#280)

Poller.add() is unsafe in `polling` 3.x, but we want to keep this lib safe code only. Hence the change.

.github/workflows/build.yml

@@ -19,7 +19,7 @@ jobs:
         os: [ubuntu-20.04, windows-latest, macos-latest]
     steps:
       - uses: actions/checkout@v4
-      - uses: dtolnay/rust-toolchain@1.65.0
+      - uses: dtolnay/rust-toolchain@1.70.0
         with:
           components: rustfmt, clippy
       - name: Run rustfmt and fail if any warnings

Cargo.toml

@@ -3,7 +3,7 @@ name = "mdns-sd"
 version = "0.12.0"
 authors = ["keepsimple <[email protected]>"]
 edition = "2018"
-rust-version = "1.65.0"
+rust-version = "1.70.0"
 license = "Apache-2.0 OR MIT"
 repository = "https://github.com/keepsimple1/mdns-sd"
 documentation = "https://docs.rs/mdns-sd"
@@ -21,7 +21,7 @@ fastrand = "2.1"
 flume = { version = "0.11", default-features = false } # channel between threads
 if-addrs = { version = "0.13", features = ["link-local"] } # get local IP addresses
 log = { version = "0.4", optional = true }             # logging
-polling = "2.1"                                        # select/poll sockets
+mio = { version = "1.0", features = ["os-poll", "net"] }  # select/poll sockets
 socket2 = { version = "0.5.5", features = ["all"] }      # socket APIs
 
 [dev-dependencies]

README.md

@@ -3,7 +3,7 @@
 [![Build](https://github.com/keepsimple1/mdns-sd/actions/workflows/build.yml/badge.svg)](https://github.com/keepsimple1/mdns-sd/actions)
 [![Cargo](https://img.shields.io/crates/v/mdns-sd.svg)](https://crates.io/crates/mdns-sd)
 [![docs.rs](https://img.shields.io/docsrs/mdns-sd)](https://docs.rs/mdns-sd/latest/mdns_sd/)
-[![Rust version: 1.63+](https://img.shields.io/badge/rust%20version-1.63+-orange)](https://blog.rust-lang.org/2022/08/11/Rust-1.63.0.html)
+[![Rust version: 1.70+](https://img.shields.io/badge/rust%20version-1.70+-orange)](https://blog.rust-lang.org/2022/08/11/Rust-1.70.0.html)
 
 This is a small implementation of mDNS (Multicast DNS) based service discovery in safe Rust, with a small set of dependencies. Some highlights:
 

src/service_daemon.rs

@@ -43,13 +43,12 @@ use crate::{
 };
 use flume::{bounded, Sender, TrySendError};
 use if_addrs::{IfAddr, Interface};
-use polling::Poller;
-use socket2::{SockAddr, Socket};
+use mio::{net::UdpSocket as MioUdpSocket, Poll};
+use socket2::Socket;
 use std::{
     cmp::{self, Reverse},
     collections::{BinaryHeap, HashMap, HashSet},
     fmt,
-    io::Read,
     net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV6, UdpSocket},
     str, thread,
     time::Duration,
@@ -179,14 +178,15 @@ impl ServiceDaemon {
             .set_nonblocking(true)
             .map_err(|e| e_fmt!("failed to set nonblocking for signal socket: {}", e))?;
 
-        let poller = Poller::new().map_err(|e| e_fmt!("Failed to create Poller: {}", e))?;
+        let poller = Poll::new().map_err(|e| e_fmt!("failed to create mio Poll: {e}"))?;
 
         let (sender, receiver) = bounded(100);
 
         // Spawn the daemon thread
+        let mio_sock = MioUdpSocket::from_std(signal_sock);
         thread::Builder::new()
             .name("mDNS_daemon".to_string())
-            .spawn(move || Self::daemon_thread(signal_sock, poller, receiver))
+            .spawn(move || Self::daemon_thread(mio_sock, poller, receiver))
             .map_err(|e| e_fmt!("thread builder failed to spawn: {}", e))?;
 
         Ok(Self {
@@ -417,7 +417,7 @@ impl ServiceDaemon {
         self.send_cmd(Command::Verify(instance_fullname, timeout))
     }
 
-    fn daemon_thread(signal_sock: UdpSocket, poller: Poller, receiver: Receiver<Command>) {
+    fn daemon_thread(signal_sock: MioUdpSocket, poller: Poll, receiver: Receiver<Command>) {
         let zc = Zeroconf::new(signal_sock, poller);
 
         if let Some(cmd) = Self::run(zc, receiver) {
@@ -436,35 +436,40 @@ impl ServiceDaemon {
         }
     }
 
-    fn handle_poller_events(zc: &mut Zeroconf, events: &[polling::Event]) {
+    fn handle_poller_events(zc: &mut Zeroconf, events: &mio::Events) {
         for ev in events.iter() {
-            trace!("event received with key {}", ev.key);
-            if ev.key == SIGNAL_SOCK_EVENT_KEY {
+            trace!("event received with key {:?}", ev.token());
+            if ev.token().0 == SIGNAL_SOCK_EVENT_KEY {
                 // Drain signals as we will drain commands as well.
                 zc.signal_sock_drain();
 
-                if let Err(e) = zc
-                    .poller
-                    .modify(&zc.signal_sock, polling::Event::readable(ev.key))
-                {
+                if let Err(e) = zc.poller.registry().reregister(
+                    &mut zc.signal_sock,
+                    ev.token(),
+                    mio::Interest::READABLE,
+                ) {
                     debug!("failed to modify poller for signal socket: {}", e);
                 }
                 continue; // Next event.
             }
 
             // Read until no more packets available.
-            let intf = match zc.poll_ids.get(&ev.key) {
+            let intf = match zc.poll_ids.get(&ev.token().0) {
                 Some(interface) => interface.clone(),
                 None => {
-                    debug!("Ip for event key {} not found", ev.key);
+                    debug!("Ip for event key {} not found", ev.token().0);
                     break;
                 }
             };
             while zc.handle_read(&intf) {}
 
             // we continue to monitor this socket.
-            if let Some(sock) = zc.intf_socks.get(&intf) {
-                if let Err(e) = zc.poller.modify(sock, polling::Event::readable(ev.key)) {
+            if let Some(sock) = zc.intf_socks.get_mut(&intf) {
+                if let Err(e) =
+                    zc.poller
+                        .registry()
+                        .reregister(sock, ev.token(), mio::Interest::READABLE)
+                {
                     debug!("modify poller for interface {:?}: {}", &intf, e);
                     break;
                 }
@@ -482,20 +487,26 @@ impl ServiceDaemon {
     /// 5. process retransmissions if any.
     fn run(mut zc: Zeroconf, receiver: Receiver<Command>) -> Option<Command> {
         // Add the daemon's signal socket to the poller.
-        if let Err(e) = zc.poller.add(
-            &zc.signal_sock,
-            polling::Event::readable(SIGNAL_SOCK_EVENT_KEY),
+        if let Err(e) = zc.poller.registry().register(
+            &mut zc.signal_sock,
+            mio::Token(SIGNAL_SOCK_EVENT_KEY),
+            mio::Interest::READABLE,
         ) {
             debug!("failed to add signal socket to the poller: {}", e);
             return None;
         }
 
         // Add mDNS sockets to the poller.
-        for (intf, sock) in zc.intf_socks.iter() {
+        for (intf, sock) in zc.intf_socks.iter_mut() {
             let key =
                 Zeroconf::add_poll_impl(&mut zc.poll_ids, &mut zc.poll_id_count, intf.clone());
-            if let Err(e) = zc.poller.add(sock, polling::Event::readable(key)) {
-                debug!("add socket of {:?} to poller: {}", intf, e);
+
+            if let Err(e) =
+                zc.poller
+                    .registry()
+                    .register(sock, mio::Token(key), mio::Interest::READABLE)
+            {
+                debug!("add socket of {:?} to poller: {e}", intf);
                 return None;
             }
         }
@@ -507,7 +518,7 @@ impl ServiceDaemon {
 
         // Start the run loop.
 
-        let mut events = Vec::new();
+        let mut events = mio::Events::with_capacity(1024);
         loop {
             let now = current_time_millis();
 
@@ -520,7 +531,7 @@ impl ServiceDaemon {
 
             // Process incoming packets, command events and optional timeout.
             events.clear();
-            match zc.poller.wait(&mut events, timeout) {
+            match zc.poller.poll(&mut events, timeout) {
                 Ok(_) => Self::handle_poller_events(&mut zc, &events),
                 Err(e) => debug!("failed to select from sockets: {}", e),
             }
@@ -626,7 +637,7 @@ impl ServiceDaemon {
 }
 
 /// Creates a new UDP socket that uses `intf` to send and recv multicast.
-fn new_socket_bind(intf: &Interface) -> Result<Socket> {
+fn new_socket_bind(intf: &Interface) -> Result<MioUdpSocket> {
     // Use the same socket for receiving and sending multicast packets.
     // Such socket has to bind to INADDR_ANY or IN6ADDR_ANY.
     let intf_ip = &intf.ip();
@@ -650,7 +661,7 @@ fn new_socket_bind(intf: &Interface) -> Result<Socket> {
                 sock.send_to(&packet, &multicast_addr)
                     .map_err(|e| e_fmt!("send multicast packet on addr {}: {}", ip, e))?;
             }
-            Ok(sock)
+            Ok(MioUdpSocket::from_std(UdpSocket::from(sock)))
         }
         IpAddr::V6(ip) => {
             let addr = SocketAddrV6::new(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 0), MDNS_PORT, 0, 0);
@@ -668,7 +679,7 @@ fn new_socket_bind(intf: &Interface) -> Result<Socket> {
             // be many IPv6 interfaces on a host and could cause such send error:
             // "No buffer space available (os error 55)".
 
-            Ok(sock)
+            Ok(MioUdpSocket::from_std(UdpSocket::from(sock)))
         }
     }
 }
@@ -834,7 +845,7 @@ struct IfSelection {
 /// A struct holding the state. It was inspired by `zeroconf` package in Python.
 struct Zeroconf {
     /// Local interfaces with sockets to recv/send on these interfaces.
-    intf_socks: HashMap<Interface, Socket>,
+    intf_socks: HashMap<Interface, MioUdpSocket>,
 
     /// Map poll id to Interface.
     poll_ids: HashMap<usize, Interface>,
@@ -865,7 +876,7 @@ struct Zeroconf {
     counters: Metrics,
 
     /// Waits for incoming packets.
-    poller: Poller,
+    poller: Poll,
 
     /// Channels to notify events.
     monitors: Vec<Sender<DaemonEvent>>,
@@ -877,7 +888,7 @@ struct Zeroconf {
     if_selections: Vec<IfSelection>,
 
     /// Socket for signaling.
-    signal_sock: UdpSocket,
+    signal_sock: MioUdpSocket,
 
     /// Timestamps marking where we need another iteration of the run loop,
     /// to react to events like retransmissions, cache refreshes, interface IP address changes, etc.
@@ -896,7 +907,7 @@ struct Zeroconf {
 }
 
 impl Zeroconf {
-    fn new(signal_sock: UdpSocket, poller: Poller) -> Self {
+    fn new(signal_sock: MioUdpSocket, poller: Poll) -> Self {
         // Get interfaces.
         let my_ifaddrs = my_ip_interfaces();
 
@@ -1087,8 +1098,8 @@ impl Zeroconf {
                 }
             } else {
                 // Remove the interface
-                if let Some(sock) = self.intf_socks.remove(&intf) {
-                    if let Err(e) = self.poller.delete(&sock) {
+                if let Some(mut sock) = self.intf_socks.remove(&intf) {
+                    if let Err(e) = self.poller.registry().deregister(&mut sock) {
                         debug!("process_if_selections: poller.delete {:?}: {}", &intf, e);
                     }
                     // Remove from poll_ids
@@ -1108,10 +1119,10 @@ impl Zeroconf {
         // Remove unused sockets in the poller.
         let deleted_addrs = self
             .intf_socks
-            .iter()
+            .iter_mut()
             .filter_map(|(intf, sock)| {
                 if !my_ifaddrs.contains(intf) {
-                    if let Err(e) = poller.delete(sock) {
+                    if let Err(e) = poller.registry().deregister(sock) {
                         debug!("check_ip_changes: poller.delete {:?}: {}", intf, e);
                     }
                     // Remove from poll_ids
@@ -1139,7 +1150,7 @@ impl Zeroconf {
     fn add_new_interface(&mut self, intf: Interface) {
         // Bind the new interface.
         let new_ip = intf.ip();
-        let sock = match new_socket_bind(&intf) {
+        let mut sock = match new_socket_bind(&intf) {
             Ok(s) => s,
             Err(e) => {
                 debug!("bind a socket to {}: {}. Skipped.", &intf.ip(), e);
@@ -1149,7 +1160,11 @@ impl Zeroconf {
 
         // Add the new interface into the poller.
         let key = self.add_poll(intf.clone());
-        if let Err(e) = self.poller.add(&sock, polling::Event::readable(key)) {
+        if let Err(e) =
+            self.poller
+                .registry()
+                .register(&mut sock, mio::Token(key), mio::Interest::READABLE)
+        {
             debug!("check_ip_changes: poller add ip {}: {}", new_ip, e);
             return;
         }
@@ -1417,7 +1432,12 @@ impl Zeroconf {
         }
     }
 
-    fn unregister_service(&self, info: &ServiceInfo, intf: &Interface, sock: &Socket) -> Vec<u8> {
+    fn unregister_service(
+        &self,
+        info: &ServiceInfo,
+        intf: &Interface,
+        sock: &MioUdpSocket,
+    ) -> Vec<u8> {
         let mut out = DnsOutgoing::new(FLAGS_QR_RESPONSE | FLAGS_AA);
         out.add_answer_at_time(
             DnsPointer::new(
@@ -1559,7 +1579,7 @@ impl Zeroconf {
         // be truncated by the socket layer depending on the platform's libc.
         // In any case, such large datagram will not be decoded properly and
         // this function should return false but should not crash.
-        let sz = match sock.read(&mut buf) {
+        let sz = match sock.recv(&mut buf) {
             Ok(sz) => sz,
             Err(e) => {
                 if e.kind() != std::io::ErrorKind::WouldBlock {
@@ -1573,8 +1593,8 @@ impl Zeroconf {
 
         // If sz is 0, it means sock reached End-of-File.
         if sz == 0 {
-            debug!("socket {:?} was likely shutdown", sock);
-            if let Err(e) = self.poller.delete(&*sock) {
+            debug!("socket {:?} was likely shutdown", &sock);
+            if let Err(e) = self.poller.registry().deregister(sock) {
                 debug!("failed to remove sock {:?} from poller: {}", sock, &e);
             }
 
@@ -3019,7 +3039,7 @@ fn my_ip_interfaces() -> Vec<Interface> {
 }
 
 /// Send an outgoing mDNS query or response, and returns the packet bytes.
-fn send_dns_outgoing(out: &DnsOutgoing, intf: &Interface, sock: &Socket) -> Vec<Vec<u8>> {
+fn send_dns_outgoing(out: &DnsOutgoing, intf: &Interface, sock: &MioUdpSocket) -> Vec<Vec<u8>> {
     let qtype = if out.is_query() { "query" } else { "response" };
     trace!(
         "send outgoing {}: {} questions {} answers {} authorities {} additional",
@@ -3037,7 +3057,7 @@ fn send_dns_outgoing(out: &DnsOutgoing, intf: &Interface, sock: &Socket) -> Vec<
 }
 
 /// Sends a multicast packet, and returns the packet bytes.
-fn multicast_on_intf(packet: &[u8], intf: &Interface, socket: &Socket) {
+fn multicast_on_intf(packet: &[u8], intf: &Interface, socket: &MioUdpSocket) {
     if packet.len() > MAX_MSG_ABSOLUTE {
         debug!("Drop over-sized packet ({})", packet.len());
         return;
@@ -3056,9 +3076,8 @@ fn multicast_on_intf(packet: &[u8], intf: &Interface, socket: &Socket) {
 }
 
 /// Sends out `packet` to `addr` on the socket in `intf_sock`.
-fn send_packet(packet: &[u8], addr: SocketAddr, intf: &Interface, sock: &Socket) {
-    let sockaddr = SockAddr::from(addr);
-    match sock.send_to(packet, &sockaddr) {
+fn send_packet(packet: &[u8], addr: SocketAddr, intf: &Interface, sock: &MioUdpSocket) {
+    match sock.send_to(packet, addr) {
         Ok(sz) => trace!("sent out {} bytes on interface {:?}", sz, intf),
         Err(e) => debug!("Failed to send to {} via {:?}: {}", addr, &intf, e),
     }
@@ -3224,7 +3243,7 @@ fn announce_service_on_intf(
     dns_registry: &mut DnsRegistry,
     info: &ServiceInfo,
     intf: &Interface,
-    sock: &Socket,
+    sock: &MioUdpSocket,
 ) -> bool {
     if let Some(out) = prepare_announce(info, intf, dns_registry) {
         send_dns_outgoing(&out, intf, sock);