feat(client): Add connect timeout to HttpConnector (#1972)

This takes the same strategy as golang, where the timeout value is
divided equally between the candidate socket addresses.

If happy eyeballs is enabled, the division takes place "below" the
IPv4/IPv6 partitioning.

src/client/connect/dns.rs

@@ -235,6 +235,10 @@ impl IpAddrs {
     pub(super) fn is_empty(&self) -> bool {
         self.iter.as_slice().is_empty()
     }
+
+    pub(super) fn len(&self) -> usize {
+        self.iter.as_slice().len()
+    }
 }
 
 impl Iterator for IpAddrs {

src/client/connect/http.rs

@@ -10,7 +10,7 @@ use futures_util::{TryFutureExt, FutureExt};
 use net2::TcpBuilder;
 use tokio_net::driver::Handle;
 use tokio_net::tcp::TcpStream;
-use tokio_timer::Delay;
+use tokio_timer::{Delay, Timeout};
 
 use crate::common::{Future, Pin, Poll, task};
 use super::{Connect, Connected, Destination};
@@ -32,6 +32,7 @@ type ConnectFuture = Pin<Box<dyn Future<Output = io::Result<TcpStream>> + Send>>
 pub struct HttpConnector<R = GaiResolver> {
     enforce_http: bool,
     handle: Option<Handle>,
+    connect_timeout: Option<Duration>,
     happy_eyeballs_timeout: Option<Duration>,
     keep_alive_timeout: Option<Duration>,
     local_address: Option<IpAddr>,
@@ -101,6 +102,7 @@ impl<R> HttpConnector<R> {
         HttpConnector {
             enforce_http: true,
             handle: None,
+            connect_timeout: None,
             happy_eyeballs_timeout: Some(Duration::from_millis(300)),
             keep_alive_timeout: None,
             local_address: None,
@@ -168,6 +170,17 @@ impl<R> HttpConnector<R> {
         self.local_address = addr;
     }
 
+    /// Set the connect timeout.
+    ///
+    /// If a domain resolves to multiple IP addresses, the timeout will be
+    /// evenly divided across them.
+    ///
+    /// Default is `None`.
+    #[inline]
+    pub fn set_connect_timeout(&mut self, dur: Option<Duration>) {
+        self.connect_timeout = dur;
+    }
+
     /// Set timeout for [RFC 6555 (Happy Eyeballs)][RFC 6555] algorithm.
     ///
     /// If hostname resolves to both IPv4 and IPv6 addresses and connection
@@ -240,6 +253,7 @@ where
         HttpConnecting {
             state: State::Lazy(self.resolver.clone(), host.into(), self.local_address),
             handle: self.handle.clone(),
+            connect_timeout: self.connect_timeout,
             happy_eyeballs_timeout: self.happy_eyeballs_timeout,
             keep_alive_timeout: self.keep_alive_timeout,
             nodelay: self.nodelay,
@@ -295,6 +309,7 @@ where
         let fut = HttpConnecting {
             state: State::Lazy(self.resolver.clone(), host.into(), self.local_address),
             handle: self.handle.clone(),
+            connect_timeout: self.connect_timeout,
             happy_eyeballs_timeout: self.happy_eyeballs_timeout,
             keep_alive_timeout: self.keep_alive_timeout,
             nodelay: self.nodelay,
@@ -323,6 +338,7 @@ fn invalid_url<R: Resolve>(err: InvalidUrl, handle: &Option<Handle>) -> HttpConn
         keep_alive_timeout: None,
         nodelay: false,
         port: 0,
+        connect_timeout: None,
         happy_eyeballs_timeout: None,
         reuse_address: false,
         send_buffer_size: None,
@@ -357,6 +373,7 @@ impl StdError for InvalidUrl {
 pub struct HttpConnecting<R: Resolve = GaiResolver> {
     state: State<R>,
     handle: Option<Handle>,
+    connect_timeout: Option<Duration>,
     happy_eyeballs_timeout: Option<Duration>,
     keep_alive_timeout: Option<Duration>,
     nodelay: bool,
@@ -389,7 +406,7 @@ where
                     // skip resolving the dns and start connecting right away.
                     if let Some(addrs) = dns::IpAddrs::try_parse(host, me.port) {
                         state = State::Connecting(ConnectingTcp::new(
-                            local_addr, addrs, me.happy_eyeballs_timeout, me.reuse_address));
+                            local_addr, addrs, me.connect_timeout, me.happy_eyeballs_timeout, me.reuse_address));
                     } else {
                         let name = dns::Name::new(mem::replace(host, String::new()));
                         state = State::Resolving(resolver.resolve(name), local_addr);
@@ -403,7 +420,7 @@ where
                         .collect();
                     let addrs = dns::IpAddrs::new(addrs);
                     state = State::Connecting(ConnectingTcp::new(
-                        local_addr, addrs, me.happy_eyeballs_timeout, me.reuse_address));
+                        local_addr, addrs, me.connect_timeout, me.happy_eyeballs_timeout, me.reuse_address));
                 },
                 State::Connecting(ref mut c) => {
                     let sock = ready!(c.poll(cx, &me.handle))?;
@@ -454,6 +471,7 @@ impl ConnectingTcp {
     fn new(
         local_addr: Option<IpAddr>,
         remote_addrs: dns::IpAddrs,
+        connect_timeout: Option<Duration>,
         fallback_timeout: Option<Duration>,
         reuse_address: bool,
     ) -> ConnectingTcp {
@@ -462,7 +480,7 @@ impl ConnectingTcp {
             if fallback_addrs.is_empty() {
                 return ConnectingTcp {
                     local_addr,
-                    preferred: ConnectingTcpRemote::new(preferred_addrs),
+                    preferred: ConnectingTcpRemote::new(preferred_addrs, connect_timeout),
                     fallback: None,
                     reuse_address,
                 };
@@ -470,17 +488,17 @@ impl ConnectingTcp {
 
             ConnectingTcp {
                 local_addr,
-                preferred: ConnectingTcpRemote::new(preferred_addrs),
+                preferred: ConnectingTcpRemote::new(preferred_addrs, connect_timeout),
                 fallback: Some(ConnectingTcpFallback {
                     delay: tokio_timer::delay_for(fallback_timeout),
-                    remote: ConnectingTcpRemote::new(fallback_addrs),
+                    remote: ConnectingTcpRemote::new(fallback_addrs, connect_timeout),
                 }),
                 reuse_address,
             }
         } else {
             ConnectingTcp {
                 local_addr,
-                preferred: ConnectingTcpRemote::new(remote_addrs),
+                preferred: ConnectingTcpRemote::new(remote_addrs, connect_timeout),
                 fallback: None,
                 reuse_address,
             }
@@ -495,13 +513,17 @@ struct ConnectingTcpFallback {
 
 struct ConnectingTcpRemote {
     addrs: dns::IpAddrs,
+    connect_timeout: Option<Duration>,
     current: Option<ConnectFuture>,
 }
 
 impl ConnectingTcpRemote {
-    fn new(addrs: dns::IpAddrs) -> Self {
+    fn new(addrs: dns::IpAddrs, connect_timeout: Option<Duration>) -> Self {
+        let connect_timeout = connect_timeout.map(|t| t / (addrs.len() as u32));
+
         Self {
             addrs,
+            connect_timeout,
             current: None,
         }
     }
@@ -530,14 +552,14 @@ impl ConnectingTcpRemote {
                         err = Some(e);
                         if let Some(addr) = self.addrs.next() {
                             debug!("connecting to {}", addr);
-                            *current = connect(&addr, local_addr, handle, reuse_address)?;
+                            *current = connect(&addr, local_addr, handle, reuse_address, self.connect_timeout)?;
                             continue;
                         }
                     }
                 }
             } else if let Some(addr) = self.addrs.next() {
                 debug!("connecting to {}", addr);
-                self.current = Some(connect(&addr, local_addr, handle, reuse_address)?);
+                self.current = Some(connect(&addr, local_addr, handle, reuse_address, self.connect_timeout)?);
                 continue;
             }
 
@@ -546,7 +568,13 @@ impl ConnectingTcpRemote {
     }
 }
 
-fn connect(addr: &SocketAddr, local_addr: &Option<IpAddr>, handle: &Option<Handle>, reuse_address: bool) -> io::Result<ConnectFuture> {
+fn connect(
+    addr: &SocketAddr,
+    local_addr: &Option<IpAddr>,
+    handle: &Option<Handle>,
+    reuse_address: bool,
+    connect_timeout: Option<Duration>,
+) -> io::Result<ConnectFuture> {
     let builder = match addr {
         &SocketAddr::V4(_) => TcpBuilder::new_v4()?,
         &SocketAddr::V6(_) => TcpBuilder::new_v6()?,
@@ -581,10 +609,16 @@ fn connect(addr: &SocketAddr, local_addr: &Option<IpAddr>, handle: &Option<Handl
     let std_tcp = builder.to_tcp_stream()?;
 
     Ok(Box::pin(async move {
-        TcpStream::connect_std(std_tcp, &addr, &handle).await
+        let connect = TcpStream::connect_std(std_tcp, &addr, &handle);
+        match connect_timeout {
+            Some(timeout) => match Timeout::new(connect, timeout).await {
+                Ok(Ok(s)) => Ok(s),
+                Ok(Err(e)) => Err(e),
+                Err(e) => Err(io::Error::new(io::ErrorKind::TimedOut, e)),
+            }
+            None => connect.await,
+        }
     }))
-
-    //Ok(Box::pin(TcpStream::connect_std(std_tcp, addr, &handle)))
 }
 
 impl ConnectingTcp {
@@ -673,7 +707,6 @@ mod tests {
         })
     }
 
-
     #[test]
     fn test_errors_missing_scheme() {
         let mut rt = Runtime::new().unwrap();
@@ -765,7 +798,7 @@ mod tests {
             }
 
             let addrs = hosts.iter().map(|host| (host.clone(), addr.port()).into()).collect();
-            let connecting_tcp = ConnectingTcp::new(None, dns::IpAddrs::new(addrs), Some(fallback_timeout), false);
+            let connecting_tcp = ConnectingTcp::new(None, dns::IpAddrs::new(addrs), None, Some(fallback_timeout), false);
             let fut = ConnectingTcpFuture(connecting_tcp);
 
             let start = Instant::now();