Implement timeouts when there are multiple socket addrs

src/raw_client.rs

@@ -5,7 +5,7 @@
 use std::collections::{HashMap, HashSet, VecDeque};
 use std::io::{BufRead, BufReader, Read, Write};
 use std::mem::drop;
-use std::net::{SocketAddr, TcpStream, ToSocketAddrs};
+use std::net::{TcpStream, ToSocketAddrs};
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::sync::mpsc::{channel, Receiver, Sender};
 use std::sync::{Arc, Mutex, TryLockError};
@@ -161,8 +161,7 @@ impl RawClient<ElectrumPlaintextStream> {
     ) -> Result<Self, Error> {
         let stream = match timeout {
             Some(timeout) => {
-                let socket_addr = get_one_socket_addr(socket_addrs)?;
-                let stream = TcpStream::connect_timeout(&socket_addr, timeout)?;
+                let stream = connect_with_total_timeout(socket_addrs, timeout)?;
                 stream.set_read_timeout(Some(timeout))?;
                 stream.set_write_timeout(Some(timeout))?;
                 stream
@@ -174,16 +173,41 @@ impl RawClient<ElectrumPlaintextStream> {
     }
 }
 
-fn get_one_socket_addr<A: ToSocketAddrs>(socket_addrs: A) -> Result<SocketAddr, Error> {
-    let mut socket_iter = socket_addrs.to_socket_addrs()?;
-    let socket_addr = socket_iter
-        .next()
-        .ok_or(Error::WrongAddrsNumberWithTimeout)?;
-    // Unlike `connect`, `connect_timeout` takes a single [`SocketAddr`]
-    match socket_iter.next() {
-        None => Ok(socket_addr),
-        Some(_) => Err(Error::WrongAddrsNumberWithTimeout),
+fn connect_with_total_timeout<A: ToSocketAddrs>(
+    socket_addrs: A,
+    mut timeout: Duration,
+) -> Result<TcpStream, Error> {
+    // Use the same algorithm as curl: 1/2 on the first host, 1/4 on the second one, etc.
+    // https://curl.se/mail/lib-2014-11/0164.html
+
+    let mut errors = Vec::new();
+
+    let addrs = socket_addrs
+        .to_socket_addrs()?
+        .enumerate()
+        .collect::<Vec<_>>();
+    for (index, addr) in &addrs {
+        if *index < addrs.len() - 1 {
+            timeout = timeout.div_f32(2.0);
+        }
+
+        info!(
+            "Trying to connect to {} (attempt {}/{}) with timeout {:?}",
+            addr,
+            index + 1,
+            addrs.len(),
+            timeout
+        );
+        match TcpStream::connect_timeout(addr, timeout) {
+            Ok(socket) => return Ok(socket),
+            Err(e) => {
+                warn!("Connection error: {:?}", e);
+                errors.push(e.into());
+            }
+        }
     }
+
+    Err(Error::AllAttemptsErrored(errors))
 }
 
 #[cfg(feature = "use-openssl")]
@@ -209,8 +233,7 @@ impl RawClient<ElectrumSslStream> {
         }
         match timeout {
             Some(timeout) => {
-                let socket_addr = get_one_socket_addr(socket_addrs.clone())?;
-                let stream = TcpStream::connect_timeout(&socket_addr, timeout)?;
+                let stream = connect_with_total_timeout(socket_addrs.clone(), timeout)?;
                 stream.set_read_timeout(Some(timeout))?;
                 stream.set_write_timeout(Some(timeout))?;
                 Self::new_ssl_from_stream(socket_addrs, validate_domain, stream)
@@ -300,8 +323,7 @@ impl RawClient<ElectrumSslStream> {
         }
         match timeout {
             Some(timeout) => {
-                let socket_addr = get_one_socket_addr(socket_addrs.clone())?;
-                let stream = TcpStream::connect_timeout(&socket_addr, timeout)?;
+                let stream = connect_with_total_timeout(socket_addrs.clone(), timeout)?;
                 stream.set_read_timeout(Some(timeout))?;
                 stream.set_write_timeout(Some(timeout))?;
                 Self::new_ssl_from_stream(socket_addrs, validate_domain, stream)

src/types.rs

@@ -296,8 +296,6 @@ pub enum Error {
     SharedIOError(Arc<std::io::Error>),
     /// Setting both a proxy and a timeout in `Config` is an error
     BothSocksAndTimeout,
-    /// Setting both a timeout and passing zero or more than one socket addrs is an error
-    WrongAddrsNumberWithTimeout,
 
     /// Couldn't take a lock on the reader mutex. This means that there's already another reader
     /// thread running
@@ -343,7 +341,6 @@ impl Display for Error {
 
             Error::MissingDomain => f.write_str("Missing domain while it was explicitly asked to validate it"),
             Error::BothSocksAndTimeout => f.write_str("Setting both a proxy and a timeout in `Config` is an error"),
-            Error::WrongAddrsNumberWithTimeout => f.write_str("Setting both a timeout and passing zero or more than one socket addrs is an error"),
             Error::CouldntLockReader => f.write_str("Couldn't take a lock on the reader mutex. This means that there's already another reader thread is running"),
         }
     }