Allow a connection attempt to timeout and keep trying resolved addresses

src/stream.rs

@@ -2,6 +2,7 @@ use log::debug;
 use std::io::{self, BufRead, BufReader, Read, Write};
 use std::net::SocketAddr;
 use std::net::TcpStream;
+use std::ops::Div;
 use std::time::Duration;
 use std::time::Instant;
 use std::{fmt, io::Cursor};
@@ -366,10 +367,18 @@ pub(crate) fn connect_host(
     let mut any_err = None;
     let mut any_stream_and_addr = None;
     // Find the first sock_addr that accepts a connection
+    let multiple_addrs = sock_addrs.len() > 1;
+
     for sock_addr in sock_addrs {
         // ensure connect timeout or overall timeout aren't yet hit.
         let timeout = match connect_deadline {
-            Some(deadline) => Some(time_until_deadline(deadline)?),
+            Some(deadline) => {
+                let mut deadline = time_until_deadline(deadline)?;
+                if multiple_addrs {
+                    deadline = deadline.div(2);
+                }
+                Some(deadline)
+            }
             None => None,
         };
 

src/test/agent_test.rs

@@ -3,7 +3,7 @@
 use crate::error::Error;
 use crate::testserver::{read_request, TestServer};
 use std::io::{self, Read, Write};
-use std::net::TcpStream;
+use std::net::{IpAddr, Ipv4Addr, SocketAddr, TcpStream};
 use std::thread;
 use std::time::Duration;
 
@@ -111,6 +111,33 @@ fn custom_resolver() {
     assert_eq!(&server.join().unwrap(), b"GET / HTTP/1.1\r\n");
 }
 
+#[test]
+fn socket_addr_fail_over() {
+    use std::net::TcpListener;
+
+    let listener = TcpListener::bind("127.0.0.1:0").unwrap();
+
+    let local_addr = listener.local_addr().unwrap();
+    let non_routable_ipv4 = SocketAddr::new(IpAddr::V4(Ipv4Addr::new(10, 255, 255, 1)), 9872);
+    let server = std::thread::spawn(move || {
+        let (mut client, _) = listener.accept().unwrap();
+        let mut buf = vec![0u8; 16];
+        let read = client.read(&mut buf).unwrap();
+        buf.truncate(read);
+        buf
+    });
+
+    AgentBuilder::new()
+        .resolver(move |_: &str| Ok(vec![non_routable_ipv4, local_addr]))
+        .timeout_connect(Duration::from_secs(2))
+        .build()
+        .get("http://cool.server/")
+        .call()
+        .ok();
+
+    assert_eq!(&server.join().unwrap(), b"GET / HTTP/1.1\r\n");
+}
+
 #[cfg(feature = "cookies")]
 #[cfg(test)]
 fn cookie_and_redirect(mut stream: TcpStream) -> io::Result<()> {