tcp_tester: try to connect multiple times

On slow hosts (i.e. running with nested virt), when the server is
inside the guest, the client may fail to connect because the first is
not yet ready.

Make the test attempt to connect multiple times, waiting a second
between attempts.

Signed-off-by: Sergio Lopez <[email protected]>

Author: slp

tests/test_cases/src/tcp_tester.rs

@@ -1,6 +1,7 @@
 use std::io::{ErrorKind, Read, Write};
 use std::mem;
 use std::net::{IpAddr, Ipv4Addr, SocketAddr, SocketAddrV4, TcpListener, TcpStream};
+use std::thread;
 use std::time::Duration;
 
 fn expect_msg(stream: &mut TcpStream, expected: &[u8]) {
@@ -25,6 +26,23 @@ fn set_timeouts(stream: &mut TcpStream) {
         .unwrap();
 }
 
+fn connect(port: u16) -> TcpStream {
+    let addr = SocketAddr::new(IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1)), port);
+    let mut tries = 0;
+    loop {
+        match TcpStream::connect(&addr) {
+            Ok(stream) => return stream,
+            Err(err) => {
+                if tries == 5 {
+                    panic!("Couldn't connect to server after 5 attempts: {err}");
+                }
+                tries += 1;
+                thread::sleep(Duration::from_secs(1));
+            }
+        }
+    }
+}
+
 #[derive(Debug, Copy, Clone)]
 pub struct TcpTester {
     port: u16,
@@ -51,8 +69,7 @@ impl TcpTester {
     }
 
     pub fn run_client(&self) {
-        let addr = SocketAddr::new(IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1)), self.port);
-        let mut stream = TcpStream::connect(&addr).unwrap();
+        let mut stream = connect(self.port);
         set_timeouts(&mut stream);
         expect_msg(&mut stream, b"ping!");
         expect_wouldblock(&mut stream);