fix(server): fix broken keep-alive in Server

Closes #1134

src/http/conn.rs

@@ -610,6 +610,9 @@ impl<B, K: KeepAlive> State<B, K> {
     }
 
     fn busy(&mut self) {
+        if let KA::Disabled = self.keep_alive.status() {
+            return;
+        }
         self.keep_alive.busy();
     }
 

tests/server.rs

@@ -146,10 +146,16 @@ fn connect(addr: &SocketAddr) -> TcpStream {
 }
 
 fn serve() -> Serve {
-    serve_with_timeout(None)
+    serve_with_options(Default::default())
 }
 
-fn serve_with_timeout(dur: Option<Duration>) -> Serve {
+#[derive(Default)]
+struct ServeOptions {
+    keep_alive_disabled: bool,
+    timeout: Option<Duration>,
+}
+
+fn serve_with_options(options: ServeOptions) -> Serve {
     let _ = pretty_env_logger::init();
 
     let (addr_tx, addr_rx) = mpsc::channel();
@@ -159,9 +165,12 @@ fn serve_with_timeout(dur: Option<Duration>) -> Serve {
 
     let addr = "127.0.0.1:0".parse().unwrap();
 
+    let keep_alive = !options.keep_alive_disabled;
+    let dur = options.timeout;
+
     let thread_name = format!("test-server-{:?}", dur);
     let thread = thread::Builder::new().name(thread_name).spawn(move || {
-        let srv = Http::new().bind(&addr, TestService {
+        let srv = Http::new().keep_alive(keep_alive).bind(&addr, TestService {
             tx: Arc::new(Mutex::new(msg_tx.clone())),
             _timeout: dur,
             reply: reply_rx,
@@ -456,3 +465,61 @@ fn server_keep_alive() {
         }
     }
 }
+
+#[test]
+fn test_server_disable_keep_alive() {
+  let foo_bar = b"foo bar baz";
+    let server = serve_with_options(ServeOptions {
+        keep_alive_disabled: true,
+        .. Default::default()
+    });
+    server.reply()
+        .status(hyper::Ok)
+        .header(hyper::header::ContentLength(foo_bar.len() as u64))
+        .body(foo_bar);
+    let mut req = connect(server.addr());
+    req.write_all(b"\
+        GET / HTTP/1.1\r\n\
+        Host: example.domain\r\n\
+        Connection: keep-alive\r\n\
+        \r\n\
+    ").expect("writing 1");
+
+    let mut buf = [0; 1024 * 8];
+    loop {
+        let n = req.read(&mut buf[..]).expect("reading 1");
+        if n < buf.len() {
+            if &buf[n - foo_bar.len()..n] == foo_bar {
+                break;
+            } else {
+            }
+        }
+    }
+
+    // try again!
+
+    let quux = b"zar quux";
+    server.reply()
+        .status(hyper::Ok)
+        .header(hyper::header::ContentLength(quux.len() as u64))
+        .body(quux);
+    
+    let _ = req.write_all(b"\
+        GET /quux HTTP/1.1\r\n\
+        Host: example.domain\r\n\
+        Connection: close\r\n\
+        \r\n\
+    ");
+
+    // the write can possibly succeed, since it fills the kernel buffer on the first write
+    let mut buf = [0; 1024 * 8];
+    match req.read(&mut buf[..]) {
+        // Ok(0) means EOF, so a proper shutdown
+        // Err(_) could mean ConnReset or something, also fine
+        Ok(0) |
+        Err(_) => {}
+        Ok(n) => {
+            panic!("read {} bytes on a disabled keep-alive socket", n);
+        }
+    }
+}