agent/http: Update TestSetupHTTPServer_HTTP2

To remove the need to store the http.Server. This will allow us to
remove the http.Server field from the HTTPServer struct.

agent/agent.go

@@ -1168,29 +1168,7 @@ func (a *Agent) listenHTTP() ([]*HTTPServer, error) {
 			connLimitFn := a.httpConnLimiter.HTTPConnStateFunc()
 
 			if proto == "https" {
-				// Enforce TLS handshake timeout
-				httpServer.ConnState = func(conn net.Conn, state http.ConnState) {
-					switch state {
-					case http.StateNew:
-						// Set deadline to prevent slow send before TLS handshake or first
-						// byte of request.
-						conn.SetReadDeadline(time.Now().Add(a.config.HTTPSHandshakeTimeout))
-					case http.StateActive:
-						// Clear read deadline. We should maybe set read timeouts more
-						// generally but that's a bigger task as some HTTP endpoints may
-						// stream large requests and responses (e.g. snapshot) so we can't
-						// set sensible blanket timeouts here.
-						conn.SetReadDeadline(time.Time{})
-					}
-					// Pass through to conn limit. This is OK because we didn't change
-					// state (i.e. Close conn).
-					connLimitFn(conn, state)
-				}
-
-				// This will enable upgrading connections to HTTP/2 as
-				// part of TLS negotiation.
-				err = http2.ConfigureServer(httpServer, nil)
-				if err != nil {
+				if err := setupHTTPS(httpServer, connLimitFn, a.config.HTTPSHandshakeTimeout); err != nil {
 					return err
 				}
 			} else {
@@ -1218,6 +1196,33 @@ func (a *Agent) listenHTTP() ([]*HTTPServer, error) {
 	return servers, nil
 }
 
+// setupHTTPS adds HTTP/2 support, ConnState, and a connection handshake timeout
+// to the http.Server.
+func setupHTTPS(server *http.Server, connState func(net.Conn, http.ConnState), timeout time.Duration) error {
+	// Enforce TLS handshake timeout
+	server.ConnState = func(conn net.Conn, state http.ConnState) {
+		switch state {
+		case http.StateNew:
+			// Set deadline to prevent slow send before TLS handshake or first
+			// byte of request.
+			conn.SetReadDeadline(time.Now().Add(timeout))
+		case http.StateActive:
+			// Clear read deadline. We should maybe set read timeouts more
+			// generally but that's a bigger task as some HTTP endpoints may
+			// stream large requests and responses (e.g. snapshot) so we can't
+			// set sensible blanket timeouts here.
+			conn.SetReadDeadline(time.Time{})
+		}
+		// Pass through to conn limit. This is OK because we didn't change
+		// state (i.e. Close conn).
+		connState(conn, state)
+	}
+
+	// This will enable upgrading connections to HTTP/2 as
+	// part of TLS negotiation.
+	return http2.ConfigureServer(server, nil)
+}
+
 // tcpKeepAliveListener sets TCP keep-alive timeouts on accepted
 // connections. It's used so dead TCP connections eventually go away.
 type tcpKeepAliveListener struct {

agent/http_test.go

@@ -3,6 +3,7 @@ package agent
 import (
 	"bytes"
 	"context"
+	"crypto/tls"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -129,7 +130,7 @@ func TestHTTPServer_UnixSocket_FileExists(t *testing.T) {
 	}
 }
 
-func TestHTTPServer_HTTP2(t *testing.T) {
+func TestSetupHTTPServer_HTTP2(t *testing.T) {
 	t.Parallel()
 
 	// Fire up an agent with TLS enabled.
@@ -169,14 +170,28 @@ func TestHTTPServer_HTTP2(t *testing.T) {
 		fmt.Fprint(resp, req.Proto)
 	}
 
-	w, ok := a.srv.Server.Handler.(*wrappedMux)
-	if !ok {
-		t.Fatalf("handler is not expected type")
-	}
-	w.mux.HandleFunc("/echo", handler)
+	// Create an httpServer to be configured with setupHTTPS, and add our
+	// custom handler.
+	httpServer := &http.Server{}
+	noopConnState := func(net.Conn, http.ConnState) {}
+	err = setupHTTPS(httpServer, noopConnState, time.Second)
+	require.NoError(t, err)
+
+	srvHandler := a.srv.handler(true)
+	mux, ok := srvHandler.(*wrappedMux)
+	require.True(t, ok, "expected a *wrappedMux, got %T", handler)
+	mux.mux.HandleFunc("/echo", handler)
+	httpServer.Handler = mux
+
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	require.NoError(t, err)
+	tlsListener := tls.NewListener(listener, a.tlsConfigurator.IncomingHTTPSConfig())
+
+	go httpServer.Serve(tlsListener)
+	defer httpServer.Shutdown(context.Background())
 
 	// Call it and make sure we see HTTP/2.
-	url := fmt.Sprintf("https://%s/echo", a.srv.ln.Addr().String())
+	url := fmt.Sprintf("https://%s/echo", listener.Addr().String())
 	resp, err := httpClient.Get(url)
 	if err != nil {
 		t.Fatalf("err: %v", err)
@@ -194,7 +209,7 @@ func TestHTTPServer_HTTP2(t *testing.T) {
 	// some other endpoint, but configure an API client and make a call
 	// just as a sanity check.
 	cfg := &api.Config{
-		Address:    a.srv.ln.Addr().String(),
+		Address:    listener.Addr().String(),
 		Scheme:     "https",
 		HttpClient: httpClient,
 	}