net/http: add Server.DisableOptionsHandler for custom handling of OPTIONS *

Fixes #41773

Change-Id: I432ad5410d5e3bb0aff3a6e0eea6906ab1b214e2
GitHub-Last-Rev: 57d1ee249d
GitHub-Pull-Request: golang/go#49014
Reviewed-on: https://go-review.googlesource.com/c/go/+/356410
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: hopehook <hopehook@qq.com>
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

api/next/41773.txt

@@ -0,0 +1 @@
+pkg net/http, type Server struct, DisableGeneralOptionsHandler bool #41773

src/net/http/serve_test.go

@@ -3492,6 +3492,37 @@ func TestOptions(t *testing.T) {
 	}
 }
 
+func TestOptionsHandler(t *testing.T) {
+	rc := make(chan *Request, 1)
+
+	ts := httptest.NewUnstartedServer(HandlerFunc(func(w ResponseWriter, r *Request) {
+		rc <- r
+	}))
+	ts.Config.DisableGeneralOptionsHandler = true
+	ts.Start()
+	defer ts.Close()
+
+	conn, err := net.Dial("tcp", ts.Listener.Addr().String())
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer conn.Close()
+
+	_, err = conn.Write([]byte("OPTIONS * HTTP/1.1\r\nHost: foo.com\r\n\r\n"))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	select {
+	case got := <-rc:
+		if got.Method != "OPTIONS" || got.RequestURI != "*" {
+			t.Errorf("Expected OPTIONS * request, got %v", got)
+		}
+	case <-time.After(5 * time.Second):
+		t.Error("timeout")
+	}
+}
+
 // Tests regarding the ordering of Write, WriteHeader, Header, and
 // Flush calls. In Go 1.0, rw.WriteHeader immediately flushed the
 // (*response).header to the wire. In Go 1.1, the actual wire flush is

src/net/http/server.go

@@ -2584,6 +2584,10 @@ type Server struct {
 
 	Handler Handler // handler to invoke, http.DefaultServeMux if nil
 
+	// DisableGeneralOptionsHandler, if true, passes "OPTIONS *" requests to the Handler,
+	// otherwise responds with 200 OK and Content-Length: 0.
+	DisableGeneralOptionsHandler bool
+
 	// TLSConfig optionally provides a TLS configuration for use
 	// by ServeTLS and ListenAndServeTLS. Note that this value is
 	// cloned by ServeTLS and ListenAndServeTLS, so it's not
@@ -2916,7 +2920,7 @@ func (sh serverHandler) ServeHTTP(rw ResponseWriter, req *Request) {
 	if handler == nil {
 		handler = DefaultServeMux
 	}
-	if req.RequestURI == "*" && req.Method == "OPTIONS" {
+	if !sh.srv.DisableGeneralOptionsHandler && req.RequestURI == "*" && req.Method == "OPTIONS" {
 		handler = globalOptionsHandler{}
 	}