accept: Add unwrapping for hijack like http.ResponseController

accept.go

@@ -105,7 +105,7 @@ func accept(w http.ResponseWriter, r *http.Request, opts *AcceptOptions) (_ *Con
 		}
 	}
 
-	hj, ok := w.(http.Hijacker)
+	hj, ok := hijacker(w)
 	if !ok {
 		err = errors.New("http.ResponseWriter does not implement http.Hijacker")
 		http.Error(w, http.StatusText(http.StatusNotImplemented), http.StatusNotImplemented)

accept_test.go

@@ -143,6 +143,33 @@ func TestAccept(t *testing.T) {
 		_, err := Accept(w, r, nil)
 		assert.Contains(t, err, `failed to hijack connection`)
 	})
+
+	t.Run("wrapperHijackerIsUnwrapped", func(t *testing.T) {
+		t.Parallel()
+
+		rr := httptest.NewRecorder()
+		w := mockUnwrapper{
+			ResponseWriter: rr,
+			unwrap: func() http.ResponseWriter {
+				return mockHijacker{
+					ResponseWriter: rr,
+					hijack: func() (conn net.Conn, writer *bufio.ReadWriter, err error) {
+						return nil, nil, errors.New("haha")
+					},
+				}
+			},
+		}
+
+		r := httptest.NewRequest("GET", "/", nil)
+		r.Header.Set("Connection", "Upgrade")
+		r.Header.Set("Upgrade", "websocket")
+		r.Header.Set("Sec-WebSocket-Version", "13")
+		r.Header.Set("Sec-WebSocket-Key", xrand.Base64(16))
+
+		_, err := Accept(w, r, nil)
+		assert.Contains(t, err, "failed to hijack connection")
+	})
+
 	t.Run("closeRace", func(t *testing.T) {
 		t.Parallel()
 
@@ -534,3 +561,14 @@ var _ http.Hijacker = mockHijacker{}
 func (mj mockHijacker) Hijack() (net.Conn, *bufio.ReadWriter, error) {
 	return mj.hijack()
 }
+
+type mockUnwrapper struct {
+	http.ResponseWriter
+	unwrap func() http.ResponseWriter
+}
+
+var _ rwUnwrapper = mockUnwrapper{}
+
+func (mu mockUnwrapper) Unwrap() http.ResponseWriter {
+	return mu.unwrap()
+}

hijack.go

@@ -0,0 +1,33 @@
+//go:build !js
+
+package websocket
+
+import (
+	"net/http"
+)
+
+type rwUnwrapper interface {
+	Unwrap() http.ResponseWriter
+}
+
+// hijacker returns the Hijacker interface of the http.ResponseWriter.
+// It follows the Unwrap method of the http.ResponseWriter if available,
+// matching the behavior of http.ResponseController. If the Hijacker
+// interface is not found, it returns false.
+//
+// Since the http.ResponseController is not available in Go 1.19, and
+// does not support checking the presence of the Hijacker interface,
+// this function is used to provide a consistent way to check for the
+// Hijacker interface across Go versions.
+func hijacker(rw http.ResponseWriter) (http.Hijacker, bool) {
+	for {
+		switch t := rw.(type) {
+		case http.Hijacker:
+			return t, true
+		case rwUnwrapper:
+			rw = t.Unwrap()
+		default:
+			return nil, false
+		}
+	}
+}

hijack_go120_test.go

@@ -0,0 +1,38 @@
+//go:build !js && go1.20
+
+package websocket
+
+import (
+	"bufio"
+	"errors"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/coder/websocket/internal/test/assert"
+)
+
+func Test_hijackerHTTPResponseControllerCompatibility(t *testing.T) {
+	t.Parallel()
+
+	rr := httptest.NewRecorder()
+	w := mockUnwrapper{
+		ResponseWriter: rr,
+		unwrap: func() http.ResponseWriter {
+			return mockHijacker{
+				ResponseWriter: rr,
+				hijack: func() (conn net.Conn, writer *bufio.ReadWriter, err error) {
+					return nil, nil, errors.New("haha")
+				},
+			}
+		},
+	}
+
+	_, _, err := http.NewResponseController(w).Hijack()
+	assert.Contains(t, err, "haha")
+	hj, ok := hijacker(w)
+	assert.Equal(t, "hijacker found", ok, true)
+	_, _, err = hj.Hijack()
+	assert.Contains(t, err, "haha")
+}