Add DialErrorResponse func

api/buf.lock

@@ -4,7 +4,4 @@ deps:
   - remote: buf.build
     owner: googleapis
     repository: googleapis
-    branch: main
-    commit: c348fb6ca1774f95bdabe20c7b379d50
-    digest: b1-liJZ9g7gOLHZca7G3Fu-Z4-9VKgrE3ci0lXsuG8hsVY=
-    create_time: 2022-03-17T15:04:57.656498Z
+    commit: d1263fe26f8e430a967dc22a4d0cad18

ws/client.go

@@ -3,11 +3,9 @@ package ws
 import (
 	"context"
 	"errors"
-	"fmt"
 	"io"
 	"net/http"
 
-	"google.golang.org/grpc/metadata"
 	"nhooyr.io/websocket"
 	"nhooyr.io/websocket/wspb"
 
@@ -30,6 +28,7 @@ type ClientOptions struct {
 type HandshakeResponse func(ctx context.Context, res *http.Response) (context.Context, error)
 
 // Tunnel implements connect.Tunneler and creates a connection over a WebSocket.
+// On error a http.Response may be provided by DialErrorResponse.
 func (o ClientOptions) Tunnel(ctx context.Context) (connect.Tunnel, error) {
 	ctx, ws, err := o.dial(ctx)
 	if err != nil {
@@ -51,6 +50,7 @@ func (o ClientOptions) Tunnel(ctx context.Context) (connect.Tunnel, error) {
 }
 
 // Watch implements connect.Watcher and watches for session proposals.
+// On error a http.Response may be provided by DialErrorResponse.
 func (o ClientOptions) Watch(ctx context.Context, propose connect.ReceiveProposal) error {
 	ctx, ws, err := o.dial(ctx)
 	if err != nil {
@@ -90,41 +90,5 @@ func (o ClientOptions) Watch(ctx context.Context, propose connect.ReceiveProposa
 	return err
 }
 
-func (o *ClientOptions) dial(ctx context.Context) (context.Context, *websocket.Conn, error) {
-	if o.URL == "" {
-		return nil, nil, errors.New("missing websocket url")
-	}
-
-	// Add metadata to websocket handshake request header
-	md, _ := metadata.FromOutgoingContext(ctx)
-	if o.DialOptions.HTTPHeader == nil {
-		o.DialOptions.HTTPHeader = http.Header(md)
-	} else {
-		header := metadata.Join(metadata.MD(o.DialOptions.HTTPHeader), md)
-		o.DialOptions.HTTPHeader = http.Header(header)
-	}
-
-	// Dial service
-	if o.DialContext == nil {
-		o.DialContext = ctx
-	}
-	ws, res, err := websocket.Dial(o.DialContext, o.URL, &o.DialOptions)
-	if err != nil {
-		return nil, nil, fmt.Errorf("error handshaking with websocket server: %w", err)
-	}
-
-	// Callback for handshake response
-	if o.Handshake != nil {
-		ctx, err = o.Handshake(ctx, res)
-		if err != nil {
-			_ = ws.Close(websocket.StatusNormalClosure, fmt.Sprintf(
-				"handshake response rejected: %v", err))
-			return nil, nil, err
-		}
-	}
-
-	return ctx, ws, nil
-}
-
 var _ connect.Tunneler = (*ClientOptions)(nil)
 var _ connect.Watcher = (*ClientOptions)(nil)

ws/dial.go

@@ -0,0 +1,77 @@
+package ws
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/http"
+
+	"google.golang.org/grpc/metadata"
+	"nhooyr.io/websocket"
+)
+
+// DialErrorResponse returns the HTTP response from the WebSocket handshake error, if any.
+func DialErrorResponse(err error) (*http.Response, bool) {
+	var e *dialErr
+	if errors.As(err, &e) {
+		return e.res, true
+	}
+	return nil, false
+}
+
+func (o *ClientOptions) dial(ctx context.Context) (context.Context, *websocket.Conn, error) {
+	if o.URL == "" {
+		return nil, nil, errors.New("missing websocket url")
+	}
+
+	header := metadata.Join(
+		metadata.MD(o.DialOptions.HTTPHeader),
+		mdFromContext(o.DialContext),
+		mdFromContext(ctx),
+	)
+	if o.DialContext != nil {
+		ctx = o.DialContext
+	}
+
+	// Dial service
+	ws, res, err := websocket.Dial(ctx, o.URL, &websocket.DialOptions{
+		HTTPClient:           o.DialOptions.HTTPClient,
+		HTTPHeader:           http.Header(header),
+		Subprotocols:         o.DialOptions.Subprotocols,
+		CompressionMode:      o.DialOptions.CompressionMode,
+		CompressionThreshold: o.DialOptions.CompressionThreshold,
+	})
+	if err != nil {
+		if res != nil {
+			err = &dialErr{error: err, res: res}
+		}
+		return nil, nil, fmt.Errorf("error handshaking with websocket server: %w", err)
+	}
+
+	// Callback for handshake response
+	if o.Handshake != nil {
+		ctx, err = o.Handshake(ctx, res)
+		if err != nil {
+			_ = ws.Close(websocket.StatusNormalClosure, fmt.Sprintf(
+				"handshake response rejected: %v", err))
+			return nil, nil, err
+		}
+	}
+
+	return ctx, ws, nil
+}
+
+type dialErr struct {
+	error
+	res *http.Response
+}
+
+func (e *dialErr) Error() string {
+	return fmt.Sprintf("%s (%d): %v", e.res.Status, e.res.StatusCode, e.error)
+}
+func (e *dialErr) Unwrap() error { return e.error }
+
+func mdFromContext(ctx context.Context) metadata.MD {
+	md, _ := metadata.FromOutgoingContext(ctx)
+	return md
+}