Fix default network strategy

common/dialer/default.go

@@ -100,10 +100,6 @@ func NewDefault(ctx context.Context, options option.DialerOptions) (*DefaultDial
 			} else if networkManager.AutoDetectInterface() {
 				if platformInterface != nil {
 					networkStrategy = (*C.NetworkStrategy)(options.NetworkStrategy)
-					if networkStrategy == nil {
-						networkStrategy = common.Ptr(C.NetworkStrategyDefault)
-						defaultNetworkStrategy = true
-					}
 					networkType = common.Map(options.NetworkType, option.InterfaceType.Build)
 					fallbackNetworkType = common.Map(options.FallbackNetworkType, option.InterfaceType.Build)
 					if networkStrategy == nil && len(networkType) == 0 && len(fallbackNetworkType) == 0 {
@@ -115,6 +111,10 @@ func NewDefault(ctx context.Context, options option.DialerOptions) (*DefaultDial
 					if networkFallbackDelay == 0 && defaultOptions.FallbackDelay != 0 {
 						networkFallbackDelay = defaultOptions.FallbackDelay
 					}
+					if networkStrategy == nil {
+						networkStrategy = common.Ptr(C.NetworkStrategyDefault)
+						defaultNetworkStrategy = true
+					}
 					bindFunc := networkManager.ProtectFunc()
 					dialer.Control = control.Append(dialer.Control, bindFunc)
 					listener.Control = control.Append(listener.Control, bindFunc)

common/dialer/tfo.go

@@ -12,7 +12,6 @@ import (
 
 	"github.com/sagernet/sing/common"
 	"github.com/sagernet/sing/common/bufio"
-	E "github.com/sagernet/sing/common/exceptions"
 	M "github.com/sagernet/sing/common/metadata"
 	N "github.com/sagernet/sing/common/network"
 
@@ -76,10 +75,11 @@ func (c *slowOpenConn) Write(b []byte) (n int, err error) {
 		return c.conn.Write(b)
 	default:
 	}
-	c.conn, err = c.dialer.DialContext(c.ctx, c.network, c.destination.String(), b)
+	conn, err := c.dialer.DialContext(c.ctx, c.network, c.destination.String(), b)
 	if err != nil {
-		c.conn = nil
-		c.err = E.Cause(err, "dial tcp fast open")
+		c.err = err
+	} else {
+		c.conn = conn
 	}
 	n = len(b)
 	close(c.create)