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 = err
-		c.err = E.Cause(err, "dial tcp fast open")
+	} else {
+		c.conn = conn
 	}
 	n = len(b)
 	close(c.create)

route/dns.go

@@ -31,7 +31,7 @@ func (r *Router) hijackDNSStream(ctx context.Context, conn net.Conn, metadata ad
 	}
 }
 
-func (r *Router) hijackDNSPacket(ctx context.Context, conn N.PacketConn, packetBuffers []*N.PacketBuffer, metadata adapter.InboundContext) {
+func (r *Router) hijackDNSPacket(ctx context.Context, conn N.PacketConn, packetBuffers []*N.PacketBuffer, metadata adapter.InboundContext, onClose N.CloseHandlerFunc) {
 	if natConn, isNatConn := conn.(udpnat.Conn); isNatConn {
 		metadata.Destination = M.Socksaddr{}
 		for _, packet := range packetBuffers {
@@ -45,10 +45,12 @@ func (r *Router) hijackDNSPacket(ctx context.Context, conn N.PacketConn, packetB
 			conn:     conn,
 			ctx:      ctx,
 			metadata: metadata,
+			onClose:  onClose,
 		})
 		return
 	}
 	err := dnsOutbound.NewDNSPacketConnection(ctx, r, conn, packetBuffers, metadata)
+	N.CloseOnHandshakeFailure(conn, onClose, err)
 	if err != nil && !E.IsClosedOrCanceled(err) {
 		r.dnsLogger.ErrorContext(ctx, E.Cause(err, "process packet connection"))
 	}
@@ -85,8 +87,16 @@ type dnsHijacker struct {
 	conn     N.PacketConn
 	ctx      context.Context
 	metadata adapter.InboundContext
+	onClose  N.CloseHandlerFunc
 }
 
 func (h *dnsHijacker) NewPacketEx(buffer *buf.Buffer, destination M.Socksaddr) {
 	go ExchangeDNSPacket(h.ctx, h.router, h.conn, buffer, h.metadata, destination)
 }
+
+func (h *dnsHijacker) Close() error {
+	if h.onClose != nil {
+		h.onClose(nil)
+	}
+	return nil
+}

route/route.go

@@ -120,7 +120,7 @@ func (r *Router) routeConnection(ctx context.Context, conn net.Conn, metadata ad
 			for _, buffer := range buffers {
 				conn = bufio.NewCachedConn(conn, buffer)
 			}
-			r.hijackDNSStream(ctx, conn, metadata)
+			N.CloseOnHandshakeFailure(conn, onClose, r.hijackDNSStream(ctx, conn, metadata))
 			return nil
 		}
 	}
@@ -233,7 +233,7 @@ func (r *Router) routePacketConnection(ctx context.Context, conn N.PacketConn, m
 			N.CloseOnHandshakeFailure(conn, onClose, action.Error(ctx))
 			return nil
 		case *rule.RuleActionHijackDNS:
-			r.hijackDNSPacket(ctx, conn, packetBuffers, metadata)
+			r.hijackDNSPacket(ctx, conn, packetBuffers, metadata, onClose)
 			return nil
 		}
 	}