Refactor: HTTP clients, unified HTTP2/QUIC options, Apple engines

common/dialer/detour.go

@@ -19,6 +19,7 @@ type DirectDialer interface {
 type DetourDialer struct {
 	outboundManager adapter.OutboundManager
 	detour          string
+	defaultOutbound bool
 	legacyDNSDialer bool
 	dialer          N.Dialer
 	initOnce        sync.Once
@@ -33,6 +34,13 @@ func NewDetour(outboundManager adapter.OutboundManager, detour string, legacyDNS
 	}
 }
 
+func NewDefaultOutboundDetour(outboundManager adapter.OutboundManager) N.Dialer {
+	return &DetourDialer{
+		outboundManager: outboundManager,
+		defaultOutbound: true,
+	}
+}
+
 func InitializeDetour(dialer N.Dialer) error {
 	detourDialer, isDetour := common.Cast[*DetourDialer](dialer)
 	if !isDetour {
@@ -47,12 +55,18 @@ func (d *DetourDialer) Dialer() (N.Dialer, error) {
 }
 
 func (d *DetourDialer) init() {
-	dialer, loaded := d.outboundManager.Outbound(d.detour)
-	if !loaded {
-		d.initErr = E.New("outbound detour not found: ", d.detour)
-		return
+	var dialer adapter.Outbound
+	if d.detour != "" {
+		var loaded bool
+		dialer, loaded = d.outboundManager.Outbound(d.detour)
+		if !loaded {
+			d.initErr = E.New("outbound detour not found: ", d.detour)
+			return
+		}
+	} else {
+		dialer = d.outboundManager.Default()
 	}
-	if !d.legacyDNSDialer {
+	if !d.defaultOutbound && !d.legacyDNSDialer {
 		if directDialer, isDirect := dialer.(DirectDialer); isDirect {
 			if directDialer.IsEmpty() {
 				d.initErr = E.New("detour to an empty direct outbound makes no sense")

common/dialer/dialer.go

@@ -25,6 +25,7 @@ type Options struct {
 	NewDialer        bool
 	LegacyDNSDialer  bool
 	DirectOutbound   bool
+	DefaultOutbound  bool
 }
 
 // TODO: merge with NewWithOptions
@@ -42,19 +43,26 @@ func NewWithOptions(options Options) (N.Dialer, error) {
 		dialer N.Dialer
 		err    error
 	)
+	hasDetour := dialOptions.Detour != "" || options.DefaultOutbound
 	if dialOptions.Detour != "" {
 		outboundManager := service.FromContext[adapter.OutboundManager](options.Context)
 		if outboundManager == nil {
 			return nil, E.New("missing outbound manager")
 		}
 		dialer = NewDetour(outboundManager, dialOptions.Detour, options.LegacyDNSDialer)
+	} else if options.DefaultOutbound {
+		outboundManager := service.FromContext[adapter.OutboundManager](options.Context)
+		if outboundManager == nil {
+			return nil, E.New("missing outbound manager")
+		}
+		dialer = NewDefaultOutboundDetour(outboundManager)
 	} else {
 		dialer, err = NewDefault(options.Context, dialOptions)
 		if err != nil {
 			return nil, err
 		}
 	}
-	if options.RemoteIsDomain && (dialOptions.Detour == "" || options.ResolverOnDetour || dialOptions.DomainResolver != nil && dialOptions.DomainResolver.Server != "") {
+	if options.RemoteIsDomain && (!hasDetour || options.ResolverOnDetour || dialOptions.DomainResolver != nil && dialOptions.DomainResolver.Server != "") {
 		networkManager := service.FromContext[adapter.NetworkManager](options.Context)
 		dnsTransport := service.FromContext[adapter.DNSTransportManager](options.Context)
 		var defaultOptions adapter.NetworkOptions