Add outbound sniff option

adapter/outbound.go

@@ -19,6 +19,11 @@ type Outbound interface {
 	NewPacketConnection(ctx context.Context, conn N.PacketConn, metadata InboundContext) error
 }
 
+type SniffOutbound interface {
+	Outbound
+	UseSniffedDestination() bool
+}
+
 type IPOutbound interface {
 	Outbound
 	NewIPConnection(ctx context.Context, conn tun.RouteContext, metadata InboundContext) (tun.DirectDestination, error)

docs/configuration/outbound/socks.md

@@ -14,6 +14,7 @@
   "password": "admin",
   "network": "udp",
   "udp_over_tcp": false | {},
+  "use_sniffed_destination": false
 
   ... // Dial Fields
 }
@@ -61,6 +62,10 @@ UDP over TCP protocol settings.
 
 See [UDP Over TCP](/configuration/shared/udp-over-tcp) for details.
 
+#### use_sniffed_destination
+
+When an inbound request is routed to the outbound, the detected domain name will be used to override the connection target address before establishing a connection. This option is only effective when `sniff` is set to `true` and `sniff_override_destination` is `false` in the inbound.
+
 ### Dial Fields
 
 See [Dial Fields](/configuration/shared/dial) for details.

docs/configuration/outbound/socks.zh.md

@@ -14,6 +14,7 @@
   "password": "admin",
   "network": "udp",
   "udp_over_tcp": false | {},
+  "use_sniffed_destination": false
 
   ... // 拨号字段
 }
@@ -61,6 +62,10 @@ UDP over TCP 配置。
 
 参阅 [UDP Over TCP](/zh/configuration/shared/udp-over-tcp)。
 
+#### use_sniffed_destination
+
+当入站请求路由到该出站时，在建立连接前会用探测出的域名覆盖连接目标地址，仅当入站设置了`sniff`为`true`同时`sniff_override_destination`为`false`时该选项有效。
+
 ### 拨号字段
 
 参阅 [拨号字段](/zh/configuration/shared/dial/)。

option/outbound.go

@@ -144,6 +144,10 @@ func (o ServerOptions) Build() M.Socksaddr {
 	return M.ParseSocksaddrHostPort(o.Server, o.ServerPort)
 }
 
+type SniffOptions struct {
+	UseSniffedDestination bool `json:"use_sniffed_destination,omitempty"`
+}
+
 type MultiplexOptions struct {
 	Enabled        bool   `json:"enabled,omitempty"`
 	Protocol       string `json:"protocol,omitempty"`

option/simple.go

@@ -17,6 +17,7 @@ type HTTPMixedInboundOptions struct {
 type SocksOutboundOptions struct {
 	DialerOptions
 	ServerOptions
+	SniffOptions
 	Version           string             `json:"version,omitempty"`
 	Username          string             `json:"username,omitempty"`
 	Password          string             `json:"password,omitempty"`

outbound/socks.go

@@ -17,13 +17,18 @@ import (
 	"github.com/sagernet/sing/protocol/socks"
 )
 
-var _ adapter.Outbound = (*Socks)(nil)
+var _ adapter.SniffOutbound = (*Socks)(nil)
 
 type Socks struct {
 	myOutboundAdapter
-	client    *socks.Client
+	client                *socks.Client
-	resolve   bool
+	resolve               bool
-	uotClient *uot.Client
+	uotClient             *uot.Client
+	useSniffedDestination bool
+}
+
+func (h *Socks) UseSniffedDestination() bool {
+	return h.useSniffedDestination
 }
 
 func NewSocks(router adapter.Router, logger log.ContextLogger, tag string, options option.SocksOutboundOptions) (*Socks, error) {
@@ -45,8 +50,9 @@ func NewSocks(router adapter.Router, logger log.ContextLogger, tag string, optio
 			logger:   logger,
 			tag:      tag,
 		},
-		client:  socks.NewClient(dialer.New(router, options.DialerOptions), options.ServerOptions.Build(), version, options.Username, options.Password),
+		client:                socks.NewClient(dialer.New(router, options.DialerOptions), options.ServerOptions.Build(), version, options.Username, options.Password),
-		resolve: version == socks.Version4,
+		resolve:               version == socks.Version4,
+		useSniffedDestination: options.UseSniffedDestination,
 	}
 	uotOptions := common.PtrValueOrDefault(options.UDPOverTCPOptions)
 	if uotOptions.Enabled {

route/router.go

@@ -657,6 +657,7 @@ func (r *Router) RouteConnection(ctx context.Context, conn net.Conn, metadata ad
 		r.logger.DebugContext(ctx, "found fakeip domain: ", domain)
 	}
 
+	var sniffedDestination M.Socksaddr
 	if metadata.InboundOptions.SniffEnabled {
 		buffer := buf.NewPacket()
 		buffer.FullReset()
@@ -664,11 +665,14 @@ func (r *Router) RouteConnection(ctx context.Context, conn net.Conn, metadata ad
 		if sniffMetadata != nil {
 			metadata.Protocol = sniffMetadata.Protocol
 			metadata.Domain = sniffMetadata.Domain
-			if metadata.InboundOptions.SniffOverrideDestination && M.IsDomainName(metadata.Domain) {
+			if M.IsDomainName(metadata.Domain) {
-				metadata.Destination = M.Socksaddr{
+				sniffedDestination = M.Socksaddr{
 					Fqdn: metadata.Domain,
 					Port: metadata.Destination.Port,
 				}
+				if metadata.InboundOptions.SniffOverrideDestination {
+					metadata.Destination = sniffedDestination
+				}
 			}
 			if metadata.Domain != "" {
 				r.logger.DebugContext(ctx, "sniffed protocol: ", metadata.Protocol, ", domain: ", metadata.Domain)
@@ -706,6 +710,13 @@ func (r *Router) RouteConnection(ctx context.Context, conn net.Conn, metadata ad
 	if !common.Contains(detour.Network(), N.NetworkTCP) {
 		return E.New("missing supported outbound, closing connection")
 	}
+	if metadata.InboundOptions.SniffEnabled && !metadata.InboundOptions.SniffOverrideDestination && sniffedDestination.IsValid() {
+		sniffOutbound, loaded := detour.(adapter.SniffOutbound)
+		if loaded && sniffOutbound.UseSniffedDestination() {
+			r.logger.DebugContext(ctx, "use sniffed destination, detor: ", detour.Tag(), ", domain: ", metadata.Domain)
+			metadata.Destination = sniffedDestination
+		}
+	}
 	if r.clashServer != nil {
 		trackerConn, tracker := r.clashServer.RoutedConnection(ctx, conn, metadata, matchedRule)
 		defer tracker.Leave()
@@ -760,6 +771,7 @@ func (r *Router) RoutePacketConnection(ctx context.Context, conn N.PacketConn, m
 		r.logger.DebugContext(ctx, "found fakeip domain: ", domain)
 	}
 
+	var sniffedDestination M.Socksaddr
 	if metadata.InboundOptions.SniffEnabled {
 		buffer := buf.NewPacket()
 		buffer.FullReset()
@@ -772,11 +784,14 @@ func (r *Router) RoutePacketConnection(ctx context.Context, conn N.PacketConn, m
 		if sniffMetadata != nil {
 			metadata.Protocol = sniffMetadata.Protocol
 			metadata.Domain = sniffMetadata.Domain
-			if metadata.InboundOptions.SniffOverrideDestination && M.IsDomainName(metadata.Domain) {
+			if M.IsDomainName(metadata.Domain) {
-				metadata.Destination = M.Socksaddr{
+				sniffedDestination = M.Socksaddr{
 					Fqdn: metadata.Domain,
 					Port: metadata.Destination.Port,
 				}
+				if metadata.InboundOptions.SniffOverrideDestination {
+					metadata.Destination = sniffedDestination
+				}
 			}
 			if metadata.Domain != "" {
 				r.logger.DebugContext(ctx, "sniffed packet protocol: ", metadata.Protocol, ", domain: ", metadata.Domain)
@@ -808,6 +823,13 @@ func (r *Router) RoutePacketConnection(ctx context.Context, conn N.PacketConn, m
 	if !common.Contains(detour.Network(), N.NetworkUDP) {
 		return E.New("missing supported outbound, closing packet connection")
 	}
+	if metadata.InboundOptions.SniffEnabled && !metadata.InboundOptions.SniffOverrideDestination && sniffedDestination.IsValid() {
+		sniffOutbound, loaded := detour.(adapter.SniffOutbound)
+		if loaded && sniffOutbound.UseSniffedDestination() {
+			r.logger.DebugContext(ctx, "use sniffed destination, detor: ", detour.Tag(), ", domain: ", metadata.Domain)
+			metadata.Destination = sniffedDestination
+		}
+	}
 	if r.clashServer != nil {
 		trackerConn, tracker := r.clashServer.RoutedPacketConnection(ctx, conn, metadata, matchedRule)
 		defer tracker.Leave()