Loopback outbound: Add sniffing (#6326)

Example: https://github.com/XTLS/Xray-core/pull/6326#issue-4659701786

infra/conf/loopback.go

@@ -1,14 +1,24 @@
 package conf
 
 import (
+	"github.com/xtls/xray-core/common/errors"
 	"github.com/xtls/xray-core/proxy/loopback"
 	"google.golang.org/protobuf/proto"
 )
 
 type LoopbackConfig struct {
-	InboundTag string `json:"inboundTag"`
+	InboundTag string          `json:"inboundTag"`
+	Sniffing   *SniffingConfig `json:"sniffing"`
 }
 
 func (l LoopbackConfig) Build() (proto.Message, error) {
-	return &loopback.Config{InboundTag: l.InboundTag}, nil
+	c := &loopback.Config{InboundTag: l.InboundTag}
+	if l.Sniffing != nil {
+		sc, err := l.Sniffing.Build()
+		if err != nil {
+			return nil, errors.New("failed to build sniffing config").Base(err)
+		}
+		c.Sniffing = sc
+	}
+	return c, nil
 }

proxy/loopback/config.pb.go

@@ -7,6 +7,7 @@
 package loopback
 
 import (
+	proxyman "github.com/xtls/xray-core/app/proxyman"
 	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
 	reflect "reflect"
@@ -22,8 +23,9 @@ const (
 )
 
 type Config struct {
-	state         protoimpl.MessageState `protogen:"open.v1"`
-	InboundTag    string                 `protobuf:"bytes,1,opt,name=inbound_tag,json=inboundTag,proto3" json:"inbound_tag,omitempty"`
+	state         protoimpl.MessageState   `protogen:"open.v1"`
+	InboundTag    string                   `protobuf:"bytes,1,opt,name=inbound_tag,json=inboundTag,proto3" json:"inbound_tag,omitempty"`
+	Sniffing      *proxyman.SniffingConfig `protobuf:"bytes,2,opt,name=sniffing,proto3" json:"sniffing,omitempty"`
 	unknownFields protoimpl.UnknownFields
 	sizeCache     protoimpl.SizeCache
 }
@@ -65,14 +67,22 @@ func (x *Config) GetInboundTag() string {
 	return ""
 }
 
+func (x *Config) GetSniffing() *proxyman.SniffingConfig {
+	if x != nil {
+		return x.Sniffing
+	}
+	return nil
+}
+
 var File_proxy_loopback_config_proto protoreflect.FileDescriptor
 
 const file_proxy_loopback_config_proto_rawDesc = "" +
 	"\n" +
-	"\x1bproxy/loopback/config.proto\x12\x13xray.proxy.loopback\")\n" +
+	"\x1bproxy/loopback/config.proto\x12\x13xray.proxy.loopback\x1a\x19app/proxyman/config.proto\"h\n" +
 	"\x06Config\x12\x1f\n" +
 	"\vinbound_tag\x18\x01 \x01(\tR\n" +
-	"inboundTagB[\n" +
+	"inboundTag\x12=\n" +
+	"\bsniffing\x18\x02 \x01(\v2!.xray.app.proxyman.SniffingConfigR\bsniffingB[\n" +
 	"\x17com.xray.proxy.loopbackP\x01Z(github.com/xtls/xray-core/proxy/loopback\xaa\x02\x13Xray.Proxy.Loopbackb\x06proto3"
 
 var (
@@ -89,14 +99,16 @@ func file_proxy_loopback_config_proto_rawDescGZIP() []byte {
 
 var file_proxy_loopback_config_proto_msgTypes = make([]protoimpl.MessageInfo, 1)
 var file_proxy_loopback_config_proto_goTypes = []any{
-	(*Config)(nil), // 0: xray.proxy.loopback.Config
+	(*Config)(nil),                  // 0: xray.proxy.loopback.Config
+	(*proxyman.SniffingConfig)(nil), // 1: xray.app.proxyman.SniffingConfig
 }
 var file_proxy_loopback_config_proto_depIdxs = []int32{
-	0, // [0:0] is the sub-list for method output_type
-	0, // [0:0] is the sub-list for method input_type
-	0, // [0:0] is the sub-list for extension type_name
-	0, // [0:0] is the sub-list for extension extendee
-	0, // [0:0] is the sub-list for field type_name
+	1, // 0: xray.proxy.loopback.Config.sniffing:type_name -> xray.app.proxyman.SniffingConfig
+	1, // [1:1] is the sub-list for method output_type
+	1, // [1:1] is the sub-list for method input_type
+	1, // [1:1] is the sub-list for extension type_name
+	1, // [1:1] is the sub-list for extension extendee
+	0, // [0:1] is the sub-list for field type_name
 }
 
 func init() { file_proxy_loopback_config_proto_init() }

proxy/loopback/config.proto

@@ -6,6 +6,9 @@ option go_package = "github.com/xtls/xray-core/proxy/loopback";
 option java_package = "com.xray.proxy.loopback";
 option java_multiple_files = true;
 
+import "app/proxyman/config.proto";
+
 message Config {
   string inbound_tag = 1;
+  xray.app.proxyman.SniffingConfig sniffing = 2;
 }

proxy/loopback/loopback.go

@@ -3,6 +3,7 @@ package loopback
 import (
 	"context"
 
+	proxyman "github.com/xtls/xray-core/app/proxyman"
 	"github.com/xtls/xray-core/common"
 	"github.com/xtls/xray-core/common/errors"
 	"github.com/xtls/xray-core/common/session"
@@ -13,7 +14,8 @@ import (
 )
 
 type Loopback struct {
-	config             *Config
+	inboundTag         string
+	sniffingRequest    session.SniffingRequest
 	dispatcherInstance routing.Dispatcher
 }
 
@@ -29,6 +31,7 @@ func (l *Loopback) Process(ctx context.Context, link *transport.Link, _ internet
 	errors.LogInfo(ctx, "opening connection to ", destination)
 	content := new(session.Content)
 	content.SkipDNSResolve = true
+	content.SniffingRequest = l.sniffingRequest
 
 	ctx = session.ContextWithContent(ctx, content)
 	inbound := &session.Inbound{}
@@ -37,20 +40,26 @@ func (l *Loopback) Process(ctx context.Context, link *transport.Link, _ internet
 		// get a shallow copy to avoid modifying the inbound tag in upstream context
 		*inbound = *originInbound
 	}
-	inbound.Tag = l.config.InboundTag
+	inbound.Tag = l.inboundTag
 	ctx = session.ContextWithInbound(ctx, inbound)
 
 	err := l.dispatcherInstance.DispatchLink(ctx, destination, link)
 	if err != nil {
-		errors.New(ctx, "failed to process loopback connection").Base(err)
-		return err
+		return errors.New(ctx, "failed to process loopback connection").Base(err)
 	}
 	return nil
 }
 
 func (l *Loopback) init(config *Config, dispatcherInstance routing.Dispatcher) error {
 	l.dispatcherInstance = dispatcherInstance
-	l.config = config
+	l.inboundTag = config.InboundTag
+	if config.Sniffing.GetEnabled() {
+		request, err := proxyman.BuildSniffingRequest(config.Sniffing)
+		if err != nil {
+			return errors.New("failed to build loopback sniffing request").Base(err).AtError()
+		}
+		l.sniffingRequest = request
+	}
 	return nil
 }