virtual-net: initial (#4751)

pkg/config/v1/client.go

@@ -58,9 +58,14 @@ type ClientCommonConfig struct {
 	// set.
 	Start []string `json:"start,omitempty"`
 
-	Log       LogConfig             `json:"log,omitempty"`
-	WebServer WebServerConfig       `json:"webServer,omitempty"`
-	Transport ClientTransportConfig `json:"transport,omitempty"`
+	Log        LogConfig             `json:"log,omitempty"`
+	WebServer  WebServerConfig       `json:"webServer,omitempty"`
+	Transport  ClientTransportConfig `json:"transport,omitempty"`
+	VirtualNet VirtualNetConfig      `json:"virtualNet,omitempty"`
+
+	// FeatureGates specifies a set of feature gates to enable or disable.
+	// This can be used to enable alpha/beta features or disable default features.
+	FeatureGates map[string]bool `json:"featureGates,omitempty"`
 
 	// UDPPacketSize specifies the udp packet size
 	// By default, this value is 1500
@@ -204,3 +209,7 @@ type AuthOIDCClientConfig struct {
 	// this field will be transfer to map[string][]string in OIDC token generator.
 	AdditionalEndpointParams map[string]string `json:"additionalEndpointParams,omitempty"`
 }
+
+type VirtualNetConfig struct {
+	Address string `json:"address,omitempty"`
+}

pkg/config/v1/proxy_plugin.go

@@ -26,6 +26,32 @@ import (
 	"github.com/fatedier/frp/pkg/util/util"
 )
 
+const (
+	PluginHTTP2HTTPS       = "http2https"
+	PluginHTTPProxy        = "http_proxy"
+	PluginHTTPS2HTTP       = "https2http"
+	PluginHTTPS2HTTPS      = "https2https"
+	PluginHTTP2HTTP        = "http2http"
+	PluginSocks5           = "socks5"
+	PluginStaticFile       = "static_file"
+	PluginUnixDomainSocket = "unix_domain_socket"
+	PluginTLS2Raw          = "tls2raw"
+	PluginVirtualNet       = "virtual_net"
+)
+
+var clientPluginOptionsTypeMap = map[string]reflect.Type{
+	PluginHTTP2HTTPS:       reflect.TypeOf(HTTP2HTTPSPluginOptions{}),
+	PluginHTTPProxy:        reflect.TypeOf(HTTPProxyPluginOptions{}),
+	PluginHTTPS2HTTP:       reflect.TypeOf(HTTPS2HTTPPluginOptions{}),
+	PluginHTTPS2HTTPS:      reflect.TypeOf(HTTPS2HTTPSPluginOptions{}),
+	PluginHTTP2HTTP:        reflect.TypeOf(HTTP2HTTPPluginOptions{}),
+	PluginSocks5:           reflect.TypeOf(Socks5PluginOptions{}),
+	PluginStaticFile:       reflect.TypeOf(StaticFilePluginOptions{}),
+	PluginUnixDomainSocket: reflect.TypeOf(UnixDomainSocketPluginOptions{}),
+	PluginTLS2Raw:          reflect.TypeOf(TLS2RawPluginOptions{}),
+	PluginVirtualNet:       reflect.TypeOf(VirtualNetPluginOptions{}),
+}
+
 type ClientPluginOptions interface {
 	Complete()
 }
@@ -74,30 +100,6 @@ func (c *TypedClientPluginOptions) MarshalJSON() ([]byte, error) {
 	return json.Marshal(c.ClientPluginOptions)
 }
 
-const (
-	PluginHTTP2HTTPS       = "http2https"
-	PluginHTTPProxy        = "http_proxy"
-	PluginHTTPS2HTTP       = "https2http"
-	PluginHTTPS2HTTPS      = "https2https"
-	PluginHTTP2HTTP        = "http2http"
-	PluginSocks5           = "socks5"
-	PluginStaticFile       = "static_file"
-	PluginUnixDomainSocket = "unix_domain_socket"
-	PluginTLS2Raw          = "tls2raw"
-)
-
-var clientPluginOptionsTypeMap = map[string]reflect.Type{
-	PluginHTTP2HTTPS:       reflect.TypeOf(HTTP2HTTPSPluginOptions{}),
-	PluginHTTPProxy:        reflect.TypeOf(HTTPProxyPluginOptions{}),
-	PluginHTTPS2HTTP:       reflect.TypeOf(HTTPS2HTTPPluginOptions{}),
-	PluginHTTPS2HTTPS:      reflect.TypeOf(HTTPS2HTTPSPluginOptions{}),
-	PluginHTTP2HTTP:        reflect.TypeOf(HTTP2HTTPPluginOptions{}),
-	PluginSocks5:           reflect.TypeOf(Socks5PluginOptions{}),
-	PluginStaticFile:       reflect.TypeOf(StaticFilePluginOptions{}),
-	PluginUnixDomainSocket: reflect.TypeOf(UnixDomainSocketPluginOptions{}),
-	PluginTLS2Raw:          reflect.TypeOf(TLS2RawPluginOptions{}),
-}
-
 type HTTP2HTTPSPluginOptions struct {
 	Type              string           `json:"type,omitempty"`
 	LocalAddr         string           `json:"localAddr,omitempty"`
@@ -185,3 +187,9 @@ type TLS2RawPluginOptions struct {
 }
 
 func (o *TLS2RawPluginOptions) Complete() {}
+
+type VirtualNetPluginOptions struct {
+	Type string `json:"type,omitempty"`
+}
+
+func (o *VirtualNetPluginOptions) Complete() {}

pkg/config/v1/validation/client.go

@@ -23,6 +23,7 @@ import (
 	"github.com/samber/lo"
 
 	v1 "github.com/fatedier/frp/pkg/config/v1"
+	"github.com/fatedier/frp/pkg/featuregate"
 )
 
 func ValidateClientCommonConfig(c *v1.ClientCommonConfig) (Warning, error) {
@@ -30,6 +31,13 @@ func ValidateClientCommonConfig(c *v1.ClientCommonConfig) (Warning, error) {
 		warnings Warning
 		errs     error
 	)
+	// validate feature gates
+	if c.VirtualNet.Address != "" {
+		if !featuregate.Enabled(featuregate.VirtualNet) {
+			return warnings, fmt.Errorf("VirtualNet feature is not enabled; enable it by setting the appropriate feature gate flag")
+		}
+	}
+
 	if !slices.Contains(SupportedAuthMethods, c.Auth.Method) {
 		errs = AppendError(errs, fmt.Errorf("invalid auth method, optional values are %v", SupportedAuthMethods))
 	}

pkg/config/v1/visitor.go

@@ -44,6 +44,9 @@ type VisitorBaseConfig struct {
 	// It can be less than 0, it means don't bind to the port and only receive connections redirected from
 	// other visitors. (This is not supported for SUDP now)
 	BindPort int `json:"bindPort,omitempty"`
+
+	// Plugin specifies what plugin should be used.
+	Plugin TypedVisitorPluginOptions `json:"plugin,omitempty"`
 }
 
 func (c *VisitorBaseConfig) GetBaseConfig() *VisitorBaseConfig {

pkg/config/v1/visitor_plugin.go

@@ -0,0 +1,86 @@
+// Copyright 2025 The frp Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package v1
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"reflect"
+)
+
+const (
+	VisitorPluginVirtualNet = "virtual_net"
+)
+
+var visitorPluginOptionsTypeMap = map[string]reflect.Type{
+	VisitorPluginVirtualNet: reflect.TypeOf(VirtualNetVisitorPluginOptions{}),
+}
+
+type VisitorPluginOptions interface {
+	Complete()
+}
+
+type TypedVisitorPluginOptions struct {
+	Type string `json:"type"`
+	VisitorPluginOptions
+}
+
+func (c *TypedVisitorPluginOptions) UnmarshalJSON(b []byte) error {
+	if len(b) == 4 && string(b) == "null" {
+		return nil
+	}
+
+	typeStruct := struct {
+		Type string `json:"type"`
+	}{}
+	if err := json.Unmarshal(b, &typeStruct); err != nil {
+		return err
+	}
+
+	c.Type = typeStruct.Type
+	if c.Type == "" {
+		return errors.New("visitor plugin type is empty")
+	}
+
+	v, ok := visitorPluginOptionsTypeMap[typeStruct.Type]
+	if !ok {
+		return fmt.Errorf("unknown visitor plugin type: %s", typeStruct.Type)
+	}
+	options := reflect.New(v).Interface().(VisitorPluginOptions)
+
+	decoder := json.NewDecoder(bytes.NewBuffer(b))
+	if DisallowUnknownFields {
+		decoder.DisallowUnknownFields()
+	}
+
+	if err := decoder.Decode(options); err != nil {
+		return fmt.Errorf("unmarshal VisitorPluginOptions error: %v", err)
+	}
+	c.VisitorPluginOptions = options
+	return nil
+}
+
+func (c *TypedVisitorPluginOptions) MarshalJSON() ([]byte, error) {
+	return json.Marshal(c.VisitorPluginOptions)
+}
+
+type VirtualNetVisitorPluginOptions struct {
+	Type          string `json:"type"`
+	DestinationIP string `json:"destinationIP"`
+}
+
+func (o *VirtualNetVisitorPluginOptions) Complete() {}