virtual-net: initial (#4751)

pkg/plugin/visitor/plugin.go

@@ -0,0 +1,58 @@
+// 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 visitor
+
+import (
+	"context"
+	"fmt"
+	"net"
+
+	v1 "github.com/fatedier/frp/pkg/config/v1"
+	"github.com/fatedier/frp/pkg/vnet"
+)
+
+type PluginContext struct {
+	Name           string
+	Ctx            context.Context
+	VnetController *vnet.Controller
+	HandleConn     func(net.Conn)
+}
+
+// Creators is used for create plugins to handle connections.
+var creators = make(map[string]CreatorFn)
+
+type CreatorFn func(pluginCtx PluginContext, options v1.VisitorPluginOptions) (Plugin, error)
+
+func Register(name string, fn CreatorFn) {
+	if _, exist := creators[name]; exist {
+		panic(fmt.Sprintf("plugin [%s] is already registered", name))
+	}
+	creators[name] = fn
+}
+
+func Create(pluginName string, pluginCtx PluginContext, options v1.VisitorPluginOptions) (p Plugin, err error) {
+	if fn, ok := creators[pluginName]; ok {
+		p, err = fn(pluginCtx, options)
+	} else {
+		err = fmt.Errorf("plugin [%s] is not registered", pluginName)
+	}
+	return
+}
+
+type Plugin interface {
+	Name() string
+	Start()
+	Close() error
+}

pkg/plugin/visitor/virtual_net.go

@@ -0,0 +1,232 @@
+// 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.
+
+//go:build !frps
+
+package visitor
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net"
+	"sync"
+	"time"
+
+	v1 "github.com/fatedier/frp/pkg/config/v1"
+	netutil "github.com/fatedier/frp/pkg/util/net"
+	"github.com/fatedier/frp/pkg/util/xlog"
+)
+
+func init() {
+	Register(v1.VisitorPluginVirtualNet, NewVirtualNetPlugin)
+}
+
+type VirtualNetPlugin struct {
+	pluginCtx PluginContext
+
+	routes []net.IPNet
+
+	mu             sync.Mutex
+	controllerConn net.Conn
+	closeSignal    chan struct{}
+
+	ctx    context.Context
+	cancel context.CancelFunc
+}
+
+func NewVirtualNetPlugin(pluginCtx PluginContext, options v1.VisitorPluginOptions) (Plugin, error) {
+	opts := options.(*v1.VirtualNetVisitorPluginOptions)
+
+	p := &VirtualNetPlugin{
+		pluginCtx: pluginCtx,
+		routes:    make([]net.IPNet, 0),
+	}
+
+	p.ctx, p.cancel = context.WithCancel(pluginCtx.Ctx)
+
+	if opts.DestinationIP == "" {
+		return nil, errors.New("destinationIP is required")
+	}
+
+	// Parse DestinationIP as a single IP and create a host route
+	ip := net.ParseIP(opts.DestinationIP)
+	if ip == nil {
+		return nil, fmt.Errorf("invalid destination IP address [%s]", opts.DestinationIP)
+	}
+
+	var mask net.IPMask
+	if ip.To4() != nil {
+		mask = net.CIDRMask(32, 32) // /32 for IPv4
+	} else {
+		mask = net.CIDRMask(128, 128) // /128 for IPv6
+	}
+	p.routes = append(p.routes, net.IPNet{IP: ip, Mask: mask})
+
+	return p, nil
+}
+
+func (p *VirtualNetPlugin) Name() string {
+	return v1.VisitorPluginVirtualNet
+}
+
+func (p *VirtualNetPlugin) Start() {
+	xl := xlog.FromContextSafe(p.pluginCtx.Ctx)
+	if p.pluginCtx.VnetController == nil {
+		return
+	}
+
+	routeStr := "unknown"
+	if len(p.routes) > 0 {
+		routeStr = p.routes[0].String()
+	}
+	xl.Infof("Starting VirtualNetPlugin for visitor [%s], attempting to register routes for %s", p.pluginCtx.Name, routeStr)
+
+	go p.run()
+}
+
+func (p *VirtualNetPlugin) run() {
+	xl := xlog.FromContextSafe(p.ctx)
+	reconnectDelay := 10 * time.Second
+
+	for {
+		// Create a signal channel for this connection attempt
+		currentCloseSignal := make(chan struct{})
+
+		// Store the signal channel under lock
+		p.mu.Lock()
+		p.closeSignal = currentCloseSignal
+		p.mu.Unlock()
+
+		select {
+		case <-p.ctx.Done():
+			xl.Infof("VirtualNetPlugin run loop for visitor [%s] stopping (context cancelled before pipe creation).", p.pluginCtx.Name)
+			// Ensure controllerConn from previous loop is cleaned up if necessary
+			p.cleanupControllerConn(xl)
+			return
+		default:
+		}
+
+		controllerConn, pluginConn := net.Pipe()
+
+		// Store controllerConn under lock for cleanup purposes
+		p.mu.Lock()
+		p.controllerConn = controllerConn
+		p.mu.Unlock()
+
+		// Wrap pluginConn using CloseNotifyConn
+		pluginNotifyConn := netutil.WrapCloseNotifyConn(pluginConn, func() {
+			close(currentCloseSignal) // Signal the run loop
+		})
+
+		xl.Infof("Attempting to register client route for visitor [%s]", p.pluginCtx.Name)
+		err := p.pluginCtx.VnetController.RegisterClientRoute(p.ctx, p.pluginCtx.Name, p.routes, controllerConn)
+		if err != nil {
+			xl.Errorf("Failed to register client route for visitor [%s]: %v. Retrying after %v", p.pluginCtx.Name, err, reconnectDelay)
+			p.cleanupPipePair(xl, controllerConn, pluginConn) // Close both ends on registration failure
+
+			// Wait before retrying registration, unless context is cancelled
+			select {
+			case <-time.After(reconnectDelay):
+				continue // Retry the loop
+			case <-p.ctx.Done():
+				xl.Infof("VirtualNetPlugin registration retry wait interrupted for visitor [%s]", p.pluginCtx.Name)
+				return // Exit loop if context is cancelled during wait
+			}
+		}
+
+		xl.Infof("Successfully registered client route for visitor [%s]. Starting connection handler with CloseNotifyConn.", p.pluginCtx.Name)
+
+		// Pass the CloseNotifyConn to HandleConn.
+		// HandleConn is responsible for calling Close() on pluginNotifyConn.
+		p.pluginCtx.HandleConn(pluginNotifyConn)
+
+		// Wait for either the plugin context to be cancelled or the wrapper's Close() to be called via the signal channel.
+		select {
+		case <-p.ctx.Done():
+			xl.Infof("VirtualNetPlugin run loop stopping for visitor [%s] (context cancelled while waiting).", p.pluginCtx.Name)
+			// Context cancelled, ensure controller side is closed if HandleConn didn't close its side yet.
+			p.cleanupControllerConn(xl)
+			return
+		case <-currentCloseSignal:
+			xl.Infof("Detected connection closed via CloseNotifyConn for visitor [%s].", p.pluginCtx.Name)
+			// HandleConn closed the plugin side (pluginNotifyConn). The closeFn was called, closing currentCloseSignal.
+			// We still need to close the controller side.
+			p.cleanupControllerConn(xl)
+
+			// Add a delay before attempting to reconnect, respecting context cancellation.
+			xl.Infof("Waiting %v before attempting reconnection for visitor [%s]...", reconnectDelay, p.pluginCtx.Name)
+			select {
+			case <-time.After(reconnectDelay):
+				// Delay completed, loop will continue.
+			case <-p.ctx.Done():
+				xl.Infof("VirtualNetPlugin reconnection delay interrupted for visitor [%s]", p.pluginCtx.Name)
+				return // Exit loop if context is cancelled during wait
+			}
+			// Loop will continue to reconnect.
+		}
+
+		// Loop will restart, context check at the beginning of the loop is sufficient.
+		xl.Infof("Re-establishing virtual connection for visitor [%s]...", p.pluginCtx.Name)
+	}
+}
+
+// cleanupControllerConn closes the current controllerConn (if it exists) under lock.
+func (p *VirtualNetPlugin) cleanupControllerConn(xl *xlog.Logger) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	if p.controllerConn != nil {
+		xl.Debugf("Cleaning up controllerConn for visitor [%s]", p.pluginCtx.Name)
+		p.controllerConn.Close()
+		p.controllerConn = nil
+	}
+	// Also clear the closeSignal reference for the completed/cancelled connection attempt
+	p.closeSignal = nil
+}
+
+// cleanupPipePair closes both ends of a pipe, used typically when registration fails.
+func (p *VirtualNetPlugin) cleanupPipePair(xl *xlog.Logger, controllerConn, pluginConn net.Conn) {
+	xl.Debugf("Cleaning up pipe pair for visitor [%s] after registration failure", p.pluginCtx.Name)
+	controllerConn.Close()
+	pluginConn.Close()
+	p.mu.Lock()
+	p.controllerConn = nil // Ensure field is nil if it was briefly set
+	p.closeSignal = nil    // Ensure field is nil if it was briefly set
+	p.mu.Unlock()
+}
+
+// Close initiates the plugin shutdown.
+func (p *VirtualNetPlugin) Close() error {
+	xl := xlog.FromContextSafe(p.pluginCtx.Ctx) // Use base context for close logging
+	xl.Infof("Closing VirtualNetPlugin for visitor [%s]", p.pluginCtx.Name)
+
+	// 1. Signal the run loop goroutine to stop via context cancellation.
+	p.cancel()
+
+	// 2. Unregister the route from the controller.
+	// This might implicitly cause the VnetController to close its end of the pipe (controllerConn).
+	if p.pluginCtx.VnetController != nil {
+		p.pluginCtx.VnetController.UnregisterClientRoute(p.pluginCtx.Name)
+		xl.Infof("Unregistered client route for visitor [%s]", p.pluginCtx.Name)
+	} else {
+		xl.Warnf("VnetController is nil during close for visitor [%s], cannot unregister route", p.pluginCtx.Name)
+	}
+
+	// 3. Explicitly close the controller side of the pipe managed by this plugin.
+	// This ensures the pipe is broken even if the run loop is stuck or HandleConn hasn't closed its end.
+	p.cleanupControllerConn(xl)
+	xl.Infof("Finished cleaning up connections during close for visitor [%s]", p.pluginCtx.Name)
+
+	return nil
+}