frp/client/visitor/xtcp.go

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// Copyright 2017 fatedier, fatedier@gmail.com
//
// 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"
"errors"
"fmt"
"io"
"net"
"strconv"
"sync"
"time"
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libio "github.com/fatedier/golib/io"
fmux "github.com/hashicorp/yamux"
quic "github.com/quic-go/quic-go"
"golang.org/x/time/rate"
v1 "github.com/fatedier/frp/pkg/config/v1"
"github.com/fatedier/frp/pkg/msg"
"github.com/fatedier/frp/pkg/nathole"
"github.com/fatedier/frp/pkg/transport"
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netpkg "github.com/fatedier/frp/pkg/util/net"
"github.com/fatedier/frp/pkg/util/util"
"github.com/fatedier/frp/pkg/util/xlog"
)
var ErrNoTunnelSession = errors.New("no tunnel session")
type XTCPVisitor struct {
*BaseVisitor
session TunnelSession
startTunnelCh chan struct{}
retryLimiter *rate.Limiter
cancel context.CancelFunc
cfg *v1.XTCPVisitorConfig
}
func (sv *XTCPVisitor) Run() (err error) {
sv.ctx, sv.cancel = context.WithCancel(sv.ctx)
if sv.cfg.Protocol == "kcp" {
sv.session = NewKCPTunnelSession()
} else {
sv.session = NewQUICTunnelSession(sv.clientCfg)
}
if sv.cfg.BindPort > 0 {
sv.l, err = net.Listen("tcp", net.JoinHostPort(sv.cfg.BindAddr, strconv.Itoa(sv.cfg.BindPort)))
if err != nil {
return
}
go sv.worker()
}
go sv.internalConnWorker()
go sv.processTunnelStartEvents()
if sv.cfg.KeepTunnelOpen {
sv.retryLimiter = rate.NewLimiter(rate.Every(time.Hour/time.Duration(sv.cfg.MaxRetriesAnHour)), sv.cfg.MaxRetriesAnHour)
go sv.keepTunnelOpenWorker()
}
return
}
func (sv *XTCPVisitor) Close() {
sv.mu.Lock()
defer sv.mu.Unlock()
sv.BaseVisitor.Close()
if sv.cancel != nil {
sv.cancel()
}
if sv.session != nil {
sv.session.Close()
}
}
func (sv *XTCPVisitor) worker() {
xl := xlog.FromContextSafe(sv.ctx)
for {
conn, err := sv.l.Accept()
if err != nil {
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xl.Warnf("xtcp local listener closed")
return
}
go sv.handleConn(conn)
}
}
func (sv *XTCPVisitor) internalConnWorker() {
xl := xlog.FromContextSafe(sv.ctx)
for {
conn, err := sv.internalLn.Accept()
if err != nil {
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xl.Warnf("xtcp internal listener closed")
return
}
go sv.handleConn(conn)
}
}
func (sv *XTCPVisitor) processTunnelStartEvents() {
for {
select {
case <-sv.ctx.Done():
return
case <-sv.startTunnelCh:
start := time.Now()
sv.makeNatHole()
duration := time.Since(start)
// avoid too frequently
if duration < 10*time.Second {
time.Sleep(10*time.Second - duration)
}
}
}
}
func (sv *XTCPVisitor) keepTunnelOpenWorker() {
xl := xlog.FromContextSafe(sv.ctx)
ticker := time.NewTicker(time.Duration(sv.cfg.MinRetryInterval) * time.Second)
defer ticker.Stop()
sv.startTunnelCh <- struct{}{}
for {
select {
case <-sv.ctx.Done():
return
case <-ticker.C:
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xl.Debugf("keepTunnelOpenWorker try to check tunnel...")
conn, err := sv.getTunnelConn()
if err != nil {
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xl.Warnf("keepTunnelOpenWorker get tunnel connection error: %v", err)
_ = sv.retryLimiter.Wait(sv.ctx)
continue
}
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xl.Debugf("keepTunnelOpenWorker check success")
if conn != nil {
conn.Close()
}
}
}
}
func (sv *XTCPVisitor) handleConn(userConn net.Conn) {
xl := xlog.FromContextSafe(sv.ctx)
isConnTrasfered := false
defer func() {
if !isConnTrasfered {
userConn.Close()
}
}()
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xl.Debugf("get a new xtcp user connection")
// Open a tunnel connection to the server. If there is already a successful hole-punching connection,
// it will be reused. Otherwise, it will block and wait for a successful hole-punching connection until timeout.
ctx := context.Background()
if sv.cfg.FallbackTo != "" {
timeoutCtx, cancel := context.WithTimeout(ctx, time.Duration(sv.cfg.FallbackTimeoutMs)*time.Millisecond)
defer cancel()
ctx = timeoutCtx
}
tunnelConn, err := sv.openTunnel(ctx)
if err != nil {
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xl.Errorf("open tunnel error: %v", err)
// no fallback, just return
if sv.cfg.FallbackTo == "" {
return
}
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xl.Debugf("try to transfer connection to visitor: %s", sv.cfg.FallbackTo)
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if err := sv.helper.TransferConn(sv.cfg.FallbackTo, userConn); err != nil {
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xl.Errorf("transfer connection to visitor %s error: %v", sv.cfg.FallbackTo, err)
return
}
isConnTrasfered = true
return
}
var muxConnRWCloser io.ReadWriteCloser = tunnelConn
if sv.cfg.Transport.UseEncryption {
muxConnRWCloser, err = libio.WithEncryption(muxConnRWCloser, []byte(sv.cfg.SecretKey))
if err != nil {
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xl.Errorf("create encryption stream error: %v", err)
return
}
}
if sv.cfg.Transport.UseCompression {
var recycleFn func()
muxConnRWCloser, recycleFn = libio.WithCompressionFromPool(muxConnRWCloser)
defer recycleFn()
}
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_, _, errs := libio.Join(userConn, muxConnRWCloser)
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xl.Debugf("join connections closed")
if len(errs) > 0 {
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xl.Tracef("join connections errors: %v", errs)
}
}
// openTunnel will open a tunnel connection to the target server.
func (sv *XTCPVisitor) openTunnel(ctx context.Context) (conn net.Conn, err error) {
xl := xlog.FromContextSafe(sv.ctx)
ticker := time.NewTicker(500 * time.Millisecond)
defer ticker.Stop()
timeoutC := time.After(20 * time.Second)
immediateTrigger := make(chan struct{}, 1)
defer close(immediateTrigger)
immediateTrigger <- struct{}{}
for {
select {
case <-sv.ctx.Done():
return nil, sv.ctx.Err()
case <-ctx.Done():
return nil, ctx.Err()
case <-immediateTrigger:
conn, err = sv.getTunnelConn()
case <-ticker.C:
conn, err = sv.getTunnelConn()
case <-timeoutC:
return nil, fmt.Errorf("open tunnel timeout")
}
if err != nil {
if err != ErrNoTunnelSession {
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xl.Warnf("get tunnel connection error: %v", err)
}
continue
}
return conn, nil
}
}
func (sv *XTCPVisitor) getTunnelConn() (net.Conn, error) {
conn, err := sv.session.OpenConn(sv.ctx)
if err == nil {
return conn, nil
}
sv.session.Close()
select {
case sv.startTunnelCh <- struct{}{}:
default:
}
return nil, err
}
// 0. PreCheck
// 1. Prepare
// 2. ExchangeInfo
// 3. MakeNATHole
// 4. Create a tunnel session using an underlying UDP connection.
func (sv *XTCPVisitor) makeNatHole() {
xl := xlog.FromContextSafe(sv.ctx)
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xl.Tracef("makeNatHole start")
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if err := nathole.PreCheck(sv.ctx, sv.helper.MsgTransporter(), sv.cfg.ServerName, 5*time.Second); err != nil {
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xl.Warnf("nathole precheck error: %v", err)
return
}
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xl.Tracef("nathole prepare start")
prepareResult, err := nathole.Prepare([]string{sv.clientCfg.NatHoleSTUNServer})
if err != nil {
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xl.Warnf("nathole prepare error: %v", err)
return
}
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xl.Infof("nathole prepare success, nat type: %s, behavior: %s, addresses: %v, assistedAddresses: %v",
prepareResult.NatType, prepareResult.Behavior, prepareResult.Addrs, prepareResult.AssistedAddrs)
listenConn := prepareResult.ListenConn
// send NatHoleVisitor to server
now := time.Now().Unix()
transactionID := nathole.NewTransactionID()
natHoleVisitorMsg := &msg.NatHoleVisitor{
TransactionID: transactionID,
ProxyName: sv.cfg.ServerName,
Protocol: sv.cfg.Protocol,
SignKey: util.GetAuthKey(sv.cfg.SecretKey, now),
Timestamp: now,
MappedAddrs: prepareResult.Addrs,
AssistedAddrs: prepareResult.AssistedAddrs,
}
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xl.Tracef("nathole exchange info start")
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natHoleRespMsg, err := nathole.ExchangeInfo(sv.ctx, sv.helper.MsgTransporter(), transactionID, natHoleVisitorMsg, 5*time.Second)
if err != nil {
listenConn.Close()
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xl.Warnf("nathole exchange info error: %v", err)
return
}
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xl.Infof("get natHoleRespMsg, sid [%s], protocol [%s], candidate address %v, assisted address %v, detectBehavior: %+v",
natHoleRespMsg.Sid, natHoleRespMsg.Protocol, natHoleRespMsg.CandidateAddrs,
natHoleRespMsg.AssistedAddrs, natHoleRespMsg.DetectBehavior)
newListenConn, raddr, err := nathole.MakeHole(sv.ctx, listenConn, natHoleRespMsg, []byte(sv.cfg.SecretKey))
if err != nil {
listenConn.Close()
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xl.Warnf("make hole error: %v", err)
return
}
listenConn = newListenConn
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xl.Infof("establishing nat hole connection successful, sid [%s], remoteAddr [%s]", natHoleRespMsg.Sid, raddr)
if err := sv.session.Init(listenConn, raddr); err != nil {
listenConn.Close()
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xl.Warnf("init tunnel session error: %v", err)
return
}
}
type TunnelSession interface {
Init(listenConn *net.UDPConn, raddr *net.UDPAddr) error
OpenConn(context.Context) (net.Conn, error)
Close()
}
type KCPTunnelSession struct {
session *fmux.Session
lConn *net.UDPConn
mu sync.RWMutex
}
func NewKCPTunnelSession() TunnelSession {
return &KCPTunnelSession{}
}
func (ks *KCPTunnelSession) Init(listenConn *net.UDPConn, raddr *net.UDPAddr) error {
listenConn.Close()
laddr, _ := net.ResolveUDPAddr("udp", listenConn.LocalAddr().String())
lConn, err := net.DialUDP("udp", laddr, raddr)
if err != nil {
return fmt.Errorf("dial udp error: %v", err)
}
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remote, err := netpkg.NewKCPConnFromUDP(lConn, true, raddr.String())
if err != nil {
return fmt.Errorf("create kcp connection from udp connection error: %v", err)
}
fmuxCfg := fmux.DefaultConfig()
fmuxCfg.KeepAliveInterval = 10 * time.Second
fmuxCfg.MaxStreamWindowSize = 6 * 1024 * 1024
fmuxCfg.LogOutput = io.Discard
session, err := fmux.Client(remote, fmuxCfg)
if err != nil {
remote.Close()
return fmt.Errorf("initial client session error: %v", err)
}
ks.mu.Lock()
ks.session = session
ks.lConn = lConn
ks.mu.Unlock()
return nil
}
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func (ks *KCPTunnelSession) OpenConn(_ context.Context) (net.Conn, error) {
ks.mu.RLock()
defer ks.mu.RUnlock()
session := ks.session
if session == nil {
return nil, ErrNoTunnelSession
}
return session.Open()
}
func (ks *KCPTunnelSession) Close() {
ks.mu.Lock()
defer ks.mu.Unlock()
if ks.session != nil {
_ = ks.session.Close()
ks.session = nil
}
if ks.lConn != nil {
_ = ks.lConn.Close()
ks.lConn = nil
}
}
type QUICTunnelSession struct {
session quic.Connection
listenConn *net.UDPConn
mu sync.RWMutex
clientCfg *v1.ClientCommonConfig
}
func NewQUICTunnelSession(clientCfg *v1.ClientCommonConfig) TunnelSession {
return &QUICTunnelSession{
clientCfg: clientCfg,
}
}
func (qs *QUICTunnelSession) Init(listenConn *net.UDPConn, raddr *net.UDPAddr) error {
tlsConfig, err := transport.NewClientTLSConfig("", "", "", raddr.String())
if err != nil {
return fmt.Errorf("create tls config error: %v", err)
}
tlsConfig.NextProtos = []string{"frp"}
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quicConn, err := quic.Dial(context.Background(), listenConn, raddr, tlsConfig,
&quic.Config{
MaxIdleTimeout: time.Duration(qs.clientCfg.Transport.QUIC.MaxIdleTimeout) * time.Second,
MaxIncomingStreams: int64(qs.clientCfg.Transport.QUIC.MaxIncomingStreams),
KeepAlivePeriod: time.Duration(qs.clientCfg.Transport.QUIC.KeepalivePeriod) * time.Second,
})
if err != nil {
return fmt.Errorf("dial quic error: %v", err)
}
qs.mu.Lock()
qs.session = quicConn
qs.listenConn = listenConn
qs.mu.Unlock()
return nil
}
func (qs *QUICTunnelSession) OpenConn(ctx context.Context) (net.Conn, error) {
qs.mu.RLock()
defer qs.mu.RUnlock()
session := qs.session
if session == nil {
return nil, ErrNoTunnelSession
}
stream, err := session.OpenStreamSync(ctx)
if err != nil {
return nil, err
}
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return netpkg.QuicStreamToNetConn(stream, session), nil
}
func (qs *QUICTunnelSession) Close() {
qs.mu.Lock()
defer qs.mu.Unlock()
if qs.session != nil {
_ = qs.session.CloseWithError(0, "")
qs.session = nil
}
if qs.listenConn != nil {
_ = qs.listenConn.Close()
qs.listenConn = nil
}
}