add udp redirect listener

cmd/gost/register.go

@@ -49,6 +49,7 @@ import (
 	_ "github.com/go-gost/gost/pkg/listener/obfs/http"
 	_ "github.com/go-gost/gost/pkg/listener/obfs/tls"
 	_ "github.com/go-gost/gost/pkg/listener/quic"
+	_ "github.com/go-gost/gost/pkg/listener/redirect/udp"
 	_ "github.com/go-gost/gost/pkg/listener/rtcp"
 	_ "github.com/go-gost/gost/pkg/listener/rudp"
 	_ "github.com/go-gost/gost/pkg/listener/tcp"

go.mod

@@ -3,6 +3,7 @@ module github.com/go-gost/gost
 go 1.17
 
 require (
+	github.com/LiamHaworth/go-tproxy v0.0.0-20190726054950-ef7efd7f24ed
 	github.com/aead/chacha20 v0.0.0-20180709150244-8b13a72661da // indirect
 	github.com/asaskevich/govalidator v0.0.0-20210307081110-f21760c49a8d
 	github.com/cheekybits/genny v1.0.0 // indirect

go.sum

@@ -51,6 +51,8 @@ dmitri.shuralyov.com/state v0.0.0-20180228185332-28bcc343414c/go.mod h1:0PRwlb0D
 git.apache.org/thrift.git v0.0.0-20180902110319-2566ecd5d999/go.mod h1:fPE2ZNJGynbRyZ4dJvy6G277gSllfV2HJqblrnkyeyg=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
+github.com/LiamHaworth/go-tproxy v0.0.0-20190726054950-ef7efd7f24ed h1:eqa6queieK8SvoszxCu0WwH7lSVeL4/N/f1JwOMw1G4=
+github.com/LiamHaworth/go-tproxy v0.0.0-20190726054950-ef7efd7f24ed/go.mod h1:rA52xkgZwql9LRZXWb2arHEFP6qSR48KY2xOfWzEciQ=
 github.com/OneOfOne/xxhash v1.2.2/go.mod h1:HSdplMjZKSmBqAxg5vPj2TmRDmfkzw+cTzAElWljhcU=
 github.com/aead/chacha20 v0.0.0-20180709150244-8b13a72661da h1:KjTM2ks9d14ZYCvmHS9iAKVt9AyzRSqNU1qabPih5BY=
 github.com/aead/chacha20 v0.0.0-20180709150244-8b13a72661da/go.mod h1:eHEWzANqSiWQsof+nXEI9bUVUyV6F53Fp89EuCh2EAA=
@@ -397,8 +399,6 @@ github.com/xtaci/kcp-go/v5 v5.6.1 h1:Pwn0aoeNSPF9dTS7IgiPXn0HEtaIlVb6y5UKWPsx8bI
 github.com/xtaci/kcp-go/v5 v5.6.1/go.mod h1:W3kVPyNYwZ06p79dNwFWQOVFrdcBpDBsdyvK8moQrYo=
 github.com/xtaci/lossyconn v0.0.0-20190602105132-8df528c0c9ae h1:J0GxkO96kL4WF+AIT3M4mfUVinOCPgf2uUWYFUzN0sM=
 github.com/xtaci/lossyconn v0.0.0-20190602105132-8df528c0c9ae/go.mod h1:gXtu8J62kEgmN++bm9BVICuT/e8yiLI2KFobd/TRFsE=
-github.com/xtaci/smux v1.5.15 h1:6hMiXswcleXj5oNfcJc+DXS8Vj36XX2LaX98udog6Kc=
-github.com/xtaci/smux v1.5.15/go.mod h1:OMlQbT5vcgl2gb49mFkYo6SMf+zP3rcjcwQz7ZU7IGY=
 github.com/xtaci/smux v1.5.16 h1:FBPYOkW8ZTjLKUM4LI4xnnuuDC8CQ/dB04HD519WoEk=
 github.com/xtaci/smux v1.5.16/go.mod h1:OMlQbT5vcgl2gb49mFkYo6SMf+zP3rcjcwQz7ZU7IGY=
 github.com/xtaci/tcpraw v1.2.25 h1:VDlqo0op17JeXBM6e2G9ocCNLOJcw9mZbobMbJjo0vk=

pkg/handler/redirect/handler.go

@@ -16,6 +16,7 @@ import (
 
 func init() {
 	registry.RegisterHandler("red", NewHandler)
+	registry.RegisterHandler("redu", NewHandler)
 	registry.RegisterHandler("redir", NewHandler)
 	registry.RegisterHandler("redirect", NewHandler)
 }
@@ -49,6 +50,8 @@ func (h *redirectHandler) WithChain(chain *chain.Chain) {
 }
 
 func (h *redirectHandler) Handle(ctx context.Context, conn net.Conn) {
+	defer conn.Close()
+
 	start := time.Now()
 	h.logger = h.logger.WithFields(map[string]interface{}{
 		"remote": conn.RemoteAddr().String(),
@@ -78,7 +81,6 @@ func (h *redirectHandler) Handle(ctx context.Context, conn net.Conn) {
 			return
 		}
 	}
-	defer conn.Close()
 
 	h.logger = h.logger.WithFields(map[string]interface{}{
 		"dst": fmt.Sprintf("%s/%s", dstAddr, network),

pkg/handler/redirect/handler_other.go

@@ -10,6 +10,6 @@ import (
 func (h *redirectHandler) getOriginalDstAddr(conn net.Conn) (addr net.Addr, c net.Conn, err error) {
 	defer conn.Close()
 
-	err = errors.New("TCP redirect is not available on Windows platform")
+	err = errors.New("TCP redirect is not available on non-linux platform")
 	return
 }

pkg/listener/redirect/udp/conn.go

@@ -0,0 +1,42 @@
+package udp
+
+import (
+	"net"
+	"sync"
+	"time"
+
+	"github.com/go-gost/gost/pkg/common/bufpool"
+)
+
+type redirConn struct {
+	net.Conn
+	buf  []byte
+	ttl  time.Duration
+	once sync.Once
+}
+
+func (c *redirConn) Read(b []byte) (n int, err error) {
+	if c.ttl > 0 {
+		c.SetReadDeadline(time.Now().Add(c.ttl))
+		defer c.SetReadDeadline(time.Time{})
+	}
+
+	c.once.Do(func() {
+		n = copy(b, c.buf)
+		bufpool.Put(c.buf)
+		c.buf = nil
+	})
+
+	if n == 0 {
+		n, err = c.Conn.Read(b)
+	}
+	return
+}
+
+func (c *redirConn) Write(b []byte) (n int, err error) {
+	if c.ttl > 0 {
+		c.SetWriteDeadline(time.Now().Add(c.ttl))
+		defer c.SetWriteDeadline(time.Time{})
+	}
+	return c.Conn.Write(b)
+}

pkg/listener/redirect/udp/listener.go

@@ -0,0 +1,63 @@
+package udp
+
+import (
+	"net"
+
+	"github.com/go-gost/gost/pkg/listener"
+	"github.com/go-gost/gost/pkg/logger"
+	md "github.com/go-gost/gost/pkg/metadata"
+	"github.com/go-gost/gost/pkg/registry"
+)
+
+func init() {
+	registry.RegisterListener("redu", NewListener)
+}
+
+type redirectListener struct {
+	addr   string
+	ln     *net.UDPConn
+	logger logger.Logger
+	md     metadata
+}
+
+func NewListener(opts ...listener.Option) listener.Listener {
+	options := &listener.Options{}
+	for _, opt := range opts {
+		opt(options)
+	}
+	return &redirectListener{
+		addr:   options.Addr,
+		logger: options.Logger,
+	}
+}
+
+func (l *redirectListener) Init(md md.Metadata) (err error) {
+	if err = l.parseMetadata(md); err != nil {
+		return
+	}
+
+	laddr, err := net.ResolveUDPAddr("udp", l.addr)
+	if err != nil {
+		return
+	}
+
+	ln, err := l.listenUDP(laddr)
+	if err != nil {
+		return
+	}
+
+	l.ln = ln
+	return
+}
+
+func (l *redirectListener) Accept() (conn net.Conn, err error) {
+	return l.accept()
+}
+
+func (l *redirectListener) Addr() net.Addr {
+	return l.ln.LocalAddr()
+}
+
+func (l *redirectListener) Close() error {
+	return l.ln.Close()
+}

pkg/listener/redirect/udp/listener_linux.go

@@ -0,0 +1,37 @@
+package udp
+
+import (
+	"net"
+
+	"github.com/LiamHaworth/go-tproxy"
+	"github.com/go-gost/gost/pkg/common/bufpool"
+)
+
+func (l *redirectListener) listenUDP(addr *net.UDPAddr) (*net.UDPConn, error) {
+	return tproxy.ListenUDP("udp", addr)
+}
+
+func (l *redirectListener) accept() (conn net.Conn, err error) {
+	b := bufpool.Get(l.md.readBufferSize)
+
+	n, raddr, dstAddr, err := tproxy.ReadFromUDP(l.ln, b)
+	if err != nil {
+		l.logger.Error(err)
+		return
+	}
+
+	l.logger.Infof("%s >> %s", raddr.String(), dstAddr.String())
+
+	c, err := tproxy.DialUDP("udp", dstAddr, raddr)
+	if err != nil {
+		l.logger.Error(err)
+		return
+	}
+
+	conn = &redirConn{
+		Conn: c,
+		buf:  b[:n],
+		ttl:  l.md.ttl,
+	}
+	return
+}

pkg/listener/redirect/udp/listener_other.go

@@ -0,0 +1,16 @@
+//go:build !linux
+
+package udp
+
+import (
+	"errors"
+	"net"
+)
+
+func (l *redirectListener) listenUDP(addr *net.UDPAddr) (*net.UDPConn, error) {
+	return nil, errors.New("UDP redirect is not available on non-linux platform")
+}
+
+func (l *redirectListener) accept() (conn net.Conn, err error) {
+	return nil, errors.New("UDP redirect is not available on non-linux platform")
+}

pkg/listener/redirect/udp/metadata.go

@@ -0,0 +1,36 @@
+package udp
+
+import (
+	"time"
+
+	md "github.com/go-gost/gost/pkg/metadata"
+)
+
+const (
+	defaultTTL            = 60 * time.Second
+	defaultReadBufferSize = 1024
+)
+
+type metadata struct {
+	ttl            time.Duration
+	readBufferSize int
+}
+
+func (l *redirectListener) parseMetadata(md md.Metadata) (err error) {
+	const (
+		ttl            = "ttl"
+		readBufferSize = "readBufferSize"
+	)
+
+	l.md.ttl = md.GetDuration(ttl)
+	if l.md.ttl <= 0 {
+		l.md.ttl = defaultTTL
+	}
+
+	l.md.readBufferSize = md.GetInt(readBufferSize)
+	if l.md.readBufferSize <= 0 {
+		l.md.readBufferSize = defaultReadBufferSize
+	}
+
+	return
+}