add auth for tun

go.mod

@@ -7,7 +7,7 @@ require (
 	github.com/asaskevich/govalidator v0.0.0-20210307081110-f21760c49a8d
 	github.com/gin-contrib/cors v1.3.1
 	github.com/gin-gonic/gin v1.7.7
-	github.com/go-gost/core v0.0.0-20220928034632-6e7a8f461903
+	github.com/go-gost/core v0.0.0-20221020130224-eb9d483127cc
 	github.com/go-gost/gosocks4 v0.0.1
 	github.com/go-gost/gosocks5 v0.3.1-0.20211109033403-d894d75b7f09
 	github.com/go-gost/relay v0.1.1-0.20211123134818-8ef7fd81ffd7

go.sum

@@ -98,8 +98,8 @@ github.com/gin-gonic/gin v1.7.7/go.mod h1:axIBovoeJpVj8S3BwE0uPMTeReE4+AfFtqpqaZ
 github.com/go-gl/glfw v0.0.0-20190409004039-e6da0acd62b1/go.mod h1:vR7hzQXu2zJy9AVAgeJqvqgH9Q5CA+iKCZ2gyEVpxRU=
 github.com/go-gl/glfw/v3.3/glfw v0.0.0-20191125211704-12ad95a8df72/go.mod h1:tQ2UAYgL5IevRw8kRxooKSPJfGvJ9fJQFa0TUsXzTg8=
 github.com/go-gl/glfw/v3.3/glfw v0.0.0-20200222043503-6f7a984d4dc4/go.mod h1:tQ2UAYgL5IevRw8kRxooKSPJfGvJ9fJQFa0TUsXzTg8=
-github.com/go-gost/core v0.0.0-20220928034632-6e7a8f461903 h1:Ye6Ns0+Ms63vC+nbe9sBgBDTr+l+ukPX18SvEJuWXUw=
+github.com/go-gost/core v0.0.0-20221020130224-eb9d483127cc h1:pS75VLwTkYLIC3n0QbfwE65N/1Zh8BnXfErNq9DGWd4=
-github.com/go-gost/core v0.0.0-20220928034632-6e7a8f461903/go.mod h1:bHVbCS9da6XtKNYMkMUVcck5UqDDUkyC37erVfs4GXQ=
+github.com/go-gost/core v0.0.0-20221020130224-eb9d483127cc/go.mod h1:bHVbCS9da6XtKNYMkMUVcck5UqDDUkyC37erVfs4GXQ=
 github.com/go-gost/gosocks4 v0.0.1 h1:+k1sec8HlELuQV7rWftIkmy8UijzUt2I6t+iMPlGB2s=
 github.com/go-gost/gosocks4 v0.0.1/go.mod h1:3B6L47HbU/qugDg4JnoFPHgJXE43Inz8Bah1QaN9qCc=
 github.com/go-gost/gosocks5 v0.3.1-0.20211109033403-d894d75b7f09 h1:A95M6UWcfZgOuJkQ7QLfG0Hs5peWIUSysCDNz4pfe04=

handler/tun/client.go

@@ -1,6 +1,7 @@
 package tun
 
 import (
+	"bytes"
 	"context"
 	"io"
 	"net"
@@ -15,12 +16,12 @@ import (
 )
 
 const (
-	// 4-byte magic header followed by 16-byte IP address
+	// 4-byte magic header followed by 16-byte IP address followed by 16-byte key.
-	keepAliveDataLength = 20
+	keepAliveDataLength = 36
 )
 
 var (
-	keepAliveHeader = []byte("GOST")
+	magicHeader = []byte("GOST")
 )
 
 func (h *tunHandler) handleClient(ctx context.Context, conn net.Conn, addr net.Addr, config *tun_util.Config, log logger.Logger) error {
@@ -38,22 +39,26 @@ func (h *tunHandler) handleClient(ctx context.Context, conn net.Conn, addr net.A
 	ctx, cancel := context.WithCancel(ctx)
 	defer cancel()
 
-	if h.md.keepAlivePeriod > 0 {
+	go h.keepAlive(ctx, cc, ip)
-		go h.keepAlive(ctx, cc, ip)
-	}
 
 	return h.transportClient(conn, cc, config, log)
 }
 
 func (h *tunHandler) keepAlive(ctx context.Context, conn net.Conn, ip net.IP) {
+	// handshake
 	var keepAliveData [keepAliveDataLength]byte
-	copy(keepAliveData[:4], keepAliveHeader) // magic header
+	copy(keepAliveData[:4], magicHeader) // magic header
-	copy(keepAliveData[4:], ip.To16())
+	copy(keepAliveData[4:20], ip.To16())
-
+	copy(keepAliveData[20:36], []byte(h.md.passphrase))
 	if _, err := conn.Write(keepAliveData[:]); err != nil {
 		return
 	}
 
+	if h.md.keepAlivePeriod <= 0 {
+		return
+	}
+	conn.SetReadDeadline(time.Now().Add(h.md.keepAlivePeriod * 3))
+
 	ticker := time.NewTicker(h.md.keepAlivePeriod)
 	defer ticker.Stop()
 
@@ -63,6 +68,7 @@ func (h *tunHandler) keepAlive(ctx context.Context, conn net.Conn, ip net.IP) {
 			if _, err := conn.Write(keepAliveData[:]); err != nil {
 				return
 			}
+			h.options.Logger.Debugf("keepalive sended")
 		case <-ctx.Done():
 			return
 		}
@@ -131,6 +137,16 @@ func (h *tunHandler) transportClient(tun net.Conn, conn net.Conn, config *tun_ut
 					return err
 				}
 
+				if n == keepAliveDataLength && bytes.Equal((*b)[:4], magicHeader) {
+					ip := net.IP((*b)[4:20])
+					log.Debugf("keepalive received at %v", ip)
+
+					if h.md.keepAlivePeriod > 0 {
+						conn.SetReadDeadline(time.Now().Add(h.md.keepAlivePeriod * 3))
+					}
+					return nil
+				}
+
 				if waterutil.IsIPv4((*b)[:n]) {
 					header, err := ipv4.ParseHeader((*b)[:n])
 					if err != nil {

handler/tun/metadata.go

@@ -14,6 +14,7 @@ const (
 type metadata struct {
 	bufferSize      int
 	keepAlivePeriod time.Duration
+	passphrase      string
 }
 
 func (h *tunHandler) parseMetadata(md mdata.Metadata) (err error) {
@@ -21,6 +22,7 @@ func (h *tunHandler) parseMetadata(md mdata.Metadata) (err error) {
 		bufferSize      = "bufferSize"
 		keepAlive       = "keepAlive"
 		keepAlivePeriod = "ttl"
+		passphrase      = "passphrase"
 	)
 
 	h.md.bufferSize = mdutil.GetInt(md, bufferSize)
@@ -34,5 +36,7 @@ func (h *tunHandler) parseMetadata(md mdata.Metadata) (err error) {
 			h.md.keepAlivePeriod = defaultKeepAlivePeriod
 		}
 	}
+
+	h.md.passphrase = mdutil.GetString(md, passphrase)
 	return
 }

handler/tun/server.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"io"
 	"net"
+	"net/netip"
 
 	"github.com/go-gost/core/common/bufpool"
 	"github.com/go-gost/core/logger"
@@ -25,6 +26,11 @@ func (h *tunHandler) handleServer(ctx context.Context, conn net.Conn, config *tu
 }
 
 func (h *tunHandler) transportServer(tun net.Conn, conn net.PacketConn, config *tun_util.Config, log logger.Logger) error {
+	tunIP, _, err := net.ParseCIDR(config.Net)
+	if err != nil {
+		return err
+	}
+
 	errc := make(chan error, 1)
 
 	go func() {
@@ -48,7 +54,7 @@ func (h *tunHandler) transportServer(tun net.Conn, conn net.PacketConn, config *
 					src, dst = header.Src, header.Dst
 
 					log.Tracef("%s >> %s %-4s %d/%-4d %-4x %d",
-						header.Src, header.Dst, ipProtocol(waterutil.IPv4Protocol((*b)[:n])),
+						src, dst, ipProtocol(waterutil.IPv4Protocol((*b)[:n])),
 						header.Len, header.TotalLen, header.ID, header.Flags)
 				} else if waterutil.IsIPv6((*b)[:n]) {
 					header, err := ipv6.ParseHeader((*b)[:n])
@@ -59,7 +65,7 @@ func (h *tunHandler) transportServer(tun net.Conn, conn net.PacketConn, config *
 					src, dst = header.Src, header.Dst
 
 					log.Tracef("%s >> %s %s %d %d",
-						header.Src, header.Dst,
+						src, dst,
 						ipProtocol(waterutil.IPProtocol(header.NextHeader)),
 						header.PayloadLen, header.TrafficClass)
 				} else {
@@ -98,9 +104,42 @@ func (h *tunHandler) transportServer(tun net.Conn, conn net.PacketConn, config *
 				if err != nil {
 					return err
 				}
-				if n == keepAliveDataLength && bytes.Equal((*b)[:4], keepAliveHeader) {
+				if n == keepAliveDataLength && bytes.Equal((*b)[:4], magicHeader) {
-					peerIP := net.IP((*b)[4:keepAliveDataLength])
+					peerIP := net.IP((*b)[4:20])
-					log.Debugf("keepalive from %v => %v", peerIP, addr)
+					key := bytes.TrimRight((*b)[20:36], "\x00")
+
+					if peerIP.Equal(tunIP.To16()) {
+						return nil
+					}
+
+					if auther := h.options.Auther; auther != nil {
+						ip := peerIP
+						if v := peerIP.To4(); ip != nil {
+							ip = v
+						}
+						if !auther.Authenticate(ip.String(), string(key)) {
+							log.Debugf("keepalive from %v => %v, auth FAILED", addr, peerIP)
+							return nil
+						}
+					}
+
+					log.Debugf("keepalive from %v => %v", addr, peerIP)
+
+					addrPort, err := netip.ParseAddrPort(addr.String())
+					if err != nil {
+						log.Warnf("keepalive from %v: %v", addr, err)
+						return nil
+					}
+					var keepAliveData [keepAliveDataLength]byte
+					copy(keepAliveData[:4], magicHeader) // magic header
+					a16 := addrPort.Addr().As16()
+					copy(keepAliveData[4:], a16[:])
+
+					if _, err := conn.WriteTo(keepAliveData[:], addr); err != nil {
+						log.Warnf("keepalive to %v: %v", addr, err)
+						return nil
+					}
+
 					h.updateRoute(peerIP, addr, log)
 					return nil
 				}
@@ -115,7 +154,7 @@ func (h *tunHandler) transportServer(tun net.Conn, conn net.PacketConn, config *
 					src, dst = header.Src, header.Dst
 
 					log.Tracef("%s >> %s %-4s %d/%-4d %-4x %d",
-						header.Src, header.Dst, ipProtocol(waterutil.IPv4Protocol((*b)[:n])),
+						src, dst, ipProtocol(waterutil.IPv4Protocol((*b)[:n])),
 						header.Len, header.TotalLen, header.ID, header.Flags)
 				} else if waterutil.IsIPv6((*b)[:n]) {
 					header, err := ipv6.ParseHeader((*b)[:n])
@@ -126,7 +165,7 @@ func (h *tunHandler) transportServer(tun net.Conn, conn net.PacketConn, config *
 					src, dst = header.Src, header.Dst
 
 					log.Tracef("%s > %s %s %d %d",
-						header.Src, header.Dst,
+						src, dst,
 						ipProtocol(waterutil.IPProtocol(header.NextHeader)),
 						header.PayloadLen, header.TrafficClass)
 				} else {
@@ -134,7 +173,7 @@ func (h *tunHandler) transportServer(tun net.Conn, conn net.PacketConn, config *
 					return nil
 				}
 
-				h.updateRoute(src, addr, log)
+				// h.updateRoute(src, addr, log)
 
 				if addr := h.findRouteFor(dst, config.Routes...); addr != nil {
 					log.Debugf("find route: %s -> %s", dst, addr)
@@ -156,7 +195,7 @@ func (h *tunHandler) transportServer(tun net.Conn, conn net.PacketConn, config *
 		}
 	}()
 
-	err := <-errc
+	err = <-errc
 	if err != nil && err == io.EOF {
 		err = nil
 	}