udp listener cleanup, add early port listen checks

client/client.go

@@ -106,6 +106,10 @@ func NewClient(c *Config) (*Client, error) {
 			}
 			hasStdio = true
 		}
+		//confirm non-reverse tunnel is available
+		if !r.Reverse && !r.CanListen() {
+			return nil, fmt.Errorf("Remote %s cannot listen", r.String())
+		}
 		client.computed.Remotes = append(client.computed.Remotes, r)
 	}
 	//set default log level

server/server_handler.go

@@ -109,24 +109,28 @@ func (s *Server) handleWebsocket(w http.ResponseWriter, req *http.Request) {
 		l.Infof("Client version (%s) differs from server version (%s)",
 			v, chshare.BuildVersion)
 	}
-	//confirm reverse tunnels are allowed
+	//validate remotes
 	for _, r := range c.Remotes {
-		if r.Reverse && !s.config.Reverse {
-			l.Debugf("Denied reverse port forwarding request, please enable --reverse")
-			failed(s.Errorf("Reverse port forwaring not enabled on server"))
-			return
-		}
-	}
-	//if user is provided, ensure they have
-	//access to the desired remotes
-	if user != nil {
-		for _, r := range c.Remotes {
+		//if user is provided, ensure they have
+		//access to the desired remotes
+		if user != nil {
 			addr := r.UserAddr()
 			if !user.HasAccess(addr) {
 				failed(s.Errorf("access to '%s' denied", addr))
 				return
 			}
 		}
+		//confirm reverse tunnels are allowed
+		if r.Reverse && !s.config.Reverse {
+			l.Debugf("Denied reverse port forwarding request, please enable --reverse")
+			failed(s.Errorf("Reverse port forwaring not enabled on server"))
+			return
+		}
+		//confirm reverse tunnel is available
+		if r.Reverse && !r.CanListen() {
+			failed(s.Errorf("Remote %s cannot listen", r.String()))
+			return
+		}
 	}
 	//successfuly validated config!
 	r.Reply(true, nil)

share/settings/remote.go

@@ -2,6 +2,7 @@ package settings
 
 import (
 	"errors"
+	"net"
 	"net/url"
 	"regexp"
 	"strconv"
@@ -223,6 +224,33 @@ func (r Remote) UserAddr() string {
 	return r.RemoteHost + ":" + r.RemotePort
 }
 
+//CanListen checks if the port can be listened on
+func (r Remote) CanListen() bool {
+	switch r.LocalProto {
+	case "tcp":
+		//valid
+		conn, err := net.Listen("tcp", r.Local())
+		if err == nil {
+			conn.Close()
+			return true
+		}
+		return false
+	case "udp":
+		addr, err := net.ResolveUDPAddr("udp", r.Local())
+		if err != nil {
+			return false
+		}
+		conn, err := net.ListenUDP(r.LocalProto, addr)
+		if err == nil {
+			conn.Close()
+			return true
+		}
+		return false
+	}
+	//invalid
+	return false
+}
+
 type Remotes []*Remote
 
 //Filter out forward reversed/non-reversed remotes

share/tunnel/tunnel_in_proxy.go

@@ -52,14 +52,14 @@ func (p *Proxy) listen() error {
 		if err != nil {
 			return p.Errorf("tcp: %s", err)
 		}
-		p.Debugf("Listening")
+		p.Infof("Listening")
 		p.tcp = l
 	} else if p.remote.LocalProto == "udp" {
 		l, err := listenUDP(p.Logger, p.sshTun, p.remote)
 		if err != nil {
 			return err
 		}
-		p.Debugf("Listening")
+		p.Infof("Listening")
 		p.udp = l
 	} else {
 		return p.Errorf("unknown local proto")
@@ -70,7 +70,6 @@ func (p *Proxy) listen() error {
 //Run enables the proxy and blocks while its active,
 //close the proxy by cancelling the context.
 func (p *Proxy) Run(ctx context.Context) error {
-	defer p.Debugf("Closed")
 	if p.remote.Stdio {
 		return p.runStdio(ctx)
 	} else if p.remote.LocalProto == "tcp" {
@@ -82,6 +81,7 @@ func (p *Proxy) Run(ctx context.Context) error {
 }
 
 func (p *Proxy) runStdio(ctx context.Context) error {
+	defer p.Infof("Closed")
 	for {
 		p.pipeRemote(ctx, cio.Stdio)
 		select {

share/tunnel/tunnel_in_proxy_udp.go

@@ -13,6 +13,7 @@ import (
 
 	"github.com/jpillora/chisel/share/cio"
 	"github.com/jpillora/chisel/share/settings"
+	"github.com/jpillora/sizestr"
 	"golang.org/x/crypto/ssh"
 	"golang.org/x/sync/errgroup"
 )
@@ -59,6 +60,7 @@ type udpListener struct {
 }
 
 func (u *udpListener) run(ctx context.Context) error {
+	defer u.inbound.Close()
 	//udp doesnt accept connections,
 	//udp simply forwards packets
 	//and therefore only needs to listen
@@ -73,7 +75,7 @@ func (u *udpListener) run(ctx context.Context) error {
 		u.Debugf("listen: %s", err)
 		return err
 	}
-	u.Debugf("sent %d, received %d", u.sent, u.recv)
+	u.Debugf("Close (sent %s received %s)", sizestr.ToString(u.sent), sizestr.ToString(u.recv))
 	return nil
 }
 

test/e2e/setup_test.go

@@ -119,7 +119,7 @@ func post(url, body string) (string, error) {
 }
 
 func availablePort() string {
-	l, err := net.Listen("tcp4", "127.0.0.1:0")
+	l, err := net.Listen("tcp", "127.0.0.1:0")
 	if err != nil {
 		log.Panic(err)
 	}