add relay proxy

pkg/listener/listener.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"net"
 
+	"github.com/go-gost/gost/pkg/chain"
 	"github.com/go-gost/gost/pkg/metadata"
 )
 
@@ -21,3 +22,7 @@ type Listener interface {
 type Accepter interface {
 	Accept() (net.Conn, error)
 }
+
+type Chainable interface {
+	Chain(chain *chain.Chain)
+}