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)
+}

pkg/listener/option.go

@@ -1,13 +1,11 @@
 package listener
 
 import (
-	"github.com/go-gost/gost/pkg/chain"
 	"github.com/go-gost/gost/pkg/logger"
 )
 
 type Options struct {
 	Addr   string
-	Chain  *chain.Chain
 	Logger logger.Logger
 }
 
@@ -19,12 +17,6 @@ func AddrOption(addr string) Option {
 	}
 }
 
-func ChainOption(chain *chain.Chain) Option {
-	return func(opts *Options) {
-		opts.Chain = chain
-	}
-}
-
 func LoggerOption(logger logger.Logger) Option {
 	return func(opts *Options) {
 		opts.Logger = logger

pkg/listener/rtcp/listener.go

@@ -40,12 +40,16 @@ func NewListener(opts ...listener.Option) listener.Listener {
 	}
 	return &rtcpListener{
 		addr:   options.Addr,
-		chain:  options.Chain,
 		closed: make(chan struct{}),
 		logger: options.Logger,
 	}
 }
 
+// implements listener.Chainable interface
+func (l *rtcpListener) Chain(chain *chain.Chain) {
+	l.chain = chain
+}
+
 func (l *rtcpListener) Init(md md.Metadata) (err error) {
 	if err = l.parseMetadata(md); err != nil {
 		return

pkg/listener/rudp/listener.go

@@ -39,12 +39,16 @@ func NewListener(opts ...listener.Option) listener.Listener {
 	}
 	return &rudpListener{
 		addr:   options.Addr,
-		chain:  options.Chain,
 		closed: make(chan struct{}),
 		logger: options.Logger,
 	}
 }
 
+// implements listener.Chainable interface
+func (l *rudpListener) Chain(chain *chain.Chain) {
+	l.chain = chain
+}
+
 func (l *rudpListener) Init(md md.Metadata) (err error) {
 	if err = l.parseMetadata(md); err != nil {
 		return