add kcp dialer

pkg/dialer/tcp/metadata.go

@@ -1,6 +1,10 @@
 package tcp
 
-import "time"
+import (
+	"time"
+
+	md "github.com/go-gost/gost/pkg/metadata"
+)
 
 const (
 	dialTimeout = "dialTimeout"
@@ -13,3 +17,7 @@ const (
 type metadata struct {
 	dialTimeout time.Duration
 }
+
+func (d *tcpDialer) parseMetadata(md md.Metadata) (err error) {
+	return
+}