fix (plg_backend_nfs): support auxiliary gids

server/plugin/plg_backend_nfs/auth_unix.go

@@ -9,26 +9,28 @@ import (
 	"github.com/vmware/go-nfs-client/nfs/xdr"
 )
 
+// ref: https://datatracker.ietf.org/doc/html/rfc5531#section-8.2
+// so far we only have implemented AUTH_SYS but one day we might want to add support
+// for RPCSEC_GSS as detailed in https://datatracker.ietf.org/doc/html/rfc2203
 type AuthUnix struct {
 	Stamp       uint32
 	Machinename string
 	Uid         uint32
 	Gid         uint32
-	GidLen      uint32
 	Gids        []uint32
 }
 
-func NewAuth(machineName string, uid, gid uint32) rpc.Auth {
+func NewUnixAuth(machineName string, uid, gid uint32, gids []uint32) rpc.Auth {
 	w := new(bytes.Buffer)
 	xdr.Write(w, AuthUnix{
 		Stamp:       rand.New(rand.NewSource(time.Now().UnixNano())).Uint32(),
 		Machinename: machineName,
-		Uid:         uid,
-		Gid:         gid,
-		GidLen:      1,
+		Uid:         1000,
+		Gid:         1000,
+		Gids:        gids,
 	})
 	return rpc.Auth{
-		1,
+		1, // = AUTH_SYS in RFC5531
 		w.Bytes(),
 	}
 }