diff --git a/demo_test/vendor/golang.org/x/sys/unix/sockcmsg_linux.go b/demo_test/vendor/golang.org/x/sys/unix/sockcmsg_linux.go
new file mode 100644
index 0000000..8bf4570
--- /dev/null
+++ b/demo_test/vendor/golang.org/x/sys/unix/sockcmsg_linux.go
@@ -0,0 +1,36 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Socket control messages
+
+package unix
+
+import "unsafe"
+
+// UnixCredentials encodes credentials into a socket control message
+// for sending to another process. This can be used for
+// authentication.
+func UnixCredentials(ucred *Ucred) []byte {
+	b := make([]byte, CmsgSpace(SizeofUcred))
+	h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
+	h.Level = SOL_SOCKET
+	h.Type = SCM_CREDENTIALS
+	h.SetLen(CmsgLen(SizeofUcred))
+	*(*Ucred)(h.data(0)) = *ucred
+	return b
+}
+
+// ParseUnixCredentials decodes a socket control message that contains
+// credentials in a Ucred structure. To receive such a message, the
+// SO_PASSCRED option must be enabled on the socket.
+func ParseUnixCredentials(m *SocketControlMessage) (*Ucred, error) {
+	if m.Header.Level != SOL_SOCKET {
+		return nil, EINVAL
+	}
+	if m.Header.Type != SCM_CREDENTIALS {
+		return nil, EINVAL
+	}
+	ucred := *(*Ucred)(unsafe.Pointer(&m.Data[0]))
+	return &ucred, nil
+}