fixed setting unix socket permissions

first call fchmod() to prevent TOCTTOU, then apply permissions using
chmod()

src/net/SocketUtil.cxx

@@ -34,11 +34,10 @@ socket_bind_listen(int domain, int type, int protocol,
 	if (!fd.CreateNonBlock(domain, type, protocol))
 		throw MakeSocketError("Failed to create socket");
 
-
 #ifdef HAVE_UN
 	if (domain == AF_UNIX) {
-		/* allow everybody to connect */
-		fchmod(fd.Get(), 0666);
+		/* Prevent access until right permissions are set */
+		fchmod(fd.Get(), 0);
 	}
 #endif