$entered_map = "mp_crash";
$sv_maprotation = $this->mod->rconRcon("sv_maprotation");
// set sv_maprotation "map mp_crash map mp_backlot map mp_crossfire map mp_vacant"
$maps = explode("map ", $sv_maprotation);

if(in_array($entered_map,$maps)) {
    $this->mod->rconChangeMap($entered_map,$gametype);
} else {
    // map nicht gefunden
}