php优化,该怎么处理

//define server info begin
$servername = "192.168.1.182";  
$serverusername = "whh";  
$serverpassword = "whh"; 
$database="whh";
$usertable="user";
$userfield="user_name";
$passwordfield="password";
//define server info end

$fh  = fopen("php://stdin", 'r');
$stdout = fopen('php://stdout', 'w');
$fs = fopen("auth-log.txt." . getmypid(), 'a');

if(!$fh){
    die("Cannot open STDIN\n");
}

do{
    $lenBytes = fgets($fh, 3);
    $len = unpack('n', $lenBytes);
    $len = $len[1];
    if($len<1) continue;
    $msg = fgets($fh, $len+1);
    $toks=explode(':',$msg);
    fwrite($fs, $msg . "\n");

    $method = array_shift($toks);
    fwrite($fs, "$method\n");
    $result = false;

    switch($method){
        case 'auth':
            list($username, $server, $password) = $toks;
            $password = trim($password);
            fwrite($fs, "checking user: $username and password $password\n");
            //check password begin
						$conn=mysql_connect($servername, $serverusername, $serverpassword); 
						mysql_query("set names 'utf8'");
						if(!$conn){                              
						  die("could not connect to the database");
						}
						$db_select=mysql_select_db($database);//选择数据库        
						if(!$db_select)
						{
						  die("could not to the database");
						}
						$query="select * from $usertable where $userfield = '$username' and $passwordfield='$password'";//构建查询语句
						$result=mysql_query($query);//执行查询
						$count=mysql_numrows($result);//取得条数
						mysql_close($conn);
						if($count > 0){
							$result = true;
						}else{
							$result = false;
						}
						//check password end
            break;

        case 'isuser':
            list($username, $server) = $toks;
            //check password begin
						$conn=mysql_connect($servername, $serverusername, $serverpassword); 
						mysql_query("set names 'utf8'");
						if(!$conn){                              
						  die("could not connect to the database");
						}
						$db_select=mysql_select_db($database);//选择数据库        
						if(!$db_select)
						{
						  die("could not to the database");
						}
						$query="select * from $usertable where $userfield = '$username'";//构建查询语句
						$result=mysql_query($query);//执行查询
						$count=mysql_numrows($result);//取得条数
						mysql_close($conn);
						if($count > 0){
							$result = true;
						}else{
							$result = false;
						}
						//check password end
            break;

        default:
            $result = false;
    }
        $message =  @pack("nn", 2, $result);
        fwrite($stdout, $message);
        $dump = @unpack("nn", $message);
        $dump = $dump["n"];
        fwrite($fs, $dump . "\n");
        flush();
} while(true);