캡차 관련

/**
 * 랜던한 문자열을 길이만큼 반환
 * @param int $length
 * @param string $chars
 * @return string
 */
function getRandStr($length = 32, $chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890') {
    $chars_length = (strlen($chars) - 1); 
    $string = $chars{rand(0, $chars_length)};
    for ($i = 1; $i < $length; $i = strlen($string)) {
        $r = $chars{rand(0, $chars_length)};         
        if ($r != $string{$i - 1}) $string .=  $r;
    }     
    return $string;
}

/**
 * 캡차처리(getRandStr 필요함, func.other.php)
 * @param string $text
 * @param int $font_size
 * @param int $width
 * @param int $height
 * @param int $xpos
 * @param int $ypos
 */
function captcha($font_size, $width, $height, $xpos, $ypos) {
    $text = getRandStr(6, $chars = 'abcdefghijkmnpqrstuvwxyz23456789');
    $_SESSION['sess_captcha'] = $text;
    
    header ("Content-type: image/png");
    
    $im = imagecreate($width, $height);
    $white = imagecolorallocate ($im, 240, 240, 240); 
    $grey = imagecolorallocate ($im, 110, 110, 110); 

    imagettftext($im, $font_size, 0, $xpos, $ypos, $grey, CFG_LIB_PATH.'/fonts/unispace.ttf', $text);
    
    imagepng($im); 
    imagedestroy($im); 
}