解析dedeCMS验证码的实现代码

鹿城哥 發表於 2023-6-4 00:00:00

如下所示:

复制代码 代码如下:

 
<?php 
$rndstring = ''; 
for($i=0; $i<4; $i++) $rndstring .= chr(mt_rand(65,90)); 
//如果支持GD，则绘图 
if(function_exists("imagecreate")) 
{ 
//Firefox部份情况会多次请求的问题，5秒内刷新页面将不改变session 
$ntime = time(); 
if(empty($_SESSION['dd_ckstr_last']) || empty($_SESSION['dd_ckstr']) || ($ntime - $_SESSION['dd_ckstr_last'] > 5)) 
{ 
 $_SESSION['dd_ckstr'] = strtolower($rndstring); 
 $_SESSION['dd_ckstr_last'] = $ntime; 
} 
$rndstring = $_SESSION['dd_ckstr']; 
$rndcodelen = strlen($rndstring); 
//创建图片，并设置背景色 
$im = imagecreate(50,20); 
ImageColorAllocate($im, 255,255,255); 
//背景线 
$lineColor1 = ImageColorAllocate($im,240,220,180); 
$lineColor2 = ImageColorAllocate($im,250,250,170); 
for($j=3;$j<=16;$j=$j+3) 
{ 
 imageline($im,2,$j,48,$j,$lineColor1); 
} 
for($j=2;$j<52;$j=$j+(mt_rand(3,6))) 
{ 
 imageline($im,$j,2,$j-6,18,$lineColor2); 
} 
//画边框 
$bordercolor = ImageColorAllocate($im, 0x99,0x99,0x99); 
imagerectangle($im, 0, 0, 49, 19, $bordercolor); 
//输出文字 
$fontColor = ImageColorAllocate($im, 48,61,50); 
for($i=0;$i<$rndcodelen;$i++) 
{ 
 $bc = mt_rand(0,1); 
 $rndstring[$i] = strtoupper($rndstring[$i]); 
 imagestring($im, 5, $i*10+6, mt_rand(2,4), $rndstring[$i], $fontColor); 
} 
header("Pragma:no-cache/r/n"); 
header("Cache-Control:no-cache/r/n"); 
header("Expires:0/r/n"); 
//输出特定类型的图片格式，优先级为 gif -> jpg ->png 
if(function_exists("imagejpeg")) 
{ 
 header("content-type:image/jpeg/r/n"); 
 imagejpeg($im); 
} 
else 
{ 
 header("content-type:image/png/r/n"); 
 imagepng($im); 
} 
ImageDestroy($im); 
exit(); 
} 
else 
{ 
//不支持GD，只输出字母 ABCD 
$_SESSION['dd_ckstr'] = "abcd"; 
$_SESSION['dd_ckstr_last'] = ''; 
header("content-type:image/jpeg/r/n"); 
header("Pragma:no-cache/r/n"); 
header("Cache-Control:no-cache/r/n"); 
header("Expires:0/r/n"); 
$fp = fopen("data/vdcode.jpg","r"); 
echo fread($fp,filesize("data/vdcode.jpg")); 
fclose($fp); 
exit(); 
} 
?>

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解析dedeCMS验证码的实现代码