CakePHP表单垃圾邮件

Question

I have built a contact form using CakePHP following the tutorial at http://snook.ca/archives/cakephp/contact_form_cakephp

But would like to add a spam protector where the user is presented with a 5 letter character word such as BB42A that is random and the user has to type in before they can submit the form.

I have done some Googling but haven't found anything suitable online.

Any suggestions? Thanks

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Answer 1

What you need is called captcha.

Google search for cakePHP + captcha should come up with some cakePHP plugins. I don't develop in cakePHP, so I can't tell more.

You can, of course, make your own captcha and then integrate it in your website. To keep it short:

• Generate a random string;
• create an image with this string (imagecreate function on php.net);
• save the string as session variable;
• compare what user submitted with what's saved in session.

Code:

<?php
session_start();    

function rand_str($length = 6,
$chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890')
{
    $chars_length = (strlen($chars) - 1);
    $string = $chars{rand(0, $chars_length)};
    // Generate random string
    for ($i = 1; $i < $length; $i = strlen($string))
    {
        // Grab a random character from list
        $r = $chars{rand(0, $chars_length)};
        // Make sure the same two characters don't appear next to each other
        if ($r != $string{$i - 1}) $string .=  $r;
    }
    return $string;
}

header("Content-Type: image/png");
$im = @imagecreate(100, 40) or die("Cannot Initialize new GD image stream");
$background_color = imagecolorallocate($im, 0, 0, 0); // black
$text_color = imagecolorallocate($im, 255, 255,255); // white

$random_string = rand_str();
$_SESSION['captcha'] = $random_string;

imagestring($im, 5, 5, 5,  $random_string, $text_color);
imagepng($im);
imagedestroy($im);

?>