Simple captcha for oscommerce contact form

Submitted by sandip on Thu, 07/24/2008 - 21:52. | Tags:

Embed the captcha image by calling a php script in "contact_us.php":

<img src="/image.php" width="60" height="20" alt="Please enter the values from this image" />

Edit contact_us.php file and exactly after the below line:

if (isset($HTTP_GET_VARS['action']) && ($HTTP_GET_VARS['action'] == 'send')) {

place the verification code:

        // Captcha check
        $t = trim($HTTP_POST_VARS['verify']);
        if ($t == "") {
                $captcha_error = "Enter the verification code!";
                $error = true;
                $messageStack->add('contact', $captcha_error);
        } else if (trim($_SESSION["thecode"]) == "") {
                $captcha_error = "No verification code generated!";
                $error = true;
                $messageStack->add('contact', $captcha_error);
        } else if ($_SESSION["thecode"] != strtoupper($t)) {
                $captcha_error = "Invalid verification code!";
                $error = true;
                $messageStack->add('contact', $captcha_error);
        }
        else
        { // End Captcha Check

Here's the "image.php" file that produces a simple captcha image:

<?php
include_once('includes/application_top.php');

function generate_verification() {
        srand((double)microtime()*1000000);
        $rand = rand(0,999999999);
        $thecode = substr(strtoupper(md5($rand)), 2, 5);
        $thecode = str_replace("O", "A", $thecode);
        $thecode = str_replace("0", "B", $thecode);
        $_SESSION['thecode'] = $thecode;
}

generate_verification();
header("Content-type: image/png");
$image = imagecreate(60,20);
$background_color = imagecolorallocate ($image, 219, 236, 255);
$blue = imagecolorallocate($image, 0, 90, 190);
imagestring($image,5,8,2,$_SESSION['thecode'],$blue);
imagepng($image);
imagedestroy($image);
tep_session_register('thecode');
?>