verification.php

<?php
/**
 * LimeSurvey
 * Copyright (C) 2007 The LimeSurvey Project Team / Carsten Schmitz
 * All rights reserved.
 * License: GNU/GPL License v2 or later, see LICENSE.php
 * LimeSurvey is free software. This version may have been modified pursuant
 * to the GNU General Public License, and as distributed it includes or
 * is derivative of works licensed under the GNU General Public License or
 * other free or open source software licenses.
 * See COPYRIGHT.php for copyright notices and details.
 *
 * $Id: verification.php 8639 2010-04-26 14:58:08Z c_schmitz $
 */

// Security Checked: POST, GET, SESSION, REQUEST, returnglobal, DB

// make sure you include this file only if the ImageCreate function does exist since it is an optional library
// Lets get into the session

require_once(dirname(__FILE__).'/config-defaults.php');
require_once(dirname(__FILE__).'/common.php');

if (isset($_GET['sid'])) $surveyid=(int)$_GET['sid']; else die();

$usquery = "SELECT stg_value FROM ".db_table_name("settings_global")." where stg_name='SessionName'";
$usresult = db_execute_assoc($usquery,'',true);          //Checked
if ($usresult)
{
    $usrow = $usresult->FetchRow();
    $stg_SessionName=$usrow['stg_value'];
    if ($surveyid)
    {
        @session_name($stg_SessionName.'-runtime-'.$surveyid);
    }
    else
    {
        @session_name($stg_SessionName.'-runtime-publicportal');
    }
}
else
{
    session_name("LimeSurveyRuntime-$surveyid");
}
session_set_cookie_params(0,$relativeurl.'/');
@session_start();

// header for png
Header("Content-Type: image/png");

// Create Image
$im = ImageCreate(75, 20);
$white = ImageColorAllocate($im, 255, 255, 255);
$black = ImageColorAllocate($im, 0, 0, 0);
$red = ImageColorAllocate($im, 255, 0, 0);
$blue = ImageColorAllocate($im, 0, 0, 255);
$grey_shade = ImageColorAllocate($im, 204, 204, 204);

// Create the random numberes
srand((double)microtime()*1000000);

$num1 = rand(1,5);
$found = false;
while ($found == false)
{
    $num2 = rand(1,100);
    if (preg_match('/^[0-9]+$/', $num2/5))
    {
        $found = true;
        break;
    }
}
$font_c_rand = rand(1,3);
if ($font_c_rand == 1)
{
    $font_color = $black;
} else if ($font_c_rand == 2)
{
    $font_color = $red;
} else if ($font_c_rand == 3)
{
    $font_color = $blue;
}

$font_rand = rand(1,3);
if ($font_rand == 1)
{
    $font = $rootdir."/fonts/verabd.ttf";
} else if ($font_rand == 2) {
    $font = $rootdir."/fonts/vera.ttf";
} else if ($font_rand == 3)
{
    $font = $rootdir."/fonts/verait.ttf";
}

$line_rand = rand(1,3);
if ($line_rand == 1)
{
    $line_color = $black;
} else if ($line_rand == 2)
{
    $line_color = $red;
} else if ($line_rand == 3)
{
    $line_color = $blue;
}

// Fill image, make transparent
ImageFill($im, 0, 0, $grey_shade);
//imagecolortransparent ($im, $white);
imageline($im,0,0,0,20,$line_color);
imageline($im,74,0,74,19,$line_color);
imageline($im,0,0,74,0,$line_color);
imageline($im,0,19,74,19,$line_color);
// Write math question in a nice TTF Font
ImageTTFText($im, 10, 0, 3, 16,$font_color, $font,  $num1." + ".$num2." =" );

// Display Image
ImagePNG($im);
ImageDestroy($im);

// Add the answer to the session
$_SESSION['secanswer'] = $num1+$num2;
?>