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| <h1>CAPTCHA Helper</h1> |
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| <p>The CAPTCHA Helper file contains functions that assist in creating CAPTCHA images.</p> |
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| <h2>Loading this Helper</h2> |
| |
| <p>This helper is loaded using the following code:</p> |
| <code>$this->load->helper('captcha');</code> |
| |
| <p>The following functions are available:</p> |
| |
| <h2>create_captcha(<var>$data</var>)</h2> |
| |
| <p>Takes an array of information to generate the CAPTCHA as input and creates the image to your specifications, returning an array of associative data about the image.</p> |
| |
| <code>[array]<br /> |
| (<br /> |
| 'image' => IMAGE TAG<br /> |
| 'time' => TIMESTAMP (in microtime)<br /> |
| 'word' => CAPTCHA WORD<br /> |
| )</code> |
| |
| <p>The "image" is the actual image tag: |
| <code><img src="http://example.com/captcha/12345.jpg" width="140" height="50" /></code></p> |
| |
| <p>The "time" is the micro timestamp used as the image name without the file |
| extension. It will be a number like this: 1139612155.3422</p> |
| |
| <p>The "word" is the word that appears in the captcha image, which if not |
| supplied to the function, will be a random string.</p> |
| |
| <h3>Using the CAPTCHA helper</h3> |
| |
| <p>Once loaded you can generate a captcha like this:</p> |
| |
| <code>$vals = array(<br /> |
| 'word' => 'Random word',<br /> |
| 'img_path' => './captcha/',<br /> |
| 'img_url' => 'http://example.com/captcha/',<br /> |
| 'font_path' => './path/to/fonts/texb.ttf',<br /> |
| 'img_width' => '150',<br /> |
| 'img_height' => 30,<br /> |
| 'expiration' => 7200<br /> |
| );<br /> |
| <br /> |
| $cap = create_captcha($vals);<br /> |
| echo $cap['image'];</code> |
| |
| <ul> |
| <li>The captcha function requires the GD image library.</li> |
| <li>Only the img_path and img_url are required.</li> |
| <li>If a "word" is not supplied, the function will generate a random |
| ASCII string. You might put together your own word library that |
| you can draw randomly from.</li> |
| <li>If you do not specify a path to a TRUE TYPE font, the native ugly GD |
| font will be used.</li> |
| <li>The "captcha" folder must be writable (666, or 777)</li> |
| <li>The "expiration" (in seconds) signifies how long an image will |
| remain in the captcha folder before it will be deleted. The default |
| is two hours.</li> |
| </ul> |
| |
| <h3>Adding a Database</h3> |
| |
| <p>In order for the captcha function to prevent someone from submitting, you will need |
| to add the information returned from <kbd>create_captcha()</kbd> function to your database. |
| Then, when the data from the form is submitted by the user you will need to verify |
| that the data exists in the database and has not expired.</p> |
| |
| <p>Here is a table prototype:</p> |
| |
| <code>CREATE TABLE captcha (<br /> |
| captcha_id bigint(13) unsigned NOT NULL auto_increment,<br /> |
| captcha_time int(10) unsigned NOT NULL,<br /> |
| ip_address varchar(16) default '0' NOT NULL,<br /> |
| word varchar(20) NOT NULL,<br /> |
| PRIMARY KEY `captcha_id` (`captcha_id`),<br /> |
| KEY `word` (`word`)<br /> |
| );</code> |
| |
| <p>Here is an example of usage with a database. On the page where the CAPTCHA will be shown you'll have something like this:</p> |
| |
| <code>$this->load->helper('captcha');<br /> |
| $vals = array(<br /> |
| 'img_path' => './captcha/',<br /> |
| 'img_url' => 'http://example.com/captcha/'<br /> |
| );<br /> |
| <br /> |
| $cap = create_captcha($vals);<br /> |
| <br /> |
| $data = array(<br /> |
| 'captcha_time' => $cap['time'],<br /> |
| 'ip_address' => $this->input->ip_address(),<br /> |
| 'word' => $cap['word']<br /> |
| );<br /> |
| <br /> |
| $query = $this->db->insert_string('captcha', $data);<br /> |
| $this->db->query($query);<br /> |
| <br /> |
| echo 'Submit the word you see below:';<br /> |
| echo $cap['image'];<br /> |
| echo '<input type="text" name="captcha" value="" />';</code> |
| |
| <p>Then, on the page that accepts the submission you'll have something like this:</p> |
| |
| <code>// First, delete old captchas<br /> |
| $expiration = time()-7200; // Two hour limit<br /> |
| $this->db->query("DELETE FROM captcha WHERE captcha_time < ".$expiration); <br /> |
| <br /> |
| // Then see if a captcha exists:<br /> |
| $sql = "SELECT COUNT(*) AS count FROM captcha WHERE word = ? AND ip_address = ? AND captcha_time > ?";<br /> |
| $binds = array($_POST['captcha'], $this->input->ip_address(), $expiration);<br /> |
| $query = $this->db->query($sql, $binds);<br /> |
| $row = $query->row();<br /> |
| <br /> |
| if ($row->count == 0)<br /> |
| {<br /> |
| echo "You must submit the word that appears in the image";<br /> |
| }</code> |
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