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+CAPTCHA Helper
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+
+<h1>CAPTCHA Helper</h1>
+
+<p>The CAPTCHA Helper file contains functions that assist in creating CAPTCHA images.</p>
+
+
+<h2>Loading this Helper</h2>
+
+<p>This helper is loaded using the following code:</p>
+<code>$this->load->helper('captcha');</code>
+
+<p>The following functions are available:</p>
+
+<h2>captcha_create(<var>$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 />
+&nbsp;&nbsp;'image' => IMAGE TAG<br />
+&nbsp;&nbsp;'time' => TIMESTAMP (in microtime)<br />
+&nbsp;&nbsp;'word' => CAPTCHA WORD<br />
+)</code>
+
+ <p>The "image" is the actual image tag:
+<code>&lt;img src=&quot;http://example.com/captcha/12345.jpg&quot; width=&quot;140&quot; height=&quot;50&quot; /&gt;</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 plugin</h3>
+
+ <p>Once loaded you can generate a captcha like this:</p>
+
+<code>$vals = array(<br />
+&nbsp;&nbsp;&nbsp;&nbsp;'word' => 'Random word',<br />
+&nbsp;&nbsp;&nbsp;&nbsp;'img_path' => './captcha/',<br />
+&nbsp;&nbsp;&nbsp;&nbsp;'img_url' => 'http://example.com/captcha/',<br />
+&nbsp;&nbsp;&nbsp;&nbsp;'font_path' => './path/to/fonts/texb.ttf',<br />
+&nbsp;&nbsp;&nbsp;&nbsp;'img_width' => '150',<br />
+&nbsp;&nbsp;&nbsp;&nbsp;'img_height' => 30,<br />
+&nbsp;&nbsp;&nbsp;&nbsp;'expiration' => 7200<br />
+&nbsp;&nbsp;&nbsp;&nbsp;);<br />
+<br />
+$cap = create_captcha($vals);<br />
+echo $cap['image'];</code>
+
+ <ul>
+ <li>The captcha function requires the GD image library.</li>
+ <li>Only the img_path and img_url are required.</li>
+ <li>If a "word" is not supplied, the function will generate a random
+ ASCII string. You might put together your own word library that
+ you can draw randomly from.</li>
+ <li>If you do not specify a path to a TRUE TYPE font, the native ugly GD
+ font will be used.</li>
+ <li>The "captcha" folder must be writable (666, or 777)</li>
+ <li>The "expiration" (in seconds) signifies how long an image will
+ remain in the captcha folder before it will be deleted. The default
+ is two hours.</li>
+ </ul>
+
+ <h3>Adding a Database</h3>
+
+ <p>In order for the captcha function to prevent someone from submitting, you will need
+ to add the information returned from <kbd>create_captcha()</kbd> function to your database.
+ Then, when the data from the form is submitted by the user you will need to verify
+ that the data exists in the database and has not expired.</p>
+
+ <p>Here is a table prototype:</p>
+
+<code>CREATE TABLE captcha (<br />
+&nbsp;captcha_id bigint(13) unsigned NOT NULL auto_increment,<br />
+&nbsp;captcha_time int(10) unsigned NOT NULL,<br />
+&nbsp;ip_address varchar(16) default '0' NOT NULL,<br />
+&nbsp;word varchar(20) NOT NULL,<br />
+&nbsp;PRIMARY KEY `captcha_id` (`captcha_id`),<br />
+&nbsp;KEY `word` (`word`)<br />
+)</code>
+
+ <p>Here is an example of usage with a database. On the page where the CAPTCHA will be shown you'll have something like this:</p>
+
+<code>$this-&gt;load-&gt;plugin(&#x27;captcha&#x27;);<br />
+$vals = array(<br />
+&nbsp;&nbsp;&nbsp;&nbsp;&#x27;img_path&#x27; =&gt; &#x27;./captcha/&#x27;,<br />
+&nbsp;&nbsp;&nbsp;&nbsp;&#x27;img_url&#x27; =&gt; &#x27;http://example.com/captcha/&#x27;<br />
+&nbsp;&nbsp;&nbsp;&nbsp;);<br />
+<br />
+$cap = create_captcha($vals);<br />
+<br />
+$data = array(<br />
+&nbsp;&nbsp;&nbsp;&nbsp;&#x27;captcha_time&#x27; =&gt; $cap[&#x27;time&#x27;],<br />
+&nbsp;&nbsp;&nbsp;&nbsp;&#x27;ip_address&#x27; =&gt; $this-&gt;input-&gt;ip_address(),<br />
+&nbsp;&nbsp;&nbsp;&nbsp;&#x27;word&#x27; =&gt; $cap[&#x27;word&#x27;]<br />
+&nbsp;&nbsp;&nbsp;&nbsp;);<br />
+<br />
+$query = $this-&gt;db-&gt;insert_string(&#x27;captcha&#x27;, $data);<br />
+$this-&gt;db-&gt;query($query);<br />
+<br />
+echo &#x27;Submit the word you see below:&#x27;;<br />
+echo $cap[&#x27;image&#x27;];<br />
+echo &#x27;&lt;input type=&quot;text&quot; name=&quot;captcha&quot; value=&quot;&quot; /&gt;&#x27;;</code>
+
+ <p>Then, on the page that accepts the submission you'll have something like this:</p>
+
+<code>// First, delete old captchas<br />
+$expiration = time()-7200; // Two hour limit<br />
+$this-&gt;db-&gt;query(&quot;DELETE FROM captcha WHERE captcha_time &lt; &quot;.$expiration); <br />
+<br />
+// Then see if a captcha exists:<br />
+$sql = &quot;SELECT COUNT(*) AS count FROM captcha WHERE word = ? AND ip_address = ? AND date &gt; ?&quot;;<br />
+$binds = array($_POST[&#x27;captcha&#x27;], $this-&gt;input-&gt;ip_address(), $expiration);<br />
+$query = $this-&gt;db-&gt;query($sql, $binds);<br />
+$row = $query-&gt;row();<br />
+<br />
+if ($row-&gt;count == 0)<br />
+{<br />
+&nbsp;&nbsp;&nbsp;&nbsp;echo &quot;You must submit the word that appears in the image&quot;;<br />
+}</code>
+
+</div>
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