+ +
+

CAPTCHA Helper

+

The CAPTCHA Helper file contains functions that assist in creating +CAPTCHA images.

+ +
+

Loading this Helper

+

This helper is loaded using the following code:

+
$this->load->helper('captcha');
+
+
+
+
+

Using the CAPTCHA helper

+

Once loaded you can generate a CAPTCHA like this:

+
$vals = array(
+        'word'          => 'Random word',
+        'img_path'      => './captcha/',
+        'img_url'       => 'http://example.com/captcha/',
+        'font_path'     => './path/to/fonts/texb.ttf',
+        'img_width'     => '150',
+        'img_height'    => 30,
+        'expiration'    => 7200,
+        'word_length'   => 8,
+        'font_size'     => 16,
+        'img_id'        => 'Imageid',
+        'pool'          => '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ',
+
+        // White background and border, black text and red grid
+        'colors'        => array(
+                'background' => array(255, 255, 255),
+                'border' => array(255, 255, 255),
+                'text' => array(0, 0, 0),
+                'grid' => array(255, 40, 40)
+        )
+);
+
+$cap = create_captcha($vals);
+echo $cap['image'];
+
+
+
    +
  • The captcha function requires the GD image library.
    • +
  • Only the img_path and img_url are required.
    • +
  • 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.
    • +
  • If you do not specify a path to a TRUE TYPE font, the native ugly GD +font will be used.
    • +
  • The “captcha” directory must be writable
    • +
  • 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.
    • +
  • word_length defaults to 8, pool defaults to ‘0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ’
    • +
  • font_size defaults to 16, the native GD font has a size limit. Specify a “true type” font for bigger sizes.
    • +
  • The img_id will be set as the “id” of the captcha image.
    • +
  • If any of the colors values is missing, it will be replaced by the default.
    • +
+
+

Adding a Database

+

In order for the captcha function to prevent someone from submitting, +you will need to add the information returned from create_captcha() +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.

+

Here is a table prototype:

+
CREATE TABLE captcha (
+        captcha_id bigint(13) unsigned NOT NULL auto_increment,
+        captcha_time int(10) unsigned NOT NULL,
+        ip_address varchar(45) NOT NULL,
+        word varchar(20) NOT NULL,
+        PRIMARY KEY `captcha_id` (`captcha_id`),
+        KEY `word` (`word`)
+);
+
+
+

Here is an example of usage with a database. On the page where the +CAPTCHA will be shown you’ll have something like this:

+
$this->load->helper('captcha');
+$vals = array(
+        'img_path'      => './captcha/',
+        'img_url'       => 'http://example.com/captcha/'
+);
+
+$cap = create_captcha($vals);
+$data = array(
+        'captcha_time'  => $cap['time'],
+        'ip_address'    => $this->input->ip_address(),
+        'word'          => $cap['word']
+);
+
+$query = $this->db->insert_string('captcha', $data);
+$this->db->query($query);
+
+echo 'Submit the word you see below:';
+echo $cap['image'];
+echo '<input type="text" name="captcha" value="" />';
+
+
+

Then, on the page that accepts the submission you’ll have something like +this:

+
// First, delete old captchas
+$expiration = time() - 7200; // Two hour limit
+$this->db->where('captcha_time < ', $expiration)
+        ->delete('captcha');
+
+// Then see if a captcha exists:
+$sql = 'SELECT COUNT(*) AS count FROM captcha WHERE word = ? AND ip_address = ? AND captcha_time > ?';
+$binds = array($_POST['captcha'], $this->input->ip_address(), $expiration);
+$query = $this->db->query($sql, $binds);
+$row = $query->row();
+
+if ($row->count == 0)
+{
+        echo 'You must submit the word that appears in the image.';
+}
+
+
+
+
+
+

Available Functions

+

The following functions are available:

+
+
+create_captcha([$data = ''[, $img_path = ''[, $img_url = ''[, $font_path = '']]]])
+
+++ + + + + + + + +
Parameters:
    +
  • $data (array) – Array of data for the CAPTCHA
    • +
  • $img_path (string) – Path to create the image in
    • +
  • $img_url (string) – URL to the CAPTCHA image folder
    • +
  • $font_path (string) – Server path to font
    • +
+
Returns:

array(‘word’ => $word, ‘time’ => $now, ‘image’ => $img)

+
Return type:

array

+
+

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.

+
array(
+        'image' => IMAGE TAG
+        'time'  => TIMESTAMP (in microtime)
+        'word'  => CAPTCHA WORD
+)
+
+
+

The image is the actual image tag:

+
<img src="http://example.com/captcha/12345.jpg" width="140" height="50" />
+
+
+

The time is the micro timestamp used as the image name without the +file extension. It will be a number like this: 1139612155.3422

+

The word is the word that appears in the captcha image, which if not +supplied to the function, will be a random string.

+
+ +
+
+ + +