Add 'valid_url' rule to Form Validation (issue bcit-ci#1966)

system/libraries/Form_validation.php

@@ -1083,6 +1083,48 @@ public function exact_length($str, $val)
 
 	// --------------------------------------------------------------------
 
+	/**
+	 * Valid URL
+	 *
+	 * @param	string	$str
+	 * @return	bool
+	 */
+	public function valid_url($str)
+	{
+		if (empty($str))
+		{
+			return FALSE;
+		}
+		elseif (preg_match('/^(?:([^:]*)\:)?\/\/(.+)$/', $str, $matches))
+		{
+			if (empty($matches[2]))
+			{
+				return FALSE;
+			}
+			elseif ( ! in_array($matches[1], array('http', 'https'), TRUE))
+			{
+				return FALSE;
+			}
+
+			$str = $matches[2];
+		}
+
+		$str = 'http://'.$str;
+
+		// There's a bug affecting PHP 5.2.13, 5.3.2 that considers the
+		// underscore to be a valid hostname character instead of a dash.
+		// Reference: https://bugs.php.net/bug.php?id=51192
+		if (version_compare(PHP_VERSION, '5.2.13', '==') === 0 OR version_compare(PHP_VERSION, '5.3.2', '==') === 0)
+		{
+			sscanf($str, 'http://%[^/]', $host);
+			$str = substr_replace($str, strtr($host, array('_' => '-', '-' => '_')), 7, strlen($host));
+		}
+
+		return (filter_var($str, FILTER_VALIDATE_URL) !== FALSE);
+	}
+
+	// --------------------------------------------------------------------
+
 	/**
 	 * Valid Email
 	 *

user_guide_src/source/changelog.rst

@@ -220,11 +220,12 @@ Release Date: Not Released
 	 -  Added method ``reset_validation()`` which resets internal validation variables in case of multiple validation routines.
 	 -  Added support for setting error delimiters in the config file via ``$config['error_prefix']`` and ``$config['error_suffix']``.
 	 -  ``_execute()`` now considers input data to be invalid if a specified rule is not found.
-	 -  Removed method ``is_numeric()`` as it exists as a native PHP function and ``_execute()`` will find and use that (the *is_numeric* rule itself is deprecated since 1.6.1).
+	 -  Removed method ``is_numeric()`` as it exists as a native PHP function and ``_execute()`` will find and use that (the **is_numeric** rule itself is deprecated since 1.6.1).
 	 -  Native PHP functions used as rules can now accept an additional parameter, other than the data itself.
 	 -  Updated ``set_rules()`` to accept an array of rules as well as a string.
 	 -  Fields that have empty rules set no longer run through validation (and therefore are not considered erroneous).
-	 -  Added rule *differs* to check if the value of a field differs from the value of another field.
+	 -  Added rule **differs* to check if the value of a field differs from the value of another field.
+	 -  Added rule **valid_url**.
    -  Added support for setting :doc:`Table <libraries/table>` class defaults in a config file.
    -  :doc:`Caching Library <libraries/caching>` changes include:
 	 -  Added Wincache driver.

user_guide_src/source/libraries/form_validation.rst

@@ -894,6 +894,7 @@ Rule                      Parameter  Description
                                      0, 1, 2, 3, etc.
 **is_natural_no_zero**    No         Returns FALSE if the form element contains anything other than a natural
                                      number, but not zero: 1, 2, 3, etc.
+**valid_url**             No         Returns FALSE if the form element does not contain a valid URL.
 **valid_email**           No         Returns FALSE if the form element does not contain a valid email address.
 **valid_emails**          No         Returns FALSE if any value provided in a comma separated list is not a valid email.
 **valid_ip**              No         Returns FALSE if the supplied IP is not valid.