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/**
* TfishFilter class file.
*
* @copyright Simon Wilkinson 2013-2017 (https://tuskfish.biz)
* @license https://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html GNU General Public License (GPL) V2
* @author Simon Wilkinson <[email protected]>
* @version Release: 1.0
* @since 1.0
* @package security
*/
// Enable strict type declaration.
declare(strict_types=1);
if (!defined("TFISH_ROOT_PATH")) die("TFISH_ERROR_ROOT_PATH_NOT_DEFINED");
/**
* Provides methods to validate different data types and to conduct range checks.
*
* WARNING: The methods in this class validate TYPE COMPLIANCE ONLY. They DO NOT PROVIDE DATABASE
* SAFETY in their own right. Use them in conjunction with prepared statements and bound values to
* mitigate SQL injection.
*
* 1. Pass ALL STRING type data through the trimString() function first to check for UTF-8 encoding
* and basic whitespace & control character removal. Note that this function always returns a string,
* so DO NOT USE IT ON NON-STRINGS.
*
* 2. Use the relevant type and pattern-specific methods to validate that other data types meet your
* expectations.
*
* @copyright Simon Wilkinson 2013-2017 (https://tuskfish.biz)
* @license https://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html GNU General Public License (GPL) V2
* @author Simon Wilkinson <[email protected]>
* @version Release: 1.0
* @since 1.0
* @package security
*/
class TfishFilter
{
/**
* Escape data for display to mitigate XSS attacks.
*
* Casts to string and applies htmlentities to text fields destined for output / display to
* limit XSS attacks. Encoding of quotes and use of UTF-8 character set is hardcoded in.
*
* @param mixed $output Unescaped string intended for display.
* @return string Escaped output string safe for display.
*/
public static function escape($output)
{
$output = (string) $output;
if (isset($output)) {
return htmlspecialchars($output, ENT_NOQUOTES, 'UTF-8', false);
} else {
return '';
}
}
/**
* URL-encode and escape a query string for use in a URL.
*
* Trims, checks for UTF-8 compliance, rawurlencodes and then escapes with htmlspecialchars().
* If you wish to use the data on a landing page you must decode it with
* htmlspecialchars_decode() followed by rawurldecode() in that order. But really, if you are
* using any characters that need to be encoded in the first place you should probably just
* stop.
*
* @param string $url Unescaped input URL.
* @return string Encoded and escaped URL.
*/
public static function encodeEscapeUrl(string $url)
{
$url = self::trimString($url); // Trim control characters, verify UTF-8 character set.
$url = rawurlencode($url); // Encode characters to make them URL safe.
$clean_url = self::escape($url); // Encode entities with htmlspecialchars()
return $clean_url;
}
/**
* Validate (and to some extent, "sanitise") HTML input to conform with whitelisted tags.
*
* Applies HTMLPurifier to validate and sanitise HTML input. The precise operation can be
* modified by altering the configuration of HTMLPurifier. Default options are to mandate
* UTF-8 encoding and to enable HTML5-style IDs (anchor targets).
*
* @param string $dirty_html Unvalidated HTML input.
* @param array $config_options HTMLPurifier configuration options (see HTMLPurifier documentation).
* @return string Validated HTML content.
*/
public static function filterHtml(string $dirty_html, array $config_options = array())
{
if (self::isUtf8($dirty_html) && class_exists('HTMLPurifier')) {
// Set default configuration options.
$config = HTMLPurifier_Config::createDefault();
$config->set('Core.Encoding', 'UTF-8');
$config->set('Attr.EnableID', true);
$config->set('Attr.ID.HTML5', true);
// Set optional configuration options.
if ($config_options) {
foreach ($config_options as $key => $value) {
$config->set($key, $value);
}
}
$html_purifier = new HTMLPurifier($config);
$clean_html = (string) $html_purifier->purify($dirty_html);
return $clean_html;
} else {
return false;
}
}
/**
* Check if a file path contains traversals (including encoded traversals) or null bytes.
*
* Directory traversals are not permitted in Tuskfish method parameters. If a path is found to
* contain a traversal it is presumed to be an attack. Encoded traversals are a clear sign of
* attempted abuse.
*
* In general untrusted data should never be used to construct a file path. This method exists
* as a second line safety measure.
*
* @see https://www.owasp.org/index.php/Path_Traversal.
*
* @param string $path
* @return boolean True if a traversal or null byte is found, otherwise false.
*/
public static function hasTraversalorNullByte(string $path)
{
// List of traversals and null byte encodings.
$traversals = array(
"../",
"..\\",
"%2e%2e%2f", // Represents ../
"%2e%2e/", // Represents ../
"..%2f", // Represents ../
"%2e%2e%5c", // Represents ..\
"%2e%2e", // Represents ..\
"..%5c", // Represents ..\
"%252e%252e%255c", // Represents ..\
"..%255c", // Represents ..\
"..%c0%af", // Represents ../ (URL encoding)
"..%c1%9c", // Represents ..\
"%00", // URL-encoded null byte filename terminator.
"\0", // C-style null byte (PHP functions are written in C).
"0x00" // Hex-encoded null byte.
);
// Search the path for traversals.
foreach ($traversals as $traverse) {
if (mb_strripos($path, $traverse, 0, "utf-8")) {
return true;
}
}
// No traversals found.
return false;
}
/**
* Check that a string is comprised solely of alphabetical characters.
*
* Tolerates vanilla ASCII only. Accented regional characters are rejected. This method is
* designed to be used to check database identifiers or object property names.
*
* @param string $alpha Input to be tested.
* @return bool True if valid alphabetical string, false otherwise.
*/
public static function isAlpha(string $alpha)
{
if (mb_strlen($alpha, 'UTF-8') > 0) {
return preg_match('/[^a-z]/i', $alpha) ? false : true;
} else {
return false;
}
}
/**
* Check that a string is comprised solely of alphanumeric characters.
*
* Accented regional characters are rejected. This method is designed to be used to check
* database identifiers or object property names.
*
* @param string $alnum Input to be tested.
* @return bool True if valid alphanumerical string, false otherwise.
*/
public static function isAlnum(string $alnum)
{
if (mb_strlen($alnum, 'UTF-8') > 0) {
return preg_match('/[^a-z0-9]/i', $alnum) ? false : true;
} else {
return false;
}
}
/**
* Check that a string is comprised solely of alphanumeric characters and underscores.
*
* Accented regional characters are rejected. This method is designed to be used to check
* database identifiers or object property names.
*
* @param string $alnumUnderscore Input to be tested.
* @return bool True if valid alphanumerical or underscore string, false otherwise.
*/
public static function isAlnumUnderscore(string $alnumUnderscore)
{
if (mb_strlen($alnumUnderscore, 'UTF-8') > 0) {
return preg_match('/[^a-z0-9_]/i', $alnumUnderscore) ? false : true;
} else {
return false;
}
}
/**
* Validate boolean input.
*
* Be careful with the return value; this method simply determines if a value is boolean or
* not; it does not return the actual value of the parameter.
*
* @param mixed $bool Input to be tested.
* @return bool True if a valid boolean value, false otherwise.
*/
public static function isBool($bool)
{
$result = filter_var($bool, FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE);
if (is_null($result)) {
return false;
} else {
return true;
}
}
/**
* Check that a string is comprised solely of digits.
*
* @param string $digit Input to be tested.
* @return bool True if valid digit string, false otherwise.
*/
public static function isDigit(string $digit)
{
if (mb_strlen($digit, 'UTF-8') > 0) {
return preg_match('/[^0-9]/', $digit) ? false : true;
} else {
return false;
}
}
/**
* Check if an email address is valid.
*
* Note that single quotes ' are a valid character in email addresses, so the output of this
* filter does NOT indicate that the value is database safe.
*
* @param string $email Input to be tested.
* @return boolean True if valid email address, otherwise false.
*/
public static function isEmail(string $email)
{
if (mb_strlen($email, 'UTF-8') > 2) {
return filter_var($email, FILTER_VALIDATE_EMAIL);
} else {
return false;
}
}
/**
* Validate float (decimal point allowed).
*
* Note that is_float() allows exponents.
*
* @param mixed $float Input to be tested.
* @return boolean True if valid float, otherwise false.
*/
public static function isFloat($float)
{
return is_float($float);
}
/**
* Validate integer, optionally include range check.
*
* @param mixed $int Input to be tested.
* @param int $min Minimum acceptable value.
* @param int $max Maximum acceptable value.
* @return bool True if valid int and within optional range check, false otherwise.
*/
public static function isInt($int, int $min = null, int $max = null)
{
$clean_int = is_int($int) ? (int) $int : null;
$clean_min = is_int($min) ? (int) $min : null;
$clean_max = is_int($max) ? (int) $max : null;
// Range check on minimum and maximum value.
if (is_int($clean_int) && is_int($clean_min) && is_int($clean_max)) {
return ($clean_int >= $clean_min) && ($clean_int <= $clean_max) ? true : false;
}
// Range check on minimum value.
if (is_int($clean_int) && is_int($clean_min) && !isset($clean_max)) {
return $clean_int >= $clean_min ? true : false;
}
// Range check on maximum value.
if (is_int($clean_int) && !isset($clean_min) && is_int($clean_max)) {
return $clean_int <= $clean_max ? true : false;
}
// Simple use case, no range check.
if (is_int($clean_int) && !isset($clean_min) && !isset($clean_max)) {
return true;
} else {
return false;
}
}
/**
* Validates IP addresses. Accepts private (but not reserved) ranges. Optionally IPV6.
*
* @param string $ip Input to be tested.
* @param int $version IP address version ('4' or '6').
* @return bool True if valid IP address, false otherwise.
*/
public static function isIp(string $ip, int $version = null)
{
if (isset($version) && $version === 6) {
if (!filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6
| FILTER_FLAG_NO_RES_RANGE) === false) {
return true;
} else {
return false;
}
} else {
if (!filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4
| FILTER_FLAG_NO_RES_RANGE) === false) {
return true;
} else {
return false;
}
}
}
/**
* Check if the character encoding of text is UTF-8.
*
* All strings received from external sources must be passed through this function, particularly
* prior to storage in the database.
*
* @param string $dirty_string Input string to check.
* @return bool True if string is UTF-8 encoded otherwise false.
*/
public static function isUtf8(string $dirty_string)
{
return mb_check_encoding($dirty_string, 'UTF-8');
}
/**
* Validate URL.
*
* Only accepts http:// and https:// protocol and ASCII characters. Other protocols
* and internationalised domain names will fail validation due to limitation of filter.
*
* @param string $url Input to be tested.
* @return bool True if valid URL otherwise false.
*/
public static function isUrl(string $url)
{
if (filter_var($url, FILTER_VALIDATE_URL, FILTER_FLAG_SCHEME_REQUIRED
| FILTER_FLAG_HOST_REQUIRED)) {
if (mb_substr($url, 0, 7, 'UTF-8') === 'http://'
|| mb_substr($url, 0, 8, 'UTF-8') === 'https://') {
return true;
}
}
return false;
}
/**
* Test if input is an array.
*
* @param mixed $array Input to be tested.
* @return bool True if valid array otherwise false.
*/
public static function isArray($array)
{
return is_array($array);
}
/**
* Test if input is an object.
*
* @param mixed $object Input to be tested.
* @return bool True if valid object otherwise false.
*/
public static function isObject($object)
{
return is_object($object);
}
/**
* Tests if the input is null (ie set but without an assigned value) or not.
*
* @param mixed $null Input to be tested.
* @return bool True if input is null otherwise false.
*/
public static function isNull($null)
{
return is_null($null);
}
/**
* Tests if input is a resource.
*
* @param mixed $resource Input to be tested.
* @return bool True if valid resource otherwise false.
*/
public static function isResource($resource)
{
return is_resource($resource);
}
/**
* Cast to string, check UTF-8 encoding and strip trailing whitespace and control characters.
*
* Removes trailing whitespace and control characters (ASCII <= 32), checks for UTF-8 character
* set and casts input to a string. Note that the data returned by this function still
* requires escaping at the point of use; it is not database or XSS safe.
*
* As the input is cast to a string do NOT apply this function to non-string types (int, float,
* bool, object, resource, null, array, etc).
*
* @param mixed $dirty_string Input to be trimmed.
* @return string Trimmed and UTF-8 validated string.
*/
public static function trimString($dirty_string)
{
$dirty_string = (string) $dirty_string;
if (self::isUtf8($dirty_string)) {
// Trims all control characters plus space (ASCII / UTF-8 points 0-32 inclusive).
return trim($dirty_string, "\x00..\x20");
} else {
return false;
}
}
}