<?php
/**
* php-csrf v1.0.4
*
* Single PHP library file for protection over Cross-Site Request Forgery
* Easily generate and manage CSRF tokens in groups.
*
*
* MIT License
*
* Copyright (c) 2023 Grammatopoulos Athanasios-Vasileios
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*
*/
/**
* Usage:
* // Load or Start a new list of tokens
* $csrf_tokens = new CSRF(
* <modifier for the session variable and the form input name>,
* <default time before the token expire, in seconds>
* );
* // Generate an input for a form with a token
* // Tokens on the list are binded on a group so that
* // they can only be matched on that group
* // You can use as a group name the form name
* echo $csrf_tokens->input(<name of the group>);
*/
class CSRF {
private $name;
private $hashes;
private $hashTime2Live;
private $hashSize;
private $inputName;
/**
* Initialize a CSRF instance
* @param string $session_name Session name
* @param string $input_name Form name
* @param integer $hashTime2Live Default seconds hash before expiration
* @param integer $hashSize Default hash size in chars
*/
function __construct ($session_name='csrf-lib', $input_name='key-awesome', $hashTime2Live=0, $hashSize=64) {
// Session mods
$this->name = $session_name;
// Form input name
$this->inputName = $input_name;
// Default time before expire for hashes
$this->hashTime2Live = $hashTime2Live;
// Default hash size
$this->hashSize = $hashSize;
// Load hash list
$this->_load();
}
/**
* Generate a CSRF_Hash
* @param string $context Name of the form
* @param integer $time2Live Seconds before expiration
* @param integer $max_hashes Clear old context hashes if more than this number
* @return CSRF_Hash
*/
private function generateHash ($context='', $time2Live=-1, $max_hashes=5) {
// If no time2live (or invalid) use default
if ($time2Live < 0) $time2Live = $this->hashTime2Live;
// Generate new hash
$hash = new CSRF_Hash($context, $time2Live, $this->hashSize);
// Save it
array_push($this->hashes, $hash);
if ($this->clearHashes($context, $max_hashes) === 0) {
$this->_save();
}
// Return hash info
return $hash;
}
/**
* Get the hashes of a context
* @param string $context the group to clean
* @param integer $max_hashes max hashes to get
* @return array array of hashes as strings
*/
public function getHashes ($context='', $max_hashes=-1) {
$len = count($this->hashes);
$hashes = array();
// Check in the hash list
for ($i = $len - 1; $i >= 0 && $len > 0; $i--) {
if ($this->hashes[$i]->inContext($context)) {
array_push($hashes, $this->hashes[$i]->get());
$len--;
}
}
return $hashes;
}
/**
* Clear the hashes of a context
* @param string $context the group to clean
* @param integer $max_hashes ignore first x hashes
* @return integer number of deleted hashes
*/
public function clearHashes ($context='', $max_hashes=0) {
$ignore = $max_hashes;
$deleted = 0;
// Check in the hash list
for ($i = count($this->hashes) - 1; $i >= 0; $i--) {
if ($this->hashes[$i]->inContext($context) && $ignore-- <= 0) {
array_splice($this->hashes, $i, 1);
$deleted++;
}
}
if ($deleted > 0) {
$this->_save();
}
return $deleted;
}
/**
* Generate an input html element
* @param string $context Name of the form
* @param integer $time2Live Seconds before expire
* @param integer $max_hashes Clear old context hashes if more than this number
* @return integer html input element code as a string
*/
public function input ($context='', $time2Live=-1, $max_hashes=5) {
// Generate hash
$hash = $this->generateHash ($context, $time2Live, $max_hashes);
// Generate html input string
return '<input type="hidden" name="' . htmlspecialchars($this->inputName) . '" id="' . htmlspecialchars($this->inputName) . '" value="' . htmlspecialchars($hash->get()) . '"/>';
}
/**
* Generate a script html element with the hash variable
* @param string $context Name of the form
* @param string $name The name for the variable
* @param integer $time2Live Seconds before expire
* @param integer $max_hashes Clear old context hashes if more than this number
* @return integer html script element code as a string
*/
public function script ($context='', $name='', $declaration='var', $time2Live=-1, $max_hashes=5) {
// Generate hash
$hash = $this->generateHash ($context, $time2Live, $max_hashes);
// Variable name
if (strlen($name) === 0) {
$name = $this->inputName;
}
// Generate html input string
return '<script type="text/javascript">' . $declaration . ' ' . $name . ' = ' . json_encode($hash->get()) . ';</script>';
}
/**
* Generate a javascript variable with the hash
* @param string $context Name of the form
* @param string $name The name for the variable
* @param integer $time2Live Seconds before expire
* @param integer $max_hashes Clear old context hashes if more than this number
* @return integer html script element code as a string
*/
public function javascript ($context='', $name='', $declaration='var', $time2Live=-1, $max_hashes=5) {
// Generate hash
$hash = $this->generateHash ($context, $time2Live, $max_hashes);
// Variable name
if (strlen($name) === 0) {
$name = $this->inputName;
}
// Generate html input string
return $declaration . ' ' . $name . ' = ' . json_encode($hash->get()) . ';';
}
/**
* Generate a string hash
* @param string $context Name of the form
* @param integer $time2Live Seconds before expire
* @param integer $max_hashes Clear old context hashes if more than this number
* @return integer hash as a string
*/
public function string ($context='', $time2Live=-1, $max_hashes=5) {
// Generate hash
$hash = $this->generateHash ($context, $time2Live, $max_hashes);
// Generate html input string
return $hash->get();
}
/**
* Validate by context
* @param string $context Name of the form
* @return boolean Valid or not
*/
public function validate ($context='', $hash = null) {
// If hash was not given, find hash
if (is_null($hash)) {
if (isset($_POST[$this->inputName])) {
$hash = $_POST[$this->inputName];
}
else if (isset($_GET[$this->inputName])) {
$hash = $_GET[$this->inputName];
}
else {
return false;
}
}
// Check in the hash list
for ($i = count($this->hashes) - 1; $i >= 0; $i--) {
if ($this->hashes[$i]->verify($hash, $context)) {
array_splice($this->hashes, $i, 1);
return true;
}
}
return false;
}
/**
* Load hash list
*/
private function _load () {
$this->hashes = array();
// If there are hashes on the session
if (isset($_SESSION[$this->name])) {
// Load session hashes
$session_hashes = unserialize($_SESSION[$this->name]);
// Ignore expired
for ($i = count($session_hashes) - 1; $i >= 0; $i--) {
// If an expired found, the rest will be expired
if ($session_hashes[$i]->hasExpire()) {
break;
}
array_unshift($this->hashes, $session_hashes[$i]);
}
if (count($this->hashes) != count($session_hashes)) {
$this->_save();
}
}
}
/**
* Save hash list
*/
private function _save () {
$_SESSION[$this->name] = serialize($this->hashes);
}
}
class CSRF_Hash {
private $hash;
private $context;
private $expire;
/**
* [__construct description]
* @param string $context [description]
* @param integer $time2Live Number of seconds before expiration
*/
function __construct($context, $time2Live=0, $hashSize=64) {
// Save context name
$this->context = $context;
// Generate hash
$this->hash = $this->_generateHash($hashSize);
// Set expiration time
if ($time2Live > 0) {
$this->expire = time() + $time2Live;
}
else {
$this->expire = 0;
}
}
/**
* The hash function to use
* @param int $n Size in bytes
* @return string The generated hash
*/
private function _generateHash ($n) {
return bin2hex(openssl_random_pseudo_bytes($n/2));
}
/**
* Check if hash has expired
* @return boolean
*/
public function hasExpire () {
if ($this->expire === 0 || $this->expire > time()) {
return false;
}
return true;
}
/**
* Verify hash
* @return boolean
*/
public function verify ($hash, $context='') {
if (strcmp($context, $this->context) === 0 && !$this->hasExpire() && hash_equals($hash, $this->hash)) {
return true;
}
return false;
}
/**
* Check Context
* @return boolean
*/
public function inContext ($context='') {
if (strcmp($context, $this->context) === 0) {
return true;
}
return false;
}
/**
* Get hash
* @return string
*/
public function get () {
return $this->hash;
}
}