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<?php
/**
* BigMath: A math library wrapper that abstracts out the underlying
* long integer library.
*
* PHP versions 4 and 5
*
* LICENSE: See the COPYING file included in this distribution.
*
* @access private
* @package OpenID
* @author JanRain, Inc. <openid@janrain.com>
* @copyright 2005-2008 Janrain, Inc.
* @license http://www.apache.org/licenses/LICENSE-2.0 Apache
*/
/**
* Needed for random number generation
*/
require_once 'Auth/OpenID/CryptUtil.php';
/**
* Need Auth_OpenID::bytes().
*/
require_once 'Auth/OpenID.php';
/**
* The superclass of all big-integer math implementations
* @access private
* @package OpenID
*/
class Auth_OpenID_MathLibrary {
/**
* Given a long integer, returns the number converted to a binary
* string. This function accepts long integer values of arbitrary
* magnitude and uses the local large-number math library when
* available.
*
* @param integer $long The long number (can be a normal PHP
* integer or a number created by one of the available long number
* libraries)
* @return string $binary The binary version of $long
*/
function longToBinary($long)
{
$cmp = $this->cmp($long, 0);
if ($cmp < 0) {
$msg = __FUNCTION__ . " takes only positive integers.";
trigger_error($msg, E_USER_ERROR);
return null;
}
if ($cmp == 0) {
return "\x00";
}
$bytes = array();
while ($this->cmp($long, 0) > 0) {
array_unshift($bytes, $this->mod($long, 256));
$long = $this->div($long, pow(2, 8));
}
if ($bytes && ($bytes[0] > 127)) {
array_unshift($bytes, 0);
}
$string = '';
foreach ($bytes as $byte) {
$string .= pack('C', $byte);
}
return $string;
}
/**
* Given a binary string, returns the binary string converted to a
* long number.
*
* @param string $binary The binary version of a long number,
* probably as a result of calling longToBinary
* @return integer $long The long number equivalent of the binary
* string $str
*/
function binaryToLong($str)
{
if ($str === null) {
return null;
}
// Use array_merge to return a zero-indexed array instead of a
// one-indexed array.
$bytes = array_merge(unpack('C*', $str));
$n = $this->init(0);
if ($bytes && ($bytes[0] > 127)) {
trigger_error("bytesToNum works only for positive integers.",
E_USER_WARNING);
return null;
}
foreach ($bytes as $byte) {
$n = $this->mul($n, pow(2, 8));
$n = $this->add($n, $byte);
}
return $n;
}
function base64ToLong($str)
{
$b64 = base64_decode($str);
if ($b64 === false) {
return false;
}
return $this->binaryToLong($b64);
}
function longToBase64($str)
{
return base64_encode($this->longToBinary($str));
}
/**
* Returns a random number in the specified range. This function
* accepts $start, $stop, and $step values of arbitrary magnitude
* and will utilize the local large-number math library when
* available.
*
* @param integer $start The start of the range, or the minimum
* random number to return
* @param integer $stop The end of the range, or the maximum
* random number to return
* @param integer $step The step size, such that $result - ($step
* * N) = $start for some N
* @return integer $result The resulting randomly-generated number
*/
function rand($stop)
{
static $duplicate_cache = array();
// Used as the key for the duplicate cache
$rbytes = $this->longToBinary($stop);
if (array_key_exists($rbytes, $duplicate_cache)) {
list($duplicate, $nbytes) = $duplicate_cache[$rbytes];
} else {
if ($rbytes[0] == "\x00") {
$nbytes = Auth_OpenID::bytes($rbytes) - 1;
} else {
$nbytes = Auth_OpenID::bytes($rbytes);
}
$mxrand = $this->pow(256, $nbytes);
// If we get a number less than this, then it is in the
// duplicated range.
$duplicate = $this->mod($mxrand, $stop);
if (count($duplicate_cache) > 10) {
$duplicate_cache = array();
}
$duplicate_cache[$rbytes] = array($duplicate, $nbytes);
}
do {
$bytes = "\x00" . Auth_OpenID_CryptUtil::getBytes($nbytes);
$n = $this->binaryToLong($bytes);
// Keep looping if this value is in the low duplicated range
} while ($this->cmp($n, $duplicate) < 0);
return $this->mod($n, $stop);
}
}
/**
* Exposes BCmath math library functionality.
*
* {@link Auth_OpenID_BcMathWrapper} wraps the functionality provided
* by the BCMath extension.
*
* @access private
* @package OpenID
*/
class Auth_OpenID_BcMathWrapper extends Auth_OpenID_MathLibrary{
var $type = 'bcmath';
function add($x, $y)
{
return bcadd($x, $y);
}
function sub($x, $y)
{
return bcsub($x, $y);
}
function pow($base, $exponent)
{
return bcpow($base, $exponent);
}
function cmp($x, $y)
{
return bccomp($x, $y);
}
function init($number, $base = 10)
{
return $number;
}
function mod($base, $modulus)
{
return bcmod($base, $modulus);
}
function mul($x, $y)
{
return bcmul($x, $y);
}
function div($x, $y)
{
return bcdiv($x, $y);
}
/**
* Same as bcpowmod when bcpowmod is missing
*
* @access private
*/
function _powmod($base, $exponent, $modulus)
{
$square = $this->mod($base, $modulus);
$result = 1;
while($this->cmp($exponent, 0) > 0) {
if ($this->mod($exponent, 2)) {
$result = $this->mod($this->mul($result, $square), $modulus);
}
$square = $this->mod($this->mul($square, $square), $modulus);
$exponent = $this->div($exponent, 2);
}
return $result;
}
function powmod($base, $exponent, $modulus)
{
if (function_exists('bcpowmod')) {
return bcpowmod($base, $exponent, $modulus);
} else {
return $this->_powmod($base, $exponent, $modulus);
}
}
function toString($num)
{
return $num;
}
}
/**
* Exposes GMP math library functionality.
*
* {@link Auth_OpenID_GmpMathWrapper} wraps the functionality provided
* by the GMP extension.
*
* @access private
* @package OpenID
*/
class Auth_OpenID_GmpMathWrapper extends Auth_OpenID_MathLibrary{
var $type = 'gmp';
function add($x, $y)
{
return gmp_add($x, $y);
}
function sub($x, $y)
{
return gmp_sub($x, $y);
}
function pow($base, $exponent)
{
return gmp_pow($base, $exponent);
}
function cmp($x, $y)
{
return gmp_cmp($x, $y);
}
function init($number, $base = 10)
{
return gmp_init($number, $base);
}
function mod($base, $modulus)
{
return gmp_mod($base, $modulus);
}
function mul($x, $y)
{
return gmp_mul($x, $y);
}
function div($x, $y)
{
return gmp_div_q($x, $y);
}
function powmod($base, $exponent, $modulus)
{
return gmp_powm($base, $exponent, $modulus);
}
function toString($num)
{
return gmp_strval($num);
}
}
/**
* Define the supported extensions. An extension array has keys
* 'modules', 'extension', and 'class'. 'modules' is an array of PHP
* module names which the loading code will attempt to load. These
* values will be suffixed with a library file extension (e.g. ".so").
* 'extension' is the name of a PHP extension which will be tested
* before 'modules' are loaded. 'class' is the string name of a
* {@link Auth_OpenID_MathWrapper} subclass which should be
* instantiated if a given extension is present.
*
* You can define new math library implementations and add them to
* this array.
*/
function Auth_OpenID_math_extensions()
{
$result = array();
if (!defined('Auth_OpenID_BUGGY_GMP')) {
$result[] =
array('modules' => array('gmp', 'php_gmp'),
'extension' => 'gmp',
'class' => 'Auth_OpenID_GmpMathWrapper');
}
$result[] = array('modules' => array('bcmath', 'php_bcmath'),
'extension' => 'bcmath',
'class' => 'Auth_OpenID_BcMathWrapper');
return $result;
}
/**
* Detect which (if any) math library is available
*/
function Auth_OpenID_detectMathLibrary($exts)
{
$loaded = false;
foreach ($exts as $extension) {
if (extension_loaded($extension['extension'])) {
return $extension;
}
}
return false;
}
/**
* {@link Auth_OpenID_getMathLib} checks for the presence of long
* number extension modules and returns an instance of
* {@link Auth_OpenID_MathWrapper} which exposes the module's
* functionality.
*
* Checks for the existence of an extension module described by the
* result of {@link Auth_OpenID_math_extensions()} and returns an
* instance of a wrapper for that extension module. If no extension
* module is found, an instance of {@link Auth_OpenID_MathWrapper} is
* returned, which wraps the native PHP integer implementation. The
* proper calling convention for this method is $lib =
* Auth_OpenID_getMathLib().
*
* This function checks for the existence of specific long number
* implementations in the following order: GMP followed by BCmath.
*
* @return Auth_OpenID_MathWrapper $instance An instance of
* {@link Auth_OpenID_MathWrapper} or one of its subclasses
*
* @package OpenID
*/
function Auth_OpenID_getMathLib()
{
// The instance of Auth_OpenID_MathWrapper that we choose to
// supply will be stored here, so that subseqent calls to this
// method will return a reference to the same object.
static $lib = null;
if (isset($lib)) {
return $lib;
}
if (Auth_OpenID_noMathSupport()) {
$null = null;
return $null;
}
// If this method has not been called before, look at
// Auth_OpenID_math_extensions and try to find an extension that
// works.
$ext = Auth_OpenID_detectMathLibrary(Auth_OpenID_math_extensions());
if ($ext === false) {
$tried = array();
foreach (Auth_OpenID_math_extensions() as $extinfo) {
$tried[] = $extinfo['extension'];
}
$triedstr = implode(", ", $tried);
Auth_OpenID_setNoMathSupport();
$result = null;
return $result;
}
// Instantiate a new wrapper
$class = $ext['class'];
$lib = new $class();
return $lib;
}
function Auth_OpenID_setNoMathSupport()
{
if (!defined('Auth_OpenID_NO_MATH_SUPPORT')) {
define('Auth_OpenID_NO_MATH_SUPPORT', true);
}
}
function Auth_OpenID_noMathSupport()
{
return defined('Auth_OpenID_NO_MATH_SUPPORT');
}
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