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<?php
// +-----------------------------------------------------------------------+
// | Copyright (c) 2002-2003 Richard Heyes |
// | All rights reserved. |
// | |
// | Redistribution and use in source and binary forms, with or without |
// | modification, are permitted provided that the following conditions |
// | are met: |
// | |
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// | notice, this list of conditions and the following disclaimer. |
// | o Redistributions in binary form must reproduce the above copyright |
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// | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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// +-----------------------------------------------------------------------+
// | Author: Richard Heyes <richard@php.net> |
// +-----------------------------------------------------------------------+
//
// $Id$
/**
* Implmentation of DIGEST-MD5 SASL mechanism
*
* @author Richard Heyes <richard@php.net>
* @access public
* @version 1.0
* @package Auth_SASL
*/
require_once('Auth/SASL/Common.php');
class Auth_SASL_DigestMD5 extends Auth_SASL_Common
{
/**
* Provides the (main) client response for DIGEST-MD5
* requires a few extra parameters than the other
* mechanisms, which are unavoidable.
*
* @param string $authcid Authentication id (username)
* @param string $pass Password
* @param string $challenge The digest challenge sent by the server
* @param string $hostname The hostname of the machine you're connecting to
* @param string $service The servicename (eg. imap, pop, acap etc)
* @param string $authzid Authorization id (username to proxy as)
* @return string The digest response (NOT base64 encoded)
* @access public
*/
function getResponse($authcid, $pass, $challenge, $hostname, $service, $authzid = '')
{
$challenge = $this->_parseChallenge($challenge);
$authzid_string = '';
if ($authzid != '') {
$authzid_string = ',authzid="' . $authzid . '"';
}
if (!empty($challenge)) {
$cnonce = $this->_getCnonce();
$digest_uri = sprintf('%s/%s', $service, $hostname);
$response_value = $this->_getResponseValue($authcid, $pass, $challenge['realm'], $challenge['nonce'], $cnonce, $digest_uri, $authzid);
if ($challenge['realm']) {
return sprintf('username="%s",realm="%s"' . $authzid_string .
',nonce="%s",cnonce="%s",nc=00000001,qop=auth,digest-uri="%s",response=%s,maxbuf=%d', $authcid, $challenge['realm'], $challenge['nonce'], $cnonce, $digest_uri, $response_value, $challenge['maxbuf']);
} else {
return sprintf('username="%s"' . $authzid_string . ',nonce="%s",cnonce="%s",nc=00000001,qop=auth,digest-uri="%s",response=%s,maxbuf=%d', $authcid, $challenge['nonce'], $cnonce, $digest_uri, $response_value, $challenge['maxbuf']);
}
} else {
return PEAR::raiseError('Invalid digest challenge');
}
}
/**
* Parses and verifies the digest challenge*
*
* @param string $challenge The digest challenge
* @return array The parsed challenge as an assoc
* array in the form "directive => value".
* @access private
*/
function _parseChallenge($challenge)
{
$tokens = array();
while (preg_match('/^([a-z-]+)=("[^"]+(?<!\\\)"|[^,]+)/i', $challenge, $matches)) {
// Ignore these as per rfc2831
if ($matches[1] == 'opaque' OR $matches[1] == 'domain') {
$challenge = substr($challenge, strlen($matches[0]) + 1);
continue;
}
// Allowed multiple "realm" and "auth-param"
if (!empty($tokens[$matches[1]]) AND ($matches[1] == 'realm' OR $matches[1] == 'auth-param')) {
if (is_array($tokens[$matches[1]])) {
$tokens[$matches[1]][] = preg_replace('/^"(.*)"$/', '\\1', $matches[2]);
} else {
$tokens[$matches[1]] = array($tokens[$matches[1]], preg_replace('/^"(.*)"$/', '\\1', $matches[2]));
}
// Any other multiple instance = failure
} elseif (!empty($tokens[$matches[1]])) {
$tokens = array();
break;
} else {
$tokens[$matches[1]] = preg_replace('/^"(.*)"$/', '\\1', $matches[2]);
}
// Remove the just parsed directive from the challenge
$challenge = substr($challenge, strlen($matches[0]) + 1);
}
/**
* Defaults and required directives
*/
// Realm
if (empty($tokens['realm'])) {
$tokens['realm'] = "";
}
// Maxbuf
if (empty($tokens['maxbuf'])) {
$tokens['maxbuf'] = 65536;
}
// Required: nonce, algorithm
if (empty($tokens['nonce']) OR empty($tokens['algorithm'])) {
return array();
}
return $tokens;
}
/**
* Creates the response= part of the digest response
*
* @param string $authcid Authentication id (username)
* @param string $pass Password
* @param string $realm Realm as provided by the server
* @param string $nonce Nonce as provided by the server
* @param string $cnonce Client nonce
* @param string $digest_uri The digest-uri= value part of the response
* @param string $authzid Authorization id
* @return string The response= part of the digest response
* @access private
*/
function _getResponseValue($authcid, $pass, $realm, $nonce, $cnonce, $digest_uri, $authzid = '')
{
if ($authzid == '') {
$A1 = sprintf('%s:%s:%s', pack('H32', md5(sprintf('%s:%s:%s', $authcid, $realm, $pass))), $nonce, $cnonce);
} else {
$A1 = sprintf('%s:%s:%s:%s', pack('H32', md5(sprintf('%s:%s:%s', $authcid, $realm, $pass))), $nonce, $cnonce, $authzid);
}
$A2 = 'AUTHENTICATE:' . $digest_uri;
return md5(sprintf('%s:%s:00000001:%s:auth:%s', md5($A1), $nonce, $cnonce, md5($A2)));
}
/**
* Creates the client nonce for the response
*
* @return string The cnonce value
* @access private
*/
function _getCnonce()
{
if (@file_exists('/dev/urandom') && $fd = @fopen('/dev/urandom', 'r')) {
return base64_encode(fread($fd, 32));
} elseif (@file_exists('/dev/random') && $fd = @fopen('/dev/random', 'r')) {
return base64_encode(fread($fd, 32));
} else {
$str = '';
for ($i=0; $i<32; $i++) {
$str .= chr(mt_rand(0, 255));
}
return base64_encode($str);
}
}
}
?>