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<?php
/**
* auth.php
*
* Contains functions used to do authentication.
*
* @copyright 1999-2010 The SquirrelMail Project Team
* @license http://opensource.org/licenses/gpl-license.php GNU Public License
* @version $Id: auth.php 13893 2010-01-25 02:47:41Z pdontthink $
* @package squirrelmail
*/
/** Put in a safety net here, in case a naughty admin didn't run conf.pl when they upgraded */
if (! isset($smtp_auth_mech)) {
$smtp_auth_mech = 'none';
}
if (! isset($imap_auth_mech)) {
$imap_auth_mech = 'login';
}
if (! isset($use_imap_tls)) {
$use_imap_tls = false;
}
if (! isset($use_smtp_tls)) {
$use_smtp_tls = false;
}
/**
* Check if user has previously logged in to the SquirrelMail session. If user
* has not logged in, execution will stop inside this function.
*
* This function optionally checks the referrer of this page request. If the
* administrator wants to impose a check that the referrer of this page request
* is another page on the same domain (otherwise, the page request is likely
* the result of a XSS or phishing attack), then they need to specify the
* acceptable referrer domain in a variable named $check_referrer in
* config/config.php (or the configuration tool) for which the value is
* usually the same as the $domain setting (for example:
* $check_referrer = 'example.com';
* However, in some cases (where proxy servers are in use, etc.), the
* acceptable referrer might be different. If $check_referrer is set to
* "###DOMAIN###", then the current value of $domain is used (useful in
* situations where $domain might change at runtime (when using the Login
* Manager plugin to host multiple domains with one SquirrelMail installation,
* for example)):
* $check_referrer = '###DOMAIN###';
* NOTE HOWEVER, that referrer checks are not foolproof - they can be spoofed
* by browsers, and some browsers intentionally don't send them, in which
* case SquirrelMail silently ignores referrer checks.
*
* @return void This function returns ONLY if user has previously logged in
* successfully (otherwise, execution terminates herein).
*/
function is_logged_in() {
// check for user login as well as referrer if needed
//
global $check_referrer, $domain;
if ($check_referrer == '###DOMAIN###') $check_referrer = $domain;
if (!empty($check_referrer)) {
$ssl_check_referrer = 'https://' . $check_referrer;
$plain_check_referrer = 'http://' . $check_referrer;
}
if (!sqgetGlobalVar('HTTP_REFERER', $referrer, SQ_SERVER)) $referrer = '';
if (sqsession_is_registered('user_is_logged_in')
&& (!$check_referrer || empty($referrer)
|| ($check_referrer && !empty($referrer)
&& (strpos(strtolower($referrer), strtolower($plain_check_referrer)) === 0
|| strpos(strtolower($referrer), strtolower($ssl_check_referrer)) === 0)))) {
return;
} else {
global $session_expired_post,
$session_expired_location, $squirrelmail_language;
// use $message to indicate what logout text the user
// will see... if 0, typical "You must be logged in"
// if 1, information that the user session was saved
// and will be resumed after (re)login, if 2, there
// seems to have been a XSS or phishing attack (bad
// referrer)
//
$message = 0;
// First we store some information in the new session to prevent
// information-loss.
$session_expired_post = $_POST;
if (defined('PAGE_NAME')) {
$session_expired_location = PAGE_NAME;
}
if (!sqsession_is_registered('session_expired_post')) {
sqsession_register($session_expired_post,'session_expired_post');
}
if (!sqsession_is_registered('session_expired_location')) {
sqsession_register($session_expired_location,'session_expired_location');
if ($session_expired_location == 'compose')
$message = 1;
}
// was bad referrer the reason we were rejected?
//
if (sqsession_is_registered('user_is_logged_in')
&& $check_referrer && !empty($referrer))
$message = 2;
session_write_close();
// signout page will deal with users who aren't logged
// in on its own; don't show error here
if (defined('PAGE_NAME') && PAGE_NAME == 'signout') {
return;
}
include_once( SM_PATH . 'functions/display_messages.php' );
set_up_language($squirrelmail_language, true);
if (!$message)
logout_error( _("You must be logged in to access this page.") );
else if ($message == 1)
logout_error( _("Your session has expired, but will be resumed after logging in again.") );
else if ($message == 2)
logout_error( _("The current page request appears to have originated from an unrecognized source.") );
exit;
}
}
/**
* Given the challenge from the server, supply the response using cram-md5 (See
* RFC 2195 for details)
*
* @param string $username User ID
* @param string $password User password supplied by User
* @param string $challenge The challenge supplied by the server
* @return string The response to be sent to the IMAP server
*
*/
function cram_md5_response ($username,$password,$challenge) {
$challenge=base64_decode($challenge);
$hash=bin2hex(hmac_md5($challenge,$password));
$response=base64_encode($username . " " . $hash) . "\r\n";
return $response;
}
/**
* Return Digest-MD5 response.
* Given the challenge from the server, calculate and return the
* response-string for digest-md5 authentication. (See RFC 2831 for more
* details)
*
* @param string $username User ID
* @param string $password User password supplied by User
* @param string $challenge The challenge supplied by the server
* @param string $service The service name, usually 'imap'; it is used to
* define the digest-uri.
* @param string $host The host name, usually the server's FQDN; it is used to
* define the digest-uri.
* @return string The response to be sent to the IMAP server
*/
function digest_md5_response ($username,$password,$challenge,$service,$host) {
$result=digest_md5_parse_challenge($challenge);
//FIXME we should check that $result contains the expected values that we use below
// verify server supports qop=auth
// $qop = explode(",",$result['qop']);
//if (!in_array("auth",$qop)) {
// rfc2831: client MUST fail if no qop methods supported
// return false;
//}
$cnonce = base64_encode(bin2hex(hmac_md5(microtime())));
$ncount = "00000001";
/* This can be auth (authentication only), auth-int (integrity protection), or
auth-conf (confidentiality protection). Right now only auth is supported.
DO NOT CHANGE THIS VALUE */
$qop_value = "auth";
$digest_uri_value = $service . '/' . $host;
// build the $response_value
//FIXME This will probably break badly if a server sends more than one realm
$string_a1 = utf8_encode($username).":";
$string_a1 .= utf8_encode($result['realm']).":";
$string_a1 .= utf8_encode($password);
$string_a1 = hmac_md5($string_a1);
$A1 = $string_a1 . ":" . $result['nonce'] . ":" . $cnonce;
$A1 = bin2hex(hmac_md5($A1));
$A2 = "AUTHENTICATE:$digest_uri_value";
// If qop is auth-int or auth-conf, A2 gets a little extra
if ($qop_value != 'auth') {
$A2 .= ':00000000000000000000000000000000';
}
$A2 = bin2hex(hmac_md5($A2));
$string_response = $result['nonce'] . ':' . $ncount . ':' . $cnonce . ':' . $qop_value;
$response_value = bin2hex(hmac_md5($A1.":".$string_response.":".$A2));
$reply = 'charset=utf-8,username="' . $username . '",realm="' . $result["realm"] . '",';
$reply .= 'nonce="' . $result['nonce'] . '",nc=' . $ncount . ',cnonce="' . $cnonce . '",';
$reply .= "digest-uri=\"$digest_uri_value\",response=$response_value";
$reply .= ',qop=' . $qop_value;
$reply = base64_encode($reply);
return $reply . "\r\n";
}
/**
* Parse Digest-MD5 challenge.
* This function parses the challenge sent during DIGEST-MD5 authentication and
* returns an array. See the RFC for details on what's in the challenge string.
*
* @param string $challenge Digest-MD5 Challenge
* @return array Digest-MD5 challenge decoded data
*/
function digest_md5_parse_challenge($challenge) {
$challenge=base64_decode($challenge);
$parsed = array();
while (!empty($challenge)) {
if ($challenge{0} == ',') { // First char is a comma, must not be 1st time through loop
$challenge=substr($challenge,1);
}
$key=explode('=',$challenge,2);
$challenge=$key[1];
$key=$key[0];
if ($challenge{0} == '"') {
// We're in a quoted value
// Drop the first quote, since we don't care about it
$challenge=substr($challenge,1);
// Now explode() to the next quote, which is the end of our value
$val=explode('"',$challenge,2);
$challenge=$val[1]; // The rest of the challenge, work on it in next iteration of loop
$value=explode(',',$val[0]);
// Now, for those quoted values that are only 1 piece..
if (sizeof($value) == 1) {
$value=$value[0]; // Convert to non-array
}
} else {
// We're in a "simple" value - explode to next comma
$val=explode(',',$challenge,2);
if (isset($val[1])) {
$challenge=$val[1];
} else {
unset($challenge);
}
$value=$val[0];
}
$parsed["$key"]=$value;
} // End of while loop
return $parsed;
}
/**
* Creates a HMAC digest that can be used for auth purposes
* See RFCs 2104, 2617, 2831
* Uses mhash() extension if available
*
* @param string $data Data to apply hash function to.
* @param string $key Optional key, which, if supplied, will be used to
* calculate data's HMAC.
* @return string HMAC Digest string
*/
function hmac_md5($data, $key='') {
if (extension_loaded('mhash')) {
if ($key== '') {
$mhash=mhash(MHASH_MD5,$data);
} else {
$mhash=mhash(MHASH_MD5,$data,$key);
}
return $mhash;
}
if (!$key) {
return pack('H*',md5($data));
}
$key = str_pad($key,64,chr(0x00));
if (strlen($key) > 64) {
$key = pack("H*",md5($key));
}
$k_ipad = $key ^ str_repeat(chr(0x36), 64) ;
$k_opad = $key ^ str_repeat(chr(0x5c), 64) ;
/* Heh, let's get recursive. */
$hmac=hmac_md5($k_opad . pack("H*",md5($k_ipad . $data)) );
return $hmac;
}
/**
* Reads and decodes stored user password information
*
* Direct access to password information is deprecated.
* @return string password in plain text
* @since 1.4.11
*/
function sqauth_read_password() {
sqgetGlobalVar('key', $key, SQ_COOKIE);
sqgetGlobalVar('onetimepad', $onetimepad,SQ_SESSION);
return OneTimePadDecrypt($key, $onetimepad);
}
/**
* Saves or updates user password information
*
* This function is used to update the password information that
* SquirrelMail stores in the existing PHP session. It does NOT
* modify the password stored in the authentication system used
* by the IMAP server.
*
* This function must be called before any html output is started.
* Direct access to password information is deprecated. The saved
* password information is available only to the SquirrelMail script
* that is called/executed AFTER the current one. If your script
* needs access to the saved password after a sqauth_save_password()
* call, use the returned OTP encrypted key.
*
* @param string $pass password
*
* @return string Password encrypted with OTP. In case the script
* wants to access the password information before
* the end of its execution.
*
* @since 1.4.16
*
*/
function sqauth_save_password($pass) {
sqgetGlobalVar('base_uri', $base_uri, SQ_SESSION);
$onetimepad = OneTimePadCreate(strlen($pass));
sqsession_register($onetimepad,'onetimepad');
$key = OneTimePadEncrypt($pass, $onetimepad);
sqsetcookie('key', $key, false, $base_uri);
return $key;
}
/**
* Fillin user and password based on SMTP auth settings.
*
* @param string $user Reference to SMTP username
* @param string $pass Reference to SMTP password (unencrypted)
* @since 1.4.11
*/
function get_smtp_user(&$user, &$pass) {
global $username, $smtp_auth_mech,
$smtp_sitewide_user, $smtp_sitewide_pass;
if ($smtp_auth_mech == 'none') {
$user = '';
$pass = '';
} elseif ( isset($smtp_sitewide_user) && isset($smtp_sitewide_pass) &&
!empty($smtp_sitewide_user)) {
$user = $smtp_sitewide_user;
$pass = $smtp_sitewide_pass;
} else {
$user = $username;
$pass = sqauth_read_password();
}
// plugin authors note: override $user or $pass by
// returning an array where the new username is the
// first array value and the new password is the
// second array value e.g., return array($myuser, $mypass);
//
$ret = do_hook_function('smtp_auth', array($user, $pass));
if (!empty($ret[0]))
$user = $ret[0];
if (!empty($ret[1]))
$pass = $ret[1];
}
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