<?php
/* vim: set expandtab sw=4 ts=4 sts=4: */
/**
 * session handling
 *
 * @todo    add failover or warn if sessions are not configured properly
 * @todo    add an option to use mm-module for session handler
 *
 * @package PhpMyAdmin
 * @see     http://www.php.net/session
 */
if (! defined('PHPMYADMIN')) {
    exit;
}

if (! function_exists('openssl_random_pseudo_bytes')) {
    require_once PHPSECLIB_INC_DIR . '/Crypt/Random.php';
}

// verify if PHP supports session, die if it does not

if (!@function_exists('session_name')) {
    PMA_warnMissingExtension('session', true);
} elseif (ini_get('session.auto_start') !== '' && session_name() != 'phpMyAdmin') {
    // Do not delete the existing session, it might be used by other
    // applications; instead just close it.
    session_write_close();
}

// disable starting of sessions before all settings are done
// does not work, besides how it is written in php manual
//ini_set('session.auto_start', '0');

// session cookie settings
session_set_cookie_params(
    0, $GLOBALS['PMA_Config']->getCookiePath(),
    '', $GLOBALS['PMA_Config']->isHttps(), true
);

// cookies are safer (use @ini_set() in case this function is disabled)
@ini_set('session.use_cookies', 'true');

// optionally set session_save_path
$path = $GLOBALS['PMA_Config']->get('SessionSavePath');
if (!empty($path)) {
    session_save_path($path);
}

// but not all user allow cookies
@ini_set('session.use_only_cookies', 'false');
// do not force transparent session ids, see bug #3398788
//@ini_set('session.use_trans_sid', 'true');
@ini_set(
    'url_rewriter.tags',
    'a=href,frame=src,input=src,form=fakeentry,fieldset='
);
//ini_set('arg_separator.output', '&amp;');

// delete session/cookies when browser is closed
@ini_set('session.cookie_lifetime', '0');

// warn but don't work with bug
@ini_set('session.bug_compat_42', 'false');
@ini_set('session.bug_compat_warn', 'true');

// use more secure session ids
@ini_set('session.hash_function', '1');

// some pages (e.g. stylesheet) may be cached on clients, but not in shared
// proxy servers
session_cache_limiter('private');

// start the session
// on some servers (for example, sourceforge.net), we get a permission error
// on the session data directory, so I add some "@"

// See bug #1538132. This would block normal behavior on a cluster
//ini_set('session.save_handler', 'files');

$session_name = 'phpMyAdmin';
@session_name($session_name);

if (! isset($_COOKIE[$session_name])) {
    // on first start of session we check for errors
    // f.e. session dir cannot be accessed - session file not created
    $orig_error_count = $GLOBALS['error_handler']->countErrors();
    $session_result = session_start();
    if ($session_result !== true
        || $orig_error_count != $GLOBALS['error_handler']->countErrors()
    ) {
        setcookie($session_name, '', 1);
        /*
         * Session initialization is done before selecting language, so we
         * can not use translations here.
         */
        PMA_fatalError(
            'Error during session start; please check your PHP and/or '
            . 'webserver log file and configure your PHP '
            . 'installation properly. Also ensure that cookies are enabled '
            . 'in your browser.'
        );
    }
    unset($orig_error_count, $session_result);
} else {
    session_start();
}

/**
 * Disable setting of session cookies for further session_start() calls.
 */
@ini_set('session.use_cookies', 'true');

/**
 * Token which is used for authenticating access queries.
 * (we use "space PMA_token space" to prevent overwriting)
 */
if (! isset($_SESSION[' PMA_token '])) {
    if (! function_exists('openssl_random_pseudo_bytes')) {
        $_SESSION[' PMA_token '] = bin2hex(phpseclib\Crypt\Random::string(16));
    } else {
        $_SESSION[' PMA_token '] = bin2hex(openssl_random_pseudo_bytes(16));
    }
}

/**
 * tries to secure session from hijacking and fixation
 * should be called before login and after successful login
 * (only required if sensitive information stored in session)
 *
 * @return void
 */
function PMA_secureSession()
{
    // prevent session fixation and XSS
    // (better to use session_status() if available)
    if ((PMA_PHP_INT_VERSION >= 50400 && session_status() === PHP_SESSION_ACTIVE)
        || (PMA_PHP_INT_VERSION < 50400 && session_id() !== '')
    ) {
        session_regenerate_id(true);
    }
    if (! function_exists('openssl_random_pseudo_bytes')) {
        $_SESSION[' PMA_token '] = bin2hex(phpseclib\Crypt\Random::string(16));
    } else {
        $_SESSION[' PMA_token '] = bin2hex(openssl_random_pseudo_bytes(16));
    }
}
