<?php
/***************************************************************************
 *  Copyright (C) 2003-2014 Polytechnique.org                              *
 *  http://opensource.polytechnique.org/                                   *
 *                                                                         *
 *  This program is free software; you can redistribute it and/or modify   *
 *  it under the terms of the GNU General Public License as published by   *
 *  the Free Software Foundation; either version 2 of the License, or      *
 *  (at your option) any later version.                                    *
 *                                                                         *
 *  This program is distributed in the hope that it will be useful,        *
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of         *
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the          *
 *  GNU General Public License for more details.                           *
 *                                                                         *
 *  You should have received a copy of the GNU General Public License      *
 *  along with this program; if not, write to the Free Software            *
 *  Foundation, Inc.,                                                      *
 *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA                *
 ***************************************************************************/

class XorgSession extends PlSession
{
    const INVALID_USER = -2;
    const NO_COOKIE = -1;
    const COOKIE_SUCCESS = 0;
    const INVALID_COOKIE = 1;

    public function __construct()
    {
        parent::__construct();
    }

    public function startAvailableAuth()
    {
        if (!S::logged()) {
            switch ($this->tryCookie()) {
              case self::COOKIE_SUCCESS:
                if (!$this->start(AUTH_COOKIE)) {
                    return false;
                }
                break;

              case self::INVALID_USER:
              case self::INVALID_COOKIE:
                return false;
            }
        }
        if ((check_ip('dangerous') && S::has('uid')) || check_account()) {
            S::logger()->log("view_page", $_SERVER['REQUEST_URI']);
        }
        return true;
    }

    /** Check the cookie and set the associated uid in the auth_by_cookie session variable.
     */
    private function tryCookie()
    {
        S::kill('auth_by_cookie');
        if (Cookie::v('access') == '' || !Cookie::has('uid')) {
            return self::NO_COOKIE;
        }

        $res = XDB::query('SELECT  uid, password
                             FROM  accounts
                            WHERE  uid = {?} AND state = \'active\'',
                         Cookie::i('uid'));
        if ($res->numRows() != 0) {
            list($uid, $password) = $res->fetchOneRow();
            if (sha1($password) == Cookie::v('access')) {
                S::set('auth_by_cookie', $uid);
                return self::COOKIE_SUCCESS;
            } else {
                return self::INVALID_COOKIE;
            }
        }
        return self::INVALID_USER;
    }

    const TEXT_INVALID_LOGIN = "Mot de passe ou nom d'utilisateur invalide";
    const TEXT_INVALID_PASS = "Mot de passe invalide";

    private function checkPassword($login, User $user, $response)
    {
        if ($user === null) {
            Platal::page()->trigError(self::TEXT_INVALID_LOGIN);
            return false;
        } else {
            $password = $user->password();
            $expected_response = sha1("$login:$password:" . S::v('challenge'));
            /* Deprecates len(password) > 10 conversion. */
            if ($response != $expected_response) {
                if (!S::logged()) {
                    Platal::page()->trigError(self::TEXT_INVALID_LOGIN);
                } else {
                    Platal::page()->trigError(self::TEXT_INVALID_PASS);
                }
                S::logger($uid)->log('auth_fail', 'bad password');
                return false;
            }
            return true;
        }
    }


    /** Check auth.
     */
    protected function doAuth($level)
    {
        global $globals;

        /* Cookie authentication
         */
        if ($level == AUTH_COOKIE && !S::has('auth_by_cookie')) {
            $this->tryCookie();
        }
        if ($level == AUTH_COOKIE && S::has('auth_by_cookie')) {
            if (!S::logged()) {
                S::set('auth', AUTH_COOKIE);
            }
            return User::getSilentWithUID(S::i('auth_by_cookie'));
        }


        /* We want to do auth... we must have infos from a form.
         */
        if (!Post::has('username') || !Post::has('response') || !S::has('challenge')) {
            return null;
        }

        /** We come from an authentication form.
         */
        if (S::suid()) {
            $login = S::suid('uid');
        } else {
            $login = Post::v('username');
        }

        $user = User::getSilent($login);

        if (is_null($user)) {
            Platal::page()->trigError(self::TEXT_INVALID_LOGIN);
            $success = false;
        } else {
            if (S::suid()) {
                $success = (S::suid('uid') == $user->id());
            } else {
                $success = $this->checkPassword($login, $user, Post::v('response'));
            }
        }

        if ($success) {
            S::set('auth', AUTH_PASSWD);
            S::kill('challenge');
            S::logger($user->id())->log('auth_ok');
        }
        return $user;
    }

    protected function startSessionAs($user, $level)
    {
        if ((!is_null(S::user()) && S::user()->id() != $user->id())
            || (S::has('uid') && S::i('uid') != $user->id())) {
            return false;
        } else if (S::has('uid')) {
            return true;
        }
        if ($level == AUTH_SUID) {
            S::set('auth', AUTH_PASSWD);
        }

        // Loads uid and hruid into the session for developement conveniance.
        $_SESSION = array_merge($_SESSION, array('uid' => $user->id(), 'hruid' => $user->hruid, 'token' => $user->token, 'user' => $user));

        // Starts the session's logger, and sets up the permanent cookie.
        if (S::suid()) {
            S::logger()->log("suid_start", S::v('hruid') . ' by ' . S::suid('hruid'));
        } else {
            S::logger()->saveLastSession();
            Cookie::set('uid', $user->id(), 300);

            if (S::i('auth_by_cookie') == $user->id() || Post::v('remember', 'false') == 'true') {
                $this->setAccessCookie(false, S::i('auth_by_cookie') != $user->id());
            } else {
                $this->killAccessCookie();

                // If login for an external website and not activating cookie,
                // mark that we want to disconnect once external auth checks
                // have been performed.
                if (Post::b('external_auth')) {
                    S::set('external_auth_exit', true);
                }
            }
        }

        // Finalizes the session setup.
        $this->makePerms($user->perms, $user->is_admin);
        $this->securityChecks();
        $this->setSkin();
        $this->updateNbNotifs();
        // Only check email redirection for 'internal' users.
        if ($user->checkPerms(PERMS_USER)) {
            check_redirect();
        }

        // We should not have to use this private data anymore
        S::kill('auth_by_cookie');
        return true;
    }

    private function securityChecks()
    {
        $mail_subject = array();
        if (check_account()) {
            $mail_subject[] = 'Connexion d\'un utilisateur surveillé';
        }
        if (check_ip('unsafe')) {
            $mail_subject[] = 'Une IP surveillee a tente de se connecter';
            if (check_ip('ban')) {
                send_warning_mail(implode(' - ', $mail_subject));
                $this->destroy();
                Platal::page()->kill('Une erreur est survenue lors de la procédure d\'authentification. '
                                    . 'Merci de contacter au plus vite '
                                    . '<a href="mailto:support@polytechnique.org">support@polytechnique.org</a>');
                return false;
            }
        }
        if (count($mail_subject)) {
            send_warning_mail(implode(' - ', $mail_subject));
        }
    }

    /**
     * The authentication schema is based on three query parameters:
     *   ?user=<hruid>&timestamp=<timestamp>&sig=<sig>
     * where:
     *   - hruid is the hruid of the querying user
     *   - timestamp is the current UNIX timestamp, which has to be within a
     *     given distance of the server-side UNIX timestamp
     *   - sig is the HMAC of "<method>#<resource>#<payload>#<timestamp>" using
     *     a known secret of the user as the key.
     *
     * At the moment, the shared secret of the user is the sha1 hash of its
     * password. This is temporary, though, until better support for tokens is
     * implemented in plat/al.
     * TODO(vzanotti): Switch to dedicated secrets for authentication.
     */
    public function apiAuth($method, $resource, $payload)
    {
        // Verify that the timestamp is within acceptable bounds.
        $timestamp = Env::i('timestamp', 0);
        if (abs($timestamp - time()) > Platal::globals()->api->timestamp_tolerance) {
            return null;
        }

        // Retrieve the user corresponding to the forlife. Note that at the
        // moment, other aliases are also accepted.
        $user = User::getSilent(Env::s('user', ''));
        if (is_null($user) || !$user->isActive()) {
            return null;
        }

        // Determine the list of tokens associated with the user. At the moment,
        // this is just the sha1 of the password.
        $tokens = array($user->password());

        // For each token, try to validate the signature.
        $message = implode('#', array($method, $resource, $payload, $timestamp));
        $signature = Env::s('sig');
        foreach ($tokens as $token) {
            $expected_signature = hash_hmac(
                Platal::globals()->api->hmac_algo, $message, $token);
            if ($signature == $expected_signature) {
                return $user;
            }
        }

        return null;
    }

    public function tokenAuth($login, $token)
    {
        $res = XDB::query('SELECT  a.uid, a.hruid
                             FROM  accounts AS a
                            WHERE  a.token = {?} AND a.hruid = {?} AND a.state = \'active\'',
                          $token, $login);
        if ($res->numRows() == 1) {
            return new User(null, $res->fetchOneAssoc());
        }
        return null;
    }

    protected function makePerms($perm, $is_admin)
    {
        S::set('perms', User::makePerms($perm, $is_admin));
    }

    public function setSkin()
    {
        if (S::logged() && (!S::has('skin') || S::suid())) {
            $res = XDB::query('SELECT  skin_tpl
                                 FROM  accounts AS a
                           INNER JOIN  skins    AS s on (a.skin = s.id)
                                WHERE  a.uid = {?} AND skin_tpl != \'\'', S::i('uid'));
            S::set('skin', $res->fetchOneCell());
        }
    }

    public function loggedLevel()
    {
        return AUTH_COOKIE;
    }

    public function sureLevel()
    {
        return AUTH_PASSWD;
    }


    public function updateNbNotifs()
    {
        require_once 'notifs.inc.php';
        $user = S::user();
        $n = Watch::getCount($user);
        S::set('notifs', $n);
    }

    public function setAccessCookie($replace = false, $log = true) {
        if (S::suid() || ($replace && !Cookie::blank('access'))) {
            return;
        }
        Cookie::set('access', sha1(S::user()->password()), 300, true);
        if ($log) {
            S::logger()->log('cookie_on');
        }
    }

    public function killAccessCookie($log = true) {
        Cookie::kill('access');
        if ($log) {
            S::logger()->log('cookie_off');
        }
    }

    public function killLoginFormCookies() {
        Cookie::kill('uid');
        Cookie::kill('domain');
    }
}

// vim:set et sw=4 sts=4 sws=4 foldmethod=marker fenc=utf-8:
?>