<?php

/**

 * Webserver class

 * 

 * Greyhound - real web management for Amarok

 * Copyright (C) 2008 Dan Fuhry

 *

 * This program is Free Software; you can redistribute 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 details.

 */

require('multithreading.php');

/**

 * Version of the server

 * @const string

 */

define('HTTPD_VERSION', '0.1b5');

/**

 * Length of keep-alive connections

 * @const int

 */

define('HTTPD_KEEP_ALIVE_TIMEOUT', 300);

/**

 * Webserver system icons

 */

define('HTTPD_ICON_SCRIPT', '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');

define('HTTPD_ICON_FOLDER', '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');

define('HTTPD_ICON_FILE',   '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');

/**

 * Abstraction layer to use

 */

define('HTTPD_SOCKET_LAYER', 'Stream');

/**

 * Simple but full-featured embedded web server written in PHP.

 * @package Amarok

 * @subpackage WebControl

 * @author Dan Fuhry

 * @license GNU General Public License <http://www.gnu.org/licenses/old-licenses/gpl-2.0.html>

 */

class WebServer

{

  /**

   * IP address we're bound to

   * @var string

   */

  var $bind_address = '127.0.0.1';

  /**

   * Port we're listening on

   * @var int

   */

  var $port = 8080;

  /**

   * Socket abstraction object

   * @var object

   */

  var $server = null;

  /**

   * Server string

   * @var string

   */

  var $server_string = 'PhpHttpd';

  /**

   * Default document (well default handler)

   * @var string

   */

  var $default_document = false;

  /**

   * List of filenames or handlers used when a directory listing is requested

   * @var array

   */

  var $directory_index = array('index.html', 'index.htm', 'index', 'default.html', 'default.htm');

  /**

   * HTTP response code set by the handler function

   * @var int

   */

  var $response_code = 0;

  /**

   * Content type set by the current handler function

   * @var string

   */

  var $content_type = '';

  /**

   * Response headers to send back to the client

   * @var array

   */

  var $response_headers = array();

  /**

   * List of handlers

   * @var array

   */

  var $handlers = array();

  /**

   * Switch to control if directory listing is enabled

   * @var bool

   */

  var $allow_dir_list = false;

  /**

   * Switch to control forking support.

   * @var bool

   */

  var $allow_fork = true;

  /**

   * Multi-threading manager.

   * @var object

   */

  var $threader = false;

  /**

   * Keep-alive support uses this to track what the client requested.

   * Only used if $allow_fork is set to true.

   * @var bool

   */

  var $in_keepalive = false;

  /**

   * UUID for this server instance

   * @var string

   */

  var $uuid = '00000000-0000-0000-0000-000000000000';

  /**

   * Switch to track whether a scriptlet is running. If it is, send_http_error() does more than normal.

   * @var bool

   */

  var $in_scriptlet = false;

  /**

   * Switch to track whether headers have been sent or not.

   * @var bool

   */

  var $headers_sent = false;

  /**

   * Switch to track if the socket is bound and thus needs to be freed or not

   * @var bool

   */

  var $socket_initted = false;

  /**

   * The list of child processes spawned by this server.

   * @var array

   */

  var $child_list = array();

  /**

   * The parent process's PID

   * @var int

   */

  var $parent_pid = 0;

  /**

   * List of IPC request handlers

   * @var array

   * @access private

   */

  var $ipc_handlers = array();

  /**

   * Sockets for parent and child to communicate

   * @var resource

   * @var resource

   */

  var $parent_sock = null;

  var $child_sock = null;

  /**

   * Switched on when a graceful reboot event is sent.

   * @var bool

   */

  var $reboot_sent = false;

  /**

   * Constructor.

   * @param string IPv4 address to bind to

   * @param int Port number

   * @param int If port is under 1024, specify a user ID/name to switch to here

   * @param int If port is under 1024, specify a group ID/name to switch to here

   */

  function __construct($address = '127.0.0.1', $port = 8080, $targetuser = null, $targetgroup = null)

  {

    @set_time_limit(0);

    @ini_set('memory_limit', '128M');

    // make sure we're not running as root

    // note that if allow_root is true, you must specify a UID/GID (or user/group) to switch to once the socket is bound

    $allow_root = ( $port < 1024 ) ? true : false;

    if ( function_exists('posix_geteuid') )

    {

      $euid = posix_geteuid();

      $egid = posix_getegid();

      $username = posix_getpwuid($euid);

      $username = $username['name'];

      $group = posix_getgrgid($egid);

      $group = $group['name'];

      if ( $euid == 0 && !$allow_root )

      {

        // running as root but not on a privileged port - die for security

        burnout("Running as superuser (user \"$username\" and group \"$group\"). This is not allowed for security reasons.");

      }

      else if ( $euid == 0 && $allow_root )

      {

        // running as root and port below 1024, so notify of the switch and verify that a target UID and GID were passed

        if ( $targetuser === null || $targetgroup === null )

        {

          // no target user/group specified

          burnout("Must specify a target user and group when running server as root");

        }

        // get info about target user/group

        if ( is_string($targetuser) )

        {

          $targetuser = posix_getpwnam($targetuser);

          $targetuser = $targetuser['uid'];

        }

        if ( is_string($targetgroup) )

        {

          $targetgroup = posix_getgrnam($targetgroup);

          $targetgroup = $targetgroup['gid'];

        }

        // make sure all info is valid

        if ( !is_int($targetuser) || !is_int($targetgroup) )

        {

          burnout('Invalid user or group specified');

        }

        $userinfo = posix_getpwuid($targetuser);

        $groupinfo = posix_getgrgid($targetgroup);

        if ( function_exists('status') )

          status("Will switch to user \"{$userinfo['name']}\" and group \"{$groupinfo['name']}\" shortly after binding to socket");

      }

      else if ( $allow_root && $euid > 0 )

      {

        burnout("Must be superuser to bind to ports below 1024");

      }

    }

    $socket_do_root = ( $allow_root ) ? function_exists('posix_geteuid') : false;

    $class = 'Socket_' . HTTPD_SOCKET_LAYER;

    $this->server = new $class();

    if ( is_array($address) )

    {

      foreach ( $address as $a )

      {

        if ( is_array($port) )

        {

          foreach ( $port as $p )

          {

            $this->server->tcp_listen($a, $p);

          }

        }

        else

        {

          $this->server->tcp_listen($a, $port);

        }

      }

    }

    else

    {

      if ( is_array($port) )

      {

        foreach ( $port as $p )

        {

          $this->server->tcp_listen($address, $p);

        }

      }

      else

      {

        $this->server->tcp_listen($address, $port);

      }

    }

    // if running as root and we made it here, switch credentials

    if ( $socket_do_root )

    {

      posix_setuid($targetuser);

      posix_setgid($targetgroup);

      posix_setegid($targetgroup);

      posix_seteuid($targetuser);

      if ( function_exists('status') )

        status('Successfully switched user ID');

    }

    $this->bind_address = $address;

    $this->port = $port;

    $this->server_string = "PhpHttpd/" . HTTPD_VERSION . " PHP/" . PHP_VERSION . "\r\n";

    $this->parent_pid = getmypid();

    $this->threader = new Threader();

    $this->threader->ipc_register('ws_reboot', array(&$this, 'reboot'));

    // create a UUID

    $uuid_base = md5(microtime() . ( function_exists('mt_rand') ? mt_rand() : rand() ));

    $this->uuid = substr($uuid_base, 0,  8) . '-' .

                  substr($uuid_base, 8,  4) . '-' .

                  substr($uuid_base, 12, 4) . '-' .

                  substr($uuid_base, 16, 4) . '-' .

                  substr($uuid_base, 20, 20);

  }

  /**

   * Destructor.

   */

  function __destruct()

  {

    if ( !$this->threader )

    {

      return false;

    }

    if ( !$this->threader->is_child() && $this->socket_initted )

    {

      if ( function_exists('status') )

        status('WebServer: destroying socket');

      $this->server->destroy();

      // tell all children to shut down

      if ( $this->allow_fork )

      {

        if ( function_exists('status') )

          status('WebServer: asking all children to exit');

        $this->threader->kill_all_children();

      }

    }

  }

  /**

   * Reboot the server. Useful for applying new settings.

   * @param string Optional, new IP address to bind to

   * @param int Optional, new port to bind to

   * @param bool Optional, whether to allow forking or not

   */

  function reboot($addr = null, $port = null, $allow_fork = null)

  {

    if ( function_exists('status') )

      status('Reboot request has been received');

    $addr = ( !is_string($addr) ) ? $this->bind_address : $addr;

    $port = ( !is_int($port) ) ? $this->port : $port;

    $fork = ( !is_bool($allow_fork) ) ? $this->allow_fork : $allow_fork;

    //

    // REBOOTING IS A COMPLICATED THING.

    // We need to ask all children to close any existing connections so

    // that all relevant socket resources can be freed. Then we need to

    // call the constructor again to respawn the server, and finally

    // re-enter the server loop.

    //

    // However, reboot() is often called from a PHP-based handler. This

    // means that some config page probably still needs to be sent. What

    // we can do here is send an IPC event that fires the actual reboot,

    // then return to allow the current page to finish up. We also need

    // to signal the current process to shut down any existing keep-

    // alive connections. This can be accomplished by setting in_keepalive

    // to false.

    //

    // Kill the entire child after this response is sent

    $this->in_keepalive = false;

    // If we're the parent process, we need to know that a reboot event

    // was fired, and thus the server's main socket needs to be destroyed

    // and recreated. This is just done with another boolean switch.

    $this->reboot_sent = true;

    // this is really to track if there are any children

    $oldfork = $this->allow_fork;

    // Set our new server flags

    $this->bind_address = $addr;

    $this->port = $port;

    $this->allow_fork = $fork;

    // If we're a child, we have to tell the parent what the hell is

    // going on, and then get out of here as quickly as possible

    // (and other children should do the same). If this is a child,

    // fire an IPC reboot event. Else, fire a "die all" event

    if ( $this->threader->is_child() )

    {

      if ( function_exists('status') )

        status('Signaling parent with parameter changes (fork = ' . intval($fork) . ') + reboot request');

      // this is the child

      $this->threader->ipc_send(array(

        'action' => 'ws_reboot',

        'addr' => $addr,

        'port' => $port,

        'fork' => $fork

      ));

    }

    else if ( !$this->threader->is_child() && $oldfork )

    {

      // we are the parent and have been asked to respawn. there are (presumably)

      // still children running around; when one of them dies, we'll receive a

      // SIGCHLD, but often times this is already being called from the SIGUSR2

      // handler. whoops.

      if ( function_exists('status') )

        status('Waiting on all children');

      // this is the parent, and there are children present

      $this->threader->kill_all_children();

      // all children are dead, we are ok to respawn

      $this->respawn();

    }

    else

    {

      // not sure what to do in this particular scenario.

    }

  }

  /**

   * Respawns the server. All children should be dead, and any client

   * connections must be closed.

   */

  function respawn()

  {

    $this->reboot_sent = false;

    if ( function_exists('status') )

      status('Respawn event sent');

    $this->server->destroy();

    unset($this->server);

    // try to spawn up to 10 times

    for ( $i = 0; $i < 10; $i++ )

    {

      try

      {

        $this->__construct($this->bind_address, $this->port);

      }

      catch ( Exception $e )

      {

        if ( $i == 9 )

        {

          if ( function_exists('burnout') )

          {

            burnout("Couldn't respawn because one of the child processes did not die, and thus the port was not freed.");

          }

          exit(1);

        }

        if ( function_exists('status') )

        {

          status("Respawn failed, retrying in 2 seconds");

        }

        usleep(2000000);

        continue;

      }