<?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.

 */

/**

 * Version of the server

 * @const string

 */

define('HTTPD_VERSION', '0.1b4');

/**

 * 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';

  /**

   * 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;

  /**

   * 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;

  /**

   * Sockets for parent and child to communicate

   * @var resource

   * @var resource

   */

  var $parent_sock = null;

  var $child_sock = null;

  /**

   * 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');

    // do we have socket functions?

    if ( !function_exists('socket_create') )

    {

      burnout('System does not support socket functions. Please rebuild your PHP or install an appropriate extension.');

    }

    // 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['uid'];

        }

        // 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();

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

    $this->parent_pid = getmypid();

    // 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 ( !defined('HTTPD_WS_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->send_ipc_event("die _");

      }

      // that last operation should have been asynchronous, so shut everything down now

      @socket_shutdown($this->parent_sock);

      @socket_close($this->parent_sock);

    }

    else if ( defined('HTTPD_WS_CHILD') )

    {

      @socket_shutdown($this->child_sock);

      @socket_close($this->child_sock);

    }

  }

  /**

   * Main server loop

   */

  function serve()

  {

    // If we're allowed to use multithreading, set up to handle SIGUSR2 which waits on the child

    if ( function_exists('pcntl_signal') && $this->allow_fork )

    {

      // required for signal handling to work

      declare(ticks=1);

      // trap SIGTERM

      pcntl_signal(SIGUSR2, array(&$this, '_ipc_event'));

      if ( !($sockets = stream_socket_pair(STREAM_PF_UNIX, STREAM_SOCK_STREAM, STREAM_IPPROTO_IP)) )

      {

        throw new Exception("Could not set up private IPC socket. Reason: " . socket_strerror(socket_last_error()));

      }

      $this->parent_sock =& $sockets[0];

      $this->child_sock =& $sockets[1];

    }

    while ( true )

    {

      // if this is a child process, we're finished - close up shop

      if ( defined('HTTPD_WS_CHILD') && !$this->in_keepalive )

      {

        if ( function_exists('status') )

          status('Exiting child process');

        $remote->destroy();

        // let the parent know that we're out of here

        $this->send_ipc_event("exit " . getmypid());

        // bye

        exit(0);

      }

      // wait for connection...

      // trick from http://us.php.net/manual/en/function.socket-accept.php

      if ( !defined('HTTPD_WS_CHILD') )

      {

        $remote = $this->server->accept();

      }

      if ( !$remote )

      {

        $this->in_keepalive = false;

        continue;

      }

      // fork off if possible

      if ( function_exists('pcntl_fork') && $this->allow_fork && !$this->in_keepalive )

      {

        $pid = pcntl_fork();

        if ( $pid == -1 )

        {

          // do nothing; continue responding to request in single-threaded mode

        }

        else if ( $pid )

        {

          // we are the parent, continue listening

          $remote->soft_shutdown();

          $this->child_list[] = $pid;

          continue;

        }

        else

        {

          // this is the child

          define('HTTPD_WS_CHILD', 1);

          // setup to handle signals

          if ( function_exists('pcntl_signal') )

          {

            // required for signal handling to work

            declare(ticks=1);

            // trap SIGTERM

            pcntl_signal(SIGUSR2, array(&$this, '_ipc_event'));

          }

        }

      }

      $this->in_keepalive = false;

      $this->headers_sent = false;

      $this->in_scriptlet = false;

      //

      // READ THE REQUEST

      //

      // this is a complicated situation because we need to keep enough ticks going to properly handle

      // signals, meaning we can't use stream_set_timeout() and instead need to rely on our own timing

      // logic. setting the timeout to a short period, say 200,000 usec, we can minimize CPU usage and

      // have a good response time.

      $remote->set_timeout(0, 200000);

      $start_time = microtime(true);

      $client_headers = '';

      $last_line = '';

      while ( true )

      {

        if ( $start_time + HTTPD_KEEP_ALIVE_TIMEOUT < microtime(true) || $remote->is_eof() )

        {

          // request expired -- end the process here

          if ( !defined('HTTPD_WS_CHILD') )

            $remote->destroy();

          continue 2;

        }

        $line = strval($remote->read_normal());

        $line = str_replace("\r", "", $line);

        // raw layer wants to send 2 empty lines through, stream layer wants to send one.

        $last_line_check = ( HTTPD_SOCKET_LAYER != 'Raw' || ( HTTPD_SOCKET_LAYER == 'Raw' && $last_line == "\n" ) );

        if ( $line == "\n" && $last_line_check )

          // we have two newlines in a row, break out since we have a full request

          break;

        $client_headers .= $line;

        $last_line = $line;

      }

      // parse request

      $client_headers = trim($client_headers);

      if ( isset($last_finish_time) && empty($client_headers) && defined('HTTPD_WS_CHILD') && $last_finish_time + HTTPD_KEEP_ALIVE_TIMEOUT < microtime(true) )

      {

        status('[debug] keep-alive connection timed out (checkpoint 2)');

        continue; // will jump back to the start of the loop and kill the child process

      }

      $client_headers = explode("\n", $client_headers);

      // first line

      $request = $client_headers[0];

      if ( !preg_match('/^(GET|POST) \/([^ ]*) HTTP\/1\.[01]$/', $request, $match) )

      {

        $this->send_http_error($remote, 400, 'Your client issued a malformed or illegal request.');

        continue;

      }

      $method =& $match[1];

      $uri =& $match[2];

      // set client headers

      unset($client_headers[0]);

      foreach ( $client_headers as $line )

      {

        if ( !preg_match('/^([A-z0-9-]+): (.+)$/is', $line, $match) )

          continue;

        $key = 'HTTP_' . strtoupper(str_replace('-', '_', $match[1]));

        $_SERVER[$key] = $match[2];

      }

      // enable keep-alive if requested

      if ( isset($_SERVER['HTTP_CONNECTION']) && defined('HTTPD_WS_CHILD') )

      {

        $this->in_keepalive = ( strtolower($_SERVER['HTTP_CONNECTION']) === 'keep-alive' );

      }

      // parse authorization, if any

      if ( isset($_SERVER['PHP_AUTH_USER']) )

      {

        unset($_SERVER['PHP_AUTH_USER'], $_SERVER['PHP_AUTH_PW']);

      }

      if ( isset($_SERVER['HTTP_AUTHORIZATION']) )

      {

        $data = $_SERVER['HTTP_AUTHORIZATION'];

        $data = substr(strstr($data, ' '), 1);

        $data = base64_decode($data);

        $_SERVER['PHP_AUTH_USER'] = substr($data, 0, strpos($data, ':'));

        $_SERVER['PHP_AUTH_PW'] = substr(strstr($data, ':'), 1);

      }

      // anything on POST?