<?php
 define("ACC_NAME", "bouncer222");
 define("ACC_PASS", "PASSWORDHERE");
 define("GROUP_ID", "103582791430981168"); // open steam group page and see "Enter chat room" link, which contains ID
 define("MY_STEAM_ID", "STEAM_0:0:35005283"); // steam ID which can invite to join group

 $invite_steam_id = $_GET['i'];

 $ids = file('invited_ids.txt');
 foreach($ids as $id) {
   $id = trim($id);
   if ( $id == $invite_steam_id )
     die($id .": Already invited!\n");
 }

 function GetFriendID( $steam_id ) {
   if ( !$steam_id )
     return 0;
   $auth = explode(':', $steam_id);
   if ( !$auth[2] )
     return 0;
   $fid = gmp_init($auth[2]);
   $fid = gmp_mul($fid, "2");
   $fid = gmp_add($fid, "76561197960265728");
   $fid = gmp_add($fid, $auth[1]);
   return gmp_strval($fid);
 }


 require_once "HTTP/Request.php";

 $req = &new HTTP_Request('https://steamcommunity.com');
 $req->setMethod(HTTP_REQUEST_METHOD_POST);

 $req->addPostData("action", "doLogin");
 $req->addPostData("goto", "");

 $req->addPostData("steamAccountName", ACC_NAME);
 $req->addPostData("steamPassword", ACC_PASS);

 echo "Login: ";

 $res = $req->sendRequest();
 if (PEAR::isError($res))
   die($res->getMessage());

 $cookies = $req->getResponseCookies();
 if ( !$cookies )
   die("fail!\n");

 echo "ok\n";

 foreach($cookies as $cookie)
   $req->addCookie($cookie['name'],$cookie['value']);

 $mid = GetFriendID(MY_STEAM_ID);
 $fid = GetFriendID($invite_steam_id);
 $url = "
 http://steamcommunity.com/actions/GroupInvite?type=groupInvite&inviter=$mid&invitee=$fid&group=";GROUP_ID;

 echo "Inviting $invite_steam_id ($fid): ";
 $req->setMethod(HTTP_REQUEST_METHOD_GET);
 $req->setUrl($url);

 $res = $req->sendRequest();
 if (PEAR::isError($res))
   die($res->getMessage());

 $data = $req->getResponseBody();
 preg_match("/CDATA\[([^\]]+)\]/", $data, $matches);
 echo $matches[1] . "\n";
 if ( $matches[1] == "OK" )
   file_put_contents('invited_ids.txt', $invite_steam_id . "\n",
 FILE_APPEND);
 ?>