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<?

//*********************++ HILFS-Funktionen ******************************//
 function escape_string($string){
    if(get_magic_quotes_gpc()) {

      $string = stripslashes($string);
    }

    return mysql_real_escape_string(strip_tags($string));
  }
//********************ENDE HILFS-Funktionen ******************************//
//*********************++ USER-HILFS-Funktionen ******************************//
 
 function register($user,$password,$email){

   $user     = escape_string($user);
   $password = escape_string($password);
   $email    = escape_string($email);
   $return   =  "Der Benutzer wurde erstellt.
                 Sie k&ouml;nnen sich nun als $user mit ihrem Passwort anmelden!";
   $sql= "INSERT INTO ".MYSQL_TABLE." SET name='$user',".
         " password=MD5('$password'), email='$email'";
   mysql_query($sql) or die(mysql_error());;
   return $return;
 }

 function return_user($user="",$password=""){
   $user     = escape_string($user);
   $password = escape_string($password);
   if($user == "" && $password == ""){

     $session = session_id();
     $sql = "SELECT * FROM `".MYSQL_TABLE."` WHERE `session`='$session'";
   }
   else{

     $sql = "SELECT * FROM `".MYSQL_TABLE."` WHERE `password`=MD5('$password')".
            " AND `name`='$user'";
   }
   $result = mysql_query($sql) or die(mysql_error());
   if (mysql_num_rows($result) == 1){

     $user  = mysql_fetch_assoc($result);
     return $user['id'];
   }
   else{
     return false;;
   } 
 }

 function login($id){
   $id = intval($id);
   $session = session_id();
   $sql = "UPDATE `".MYSQL_TABLE."` SET `session`='$session'".
          "WHERE `id`='$id'";
   mysql_query($sql) or die(mysql_error());
 }

 function logged_in(){
   $session = session_id();
     $sql = "SELECT id FROM `".MYSQL_TABLE."` WHERE `session`='$session'";
     $result = mysql_query($sql);
     $assoc  = mysql_fetch_assoc($result);
     if(isset($assoc[id])){

      return $assoc[id];
     }
     else{
      return false;
     }
 }

 function logout(){
   $session = session_id();
   $sql = "UPDATE `".MYSQL_TABLE."` SET `session`='' ".
          "WHERE `session` = '$session'";
   if(mysql_query($sql)){

    return true;
   }
   else{
     return false;
   }
   session_unset();
   session_destroy();
 }

 function userName($id){
   $id     = intval($id);
   $sql    = "SELECT `name` FROM `".MYSQL_TABLE."` WHERE `id`='$id'";
   $result = mysql_query($sql);
   $assoc  = mysql_fetch_assoc($result);
   return $assoc[name];
 }

//*********************ENDE USER-HILFS-Funktionen **********************//
 
 ?>
Listing 1.10 - Die Datei functions.inc.php