Essential PHP Security Book Cover
Essential PHP Security by Chris Shiflett
About | Contents | Buy Now | Reviews | Errata | Code
  1. Foreword
  2. Preface
  1. Introduction
  2. Forms and URLs
          ch02.pdf
  3. Databases and SQL
  4. Sessions and Cookies
          ch04.pdf
  5. Includes
  6. Files and Commands
  7. Authentication and Authorization
  8. Shared Hosting
  1. Configuration Directives
  2. Functions
  3. Cryptography
  4. Index

Check a Persistent Login Cookie

(Chapter 7, Authentication and Authorization - Pg 71-73)

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<?php

/* mysql_connect() */
/* mysql_select_db() */

$clean = array();
$mysql = array();

$now time();
$salt 'SHIFLETT';

list(
$identifier$token) = explode(':'$_COOKIE['auth']);

if (
ctype_alnum($identifier) && ctype_alnum($token))
{
    
$clean['identifier'] = $identifier;
    
$clean['token'] = $token;
}
else
{
    
/* ... */
}

$mysql['identifier'] = mysql_real_escape_string($clean['identifier']);

$sql "SELECT username, token, timeout
        FROM   users
        WHERE  identifier = '
{$mysql['identifier']}'";

if (
$result mysql_query($sql))
{
    if (
mysql_num_rows($result))
    {
        
$record mysql_fetch_assoc($result);

        if (
$clean['token'] != $record['token'])
        {
            
/* Failed Login (wrong token) */
        
}
        elseif (
$now $record['timeout'])
        {
            
/* Failed Login (timeout) */
        
}
        elseif (
$clean['identifier'] !=
                
md5($salt md5($record['username'] . $salt)))
        {
            
/* Failed Login (invalid identifier) */
        
}
        else
        {
            
/* Successful Login */
        
}
    }
    else
    {
        
/* Failed Login (invalid identifier) */
    
}
}
else
{
    
/* Error */
}

?>