Re: Login Script: mysql_num_rows(): supplied argument is not a valid MySQL result resource

David Hutto schreef:
> 
> --- On Fri, 2/19/10, David Hutto <[email protected]> wrote:
> 
> From: David Hutto <[email protected]>
> Subject: Login Script: mysql_num_rows(): supplied argument is not a valid MySQL result resource
> To: [email protected]
> Date: Friday, February 19, 2010, 3:30 AM
> 
> The following script is supposed to validate a username and password in a mysql db.  When entering the username and password of a preregistered user, I get the following errors:
> 
> Warning:  mysql_num_rows(): supplied argument is not a valid MySQL result resource in /var/www/login.php on line 24
> 
> 
> 
> Warning:  Cannot modify header information - headers already sent by (output started at /var/www/login.php:24) in /var/www/login.php on line 26
> 
> On line 24 is:
> 
>>>> if(!mysql_num_rows($login)) //if the username and pass are wrong
> 
> --The supplied argument is $login, which is previously defined as:
> 
>>>> $login = mysql_query("SELECT * FROM 'userinfo' WHERE `user` = '$user' AND `pass` = '$pass`");
> 
> --which is further defined above it as these values:
> 
>   $user = $_POST['user']; //pulls the username from the form
>   $pw = $_POST['pass']; //pulls the pass from the form
>   $pass = md5($pw); //makes our password an md
> 
> So why is the sum of those previous definitions an invalid argument for the mysql_query() to test for whether the username and md5 password values are true/equivalent to each other?
> 
> Because basically !mysql_num_rows($login) is just if'ing the lack of a user/pass match, else it continues to set cookie and session variables.
> 
> If I'm looking at this wrong let me know.
> 
> Thanks for any help you may be able to provide, below is the
>  full login.php page.
> 
> David
> ********************************************************
> 
> This is the full login.php script, I'm pretty sure no other portions are needed to show at this point for the current problem:
> 
> <?php
> $act = $_GET['act']; //retrives the page action
> if(empty($act)) //if there is no action
> {
>   echo('<form action="login.php?act=auth" method="post" name="loginform" id="loginform">
>   <p>Username
>   <input type="text" name="user">
>   </p>
>   <p>Password
>   <input type="password" name="pass">
>   </p>
>   <p>
>   <input type="submit" name="Submit" value="Login">
>   </p>
>   </form>');
> }
> elseif($act == "auth") //if our page action = auth
> {
>   $user = $_POST['user']; //pulls the username from the form
>   $pw = $_POST['pass']; //pulls the pass from
>  the form
>   $pass = md5($pw); //makes our password an md5
>   include("connect.php"); //connects to our mysql database
>   $login = mysql_query("SELECT * FROM `userinfo` WHERE `user` = '$user' AND `pass` = '$pass`"); //selects info from our table if the row has the same user and pass that our form does
>   if(!mysql_num_rows($login)) //if the username and pass are wrong
>   {
>         header("Location: login.php");  //redirects to our login page
>         die(); //stops the page from going any further
>   }
>   else
>   {
>         setcookie("user", $user, time()+3600);//sets our user cookie
>                 setcookie("pass", $pass, time()+3600);//sets our pass
>  cookie
>                 header("Location: memprar.php");//instead of yourpage.php it would be your protected page
>   } 
> }
> ?>
> 
> 
> 
> 
> 
>       
> 
> 
>       

The query should be:
SELECT * FROM `userinfo` WHERE `user` = '$user' AND `pass` = '$pass'

Remember: ` for tables and columns, ' for strings.
Also, look up SQL Injection, as your script contains a huge vulnerability.
This can be fixed using mysql_real_escape_string, so it is this:
ELECT * FROM `userinfo` WHERE `user` = 
'".mysql_real_escape_string($user)."' AND `pass` = 
'".mysql_real_escape_string($pass)."'

-- 
Kind regards,
Mark Cilissen / Pixlism