PHP and AJAX Log in validation - php

Question

I need some help troubleshooting my code that's used for Log In validation. It's a combo of AJAX and PHP.
Here's the AJAX code that's directly in the login page.
<script language="javascript">
$(document).ready(function()
{
$("#login_form").submit(function()
{
$("#msgbox").removeClass().addClass('messagebox').text('Validating....').fadeIn(1000);
$.post("/ajax_login.php",{ user_name:$('#username').val(),password:$('#password').val()
,rand:Math.random() } ,function(data)
{
if (data=='no')
{
$("#msgbox").fadeTo
(200,0.1,function()
{
$(this).html('Incorrect Username or Password.')
.addClass('messageboxerror').fadeTo(900,1);
}
);
}
else if(data=='yes')
{
$("#msgbox").fadeTo
(200,0.1,function()
{
$(this).html('Logging in.....').addClass('messageboxok').fadeTo
(900,1, function()
{
document.location='/mainpage.php';
}
);
}
);
}
else
{
$("#msgbox").fadeTo
(200,0.1,function()
{
$(this).html('User is already logged in.').
addClass('messageboxerror').fadeTo(900,1);
}
);
}
});
return false;
});
$("#password").blur(function()
{
$("#login_form").trigger('submit');
});
});
</script>
PHP CODE:
<?
//Log In credentials
if ($rehash==$dboPW && $user_name == $dboUN && $logged=='Y'){echo "alreadyLogged"; exit;}
if ($rehash==$dboPW && $user_name == $dboUN && $logged=='N')
{
echo "yes";
$_SESSION['login'] = $username;
$_SESSION['password'] = $rehash;
$loggedUpdate=mysql_query("UPDATE Users SET LOGGED='Y' WHERE username='$user_name'");
exit;
}
else
{echo "no";}
?>
To summarize this process, someone logs in and the PHP script checks
if the username and password is valid AND that the person is NOT logged in already - returns value of 'yes'
if the username and password is valid AND that the person IS logged in already - returns value of 'alreadyLogged'
Invalid username or password - returns value of 'no'
This gets passed to AJAX, which SHOULD display the correct messages based on the return values from the php script. For reference (using the above summary):
AJAX should return: Logging in...
AJAX should return: User is already logged in.
AJAX should return: Invalid Username or Password.
The problem is this: If someone logs in correctly and IS NOT already logged in, message 2 appears instead of message 1. (I think that message 1 may appear but it disappears so fast).
I think the culprit is AJAX but unfortunately I'm not as familiar with it as I am with PHP.

Answer 1

I think the problem is with your php code.Your ajax code looks fine
try this
if ($rehash==$dboPW && $user_name == $dboUN && $logged=='Y')
{
echo "alreadyLogged"; exit;
}
elseif ($rehash==$dboPW && $user_name == $dboUN && $logged=='N')
{
}

Answer 2

I think it is the php problem,it occur an error and return the error message. if ajax_login.php does not return "yes" or "no" it will show the second message, whatever it returns.

Answer 3

Just need modify your PHP. try this :
//Log In credentials
// check if post if (isset($_POST)) {
// must initially to use check if on loggin
session_start();
// set variable post
$username = $_POST['user_name'];
$password = $_POST['password']; // change if use sha1 or md5
$rand = $_POST['rand'];
// check query database
$query = mysql_query("SELECT * FROM Users WHERE username='$username' AND password='$password'");
$user = mysql_fetch_array($query);
$row = mysql_num_rows($query);
if ($row > 0) {
if ($user['LOGGED'] == 'Y') {
echo "yes";
$_SESSION['login'] = $username;
$_SESSION['password'] = $rehash;
$loggedUpdate = mysql_query("UPDATE Users SET LOGGED='Y' WHERE username='$user_name'");
exit;
} elseif ($user['LOGGED'] == 'N') { // you can use 'else'
echo "alreadyLogged";
exit;
}
} else {
// invalid value password and username
echo "no";
exit;
} }