php sessions to authenticate user on login form

Question

I have the following code designed to begin a session and store username/password data, and if nothing is submitted, or no session data stored, redirect to a fail page.

Answer 1

Don't use else section in second if statement.

session_start();

if(isset($_POST['username']) || isset($_POST['password'])) {

    $username = $_POST['username'];

    $password = $_POST['password'];

    $_SESSION['username'] = $username;

    $_SESSION['password'] = $password;

}

if(isset($_SESSION['username']) || isset($_SESSION['password'])){

    $navbar = "1";

    $logindisplay = "0";

    $username = $_SESSION['username'];

    $password = $_SESSION['password'];

}

$authed = auth($username, $password);

if( $authed == "0" ){

    header('Location:http://website.com/fail.php');

}

Answer 2

Here are a few other things, which may or may not help you, by the way :

• Do you have error_reporting on ? (see also)
• Do you have display_errors on ?
• Is session_start the first thing you are doing in your page ? There must be nothing output before
• Are the cookies created on the client-side ?
• header Location indicates the browser it has to go to another page ; it doesn't stop the execution of the PHP script. You might want to (almost always anyway) add "exit" after it.

Answer 3

The solution to my specific problem above

session_start();
if(isset($_POST['username']) || isset($_POST['password'])){
$username = $_POST['username'];
$password = $_POST['password'];
$_SESSION['username'] = $username;
$_SESSION['password'] = $password;
}

if(isset($_SESSION['username']) || isset($_SESSION['password'])){
$navbar = "1";
$logindisplay = "0";
$username = $_SESSION['username'];
$password = $_SESSION['password'];
$authed = auth($username, $password);
if( $authed == "0" ){
header('Location:http://website.com/fail.php');
}
} else {
header('Location:http://website.com/fail.php');
}

Answer 4

Headers are not function calls. They put a directive into the HTTP headers, and the last one to execute is the one which will be processed. So let say if you have something like this

if ($bAuthed)
{
     header("location: login.php");
}

// error case
header("location: error-login.php");

You will always be redirected to error-login.php no matter what happens. Headers are not function calls!

Answer 5

First, don't store the password in the session. It's a bad thing. Second, don't store the username in the session until after you have authenticated.

Try the following:

<?php

session_start();

if (isset($_POST['username']) && isset($_POST['password'])) {
    $username = $_POST['username'];
    $password = $_POST['password'];
    $authed = auth($username, $password);

    if (! $authed) {
        header('Location: http://website.com/fail.php');
    } else {
        $_SESSION['username'] = $username;
    }
}

if (isset($_SESSION['username'])) {
    $navbar = 1;
    $logindisplay = 0;
} else {
    header ('Location: http://website.com/fail.php');
}

Answer 6

what about using this to setup session

session_start();
if( isset($_POST['username']) && isset($_POST['password']) )
{
    if( auth($_POST['username'], $_POST['password']) )
    {
        // auth okay, setup session
        $_SESSION['user'] = $_POST['username'];
        // redirect to required page
        header( "Location: index.php" );
     } else {
        // didn't auth go back to loginform
        header( "Location: loginform.html" );
     }
 } else {
     // username and password not given so go back to login
     header( "Location: loginform.html" );
 }

and at the top of each "secure" page use this code:

session_start();
session_regenerate_id();
if(!isset($_SESSION['user']))      // if there is no valid session
{
    header("Location: loginform.html");
}

this keeps a very small amount of code at the top of each page instead of running the full auth at the top of every page. To logout of the session:

session_start();
unset($_SESSION['user']);
session_destroy();
header("Location: loginform.html");