Solved

Reverse asset logic not working

Posted on 2016-10-04
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33 Views
Last Modified: 2016-10-05
If I do this:

if(isset($_SESSION['sessionID']) || isset($_COOKIE['userID'])) {

echo "Welcome";

} else {

header("location:login.php");
exit;
}

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then it works fine. If no session or cookie is set then the user is redirected. I don't want to do it this way because I don't actually want to do anything if the user is logged in, I only want to worry about if the cookie or session isn't set so I can redirect them. I tried to reverse the logic like this:

if(!isset($_SESSION['sessionID']) || !isset($_COOKIE['userID'])) {
	
	header("location:login.php");
	exit;
	
	}

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but it doesn't work. I THINK it is saying, if no session is found OR if no cookie is found, redirect. If I enter correct login details it doesn't log me in, just sends me back to the login page.
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Question by:Black Sulfur
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11 Comments
 
LVL 108

Expert Comment

by:Ray Paseur
Comment Utility
Not sure whether this is the problem or not, but isset() may be too sensitive a test.  You might want to use empty() instead.  A field can be TRUE for isset() but FALSE for empty(), according to the man pages.  

The best approach might be to follow the design pattern in this article.
https://www.experts-exchange.com/articles/2391/PHP-Client-Registration-Login-Logout-and-Easy-Access-Control.html
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Author Comment

by:Black Sulfur
Comment Utility
Sorry, I did type isset but I noticed when typing it now that spell check changed it to asset, haha!

Thanks, Ray. I have been reading that from your previous post on my last question.

I think this is your code which is doing a similar thing:

function access_control($test=FALSE)
{
    // REMEMBER HOW WE GOT HERE
    $_SESSION["entry_uri"] = $_SERVER["REQUEST_URI"];

    // IF THE UID IS SET, WE ARE LOGGED IN
    if (isset($_SESSION["uid"])) return $_SESSION["uid"];

    // IF WE ARE NOT LOGGED IN - RESPOND TO THE TEST REQUEST
    if ($test) return FALSE;

    // IF THIS IS NOT A TEST, REDIRECT TO CALL FOR A LOGIN
    header("Location: RAY_EE_login.php");
    exit;
}

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But then you also have this going on:

if (!isset($_SESSION["uid"]))
{

    // DETERMINE IF THE CLIENT IS ALREADY LOGGED IN BECAUSE OF "REMEMBER ME" FEATURE
    if (isset($_COOKIE["uuk"]))
    {

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0
 

Author Comment

by:Black Sulfur
Comment Utility
PS. I did try empty and I got the same result:

if(empty($_SESSION['sessionID']) || empty($_COOKIE['userID'])) {
	
	header("location:login.php");
	exit;
	
	}

Open in new window

0
 
LVL 108

Assisted Solution

by:Ray Paseur
Ray Paseur earned 150 total points
Comment Utility
The general logic I follow goes like this...

1. Test the session value.  If it's set, the client is logged in.
2. Test the cookie value.  If it's set, look up the client information and set the session value.
3. Else, the client is not logged in.

In this logic, the session is the canonical indicator of whether the client is logged in.  The cookie is used only to set the session value.

Consider this if statement:
if(empty($_SESSION['sessionID']) || empty($_COOKIE['userID'])) {
	
	header("location:login.php");
	exit;
	
	}

Open in new window

This is saying that if either the session or cookie is empty(), return TRUE.  In other words, a session alone is not going to allow the client to be logged in; there must be a separate cookie, too.  That's probably not what you want.
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LVL 82

Accepted Solution

by:
Dave Baldwin earned 350 total points
Comment Utility
I think you want to use 'AND' logic to test for both of them being empty.
if(empty($_SESSION['sessionID']) && empty($_COOKIE['userID'])) {

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Author Comment

by:Black Sulfur
Comment Utility
Ah, can't believe I didn't see that as that seems really obvious now that you pointed it out!
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Author Comment

by:Black Sulfur
Comment Utility
Regarding this...

  $_SESSION["entry_uri"] = $_SERVER["REQUEST_URI"];

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Would you only use this as an extra security layer with a session based login because then you will always have to come from the login page to get to your account area? But it would not  work with cookies because I might just open my browser and go directly to the account page and completely bypass the login page?
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LVL 82

Expert Comment

by:Dave Baldwin
Comment Utility
$_SERVER["REQUEST_URI"] is the page you are currently on.  If you want to see where you came from, use $_SERVER["HTTP_REFERER"].  $_SERVER["HTTP_REFERER"] is Not set if you went directly to the page instead of from another page.  And since it can be spoofed, you should not rely only on it.  I do use it on a lot of pages though.  If they can't get that right, they shouldn't be there anyway.

http://php.net/manual/en/reserved.variables.server.php
1
 
LVL 108

Expert Comment

by:Ray Paseur
Comment Utility
This is a complicated issue that produces a simple, intuitive, "good-UX" result.  If you read the article and still have questions about why we use that, please post a new question and I'll try to explain.
$_SESSION["entry_uri"] = $_SERVER["REQUEST_URI"];

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Author Comment

by:Black Sulfur
Comment Utility
Thanks guys. Ray, I have read the part of the article which explains it and I have looked at the code but I still can't understand why exactly you do it. I initially thought that maybe it was for if you are browsing a site and for example find a page with a particular product or article and you want to make a purchase, then if you login you will stay on that page instead of being taken to your dashboard and you have to hunt for that page again. But that probably isn't it. I will open a related question.
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Expert Comment

by:Ray Paseur
Comment Utility
I posted in the related question.  HTH, ~Ray
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