[php] Redirecting to previous page after login? PHP

I've been searching for a solution but it's seem I can't get it right, no matter what I try.

After successful login, the user should be redirected to the page he came from, let's say he's been browsing a post and wants to log in so he can leave a comment, so he should be redirected to the post he was browsing. So here is what I have:

login.php shows the login form:

<form method="post" action="login-check.php">
... //input for username and password
</form>

The login-check.php checks if the username and pass are entered, does the user exist, or if he's already logged in, and a p parameter is sent to login.php:

<?php
session_start();
if((empty($username) OR empty($password) AND !isset($_SESSION['id_login']))) {
   header("Location:login.php?p=1");
   exit();
}
elseif (!user_exists($username,$password) AND !isset($_SESSION['id_login'])) {
   header("Location:login.php?p=2");
   exit();
}
elseif(isset($_SESSION['id_login'])) {
   header("Location:login.php?p=3");
   exit();
}
?>

then parameter p is sent back to login.php and displays the according message:

<?php
if(isset($_GET['p'])) {
  $p = $_GET["p"];

  if($p=="1")
    echo "<p class=\"red\">You didn't fill the form.</p><br></br>";
  if($p=="2")
    echo "<p class=\"red\">User exists.</p><br></br>";
  if($p=="3")
    header("Location: index.php");
}
?>

BUT, instead of going to index.php after successful login, it should go to the page the user has previously been. I've tried in different ways but ether it doesn't work at all or it returns to login.php. It doesn't need to be super safe, because I'm doing this for a school project.
ALSO, I consider myself pretty novice, so please have patience :D

You can use session to to store the current page on which you want to return after login and that will work for other pages if you maintain session properly. It is very useful technique as you can develop your breadcrumb using it.

Construct the form action such that it 'remembers', or persists, the previous page by writing out a returnurl=value query string key/value pair to the URL - this can be passed from any page that redirects to login.

You should probably place the url to redirect to in a POST variable.

I think you might need the $_SERVER['REQUEST_URI'];

if(isset($_SESSION['id_login'])) {
  header("Location:" . $_SERVER['REQUEST_URI']);
}

That should take the url they're at and redirect them them after a successful login.

Use hidden input in your login page. Like:

<input name="location" value="<?php if(!empty($_SERVER['HTTP_REFERER'])) echo $_SERVER['HTTP_REFERER']; else echo 'products.php'; ?>" type="text" style="display: none;" />

Since the login page is a separate page, I am assuming that you want to redirect to the page that the user reached the login page from.

$_SERVER['REQUEST_URI'] will simply hold the current page. What you want to do is use $_SERVER['HTTP_REFERER']

So save the HTTP_REFERER in a hidden element on your form <input type="hidden" name="referer" value="<?= $_SERVER['HTTP_REFERER'] ?>" /> but keep in mind that in the PHP that processes the form you will need some logic that redirects back to the login page if login fails but also to check that the referer is actually your website, if it isn't, then redirect back to the homepage.

use something like

$_SERVER['HTTP_REFERER'];

And if it's a successful login, display a link saying "Click here to go back" and a link to the referrer, and when the page loads, use some javascript to automatically load that page (don't use back() or whatever that function is as it won't re-load the page and it'll appear like the user never logged in.

I have created a function to store URL of previous page

//functions.php

function set_previous_page_url(){

    $current_url = (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] === 'on' ? "https" : "http") . "://{$_SERVER['HTTP_HOST']}{$_SERVER['REQUEST_URI']}"; 
    $previous_url = $_SERVER['HTTP_REFERER'];
    if (!($current_url === $previous_url)){
        $_SESSION['redirect_url'] = $previous_url;
    }
    if(isset($_SESSION['redirect_url'])){
        $url = $_SESSION['redirect_url'];
        return $url;

    } else {
        $url = "index.php";
        return $url;
    }
}

And call this function in login.php

// login.php

<?php
// set previous page url to redirect after login
$url = set_previous_page_url();

if(ifItIsMethod('post')){
    if(isset($_POST['username']) && isset($_POST['password'])){
        if (login_user($_POST['username'], $_POST['password'])) {
            redirect($url);
            //unset session defined in set_previous_page_url() function
            if(isset($_SESSION['redirect_url'])){
                unset($_SESSION['redirect_url']);
            }

        } 
    }
}
?>

You should try something like $_SERVER['HTTP_REFERER'].

You can save a page using php, like this:

$_SESSION['current_page'] = $_SERVER['REQUEST_URI']

And return to the page with:

header("Location: ". $_SESSION['current_page'])

you can use this:

$refererpage = $_SERVER['HTTP_REFERER']; //get referer stored in a variable
if (strpos($refererpage, $_SERVER['SERVER_NAME']) == TRUE) { //if the start position of the referer and the server name is equal
    $refvar= $refererpage; //create a mew variable to be used to locate header
} else { //if referer's address is not the same as server name
    $refvar= "index.php"; //set the variable to another direction for this request
}

and add the header where ever u want as:

header('location: '. $refvr); //set the header location to the referer varaible

You should first get user refer page in a variable using $_SERVER['HTTP_REFERER']; in your login page.

LIKE:

<?php 
    session_start();
    $refPage = $_SERVER['HTTP_REFERER']; 
?>

And now when the user clicks to Login then change header location to user refer page

LIKE:

<?php 
if(isset($_POST[login])){
    session_start();
    header('location:' . $refPage);
}
?>

And in this time you should first check that user refers page empty or not because your user can visit direct your login page then your $refPage variable will be empty so after Click to Login page stays here

LIKE:

<?php
if(isset($_POST[login])){
    session_start();
    $refPage = $_SERVER['HTTP_REFERER'];  // get reffer page url
    if(empty($refPage)){ 
        header('location: yourredirectpage'); // if ref page is empty then set default redirect page.
    }else{
        header('location:' . $refPage); // or if ref page in not empty then redirect page to reffer page
    }
}
?>

Or you can use input type hidden where you can set value $_SERVER['HTTP_REFERER'];

LIKE:

<input type="hidden" name="refPage" value="<?php echo $_SERVER['HTTP_REFERER']; ?>">

And when a user clicks to Login then you can get the refPage value and redirect the previous page. And you should also check empty refer page. Because your user can visit direct your login page.

Thank you.

Another way, using SESSION

Assign current URL to session (use it on every page)

$_SESSION['rdrurl'] = $_SERVER['REQUEST_URI'];

and in your login page, use

if(isset($_SESSION['rdrurl']))
header('location: '.$_SESSION['rdrurl']);
else
header('location: http://example.com');

@philipobenito's answer worked best for me.
I first created a hidden input that contain the user's HTTP referer

<input type="hidden" name="referer" value="<?= $_SERVER['HTTP_REFERER'] ?>" />

and after a successful login i redirected the users to whatever value was stored in that hidden input

$_POST = filter_input_array(INPUT_POST, FILTER_SANITIZE_STRING);
if(!empty($_POST['referer'])){
    header('Location: '.$_POST['referer']);
}
else{
    header('Location: members.php'); //members.php is a page used to send a user to their profile page.
}
exit;

how about this :: javascript+php

echo "<script language=javascript> javascript:history.back();</script>";

it will work same as the previous button in your browser

You can try

echo "<SCRIPT>alert(\"Login Successful Redirecting To Previous Page \");history.go(-2)</SCRIPT>";

Or

echo "<SCRIPT>alert(\"Login Successful Redirecting To Previous Page \");history.go(-1)</SCRIPT>";

When user gets to the login page use this to see where is come from

$_SERVER['HTTP_REFERER']

Then set this value into the session, and when he is authenticated use url from the session to redirect him back. But you should do some checking before, if the url is your site. Maybe he come from another site directly to login :)