How to check if a user is logged in - php

Question

I have built a login php form for an internal website I'm building for our intranet. I am going to combine a few different websites together under one login system. I want to see how I could check if a user is logged in if they visit one of the url's directly and if they're not logged in then redirect them to the login page then after successfully logging in redirect back to the initial page.
I have logged their username and password into a cookie. I know this isn't secure, but again this is just an in house website on the companies intranet. So I don't need much security. The log in system is to just track what each user is doing.
Here's my login code, but now I need to figure out how to check if a user is logged in or not on separate web pages.
//get info from login form
if(isset($_POST['login'])) {
$username = $_POST['username'];
$password = $_POST['password'];
$rememberme = $_POST['rememberme'];
$username = mysqli_real_escape_string($connection, $username);
$password = mysqli_real_escape_string($connection, $password);
//query users table
$query = "SELECT * FROM users WHERE username = '{$username}' ";
$select_user_query = mysqli_query($connection, $query);
if(!$select_user_query) {
die("Query failed" . mysqli_error($connection));
}
//loop through user info and assigning to variables
while($row = mysqli_fetch_array($select_user_query)) {
$db_id = $row['user_id'];
$db_username = $row['username'];
$db_password = $row['user_password'];
$db_firstname = $row['user_firstname'];
$db_lastname = $row['user_lastname'];
$db_role = $row['user_role'];
}
//validate username and password
if($username === $db_username && $password === $db_password) {
//create cookie to remember user
if(isset($rememberme)) {
//set cookie to last one year
setcookie('username', $_POST['username'], time()+60*60*24*365, '/', 'localhost');
setcookie('password', md5($_POST['user_password']), time()+60*60*24*365, '/', 'localhost');
} else {
//cookie expires when browser closes
setcookie('username', $_POST['username'], false, '/', 'localhost');
setcookie('password', md5($_POST['user_password']), false, '/', 'localhost');
}
//if user exists send to dashboard
$_SESSION['username'] = $db_username;
$_SESSION['user_firstname'] = $db_firstname;
$_SESSION['user_lastname'] = $db_lastname;
$_SESSION['user_role'] = $db_role;
header("Location: ../dashboard.php ");
} else {
header("Location: ../index.php");
}
}

Answer 1

Here is how to check if a user is logged in and then redirect them to the page they first visited.
First check to see if a user is logged in:
<?php
session_start();
if(!(isset($_SESSION['username'])))
{
header("Location: index.php");
}
?>
Then include that file in all of your web pages you will be using. Also, create a session for the URL. This will go at the top of your page:
<?php include "includes/login-check.php"; ?>
<?php $_SESSION['url'] = $_SERVER['REQUEST_URI']; ?>
<?php ob_start(); ?>
Then right in the body of the HTML add this:
<input type="hidden" name="redirurl" value="<? echo $_SERVER['HTTP_REFERER']; ?>" />
Then within your login file check for the URL session:
//check to see what page user first visited
if(isset($_SESSION['url'])) {
$url = $_SESSION['url'];
} else {
$url = "../index.php";
}
//redirect user to page they initially visited
header("Location: $url");
That should fully answer your question.

Answer 2

Create a file which you should include at the top in every file of your system and add the following code
session_start();
if(!(isset($_SESSION['username'])))
{
header("Location:login.php")
}