How to check if a user is logged
I'm pretty new to php and I am trying to figure out how to use sessions to check and see if a user is logged into a website so that they would have authorization to access specific pages.
Is this something that is complicated or is it because I am a noob that I can't figure it out?
Thanks for the help!
Logins are not too complicated, but there are some specific pieces that almost all login processes need.
First, make sure you enable the session variable on all pages that require knowledge of logged-in status by putting this at the beginning of those pages:
session_start();
Next, when the user submits their username and password via the login form, you will typically check their username and password by querying a database containing username and password information, such as MySQL. If the database returns a match, you can then set a session variable to contain that fact. You might also want to include other information:
if (match_found_in_database()) {
$_SESSION['loggedin'] = true;
$_SESSION['username'] = $username; // $username coming from the form, such as $_POST['username']
// something like this is optional, of course
}
Then, on the page that depends on logged-in status, put the following (don't forget the session_start() ):
if (isset($_SESSION['loggedin']) && $_SESSION['loggedin'] == true) {
echo "Welcome to the member's area, " . $_SESSION['username'] . "!";
} else {
echo "Please log in first to see this page.";
}
Those are the basic components. If you need help with the SQL aspect, there are tutorials-a-plenty around the net.
In Login.html:
<html>
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<title>Login Form</title>
</head>
<body>
<section class="container">
<div class="login">
<h1>Login</h1>
<form method="post" action="login.php">
<p><input type="text" name="username" value="" placeholder="Username"></p>
<p><input type="password" name="password" value="" placeholder="Password"></p>
<p class="submit"><input type="submit" name="commit" value="Login"></p>
</form>
</div>
</body>
</html>
In Login.php:
<?php
$host="localhost"; // Host name
$username=""; // Mysql username
$password=""; // Mysql password
$db_name=""; // Database name
$tbl_name="members"; // Table name
// Connect to server and select databse.
mysql_connect("$host", "$username", "$password")or die("cannot connect");
mysql_select_db("$db_name")or die("cannot select DB");
// username and password sent from form
$username=$_POST['username'];
$password=$_POST['password'];
// To protect MySQL injection (more detail about MySQL injection)
$username = stripslashes($username);
$password = stripslashes($password);
$username = mysql_real_escape_string($username);
$password = mysql_real_escape_string($password);
$sql="SELECT * FROM $tbl_name WHERE username='$username' and password='$password'";
$result=mysql_query($sql);
// Mysql_num_row is counting table row
$count=mysql_num_rows($result);
// If result matched $username and $password, table row must be 1 row
if($count==1){
session_start();
$_SESSION['loggedin'] = true;
$_SESSION['username'] = $username;
}
In Member.php:
session_start();
if (isset($_SESSION['loggedin']) && $_SESSION['loggedin'] == true) {
echo "Welcome to the member's area, " . $_SESSION['username'] . "!";
} else {
echo "Please log in first to see this page.";
}
In MYSQL:
CREATE TABLE `members` (
`id` int(4) NOT NULL auto_increment,
`username` varchar(65) NOT NULL default '',
`password` varchar(65) NOT NULL default '',
PRIMARY KEY (`id`)
) TYPE=MyISAM AUTO_INCREMENT=2 ;
In Register.html:
<html>
<head>
<title>Sign-Up</title>
</head>
<body id="body-color">
<div id="Sign-Up">
<fieldset style="width:30%"><legend>Registration Form</legend>
<table border="0">
<form method="POST" action="register.php">
<tr>
<td>UserName</td><td> <input type="text" name="username"></td>
</tr>
<tr>
<td>Password</td><td> <input type="password" name="password"></td>
</tr>
<tr>
<td><input id="button" type="submit" name="submit" value="Sign-Up"></td>
</tr>
</form>
</table>
</fieldset>
</div>
</body>
</html>
In Register.php:
<?php
define('DB_HOST', '');
define('DB_NAME', '');
define('DB_USER','');
define('DB_PASSWORD','');
$con=mysql_connect(DB_HOST,DB_USER,DB_PASSWORD) or die("Failed to connect to MySQL: " . mysql_error());
$db=mysql_select_db(DB_NAME,$con) or die("Failed to connect to MySQL: " . mysql_error());
$userName = $_POST['username'];
$password = $_POST['password'];
$query = "INSERT INTO members (username,password) VALUES ('$userName','$password')";
$data = mysql_query ($query)or die(mysql_error());
if($data)
{
echo "YOUR REGISTRATION IS COMPLETED...";
}
else
{
echo "Unknown Error!"
}
Any page you want to perform session-checks on needs to start with:
session_start();
From there, you check your session array for a variable indicating they are logged in:
if (!$_SESSION["loggedIn"]) redirect_to_login();
Logging them in is nothing more than setting that value:
$_SESSION["loggedIn"] = true;
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