<?php
// Initialize the session
session_start();
// Check if the user is already logged in, if yes then redirect him to welcome page
if(isset($_SESSION["loggedin"]) && $_SESSION["loggedin"] === true){
header("location: welcome.php");
exit;
}
// Include config file
require_once "config.php";
// Define variables and initialize with empty values
$username = $password = "";
$username_err = $password_err = "";
// Processing form data when form is submitted
if($_SERVER["REQUEST_METHOD"] == "POST"){
// Validate username
if(empty(trim($_POST["username"]))){
$username_err = "Please enter username.";
} else{
if (preg_match("[a-zA-Z0-9_]+", $_POST["username"]) == 1) {
$username_err = "Invalid username.";
}
else {
$username = trim($_POST["username"]);
}
}
// Validated password
if(empty(trim($_POST["password"]))){
$password_err = "Please enter your password.";
} else{
if (preg_match("[a-zA-Z0-9_]+", $_POST["password"]) == 1) {
$username_err = "Invalid password.";
}
else {
$password = trim($_POST["password"]);
}
}
// Validate credentials
if(empty($username_err) && empty($password_err)){
// Prepare a select statement
$sql = "SELECT id, username, password FROM users WHERE username = ?";
if($stmt = mysqli_prepare($link, $sql)){
// Bind variables to the prepared statement as parameters
mysqli_stmt_bind_param($stmt, "s", $param_username);
// Set parameters
$param_username = $username;
// Attempt to execute the prepared statement
if(mysqli_stmt_execute($stmt)){
// Store result
mysqli_stmt_store_result($stmt);
// Check if username exists, if yes then verify password
if(mysqli_stmt_num_rows($stmt) == 1){
// Bind result variables
mysqli_stmt_bind_result($stmt, $id, $username, $hashed_password);
if(mysqli_stmt_fetch($stmt)){
if(password_verify($password, $hashed_password)){
// Password is correct, so start a new session
session_start();
// Store data in session variables
$_SESSION["loggedin"] = true;
$_SESSION["id"] = $id;
$_SESSION["username"] = $username;
// Redirect user to welcome page
header("location: welcome.php");
} else{
// Display an error message if password is not valid
$password_err = "The password you entered was not valid.";
}
}
} else{
// Display an error message if username doesn't exist
$username_err = "No account found with that username.";
}
} else{
echo "Oops! Something went wrong. Please try again later.";
}
// Close statement
mysqli_stmt_close($stmt);
}
}
// Close connection
mysqli_close($link);
}
?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>CSTIMS Login</title>
<link rel="stylesheet" type="text/css" href="/style.css">
</head>
<body>
<header><a href="https://arf20.com/">
<img src="arfnet_logo.png" width="64"><span class="title"><strong>ARFNET</strong></span>
</a></header>
<hr>
<main>
<div class="wrapper">
<h2>CSTIMS Login</h2>
<form action="/login.php" method="post">
<div class="form-group row <?php echo (!empty($username_err)) ? 'has-error' : ''; ?>">
<div class="column"><label>Username</label></div>
<div class="column"><input type="text" name="username" class="form-control" pattern="[a-zA-Z0-9_]+" value="<?php echo $username; ?>"></div>
<span class="help-block"><?php echo $username_err; ?></span>
</div>
<div class="form-group row <?php echo (!empty($password_err)) ? 'has-error' : ''; ?>">
<div class="column"><label>Password</label></div>
<div class="column"><input type="password" name="password" pattern="[a-zA-Z0-9_]+" class="form-control"></div>
<span class="help-block"><?php echo $password_err; ?></span>
</div>
<div class="form-group">
<input type="submit" class="btn btn-primary" value="Login">
</div>
<p>Don't have an account? <a href="register.php">Sign up now</a>.</p>
</form>
</div>
</main>
</body>
</html>