htkcodes/session_example_config.php

## session_example_config.php
<?php

define('DB_USERNAME', 'root');
define('DB_PASSWORD', 'Hoang123');
define('DB_NAME', 'session_example');
define('DB_SERVER', 'localhost');

/* Attempt to connect to MySQL database */
/** @var mysqli $mysqli */
$mysqli = new mysqli(DB_SERVER, DB_USERNAME, DB_PASSWORD, DB_NAME);


// Check connection
if($mysqli->connect_errno){
    die("ERROR: Could not connect. (" .$mysqli->connect_errno. ") " . $mysqli->connect_error);
}

## session_example_database.sql
-- create database
CREATE DATABASE session_example;

-- creating table
CREATE TABLE users (
    id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
    username VARCHAR(50) NOT NULL UNIQUE,
    password VARCHAR(255) NOT NULL,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
);

## session_example_login.php
<?php

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"){

    // Check if username is empty
    if(empty(trim($_POST["username"]))){
        $username_err = 'Please enter username.';
    } else{
        $username = trim($_POST["username"]);
    }

    // Check if password is empty
    if(empty(trim($_POST['password']))){
        $password_err = 'Please enter your password.';
    } else{
        $password = trim($_POST['password']);
    }

    // Validate credentials
    if(empty($username_err) && empty($password_err)){
        // Prepare a select statement
        $sql = "SELECT username, password FROM users WHERE username = ?";

        if($stmt = $mysqli->prepare($sql)){
            // Bind variables to the prepared statement as parameters
            $stmt->bind_param("s", $param_username);

            // Set parameters
            $param_username = $username;

            // Attempt to execute the prepared statement
            if($stmt->execute()){
                // Store result
                $stmt->store_result();

                // Check if username exists, if yes then verify password
                if($stmt->num_rows == 1){
                    // Bind result variables
                    $stmt->bind_result($username, $hashed_password);
                    if($stmt->fetch()){
                        if(password_verify($password, $hashed_password)){
                            /* Password is correct, so start a new session and
                            save the username to the session */
                            session_start();
                            $_SESSION['username'] = $username;
                            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
        $stmt->close();
    }

    // Close connection
    $mysqli->close();
}
?>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Login</title>
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.css">
    <style type="text/css">
        body{ font: 14px sans-serif; }
        .wrapper{ width: 350px; padding: 20px; }
    </style>
</head>
<body>
<div class="wrapper">
    <h2>Login</h2>
    <p>Please fill in your credentials to login.</p>
    <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="post">
        <div class="form-group <?php echo (!empty($username_err)) ? 'has-error' : ''; ?>">
            <label>Username:<sup>*</sup></label>
            <input type="text" name="username"class="form-control" value="<?php echo $username; ?>">
            <span class="help-block"><?php echo $username_err; ?></span>
        </div>
        <div class="form-group <?php echo (!empty($password_err)) ? 'has-error' : ''; ?>">
            <label>Password:<sup>*</sup></label>
            <input type="password" name="password" class="form-control">
            <span class="help-block"><?php echo $password_err; ?></span>
        </div>
        <div class="form-group">
            <input type="submit" class="btn btn-primary" value="Submit">
        </div>
        <p>Don't have an account? <a href="register.php">Sign up now</a>.</p>
    </form>
</div>
</body>
</html>

## session_example_logout.php
<?php

session_start();

// Unset all of the session variables
$_SESSION = array();

// Destroy the session.
session_destroy();

## session_example_readme.md

      
    Raw
  

              session_example_readme.md
            
          
    login system used to demo security in php

  
## session_example_register.php
<?php

require_once 'config.php';

// Define variables and initialize with empty values
$username = $password = $confirm_password = "";
$username_err = $password_err = $confirm_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 a username.";
    } else{
        // Prepare a select statement
        $sql = "SELECT id FROM users WHERE username = ?";

        if($stmt = $mysqli->prepare($sql)){
            // Bind variables to the prepared statement as parameters
            $stmt->bind_param("s", $param_username);

            // Set parameters
            $param_username = trim($_POST["username"]);

            // Attempt to execute the prepared statement
            if($stmt->execute()){
                // store result
                $stmt->store_result();

                if($stmt->num_rows == 1){
                    $username_err = "This username is already taken.";
                } else{
                    $username = trim($_POST["username"]);
                }
            } else{
                echo "Oops! Something went wrong. Please try again later.";
            }
        }

        // Close statement
        $stmt->close();
    }

    // Validate password
    if(empty(trim($_POST['password']))){
        $password_err = "Please enter a password.";
    } elseif(strlen(trim($_POST['password'])) < 6){
        $password_err = "Password must have atleast 6 characters.";
    } else{
        $password = trim($_POST['password']);
    }

    // Validate confirm password
    if(empty(trim($_POST["confirm_password"]))){
        $confirm_password_err = 'Please confirm password.';
    } else{
        $confirm_password = trim($_POST['confirm_password']);
        if($password != $confirm_password){
            $confirm_password_err = 'Password did not match.';
        }
    }

    // Check input errors before inserting in database
    if(empty($username_err) && empty($password_err) && empty($confirm_password_err)){

        // Prepare an insert statement
        $sql = "INSERT INTO users (username, password) VALUES (?, ?)";

        if($stmt = $mysqli->prepare($sql)){
            // Bind variables to the prepared statement as parameters
            $stmt->bind_param("ss", $param_username, $param_password);

            // Set parameters
            $param_username = $username;
            $param_password = password_hash($password, PASSWORD_DEFAULT); // Creates a password hash

            // Attempt to execute the prepared statement
            if($stmt->execute()){
                // Redirect to login page
                header("location: login.php");
            } else{
                echo "Something went wrong. Please try again later.";
            }
        }

        // Close statement
        $stmt->close();
    }

    // Close connection
    $mysqli->close();
}
?>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Sign Up</title>
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.css">
    <style type="text/css">
        body{ font: 14px sans-serif; }
        .wrapper{ width: 350px; padding: 20px; }
    </style>
</head>
<body>
<div class="wrapper">
    <h2>Sign Up</h2>
    <p>Please fill this form to create an account.</p>
    <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="post">
        <div class="form-group <?php echo (!empty($username_err)) ? 'has-error' : ''; ?>">
            <label>Username:<sup>*</sup></label>
            <input type="text" name="username"class="form-control" value="<?php echo $username; ?>">
            <span class="help-block"><?php echo $username_err; ?></span>
        </div>
        <div class="form-group <?php echo (!empty($password_err)) ? 'has-error' : ''; ?>">
            <label>Password:<sup>*</sup></label>
            <input type="password" name="password" class="form-control" value="<?php echo $password; ?>">
            <span class="help-block"><?php echo $password_err; ?></span>
        </div>
        <div class="form-group <?php echo (!empty($confirm_password_err)) ? 'has-error' : ''; ?>">
            <label>Confirm Password:<sup>*</sup></label>
            <input type="password" name="confirm_password" class="form-control" value="<?php echo $confirm_password; ?>">
            <span class="help-block"><?php echo $confirm_password_err; ?></span>
        </div>
        <div class="form-group">
            <input type="submit" class="btn btn-primary" value="Submit">
            <input type="reset" class="btn btn-default" value="Reset">
        </div>
        <p>Already have an account? <a href="login.php">Login here</a>.</p>
    </form>
</div>
</body>
</html>

## session_example_welcome.php
<?php

session_start();

// If session variable is not set it will redirect to login page
if(!isset($_SESSION['username']) || empty($_SESSION['username'])){
    header("location: login.php");
    exit;
}
	<?php

	define('DB_USERNAME', 'root');
	define('DB_PASSWORD', 'Hoang123');
	define('DB_NAME', 'session_example');
	define('DB_SERVER', 'localhost');

	/* Attempt to connect to MySQL database */
	/** @var mysqli $mysqli */
	$mysqli = new mysqli(DB_SERVER, DB_USERNAME, DB_PASSWORD, DB_NAME);


	// Check connection
	if($mysqli->connect_errno){
	die("ERROR: Could not connect. (" .$mysqli->connect_errno. ") " . $mysqli->connect_error);
	}
	-- create database
	CREATE DATABASE session_example;

	-- creating table
	CREATE TABLE users (
	id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
	username VARCHAR(50) NOT NULL UNIQUE,
	password VARCHAR(255) NOT NULL,
	created_at DATETIME DEFAULT CURRENT_TIMESTAMP
	);
	<?php

	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"){

	// Check if username is empty
	if(empty(trim($_POST["username"]))){
	$username_err = 'Please enter username.';
	} else{
	$username = trim($_POST["username"]);
	}

	// Check if password is empty
	if(empty(trim($_POST['password']))){
	$password_err = 'Please enter your password.';
	} else{
	$password = trim($_POST['password']);
	}

	// Validate credentials
	if(empty($username_err) && empty($password_err)){
	// Prepare a select statement
	$sql = "SELECT username, password FROM users WHERE username = ?";

	if($stmt = $mysqli->prepare($sql)){
	// Bind variables to the prepared statement as parameters
	$stmt->bind_param("s", $param_username);

	// Set parameters
	$param_username = $username;

	// Attempt to execute the prepared statement
	if($stmt->execute()){
	// Store result
	$stmt->store_result();

	// Check if username exists, if yes then verify password
	if($stmt->num_rows == 1){
	// Bind result variables
	$stmt->bind_result($username, $hashed_password);
	if($stmt->fetch()){
	if(password_verify($password, $hashed_password)){
	/* Password is correct, so start a new session and
	save the username to the session */
	session_start();
	$_SESSION['username'] = $username;
	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
	$stmt->close();
	}

	// Close connection
	$mysqli->close();
	}
	?>

	<!DOCTYPE html>
	<html lang="en">
	<head>
	<meta charset="UTF-8">
	<title>Login</title>
	<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.css">
	<style type="text/css">
	body{ font: 14px sans-serif; }
	.wrapper{ width: 350px; padding: 20px; }
	</style>
	</head>
	<body>
	<div class="wrapper">
	<h2>Login</h2>
	<p>Please fill in your credentials to login.</p>
	<form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="post">
	<div class="form-group <?php echo (!empty($username_err)) ? 'has-error' : ''; ?>">
	<label>Username:<sup>*</sup></label>
	<input type="text" name="username"class="form-control" value="<?php echo $username; ?>">
	<span class="help-block"><?php echo $username_err; ?></span>
	</div>
	<div class="form-group <?php echo (!empty($password_err)) ? 'has-error' : ''; ?>">
	<label>Password:<sup>*</sup></label>
	<input type="password" name="password" class="form-control">
	<span class="help-block"><?php echo $password_err; ?></span>
	</div>
	<div class="form-group">
	<input type="submit" class="btn btn-primary" value="Submit">
	</div>
	<p>Don't have an account? <a href="register.php">Sign up now</a>.</p>
	</form>
	</div>
	</body>
	</html>
	<?php

	session_start();

	// Unset all of the session variables
	$_SESSION = array();

	// Destroy the session.
	session_destroy();
	<?php

	session_start();

	// If session variable is not set it will redirect to login page
	if(!isset($_SESSION['username']) \|\| empty($_SESSION['username'])){
	header("location: login.php");
	exit;
	}