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  1. <?php
  2. // register_demo_w3.php
  3. // Single-file demo suitable for W3Schools PHP compiler.
  4. // Intent: Demonstrate secure registration flow (CSRF, validation, password_hash) in an environment
  5. //         where persistent DB is unavailable. Data is kept in session only for demonstration.
  6.  
  7. session_start();
  8.  
  9. // CSRF token for the session
  10. if (empty($_SESSION['csrf_token'])) {
  11.     $_SESSION['csrf_token'] = bin2hex(random_bytes(16));
  12. }
  13. $csrf = $_SESSION['csrf_token'];
  14.  
  15. $errors = [];
  16. $success = null;
  17.  
  18. // Handle POST submission in same file
  19. if ($_SERVER['REQUEST_METHOD'] === 'POST') {
  20.     $posted_csrf = $_POST['csrf'] ?? '';
  21.     if (empty($posted_csrf) || !hash_equals($csrf, $posted_csrf)) {
  22.         $errors[] = 'Invalid CSRF token. Reload and try again.';
  23.     } else {
  24.         // Normalize inputs
  25.         $username = trim((string)($_POST['username'] ?? ''));
  26.         $email    = trim((string)($_POST['email'] ?? ''));
  27.         $password = (string)($_POST['password'] ?? '');
  28.         $confirm  = (string)($_POST['confirm_password'] ?? '');
  29.  
  30.         if ($username === '') $errors[] = 'Username is required.';
  31.         if ($email === '')    $errors[] = 'Email is required.';
  32.         if ($password === '') $errors[] = 'Password is required.';
  33.         if ($confirm === '')  $errors[] = 'Please confirm password.';
  34.  
  35.         if ($email !== '' && !filter_var($email, FILTER_VALIDATE_EMAIL)) {
  36.             $errors[] = 'Invalid email format.';
  37.         }
  38.  
  39.         if (mb_strlen($username) < 3 || mb_strlen($username) > 50) {
  40.             $errors[] = 'Username must be 3–50 characters.';
  41.         }
  42.  
  43.         // Password policy
  44.         $pw_ok = true;
  45.         if (strlen($password) < 8) $pw_ok = false;
  46.         if (!preg_match('/[A-Z]/', $password)) $pw_ok = false;
  47.         if (!preg_match('/[a-z]/', $password)) $pw_ok = false;
  48.         if (!preg_match('/[0-9]/', $password)) $pw_ok = false;
  49.         if (!preg_match('/[\W_]/', $password)) $pw_ok = false;
  50.         if (!$pw_ok) $errors[] = 'Password must be 8+ chars and include upper, lower, number and symbol.';
  51.  
  52.         if ($password !== $confirm) $errors[] = 'Passwords do not match.';
  53.  
  54.         // If valid, "save" into session demo storage
  55.         if (empty($errors)) {
  56.             if (!isset($_SESSION['demo_users'])) $_SESSION['demo_users'] = [];
  57.  
  58.             $email_norm = strtolower($email);
  59.             foreach ($_SESSION['demo_users'] as $u) {
  60.                 if ($u['email'] === $email_norm) {
  61.                     $errors[] = 'An account with this email already exists (demo).';
  62.                     break;
  63.                 }
  64.             }
  65.             if (empty($errors)) {
  66.                 $hash = password_hash($password, PASSWORD_DEFAULT);
  67.                 $_SESSION['demo_users'][] = [
  68.                     'id' => uniqid('u', true),
  69.                     'username' => $username,
  70.                     'email' => $email_norm,
  71.                     'password_hash' => $hash,
  72.                     'created_at' => date(DATE_ATOM)
  73.                 ];
  74.                 $success = 'Registration successful (demo users saved to session).';
  75.                 // rotate token to reduce replay risk
  76.                 $_SESSION['csrf_token'] = bin2hex(random_bytes(16));
  77.                 $csrf = $_SESSION['csrf_token'];
  78.                 // clear posted values for sticky UI
  79.                 $_POST = [];
  80.             }
  81.         }
  82.     }
  83. }
  84.  
  85. // Helper
  86. function h($s){ return htmlspecialchars((string)$s, ENT_QUOTES, 'UTF-8'); }
  87. ?>
  88. <!doctype html>
  89. <html lang="en">
  90. <head><meta charset="utf-8"><title>Register Demo</title></head>
  91. <body>
  92.   <h1>Register (W3Schools Demo)</h1>
  93.  
  94.   <?php if (!empty($errors)): ?>
  95.     <div style="color:darkred;"><ul><?php foreach ($errors as $e): ?><li><?php echo h($e); ?></li><?php endforeach; ?></ul></div>
  96.   <?php endif; ?>
  97.  
  98.   <?php if ($success): ?>
  99.     <div style="color:green"><?php echo h($success); ?></div>
  100.   <?php endif; ?>
  101.  
  102.   <form method="post" action="">
  103.     <input type="hidden" name="csrf" value="<?php echo h($csrf); ?>">
  104.     <label>Username:<br><input type="text" name="username" required maxlength="50" value="<?php echo isset($_POST['username'])?h($_POST['username']):''; ?>"></label><br><br>
  105.     <label>Email:<br><input type="email" name="email" required value="<?php echo isset($_POST['email'])?h($_POST['email']):''; ?>"></label><br><br>
  106.     <label>Password:<br><input type="password" name="password" required></label><br><br>
  107.     <label>Confirm Password:<br><input type="password" name="confirm_password" required></label><br><br>
  108.     <button type="submit">Register</button>
  109.   </form>
  110.  
  111.   <hr>
  112.   <h2>Demo: Registered users (session)</h2>
  113.   <?php if (!empty($_SESSION['demo_users'])): ?>
  114.     <ul>
  115.       <?php foreach ($_SESSION['demo_users'] as $u): ?>
  116.         <li><?php echo h($u['username']); ?> — <?php echo h($u['email']); ?> — <?php echo h($u['created_at']); ?></li>
  117.       <?php endforeach; ?>
  118.     </ul>
  119.   <?php else: ?>
  120.     <p>No demo users yet.</p>
  121.   <?php endif; ?>
  122.  
  123.   <p><small>Note: This demo stores users in session only. Use a database and stronger infrastructure for production.</small></p>
  124. </body>
  125. </html>
  126.  
Success #stdin #stdout #stderr 0.03s 26208KB
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<!doctype html>
<html lang="en">
<head><meta charset="utf-8"><title>Register Demo</title></head>
<body>
  <h1>Register (W3Schools Demo)</h1>

  
  
  <form method="post" action="">
    <input type="hidden" name="csrf" value="dc17516decdcee5b221bbbfca1cd80ea">
    <label>Username:<br><input type="text" name="username" required maxlength="50" value=""></label><br><br>
    <label>Email:<br><input type="email" name="email" required value=""></label><br><br>
    <label>Password:<br><input type="password" name="password" required></label><br><br>
    <label>Confirm Password:<br><input type="password" name="confirm_password" required></label><br><br>
    <button type="submit">Register</button>
  </form>

  <hr>
  <h2>Demo: Registered users (session)</h2>
      <p>No demo users yet.</p>
  
  <p><small>Note: This demo stores users in session only. Use a database and stronger infrastructure for production.</small></p>
</body>
</html>
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PHP Notice:  Undefined index: REQUEST_METHOD in /home/Ssc5S6/prog.php on line 19
https://ideone.com/DJYsjF
language:
PHP (php 7.3.5)
created:
4 days ago
visibility:
public

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