Adds rate limiting to the login page

app/classes/ratelimitrer.php

@@ -0,0 +1,91 @@
+<?php
+
+class RateLimiter {
+    private $db;
+    private $maxAttempts = 5;        // Maximum login attempts
+    private $decayMinutes = 15;      // Time window in minutes
+    private $tableName = 'login_attempts';
+
+    public function __construct($database) {
+        $this->db = $database->getConnection();
+        $this->createTableIfNotExists();
+    }
+
+    private function createTableIfNotExists() {
+        $sql = "CREATE TABLE IF NOT EXISTS {$this->tableName} (
+            id INTEGER PRIMARY KEY AUTOINCREMENT,
+            ip_address VARCHAR(45) NOT NULL,
+            username VARCHAR(255) NOT NULL,
+            attempted_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+            INDEX idx_ip_username (ip_address, username)
+        )";
+
+        $this->db->exec($sql);
+    }
+
+    public function attempt($username, $ipAddress) {
+        // Clean old attempts
+        $this->clearOldAttempts();
+
+        // Record this attempt
+        $sql = "INSERT INTO {$this->tableName} (ip_address, username) VALUES (:ip, :username)";
+        $stmt = $this->db->prepare($sql);
+        $stmt->execute([
+            ':ip'		=> $ipAddress,
+            ':username'		=> $username
+        ]);
+
+        // Check if too many attempts
+        return !$this->tooManyAttempts($username, $ipAddress);
+    }
+
+    public function tooManyAttempts($username, $ipAddress) {
+        $sql = "SELECT COUNT(*) as attempts 
+                FROM {$this->tableName} 
+                WHERE ip_address = :ip 
+                AND username = :username 
+                AND attempted_at > datetime('now', '-' || :minutes || ' minutes')";
+
+        $stmt = $this->db->prepare($sql);
+        $stmt->execute([
+            ':ip'		=> $ipAddress,
+            ':username'		=> $username,
+            ':minutes'		=> $this->decayMinutes
+        ]);
+
+        $result = $stmt->fetch(PDO::FETCH_ASSOC);
+        return $result['attempts'] >= $this->maxAttempts;
+    }
+
+    public function clearOldAttempts() {
+        $sql = "DELETE FROM {$this->tableName} 
+                WHERE attempted_at < datetime('now', '-' || :minutes || ' minutes')";
+
+        $stmt = $this->db->prepare($sql);
+        $stmt->execute([
+            ':minutes'		=> $this->decayMinutes
+        ]);
+    }
+
+    public function getRemainingAttempts($username, $ipAddress) {
+        $sql = "SELECT COUNT(*) as attempts 
+                FROM {$this->tableName} 
+                WHERE ip_address = :ip 
+                AND username = :username 
+                AND attempted_at > datetime('now', '-' || :minutes || ' minutes')";
+
+        $stmt = $this->db->prepare($sql);
+        $stmt->execute([
+            ':ip'		=> $ipAddress,
+            ':username'		=> $username,
+            ':minutes'		=> $this->decayMinutes
+        ]);
+
+        $result = $stmt->fetch(PDO::FETCH_ASSOC);
+        return max(0, $this->maxAttempts - $result['attempts']);
+    }
+
+    public function getDecayMinutes() {
+        return $this->decayMinutes;
+    }
+}

app/classes/user.php

@@ -10,6 +10,7 @@ class User {
      * @var PDO|null $db The database connection instance.
      */
     private $db;
+    private $ratelimiter;
 
     /**
      * User constructor.
@@ -19,6 +20,7 @@ class User {
      */
     public function __construct($database) {
         $this->db = $database->getConnection();
+        $this->ratelimiter = new RateLimiter($database);
     }
 
 
@@ -88,17 +90,33 @@ class User {
      * @return bool True if login is successful, false otherwise.
      */
     public function login($username, $password) {
+        // get client IP address
+        $ipAddress = $_SERVER['REMOTE_ADDR'] ?? '0.0.0.0';
+
+        // check rate limiting
+        if (!$this->rateLimiter->attempt($username, $ipAddress)) {
+            $remainingTime = $this->rateLimiter->getDecayMinutes();
+            throw new Exception("Too many login attempts. Please try again in {$remainingTime} minutes.");
+        }
+
         $query = $this->db->prepare("SELECT * FROM users WHERE username = :username");
         $query->bindParam(':username', $username);
         $query->execute();
 
         $user = $query->fetch(PDO::FETCH_ASSOC);
-        if ( $user && password_verify($password, $user['password'])) {
+        if ($user && password_verify($password, $user['password'])) {
             $_SESSION['user_id'] = $user['id'];
             $_SESSION['username'] = $user['username'];
             return true;
+        }
+
+        // Login failed, return remaining attempts info
+        $remainingAttempts = $this->rateLimiter->getRemainingAttempts($username, $ipAddress);
+        if ($remainingAttempts > 0) {
+            throw new Exception("Invalid credentials. {$remainingAttempts} attempts remaining.");
         } else {
-            return false;
+            $remainingTime = $this->rateLimiter->getDecayMinutes();
+            throw new Exception("Too many login attempts. Please try again in {$remainingTime} minutes.");
         }
     }
 

app/pages/login.php

@@ -22,6 +22,7 @@ try {
     $dbWeb = connectDB($config);
 
     if ( $_SERVER['REQUEST_METHOD'] == 'POST' ) {
+        try {
             $username = $_POST['username'];
             $password = $_POST['password'];
 
@@ -66,6 +67,9 @@ try {
                 header('Location: ' . htmlspecialchars($app_root));
                 exit();
             }
+        } catch (Exception $e) {
+            $error = $e->getMessage();
+        }
     }
 } catch (Exception $e) {
     $error = getError('There was an unexpected error. Please try again.', $e->getMessage());