Add rate limit for login APIs. Credit to ChatGPT

ThuInfoWeb/LoginAttemptService.cs

@@ -0,0 +1,39 @@
+public class LoginAttemptService
+{
+    private static readonly Dictionary<string, (int Attempts, DateTime LastAttempt)> _loginAttempts = new();
+
+    private const int MaxAttempts = 5; // Max allowed attempts
+    private readonly TimeSpan _blockDuration = TimeSpan.FromMinutes(15); // Block duration
+
+    public bool IsBlocked(string username)
+    {
+        if (_loginAttempts.TryGetValue(username, out var attemptData))
+        {
+            if (attemptData.Attempts >= MaxAttempts)
+            {
+                if (DateTime.UtcNow < attemptData.LastAttempt.Add(_blockDuration))
+                {
+                    return true; // Blocked
+                }
+                else
+                {
+                    // Reset attempts after block duration
+                    _loginAttempts.Remove(username);
+                }
+            }
+        }
+        return false;
+    }
+
+    public void RecordAttempt(string username)
+    {
+        if (_loginAttempts.ContainsKey(username))
+        {
+            _loginAttempts[username] = (_loginAttempts[username].Attempts + 1, DateTime.UtcNow);
+        }
+        else
+        {
+            _loginAttempts[username] = (1, DateTime.UtcNow);
+        }
+    }
+}