Merge pull request #80 from nicolgit/main

Throttling

Author: nicolgit

firewall-mon-api/backend.cs

@@ -0,0 +1,87 @@
+using System.Collections.Concurrent;
+using System.Net;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.Azure.Functions.Worker;
+using Microsoft.Extensions.Logging;
+
+namespace firewallmon.function;
+
+class RequestLog
+    {
+        public List<DateTime> Requests { get; } = new();
+    }
+
+
+public class Backend
+{    
+    private static readonly ConcurrentDictionary<string, RequestLog> IpLogs = new();
+
+    private readonly ILogger<Backend> _logger;
+
+    private int ThrottlingInterval = int.TryParse(Environment.GetEnvironmentVariable("aiao_throttling_window"), out var interval) ? interval : 0; // minutes
+    private int ThrottlingRequests = int.TryParse(Environment.GetEnvironmentVariable("aiao_throttling_calls"), out var requests) ? requests : 0; // max requests in the interval
+    private bool IsThrottlingEnabled => ThrottlingInterval > 0 && ThrottlingRequests > 0;
+
+    private bool ImplementThrottling(HttpRequest req)
+    {
+        if (!IsThrottlingEnabled)
+        {
+            return false;
+        }
+
+        string ip = req.HttpContext.Connection.RemoteIpAddress?.ToString() ?? "unknown";
+
+        var now = DateTime.UtcNow;
+        var logEntry = IpLogs.GetOrAdd(ip, _ => new RequestLog());
+
+        lock (logEntry)
+        {
+            logEntry.Requests.RemoveAll(t => (now - t).TotalMinutes > ThrottlingInterval);
+
+            int count = logEntry.Requests.Count;
+            if (count >= ThrottlingRequests)
+            {
+                // Log the throttling event
+                _logger.LogError($"Throttling request from IP: {ip}");
+                return true;
+            }
+            else
+            {
+                _logger.LogInformation($"Request {count} from IP {ip}.");
+            }
+
+            logEntry.Requests.Add(now);
+        }
+
+        return false;
+    }
+
+    public Backend(ILogger<Backend> logger)
+    {
+        _logger = logger;
+    }
+
+    [Function("helloWorld")]
+    public IActionResult Run([HttpTrigger(AuthorizationLevel.Anonymous, "get", "post")] HttpRequest req)
+    {
+        if (ImplementThrottling(req))
+        {
+            return new ContentResult
+            {
+                StatusCode = StatusCodes.Status429TooManyRequests,
+                Content = "Too many requests. Please try again later."
+            };
+        }   
+
+        string? author = "";
+
+        author = Environment.GetEnvironmentVariable("author");
+        if (string.IsNullOrEmpty(author))
+        {
+            author = "unknown";
+        }        
+
+        return new OkObjectResult($"Hello from the other side... of the endpoint.\r\nbackend owned by {author}.\r\n");
+    }
+}

firewall-mon-api/helloWorld.cs

@@ -3,6 +3,8 @@
   "Values": {
     "AzureWebJobsStorage": "",
     "FUNCTIONS_WORKER_RUNTIME": "dotnet-isolated",
-    "author" : "john john"
+    "author" : "john john",
+    "aiao_throttling_window" : "10",
+    "aiao_throttling_calls" : "3"
   }
-}
+}