improve voice chat security by implementing join validation

LarpixServer/Program.cs

@@ -13,6 +13,29 @@ public class Program
     public static async Task Main(string[] args)
     {
         await LoadEnv();
+
+        // Voice ticket sweeper: issued tickets live for 60s; remove expired
+        // ones a minute later so nothing lingers in memory. Also prunes stale
+        // per-IP auth rate-limit counters (they are written pre-HMAC-check,
+        // so without pruning any scanner could grow the map forever).
+        _ = Task.Run(async () =>
+        {
+            while (true)
+            {
+                await Task.Delay(30000);
+                long cutoff = DateTimeOffset.UtcNow.ToUnixTimeSeconds() - 120;
+                foreach (var entry in VoiceTickets)
+                {
+                    if (entry.Value.Exp < cutoff) VoiceTickets.TryRemove(entry.Key, out _);
+                }
+                long nowSec = DateTimeOffset.UtcNow.ToUnixTimeSeconds();
+                foreach (var entry in VoiceAuthLimits)
+                {
+                    if (entry.Value.resetAt <= nowSec) VoiceAuthLimits.TryRemove(entry.Key, out _);
+                }
+            }
+        });
+
         var builder = WebApplication.CreateBuilder(args);
         builder.Services.AddHostedService<BackgroundDelete>();
         builder.Logging.ClearProviders();
@@ -95,6 +118,9 @@ public class Program
                             context.Response.StatusCode = StatusCodes.Status400BadRequest;
                         }
                         return;
+                    case "/_larpix/voice/auth":
+                        await LarpixServer.Room.Shared.InternalVoiceAuth(context);
+                        return;
                     case "/_larpix/serverinfo":
                         ServerInfo serverInfo = new ServerInfo();
                         serverInfo.domain = DOMAIN;