DeflateMiddleware: Add deflate compression to game responses (#487)

Refresh.Common/Refresh.Common.csproj

@@ -7,8 +7,8 @@
     </PropertyGroup>
 
     <ItemGroup>
-      <PackageReference Include="Bunkum" Version="4.5.2" />
-      <PackageReference Include="Bunkum.Protocols.Http" Version="4.5.2" />
+      <PackageReference Include="Bunkum" Version="4.5.3" />
+      <PackageReference Include="Bunkum.Protocols.Http" Version="4.5.3" />
     </ItemGroup>
 
 </Project>

Refresh.GameServer/Configuration/GameServerConfig.cs

@@ -9,7 +9,7 @@ namespace Refresh.GameServer.Configuration;
 [SuppressMessage("ReSharper", "RedundantDefaultMemberInitializer")]
 public class GameServerConfig : Config
 {
-    public override int CurrentConfigVersion => 13;
+    public override int CurrentConfigVersion => 14;
     public override int Version { get; set; } = 0;
 
     protected override void Migrate(int oldVer, dynamic oldConfig) {}
@@ -27,6 +27,11 @@ protected override void Migrate(int oldVer, dynamic oldConfig) {}
     public bool MaintenanceMode { get; set; } = false;
     public bool RequireGameLoginToRegister { get; set; } = false;
     public bool TrackRequestStatistics { get; set; } = false;
+    /// <summary>
+    /// Whether to use deflate compression for responses.
+    /// If this is disabled, large enough responses will cause LBP to overflow its read buffer and eventually corrupt its own memory to the point of crashing.
+    /// </summary>
+    public bool UseDeflateCompression { get; set; } = true;
     public string WebExternalUrl { get; set; } = "https://refresh.example.com";
     /// <summary>
     /// The base URL that LBP3 uses to grab config files like `network_settings.nws`.

Refresh.GameServer/Middlewares/DeflateMiddleware.cs

@@ -0,0 +1,61 @@
+using Bunkum.Core.Database;
+using Bunkum.Core.Endpoints.Middlewares;
+using Bunkum.Listener.Request;
+using Org.BouncyCastle.Utilities.Zlib;
+using Refresh.GameServer.Configuration;
+using Refresh.GameServer.Endpoints;
+
+namespace Refresh.GameServer.Middlewares;
+
+/// <summary>
+/// Adds deflate encoding to LBP game server responses if they reach a certain size.
+/// The game will eventually corrupt its own memory if we do not do this,
+/// since non-deflate requests only get a very small request buffer, and if you send too big of a request,
+/// it overruns that buffer and starts corrupting random heap memory.
+/// Requests encoded with deflate get a much larger read buffer, so they avoid this problem until much larger buffer sizes.
+/// </summary>
+public class DeflateMiddleware(GameServerConfig config) : IMiddleware
+{
+    /// <summary>
+    /// After this many bytes, start deflating request bodies
+    /// </summary>
+    private const int DeflateCutoff = 1024;
+
+    public void HandleRequest(ListenerContext context, Lazy<IDatabaseContext> database, Action next)
+    {
+        next();
+
+        if (!config.UseDeflateCompression)
+            return;
+
+        // If this isn't a game request or it's a resource request, don't deflate, since resource requests will be corrupted if deflated
+        if (!context.Uri.AbsolutePath.StartsWith(GameEndpointAttribute.BaseRoute) || context.Uri.AbsolutePath.StartsWith($"{GameEndpointAttribute.BaseRoute}r/"))
+            return;
+
+        string? encodings = context.RequestHeaders.Get("Accept-Encoding");
+        // If the accepted encodings aren't specified, or they don't contain deflate, or we don't need to use deflate on the data, do nothing.
+        if (encodings == null || !encodings.Contains("deflate") || context.ResponseStream.Length <= DeflateCutoff) 
+            return;
+
+        // Update the headers marking that we are sending encoded data
+        context.ResponseHeaders["X-Original-Content-Length"] = context.ResponseStream.Length.ToString();
+        context.ResponseHeaders["Vary"] = "Accept-Encoding";
+        context.ResponseHeaders["Content-Encoding"] = "deflate";
+
+        // Create a copy of our uncompressed data
+        byte[] uncompressed = context.ResponseStream.ToArray();
+
+        // Reset the response stream position and length to 0, so we can start writing to it again
+        context.ResponseStream.Position = 0;
+        context.ResponseStream.SetLength(0);
+
+        // Compress our source data into the response stream
+        using ZOutputStreamLeaveOpen zlibStream = new(context.ResponseStream, 6);
+        zlibStream.Write(uncompressed);
+        zlibStream.Finish();
+        zlibStream.Close();
+
+        // Seek back to the start
+        context.ResponseStream.Position = 0;
+    }
+}

Refresh.GameServer/Middlewares/DigestMiddleware.cs

@@ -84,7 +84,7 @@ private void SetDigestResponse(ListenerContext context)
 
     public void HandleRequest(ListenerContext context, Lazy<IDatabaseContext> database, Action next)
     {
-        //If this isnt an LBP endpoint, dont do digest
+        //If this isn't an LBP endpoint, dont do digest
         if (!context.Uri.AbsolutePath.StartsWith(GameEndpointAttribute.BaseRoute))
         {
             next();

Refresh.GameServer/Refresh.GameServer.csproj

@@ -52,12 +52,12 @@
     </ItemGroup>
 
     <ItemGroup Condition="'$(Configuration)'!='DebugLocalBunkum'">
-        <PackageReference Include="Bunkum" Version="4.5.2" />
-        <PackageReference Include="Bunkum.RealmDatabase" Version="4.5.2" />
-        <PackageReference Include="Bunkum.AutoDiscover" Version="4.5.2" />
-        <PackageReference Include="Bunkum.HealthChecks" Version="4.5.2" />
-        <PackageReference Include="Bunkum.HealthChecks.RealmDatabase" Version="4.5.2" />
-        <PackageReference Include="Bunkum.Protocols.Http" Version="4.5.2" />
+        <PackageReference Include="Bunkum" Version="4.5.3" />
+        <PackageReference Include="Bunkum.RealmDatabase" Version="4.5.3" />
+        <PackageReference Include="Bunkum.AutoDiscover" Version="4.5.3" />
+        <PackageReference Include="Bunkum.HealthChecks" Version="4.5.3" />
+        <PackageReference Include="Bunkum.HealthChecks.RealmDatabase" Version="4.5.3" />
+        <PackageReference Include="Bunkum.Protocols.Http" Version="4.5.3" />
     </ItemGroup>
 
     <ItemGroup>

Refresh.GameServer/RefreshGameServer.cs

@@ -87,6 +87,7 @@ protected override void SetupMiddlewares()
     {
         this.Server.AddMiddleware<LegacyAdapterMiddleware>();
         this.Server.AddMiddleware<WebsiteMiddleware>();
+        this.Server.AddMiddleware(new DeflateMiddleware(this._config!));
         this.Server.AddMiddleware<DigestMiddleware>();
         this.Server.AddMiddleware<CrossOriginMiddleware>();
         this.Server.AddMiddleware<PspVersionMiddleware>();