feat: Add ProtoDumper for runtime Google.Protobuf schema extraction and decoding

DorkNet.ProtoDumper/ProtoDumper.cs

@@ -0,0 +1,259 @@
+// DorkNet ProtoDumper — runtime Google.Protobuf schema extractor.
+//
+// Rec Room compiles its room-save / creation / circuits data model from
+// .proto files into Google.Protobuf C# classes. In the shipped IL2CPP build
+// those classes are name-obfuscated and the descriptor base64 is split into
+// scattered string-literal chunks, so static reconstruction from
+// global-metadata.dat is unreliable.
+//
+// At RUNTIME every FileDescriptor still carries its original, un-obfuscated
+// FileDescriptorProto (message names, field names, numbers, types intact).
+// The catch: these descriptors are built LAZILY and in a specific dependency
+// order by the game. Force-building them ourselves (by reading a message
+// type's static descriptor property out of order) throws inside the type's
+// static constructor and the failure is cached — poisoning the type. So we do
+// NOT enumerate types. Instead we Harmony-postfix the one library method every
+// generated cctor funnels through — Google.Protobuf.Reflection.FileDescriptor
+// .BuildFrom / .FromGeneratedCode — and capture each descriptor as the game
+// builds it. Completely passive: just play the client through the dorm, a
+// created room, the Maker Pen and a circuits board, and every descriptor that
+// loads is recorded.
+//
+// Output (under <RecRoom>\DorkNet-ProtoDump\):
+//   manifest.tsv          — one "<proto path>\t<base64>" line per file
+//   files\<sanitised>.b64 — same base64, one file each
+//   dump.log              — capture log
+//
+// Decode offline with decode_dump.py (see README.md).
+
+using HarmonyLib;
+using MelonLoader;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Reflection;
+using System.Text;
+
+[assembly: MelonInfo(typeof(DorkNet.ProtoDumper.ProtoDumper), "DorkNet ProtoDumper", "2.0.0", "Dork Squad")]
+[assembly: MelonGame(null, null)]
+
+namespace DorkNet.ProtoDumper;
+
+public class ProtoDumper : MelonMod
+{
+    private static MelonLogger.Instance? _log;
+
+    // proto file name -> descriptor base64 (accumulated as the game builds them)
+    private static readonly Dictionary<string, string> Files = new(StringComparer.Ordinal);
+    private static readonly object Gate = new();
+    private static string _outDir = "";
+    private static string _filesDir = "";
+    private static volatile bool _dirty;
+    private int _frame;
+
+    public override void OnInitializeMelon()
+    {
+        _log = LoggerInstance;
+        try
+        {
+            string baseDir = AppDomain.CurrentDomain.BaseDirectory ?? Directory.GetCurrentDirectory();
+            _outDir = Path.Combine(baseDir, "DorkNet-ProtoDump");
+            _filesDir = Path.Combine(_outDir, "files");
+            Directory.CreateDirectory(_filesDir);
+            _log.Msg($"ProtoDumper ready. Output dir: {_outDir}");
+        }
+        catch (Exception e) { _log?.Error($"ProtoDumper init failed: {e}"); }
+
+        InstallHooks();
+    }
+
+    private void InstallHooks()
+    {
+        try
+        {
+            // Google.Protobuf library type — NOT obfuscated (it's the library,
+            // not game code), reached by its original name via every loaded
+            // assembly so we never reference the interop DLL at compile time.
+            Type? fd = ResolveType("Google.Protobuf.Reflection.FileDescriptor");
+            if (fd == null)
+            {
+                _log?.Error("ProtoDumper: FileDescriptor type not found — cannot hook.");
+                return;
+            }
+
+            var postfix = new HarmonyMethod(
+                typeof(ProtoDumper).GetMethod(nameof(Captured_Postfix),
+                    BindingFlags.Public | BindingFlags.Static));
+
+            int patched = 0;
+            // BuildFrom is the lower-level builder every descriptor passes
+            // through; FromGeneratedCode is the generated-code entry point.
+            // Patch both (deduped downstream) so nothing is missed.
+            foreach (string name in new[] { "BuildFrom", "FromGeneratedCode" })
+            {
+                foreach (MethodInfo m in fd.GetMethods(BindingFlags.Public | BindingFlags.Static))
+                {
+                    if (m.Name != name) continue;
+                    try { HarmonyInstance.Patch(m, postfix: postfix); patched++; }
+                    catch (Exception e) { _log?.Warning($"ProtoDumper: patch {name} failed: {e.Message}"); }
+                }
+            }
+            _log?.Msg($"ProtoDumper: installed {patched} descriptor-build hooks. Play through your content; descriptors are captured as they load.");
+        }
+        catch (Exception e) { _log?.Error($"ProtoDumper hook install error: {e}"); }
+    }
+
+    // Resolve a type by its ORIGINAL (game-side) name, accounting for the
+    // Il2Cpp prefix Il2CppInterop puts on the namespace (so
+    // "Google.Protobuf.Reflection.FileDescriptor" ->
+    // "Il2CppGoogle.Protobuf.Reflection.FileDescriptor").
+    private static Type? ResolveType(string name)
+    {
+        foreach (Assembly asm in AppDomain.CurrentDomain.GetAssemblies())
+        {
+            try
+            {
+                var t = asm.GetType(name, false) ?? asm.GetType("Il2Cpp" + name, false);
+                if (t != null) return t;
+                int dot = name.IndexOf('.');
+                if (dot > 0)
+                {
+                    var ns = asm.GetType("Il2Cpp" + name.Substring(0, dot) + name.Substring(dot), false);
+                    if (ns != null) return ns;
+                }
+            }
+            catch { }
+        }
+        return null;
+    }
+
+    // Harmony postfix on FileDescriptor.BuildFrom / FromGeneratedCode.
+    // __result is the freshly-built FileDescriptor (Il2Cpp proxy, boxed as
+    // object — same pattern the ClientMod uses for il2cpp reference returns).
+    public static void Captured_Postfix(object? __result)
+    {
+        if (__result == null) return;
+        try { CollectFile(__result); }
+        catch { /* never let our hook disturb the game */ }
+    }
+
+    private static void CollectFile(object file)
+    {
+        string? name = GetProp(file, "Name") as string;
+        if (string.IsNullOrEmpty(name)) return;
+
+        lock (Gate)
+        {
+            if (Files.ContainsKey(name!)) return;
+
+            string b64 = DescriptorBase64(file);
+            Files[name!] = b64;
+            _dirty = true;
+        }
+
+        // Capture import dependencies too (closure of well-known + leaf protos).
+        try
+        {
+            object? deps = GetProp(file, "Dependencies");
+            if (deps != null)
+            {
+                var dt = deps.GetType();
+                var countP = dt.GetProperty("Count");
+                var itemM = dt.GetMethod("get_Item", new[] { typeof(int) });
+                if (countP != null && itemM != null)
+                {
+                    int n = (int)(countP.GetValue(deps) ?? 0);
+                    for (int i = 0; i < n; i++)
+                    {
+                        object? dep = itemM.Invoke(deps, new object[] { i });
+                        if (dep != null) CollectFile(dep);
+                    }
+                }
+            }
+        }
+        catch { }
+    }
+
+    private static string DescriptorBase64(object file)
+    {
+        try
+        {
+            // FileDescriptor exposes no public SerializedData property — only
+            // the Il2CppInterop backing field (a ByteString with the original
+            // descriptor bytes). Fall back to re-serialising the parsed Proto.
+            object? sd = GetProp(file, "_SerializedData_k__BackingField")
+                         ?? GetProp(file, "SerializedData");
+            if (sd != null)
+            {
+                string b = ByteStringToBase64(sd);
+                if (b.Length > 0) return b;
+            }
+            object? proto = GetProp(file, "Proto");
+            if (proto != null)
+            {
+                MethodInfo? toBs = proto.GetType().GetMethod("ToByteString", Type.EmptyTypes);
+                object? bs = toBs?.Invoke(proto, null);
+                if (bs != null) return ByteStringToBase64(bs);
+            }
+        }
+        catch { }
+        return "";
+    }
+
+    private static string ByteStringToBase64(object byteString)
+    {
+        MethodInfo? toB64 = byteString.GetType().GetMethod("ToBase64", Type.EmptyTypes);
+        return toB64?.Invoke(byteString, null) as string ?? "";
+    }
+
+    private static object? GetProp(object obj, string propName)
+    {
+        var p = obj.GetType().GetProperty(propName,
+            BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
+        return p?.GetValue(obj);
+    }
+
+    public override void OnUpdate()
+    {
+        // Flush to disk shortly after new descriptors are captured (every ~1s).
+        if (++_frame % 60 == 0 && _dirty)
+            Flush();
+    }
+
+    public override void OnApplicationQuit() => Flush();
+
+    private static void Flush()
+    {
+        lock (Gate)
+        {
+            if (!_dirty) return;
+            _dirty = false;
+            try
+            {
+                var sb = new StringBuilder();
+                int withData = 0;
+                foreach (var kv in Files)
+                {
+                    if (kv.Value.Length == 0) continue;
+                    withData++;
+                    sb.Append(kv.Key).Append('\t').Append(kv.Value).Append('\n');
+                    string fp = Path.Combine(_filesDir, Sanitize(kv.Key) + ".b64");
+                    if (!File.Exists(fp)) File.WriteAllText(fp, kv.Value);
+                }
+                File.WriteAllText(Path.Combine(_outDir, "manifest.tsv"), sb.ToString());
+                string line = $"captured files={Files.Count} (with-data={withData})";
+                File.AppendAllText(Path.Combine(_outDir, "dump.log"), line + "\n");
+                _log?.Msg($"ProtoDumper: {line} -> {_outDir}");
+            }
+            catch (Exception e) { _log?.Error($"ProtoDumper flush error: {e}"); }
+        }
+    }
+
+    private static string Sanitize(string protoPath)
+    {
+        var sb = new StringBuilder(protoPath.Length);
+        foreach (char c in protoPath)
+            sb.Append(char.IsLetterOrDigit(c) || c == '_' || c == '-' || c == '.' ? c : '_');
+        return sb.ToString();
+    }
+}