protodec

A tool to decompile protobuf classes compiled by protoc, from il2cpp compiled CIL assemblies back into .proto definitions.

This branch was created as a proof-of-concept using the development branch of LibCpp2Il to parse the game assembly and metadata directly, without the intermediate step of generating dummy DLLs.

I offer no guarantees that this branch functions 1:1 with master, it may explode.

Usage

Usage: protodec(.exe) <game_assembly_path> <global_metadata_path> <unity_version> <out_path> [options]
Arguments:
  game_assembly_path    The path to the game assembly DLL.
  global_metadata_path  The path to the global-metadata.dat file.
  unity_version         The version of Unity which was used to create the metadata file or alternatively, the path to the globalgamemanagers or the data.unity3d file.
  out_path              An existing directory to output into individual files, otherwise output to a single file.
Options:
  --debug                                                     Drops the minimum log level to Debug.
  --parse_service_servers                                     Parses gRPC service definitions from server classes.
  --parse_service_clients                                     Parses gRPC service definitions from client classes.
  --skip_enums                                                Skip parsing enums and replace references to them with int32.
  --include_properties_without_non_user_code_attribute        Includes properties that aren't decorated with `DebuggerNonUserCode` when parsing.
  --include_service_methods_without_generated_code_attribute  Includes methods that aren't decorated with `GeneratedCode("grpc_csharp_plugin")` when parsing gRPC services.

Limitations

• Integers are assumed to be (u)int32/64 as CIL doesn't differentiate between them and sint32/64 and (s)fixed32/64.
• Package names are not preserved in protobuf compilation so naturally we cannot recover them during decompilation, which may result in naming conflicts.
• Due to the development branch of Cpp2Il not yet recovering method bodies, when parsing an Il2Cpp assembly older than metadata version 29
  • The Name parameter of OriginalNameAttribute is not parsed. In this case, the CIL enum field names are used after conforming them to protobuf conventions.
  • The Tool parameter of GeneratedCodeAttribute is not compared against when parsing gRPC service methods, which may cause false positives in the event that another tool has generated methods in the service class.

License

This project is subject to the terms of the Mozilla Public License, v. 2.0.