# Third-party native dependencies

The GDExtension links four native libraries that are **not** part of Godot or
godot-cpp. Phase 1 (macOS) pulled the first three from Homebrew; that stops
working the moment we cross-compile for the Android NDK or the iOS SDK (BACKLOG
F1/F2), so as of 2026-08-30 they are built from source as part of our own CMake
build. Crypto++ joined later (2026-09-02) with the `MT_PROTOCOL=classic` 40250
backend and was vendored the same way from the start.

Everything lives under `extension/third_party/` and is wired by
`extension/third_party/CMakeLists.txt`, which exposes four aliases:

| Alias             | Backing target   | Consumed by                  |
|-------------------|------------------|------------------------------|
| `mt3p::sodium`    | `sodium`         | `mtnet`, `mtpack`, `mtproto` |
| `mt3p::zstd`      | `libzstd_static` | `mtpack`                     |
| `mt3p::minilzo`   | `minilzo`        | `mtproto`                    |
| `mt3p::cryptopp`  | `cryptopp`       | `mtnet` (classic backend)    |

No source file changed: `#include <sodium.h>`, `#include <zstd.h>`,
`#include <lzo/lzo1x.h>` and `#include <cryptopp/…>` all still resolve (the LZO
one via a 1-line shim header, see below).

## libsodium — via `robinlinden/libsodium-cmake`

* **Submodule:** `extension/third_party/libsodium-cmake` @ `9b2848d`
  * itself carries `jedisct1/libsodium` @ `93a7d0d` (libsodium 1.0.20 line) as a
    **nested** submodule — clones need `--recursive`.
* **Why the wrapper:** upstream libsodium is autotools-only. This MIT-licensed
  wrapper is a pure CMakeLists over an untouched libsodium checkout; it generates
  `version.h`, sets `CONFIGURED`, and builds clean for macOS / iOS / Android /
  Windows. Used by many mobile projects.
* **Build options we force:** `SODIUM_DISABLE_TESTS=ON`, `SODIUM_MINIMAL=OFF`
  (we need `crypto_kx`, `crypto_auth`, `crypto_aead_xchacha20poly1305`,
  `crypto_stream_xchacha20`, `crypto_generichash`/BLAKE2b — all outside the
  "minimal" set).
* **License:** ISC (libsodium) + MIT (wrapper). Ship-safe.

## libzstd — `facebook/zstd`

* **Submodule:** `extension/third_party/zstd` @ tag **v1.5.6** (`794ea1b0`).
* Built through upstream `build/cmake` with:
  `ZSTD_BUILD_PROGRAMS/SHARED/TESTS/CONTRIB=OFF`, `ZSTD_BUILD_STATIC=ON`,
  `ZSTD_LEGACY_SUPPORT=OFF`, `ZSTD_MULTITHREAD_SUPPORT=OFF` (the eterpack path
  only does single-shot `ZSTD_compress`/`ZSTD_decompress`).
* Target consumed: `libzstd_static` (carries its own public include dir).
* **License:** BSD-3-Clause / GPLv2 dual. Ship-safe under BSD.

## miniLZO — vendored source (not a submodule)

* **Files:** `extension/third_party/minilzo/{minilzo.c,minilzo.h,lzoconf.h,lzodefs.h}`
  copied verbatim from **lzo-2.10** (`minilzo.c` sha1 `019debb3…`), plus
  `README.LZO`, `COPYING`, `AUTHORS` as required by the LZO license.
* Upstream LZO has no git repo (oberhumer.com tarball only), and miniLZO is a
  4-file amalgamation, so it is copied in rather than submoduled.
* **Shim:** `minilzo/lzo/lzo1x.h` is a 1-line `#include "../minilzo.h"` so
  `extension/src/proto/proto.cpp` keeps `#include <lzo/lzo1x.h>` unchanged.
  miniLZO's API (`lzo_init`, `lzo1x_decompress_safe`, `LZO_E_OK`, `lzo_uint`) is a
  strict subset of full LZO and covers everything the CLZO path uses.
* **License:** **GPLv2**. Acceptable for this internal, non-published,
  non-commercial project on the same footing as `libgr2/src/oodle1.c` — but LZO
  must be removed, replaced, or commercially licensed before any public release
  or commercial use. (item_proto/mob_proto are the only LZO consumers; a
  clean-room LZO1X decompressor is the eventual fix.)

## Crypto++ — vendored source (not a submodule)

* **Files:** `extension/third_party/cryptopp/` (~6.6 MB), copied from the 40250
  client tree (`ClientVS22/extern/include/cryptopp`), `CRYPTOPP_VERSION 840` =
  **8.4.0**. The 40250 server links this exact version
  (`Server/.../extern/cryptopp_8_4_0.tar.gz`), so the version is pinned by
  wire compatibility, not preference.
* **Why:** the `MT_PROTOCOL=classic` backend's `_IMPROVED_PACKET_ENCRYPTION_`
  cipher — DH2 key agreement + hint-selected block ciphers (Twofish default) in
  CTR mode. Only consumer is `extension/src/net/classic/classic_cipher.{h,cpp}`.
  The m2dev backend does not use it (that one is libsodium/XChaCha20).
* **No upstream CMakeLists**, so `cryptopp/CMakeLists.txt` is ours: it globs the
  library TUs and drops the cryptest / benchmark / adhoc / FIPS-selftest ones
  (`adhoc`, `bench1..3`, `datatest`, `dlltest`, `fipsalgt`, `fipstest`, `pch`,
  `regtest1..4`, `test`, `validat0..10`).
* **ASM disabled everywhere** (`CRYPTOPP_DISABLE_ASM` / `_SSSE3` / `_AESNI`) so
  one pure-C++ build works on macOS, the Android NDK and the iOS SDK; the classic
  cipher needs no AES-NI / SHA-ext. Android additionally compiles the NDK's
  `sources/android/cpufeatures/cpu-features.c` in, because upstream `cpu.cpp`
  includes `cpu-features.h` unconditionally under `__ANDROID__`.
* Built with `-w` (upstream is not warning-clean under `-Wall`) and
  `-fno-strict-aliasing`.
* **License:** **public domain** — the compilation carries Wei Dai's copyright,
  but every individual file is placed in the public domain by its authors
  (`extension/third_party/cryptopp/License.txt`). Ship-safe; unlike miniLZO it
  imposes no obligation before a public or commercial release.

## Rebuilding / fetching

`./build.sh` auto-runs `git submodule update --init --recursive` if any of the
three submodules (godot-cpp, zstd, libsodium-cmake+libsodium) is missing.
miniLZO and Crypto++ are vendored source and need no fetch.

Homebrew `libsodium` / `zstd` / `lzo` are no longer referenced by the build and
can be uninstalled.