libsamp

Libre-SAMP: compatibility-focused drop-in replacement for the SA-MP 0.3.7-R5 samp.dll.

Runtime traces, original DLL reverse engineering, open.mp compatibility work, and an ASI probe for reproducible client-side instrumentation.

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TL;DR

git clone --recurse-submodules https://github.com/Knogle/libsamp
cd libsamp

reimpl/scripts/build_win32.sh
tools/asi_probe/build_win32.sh

Build outputs:

• build-win32/samp.dll
• build-asi-probe/samp_probe.asi

The build ships the vendored Knogle/RakNet submodule as the SA-MP/open.mp-compatible network transport source.

Use this only with local development servers and controlled test environments. It is not a cheat, bypass, or public-server abuse toolkit.

What It Is

libsamp, written out as Libre-SAMP, targets one concrete artifact: a compatible drop-in replacement for the SA-MP 0.3.7-R5 client samp.dll.

The short-term runtime still expects an existing GTA San Andreas installation with the SA-MP client files installed by the normal SA-MP installer. This repository does not ship proprietary client assets, game files, or a complete client distribution. The goal is to replace the DLL in that existing install while preserving protocol and runtime compatibility with 0.3.7-compatible servers, including open.mp compatibility paths.

The project is driven by observed behavior from the original DLL, ASI probe golden traces, and public engine/protocol references. Proprietary binaries, game assets, and local reverse-engineering workspaces are intentionally not part of this repository.

Current Status

Libre-SAMP has reached a playable compatibility milestone. The replacement now boots GTA San Andreas, connects to tested local SA-MP 0.3.7/open.mp servers, completes class selection and spawn, and runs feature-heavy legacy gamemodes. The broad RPC gap pass for the currently agreed compatibility scope is largely complete; development has moved into consolidation, regression testing, and closer original-R5 parity work.

Implemented and exercised surfaces include:

• Loading and pre-connect presentation, RakNet join, class selection, spawn, death/F4 flows, GMX handling, and full connection-loss reset back to the pre-connect state.
• Chat, commands, fragmented dialogs and responses, menus, mouse mode, the TAB player list, player-pool updates, and core local/remote sync paths.
• GTA vehicles, actors, normal and SA-MP custom atomic objects, object movement, materials/material text, attachments, map icons, gang zones, checkpoints, 3D labels, GameText, and building removal.
• SA-MP HUD and UI behavior, GTA CFont-backed TextDraws, Font 5 model previews, class selection, death window, weather/time, camera, spectating, player attributes, weapons, animations, and advanced vehicle RPCs.
• BASS-backed audio streams, GTA sound/scanner integration, attached-object and object editing with wire-compatible responses, plus bounds-checked RPC decoding and detailed runtime traces.

This is still a compatibility rebuild, not a byte-for-byte finished clone. Current work is concentrated on:

• Golden-trace consolidation and repeatable original/replacement regression scenarios, including two-client and long-running sessions.
• Exact R5 presentation details such as attachment bone matrices, the original edit gizmo/camera behavior, scanner phrasing, and visual edge cases.
• Generic samp.saa ArchiveFS virtualization and remaining custom-asset streaming/material edge cases.
• Remote-player/vehicle interpolation, uncommon RPC and pool edge cases, defensive payload tests, and remaining pickup behavior.
• PE layout/import parity and other binary-surface differences that do not currently block the tested runtime milestone.

Screenshots

Replacement-client snapshots from a local feature-heavy legacy gamemode run on 2026-07-18:

Replacement DLL startup and loading-screen path.	Pre-connect panorama, status overlay, and session-ready state.
Server dialog rendering, selection, mouse input, and response flow.	Class selection, camera control, TextDraws, and custom object scene.
Vehicle pools, map objects, labels, HUD, radar, and world streaming.	Bare open.mp fixture with vehicles, custom objects, HUD, radar, and TAB player list.

Highlights

• Playable Win32 samp.dll drop-in rebuild with PE/export compatibility tracking and a broad, bounds-checked SA-MP RPC surface.
• Vendored Knogle/RakNet transport with join, reconnect, sync, dialog/menu, and client-to-server response paths for SA-MP/open.mp-oriented networking.
• GTA-SA runtime integration for players, vehicles, actors, objects and custom models, materials, world state, audio, cameras, HUD, TextDraws, dialogs, menus, labels, markers, and editing flows.
• Legacy lifecycle behavior covering loading, pre-connect, class selection, spawn/death, GMX, disconnect, and reconnect preparation.
• ASI probe included under tools/asi_probe for repeatable instrumentation and golden trace collection.
• Evidence-tagged documentation model: OBSERVED_037, PROBE_TRACE, STATIC_037, OPENMP_REF, GTA_REVERSED_REF, INFERRED, and TODO_VERIFY.

Build From Source

Requirements

On Linux, install:

• CMake
• Ninja
• MinGW-w64 i686 GCC/G++
• Git submodule support

Fedora example:

sudo dnf install cmake ninja-build mingw32-gcc mingw32-gcc-c++

Debian/Ubuntu example:

sudo apt-get install cmake ninja-build gcc-mingw-w64-i686 g++-mingw-w64-i686

Build The DLL

git submodule update --init --recursive
reimpl/scripts/build_win32.sh

This is the same public CI-style build used by GitHub Actions. It verifies the DLL surface, runtime bridge, and vendored RakNet-backed network path without depending on local-only reference workspaces.

Build The ASI Probe

tools/asi_probe/build_win32.sh

The probe builds to build-asi-probe/samp_probe.asi and is loaded by a normal ASI loader from the game root or an ASI loader search path.

GitHub Actions

The repository contains a CI workflow at .github/workflows/build.yml. It builds:

• samp.dll
• samp_probe.asi
• SHA256SUMS.txt

The CI artifact build intentionally avoids proprietary inputs and local-only reference paths. Runtime parity still depends on golden-trace verification.

Documentation

• Original public-milestone task tracker
• Publication checklist
• Reverse-engineering evidence guide
• Current RPC attachment/edit/crime/building pass
• Legacy feature gap matrix
• TextDraw render stack notes
• Custom asset pipeline notes
• ASI probe README

Scope And Safety

This project is for compatibility research, local testing, and preservation of 0.3.7-compatible client behavior. Do not use it to cheat, evade bans, bypass server protections, or disrupt public servers.

Server-provided data is treated as untrusted. New RPC handlers should be bounds-checked, fail closed, and log unknown behavior before implementing unverified semantics.

License

Libre-SAMP is licensed under the MIT License. See LICENSE.

Third-party components and generated asset provenance are documented in NOTICE.md. The repository MIT License does not relicense third-party submodules.

Credits

• SA-MP and GTA-SA modding communities for protocol and engine knowledge.
• open.mp for public server-side compatibility references.
• gta-reversed for public GTA-SA engine research.
• Ultimate ASI Loader and related tooling for the ASI plugin ecosystem.