DiscordP2PMesh

C/C++ Peer To Peer Mesh Networking SDK built on Discord

DiscordP2PMesh connects players directly to each other, without you running any servers.

Discord does the parts around the connection: players log in with their Discord account, join a lobby by secret, and the offer/answer messages peers need to find each other travel through that lobby as hidden chat messages. libjuice then does the ICE negotiation that opens a direct UDP path between them, punching through NATs along the way.

You drive it through a plain C API. Once two players are connected you get a peer ID and raw byte buffers in both directions, and what you send over them is up to you.

Project Goals

Done

• Discord authentication (OAuth device flow, handled by the SDK)
• Lobbies
  • Create or join by secret
  • Lobby chat messages
  • Member join/leave notifications
• Peer to peer connections
  • ICE negotiation over the lobby, no signaling server of your own
  • Configurable STUN/TURN servers
  • Glare resolution when both sides connect at once
• Rich presence updates
• Poll based event system, no callbacks across the C boundary
• Automated builds for Windows, Linux and macOS

Maybe Later

• Reliability/ordering options on top of the raw UDP path
• Voice support

Getting Started

Docs

• Need a Discord application first? See docs/discord_application.md
• The API lives in a single header: include/discord_p2p_mesh.h
• Look at examples/console to see how it all fits together, it exercises every function and event in the API

The shape of it:

DPMeshConfig config = {0};
config.application_id = 1234567890;
config.stun_server_host = "stun.l.google.com";
config.stun_server_port = 19302;

DPMeshSession *session = dpmesh_create(&config);
dpmesh_login(session);

while (running) {
    dpmesh_update(session);

    DPMeshEvent event;
    while (dpmesh_poll_event(session, &event)) {
        // handle event.type
    }
}

dpmesh_destroy(session);

Event payload pointers stay valid until the next dpmesh_update() call on that session, so read them before you update again. All calls for a session must happen on the same thread that drives dpmesh_update().

Using it in Godot

There is a GDExtension wrapper over this library at DiscordP2PMesh-GD.

Building Examples

• The examples are built and ran using Visual Studio through DiscordP2PMesh.slnx, which builds the library alongside them
• Windows only for now

Building DiscordP2PMesh

Prerequisites

To build DiscordP2PMesh, make sure you have the following installed:

1. CMake (version 3.16 or higher)
2. C++ Compiler with C++20 support:
   • GCC or Clang (Linux/macOS)
   • MSVC (Visual Studio) for Windows
3. The Discord Social SDK, see thirdparty/README.md. It's proprietary so it can't be shipped in this repo, you download it once and drop it in place.

libjuice comes along as a submodule and is built and linked statically, so there is no package manager to set up.

Step-by-Step Instructions

1. Clone the Repository

git clone --recurse-submodules https://github.com/HeatXD/DiscordP2PMesh.git
cd DiscordP2PMesh

2. Add the Discord Social SDK

Follow thirdparty/README.md so the SDK ends up at thirdparty/discord_social_sdk/. If you keep it somewhere else, point DPMESH_DISCORD_SDK_DIR at it instead.

3. Configure Build Options

DiscordP2PMesh includes a few options to customize the build:

• BUILD_SHARED_LIBS: Set to ON to build a shared library, or OFF for a static one.
• DPMESH_DISCORD_SDK_DIR: Path to the Discord Social SDK, defaults to thirdparty/discord_social_sdk.

To configure these options, use cmake with -D flags. For example:

cmake -S . -B build -DBUILD_SHARED_LIBS=ON

4. Build the Project

cmake --build build

On successful completion, the library will be located in the out directory inside your build directory, together with the Discord SDK runtime it needs.

On Windows you can also just open DiscordP2PMesh.slnx in Visual Studio, which builds the library and the examples without CMake.

Build Output

• Library: discordp2pmesh, shared or static depending on BUILD_SHARED_LIBS
• Runtime dependency: discord_partner_sdk, copied next to the library. libjuice is linked in statically, so it doesn't ship separately.

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License

DiscordP2PMesh is licensed under the BSD-2-Clause license Read about it here.

The Discord Social SDK is not covered by that license and is not redistributed here, it remains subject to Discord's own developer terms.