Lmnet

Cross-platform asynchronous networking library for C++17.

Lmnet provides a unified API for TCP, UDP, and Unix domain socket communication while using the native I/O model of each platform:

• Linux: epoll or io_uring
• macOS: kqueue
• Windows: IOCP

It is intended for learning, prototypes, and application-level network components that need the same API across platforms.

Overview

• TCP client and server APIs
• UDP client and server APIs
• Unix domain socket client and server APIs on Linux and macOS
• Platform-specific backends selected by CMake
• Callback-based session and buffer handling
• Examples and unit tests in the repository

Platform Support

Capability	Linux	macOS	Windows	Notes
TCP client/server	Yes	Yes	Yes	Uses the platform backend selected at build time
UDP client/server	Yes	Yes	Yes	Datagram APIs share the same listener model
Unix domain sockets	Yes	Yes	No	Exposed through UnixClient and UnixServer
Linux backend selection	epoll / io_uring	N/A	N/A	`LMNET_LINUX_BACKEND=AUTO

Requirements

• C++17 compiler
• CMake 3.10 or later
• lmcore
• On Linux, liburing is required only when building with the io_uring backend
• On Windows, Visual Studio 2019 or later is recommended

Getting Started

1. Provide lmcore

Lmnet first tries find_package(lmcore). If that fails, it looks for a sibling directory named ../lmcore.

Recommended local layout:

workspace/
|- lmcore/
`- lmnet/

Example:

git clone https://github.com/lmshao/lmcore.git
git clone https://github.com/lmshao/lmnet.git

2. Configure and build

Linux and macOS:

cmake -S . -B build
cmake --build build --parallel

Windows:

cmake -S . -B build -G "Visual Studio 16 2019" -A x64
cmake --build build --config Debug

Useful CMake options:

• -DBUILD_EXAMPLES=OFF
• -DBUILD_TESTS=OFF
• -DBUILD_STATIC_LIBS=OFF
• -DBUILD_SHARED_LIBS=OFF

3. Select the Linux backend

Linux builds accept these values:

• AUTO: prefer io_uring when liburing is available, otherwise fall back to epoll
• EPOLL: force the epoll backend
• IOURING: require io_uring and fail configuration if liburing is unavailable

Examples:

cmake -S . -B build -DLMNET_LINUX_BACKEND=AUTO
cmake -S . -B build -DLMNET_LINUX_BACKEND=EPOLL
cmake -S . -B build -DLMNET_LINUX_BACKEND=IOURING

4. Install

Install and CMake package export targets are generated on Unix-like platforms:

cmake --install build

Windows does not currently provide install or uninstall targets; use the build output directly.

Quick Start

Minimal TCP echo server:

#include <chrono>
#include <lmnet/tcp_server.h>

#include <iostream>
#include <memory>
#include <thread>

using namespace lmshao::lmnet;

class MyListener : public IServerListener {
public:
    void OnAccept(std::shared_ptr<Session> session) override
    {
        std::cout << "accepted: " << session->ClientInfo() << std::endl;
    }

    void OnReceive(std::shared_ptr<Session> session, std::shared_ptr<DataBuffer> buffer) override
    {
        session->Send(buffer);
    }

    void OnClose(std::shared_ptr<Session>) override {}
    void OnError(std::shared_ptr<Session>, const std::string &) override {}
};

int main()
{
    uint16_t port = 7777;
    auto tcp_server = TcpServer::Create("0.0.0.0", port);
    auto listener = std::make_shared<MyListener>();

    tcp_server->SetListener(listener);
    if (!tcp_server->Init() || !tcp_server->Start()) {
        return 1;
    }

    std::cout << "listening on 0.0.0.0:" << port << std::endl;
    while (true) {
        std::this_thread::sleep_for(std::chrono::hours(24));
    }
}

Examples

The repository includes runnable examples in examples:

• tcp_echo_server
• tcp_client
• tcp_benchmark
• udp_echo_server
• udp_client
• udp_stream
• unix_echo_server
• unix_client
• network_utils_demo

The public headers are under include/lmnet.

Testing

Builds enable tests by default. Run them after building:

Unix-like platforms:

ctest --test-dir build --output-on-failure

Windows:

ctest --test-dir build -C Debug --output-on-failure

Repository Layout

include/lmnet/      Public headers
src/                Common implementation
src/platforms/      Platform backends
examples/           Sample programs
tests/              Unit tests
cmake/              Package config and uninstall helpers

Contributing

Contributions are welcome! Please open issues or pull requests for bug reports, feature requests, or improvements.

License

This project is licensed under the MIT License. See LICENSE for details.