c-libp2p

c-libp2p is an implementation of the libp2p specification written in C. The project is still in active development but already provides the building blocks needed for peer-to-peer networking applications.

Building

c-libp2p uses CMake and should build on Linux, macOS and Windows. A C compiler that supports the C11 standard is required.

Clone the repository

git clone --recursive https://github.com/Pier-Two/c-libp2p.git
cd c-libp2p

The --recursive flag ensures that all third-party submodules are fetched.

Linux / macOS

mkdir build
cmake -S . -B build
cmake --build build
ctest --test-dir build

Sanitizers can be enabled with -DENABLE_SANITIZERS=ON and additional flags in SANITIZERS. Stress tests for the TCP module are built when -DENABLE_STRESS_TESTS=ON is passed.

Windows

A recent Visual Studio with CMake support is recommended. From the x64 Native Tools command prompt run:

mkdir build
cmake -S . -B build -G "Visual Studio 16 2019" -A x64
cmake --build build --config Release
ctest --test-dir build -C Release

When building shared libraries on Windows the produced DLLs are copied next to the test executables automatically.

CI lanes

Validation is split into two lanes:

• Fast lane (.github/workflows/ci-fast.yml, required for PRs):
  • macos-smoke
  • linux-smoke
  • windows-smoke
• Full lane (.github/workflows/ci-full.yml, runs on main, nightly, and manual dispatch):
  • macos-full
  • linux-gcc-full
  • linux-clang-full
  • linux-sanitizers (ASan/UBSan)
  • windows-full

The lane presets are versioned in CMakePresets.json and can be run locally:

# fast lane (macOS example)
cmake --preset macos-smoke
cmake --build --preset macos-smoke
ctest --preset macos-smoke

# full lane (macOS example)
cmake --preset macos-full
cmake --build --preset macos-full
ctest --preset macos-full

For Windows validation from non-Windows development machines, trigger and monitor the full lane with GitHub CLI:

gh workflow run ci-full.yml --ref <branch>
gh run list --workflow ci-full.yml
gh run watch <run-id>
gh run view <run-id> --log

Local pre-push fast-lane hook (macOS/Linux)

Install the repository-managed git hooks:

scripts/dev/install-hooks.sh

This configures core.hooksPath to .githooks and enables a pre-push hook that runs the same macOS/Linux fast-lane checks used by CI.

On Linux, fast-lane checks include:

• clang-format diff check for changed src/, include/, and tests C files.
• a targeted Doxygen documentation gate for changed headers in include/multiformats/unsigned_varint/ and include/multiformats/multicodec/ (WARN_IF_UNDOCUMENTED=YES, WARN_AS_ERROR=YES).
• a targeted MISRA add-on check for rewritten multiformats scope (unsigned_varint + multicodec) with documented Rule 8.7 advisory suppressions for exported API symbols.
• a targeted clang-tidy CERT gate (-checks=-*,cert-*, warnings-as-errors) for changed C sources in src/multiformats/{unsigned_varint,multicodec}.
• cppcheck smoke static analysis for core scope.

Manual local run:

# Auto-detect host platform (macOS or Linux)
scripts/dev/run-fast-lane-local.sh

# Force a specific platform script
scripts/dev/run-fast-lane-local.sh --platform macos
scripts/dev/run-fast-lane-local.sh --platform linux

To bypass the hook for one push:

LIBP2P_SKIP_FAST_HOOK=1 git push

Project Structure

• src/ – library source code
• include/ – public headers
• tests/ – unit tests
• benchmarks/ – optional benchmarks
• docs/ – user guides and examples

Detailed documentation is available under docs/.

Third-party libraries

c-libp2p bundles several third-party projects under external/:

• libtomcrypt and libtommath – LibTom License
• secp256k1 – MIT License
• sha3 – MIT-0 License
• WjCryptLib – Unlicense
• c20p1305 – MIT License
• libeddsa – Unlicense
• noise-c – MIT License

Please refer to each submodule for license details.

License

The code in this repository is licensed under the MIT License.