RTACO

RTACO (RTnetlink Asio COroutines) is a coroutine-first, RTNL-only control-plane library for Linux. It provides Boost.Asio awaitable APIs for NETLINK_ROUTE transactions and for subscribing to kernel notifications (link, address, route, neighbor).

Scope

• Linux only (NETLINK_ROUTE / RTNETLINK).
• Control-plane only - no dataplane.
• Results use std::expected<..., std::error_code>.

API at a glance

• llmx::rtaco::Control (include/rtaco/nl_control.hxx)

  • Dumps: dump_routes(), dump_addresses(), dump_links(), dump_neighbors().
  • Awaitables: async_dump_routes(), async_dump_addresses(), async_dump_links(), async_dump_neighbors().
  • Neighbor ops: probe_neighbor(), flush_neighbor(), get_neighbor() and async variants.

• llmx::rtaco::Listener (include/rtaco/nl_listener.hxx)

  • Starts a netlink receive loop and emits typed events via Signal.
  • Subscribe via connect_to_event(...) for LinkEvent, AddressEvent, RouteEvent, NeighborEvent.
  • Use ExecPolicy::Sync for inline handlers, or ExecPolicy::Async to post handlers onto the executor.

Build

Dependencies:

• C++23 compiler on Linux
• Boost (Asio, Signals2, System)
• Linux netlink headers (typically from linux-libc-dev / kernel headers)

Configure and build (Ninja):

cmake -S . -B build -G Ninja \
  -DCMAKE_BUILD_TYPE=Release \
  -DRTACO_BUILD_EXAMPLES=ON
cmake --build build

Install:

cmake --install build

Consume from CMake:

find_package(llmx-rtaco CONFIG REQUIRED)
target_link_libraries(your_target PRIVATE llmx::rtaco)

Usage (minimal)

#include <boost/asio/io_context.hpp>

#include <rtaco/core/nl_control.hxx>
#include <rtaco/core/nl_listener.hxx>

auto main() -> int {
    boost::asio::io_context io;

    llmx::rtaco::Control ctl{io};
    if (auto routes = ctl.dump_routes(); !routes) {
        // routes.error() is a std::error_code
        return 1;
    }

    llmx::rtaco::Listener listener{io};
    listener.connect_to_event([](const llmx::rtaco::RouteEvent& ev) {
        // do something with ev
    });
    listener.start();

    io.run();
    return 0;
}

For a more complete setup, see:

• examples/nl_control_example.cxx
• examples/nl_listener_example.cxx

Privileges

Some operations (for example neighbor probe/flush) typically require CAP_NET_ADMIN. The examples may need to be run under sudo or with capabilities, depending on your environment.

License

See LICENSE.