Abyss Raw 0.9.0

This independent OTP package owns the Rustler build and native artifact for interface-bound DHCP client UDP and raw ARP. It does not depend on Abyss or start a socket/poll thread at application startup. AbyssDhcpSocket.Native implements the five native operations; existing callers use the pure Elixir Abyss.DhcpSocket.Native facade supplied by Abyss.

DHCP users must explicitly install the optional Hex package when upgrading Abyss:

defp deps do
  [
    {:abyss, "~> 0.9.0"},
    {:abyss_raw, "~> 0.9.0"}
  ]
end

The package is also usable independently with only {:abyss_raw, "~> 0.9.0"} and direct calls to AbyssDhcpSocket.Native. It has no dependency on Abyss. The implementation module AbyssDhcpSocket.Native, Rust crate dhcp_socket, and NIF registration retain their existing names for compatibility, including with the facade in Abyss 0.8.1. No abyss_dhcp_socket Hex dependency is needed.

Build from source with Elixir/Mix, Cargo/Rust, and a native linker. There are no precompiled NIF downloads; installing the package requires the native toolchain. The crate and Cargo.lock are preserved from Abyss. Its shared library belongs to :abyss_raw under priv/native/dhcp_socket, never the core application. The package does not ship Abyss.DhcpSocket.Native or require a dependency cycle.

The five operations are open/2, send_broadcast/2, send_unicast/3, send_arp_probe/2, and close/1. open(interface, owner) returns an opaque resource directly or {:error, reason}. Sends return :ok or {:error, reason}; close/1 is idempotent. DHCP binds UDP port 68 and sends to port 67. Linux raw ARP needs CAP_NET_RAW; binding low ports may need CAP_NET_BIND_SERVICE. The implementation targets Unix systems; Windows is unsupported. macOS/FreeBSD raw ARP remains unavailable, as before.

Owner messages remain {:dhcp_rx, binary}, {:arp_rx, binary}, {:dhcp_socket_down, reason}, and {:arp_socket_down, reason}. Explicit close sends no down message. Owner death is observed when packet delivery fails; resource cleanup or explicit close/1 closes the descriptors. Do not infer immediate native reclamation from process death.

The Abyss 0.9.0 facade reports {:error, {:missing_optional_dependency, :abyss_raw}} when this package is absent, and {:error, {:optional_dependency_load_failed, :abyss_raw, reason}} when its module cannot load. Native operation errors pass through unchanged.

Run independent validation:

cd packages/abyss_raw
mix deps.get
mix test
bash scripts/test_arp.sh
cargo clippy --manifest-path native/dhcp_socket/Cargo.toml --locked --all-targets -- -D warnings

The ARP script runs the five existing source unit tests in a disposable Rust-only harness without linking BEAM NIF symbols. Native DHCP/ARP wire validation uses scripts/udp/dhcp_fixture.py through python3 scripts/udp/p5_consumers.py from the repository root. It shares the existing UDP namespace topology, confines capabilities and packets to those namespaces, and never changes the ambient LAN. This validation is opt-in and requires namespace setup permission. No publication is performed.