oxipd

A from-scratch Rust rewrite of dhcpcd, targeting Linux only: a DHCPv4 + DHCPv6 + IPv6 Router Advertisement/SLAAC client daemon.

This is a clean-slate design (new config format, new oxipdctl CLI, new hook/event contract) rather than a dhcpcd drop-in replacement. See PLAN.md for the full architecture writeup and milestone breakdown this project is being built against.

The DHCPv4 client works end-to-end against a real DHCP server (verified in a network namespace + veth pair against dnsmasq: DISCOVER → OFFER → REQUEST → ACK, ARP-probed, and the address actually configured on the interface via oxipd's own netlink code — see crates/oxipd-core/examples/dhcp4_client.rs). DHCPv6/IPv6-RA, the control socket, and config/CLI are not implemented yet. 87+ tests across the workspace, zero clippy warnings.

• oxipd-proto — pure wire codecs, no I/O: dhcpv4 (DHCPv4/BOOTP, RFC 2132 option-overload + RFC 3396 long-option handling), arp (RFC 5227 probe/ announcement packets), ndp (RFC 4861 Router Solicitation/Advertisement + Prefix Information/MTU/RFC 4191 Route Information/RFC 8106 RDNSS options).
• oxipd-net — checksum (RFC 1071 Internet checksum + IPv4/UDP and IPv6/ICMPv6 pseudo-header variants), netlink (async rtnetlink wrapper: link/address/route dump+mutate+event-stream, verified live against the kernel), packet (non- blocking AF_PACKET/SOCK_RAW sockets scoped by EtherType, no kernel BPF filter — see the module docs for why — verified to fail cleanly with EPERM without CAP_NET_RAW).
• oxipd-privsep — fork-based privilege separation: a SOCK_SEQPACKET + SCM_RIGHTS channel, a tagged request/response protocol, capability dropping, and both the synchronous privileged-helper loop and the async engine-side client. Verified end to end (fork → ping → open-a-socket-on-my-behalf → clean shutdown, cargo run -p oxipd-privsep --example roundtrip).
• oxipd-core::arp/ipv4ll — the RFC 5227 probe/announce/defend engine and RFC 3927 IPv4 Link-Local address selection, both with the core policy (conflict detection, address picking) isolated as pure, unit-tested functions.
• oxipd-core::dhcp4 — the whole DHCPv4 client: a pure state machine (Dhcp4Fsm, DISCOVER/OFFER/REQUEST/ACK/NAK/INIT-REBOOT/ARP-probing/RENEW/REBIND/expiry/ RELEASE), pure timing (retransmit/NAK backoff, T1/T2) and lease-extraction modules, a pure message-codec bridge (message, raw_frame — including hand-computed IPv4/UDP checksums for the pre-address-bind window), and the async shell (client) that drives it all over real sockets + netlink. This is the one live-verified end-to-end, per the note above.
• oxipd-core::ipv6::slaac/ipv6nd — SLAAC interface-identifier generation (RFC 4291/2464 Modified EUI-64, RFC 7217 stable-private, RFC 5453 reserved-IID rejection) and the pure Router-Advertisement-processing policy (M/O flag → DHCPv6 mode, RFC 4862 §5.5.3.e's lifetime-floor rule). The stateful router/ prefix-lifecycle tracking and the RS/RA raw-ICMPv6-socket shell aren't built yet.

Not yet done for the DHCPv4 client specifically: default-route installation, lease-file persistence (for INIT-REBOOT across restarts), hook/event execution, and running IPv4LL alongside DHCP. Full uid-dropping while retaining capabilities (running the privsep helper as non-root) needs root to test and is deferred — see oxipd-privsep::privileges's module docs.

crates/
  oxipd-proto/    wire codecs only, no I/O (DHCPv4, DHCPv6, ARP, ND/RA options)
  oxipd-net/      netlink client, raw AF_PACKET/ICMPv6 sockets, checksums
  oxipd-privsep/  privileged-helper process + IPC framework
  oxipd-config/   CLI + TOML config + option tables
  oxipd-core/     state machines: dhcp4, dhcp6, arp, ipv4ll, ipv6nd/slaac, routes
  oxipd-ctl/      control-socket protocol + server
src/main.rs       oxipd daemon binary
src/bin/oxipdctl.rs

cargo build --workspace
cargo test --workspace
cargo clippy --workspace --all-targets -- -D warnings

Requires a Linux target; there is no BSD/Solaris backend by design.