lib: Update FRCP implementation

2026-05-20T06:17:07+00:00

The Flow and Retransmission Control Protocol (FRCP) runs end-to-end between two peers over a flow. It provides reliability, in-order delivery, flow control, and liveness. Note that congestion avoidance is orthogonal to FRCP and handled in the IPCP. A fixed 16-octet header, network byte order, is prefixed to every FRCP packet: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | flags | hcs | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | window | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | seqno | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ackno | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | payload (variable) ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ hcs is a CRC-16-CCITT-FALSE checksum over the PCI (and the stream extension when present), verified before any flag-driven dispatch. A single packet can simultaneously carry DATA + ACK + FC + RXM by OR-ing flag bits. An optional CRC trailer covers the body on DATA when qs.ber == 0, and on every SACK packet; an optional AEAD wrap (per-flow keys) sits outermost. Flag bits (MSB-first; bits 13..15 reserved, MUST be zero): +------+--------+--------+----------------------------------------+ | Bit | Mask | Name | Meaning | +------+--------+--------+----------------------------------------+ | 0 | 0x8000 | DATA | Carries caller payload | | 1 | 0x4000 | DRF | Start of a fresh data run | | 2 | 0x2000 | ACK | ackno field valid | | 3 | 0x1000 | NACK | Pre-DRF nudge (seqno informational) | | 4 | 0x0800 | FC | window field valid (rwe advertisement) | | 5 | 0x0400 | RDVS | Rendezvous probe (window-closed) | | 6 | 0x0200 | FFGM | First Fragment of a multi-fragment SDU | | 7 | 0x0100 | LFGM | Last Fragment of a multi-fragment SDU | | 8 | 0x0080 | RXM | Retransmission | | 9 | 0x0040 | SACK | Block list follows in payload | | 10 | 0x0020 | RTTP | RTT probe / echo (payload follows) | | 11 | 0x0010 | KA | Keepalive | | 12 | 0x0008 | FIN | End of stream marker | | 13-15| -- | -- | Reserved (MUST be zero) | +------+--------+--------+----------------------------------------+ (FFGM, LFGM) encodes the fragment role of a DATA packet (SCTP-style B/E): 11=SOLE, 10=FIRST, 00=MID, 01=LAST. Each fragment carries its own seqno; Retransmission recovers fragments individually, reassembly runs at consume time. In stream mode FFGM/LFGM are unused; per-byte position is carried by the stream extension below and end-of-stream is signalled by FIN on a 0-byte DATA packet. SACK payload (FRCT_ACK | FRCT_FC | FRCT_SACK): 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | n_blocks | padding (2 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | start[0] | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | end[0] | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... n_blocks pairs total ... Each block describes a *present* (received) range strictly above the cumulative ACK in the PCI ackno. D-SACK (RFC 2883) is signalled in-band as block[0] - no flag bit, no extra framing - and consumed by the RACK reo_wnd_mult scaler (RFC 8985 sec. 7.2). RTTP payload (FRCT_RTTP only; 24 octets): 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | probe_id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | echo_id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + nonce (16 octets, echoed verbatim) + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Stream PCI extension (in_order == STREAM only; 8 octets after the base PCI on every DATA packet): 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | start | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | end | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ start, end are monotonic 32-bit byte offsets; end - start equals the on-wire payload length. Stream mode is negotiated at flow allocation; the extension is present iff stream mode is in use, never on a per-packet basis. Service modes are an orthogonal (in_order, loss, ber) vector selected at flow_alloc; the cubes above map to the axes: +----------------+---------+------+-----+-----------------------+ | Cube | in_order| loss | ber | Engaged | +----------------+---------+------+-----+-----------------------+ | qos_raw | 0 | 1 | 1 | Raw passthrough | | qos_raw_safe | 0 | 1 | 0 | Raw + CRC trailer | | qos_rt | 1 | 1 | 1 | FRCP, no FRTX, no CRC | | qos_rt_safe | 1 | 1 | 0 | FRCP, no FRTX, CRC | | qos_msg | 1 | 0 | 0 | FRCP + FRTX | | qos_stream | 2 | 0 | 0 | FRCP + FRTX, stream | +----------------+---------+------+-----+-----------------------+ in_order=0 sends raw datagrams with no PCI (UDP-equivalent); in_order=1 engages FRCP with SDU framing; in_order=2 (stream) requires loss=0 and is rejected otherwise. loss=0 engages the FRTX retransmit machinery. ber=0 appends the CRC-32 trailer; QOS_DISABLE_CRC at build time forces ber=1 for development. Encryption is a separate per-flow attribute layered as an AEAD wrap outside the FRCP packet. Heritage: delta-t (Watson 1981) supplies timer-based connection management - no SYN/FIN handshake, the DRF marker, the t_mpl / t_a / t_r timers. RINA (Day 2008) supplies the unified flow_alloc(name, qos, ...) primitive and the orthogonal QoS-cube axes. Loss detection follows TCP/QUIC practice (RFCs 2018, 2883, 6582, 6298, 8985); RTT probing is nonce-authenticated like QUIC PATH_CHALLENGE. Adds oftp, a minimal file-transfer tool over an FRCP stream flow. The client reads from stdin or --in FILE and writes through a flow_alloc(qos_stream); the server (--listen) calls flow_accept and writes to stdout or --out FILE. Both sides compute a CRC-64/NVMe over the bytes they handle and print the result. The server rejects flows whose negotiated qs.in_order != STREAM. Two FRCP knobs are exposed via env vars on either side: OFTP_FRCT_RTO_MIN fccntl FRCTSRTOMIN (ns) OFTP_FRCT_STREAM_RING_SZ fccntl FRCTSRRINGSZ (octets) The ocbr_client gains an OCBR_QOS env var to pick the cube the client uses for flow_alloc; recognised values are raw, safe, rt, rt_safe, msg, stream. Unknown values fall back to raw with a warning on stderr. Without the env set behaviour is unchanged. Removes the deprecated lib/timerwheel.c Signed-off-by: Dimitri Staessens Signed-off-by: Sander Vrijders

lib: Use push/pop for ssm_pk_buff ops

2026-05-20T06:17:06+00:00

Renames the allocation for head/tail to push/pop instead of alloc/release as it's simpler and shorter. Took this approach insted of adopting the kernel's push/pull/put/trim. Signed-off-by: Dimitri Staessens Signed-off-by: Sander Vrijders

irmd: Pass MTU from IPCP to process for FRCT

2026-05-20T06:17:06+00:00

FRCT needs to know the MTU for fragmentation. The MTU is now passed from the layer serving the flow to the process as part of flow allocation. Signed-off-by: Dimitri Staessens Signed-off-by: Sander Vrijders

lib: Rename PROG_* config to PROC_*

2026-05-20T06:17:06+00:00

Per-process flow / fd / fqueue limits are properties of a process, not a program; align the naming. Mechanical rename of PROG_MAX_FLOWS, PROG_RES_FDS, and PROG_MAX_FQUEUES to PROC_*. Signed-off-by: Dimitri Staessens Signed-off-by: Sander Vrijders

ipcpd: Validate wire frame lengths

2026-05-20T06:17:03+00:00

Asserting frame lengths coming from the wire was a severe flaw. Fixed by gracefully dropping runt frames. Signed-off-by: Dimitri Staessens Signed-off-by: Sander Vrijders

lib: Fix certificate DER encoding and key buffers

2026-03-14T10:23:59+00:00

i2d_X509() allocated buf->data via OPENSSL_malloc(), but callers free it with freebuf() which uses free(). Fix by allocating with malloc() and encoding directly into the buffer. Also replaces MSGBUFSZ with CRYPT_KEY_BUFSZ (4096) for key material buffers and removes leftover debug logging. Signed-off-by: Dimitri Staessens Signed-off-by: Sander Vrijders

ipcpd: Skip vertices with empty forwarding lists

2026-02-22T15:05:00+00:00

Fixes ECMP routing table to skip unreachable vertices with empty forwarding lists, avoiding uninitialized nhop access. Replace inner vertex list walk with bounded index loop instead of using a list_for_each to track indices (which confuses the static analyzer as it seems it can't prove the index remains valid). Remove spurious free(*dist) on ECMP success path (caller frees). Extract edge cleanup into free_edges helper in del_vertex to avoid a static analyzer false positive. Signed-off-by: Dimitri Staessens Signed-off-by: Sander Vrijders

ipcpd: Fix unused values in unicast IPCP

2026-02-22T15:04:16+00:00

Use the key in the store operation in the DHT, to avoid static analyzer seeing it as being set without being used in release builds. The length of the packet buffer is only used when tracking DT stats, so should be set within the IPCP_FLOW_STATS guard. Signed-off-by: Dimitri Staessens Signed-off-by: Sander Vrijders

ipcpd: Fix lsdb being renamed to lspb

2026-02-18T07:00:14+00:00

A recent bulk rename of sdb -> spb (shm du buff to shm pkt buff) unintentionally renamed the lsdb. Signed-off-by: Dimitri Staessens Signed-off-by: Sander Vrijders

lib: Add struct llist for lists tracking len

2026-02-18T06:58:21+00:00

The DHT uses a struct {struct list_head, size_t len} pattern, which is also useful in the registry and other places. Having a struct llist (defined in list.h) with consistent macros for addition/deletion etc removes a lot of duplication and boilerplate and reduces the risk of inconsistent updates. The list management is now a macro-only implementation. Signed-off-by: Dimitri Staessens Signed-off-by: Sander Vrijders

ouroboros/src/ipcpd/unicast, branch be

lib: Update FRCP implementation

lib: Use push/pop for ssm_pk_buff ops

irmd: Pass MTU from IPCP to process for FRCT

lib: Rename PROG_* config to PROC_*

ipcpd: Validate wire frame lengths

lib: Fix certificate DER encoding and key buffers

ipcpd: Skip vertices with empty forwarding lists

ipcpd: Fix unused values in unicast IPCP

ipcpd: Fix lsdb being renamed to lspb

lib: Add struct llist for lists tracking len