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rewrite(phase5): udp.hpp — wire Server::Handler to Phase 4 frame-level dispatch - #151

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Part of the v3.0.0 ground-up rewrite (#129, ROADMAP.md Phase 17), branch rewrite/v3-from-c-rcp. Phase 5 (transport layer), Wave 1.

The gap

udp::Server::Handler was shaped to match mock::Server::dispatch()'s single-already-isolated-message contract, so serve() decoded each datagram into individual ACF messages and called Handler once per message. A caller wiring that Handler straight to mock::Server::dispatch() — the obvious, natural thing to do — never reached Phase 4 batch D2's frame-level entry points (dispatch_frame()/dispatch_frame_e2e()), silently losing Table 24 response suppression, conditional/cancellation-opcode routing, and E2E CRC verification/fragment reassembly for every request over UDP.

Note: c-RCP's current udp.c/udp.h have been re-architected into a pure raw-AVTPDU transport with no dispatch wiring at all — this gap is purely internal to cpp-RCP's own design, not a delta versus current c-RCP.

Fix

Widened Server::Handler to a frame-level contract taking raw ACF-region bytes — exactly what dispatch_frame()/dispatch_frame_e2e() accept. New FrameResponse type mirrors mock::FrameMemberResult's response half without udp.hpp needing to #include mock.hpp. Chose widening the signature over a parallel compatibility path — two wiring surfaces would keep inviting the exact mistake this gap describes.

Call sites

tests/test_udp.cpp updated; tls.hpp needed no change (SecureServer::Handler aliases udp::Server::Handler).

Verification

4 new end-to-end tests: multi-member dispatch_frame, Table 24 suppression, a Triggered conditional-opcode request, and an E2E-CRC-protected request via dispatch_frame_e2e. udp.hpp: 747→846 lines. test_udp.cpp: 599→923 lines, 24 TEST_CASEs (151 assertions).

Full tree rebuilds clean (0 errors/warnings), 58/58 ctest suites pass (100%) — independently re-verified from a fresh build.

…l dispatch

Part of the v3.0.0 ground-up rewrite (cpp-RCP #129, ROADMAP.md Phase 17),
branch rewrite/v3-from-c-rcp. Phase 5 (transport layer), Wave 1.

## The gap

udp::Server::Handler was shaped to match mock::Server::dispatch()'s
single-already-isolated-message contract, so Server::serve() decoded
each datagram into individual ACF messages and called Handler once per
message. A caller wiring that Handler straight to mock::Server::
dispatch() -- the obvious, natural thing to do -- never reached
mock.hpp's Phase 4 batch D2 frame-level entry points (dispatch_frame()/
dispatch_frame_e2e()), silently losing Table 24 response suppression,
conditional/cancellation-opcode routing, and E2E CRC verification/
fragment reassembly for every request that goes over UDP.

Note: c-RCP's current src/udp.c/include/rcp/udp.h have been
re-architected into a pure raw-AVTPDU transport (send/recv only) with
no dispatch wiring at all -- that concern is deliberately deferred to
a future layer per udp.h's own comment. This gap is purely internal to
cpp-RCP's own design (where udp::Server bakes in decode+dispatch+
encode), not a delta versus a current c-RCP dispatch implementation.

## Fix

Widened Server::Handler to a frame-level contract:
  using Handler = std::function<size_t(size_t client, avtp::StreamId
      stream_id, uint8_t sequence_num, const std::vector<uint8_t>&
      acf_frame, std::vector<FrameResponse>& out_responses)>;
acf_frame is the raw ACF-region bytes -- exactly the shape mock::
Server::dispatch_frame()/dispatch_frame_e2e() accept. New FrameResponse
type mirrors the response half of mock::FrameMemberResult without
udp.hpp needing to #include mock.hpp. serve() now hands raw bytes
straight through and treats FrameResponse::info.rsp == false as "no
wire message for this member" (Table 24 suppression/queued/pending/
etc.), skipping it from the reply MultiFrame; if every member was
suppressed, no reply datagram is sent at all (previously a reply was
always sent).

Chose widening Handler's own signature over keeping the old
single-message shape as a parallel "compatibility path" -- two wiring
surfaces would keep inviting the exact mistake this gap describes; one
correct surface is safer. Both the real POSIX Server and the Windows
stub Server were updated identically.

## Call sites

tests/test_udp.cpp: every existing handler lambda ported to the new
signature. include/rcp/tls.hpp needed no change (SecureServer::Handler
is just `using Handler = udp::Server::Handler;`, follows automatically
-- confirmed via rcp_tls ctest pass).

## Other findings

No other behavioral deltas found versus c-RCP's current udp.c/udp.h --
its Annex J wrap/unwrap and control port already match cpp-RCP's
existing encode_annexj_datagram/decode_annexj_datagram/
kAnnexJControlPort, left untouched. Documented (via a new test) that
regmap::RequestStreamConfig::rx_resp_stream_index defaults to 1, not 0
(intentional "answer discovery before configuration" power-on
default) -- the suppression test sets it explicitly to 0 to actually
exercise suppression.

## Verification

4 new end-to-end tests wiring a real mock::Server through UDP:
multi-member dispatch_frame, Table 24 suppression (client now
genuinely times out instead of getting a default response), a
Triggered conditional-opcode request (routed to Pending admission, not
mistaken for Standard), and an E2E-CRC-protected request via
dispatch_frame_e2e.

include/rcp/udp.hpp: 747 -> 846 lines. tests/test_udp.cpp: 599 -> 923
lines, test_udp: 24 TEST_CASEs (151 assertions). Full tree rebuilds
clean (0 errors, 0 warnings), 58/58 ctest suites pass (100%) --
independently re-verified from a fresh build, not just the porting
agent's own report.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Signed-off-by: Matt <47545907+SoundMatt@users.noreply.github.com>
@SoundMatt
SoundMatt merged commit 3cc4947 into rewrite/v3-from-c-rcp Aug 22, 2026
22 checks passed
@SoundMatt
SoundMatt deleted the phase5/udp branch August 22, 2026 09:07
SoundMatt added a commit that referenced this pull request Aug 22, 2026
…el dispatch (#152)

* rewrite(phase5): l2.hpp — add FrameHandler wired to Phase 4 frame-level dispatch

Part of the v3.0.0 ground-up rewrite (cpp-RCP #129, ROADMAP.md Phase 17),
branch rewrite/v3-from-c-rcp. Phase 5 (transport layer), Wave 1 (parallel
with udp.hpp's equivalent fix in #151).

## The gap

Server::serve() decoded every inbound frame straight into a MultiFrame
(parsed acf::AcfEntry list) and called Handler once per already-decoded
member -- the same shape as mock::Server::dispatch(), which never
receives a stream_id at all. A caller wiring Handler to
mock::Server::dispatch() can never reach Table 24 suppression (only
reachable via the ten dispatch_<type>() wrappers' stream_id parameter),
never reaches peek_conditional_request_type()/decode_and_dispatch()
so conditional/cancellation-opcode requests get misread as ordinary
Standard requests and executed immediately instead of queued, and
never reaches dispatch_frame()/dispatch_frame_e2e() so E2E/fragment
dispatch is unreachable too.

## Fix

Added a namespace-scope FrameMemberResult (deliberately a parallel
type to mock::Server::FrameMemberResult, not a shared one -- matching
this file's own documented "parallel concrete types, no shared
interface" convention) and a FrameHandler type receiving one whole
frame's raw, unparsed ACF bytes plus its stream_id/sequence_num -- the
exact shape mock::Server::dispatch_frame()/dispatch_frame_e2e()
expect. Two new pure, socket-free helpers, decode_avtp_frame_header()/
decode_l2_frame_header(), split the AVTP envelope off without parsing
the ACF payload, so serve() can hand raw bytes to a FrameHandler
instead of re-encoding an already-parsed MultiFrame. set_frame_handler()
takes priority over the pre-existing Handler when both are set; a
member whose response.rsp == false (Table 24 suppression, a Queued/
Pending outcome, or a frame-level sequence-gate rejection) is dropped
from the outgoing frame, and if every member was dropped, nothing is
sent at all.

The old Handler path is untouched byte-for-byte for backward
compatibility with tests/l2_veth_roundtrip.cpp (a real-frames-over-
real-veth-interfaces CI gate) -- this was a deliberate additive choice
rather than replacing Handler's signature (the sibling udp.hpp fix in
#151 widened Handler directly instead; both are valid shapes for the
same underlying gap, no reconciliation needed since they're
independent files).

## Bug found and fixed (c-RCP delta)

rcp_l2_mac_is_unicast() (c-RCP src/l2.c:79-82, include/rcp/l2.h:121-137,
REQ-L2-011) had no cpp-RCP equivalent anywhere -- added
is_unicast_mac(). Confirmed via repo-wide search that
regmap::writer_ctx()'s via_unicast parameter has no production caller
yet (lifecycle.hpp's REQ-LIFECYCLE-027 unicast gate is data-model-only
today) -- a real content gap worth closing now, but wiring it into a
live dispatch path is a separate, broader gap, documented as
out-of-scope for this batch.

## Verification

Verified in a Docker/Ubuntu 24.04 container with CAP_NET_RAW/
CAP_NET_ADMIN and a real veth pair, replicating ci.yml's exact
l2-veth job flags: clean build (0 errors, 0 warnings), full ctest
58/58, and l2_veth_roundtrip actually EXECUTED (not just compiled)
against real AF_PACKET sockets, both before and after the change. A
scratch program exercising the new FrameHandler path over the same
real veth pair (multi-member dispatch plus a suppressed member
producing no wire response) also passed. macOS build clean, 0/0
warnings, 58/58 ctest (l2_veth_roundtrip is Linux-only, gated
separately -- confirmed absent from the macOS ctest registration as
expected, re-confirmed by the "l2 veth round trip" CI job itself on
this PR).

include/rcp/l2.hpp: 808 -> 1069 lines. tests/test_l2.cpp: 244 -> 596
lines, 11 -> 21 TEST_CASEs (7 new for FrameHandler/Table-24/
conditional-opcode/multi-member/E2E wiring, 3 new for is_unicast_mac).
.fusa-reqs.json: +2 entries (REQ-L2-009, REQ-L2-010).
tests/l2_veth_roundtrip.cpp: unchanged by design (still uses Handler,
exercising raw-socket round-trip fidelity, not dispatch semantics). No
production call site wires l2::Server anywhere else in the tree
(repo-wide grep confirmed), so no other call sites needed updating.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Signed-off-by: Matt <47545907+SoundMatt@users.noreply.github.com>

* fix(l2): cast AvtpFrameHeader::sequence_num (uint16_t) to uint8_t for FrameHandler calls in tests

Fixes an MSVC /W4 /WX narrowing-conversion error (C2220/C4244) at two
new test call sites (test_l2.cpp:525,572) that call FrameHandler's
uint8_t sequence_num parameter directly with hdr.sequence_num
(uint16_t) -- not caught by clang/gcc's warning sets on the other CI
platforms. Test-only, no production code affected.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Signed-off-by: Matt <47545907+SoundMatt@users.noreply.github.com>

---------

Signed-off-by: Matt <47545907+SoundMatt@users.noreply.github.com>
Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>
SoundMatt added a commit that referenced this pull request Aug 22, 2026
…, port deadlock fix (#154)

* rewrite(phase5): shmem.hpp — rebuild Channel around a real bounded byte-level buffer

Part of the v3.0.0 ground-up rewrite (cpp-RCP #129, ROADMAP.md Phase 17),
branch rewrite/v3-from-c-rcp. Phase 5 (transport layer), Wave 2.

A dedicated investigation (this session) found cpp-RCP's shmem.hpp was
a decoded-object pass-through with no byte encoding at all and no
capacity bound -- Channel::request() called a std::function handler
directly and synchronously in the same process. c-RCP's
rcp_shmem_avtp_pair_new() is a real byte-level bounded ring-buffer
transport, real memcpy framing, RCP_ERR_BUSY backpressure when full --
but is ALSO in-process only under the hood (plain heap, non-pshared
mutex/condvar). Neither codebase has ever had genuine cross-process
shared memory; "shmem" means "a fast paired in-process queue" in both
trees. Decision: rebuild Channel around a real byte-level bounded
buffer (closing the two real gaps -- no capacity bound, codec never
exercised) while keeping the existing decoded-object Handler signature
at the boundary (matching udp::Server's own internal-codec/external-
decoded-callback shape), so admin.hpp/config.hpp need zero changes.

## Ported (c-RCP src/shmem.c 266 lines / include/rcp/shmem.h 99 lines)

- shmem.c:68-71 (RCP_ERR_BUSY on full queue) -> Channel's new
  detail::FrameSlots<kMaxQueueCapacity> bounded pool + ErrBusy return,
  REQ-SHMEM-006.
- shmem.c:64-67/109-113 (closed-side send/recv RCP_ERR_CLOSED) ->
  Channel::request()'s existing closed_ check, now cited REQ-SHMEM-005/010.
- The codec-never-exercised gap: Channel::request() now genuinely
  calls acf::encode_acf_abb/encode_acf_gbb and decode_acf_abb/
  decode_acf_gbb (selection mirrors udp.hpp's encode_frame/decode_frame)
  on both the request and response legs before/after the Handler runs.
- shmem.h:91-93's runtime queue_capacity parameter (clamped to min 1,
  shmem.c:204) -> Channel(stream_key, queue_capacity =
  kDefaultQueueCapacity), clamped into [1, kMaxQueueCapacity].

## New shape

Channel keeps its old Handler signature and synchronous, no-thread-
of-its-own dispatch model exactly. Internally, request() now: encodes
-> acquires a fixed-capacity slot (ErrBusy if none free) -> decodes
back out of that slot -> calls Handler with decoded objects (handler
copied out from under a separate mutex and invoked UNLOCKED, so
concurrent callers' handlers genuinely run in parallel) -> encodes/
decodes the response -> releases the slot via RAII. Registry's public
surface is byte-for-byte unchanged -- confirmed by reading all of
admin.hpp/config.hpp/test_admin.cpp/test_config.cpp in full: they only
use Registry::add_channel/deregister/lookup/channels/close and
Channel::stream_key()/new_channel(), never Channel::request()'s
internals. No changes needed to any of the four.

## Bug found and fixed mid-task (real concurrency bug)

The original code held the handler mutex ACROSS the handler call
itself, which would have serialized every concurrent request and
deadlocked under the new capacity tests -- fixed by copying the
handler out under the lock, then invoking it unlocked.

## Architecture note (documented in the header)

Unlike c-RCP's genuinely two-party, strict-FIFO ring (two independent
threads holding *out_a/*out_b), Channel::request() is both producer
and consumer in one synchronous call, so the bounded buffer is a
per-caller indexed slot pool, not a literal head/tail FIFO -- same
capacity bound and BUSY-without-enqueuing contract, no independent-
reader ordering to preserve since there's only ever one reader.

## REQ-SHMEM mapping / c-RCP citation drift found (not propagated)

.fusa-reqs.json was split 2026-08-18 (issue #533) into REQ-SHMEM-001..
010 (not 001..009). Found three req-id mis-citations in c-RCP's own
src/shmem.c inline comments (shmem_side_send citing 007 instead of
006; shmem_side_recv wrongly also citing 006; shmem_side_destroy
citing 007 instead of 008) -- c-RCP's own test_shmem.c citations are
correct, only the .c file's comments drifted; not propagated here.
REQ-SHMEM-004 (recv timeout) and REQ-SHMEM-007 (recv buffer-too-small)
have no analog in the new cpp shape, documented as such rather than
force-fit.

## Verification

include/rcp/shmem.hpp: 173 -> 458 lines. tests/test_shmem.cpp: 170 ->
526 lines, test_shmem: 20 TEST_CASEs (68 assertions), re-run 5x
back-to-back with no flakiness in the new thread/condition-variable-
based backpressure tests. Full tree rebuilds clean (0 errors, 0
warnings), 58/58 ctest suites pass (100%) -- independently re-verified
from a fresh build, not just the porting agent's own report.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Signed-off-by: Matt <47545907+SoundMatt@users.noreply.github.com>

* rewrite(phase5): admin.hpp — fixed-capacity subscriber/counter bounds, port deadlock fix

Part of the v3.0.0 ground-up rewrite (cpp-RCP #129, ROADMAP.md Phase 17),
branch rewrite/v3-from-c-rcp. Phase 5 (transport layer), final module.

## Ported (c-RCP src/admin.c 247 lines / include/rcp/admin.h 177 lines)

- admin.c:109-110 (RCP_ADMIN_MAX_SUBSCRIBERS=16, RCP_ADMIN_MAX_COUNTERS=256)
  -> std::array<..., kMaxSubscribers>/std::array<..., kMaxCounters> bounds
  on Server's subscriber list and counter table, replacing cpp-RCP's
  unbounded std::vector/std::map. Matches this rewrite's fixed-capacity,
  no-dynamic-allocation-on-safety-relevant-paths architecture (already
  applied to server.hpp's admission queue and shmem.hpp's FrameSlots).
- admin.c:133-147 (rcp_admin_server_subscribe, capacity check before
  add) -> Server::subscribe() returns AdminErrc::subscriber_capacity_exceeded
  once kMaxSubscribers is reached, matching c-RCP's fail-closed "cb not
  added" behavior (admin.h:145) rather than growing unbounded.
- admin.c:173-198 (rcp_admin_server_record_counter, capacity check on a
  genuinely new counter name+labels pair) -> counter_capacity_exceeded
  once kMaxCounters distinct counters exist (admin.h:158), existing
  counters still update past the bound.
- Ported c-RCP's two boundary tests (subscribe-at-capacity,
  record_counter-at-capacity) into Catch2 TEST_CASEs.

## Bug found and fixed (real concurrency bug, same class as shmem.hpp/#153)

emit() (ported from rcp_admin_server_emit(), admin.c:149-171) held the
subscriber-list mutex across every subscriber callback invocation --
a subscriber callback that itself calls back into Server (a realistic
pattern for a metrics/event sink) would deadlock. Fixed by copying the
subscriber list out under the lock, then invoking callbacks unlocked --
same fix shape as shmem.hpp's Channel::request() handler-invocation fix
in #153.

## Deliberate non-port, documented in-file

c-RCP's admin.c is caller-driven: rcp_registry_t was retired project-
wide (per c-RCP's own history) and every admin_server_t call site now
passes state in directly rather than looking it up from a live registry.
cpp-RCP's admin.hpp instead holds a reference to shmem::Registry and
looks up endpoint/channel state through it live. NOT migrated to
c-RCP's caller-driven pattern: c-RCP's rationale for going caller-driven
was retiring rcp_registry_t entirely, which doesn't apply here --
shmem::Registry is live, current, and still the single source of truth
for channel state in this rewrite (see shmem.hpp, #153). Reasoning
recorded in admin.hpp's own header comment, not just here.

## Verification

include/rcp/admin.hpp: 128 -> 338 lines. tests/test_admin.cpp: 123 ->
200 lines. Full tree rebuilds clean (0 errors, 0 warnings) from a
from-scratch rebuild against the fully-merged rewrite/v3-from-c-rcp
base (picked up #151/#152/#153 via merge-forward first), 58/58 ctest
suites pass (100%) -- independently re-verified, not just the porting
agent's own report.

## Phase 5 status

udp (#151), l2 (#152), shmem (#153) already merged; this closes out
admin, the fourth and final "port from c-RCP" module in Phase 5's
scope. tls/capi remain as re-verify-only per ROADMAP.md Phase 17 —
confirmed clean against the new core, no content changes needed.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Signed-off-by: Matt <47545907+SoundMatt@users.noreply.github.com>

---------

Signed-off-by: Matt <47545907+SoundMatt@users.noreply.github.com>
Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>
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