docs: divert verified (matrix + porting notes); FORWARD hook evaluates the out ruleset for transit traffic

docs/en/feature-matrix.md

@@ -59,7 +59,7 @@ As of 2026-11-11; source of per-row evidence: `out/test-logs/`,
 | Feature | Upstream syntax | Milestone | Status |
 |---|---|---|---|
 | `route-to` pools (`rr`, `round-robin`, `source-hash`, `hash`), `reply-to`, `dup-to`, `fail-to` | `pass out route-to (GW 10.0.3.2)` | M4 | PENDING-M4 (Linux route/neigh glue `pf_route` not implemented yet) |
-| `divert-to` / `divert` tag | `pass in … divert-to <host> <port>` | M4 e2e pending | **COMPILES (untested)** — AF_DIVERT family (PF_DIVERT=32) implemented in-module (`module/pfsrc/divert_sock.c`: bind/recvmsg/sendmsg/poll + BSD `divert_output` reinjection semantics); `pdivert` relay in `tools/pdivert/`. Packet-level proof is gate `11-divert.sh` (M4) — lab-only until then. |
+| `divert-to` / `divert` tag | `pass in … divert-to <host> port <n>` | VERIFIED in lab | **Works end-to-end.** The module registers an `AF_DIVERT` socket family (`PF_DIVERT=32`) at runtime — no kernel-tree patch. A `divert-to` rule hands the packet to that family; with no listener the packet is dropped (`divs_noport`, BSD parity); with `tools/pdivert` running the packet is delivered to userspace, rewritten and reinjected (verified with a payload mutation + checksum fix, ping 0% loss). |
 | Queues, default scheduler (priq) | `queue root on wan`, `pfctl -s queue -v` | M5 | COMPILES-untested — `compat/pfk_ifq.c` implements the ifq API with **priq fallback semantics**; `queue` rules parse and load, but packets are not actually shunted through a classful qdisc until M5 |
 | HFSC | `queue on wan { hfsc … }` | M5 | COMPILES-untested — **priq fallback until M5**; `pfsrc/hfsc.c` staged (real OpenBSD 8.0 code) but **not in the module object list** |
 | FQ-CoDel | `queue on wan { fq_codel … }` | M5 | COMPILES-untested — same as HFSC: staged, not built |

docs/porting-notes.md

@@ -860,3 +860,25 @@ ruleset's block line and the resulting state carries the reply).
   at all) on pf0, which looked like a PF failure.  Both now retry and
   verify the copy, and `vm-run-tests.sh` disables pf on pf0 on exit
   (trap) so a failed gate never leaves the lab filtered.
+
+## Divert (M4) — deviations from the OpenBSD implementation
+
+The OpenBSD flow is: `pf.c` tags the mbuf (`PACKET_TAG_PF_DIVERT`,
+`PF_TAG_DIVERTED`) and `netinet/ip_input.c` hands the tagged packet to the
+divert socket.  Linux has no `ip_input` layer to hook, and this port does not
+implement the BSD `divert(4)` `inpcb` plumbing (`ip_divert.c` is kept in the
+tree as reference but is not built).
+
+Decisions taken (all verified in the libvirt lab):
+
+| Topic | OpenBSD | This port |
+|---|---|---|
+| Rule verdict | tag the mbuf, divert later in `ip_input` | hand the packet to the divert family directly at the IN verdict (`pf.c`, `divert_packet()`); the mbuf is verdict-exclusive there |
+| Socket family | `divert(4)` via `divert_attach()`/`inpcb` | `AF_DIVERT` (`PF_DIVERT=32`, `IPPROTO_DIVERT=254`) registered at runtime with `sock_register()` — no kernel-tree patch |
+| Port byte order | network order (`inp_lport`) | network order on both sides (`sin_port` stored raw, `pf_rule.divert.port` is `htons()`ed by pfctl) |
+| Reinjection | `divert_output()` → `ip_output()` | local delivery: synthesised Ethernet header + `netif_rx()` into the ingress device (the device RX path demultiplexes by ethertype) |
+| Re-divert loop | `PF_TAG_DIVERTED_PACKET` | `skb->mark |= PFK_SKIP_PF` — the hook bypasses pf for reinjected packets |
+| Payload mutation | userspace must fix checksums | `pdivert -f` flips the last payload byte and recomputes the ICMP checksum |
+
+`pdivert` (userspace relay, `tools/pdivert/`) is the reference client; it
+demonstrates the BSD "receive -> rewrite -> reinject" cycle.

docs/pt-BR/feature-matrix.md

@@ -59,7 +59,7 @@ Estado em 2026-11-11; evidência por linha: `out/test-logs/`,
 | Feature | Sintaxe de upstream | Milestone | Status |
 |---|---|---|---|
 | Pools de `route-to` (`rr`, `round-robin`, `source-hash`, `hash`), `reply-to`, `dup-to`, `fail-to` | `pass out route-to (GW 10.0.3.2)` | M4 | PENDING-M4 (o glue Linux de rota/neigh `pf_route` ainda não existe) |
-| `divert-to` / tag `divert` | `pass in … divert-to <host> <port>` | e2e pendente (M4) | **COMPILA (não testado)** — família AF_DIVERT (PF_DIVERT=32) implementada no módulo (`module/pfsrc/divert_sock.c`: bind/recvmsg/sendmsg/poll + reinjeção com semântica `divert_output` do BSD); relay `pdivert` em `tools/pdivert/`. A prova fim-a-fim é o gate `11-divert.sh` (M4) — até lá, apenas em lab. |
+| `divert-to` / tag `divert` | `pass in … divert-to <host> port <n>` | VERIFICADO em lab | **Funciona ponta a ponta.** O módulo registra em runtime a família de sockets `AF_DIVERT` (`PF_DIVERT=32`) — sem patch no kernel. A regra `divert-to` entrega o pacote a essa família; sem listener o pacote é descartado (`divs_noport`, paridade BSD); com `tools/pdivert` rodando o pacote vai ao userspace, é reescrito e reinjetado (verificado com mutação de payload + correção de checksum, ping 0% loss). |
 | Filas, agendador default (priq) | `queue root on wan`, `pfctl -s queue -v` | M5 | COMPILES-untested — `compat/pfk_ifq.c` implementa a API ifq com **semântica de fallback priq**; regras `queue` fazem parse e carregam, mas pacotes ainda não são desviados por um qdisc classful até o M5 |
 | HFSC | `queue on wan { hfsc … }` | M5 | COMPILES-untested — **fallback priq até o M5**; `pfsrc/hfsc.c` staged (código real do OpenBSD 8.0) mas **fora da lista de objetos** do módulo |
 | FQ-CoDel | `queue on wan { fq_codel … }` | M5 | COMPILES-untested — igual ao HFSC: staged, não compilado |