- u_async.c: process immediate_queue BEFORE epoll_wait in uasync_poll
- stcp_link.c: defensive NULL etcp_conn/etcp_link in stcp_link_close
- utun_instance.c: move stcp_server_list_destroy_all to Phase J (before ETCP),
add deferred drain in both Phase J and L
- stcp.h/c: STCP_HS_ENC_CLIENT 6→38, STCP_HS_ENC_SERVER 7→39,
exchange ed25519_pubkey in both handshake directions
- etcp_connections.c: copy peer_ed25519 from STCP to ETCP_CONN in
etcp_link_enter_ready_tcp; guard link->etcp in tcp_link_close_cb
- chat_sync.c: fix lk->conn NULL dereference for TCP links
- test_stcp.c: update stcp_server_create/stcp_client_connect callsites
- tools/chat_tcp_test: change transport udp→tcp
rx_acked was used for two conflicting purposes:
1. remote ack of our sends (inflight = tx_seq - rx_acked)
2. our last sent ACK seq (dedup: rx_seq != rx_acked)
When the ack timer fired and set rx_acked = rx_seq, it overwrote
the inflight-tracking value. If rx_seq > tx_seq, the computation
tx_seq - rx_acked underflowed (e.g. 18 - 24 = 0xFFFFFFFA),
permanently blocking router_drain_send_q and causing send_q to
grow indefinitely.
Fix:
- Split rx_acked into tx_acked (remote ack, for inflight) and
last_sent_ack_seq (our ACK, for dedup)
- Incoming ACK handler only advances tx_acked forward (stale guard)
- Use int32_t cast on all inflight comparisons to handle stale states
- Add etcp_router architecture diagram (doc/etcp_router_arch.md)
evgeny