lib: Add FIN and receive-side linger for msg deallocbe

qos_msg flows had no end-of-stream signal: a deallocating sender
relied on the peer's inactivity timers (~30 s) to notice. Worse, the
dealloc-linger path was bugged: a receiver that called flow_dealloc
would stop draining its rx_rb while the peer's tail retransmits kept
arriving. Peer retransmitted into a black hole until its own dealloc
fired, and the whole shutdown stretched takes t_a time.

Generalizes frcti_stream_fin_snd to frcti_fin_snd; for msg mode emit a
FRCT_FIN-only control packet with the FIN seqno boundary in
pci->ackno. Receiver-side frcti_rcv latches rcv_fin_seen and stores
the boundary on FRCT_FIN-without-DATA.

Fix comment on the FRCT flags.

Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/lib/dev.c b/src/lib/dev.c
index 13c7544b..ae0401b7 100644
--- a/src/lib/dev.c
+++ b/src/lib/dev.c
@@ -1342,10 +1342,10 @@ int fccntl(int fd,
                 new_acc = flow->oflags & FLOWFACCMODE;
 
                 /* Defer EOS emit until after proc.lock is dropped: */
-                /* frcti_stream_fin_snd may block on shm-pool/tx-rb. */
+                /* frcti_fin_snd may block on shm-pool/tx-rb. */
                 if (new_acc == FLOWFRDONLY
                     && old_acc != FLOWFRDONLY
-                    && FRCTI_IS_STREAM(flow->frcti))
+                    && flow->frcti != NULL)
                         emit_eos = true;
 
                 rx_acl = ssm_rbuff_get_acl(flow->rx_rb);
@@ -1457,7 +1457,7 @@ int fccntl(int fd,
         pthread_rwlock_unlock(&proc.lock);
 
         if (emit_eos)
-                frcti_stream_fin_snd(flow->frcti);
+                frcti_fin_snd(flow->frcti);
 
         va_end(l);