soypat/lneto
1
0
Fork 0
mirror of https://github.com/soypat/lneto.git synced 2026-08-23 07:59:05 +00:00
Code Issues Packages Projects Releases 1 Wiki Activity

Implement basic retransmit queue reset method (#52)

Browse Source 
* implement basic retransmit queue reset method

* tcp: rto reset on new ack; accept ack after retransmit bugfix
This commit is contained in:
Pat Whittingslow
2026-03-05 21:35:16 +01:00
committed by GitHub
parent 06bd6b28dd
commit 270b8df043
8 changed files with 345 additions and 54 deletions
Download Patch File Download Diff File Expand all files Collapse all files
tcp/control.go
+24 -5
View File
@@ -493,11 +493,24 @@ func (tcb *ControlBlock) validateIncomingSegment(seg Segment) (err error) {
}
case established && acksUnsentData:
err = errDropSegment
tcb.pending[0] |= FlagACK // Send ACK for unsent data; |= preserves any pending FIN.
if isDebug {
tcb.debug("rcv:ACK-unsent", slog.String("state", tcb._state.String()),
slog.Uint64("seg.ack", uint64(seg.ACK)), slog.Uint64("snd.nxt", uint64(tcb.snd.NXT)))
// After Retransmit() rewinds snd.NXT to snd.UNA, the remote may ACK
// data it received pre-rewind — a valid cumulative ACK that exceeds
// the rewound snd.NXT. Detect this case (NXT==UNA means rewind active)
// and accept the ACK if within the send window.
retransmitActive := tcb.snd.NXT == tcb.snd.UNA
if retransmitActive && seg.ACK.InWindow(tcb.snd.UNA, tcb.snd.WND) {
tcb.snd.NXT = seg.ACK
if isDebug {
tcb.debug("rcv:ACK-advance-nxt", slog.String("state", tcb._state.String()),
slog.Uint64("seg.ack", uint64(seg.ACK)), slog.Uint64("snd.nxt", uint64(tcb.snd.NXT)))
}
} else {
err = errDropSegment
tcb.pending[0] |= FlagACK // Send ACK for unsent data; |= preserves any pending FIN.
if isDebug {
tcb.debug("rcv:ACK-unsent", slog.String("state", tcb._state.String()),
slog.Uint64("seg.ack", uint64(seg.ACK)), slog.Uint64("snd.nxt", uint64(tcb.snd.NXT)))
}
}
case preestablished && (acksOld || acksUnsentData):
@@ -562,6 +575,12 @@ func (tcb *ControlBlock) rstJump() Value {
return 100
}
// Retransmit resets snd.NXT back to snd.UNA, allowing the next PendingSegment
// and Send calls to retransmit unacknowledged data. Must be paired with
// ringTx.RetransmitFromUNA to rewind the transmit buffer.
// Implements RFC 9293 §3.10.8 (RETRANSMISSION TIMEOUT).
func (tcb *ControlBlock) Retransmit() { tcb.snd.NXT = tcb.snd.UNA }
// Abort sets ControlBlock state to Closed and resets all sequence numbers and pending flag.
// No more data can be sent nor received after the connection is aborted until opened again.
// An abort call prepares the connection for opening an active connection via a