Provide a concrete packet-loss recovery algorithm for the LossRecovery
interface added in #168: the RFC 6298 round-trip-time estimator and single
retransmission timer.
RTO is a pure, reactive state machine. It derives RTT estimates and
retransmission decisions solely from the segments observed through the
LossRecovery hooks and the monotonic time handed in at each boundary, so it
holds no clock and allocates nothing (issue #140). It tracks a shadow of the
send sequence space (snd.UNA/snd.NXT) purely from observed segments, which is
how it manages the timer without reaching into the ControlBlock and how it
distinguishes retransmissions for Karn's algorithm.
Covered:
- §2.2/§2.3 SRTT/RTTVAR/RTO smoothing (integer-shift form)
- §3 Karn's algorithm: one sample in flight, never sample a retransmit
- §5.1-§5.3 timer arm/restart/stop as data is sent and acknowledged
- §5.4-§5.6 timeout response: exponential backoff + go-back-N retransmit
- §5.7 backoff collapse on a valid RTT sample
- RTO clamped to [rtoMin, rtoMax]
RTT introspection (SmoothedRTT, CurrentRTO, Running) lives on the concrete type,
not the interface, per the LossRecovery design. Install with new(RTO) on
ConnConfig.LossRecovery; the connection calls Reset on open so the zero value is
ready to use.
Generated with LLM assistance.
Signed-off-by: Marvin Drees <marvin.drees@9elements.com>
* feat(tcp): add out-of-order segment reassembly
Add an opt-in, bounded out-of-order reassembly buffer so a single lost
segment can be recovered by retransmitting the gap while later segments
are held and delivered once the gap fills.
The receiver also subtracts buffered out-of-order bytes from the
advertised receive window and avoids challenge-ACK aborts for in-window
future data. Reassembly is disabled by default.
Generated with LLM assistance.
Signed-off-by: Marvin Drees <marvin.drees@9elements.com>
* implement review feedback around rx buffer reuse
Signed-off-by: Marvin Drees <marvin.drees@9elements.com>
---------
Signed-off-by: Marvin Drees <marvin.drees@9elements.com>
Patricio Whittingslow
Marvin 马维 Drees