Fix TCP loss recovery, VPP-745
Allows pure loss recovery retransmits only on timeout.
Change-Id: I563cdbf9e7b890a6569350bdbda4f746ace0544e
Signed-off-by: Florin Coras <fcoras@cisco.com>
diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c
index 0030cfe..e9c52c5 100644
--- a/src/vnet/tcp/tcp_input.c
+++ b/src/vnet/tcp/tcp_input.c
@@ -392,11 +392,10 @@
/* Karn's rule, part 1. Don't use retransmitted segments to estimate
* RTT because they're ambiguous. */
- if (tc->rtt_seq && seq_gt (ack, tc->rtt_seq) && !tc->rto_boff)
+ if (tc->rtt_ts && seq_geq (ack, tc->rtt_seq) && !tc->rto_boff)
{
mrtt = tcp_time_now () - tc->rtt_ts;
}
-
/* As per RFC7323 TSecr can be used for RTTM only if the segment advances
* snd_una, i.e., the left side of the send window:
* seq_lt (tc->snd_una, ack). Note: last condition could be dropped, we don't
@@ -406,19 +405,22 @@
mrtt = tcp_time_now () - tc->opt.tsecr;
}
+ /* Allow measuring of a new RTT */
+ tc->rtt_ts = 0;
+
+ /* If ACK moves left side of the wnd make sure boff is 0, even if mrtt is
+ * not valid */
+ if (tc->bytes_acked)
+ tc->rto_boff = 0;
+
/* Ignore dubious measurements */
if (mrtt == 0 || mrtt > TCP_RTT_MAX)
return 0;
tcp_estimate_rtt (tc, mrtt);
-
tc->rto = clib_min (tc->srtt + (tc->rttvar << 2), TCP_RTO_MAX);
- /* Allow measuring of RTT and make sure boff is 0 */
- tc->rtt_seq = 0;
- tc->rto_boff = 0;
-
- return 1;
+ return 0;
}
/**
@@ -735,7 +737,7 @@
{
u8 partial_ack;
- if (tcp_in_cong_recovery (tc))
+ if (tcp_in_fastrecovery (tc))
{
partial_ack = seq_lt (tc->snd_una, tc->snd_congestion);
if (!partial_ack)
@@ -749,6 +751,7 @@
/* Clear retransmitted bytes. XXX should we clear all? */
tc->rtx_bytes = 0;
+
tc->cc_algo->rcv_cong_ack (tc, TCP_CC_PARTIALACK);
/* In case snd_nxt is still in the past and output tries to
@@ -772,6 +775,13 @@
tc->cc_algo->rcv_ack (tc);
tc->tsecr_last_ack = tc->opt.tsecr;
tc->rcv_dupacks = 0;
+ if (tcp_in_recovery (tc))
+ {
+ tc->rtx_bytes -= clib_min (tc->bytes_acked, tc->rtx_bytes);
+ tc->rto = clib_min (tc->srtt + (tc->rttvar << 2), TCP_RTO_MAX);
+ if (seq_geq (tc->snd_una, tc->snd_congestion))
+ tcp_recovery_off (tc);
+ }
}
}
@@ -897,7 +907,7 @@
tcp_cc_rcv_ack (tc, b);
/* If everything has been acked, stop retransmit timer
- * otherwise update */
+ * otherwise update. */
if (tc->snd_una == tc->snd_una_max)
tcp_retransmit_timer_reset (tc);
else
@@ -1778,6 +1788,11 @@
tcp_send_reset (b0, is_ip4);
goto drop;
}
+
+ /* Update rtt and rto */
+ tc0->bytes_acked = 1;
+ tcp_update_rtt (tc0, vnet_buffer (b0)->tcp.ack_number);
+
/* Switch state to ESTABLISHED */
tc0->state = TCP_STATE_ESTABLISHED;