l4p/tcp: Reset wscale when timestamp is not set

wscale value calculation and handling is tightly coupled with timestamp
value. When timestamp sending is off on the other end of the connection,
wscale is being wrongly calculated, which leads to traffic being stuck.
To overcome that issue, wscale value needs to be reset during handshake
when timestamps are off. It results with slower connection, but traffic
is sustained.

Here are ofo/lost segment test script results, which were run with and
without timestamps set.

Test		Protocol File	Status	Time		Time
					timestmaps on	timestamps off
Reorder 4	ipv4	 8MB	[OK]	1m12.594s	0m58.419s
Reorder 9	ipv4	 8MB	[OK]	0m27.260s	0m31.142s
Reorder 4	ipv4	 8MB	[OK]	0m58.093s	1m34.772s
Reorder 9	ipv4	 8MB	[OK]	0m28.798s	0m34.016s
Loss 0		ipv4	 8MB	[OK]	0m0.047s	0m0.046s
Loss 20		ipv4	 8MB	[OK]	2m34.807s	2m20.491s
Loss 0		ipv4	 8MB	[OK]	0m0.047s	0m0.047s
Loss 20		ipv4	 8MB	[OK]	0m57.360s	2m15.736s
Reorder 4	ipv6	 8MB	[OK]	1m0.237s	0m46.347s
Reorder 9	ipv6	 8MB	[OK]	0m25.977s	0m32.035s
Reorder 4	ipv6	 8MB	[OK]	0m53.248s	0m50.953s
Reorder 9	ipv6	 8MB	[OK]	0m26.501s	0m29.248s
Loss 0		ipv6	 8MB	[OK]	0m0.044s	0m0.042s
Loss 20		ipv6	 8MB	[OK]	1m0.388s	2m14.005s
Loss 0		ipv6	 8MB	[OK]	0m0.045s	0m0.042s
Loss 20		ipv6	 8MB	[OK]	0m58.344s	2m1.191s

Signed-off-by: Mariusz Drost <mariuszx.drost@intel.com>
Change-Id: Id89823409e5e6a87722689d0c2322de7ef0f6cf9

diff --git a/lib/libtle_l4p/tcp_rxtx.c b/lib/libtle_l4p/tcp_rxtx.c
index b71a565..b4bc626 100644 (file)
--- a/lib/libtle_l4p/tcp_rxtx.c
+++ b/lib/libtle_l4p/tcp_rxtx.c
@@ -653,6 +653,10 @@ sync_ack(struct tle_tcp_stream *s, const union pkt_info *pi,
                m->l2_len + m->l3_len);
        get_syn_opts(&s->tcb.so, (uintptr_t)(th + 1), m->l4_len - sizeof(*th));
 
+       /* reset wscale option if timestamp is not present */
+       if (s->tcb.so.ts.val == 0)
+               s->tcb.so.wscale = 0;
+
        s->tcb.rcv.nxt = si->seq + 1;
        seq = sync_gen_seq(pi, s->tcb.rcv.nxt, ts, s->tcb.so.mss,
                                s->s.ctx->prm.hash_alg,