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tcp: track zero rwnd errors

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Type: feature

Distinguish between rcv window errors and errors after we advertised a
zero rcv window, i.e., potential window probes.

Change-Id: I6cb453c7aaae456c0a05a8328cfaa55eaca10bf7
Signed-off-by: Florin Coras <fcoras@cisco.com>
(cherry picked from commit a495a3ea146a8484dac9f6b594fb2b044437c7a4)
This commit is contained in:
Florin Coras 2019-08-29 18:33:24 -07:00 committed by Andrew Yourtchenko
parent 6cf2fde9bb
commit a2c0637129
2 changed files with 9 additions and 1 deletions
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3
src/vnet/tcp/tcp_error.def
View File

@ -48,4 +48,5 @@ tcp_error (OPTIONS, "Could not parse options")
tcp_error (PAWS, "PAWS check failed")
tcp_error (RCV_WND, "Segment not in receive window")
tcp_error (FIN_RCVD, "FINs received")
tcp_error (LINK_LOCAL_RW, "No rewrite for link local connection")
tcp_error (LINK_LOCAL_RW, "No rewrite for link local connection")
tcp_error (ZERO_RWND, "Zero receive window")

7
src/vnet/tcp/tcp_input.c
View File

@ -365,6 +365,13 @@ tcp_segment_validate (tcp_worker_ctx_t * wrk, tcp_connection_t * tc0,
*error0 = TCP_ERROR_RCV_WND;
/* If we advertised a zero rcv_wnd and the segment is in the past or the
* next one that we expect, it is probably a window probe */
if ((tc0->flags & TCP_CONN_ZERO_RWND_SENT)
&& seq_lt (vnet_buffer (b0)->tcp.seq_end,
tc0->rcv_las + tc0->rcv_opts.mss))
*error0 = TCP_ERROR_ZERO_RWND;
tc0->errors.below_data_wnd += seq_lt (vnet_buffer (b0)->tcp.seq_end,
tc0->rcv_las);