Commit f5fda1a8 authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

selftests/net: packetdrill: add tcp_rcv_big_endseq.pkt 



This test checks TCP behavior when receiving a packet beyond the window.

It checks the new TcpExtBeyondWindow SNMP counter.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarKuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20250711114006.480026-4-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 6c758062

tools/testing/selftests/net/packetdrill/tcp_rcv_big_endseq.pkt

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+44 −0
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// SPDX-License-Identifier: GPL-2.0



--mss=1000



`./defaults.sh`



    0 `nstat -n`



// Establish a connection.

   +0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3

   +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0

   +0 setsockopt(3, SOL_SOCKET, SO_RCVBUF, [10000], 4) = 0

   +0 bind(3, ..., ...) = 0

   +0 listen(3, 1) = 0



   +0 < S 0:0(0) win 32792 <mss 1000,nop,wscale 7>

   +0 > S. 0:0(0) ack 1 <mss 1460,nop,wscale 0>

  +.1 < . 1:1(0) ack 1 win 257



  +0 accept(3, ..., ...) = 4



  +0 < P. 1:4001(4000) ack 1 win 257

  +0 > .  1:1(0) ack 4001 win 5000



// packet in sequence : SKB_DROP_REASON_TCP_INVALID_END_SEQUENCE / LINUX_MIB_BEYOND_WINDOW

  +0 < P. 4001:54001(50000) ack 1 win 257

  +0 > .  1:1(0) ack 4001 win 5000



// ooo packet. : SKB_DROP_REASON_TCP_INVALID_END_SEQUENCE / LINUX_MIB_BEYOND_WINDOW

  +1 < P. 5001:55001(50000) ack 1 win 257

  +0 > .  1:1(0) ack 4001 win 5000



// SKB_DROP_REASON_TCP_INVALID_SEQUENCE / LINUX_MIB_BEYOND_WINDOW

  +0 < P. 70001:80001(10000) ack 1 win 257

  +0 > .  1:1(0) ack 4001 win 5000



  +0 read(4, ..., 100000) = 4000



// If queue is empty, accept a packet even if its end_seq is above wup + rcv_wnd

  +0 < P. 4001:54001(50000) ack 1 win 257

  +.040 > .  1:1(0) ack 54001 win 0



// Check LINUX_MIB_BEYOND_WINDOW has been incremented 3 times.

+0 `nstat | grep TcpExtBeyondWindow | grep -q " 3 "`