tools/testing/selftests/net/packetdrill/tcp_sack_sack-shift-sacked-2-6-8-3-9-nofack.pkt

Source file repositories/reference/linux-study-clean/tools/testing/selftests/net/packetdrill/tcp_sack_sack-shift-sacked-2-6-8-3-9-nofack.pkt

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/net/packetdrill/tcp_sack_sack-shift-sacked-2-6-8-3-9-nofack.pkt
Extension
.pkt
Size
2475 bytes
Lines
65
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: tools
Status
atlas-only

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0
// Test shifting of newly-SACKed ranges onto the previous already-SACKed skb.
// This variant tests non-FACK SACK with SACKs coming in the order
// 2 6 8 3 9, to test what happens when we get a new SACKed range
// (for packet 3) that is on the right of an existing SACKed range
// (for packet 2).

`./defaults.sh`

// Establish a connection and send 10 MSS.
    0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
   +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
   +0 bind(3, ..., ...) = 0
   +0 listen(3, 1) = 0

   +0 < S 0:0(0) win 32792 <mss 1000,sackOK,nop,nop,nop,wscale 7>
   +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
  +.1 < . 1:1(0) ack 1 win 1024
   +0 accept(3, ..., ...) = 4

   +0 write(4, ..., 10000) = 10000
   +0 > P. 1:10001(10000) ack 1

  +.1 < . 1:1(0) ack 1 win 257 <sack 2001:3001,nop,nop>
+.001 < . 1:1(0) ack 1 win 257 <sack 2001:3001 6001:7001,nop,nop>
+.001 < . 1:1(0) ack 1 win 257 <sack 2001:3001 6001:7001 8001:9001,nop,nop>

// 3 SACKed packets, so we enter Fast Recovery.
   +0 > . 1:1001(1000) ack 1
   +0 %{ assert tcpi_ca_state == TCP_CA_Recovery, tcpi_ca_state }%
   +0 %{ assert tcpi_lost == 6, tcpi_lost }%

// SACK for 3001:4001.
// This SACK for an adjacent range causes the sender to
// shift the newly-SACKed range onto the previous skb.
+.007 < . 1:1(0) ack 1 win 257 <sack 2001:4001 6001:7001 8001:9001,nop,nop>
   +0 > . 1001:2001(1000) ack 1
   +0 %{ assert tcpi_lost == 5, tcpi_lost }%
   +0 %{ assert tcpi_reordering == 6, tcpi_reordering }%   // 8001:9001 -> 3001:4001 is 6

// SACK for 9001:10001.
 +.01 < . 1:1(0) ack 1 win 257 <sack 2001:4001 6001:7001 8001:10001,nop,nop>
   +0 %{ assert tcpi_lost == 5, tcpi_lost }%

// ACK for 1:1001 as packets from t=0.303 arrive.
+.083 < . 1:1(0) ack 1001 win 257 <sack 2001:4001 6001:7001 8001:10001,nop,nop>
   +0 %{ assert tcpi_lost == 4,tcpi_lost }%

// ACK for 1:4001 as packets from t=0.310 arrive.
+.017 < . 1:1(0) ack 4001 win 257 <sack 6001:7001 8001:10001,nop,nop>
   +0 %{ assert tcpi_lost == 3,tcpi_lost }%

// ACK for 1:7001 as packets from t=0.320 arrive.
 +.01 < . 1:1(0) ack 7001 win 257 <sack 8001:10001,nop,nop>

// ACK for all data as packets from t=0.403 arrive.
  +.1 < . 1:1(0) ack 10001 win 257
   +0 %{
assert tcpi_ca_state == TCP_CA_Open, tcpi_ca_state
assert tcpi_unacked == 0, tcpi_unacked
assert tcpi_sacked == 0, tcpi_sacked
assert tcpi_lost == 0, tcpi_lost
assert tcpi_retrans == 0, tcpi_retrans
}%

Annotation

Implementation Notes