netdev - [PATCH v2 net-next 03/13] selftest: packetdrill: Define common TCP Fast Open cookie.

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Message-ID: <20250927213022.1850048-4-kuniyu@google.com>
Date: Sat, 27 Sep 2025 21:29:41 +0000
From: Kuniyuki Iwashima <kuniyu@...gle.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Cc: Simon Horman <horms@...nel.org>, Kuniyuki Iwashima <kuniyu@...gle.com>, 
	Kuniyuki Iwashima <kuni1840@...il.com>, netdev@...r.kernel.org
Subject: [PATCH v2 net-next 03/13] selftest: packetdrill: Define common TCP
 Fast Open cookie.

TCP Fast Open cookie is generated in __tcp_fastopen_cookie_gen_cipher().

The cookie value is generated from src/dst IPs and a key configured by
setsockopt(TCP_FASTOPEN_KEY) or net.ipv4.tcp_fastopen_key.

The default.sh sets net.ipv4.tcp_fastopen_key, and the original packetdrill
defines the corresponding cookie as TFO_COOKIE in run_all.py. [0]

Then, each test does not need to care about the value, and we can easily
update TFO_COOKIE in case __tcp_fastopen_cookie_gen_cipher() changes the
algorithm.

However, some tests use the bare hex value for specific IPv4 addresses
and do not support IPv6.

Let's define the same TFO_COOKIE in ksft_runner.sh.

We will replace such bare hex values with TFO_COOKIE except for a single
test for setsockopt(TCP_FASTOPEN_KEY).

Signed-off-by: Kuniyuki Iwashima <kuniyu@...gle.com>
---
 tools/testing/selftests/net/packetdrill/defaults.sh    | 1 +
 tools/testing/selftests/net/packetdrill/ksft_runner.sh | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/tools/testing/selftests/net/packetdrill/defaults.sh b/tools/testing/selftests/net/packetdrill/defaults.sh
index 34fcafefa344..37edd3dc3b07 100755
--- a/tools/testing/selftests/net/packetdrill/defaults.sh
+++ b/tools/testing/selftests/net/packetdrill/defaults.sh
@@ -52,6 +52,7 @@ sysctl -q net.ipv4.tcp_pacing_ca_ratio=120
 sysctl -q net.ipv4.tcp_notsent_lowat=4294967295 > /dev/null 2>&1
 
 sysctl -q net.ipv4.tcp_fastopen=0x3
+# Use TFO_COOKIE in ksft_runner.sh for this key.
 sysctl -q net.ipv4.tcp_fastopen_key=a1a1a1a1-b2b2b2b2-c3c3c3c3-d4d4d4d4
 
 sysctl -q net.ipv4.tcp_syncookies=1
diff --git a/tools/testing/selftests/net/packetdrill/ksft_runner.sh b/tools/testing/selftests/net/packetdrill/ksft_runner.sh
index 3fa7c7f66caf..cc672bf5f58a 100755
--- a/tools/testing/selftests/net/packetdrill/ksft_runner.sh
+++ b/tools/testing/selftests/net/packetdrill/ksft_runner.sh
@@ -9,6 +9,7 @@ declare -A ip_args=(
 		--gateway_ip=192.168.0.1
 		--netmask_ip=255.255.0.0
 		--remote_ip=192.0.2.1
+		-D TFO_COOKIE=3021b9d889017eeb
 		-D CMSG_LEVEL_IP=SOL_IP
 		-D CMSG_TYPE_RECVERR=IP_RECVERR"
 	[ipv6]="--ip_version=ipv6
@@ -16,6 +17,7 @@ declare -A ip_args=(
 		--local_ip=fd3d:0a0b:17d6::1
 		--gateway_ip=fd3d:0a0b:17d6:8888::1
 		--remote_ip=fd3d:fa7b:d17d::1
+		-D TFO_COOKIE=c1d1e9742a47a9bc
 		-D CMSG_LEVEL_IP=SOL_IPV6
 		-D CMSG_TYPE_RECVERR=IPV6_RECVERR"
 )
-- 
2.51.0.536.g15c5d4f767-goog