From 752e0662303a187002310a5ce5d2cf8517ce1ae6 Mon Sep 17 00:00:00 2001
From: Maxim Galaganov <max@internet.ru>
Date: Thu, 25 Nov 2021 13:50:26 +0300
Subject: [PATCH] mptcp: sockopt: add coverage for TCP_CORK and TCP_NODELAY

Add coverage for new socket options that allow changing behavior of
Nagle's algorithm on MPTCP sockets.

Link: https://lore.kernel.org/mptcp/20211123070708.2897469-1-max@internet.ru/T/
Link: https://github.com/multipath-tcp/packetdrill/pull/75
Signed-off-by: Maxim Galaganov <max@internet.ru>
---
 .../mptcp/sockopts/sockopt_cork_nodelay.pkt   | 53 +++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 gtests/net/mptcp/sockopts/sockopt_cork_nodelay.pkt

diff --git a/gtests/net/mptcp/sockopts/sockopt_cork_nodelay.pkt b/gtests/net/mptcp/sockopts/sockopt_cork_nodelay.pkt
new file mode 100644
index 00000000..5da40eea
--- /dev/null
+++ b/gtests/net/mptcp/sockopts/sockopt_cork_nodelay.pkt
@@ -0,0 +1,53 @@
+// derived from tcp/nagle/sockopt_cork_nodelay.pkt
+--tolerance_usecs=100000
+`../common/defaults.sh`
+
+
++0.0   socket(..., SOCK_STREAM, IPPROTO_MPTCP) = 3
++0.0   setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
++0.0   setsockopt(3, SOL_TCP, TCP_CORK, [1], 4) = 0
+
++0     bind(3, ..., ...) = 0
++0     listen(3, 1) = 0
+
++0.0    <  S   0:0(0)               win 65535  <mss 1460, sackOK, TS val 4074410674 ecr 0,          nop, wscale 8, mpcapable v1 flags[flag_h] nokey>
++0.0    >  S.  0:0(0)       ack 1              <mss 1460, sackOK, TS val 4074410674 ecr 4074410674, nop, wscale 8, mpcapable v1 flags[flag_h] key[skey]>
++0.0    <   .  1:1(0)       ack 1   win 256    <nop, nop,         TS val 4074410674 ecr 4074410674,                mpcapable v1 flags[flag_h] key[ckey=2, skey]>
++0     accept(3, ..., ...) = 4
+
+// check that TCP_CORK was synced from listener
++0.0   getsockopt(4, SOL_TCP, TCP_CORK,  [1], [4]) = 0
+
++0.0   write(4, ..., 40) = 40
++0.05  write(4, ..., 40) = 40
+
+// clearing TCP_CORK should push pending bytes out
++0.01  setsockopt(4, SOL_TCP, TCP_CORK, [0], 4) = 0
++0.0    >  P.  1:81(80)     ack 1              <nop, nop, TS val 448955294 ecr 448955294,   dss dack4=1  dsn8=1   ssn=1    dll=80  nocs, nop, nop>
++0.01   <   .  1:1(0)       ack 81  win 256    <nop, nop, TS val 448955294 ecr 448955294,   dss dack4=81 nocs>
+
+// set TCP_CORK once again
++0.0   setsockopt(4, SOL_TCP, TCP_CORK, [1], 4) = 0
++0.0   write(4, ..., 40) = 40
++0.05  write(4, ..., 40) = 40
+
+// setting TCP_NODELAY on a socket with TCP_CORK should push pending bytes out
++0.0   setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = 0
++0.0    >  P.  81:161(80)   ack 1              <nop, nop, TS val 448955294 ecr 448955294,   dss dack4=1   dsn8=81  ssn=81  dll=80  nocs, nop, nop>
++0.1    <   .  1:1(0)       ack 161 win 256    <nop, nop, TS val 448955294 ecr 448955294,   dss dack4=161 nocs>
+
+// TCP_CORK has priority over TCP_NODELAY
++0.0   write(4, ..., 1) = 1
++0.01  write(4, ..., 1) = 1
++0.2    >  P.  161:163(2)   ack 1              <nop, nop, TS val 448955294 ecr 448955294,   dss dack4=1   dsn8=161 ssn=161 dll=2   nocs, nop, nop>
++0.0    <   .  1:1(0)       ack 163 win 256    <nop, nop, TS val 448955294 ecr 448955294,   dss dack4=163 nocs>
+
+// clearing TCP_CORK on the accepted connection (TCP_NODELAY stays enabled)
++0.01  setsockopt(4, SOL_TCP, TCP_CORK, [0], 4) = 0
+
+// check that Nagle's algorithm is disabled
++0.0   write(4, ..., 1) = 1
++0.01  write(4, ..., 1) = 1
++0.0    >  P.  163:164(1)   ack 1              <nop, nop, TS val 448955294 ecr 448955294,   dss dack4=1   dsn8=163 ssn=163 dll=1   nocs, nop, nop>
++0.0    >  P.  164:165(1)   ack 1              <nop, nop, TS val 448955294 ecr 448955294,   dss dack4=1   dsn8=164 ssn=164 dll=1   nocs, nop, nop>
++0.0    <   .  1:1(0)       ack 165 win 256    <nop, nop, TS val 448955294 ecr 448955294,   dss dack4=165 nocs>