fix data-fin in 'dss' tests

on recent kernels (5.9-rc1+), a call to close() causes the transmission of a
regular ack having the DATA FIN bit set. This bit is acknowledged by the
peer and then subflows are closed with TCP FIN: adjust tests in the
'dss' and 'add_addr' folders accordingly.

Closes: multipath-tcp/mptcp_net-next#69
Signed-off-by: Davide Caratti <dcaratti@redhat.com>

gtests/net/mptcp/add_addr/add_addr_client.pkt

@@ -21,4 +21,4 @@
 +0.0 < . 1:1(0) ack 101 win 256 <nop,nop,TS val 705 ecr 305,add_address addr[saddr] hmac=auto,dss dack8=101 dll=0 nocs>
 
 +0.4 close(3) = 0
-+0.0 > F. 101:101(0) ack 1 <nop, nop,TS val 494 ecr 700,dss dack4=1 dsn8=101 ssn=0 dll=1 nocs fin, nop, nop>
++0.0 > . 101:101(0) ack 1 <nop, nop,TS val 494 ecr 700,dss dack4=1 dsn8=101 ssn=0 dll=1 nocs fin, nop, nop>

gtests/net/mptcp/add_addr/add_addr_server.pkt

@@ -22,4 +22,4 @@
 +0.3 read(4, ..., 1000) = 1000
 
 +0 close(4) = 0
-+0 > F. 1:1(0) ack 1001 <dss dack8=1001 dsn8=1 ssn=0 dll=1 nocs fin, nop, nop>
++0 > . 1:1(0) ack 1001 <dss dack8=1001 dsn8=1 ssn=0 dll=1 nocs fin, nop, nop>

gtests/net/mptcp/dss/dss_ssn_specified_client.pkt

@@ -21,6 +21,8 @@
 +0.3 read(3, ..., 1000) = 1000
 +0.0 write(3,..., 100) = 100
 +0.0 > P. 1:101(100) ack 1001 <nop, nop, TS val 100 ecr 700, dss dack8=1001 dsn8=1 ssn=1 dll=100 nocs, nop, nop>
++0.0 < . 1001:1001(0) ack 101 win 450 <dss dack8=101 nocs>
 +0.4 close(3) = 0
-// SSN should be 0 for DATA-FIN packets carrying no data at all
-+0.0 > F. 101:101(0) ack 1001 <nop, nop,TS val 100 ecr 700,dss dack8=1001 dsn8=101 ssn=0 dll=1 nocs fin, nop, nop>
++0.0 > . 101:101(0) ack 1001 <nop, nop,TS val 100 ecr 700,dss dack8=1001 dsn8=101 ssn=0 dll=1 nocs fin, nop, nop>
++0.0 < . 1001:1001(0) ack 101 win 450 <dss dack8=101 nocs>
++0.0 > F. 101:101(0) ack 1001 <nop, nop,TS val 100 ecr 700,dss dack8=1001 dsn8=101 ssn=0 dll=1 nocs fin, nop, nop>

gtests/net/mptcp/dss/dss_ssn_specified_server.pkt

@@ -30,7 +30,11 @@
 // send 1 more data segment, this time dack8 will have to be used: server sent dsn8
 +0 write(4, ..., 1000) = 1000
 +0 > P. 2001:3001(1000) ack 11 <dss dack8=11 dsn8=2001 ssn=2001 dll=1000 nocs, nop, nop>
-+0.1 < . 11:11(0) ack 3001 win 225 <dss dack8=3001 dsn8=10 ssn=1 dll=0 nocs, nop, nop>
++0  < . 11:11(0) ack 3001 win 225 <dss dack8=3001 dsn8=10 ssn=1 dll=0 nocs, nop, nop>
 
 +0 close(4) = 0
++0 > . 3001:3001(0) ack 11 <dss dack8=11 dsn8=3001 ssn=0 dll=1 nocs fin, nop, nop>
+// rcv DATA_ACK[DFIN]
++0 < . 11:11(0) ack 3001 win 225 <dss dack8=3001 nocs>
+// close all subflows
 +0 > F. 3001:3001(0) ack 11 <dss dack8=11 dsn8=3001 ssn=0 dll=1 nocs fin, nop, nop>

gtests/net/mptcp/dss/mpc_with_data_server.pkt

@@ -24,4 +24,6 @@
 // read 100 bytes from the MPC+data
 +0.01 read(4, ..., 100) = 100
 +0 close(4) = 0
++0 > . 1001:1001(0) ack 101 <dss dack8=101 dsn8=1001 ssn=0 dll=1 nocs fin, nop, nop>
++0 < F. 101:101(0) ack 1001 win 225 <dss dack8=1001 nocs>
 +0 > F. 1001:1001(0) ack 101 <dss dack8=101 dsn8=1001 ssn=0 dll=1 nocs fin, nop, nop>