selftest: packetdrill: Refine tcp_fastopen_server_reset-after-disconnect.pkt.

These changes are applied to follow the imported packetdrill tests.

* Call setsockopt(TCP_FASTOPEN)
* Remove unnecessary accept() delay
* Add assertion for TCP states
* Rename to tcp_fastopen_server_trigger-rst-reconnect.pkt.

Signed-off-by: Kuniyuki Iwashima <[e-mail]>
Reviewed-by: Willem de Bruijn <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

tools/testing/selftests/net/packetdrill/tcp_fastopen_server_reset-after-disconnect.pkt tools/testing/selftests/net/packetdrill/tcp_fastopen_server_trigger-rst-reconnect.pkt

···
 // SPDX-License-Identifier: GPL-2.0
 `./defaults.sh
- ./set_sysctls.py /proc/sys/net/ipv4/tcp_fastopen=0x602 /proc/sys/net/ipv4/tcp_timestamps=0`
+ ./set_sysctls.py /proc/sys/net/ipv4/tcp_timestamps=0`
 
     0 socket(..., SOCK_STREAM|SOCK_NONBLOCK, IPPROTO_TCP) = 3
    +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
    +0 bind(3, ..., ...) = 0
    +0 listen(3, 1) = 0
+   +0 setsockopt(3, SOL_TCP, TCP_FASTOPEN, [1], 4) = 0
 
-   +0 < S 0:10(10) win 32792 <mss 1460,nop,nop,sackOK>
+   +0 < S 0:10(10) win 32792 <mss 1460,nop,nop,sackOK,nop,nop,FO TFO_COOKIE>
    +0 > S. 0:0(0) ack 11 win 65535 <mss 1460,nop,nop,sackOK>
 
 // sk->sk_state is TCP_SYN_RECV
-  +.1 accept(3, ..., ...) = 4
+   +0 accept(3, ..., ...) = 4
+   +0 %{ assert tcpi_state == TCP_SYN_RECV, tcpi_state }%
 
 // tcp_disconnect() sets sk->sk_state to TCP_CLOSE
    +0 connect(4, AF_UNSPEC, ...) = 0
    +0 > R. 1:1(0) ack 11 win 65535
+   +0 %{ assert tcpi_state == TCP_CLOSE, tcpi_state }%
 
 // connect() sets sk->sk_state to TCP_SYN_SENT
    +0 fcntl(4, F_SETFL, O_RDWR|O_NONBLOCK) = 0
    +0 connect(4, ..., ...) = -1 EINPROGRESS (Operation is now in progress)
    +0 > S 0:0(0) win 65535 <mss 1460,nop,nop,sackOK,nop,wscale 8>
+   +0 %{ assert tcpi_state == TCP_SYN_SENT, tcpi_state }%
 
 // tp->fastopen_rsk must be NULL
    +1 > S 0:0(0) win 65535 <mss 1460,nop,nop,sackOK,nop,wscale 8>