tcp_user_timeout_user-timeout-probe.pkt

 1// SPDX-License-Identifier: GPL-2.0
 2
 3`./defaults.sh`
 4
 5    0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
 6   +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
 7   +0 bind(3, ..., ...) = 0
 8   +0 listen(3, 1) = 0
 9
10
11   +0 < S 0:0(0) win 0 <mss 1460>
12   +0 > S. 0:0(0) ack 1 <mss 1460>
13
14  +.1 < . 1:1(0) ack 1 win 65530
15   +0 accept(3, ..., ...) = 4
16
17   +0 setsockopt(4, SOL_TCP, TCP_USER_TIMEOUT, [3000], 4) = 0
18   +0 write(4, ..., 24) = 24
19   +0 > P. 1:25(24) ack 1
20   +.1 < . 1:1(0) ack 25 win 65530
21   +0 %{ assert tcpi_probes == 0, tcpi_probes; \
22         assert tcpi_backoff == 0, tcpi_backoff }%
23
24// install a qdisc dropping all packets
25   +0 `tc qdisc delete dev tun0 root 2>/dev/null ; tc qdisc add dev tun0 root pfifo limit 0`
26
27   +0 write(4, ..., 24) = 24
28   // When qdisc is congested we retry every 500ms
29   // (TCP_RESOURCE_PROBE_INTERVAL) and therefore
30   // we retry 6 times before hitting 3s timeout.
31   // First verify that the connection is alive:
32+3 write(4, ..., 24) = 24
33
34   // Now verify that shortly after that the socket is dead:
35+1 write(4, ..., 24) = -1 ETIMEDOUT (Connection timed out)
36
37   +0 %{ assert tcpi_probes == 6, tcpi_probes; \
38         assert tcpi_backoff == 0, tcpi_backoff }%
39   +0 close(4) = 0