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 40