tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0
2`./defaults.sh`
3
4// Initialize connection
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 +0 < S 0:0(0) win 32792 <mss 1000,sackOK,nop,nop>
11 +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK>
12 +.1 < . 1:1(0) ack 1 win 32792
13
14
15 +0 accept(3, ..., ...) = 4
16
17// Okay, we received nothing, and decide to close this idle socket.
18// We set TCP_USER_TIMEOUT to 3 seconds because really it is not worth
19// trying hard to cleanly close this flow, at the price of keeping
20// a TCP structure in kernel for about 1 minute !
21 +2 setsockopt(4, SOL_TCP, TCP_USER_TIMEOUT, [3000], 4) = 0
22 +0 close(4) = 0
23
24 +0 > F. 1:1(0) ack 1
25 +.3~+.400 > F. 1:1(0) ack 1
26 +.3~+.400 > F. 1:1(0) ack 1
27 +.6~+.800 > F. 1:1(0) ack 1
28
29// We finally receive something from the peer, but it is way too late
30// Our socket vanished because TCP_USER_TIMEOUT was really small
31 +0 < . 1:2(1) ack 1 win 32792
32 +0 > R 1:1(0)