curl/docs/cmdline-opts/happy-eyeballs-timeout-ms.d
Daniel Stenberg ef305de95c
cmdline/docs: add a required 'multi' keyword for each option
The keyword specifies how option works when specified multiple times:

 - single: the last provided value replaces the earlier ones
 - append: it supports being provided multiple times
 - boolean: on/off values
 - mutex: flag-like option that disable anoter flag

The 'gen.pl' script then outputs the proper and unified language for
each option's multi-use behavior in the generated man page.

The multi: header is requires in each .d file and will cause build error
if missing or set to an unknown value.

Closes #9759
2022-10-18 18:50:25 +02:00

22 lines
978 B
D

c: Copyright (C) 1998 - 2022, Daniel Stenberg, <daniel@haxx.se>, et al.
SPDX-License-Identifier: curl
Long: happy-eyeballs-timeout-ms
Arg: <milliseconds>
Help: Time for IPv6 before trying IPv4
Added: 7.59.0
Category: connection
Example: --happy-eyeballs-timeout-ms 500 $URL
See-also: max-time connect-timeout
Multi: single
---
Happy Eyeballs is an algorithm that attempts to connect to both IPv4 and IPv6
addresses for dual-stack hosts, giving IPv6 a head-start of the specified
number of milliseconds. If the IPv6 address cannot be connected to within that
time, then a connection attempt is made to the IPv4 address in parallel. The
first connection to be established is the one that is used.
The range of suggested useful values is limited. Happy Eyeballs RFC 6555 says
"It is RECOMMENDED that connection attempts be paced 150-250 ms apart to
balance human factors against network load." libcurl currently defaults to
200 ms. Firefox and Chrome currently default to 300 ms.