mirror of
https://git.haproxy.org/git/haproxy.git/
synced 2025-09-22 14:21:25 +02:00
bca5a4e0a8
The v4v6 and v6only options are passed as data during the socket transfer
between processes so that the new process can decide whether it wants to
reuse a socket or not. But this actually misses one point: if no such option
is set and the OS defaults are changed between the reloads, then the socket
will still be inherited and will never be rebound using the new options.
This can be seen by starting the following config:
global
stats socket /tmp/haproxy.sock level admin expose-fd listeners
frontend testme
bind :::1234
timeout client 2000ms
Having a look at the OS settins, v6only is disabled:
$ cat /proc/sys/net/ipv6/bindv6only
0
A first check shows it's indeed bound to v4 and v6:
$ ss -an -6|grep 1234
tcp LISTEN 0 2035 *:1234 *:*
Reloading the process doesn't change anything (which is expected). Now let's set
bindv6only:
$ echo 1 | sudo tee /proc/sys/net/ipv6/bindv6only
1
$ cat /proc/sys/net/ipv6/bindv6only
1
Reloading gives the same state:
$ ss -an -6|grep 1234
tcp LISTEN 0 2035 *:1234 *:*
However a restart properly shows a correct bind:
$ ss -an -6|grep 1234
tcp LISTEN 0 2035 [::]:1234 [::]:*
This one doesn't change once bindv6only is reset, for the same reason.
This patch attacks this problem differently. Instead of passing the two
options at once for each listening fd, it ignores the options and reads
the socket's current state for the IPV6_V6ONLY flag and sets it only.
Then before looking for a compatible FD, it checks the OS's defaults
before deciding which of the v4v6 and v6only needs to be kept on the
listener. And the selection is only made on this.
First, it addresses this issue. Second, it also ensures that if such
options are changed between reloads to identical states, the socket
can still be inherited. For example adding v4v6 when bindv6only is not
set will allow the socket to still be usable. Third, it avoids an
undesired dependency on the LI_O_* bit values between processes across
a reload (for these ones at least).
It might make sense to backport this to some recent stable versions, but
quite frankly the likelyhood that anyone will ever notice it is extremely
faint.
The HAProxy documentation has been split into a number of different files for ease of use. Please refer to the following files depending on what you're looking for : - INSTALL for instructions on how to build and install HAProxy - BRANCHES to understand the project's life cycle and what version to use - LICENSE for the project's license - CONTRIBUTING for the process to follow to submit contributions The more detailed documentation is located into the doc/ directory : - doc/intro.txt for a quick introduction on HAProxy - doc/configuration.txt for the configuration's reference manual - doc/lua.txt for the Lua's reference manual - doc/SPOE.txt for how to use the SPOE engine - doc/network-namespaces.txt for how to use network namespaces under Linux - doc/management.txt for the management guide - doc/regression-testing.txt for how to use the regression testing suite - doc/peers.txt for the peers protocol reference - doc/coding-style.txt for how to adopt HAProxy's coding style - doc/internals for developer-specific documentation (not all up to date)