We have an option to set the fallback list, so we don't know what the contents
are. It may in fact be empty. Let's add some examples to make it easy for a user
stranded without any DNS to fill in something that would work. As a bonus, this
also gives names to the entries we provide by default.
(I added google and cloudflare because that's what we have currently, and quad9
because it seems to be a good privacy-concious and fast choice and was requested
in #12499. As a minimum, things we should include should be well-known global
services with a documented privacy policy and both IPv4 and IPv6 support and
decent response times.)
Also, document this functionality more prominently, including with a
reference from sd_event_exit().
This is mostly to make things complete, as previously we supported NULL
callbacks only in _add_time() and _add_signal(). However, I think this
makes snese for IO event sources too (think: when some fd such as a pipe
end sees SIGHUP or so, exit), as well as defer or post event sources (i.e. exit
once we got nothing else to do). This also adds support for inotify
event sources, simply to complete things (I can't see the immediate use,
but maybe someone else comes up with it).
The only event source type that doesn't allow callback=NULL now are exit
callbacks, but for them they make little sense, as the event loop is
exiting then anyway.
Currently, if an event source callback returns an error, we'll disable
the event source and continue. This adds a per-event source flag that if
turned on goes further: the event loop is also exited, propagating the
error code.
This is inspired by some patterns repeatedly seen in #15206.
The idea is that event sources that server the "primary" function of a
program are marked like this, so that if they fail the failure is
instantly propagated and terminates the program.
Functions that accept no arguments should be
explicitly declared a void parameter in their parameter list.
Signed-off-by: Marco Wang <m.aesophor@gmail.com>
We usually disable IPv6AcceptRA= if the test does not require any
dynamic address configuration, as it makes slightly slow down the test.
C.f. 491b79aeac.
Previously, address_establish() took Address object stored in Network
object. And address_release() took Address object stored in Link
object. Thus, address_release() always did nothing.
When the MAC address of a link is updated, an address on the link may
be under checking address duplication. Or, (currently such code is not
implemented yet, but) address duplication check may be restarted later.
For that case, the IPv4 ACD clients must use the new updated MAC address.
Previously, IPv4 DAD is configured in each Address object stored in
Network object. If a .network file matches multipe links, then it causes
an assertion. To prevent it, now IPv4 DAD is configured in each Address
object belogs to Link object.
Lennart Poettering