Compared to version 10 this fixes a bunch of formatting issues, mostly
around structs/classes with attributes like [[gnu::packed]], and
incorrect insertion of spaces in parameter types ("T &"/"T &&").
I also removed a bunch of // clang-format off/on and FIXME comments that
are no longer relevant - on the other hand it tried to destroy a couple of
neatly formatted comments, so I had to add some as well.
Create macros for the byte swap operations one would expect to be in
endian.h or byteswap.h in AK/Endian.h. It's likely a similar/different
change will be needed for BSDs, but there's no github action for those
added to the project yet.
With this, `ntpquery` can adjust the system time without
making it jump.
A fun activity with this in:
0. Boot
1. Run `su`
2. Run `ntpquery -a` to adjust the time offset after boot
(usually around a second)
3. Keep running `ntpquery ; adjtime` to see how the offset
behind NTP and the remaining adjtime both shrink.
adjtime adjustment is large enough to make the time offset
go down by a bit, but we currently lose time quickly enough
that by the time adjtime is done, we've only corrected the
clock about halfway, and not all the way to zero. Goto 2.
So this isn't all that great yet, but I think it's good enough
to think about turning this into a permanently running service next.
This implements the transmit time suggestion in (abandoned?)
draft-ietf-ntp-data-minimization. (The other suggestions were already
implemented as far as I can tell.)
We can now see at which time a packet was received by the network
adapter, instead of having to measure user time after receiving
the packet in user space.
This means the destination timestamp is no longer affected by in-kernel
queuing delays, which can be tens of milliseconds when the system
is under load.
It also means that if ntpquery grows a message queue that waits on
replies from several requests, the time used processing one response
won't be incorrectly included in the destination timestamp of the
next response (in case two responses arrive at the network adapter
at roughly the same time).
NTP's calculations work better if send and receive latency are
about equal, and this only removes in-kernel queue delays and
context switch delays for the receiving packet. But the two
latencies aren't very equal anyways because $network. Also, maybe
we can add another API for setting the send time in the outgoing
packet in kernel space right before (or when) hitting the network
adapter and use that here too. So this still seems like progress.
Using a pool.ntp.org server seems nicer and more open-source-y,
but until our pool use is approved, let's put in a default value
that works.
(time.google.com serves smeared time instead of doing leap seconds.
pool.ntp.org doesn't serve smeared time. I intend to implement
client-side leap second smearing since nobody likes jumpy timestamps.
For now, we get this for free.)
This only queries a single NTP server, only does a point-to-point
request, doens't do any filtering, doesn't display the response
in any useful format, and is generally very bare-bones.
But maybe, over time it can learn to query more servers, do
filtering, run as a service that keeps state over time to
improve filtering, adjust system time, and maybe learn to
run as an NTP server then.
