Save the local receive and remote transmit timestamp needed for
(re)starting the symmetric protocol when no valid reply was received
separately from the timestamps that are used for synchronization of the
local clock.
This extends the interval in which the local NTP state is (partially)
protected against replay attacks in order to complete a measurement
in the interleaved symmetric mode from [last valid RX, next TX] to
[last TX, next TX], i.e. it should be the same as in the basic mode.
Similarly to the maxdelaydevratio test, include in the maximum delay
dispersion which accumulated in the interval since the last sample.
Also, enable the test for symmetric associations.
On some HW it seems it's possible to get an occasional bad reading of
the PHC (with normal delay), or in a worse case the clock can step due
to a HW/driver bug, which triggers reset of the HW clock instance. To
avoid having a bad estimate of the frequency when the next (good) sample
is accumulated, drop also the last sample which triggered the reset.
If the minimum delay is known (in a static network configuration), it
can replace the measured minimum from the register. This should improve
the stability of corrections for asymmetric jitter, sample weighting and
maxdelay* tests.
In interleaved client mode, when so many consecutive requests were lost
that the first valid (interleaved) response would be dropped for being
too old, switch to basic mode so the response can be accepted if it
doesn't fail in the other tests.
This reworks commit 16afa8eb50.
In symmetric mode, don't send a packet in interleaved mode unless it is
the first response to the last valid request received from the peer and
there was just one response to the previous valid request. This prevents
the peer from matching the transmit timestamp with an older response if
it can't detect missed responses.
If the -Q option is specified, disable by default pidfile, ntpport,
cmdport, Unix domain command socket, and clock control, in order to
allow starting chronyd without root privileges and/or when another
chronyd instance is already running.
Specify the maximum length of the path in the snprintf() format to avoid
a new gcc warning (-Wformat-truncation). If the path doesn't fit in the
buffer, indicate with the '>' symbol that it was truncated. The function
is used only for debug messages.
Add options to allow running the tests in multiple iterations while
allowing a small number of failures per test. Some tests are expected to
fail occasionally as they are basically statistical tests. Improving
their reliability is possible, but it's always a compromise between
sensitivity, reliability, and execution time.
This is an incompatible change in the output of the tracking command,
which may break some scripts, but it's necessary to avoid confusion with
IPv4 addresses when synchronised to an IPv6 server or reference clock.
