Instead of making the initial burst only once and immediately after
chronyd start (even when iburst is specified together with the offline
option), trigger the burst whenever the connectivity changes from
offline to online.
Refactor the client record and clientlog API to reuse more code between
different services and enumerate the services instead of hardcoding NTP
and cmdmon.
Refactor the code to allow the selection options of the current sources
to be modified when other sources are added and removed. Also, make the
authentication status of each source available to the code which makes
the modifications.
When replacing an NTP source, update the NTS address before the NTP
address to save cookies with the old NTP address instead of the newly
resolved address (which may immediately change to an address provided by
NTS-KE).
Remove leap status from the NTP sample and set it independently from
the sample accumulation in order to accept a leap second sooner when
samples are filtered.
Add an option to enable NTS for an NTP source. Check for NTS-specific
extension fields and pass the packets to the NTS-NTP code in order to
enable the NTS client and server.
This will allow a source to have its address changed due to NTS-KE
server negotiation, which allows the NTS-KE server to have a different
address than the NTP server.
Move most of the authentication-specific code to a new file and
introduce authenticator instances in order to support other
authentication mechanisms (e.g. NTS).
Rework the code to detect the authentication mode and count extension
fields in the first parsing of the packet and store this information in
the new packet info structure.
When sending a response in the server or passive mode, make sure the
response is not longer than the request to prevent amplification
attacks when resposes may contain extension fields (e.g. NTS).
Add a structure for length and other information about received and
transmitted NTP packets to minimize the number of parameters and avoid
repeated parsing of the packet.
Improve the client's test D to compare the stratum, reference ID,
reference timestamp, and root delay from the received packet with its
own reference data in order to prevent it from synchronizing to itself,
e.g. due to a misconfiguration.
Add an option to use the median filter to reduce noise in measurements
before they are accumulated to sourcestats, similarly to reference
clocks. The option specifies how many samples are reduced to a single
sample.
The filter is intended to be used with very short polling intervals in
local networks where it is acceptable to generate a lot of NTP traffic.
When the local polling interval is adjusted between minpoll and maxpoll
to a sub-second value, check if the source is reachable and the minimum
measured delay is 10 milliseconds or less. If it's not, ignore the
maxpoll value and set the interval to 1 second.
This should prevent clients (mis)configured with an extremely short
minpoll/maxpoll from flooding servers on the Internet.
If the polling interval is shorter than 8 seconds, set the burst
interval to the 1/4th of the polling interval instead of the 2-second
constant. This should make the burst option and command useful with
very short polling intervals.
Fix mismatches between the format and sign of variables passed to
printf() or scanf(), which were found in a Frama-C analysis and gcc
using the -Wformat-signedness option.
Instead of counting missing responses, switch to the offline state
immediately when sendmsg() fails.
This makes the option usable with servers and networks that may drop
packets, and the effect will be consistent with the onoffline command.
Allow SRC_MAYBE_ONLINE to be specified for new NTP sources and
connectivity setting to select between SRC_ONLINE and SRC_OFFLINE
according to the result of the connect() system call, i.e. check whether
the client has a route to send its requests.
NTPv1 packets have a reserved field instead of the mode field and the
actual mode is determined from the port numbers. It seems there is still
a large number of clients sending NTPv1 requests with a zero value in
the field (per RFC 1059).
Follow ntpd and respond to the requests with server mode packets.
Clients sending packets in the interleaved mode are supposed to use
a different receive and transmit timestamp in order to reliably detect
the mode of the response. If an interleaved request with the receive
timestamp equal to the transmit timestamp is detected, respond in the
basic mode.
When the burst option is specified in the server/pool directive and the
current poll is longer than the minimum poll, initiate on each poll a
burst with 1 good sample and 2 or 4 total samples according to the
difference between the current and minimum poll.
