Dnsmasq used SIGHUP to do too many things: 1) set dnssec time validation
enabled, 2) bump SOA zone serial, 3) clear dns cache, 4) reload hosts
files, 5) reload resolvers/servers files.
Many subsystems within LEDE can send SIGHUP to dnsmasq: 1) ntpd hotplug
(to indicate time is valid for dnssec) 2) odhcpd (to indicate a
new/removed host - typically DHCPv6 leases) 3) procd on interface state
changes 4) procd on system config state changes, 5) service reload.
If dnssec time validation is enabled before the system clock has been
set to a sensible time, name resolution will fail. Because name
resolution fails, ntpd is unable to resolve time server names to
addresses, so is unable to set time. Classic chicken/egg.
Since commits 23bba9cb33 (service reload) &
4f02285d8b (system config) make it more
likely a SIGHUP will be sent for events other than 'ntpd has set time'
it is more likely that an errant 'name resolution is failing for
everything' situation will be encountered.
Fortunately the upstream dnsmasq people agree and have moved 'check
dnssec timestamp enable' from SIGHUP handler to SIGINT.
Backport the upstream patch to use SIGINT.
ntpd hotplug script updated to use SIGINT.
Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
Use ubus process signalling instead of 'kill pidof dnsmasq' for
SIGHUP signalling to dnsmasq when ntp says time is valid.
Signed-off-by: Kevin Darbyshire-Bryant <kevin@darbyshire-bryant.me.uk>
Change dnsmasq's dnssec time check handling to use time validity
indicated by ntpd rather than maintaining a cross boot/upgrade
/etc/dnsmasq.time timestamp file. This saves flash device wear.
If ntpd client is configured in uci and you're using dnssec, then
dnsmasq will not check dnssec timestamp validity until ntpd hotplug
indicates sync via a stratum change. The ntpd hotplug leaves a status
flag file to indicate to dnsmasq.init that time is valid and that it
should now start in 'check dnssec timestamp valid' mode.
If ntpd client is not configured and you're using dnssec, then it is
presumed you're using an alternate time sync mechanism and that time is
correct, thus dnsmasq checks dnssec timestamps are valid from 1st start.
Signed-off-by: Kevin Darbyshire-Bryant <kevin@darbyshire-bryant.me.uk>
V2 - stratum & step ntp changes indicate time is valid
V3 - on initial flag file step signal dnsmasq with SIGHUP if running
V4 - only accept step ntp changes. Accepting both stratum & step could
result in unpleasant script race conditions
V5 - Actually only accepting stratum is the correct thing to do after
further testing
V6 - improve handling of non busybox ntpd
if sysntpd not executable
dnsmasq checks dnssec timestamps
else
sysntp script disabled - look for timestamp file - allows external mechanism to use hotplug flag file
sysntp script enabled & uci ntp enabled - look for timestamp file
sysntp script enabled & uci ntp disabled - dnsmasq checks dnssec
timestamps
fi
