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#!rsc by RouterOS
# RouterOS script: netwatch-dns
# Copyright (c) 2022-2024 Christian Hesse <mail@eworm.de>
# https://git.eworm.de/cgit/routeros-scripts/about/COPYING.md
#
# requires RouterOS, version=7.12
#
# monitor and manage dns/doh with netwatch
# https://git.eworm.de/cgit/routeros-scripts/about/doc/netwatch-dns.md
:global GlobalFunctionsReady;
:while ($GlobalFunctionsReady != true) do={ :delay 500ms; }
:do {
:local ScriptName [ :jobname ];
:global CertificateAvailable;
:global EitherOr;
:global LogPrint;
:global ParseKeyValueStore;
:global ScriptLock;
:if ([ $ScriptLock $ScriptName ] = false) do={
:error false;
}
:local SettleTime (5m30s - [ /system/resource/get uptime ]);
:if ($SettleTime > 0s) do={
$LogPrint info $ScriptName ("System just booted, giving netwatch " . $SettleTime . " to settle.");
:error true;
}
:local DnsServers ({});
:local DnsFallback ({});
:local DnsCurrent [ /ip/dns/get servers ];
:foreach Host in=[ /tool/netwatch/find where comment~"\\bdns\\b" status="up" ] do={
:local HostVal [ /tool/netwatch/get $Host ];
:local HostInfo [ $ParseKeyValueStore ($HostVal->"comment") ];
:if ($HostInfo->"disabled" != true) do={
:if ($HostInfo->"dns" = true) do={
:set DnsServers ($DnsServers, $HostVal->"host");
}
:if ($HostInfo->"dns-fallback" = true) do={
:set DnsFallback ($DnsFallback, $HostVal->"host");
}
}
}
:if ([ :len $DnsServers ] > 0) do={
:if ($DnsServers != $DnsCurrent) do={
$LogPrint info $ScriptName ("Updating DNS servers: " . [ :tostr $DnsServers ]);
/ip/dns/set servers=$DnsServers;
/ip/dns/cache/flush;
}
} else={
:if ([ :len $DnsFallback ] > 0) do={
:if ($DnsFallback != $DnsCurrent) do={
$LogPrint info $ScriptName ("Updating DNS servers to fallback: " . [ :tostr $DnsFallback ]);
/ip/dns/set servers=$DnsFallback;
/ip/dns/cache/flush;
}
}
}
:local DohCurrent [ /ip/dns/get use-doh-server ];
:local DohServers ({});
:foreach Host in=[ /tool/netwatch/find where comment~"\\bdoh\\b" status="up" ] do={
:local HostVal [ /tool/netwatch/get $Host ];
:local HostInfo [ $ParseKeyValueStore ($HostVal->"comment") ];
:local HostName [ /ip/dns/static/find where name address=($HostVal->"host") \
(!type or type="A" or type="AAAA") !disabled !dynamic ];
:if ([ :len $HostName ] > 0) do={
:set HostName [ /ip/dns/static/get ($HostName->0) name ];
}
:if ($HostInfo->"doh" = true && $HostInfo->"disabled" != true) do={
:if ([ :len ($HostInfo->"doh-url") ] = 0) do={
:set ($HostInfo->"doh-url") ("https://" . [ $EitherOr $HostName ($HostVal->"host") ] . "/dns-query");
}
:if ($DohCurrent = $HostInfo->"doh-url") do={
$LogPrint debug $ScriptName ("Current DoH server is still up: " . $DohCurrent);
:error true;
}
:set ($DohServers->[ :len $DohServers ]) $HostInfo;
}
}
:if ([ :len $DohCurrent ] > 0) do={
$LogPrint info $ScriptName ("Current DoH server is down, disabling: " . $DohCurrent);
/ip/dns/set use-doh-server="";
/ip/dns/cache/flush;
}
:foreach DohServer in=$DohServers do={
:if ([ :len ($DohServer->"doh-cert") ] > 0) do={
:if ([ $CertificateAvailable ($DohServer->"doh-cert") ] = false) do={
$LogPrint warning $ScriptName ("Downloading certificate failed, trying without.");
}
}
:local Data false;
:do {
:set Data ([ /tool/fetch check-certificate=yes-without-crl output=user \
http-header-field=({ "accept: application/dns-message" }) \
url=(($DohServer->"doh-url") . "?dns=" . [ :convert to=base64 ([ :rndstr length=2 ] . \
"\01\00" . "\00\01" . "\00\00" . "\00\00" . "\00\00" . "\09doh-check\05eworm\02de\00" . \
"\00\10" . "\00\01") ]) as-value ]->"data");
} on-error={
$LogPrint warning $ScriptName ("Request to DoH server failed (network or certificate issue): " . \
($DohServer->"doh-url"));
}
:if ($Data != false) do={
:if ([ :typeof [ :find $Data "doh-check-OK" ] ] = "num") do={
/ip/dns/set use-doh-server=($DohServer->"doh-url") verify-doh-cert=yes;
/ip/dns/cache/flush;
$LogPrint info $ScriptName ("Setting DoH server: " . ($DohServer->"doh-url"));
:error true;
} else={
$LogPrint warning $ScriptName ("Received unexpected response from DoH server: " . \
($DohServer->"doh-url"));
}
}
}
} on-error={ }
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