[Samba] same changes in the DHCP to DNS script

[Mani Wieser]

I am "playing" around with the DNS update script from the Wiki 
(https://wiki.samba.org/index.php/Configure_DHCP_to_update_DNS_records_with_BIND9) 
and made a "few" changes, which I think could be important.

1. the script dhcp-dyndns.sh should give back the control to dhcpd as 
soon as possible; therefore I am using a second bash-script (dyndns.sh) 
to fork of the main script with following context:
NOTE: i have both in /etc/dhcp/bin/

#!/bin/bash

(setsid ${0%/*}/dhcp-dyndns.sh $@ 2>&1 & disown)
exit 0


2. changes in dhcpd.conf.main

######Samba##################################################################################
on commit {
set ClientIP = binary-to-ascii(10, 8, ".", leased-address);
set noName = concat("dhcp-", ClientIP);
set ClientDHCID = binary-to-ascii(16, 8, ":", substring(hardware,1,6));
set ClientName = pick-first-value(config-option server.ddns-hostname, 
option host-name, config-option-host-name, client-name, noName);
#log(concat("Commit: IP: ", ClientIP, " DHCID: ", ClientDHCID, " Name: 
", ClientName));
execute("/etc/dhcp/bin/dyndns.sh", "commit", ClientIP, ClientDHCID, 
ClientName);
}

on release {
#log(concat("Release: IP: ", ClientIP, " DHCID: ", ClientDHCID, " Name: 
", ClientName));
execute("/etc/dhcp/bin/dyndns.sh", "release", ClientIP, ClientDHCID, 
ClientName);
}

on expiry {
#log(concat("Expiry: IP: ", ClientIP, " DHCID: ", ClientDHCID, " Name: 
", ClientName));
execute("/etc/dhcp/bin/dyndns.sh", "expiry", ClientIP, ClientDHCID, 
ClientName);
}
#####Samba###################################################################################

. mostly cosmetic in on-commit to shorten it; the ddns-hostname (first 
in ClientName) is important for me, because I am manipulating some 
client names, like Samsung TVs, with a stupid fixed name: localhost
. the on release and expiry should not try to change the data from the 
lease file, which is contra-productive......all the data set in "on 
commit" is delivered automatically and can't be extracted from the not 
existing dhcpoffer
. execute: first parameter is my "fork-shell script", the second one I 
changed from add/delete to on - xxx, to see when a client releases his 
lease or to see if dhcpd is kicking him out.
. the writing to the log is commented-out, because you get, with 
execute, 5 lines with the same information.

3. due to the above changes also the dhcp-dyndns.sh is changed and there 
I changed a lot, because I tried to ask samba itself for all the 
parameters  and DNS data. For my tests I added also a function to leave 
"doublettes"  like LAN and WLAN with two IPs and the same name and there 
is still my full debugging code in it.
. I didn't touched the Add_macAddress part, because I don't need it.
. Before my changes I had massive CNF entries (failover dhcp setup), but 
nowadays I get only one (in every zone) per new client and afterwards 
none. My experiment with this entries have shown, that you can list them 
with samba-tool, but you can't delete them with it. (I believe that the 
line break in the name (windows style with carriage return) is getting 
lost, before it arrives the actual delete function)
. One "short coming" is still existing in my script: changing the subnet 
for leases is not deleting the old PTR record, because I can't list the 
full rev zone. eg.: 168.192.in-addr.arpa, change from 1.0 to 1.1 leaves 
the 1.0 record and I would have to check first in which subnets records 
are available and query than all subnets for this record. Normally dhcpd 
should kick it after expiry of the lease, but I have a few test-records 
left, which my check function is not grabbing.

BTW: I am running samba 4.9.5 at the moment (DC2 was upgraded yesterday 
to 4.12.3) For test purposes you can add an (in bind9) existing zone 
with RSAT, but bind doesn't survive a restart with it ;-) Therefore I 
could check my script with all 3 different zone sizes at once, but I 
don't have a busy server.

450 lines are to much for this email, therefore I linked it.

https://1drv.ms/u/s!AtKwcFU5bIBMhzVibxfJsHjygokd?e=cHeim6

NOT FOR PRODUCTION.........pre-Alpha version!!!

Mani