lease-times in omapi are cryptic

Tue Oct 12 08:17:43 UTC 2021

Hi Glenn

Haha :) It never occurred to me that this could be something "that simple"
:)

Well in this case I have to do a litte bit more string processing with tr,
od, cut and all that ugly built in shell commands

Thank you very much
/BR
Philippe

On Tue, 12 Oct 2021 at 02:28, Glenn Satchell <glenn.satchell at uniq.com.au>
wrote:

> Hi Philipp
>
> Nothing fishy going on, more a "feature" of the routine that prints out
> byte strings in omshell.
>
> For example the ip address is printed as 1f:19:7b:b7 - if you convert each
> of these hexadecimal values to a decimal integer you get 31 25 123 183. The
> print routine tries to be clever and if a byte value is in the range of an
> ascii character it prints the ascii character rather than the hexadecimal
> value.
>
> So taking the ends value "adTf", each of these characters has an ascii
> value a=0x61, d=0x64, T=0x54, f=0x66. These represent the 4 bytes making up
> an integer. If the string was printed as hexadecimal values it would be
> 61:64:54:66. Converting 0x61645466 to a 32 bit integer using my trusty hex
> calculator we get 1633965158 which is the number of seconds since the
> epoch. Finally we convert this to a date in the UTC time zone
>
> $ date -d @1633965158 -u
> Mon 11 Oct 2021 15:12:38 UTC
>
> which matches the value in the lease file.
>
> Why does it work this way? Well, my guess is the function that prints out
> the values of the various lease parameters is not that smart and doesn't
> always know that a particular value represents a string of text,  binary
> data, or a time, so it uses a fairly generic routine that (sort of) works
> some of the time. You can see another variation of this in the leases file
> where the uid is printed as a series of octal digits with the \ooo syntax
> for each byte.
>
> regards,
>
> Glenn
>
> On 2021-10-12 01:54, Philippe Maechler wrote:
>
> Hello bind-users
>
>
>
> Since a while I'm having troubles getting the right lease-time by omapi
> for some? maybe all leases...
>
>
>
> pmaechler at stageing:/ % /usr/local/bin/omshell
>
> > server 10.20.0.251
>
> > port XXXX
>
> > key omapi_key XXXXXXXXXXXXXXXXXXXXXX
>
> > connect
>
> obj: <null>
>
> > new lease
>
> obj: lease
>
> > set ip-address = 31.25.123.183
>
> obj: lease
>
> ip-address = 1f:19:7b:b7
>
> > open
>
> obj: lease
>
> ip-address = 1f:19:7b:b7
>
> state = 00:00:00:02
>
> dhcp-client-identifier = 01:e0:91:f5:dc:a1:e1
>
> subnet = 00:00:00:2e
>
> pool = 00:00:00:2f
>
> billing-class = 00:00:00:30
>
> hardware-address = e0:91:f5:dc:a1:e1
>
> hardware-type = 00:00:00:01
>
> ends = "adTf"
>
> starts = "adFV"
>
> tstp = 00:00:00:00
>
> tsfp = 00:00:00:00
>
> atsfp = 00:00:00:00
>
> cltt = "adFV"
>
> flags = 00
>
> circuit = "some stupid string from our access devices"
>
> clhw = "e0:91:f5:dc:a1:e1"
>
> clip = "31.25.123.183"
>
> vendor-class-identifier = "udhcp 0.9.8"
>
> >
>
>
>
> What kinda bothers me is the lease-times ends, starts and cltt
>
> Checking it directly in the leasefile results in
>
>
>
> lease 31.25.123.183 {
>
>   starts 1 2021/10/11 14:12:38;
>
>   ends 1 2021/10/11 15:12:38;
>
>   cltt 1 2021/10/11 14:12:38;
>
>   binding state active;
>
>   next binding state free;
>
>   rewind binding state free;
>
>   billing subclass "XXXXX_XXXXXX_XXXXXX_CPE_DHCP" "another stupid string";
>
>   hardware ethernet e0:91:f5:dc:a1:e1;
>
>   uid "\001\340\221\365\334\241\341";
>
>   set remote = "";
>
>   set circuit = "you can guess, again that thing";
>
>   set clhw = "e0:91:f5:dc:a1:e1";
>
>   set clip = "31.25.123.183";
>
>   set vendor-class-identifier = "udhcp 0.9.8";
>
>   option agent.circuit-id "again that stupid string";
>
> }
>
>
>
>
>
> we have 4 active servers all with their own pools, no failover and no
> overlapping pools.
>
> The dhcpd servers in use are running either ISC DHCP Server 4.4.1 or 4.4.2
>
> The client has 4.4.2-P1 installed, only for the omapi binaries
>
>
>
> Without further debugging into the version mismatch, it feels like only
> "some" lease-times are strange, but not all.
>
>
>
> Could this be due to the different versions or is something else "fishy"?
>
>
>
> Best regards
>
> Philipp
>
>
>
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