dhcpcd-discuss

Turns out the output is sent to syslog and is not parsable after it is
mixed with tons of other logs.

Can we force the logs to go somewhere else? (not to syslog)

Would love to see an event sent to the hook script for that effect.

Thanks
-shahid

On Mon, Jun 20, 2016 at 11:25 AM, Shahid Mahmood <shahid.avaya@xxxxxxxxx>
wrote:

>
>
> On Fri, Jun 17, 2016 at 1:11 PM, Shahid Mahmood <shahid.avaya@xxxxxxxxx>
> wrote:
>
>>
>> On Fri, Jun 17, 2016 at 12:51 PM, Roy Marples <roy@xxxxxxxxxxxx> wrote:
>>
>>> Hi
>>>
>>> On 16/06/2016 21:27, Shahid Mahmood wrote:
>>> > Back to this question again ...
>>> >
>>> > Recap: Two dhcp servers, one sending offer with preferred option, other
>>> > without.
>>> >
>>> > If within 1 second of sending discover, two leases were received, then
>>> > pick the one with preferred option.
>>> > If 1 second has elapsed and no lease with preferred option seen, then
>>> > just pick the other one without the preferred option.
>>> >
>>> > (1 sec can be changed to upto 5)
>>> >
>>> > Here is my idea how to implement this:
>>> >
>>> > 1. Start dhcpcd with -Q vendor_option -t10
>>> > (Hook scripts dump option and variables in a file, say
>>> > /tmp/dhcp/dhcpcd_data)
>>> > 2. Monitor /tmp/dhcp/ for activity (using inotify)
>>> > 3. *Somehow detect* 2 lease situation, e.g a lease was offered but
>>> > rejected, or timeout has occurred, and if so, restart dhcpcd without -Q
>>> > and -t (settle on non-preferred lease)
>>> > 4. Of course, if a lease with vendor_option was received, accept it and
>>> > continue normal life.
>>> >
>>> > Q:
>>> > Is this good approach?
>>> > If so, how can I do step 3? ie detect events such as timeout, reject or
>>> > offer received?
>>> > If not, is there a better way to do this? e.g is -T worth considering?
>>>
>>> I don't think that's a good approach because you're signallng dhcpcd
>>> from outside about what is good and what is bad.
>>>
>>>
>> Correct, because dhcpcd does not know how to decide with lease to select.
>>
>>
>>> Right now, dhcpcd internally has a state machine per protocol that is
>>> desinged to handle only one offer. These should be refactored to handle
>>> N offers, with a mechanisn to handle preference.
>>>
>>> We need only one offer per protocol. Just need to prefer the one with
>> site_specif option.
>>
>>
>>> Another interesting question is this: do we want to only have one
>>> primary lease or take the IPv6 autoconf approach and merge active offers?
>>>
>>> Just one lease for now. Merged offer option will also do the job,
>> if/when it is available :)
>>
>>> Roy
>>>
>>>
>> Trying to implement the flow as outlined above.
> dhcpcd starts correctly with '-Q site_specific' and rejects the lease when
> it comes from a server not providing this option.
> HOWEVER I am not able to detect this condition programatically.
> Is there a variable I can check in the hook script? I can't find one.
> I tried redirecting stdout and stderr in a log file ( 2>&1 >
> /tmp/logfile.txt) but the file is always empty.
> If I run dhcpcd with command line, e.g
> # dhcpcd -Q site_specific
> The console shows some usable output, e.g
> #eth0: sending DISCOVER (xid 0xd265890a), next in 4.2 seconds
> #eth0: reject DHCP 192.168.20.20 from 192.168.20.4 `DC16010051'
>
> How can my application detect if an offer was rejected?
> Alternately, is there a better way to save/read logs? (I have 'debug'
> enabled too).
>
> Thanks
> -shahid
>
>