[Dnsmasq-discuss] [PATCH] Logging of dhcp_script output
pemensik at redhat.com
Wed Apr 19 19:14:46 BST 2017
I like your changes. New shorter log is definitely helpful, separate log section helps. The only bug I found is red white space highlight in the patch.
However I did yet another fix for remaining dhcp-script init action.
It completely ignored any error in structure and silently skipped the rest of database. If there was any message in stdin of init script, it just died silently.
The only thing that were visible was SIGPIPE from dhcp-script, because it did not read whole database, if that signal was logged at all.
My new patch handles garbage in leases database. If the line is wrong, it logs part of wrong line and skips the rest of init.
I thought about die in that case. I think it would be better for backward compatibility to start with empty leases as before.
Red Hat, http://www.redhat.com/
email: pemensik at redhat.com PGP: 65C6C973
----- Original Message -----
From: "Simon Kelley" <simon at thekelleys.org.uk>
To: dnsmasq-discuss at lists.thekelleys.org.uk
Sent: Sunday, April 16, 2017 9:29:21 PM
Subject: Re: [Dnsmasq-discuss] [PATCH] Logging of dhcp_script output
I like this. Yes, I know you can do it with shell magic, but this is
easier and what I would expect to happen.
I've changed the patch quite a lot:
1) Don't go to large effort to report "never happen" errors from pipe(),
just silently handle them in the same way as fork()
2) Don't do any of this when the -d debug flag is in effect, as it's
already defined that the script gets stdin, stdout and stderr from the
dnsmasq process in that case.
3) Expand the subject-based logging that already exists, DHCP stuff
comes from dnsmasq-dhcp, script output comes from dhcp-script. That
avoids the wordy preamble to every line otherwise.
4) Pull the copy-to-log code out of the loop wait()ing for processes to
die, it makes more sense to iterate until the descriptors close, then
reap child processes.
5) Rationalise conditional compilation stuff. There may be more of that
in a subsequent commit.
6) Update the man page to reflect new reality (!)
Any remaining bugs are mine, but Petr please check that I didn't break
On 24/03/17 17:38, Petr Mensik wrote:
> Some guys using dnsmasq in virtual machines and OpenStack use custom dhcp_script to manage leases of clients.
> However they complain if there is anything wrong with them, then are just told broken pipe and no information.
> We understand it should not produce any output under normal operation. But it would be really helpful if at least anything was visible in logs. Especially for errors happening under rare circumstances.
> I have prepared patch to forward events from helper. It prevents SIGPIPE receiving if script does write anything. And logs it from dnsmasq.
> It seems very handy to me.
> It was not simple to forward it to main log. I would like opinions if it is useful or dangerous.
> Do you consider it worth merging Simon?
> Best Regards,
> Petr Menšík
> Software Engineer
> Red Hat, http://www.redhat.com/
> email: pemensik at redhat.com PGP: 65C6C973
> Dnsmasq-discuss mailing list
> Dnsmasq-discuss at lists.thekelleys.org.uk
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