Debian Bug report logs - #798653
Should detect entries removed from files in hostsdir=/dir/ and not serve them anymore

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Message #5 received at submit@bugs.debian.org (full text, mbox, reply):

From: Guido Günther <agx@sigxcpu.org>

To: Debian Bug Tracking System <submit@bugs.debian.org>

Subject: hosts from hostsdir=/dir/ picked up but not served

Date: Fri, 11 Sep 2015 15:57:19 +0200

Package: dnsmasq
Version: 2.75-1
Severity: normal

Hi,
I just tried your suggestion with --hostdir=/tmp/test. While I see these
log messages nicely:

Sep 11 15:53:49 foo dnsmasq[14616]: inotify, new or changed file /tmp/test/libvirt-qemu%3A%2F%2F%2Fsystem.hosts.tmp
Sep 11 15:53:49 foo dnsmasq[14616]: read /tmp/test/libvirt-qemu%3A%2F%2F%2Fsystem.hosts.tmp - 3 addresses
Sep 11 15:53:49 foo dnsmasq[14616]: inotify, new or changed file /tmp/test/libvirt-qemu%3A%2F%2F%2Fsystem.hosts
Sep 11 15:53:49 foo dnsmasq[14616]: read /tmp/test/libvirt-qemu%3A%2F%2F%2Fsystem.hosts - 3 addresses

these addresses are _only_ being served if they are already present in
the file during daemon start. New entries are not being served. Note
that my program writes to a .tmp first and then does a rename so this
might confuse dnsmasq (and I can't use s.th. like:

    --host-dir=/tmp/test,*.tmp

to ignor the temporary file).
Cheers,
 -- Guido


-- System Information:
Debian Release: 8.1
  APT prefers stable
  APT policy: (990, 'stable'), (500, 'stable-updates'), (500, 'unstable'), (500, 'testing'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.1.0-2-amd64 (SMP w/p4 CPU cores)
Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages dnsmasq depends on:
ii  dnsmasq-base         2.75-1
ii  init-system-helpers  1.22
ii  netbase              5.3

dnsmasq recommends no packages.

Versions of packages dnsmasq suggests:
ii  resolvconf  1.76.1

-- no debconf information

Message #10 received at submit@bugs.debian.org (full text, mbox, reply):

From: Guido Günther <agx@sigxcpu.org>

To: Debian Bug Tracking System <submit@bugs.debian.org>

Subject: Re: Bug#798653: hosts from hostsdir=/dir/ picked up but not served

Date: Fri, 11 Sep 2015 16:54:57 +0200

On Fri, Sep 11, 2015 at 03:57:19PM +0200, Guido Günther wrote:
> Package: dnsmasq
> Version: 2.75-1
> Severity: normal
> 
> Hi,
> I just tried your suggestion with --hostdir=/tmp/test. While I see these
> log messages nicely:
> 
> Sep 11 15:53:49 foo dnsmasq[14616]: inotify, new or changed file /tmp/test/libvirt-qemu%3A%2F%2F%2Fsystem.hosts.tmp
> Sep 11 15:53:49 foo dnsmasq[14616]: read /tmp/test/libvirt-qemu%3A%2F%2F%2Fsystem.hosts.tmp - 3 addresses
> Sep 11 15:53:49 foo dnsmasq[14616]: inotify, new or changed file /tmp/test/libvirt-qemu%3A%2F%2F%2Fsystem.hosts
> Sep 11 15:53:49 foo dnsmasq[14616]: read /tmp/test/libvirt-qemu%3A%2F%2F%2Fsystem.hosts - 3 addresses
> 
> these addresses are _only_ being served if they are already present in
> the file during daemon start. New entries are not being served. Note
> that my program writes to a .tmp first and then does a rename so this
> might confuse dnsmasq (and I can't use s.th. like:

Even when I skip the writing to .tmp file step dnsmasq does only server
entries that are present in the file at startup.

A SIGHUP also lets the daemon server the entries from the hostdir.

Cheers,
 -- Guido

Message #15 received at submit@bugs.debian.org (full text, mbox, reply):

From: Simon Kelley <simon@thekelleys.org.uk>

To: Guido Günther <agx@sigxcpu.org>, 798653@bugs.debian.org, Debian Bug Tracking System <submit@bugs.debian.org>

Subject: Re: Bug#798653: hosts from hostsdir=/dir/ picked up but not served

Date: Fri, 18 Sep 2015 22:23:57 +0100

On 11/09/15 15:54, Guido Günther wrote:
> On Fri, Sep 11, 2015 at 03:57:19PM +0200, Guido Günther wrote:
>> Package: dnsmasq
>> Version: 2.75-1
>> Severity: normal
>>
>> Hi,
>> I just tried your suggestion with --hostdir=/tmp/test. While I see these
>> log messages nicely:
>>
>> Sep 11 15:53:49 foo dnsmasq[14616]: inotify, new or changed file /tmp/test/libvirt-qemu%3A%2F%2F%2Fsystem.hosts.tmp
>> Sep 11 15:53:49 foo dnsmasq[14616]: read /tmp/test/libvirt-qemu%3A%2F%2F%2Fsystem.hosts.tmp - 3 addresses
>> Sep 11 15:53:49 foo dnsmasq[14616]: inotify, new or changed file /tmp/test/libvirt-qemu%3A%2F%2F%2Fsystem.hosts
>> Sep 11 15:53:49 foo dnsmasq[14616]: read /tmp/test/libvirt-qemu%3A%2F%2F%2Fsystem.hosts - 3 addresses
>>
>> these addresses are _only_ being served if they are already present in
>> the file during daemon start. New entries are not being served. Note
>> that my program writes to a .tmp first and then does a rename so this
>> might confuse dnsmasq (and I can't use s.th. like:
> 
> Even when I skip the writing to .tmp file step dnsmasq does only server
> entries that are present in the file at startup.
> 
> A SIGHUP also lets the daemon server the entries from the hostdir.
> 
> Cheers,
>  -- Guido
> 

Ok, a trivial attempt to reproduce this fails for me. I create a new
file in the directory with a new name in it and I can immediately look
up the new name. What is in your hosts file? Are the names or addresses
re-used?

I would be interesting to set --log-queries, and to look at the cache
dump created in the log by sending SIGUSR1.


Cheers,

Simon.

Message #25 received at submit@bugs.debian.org (full text, mbox, reply):

From: Guido Günther <agx@sigxcpu.org>

To: Simon Kelley <simon@thekelleys.org.uk>

Cc: 798653@bugs.debian.org, Debian Bug Tracking System <submit@bugs.debian.org>

Subject: Re: Bug#798653: hosts from hostsdir=/dir/ picked up but not served

Date: Sat, 19 Sep 2015 12:57:55 +0200

Hi,
On Fri, Sep 18, 2015 at 10:23:57PM +0100, Simon Kelley wrote:
[..snip..]
> > A SIGHUP also lets the daemon server the entries from the hostdir.
> > 
> > Cheers,
> >  -- Guido
> > 
> 
> Ok, a trivial attempt to reproduce this fails for me. I create a new
> file in the directory with a new name in it and I can immediately look
> up the new name. What is in your hosts file? Are the names or addresses
> re-used?

IT works now for, I have no idea what changed:

Addresses are not reused. They come and go but the IPs shouldn't
change. Here's a typical query:

 dnsmasq[8490]: query[A] sid from 127.0.0.1
 dnsmasq[8490]: /tmp/test/ sid is 192.168.122.46
 dnsmasq[8490]: query[AAAA] sid from 127.0.0.1
 dnsmasq[8490]: forwarded sid to 193.189.244.225
 dnsmasq[8490]: forwarded sid to 193.189.244.206
 dnsmasq[8490]: reply sid is NODATA-IPv6
 dnsmasq[8490]: query[MX] sid from 127.0.0.1
 dnsmasq[8490]: forwarded sid to 193.189.244.206

> 
> I would be interesting to set --log-queries, and to look at the cache
> dump created in the log by sending SIGUSR1.

 dnsmasq[984]: time 1442659875
 dnsmasq[984]: cache size 150, 0/418 cache insertions re-used unexpired cache entries.
 dnsmasq[984]: queries forwarded 257, queries answered locally 358
 dnsmasq[984]: queries for authoritative zones 0
 dnsmasq[984]: server 193.189.244.225#53: queries sent 181, retried or failed 4
 dnsmasq[984]: server 193.189.244.206#53: queries sent 178, retried or failed 35

What does not seem to work is that addresses removed from the file are
removed from the cache immediately. So if I remove the entry for sid it
will still be served.

Cheers and thanks a lot for looking into this and dnsmasq in general!
 -- Guido

Message #35 received at 798653@bugs.debian.org (full text, mbox, reply):

From: Simon Kelley <simon@thekelleys.org.uk>

To: Guido Günther <agx@sigxcpu.org>, 798653@bugs.debian.org

Subject: Re: Bug#798653: hosts from hostsdir=/dir/ picked up but not served

Date: Mon, 21 Sep 2015 22:16:26 +0100

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256




> What does not seem to work is that addresses removed from the file
> are removed from the cache immediately. So if I remove the entry
> for sid it will still be served.
> 

That's documented behaviour. New or changed files are read, so extra
information is added, but old information is not removed. Doing that
needs a SIGUSR1 as it's a rather heavyweight operation that involves
deleting everything are re-reading all the relevant files.


Cheers,

Simon.

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Message #40 received at 798653@bugs.debian.org (full text, mbox, reply):

From: Guido Günther <agx@sigxcpu.org>

To: Simon Kelley <simon@thekelleys.org.uk>

Cc: 798653@bugs.debian.org

Subject: Re: Bug#798653: hosts from hostsdir=/dir/ picked up but not served

Date: Tue, 22 Sep 2015 08:47:57 +0200

retitle 798653 Should detect entries removed from files in hostsdir=/dir/ and not serve them anymore
severity 798653 wishlist
thanks

On Mon, Sep 21, 2015 at 10:16:26PM +0100, Simon Kelley wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA256
> 
> 
> 
> 
> > What does not seem to work is that addresses removed from the file
> > are removed from the cache immediately. So if I remove the entry
> > for sid it will still be served.
> > 
> 
> That's documented behaviour. New or changed files are read, so extra
> information is added, but old information is not removed. Doing that
> needs a SIGUSR1 as it's a rather heavyweight operation that involves
> deleting everything are re-reading all the relevant files.

Thanks for the update. It would still be nice functionality though. I've
moved the severity to wishlist but feel free to close it.

Cheers,
 -- Guido

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