[Dnsmasq-discuss] unwanted debug messages

[e9hack]

Hi,

since some time, the log is flooded with messages like this:

Fri Dec 29 20:53:50 2017 daemon.warn dnsmasq[20961]: reducing DNS packet size for nameserver 217.237.151.142 to 1280
(17, 1280)

I did change the name server and start dnsmasq with the option '-edns-packet-max=1280'. It doesn't relay help. I did
check the related source code. I don't understand the source code, but it looks strange for me.

I did add an additional check and now I don't get this messages any more.

--- forward.c.save 2017-12-14 23:40:48.000000000 +0100
+++ forward.c 2017-12-29 21:34:51.131218864 +0100
@@ -853,8 +853,8 @@
/* We tried resending to this server with a smaller maximum size and got an answer.
Make that permanent. To avoid reduxing the packet size for an single dropped packet,
only do this when we get a truncated answer, or one larger than the safe size. */
- if (server && (forward->flags & FREC_TEST_PKTSZ) &&
- ((header->hb3 & HB3_TC) || n >= SAFE_PKTSZ))
+ if ((server && (forward->flags & FREC_TEST_PKTSZ) &&
+ ((header->hb3 & HB3_TC) || n >= SAFE_PKTSZ)) && server->edns_pktsz > SAFE_PKTSZ)
{
server->edns_pktsz = SAFE_PKTSZ;
prettyprint_addr(&server->addr, daemon->addrbuff);

Regards,
Hartmut

[Simon Kelley]

I just committed a patch which does this, and some other changes to make
this work better.


Cheers,

Simon.

Post by e9hack
Hi,
Fri Dec 29 20:53:50 2017 daemon.warn dnsmasq[20961]: reducing DNS packet size for nameserver 217.237.151.142 to 1280
(17, 1280)
I did change the name server and start dnsmasq with the option '-edns-packet-max=1280'. It doesn't relay help. I did
check the related source code. I don't understand the source code, but it looks strange for me.
I did add an additional check and now I don't get this messages any more.
--- forward.c.save 2017-12-14 23:40:48.000000000 +0100
+++ forward.c 2017-12-29 21:34:51.131218864 +0100
@@ -853,8 +853,8 @@
/* We tried resending to this server with a smaller maximum size and got an answer.
Make that permanent. To avoid reduxing the packet size for an single dropped packet,
only do this when we get a truncated answer, or one larger than the safe size. */
- if (server && (forward->flags & FREC_TEST_PKTSZ) &&
- ((header->hb3 & HB3_TC) || n >= SAFE_PKTSZ))
+ if ((server && (forward->flags & FREC_TEST_PKTSZ) &&
+ ((header->hb3 & HB3_TC) || n >= SAFE_PKTSZ)) && server->edns_pktsz > SAFE_PKTSZ)
{
server->edns_pktsz = SAFE_PKTSZ;
prettyprint_addr(&server->addr, daemon->addrbuff);
Regards,
Hartmut
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