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ndb/dns: ignore terminating authoritative flag for no-answer when more nameservers are provided

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continue recursing when we get empty but non-negative answer
from a (claimed) authoritative nameserer that provides more
nameservers.

this fixes wordpress dns:

63766.3: sending to 192.0.80.93/ns1.wordpress.com bossypally.files.wordpress.com ip
63766: rcvd OK from 192.0.80.93 (authoritative)
	Q:    bossypally.files.wordpress.com ip
	Auth: files.wordpress.com              5 min           ns   	mdns1.wordpress.com
	      files.wordpress.com              5 min           ns   	mdns2.wordpress.com
	      files.wordpress.com              5 min           ns   	mdns3.wordpress.com
	      files.wordpress.com              5 min           ns   	mdns4.wordpress.com
	      files.wordpress.com              5 min           ns   	mdns5.wordpress.com
	Hint: mdns1.wordpress.com              4 hr            ip   	192.0.75.7
	      mdns2.wordpress.com              4 hr            ip   	198.181.117.7
	      mdns3.wordpress.com              4 hr            ip   	198.181.116.7
	      mdns4.wordpress.com              4 hr            ip   	198.181.118.7
	      mdns5.wordpress.com              4 hr            ip   	192.0.74.7


63766.4: sending to 192.0.75.7/mdns1.wordpress.com bossypally.files.wordpress.com ip
63766: rcvd OK from 192.0.75.7 (authoritative)
	Q:    bossypally.files.wordpress.com ip
	Ans:  bossypally.files.wordpress.com   5 min           ip   	192.0.72.2
	      bossypally.files.wordpress.com   5 min           ip   	192.0.72.3
----------------------------
answer bossypally.files.wordpress.com   5 min           ip   	192.0.72.2
answer bossypally.files.wordpress.com   5 min           ip   	192.0.72.3
----------------------------

note the authoritative flag in the first response from ns1.wordpress.com that
would otherwise terminate the search.
This commit is contained in:
cinap_lenrek 2014-12-08 01:26:07 +01:00
parent 887d02274d
commit 501e69d010
1 changed files with 4 additions and 3 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

7
sys/src/cmd/ndb/dnresolve.c
View file

@ -1229,11 +1229,12 @@ procansw(Query *qp, DNSmsg *mp, int depth, Dest *p)
}
/*
* Any reply from an authoritative server,
* Any reply from an authoritative server
* that does not provide more nameservers,
* or a positive reply terminates the search.
* A negative response now also terminates the search.
*/
if(mp->an != nil || (mp->flags & Fauth)){
if(mp->an || (mp->flags & Fauth) && mp->ns == nil){
if(isnegrname(mp))
qp->dp->respcode = Rname;
else
@ -1267,7 +1268,7 @@ procansw(Query *qp, DNSmsg *mp, int depth, Dest *p)
* if we're a pure resolver, don't recurse, we have
* to forward to a fixed set of named servers.
*/
if(!mp->ns || cfg.resolver && cfg.justforw)
if(mp->ns == nil || cfg.resolver && cfg.justforw)
return Answnone;
tp = rrlookup(ndp, Tns, NOneg);
if(contains(qp->nsrp, tp)){