diff options
| -rw-r--r-- | sys/src/cmd/ndb/dnresolve.c | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/sys/src/cmd/ndb/dnresolve.c b/sys/src/cmd/ndb/dnresolve.c index 56b8024f9..b21289c2b 100644 --- a/sys/src/cmd/ndb/dnresolve.c +++ b/sys/src/cmd/ndb/dnresolve.c @@ -1091,8 +1091,20 @@ procansw(Query *qp, DNSmsg *mp, uchar *srcip, int depth, Dest *p) unique(mp->ns); unique(mp->ar); - if(mp->an) + if(mp->an){ + /* + * only use cname answer when returned. some dns servers + * attach spam address records which poisons the cache. + */ + if((tp = rrremtype(&mp->an, Tcname)) != 0){ + if(mp->an){ + dnslog("removing spam %Q for %Q from %I", mp->an, tp, srcip); + rrfreelist(mp->an); + } + mp->an = tp; + } rrattach(mp->an, (mp->flags & Fauth) != 0); + } if(mp->ar) rrattach(mp->ar, Notauthoritative); if(mp->ns && !cfg.justforw){ |