Merge pull request #16968 from rgacogne/ddist-fix-compression-dname-srv

dnsdist: Fix the use of compression for SRV and DNAME targets

Author: rgacogne

pdns/dnsdistdist/dnsdist-dnsparser.cc

@@ -132,7 +132,8 @@ bool changeNameInDNSPacket(PacketBuffer& initialPacket, const DNSName& from, con
     pw.startRecord(rrname, ah.d_type, ah.d_ttl, ah.d_class, place, true);
     if (nameOnlyTypes.count(ah.d_type)) {
       rrname = pr.getName();
-      pw.xfrName(rrname, true);
+      // compression is not allowed for DNAME target per rfc6672 section 2.5
+      pw.xfrName(rrname, ah.d_type != QType::DNAME);
     }
     else if (noNameTypes.count(ah.d_type)) {
       pr.xfrBlob(blob);
@@ -173,7 +174,11 @@ bool changeNameInDNSPacket(PacketBuffer& initialPacket, const DNSName& from, con
       /* port */
       pw.xfr16BitInt(pr.get16BitInt());
       auto target = pr.getName();
-      pw.xfrName(target, true);
+      /* Compression is not allowed per rfc2782:
+         "Unless and until permitted by future standards action,
+         name compression is not to be used for this field."
+      */
+      pw.xfrName(target, false);
     }
     else {
       /* sorry, unsafe type */