fix querying glue directly

tdns/README.md

@@ -0,0 +1,58 @@
+# teaching DNS
+Welcome to tdns, the teaching authoritative server, implementing all of
+basic DNS in 1000 lines of code.
+
+The goals of tdns are:
+
+ * Protocol correctness
+ * Suitable for educational purposes
+ * Display best practices
+
+Non-goals are:
+ * Performance
+ * Implementing more features
+
+# Current status
+Features are complete:
+
+ * A, AAAA, NS, MX, CNAME, TXT, SOA
+ * UDP & TCP
+ * AXFR
+ * Wildcards
+ * Delegations
+ * Glue records
+
+Missing:
+ * Truncation
+ * Compression (may not fit in the 1000 lines!)
+ * EDNS (not 'basic' DNS by our definition, but ok)
+
+Known broken:
+ * Embedded 0s in DNS labels don't yet work
+ * Case-insensitive comparison isn't 100% correct 
+ * RCode after one CNAME chase
+ * On output (to screen) we do not escape DNS names correctly
+
+The code is not yet in a teachable state, and the layout is somewhat
+confusing: some stuff is in the wrong files.
+
+# Layout
+Key to a good DNS implementation is having a faithful DNS storage model.
+Over the decades, many many nameservers have started out with an incorrect
+storage model, leading to pain later on with empty non-terminals, setting
+the 'AA' bit on glue (or not) and eventually DNSSEC ordering problems.
+
+When storing DNS as a tree, as described in RFC 1034, a lot of things go
+right "automatically".
+
+The core or `tdns` therefore is the tree of nodes as intended in 1034. This
+is implemented in `dns-storage.cc` and `dns-storage.hh`. 
+
+This lookup mechanism will tell you if a name is fully present in a zone, or
+if it was matched by an NS record. It will also perform wildcard matching,
+but not CNAME chasing.
+
+# Best practices
+The code does not do any form of DNS escaping. Instead, DNS names are stored
+and manipulated as a sequence of DNS labels. So instead of messing with
+"www.powerdns.org", we use {"www", "powerdns", "org"}. 

tdns/dns-storage.cc

@@ -18,11 +18,15 @@ bool dnsname::makeRelative(const dnsname& root)
   return true;
 }
 
-const DNSNode* DNSNode::find(dnsname& name, dnsname& last, bool* passedZonecut) const
+const DNSNode* DNSNode::find(dnsname& name, dnsname& last, const DNSNode** passedZonecut, dnsname* zonecutname) const
 {
   cout<<"find for '"<<name<<"', last is now '"<<last<<"'"<<endl;
-  if(!last.empty() && passedZonecut && rrsets.count(DNSType::NS)) {
-    *passedZonecut=true;
+  if(!last.empty() && rrsets.count(DNSType::NS)) {
+    cout<<"  passed a zonecut, making note of this"<<endl;
+    if(passedZonecut)
+      *passedZonecut=this;
+    if(zonecutname)
+      *zonecutname=last;
   }
 
   if(name.empty()) {
@@ -55,7 +59,7 @@ const DNSNode* DNSNode::find(dnsname& name, dnsname& last, bool* passedZonecut)
   cout<<"  Had match, continuing to child '"<<iter->first<<"'"<<endl;
   last.push_front(name.back());
   name.pop_back();
-  return iter->second.find(name, last, passedZonecut);
+  return iter->second.find(name, last, passedZonecut, zonecutname);
 }
 
 DNSNode* DNSNode::add(dnsname name) 

tdns/dns-storage.hh

@@ -81,7 +81,7 @@ struct DNSLabelCompare: public std::binary_function<std::string, std::string, bo
 
 struct DNSNode
 {
-  const DNSNode* find(dnsname& name, dnsname& last, bool* passedZonecut=0) const;
+  const DNSNode* find(dnsname& name, dnsname& last, const DNSNode** passedZonecut=0, dnsname* zonecutname=0) const;
   DNSNode* add(dnsname name);
   std::map<dnslabel, DNSNode, DNSLabelCompare> children;
   std::map<DNSType, RRSet > rrsets;

tdns/tdns.cc

@@ -76,43 +76,42 @@ try
     response.dh.aa = 1; 
     
     auto bestzone = fnd->zone;
-    dnsname searchname(name), lastnode;
-    bool passedZonecut=false;
+    dnsname searchname(name), lastnode, zonecutname;
+    const DNSNode* passedZonecut=0;
     int CNAMELoopCount = 0;
-  loopCNAME:;
-    passedZonecut=false;
-    lastnode.clear();
-    auto node = bestzone->find(searchname, lastnode, &passedZonecut);
-    if(passedZonecut)
-      response.dh.aa = false;
     
+  loopCNAME:;
+    lastnode.clear();
+    zonecutname.clear();
+    auto node = bestzone->find(searchname, lastnode, &passedZonecut, &zonecutname);
+
     if(!node) {
       cout<<"Found nothing in zone '"<<zone<<"' for lhs '"<<name<<"'"<<endl;
     }
-    else if(!searchname.empty()) {
-      cout<<"This was a partial match, searchname now "<<searchname<<endl;
+    else if(passedZonecut) {
+      response.dh.aa = false;
+      cout<<"This is a delegation, zonecutname: '"<<zonecutname<<"'"<<endl;
       
-      for(const auto& rr: node->rrsets) {
+      for(const auto& rr: passedZonecut->rrsets) {
         cout<<"  Have type "<<rr.first<<endl;
       }
-      auto iter = node->rrsets.find(DNSType::NS);
-      if(iter != node->rrsets.end() && passedZonecut) {
-        cout<<"Have delegation"<<endl;
+      auto iter = passedZonecut->rrsets.find(DNSType::NS);
+      if(iter != passedZonecut->rrsets.end()) {
         const auto& rrset = iter->second;
         vector<dnsname> toresolve;
         for(const auto& rr : rrset.contents) {
-          response.putRR(DNSSection::Authority, lastnode+zone, DNSType::NS, rrset.ttl, rr);
+          response.putRR(DNSSection::Authority, zonecutname+zone, DNSType::NS, rrset.ttl, rr);
           toresolve.push_back(dynamic_cast<NameGenerator*>(rr.get())->d_name);
         }
 
         addAdditional(bestzone, zone, toresolve, response);
       }
-      else {
-        cout<<"This is an NXDOMAIN situation"<<endl;
-        const auto& rrset = fnd->zone->rrsets[DNSType::SOA];
-        response.dh.rcode = (int)RCode::Nxdomain;
-        response.putRR(DNSSection::Authority, zone, DNSType::SOA, rrset.ttl, rrset.contents[0]);
-      }
+    }
+    else if(!searchname.empty()) {
+      cout<<"This is an NXDOMAIN situation"<<endl;
+      const auto& rrset = fnd->zone->rrsets[DNSType::SOA];
+      response.dh.rcode = (int)RCode::Nxdomain;
+      response.putRR(DNSSection::Authority, zone, DNSType::SOA, rrset.ttl, rrset.contents[0]);
     }
     else {
       cout<<"Found something in zone '"<<zone<<"' for lhs '"<<name<<"', searchname now '"<<searchname<<"', lastnode '"<<lastnode<<"', passedZonecut="<<passedZonecut<<endl;
@@ -338,6 +337,7 @@ void loadZones(DNSNode& zones)
 
   newzone->add({"ns1", "fra"})->rrsets[DNSType::A].add(AGenerator::make("12.13.14.15"));
   newzone->add({"NS2", "fra"})->rrsets[DNSType::A].add(AGenerator::make("12.13.14.16"));
+  newzone->add({"NS2", "fra"})->rrsets[DNSType::AAAA].add(AAAAGenerator::make("::1"));
 }
 
 int main(int argc, char** argv)