add EDNS, proper label ordering including embedded zeros, update docs

tdns/README.md

@@ -26,14 +26,14 @@ Features are complete:
  * Delegations
  * Glue records
  * Truncation
+ * EDNS (buffer size, no options)
 
 Missing:
- * Compression (may not fit in the 1000 lines!)
- * EDNS (not 'basic' DNS by our definition, but ok)
+ * Compression (may not fit in the 1200 lines!)
 
 Known broken:
- * Embedded 0s in DNS labels don't yet work
- * Case-insensitive comparison isn't 100% correct 
+ * ~~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
  * TCP/IP does not follow recommended timeouts

tdns/contents.cc

@@ -28,7 +28,9 @@ void loadZones(DNSNode& zones)
   newzone->add({"fra"})->addRRs(NSGen::make({"ns1","fra","powerdns","org"}), NSGen::make({"ns1","fra","powerdns","org"}));
   newzone->add({"ns1"})->addRRs(AGen::make("212.13.14.15"));
   newzone->add({"ns1", "fra"})->addRRs(AGen::make("12.13.14.15"));
-  newzone->add({"NS2", "fra"})->addRRs(AGen::make("12.13.14.16"), AAAAGen::make("::1"));
+  newzone->add({"NS2", "fra"})->addRRs(AGen::make("12.13.14.16"));
+  newzone->add({"ns2", "fra"})->addRRs(AAAAGen::make("::1"));  
+
   newzone->add({"something"})->addRRs(AAAAGen::make("::1"), AGen::make("12.13.14.15"));
   newzone->add({"time"})->addRRs(ClockTXTGen::make("The time is %a, %d %b %Y %T %z"));
 }

tdns/dns-storage.hh

@@ -14,18 +14,28 @@ class dnslabel
 {
 public:
   dnslabel() {}
-  dnslabel(const char* s) : d_s(s) {} // XXX check length here!
+  dnslabel(const char* s) : dnslabel(std::string(s)) {} 
   dnslabel(const std::string& s) : d_s(s) {} // XXX check length here!
   bool operator<(const dnslabel& rhs) const
   {
-    return strcasecmp(d_s.c_str(), rhs.d_s.c_str()) < 0; // XXX locale pain, plus embedded zeros
+    return std::lexicographical_compare(d_s.begin(), d_s.end(), rhs.d_s.begin(), rhs.d_s.end(), charcomp);
   }
   bool operator==(const dnslabel &rhs) const
   {
-    return strcasecmp(d_s.c_str(), rhs.d_s.c_str()) == 0; // XXX locale pain, plus embedded zeros
+    return !(*this < rhs) && !(rhs<*this);
   }
   auto size() const { return d_s.size(); }
   std::string d_s;
+private:
+  static bool charcomp(char a, char b)
+  {
+    if(a >= 0x61 && a <= 0x7A)
+      a -= 0x20;
+    if(b >= 0x61 && b <= 0x7A)
+      b -= 0x20;
+    return a < b;
+  }
+
 };
 std::ostream & operator<<(std::ostream &os, const dnslabel& d);
 
@@ -40,12 +50,12 @@ SMARTENUMEND(RCode)
 
 enum class DNSType : uint16_t
 {
-  A = 1, NS = 2, CNAME = 5, SOA=6, PTR=12, MX=15, TXT=16, AAAA = 28, SRV=33, IXFR = 251, AXFR = 252, ANY = 255
+  A = 1, NS = 2, CNAME = 5, SOA=6, PTR=12, MX=15, TXT=16, AAAA = 28, SRV=33, OPT=41, IXFR = 251, AXFR = 252, ANY = 255
 };
 
 SMARTENUMSTART(DNSType)
-SENUM13(DNSType, A, NS, CNAME, SOA, PTR, MX, TXT, AAAA, IXFR, AAAA, SRV, IXFR, AXFR)
-SENUM(DNSType, ANY)
+SENUM13(DNSType, A, NS, CNAME, SOA, PTR, MX, TXT, AAAA, IXFR, AAAA, SRV, OPT, IXFR)
+SENUM2(DNSType, AXFR, ANY)
 SMARTENUMEND(DNSType)
 
 COMBOENUM4(DNSSection, Question, 0, Answer, 1, Authority, 2, Additional, 3)

tdns/dnsmessages.cc

@@ -22,9 +22,9 @@ void DNSMessageReader::getQuestion(dnsname& name, DNSType& type)
 {
   name=getName();
   type=(DNSType)payload.getUInt16();
+  payload.getUInt16(); // skip the class
 }
 
-
 void DNSMessageWriter::putRR(DNSSection section, const dnsname& name, DNSType type, uint32_t ttl, const std::unique_ptr<RRGen>& content)
 {
   auto cursize = payloadpos;
@@ -55,6 +55,21 @@ void DNSMessageWriter::putRR(DNSSection section, const dnsname& name, DNSType ty
   }
 }
 
+void DNSMessageWriter::putEDNS(uint16_t bufsize, bool doBit)
+{
+  auto cursize = payloadpos;
+  try {
+    putUInt8(0); putUInt16((uint16_t)DNSType::OPT); // 'root' name, our type
+    putUInt16(bufsize); putUInt16(0); putUInt8(doBit ? 0x80 : 0); putUInt8(0);
+    putUInt16(0);
+  }
+  catch(...) {
+    payloadpos = cursize;
+    throw;
+  }
+  dh.nscount = htons(ntohs(dh.nscount)+1);
+}
+
 void DNSMessageWriter::setQuestion(const dnsname& name, DNSType type)
 {
   dh.ancount = dh.arcount = dh.nscount = 0;

tdns/dnsmessages.hh

@@ -25,6 +25,8 @@ struct DNSMessageWriter
   std::vector<uint8_t> payload;
   void setQuestion(const dnsname& name, DNSType type);
   void putRR(DNSSection section, const dnsname& name, DNSType type, uint32_t ttl, const std::unique_ptr<RRGen>& rr);
+
+  void putEDNS(uint16_t bufsize, bool doBit);
   std::string serialize() const;
 
   uint16_t payloadpos=0;

tdns/tdns.cc

@@ -44,12 +44,28 @@ void addAdditional(const DNSNode* bestzone, const dnsname& zone, const vector<dn
 
 bool processQuestion(const DNSNode& zones, DNSMessageReader& dm, const ComboAddress& local, const ComboAddress& remote, DNSMessageWriter& response)
 {
-  dnsname name, origname;
+  dnsname name;
   DNSType type;
   dm.getQuestion(name, type);
-  origname=name; // we munch on this below
+  dnsname origname=name; // we need this for error reporting, we munch the original name
+  bool haveEDNS=false;
   cout<<"Received a query from "<<remote.toStringWithPort()<<" for "<<name<<" and type "<<type<<endl;
-
+  uint16_t newsize=0;
+  bool doBit=false;
+  if(dm.dh.arcount) {
+    if(dm.payload.getUInt8() == 0 && dm.payload.getUInt16() == (uint16_t)DNSType::OPT) {
+      haveEDNS=true;
+      newsize=dm.payload.getUInt16();
+      dm.payload.getUInt16(); // extended RCODE, EDNS version
+      auto flags = dm.payload.getUInt8();
+      doBit = flags & 0x80;
+      dm.payload.getUInt8(); dm.payload.getUInt16(); // ignore rest
+      cout<<"   There was an EDNS section, size supported: "<<newsize<<endl;
+      if(newsize > sizeof(dnsheader))
+        response.payload.resize(newsize - sizeof(dnsheader));
+      
+    }
+  }
   try {
     response.dh = dm.dh;
     response.dh.ad = response.dh.ra = response.dh.aa = 0;
@@ -162,19 +178,25 @@ bool processQuestion(const DNSNode& zones, DNSMessageReader& dm, const ComboAddr
           response.putRR(DNSSection::Answer, zone, DNSType::SOA, rrset.ttl, rrset.contents[0]);
         }
         addAdditional(bestzone, zone, additional, response);
-      
       }
     }
     else {
       cout<<"No zone matched"<<endl;
       response.dh.rcode = (uint8_t)RCode::Refused;
     }
+    if(haveEDNS) {
+      response.putEDNS(newsize, doBit);
+    }
     return true;
   }
   catch(std::out_of_range& e) { // exceeded packet size
     cout<<"Query for '"<<origname<<"'|"<<type<<" got truncated"<<endl;
     response.setQuestion(origname, type); // this resets the packet
     response.dh.tc=1; response.dh.aa=0;
+    if(haveEDNS) {
+      response.putEDNS(newsize, doBit);
+    }
+      
     return true;
   }
   catch(std::exception& e) {