[1455] restrict empty rrsets to class ANY and NONE

also implement the rest of the handling (adding to messages, converting to text, etc)

src/lib/dns/message.cc

@@ -130,6 +130,11 @@ public:
                const RRClass& rrclass, const RRType& rrtype,
                const RRTTL& ttl, ConstRdataPtr rdata,
                Message::ParseOptions options);
+    // There are also times where an RR needs to be added that
+    // represents an empty RRset. There is no Rdata in that case
+    void addRR(Message::Section section, const Name& name,
+               const RRClass& rrclass, const RRType& rrtype,
+               const RRTTL& ttl, Message::ParseOptions options);
     void addEDNS(Message::Section section, const Name& name,
                  const RRClass& rrclass, const RRType& rrtype,
                  const RRTTL& ttl, const Rdata& rdata);
@@ -740,6 +745,17 @@ MessageImpl::parseSection(const Message::Section section,
         const RRClass rrclass(buffer.readUint16());
         const RRTTL ttl(buffer.readUint32());
         const size_t rdlen = buffer.readUint16();
+
+        // If class is ANY or NONE, rdlength may be zero, to signal
+        // an empty RRset.
+        // (the class check must be done to differentiate from RRTypes
+        // that can have zero length rdata
+        if ((rrclass == RRClass::ANY() || rrclass == RRClass::NONE()) &&
+            rdlen == 0) {
+            addRR(section, name, rrclass, rrtype, ttl, options);
+            ++added;
+            continue;
+        }
         ConstRdataPtr rdata = createRdata(rrtype, rrclass, buffer, rdlen);
 
         if (rrtype == RRType::OPT()) {
@@ -778,6 +794,24 @@ MessageImpl::addRR(Message::Section section, const Name& name,
 }
 
 void
+MessageImpl::addRR(Message::Section section, const Name& name,
+                   const RRClass& rrclass, const RRType& rrtype,
+                   const RRTTL& ttl, Message::ParseOptions options)
+{
+    if ((options & Message::PRESERVE_ORDER) == 0) {
+        vector<RRsetPtr>::iterator it =
+            find_if(rrsets_[section].begin(), rrsets_[section].end(),
+                    MatchRR(name, rrtype, rrclass));
+        if (it != rrsets_[section].end()) {
+            (*it)->setTTL(min((*it)->getTTL(), ttl));
+            return;
+        }
+    }
+    RRsetPtr rrset(new RRset(name, rrclass, rrtype, ttl));
+    rrsets_[section].push_back(rrset);
+}
+
+void
 MessageImpl::addEDNS(Message::Section section,  const Name& name,
                      const RRClass& rrclass, const RRType& rrtype,
                      const RRTTL& ttl, const Rdata& rdata)

src/lib/dns/python/rrset_python.cc

@@ -251,22 +251,28 @@ RRset_toWire(PyObject* self_p, PyObject* args) {
     PyObject* mr;
     const s_RRset* self(static_cast<const s_RRset*>(self_p));
 
-    if (PyArg_ParseTuple(args, "O", &bytes) && PySequence_Check(bytes)) {
-        PyObject* bytes_o = bytes;
-
-        OutputBuffer buffer(4096);
-        self->cppobj->toWire(buffer);
-        PyObject* n = PyBytes_FromStringAndSize(static_cast<const char*>(buffer.getData()), buffer.getLength());
-        PyObject* result = PySequence_InPlaceConcat(bytes_o, n);
-        // We need to release the object we temporarily created here
-        // to prevent memory leak
-        Py_DECREF(n);
-        return (result);
-    } else if (PyArg_ParseTuple(args, "O!", &messagerenderer_type, &mr)) {
-        self->cppobj->toWire(PyMessageRenderer_ToMessageRenderer(mr));
-        // If we return NULL it is seen as an error, so use this for
-        // None returns
-        Py_RETURN_NONE;
+    try {
+        if (PyArg_ParseTuple(args, "O", &bytes) && PySequence_Check(bytes)) {
+            PyObject* bytes_o = bytes;
+
+            OutputBuffer buffer(4096);
+            self->cppobj->toWire(buffer);
+            PyObject* n = PyBytes_FromStringAndSize(static_cast<const char*>(buffer.getData()), buffer.getLength());
+            PyObject* result = PySequence_InPlaceConcat(bytes_o, n);
+            // We need to release the object we temporarily created here
+            // to prevent memory leak
+            Py_DECREF(n);
+            return (result);
+        } else if (PyArg_ParseTuple(args, "O!", &messagerenderer_type, &mr)) {
+            self->cppobj->toWire(PyMessageRenderer_ToMessageRenderer(mr));
+            // If we return NULL it is seen as an error, so use this for
+            // None returns
+            Py_RETURN_NONE;
+        }
+    } catch (const EmptyRRset& ers) {
+        PyErr_Clear();
+        PyErr_SetString(po_EmptyRRset, ers.what());
+        return (NULL);
     }
     PyErr_Clear();
     PyErr_SetString(PyExc_TypeError,

src/lib/dns/python/tests/rrset_python_test.py

@@ -30,6 +30,7 @@ class TestModuleSpec(unittest.TestCase):
         self.test_nsname = Name("ns.example.com")
         self.rrset_a = RRset(self.test_name, RRClass("IN"), RRType("A"), RRTTL(3600))
         self.rrset_a_empty = RRset(self.test_name, RRClass("IN"), RRType("A"), RRTTL(3600))
+        self.rrset_any_a_empty = RRset(self.test_name, RRClass("ANY"), RRType("A"), RRTTL(3600))
         self.rrset_ns = RRset(self.test_domain, RRClass("IN"), RRType("NS"), RRTTL(86400))
         self.rrset_ch_txt = RRset(self.test_domain, RRClass("CH"), RRType("TXT"), RRTTL(0))
         self.MAX_RDATA_COUNT = 100
@@ -90,19 +91,23 @@ class TestModuleSpec(unittest.TestCase):
 
         self.assertRaises(EmptyRRset, self.rrset_a_empty.to_text)
 
+        self.assertEqual("test.example.com. 3600 ANY A\n",
+                         self.rrset_any_a_empty.to_text())
+
     def test_to_wire_buffer(self):
         exp_buffer = bytearray(b'\x04test\x07example\x03com\x00\x00\x01\x00\x01\x00\x00\x0e\x10\x00\x04\xc0\x00\x02\x01\x04test\x07example\x03com\x00\x00\x01\x00\x01\x00\x00\x0e\x10\x00\x04\xc0\x00\x02\x02')
         buffer = bytearray()
         self.rrset_a.to_wire(buffer)
         self.assertEqual(exp_buffer, buffer)
 
-        exp_buffer = bytearray(b'\x04test\x07example\x03com\x00\x00\x01\x00\x01\x00\x00\x0e\x10\x00\x00')
+        self.assertRaises(EmptyRRset, self.rrset_a_empty.to_wire, buffer);
+        self.assertRaises(TypeError, self.rrset_a.to_wire, 1)
+
+        exp_buffer = bytearray(b'\x04test\x07example\x03com\x00\x00\x01\x00\xff\x00\x00\x0e\x10\x00\x00')
         buffer = bytearray()
-        self.rrset_a_empty.to_wire(buffer)
+        self.rrset_any_a_empty.to_wire(buffer)
         self.assertEqual(exp_buffer, buffer)
 
-        self.assertRaises(TypeError, self.rrset_a.to_wire, 1)
-
     def test_to_wire_renderer(self):
         exp_buffer = bytearray(b'\x04test\x07example\x03com\x00\x00\x01\x00\x01\x00\x00\x0e\x10\x00\x04\xc0\x00\x02\x01\xc0\x00\x00\x01\x00\x01\x00\x00\x0e\x10\x00\x04\xc0\x00\x02\x02')
         mr = MessageRenderer()

src/lib/dns/rrset.cc

@@ -43,14 +43,24 @@ AbstractRRset::toText() const {
     string s;
     RdataIteratorPtr it = getRdataIterator();
 
+    // In the case of an empty rrset, just print name, ttl, class, and
+    // type
     if (it->isLast()) {
-        isc_throw(EmptyRRset, "ToText() is attempted for an empty RRset");
+        // But only for class ANY or NONE
+        if (getClass() != RRClass::ANY() &&
+            getClass() != RRClass::NONE()) {
+            isc_throw(EmptyRRset, "toText() is attempted for an empty RRset");
+        }
+        
+        s += getName().toText() + " " + getTTL().toText() + " " +
+             getClass().toText() + " " + getType().toText() + "\n";
+        return (s);
     }
 
     do {
         s += getName().toText() + " " + getTTL().toText() + " " +
-            getClass().toText() + " " + getType().toText() + " " +
-            it->getCurrent().toText() + "\n";
+             getClass().toText() + " " + getType().toText() + " " +
+             it->getCurrent().toText() + "\n";
         it->next();
     } while (!it->isLast());
 
@@ -65,6 +75,12 @@ rrsetToWire(const AbstractRRset& rrset, T& output, const size_t limit) {
     RdataIteratorPtr it = rrset.getRdataIterator();
 
     if (it->isLast()) {
+        // empty rrsets are only allowed for classes ANY and NONE
+        if (rrset.getClass() != RRClass::ANY() &&
+            rrset.getClass() != RRClass::NONE()) {
+            isc_throw(EmptyRRset, "toWire() is attempted for an empty RRset");
+        }
+
         // For an empty RRset, write the name, type, class and TTL once,
         // followed by empty rdata.
         rrset.getName().toWire(output);
@@ -72,7 +88,8 @@ rrsetToWire(const AbstractRRset& rrset, T& output, const size_t limit) {
         rrset.getClass().toWire(output);
         rrset.getTTL().toWire(output);
         output.writeUint16(0);
-        return (n);
+        // Still counts as 1 'rr'; it does show up in the message
+        return (1);
     }
 
     // sort the set of Rdata based on rrset-order and sortlist, and possible
@@ -243,6 +260,7 @@ public:
     ~BasicRdataIterator() {}
     virtual void first() { it_ = datavector_->begin(); }
     virtual void next() { ++it_; }
+    virtual bool currentEmpty() const { return (!(*it_)); }
     virtual const rdata::Rdata& getCurrent() const { return (**it_); }
     virtual bool isLast() const { return (it_ == datavector_->end()); }
 private:

src/lib/dns/rrset.h

@@ -267,8 +267,6 @@ public:
     /// the resulting string with a trailing newline character.
     /// (following the BIND9 convention)
     ///
-    /// The RRset must contain some RDATA; otherwise, an exception of class
-    /// \c EmptyRRset will be thrown.
     /// If resource allocation fails, a corresponding standard exception
     /// will be thrown.
     /// The default implementation may throw other exceptions if the
@@ -299,8 +297,6 @@ public:
     ///
     /// If resource allocation fails, a corresponding standard exception
     /// will be thrown.
-    /// The RRset must contain some RDATA; otherwise, an exception of class
-    /// \c EmptyRRset will be thrown.
     /// The default implementation may throw other exceptions if the
     /// \c toWire() method of the RDATA objects throws.
     /// If a derived class of \c AbstractRRset overrides the default
@@ -560,6 +556,11 @@ public:
     /// This method should never throw an exception.
     virtual void next() = 0;
 
+    /// \brief Check if 'current' is empty (in which case getCurrent() would
+    ///        fail
+    /// \return True if the current Rdata field is NULL, false if not
+    virtual bool currentEmpty() const = 0;
+
     /// \brief Return the current \c Rdata corresponding to the rdata cursor.
     ///
     /// \return A reference to an \c rdata::Rdata object corresponding

src/lib/dns/tests/rrset_unittest.cc

@@ -46,6 +46,10 @@ protected:
                   rrset_a(test_name, RRClass::IN(), RRType::A(), RRTTL(3600)),
                   rrset_a_empty(test_name, RRClass::IN(), RRType::A(),
                                 RRTTL(3600)),
+                  rrset_any_a_empty(test_name, RRClass::ANY(), RRType::A(),
+                                    RRTTL(3600)),
+                  rrset_none_a_empty(test_name, RRClass::NONE(), RRType::A(),
+                                     RRTTL(3600)),
                   rrset_ns(test_domain, RRClass::IN(), RRType::NS(),
                            RRTTL(86400)),
                   rrset_ch_txt(test_domain, RRClass::CH(), RRType::TXT(),
@@ -62,6 +66,8 @@ protected:
     Name test_nsname;
     RRset rrset_a;
     RRset rrset_a_empty;
+    RRset rrset_any_a_empty;
+    RRset rrset_none_a_empty;
     RRset rrset_ns;
     RRset rrset_ch_txt;
     std::vector<unsigned char> wiredata;
@@ -193,11 +199,16 @@ TEST_F(RRsetTest, toText) {
               "test.example.com. 3600 IN A 192.0.2.2\n",
               rrset_a.toText());
 
-    // toText() cannot be performed for an empty RRset.
+    // toText() cannot be performed for an empty RRset
     EXPECT_THROW(rrset_a_empty.toText(), EmptyRRset);
+
+    // Unless it is type ANY or NONE
+    EXPECT_EQ("test.example.com. 3600 ANY A\n",
+              rrset_any_a_empty.toText());
+    EXPECT_EQ("test.example.com. 3600 CLASS254 A\n",
+              rrset_none_a_empty.toText());
 }
 
-#include <iostream>
 TEST_F(RRsetTest, toWireBuffer) {
     rrset_a.toWire(buffer);
 
@@ -207,11 +218,21 @@ TEST_F(RRsetTest, toWireBuffer) {
 
     // toWire() cannot be performed for an empty RRset.
     buffer.clear();
-    rrset_a_empty.toWire(buffer);
+    EXPECT_THROW(rrset_a_empty.toWire(buffer), EmptyRRset);
+
+    // Unless it is type ANY or None
+    buffer.clear();
+    rrset_any_a_empty.toWire(buffer);
     wiredata.clear();
     UnitTestUtil::readWireData("rrset_toWire3", wiredata);
     EXPECT_PRED_FORMAT4(UnitTestUtil::matchWireData, buffer.getData(),
                         buffer.getLength(), &wiredata[0], wiredata.size());
+    buffer.clear();
+    rrset_none_a_empty.toWire(buffer);
+    wiredata.clear();
+    UnitTestUtil::readWireData("rrset_toWire4", wiredata);
+    EXPECT_PRED_FORMAT4(UnitTestUtil::matchWireData, buffer.getData(),
+                        buffer.getLength(), &wiredata[0], wiredata.size());
 }
 
 TEST_F(RRsetTest, toWireRenderer) {
@@ -224,13 +245,25 @@ TEST_F(RRsetTest, toWireRenderer) {
     EXPECT_PRED_FORMAT4(UnitTestUtil::matchWireData, renderer.getData(),
                         renderer.getLength(), &wiredata[0], wiredata.size());
 
+    // toWire() cannot be performed for an empty RRset.
+    buffer.clear();
+    EXPECT_THROW(rrset_a_empty.toWire(buffer), EmptyRRset);
+
+    // Unless it is type ANY or None
     // toWire() can also be performed for an empty RRset.
     buffer.clear();
-    rrset_a_empty.toWire(buffer);
+    rrset_any_a_empty.toWire(buffer);
     wiredata.clear();
     UnitTestUtil::readWireData("rrset_toWire3", wiredata);
     EXPECT_PRED_FORMAT4(UnitTestUtil::matchWireData, buffer.getData(),
                         buffer.getLength(), &wiredata[0], wiredata.size());
+
+    buffer.clear();
+    rrset_none_a_empty.toWire(buffer);
+    wiredata.clear();
+    UnitTestUtil::readWireData("rrset_toWire4", wiredata);
+    EXPECT_PRED_FORMAT4(UnitTestUtil::matchWireData, buffer.getData(),
+                        buffer.getLength(), &wiredata[0], wiredata.size());
 }
 
 // test operator<<.  We simply confirm it appends the result of toText().

src/lib/dns/tests/testdata/rrset_toWire3

@@ -3,8 +3,8 @@
 #
 #(4) t  e  s  t (7) e  x  a  m  p  l  e (3) c  o  m  .
  04 74 65 73 74 07 65 78 61 6d 70 6c 65 03 63 6f 6d 00
-# type/class: A = 1, IN = 1
-00 01 00 01
+# type/class: A = 1, ANY = 255
+00 01 00 ff
 # TTL: 3600
 00 00 0e 10
 #6  7

src/lib/dns/tests/testdata/rrset_toWire4

@@ -0,0 +1,12 @@
+#
+# Rendering an empty IN/A RRset
+#
+#(4) t  e  s  t (7) e  x  a  m  p  l  e (3) c  o  m  .
+ 04 74 65 73 74 07 65 78 61 6d 70 6c 65 03 63 6f 6d 00
+# type/class: A = 1, ANY = 255
+00 01 00 fe
+# TTL: 3600
+00 00 0e 10
+#6  7
+# RDLENGTH: 0
+00 00

src/lib/python/isc/ddns/session.py

@@ -250,4 +250,21 @@ class UpdateSession:
         return not self.__check_prerequisite_name_in_use(datasrc_client, rrset)
 
     def __check_prerequisites(self, datasrc_client):
+        '''Check the prerequisites section of the UPDATE Message.
+           RFC2136 Section 2.4'''
+        for rrset in self.__message.get_section(SECTION_PREREQUISITE):
+            # called atm, but not 'handled' yet
+            if rrset.getClass() == RRClass.ANY():
+                # Check for each RR in the 'set' XXX
+                self.__check_prerequisite_exists(rrset)
+            elif rrset.getClass() == datasrc_client.getClass():
+                self.__check_prerequisite_exists_value(datasrc_client, rrset)
+            elif rrset.getClass() == RRClass.NONE():
+                self.__check_prerequisite_does_not_exist(datasrc_client, rrset)
+            elif rrset.getClass() == RRClass.ANY() and rrset.getType() == RRType.ANY():
+                self.__check_prerequisite_name_exists(datasrc_client, rrset)
+            elif rrset.getClass() == RRClass.NONE() and rrset.getType() == RRType.ANY():
+                self.__check_prerequisite_name_does_not_exist(datasrc_client, rrset)
+            else:
+                print("[XX] ERROR! unknown prerequisite")
         pass

src/lib/python/isc/ddns/tests/session_tests.py

@@ -36,13 +36,15 @@ TEST_ZONE_RECORD = Question(TEST_ZONE_NAME, TEST_RRCLASS, UPDATE_RRTYPE)
 TEST_CLIENT6 = ('2001:db8::1', 53, 0, 0)
 TEST_CLIENT4 = ('192.0.2.1', 53)
 
-def create_update_msg(zones=[TEST_ZONE_RECORD]):
+def create_update_msg(zones=[TEST_ZONE_RECORD], prerequisites=[]):
     msg = Message(Message.RENDER)
     msg.set_qid(5353)           # arbitrary chosen
     msg.set_opcode(Opcode.UPDATE())
     msg.set_rcode(Rcode.NOERROR())
     for z in zones:
         msg.add_question(z)
+    for p in prerequisites:
+        msg.add_rrset(SECTION_PREREQUISITE, p)
 
     renderer = MessageRenderer()
     msg.to_wire(renderer)
@@ -469,7 +471,69 @@ class SessionTest(unittest.TestCase):
         self.__check_prerequisite_name_not_in_use(False, self.__datasrc_client, rrset)
 
     def test_check_prerequisites(self):
-        pass
+        # This test checks if the actual prerequisite-type-specific
+        # methods are called. Whether those succeed or not is tested above (or is it)
+        
+        # Let's first define a number of prereq's that should succeed
+        rrset_exists_yes = isc.dns.RRset(isc.dns.Name("example.org"),
+                                         isc.dns.RRClass.ANY(),
+                                         isc.dns.RRType.SOA(),
+                                         isc.dns.RRTTL(0))
+        rrset_exists_no = isc.dns.RRset(isc.dns.Name("foo.example.org"),
+                                        isc.dns.RRClass.ANY(),
+                                        isc.dns.RRType.SOA(),
+                                        isc.dns.RRTTL(0))
+
+        rrset_exists_value_yes = isc.dns.RRset(isc.dns.Name("www.example.org"),
+                                               isc.dns.RRClass.IN(),
+                                               isc.dns.RRType.A(),
+                                               isc.dns.RRTTL(0))
+        rrset_exists_value_yes.add_rdata(isc.dns.Rdata(isc.dns.RRType.A(),
+                                                       isc.dns.RRClass.IN(),
+                                                       "192.0.2.1"))
+
+        rrset_exists_value_no = isc.dns.RRset(isc.dns.Name("www.example.org"),
+                                              isc.dns.RRClass.IN(),
+                                              isc.dns.RRType.A(),
+                                              isc.dns.RRTTL(0))
+        rrset_exists_value_no.add_rdata(isc.dns.Rdata(isc.dns.RRType.A(),
+                                                      isc.dns.RRClass.IN(),
+                                                      "192.0.2.2"))
+
+        rrset_does_not_exist_yes = isc.dns.RRset(isc.dns.Name("foo.example.org"),
+                                                 isc.dns.RRClass.NONE(),
+                                                 isc.dns.RRType.SOA(),
+                                                 isc.dns.RRTTL(0))
+        rrset_does_not_exist_no = isc.dns.RRset(isc.dns.Name("foo.example.org"),
+                                                isc.dns.RRClass.NONE(),
+                                                isc.dns.RRType.SOA(),
+                                                isc.dns.RRTTL(0))
+
+        name_in_use_yes = isc.dns.RRset(isc.dns.Name("www.example.org"),
+                                        isc.dns.RRClass.ANY(),
+                                        isc.dns.RRType.ANY(),
+                                        isc.dns.RRTTL(0))
+        name_in_use_no = isc.dns.RRset(isc.dns.Name("foo.example.org"),
+                                       isc.dns.RRClass.ANY(),
+                                       isc.dns.RRType.ANY(),
+                                       isc.dns.RRTTL(0))
+
+        name_not_in_use_yes = isc.dns.RRset(isc.dns.Name("foo.example.org"),
+                                            isc.dns.RRClass.ANY(),
+                                            isc.dns.RRType.ANY(),
+                                            isc.dns.RRTTL(0))
+
+        # Create an UPDATE with all 5 'yes' prereqs
+        data, update = create_update_msg([TEST_ZONE_RECORD],
+                                         [
+                                          rrset_exists_yes,
+                                          rrset_does_not_exist_yes,
+                                          name_in_use_yes,
+                                          name_not_in_use_yes,
+                                          rrset_exists_value_yes
+                                         ])
+        print("[XX]")
+        print(update.to_text())
 
 if __name__ == "__main__":
     isc.log.init("bind10")