Adding upstream version 2.4.1.upstream/2.4.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 958 insertions, 0 deletions

diff --git a/src/lib/dns/rrset.h b/src/lib/dns/rrset.h
new file mode 100644
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--- /dev/null
+++ b/src/lib/dns/rrset.h
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+// Copyright (C) 2010-2021 Internet Systems Consortium, Inc. ("ISC")
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#ifndef RRSET_H
+#define RRSET_H 1
+
+#include <iostream>
+#include <string>
+
+#include <boost/shared_ptr.hpp>
+
+#include <dns/exceptions.h>
+
+#include <dns/rdata.h>
+#include <dns/rrtype.h>
+
+namespace isc {
+namespace util {
+class OututBuffer;
+}
+
+namespace dns {
+
+///
+/// \brief A standard DNS module exception that is thrown if an RRset object
+/// does not contain any RDATA where required.
+///
+class EmptyRRset : public isc::dns::Exception {
+public:
+    EmptyRRset(const char* file, size_t line, const char* what) :
+        isc::dns::Exception(file, line, what) {}
+};
+
+// forward declarations
+class Name;
+class RRType;
+class RRClass;
+class RRTTL;
+class AbstractMessageRenderer;
+class AbstractRRset;
+class BasicRRset;
+class RdataIterator;
+class BasicRRsetImpl;
+class RRset;
+
+/// \brief A pointer-like type pointing to an \c RRset object.
+///
+/// This type is commonly used as an argument of various functions defined
+/// in this library in order to handle RRsets in a polymorphic manner.
+typedef boost::shared_ptr<AbstractRRset> RRsetPtr;
+
+/// \brief A pointer-like type pointing to an (immutable) \c RRset
+/// object.
+///
+/// This type is commonly used as an argument of various functions defined
+/// in this library in order to handle RRsets in a polymorphic manner.
+typedef boost::shared_ptr<const AbstractRRset> ConstRRsetPtr;
+
+/// \brief A pointer-like type point to an \c RdataIterator object.
+typedef boost::shared_ptr<RdataIterator> RdataIteratorPtr;
+
+/// \brief The \c AbstractRRset class is an abstract base class that
+/// models a DNS RRset.
+///
+/// An object of (a specific derived class of) \c AbstractRRset
+/// models an RRset as described in the DNS standard:
+/// A set of DNS resource records (RRs) of the same type and class.
+/// The standard requires the TTL of all RRs in an RRset be the same;
+/// this class follows that requirement.
+
+/// Note about duplicate RDATA: RFC2181 states that it's meaningless that an
+/// RRset contains two identical RRs and that name servers should suppress
+/// such duplicates.
+/// This class is not responsible for ensuring this requirement: For example,
+/// \c addRdata() method doesn't check if there's already RDATA identical
+/// to the one being added.
+/// This is because such checks can be expensive, and it's often easy to
+/// ensure the uniqueness requirement at the %data preparation phase
+/// (e.g. when loading a zone).
+/// When parsing an incoming DNS message, the uniqueness may not be guaranteed,
+/// so the application needs to detect and ignore any duplicate RDATA
+/// (the \c Message class of this library should provide this responsibility).
+///
+/// Another point to note is that \c AbstractRRset and its derived classes
+/// allow an object to have an empty set of RDATA.
+/// Even though there's no corresponding notion in the protocol specification,
+/// it would be more intuitive for a container-like %data structure
+/// to allow an empty set.
+///
+/// Since \c AbstractRRset is an abstract class, it is generally used
+/// via a pointer (or pointer like object) or a reference.
+/// In particular, \c RRsetPtr, a pointer like type for \c AbstractRRset,
+/// is used for polymorphic RRset operations throughout this library.
+///
+/// The \c AbstractRRset class is also intended to be a major customization
+/// point.  For example, a high performance server implementation may want
+/// to define an optimized "pre-compiled" RRset and provide an optimized
+/// implementation of the \c toWire() method.
+///
+/// Note about design choice: In BIND9, a set of RDATA with a common tuple
+/// of RR class, RR type, and TTL was represented in a structure named
+/// \c rdataset.  Unlike the RRset classes, an \c rdataset did not contain
+/// the information of the owner name.
+/// This might be advantageous if we want to handle "RRsets", that is,
+/// a set of different types of RRset for the same owner name, because
+/// a single "name" structure can be used for multiple RRsets, minimizing
+/// %data copy and memory footprint.
+/// On the other hand, it's inconvenient for API users since in many cases
+/// a pair of name and an \c rdataset must be maintained.  It's also counter
+/// intuitive in implementing protocol operations as an RRset is often used
+/// as an atomic entity in DNS protocols while an \c rdataset is a component
+/// of an RRset.
+///
+/// We have therefore defined the notion of RRset explicitly in our initial
+/// API design.  We believe memory footprint is not a big concern because
+/// RRsets are generally expected to be used as temporary objects, e.g.
+/// while parsing or constructing a DNS message, or searching a DNS %data
+/// source; for longer term purposes such as in-memory %data source entries,
+/// the corresponding %data would be represented in a different, memory
+/// optimized format.  As for the concern about %data copy, we believe
+/// it can be mitigated by using copy-efficient implementation for the
+/// \c Name class implementation, such as reference counted objects.
+/// Later, We plan to perform benchmark tests later to see if this assumption
+/// is valid and to revisit the design if necessary.
+///
+/// Note about terminology: there has been a discussion at the IETF
+/// namedroppers ML about RRset vs RRSet (case of "s")
+/// [http://ops.ietf.org/lists/namedroppers/namedroppers.2009/msg02737.html].
+/// While RFC2181 uses the latter, many other RFCs use the former,
+/// and most of the list members who showed their opinion seem to prefer
+/// "RRset".  We follow that preference in this implementation.
+///
+/// The current design of \c AbstractRRset is still in flux.
+/// There are many open questions in design details:
+///   - support more set-like operations, e.g, merge two RRsets of the same
+///     type?
+///   - more convenient methods or non member utility functions, e.g.
+///      "sort" and "search(find)" method?
+///   - what about comparing two RRsets of the same type?  If we need this,
+///     should it compare rdata's as a set or as a list (i.e. compare
+///     each rdata one by one or as a whole)?  c.f. NLnet Labs' ldns
+///     (http://www.nlnetlabs.nl/projects/ldns/doc/index.html)
+///     has \c ldns_rr_list_compare(), which takes the latter approach
+///     (seemingly assuming the caller sorts the lists beforehand).
+///   - BIND9 libdns has some special DNSSEC-related methods
+///     such as \c addnoqname() or \c addclosest().  Do we need these?
+///     (Probably not.  We wouldn't want to make the class design too
+///     monolithic.)
+///   - Do we need to allow the user to remove specific Rdata?
+///     Probably not, according to the current usage of the BIND9 code.
+class AbstractRRset {
+    ///
+    /// \name Constructors and Destructor
+    ///
+    /// Note: The copy constructor and the assignment operator are intentionally
+    /// defined as private to make it explicit that this is a pure base class.
+    //@{
+private:
+    AbstractRRset(const AbstractRRset& source);
+    AbstractRRset& operator=(const AbstractRRset& source);
+protected:
+    /// \brief The default constructor.
+    ///
+    /// This is intentionally defined as \c protected as this base class should
+    /// never be instantiated (except as part of a derived class).
+    AbstractRRset() {}
+public:
+    /// The destructor.
+    virtual ~AbstractRRset() {}
+    //@}
+
+    ///
+    /// \name Getter and Setter Methods
+    ///
+    /// These methods are generally expected to be exception free, but it's
+    /// not guaranteed at the interface level;
+    /// for example, some performance optimized derived class may manage
+    /// the information corresponding to the class "attributes" to get or set,
+    /// and may require dynamic memory allocation to execute the method.
+    /// Consult the derived class description to see if a specific derived
+    /// \c RRset class may throw an exception from these methods.
+    ///
+    /// Note that setter methods are not provided for \c RRClass and
+    /// \c RRType.  This is intentional.  Since the format and semantics of
+    /// \c Rdata are dependent on the RR type (and RR class for some RR types),
+    /// allowing dynamically modify these attributes can easily lead to a
+    /// bug where the RDATA and type and/or class become inconsistent.
+    /// We want to avoid that situation by restricting the access.
+    //@{
+    /// \brief Returns the number of \c Rdata objects contained in the \c RRset.
+    ///
+    /// Note that an \c RRset with an empty set of \c Rdata can exist, so
+    /// this method may return 0.
+    ///
+    /// \return The number of \c Rdata objects contained.
+    virtual unsigned int getRdataCount() const = 0;
+
+    /// \brief Get the wire format length of the \c AbstractRRset.
+    ///
+    /// This method returns the wire format length of the
+    /// \c AbstractRRset, which is calculated by summing the individual
+    /// lengths of the various fields that make up each RR.
+    ///
+    /// NOTE: When including name lengths, the allocation for
+    /// uncompressed name wire format representation is used.
+    ///
+    /// \return The length of the wire format representation of the
+    /// \c AbstractRRset.
+    /// \throw EmptyRRset if the \c AbstractRRset is empty.
+    virtual uint16_t getLength() const = 0;
+
+    /// \brief Returns the owner name of the \c RRset.
+    ///
+    /// \return A reference to a \c Name class object corresponding to the
+    /// \c RRset owner name.
+    virtual const Name& getName() const = 0;
+
+    /// \brief Returns the RR Class of the \c RRset.
+    ///
+    /// \return A reference to a \c RRClass class object corresponding to the
+    /// RR class of the \c RRset.
+    virtual const RRClass& getClass() const = 0;
+
+    /// \brief Returns the RR Type of the \c RRset.
+    ///
+    /// \return A reference to a \c RRType class object corresponding to the
+    /// RR type of the \c RRset.
+    virtual const RRType& getType() const = 0;
+
+    /// \brief Returns the TTL of the RRset.
+    ///
+    /// \return A reference to a \c RRTTL class object corresponding to the
+    /// TTL of the \c RRset.
+    virtual const RRTTL& getTTL() const = 0;
+
+    /// \brief Updates the TTL of the \c RRset.
+    ///
+    /// \param ttl A reference to a \c RRTTL class object to be copied as the
+    /// new TTL.
+    virtual void setTTL(const RRTTL& ttl) = 0;
+    //@}
+
+    ///
+    /// \name Converter Methods
+    ///
+    /// These methods have the default implementation that can be reused by
+    /// derived classes.
+    /// Since they are defined as pure virtual, derived classes
+    /// that want to reuse the default implementation must explicitly
+    /// invoke their base class version (see the description for
+    /// <code>addRdata(const rdata::Rdata&)</code>).
+    ///
+    /// Design Note: the default implementations are defined only using
+    /// other public methods of the \c AbstractRRset class, and could be
+    /// implemented as non member functions (as some C++ textbooks suggest).
+    /// However, since derived classes may want to provide customized versions
+    /// (especially of the \c toWire() method for performance reasons)
+    /// we chose to define them as virtual functions, and, as a result,
+    /// member functions.
+    //@{
+    /// \brief Convert the RRset to a string.
+    ///
+    /// Unlike other similar methods of this library, this method terminates
+    /// the resulting string with a trailing newline character.
+    /// (following the BIND9 convention)
+    ///
+    /// If any RRSIGs are associated with the RRset, they are also
+    /// appended to the returned string.
+    ///
+    /// If the class is not ANY or NONE, 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
+    /// \c toText() method of the RDATA objects throws.
+    /// If a derived class of \c AbstractRRset overrides the default
+    /// implementation, the derived version may throw its own exceptions.
+    ///
+    /// Open issue: We may want to support multiple output formats as
+    /// BIND9 does.  For example, we might want to allow omitting the owner
+    /// name when possible in the context of zone dump.  This is a future
+    /// TODO item.
+    ///
+    /// \return A string representation of the RRset.
+    virtual std::string toText() const = 0;
+
+    /// \brief Render the RRset in the wire format with name compression and
+    /// truncation handling.
+    ///
+    /// This method compresses the owner name of the RRset and domain names
+    /// used in RDATA that should be compressed.
+    /// In addition, this method detects the case where rendering the entire
+    /// RRset would cause truncation, and handles the case appropriately
+    /// (this is a TODO item, and not implemented in this version).
+    ///
+    /// If any RRSIGs are associated with the RRset, they are also rendered.
+    ///
+    /// Note: perhaps we may want to add more arguments to convey optional
+    /// information such as an "rrset-order" policy or how to handle truncation
+    /// case.  This is a TODO item.
+    ///
+    /// If resource allocation fails, a corresponding standard exception
+    /// will be thrown.
+    /// If the class is not ANY or NONE, 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
+    /// implementation, the derived version may throw its own exceptions.
+    ///
+    /// \param renderer DNS message rendering context that encapsulates the
+    /// output buffer and name compression information.
+    /// \return The number of RRs rendered.  If the truncation is necessary
+    /// this value may be different from the number of RDATA objects contained
+    /// in the RRset.
+    virtual unsigned int toWire(AbstractMessageRenderer& renderer) const = 0;
+
+    /// \brief Render the RRset in the wire format without any compression.
+    ///
+    /// See the other toWire() description about possible exceptions.
+    ///
+    /// \param buffer An output buffer to store the wire data.
+    /// \return The number of RRs rendered.
+    virtual unsigned int toWire(isc::util::OutputBuffer& buffer) const = 0;
+    //@}
+
+    ///
+    /// \name RDATA Manipulation Methods
+    ///
+    //@{
+    /// \brief Add an RDATA to the RRset (pointer version).
+    ///
+    /// This method adds the given RDATA (as a pointer-like type to a
+    /// derived class object of \c rdata::Rdata) to the \c RRset.
+    ///
+    /// \param rdata A pointer (like) type of \c rdata::RdataPtr to be added
+    /// to the \c RRset.
+    virtual void addRdata(rdata::ConstRdataPtr rdata) = 0;
+
+    /// \brief Add an RDATA to the RRset (reference version).
+    ///
+    /// This method adds the given RDATA (as a reference to a
+    /// derived class object of \c rdata::Rdata) to the \c RRset.
+    ///
+    /// This method has the default implementation that can be reused by
+    /// derived classes.
+    /// Since this method is defined as pure virtual, derived classes
+    /// that want to reuse the default implementation must explicitly
+    /// invoke this base class version.
+    /// For example, if the class \c CustomizedRRset, a derived class of
+    /// \c AbstractRRset, wants to reuse the default implementation of
+    /// \c %addRdata() (reference version), it would be defined as follows:
+    /// \code void
+    /// CustomizedRRset::addRdata(const rdata::Rdata& rdata)
+    /// {
+    ///     AbstractRRset::addRdata(rdata);
+    /// }
+    /// \endcode
+    ///
+    /// This method is more strictly typed than the pointer version:
+    /// If \c rdata does not refer to the appropriate derived
+    /// \c Rdata class
+    /// for the \c RRType for this \c RRset, it throws an exception of class
+    /// \c std::bad_cast.
+    /// 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
+    /// implementation, the derived version may throw its own exceptions.
+    ///
+    /// The default implementation simply constructs an \c rdata::RdataPtr
+    /// object from a newly allocated RDATA object copying from parameter
+    /// \c rdata, and calls the other version of
+    /// \c addRdata(const rdata::RdataPtr).
+    /// So it is inherently less efficient than the other version.
+    /// Still, this version would offer a more intuitive interface and is
+    /// provided as such.
+    ///
+    /// NOTE: Because a new Rdata object is constructed, this method can
+    /// throw a std::bad_cast exception if this RRset's class is NONE,
+    /// or if some other error occurs. If you want to be able to add
+    /// RDATA to an RRset whose class is NONE, please use the other
+    /// variant of \c addRdata() which accepts a \c ConstRdataPtr
+    /// argument.
+    ///
+    /// \param rdata A reference to a \c rdata::RdataPtr (derived) class
+    /// object, a copy of which is to be added to the \c RRset.
+    virtual void addRdata(const rdata::Rdata& rdata) = 0;
+
+    /// \brief Add an RDATA to the RRset (string version).
+    ///
+    /// This method constructs an Rdata object from the given
+    /// \c rdata_str in presentation format and adds it to the \c RRset.
+    ///
+    /// \param rdata_str RDATA string in presentation format.
+    /// \throw InvalidRdataText if the \c rdata_str is invalid for this
+    /// \c RRset.
+    virtual void addRdata(const std::string& rdata_str) = 0;
+
+    /// \brief Return an iterator to go through all RDATA stored in the
+    /// \c RRset.
+    ///
+    /// The rdata cursor of the returned iterator will point to the first
+    /// RDATA, that is, it effectively calls \c RdataIterator::first()
+    /// internally.
+    ///
+    /// Using the design pattern terminology, \c getRdataIterator()
+    /// is an example of a <em>factory method</em>.
+    ///
+    /// Whether this method throws an exception depends on the actual
+    /// implementation of the derived \c AbstractRRset class, but in general
+    /// it will involve resource allocation and can throw a standard exception
+    /// if it fails.
+    ///
+    /// \return A pointer-like object pointing to the derived \c RdataIterator
+    /// object.
+    virtual RdataIteratorPtr getRdataIterator() const = 0;
+    //@}
+
+    ///
+    /// \name Associated RRSIG methods
+    ///
+    /// These methods access an "associated" RRset, that containing the DNSSEC
+    /// signatures for this RRset.  It can be argued that this is not a
+    /// fundamental part of the RRset abstraction, since RFC 2181 defined an
+    /// RRset as a group of records with the same label, class and type but
+    /// different data.  However, BIND 10 had to deal with DNSSEC and in
+    /// practice, including the information at the AbstractRRset level makes
+    /// implementation easier.  (If a class is ever needed that must be
+    /// ignorant of the idea of an associated RRSIG RRset - e.g. a specialised
+    /// RRSIG RRset class - these methods can just throw a "NotImplemented"
+    /// exception.) DNSSEC is unlikely to be ever needed in Kea, but it does
+    /// not make sense to redesign the abstract RRSet class now.
+    //@{
+    /// \brief Return pointer to this RRset's RRSIG RRset
+    ///
+    /// \return Pointer to the associated RRSIG RRset or null if there is none.
+    virtual RRsetPtr getRRsig() const = 0;
+
+    /// \brief Returns the number of \c RRSIG records associated with
+    /// the \c RRset.
+    ///
+    /// Note that an \c RRset with no RRSIG records may exist, so this
+    /// method may return 0.
+    ///
+    /// \return The number of \c RRSIG records associated.
+    virtual unsigned int getRRsigDataCount() const = 0;
+
+    /// \brief Adds RRSIG RRset RRs to the associated RRSIG RRset
+    ///
+    /// Adds the (assumed) RRSIG rdata the RRSIG RRset associated with this
+    /// RRset.  If one does not exist, it is created using the data given.
+    ///
+    /// \param rdata Pointer to RRSIG rdata to be added.
+    virtual void addRRsig(const rdata::ConstRdataPtr& rdata) = 0;
+
+    /// \brief Adds RRSIG RRset RRs to the associated RRSIG RRset
+    ///
+    /// Adds the (assumed) RRSIG rdata the RRSIG RRset associated with this
+    /// RRset.  If one does not exist, it is created using the data given.
+    ///
+    /// (This overload is for an older version of boost that doesn't support
+    /// conversion from shared_ptr<X> to shared_ptr<const X>.)
+    ///
+    /// \param rdata Pointer to RRSIG rdata to be added.
+    virtual void addRRsig(const rdata::RdataPtr& rdata) = 0;
+
+    /// \brief Adds RRSIG RRset RRs to the associated RRSIG RRset
+    ///
+    /// Adds the signatures in the given (assumed) RRSIG RRset to the RRSIG
+    /// RRset associated with this RRset.  If one does not exist, it is created
+    /// using the data given.
+    ///
+    /// \param sigs RRSIG RRset containing signatures to be added to the
+    ///             RRSIG RRset associated with this class.
+    virtual void addRRsig(const AbstractRRset& sigs) = 0;
+
+    /// \brief Adds RRSIG RRset RRs to the associated RRSIG RRset
+    ///
+    /// Adds the signatures in the given (assumed) RRSIG RRset to the RRSIG
+    /// RRset associated with this RRset.  If one does not exist, it is created
+    /// using the data given.
+    ///
+    /// \param sigs Pointer to a RRSIG RRset containing signatures to be added
+    ///             to the RRSIG RRset associated with this class.
+    virtual void addRRsig(const ConstRRsetPtr& sigs) = 0;
+
+    /// \brief Adds RRSIG RRset RRs to the associated RRSIG RRset
+    ///
+    /// Adds the signatures in the given (assumed) RRSIG RRset to the RRSIG
+    /// RRset associated with this RRset.  If one does not exist, it is created
+    /// using the data given.
+    ///
+    /// (This overload is for an older version of boost that doesn't support
+    /// conversion from shared_ptr<X> to shared_ptr<const X>.)
+    ///
+    /// \param sigs Pointer to a RRSIG RRset containing signatures to be added
+    ///             to the RRSIG RRset associated with this class.
+    virtual void addRRsig(const RRsetPtr& sigs) = 0;
+
+    /// \brief Clear the RRSIGs for this RRset
+    virtual void removeRRsig() = 0;
+
+    /// \brief Check whether two RRsets are of the same kind
+    ///
+    /// Checks if two RRsets have the same name, RR type, and RR class.
+    ///
+    /// \param other Pointer to another AbstractRRset to compare
+    ///              against.
+    virtual bool isSameKind(const AbstractRRset& other) const;
+    //@}
+
+};
+
+/// \brief The \c RdataIterator class is an abstract base class that
+/// provides an interface for accessing RDATA objects stored in an RRset.
+///
+/// While different derived classes of \c AbstractRRset may maintain the RDATA
+/// objects in different ways, the \c RdataIterator class provides a
+/// unified interface to iterate over the RDATA objects in a polymorphic
+/// manner.
+///
+/// Each derived class of \c AbstractRRset is expected to provide a concrete
+/// derived class of \c RdataIterator, and each derived \c RdataIterator
+/// class implements the unified interface in a way specific to the
+/// implementation of the corresponding derived \c AbstractRRset class.
+/// Using the design pattern terminology, this is a typical example of
+/// the \e Iterator pattern.
+///
+/// The RDATA objects stored in the \c RRset are considered to form
+/// a unidirectional list from the \c RdataIterator point of view (while
+/// the actual implementation in the derived \c RRset may not use a list).
+/// We call this unidirectional list the <em>rdata list</em>.
+///
+/// An \c RdataIterator object internally (and conceptually) holds a
+/// <em>rdata cursor</em>, which points to a specific item of the rdata list.
+///
+/// Note about design choice: as is clear from the interface, \c RdataIterator
+/// is not compatible with the standard iterator classes.
+/// Although it would be useful (for example, we could then use STL algorithms)
+/// and is not necessarily impossible, it would make the iterator implementation
+/// much more complicated.
+/// For instance, any standard iterator must be assignable and
+/// copy-constructible.
+/// So we'd need to implement \c RdataIterator::operator=() in a polymorphic
+/// way.  This will require non-trivial implementation tricks.
+/// We believe the simplified iterator interface as provided by the
+/// \c RdataIterator class is sufficient in practice:
+/// Most applications will simply go through the RDATA objects contained in
+/// an RRset, examining (and possibly using) each object, as one path
+/// operation.
+class RdataIterator {
+    ///
+    /// \name Constructors and Destructor
+    ///
+    /// Note: The copy constructor and the assignment operator are intentionally
+    /// defined as private to make it explicit that this is a pure base class.
+    //@{
+protected:
+    /// \brief The default constructor.
+    ///
+    /// This is intentionally defined as \c protected as this base class should
+    /// never be instantiated (except as part of a derived class).
+    RdataIterator() {}
+public:
+    /// \brief Destructor
+    virtual ~RdataIterator() {}
+private:
+    RdataIterator(const RdataIterator& source);
+    RdataIterator& operator=(const RdataIterator& source);
+    //@}
+
+public:
+    /// \brief Move the rdata cursor to the first RDATA in the rdata list
+    /// (if any).
+    ///
+    /// This method can safely be called multiple times, even after moving
+    /// the rdata cursor forward by the \c next() method.
+    ///
+    /// This method should never throw an exception.
+    virtual void first() = 0;
+
+    /// \brief Move the rdata cursor to the next RDATA in the rdata list
+    /// (if any).
+    ///
+    /// This method should never throw an exception.
+    virtual void next() = 0;
+
+    /// \brief Return the current \c Rdata corresponding to the rdata cursor.
+    ///
+    /// \return A reference to an \c rdata::Rdata object corresponding
+    /// to the rdata cursor.
+    virtual const rdata::Rdata& getCurrent() const = 0;
+
+    /// \brief Return true iff the rdata cursor has reached the end of the
+    /// rdata list.
+    ///
+    /// Once this method returns \c true, the behavior of any subsequent
+    /// call to \c next() or \c getCurrent() is undefined.
+    /// Likewise, the result of \c isLast() call followed by such undefined
+    /// operations is also undefined.
+    ///
+    /// This method should never throw an exception.
+    ///
+    /// \return \c true if the rdata cursor has reached the end of the
+    /// rdata list; otherwise \c false.
+    virtual bool isLast() const = 0;
+};
+
+/// \brief The \c BasicRRset class is a concrete derived class of
+/// \c AbstractRRset that defines a straightforward RRset implementation.
+///
+/// This class is designed to be as portable as possible, and so it adopts
+/// the Pimpl idiom to hide as many details as possible.
+/// Performance is a secondary concern for this class.
+///
+/// This class is intended to be used by applications that only need
+/// moderate level of performance with full functionality provided by
+/// the \c AbstractRRset interfaces.
+/// Highly performance-sensitive applications, such as a large scale
+/// authoritative or caching name servers will implement and use a customized
+/// version of derived \c AbstractRRset class.
+class BasicRRset : public AbstractRRset {
+    ///
+    /// \name Constructors and Destructor
+    ///
+    /// Note: The copy constructor and the assignment operator are intentionally
+    /// defined as private.  The intended use case wouldn't require copies of
+    /// a \c BasicRRset object; once created, it would normally be used
+    /// as a \c const object (via references).
+    //@{
+private:
+    BasicRRset(const BasicRRset& source);
+    BasicRRset& operator=(const BasicRRset& source);
+public:
+    /// \brief Constructor from (mostly) fixed parameters of the RRset.
+    ///
+    /// This constructor is normally expected to be exception free, but
+    /// copying the name may involve resource allocation, and if it fails
+    /// the corresponding standard exception will be thrown.
+    ///
+    /// \param name The owner name of the RRset.
+    /// \param rrclass The RR class of the RRset.
+    /// \param rrtype The RR type of the RRset.
+    /// \param ttl The TTL of the RRset.
+    BasicRRset(const Name& name, const RRClass& rrclass,
+               const RRType& rrtype, const RRTTL& ttl);
+    /// \brief The destructor.
+    virtual ~BasicRRset();
+    //@}
+
+    ///
+    /// \name Getter and Setter Methods
+    ///
+    //@{
+    /// \brief Returns the number of \c Rdata objects contained in the \c RRset.
+    ///
+    /// This method never throws an exception.
+    ///
+    /// \return The number of \c Rdata objects contained.
+    virtual unsigned int getRdataCount() const;
+
+    /// \brief Get the wire format length of the \c BasicRRset.
+    ///
+    /// \return The length of the wire format representation of the
+    /// \c BasicRRset.
+    /// \throw EmptyRRset if the \c BasicRRset is empty.
+    virtual uint16_t getLength() const;
+
+    /// \brief Returns the owner name of the \c RRset.
+    ///
+    /// This method never throws an exception.
+    ///
+    /// \return A reference to a \c Name class object corresponding to the
+    /// \c RRset owner name.
+    virtual const Name& getName() const;
+
+    /// \brief Returns the RR Class of the \c RRset.
+    ///
+    /// This method never throws an exception.
+    ///
+    /// \return A reference to a \c RRClass class object corresponding to the
+    /// RR class of the \c RRset.
+    virtual const RRClass& getClass() const;
+
+    /// \brief Returns the RR Type of the \c RRset.
+    ///
+    /// This method never throws an exception.
+    ///
+    /// \return A reference to a \c RRType class object corresponding to the
+    /// RR type of the \c RRset.
+    virtual const RRType& getType() const;
+
+    /// \brief Returns the TTL of the \c RRset.
+    ///
+    /// This method never throws an exception.
+    ///
+    /// \return A reference to a \c RRTTL class object corresponding to the
+    /// TTL of the \c RRset.
+    virtual const RRTTL& getTTL() const;
+
+    /// \brief Updates the TTL of the \c RRset.
+    ///
+    /// This method never throws an exception.
+    ///
+    /// \param ttl A reference to a \c RRTTL class object to be copied as the
+    /// new TTL.
+    virtual void setTTL(const RRTTL& ttl);
+    //@}
+
+    ///
+    /// \name Converter Methods
+    ///
+    //@{
+    /// \brief Convert the RRset to a string.
+    ///
+    /// This method simply uses the default implementation.
+    /// See \c AbstractRRset::toText().
+    virtual std::string toText() const;
+
+    /// \brief Render the RRset in the wire format with name compression and
+    /// truncation handling.
+    ///
+    /// This method simply uses the default implementation.
+    /// See \c AbstractRRset::toWire(MessageRenderer&)const.
+    virtual unsigned int toWire(AbstractMessageRenderer& renderer) const;
+
+    /// \brief Render the RRset in the wire format without any compression.
+    ///
+    /// This method simply uses the default implementation.
+    /// See \c AbstractRRset::toWire(OutputBuffer&)const.
+    virtual unsigned int toWire(isc::util::OutputBuffer& buffer) const;
+    //@}
+
+    ///
+    /// \name RDATA manipulation methods
+    ///
+    //@{
+    /// \brief Add an RDATA to the RRset (pointer version).
+    ///
+    /// This method is normally expected to be exception free, but it may
+    /// involve resource allocation, and if it fails the corresponding
+    /// standard exception will be thrown.
+    ///
+    /// \param rdata A pointer (like) type of \c rdata::RdataPtr to be added
+    /// to the \c BasicRRset.
+    virtual void addRdata(rdata::ConstRdataPtr rdata);
+
+    /// \brief Add an RDATA to the RRset (reference version).
+    ///
+    /// This method simply uses the default implementation.
+    /// See \c AbstractRRset::addRdata(const rdata::Rdata&).
+    virtual void addRdata(const rdata::Rdata& rdata);
+
+    /// \brief Add an RDATA to the RRset (string version).
+    ///
+    /// \param rdata_str RDATA string in presentation format.
+    /// \throw InvalidRdataText if the \c rdata_str is invalid for this
+    /// \c RRset.
+    virtual void addRdata(const std::string& rdata_str);
+
+    /// \brief Return an iterator to go through all RDATA stored in the
+    /// \c BasicRRset.
+    ///
+    /// This is a concrete derived implementation of
+    /// \c AbstractRRset::getRdataIterator().
+    ///
+    /// This method dynamically allocates resources.  If it fails it will
+    /// throw the corresponding standard exception.
+    /// The iterator methods for the \c BasicRRset class are exception free.
+    ///
+    /// \return A pointer-like object pointing to the derived \c RdataIterator
+    /// object for the \c BasicRRset class.
+    virtual RdataIteratorPtr getRdataIterator() const;
+    //@}
+
+    ///
+    /// \name Associated RRSIG methods
+    ///
+    /// The associated RRSIG RRset is not supported in BasicRRset.  For
+    /// ease of use, getRRsig() returns a null pointer (indicating no RRset).
+    /// The addRRsig()/removeRRsig() methods throw a "NotImplemented"
+    /// exception - if you are using a BasicRRset, you should not be trying
+    /// to modify signatures on it.
+    //@{
+    /// \brief Return pointer to this RRset's RRSIG RRset
+    ///
+    /// \return Null pointer, as this class does not support RRSIG records.
+    virtual RRsetPtr getRRsig() const {
+        return (RRsetPtr());
+    }
+
+    /// \brief Returns the number of \c RRSIG records associated with
+    /// the \c RRset.
+    ///
+    /// \return Always returns 0. Associated RRSIG RRsets are not
+    ///         supported in this class.
+    virtual unsigned int getRRsigDataCount() const {
+        return (0);
+    }
+
+    virtual void addRRsig(const rdata::ConstRdataPtr&) {
+        isc_throw(NotImplemented,
+                  "BasicRRset does not implement the addRRsig() method");
+    }
+
+    virtual void addRRsig(const rdata::RdataPtr&) {
+        isc_throw(NotImplemented,
+                  "BasicRRset does not implement the addRRsig() method");
+    }
+
+    virtual void addRRsig(const AbstractRRset&) {
+        isc_throw(NotImplemented,
+                  "BasicRRset does not implement the addRRsig() method");
+    }
+
+    virtual void addRRsig(const ConstRRsetPtr&) {
+        isc_throw(NotImplemented,
+                  "BasicRRset does not implement the addRRsig() method");
+    }
+
+    virtual void addRRsig(const RRsetPtr&) {
+        isc_throw(NotImplemented,
+                  "BasicRRset does not implement the addRRsig() method");
+    }
+
+    virtual void removeRRsig() {
+        isc_throw(NotImplemented,
+                  "BasicRRset does not implement the removeRRsig() method");
+    }
+    //@}
+private:
+    BasicRRsetImpl* impl_;
+};
+
+/// \brief The \c RRset class is a concrete derived class of
+/// \c BasicRRset which contains a pointer to an additional RRset
+/// containing associated RRSIG records.  This allows DNSSEC aware
+/// applications to treat data associated with a particular
+/// QNAME/QTYPE/QCLASS as a single object.
+class RRset : public BasicRRset {
+public:
+    RRset(const Name& name, const RRClass& rrclass,
+          const RRType& rrtype, const RRTTL& ttl);
+
+    virtual ~RRset();
+
+    /// \brief Get the wire format length of the \c RRset.
+    ///
+    /// \return The length of the wire format representation of the
+    /// \c RRset.
+    /// \throw EmptyRRset if the \c RRset is empty.
+    virtual uint16_t getLength() const;
+
+    /// \brief Render the RRset in the wire format with name compression and
+    /// truncation handling.
+    ///
+    /// See \c AbstractRRset::toWire(MessageRenderer&)const.
+    virtual unsigned int toWire(AbstractMessageRenderer& renderer) const;
+
+    /// \brief Render the RRset in the wire format without any compression.
+    ///
+    /// See \c AbstractRRset::toWire(OutputBuffer&)const.
+    virtual unsigned int toWire(isc::util::OutputBuffer& buffer) const;
+
+    /// \brief Updates the owner name of the \c RRset, including RRSIGs if any
+    virtual void setTTL(const RRTTL& ttl) {
+        BasicRRset::setTTL(ttl);
+        if (rrsig_) {
+            rrsig_->setTTL(ttl);
+        }
+    }
+
+    /// \brief Adds an RRSIG RR to this RRset's signatures
+    virtual void addRRsig(const rdata::ConstRdataPtr& rdata) {
+        if (!rrsig_) {
+            rrsig_ = RRsetPtr(new RRset(getName(), getClass(),
+                                        RRType::RRSIG(), getTTL()));
+        }
+        rrsig_->addRdata(rdata);
+    }
+
+    // Workaround for older versions of boost: some don't support implicit
+    // conversion from shared_ptr<X> to shared_ptr<const X>.  Note: we should
+    // revisit the interface of managing RRset signatures, at which point this
+    // problem may go away.
+    virtual void addRRsig(const rdata::RdataPtr& rdata) {
+        // Don't try to convert as a reference here.  SunStudio will reject it.
+        addRRsig(static_cast<const rdata::ConstRdataPtr>(rdata));
+    }
+
+    /// \brief Adds an RRSIG RRset to this RRset
+    virtual void addRRsig(const AbstractRRset& sigs) {
+        RdataIteratorPtr it = sigs.getRdataIterator();
+
+        if (!rrsig_) {
+            rrsig_ = RRsetPtr(new RRset(getName(), getClass(),
+                                        RRType::RRSIG(), getTTL()));
+        }
+
+        for (it->first(); !it->isLast(); it->next()) {
+            rrsig_->addRdata(it->getCurrent());
+        }
+    }
+
+    virtual void addRRsig(const ConstRRsetPtr& sigs) { addRRsig(*sigs); }
+
+    // Another workaround for older boost (see above)
+    virtual void addRRsig(const RRsetPtr& sigs) { addRRsig(*sigs); }
+
+    /// \brief Clear the RRSIGs for this RRset
+    virtual void removeRRsig() { rrsig_ = RRsetPtr(); }
+
+    /// \brief Return a pointer to this RRset's RRSIG RRset
+    virtual RRsetPtr getRRsig() const { return (rrsig_); }
+
+    /// \brief Returns the number of \c RRSIG records associated with
+    /// the \c RRset.
+    ///
+    /// Note that an \c RRset with no RRSIG records may exist, so this
+    /// method may return 0.
+    ///
+    /// \return The number of \c RRSIG records associated.
+    virtual unsigned int getRRsigDataCount() const;
+
+private:
+    RRsetPtr rrsig_;
+};
+
+
+/// \brief Insert the \c RRset as a string into stream.
+///
+/// This method convert the \c rrset into a string and inserts it into the
+/// output stream \c os.
+///
+/// This function overloads the global \c operator<< to behave as described in
+/// \c %ostream::%operator<< but applied to RRset objects.
+///
+/// \param os A \c std::ostream object on which the insertion operation is
+/// performed.
+/// \param rrset A reference to a (derived class of) \c AbstractRRset object
+/// output by the operation.
+/// \return A reference to the same \c std::ostream object referenced by
+/// parameter \c os after the insertion operation.
+std::ostream& operator<<(std::ostream& os, const AbstractRRset& rrset);
+} // end of namespace dns
+} // end of namespace isc
+#endif  // RRSET_H
+
+// Local Variables: 
+// mode: c++
+// End: