kea/src/lib/datasrc/rbnode_rrset.h

// Copyright (C) 2012  Internet Systems Consortium, Inc. ("ISC")
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
// OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
// PERFORMANCE OF THIS SOFTWARE.

#ifndef __RBNODE_RRSET_H
#define __RBNODE_RRSET_H

#include <dns/messagerenderer.h>
#include <dns/name.h>
#include <dns/rrclass.h>
#include <dns/rrset.h>
#include <dns/rrttl.h>
#include <dns/rrtype.h>
#include <util/buffer.h>

#include <string>

namespace isc {
namespace datasrc {
namespace internal {

/// \brief Special RRset for optimizing memory datasource requirement
///
/// To speed up the performance of the in-memory data source, at load time
/// associate relevant "additional section" data with each RRset in the
/// data source.
///
/// This class, derived from AbstractRRset, holds a "const" pointer to the
/// underlying RRset object.  All calls to methods on the class are passed to
/// the underlying object.  However, there are some restrictions:
///
/// - Calls to methods that change attributes of the underlying RRset (such as
///   TTL or Name) cause an exception to be thrown.  The in-memory data source
///   does not allow modification of these attributes.
/// - Calls that add the pointer to the associated RRSIG to the RRset are
///   allowed (even though the pointer is to a "const" RRset).  The reason here
///   is that RRSIGs are added to the in-memory data source after the
///   RBNodeRRset objects have been created.  Thus there has to be the
///   capability of modifying this information.
///
/// The class is not derived from RRset itself to simplify coding: part of the
/// loading of the memory data source is handled in the BIND 10 "libdns++"
/// code, which creates RRsets and passes them to the data source code.  This
/// does not have to be altered if encapsulation, rather than inheritcance, is
/// used.

// Note: non-Doxygen-documented methods are documented in the base class.

class RBNodeRRset : public isc::dns::AbstractRRset {

private:
    // Note: The copy constructor and the assignment operator are intentionally
    // defined as private as we would normally not duplicate a RBNodeRRset.
    // (We use the "private" method instead of inheriting from
    // boost::noncopyable so as to avoid multiple inheritance.)
    RBNodeRRset(const RBNodeRRset& source);
    RBNodeRRset& operator=(const RBNodeRRset& source);

public:
    /// \brief Usual Constructor
    ///
    /// Creates an RBNodeRRset from the pointer to the RRset passed to it.
    ///
    /// \param rrset Pointer to underlying RRset encapsulated by this object.
    explicit RBNodeRRset(const isc::dns::ConstRRsetPtr& rrset) : rrset_(rrset)
    {}

    /// \brief Destructor
    virtual ~RBNodeRRset() {}

    // Getter and Setter Methods
    //
    // The getter methods pass the call through to the underlying RRset.  The
    // setter methods thrown an exception - this specialisation of the RRset
    // object does not expect the underlying RRset to be modified.

    virtual unsigned int getRdataCount() const {
        return (rrset_->getRdataCount());
    }

    virtual const isc::dns::Name& getName() const {
        return (rrset_->getName());
    }

    virtual const isc::dns::RRClass& getClass() const {
        return (rrset_->getClass());
    }

    virtual const isc::dns::RRType& getType() const {
        return (rrset_->getType());
    }

    virtual const isc::dns::RRTTL& getTTL() const {
        return (rrset_->getTTL());
    }

    virtual void setName(const isc::dns::Name&) {
        isc_throw(isc::NotImplemented, "RBNodeRRset::setName() not supported");
    }

    virtual void setTTL(const isc::dns::RRTTL&) {
        isc_throw(isc::NotImplemented, "RBNodeRRset::setTTL() not supported");
    }

    virtual std::string toText() const {
        return (rrset_->toText());
    }

    virtual unsigned int toWire(
            isc::dns::AbstractMessageRenderer& renderer) const {
        return (rrset_->toWire(renderer));
    }

    virtual unsigned int toWire(isc::util::OutputBuffer& buffer) const {
        return (rrset_->toWire(buffer));
    }

    virtual void addRdata(isc::dns::rdata::ConstRdataPtr) {
        isc_throw(isc::NotImplemented,
                  "RBNodeRRset::addRdata() not supported");
    }

    virtual void addRdata(const isc::dns::rdata::Rdata&) {
        isc_throw(isc::NotImplemented,
                  "RBNodeRRset::addRdata() not supported");
    }

    virtual isc::dns::RdataIteratorPtr getRdataIterator() const {
        return (rrset_->getRdataIterator());
    }

    virtual isc::dns::RRsetPtr getRRsig() const {
        return (rrset_->getRRsig());
    }

    // With all the RRsig methods, we have the problem that we store the
    // underlying RRset using a ConstRRsetPtr - a pointer to a "const" RRset -
    // but we need to modify it by adding or removing an RRSIG.  We overcome
    // this by temporarily violating the "const" nature of the RRset to add the
    // data.

    virtual void addRRsig(const isc::dns::rdata::ConstRdataPtr& rdata) {
        AbstractRRset* p = const_cast<AbstractRRset*>(rrset_.get());
        p->addRRsig(rdata);
    }

    virtual void addRRsig(const isc::dns::rdata::RdataPtr& rdata) {
        AbstractRRset* p = const_cast<AbstractRRset*>(rrset_.get());
        p->addRRsig(rdata);
    }

    virtual void addRRsig(const AbstractRRset& sigs) {
        AbstractRRset* p = const_cast<AbstractRRset*>(rrset_.get());
        p->addRRsig(sigs);
    }

    virtual void addRRsig(const isc::dns::ConstRRsetPtr& sigs) {
        AbstractRRset* p = const_cast<AbstractRRset*>(rrset_.get());
        p->addRRsig(sigs);
    }

    virtual void addRRsig(const isc::dns::RRsetPtr& sigs) {
        AbstractRRset* p = const_cast<AbstractRRset*>(rrset_.get());
        p->addRRsig(sigs);
    }

    virtual void removeRRsig() {
        AbstractRRset* p = const_cast<AbstractRRset*>(rrset_.get());
        p->removeRRsig();
    }

    /// \brief Return underlying RRset pointer
    ///
    /// ... mainly for testing.
    isc::dns::ConstRRsetPtr getUnderlyingRRset() const {
        return (rrset_);
    }

private:
    isc::dns::ConstRRsetPtr rrset_;     ///< Underlying RRset
};

}   // namespace internal
}   // namespace datasrc
}   // namespace isc

#endif  // __RBNODE_RRSET_H