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// Copyright (C) 2010 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 __ZONE_ENTRY_H
#define __ZONE_ENTRY_H
#include <string>
#include <vector>
#include <set>
#include <boost/shared_ptr.hpp>
#include <boost/enable_shared_from_this.hpp>
#include <dns/rrset.h>
#include <resolve/resolver_interface.h>
#include <util/locks.h>
#include <util/random/random_number_generator.h>
#include "hash_key.h"
#include "nsas_entry.h"
#include "asiolink.h"
#include "fetchable.h"
#include "nsas_types.h"
#include "glue_hints.h"
namespace isc {
namespace nsas {
class NameserverEntry;
class AddressRequestCallback;
/// \brief Zone Entry
///
/// The zone entry object describes a zone for which nameserver address
/// information is held.
///
/// Although the interface is simple, the internal processing is fairly
/// complicated, in that the class takes account of triggering fetches for
/// addresses of nameservers when the address records expire.
///
/// It uses shared_from_this in its methods. It must live inside a shared_ptr.
class ZoneEntry : public NsasEntry<ZoneEntry>, public Fetchable {
public:
/**
* \brief Constructor.
*
* It asks the resolver any needed questions to get the nameservers.
*
* \param resolver The resolver used to ask for IP addresses
* \param name Name of the zone
* \param class_code Class of this zone (zones of different classes have
* different objects.
* \param nameserver_table Hashtable of NameServerEntry objects for
* this zone
* \param nameserver_lru LRU for the nameserver entries
* \todo Move to cc file, include the lookup (if NSAS uses resolver for
* everything)
*/
ZoneEntry(isc::resolve::ResolverInterface* resolver,
const std::string& name, const isc::dns::RRClass& class_code,
boost::shared_ptr<HashTable<NameserverEntry> > nameserver_table,
boost::shared_ptr<isc::util::LruList<NameserverEntry> > nameserver_lru);
/// \return Name of the zone
std::string getName() const {
return name_;
}
/// \return Class of zone
const isc::dns::RRClass& getClass() const {
return class_code_;
}
/// \return Return Hash Key
virtual HashKey hashKey() const {
return HashKey(name_, class_code_);
}
/**
* \short Put another callback inside.
*
* This callback is either executed right away, if it is possible,
* or queued for later.
*
* \param callback The callback itself.
* \param family Which address family is acceptable as an answer?
* \param glue_hints If a non-empty glue-hints object is passed,
* and the NSAS does not have an immediate answer, it will
* call back immediately with one of the glue hints.
*/
void addCallback(boost::shared_ptr<AddressRequestCallback>
callback, AddressFamily family,
const GlueHints& glue_hints = GlueHints());
/**
* \short Remove a callback from the list
*
* \param callback The callback itself.
* \param family Which address family is acceptable as an answer?
*/
void removeCallback(const boost::shared_ptr<AddressRequestCallback>&
callback, AddressFamily family);
/// \short Protected members, so they can be accessed by tests.
//@{
protected:
// TODO Read-Write lock?
typedef boost::shared_ptr<NameserverEntry> NameserverPtr;
typedef std::vector<NameserverPtr> NameserverVector;
NameserverVector nameservers_; ///< Nameservers
// Which nameservers didn't have any of our callbacks yet
std::set<NameserverPtr> nameservers_not_asked_;
/*
* Callbacks. For each fimily type one vector, so we can process
* them separately.
*/
std::vector<boost::shared_ptr<AddressRequestCallback> >
callbacks_[ADDR_REQ_MAX];
time_t expiry_; ///< Expiry time of this entry, 0 means not set
//}@
private:
mutable isc::util::locks::recursive_mutex mutex_;///< Mutex protecting this zone entry
std::string name_; ///< Canonical zone name
isc::dns::RRClass class_code_; ///< Class code
/**
* \short Process all the callbacks that can be processed
*
* The purpose of this funtion is to ask all nameservers for their IP
* addresses and execute all callbacks that can be executed. It is
* called whenever new callback appears and there's a chance it could
* be answered or when new information is available (list of nameservers,
* nameserver is unreachable or has an address).
* \param family Which is the interesting address family where the change
* happened. ADDR_REQ_MAX means it could be any of them and it will
* trigger processing of all callbacks no matter what their family
* was.
* \param nameserver Pass a nameserver if the change was triggered by
* the nameserver (if it wasn't triggered by a nameserver, pass empty
* pointer). This one will be accepted even with 0 TTL, the information
* just arrived and we are allowed to use it just now.
* \todo With the recursive locks now, we might want to simplify executing
* callbacks (here and other functions as well);
*/
void process(AddressFamily family,
const boost::shared_ptr<NameserverEntry>& nameserver);
// Resolver we use
isc::resolve::ResolverInterface* resolver_;
// We store the nameserver table and lru, so we can look up when there's
// update
boost::shared_ptr<HashTable<NameserverEntry> > nameserver_table_;
boost::shared_ptr<isc::util::LruList<NameserverEntry> > nameserver_lru_;
// Resolver callback class, documentation with the class declaration
class ResolverCallback;
// It has direct access to us
friend class ResolverCallback;
// Guard class to eliminate missing finally
class ProcessGuard;
friend class ProcessGuard;
// Are we in the process method?
bool in_process_[ADDR_REQ_MAX];
// Callback from nameserver entry (documented with the class)
class NameserverCallback;
// And it can get into our internals as well (call process)
friend class NameserverCallback;
// This dispatches callbacks of given family with failures
void dispatchFailures(AddressFamily family);
// Put a callback into the nameserver entry. Same ADDR_REQ_MAX means for
// all families
void insertCallback(NameserverPtr nameserver, AddressFamily family);
// A random generator for this zone entry
// TODO: A more global one? Per thread one?
isc::util::random::WeightedRandomIntegerGenerator address_selector;
};
} // namespace nsas
} // namespace isc
#endif // __ZONE_ENTRY_H
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