rib/auto-prefix-propagator.cpp - NFD - Gitiles

 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
  * Copyright (c) 2014-2016,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
  *                           Washington University in St. Louis,
  *                           Beijing Institute of Technology,
  *                           The University of Memphis.
  *
  * This file is part of NFD (Named Data Networking Forwarding Daemon).
  * See AUTHORS.md for complete list of NFD authors and contributors.
  *
  * NFD is free software: you can redistribute it and/or modify it under the terms
  * of the GNU General Public License as published by the Free Software Foundation,
  * either version 3 of the License, or (at your option) any later version.
  *
  * NFD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
  * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
  * PURPOSE.  See the GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License along with
  * NFD, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
  */

 #include "auto-prefix-propagator.hpp"
 #include "core/logger.hpp"
 #include "core/scheduler.hpp"
 #include <ndn-cxx/security/signing-helpers.hpp>
 #include <vector>

 namespace nfd {
 namespace rib {

 NFD_LOG_INIT("AutoPrefixPropagator");

 using ndn::nfd::ControlParameters;
 using ndn::nfd::CommandOptions;

 const Name LOCAL_REGISTRATION_PREFIX("/localhost");
 const Name LINK_LOCAL_NFD_PREFIX("/localhop/nfd");
 const name::Component IGNORE_COMMPONENT("nrd");
 const time::seconds PREFIX_PROPAGATION_DEFAULT_REFRESH_INTERVAL = time::seconds(25);
 const time::seconds PREFIX_PROPAGATION_MAX_REFRESH_INTERVAL = time::seconds(600);
 const time::seconds PREFIX_PROPAGATION_DEFAULT_BASE_RETRY_WAIT = time::seconds(50);
 const time::seconds PREFIX_PROPAGATION_DEFAULT_MAX_RETRY_WAIT = time::seconds(3600);
 const uint64_t PREFIX_PROPAGATION_DEFAULT_COST = 15;
 const time::milliseconds PREFIX_PROPAGATION_DEFAULT_TIMEOUT = time::milliseconds(10000);

 AutoPrefixPropagator::AutoPrefixPropagator(ndn::nfd::Controller& controller,
                                            ndn::KeyChain& keyChain,
                                            Rib& rib)
   : m_nfdController(controller)
   , m_keyChain(keyChain)
   , m_rib(rib)
   , m_refreshInterval(PREFIX_PROPAGATION_DEFAULT_REFRESH_INTERVAL)
   , m_baseRetryWait(PREFIX_PROPAGATION_DEFAULT_BASE_RETRY_WAIT)
   , m_maxRetryWait(PREFIX_PROPAGATION_DEFAULT_MAX_RETRY_WAIT)
   , m_hasConnectedHub(false)
 {
 }

 void
 AutoPrefixPropagator::loadConfig(const ConfigSection& configSection)
 {
   m_refreshInterval = PREFIX_PROPAGATION_DEFAULT_REFRESH_INTERVAL;
   m_baseRetryWait = PREFIX_PROPAGATION_DEFAULT_BASE_RETRY_WAIT;
   m_maxRetryWait = PREFIX_PROPAGATION_DEFAULT_MAX_RETRY_WAIT;

   m_controlParameters
      .setCost(PREFIX_PROPAGATION_DEFAULT_COST)
      .setOrigin(ndn::nfd::ROUTE_ORIGIN_CLIENT)// set origin to client.
      .setFaceId(0);// the remote hub will take the input face as the faceId.

    m_commandOptions
      .setPrefix(LINK_LOCAL_NFD_PREFIX)
      .setTimeout(PREFIX_PROPAGATION_DEFAULT_TIMEOUT);

   NFD_LOG_INFO("Load auto_prefix_propagate section in rib section");

   for (auto&& i : configSection) {
     if (i.first == "cost") {
       m_controlParameters.setCost(i.second.get_value<uint64_t>());
     }
     else if (i.first == "timeout") {
       m_commandOptions.setTimeout(time::milliseconds(i.second.get_value<size_t>()));
     }
     else if (i.first == "refresh_interval") {
       m_refreshInterval = std::min(PREFIX_PROPAGATION_MAX_REFRESH_INTERVAL,
                                    time::seconds(i.second.get_value<size_t>()));
     }
     else if (i.first == "base_retry_wait") {
       m_baseRetryWait = time::seconds(i.second.get_value<size_t>());
     }
     else if (i.first == "max_retry_wait") {
       m_maxRetryWait = time::seconds(i.second.get_value<size_t>());
     }
     else {
       BOOST_THROW_EXCEPTION(ConfigFile::Error("Unrecognized option \"" + i.first +
                                               "\" in \"auto_prefix_propagate\" section"));
     }
   }
 }

 void
 AutoPrefixPropagator::enable()
 {
   m_afterInsertConnection =
     m_rib.afterInsertEntry.connect(bind(&AutoPrefixPropagator::afterInsertRibEntry, this, _1));
   m_afterEraseConnection =
     m_rib.afterEraseEntry.connect(bind(&AutoPrefixPropagator::afterEraseRibEntry, this, _1));
 }

 void
 AutoPrefixPropagator::disable()
 {
   m_afterInsertConnection.disconnect();
   m_afterEraseConnection.disconnect();
 }

 AutoPrefixPropagator::PrefixPropagationParameters
 AutoPrefixPropagator::getPrefixPropagationParameters(const Name& localRibPrefix)
 {
   // get all identities from the KeyChain
   std::vector<Name> identities;
   m_keyChain.getAllIdentities(identities, false); // get all except the default
   identities.push_back(m_keyChain.getDefaultIdentity()); // get the default

   // shortest prefix matching to all identies.
   Name propagatedPrefix, signingIdentity;
   bool isFound = false;
   for (auto&& i : identities) {
     Name prefix = !i.empty() && IGNORE_COMMPONENT == i.at(-1) ? i.getPrefix(-1) : i;
     if (prefix.isPrefixOf(localRibPrefix) && (!isFound || i.size() < signingIdentity.size())) {
       isFound = true;
       propagatedPrefix = prefix;
       signingIdentity = i;
     }
   }

   PrefixPropagationParameters propagateParameters;
   if (!isFound) {
     propagateParameters.isValid = false;
   }
   else {
     propagateParameters.isValid = true;
     propagateParameters.parameters = m_controlParameters;
     propagateParameters.options = m_commandOptions;
     propagateParameters.parameters.setName(propagatedPrefix);
     propagateParameters.options.setSigningInfo(signingByIdentity(signingIdentity));
   }

   return propagateParameters;
 }

 void
 AutoPrefixPropagator::afterInsertRibEntry(const Name& prefix)
 {
   if (LOCAL_REGISTRATION_PREFIX.isPrefixOf(prefix)) {
     NFD_LOG_INFO("local registration only for " << prefix);
     return;
   }

   if (prefix == LINK_LOCAL_NFD_PREFIX) {
     NFD_LOG_INFO("this is a prefix registered by some hub: " << prefix);

     m_hasConnectedHub = true;
     return afterHubConnect();
   }

   auto propagateParameters = getPrefixPropagationParameters(prefix);
   if (!propagateParameters.isValid) {
     NFD_LOG_INFO("no signing identity available for: " << prefix);
     return;
   }

   auto entryIt = m_propagatedEntries.find(propagateParameters.parameters.getName());
   if (entryIt != m_propagatedEntries.end()) {
     // in addition to PROPAGATED and PROPAGATE_FAIL, the state may also be NEW,
     // if its propagation was suspended because there was no connectivity to the Hub.
     NFD_LOG_INFO("prefix has already been propagated: "
                  << propagateParameters.parameters.getName());
     return;
   }

   afterRibInsert(propagateParameters.parameters, propagateParameters.options);
 }

 void
 AutoPrefixPropagator::afterEraseRibEntry(const Name& prefix)
 {
   if (LOCAL_REGISTRATION_PREFIX.isPrefixOf(prefix)) {
     NFD_LOG_INFO("local unregistration only for " << prefix);
     return;
   }

   if (prefix == LINK_LOCAL_NFD_PREFIX) {
     NFD_LOG_INFO("disconnected to hub with prefix: " << prefix);

     m_hasConnectedHub = false;
     return afterHubDisconnect();
   }

   auto propagateParameters = getPrefixPropagationParameters(prefix);
   if (!propagateParameters.isValid) {
     NFD_LOG_INFO("no signing identity available for: " << prefix);
     return;
   }

   auto entryIt = m_propagatedEntries.find(propagateParameters.parameters.getName());
   if (entryIt == m_propagatedEntries.end()) {
     NFD_LOG_INFO("prefix has not been propagated yet: "
                  << propagateParameters.parameters.getName());
     return;
   }

   for (auto&& ribTableEntry : m_rib) {
     if (propagateParameters.parameters.getName().isPrefixOf(ribTableEntry.first) &&
         propagateParameters.options.getSigningInfo().getSignerName() ==
         getPrefixPropagationParameters(ribTableEntry.first)
           .options.getSigningInfo().getSignerName()) {
       NFD_LOG_INFO("should be kept for another RIB entry: " << ribTableEntry.first);
       return;
     }
   }

   afterRibErase(propagateParameters.parameters.unsetCost(), propagateParameters.options);
 }

 bool
 AutoPrefixPropagator::doesCurrentPropagatedPrefixWork(const Name& prefix)
 {
   auto propagateParameters = getPrefixPropagationParameters(prefix);
   if (!propagateParameters.isValid) {
     // no identity can sign the input prefix
     return false;
   }

   // there is at least one identity can sign the input prefix, so the prefix selected for
   // propagation (i.e., propagateParameters.parameters.getName()) must be a prefix of the input
   // prefix. Namely it's either equal to the input prefix or a better choice.
   return propagateParameters.parameters.getName().size() == prefix.size();
 }

 void
 AutoPrefixPropagator::redoPropagation(PropagatedEntryIt entryIt,
                                       const ControlParameters& parameters,
                                       const CommandOptions& options,
                                       time::seconds retryWaitTime)
 {
   if (doesCurrentPropagatedPrefixWork(parameters.getName())) {
     // PROPAGATED / PROPAGATE_FAIL --> PROPAGATING
     entryIt->second.startPropagation();
     return startPropagation(parameters, options, retryWaitTime);
   }

   NFD_LOG_INFO("current propagated prefix does not work any more");
   m_propagatedEntries.erase(entryIt);

   // re-handle all locally RIB entries that can be covered by this propagated prefix
   for (auto&& ribTableEntry : m_rib) {
     if (parameters.getName().isPrefixOf(ribTableEntry.first)) {
       afterInsertRibEntry(ribTableEntry.first);
     }
   }
 }

 void
 AutoPrefixPropagator::startPropagation(const ControlParameters& parameters,
                                        const CommandOptions& options,
                                        time::seconds retryWaitTime)
 {
   NFD_LOG_TRACE("start propagate " << parameters.getName());

   ndn::Scheduler::Event refreshEvent =
     bind(&AutoPrefixPropagator::onRefreshTimer, this, parameters, options);
   ndn::Scheduler::Event retryEvent =
     bind(&AutoPrefixPropagator::onRetryTimer, this, parameters, options,
          std::min(m_maxRetryWait, retryWaitTime * 2));

   m_nfdController.start<ndn::nfd::RibRegisterCommand>(
      parameters,
      bind(&AutoPrefixPropagator::afterPropagateSucceed, this, parameters, options, refreshEvent),
      bind(&AutoPrefixPropagator::afterPropagateFail,
           this, _1, parameters, options, retryWaitTime, retryEvent),
      options);
 }

 void
 AutoPrefixPropagator::startRevocation(const ControlParameters& parameters,
                                       const CommandOptions& options,
                                       time::seconds retryWaitTime)
 {
   NFD_LOG_INFO("start revoke propagation of " << parameters.getName());

   m_nfdController.start<ndn::nfd::RibUnregisterCommand>(
      parameters,
      bind(&AutoPrefixPropagator::afterRevokeSucceed, this, parameters, options, retryWaitTime),
      bind(&AutoPrefixPropagator::afterRevokeFail, this, _1, parameters, options),
      options);
 }

 void
 AutoPrefixPropagator::afterRibInsert(const ControlParameters& parameters,
                                      const CommandOptions& options)
 {
   BOOST_ASSERT(m_propagatedEntries.find(parameters.getName()) == m_propagatedEntries.end());

   // keep valid entries although there is no connectivity to hub
   auto& entry = m_propagatedEntries[parameters.getName()]
     .setSigningIdentity(options.getSigningInfo().getSignerName());

   if (!m_hasConnectedHub) {
     NFD_LOG_INFO("no hub connected to propagate " << parameters.getName());
     return;
   }

   // NEW --> PROPAGATING
   entry.startPropagation();
   startPropagation(parameters, options, m_baseRetryWait);
 }

 void
 AutoPrefixPropagator::afterRibErase(const ControlParameters& parameters,
                                     const CommandOptions& options)
 {
   auto entryIt = m_propagatedEntries.find(parameters.getName());
   BOOST_ASSERT(entryIt != m_propagatedEntries.end());

   bool hasPropagationSucceeded = entryIt->second.isPropagated();

   // --> "RELEASED"
   m_propagatedEntries.erase(entryIt);

   if (!m_hasConnectedHub) {
     NFD_LOG_INFO("no hub connected to revoke propagation of " << parameters.getName());
     return;
   }

   if (!hasPropagationSucceeded) {
     NFD_LOG_INFO("propagation has not succeeded: " << parameters.getName());
     return;
   }

   startRevocation(parameters, options, m_baseRetryWait);
 }

 void
 AutoPrefixPropagator::afterHubConnect()
 {
   NFD_LOG_INFO("redo " << m_propagatedEntries.size()
                        << " propagations when new Hub connectivity is built.");

   std::vector<PropagatedEntryIt> regEntryIterators;
   for (auto it = m_propagatedEntries.begin() ; it != m_propagatedEntries.end() ; it ++) {
     BOOST_ASSERT(it->second.isNew());
     regEntryIterators.push_back(it);
   }

   for (auto&& it : regEntryIterators) {
     auto parameters = m_controlParameters;
     auto options = m_commandOptions;

     redoPropagation(it,
                      parameters.setName(it->first),
                      options.setSigningInfo(signingByIdentity(it->second.getSigningIdentity())),
                      m_baseRetryWait);
   }
 }

 void
 AutoPrefixPropagator::afterHubDisconnect()
 {
   for (auto&& entry : m_propagatedEntries) {
     // --> NEW
     BOOST_ASSERT(!entry.second.isNew());
     entry.second.initialize();
   }
 }

 void
 AutoPrefixPropagator::afterPropagateSucceed(const ControlParameters& parameters,
                                             const CommandOptions& options,
                                             const ndn::Scheduler::Event& refreshEvent)
 {
   NFD_LOG_TRACE("success to propagate " << parameters.getName());

   auto entryIt = m_propagatedEntries.find(parameters.getName());
   if (entryIt == m_propagatedEntries.end()) {
     // propagation should be revoked if this entry has been erased (i.e., be in RELEASED state)
     NFD_LOG_DEBUG("Already erased!");
     ControlParameters newParameters = parameters;
     return startRevocation(newParameters.unsetCost(), options, m_baseRetryWait);
   }

   // PROPAGATING --> PROPAGATED
   BOOST_ASSERT(entryIt->second.isPropagating());
   entryIt->second.succeed(scheduler::schedule(m_refreshInterval, refreshEvent));
 }

 void
 AutoPrefixPropagator::afterPropagateFail(const ndn::nfd::ControlResponse& response,
                                          const ControlParameters& parameters,
                                          const CommandOptions& options,
                                          time::seconds retryWaitTime,
                                          const ndn::Scheduler::Event& retryEvent)
 {
   NFD_LOG_TRACE("fail to propagate " << parameters.getName()
                                      << "\n\t reason:" << response.getText()
                                      << "\n\t retry wait time: " << retryWaitTime);

   auto entryIt = m_propagatedEntries.find(parameters.getName());
   if (entryIt == m_propagatedEntries.end()) {
     // current state is RELEASED
     return;
   }

   // PROPAGATING --> PROPAGATE_FAIL
   BOOST_ASSERT(entryIt->second.isPropagating());
   entryIt->second.fail(scheduler::schedule(retryWaitTime, retryEvent));
 }

 void
 AutoPrefixPropagator::afterRevokeSucceed(const ControlParameters& parameters,
                                          const CommandOptions& options,
                                          time::seconds retryWaitTime)
 {
   NFD_LOG_TRACE("success to revoke propagation of " << parameters.getName());

   auto entryIt = m_propagatedEntries.find(parameters.getName());
   if (m_propagatedEntries.end() != entryIt && !entryIt->second.isPropagateFail()) {
     // if is not RELEASED or PROPAGATE_FAIL
     NFD_LOG_DEBUG("propagated entry still exists");

     // PROPAGATING / PROPAGATED --> PROPAGATING
     BOOST_ASSERT(!entryIt->second.isNew());
     entryIt->second.startPropagation();

     ControlParameters newParameters = parameters;
     startPropagation(newParameters.setCost(m_controlParameters.getCost()), options, retryWaitTime);
   }
 }

 void
 AutoPrefixPropagator::afterRevokeFail(const ndn::nfd::ControlResponse& response,
                                       const ControlParameters& parameters,
                                       const CommandOptions& options)
 {
   NFD_LOG_INFO("fail to revoke the propagation of  " << parameters.getName()
                                                      << "\n\t reason:" << response.getText());
 }

 void
 AutoPrefixPropagator::onRefreshTimer(const ControlParameters& parameters,
                                      const CommandOptions& options)
 {
   auto entryIt = m_propagatedEntries.find(parameters.getName());
   BOOST_ASSERT(entryIt != m_propagatedEntries.end() && entryIt->second.isPropagated());
   redoPropagation(entryIt, parameters, options, m_baseRetryWait);
 }

 void
 AutoPrefixPropagator::onRetryTimer(const ControlParameters& parameters,
                                    const CommandOptions& options,
                                    time::seconds retryWaitTime)
 {
   auto entryIt = m_propagatedEntries.find(parameters.getName());
   BOOST_ASSERT(entryIt != m_propagatedEntries.end() && entryIt->second.isPropagateFail());
   redoPropagation(entryIt, parameters, options, retryWaitTime);
 }

 } // namespace rib
 } // namespace nfd
	/* -- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -- */
	/**
	* Copyright (c) 2014-2016, Regents of the University of California,
	* Arizona Board of Regents,
	* Colorado State University,
	* University Pierre & Marie Curie, Sorbonne University,
	* Washington University in St. Louis,
	* Beijing Institute of Technology,
	* The University of Memphis.
	*
	* This file is part of NFD (Named Data Networking Forwarding Daemon).
	* See AUTHORS.md for complete list of NFD authors and contributors.
	*
	* NFD is free software: you can redistribute it and/or modify it under the terms
	* of the GNU General Public License as published by the Free Software Foundation,
	* either version 3 of the License, or (at your option) any later version.
	*
	* NFD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
	* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
	* PURPOSE. See the GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License along with
	* NFD, e.g., in COPYING.md file. If not, see <http://www.gnu.org/licenses/>.
	*/

	#include "auto-prefix-propagator.hpp"
	#include "core/logger.hpp"
	#include "core/scheduler.hpp"
	#include <ndn-cxx/security/signing-helpers.hpp>
	#include <vector>

	namespace nfd {
	namespace rib {

	NFD_LOG_INIT("AutoPrefixPropagator");

	using ndn::nfd::ControlParameters;
	using ndn::nfd::CommandOptions;

	const Name LOCAL_REGISTRATION_PREFIX("/localhost");
	const Name LINK_LOCAL_NFD_PREFIX("/localhop/nfd");
	const name::Component IGNORE_COMMPONENT("nrd");
	const time::seconds PREFIX_PROPAGATION_DEFAULT_REFRESH_INTERVAL = time::seconds(25);
	const time::seconds PREFIX_PROPAGATION_MAX_REFRESH_INTERVAL = time::seconds(600);
	const time::seconds PREFIX_PROPAGATION_DEFAULT_BASE_RETRY_WAIT = time::seconds(50);
	const time::seconds PREFIX_PROPAGATION_DEFAULT_MAX_RETRY_WAIT = time::seconds(3600);
	const uint64_t PREFIX_PROPAGATION_DEFAULT_COST = 15;
	const time::milliseconds PREFIX_PROPAGATION_DEFAULT_TIMEOUT = time::milliseconds(10000);

	AutoPrefixPropagator::AutoPrefixPropagator(ndn::nfd::Controller& controller,
	ndn::KeyChain& keyChain,
	Rib& rib)
	: m_nfdController(controller)
	, m_keyChain(keyChain)
	, m_rib(rib)
	, m_refreshInterval(PREFIX_PROPAGATION_DEFAULT_REFRESH_INTERVAL)
	, m_baseRetryWait(PREFIX_PROPAGATION_DEFAULT_BASE_RETRY_WAIT)
	, m_maxRetryWait(PREFIX_PROPAGATION_DEFAULT_MAX_RETRY_WAIT)
	, m_hasConnectedHub(false)
	{
	}

	void
	AutoPrefixPropagator::loadConfig(const ConfigSection& configSection)
	{
	m_refreshInterval = PREFIX_PROPAGATION_DEFAULT_REFRESH_INTERVAL;
	m_baseRetryWait = PREFIX_PROPAGATION_DEFAULT_BASE_RETRY_WAIT;
	m_maxRetryWait = PREFIX_PROPAGATION_DEFAULT_MAX_RETRY_WAIT;

	m_controlParameters
	.setCost(PREFIX_PROPAGATION_DEFAULT_COST)
	.setOrigin(ndn::nfd::ROUTE_ORIGIN_CLIENT)// set origin to client.
	.setFaceId(0);// the remote hub will take the input face as the faceId.

	m_commandOptions
	.setPrefix(LINK_LOCAL_NFD_PREFIX)
	.setTimeout(PREFIX_PROPAGATION_DEFAULT_TIMEOUT);

	NFD_LOG_INFO("Load auto_prefix_propagate section in rib section");

	for (auto&& i : configSection) {
	if (i.first == "cost") {
	m_controlParameters.setCost(i.second.get_value<uint64_t>());
	}
	else if (i.first == "timeout") {
	m_commandOptions.setTimeout(time::milliseconds(i.second.get_value<size_t>()));
	}
	else if (i.first == "refresh_interval") {
	m_refreshInterval = std::min(PREFIX_PROPAGATION_MAX_REFRESH_INTERVAL,
	time::seconds(i.second.get_value<size_t>()));
	}
	else if (i.first == "base_retry_wait") {
	m_baseRetryWait = time::seconds(i.second.get_value<size_t>());
	}
	else if (i.first == "max_retry_wait") {
	m_maxRetryWait = time::seconds(i.second.get_value<size_t>());
	}
	else {
	BOOST_THROW_EXCEPTION(ConfigFile::Error("Unrecognized option \"" + i.first +
	"\" in \"auto_prefix_propagate\" section"));
	}
	}
	}

	void
	AutoPrefixPropagator::enable()
	{
	m_afterInsertConnection =
	m_rib.afterInsertEntry.connect(bind(&AutoPrefixPropagator::afterInsertRibEntry, this, _1));
	m_afterEraseConnection =
	m_rib.afterEraseEntry.connect(bind(&AutoPrefixPropagator::afterEraseRibEntry, this, _1));
	}

	void
	AutoPrefixPropagator::disable()
	{
	m_afterInsertConnection.disconnect();
	m_afterEraseConnection.disconnect();
	}

	AutoPrefixPropagator::PrefixPropagationParameters
	AutoPrefixPropagator::getPrefixPropagationParameters(const Name& localRibPrefix)
	{
	// get all identities from the KeyChain
	std::vector<Name> identities;
	m_keyChain.getAllIdentities(identities, false); // get all except the default
	identities.push_back(m_keyChain.getDefaultIdentity()); // get the default

	// shortest prefix matching to all identies.
	Name propagatedPrefix, signingIdentity;
	bool isFound = false;
	for (auto&& i : identities) {
	Name prefix = !i.empty() && IGNORE_COMMPONENT == i.at(-1) ? i.getPrefix(-1) : i;
	if (prefix.isPrefixOf(localRibPrefix) && (!isFound \|\| i.size() < signingIdentity.size())) {
	isFound = true;
	propagatedPrefix = prefix;
	signingIdentity = i;
	}
	}

	PrefixPropagationParameters propagateParameters;
	if (!isFound) {
	propagateParameters.isValid = false;
	}
	else {
	propagateParameters.isValid = true;
	propagateParameters.parameters = m_controlParameters;
	propagateParameters.options = m_commandOptions;
	propagateParameters.parameters.setName(propagatedPrefix);
	propagateParameters.options.setSigningInfo(signingByIdentity(signingIdentity));
	}

	return propagateParameters;
	}

	void
	AutoPrefixPropagator::afterInsertRibEntry(const Name& prefix)
	{
	if (LOCAL_REGISTRATION_PREFIX.isPrefixOf(prefix)) {
	NFD_LOG_INFO("local registration only for " << prefix);
	return;
	}

	if (prefix == LINK_LOCAL_NFD_PREFIX) {
	NFD_LOG_INFO("this is a prefix registered by some hub: " << prefix);

	m_hasConnectedHub = true;
	return afterHubConnect();
	}

	auto propagateParameters = getPrefixPropagationParameters(prefix);
	if (!propagateParameters.isValid) {
	NFD_LOG_INFO("no signing identity available for: " << prefix);
	return;
	}

	auto entryIt = m_propagatedEntries.find(propagateParameters.parameters.getName());
	if (entryIt != m_propagatedEntries.end()) {
	// in addition to PROPAGATED and PROPAGATE_FAIL, the state may also be NEW,
	// if its propagation was suspended because there was no connectivity to the Hub.
	NFD_LOG_INFO("prefix has already been propagated: "
	<< propagateParameters.parameters.getName());
	return;
	}

	afterRibInsert(propagateParameters.parameters, propagateParameters.options);
	}

	void
	AutoPrefixPropagator::afterEraseRibEntry(const Name& prefix)
	{
	if (LOCAL_REGISTRATION_PREFIX.isPrefixOf(prefix)) {
	NFD_LOG_INFO("local unregistration only for " << prefix);
	return;
	}

	if (prefix == LINK_LOCAL_NFD_PREFIX) {
	NFD_LOG_INFO("disconnected to hub with prefix: " << prefix);

	m_hasConnectedHub = false;
	return afterHubDisconnect();
	}

	auto propagateParameters = getPrefixPropagationParameters(prefix);
	if (!propagateParameters.isValid) {
	NFD_LOG_INFO("no signing identity available for: " << prefix);
	return;
	}

	auto entryIt = m_propagatedEntries.find(propagateParameters.parameters.getName());
	if (entryIt == m_propagatedEntries.end()) {
	NFD_LOG_INFO("prefix has not been propagated yet: "
	<< propagateParameters.parameters.getName());
	return;
	}

	for (auto&& ribTableEntry : m_rib) {
	if (propagateParameters.parameters.getName().isPrefixOf(ribTableEntry.first) &&
	propagateParameters.options.getSigningInfo().getSignerName() ==
	getPrefixPropagationParameters(ribTableEntry.first)
	.options.getSigningInfo().getSignerName()) {
	NFD_LOG_INFO("should be kept for another RIB entry: " << ribTableEntry.first);
	return;
	}
	}

	afterRibErase(propagateParameters.parameters.unsetCost(), propagateParameters.options);
	}

	bool
	AutoPrefixPropagator::doesCurrentPropagatedPrefixWork(const Name& prefix)
	{
	auto propagateParameters = getPrefixPropagationParameters(prefix);
	if (!propagateParameters.isValid) {
	// no identity can sign the input prefix
	return false;
	}

	// there is at least one identity can sign the input prefix, so the prefix selected for
	// propagation (i.e., propagateParameters.parameters.getName()) must be a prefix of the input
	// prefix. Namely it's either equal to the input prefix or a better choice.
	return propagateParameters.parameters.getName().size() == prefix.size();
	}

	void
	AutoPrefixPropagator::redoPropagation(PropagatedEntryIt entryIt,
	const ControlParameters& parameters,
	const CommandOptions& options,
	time::seconds retryWaitTime)
	{
	if (doesCurrentPropagatedPrefixWork(parameters.getName())) {
	// PROPAGATED / PROPAGATE_FAIL --> PROPAGATING
	entryIt->second.startPropagation();
	return startPropagation(parameters, options, retryWaitTime);
	}

	NFD_LOG_INFO("current propagated prefix does not work any more");
	m_propagatedEntries.erase(entryIt);

	// re-handle all locally RIB entries that can be covered by this propagated prefix
	for (auto&& ribTableEntry : m_rib) {
	if (parameters.getName().isPrefixOf(ribTableEntry.first)) {
	afterInsertRibEntry(ribTableEntry.first);
	}
	}
	}

	void
	AutoPrefixPropagator::startPropagation(const ControlParameters& parameters,
	const CommandOptions& options,
	time::seconds retryWaitTime)
	{
	NFD_LOG_TRACE("start propagate " << parameters.getName());

	ndn::Scheduler::Event refreshEvent =
	bind(&AutoPrefixPropagator::onRefreshTimer, this, parameters, options);
	ndn::Scheduler::Event retryEvent =
	bind(&AutoPrefixPropagator::onRetryTimer, this, parameters, options,
	std::min(m_maxRetryWait, retryWaitTime * 2));

	m_nfdController.start<ndn::nfd::RibRegisterCommand>(
	parameters,
	bind(&AutoPrefixPropagator::afterPropagateSucceed, this, parameters, options, refreshEvent),
	bind(&AutoPrefixPropagator::afterPropagateFail,
	this, _1, parameters, options, retryWaitTime, retryEvent),
	options);
	}

	void
	AutoPrefixPropagator::startRevocation(const ControlParameters& parameters,
	const CommandOptions& options,
	time::seconds retryWaitTime)
	{
	NFD_LOG_INFO("start revoke propagation of " << parameters.getName());

	m_nfdController.start<ndn::nfd::RibUnregisterCommand>(
	parameters,
	bind(&AutoPrefixPropagator::afterRevokeSucceed, this, parameters, options, retryWaitTime),
	bind(&AutoPrefixPropagator::afterRevokeFail, this, _1, parameters, options),
	options);
	}

	void
	AutoPrefixPropagator::afterRibInsert(const ControlParameters& parameters,
	const CommandOptions& options)
	{
	BOOST_ASSERT(m_propagatedEntries.find(parameters.getName()) == m_propagatedEntries.end());

	// keep valid entries although there is no connectivity to hub
	auto& entry = m_propagatedEntries[parameters.getName()]
	.setSigningIdentity(options.getSigningInfo().getSignerName());

	if (!m_hasConnectedHub) {
	NFD_LOG_INFO("no hub connected to propagate " << parameters.getName());
	return;
	}

	// NEW --> PROPAGATING
	entry.startPropagation();
	startPropagation(parameters, options, m_baseRetryWait);
	}

	void
	AutoPrefixPropagator::afterRibErase(const ControlParameters& parameters,
	const CommandOptions& options)
	{
	auto entryIt = m_propagatedEntries.find(parameters.getName());
	BOOST_ASSERT(entryIt != m_propagatedEntries.end());

	bool hasPropagationSucceeded = entryIt->second.isPropagated();

	// --> "RELEASED"
	m_propagatedEntries.erase(entryIt);

	if (!m_hasConnectedHub) {
	NFD_LOG_INFO("no hub connected to revoke propagation of " << parameters.getName());
	return;
	}

	if (!hasPropagationSucceeded) {
	NFD_LOG_INFO("propagation has not succeeded: " << parameters.getName());
	return;
	}

	startRevocation(parameters, options, m_baseRetryWait);
	}

	void
	AutoPrefixPropagator::afterHubConnect()
	{
	NFD_LOG_INFO("redo " << m_propagatedEntries.size()
	<< " propagations when new Hub connectivity is built.");

	std::vector<PropagatedEntryIt> regEntryIterators;
	for (auto it = m_propagatedEntries.begin() ; it != m_propagatedEntries.end() ; it ++) {
	BOOST_ASSERT(it->second.isNew());
	regEntryIterators.push_back(it);
	}

	for (auto&& it : regEntryIterators) {
	auto parameters = m_controlParameters;
	auto options = m_commandOptions;

	redoPropagation(it,
	parameters.setName(it->first),
	options.setSigningInfo(signingByIdentity(it->second.getSigningIdentity())),
	m_baseRetryWait);
	}
	}

	void
	AutoPrefixPropagator::afterHubDisconnect()
	{
	for (auto&& entry : m_propagatedEntries) {
	// --> NEW
	BOOST_ASSERT(!entry.second.isNew());
	entry.second.initialize();
	}
	}

	void
	AutoPrefixPropagator::afterPropagateSucceed(const ControlParameters& parameters,
	const CommandOptions& options,
	const ndn::Scheduler::Event& refreshEvent)
	{
	NFD_LOG_TRACE("success to propagate " << parameters.getName());

	auto entryIt = m_propagatedEntries.find(parameters.getName());
	if (entryIt == m_propagatedEntries.end()) {
	// propagation should be revoked if this entry has been erased (i.e., be in RELEASED state)
	NFD_LOG_DEBUG("Already erased!");
	ControlParameters newParameters = parameters;
	return startRevocation(newParameters.unsetCost(), options, m_baseRetryWait);
	}

	// PROPAGATING --> PROPAGATED
	BOOST_ASSERT(entryIt->second.isPropagating());
	entryIt->second.succeed(scheduler::schedule(m_refreshInterval, refreshEvent));
	}

	void
	AutoPrefixPropagator::afterPropagateFail(const ndn::nfd::ControlResponse& response,
	const ControlParameters& parameters,
	const CommandOptions& options,
	time::seconds retryWaitTime,
	const ndn::Scheduler::Event& retryEvent)
	{
	NFD_LOG_TRACE("fail to propagate " << parameters.getName()
	<< "\n\t reason:" << response.getText()
	<< "\n\t retry wait time: " << retryWaitTime);

	auto entryIt = m_propagatedEntries.find(parameters.getName());
	if (entryIt == m_propagatedEntries.end()) {
	// current state is RELEASED
	return;
	}

	// PROPAGATING --> PROPAGATE_FAIL
	BOOST_ASSERT(entryIt->second.isPropagating());
	entryIt->second.fail(scheduler::schedule(retryWaitTime, retryEvent));
	}

	void
	AutoPrefixPropagator::afterRevokeSucceed(const ControlParameters& parameters,
	const CommandOptions& options,
	time::seconds retryWaitTime)
	{
	NFD_LOG_TRACE("success to revoke propagation of " << parameters.getName());

	auto entryIt = m_propagatedEntries.find(parameters.getName());
	if (m_propagatedEntries.end() != entryIt && !entryIt->second.isPropagateFail()) {
	// if is not RELEASED or PROPAGATE_FAIL
	NFD_LOG_DEBUG("propagated entry still exists");

	// PROPAGATING / PROPAGATED --> PROPAGATING
	BOOST_ASSERT(!entryIt->second.isNew());
	entryIt->second.startPropagation();

	ControlParameters newParameters = parameters;
	startPropagation(newParameters.setCost(m_controlParameters.getCost()), options, retryWaitTime);
	}
	}

	void
	AutoPrefixPropagator::afterRevokeFail(const ndn::nfd::ControlResponse& response,
	const ControlParameters& parameters,
	const CommandOptions& options)
	{
	NFD_LOG_INFO("fail to revoke the propagation of " << parameters.getName()
	<< "\n\t reason:" << response.getText());
	}

	void
	AutoPrefixPropagator::onRefreshTimer(const ControlParameters& parameters,
	const CommandOptions& options)
	{
	auto entryIt = m_propagatedEntries.find(parameters.getName());
	BOOST_ASSERT(entryIt != m_propagatedEntries.end() && entryIt->second.isPropagated());
	redoPropagation(entryIt, parameters, options, m_baseRetryWait);
	}

	void
	AutoPrefixPropagator::onRetryTimer(const ControlParameters& parameters,
	const CommandOptions& options,
	time::seconds retryWaitTime)
	{
	auto entryIt = m_propagatedEntries.find(parameters.getName());
	BOOST_ASSERT(entryIt != m_propagatedEntries.end() && entryIt->second.isPropagateFail());
	redoPropagation(entryIt, parameters, options, retryWaitTime);
	}

	} // namespace rib
	} // namespace nfd