src/lsdb.cpp - NLSR - Gitiles

 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
  * Copyright (c) 2014-2021,  The University of Memphis,
  *                           Regents of the University of California,
  *                           Arizona Board of Regents.
  *
  * This file is part of NLSR (Named-data Link State Routing).
  * See AUTHORS.md for complete list of NLSR authors and contributors.
  *
  * NLSR 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.
  *
  * NLSR 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
  * NLSR, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
  */

 #include "lsdb.hpp"

 #include "logger.hpp"
 #include "nlsr.hpp"
 #include "utility/name-helper.hpp"

 namespace nlsr {

 INIT_LOGGER(Lsdb);

 const ndn::time::steady_clock::TimePoint Lsdb::DEFAULT_LSA_RETRIEVAL_DEADLINE =
   ndn::time::steady_clock::TimePoint::min();

 Lsdb::Lsdb(ndn::Face& face, ndn::KeyChain& keyChain, ConfParameter& confParam)
   : m_face(face)
   , m_scheduler(face.getIoService())
   , m_confParam(confParam)
   , m_sync(m_face,
            [this] (const ndn::Name& routerName, const Lsa::Type& lsaType,
                    const uint64_t& sequenceNumber) {
              return isLsaNew(routerName, lsaType, sequenceNumber);
            }, m_confParam)
   , m_lsaRefreshTime(ndn::time::seconds(m_confParam.getLsaRefreshTime()))
   , m_adjLsaBuildInterval(m_confParam.getAdjLsaBuildInterval())
   , m_thisRouterPrefix(m_confParam.getRouterPrefix())
   , m_sequencingManager(m_confParam.getStateFileDir(), m_confParam.getHyperbolicState())
   , m_onNewLsaConnection(m_sync.onNewLsa->connect(
       [this] (const ndn::Name& updateName, uint64_t sequenceNumber,
               const ndn::Name& originRouter) {
         ndn::Name lsaInterest{updateName};
         lsaInterest.appendNumber(sequenceNumber);
         expressInterest(lsaInterest, 0);
       }))
   , m_segmentPublisher(m_face, keyChain)
   , m_isBuildAdjLsaScheduled(false)
   , m_adjBuildCount(0)
 {
   ndn::Name name = m_confParam.getLsaPrefix();
   NLSR_LOG_DEBUG("Setting interest filter for LsaPrefix: " << name);

   m_face.setInterestFilter(ndn::InterestFilter(name).allowLoopback(false),
     [this] (const auto& name, const auto& interest) { processInterest(name, interest); },
     [] (const auto& name) { NLSR_LOG_DEBUG("Successfully registered prefix: " << name); },
     [] (const auto& name, const auto& reason) {
       NLSR_LOG_ERROR("Failed to register prefix " << name);
       NDN_THROW(std::runtime_error("Register prefix failed: " + reason));
     },
     m_confParam.getSigningInfo(), ndn::nfd::ROUTE_FLAG_CAPTURE);

   buildAndInstallOwnNameLsa();
   // Install coordinate LSAs if using HR or dry-run HR.
   if (m_confParam.getHyperbolicState() != HYPERBOLIC_STATE_OFF) {
     buildAndInstallOwnCoordinateLsa();
   }
 }

 void
 Lsdb::buildAndInstallOwnNameLsa()
 {
   NameLsa nameLsa(m_thisRouterPrefix, m_sequencingManager.getNameLsaSeq() + 1,
                   getLsaExpirationTimePoint(), m_confParam.getNamePrefixList());
   m_sequencingManager.increaseNameLsaSeq();
   m_sequencingManager.writeSeqNoToFile();
   m_sync.publishRoutingUpdate(Lsa::Type::NAME, m_sequencingManager.getNameLsaSeq());

   installLsa(std::make_shared<NameLsa>(nameLsa));
 }

 void
 Lsdb::buildAndInstallOwnCoordinateLsa()
 {
   CoordinateLsa corLsa(m_thisRouterPrefix, m_sequencingManager.getCorLsaSeq() + 1,
                        getLsaExpirationTimePoint(), m_confParam.getCorR(),
                        m_confParam.getCorTheta());
   m_sequencingManager.increaseCorLsaSeq();
   m_sequencingManager.writeSeqNoToFile();

   // Sync coordinate LSAs if using HR or HR dry run.
   if (m_confParam.getHyperbolicState() != HYPERBOLIC_STATE_OFF) {
     m_sync.publishRoutingUpdate(Lsa::Type::COORDINATE, m_sequencingManager.getCorLsaSeq());
   }

   installLsa(std::make_shared<CoordinateLsa>(corLsa));
 }

 void
 Lsdb::scheduleAdjLsaBuild()
 {
   m_adjBuildCount++;

   if (m_confParam.getHyperbolicState() == HYPERBOLIC_STATE_ON) {
     // Don't build adjacency LSAs in hyperbolic routing
     NLSR_LOG_DEBUG("Adjacency LSA not built. Currently in hyperbolic routing state.");
     return;
   }

   if (m_isBuildAdjLsaScheduled) {
     NLSR_LOG_DEBUG("Rescheduling Adjacency LSA build in " << m_adjLsaBuildInterval);
   }
   else {
     NLSR_LOG_DEBUG("Scheduling Adjacency LSA build in " << m_adjLsaBuildInterval);
     m_isBuildAdjLsaScheduled = true;
   }
   m_scheduledAdjLsaBuild = m_scheduler.schedule(m_adjLsaBuildInterval, [this] { buildAdjLsa(); });
 }

 void
 Lsdb::writeLog() const
 {
   static const Lsa::Type types[] = {Lsa::Type::COORDINATE, Lsa::Type::NAME, Lsa::Type::ADJACENCY};
   for (const auto& type : types) {
     if ((type == Lsa::Type::COORDINATE &&
          m_confParam.getHyperbolicState() == HYPERBOLIC_STATE_OFF) ||
         (type == Lsa::Type::ADJACENCY &&
        m_confParam.getHyperbolicState() == HYPERBOLIC_STATE_ON)) {
       continue;
     }

     NLSR_LOG_DEBUG("---------------" << type << " LSDB-------------------");
     auto lsaRange = m_lsdb.get<byType>().equal_range(type);
     for (auto lsaIt = lsaRange.first; lsaIt != lsaRange.second; ++lsaIt) {
       NLSR_LOG_DEBUG((*lsaIt)->toString());
     }
   }
 }

 void
 Lsdb::processInterest(const ndn::Name& name, const ndn::Interest& interest)
 {
   ndn::Name interestName(interest.getName());
   NLSR_LOG_DEBUG("Interest received for LSA: " << interestName);

   if (interestName[-2].isVersion()) {
     // Interest for particular segment
     if (m_segmentPublisher.replyFromStore(interestName)) {
       NLSR_LOG_TRACE("Reply from SegmentPublisher storage");
       return;
     }
     // Remove version and segment
     interestName = interestName.getSubName(0, interestName.size() - 2);
     NLSR_LOG_TRACE("Interest w/o segment and version: " << interestName);
   }

   // increment RCV_LSA_INTEREST
   lsaIncrementSignal(Statistics::PacketType::RCV_LSA_INTEREST);

   std::string chkString("LSA");
   int32_t lsaPosition = util::getNameComponentPosition(interestName, chkString);

   // Forms the name of the router that the Interest packet came from.
   ndn::Name originRouter = m_confParam.getNetwork();
   originRouter.append(interestName.getSubName(lsaPosition + 1,
                                               interestName.size() - lsaPosition - 3));

   // if the interest is for this router's LSA
   if (originRouter == m_thisRouterPrefix && lsaPosition >= 0) {
     uint64_t seqNo = interestName[-1].toNumber();
     NLSR_LOG_DEBUG("LSA sequence number from interest: " << seqNo);

     std::string lsaType = interestName[-2].toUri();
     Lsa::Type interestedLsType;
     std::istringstream(lsaType) >> interestedLsType;
     if (interestedLsType == Lsa::Type::BASE) {
       NLSR_LOG_WARN("Received unrecognized LSA type: " << lsaType);
       return;
     }

     incrementInterestRcvdStats(interestedLsType);
     if (processInterestForLsa(interest, originRouter, interestedLsType, seqNo)) {
       lsaIncrementSignal(Statistics::PacketType::SENT_LSA_DATA);
     }
   }
   // else the interest is for other router's LSA, serve signed data from LsaSegmentStorage
   else if (auto lsaSegment = m_lsaStorage.find(interest)) {
     NLSR_LOG_TRACE("Found data in lsa storage. Sending the data for " << interest.getName());
     m_face.put(*lsaSegment);
   }
 }

 bool
 Lsdb::processInterestForLsa(const ndn::Interest& interest, const ndn::Name& originRouter,
                             Lsa::Type lsaType, uint64_t seqNo)
 {
   NLSR_LOG_DEBUG(interest << " received for " << lsaType);
   if (auto lsaPtr = findLsa(originRouter, lsaType)) {
     NLSR_LOG_TRACE("Verifying SeqNo for " << lsaType << " is same as requested.");
     if (lsaPtr->getSeqNo() == seqNo) {
       m_segmentPublisher.publish(interest.getName(), interest.getName(), lsaPtr->wireEncode(),
                                  m_lsaRefreshTime, m_confParam.getSigningInfo());
       incrementDataSentStats(lsaType);
       return true;
     }
   }
   else {
     NLSR_LOG_TRACE(interest << "  was not found in our LSDB");
   }
   return false;
 }

 void
 Lsdb::installLsa(std::shared_ptr<Lsa> lsa)
 {
   auto timeToExpire = m_lsaRefreshTime;
   if (lsa->getOriginRouter() != m_thisRouterPrefix) {
     auto duration = lsa->getExpirationTimePoint() - ndn::time::system_clock::now();
     if (duration > ndn::time::seconds(0)) {
       timeToExpire = ndn::time::duration_cast<ndn::time::seconds>(duration);
     }
   }

   auto chkLsa = findLsa(lsa->getOriginRouter(), lsa->getType());
   if (chkLsa == nullptr) {
     NLSR_LOG_DEBUG("Adding " << lsa->getType() << " LSA");
     NLSR_LOG_DEBUG(lsa->toString());

     m_lsdb.emplace(lsa);

     onLsdbModified(lsa, LsdbUpdate::INSTALLED, {}, {});

     lsa->setExpiringEventId(scheduleLsaExpiration(lsa, timeToExpire));
   }
   // Else this is a known name LSA, so we are updating it.
   else if (chkLsa->getSeqNo() < lsa->getSeqNo()) {
     NLSR_LOG_DEBUG("Updating " << lsa->getType() << " LSA:");
     NLSR_LOG_DEBUG(chkLsa->toString());
     chkLsa->setSeqNo(lsa->getSeqNo());
     chkLsa->setExpirationTimePoint(lsa->getExpirationTimePoint());

     bool updated;
     std::list<ndn::Name> namesToAdd, namesToRemove;
     std::tie(updated, namesToAdd, namesToRemove) = chkLsa->update(lsa);

     if (updated) {
       onLsdbModified(lsa, LsdbUpdate::UPDATED, namesToAdd, namesToRemove);
     }

     chkLsa->setExpiringEventId(scheduleLsaExpiration(chkLsa, timeToExpire));
     NLSR_LOG_DEBUG("Updated " << lsa->getType() << " LSA:");
     NLSR_LOG_DEBUG(chkLsa->toString());
   }
 }

 void
 Lsdb::removeLsa(const LsaContainer::index<Lsdb::byName>::type::iterator& lsaIt)
 {
   if (lsaIt != m_lsdb.end()) {
     auto lsaPtr = *lsaIt;
     NLSR_LOG_DEBUG("Removing " << lsaPtr->getType() << " LSA:");
     NLSR_LOG_DEBUG(lsaPtr->toString());
     m_lsdb.erase(lsaIt);
     onLsdbModified(lsaPtr, LsdbUpdate::REMOVED, {}, {});
   }
 }

 void
 Lsdb::removeLsa(const ndn::Name& router, Lsa::Type lsaType)
 {
   removeLsa(m_lsdb.get<byName>().find(std::make_tuple(router, lsaType)));
 }

 void
 Lsdb::buildAdjLsa()
 {
   NLSR_LOG_TRACE("buildAdjLsa called");

   m_isBuildAdjLsaScheduled = false;

   if (m_confParam.getAdjacencyList().isAdjLsaBuildable(m_confParam.getInterestRetryNumber())) {

     int adjBuildCount = m_adjBuildCount;
     // Only do the adjLsa build if there's one scheduled
     if (adjBuildCount > 0) {
       // It only makes sense to do the adjLsa build if we have neighbors
       if (m_confParam.getAdjacencyList().getNumOfActiveNeighbor() > 0) {
         NLSR_LOG_DEBUG("Building and installing own Adj LSA");
         buildAndInstallOwnAdjLsa();
       }
       // We have no active neighbors, meaning no one can route through
       // us.  So delete our entry in the LSDB. This prevents this
       // router from refreshing the LSA, eventually causing other
       // routers to delete it, too.
       else {
         NLSR_LOG_DEBUG("Removing own Adj LSA; no ACTIVE neighbors");
         removeLsa(m_thisRouterPrefix, Lsa::Type::ADJACENCY);
       }
       // In the case that during building the adj LSA, the FIB has to
       // wait on an Interest response, the number of scheduled adj LSA
       // builds could change, so we shouldn't just set it to 0.
       m_adjBuildCount = m_adjBuildCount - adjBuildCount;
     }
   }
   // We are still waiting to know the adjacency status of some
   // neighbor, so schedule a build for later (when all that has
   // hopefully finished)
   else {
     m_isBuildAdjLsaScheduled = true;
     auto schedulingTime = ndn::time::seconds(m_confParam.getInterestRetryNumber() *
                                              m_confParam.getInterestResendTime());
     m_scheduledAdjLsaBuild = m_scheduler.schedule(schedulingTime, [this] { buildAdjLsa(); });
   }
 }

 void
 Lsdb::buildAndInstallOwnAdjLsa()
 {
   AdjLsa adjLsa(m_thisRouterPrefix, m_sequencingManager.getAdjLsaSeq() + 1,
                 getLsaExpirationTimePoint(),
                 m_confParam.getAdjacencyList().getNumOfActiveNeighbor(),
                 m_confParam.getAdjacencyList());
   m_sequencingManager.increaseAdjLsaSeq();
   m_sequencingManager.writeSeqNoToFile();

   //Sync adjacency LSAs if link-state or dry-run HR is enabled.
   if (m_confParam.getHyperbolicState() != HYPERBOLIC_STATE_ON) {
     m_sync.publishRoutingUpdate(Lsa::Type::ADJACENCY, m_sequencingManager.getAdjLsaSeq());
   }

   installLsa(std::make_shared<AdjLsa>(adjLsa));
 }

 ndn::scheduler::EventId
 Lsdb::scheduleLsaExpiration(std::shared_ptr<Lsa> lsa, ndn::time::seconds expTime)
 {
   NLSR_LOG_DEBUG("Scheduling expiration in: " << expTime + GRACE_PERIOD << " for " << lsa->getOriginRouter());
   return m_scheduler.schedule(expTime + GRACE_PERIOD, [this, lsa] { expireOrRefreshLsa(lsa); });
 }

 void
 Lsdb::expireOrRefreshLsa(std::shared_ptr<Lsa> lsa)
 {
   NLSR_LOG_DEBUG("ExpireOrRefreshLsa called for " << lsa->getType());
   NLSR_LOG_DEBUG("OriginRouter: " << lsa->getOriginRouter() << " Seq No: " << lsa->getSeqNo());

   auto lsaIt = m_lsdb.get<byName>().find(std::make_tuple(lsa->getOriginRouter(), lsa->getType()));

   // If this name LSA exists in the LSDB
   if (lsaIt != m_lsdb.end()) {
     auto lsaPtr = *lsaIt;
     NLSR_LOG_DEBUG(lsaPtr->toString());
     NLSR_LOG_DEBUG("LSA Exists with seq no: " << lsaPtr->getSeqNo());
     // If its seq no is the one we are expecting.
     if (lsaPtr->getSeqNo() == lsa->getSeqNo()) {
       if (lsaPtr->getOriginRouter() == m_thisRouterPrefix) {
         NLSR_LOG_DEBUG("Own " << lsaPtr->getType() << " LSA, so refreshing it.");
         NLSR_LOG_DEBUG("Current LSA:");
         NLSR_LOG_DEBUG(lsaPtr->toString());
         lsaPtr->setSeqNo(lsaPtr->getSeqNo() + 1);
         m_sequencingManager.setLsaSeq(lsaPtr->getSeqNo(), lsaPtr->getType());
         lsaPtr->setExpirationTimePoint(getLsaExpirationTimePoint());
         NLSR_LOG_DEBUG("Updated LSA:");
         NLSR_LOG_DEBUG(lsaPtr->toString());
         // schedule refreshing event again
         lsaPtr->setExpiringEventId(scheduleLsaExpiration(lsaPtr, m_lsaRefreshTime));
         m_sequencingManager.writeSeqNoToFile();
         m_sync.publishRoutingUpdate(lsaPtr->getType(), m_sequencingManager.getLsaSeq(lsaPtr->getType()));
       }
       // Since we cannot refresh other router's LSAs, our only choice is to expire.
       else {
         NLSR_LOG_DEBUG("Other's " << lsaPtr->getType() << " LSA, so removing from LSDB");
         removeLsa(lsaIt);
       }
     }
   }
 }

 void
 Lsdb::expressInterest(const ndn::Name& interestName, uint32_t timeoutCount,
                       ndn::time::steady_clock::TimePoint deadline)
 {
   // increment SENT_LSA_INTEREST
   lsaIncrementSignal(Statistics::PacketType::SENT_LSA_INTEREST);

   if (deadline == DEFAULT_LSA_RETRIEVAL_DEADLINE) {
     deadline = ndn::time::steady_clock::now() + ndn::time::seconds(static_cast<int>(LSA_REFRESH_TIME_MAX));
   }
   // The first component of the interest is the name.
   ndn::Name lsaName = interestName.getSubName(0, interestName.size()-1);
   // The seq no is the last
   uint64_t seqNo = interestName[-1].toNumber();

   // If the LSA is not found in the list currently.
   if (m_highestSeqNo.find(lsaName) == m_highestSeqNo.end()) {
     m_highestSeqNo[lsaName] = seqNo;
   }
   // If the new seq no is higher, that means the LSA is valid
   else if (seqNo > m_highestSeqNo[lsaName]) {
     m_highestSeqNo[lsaName] = seqNo;
   }
   // Otherwise, its an old/invalid LSA
   else if (seqNo < m_highestSeqNo[lsaName]) {
     return;
   }

   ndn::Interest interest(interestName);
   ndn::util::SegmentFetcher::Options options;
   options.interestLifetime = m_confParam.getLsaInterestLifetime();

   NLSR_LOG_DEBUG("Fetching Data for LSA: " << interestName << " Seq number: " << seqNo);
   auto fetcher = ndn::util::SegmentFetcher::start(m_face, interest,
                                                   m_confParam.getValidator(), options);

   auto it = m_fetchers.insert(fetcher).first;

   fetcher->afterSegmentValidated.connect([this] (const ndn::Data& data) {
     // Nlsr class subscribes to this to fetch certificates
     afterSegmentValidatedSignal(data);

     // If we don't do this IMS throws: std::bad_weak_ptr: bad_weak_ptr
     auto lsaSegment = std::make_shared<const ndn::Data>(data);
     m_lsaStorage.insert(*lsaSegment);
     const ndn::Name& segmentName = lsaSegment->getName();
     // Schedule deletion of the segment
     m_scheduler.schedule(ndn::time::seconds(LSA_REFRESH_TIME_DEFAULT),
                          [this, segmentName] { m_lsaStorage.erase(segmentName); });
   });

   fetcher->onComplete.connect([=] (const ndn::ConstBufferPtr& bufferPtr) {
     m_lsaStorage.erase(ndn::Name(lsaName).appendNumber(seqNo - 1));
     afterFetchLsa(bufferPtr, interestName);
     m_fetchers.erase(it);
   });

   fetcher->onError.connect([=] (uint32_t errorCode, const std::string& msg) {
     onFetchLsaError(errorCode, msg, interestName, timeoutCount, deadline, lsaName, seqNo);
     m_fetchers.erase(it);
   });

   Lsa::Type lsaType;
   std::istringstream(interestName[-2].toUri()) >> lsaType;
   incrementInterestSentStats(lsaType);
 }

 void
 Lsdb::onFetchLsaError(uint32_t errorCode, const std::string& msg, const ndn::Name& interestName,
                       uint32_t retransmitNo, const ndn::time::steady_clock::TimePoint& deadline,
                       ndn::Name lsaName, uint64_t seqNo)
 {
   NLSR_LOG_DEBUG("Failed to fetch LSA: " << lsaName << ", Error code: " << errorCode
                  << ", Message: " << msg);

   if (ndn::time::steady_clock::now() < deadline) {
     auto it = m_highestSeqNo.find(lsaName);
     if (it != m_highestSeqNo.end() && it->second == seqNo) {
       // If the SegmentFetcher failed due to an Interest timeout, it is safe to re-express
       // immediately since at the least the LSA Interest lifetime has elapsed.
       // Otherwise, it is necessary to delay the Interest re-expression to prevent
       // the potential for constant Interest flooding.
       ndn::time::seconds delay = m_confParam.getLsaInterestLifetime();

       if (errorCode == ndn::util::SegmentFetcher::ErrorCode::INTEREST_TIMEOUT) {
         delay = ndn::time::seconds(0);
       }
       m_scheduler.schedule(delay, std::bind(&Lsdb::expressInterest, this,
                                             interestName, retransmitNo + 1, deadline));
     }
   }
 }

 void
 Lsdb::afterFetchLsa(const ndn::ConstBufferPtr& bufferPtr, const ndn::Name& interestName)
 {
   NLSR_LOG_DEBUG("Received data for LSA interest: " << interestName);
   lsaIncrementSignal(Statistics::PacketType::RCV_LSA_DATA);

   ndn::Name lsaName = interestName.getSubName(0, interestName.size()-1);
   uint64_t seqNo = interestName[-1].toNumber();

   if (m_highestSeqNo.find(lsaName) == m_highestSeqNo.end()) {
     m_highestSeqNo[lsaName] = seqNo;
   }
   else if (seqNo > m_highestSeqNo[lsaName]) {
     m_highestSeqNo[lsaName] = seqNo;
     NLSR_LOG_TRACE("SeqNo for LSA(name): " << interestName << "  updated");
   }
   else if (seqNo < m_highestSeqNo[lsaName]) {
     return;
   }

   std::string chkString("LSA");
   int32_t lsaPosition = util::getNameComponentPosition(interestName, chkString);

   if (lsaPosition >= 0) {
     // Extracts the prefix of the originating router from the data.
     ndn::Name originRouter = m_confParam.getNetwork();
     originRouter.append(interestName.getSubName(lsaPosition + 1,
                                                 interestName.size() - lsaPosition - 3));
     try {
       Lsa::Type interestedLsType;
       std::istringstream(interestName[-2].toUri()) >> interestedLsType;

       if (interestedLsType == Lsa::Type::BASE) {
         NLSR_LOG_WARN("Received unrecognized LSA Type: " << interestName[-2].toUri());
         return;
       }

       ndn::Block block(bufferPtr);
       if (interestedLsType == Lsa::Type::NAME) {
         lsaIncrementSignal(Statistics::PacketType::RCV_NAME_LSA_DATA);
         if (isLsaNew(originRouter, interestedLsType, seqNo)) {
           installLsa(std::make_shared<NameLsa>(block));
         }
       }
       else if (interestedLsType == Lsa::Type::ADJACENCY) {
         lsaIncrementSignal(Statistics::PacketType::RCV_ADJ_LSA_DATA);
         if (isLsaNew(originRouter, interestedLsType, seqNo)) {
           installLsa(std::make_shared<AdjLsa>(block));
         }
       }
       else if (interestedLsType == Lsa::Type::COORDINATE) {
         lsaIncrementSignal(Statistics::PacketType::RCV_COORD_LSA_DATA);
         if (isLsaNew(originRouter, interestedLsType, seqNo)) {
           installLsa(std::make_shared<CoordinateLsa>(block));
         }
       }
     }
     catch (const std::exception& e) {
       NLSR_LOG_TRACE("LSA data decoding error :( " << e.what());
     }
   }
 }

 } // namespace nlsr
	/* -- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -- */
	/*
	* Copyright (c) 2014-2021, The University of Memphis,
	* Regents of the University of California,
	* Arizona Board of Regents.
	*
	* This file is part of NLSR (Named-data Link State Routing).
	* See AUTHORS.md for complete list of NLSR authors and contributors.
	*
	* NLSR 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.
	*
	* NLSR 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
	* NLSR, e.g., in COPYING.md file. If not, see <http://www.gnu.org/licenses/>.
	*/

	#include "lsdb.hpp"

	#include "logger.hpp"
	#include "nlsr.hpp"
	#include "utility/name-helper.hpp"

	namespace nlsr {

	INIT_LOGGER(Lsdb);

	const ndn::time::steady_clock::TimePoint Lsdb::DEFAULT_LSA_RETRIEVAL_DEADLINE =
	ndn::time::steady_clock::TimePoint::min();

	Lsdb::Lsdb(ndn::Face& face, ndn::KeyChain& keyChain, ConfParameter& confParam)
	: m_face(face)
	, m_scheduler(face.getIoService())
	, m_confParam(confParam)
	, m_sync(m_face,
	[this] (const ndn::Name& routerName, const Lsa::Type& lsaType,
	const uint64_t& sequenceNumber) {
	return isLsaNew(routerName, lsaType, sequenceNumber);
	}, m_confParam)
	, m_lsaRefreshTime(ndn::time::seconds(m_confParam.getLsaRefreshTime()))
	, m_adjLsaBuildInterval(m_confParam.getAdjLsaBuildInterval())
	, m_thisRouterPrefix(m_confParam.getRouterPrefix())
	, m_sequencingManager(m_confParam.getStateFileDir(), m_confParam.getHyperbolicState())
	, m_onNewLsaConnection(m_sync.onNewLsa->connect(
	[this] (const ndn::Name& updateName, uint64_t sequenceNumber,
	const ndn::Name& originRouter) {
	ndn::Name lsaInterest{updateName};
	lsaInterest.appendNumber(sequenceNumber);
	expressInterest(lsaInterest, 0);
	}))
	, m_segmentPublisher(m_face, keyChain)
	, m_isBuildAdjLsaScheduled(false)
	, m_adjBuildCount(0)
	{
	ndn::Name name = m_confParam.getLsaPrefix();
	NLSR_LOG_DEBUG("Setting interest filter for LsaPrefix: " << name);

	m_face.setInterestFilter(ndn::InterestFilter(name).allowLoopback(false),
	[this] (const auto& name, const auto& interest) { processInterest(name, interest); },
	[] (const auto& name) { NLSR_LOG_DEBUG("Successfully registered prefix: " << name); },
	[] (const auto& name, const auto& reason) {
	NLSR_LOG_ERROR("Failed to register prefix " << name);
	NDN_THROW(std::runtime_error("Register prefix failed: " + reason));
	},
	m_confParam.getSigningInfo(), ndn::nfd::ROUTE_FLAG_CAPTURE);

	buildAndInstallOwnNameLsa();
	// Install coordinate LSAs if using HR or dry-run HR.
	if (m_confParam.getHyperbolicState() != HYPERBOLIC_STATE_OFF) {
	buildAndInstallOwnCoordinateLsa();
	}
	}

	void
	Lsdb::buildAndInstallOwnNameLsa()
	{
	NameLsa nameLsa(m_thisRouterPrefix, m_sequencingManager.getNameLsaSeq() + 1,
	getLsaExpirationTimePoint(), m_confParam.getNamePrefixList());
	m_sequencingManager.increaseNameLsaSeq();
	m_sequencingManager.writeSeqNoToFile();
	m_sync.publishRoutingUpdate(Lsa::Type::NAME, m_sequencingManager.getNameLsaSeq());

	installLsa(std::make_shared<NameLsa>(nameLsa));
	}

	void
	Lsdb::buildAndInstallOwnCoordinateLsa()
	{
	CoordinateLsa corLsa(m_thisRouterPrefix, m_sequencingManager.getCorLsaSeq() + 1,
	getLsaExpirationTimePoint(), m_confParam.getCorR(),
	m_confParam.getCorTheta());
	m_sequencingManager.increaseCorLsaSeq();
	m_sequencingManager.writeSeqNoToFile();

	// Sync coordinate LSAs if using HR or HR dry run.
	if (m_confParam.getHyperbolicState() != HYPERBOLIC_STATE_OFF) {
	m_sync.publishRoutingUpdate(Lsa::Type::COORDINATE, m_sequencingManager.getCorLsaSeq());
	}

	installLsa(std::make_shared<CoordinateLsa>(corLsa));
	}

	void
	Lsdb::scheduleAdjLsaBuild()
	{
	m_adjBuildCount++;

	if (m_confParam.getHyperbolicState() == HYPERBOLIC_STATE_ON) {
	// Don't build adjacency LSAs in hyperbolic routing
	NLSR_LOG_DEBUG("Adjacency LSA not built. Currently in hyperbolic routing state.");
	return;
	}

	if (m_isBuildAdjLsaScheduled) {
	NLSR_LOG_DEBUG("Rescheduling Adjacency LSA build in " << m_adjLsaBuildInterval);
	}
	else {
	NLSR_LOG_DEBUG("Scheduling Adjacency LSA build in " << m_adjLsaBuildInterval);
	m_isBuildAdjLsaScheduled = true;
	}
	m_scheduledAdjLsaBuild = m_scheduler.schedule(m_adjLsaBuildInterval, [this] { buildAdjLsa(); });
	}

	void
	Lsdb::writeLog() const
	{
	static const Lsa::Type types[] = {Lsa::Type::COORDINATE, Lsa::Type::NAME, Lsa::Type::ADJACENCY};
	for (const auto& type : types) {
	if ((type == Lsa::Type::COORDINATE &&
	m_confParam.getHyperbolicState() == HYPERBOLIC_STATE_OFF) \|\|
	(type == Lsa::Type::ADJACENCY &&
	m_confParam.getHyperbolicState() == HYPERBOLIC_STATE_ON)) {
	continue;
	}

	NLSR_LOG_DEBUG("---------------" << type << " LSDB-------------------");
	auto lsaRange = m_lsdb.get<byType>().equal_range(type);
	for (auto lsaIt = lsaRange.first; lsaIt != lsaRange.second; ++lsaIt) {
	NLSR_LOG_DEBUG((*lsaIt)->toString());
	}
	}
	}

	void
	Lsdb::processInterest(const ndn::Name& name, const ndn::Interest& interest)
	{
	ndn::Name interestName(interest.getName());
	NLSR_LOG_DEBUG("Interest received for LSA: " << interestName);

	if (interestName[-2].isVersion()) {
	// Interest for particular segment
	if (m_segmentPublisher.replyFromStore(interestName)) {
	NLSR_LOG_TRACE("Reply from SegmentPublisher storage");
	return;
	}
	// Remove version and segment
	interestName = interestName.getSubName(0, interestName.size() - 2);
	NLSR_LOG_TRACE("Interest w/o segment and version: " << interestName);
	}

	// increment RCV_LSA_INTEREST
	lsaIncrementSignal(Statistics::PacketType::RCV_LSA_INTEREST);

	std::string chkString("LSA");
	int32_t lsaPosition = util::getNameComponentPosition(interestName, chkString);

	// Forms the name of the router that the Interest packet came from.
	ndn::Name originRouter = m_confParam.getNetwork();
	originRouter.append(interestName.getSubName(lsaPosition + 1,
	interestName.size() - lsaPosition - 3));

	// if the interest is for this router's LSA
	if (originRouter == m_thisRouterPrefix && lsaPosition >= 0) {
	uint64_t seqNo = interestName[-1].toNumber();
	NLSR_LOG_DEBUG("LSA sequence number from interest: " << seqNo);

	std::string lsaType = interestName[-2].toUri();
	Lsa::Type interestedLsType;
	std::istringstream(lsaType) >> interestedLsType;
	if (interestedLsType == Lsa::Type::BASE) {
	NLSR_LOG_WARN("Received unrecognized LSA type: " << lsaType);
	return;
	}

	incrementInterestRcvdStats(interestedLsType);
	if (processInterestForLsa(interest, originRouter, interestedLsType, seqNo)) {
	lsaIncrementSignal(Statistics::PacketType::SENT_LSA_DATA);
	}
	}
	// else the interest is for other router's LSA, serve signed data from LsaSegmentStorage
	else if (auto lsaSegment = m_lsaStorage.find(interest)) {
	NLSR_LOG_TRACE("Found data in lsa storage. Sending the data for " << interest.getName());
	m_face.put(*lsaSegment);
	}
	}

	bool
	Lsdb::processInterestForLsa(const ndn::Interest& interest, const ndn::Name& originRouter,
	Lsa::Type lsaType, uint64_t seqNo)
	{
	NLSR_LOG_DEBUG(interest << " received for " << lsaType);
	if (auto lsaPtr = findLsa(originRouter, lsaType)) {
	NLSR_LOG_TRACE("Verifying SeqNo for " << lsaType << " is same as requested.");
	if (lsaPtr->getSeqNo() == seqNo) {
	m_segmentPublisher.publish(interest.getName(), interest.getName(), lsaPtr->wireEncode(),
	m_lsaRefreshTime, m_confParam.getSigningInfo());
	incrementDataSentStats(lsaType);
	return true;
	}
	}
	else {
	NLSR_LOG_TRACE(interest << " was not found in our LSDB");
	}
	return false;
	}

	void
	Lsdb::installLsa(std::shared_ptr<Lsa> lsa)
	{
	auto timeToExpire = m_lsaRefreshTime;
	if (lsa->getOriginRouter() != m_thisRouterPrefix) {
	auto duration = lsa->getExpirationTimePoint() - ndn::time::system_clock::now();
	if (duration > ndn::time::seconds(0)) {
	timeToExpire = ndn::time::duration_cast<ndn::time::seconds>(duration);
	}
	}

	auto chkLsa = findLsa(lsa->getOriginRouter(), lsa->getType());
	if (chkLsa == nullptr) {
	NLSR_LOG_DEBUG("Adding " << lsa->getType() << " LSA");
	NLSR_LOG_DEBUG(lsa->toString());

	m_lsdb.emplace(lsa);

	onLsdbModified(lsa, LsdbUpdate::INSTALLED, {}, {});

	lsa->setExpiringEventId(scheduleLsaExpiration(lsa, timeToExpire));
	}
	// Else this is a known name LSA, so we are updating it.
	else if (chkLsa->getSeqNo() < lsa->getSeqNo()) {
	NLSR_LOG_DEBUG("Updating " << lsa->getType() << " LSA:");
	NLSR_LOG_DEBUG(chkLsa->toString());
	chkLsa->setSeqNo(lsa->getSeqNo());
	chkLsa->setExpirationTimePoint(lsa->getExpirationTimePoint());

	bool updated;
	std::list<ndn::Name> namesToAdd, namesToRemove;
	std::tie(updated, namesToAdd, namesToRemove) = chkLsa->update(lsa);

	if (updated) {
	onLsdbModified(lsa, LsdbUpdate::UPDATED, namesToAdd, namesToRemove);
	}

	chkLsa->setExpiringEventId(scheduleLsaExpiration(chkLsa, timeToExpire));
	NLSR_LOG_DEBUG("Updated " << lsa->getType() << " LSA:");
	NLSR_LOG_DEBUG(chkLsa->toString());
	}
	}

	void
	Lsdb::removeLsa(const LsaContainer::index<Lsdb::byName>::type::iterator& lsaIt)
	{
	if (lsaIt != m_lsdb.end()) {
	auto lsaPtr = *lsaIt;
	NLSR_LOG_DEBUG("Removing " << lsaPtr->getType() << " LSA:");
	NLSR_LOG_DEBUG(lsaPtr->toString());
	m_lsdb.erase(lsaIt);
	onLsdbModified(lsaPtr, LsdbUpdate::REMOVED, {}, {});
	}
	}

	void
	Lsdb::removeLsa(const ndn::Name& router, Lsa::Type lsaType)
	{
	removeLsa(m_lsdb.get<byName>().find(std::make_tuple(router, lsaType)));
	}

	void
	Lsdb::buildAdjLsa()
	{
	NLSR_LOG_TRACE("buildAdjLsa called");

	m_isBuildAdjLsaScheduled = false;

	if (m_confParam.getAdjacencyList().isAdjLsaBuildable(m_confParam.getInterestRetryNumber())) {

	int adjBuildCount = m_adjBuildCount;
	// Only do the adjLsa build if there's one scheduled
	if (adjBuildCount > 0) {
	// It only makes sense to do the adjLsa build if we have neighbors
	if (m_confParam.getAdjacencyList().getNumOfActiveNeighbor() > 0) {
	NLSR_LOG_DEBUG("Building and installing own Adj LSA");
	buildAndInstallOwnAdjLsa();
	}
	// We have no active neighbors, meaning no one can route through
	// us. So delete our entry in the LSDB. This prevents this
	// router from refreshing the LSA, eventually causing other
	// routers to delete it, too.
	else {
	NLSR_LOG_DEBUG("Removing own Adj LSA; no ACTIVE neighbors");
	removeLsa(m_thisRouterPrefix, Lsa::Type::ADJACENCY);
	}
	// In the case that during building the adj LSA, the FIB has to
	// wait on an Interest response, the number of scheduled adj LSA
	// builds could change, so we shouldn't just set it to 0.
	m_adjBuildCount = m_adjBuildCount - adjBuildCount;
	}
	}
	// We are still waiting to know the adjacency status of some
	// neighbor, so schedule a build for later (when all that has
	// hopefully finished)
	else {
	m_isBuildAdjLsaScheduled = true;
	auto schedulingTime = ndn::time::seconds(m_confParam.getInterestRetryNumber() *
	m_confParam.getInterestResendTime());
	m_scheduledAdjLsaBuild = m_scheduler.schedule(schedulingTime, [this] { buildAdjLsa(); });
	}
	}

	void
	Lsdb::buildAndInstallOwnAdjLsa()
	{
	AdjLsa adjLsa(m_thisRouterPrefix, m_sequencingManager.getAdjLsaSeq() + 1,
	getLsaExpirationTimePoint(),
	m_confParam.getAdjacencyList().getNumOfActiveNeighbor(),
	m_confParam.getAdjacencyList());
	m_sequencingManager.increaseAdjLsaSeq();
	m_sequencingManager.writeSeqNoToFile();

	//Sync adjacency LSAs if link-state or dry-run HR is enabled.
	if (m_confParam.getHyperbolicState() != HYPERBOLIC_STATE_ON) {
	m_sync.publishRoutingUpdate(Lsa::Type::ADJACENCY, m_sequencingManager.getAdjLsaSeq());
	}

	installLsa(std::make_shared<AdjLsa>(adjLsa));
	}

	ndn::scheduler::EventId
	Lsdb::scheduleLsaExpiration(std::shared_ptr<Lsa> lsa, ndn::time::seconds expTime)
	{
	NLSR_LOG_DEBUG("Scheduling expiration in: " << expTime + GRACE_PERIOD << " for " << lsa->getOriginRouter());
	return m_scheduler.schedule(expTime + GRACE_PERIOD, [this, lsa] { expireOrRefreshLsa(lsa); });
	}

	void
	Lsdb::expireOrRefreshLsa(std::shared_ptr<Lsa> lsa)
	{
	NLSR_LOG_DEBUG("ExpireOrRefreshLsa called for " << lsa->getType());
	NLSR_LOG_DEBUG("OriginRouter: " << lsa->getOriginRouter() << " Seq No: " << lsa->getSeqNo());

	auto lsaIt = m_lsdb.get<byName>().find(std::make_tuple(lsa->getOriginRouter(), lsa->getType()));

	// If this name LSA exists in the LSDB
	if (lsaIt != m_lsdb.end()) {
	auto lsaPtr = *lsaIt;
	NLSR_LOG_DEBUG(lsaPtr->toString());
	NLSR_LOG_DEBUG("LSA Exists with seq no: " << lsaPtr->getSeqNo());
	// If its seq no is the one we are expecting.
	if (lsaPtr->getSeqNo() == lsa->getSeqNo()) {
	if (lsaPtr->getOriginRouter() == m_thisRouterPrefix) {
	NLSR_LOG_DEBUG("Own " << lsaPtr->getType() << " LSA, so refreshing it.");
	NLSR_LOG_DEBUG("Current LSA:");
	NLSR_LOG_DEBUG(lsaPtr->toString());
	lsaPtr->setSeqNo(lsaPtr->getSeqNo() + 1);
	m_sequencingManager.setLsaSeq(lsaPtr->getSeqNo(), lsaPtr->getType());
	lsaPtr->setExpirationTimePoint(getLsaExpirationTimePoint());
	NLSR_LOG_DEBUG("Updated LSA:");
	NLSR_LOG_DEBUG(lsaPtr->toString());
	// schedule refreshing event again
	lsaPtr->setExpiringEventId(scheduleLsaExpiration(lsaPtr, m_lsaRefreshTime));
	m_sequencingManager.writeSeqNoToFile();
	m_sync.publishRoutingUpdate(lsaPtr->getType(), m_sequencingManager.getLsaSeq(lsaPtr->getType()));
	}
	// Since we cannot refresh other router's LSAs, our only choice is to expire.
	else {
	NLSR_LOG_DEBUG("Other's " << lsaPtr->getType() << " LSA, so removing from LSDB");
	removeLsa(lsaIt);
	}
	}
	}
	}

	void
	Lsdb::expressInterest(const ndn::Name& interestName, uint32_t timeoutCount,
	ndn::time::steady_clock::TimePoint deadline)
	{
	// increment SENT_LSA_INTEREST
	lsaIncrementSignal(Statistics::PacketType::SENT_LSA_INTEREST);

	if (deadline == DEFAULT_LSA_RETRIEVAL_DEADLINE) {
	deadline = ndn::time::steady_clock::now() + ndn::time::seconds(static_cast<int>(LSA_REFRESH_TIME_MAX));
	}
	// The first component of the interest is the name.
	ndn::Name lsaName = interestName.getSubName(0, interestName.size()-1);
	// The seq no is the last
	uint64_t seqNo = interestName[-1].toNumber();

	// If the LSA is not found in the list currently.
	if (m_highestSeqNo.find(lsaName) == m_highestSeqNo.end()) {
	m_highestSeqNo[lsaName] = seqNo;
	}
	// If the new seq no is higher, that means the LSA is valid
	else if (seqNo > m_highestSeqNo[lsaName]) {
	m_highestSeqNo[lsaName] = seqNo;
	}
	// Otherwise, its an old/invalid LSA
	else if (seqNo < m_highestSeqNo[lsaName]) {
	return;
	}

	ndn::Interest interest(interestName);
	ndn::util::SegmentFetcher::Options options;
	options.interestLifetime = m_confParam.getLsaInterestLifetime();

	NLSR_LOG_DEBUG("Fetching Data for LSA: " << interestName << " Seq number: " << seqNo);
	auto fetcher = ndn::util::SegmentFetcher::start(m_face, interest,
	m_confParam.getValidator(), options);

	auto it = m_fetchers.insert(fetcher).first;

	fetcher->afterSegmentValidated.connect([this] (const ndn::Data& data) {
	// Nlsr class subscribes to this to fetch certificates
	afterSegmentValidatedSignal(data);

	// If we don't do this IMS throws: std::bad_weak_ptr: bad_weak_ptr
	auto lsaSegment = std::make_shared<const ndn::Data>(data);
	m_lsaStorage.insert(*lsaSegment);
	const ndn::Name& segmentName = lsaSegment->getName();
	// Schedule deletion of the segment
	m_scheduler.schedule(ndn::time::seconds(LSA_REFRESH_TIME_DEFAULT),
	[this, segmentName] { m_lsaStorage.erase(segmentName); });
	});

	fetcher->onComplete.connect([=] (const ndn::ConstBufferPtr& bufferPtr) {
	m_lsaStorage.erase(ndn::Name(lsaName).appendNumber(seqNo - 1));
	afterFetchLsa(bufferPtr, interestName);
	m_fetchers.erase(it);
	});

	fetcher->onError.connect([=] (uint32_t errorCode, const std::string& msg) {
	onFetchLsaError(errorCode, msg, interestName, timeoutCount, deadline, lsaName, seqNo);
	m_fetchers.erase(it);
	});

	Lsa::Type lsaType;
	std::istringstream(interestName[-2].toUri()) >> lsaType;
	incrementInterestSentStats(lsaType);
	}

	void
	Lsdb::onFetchLsaError(uint32_t errorCode, const std::string& msg, const ndn::Name& interestName,
	uint32_t retransmitNo, const ndn::time::steady_clock::TimePoint& deadline,
	ndn::Name lsaName, uint64_t seqNo)
	{
	NLSR_LOG_DEBUG("Failed to fetch LSA: " << lsaName << ", Error code: " << errorCode
	<< ", Message: " << msg);

	if (ndn::time::steady_clock::now() < deadline) {
	auto it = m_highestSeqNo.find(lsaName);
	if (it != m_highestSeqNo.end() && it->second == seqNo) {
	// If the SegmentFetcher failed due to an Interest timeout, it is safe to re-express
	// immediately since at the least the LSA Interest lifetime has elapsed.
	// Otherwise, it is necessary to delay the Interest re-expression to prevent
	// the potential for constant Interest flooding.
	ndn::time::seconds delay = m_confParam.getLsaInterestLifetime();

	if (errorCode == ndn::util::SegmentFetcher::ErrorCode::INTEREST_TIMEOUT) {
	delay = ndn::time::seconds(0);
	}
	m_scheduler.schedule(delay, std::bind(&Lsdb::expressInterest, this,
	interestName, retransmitNo + 1, deadline));
	}
	}
	}

	void
	Lsdb::afterFetchLsa(const ndn::ConstBufferPtr& bufferPtr, const ndn::Name& interestName)
	{
	NLSR_LOG_DEBUG("Received data for LSA interest: " << interestName);
	lsaIncrementSignal(Statistics::PacketType::RCV_LSA_DATA);

	ndn::Name lsaName = interestName.getSubName(0, interestName.size()-1);
	uint64_t seqNo = interestName[-1].toNumber();

	if (m_highestSeqNo.find(lsaName) == m_highestSeqNo.end()) {
	m_highestSeqNo[lsaName] = seqNo;
	}
	else if (seqNo > m_highestSeqNo[lsaName]) {
	m_highestSeqNo[lsaName] = seqNo;
	NLSR_LOG_TRACE("SeqNo for LSA(name): " << interestName << " updated");
	}
	else if (seqNo < m_highestSeqNo[lsaName]) {
	return;
	}

	std::string chkString("LSA");
	int32_t lsaPosition = util::getNameComponentPosition(interestName, chkString);

	if (lsaPosition >= 0) {
	// Extracts the prefix of the originating router from the data.
	ndn::Name originRouter = m_confParam.getNetwork();
	originRouter.append(interestName.getSubName(lsaPosition + 1,
	interestName.size() - lsaPosition - 3));
	try {
	Lsa::Type interestedLsType;
	std::istringstream(interestName[-2].toUri()) >> interestedLsType;

	if (interestedLsType == Lsa::Type::BASE) {
	NLSR_LOG_WARN("Received unrecognized LSA Type: " << interestName[-2].toUri());
	return;
	}

	ndn::Block block(bufferPtr);
	if (interestedLsType == Lsa::Type::NAME) {
	lsaIncrementSignal(Statistics::PacketType::RCV_NAME_LSA_DATA);
	if (isLsaNew(originRouter, interestedLsType, seqNo)) {
	installLsa(std::make_shared<NameLsa>(block));
	}
	}
	else if (interestedLsType == Lsa::Type::ADJACENCY) {
	lsaIncrementSignal(Statistics::PacketType::RCV_ADJ_LSA_DATA);
	if (isLsaNew(originRouter, interestedLsType, seqNo)) {
	installLsa(std::make_shared<AdjLsa>(block));
	}
	}
	else if (interestedLsType == Lsa::Type::COORDINATE) {
	lsaIncrementSignal(Statistics::PacketType::RCV_COORD_LSA_DATA);
	if (isLsaNew(originRouter, interestedLsType, seqNo)) {
	installLsa(std::make_shared<CoordinateLsa>(block));
	}
	}
	}
	catch (const std::exception& e) {
	NLSR_LOG_TRACE("LSA data decoding error :( " << e.what());
	}
	}
	}

	} // namespace nlsr