diff --git a/src/BtExtendedMessage.cc b/src/BtExtendedMessage.cc
index 901d72f3e..6ecf47900 100644
--- a/src/BtExtendedMessage.cc
+++ b/src/BtExtendedMessage.cc
@@ -51,14 +51,12 @@ namespace aria2 {
 const char BtExtendedMessage::NAME[] = "extended";
 
 BtExtendedMessage::BtExtendedMessage
-(const std::shared_ptr<ExtensionMessage>& extensionMessage):
+(std::unique_ptr<ExtensionMessage> extensionMessage):
   SimpleBtMessage(ID, NAME),
-  extensionMessage_(extensionMessage),
+  extensionMessage_(std::move(extensionMessage)),
   msgLength_(0)
 {}
 
-BtExtendedMessage::~BtExtendedMessage() {}
-
 unsigned char* BtExtendedMessage::createMessage()
 {
   /**
@@ -97,16 +95,15 @@ std::string BtExtendedMessage::toString() const {
 }
 
 std::unique_ptr<BtExtendedMessage>
-BtExtendedMessage::create(const std::shared_ptr<ExtensionMessageFactory>& factory,
+BtExtendedMessage::create(ExtensionMessageFactory* factory,
                           const std::shared_ptr<Peer>& peer,
                           const unsigned char* data, size_t dataLength)
 {
   bittorrent::assertPayloadLengthGreater(1, dataLength, NAME);
   bittorrent::assertID(ID, data, NAME);
   assert(factory);
-  std::shared_ptr<ExtensionMessage> extmsg = factory->createMessage(data+1,
-                                                                 dataLength-1);
-  return make_unique<BtExtendedMessage>(extmsg);
+  return make_unique<BtExtendedMessage>
+    (factory->createMessage(data+1, dataLength-1));
 }
 
 void BtExtendedMessage::doReceivedAction()
@@ -116,4 +113,10 @@ void BtExtendedMessage::doReceivedAction()
   }
 }
 
+const std::unique_ptr<ExtensionMessage>&
+BtExtendedMessage::getExtensionMessage() const
+{
+  return extensionMessage_;
+}
+
 } // namespace aria2
diff --git a/src/BtExtendedMessage.h b/src/BtExtendedMessage.h
index 584287e93..1238c96a4 100644
--- a/src/BtExtendedMessage.h
+++ b/src/BtExtendedMessage.h
@@ -44,20 +44,19 @@ class ExtensionMessageFactory;
 class BtExtendedMessage:public SimpleBtMessage
 {
 private:
-  std::shared_ptr<ExtensionMessage> extensionMessage_;
+  std::unique_ptr<ExtensionMessage> extensionMessage_;
 
   size_t msgLength_;
 public:
-  BtExtendedMessage(const std::shared_ptr<ExtensionMessage>& extensionMessage =
-                    std::shared_ptr<ExtensionMessage>());
-  virtual ~BtExtendedMessage();
+  BtExtendedMessage(std::unique_ptr<ExtensionMessage> extensionMessage =
+                    std::unique_ptr<ExtensionMessage>{});
 
   static const uint8_t ID = 20;
 
   static const char NAME[];
 
   static std::unique_ptr<BtExtendedMessage> create
-  (const std::shared_ptr<ExtensionMessageFactory>& factory,
+  (ExtensionMessageFactory* factory,
    const std::shared_ptr<Peer>& peer,
    const unsigned char* data,
    size_t dataLength);
@@ -72,11 +71,7 @@ public:
 
   virtual std::string toString() const;
 
-  const std::shared_ptr<ExtensionMessage>& getExtensionMessage() const
-  {
-    return extensionMessage_;
-  }
-
+  const std::unique_ptr<ExtensionMessage>& getExtensionMessage() const;
 };
 
 } // namespace aria2
diff --git a/src/BtMessageFactory.h b/src/BtMessageFactory.h
index a664828a0..fb9e41fd5 100644
--- a/src/BtMessageFactory.h
+++ b/src/BtMessageFactory.h
@@ -114,7 +114,7 @@ public:
   virtual std::unique_ptr<BtPortMessage> createPortMessage(uint16_t port) = 0;
 
   virtual std::unique_ptr<BtExtendedMessage>
-  createBtExtendedMessage(const std::shared_ptr<ExtensionMessage>& msg) = 0;
+  createBtExtendedMessage(std::unique_ptr<ExtensionMessage> msg) = 0;
 };
 
 } // namespace aria2
diff --git a/src/DefaultBtInteractive.cc b/src/DefaultBtInteractive.cc
index 16c9149ed..59a2d8bf1 100644
--- a/src/DefaultBtInteractive.cc
+++ b/src/DefaultBtInteractive.cc
@@ -199,7 +199,7 @@ void DefaultBtInteractive::addPortMessageToQueue()
 
 void DefaultBtInteractive::addHandshakeExtendedMessageToQueue()
 {
-  std::shared_ptr<HandshakeExtensionMessage> m(new HandshakeExtensionMessage());
+  auto m = make_unique<HandshakeExtensionMessage>();
   m->setClientVersion("aria2/" PACKAGE_VERSION);
   m->setTCPPort(tcpPort_);
   m->setExtensions(extensionMessageRegistry_->getExtensions());
@@ -207,7 +207,8 @@ void DefaultBtInteractive::addHandshakeExtendedMessageToQueue()
   if(!attrs->metadata.empty()) {
     m->setMetadataSize(attrs->metadataSize);
   }
-  dispatcher_->addMessageToQueue(messageFactory_->createBtExtendedMessage(m));
+  dispatcher_->addMessageToQueue
+    (messageFactory_->createBtExtendedMessage(std::move(m)));
 }
 
 void DefaultBtInteractive::addBitfieldMessageToQueue() {
@@ -479,32 +480,26 @@ void DefaultBtInteractive::checkActiveInteraction()
 
 void DefaultBtInteractive::addPeerExchangeMessage()
 {
-  if(pexTimer_.
-     difference(global::wallclock()) >= UTPexExtensionMessage::DEFAULT_INTERVAL) {
-    std::shared_ptr<UTPexExtensionMessage> m
-      (new UTPexExtensionMessage(peer_->getExtensionMessageID
-                                 (ExtensionMessageRegistry::UT_PEX)));
-
-    const PeerSet& usedPeers = peerStorage_->getUsedPeers();
-    for(PeerSet::const_iterator i = usedPeers.begin(), eoi = usedPeers.end();
+  if(pexTimer_.difference(global::wallclock()) >=
+     UTPexExtensionMessage::DEFAULT_INTERVAL) {
+    auto m = make_unique<UTPexExtensionMessage>
+      (peer_->getExtensionMessageID(ExtensionMessageRegistry::UT_PEX));
+    auto& usedPeers = peerStorage_->getUsedPeers();
+    for(auto i = std::begin(usedPeers), eoi = std::end(usedPeers);
         i != eoi && !m->freshPeersAreFull(); ++i) {
       if((*i)->isActive() && peer_->getIPAddress() != (*i)->getIPAddress()) {
         m->addFreshPeer(*i);
       }
     }
-    const std::deque<std::shared_ptr<Peer> >& droppedPeers =
-      peerStorage_->getDroppedPeers();
-    for(std::deque<std::shared_ptr<Peer> >::const_iterator i =
-          droppedPeers.begin(), eoi = droppedPeers.end();
-        i != eoi && !m->droppedPeersAreFull();
-        ++i) {
+    auto& droppedPeers = peerStorage_->getDroppedPeers();
+    for(auto i = std::begin(droppedPeers), eoi = std::end(droppedPeers);
+        i != eoi && !m->droppedPeersAreFull(); ++i) {
       if(peer_->getIPAddress() != (*i)->getIPAddress()) {
         m->addDroppedPeer(*i);
       }
     }
-
     dispatcher_->addMessageToQueue
-      (messageFactory_->createBtExtendedMessage(m));
+      (messageFactory_->createBtExtendedMessage(std::move(m)));
     pexTimer_ = global::wallclock();
   }
 }
@@ -522,7 +517,7 @@ void DefaultBtInteractive::doInteractionProcessing() {
       size_t num = utMetadataRequestTracker_->avail();
       if(num > 0) {
         auto requests =
-          utMetadataRequestFactory_->create(num, pieceStorage_);
+          utMetadataRequestFactory_->create(num, pieceStorage_.get());
         for(auto& i : requests) {
           dispatcher_->addMessageToQueue(std::move(i));
         }
@@ -531,11 +526,9 @@ void DefaultBtInteractive::doInteractionProcessing() {
         perSecTimer_ = global::wallclock();
         // Drop timeout request after queuing message to give a chance
         // to other connection to request piece.
-        std::vector<size_t> indexes =
-          utMetadataRequestTracker_->removeTimeoutEntry();
-        for(std::vector<size_t>::const_iterator i = indexes.begin(),
-              eoi = indexes.end(); i != eoi; ++i) {
-          pieceStorage_->cancelPiece(pieceStorage_->getPiece(*i), cuid_);
+        auto indexes = utMetadataRequestTracker_->removeTimeoutEntry();
+        for(auto idx : indexes) {
+          pieceStorage_->cancelPiece(pieceStorage_->getPiece(idx), cuid_);
         }
       }
       if(pieceStorage_->downloadFinished()) {
@@ -645,9 +638,9 @@ void DefaultBtInteractive::setPeerConnection
 }
 
 void DefaultBtInteractive::setExtensionMessageFactory
-(const std::shared_ptr<ExtensionMessageFactory>& factory)
+(std::unique_ptr<ExtensionMessageFactory> factory)
 {
-  extensionMessageFactory_ = factory;
+  extensionMessageFactory_ = std::move(factory);
 }
 
 void DefaultBtInteractive::setBtMessageFactory
diff --git a/src/DefaultBtInteractive.h b/src/DefaultBtInteractive.h
index b26d5e81e..51a23acc3 100644
--- a/src/DefaultBtInteractive.h
+++ b/src/DefaultBtInteractive.h
@@ -117,7 +117,7 @@ private:
   // holds the reference so that peerConnection_ is not deleted.
   std::shared_ptr<PeerConnection> peerConnection_;
   std::shared_ptr<BtMessageFactory> messageFactory_;
-  std::shared_ptr<ExtensionMessageFactory> extensionMessageFactory_;
+  std::unique_ptr<ExtensionMessageFactory> extensionMessageFactory_;
   std::shared_ptr<ExtensionMessageRegistry> extensionMessageRegistry_;
   std::shared_ptr<UTMetadataRequestFactory> utMetadataRequestFactory_;
   std::shared_ptr<UTMetadataRequestTracker> utMetadataRequestTracker_;
@@ -219,7 +219,7 @@ public:
   void setBtMessageFactory(const std::shared_ptr<BtMessageFactory>& factory);
 
   void setExtensionMessageFactory
-  (const std::shared_ptr<ExtensionMessageFactory>& factory);
+  (std::unique_ptr<ExtensionMessageFactory> factory);
 
   void setExtensionMessageRegistry
   (const std::shared_ptr<ExtensionMessageRegistry>& registry)
diff --git a/src/DefaultBtMessageFactory.cc b/src/DefaultBtMessageFactory.cc
index 978b5c8df..297bf82b5 100644
--- a/src/DefaultBtMessageFactory.cc
+++ b/src/DefaultBtMessageFactory.cc
@@ -79,6 +79,7 @@ DefaultBtMessageFactory::DefaultBtMessageFactory()
     dispatcher_{nullptr},
     requestFactory_{nullptr},
     peerConnection_{nullptr},
+    extensionMessageFactory_{nullptr},
     localNode_{nullptr},
     routingTable_{nullptr},
     taskQueue_{nullptr},
@@ -402,9 +403,9 @@ DefaultBtMessageFactory::createPortMessage(uint16_t port)
 
 std::unique_ptr<BtExtendedMessage>
 DefaultBtMessageFactory::createBtExtendedMessage
-(const std::shared_ptr<ExtensionMessage>& exmsg)
+(std::unique_ptr<ExtensionMessage> exmsg)
 {
-  auto msg = make_unique<BtExtendedMessage>(exmsg);
+  auto msg = make_unique<BtExtendedMessage>(std::move(exmsg));
   setCommonProperty(msg.get());
   return msg;
 }
@@ -447,7 +448,7 @@ void DefaultBtMessageFactory::setBtMessageDispatcher
 }
 
 void DefaultBtMessageFactory::setExtensionMessageFactory
-(const std::shared_ptr<ExtensionMessageFactory>& factory)
+(ExtensionMessageFactory* factory)
 {
   extensionMessageFactory_ = factory;
 }
diff --git a/src/DefaultBtMessageFactory.h b/src/DefaultBtMessageFactory.h
index 28299efb2..761ad4a0d 100644
--- a/src/DefaultBtMessageFactory.h
+++ b/src/DefaultBtMessageFactory.h
@@ -70,7 +70,7 @@ private:
 
   PeerConnection* peerConnection_;
 
-  std::shared_ptr<ExtensionMessageFactory> extensionMessageFactory_;
+  ExtensionMessageFactory* extensionMessageFactory_;
 
   DHTNode* localNode_;
 
@@ -133,7 +133,7 @@ public:
   virtual std::unique_ptr<BtPortMessage> createPortMessage(uint16_t port);
 
   virtual std::unique_ptr<BtExtendedMessage>
-  createBtExtendedMessage(const std::shared_ptr<ExtensionMessage>& msg);
+  createBtExtendedMessage(std::unique_ptr<ExtensionMessage> msg);
 
   void setPeer(const std::shared_ptr<Peer>& peer);
 
@@ -159,8 +159,7 @@ public:
 
   void setPeerConnection(PeerConnection* connection);
 
-  void setExtensionMessageFactory
-  (const std::shared_ptr<ExtensionMessageFactory>& factory);
+  void setExtensionMessageFactory(ExtensionMessageFactory* factory);
 
   void setLocalNode(DHTNode* localNode);
 
diff --git a/src/DefaultExtensionMessageFactory.cc b/src/DefaultExtensionMessageFactory.cc
index 202b1ca48..98b400070 100644
--- a/src/DefaultExtensionMessageFactory.cc
+++ b/src/DefaultExtensionMessageFactory.cc
@@ -58,34 +58,31 @@
 namespace aria2 {
 
 DefaultExtensionMessageFactory::DefaultExtensionMessageFactory()
-  : messageFactory_(0),
-    dispatcher_(0),
-    tracker_(0)
+  : DefaultExtensionMessageFactory{std::shared_ptr<Peer>{}, nullptr}
 {}
 
 DefaultExtensionMessageFactory::DefaultExtensionMessageFactory
-(const std::shared_ptr<Peer>& peer,
- const std::shared_ptr<ExtensionMessageRegistry>& registry)
-  : peer_(peer),
-    registry_(registry),
-    messageFactory_(0),
-    dispatcher_(0),
-    tracker_(0)
+(const std::shared_ptr<Peer>& peer, ExtensionMessageRegistry* registry)
+  : peerStorage_{nullptr},
+    peer_{peer},
+    registry_{registry},
+    dctx_{nullptr},
+    messageFactory_{nullptr},
+    dispatcher_{nullptr},
+    tracker_{nullptr}
 {}
 
-DefaultExtensionMessageFactory::~DefaultExtensionMessageFactory() {}
-
-std::shared_ptr<ExtensionMessage>
-DefaultExtensionMessageFactory::createMessage(const unsigned char* data, size_t length)
+std::unique_ptr<ExtensionMessage>
+DefaultExtensionMessageFactory::createMessage
+(const unsigned char* data, size_t length)
 {
   uint8_t extensionMessageID = *data;
   if(extensionMessageID == 0) {
     // handshake
-    HandshakeExtensionMessage* m =
-      HandshakeExtensionMessage::create(data, length);
+    auto m = HandshakeExtensionMessage::create(data, length);
     m->setPeer(peer_);
     m->setDownloadContext(dctx_);
-    return std::shared_ptr<ExtensionMessage>(m);
+    return std::move(m);
   } else {
     const char* extensionName = registry_->getExtensionName(extensionMessageID);
     if(!extensionName) {
@@ -95,9 +92,9 @@ DefaultExtensionMessageFactory::createMessage(const unsigned char* data, size_t
     }
     if(strcmp(extensionName, "ut_pex") == 0) {
       // uTorrent compatible Peer-Exchange
-      UTPexExtensionMessage* m = UTPexExtensionMessage::create(data, length);
+      auto m = UTPexExtensionMessage::create(data, length);
       m->setPeerStorage(peerStorage_);
-      return std::shared_ptr<ExtensionMessage>(m);
+      return std::move(m);
     } else if(strcmp(extensionName, "ut_metadata") == 0) {
       if(length == 0) {
         throw DL_ABORT_EX
@@ -106,8 +103,7 @@ DefaultExtensionMessageFactory::createMessage(const unsigned char* data, size_t
                static_cast<unsigned long>(length)));
       }
       size_t end;
-      std::shared_ptr<ValueBase> decoded =
-        bencode2::decode(data+1, length - 1, end);
+      auto decoded = bencode2::decode(data+1, length - 1, end);
       const Dict* dict = downcast<Dict>(decoded);
       if(!dict) {
         throw DL_ABORT_EX("Bad ut_metadata: dictionary not found");
@@ -122,14 +118,14 @@ DefaultExtensionMessageFactory::createMessage(const unsigned char* data, size_t
       }
       switch(msgType->i()) {
       case 0: {
-        UTMetadataRequestExtensionMessage* m
-          (new UTMetadataRequestExtensionMessage(extensionMessageID));
+        auto m = make_unique<UTMetadataRequestExtensionMessage>
+          (extensionMessageID);
         m->setIndex(index->i());
         m->setDownloadContext(dctx_);
         m->setPeer(peer_);
         m->setBtMessageFactory(messageFactory_);
         m->setBtMessageDispatcher(dispatcher_);
-        return std::shared_ptr<ExtensionMessage>(m);
+        return std::move(m);
       }
       case 1: {
         if(end == length) {
@@ -139,22 +135,23 @@ DefaultExtensionMessageFactory::createMessage(const unsigned char* data, size_t
         if(!totalSize) {
           throw DL_ABORT_EX("Bad ut_metadata data: total_size not found");
         }
-        UTMetadataDataExtensionMessage* m
-          (new UTMetadataDataExtensionMessage(extensionMessageID));
+        auto m = make_unique<UTMetadataDataExtensionMessage>
+          (extensionMessageID);
         m->setIndex(index->i());
         m->setTotalSize(totalSize->i());
         m->setData(&data[1+end], &data[length]);
         m->setUTMetadataRequestTracker(tracker_);
-        m->setPieceStorage(dctx_->getOwnerRequestGroup()->getPieceStorage());
+        m->setPieceStorage
+          (dctx_->getOwnerRequestGroup()->getPieceStorage().get());
         m->setDownloadContext(dctx_);
-        return std::shared_ptr<ExtensionMessage>(m);
+        return std::move(m);
       }
       case 2: {
-        UTMetadataRejectExtensionMessage* m
-          (new UTMetadataRejectExtensionMessage(extensionMessageID));
+        auto m = make_unique<UTMetadataRejectExtensionMessage>
+          (extensionMessageID);
         m->setIndex(index->i());
         // No need to inject tracker because peer will be disconnected.
-        return std::shared_ptr<ExtensionMessage>(m);
+        return std::move(m);
       }
       default:
         throw DL_ABORT_EX
@@ -170,8 +167,7 @@ DefaultExtensionMessageFactory::createMessage(const unsigned char* data, size_t
   }
 }
 
-void DefaultExtensionMessageFactory::setPeerStorage
-(const std::shared_ptr<PeerStorage>& peerStorage)
+void DefaultExtensionMessageFactory::setPeerStorage(PeerStorage* peerStorage)
 {
   peerStorage_ = peerStorage;
 }
@@ -181,4 +177,33 @@ void DefaultExtensionMessageFactory::setPeer(const std::shared_ptr<Peer>& peer)
   peer_ = peer;
 }
 
+void DefaultExtensionMessageFactory::setExtensionMessageRegistry
+(ExtensionMessageRegistry* registry)
+{
+  registry_ = registry;
+}
+
+void DefaultExtensionMessageFactory::setDownloadContext(DownloadContext* dctx)
+{
+  dctx_ = dctx;
+}
+
+void DefaultExtensionMessageFactory::setBtMessageFactory
+(BtMessageFactory* factory)
+{
+  messageFactory_ = factory;
+}
+
+void DefaultExtensionMessageFactory::setBtMessageDispatcher
+(BtMessageDispatcher* disp)
+{
+  dispatcher_ = disp;
+}
+
+void DefaultExtensionMessageFactory::setUTMetadataRequestTracker
+(UTMetadataRequestTracker* tracker)
+{
+  tracker_ = tracker;
+}
+
 } // namespace aria2
diff --git a/src/DefaultExtensionMessageFactory.h b/src/DefaultExtensionMessageFactory.h
index ab56d33dc..7be897e23 100644
--- a/src/DefaultExtensionMessageFactory.h
+++ b/src/DefaultExtensionMessageFactory.h
@@ -49,13 +49,13 @@ class UTMetadataRequestTracker;
 
 class DefaultExtensionMessageFactory:public ExtensionMessageFactory {
 private:
-  std::shared_ptr<PeerStorage> peerStorage_;
+  PeerStorage* peerStorage_;
 
   std::shared_ptr<Peer> peer_;
 
-  std::shared_ptr<ExtensionMessageRegistry> registry_;
+  ExtensionMessageRegistry* registry_;
 
-  std::shared_ptr<DownloadContext> dctx_;
+  DownloadContext* dctx_;
 
   BtMessageFactory* messageFactory_;
 
@@ -66,43 +66,24 @@ public:
   DefaultExtensionMessageFactory();
 
   DefaultExtensionMessageFactory
-  (const std::shared_ptr<Peer>& peer,
-   const std::shared_ptr<ExtensionMessageRegistry>& registry);
+  (const std::shared_ptr<Peer>& peer, ExtensionMessageRegistry* registry);
 
-  virtual ~DefaultExtensionMessageFactory();
-
-  virtual std::shared_ptr<ExtensionMessage>
+  virtual std::unique_ptr<ExtensionMessage>
   createMessage(const unsigned char* data, size_t length);
 
-  void setPeerStorage(const std::shared_ptr<PeerStorage>& peerStorage);
+  void setPeerStorage(PeerStorage* peerStorage);
 
   void setPeer(const std::shared_ptr<Peer>& peer);
 
-  void setExtensionMessageRegistry
-  (const std::shared_ptr<ExtensionMessageRegistry>& registry)
-  {
-    registry_ = registry;
-  }
+  void setExtensionMessageRegistry(ExtensionMessageRegistry* registry);
 
-  void setDownloadContext(const std::shared_ptr<DownloadContext>& dctx)
-  {
-    dctx_ = dctx;
-  }
+  void setDownloadContext(DownloadContext* dctx);
 
-  void setBtMessageFactory(BtMessageFactory* factory)
-  {
-    messageFactory_ = factory;
-  }
+  void setBtMessageFactory(BtMessageFactory* factory);
 
-  void setBtMessageDispatcher(BtMessageDispatcher* disp)
-  {
-    dispatcher_ = disp;
-  }
+  void setBtMessageDispatcher(BtMessageDispatcher* disp);
 
-  void setUTMetadataRequestTracker(UTMetadataRequestTracker* tracker)
-  {
-    tracker_ = tracker;
-  }
+  void setUTMetadataRequestTracker(UTMetadataRequestTracker* tracker);
 };
 
 } // namespace aria2
diff --git a/src/ExtensionMessageFactory.h b/src/ExtensionMessageFactory.h
index 6cde20419..557ef4bd1 100644
--- a/src/ExtensionMessageFactory.h
+++ b/src/ExtensionMessageFactory.h
@@ -47,7 +47,7 @@ class ExtensionMessageFactory {
 public:
   virtual ~ExtensionMessageFactory() {}
 
-  virtual std::shared_ptr<ExtensionMessage>
+  virtual std::unique_ptr<ExtensionMessage>
   createMessage(const unsigned char* data, size_t length) = 0;
 };
 
diff --git a/src/HandshakeExtensionMessage.cc b/src/HandshakeExtensionMessage.cc
index f37526f11..b31ef4187 100644
--- a/src/HandshakeExtensionMessage.cc
+++ b/src/HandshakeExtensionMessage.cc
@@ -52,12 +52,9 @@ namespace aria2 {
 const char HandshakeExtensionMessage::EXTENSION_NAME[] = "handshake";
 
 HandshakeExtensionMessage::HandshakeExtensionMessage()
-  : tcpPort_(0),
-    metadataSize_(0)
+  : tcpPort_{0}, metadataSize_{0}, dctx_{nullptr}
 {}
 
-HandshakeExtensionMessage::~HandshakeExtensionMessage() {}
-
 std::string HandshakeExtensionMessage::getPayload()
 {
   Dict dict;
@@ -127,12 +124,9 @@ void HandshakeExtensionMessage::doReceivedAction()
         dctx_->getFirstFileEntry()->setLength(metadataSize_);
         dctx_->markTotalLengthIsKnown();
         dctx_->getOwnerRequestGroup()->initPieceStorage();
-
-        std::shared_ptr<PieceStorage> pieceStorage =
-          dctx_->getOwnerRequestGroup()->getPieceStorage();
         // We enter 'end game' mode from the start to get metadata
         // quickly.
-        pieceStorage->enterEndGame();
+        dctx_->getOwnerRequestGroup()->getPieceStorage()->enterEndGame();
       }
       peer_->reconfigureSessionResource(dctx_->getPieceLength(),
                                         dctx_->getTotalLength());
@@ -164,7 +158,7 @@ uint8_t HandshakeExtensionMessage::getExtensionMessageID(int key) const
   return extreg_.getExtensionMessageID(key);
 }
 
-HandshakeExtensionMessage*
+std::unique_ptr<HandshakeExtensionMessage>
 HandshakeExtensionMessage::create(const unsigned char* data, size_t length)
 {
   if(length < 1) {
@@ -174,13 +168,13 @@ HandshakeExtensionMessage::create(const unsigned char* data, size_t length)
   }
   A2_LOG_DEBUG(fmt("Creating HandshakeExtensionMessage from %s",
                    util::percentEncode(data, length).c_str()));
-  std::shared_ptr<ValueBase> decoded = bencode2::decode(data+1, length - 1);
+  auto decoded = bencode2::decode(data+1, length - 1);
   const Dict* dict = downcast<Dict>(decoded);
   if(!dict) {
     throw DL_ABORT_EX
       ("Unexpected payload format for extended message handshake");
   }
-  HandshakeExtensionMessage* msg(new HandshakeExtensionMessage());
+  auto msg = make_unique<HandshakeExtensionMessage>();
   const Integer* port = downcast<Integer>(dict->get("p"));
   if(port && 0 < port->i() && port->i() < 65536) {
     msg->tcpPort_ = port->i();
diff --git a/src/HandshakeExtensionMessage.h b/src/HandshakeExtensionMessage.h
index 7690a485b..33821dcf1 100644
--- a/src/HandshakeExtensionMessage.h
+++ b/src/HandshakeExtensionMessage.h
@@ -57,14 +57,12 @@ private:
 
   ExtensionMessageRegistry extreg_;
 
-  std::shared_ptr<DownloadContext> dctx_;
+  DownloadContext* dctx_;
 
   std::shared_ptr<Peer> peer_;
 public:
   HandshakeExtensionMessage();
 
-  virtual ~HandshakeExtensionMessage();
-
   virtual std::string getPayload();
 
   virtual uint8_t getExtensionMessageID() const
@@ -113,7 +111,7 @@ public:
     metadataSize_ = size;
   }
 
-  void setDownloadContext(const std::shared_ptr<DownloadContext>& dctx)
+  void setDownloadContext(DownloadContext* dctx)
   {
     dctx_ = dctx;
   }
@@ -126,7 +124,7 @@ public:
 
   void setPeer(const std::shared_ptr<Peer>& peer);
 
-  static HandshakeExtensionMessage*
+  static std::unique_ptr<HandshakeExtensionMessage>
   create(const unsigned char* data, size_t dataLength);
 };
 
diff --git a/src/PeerInteractionCommand.cc b/src/PeerInteractionCommand.cc
index f49404354..bddd81d52 100644
--- a/src/PeerInteractionCommand.cc
+++ b/src/PeerInteractionCommand.cc
@@ -132,25 +132,22 @@ PeerInteractionCommand::PeerInteractionCommand
     utMetadataRequestTracker.reset(new UTMetadataRequestTracker());
   }
 
-  DefaultExtensionMessageFactory* extensionMessageFactoryPtr
-    (new DefaultExtensionMessageFactory(getPeer(), exMsgRegistry));
-  extensionMessageFactoryPtr->setPeerStorage(peerStorage);
-  extensionMessageFactoryPtr->setDownloadContext
-    (requestGroup_->getDownloadContext());
-  extensionMessageFactoryPtr->setUTMetadataRequestTracker
+  auto extensionMessageFactory =
+    make_unique<DefaultExtensionMessageFactory>(getPeer(),
+                                                exMsgRegistry.get());
+  extensionMessageFactory->setPeerStorage(peerStorage.get());
+  extensionMessageFactory->setDownloadContext
+    (requestGroup_->getDownloadContext().get());
+  extensionMessageFactory->setUTMetadataRequestTracker
     (utMetadataRequestTracker.get());
   // PieceStorage will be set later.
-  std::shared_ptr<ExtensionMessageFactory> extensionMessageFactory
-    (extensionMessageFactoryPtr);
-
-
 
   DefaultBtMessageFactory* factoryPtr(new DefaultBtMessageFactory());
   factoryPtr->setCuid(cuid);
   factoryPtr->setDownloadContext(requestGroup_->getDownloadContext().get());
   factoryPtr->setPieceStorage(pieceStorage.get());
   factoryPtr->setPeerStorage(peerStorage.get());
-  factoryPtr->setExtensionMessageFactory(extensionMessageFactory);
+  factoryPtr->setExtensionMessageFactory(extensionMessageFactory.get());
   factoryPtr->setPeer(getPeer());
   if(family == AF_INET) {
     factoryPtr->setLocalNode(DHTRegistry::getData().localNode.get());
@@ -218,6 +215,30 @@ PeerInteractionCommand::PeerInteractionCommand
   reqFactoryPtr->setCuid(cuid);
   std::shared_ptr<BtRequestFactory> reqFactory(reqFactoryPtr);
 
+  // reverse depends
+  factoryPtr->setBtMessageDispatcher(dispatcherPtr);
+  factoryPtr->setBtRequestFactory(reqFactoryPtr);
+  factoryPtr->setPeerConnection(peerConnection.get());
+
+  extensionMessageFactory->setBtMessageDispatcher(dispatcherPtr);
+  extensionMessageFactory->setBtMessageFactory(factoryPtr);
+
+  if(metadataGetMode) {
+    utMetadataRequestFactory->setCuid(cuid);
+    utMetadataRequestFactory->setDownloadContext
+      (requestGroup_->getDownloadContext().get());
+    utMetadataRequestFactory->setBtMessageDispatcher(dispatcherPtr);
+    utMetadataRequestFactory->setBtMessageFactory(factoryPtr);
+    utMetadataRequestFactory->setPeer(getPeer());
+    utMetadataRequestFactory->setUTMetadataRequestTracker
+      (utMetadataRequestTracker.get());
+  }
+
+  getPeer()->allocateSessionResource
+    (requestGroup_->getDownloadContext()->getPieceLength(),
+     requestGroup_->getDownloadContext()->getTotalLength());
+  getPeer()->setBtMessageDispatcher(dispatcherPtr);
+
   DefaultBtInteractive* btInteractivePtr
     (new DefaultBtInteractive(requestGroup_->getDownloadContext(), getPeer()));
   btInteractivePtr->setBtRuntime(btRuntime_);
@@ -228,7 +249,8 @@ PeerInteractionCommand::PeerInteractionCommand
   btInteractivePtr->setDispatcher(dispatcher);
   btInteractivePtr->setBtRequestFactory(reqFactory);
   btInteractivePtr->setPeerConnection(peerConnection);
-  btInteractivePtr->setExtensionMessageFactory(extensionMessageFactory);
+  btInteractivePtr->setExtensionMessageFactory
+    (std::move(extensionMessageFactory));
   btInteractivePtr->setExtensionMessageRegistry(exMsgRegistry);
   btInteractivePtr->setKeepAliveInterval
     (getOption()->getAsInt(PREF_BT_KEEP_ALIVE_INTERVAL));
@@ -264,29 +286,6 @@ PeerInteractionCommand::PeerInteractionCommand
 
   btInteractive_ = btInteractive;
 
-  // reverse depends
-  factoryPtr->setBtMessageDispatcher(dispatcherPtr);
-  factoryPtr->setBtRequestFactory(reqFactoryPtr);
-  factoryPtr->setPeerConnection(peerConnection.get());
-
-  extensionMessageFactoryPtr->setBtMessageDispatcher(dispatcherPtr);
-  extensionMessageFactoryPtr->setBtMessageFactory(factoryPtr);
-
-  if(metadataGetMode) {
-    utMetadataRequestFactory->setCuid(cuid);
-    utMetadataRequestFactory->setDownloadContext
-      (requestGroup_->getDownloadContext());
-    utMetadataRequestFactory->setBtMessageDispatcher(dispatcherPtr);
-    utMetadataRequestFactory->setBtMessageFactory(factoryPtr);
-    utMetadataRequestFactory->setPeer(getPeer());
-    utMetadataRequestFactory->setUTMetadataRequestTracker
-      (utMetadataRequestTracker.get());
-  }
-
-  getPeer()->allocateSessionResource
-    (requestGroup_->getDownloadContext()->getPieceLength(),
-     requestGroup_->getDownloadContext()->getTotalLength());
-  getPeer()->setBtMessageDispatcher(dispatcherPtr);
 
   btRuntime_->increaseConnections();
   requestGroup_->increaseNumCommand();
diff --git a/src/UTMetadataDataExtensionMessage.cc b/src/UTMetadataDataExtensionMessage.cc
index 88d78d716..208749c06 100644
--- a/src/UTMetadataDataExtensionMessage.cc
+++ b/src/UTMetadataDataExtensionMessage.cc
@@ -54,13 +54,13 @@ namespace aria2 {
 
 UTMetadataDataExtensionMessage::UTMetadataDataExtensionMessage
 (uint8_t extensionMessageID)
-  : UTMetadataExtensionMessage(extensionMessageID),
-    totalSize_(0),
-    tracker_(0)
+  : UTMetadataExtensionMessage{extensionMessageID},
+    totalSize_{0},
+    dctx_{nullptr},
+    pieceStorage_{nullptr},
+    tracker_{nullptr}
 {}
 
-UTMetadataDataExtensionMessage::~UTMetadataDataExtensionMessage() {}
-
 std::string UTMetadataDataExtensionMessage::getPayload()
 {
   Dict dict;
@@ -109,19 +109,39 @@ void UTMetadataDataExtensionMessage::doReceivedAction()
   }
 }
 
+void UTMetadataDataExtensionMessage::setTotalSize(size_t totalSize)
+{
+  totalSize_ = totalSize;
+}
+
+size_t UTMetadataDataExtensionMessage::getTotalSize() const
+{
+  return totalSize_;
+}
+
 void UTMetadataDataExtensionMessage::setData(const std::string& data)
 {
   data_ = data;
 }
 
+const std::string& UTMetadataDataExtensionMessage::getData() const
+{
+  return data_;
+}
+
 void UTMetadataDataExtensionMessage::setPieceStorage
-(const std::shared_ptr<PieceStorage>& pieceStorage)
+(PieceStorage* pieceStorage)
 {
   pieceStorage_ = pieceStorage;
 }
 
-void UTMetadataDataExtensionMessage::setDownloadContext
-(const std::shared_ptr<DownloadContext>& dctx)
+void UTMetadataDataExtensionMessage::setUTMetadataRequestTracker
+(UTMetadataRequestTracker* tracker)
+{
+  tracker_ = tracker;
+}
+
+void UTMetadataDataExtensionMessage::setDownloadContext(DownloadContext* dctx)
 {
   dctx_ = dctx;
 }
diff --git a/src/UTMetadataDataExtensionMessage.h b/src/UTMetadataDataExtensionMessage.h
index ca8ff59e9..873d3f901 100644
--- a/src/UTMetadataDataExtensionMessage.h
+++ b/src/UTMetadataDataExtensionMessage.h
@@ -51,31 +51,23 @@ private:
 
   std::string data_;
 
-  std::shared_ptr<DownloadContext> dctx_;
+  DownloadContext* dctx_;
 
-  std::shared_ptr<PieceStorage> pieceStorage_;
+  PieceStorage* pieceStorage_;
 
   UTMetadataRequestTracker* tracker_;
 public:
   UTMetadataDataExtensionMessage(uint8_t extensionMessageID);
 
-  ~UTMetadataDataExtensionMessage();
-
   virtual std::string getPayload();
 
   virtual std::string toString() const;
 
   virtual void doReceivedAction();
 
-  void setTotalSize(size_t totalSize)
-  {
-    totalSize_ = totalSize;
-  }
+  void setTotalSize(size_t totalSize);
 
-  size_t getTotalSize() const
-  {
-    return totalSize_;
-  }
+  size_t getTotalSize() const;
 
   void setData(const std::string& data);
 
@@ -85,19 +77,13 @@ public:
     data_.assign(first, last);
   }
 
-  const std::string& getData() const
-  {
-    return data_;
-  }
+  const std::string& getData() const;
 
-  void setPieceStorage(const std::shared_ptr<PieceStorage>& pieceStorage);
+  void setPieceStorage(PieceStorage* pieceStorage);
 
-  void setUTMetadataRequestTracker(UTMetadataRequestTracker* tracker)
-  {
-    tracker_ = tracker;
-  }
+  void setUTMetadataRequestTracker(UTMetadataRequestTracker* tracker);
 
-  void setDownloadContext(const std::shared_ptr<DownloadContext>& dctx);
+  void setDownloadContext(DownloadContext* dctx);
 };
 
 } // namespace aria2
diff --git a/src/UTMetadataRejectExtensionMessage.cc b/src/UTMetadataRejectExtensionMessage.cc
index 887b44af2..b23ae57a4 100644
--- a/src/UTMetadataRejectExtensionMessage.cc
+++ b/src/UTMetadataRejectExtensionMessage.cc
@@ -41,8 +41,9 @@
 namespace aria2 {
 
 UTMetadataRejectExtensionMessage::UTMetadataRejectExtensionMessage
-(uint8_t extensionMessageID):
-  UTMetadataExtensionMessage(extensionMessageID) {}
+(uint8_t extensionMessageID)
+  : UTMetadataExtensionMessage{extensionMessageID}
+{}
 
 std::string UTMetadataRejectExtensionMessage::getPayload()
 {
diff --git a/src/UTMetadataRequestExtensionMessage.cc b/src/UTMetadataRequestExtensionMessage.cc
index 21795929e..42b9a8872 100644
--- a/src/UTMetadataRequestExtensionMessage.cc
+++ b/src/UTMetadataRequestExtensionMessage.cc
@@ -54,13 +54,13 @@
 namespace aria2 {
 
 UTMetadataRequestExtensionMessage::UTMetadataRequestExtensionMessage
-(uint8_t extensionMessageID):UTMetadataExtensionMessage(extensionMessageID),
-                             dispatcher_(0),
-                             messageFactory_(0)
+(uint8_t extensionMessageID)
+  : UTMetadataExtensionMessage{extensionMessageID},
+    dctx_{nullptr},
+    dispatcher_{nullptr},
+    messageFactory_{nullptr}
 {}
 
-UTMetadataRequestExtensionMessage::~UTMetadataRequestExtensionMessage() {}
-
 std::string UTMetadataRequestExtensionMessage::getPayload()
 {
   Dict dict;
@@ -81,25 +81,22 @@ void UTMetadataRequestExtensionMessage::doReceivedAction()
   uint8_t id = peer_->getExtensionMessageID
     (ExtensionMessageRegistry::UT_METADATA);
   if(attrs->metadata.empty()) {
-    std::shared_ptr<UTMetadataRejectExtensionMessage> m
-      (new UTMetadataRejectExtensionMessage(id));
+    auto m = make_unique<UTMetadataRejectExtensionMessage>(id);
     m->setIndex(getIndex());
     dispatcher_->addMessageToQueue
-      (messageFactory_->createBtExtendedMessage(m));
+      (messageFactory_->createBtExtendedMessage(std::move(m)));
   }else if(getIndex()*METADATA_PIECE_SIZE < attrs->metadataSize) {
-    std::shared_ptr<UTMetadataDataExtensionMessage> m
-      (new UTMetadataDataExtensionMessage(id));
+    auto m = make_unique<UTMetadataDataExtensionMessage>(id);
     m->setIndex(getIndex());
     m->setTotalSize(attrs->metadataSize);
-    std::string::const_iterator begin =
-      attrs->metadata.begin()+getIndex()*METADATA_PIECE_SIZE;
-    std::string::const_iterator end =
+    auto begin = std::begin(attrs->metadata)+getIndex()*METADATA_PIECE_SIZE;
+    auto end =
       (getIndex()+1)*METADATA_PIECE_SIZE <= attrs->metadata.size()?
-      attrs->metadata.begin()+(getIndex()+1)*METADATA_PIECE_SIZE:
-      attrs->metadata.end();
+      std::begin(attrs->metadata)+(getIndex()+1)*METADATA_PIECE_SIZE:
+      std::end(attrs->metadata);
     m->setData(begin, end);
     dispatcher_->addMessageToQueue
-      (messageFactory_->createBtExtendedMessage(m));
+      (messageFactory_->createBtExtendedMessage(std::move(m)));
   } else {
     throw DL_ABORT_EX
       (fmt("Metadata piece index is too big. piece=%lu",
@@ -108,14 +105,27 @@ void UTMetadataRequestExtensionMessage::doReceivedAction()
 }
 
 void UTMetadataRequestExtensionMessage::setDownloadContext
-(const std::shared_ptr<DownloadContext>& dctx)
+(DownloadContext* dctx)
 {
   dctx_ = dctx;
 }
 
-void UTMetadataRequestExtensionMessage::setPeer(const std::shared_ptr<Peer>& peer)
+void UTMetadataRequestExtensionMessage::setPeer
+(const std::shared_ptr<Peer>& peer)
 {
   peer_ = peer;
 }
 
+void UTMetadataRequestExtensionMessage::setBtMessageDispatcher
+(BtMessageDispatcher* disp)
+{
+  dispatcher_ = disp;
+}
+
+void UTMetadataRequestExtensionMessage::setBtMessageFactory
+(BtMessageFactory* factory)
+{
+  messageFactory_ = factory;
+}
+
 } // namespace aria2
diff --git a/src/UTMetadataRequestExtensionMessage.h b/src/UTMetadataRequestExtensionMessage.h
index f7896f131..eaba6b3c0 100644
--- a/src/UTMetadataRequestExtensionMessage.h
+++ b/src/UTMetadataRequestExtensionMessage.h
@@ -48,7 +48,7 @@ class Peer;
 
 class UTMetadataRequestExtensionMessage:public UTMetadataExtensionMessage {
 private:
-  std::shared_ptr<DownloadContext> dctx_;
+  DownloadContext* dctx_;
 
   std::shared_ptr<Peer> peer_;
 
@@ -58,25 +58,17 @@ private:
 public:
   UTMetadataRequestExtensionMessage(uint8_t extensionMessageID);
 
-  ~UTMetadataRequestExtensionMessage();
-
   virtual std::string getPayload();
 
   virtual std::string toString() const;
 
   virtual void doReceivedAction();
 
-  void setDownloadContext(const std::shared_ptr<DownloadContext>& dctx);
+  void setDownloadContext(DownloadContext* dctx);
 
-  void setBtMessageDispatcher(BtMessageDispatcher* disp)
-  {
-    dispatcher_ = disp;
-  }
+  void setBtMessageDispatcher(BtMessageDispatcher* disp);
 
-  void setBtMessageFactory(BtMessageFactory* factory)
-  {
-    messageFactory_ = factory;
-  }
+  void setBtMessageFactory(BtMessageFactory* factory);
 
   void setPeer(const std::shared_ptr<Peer>& peer);
 };
diff --git a/src/UTMetadataRequestFactory.cc b/src/UTMetadataRequestFactory.cc
index fe895bfef..3824ec4cd 100644
--- a/src/UTMetadataRequestFactory.cc
+++ b/src/UTMetadataRequestFactory.cc
@@ -50,14 +50,15 @@
 namespace aria2 {
 
 UTMetadataRequestFactory::UTMetadataRequestFactory()
-  : dispatcher_{nullptr},
+  : dctx_{nullptr},
+    dispatcher_{nullptr},
     messageFactory_{nullptr},
     tracker_{nullptr},
-    cuid_(0)
+    cuid_{0}
 {}
 
 std::vector<std::unique_ptr<BtMessage>> UTMetadataRequestFactory::create
-(size_t num, const std::shared_ptr<PieceStorage>& pieceStorage)
+(size_t num, PieceStorage* pieceStorage)
 {
   auto msgs = std::vector<std::unique_ptr<BtMessage>>{};
   while(num) {
@@ -70,16 +71,15 @@ std::vector<std::unique_ptr<BtMessage>> UTMetadataRequestFactory::create
     --num;
     A2_LOG_DEBUG(fmt("Creating ut_metadata request index=%lu",
                      static_cast<unsigned long>(p->getIndex())));
-    std::shared_ptr<UTMetadataRequestExtensionMessage> m
-      (new UTMetadataRequestExtensionMessage
-       (peer_->getExtensionMessageID(ExtensionMessageRegistry::UT_METADATA)));
+    auto m = make_unique<UTMetadataRequestExtensionMessage>
+      (peer_->getExtensionMessageID(ExtensionMessageRegistry::UT_METADATA));
     m->setIndex(p->getIndex());
     m->setDownloadContext(dctx_);
     m->setBtMessageDispatcher(dispatcher_);
     m->setBtMessageFactory(messageFactory_);
     m->setPeer(peer_);
 
-    msgs.push_back(messageFactory_->createBtExtendedMessage(m));
+    msgs.push_back(messageFactory_->createBtExtendedMessage(std::move(m)));
     tracker_->add(p->getIndex());
   }
   return msgs;
diff --git a/src/UTMetadataRequestFactory.h b/src/UTMetadataRequestFactory.h
index e8de1e67b..7e5688d85 100644
--- a/src/UTMetadataRequestFactory.h
+++ b/src/UTMetadataRequestFactory.h
@@ -54,7 +54,7 @@ class BtMessage;
 
 class UTMetadataRequestFactory {
 private:
-  std::shared_ptr<DownloadContext> dctx_;
+  DownloadContext* dctx_;
 
   std::shared_ptr<Peer> peer_;
 
@@ -70,9 +70,9 @@ public:
   // Creates and returns at most num of ut_metadata request
   // message. pieceStorage is used to identify missing piece.
   std::vector<std::unique_ptr<BtMessage>> create
-  (size_t num, const std::shared_ptr<PieceStorage>& pieceStorage);
+  (size_t num, PieceStorage* pieceStorage);
 
-  void setDownloadContext(const std::shared_ptr<DownloadContext>& dctx)
+  void setDownloadContext(DownloadContext* dctx)
   {
     dctx_ = dctx;
   }
diff --git a/src/UTPexExtensionMessage.cc b/src/UTPexExtensionMessage.cc
index 4def037f5..f005d307c 100644
--- a/src/UTPexExtensionMessage.cc
+++ b/src/UTPexExtensionMessage.cc
@@ -57,23 +57,18 @@ const size_t DEFAULT_MAX_DROPPED_PEER = 50;
 
 const char UTPexExtensionMessage::EXTENSION_NAME[] = "ut_pex";
 
-UTPexExtensionMessage::UTPexExtensionMessage(uint8_t extensionMessageID):
-  extensionMessageID_(extensionMessageID),
-  interval_(DEFAULT_INTERVAL),
-  maxFreshPeer_(DEFAULT_MAX_FRESH_PEER),
-  maxDroppedPeer_(DEFAULT_MAX_DROPPED_PEER) {}
-
-UTPexExtensionMessage::~UTPexExtensionMessage() {}
+UTPexExtensionMessage::UTPexExtensionMessage(uint8_t extensionMessageID)
+  : extensionMessageID_{extensionMessageID},
+    peerStorage_{nullptr},
+    interval_{DEFAULT_INTERVAL},
+    maxFreshPeer_{DEFAULT_MAX_FRESH_PEER},
+    maxDroppedPeer_{DEFAULT_MAX_DROPPED_PEER}
+ {}
 
 std::string UTPexExtensionMessage::getPayload()
 {
-  std::pair<std::pair<std::string, std::string>,
-            std::pair<std::string, std::string> > freshPeerPair =
-    createCompactPeerListAndFlag(freshPeers_);
-  std::pair<std::pair<std::string, std::string>,
-            std::pair<std::string, std::string> > droppedPeerPair =
-    createCompactPeerListAndFlag(droppedPeers_);
-
+  auto freshPeerPair = createCompactPeerListAndFlag(freshPeers_);
+  auto droppedPeerPair = createCompactPeerListAndFlag(droppedPeers_);
   Dict dict;
   if(!freshPeerPair.first.first.empty()) {
     dict.put("added", freshPeerPair.first.first);
@@ -102,8 +97,7 @@ UTPexExtensionMessage::createCompactPeerListAndFlag
   std::string flagstring;
   std::string addrstring6;
   std::string flagstring6;
-  for(std::vector<std::shared_ptr<Peer> >::const_iterator itr = peers.begin(),
-        eoi = peers.end(); itr != eoi; ++itr) {
+  for(auto itr = std::begin(peers), eoi = std::end(peers); itr != eoi; ++itr) {
     unsigned char compact[COMPACT_LEN_IPV6];
     int compactlen = bittorrent::packcompact
       (compact, (*itr)->getIPAddress(), (*itr)->getPort());
@@ -115,8 +109,10 @@ UTPexExtensionMessage::createCompactPeerListAndFlag
       flagstring6 += (*itr)->isSeeder() ? 0x02u : 0x00u;
     }
   }
-  return std::make_pair(std::make_pair(addrstring, flagstring),
-                        std::make_pair(addrstring6, flagstring6));
+  return std::make_pair(std::make_pair(std::move(addrstring),
+                                       std::move(flagstring)),
+                        std::make_pair(std::move(addrstring6),
+                                       std::move(flagstring6)));
 }
 
 std::string UTPexExtensionMessage::toString() const
@@ -143,6 +139,12 @@ bool UTPexExtensionMessage::addFreshPeer(const std::shared_ptr<Peer>& peer)
   }
 }
 
+const std::vector<std::shared_ptr<Peer>>&
+UTPexExtensionMessage::getFreshPeers() const
+{
+  return freshPeers_;
+}
+
 bool UTPexExtensionMessage::freshPeersAreFull() const
 {
   return freshPeers_.size() >= maxFreshPeer_;
@@ -159,6 +161,12 @@ bool UTPexExtensionMessage::addDroppedPeer(const std::shared_ptr<Peer>& peer)
   }
 }
 
+const std::vector<std::shared_ptr<Peer>>&
+UTPexExtensionMessage::getDroppedPeers() const
+{
+  return droppedPeers_;
+}
+
 bool UTPexExtensionMessage::droppedPeersAreFull() const
 {
   return droppedPeers_.size() >= maxDroppedPeer_;
@@ -174,13 +182,12 @@ void UTPexExtensionMessage::setMaxDroppedPeer(size_t maxDroppedPeer)
   maxDroppedPeer_ = maxDroppedPeer;
 }
 
-void UTPexExtensionMessage::setPeerStorage
-(const std::shared_ptr<PeerStorage>& peerStorage)
+void UTPexExtensionMessage::setPeerStorage(PeerStorage* peerStorage)
 {
   peerStorage_ = peerStorage;
 }
 
-UTPexExtensionMessage*
+std::unique_ptr<UTPexExtensionMessage>
 UTPexExtensionMessage::create(const unsigned char* data, size_t len)
 {
   if(len < 1) {
@@ -188,9 +195,9 @@ UTPexExtensionMessage::create(const unsigned char* data, size_t len)
                           EXTENSION_NAME,
                           static_cast<unsigned long>(len)));
   }
-  UTPexExtensionMessage* msg(new UTPexExtensionMessage(*data));
+  auto msg = make_unique<UTPexExtensionMessage>(*data);
 
-  std::shared_ptr<ValueBase> decoded = bencode2::decode(data+1, len - 1);
+  auto decoded = bencode2::decode(data+1, len - 1);
   const Dict* dict = downcast<Dict>(decoded);
   if(dict) {
     const String* added = downcast<String>(dict->get("added"));
diff --git a/src/UTPexExtensionMessage.h b/src/UTPexExtensionMessage.h
index 6bbcd302e..e977f9f65 100644
--- a/src/UTPexExtensionMessage.h
+++ b/src/UTPexExtensionMessage.h
@@ -56,7 +56,7 @@ private:
 
   std::vector<std::shared_ptr<Peer> > droppedPeers_;
 
-  std::shared_ptr<PeerStorage> peerStorage_;
+  PeerStorage* peerStorage_;
 
   time_t interval_;
 
@@ -65,14 +65,12 @@ private:
   size_t maxDroppedPeer_;
 
   std::pair<std::pair<std::string, std::string>,
-            std::pair<std::string, std::string> >
-  createCompactPeerListAndFlag(const std::vector<std::shared_ptr<Peer> >& peers);
+            std::pair<std::string, std::string>>
+  createCompactPeerListAndFlag(const std::vector<std::shared_ptr<Peer>>& peers);
 
 public:
   UTPexExtensionMessage(uint8_t extensionMessageID);
 
-  virtual ~UTPexExtensionMessage();
-
   virtual std::string getPayload();
 
   virtual uint8_t getExtensionMessageID() const
@@ -93,25 +91,19 @@ public:
 
   bool addFreshPeer(const std::shared_ptr<Peer>& peer);
 
-  const std::vector<std::shared_ptr<Peer> >& getFreshPeers() const
-  {
-    return freshPeers_;
-  }
+  const std::vector<std::shared_ptr<Peer>>& getFreshPeers() const;
 
   bool freshPeersAreFull() const;
 
   bool addDroppedPeer(const std::shared_ptr<Peer>& peer);
 
-  const std::vector<std::shared_ptr<Peer> >& getDroppedPeers() const
-  {
-    return droppedPeers_;
-  }
+  const std::vector<std::shared_ptr<Peer>>& getDroppedPeers() const;
 
   bool droppedPeersAreFull() const;
 
-  void setPeerStorage(const std::shared_ptr<PeerStorage>& peerStorage);
+  void setPeerStorage(PeerStorage* peerStorage);
 
-  static UTPexExtensionMessage*
+  static std::unique_ptr<UTPexExtensionMessage>
   create(const unsigned char* data, size_t len);
 
   void setMaxFreshPeer(size_t maxFreshPeer);
diff --git a/test/BtExtendedMessageTest.cc b/test/BtExtendedMessageTest.cc
index a459e2871..642b9a2ce 100644
--- a/test/BtExtendedMessageTest.cc
+++ b/test/BtExtendedMessageTest.cc
@@ -33,11 +33,9 @@ public:
 CPPUNIT_TEST_SUITE_REGISTRATION(BtExtendedMessageTest);
 
 void BtExtendedMessageTest::testCreate() {
-  std::shared_ptr<Peer> peer(new Peer("192.168.0.1", 6969));
+  auto peer = std::make_shared<Peer>("192.168.0.1", 6969);
   peer->allocateSessionResource(1024, 1024*1024);
-
-  std::shared_ptr<MockExtensionMessageFactory> exmsgFactory
-    (new MockExtensionMessageFactory());
+  auto exmsgFactory = MockExtensionMessageFactory{};
 
   // payload:{4:name3:foo}->11bytes
   std::string payload = "4:name3:foo";
@@ -45,16 +43,14 @@ void BtExtendedMessageTest::testCreate() {
   bittorrent::createPeerMessageString((unsigned char*)msg, sizeof(msg), 13, 20);
   msg[5] = 1; // Set dummy extended message ID 1
   memcpy(msg+6, payload.c_str(), payload.size());
-  std::shared_ptr<BtExtendedMessage> pm(BtExtendedMessage::create(exmsgFactory,
-                                                               peer,
-                                                               &msg[4], 13));
+  auto pm = BtExtendedMessage::create(&exmsgFactory, peer, &msg[4], 13);
   CPPUNIT_ASSERT_EQUAL((uint8_t)20, pm->getId());
 
   // case: payload size is wrong
   try {
     unsigned char msg[5];
     bittorrent::createPeerMessageString(msg, sizeof(msg), 1, 20);
-    BtExtendedMessage::create(exmsgFactory, peer, &msg[4], 1);
+    BtExtendedMessage::create(&exmsgFactory, peer, &msg[4], 1);
     CPPUNIT_FAIL("exception must be thrown.");
   } catch(Exception& e) {
     std::cerr << e.stackTrace() << std::endl;
@@ -63,7 +59,7 @@ void BtExtendedMessageTest::testCreate() {
   try {
     unsigned char msg[6];
     bittorrent::createPeerMessageString(msg, sizeof(msg), 2, 21);
-    BtExtendedMessage::create(exmsgFactory, peer, &msg[4], 2);
+    BtExtendedMessage::create(&exmsgFactory, peer, &msg[4], 2);
     CPPUNIT_FAIL("exception must be thrown.");
   } catch(Exception& e) {
     std::cerr << e.stackTrace() << std::endl;
@@ -73,10 +69,8 @@ void BtExtendedMessageTest::testCreate() {
 void BtExtendedMessageTest::testCreateMessage() {
   std::string payload = "4:name3:foo";
   uint8_t extendedMessageID = 1;
-  std::shared_ptr<MockExtensionMessage> exmsg
-    (new MockExtensionMessage("charlie", extendedMessageID, payload));
-  BtExtendedMessage msg(exmsg);
-
+  BtExtendedMessage msg{make_unique<MockExtensionMessage>
+      ("charlie", extendedMessageID, payload, nullptr)};
   unsigned char data[17];
   bittorrent::createPeerMessageString(data, sizeof(data), 13, 20);
   *(data+5) = extendedMessageID;
@@ -88,19 +82,18 @@ void BtExtendedMessageTest::testCreateMessage() {
 }
 
 void BtExtendedMessageTest::testDoReceivedAction() {
-  std::shared_ptr<MockExtensionMessage> exmsg
-    (new MockExtensionMessage("charlie", 1, ""));
-  BtExtendedMessage msg(exmsg);
+  auto evcheck = MockExtensionMessageEventCheck{};
+  BtExtendedMessage msg{make_unique<MockExtensionMessage>
+      ("charlie", 1, "", &evcheck)};
   msg.doReceivedAction();
-  CPPUNIT_ASSERT(exmsg->doReceivedActionCalled_);
+  CPPUNIT_ASSERT(evcheck.doReceivedActionCalled);
 }
 
 void BtExtendedMessageTest::testToString() {
   std::string payload = "4:name3:foo";
   uint8_t extendedMessageID = 1;
-  std::shared_ptr<MockExtensionMessage> exmsg
-    (new MockExtensionMessage("charlie", extendedMessageID, payload));
-  BtExtendedMessage msg(exmsg);
+  BtExtendedMessage msg{make_unique<MockExtensionMessage>
+      ("charlie", extendedMessageID, payload, nullptr)};
   CPPUNIT_ASSERT_EQUAL(std::string("extended charlie"), msg.toString());
 }
 
diff --git a/test/DefaultBtMessageFactoryTest.cc b/test/DefaultBtMessageFactoryTest.cc
index 048744f09..76e18f859 100644
--- a/test/DefaultBtMessageFactoryTest.cc
+++ b/test/DefaultBtMessageFactoryTest.cc
@@ -42,7 +42,7 @@ public:
     factory_ = make_unique<DefaultBtMessageFactory>();
     factory_->setDownloadContext(dctx_.get());
     factory_->setPeer(peer_);
-    factory_->setExtensionMessageFactory(exmsgFactory_);
+    factory_->setExtensionMessageFactory(exmsgFactory_.get());
   }
 
   void testCreateBtMessage_BtExtendedMessage();
diff --git a/test/DefaultExtensionMessageFactoryTest.cc b/test/DefaultExtensionMessageFactoryTest.cc
index 82acb8a1e..d5fe00a39 100644
--- a/test/DefaultExtensionMessageFactoryTest.cc
+++ b/test/DefaultExtensionMessageFactoryTest.cc
@@ -38,42 +38,38 @@ class DefaultExtensionMessageFactoryTest:public CppUnit::TestFixture {
   CPPUNIT_TEST(testCreateMessage_UTMetadataReject);
   CPPUNIT_TEST_SUITE_END();
 private:
-  std::shared_ptr<MockPeerStorage> peerStorage_;
+  std::unique_ptr<MockPeerStorage> peerStorage_;
   std::shared_ptr<Peer> peer_;
-  std::shared_ptr<DefaultExtensionMessageFactory> factory_;
-  std::shared_ptr<ExtensionMessageRegistry> registry_;
-  std::shared_ptr<MockBtMessageDispatcher> dispatcher_;
-  std::shared_ptr<MockBtMessageFactory> messageFactory_;
+  std::unique_ptr<DefaultExtensionMessageFactory> factory_;
+  std::unique_ptr<ExtensionMessageRegistry> registry_;
+  std::unique_ptr<MockBtMessageDispatcher> dispatcher_;
+  std::unique_ptr<MockBtMessageFactory> messageFactory_;
   std::shared_ptr<DownloadContext> dctx_;
-  std::shared_ptr<RequestGroup> requestGroup_;
+  std::unique_ptr<RequestGroup> requestGroup_;
 public:
   void setUp()
   {
-    peerStorage_.reset(new MockPeerStorage());
+    peerStorage_ = make_unique<MockPeerStorage>();
 
-    peer_.reset(new Peer("192.168.0.1", 6969));
+    peer_ = std::make_shared<Peer>("192.168.0.1", 6969);
     peer_->allocateSessionResource(1024, 1024*1024);
     peer_->setExtension(ExtensionMessageRegistry::UT_PEX, 1);
 
-    registry_.reset(new ExtensionMessageRegistry());
-
-    dispatcher_.reset(new MockBtMessageDispatcher());
-
-    messageFactory_.reset(new MockBtMessageFactory());
-
-    dctx_.reset(new DownloadContext());
-
-    std::shared_ptr<Option> option(new Option());
-    requestGroup_.reset(new RequestGroup(GroupId::create(), option));
+    registry_ = make_unique<ExtensionMessageRegistry>();
+    dispatcher_ = make_unique<MockBtMessageDispatcher>();
+    messageFactory_ = make_unique<MockBtMessageFactory>();
+    dctx_ = std::make_shared<DownloadContext>();
+    auto option = std::make_shared<Option>();
+    requestGroup_ = make_unique<RequestGroup>(GroupId::create(), option);
     requestGroup_->setDownloadContext(dctx_);
 
-    factory_.reset(new DefaultExtensionMessageFactory());
-    factory_->setPeerStorage(peerStorage_);
+    factory_ = make_unique<DefaultExtensionMessageFactory>();
+    factory_->setPeerStorage(peerStorage_.get());
     factory_->setPeer(peer_);
-    factory_->setExtensionMessageRegistry(registry_);
+    factory_->setExtensionMessageRegistry(registry_.get());
     factory_->setBtMessageDispatcher(dispatcher_.get());
     factory_->setBtMessageFactory(messageFactory_.get());
-    factory_->setDownloadContext(dctx_);
+    factory_->setDownloadContext(dctx_.get());
   }
 
   std::string getExtensionMessageID(int key)
@@ -85,9 +81,10 @@ public:
   template<typename T>
   std::shared_ptr<T> createMessage(const std::string& data)
   {
-    return std::dynamic_pointer_cast<T>
-      (factory_->createMessage
-       (reinterpret_cast<const unsigned char*>(data.c_str()), data.size()));
+    auto m = factory_->createMessage
+      (reinterpret_cast<const unsigned char*>(data.c_str()), data.size());
+    return std::dynamic_pointer_cast<T>(std::shared_ptr<T>
+      {static_cast<T*>(m.release())});
   }
 
   void testCreateMessage_unknown();
@@ -98,7 +95,6 @@ public:
   void testCreateMessage_UTMetadataReject();
 };
 
-
 CPPUNIT_TEST_SUITE_REGISTRATION(DefaultExtensionMessageFactoryTest);
 
 void DefaultExtensionMessageFactoryTest::testCreateMessage_unknown()
@@ -123,8 +119,7 @@ void DefaultExtensionMessageFactoryTest::testCreateMessage_Handshake()
   char id[1] = { 0 };
 
   std::string data = std::string(&id[0], &id[1])+"d1:v5:aria2e";
-  std::shared_ptr<HandshakeExtensionMessage> m =
-    createMessage<HandshakeExtensionMessage>(data);
+  auto m = createMessage<HandshakeExtensionMessage>(data);
   CPPUNIT_ASSERT_EQUAL(std::string("aria2"), m->getClientVersion());
 }
 
@@ -148,8 +143,7 @@ void DefaultExtensionMessageFactoryTest::testCreateMessage_UTPex()
     std::string(&c3[0], &c3[6])+std::string(&c4[0], &c4[6])+
     "e";
 
-  std::shared_ptr<UTPexExtensionMessage> m =
-    createMessage<UTPexExtensionMessage>(data);
+  auto m = createMessage<UTPexExtensionMessage>(data);
   CPPUNIT_ASSERT_EQUAL(registry_->getExtensionMessageID
                        (ExtensionMessageRegistry::UT_PEX),
                        m->getExtensionMessageID());
@@ -162,8 +156,7 @@ void DefaultExtensionMessageFactoryTest::testCreateMessage_UTMetadataRequest()
   std::string data = getExtensionMessageID
     (ExtensionMessageRegistry::UT_METADATA)+
     "d8:msg_typei0e5:piecei1ee";
-  std::shared_ptr<UTMetadataRequestExtensionMessage> m =
-    createMessage<UTMetadataRequestExtensionMessage>(data);
+  auto m = createMessage<UTMetadataRequestExtensionMessage>(data);
   CPPUNIT_ASSERT_EQUAL((size_t)1, m->getIndex());
 }
 
@@ -174,8 +167,7 @@ void DefaultExtensionMessageFactoryTest::testCreateMessage_UTMetadataData()
   std::string data = getExtensionMessageID
     (ExtensionMessageRegistry::UT_METADATA)+
     "d8:msg_typei1e5:piecei1e10:total_sizei300ee0000000000";
-  std::shared_ptr<UTMetadataDataExtensionMessage> m =
-    createMessage<UTMetadataDataExtensionMessage>(data);
+  auto m = createMessage<UTMetadataDataExtensionMessage>(data);
   CPPUNIT_ASSERT_EQUAL((size_t)1, m->getIndex());
   CPPUNIT_ASSERT_EQUAL((size_t)300, m->getTotalSize());
   CPPUNIT_ASSERT_EQUAL(std::string(10, '0'), m->getData());
@@ -188,8 +180,7 @@ void DefaultExtensionMessageFactoryTest::testCreateMessage_UTMetadataReject()
   std::string data = getExtensionMessageID
     (ExtensionMessageRegistry::UT_METADATA)+
     "d8:msg_typei2e5:piecei1ee";
-  std::shared_ptr<UTMetadataRejectExtensionMessage> m =
-    createMessage<UTMetadataRejectExtensionMessage>(data);
+  auto m = createMessage<UTMetadataRejectExtensionMessage>(data);
   CPPUNIT_ASSERT_EQUAL((size_t)1, m->getIndex());
 }
 
diff --git a/test/HandshakeExtensionMessageTest.cc b/test/HandshakeExtensionMessageTest.cc
index bdd16cdf6..8a4d35e6b 100644
--- a/test/HandshakeExtensionMessageTest.cc
+++ b/test/HandshakeExtensionMessageTest.cc
@@ -91,16 +91,15 @@ void HandshakeExtensionMessageTest::testToString()
 
 void HandshakeExtensionMessageTest::testDoReceivedAction()
 {
-  std::shared_ptr<DownloadContext> dctx
-    (new DownloadContext(METADATA_PIECE_SIZE, 0));
-  std::shared_ptr<Option> op(new Option());
+  auto dctx = std::make_shared<DownloadContext>(METADATA_PIECE_SIZE, 0);
+  auto op = std::make_shared<Option>();
   RequestGroup rg(GroupId::create(), op);
   rg.setDownloadContext(dctx);
 
   dctx->setAttribute(CTX_ATTR_BT, make_unique<TorrentAttribute>());
   dctx->markTotalLengthIsUnknown();
 
-  std::shared_ptr<Peer> peer(new Peer("192.168.0.1", 0));
+  auto peer = std::make_shared<Peer>("192.168.0.1", 0);
   peer->allocateSessionResource(1024, 1024*1024);
   HandshakeExtensionMessage msg;
   msg.setClientVersion("aria2");
@@ -109,7 +108,7 @@ void HandshakeExtensionMessageTest::testDoReceivedAction()
   msg.setExtension(ExtensionMessageRegistry::UT_METADATA, 3);
   msg.setMetadataSize(1024);
   msg.setPeer(peer);
-  msg.setDownloadContext(dctx);
+  msg.setDownloadContext(dctx.get());
 
   msg.doReceivedAction();
 
diff --git a/test/MockBtMessageFactory.h b/test/MockBtMessageFactory.h
index b4572e93f..40b39b00f 100644
--- a/test/MockBtMessageFactory.h
+++ b/test/MockBtMessageFactory.h
@@ -20,6 +20,7 @@
 #include "BtAllowedFastMessage.h"
 #include "BtPortMessage.h"
 #include "BtExtendedMessage.h"
+#include "ExtensionMessage.h"
 
 namespace aria2 {
 
@@ -114,7 +115,7 @@ public:
   }
 
   virtual std::unique_ptr<BtExtendedMessage>
-  createBtExtendedMessage(const std::shared_ptr<ExtensionMessage>& extmsg)
+  createBtExtendedMessage(std::unique_ptr<ExtensionMessage> extmsg)
   {
     return std::unique_ptr<BtExtendedMessage>{};
   }
diff --git a/test/MockExtensionMessage.h b/test/MockExtensionMessage.h
index cf23693a5..06861e34b 100644
--- a/test/MockExtensionMessage.h
+++ b/test/MockExtensionMessage.h
@@ -5,30 +5,38 @@
 
 namespace aria2 {
 
+struct MockExtensionMessageEventCheck {
+  MockExtensionMessageEventCheck() : doReceivedActionCalled{false}
+  {}
+  bool doReceivedActionCalled;
+};
+
 class MockExtensionMessage:public ExtensionMessage {
 public:
   std::string extensionName_;
   uint8_t extensionMessageID_;
   std::string data_;
-  bool doReceivedActionCalled_;
-public:
+  MockExtensionMessageEventCheck* evcheck_;
+
   MockExtensionMessage(const std::string& extensionName,
                        uint8_t extensionMessageID,
                        const unsigned char* data,
-                       size_t length)
+                       size_t length,
+                       MockExtensionMessageEventCheck* evcheck)
     : extensionName_{extensionName},
       extensionMessageID_{extensionMessageID},
       data_{&data[0], &data[length]},
-      doReceivedActionCalled_{false}
+      evcheck_{evcheck}
   {}
 
   MockExtensionMessage(const std::string& extensionName,
                        uint8_t extensionMessageID,
-                       const std::string& data)
+                       const std::string& data,
+                       MockExtensionMessageEventCheck* evcheck)
     : extensionName_{extensionName},
       extensionMessageID_{extensionMessageID},
       data_{data},
-      doReceivedActionCalled_{false}
+      evcheck_{evcheck}
   {}
 
   virtual std::string getPayload()
@@ -53,7 +61,9 @@ public:
 
   virtual void doReceivedAction()
   {
-    doReceivedActionCalled_ = true;
+    if(evcheck_) {
+      evcheck_->doReceivedActionCalled = true;
+    }
   }
 };
 
diff --git a/test/MockExtensionMessageFactory.h b/test/MockExtensionMessageFactory.h
index 3fb422f48..ec138cb3f 100644
--- a/test/MockExtensionMessageFactory.h
+++ b/test/MockExtensionMessageFactory.h
@@ -10,11 +10,11 @@ class MockExtensionMessageFactory:public ExtensionMessageFactory {
 public:
   virtual ~MockExtensionMessageFactory() {}
 
-  virtual std::shared_ptr<ExtensionMessage> createMessage(const unsigned char* data,
-                                                       size_t length)
+  virtual std::unique_ptr<ExtensionMessage>
+  createMessage(const unsigned char* data, size_t length)
   {
-    return std::shared_ptr<ExtensionMessage>
-      (new MockExtensionMessage("a2_mock", *data, data+1, length-1));
+    return make_unique<MockExtensionMessage>
+      ("a2_mock", *data, data+1, length-1, nullptr);
   }
 };
 
diff --git a/test/UTMetadataDataExtensionMessageTest.cc b/test/UTMetadataDataExtensionMessageTest.cc
index be6c2529e..9e1a4af80 100644
--- a/test/UTMetadataDataExtensionMessageTest.cc
+++ b/test/UTMetadataDataExtensionMessageTest.cc
@@ -65,14 +65,13 @@ void UTMetadataDataExtensionMessageTest::testToString()
 
 void UTMetadataDataExtensionMessageTest::testDoReceivedAction()
 {
-  std::shared_ptr<DirectDiskAdaptor> diskAdaptor(new DirectDiskAdaptor());
-  std::shared_ptr<ByteArrayDiskWriter> diskWriter(new ByteArrayDiskWriter());
+  auto diskAdaptor = std::make_shared<DirectDiskAdaptor>();
+  auto diskWriter = std::make_shared<ByteArrayDiskWriter>();
   diskAdaptor->setDiskWriter(diskWriter);
-  std::shared_ptr<MockPieceStorage> pieceStorage(new MockPieceStorage());
+  auto pieceStorage = make_unique<MockPieceStorage>();
   pieceStorage->setDiskAdaptor(diskAdaptor);
-  std::shared_ptr<UTMetadataRequestTracker> tracker
-    (new UTMetadataRequestTracker());
-  std::shared_ptr<DownloadContext> dctx(new DownloadContext());
+  auto tracker = make_unique<UTMetadataRequestTracker>();
+  auto dctx = make_unique<DownloadContext>();
 
   std::string piece0 = std::string(METADATA_PIECE_SIZE, '0');
   std::string piece1 = std::string(METADATA_PIECE_SIZE, '1');
@@ -88,9 +87,9 @@ void UTMetadataDataExtensionMessageTest::testDoReceivedAction()
     dctx->setAttribute(CTX_ATTR_BT, std::move(attrs));
   }
   UTMetadataDataExtensionMessage m(1);
-  m.setPieceStorage(pieceStorage);
+  m.setPieceStorage(pieceStorage.get());
   m.setUTMetadataRequestTracker(tracker.get());
-  m.setDownloadContext(dctx);
+  m.setDownloadContext(dctx.get());
 
   m.setIndex(1);
   m.setData(piece1);
diff --git a/test/UTMetadataRequestExtensionMessageTest.cc b/test/UTMetadataRequestExtensionMessageTest.cc
index c77215b2b..1311da28d 100644
--- a/test/UTMetadataRequestExtensionMessageTest.cc
+++ b/test/UTMetadataRequestExtensionMessageTest.cc
@@ -31,7 +31,7 @@ class UTMetadataRequestExtensionMessageTest:public CppUnit::TestFixture {
   CPPUNIT_TEST(testDoReceivedAction_data);
   CPPUNIT_TEST_SUITE_END();
 public:
-  std::shared_ptr<DownloadContext> dctx_;
+  std::unique_ptr<DownloadContext> dctx_;
   std::unique_ptr<WrapExtBtMessageFactory> messageFactory_;
   std::unique_ptr<MockBtMessageDispatcher> dispatcher_;
   std::shared_ptr<Peer> peer_;
@@ -40,7 +40,7 @@ public:
   {
     messageFactory_ = make_unique<WrapExtBtMessageFactory>();
     dispatcher_ = make_unique<MockBtMessageDispatcher>();
-    dctx_ = std::make_shared<DownloadContext>();
+    dctx_ = make_unique<DownloadContext>();
     dctx_->setAttribute(CTX_ATTR_BT, make_unique<TorrentAttribute>());
     peer_ = std::make_shared<Peer>("host", 6880);
     peer_->allocateSessionResource(0, 0);
@@ -101,7 +101,7 @@ void UTMetadataRequestExtensionMessageTest::testDoReceivedAction_reject()
 {
   UTMetadataRequestExtensionMessage msg(1);
   msg.setIndex(10);
-  msg.setDownloadContext(dctx_);
+  msg.setDownloadContext(dctx_.get());
   msg.setPeer(peer_);
   msg.setBtMessageFactory(messageFactory_.get());
   msg.setBtMessageDispatcher(dispatcher_.get());
@@ -118,13 +118,13 @@ void UTMetadataRequestExtensionMessageTest::testDoReceivedAction_data()
 {
   UTMetadataRequestExtensionMessage msg(1);
   msg.setIndex(1);
-  msg.setDownloadContext(dctx_);
+  msg.setDownloadContext(dctx_.get());
   msg.setPeer(peer_);
   msg.setBtMessageFactory(messageFactory_.get());
   msg.setBtMessageDispatcher(dispatcher_.get());
 
   size_t metadataSize = METADATA_PIECE_SIZE*2;
-  auto attrs = bittorrent::getTorrentAttrs(dctx_);
+  auto attrs = bittorrent::getTorrentAttrs(dctx_.get());
   std::string first(METADATA_PIECE_SIZE, '0');
   std::string second(METADATA_PIECE_SIZE, '1');
   attrs->metadata = first+second;
diff --git a/test/UTMetadataRequestFactoryTest.cc b/test/UTMetadataRequestFactoryTest.cc
index 0f422bb22..e42a7f7a5 100644
--- a/test/UTMetadataRequestFactoryTest.cc
+++ b/test/UTMetadataRequestFactoryTest.cc
@@ -38,7 +38,7 @@ public:
       } else {
         size_t index = missingIndexes.front();
         missingIndexes.pop_front();
-        return std::shared_ptr<Piece>(new Piece(index, 0));
+        return std::make_shared<Piece>(index, 0);
       }
     }
   };
@@ -50,29 +50,26 @@ CPPUNIT_TEST_SUITE_REGISTRATION(UTMetadataRequestFactoryTest);
 void UTMetadataRequestFactoryTest::testCreate()
 {
   UTMetadataRequestFactory factory;
-  std::shared_ptr<DownloadContext> dctx
-    (new DownloadContext(METADATA_PIECE_SIZE, METADATA_PIECE_SIZE*2));
-  factory.setDownloadContext(dctx);
-  std::shared_ptr<MockPieceStorage2> ps(new MockPieceStorage2());
-  ps->missingIndexes.push_back(0);
-  ps->missingIndexes.push_back(1);
-  std::shared_ptr<WrapExtBtMessageFactory> messageFactory
-    (new WrapExtBtMessageFactory());
-  factory.setBtMessageFactory(messageFactory.get());
-  std::shared_ptr<Peer> peer(new Peer("peer", 6880));
+  DownloadContext dctx{METADATA_PIECE_SIZE, METADATA_PIECE_SIZE*2};
+  factory.setDownloadContext(&dctx);
+  MockPieceStorage2 ps;
+  ps.missingIndexes.push_back(0);
+  ps.missingIndexes.push_back(1);
+  WrapExtBtMessageFactory messageFactory;
+  factory.setBtMessageFactory(&messageFactory);
+  auto peer = std::make_shared<Peer>("peer", 6880);
   peer->allocateSessionResource(0, 0);
   factory.setPeer(peer);
-  std::shared_ptr<UTMetadataRequestTracker> tracker
-    (new UTMetadataRequestTracker());
-  factory.setUTMetadataRequestTracker(tracker.get());
+  UTMetadataRequestTracker tracker;
+  factory.setUTMetadataRequestTracker(&tracker);
 
-  auto msgs = factory.create(1, ps);
+  auto msgs = factory.create(1, &ps);
   CPPUNIT_ASSERT_EQUAL((size_t)1, msgs.size());
 
-  msgs = factory.create(1, ps);
+  msgs = factory.create(1, &ps);
   CPPUNIT_ASSERT_EQUAL((size_t)1, msgs.size());
 
-  msgs = factory.create(1, ps);
+  msgs = factory.create(1, &ps);
   CPPUNIT_ASSERT_EQUAL((size_t)0, msgs.size());
 }
 
diff --git a/test/UTPexExtensionMessageTest.cc b/test/UTPexExtensionMessageTest.cc
index c153e6871..3d77903bf 100644
--- a/test/UTPexExtensionMessageTest.cc
+++ b/test/UTPexExtensionMessageTest.cc
@@ -31,11 +31,11 @@ class UTPexExtensionMessageTest:public CppUnit::TestFixture {
   CPPUNIT_TEST(testDroppedPeersAreFull);
   CPPUNIT_TEST_SUITE_END();
 private:
-  std::shared_ptr<MockPeerStorage> peerStorage_;
+  std::unique_ptr<MockPeerStorage> peerStorage_;
 public:
   void setUp()
   {
-    peerStorage_.reset(new MockPeerStorage());
+    peerStorage_ = make_unique<MockPeerStorage>();
     global::wallclock().reset();
   }
 
@@ -70,23 +70,23 @@ void UTPexExtensionMessageTest::testGetExtensionName()
 void UTPexExtensionMessageTest::testGetBencodedData()
 {
   UTPexExtensionMessage msg(1);
-  std::shared_ptr<Peer> p1(new Peer("192.168.0.1", 6881));
+  auto p1 = std::make_shared<Peer>("192.168.0.1", 6881);
   p1->allocateSessionResource(256*1024, 1024*1024);
   p1->setAllBitfield();
   CPPUNIT_ASSERT(msg.addFreshPeer(p1));// added seeder, check add.f flag
-  std::shared_ptr<Peer> p2(new Peer("10.1.1.2", 9999));
+  auto p2 = std::make_shared<Peer>("10.1.1.2", 9999);
   CPPUNIT_ASSERT(msg.addFreshPeer(p2));
-  std::shared_ptr<Peer> p3(new Peer("192.168.0.2", 6882));
+  auto p3 = std::make_shared<Peer>("192.168.0.2", 6882);
   p3->startDrop();
   CPPUNIT_ASSERT(msg.addDroppedPeer(p3));
-  std::shared_ptr<Peer> p4(new Peer("10.1.1.3", 10000));
+  auto p4 = std::make_shared<Peer>("10.1.1.3", 10000);
   p4->startDrop();
   CPPUNIT_ASSERT(msg.addDroppedPeer(p4));
 
-  std::shared_ptr<Peer> p5(new Peer("1002:1035:4527:3546:7854:1237:3247:3217",
-                                 6881));
+  auto p5 = std::make_shared<Peer>("1002:1035:4527:3546:7854:1237:3247:3217",
+                                   6881);
   CPPUNIT_ASSERT(msg.addFreshPeer(p5));
-  std::shared_ptr<Peer> p6(new Peer("2001:db8:bd05:1d2:288a:1fc0:1:10ee", 6882));
+  auto p6 = std::make_shared<Peer>("2001:db8:bd05:1d2:288a:1fc0:1:10ee", 6882);
   p6->startDrop();
   CPPUNIT_ASSERT(msg.addDroppedPeer(p6));
 
@@ -150,7 +150,7 @@ void UTPexExtensionMessageTest::testDoReceivedAction()
   std::shared_ptr<Peer> p4(new Peer("2001:db8:bd05:1d2:288a:1fc0:1:10ee", 10000));
   p4->startDrop();
   msg.addDroppedPeer(p4);
-  msg.setPeerStorage(peerStorage_);
+  msg.setPeerStorage(peerStorage_.get());
 
   msg.doReceivedAction();
 
@@ -203,9 +203,8 @@ void UTPexExtensionMessageTest::testCreate()
     "8:dropped618:"+std::string(&c6[0], &c6[COMPACT_LEN_IPV6])+
     "e";
 
-  std::shared_ptr<UTPexExtensionMessage> msg
-    (UTPexExtensionMessage::create
-     (reinterpret_cast<const unsigned char*>(data.c_str()), data.size()));
+  auto msg = UTPexExtensionMessage::create
+    (reinterpret_cast<const unsigned char*>(data.c_str()), data.size());
   CPPUNIT_ASSERT_EQUAL((uint8_t)1, msg->getExtensionMessageID());
   CPPUNIT_ASSERT_EQUAL((size_t)3, msg->getFreshPeers().size());
   CPPUNIT_ASSERT_EQUAL(std::string("192.168.0.1"),
diff --git a/test/extension_message_test_helper.h b/test/extension_message_test_helper.h
index c0d432f14..5c2480b54 100644
--- a/test/extension_message_test_helper.h
+++ b/test/extension_message_test_helper.h
@@ -8,10 +8,10 @@ namespace aria2 {
 class WrapExtBtMessageFactory:public MockBtMessageFactory {
 public:
   virtual std::unique_ptr<BtExtendedMessage>
-  createBtExtendedMessage(const std::shared_ptr<ExtensionMessage>& extmsg)
+  createBtExtendedMessage(std::unique_ptr<ExtensionMessage> extmsg)
     override
   {
-    return make_unique<BtExtendedMessage>(extmsg);
+    return make_unique<BtExtendedMessage>(std::move(extmsg));
   }
 };