i2pd/NetDb.cpp

#include "I2PEndian.h"
#include <fstream>
#include <vector>
#include <boost/asio.hpp>
#include <cryptopp/gzip.h>
#include "base64.h"
#include "Log.h"
#include "Timestamp.h"
#include "I2NPProtocol.h"
#include "Tunnel.h"
#include "Transports.h"
#include "RouterContext.h"
#include "Garlic.h"
#include "NetDb.h"
#include "Reseed.h"
#include "util.h"

using namespace i2p::transport;

namespace i2p
{
namespace data
{		
	I2NPMessage * RequestedDestination::CreateRequestMessage (std::shared_ptr<const RouterInfo> router,
		const i2p::tunnel::InboundTunnel * replyTunnel)
	{
		I2NPMessage * msg = i2p::CreateDatabaseLookupMsg (m_Destination, 
			replyTunnel->GetNextIdentHash (), replyTunnel->GetNextTunnelID (), m_IsExploratory, 
		    &m_ExcludedPeers, m_IsLeaseSet, m_Pool);
		if (m_IsLeaseSet) // wrap lookup message into garlic
		{
			if (m_Pool && m_Pool->GetLocalDestination ())
				msg = m_Pool->GetLocalDestination ()->WrapMessage (*router, msg);
			else
				LogPrint ("Can't create garlic message without destination");
		}	
		m_ExcludedPeers.insert (router->GetIdentHash ());
		m_LastRouter = router;
		m_CreationTime = i2p::util::GetSecondsSinceEpoch ();
		return msg;
	}	

	I2NPMessage * RequestedDestination::CreateRequestMessage (const IdentHash& floodfill)
	{
		I2NPMessage * msg = i2p::CreateDatabaseLookupMsg (m_Destination, 
			i2p::context.GetRouterInfo ().GetIdentHash () , 0, false, &m_ExcludedPeers);
		m_ExcludedPeers.insert (floodfill);
		m_LastRouter = nullptr;
		m_CreationTime = i2p::util::GetSecondsSinceEpoch ();
		return msg;
	}	

	void RequestedDestination::ClearExcludedPeers ()
	{
		m_ExcludedPeers.clear ();
	}	
	
#ifndef _WIN32		
	const char NetDb::m_NetDbPath[] = "/netDb";
#else
	const char NetDb::m_NetDbPath[] = "\\netDb";
#endif			
	NetDb netdb;

	NetDb::NetDb (): m_IsRunning (false), m_Thread (0)
	{
	}
	
	NetDb::~NetDb ()
	{
		Stop ();	
		for (auto l:m_LeaseSets)
			delete l.second;
		for (auto r:m_RequestedDestinations)
			delete r.second;
	}	

	void NetDb::Start ()
	{	
		Load (m_NetDbPath);
		if (m_RouterInfos.size () < 100) // reseed if # of router less than 100
		{	
			Reseeder reseeder;
			reseeder.LoadCertificates (); // we need certificates for SU3 verification

			// try SU3 first
			int reseedRetries = 0;
			while (m_RouterInfos.size () < 100 && reseedRetries < 10)
			{	
				reseeder.ReseedNowSU3();
				reseedRetries++;
			}	

			// if still not enough download .dat files
			reseedRetries = 0;
			while (m_RouterInfos.size () < 100 && reseedRetries < 10)
			{
				reseeder.reseedNow();
				reseedRetries++;
				Load (m_NetDbPath);
			}
		}	
		m_Thread = new std::thread (std::bind (&NetDb::Run, this));
	}
	
	void NetDb::Stop ()
	{
		if (m_Thread)
		{	
			m_IsRunning = false;
			m_Queue.WakeUp ();
			m_Thread->join (); 
			delete m_Thread;
			m_Thread = 0;
		}	
	}	
	
	void NetDb::Run ()
	{
		uint32_t lastSave = 0, lastPublish = 0;
		m_IsRunning = true;
		while (m_IsRunning)
		{	
			try
			{	
				I2NPMessage * msg = m_Queue.GetNextWithTimeout (15000); // 15 sec
				if (msg)
				{	
					while (msg)
					{
						switch (msg->GetHeader ()->typeID) 
						{
							case eI2NPDatabaseStore:	
								LogPrint ("DatabaseStore");
								HandleDatabaseStoreMsg (msg);
							break;
							case eI2NPDatabaseSearchReply:
								LogPrint ("DatabaseSearchReply");
								HandleDatabaseSearchReplyMsg (msg);
							break;
							case eI2NPDatabaseLookup:
								LogPrint ("DatabaseLookup");
								HandleDatabaseLookupMsg (msg);
							break;	
							default: // WTF?
								LogPrint ("NetDb: unexpected message type ", msg->GetHeader ()->typeID);
								i2p::HandleI2NPMessage (msg);
						}	
						msg = m_Queue.Get ();
					}	
				}
				else 				
				{
					if (!m_IsRunning) break;
					// if no new DatabaseStore coming, explore it
					auto numRouters = m_RouterInfos.size ();
					Explore (numRouters < 1500 ? 5 : 1);
				}	

				uint64_t ts = i2p::util::GetSecondsSinceEpoch ();
				if (ts - lastSave >= 60) // save routers, manage leasesets and validate subscriptions every minute
				{
					if (lastSave)
					{
						SaveUpdated (m_NetDbPath);
						ManageLeaseSets ();
					}	
					lastSave = ts;
				}	
				if (ts - lastPublish >= 600) // publish every 10 minutes
				{
					Publish ();
					lastPublish = ts;
				}	
			}
			catch (std::exception& ex)
			{
				LogPrint ("NetDb: ", ex.what ());
			}	
		}	
	}	
	
	void NetDb::AddRouterInfo (const uint8_t * buf, int len)
	{
		IdentityEx identity;
		if (identity.FromBuffer (buf, len))
			AddRouterInfo (identity.GetIdentHash (), buf, len);	
	}

	void NetDb::AddRouterInfo (const IdentHash& ident, const uint8_t * buf, int len)
	{	
		DeleteRequestedDestination (ident);	
		auto r = FindRouter (ident);
		if (r)
		{
			auto ts = r->GetTimestamp ();
			r->Update (buf, len);
			if (r->GetTimestamp () > ts)
				LogPrint ("RouterInfo updated");
		}	
		else	
		{	
			LogPrint ("New RouterInfo added");
			auto newRouter = std::make_shared<RouterInfo> (buf, len);
			{
				std::unique_lock<std::mutex> l(m_RouterInfosMutex);
				m_RouterInfos[newRouter->GetIdentHash ()] = newRouter;
			}
			if (newRouter->IsFloodfill ())
			{
				std::unique_lock<std::mutex> l(m_FloodfillsMutex);
				m_Floodfills.push_back (newRouter);
			}	
		}	
	}	

	void NetDb::AddLeaseSet (const IdentHash& ident, const uint8_t * buf, int len,
		i2p::tunnel::InboundTunnel * from)
	{
		DeleteRequestedDestination (ident);
		if (!from) // unsolicited LS must be received directly
		{	
			auto it = m_LeaseSets.find(ident);
			if (it != m_LeaseSets.end ())
			{
				it->second->Update (buf, len); 
				LogPrint ("LeaseSet updated");
			}
			else
			{	
				LogPrint ("New LeaseSet added");
				m_LeaseSets[ident] = new LeaseSet (buf, len);
			}	
		}	
	}	

	std::shared_ptr<RouterInfo> NetDb::FindRouter (const IdentHash& ident) const
	{
		std::unique_lock<std::mutex> l(m_RouterInfosMutex);
		auto it = m_RouterInfos.find (ident);
		if (it != m_RouterInfos.end ())
			return it->second;
		else
			return nullptr;
	}

	LeaseSet * NetDb::FindLeaseSet (const IdentHash& destination) const
	{
		auto it = m_LeaseSets.find (destination);
		if (it != m_LeaseSets.end ())
			return it->second;
		else
			return nullptr;
	}

	void NetDb::SetUnreachable (const IdentHash& ident, bool unreachable)
	{
		auto it = m_RouterInfos.find (ident);
		if (it != m_RouterInfos.end ())
			return it->second->SetUnreachable (unreachable);
	}

	// TODO: Move to reseed and/or scheduled tasks. (In java version, scheduler fix this as well as sort RIs.)
	bool NetDb::CreateNetDb(boost::filesystem::path directory)
	{
		LogPrint (directory.string(), " doesn't exist, trying to create it.");
		if (!boost::filesystem::create_directory (directory))
		{
			LogPrint("Failed to create directory ", directory.string());
			return false;
		}

		// list of chars might appear in base64 string
		const char * chars = GetBase64SubstitutionTable (); // 64 bytes
		boost::filesystem::path suffix;
		for (int i = 0; i < 64; i++)
		{
#ifndef _WIN32
			suffix = std::string ("/r") + chars[i];
#else
			suffix = std::string ("\\r") + chars[i];
#endif
			if (!boost::filesystem::create_directory( boost::filesystem::path (directory / suffix) )) return false;
		}
		return true;
	}

	void NetDb::Load (const char * directory)
	{
		boost::filesystem::path p (i2p::util::filesystem::GetDataDir());
		p /= (directory);
		if (!boost::filesystem::exists (p))
		{
			// seems netDb doesn't exist yet
			if (!CreateNetDb(p)) return;
		}
		// make sure we cleanup netDb from previous attempts
		m_RouterInfos.clear ();	
		m_Floodfills.clear ();	

		// load routers now
		uint64_t ts = i2p::util::GetMillisecondsSinceEpoch ();	
		int numRouters = 0;
		boost::filesystem::directory_iterator end;
		for (boost::filesystem::directory_iterator it (p); it != end; ++it)
		{
			if (boost::filesystem::is_directory (it->status()))
			{
				for (boost::filesystem::directory_iterator it1 (it->path ()); it1 != end; ++it1)
				{
#if BOOST_VERSION > 10500
					const std::string& fullPath = it1->path().string();
#else
					const std::string& fullPath = it1->path();
#endif
					auto r = std::make_shared<RouterInfo>(fullPath);
					if (!r->IsUnreachable () && (!r->UsesIntroducer () || ts < r->GetTimestamp () + 3600*1000LL)) // 1 hour
					{	
						r->DeleteBuffer ();
						m_RouterInfos[r->GetIdentHash ()] = r;
						if (r->IsFloodfill ())
							m_Floodfills.push_back (r);
						numRouters++;
					}	
					else
					{	
						if (boost::filesystem::exists (fullPath))  
							boost::filesystem::remove (fullPath);
					}	
				}	
			}	
		}
		LogPrint (numRouters, " routers loaded");
		LogPrint (m_Floodfills.size (), " floodfills loaded");	
	}	

	void NetDb::SaveUpdated (const char * directory)
	{	
		auto GetFilePath = [](const char * directory, const RouterInfo * routerInfo)
		{
#ifndef _WIN32
			return std::string (directory) + "/r" +
				routerInfo->GetIdentHashBase64 ()[0] + "/routerInfo-" +
#else
			return std::string (directory) + "\\r" +
				routerInfo->GetIdentHashBase64 ()[0] + "\\routerInfo-" +
#endif
				routerInfo->GetIdentHashBase64 () + ".dat";
		};	

		boost::filesystem::path p (i2p::util::filesystem::GetDataDir());
		p /= (directory);
#if BOOST_VERSION > 10500		
		const char * fullDirectory = p.string().c_str ();
#else
		const char * fullDirectory = p.c_str ();
#endif		
		int count = 0, deletedCount = 0;
		auto total = m_RouterInfos.size ();
		uint64_t ts = i2p::util::GetMillisecondsSinceEpoch ();
		for (auto it: m_RouterInfos)
		{	
			if (it.second->IsUpdated ())
			{
				it.second->SaveToFile (GetFilePath(fullDirectory, it.second.get ()));
				it.second->SetUpdated (false);
				it.second->DeleteBuffer ();
				count++;
			}
			else 
			{
				// RouterInfo expires after 1 hour if uses introducer
				if ((it.second->UsesIntroducer () && ts > it.second->GetTimestamp () + 3600*1000LL) // 1 hour
				// RouterInfo expires in 72 hours if more than 300
					|| (total > 300 && ts > it.second->GetTimestamp () + 3*24*3600*1000LL)) // 3 days
				{	
					total--;
					it.second->SetUnreachable (true);
				}	
				
				if (it.second->IsUnreachable ())
				{	
					// delete RI file
					if (boost::filesystem::exists (GetFilePath (fullDirectory, it.second.get ())))
					{    
						boost::filesystem::remove (GetFilePath (fullDirectory, it.second.get ()));
						deletedCount++;
					}	
					// delete from floodfills list
					if (it.second->IsFloodfill ())
					{
						std::unique_lock<std::mutex> l(m_FloodfillsMutex);
						m_Floodfills.remove (it.second);
					}
				}
			}	
		}	
		if (count > 0)
			LogPrint (count," new/updated routers saved");
		if (deletedCount > 0)
		{
			LogPrint (deletedCount," routers deleted");
			// clean up RouterInfos table
			std::unique_lock<std::mutex> l(m_RouterInfosMutex);
			for (auto it = m_RouterInfos.begin (); it != m_RouterInfos.end ();)
			{
				if (it->second->IsUnreachable ())
					it = m_RouterInfos.erase (it);
				else
					it++;
			}
		}
	}

	void NetDb::RequestDestination (const IdentHash& destination, bool isLeaseSet, i2p::tunnel::TunnelPool * pool)
	{
		if (isLeaseSet) // we request LeaseSet through tunnels
		{	
			i2p::tunnel::OutboundTunnel * outbound = pool ? pool->GetNextOutboundTunnel () : i2p::tunnel::tunnels.GetNextOutboundTunnel ();
			if (outbound)
			{
				i2p::tunnel::InboundTunnel * inbound = pool ? pool->GetNextInboundTunnel () :i2p::tunnel::tunnels.GetNextInboundTunnel ();
				if (inbound)
				{
					RequestedDestination * dest = CreateRequestedDestination (destination, true, false, pool);
					auto floodfill = GetClosestFloodfill (destination, dest->GetExcludedPeers ());
					if (floodfill)
					{		
						// DatabaseLookup message
						outbound->SendTunnelDataMsg (
						    {
								i2p::tunnel::TunnelMessageBlock 
								{ 
									i2p::tunnel::eDeliveryTypeRouter,
									floodfill->GetIdentHash (), 0,
									dest->CreateRequestMessage (floodfill, inbound)
								}
							});	
					}	
					else
						LogPrint ("No more floodfills found");
				}	
				else
					LogPrint ("No inbound tunnels found");	
			}
			else
				LogPrint ("No outbound tunnels found");
		}	
		else // RouterInfo is requested directly
		{
			RequestedDestination * dest = CreateRequestedDestination (destination, false, false, pool);
			auto floodfill = GetClosestFloodfill (destination, dest->GetExcludedPeers ());
			if (floodfill)
				transports.SendMessage (floodfill->GetIdentHash (), dest->CreateRequestMessage (floodfill->GetIdentHash ()));
		}	
	}	
	
	void NetDb::HandleDatabaseStoreMsg (I2NPMessage * m)
	{	
		const uint8_t * buf = m->GetPayload ();
		size_t len = be16toh (m->GetHeader ()->size);		
		I2NPDatabaseStoreMsg * msg = (I2NPDatabaseStoreMsg *)buf;
		size_t offset = sizeof (I2NPDatabaseStoreMsg);
		if (msg->replyToken)
			offset += 36;
		if (msg->type)
		{
			LogPrint ("LeaseSet");
			AddLeaseSet (msg->key, buf + offset, len - offset, m->from);
		}	
		else
		{
			LogPrint ("RouterInfo");
			size_t size = be16toh (*(uint16_t *)(buf + offset));
			if (size > 2048)
			{
				LogPrint ("Invalid RouterInfo length ", (int)size);
				return;
			}	
			offset += 2;
			CryptoPP::Gunzip decompressor;
			decompressor.Put (buf + offset, size);
			decompressor.MessageEnd();
			uint8_t uncompressed[2048];
			size_t uncomressedSize = decompressor.MaxRetrievable ();
			decompressor.Get (uncompressed, uncomressedSize);
			AddRouterInfo (msg->key, uncompressed, uncomressedSize);
		}	
		i2p::DeleteI2NPMessage (m);
	}	

	void NetDb::HandleDatabaseSearchReplyMsg (I2NPMessage * msg)
	{
		uint8_t * buf = msg->GetPayload ();
		char key[48];
		int l = i2p::data::ByteStreamToBase64 (buf, 32, key, 48);
		key[l] = 0;
		int num = buf[32]; // num
		LogPrint ("DatabaseSearchReply for ", key, " num=", num);
		auto it = m_RequestedDestinations.find (IdentHash (buf));
		if (it != m_RequestedDestinations.end ())
		{	
			RequestedDestination * dest = it->second;
			bool deleteDest = true;
			if (num > 0)
			{	
				auto pool = dest ? dest->GetTunnelPool () : nullptr;
				auto outbound = pool ? pool->GetNextOutboundTunnel () : i2p::tunnel::tunnels.GetNextOutboundTunnel ();
				auto inbound = pool ? pool->GetNextInboundTunnel () : i2p::tunnel::tunnels.GetNextInboundTunnel ();
				std::vector<i2p::tunnel::TunnelMessageBlock> msgs;
				if (!dest->IsExploratory ())
				{
					// reply to our destination. Try other floodfills
					if (outbound && inbound )
					{
						auto count = dest->GetExcludedPeers ().size ();
						if (count < 7)
						{	
							auto nextFloodfill = GetClosestFloodfill (dest->GetDestination (), dest->GetExcludedPeers ());
							if (nextFloodfill)
							{
								if (!dest->IsLeaseSet ())
								{	
									// tell floodfill about us 
									msgs.push_back (i2p::tunnel::TunnelMessageBlock 
										{ 
											i2p::tunnel::eDeliveryTypeRouter,
											nextFloodfill->GetIdentHash (), 0,
											CreateDatabaseStoreMsg () 
										});  
								}	
								
								// request destination
								LogPrint ("Try ", key, " at ", count, " floodfill ", nextFloodfill->GetIdentHash ().ToBase64 ()); 
								auto msg = dest->CreateRequestMessage (nextFloodfill, inbound);
								msgs.push_back (i2p::tunnel::TunnelMessageBlock 
									{ 
										i2p::tunnel::eDeliveryTypeRouter,
										nextFloodfill->GetIdentHash (), 0, msg
									});
								deleteDest = false;
							}	
						}
						else
							LogPrint (key, " was not found on 7 floodfills");
					}	
				}	
				
				for (int i = 0; i < num; i++)
				{
					uint8_t * router = buf + 33 + i*32;
					char peerHash[48];
					int l1 = i2p::data::ByteStreamToBase64 (router, 32, peerHash, 48);
					peerHash[l1] = 0;
					LogPrint (i,": ", peerHash);

					if (dest->IsExploratory ())
					{	
						auto r = FindRouter (router); 
						if (!r || i2p::util::GetMillisecondsSinceEpoch () > r->GetTimestamp () + 3600*1000LL) 
						{	
							// router with ident not found or too old (1 hour)
							LogPrint ("Found new/outdated router. Requesting RouterInfo ...");
							if (outbound && inbound && dest->GetLastRouter ())
							{
								RequestedDestination * d1 = CreateRequestedDestination (router, false, false, pool);
								auto msg = d1->CreateRequestMessage (dest->GetLastRouter (), inbound);
								msgs.push_back (i2p::tunnel::TunnelMessageBlock 
									{ 
										i2p::tunnel::eDeliveryTypeRouter,
										dest->GetLastRouter ()->GetIdentHash (), 0, msg
									});
							}	
							else
								RequestDestination (router, false, pool);
						}
						else
							LogPrint ("Bayan");
					}	
					else
					{		
						auto r = FindRouter (router); 
						// do we have that floodfill router in our database?
						if (!r) 
						{	
							// request router
							LogPrint ("Found new floodfill. Request it");
							RequestDestination (router, false, pool);
						}	
					}						
				}
				
				if (outbound && msgs.size () > 0)
					outbound->SendTunnelDataMsg (msgs);	
				if (deleteDest)
				{
					// no more requests for the destinationation. delete it
					delete it->second;
					m_RequestedDestinations.erase (it);
				}	
			}
			else
			{
				// no more requests for detination possible. delete it
				delete it->second;
				m_RequestedDestinations.erase (it);
			}	
		}
		else
		{	
			LogPrint ("Requested destination for ", key, " not found");
			// it might contain new routers
			for (int i = 0; i < num; i++)
			{
				IdentHash router (buf + 33 + i*32);
				if (!FindRouter (router))
				{	
					LogPrint ("New router ", router.ToBase64 (), " found. Request it");
					RequestDestination (router);
				}	
			}	
		}	
		i2p::DeleteI2NPMessage (msg);
	}	
	
	void NetDb::HandleDatabaseLookupMsg (I2NPMessage * msg)
	{
		uint8_t * buf = msg->GetPayload ();
		char key[48];
		int l = i2p::data::ByteStreamToBase64 (buf, 32, key, 48);
		key[l] = 0;
		LogPrint ("DatabaseLookup for ", key, " recieved");
		uint8_t flag = buf[64];
		uint8_t * excluded = buf + 65;		
		uint32_t replyTunnelID = 0;
		if (flag & 0x01) //reply to tunnel
		{
			replyTunnelID = be32toh (*(uint32_t *)(buf + 64));
			excluded += 4;
		}
		uint16_t numExcluded = be16toh (*(uint16_t *)excluded);	
		excluded += 2;
		if (numExcluded > 512)
		{
			LogPrint ("Number of excluded peers", numExcluded, " exceeds 512");
			numExcluded = 0; // TODO:
		} 

		I2NPMessage * replyMsg = nullptr;

		{
			auto router = FindRouter (buf);
			if (router)
			{
				LogPrint ("Requested RouterInfo ", key, " found");
				router->LoadBuffer ();
				if (router->GetBuffer ()) 
					replyMsg = CreateDatabaseStoreMsg (router.get ());
			}
		}
		if (!replyMsg)
		{
			auto leaseSet = FindLeaseSet (buf);
			if (leaseSet) // we don't send back our LeaseSets
			{
				LogPrint ("Requested LeaseSet ", key, " found");
				replyMsg = CreateDatabaseStoreMsg (leaseSet);
			}
		}
		if (!replyMsg)
		{
			LogPrint ("Requested ", key, " not found. ", numExcluded, " excluded");
			std::set<IdentHash> excludedRouters;
			for (int i = 0; i < numExcluded; i++)
			{
				// TODO: check for all zeroes (exploratory)
				excludedRouters.insert (excluded);
				excluded += 32;
			}	
			replyMsg = CreateDatabaseSearchReply (buf, GetClosestFloodfill (buf, excludedRouters).get ());
		}
		else
			excluded += numExcluded*32; // we don't care about exluded	

		if (replyMsg)
		{	
			if (replyTunnelID)
			{
				// encryption might be used though tunnel only
				if (flag & 0x02) // encrypted reply requested
				{
					uint8_t * sessionKey = excluded;
					uint8_t numTags = sessionKey[32];
					if (numTags > 0) 
					{
						uint8_t * sessionTag = sessionKey + 33; // take first tag
						i2p::garlic::GarlicRoutingSession garlic (sessionKey, sessionTag);
						replyMsg = garlic.WrapSingleMessage (replyMsg);
					}
				}	
				auto exploratoryPool = i2p::tunnel::tunnels.GetExploratoryPool ();
				auto outbound = exploratoryPool ? exploratoryPool->GetNextOutboundTunnel () : nullptr;
				if (outbound)
					outbound->SendTunnelDataMsg (buf+32, replyTunnelID, replyMsg);
				else
					transports.SendMessage (buf+32, i2p::CreateTunnelGatewayMsg (replyTunnelID, replyMsg));
			}
			else
				transports.SendMessage (buf+32, replyMsg);
		}
		i2p::DeleteI2NPMessage (msg);
	}	

	void NetDb::Explore (int numDestinations)
	{	
		// clean up previous exploratories
		uint64_t ts = i2p::util::GetSecondsSinceEpoch ();	
		for (auto it = m_RequestedDestinations.begin (); it != m_RequestedDestinations.end ();)
		{
			if (it->second->IsExploratory () || ts > it->second->GetCreationTime () + 60) // no response for 1 minute
			{
				delete it->second;
				it = m_RequestedDestinations.erase (it);
			}
			else
				it++;
		}	
		// new requests
		auto exploratoryPool = i2p::tunnel::tunnels.GetExploratoryPool ();
		auto outbound = exploratoryPool ? exploratoryPool->GetNextOutboundTunnel () : i2p::tunnel::tunnels.GetNextOutboundTunnel ();
		auto inbound = exploratoryPool ? exploratoryPool->GetNextInboundTunnel () : i2p::tunnel::tunnels.GetNextInboundTunnel ();
		bool throughTunnels = outbound && inbound;
		
		CryptoPP::RandomNumberGenerator& rnd = i2p::context.GetRandomNumberGenerator ();
		uint8_t randomHash[32];
		std::vector<i2p::tunnel::TunnelMessageBlock> msgs;
		std::set<const RouterInfo *> floodfills;
		LogPrint ("Exploring new ", numDestinations, " routers ...");
		for (int i = 0; i < numDestinations; i++)
		{	
			rnd.GenerateBlock (randomHash, 32);
			RequestedDestination * dest = CreateRequestedDestination (IdentHash (randomHash), false, true, exploratoryPool);
			auto floodfill = GetClosestFloodfill (randomHash, dest->GetExcludedPeers ());
			if (floodfill && !floodfills.count (floodfill.get ())) // request floodfill only once
			{	
				floodfills.insert (floodfill.get ());
				if (throughTunnels)
				{	
					msgs.push_back (i2p::tunnel::TunnelMessageBlock 
						{ 
							i2p::tunnel::eDeliveryTypeRouter,
							floodfill->GetIdentHash (), 0,
							CreateDatabaseStoreMsg () // tell floodfill about us 
						});  
					msgs.push_back (i2p::tunnel::TunnelMessageBlock 
						{ 
							i2p::tunnel::eDeliveryTypeRouter,
							floodfill->GetIdentHash (), 0, 
							dest->CreateRequestMessage (floodfill, inbound) // explore
						}); 
				}	
				else
					i2p::transport::transports.SendMessage (floodfill->GetIdentHash (), dest->CreateRequestMessage (floodfill->GetIdentHash ()));
			}	
			else
				DeleteRequestedDestination (dest);
		}	
		if (throughTunnels && msgs.size () > 0)
			outbound->SendTunnelDataMsg (msgs);		
	}	

	void NetDb::Publish ()
	{
		std::set<IdentHash> excluded; // TODO: fill up later
		for (int i = 0; i < 3; i++)
		{	
			auto floodfill = GetClosestFloodfill (i2p::context.GetRouterInfo ().GetIdentHash (), excluded);
			if (floodfill)
			{
				LogPrint ("Publishing our RouterInfo to ", floodfill->GetIdentHashAbbreviation ());
				transports.SendMessage (floodfill->GetIdentHash (), CreateDatabaseStoreMsg ());	
				excluded.insert (floodfill->GetIdentHash ());
			}
		}	
	}	
	
	RequestedDestination * NetDb::CreateRequestedDestination (const IdentHash& dest,
		bool isLeaseSet, bool isExploratory, i2p::tunnel::TunnelPool * pool)
	{
		std::unique_lock<std::mutex> l(m_RequestedDestinationsMutex);
		auto it = m_RequestedDestinations.find (dest);
		if (it == m_RequestedDestinations.end ()) // not exist yet
		{
			RequestedDestination * d = new RequestedDestination (dest, isLeaseSet, isExploratory, pool);
			m_RequestedDestinations[dest] = d;
			return d;
		}	
		else
			return it->second;
	}
	
	bool NetDb::DeleteRequestedDestination (const IdentHash& dest)
	{
		auto it = m_RequestedDestinations.find (dest);
		if (it != m_RequestedDestinations.end ())
		{	
			std::unique_lock<std::mutex> l(m_RequestedDestinationsMutex);
			delete it->second;
			m_RequestedDestinations.erase (it);
			return true;
		}	
		return false;
	}	

	void NetDb::DeleteRequestedDestination (RequestedDestination * dest)
	{
		if (dest)
		{
			std::unique_lock<std::mutex> l(m_RequestedDestinationsMutex);
			m_RequestedDestinations.erase (dest->GetDestination ());
			delete dest;
		}	
	}	

	std::shared_ptr<const RouterInfo> NetDb::GetRandomRouter () const
	{
		return GetRandomRouter (
			[](std::shared_ptr<const RouterInfo> router)->bool 
			{ 
				return !router->IsHidden (); 
			});
	}	
	
	std::shared_ptr<const RouterInfo> NetDb::GetRandomRouter (std::shared_ptr<const RouterInfo> compatibleWith) const
	{
		return GetRandomRouter (
			[compatibleWith](std::shared_ptr<const RouterInfo> router)->bool 
			{ 
				return !router->IsHidden () && router != compatibleWith && 
					router->IsCompatible (*compatibleWith); 
			});
	}	

	std::shared_ptr<const RouterInfo> NetDb::GetHighBandwidthRandomRouter (std::shared_ptr<const RouterInfo> compatibleWith) const
	{
		return GetRandomRouter (
			[compatibleWith](std::shared_ptr<const RouterInfo> router)->bool 
			{ 
				return !router->IsHidden () && router != compatibleWith &&
					router->IsCompatible (*compatibleWith) && (router->GetCaps () & RouterInfo::eHighBandwidth); 
			});
	}	
	
	template<typename Filter>
	std::shared_ptr<const RouterInfo> NetDb::GetRandomRouter (Filter filter) const
	{
		CryptoPP::RandomNumberGenerator& rnd = i2p::context.GetRandomNumberGenerator ();
		uint32_t ind = rnd.GenerateWord32 (0, m_RouterInfos.size () - 1);	
		for (int j = 0; j < 2; j++)
		{	
			uint32_t i = 0;
			std::unique_lock<std::mutex> l(m_RouterInfosMutex);
			for (auto it: m_RouterInfos)
			{	
				if (i >= ind)
				{	
					if (!it.second->IsUnreachable () && filter (it.second))
						return it.second;
				}	
				else 
					i++;
			}
			// we couldn't find anything, try second pass
			ind = 0;
		}	
		return nullptr; // seems we have too few routers
	}	
	
	void NetDb::PostI2NPMsg (I2NPMessage * msg)
	{
		if (msg) m_Queue.Put (msg);	
	}	

	std::shared_ptr<const RouterInfo> NetDb::GetClosestFloodfill (const IdentHash& destination, 
		const std::set<IdentHash>& excluded) const
	{
		std::shared_ptr<const RouterInfo> r;
		XORMetric minMetric;
		IdentHash destKey = CreateRoutingKey (destination);
		minMetric.SetMax ();
		std::unique_lock<std::mutex> l(m_FloodfillsMutex);
		for (auto it: m_Floodfills)
		{	
			if (!it->IsUnreachable () && !excluded.count (it->GetIdentHash ()))
			{	
				XORMetric m = destKey ^ it->GetIdentHash ();
				if (m < minMetric)
				{
					minMetric = m;
					r = it;
				}
			}	
		}	
		return r;
	}	

	void NetDb::ManageLeaseSets ()
	{
		for (auto it = m_LeaseSets.begin (); it != m_LeaseSets.end ();)
		{
			if (it->second->HasNonExpiredLeases ()) // all leases expired
			{
				LogPrint ("LeaseSet ", it->second->GetIdentHash ().ToBase64 (), " expired");
				delete it->second;
				it = m_LeaseSets.erase (it);
			}	
			else 
				it++;
		}
	}
}
}