i2pd/Tunnel.cpp

#include <cryptopp/sha.h>
#include "RouterContext.h"
#include "Log.h"
#include "Timestamp.h"
#include "I2NPProtocol.h"
#include "Transports.h"
#include "NetDb.h"
#include "Tunnel.h"

namespace i2p
{	
namespace tunnel
{		
	
	Tunnel::Tunnel (TunnelConfig * config): m_Config (config),
		m_CreationTime (i2p::util::GetSecondsSinceEpoch ()), m_IsEstablished (false)
	{
	}	

	Tunnel::~Tunnel ()
	{
		delete m_Config;
	}	

	void Tunnel::Build (uint32_t replyMsgID, OutboundTunnel * outboundTunnel)
	{
		CryptoPP::RandomNumberGenerator& rnd = i2p::context.GetRandomNumberGenerator ();
		size_t numRecords = m_Config->GetNumHops ();
		I2NPMessage * msg = NewI2NPMessage ();
		*msg->GetPayload () = numRecords;
		msg->len += numRecords*sizeof (I2NPBuildRequestRecordElGamalEncrypted) + 1;
		
		I2NPBuildRequestRecordElGamalEncrypted * records = (I2NPBuildRequestRecordElGamalEncrypted *)(msg->GetPayload () + 1); 

		TunnelHopConfig * hop = m_Config->GetFirstHop ();
		int i = 0;
		while (hop)
		{
			EncryptBuildRequestRecord (*hop->router,
				CreateBuildRequestRecord (hop->router->GetIdentHash (), 
				    hop->tunnelID,
					hop->nextRouter->GetIdentHash (), 
					hop->nextTunnelID,
					hop->layerKey, hop->ivKey,                  
					hop->replyKey, hop->replyIV,
					hop->next ? rnd.GenerateWord32 () : replyMsgID, // we set replyMsgID for last hop only
				    hop->isGateway, hop->isEndpoint), 
		    	records[i]);
			i++;
			hop = hop->next;
		}	
		
		hop = m_Config->GetLastHop ()->prev;
		size_t ind = numRecords - 1;
		while (hop)
		{
			for (size_t i = ind; i < numRecords; i++)
			{	
				m_CBCDecryption.SetKeyWithIV (hop->replyKey, 32, hop->replyIV);
				m_CBCDecryption.ProcessData((uint8_t *)&records[i], (uint8_t *)&records[i], sizeof (I2NPBuildRequestRecordElGamalEncrypted));
			}	
			hop = hop->prev;
			ind--;
		}	
		FillI2NPMessageHeader (msg, eI2NPVariableTunnelBuild);
		
		if (outboundTunnel)
		{	
			outboundTunnel->SendTunnelDataMsg (GetNextIdentHash (), 0, msg);
			DeleteI2NPMessage (msg);
		}	
		else
		{	
			i2p::transports.SendMessage (GetNextIdentHash (), msg);
		}	
	}	
		
	bool Tunnel::HandleTunnelBuildResponse (uint8_t * msg, size_t len)
	{
		LogPrint ("TunnelBuildResponse ", (int)msg[0], " records.");

		TunnelHopConfig * hop = m_Config->GetLastHop (); 
		int num = msg[0];
		while (hop)
		{	
			for (int i = 0; i < num; i++)
			{			
				uint8_t * record = msg + 1 + i*sizeof (I2NPBuildResponseRecord);
				m_CBCDecryption.SetKeyWithIV(hop->replyKey, 32, hop->replyIV);
				m_CBCDecryption.ProcessData(record, record, sizeof (I2NPBuildResponseRecord));
			}
			hop = hop->prev;
			num--;
		}

		m_IsEstablished = true;
		for (int i = 0; i < msg[0]; i++)
		{			
			I2NPBuildResponseRecord * record = (I2NPBuildResponseRecord *)(msg + 1 + i*sizeof (I2NPBuildResponseRecord));
			LogPrint ("Ret code=", (int)record->ret);
			if (record->ret) 
				// if any of participants declined the tunnel is not established
				m_IsEstablished = false; 
		}
		return m_IsEstablished;
	}	
	
	void Tunnel::LayerDecrypt (const uint8_t * in, size_t len, const uint8_t * layerKey, 
		const uint8_t * iv, uint8_t * out)
	{
		m_CBCDecryption.SetKeyWithIV (layerKey, 32, iv); 
		m_CBCDecryption.ProcessData(out, in, len); 
	}	

	void Tunnel::IVDecrypt (const uint8_t * in, const uint8_t * ivKey, uint8_t * out)
	{
		m_ECBDecryption.SetKey (ivKey, 32); 
		m_ECBDecryption.ProcessData(out, in, 16); 
	}		

	void Tunnel::EncryptTunnelMsg (I2NPMessage * tunnelMsg)
	{
		uint8_t * payload = tunnelMsg->GetPayload () + 4;
		TunnelHopConfig * hop = m_Config->GetLastHop (); 
		while (hop)
		{	
			// iv + data
			IVDecrypt (payload, hop->ivKey, payload);
			LayerDecrypt (payload + 16, TUNNEL_DATA_ENCRYPTED_SIZE, hop->layerKey, payload, payload+16);
			IVDecrypt (payload, hop->ivKey, payload);
			hop = hop->prev;
		}
	}	
	
	void InboundTunnel::HandleTunnelDataMsg (I2NPMessage * msg)
	{
		EncryptTunnelMsg (msg);
		m_Endpoint.HandleDecryptedTunnelDataMsg (msg);	
	}	

	void OutboundTunnel::SendTunnelDataMsg (const uint8_t * gwHash, uint32_t gwTunnel, i2p::I2NPMessage * msg)
	{
		m_Gateway.SendTunnelDataMsg (gwHash, gwTunnel, msg);
	}
	
	void OutboundTunnel::SendTunnelDataMsg (i2p::I2NPMessage * msg)
	{
		SendTunnelDataMsg (nullptr, 0, msg);
	}	
		
		
	Tunnels tunnels;
	
	Tunnels::Tunnels (): m_IsRunning (false), m_IsTunnelCreated (false), m_NextReplyMsgID (555),
		m_ZeroHopsInboundTunnel (nullptr), m_ZeroHopsOutboundTunnel (nullptr), m_Thread (0)
	{
	}
	
	Tunnels::~Tunnels ()	
	{
		for (auto& it : m_OutboundTunnels)
			delete it;
		m_OutboundTunnels.clear ();

		for (auto& it : m_InboundTunnels)
			delete it.second;
		m_InboundTunnels.clear ();
		
		for (auto& it : m_TransitTunnels)
			delete it.second;
		m_TransitTunnels.clear ();

		for (auto& it : m_PendingTunnels)
			delete it.second;
		m_PendingTunnels.clear ();

		delete m_ZeroHopsInboundTunnel;
		delete m_ZeroHopsOutboundTunnel;
	}	
	
	InboundTunnel * Tunnels::GetInboundTunnel (uint32_t tunnelID)
	{
		auto it = m_InboundTunnels.find(tunnelID);
		if (it != m_InboundTunnels.end ())
			return it->second;
		return nullptr;
	}	
	
	TransitTunnel * Tunnels::GetTransitTunnel (uint32_t tunnelID)
	{
		auto it = m_TransitTunnels.find(tunnelID);
		if (it != m_TransitTunnels.end ())
			return it->second;
		return nullptr;
	}	
		
	Tunnel * Tunnels::GetPendingTunnel (uint32_t replyMsgID)
	{
		auto it = m_PendingTunnels.find(replyMsgID);
		if (it != m_PendingTunnels.end ())
		{
			Tunnel * t = it->second;
			m_PendingTunnels.erase (it);
			return t;
		}	
		return nullptr;
	}	

	InboundTunnel * Tunnels::GetNextInboundTunnel ()
	{
		InboundTunnel * tunnel  = nullptr; 
		size_t minReceived = 0;
		for (auto it : m_InboundTunnels)
			if (!tunnel || it.second->GetNumReceivedBytes () < minReceived)
			{
				tunnel = it.second;
				minReceived = it.second->GetNumReceivedBytes ();
			}		
		return tunnel;
	}
	
	OutboundTunnel * Tunnels::GetNextOutboundTunnel ()
	{
		OutboundTunnel * tunnel  = nullptr; 
		size_t minSent = 0;
		for (auto it : m_OutboundTunnels)
			if (!tunnel || it->GetNumSentBytes () < minSent)
			{
				tunnel = it;
				minSent = it->GetNumSentBytes ();
			}		
		return tunnel;
	}	
	
	void Tunnels::AddTransitTunnel (TransitTunnel * tunnel)
	{
		m_TransitTunnels[tunnel->GetTunnelID ()] = tunnel;
	}	

	void Tunnels::Start ()
	{
		m_IsRunning = true;
		m_Thread = new std::thread (std::bind (&Tunnels::Run, this));
	}
	
	void Tunnels::Stop ()
	{
		m_IsRunning = false;
		m_Queue.WakeUp ();
		if (m_Thread)
		{	
			m_Thread->join (); 
			delete m_Thread;
			m_Thread = 0;
		}	
	}	

	void Tunnels::Run ()
	{
		sleep (1); // wait for other parts are ready

		// we must start with zero hops tunnels
		CreateZeroHopsInboundTunnel ();
		CreateZeroHopsOutboundTunnel ();
		
		uint32_t lastTs = 0;
		while (m_IsRunning)
		{
			try
			{	
				I2NPMessage * msg = m_Queue.GetNextWithTimeout (1000); // 1 sec
				while (msg)
				{
					uint32_t  tunnelID = be32toh (*(uint32_t *)msg->GetPayload ()); 
					InboundTunnel * tunnel = GetInboundTunnel (tunnelID);
					if (tunnel)
						tunnel->HandleTunnelDataMsg (msg);
					else
					{	
						TransitTunnel * transitTunnel = GetTransitTunnel (tunnelID);
						if (transitTunnel)
							transitTunnel->HandleTunnelDataMsg (msg);
						else	
						{	
							LogPrint ("Tunnel ", tunnelID, " not found");
							i2p::DeleteI2NPMessage (msg);
						}	
					}	
					msg = m_Queue.Get ();
				}	
			
				uint32_t ts = i2p::util::GetSecondsSinceEpoch ();
				if (ts - lastTs >= 15) // manage tunnels every 15 seconds
				{
					ManageTunnels ();
					lastTs = ts;
				}
			}
			catch (std::exception& ex)
			{
				LogPrint ("Tunnels: ", ex.what ());
			}	
		}	
	}	

	void Tunnels::ManageTunnels ()
	{
		// check pending tunnel. if something is still there, wipe it out
		// because it wouldn't be reponded anyway
		for (auto& it : m_PendingTunnels)
		{	
			LogPrint ("Pending tunnel build request ", it.first, " has not been responded. Deleted");
			delete it.second;
		}	
		m_PendingTunnels.clear ();
		
		ManageOutboundTunnels ();
		ManageInboundTunnels ();
		
	/*	if (!m_IsTunnelCreated)
		{	
			InboundTunnel * inboundTunnel = CreateOneHopInboundTestTunnel ();
			if (inboundTunnel)
			    CreateOneHopOutboundTestTunnel (inboundTunnel);
			inboundTunnel = CreateTwoHopsInboundTestTunnel ();
			if (inboundTunnel)
				CreateTwoHopsOutboundTestTunnel (inboundTunnel);
				
			m_IsTunnelCreated = true;
		}*/
	}	

	void Tunnels::ManageOutboundTunnels ()
	{
		uint32_t ts = i2p::util::GetSecondsSinceEpoch ();
		for (auto it = m_OutboundTunnels.begin (); it != m_OutboundTunnels.end ();)
		{
			if (ts > (*it)->GetCreationTime () + TUNNEL_EXPIRATION_TIMEOUT)
			{
				LogPrint ("Tunnel ", (*it)->GetTunnelID (), " expired");
				it = m_OutboundTunnels.erase (it);
			}	
			else 
				it++;
		}
	
		if (m_OutboundTunnels.size () < 10)
		{
			// trying to create one more oubound tunnel
			InboundTunnel * inboundTunnel = m_ZeroHopsInboundTunnel;
			if (!m_InboundTunnels.empty ())
				inboundTunnel = m_InboundTunnels.rbegin ()->second;

			if (m_OutboundTunnels.empty () || m_OutboundTunnels.size () < 3)
			{	
				LogPrint ("Creating one hop outbound tunnel...");
				CreateTunnel<OutboundTunnel> (
				  	new TunnelConfig (i2p::data::netdb.GetRandomNTCPRouter (),
			     		inboundTunnel->GetTunnelConfig ()));
			}	
			else
			{
				OutboundTunnel * outboundTunnel =  *m_OutboundTunnels.begin ();
				LogPrint ("Creating two hops outbound tunnel...");
				CreateTunnel<OutboundTunnel> (
				  	new TunnelConfig (inboundTunnel->GetTunnelConfig ()->GetFirstHop ()->router,
						i2p::data::netdb.GetRandomNTCPRouter (),
			     		inboundTunnel->GetTunnelConfig ()),
				        	outboundTunnel);
			}	
		}
	}
	
	void Tunnels::ManageInboundTunnels ()
	{
		uint32_t ts = i2p::util::GetSecondsSinceEpoch ();
		for (auto it = m_InboundTunnels.begin (); it != m_InboundTunnels.end ();)
		{
			if (ts > it->second->GetCreationTime () + TUNNEL_EXPIRATION_TIMEOUT)
			{
				LogPrint ("Tunnel ", it->second->GetTunnelID (), " expired");
				it = m_InboundTunnels.erase (it);
			}	
			else 
				it++;
		}
		
		if (m_InboundTunnels.size () < 10)
		{
			// trying to create one more inbound tunnel
			if (m_OutboundTunnels.empty () || m_InboundTunnels.size () < 3)
			{	
				LogPrint ("Creating one hop inbound tunnel...");
				CreateTunnel<InboundTunnel> (new TunnelConfig (i2p::data::netdb.GetRandomNTCPRouter ()));
			}
			else
			{
				OutboundTunnel * outboundTunnel =  *m_OutboundTunnels.rbegin ();
				InboundTunnel * inboundTunnel =  m_InboundTunnels.rbegin ()->second;
				LogPrint ("Creating two hops inbound tunnel...");
				CreateTunnel<InboundTunnel> (
					new TunnelConfig (i2p::data::netdb.GetRandomNTCPRouter (),
				    	inboundTunnel->GetTunnelConfig ()->GetFirstHop ()->router),
				        	outboundTunnel);
			}	
		}
	}	
	
	void Tunnels::PostTunnelData (I2NPMessage * msg)
	{
		if (msg) m_Queue.Put (msg);		
	}	

	template<class TTunnel>
	TTunnel * Tunnels::CreateTunnel (TunnelConfig * config, OutboundTunnel * outboundTunnel)
	{
		TTunnel * newTunnel = new TTunnel (config);
		m_PendingTunnels[m_NextReplyMsgID] = newTunnel; 
		newTunnel->Build (m_NextReplyMsgID, outboundTunnel);
		m_NextReplyMsgID++; // TODO: should be atomic
		return newTunnel;
	}	

	void Tunnels::AddOutboundTunnel (OutboundTunnel * newTunnel)
	{
		if (newTunnel != m_ZeroHopsOutboundTunnel) 
			m_OutboundTunnels.push_back (newTunnel);
	}	

	void Tunnels::AddInboundTunnel (InboundTunnel * newTunnel)
	{
		if (newTunnel != m_ZeroHopsInboundTunnel) 
			m_InboundTunnels[newTunnel->GetTunnelID ()] = newTunnel;
	}	

	void Tunnels::CreateZeroHopsOutboundTunnel ()
	{
		m_ZeroHopsOutboundTunnel = CreateTunnel<OutboundTunnel> (
			new TunnelConfig (&i2p::context.GetRouterInfo (), 
				m_ZeroHopsInboundTunnel->GetTunnelConfig ()));
	}
	
	void Tunnels::CreateZeroHopsInboundTunnel ()
	{
		m_ZeroHopsInboundTunnel = CreateTunnel<InboundTunnel> (
			new TunnelConfig (&i2p::context.GetRouterInfo ()));
	}	
	
	OutboundTunnel * Tunnels::CreateOneHopOutboundTestTunnel (InboundTunnel * replyTunnel)
	{	
		return CreateTunnel<OutboundTunnel> (replyTunnel->GetTunnelConfig ()->Invert ());
	}	

	InboundTunnel * Tunnels::CreateOneHopInboundTestTunnel (OutboundTunnel * outboundTunnel)
	{
		i2p::ntcp::NTCPSession * peer = i2p::transports.GetNextNTCPSession ();
		if (peer)
		{
			const i2p::data::RouterInfo& router = peer->GetRemoteRouterInfo ();
			return CreateTunnel<InboundTunnel> (new TunnelConfig (&router), outboundTunnel);
		}	
		else
			LogPrint ("No established peers");
		return 0;
	}	

	OutboundTunnel * Tunnels::CreateTwoHopsOutboundTestTunnel (InboundTunnel * replyTunnel)
	{		
		return CreateTunnel<OutboundTunnel> (replyTunnel->GetTunnelConfig ()->Invert ());
	}	

	InboundTunnel * Tunnels::CreateTwoHopsInboundTestTunnel (OutboundTunnel * outboundTunnel)
	{
		i2p::ntcp::NTCPSession * peer = i2p::transports.GetNextNTCPSession ();
		if (peer)
		{
			const i2p::data::RouterInfo& router = peer->GetRemoteRouterInfo ();
			return  CreateTunnel<InboundTunnel> (
						new TunnelConfig (&router, &i2p::context.GetRouterInfo ()),
			            	outboundTunnel);		
		}
		else
			LogPrint ("No established peers");
		return 0;
	}	
}
}