i2pd/libi2pd/Garlic.h

#ifndef GARLIC_H__
#define GARLIC_H__

#include <inttypes.h>
#include <map>
#include <list>
#include <string>
#include <thread>
#include <mutex>
#include <memory>
#include "Crypto.h"
#include "I2NPProtocol.h"
#include "LeaseSet.h"
#include "Queue.h"
#include "Identity.h"

namespace i2p
{
namespace tunnel
{		
	class OutboundTunnel;
}
	
namespace garlic
{
	
	enum GarlicDeliveryType 
	{ 
		eGarlicDeliveryTypeLocal = 0, 
		eGarlicDeliveryTypeDestination = 1,
		eGarlicDeliveryTypeRouter = 2,	
		eGarlicDeliveryTypeTunnel = 3
	};	

	struct ElGamalBlock
	{
		uint8_t sessionKey[32];
		uint8_t preIV[32];
		uint8_t padding[158];
	};		

	const int INCOMING_TAGS_EXPIRATION_TIMEOUT = 960; // 16 minutes			
	const int OUTGOING_TAGS_EXPIRATION_TIMEOUT = 720; // 12 minutes
	const int OUTGOING_TAGS_CONFIRMATION_TIMEOUT = 10; // 10 seconds 
	const int LEASET_CONFIRMATION_TIMEOUT = 4000; // in milliseconds
	const int ROUTING_PATH_EXPIRATION_TIMEOUT = 30; // 30 seconds 
	const int ROUTING_PATH_MAX_NUM_TIMES_USED = 100; // how many times might be used 
	
	struct SessionTag: public i2p::data::Tag<32> 
	{
		SessionTag (const uint8_t * buf, uint32_t ts = 0): Tag<32>(buf), creationTime (ts) {};
		SessionTag () = default;
		SessionTag (const SessionTag& ) = default;
		SessionTag& operator= (const SessionTag& ) = default;
#ifndef _WIN32
		SessionTag (SessionTag&& ) = default; 
		SessionTag& operator= (SessionTag&& ) = default;	
#endif
		uint32_t creationTime; // seconds since epoch	
	};

	// AESDecryption is associated with session tags and store key
	class AESDecryption: public i2p::crypto::CBCDecryption
	{
		public:

			AESDecryption (const uint8_t * key): m_Key (key)
			{
				SetKey (key);
			}			
			const i2p::crypto::AESKey& GetKey () const { return m_Key; };

		private:

			i2p::crypto::AESKey m_Key;
	};

	struct GarlicRoutingPath
	{
		std::shared_ptr<i2p::tunnel::OutboundTunnel> outboundTunnel;
		std::shared_ptr<const i2p::data::Lease> remoteLease;
		int rtt; // RTT
		uint32_t updateTime; // seconds since epoch
		int numTimesUsed; 
	};	

	class GarlicDestination;
	class GarlicRoutingSession: public std::enable_shared_from_this<GarlicRoutingSession>
	{
			enum LeaseSetUpdateStatus
			{
				eLeaseSetUpToDate = 0,
				eLeaseSetUpdated,
				eLeaseSetSubmitted,
				eLeaseSetDoNotSend
			};
		
			struct UnconfirmedTags
			{
				UnconfirmedTags (int n): numTags (n), tagsCreationTime (0) { sessionTags = new SessionTag[numTags]; };
				~UnconfirmedTags () { delete[] sessionTags; };
				uint32_t msgID;
				int numTags;
				SessionTag * sessionTags;
				uint32_t tagsCreationTime;
			};

		public:

			GarlicRoutingSession (GarlicDestination * owner, std::shared_ptr<const i2p::data::RoutingDestination> destination, 
				int numTags, bool attachLeaseSet);
			GarlicRoutingSession (const uint8_t * sessionKey, const SessionTag& sessionTag); // one time encryption
			~GarlicRoutingSession ();
			std::shared_ptr<I2NPMessage> WrapSingleMessage (std::shared_ptr<const I2NPMessage> msg);
			void MessageConfirmed (uint32_t msgID);
			bool CleanupExpiredTags (); // returns true if something left 
			bool CleanupUnconfirmedTags (); // returns true if something has been deleted

			void SetLeaseSetUpdated () 
			{ 
				if (m_LeaseSetUpdateStatus != eLeaseSetDoNotSend) m_LeaseSetUpdateStatus = eLeaseSetUpdated; 
			};
			bool IsLeaseSetNonConfirmed () const { return m_LeaseSetUpdateStatus == eLeaseSetSubmitted; };
			bool IsLeaseSetUpdated () const { return m_LeaseSetUpdateStatus == eLeaseSetUpdated; };
			uint64_t GetLeaseSetSubmissionTime () const { return m_LeaseSetSubmissionTime; }	
			
			std::shared_ptr<GarlicRoutingPath> GetSharedRoutingPath ();
			void SetSharedRoutingPath (std::shared_ptr<GarlicRoutingPath> path);

			const GarlicDestination * GetOwner () const { return m_Owner; }
			void SetOwner (GarlicDestination * owner) { m_Owner = owner; }

		private:

			size_t CreateAESBlock (uint8_t * buf, std::shared_ptr<const I2NPMessage> msg);
			size_t CreateGarlicPayload (uint8_t * payload, std::shared_ptr<const I2NPMessage> msg, UnconfirmedTags * newTags);
			size_t CreateGarlicClove (uint8_t * buf, std::shared_ptr<const I2NPMessage> msg, bool isDestination);
			size_t CreateDeliveryStatusClove (uint8_t * buf, uint32_t msgID);

			void TagsConfirmed (uint32_t msgID);
			UnconfirmedTags * GenerateSessionTags ();

		private:

			GarlicDestination * m_Owner;
			std::shared_ptr<const i2p::data::RoutingDestination> m_Destination;
			
			i2p::crypto::AESKey m_SessionKey;
			std::list<SessionTag> m_SessionTags;
			int m_NumTags;
			std::map<uint32_t, std::unique_ptr<UnconfirmedTags> > m_UnconfirmedTagsMsgs; // msgID->tags	
			
			LeaseSetUpdateStatus m_LeaseSetUpdateStatus;
			uint32_t m_LeaseSetUpdateMsgID;
			uint64_t m_LeaseSetSubmissionTime; // in milliseconds
			
			i2p::crypto::CBCEncryption m_Encryption;

			std::shared_ptr<GarlicRoutingPath> m_SharedRoutingPath;
			
		public:
			// for HTTP only
			size_t GetNumOutgoingTags () const { return m_SessionTags.size (); };
	};	
	//using GarlicRoutingSessionPtr = std::shared_ptr<GarlicRoutingSession>;
	typedef std::shared_ptr<GarlicRoutingSession> GarlicRoutingSessionPtr; // TODO: replace to using after switch to 4.8	

	class GarlicDestination: public i2p::data::LocalDestination
	{
		public:

			GarlicDestination ();
			~GarlicDestination ();

			void CleanUp ();
			void SetNumTags (int numTags) { m_NumTags = numTags; };	
			std::shared_ptr<GarlicRoutingSession> GetRoutingSession (std::shared_ptr<const i2p::data::RoutingDestination> destination, bool attachLeaseSet);	
			void CleanupExpiredTags ();
			void RemoveDeliveryStatusSession (uint32_t msgID);
			std::shared_ptr<I2NPMessage> WrapMessage (std::shared_ptr<const i2p::data::RoutingDestination> destination, 
			    std::shared_ptr<I2NPMessage> msg, bool attachLeaseSet = false);

			void AddSessionKey (const uint8_t * key, const uint8_t * tag); // one tag
			virtual bool SubmitSessionKey (const uint8_t * key, const uint8_t * tag); // from different thread
			void DeliveryStatusSent (GarlicRoutingSessionPtr session, uint32_t msgID);
			
			virtual void ProcessGarlicMessage (std::shared_ptr<I2NPMessage> msg);
			virtual void ProcessDeliveryStatusMessage (std::shared_ptr<I2NPMessage> msg);			
			virtual void SetLeaseSetUpdated ();
			
			virtual std::shared_ptr<const i2p::data::LocalLeaseSet> GetLeaseSet () = 0; // TODO
			virtual std::shared_ptr<i2p::tunnel::TunnelPool> GetTunnelPool () const = 0;
			virtual void HandleI2NPMessage (const uint8_t * buf, size_t len, std::shared_ptr<i2p::tunnel::InboundTunnel> from) = 0;
			
		protected:

			void HandleGarlicMessage (std::shared_ptr<I2NPMessage> msg);
			void HandleDeliveryStatusMessage (std::shared_ptr<I2NPMessage> msg);			

			void SaveTags ();
			void LoadTags ();	

		private:

			void HandleAESBlock (uint8_t * buf, size_t len, std::shared_ptr<AESDecryption> decryption, 
				std::shared_ptr<i2p::tunnel::InboundTunnel> from);
			void HandleGarlicPayload (uint8_t * buf, size_t len, std::shared_ptr<i2p::tunnel::InboundTunnel> from);

		private:

			BN_CTX * m_Ctx; // incoming
			// outgoing sessions
			int m_NumTags;
			std::mutex m_SessionsMutex;
			std::map<i2p::data::IdentHash, GarlicRoutingSessionPtr> m_Sessions;
			// incoming
			std::map<SessionTag, std::shared_ptr<AESDecryption> > m_Tags;
			// DeliveryStatus
			std::mutex m_DeliveryStatusSessionsMutex;
			std::map<uint32_t, GarlicRoutingSessionPtr> m_DeliveryStatusSessions; // msgID -> session
			
		public:

			// for HTTP only
			size_t GetNumIncomingTags () const { return m_Tags.size (); }	
			const decltype(m_Sessions)& GetSessions () const { return m_Sessions; };
	};

	void CleanUpTagsFiles ();
	
}	
}

#endif