i2pd/core/tunnel/TunnelConfig.h

#ifndef TUNNEL_CONFIG_H__
#define TUNNEL_CONFIG_H__

#include <inttypes.h>
#include <sstream>
#include <vector>
#include <memory>
#include "TunnelCrypto.h"
#include "RouterInfo.h"
#include "RouterContext.h"
#include "util/Timestamp.h"

namespace i2p
{
namespace tunnel
{
    struct TunnelHopConfig
    {
        std::shared_ptr<const i2p::data::RouterInfo> router, nextRouter;
        uint32_t tunnelID, nextTunnelID;
        uint8_t layerKey[32];
        uint8_t ivKey[32];
        uint8_t replyKey[32];
        uint8_t replyIV[16];
        bool isGateway, isEndpoint; 
        
        TunnelHopConfig * next, * prev;
        i2p::crypto::TunnelDecryption decryption;   
        int recordIndex; // record # in tunnel build message
        
        TunnelHopConfig (std::shared_ptr<const i2p::data::RouterInfo> r)
        {
            CryptoPP::RandomNumberGenerator& rnd = i2p::context.GetRandomNumberGenerator ();
            rnd.GenerateBlock (layerKey, 32);
            rnd.GenerateBlock (ivKey, 32);
            rnd.GenerateBlock (replyIV, 16);
            tunnelID = rnd.GenerateWord32 ();
            isGateway = true;
            isEndpoint = true;
            router = r; 
            //nextRouter = nullptr; 
            nextTunnelID = 0;

            next = nullptr;
            prev = nullptr;
        }   

        void SetNextRouter (std::shared_ptr<const i2p::data::RouterInfo> r)
        {
            nextRouter = r;
            isEndpoint = false;
            CryptoPP::RandomNumberGenerator& rnd = i2p::context.GetRandomNumberGenerator ();
            nextTunnelID = rnd.GenerateWord32 ();
        }   

        void SetReplyHop (const TunnelHopConfig * replyFirstHop)
        {
            nextRouter = replyFirstHop->router;
            nextTunnelID = replyFirstHop->tunnelID;
            isEndpoint = true;
        }
        
        void SetNext (TunnelHopConfig * n)
        {
            next = n;
            if (next)
            {   
                next->prev = this;
                next->isGateway = false;
                isEndpoint = false;
                nextRouter = next->router;
                nextTunnelID = next->tunnelID;
            }   
        }

        void SetPrev (TunnelHopConfig * p)
        {
            prev = p;
            if (prev) 
            {   
                prev->next = this;
                prev->isEndpoint = false;
                isGateway = false;
            }   
        }

        void CreateBuildRequestRecord (uint8_t * record, uint32_t replyMsgID) const
        {
            uint8_t clearText[BUILD_REQUEST_RECORD_CLEAR_TEXT_SIZE] = {};
            htobe32buf (clearText + BUILD_REQUEST_RECORD_RECEIVE_TUNNEL_OFFSET, tunnelID);
            memcpy (clearText + BUILD_REQUEST_RECORD_OUR_IDENT_OFFSET, router->GetIdentHash (), 32);
            htobe32buf (clearText + BUILD_REQUEST_RECORD_NEXT_TUNNEL_OFFSET, nextTunnelID);
            memcpy (clearText + BUILD_REQUEST_RECORD_NEXT_IDENT_OFFSET, nextRouter->GetIdentHash (), 32);
            memcpy (clearText + BUILD_REQUEST_RECORD_LAYER_KEY_OFFSET, layerKey, 32);
            memcpy (clearText + BUILD_REQUEST_RECORD_IV_KEY_OFFSET, ivKey, 32);
            memcpy (clearText + BUILD_REQUEST_RECORD_REPLY_KEY_OFFSET, replyKey, 32);
            memcpy (clearText + BUILD_REQUEST_RECORD_REPLY_IV_OFFSET, replyIV, 16);
            uint8_t flag = 0;
            if (isGateway) flag |= 0x80;
            if (isEndpoint) flag |= 0x40;
            clearText[BUILD_REQUEST_RECORD_FLAG_OFFSET] = flag;
            htobe32buf (clearText + BUILD_REQUEST_RECORD_REQUEST_TIME_OFFSET, i2p::util::GetHoursSinceEpoch ()); 
            htobe32buf (clearText + BUILD_REQUEST_RECORD_SEND_MSG_ID_OFFSET, replyMsgID); 
            // TODO: fill padding
            router->GetElGamalEncryption ()->Encrypt (clearText, BUILD_REQUEST_RECORD_CLEAR_TEXT_SIZE, record + BUILD_REQUEST_RECORD_ENCRYPTED_OFFSET);
            memcpy (record + BUILD_REQUEST_RECORD_TO_PEER_OFFSET, (const uint8_t *)router->GetIdentHash (), 16);
        }   
    };  

    class TunnelConfig: public std::enable_shared_from_this<TunnelConfig>
    {
        public:         
            

            TunnelConfig (std::vector<std::shared_ptr<const i2p::data::RouterInfo> > peers, 
                std::shared_ptr<const TunnelConfig> replyTunnelConfig = nullptr) // replyTunnelConfig=nullptr means inbound
            {
                TunnelHopConfig * prev = nullptr;
                for (auto it: peers)
                {
                    auto hop = new TunnelHopConfig (it);
                    if (prev)
                        prev->SetNext (hop);
                    else    
                        m_FirstHop = hop;
                    prev = hop;
                }   
                m_LastHop = prev;
                
                if (replyTunnelConfig) // outbound
                {
                    m_FirstHop->isGateway = false;
                    m_LastHop->SetReplyHop (replyTunnelConfig->GetFirstHop ());
                }   
                else // inbound
                    m_LastHop->SetNextRouter (i2p::context.GetSharedRouterInfo ());
            }
            
            ~TunnelConfig ()
            {
                TunnelHopConfig * hop = m_FirstHop;
                
                while (hop)
                {
                    auto tmp = hop;
                    hop = hop->next;
                    delete tmp;
                }   
            }
            
            TunnelHopConfig * GetFirstHop () const
            {
                return m_FirstHop;
            }

            TunnelHopConfig * GetLastHop () const
            {
                return m_LastHop;
            }

            int GetNumHops () const
            {
                int num = 0;
                TunnelHopConfig * hop = m_FirstHop;     
                while (hop)
                {
                    num++;
                    hop = hop->next;
                }   
                return num;
            }

            bool IsInbound () const { return m_FirstHop->isGateway; }

            std::vector<std::shared_ptr<const i2p::data::RouterInfo> > GetPeers () const
            {
                std::vector<std::shared_ptr<const i2p::data::RouterInfo> > peers;
                TunnelHopConfig * hop = m_FirstHop;     
                while (hop)
                {
                    peers.push_back (hop->router);
                    hop = hop->next;
                }   
                return peers;
            }

            void Print (std::stringstream& s) const
            {
                TunnelHopConfig * hop = m_FirstHop;
                if (!IsInbound ()) // outbound
                    s << "me";
                s << "-->" << m_FirstHop->tunnelID;
                while (hop)
                {
                    s << ":" << hop->router->GetIdentHashAbbreviation () << "-->"; 
                    if (!hop->isEndpoint)
                        s << hop->nextTunnelID;
                    else
                        return;
                    hop = hop->next;
                }   
                // we didn't reach endpoint that mean we are last hop
                s << ":me"; 
            }

            std::shared_ptr<TunnelConfig> Invert () const
            {
                auto peers = GetPeers ();
                std::reverse (peers.begin (), peers.end ());    
                // we use ourself as reply tunnel for outbound tunnel
                return IsInbound () ? std::make_shared<TunnelConfig>(peers, shared_from_this ()) : std::make_shared<TunnelConfig>(peers);
            }

            std::shared_ptr<TunnelConfig> Clone (std::shared_ptr<const TunnelConfig> replyTunnelConfig = nullptr) const
            {
                return std::make_shared<TunnelConfig> (GetPeers (), replyTunnelConfig);
            }   
            
        private:

            // this constructor can't be called from outside
            TunnelConfig (): m_FirstHop (nullptr), m_LastHop (nullptr)
            {
            }
            
        private:

            TunnelHopConfig * m_FirstHop, * m_LastHop;
    };  
}       
}   

#endif