i2pd/Transports.cpp

#include <cryptopp/dh.h>
#include "Log.h"
#include "CryptoConst.h"
#include "RouterContext.h"
#include "I2NPProtocol.h"
#include "NetDb.h"
#include "Transports.h"

using namespace i2p::data;

namespace i2p
{
namespace transport
{
    DHKeysPairSupplier::DHKeysPairSupplier (int size):
        m_QueueSize (size), m_IsRunning (false), m_Thread (nullptr)
    {
    }   

    DHKeysPairSupplier::~DHKeysPairSupplier ()
    {
        Stop ();
    }

    void DHKeysPairSupplier::Start ()
    {
        m_IsRunning = true;
        m_Thread = new std::thread (std::bind (&DHKeysPairSupplier::Run, this));
    }

    void DHKeysPairSupplier::Stop ()
    {
        m_IsRunning = false;
        m_Acquired.notify_one ();   
        if (m_Thread)
        {   
            m_Thread->join (); 
            delete m_Thread;
            m_Thread = 0;
        }   
    }

    void DHKeysPairSupplier::Run ()
    {
        while (m_IsRunning)
        {
            int num;
            while ((num = m_QueueSize - m_Queue.size ()) > 0)
                CreateDHKeysPairs (num);
            std::unique_lock<std::mutex>  l(m_AcquiredMutex);
            m_Acquired.wait (l); // wait for element gets aquired
        }
    }       

    void DHKeysPairSupplier::CreateDHKeysPairs (int num)
    {
        if (num > 0)
        {
            CryptoPP::DH dh (i2p::crypto::elgp, i2p::crypto::elgg);
            for (int i = 0; i < num; i++)
            {
                i2p::transport::DHKeysPair * pair = new i2p::transport::DHKeysPair ();
                dh.GenerateKeyPair(m_Rnd, pair->privateKey, pair->publicKey);
                std::unique_lock<std::mutex>  l(m_AcquiredMutex);
                m_Queue.push (pair);
            }
        }
    }

    DHKeysPair * DHKeysPairSupplier::Acquire ()
    {
        if (!m_Queue.empty ())
        {
            std::unique_lock<std::mutex>  l(m_AcquiredMutex);
            auto pair = m_Queue.front ();
            m_Queue.pop ();
            m_Acquired.notify_one ();
            return pair;
        }   
        else // queue is empty, create new
        {
            DHKeysPair * pair = new DHKeysPair ();
            CryptoPP::DH dh (i2p::crypto::elgp, i2p::crypto::elgg);
            dh.GenerateKeyPair(m_Rnd, pair->privateKey, pair->publicKey);
            return pair;
        }
    }

    void DHKeysPairSupplier::Return (DHKeysPair * pair)
    {
        std::unique_lock<std::mutex>  l(m_AcquiredMutex);
        m_Queue.push (pair);
    }

    Transports transports;  
    
    Transports::Transports (): 
        m_IsRunning (false), m_Thread (nullptr), m_Work (m_Service), m_PeerCleanupTimer (m_Service),
        m_NTCPServer (nullptr), m_SSUServer (nullptr), m_DHKeysPairSupplier (5), // 5 pre-generated keys
        m_TotalSentBytes(0), m_TotalReceivedBytes(0), m_InBandwidth (0), m_OutBandwidth (0),
        m_LastInBandwidthUpdateBytes (0), m_LastOutBandwidthUpdateBytes (0), m_LastBandwidthUpdateTime (0)  
    {       
    }
        
    Transports::~Transports () 
    { 
        Stop ();
    }   

    void Transports::Start ()
    {
#ifdef USE_UPNP
        m_UPnP.Start ();
        LogPrint(eLogInfo, "UPnP started");
#endif
        m_DHKeysPairSupplier.Start ();
        m_IsRunning = true;
        m_Thread = new std::thread (std::bind (&Transports::Run, this));
        // create acceptors
        auto addresses = context.GetRouterInfo ().GetAddresses ();
        for (auto& address : addresses)
        {
            if (!m_NTCPServer)
            {   
                m_NTCPServer = new NTCPServer (address.port);
                m_NTCPServer->Start ();
            }   
            
            if (address.transportStyle == RouterInfo::eTransportSSU && address.host.is_v4 ())
            {
                if (!m_SSUServer)
                {   
                    m_SSUServer = new SSUServer (address.port);
                    LogPrint ("Start listening UDP port ", address.port);
                    m_SSUServer->Start ();  
                    DetectExternalIP ();
                }
                else
                    LogPrint ("SSU server already exists");
            }
        }   
        m_PeerCleanupTimer.expires_from_now (boost::posix_time::seconds(5*SESSION_CREATION_TIMEOUT));
        m_PeerCleanupTimer.async_wait (std::bind (&Transports::HandlePeerCleanupTimer, this, std::placeholders::_1));
    }
        
    void Transports::Stop ()
    {   
#ifdef USE_UPNP
        m_UPnP.Stop ();
        LogPrint(eLogInfo, "UPnP stopped");
#endif
        m_PeerCleanupTimer.cancel ();   
        m_Peers.clear ();
        if (m_SSUServer)
        {
            m_SSUServer->Stop ();
            delete m_SSUServer;
            m_SSUServer = nullptr;
        }   
        if (m_NTCPServer)
        {
            m_NTCPServer->Stop ();
            delete m_NTCPServer;
            m_NTCPServer = nullptr;
        }   

        m_DHKeysPairSupplier.Stop ();
        m_IsRunning = false;
        m_Service.stop ();
        if (m_Thread)
        {   
            m_Thread->join (); 
            delete m_Thread;
            m_Thread = nullptr;
        }   
    }   

    void Transports::Run () 
    { 
        while (m_IsRunning)
        {
            try
            {   
                m_Service.run ();
            }
            catch (std::exception& ex)
            {
                LogPrint ("Transports: ", ex.what ());
            }   
        }   
    }
        
    void Transports::UpdateBandwidth ()
    {
        uint64_t ts = i2p::util::GetMillisecondsSinceEpoch ();
        if (m_LastBandwidthUpdateTime > 0)
        {
            auto delta = ts - m_LastBandwidthUpdateTime;
            if (delta > 0)
            {
                m_InBandwidth = (m_TotalReceivedBytes - m_LastInBandwidthUpdateBytes)*1000/delta; // per second 
                m_OutBandwidth = (m_TotalSentBytes - m_LastOutBandwidthUpdateBytes)*1000/delta; // per second 
            } 
        }
        m_LastBandwidthUpdateTime = ts;
        m_LastInBandwidthUpdateBytes = m_TotalReceivedBytes;    
        m_LastOutBandwidthUpdateBytes = m_TotalSentBytes;       
    }

    bool Transports::IsBandwidthExceeded () const
    {
        if (i2p::context.GetRouterInfo ().IsHighBandwidth ()) return false;
        return std::max (m_InBandwidth, m_OutBandwidth) > LOW_BANDWIDTH_LIMIT;
    }

    void Transports::SendMessage (const i2p::data::IdentHash& ident, std::shared_ptr<i2p::I2NPMessage> msg)
    {
        SendMessages (ident, std::vector<std::shared_ptr<i2p::I2NPMessage> > {msg });                             
    }   

    void Transports::SendMessages (const i2p::data::IdentHash& ident, const std::vector<std::shared_ptr<i2p::I2NPMessage> >& msgs)
    {
        m_Service.post (std::bind (&Transports::PostMessages, this, ident, msgs));
    }   

    void Transports::PostMessages (i2p::data::IdentHash ident, std::vector<std::shared_ptr<i2p::I2NPMessage> > msgs)
    {
        if (ident == i2p::context.GetRouterInfo ().GetIdentHash ())
        {   
            // we send it to ourself
            for (auto it: msgs)
                i2p::HandleI2NPMessage (it);
            return;
        }   
        auto it = m_Peers.find (ident);
        if (it == m_Peers.end ())
        {
            bool connected = false; 
            try
            {
                auto r = netdb.FindRouter (ident);
                it = m_Peers.insert (std::pair<i2p::data::IdentHash, Peer>(ident, { 0, r, {},
                    i2p::util::GetSecondsSinceEpoch () })).first;
                connected = ConnectToPeer (ident, it->second);
            }
            catch (std::exception& ex)
            {
                LogPrint (eLogError, "Transports::PostMessages ", ex.what ());
            }
            if (!connected) return;
        }   
        if (!it->second.sessions.empty ())
            it->second.sessions.front ()->SendI2NPMessages (msgs);
        else
        {   
            for (auto it1: msgs)
                it->second.delayedMessages.push_back (it1);
        }   
    }   
        
    bool Transports::ConnectToPeer (const i2p::data::IdentHash& ident, Peer& peer)
    {
        if (peer.router) // we have RI already
        {   
            if (!peer.numAttempts) // NTCP
            {
                peer.numAttempts++;
                auto address = peer.router->GetNTCPAddress (!context.SupportsV6 ());
                if (address)
                {
#if BOOST_VERSION >= 104900
                    if (!address->host.is_unspecified ()) // we have address now
#else
                    boost::system::error_code ecode;
                    address->host.to_string (ecode);
                    if (!ecode)
#endif
                    {
                        if (!peer.router->UsesIntroducer () && !peer.router->IsUnreachable ())
                        {   
                            auto s = std::make_shared<NTCPSession> (*m_NTCPServer, peer.router);
                            m_NTCPServer->Connect (address->host, address->port, s);
                            return true;
                        }
                    }
                    else // we don't have address
                    {
                        if (address->addressString.length () > 0) // trying to resolve
                        {
                            LogPrint (eLogInfo, "Resolving ", address->addressString);
                            NTCPResolve (address->addressString, ident);
                            return true;
                        }
                    }
                }   
            }
            else  if (peer.numAttempts == 1)// SSU
            {
                peer.numAttempts++;
                if (m_SSUServer)
                {   
                    if (m_SSUServer->GetSession (peer.router))
                        return true;
                }
            }   
            LogPrint (eLogError, "No NTCP and SSU addresses available");
            peer.Done ();
            m_Peers.erase (ident);
            return false;
        }   
        else // otherwise request RI
        {
            LogPrint ("Router not found. Requested");
            i2p::data::netdb.RequestDestination (ident, std::bind (
                &Transports::RequestComplete, this, std::placeholders::_1, ident));
        }   
        return true;
    }   
    
    void Transports::RequestComplete (std::shared_ptr<const i2p::data::RouterInfo> r, const i2p::data::IdentHash& ident)
    {
        m_Service.post (std::bind (&Transports::HandleRequestComplete, this, r, ident));
    }       
    
    void Transports::HandleRequestComplete (std::shared_ptr<const i2p::data::RouterInfo> r, const i2p::data::IdentHash& ident)
    {
        auto it = m_Peers.find (ident);
        if (it != m_Peers.end ())
        {   
            if (r)
            {
                LogPrint ("Router found. Trying to connect");
                it->second.router = r;
                ConnectToPeer (ident, it->second);
            }   
            else
            {
                LogPrint ("Router not found. Failed to send messages");
                m_Peers.erase (it);
            }   
        }   
    }   

    void Transports::NTCPResolve (const std::string& addr, const i2p::data::IdentHash& ident)
    {
        auto resolver = std::make_shared<boost::asio::ip::tcp::resolver>(m_Service);
        resolver->async_resolve (boost::asio::ip::tcp::resolver::query (addr, ""), 
            std::bind (&Transports::HandleNTCPResolve, this, 
                std::placeholders::_1, std::placeholders::_2, ident, resolver));
    }

    void Transports::HandleNTCPResolve (const boost::system::error_code& ecode, boost::asio::ip::tcp::resolver::iterator it, 
        i2p::data::IdentHash ident, std::shared_ptr<boost::asio::ip::tcp::resolver> resolver)
    {
        auto it1 = m_Peers.find (ident);
        if (it1 != m_Peers.end ())
        {
            auto& peer = it1->second;
            if (!ecode && peer.router)
            {
                auto address = (*it).endpoint ().address ();
                LogPrint (eLogInfo, (*it).host_name (), " has been resolved to ", address);
                auto addr = peer.router->GetNTCPAddress ();
                if (addr)
                {
                    auto s = std::make_shared<NTCPSession> (*m_NTCPServer, peer.router);
                    m_NTCPServer->Connect (address, addr->port, s);
                    return;
                }   
            }
            LogPrint (eLogError, "Unable to resolve NTCP address: ", ecode.message ());
            m_Peers.erase (it1);
        }
    }

    void Transports::CloseSession (std::shared_ptr<const i2p::data::RouterInfo> router)
    {
        if (!router) return;
        m_Service.post (std::bind (&Transports::PostCloseSession, this, router));    
    }   

    void Transports::PostCloseSession (std::shared_ptr<const i2p::data::RouterInfo> router)
    {
        auto ssuSession = m_SSUServer ? m_SSUServer->FindSession (router) : nullptr;
        if (ssuSession) // try SSU first
        {   
            m_SSUServer->DeleteSession (ssuSession);
            LogPrint ("SSU session closed");    
        }   
        // TODO: delete NTCP
    }   
        
    void Transports::DetectExternalIP ()
    {
        if (m_SSUServer)
        {
            i2p::context.SetStatus (eRouterStatusTesting);
            for (int i = 0; i < 5; i++)
            {
                auto router = i2p::data::netdb.GetRandomPeerTestRouter ();
                if (router  && router->IsSSU ())
                    m_SSUServer->GetSession (router, true);  // peer test   
                else
                {
                    // if not peer test capable routers found pick any
                    router = i2p::data::netdb.GetRandomRouter ();
                    if (router && router->IsSSU ())
                        m_SSUServer->GetSession (router);   // no peer test
                }
            }   
        }
        else
            LogPrint (eLogError, "Can't detect external IP. SSU is not available");
    }
            
    DHKeysPair * Transports::GetNextDHKeysPair ()
    {
        return m_DHKeysPairSupplier.Acquire ();
    }

    void Transports::ReuseDHKeysPair (DHKeysPair * pair)
    {
        m_DHKeysPairSupplier.Return (pair);
    }

    void Transports::PeerConnected (std::shared_ptr<TransportSession> session)
    {
        m_Service.post([session, this]()
        {   
            auto ident = session->GetRemoteIdentity ().GetIdentHash ();
            auto it = m_Peers.find (ident);
            if (it != m_Peers.end ())
            {
                it->second.sessions.push_back (session);
                session->SendI2NPMessages (it->second.delayedMessages);
                it->second.delayedMessages.clear ();
            }
            else // incoming connection
                m_Peers.insert (std::make_pair (ident, Peer{ 0, nullptr, { session }, i2p::util::GetSecondsSinceEpoch () }));
        });         
    }
        
    void Transports::PeerDisconnected (std::shared_ptr<TransportSession> session)
    {
        m_Service.post([session, this]()
        {  
            auto ident = session->GetRemoteIdentity ().GetIdentHash ();
            auto it = m_Peers.find (ident);
            if (it != m_Peers.end ())
            {
                it->second.sessions.remove (session);
                if (it->second.sessions.empty ()) // TODO: why?
                {   
                    if (it->second.delayedMessages.size () > 0)
                        ConnectToPeer (ident, it->second);
                    else
                        m_Peers.erase (it);
                }
            }
        }); 
    }   

    bool Transports::IsConnected (const i2p::data::IdentHash& ident) const
    {
        auto it = m_Peers.find (ident);
        return it != m_Peers.end ();
    }   
        
    void Transports::HandlePeerCleanupTimer (const boost::system::error_code& ecode)
    {
        if (ecode != boost::asio::error::operation_aborted)
        {
            auto ts = i2p::util::GetSecondsSinceEpoch ();
            for (auto it = m_Peers.begin (); it != m_Peers.end (); )
            {
                if (it->second.sessions.empty () && ts > it->second.creationTime + SESSION_CREATION_TIMEOUT)
                {
                    LogPrint (eLogError, "Session to peer ", it->first.ToBase64 (), " has not been created in ", SESSION_CREATION_TIMEOUT, " seconds");
                    it = m_Peers.erase (it);
                }
                else
                    it++;
            }
            UpdateBandwidth (); // TODO: use separate timer(s) for it
            if (i2p::context.GetStatus () == eRouterStatusTesting) // if still testing,  repeat peer test
                DetectExternalIP ();
            m_PeerCleanupTimer.expires_from_now (boost::posix_time::seconds(5*SESSION_CREATION_TIMEOUT));
            m_PeerCleanupTimer.async_wait (std::bind (&Transports::HandlePeerCleanupTimer, this, std::placeholders::_1));
        }   
    }

    std::shared_ptr<const i2p::data::RouterInfo> Transports::GetRandomPeer () const
    {
        if(m_Peers.empty()) // ensure m.Peers.size() >= 1
            return nullptr;

        CryptoPP::RandomNumberGenerator& rnd = i2p::context.GetRandomNumberGenerator();
        auto it = m_Peers.begin();
        std::advance(it, rnd.GenerateWord32(0, m_Peers.size () - 1));

        return it->second.router;
    }
}
}