I2P: End-to-End encrypted and anonymous Internet https://i2pd.website/
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#ifndef NTCP_SESSION_H__
#define NTCP_SESSION_H__
#include <inttypes.h>
#include <map>
#include <memory>
#include <thread>
#include <mutex>
#include <boost/asio.hpp>
#include "Crypto.h"
#include "Identity.h"
#include "RouterInfo.h"
#include "I2NPProtocol.h"
#include "TransportSession.h"
namespace i2p
{
namespace transport
{
struct NTCPPhase1
{
uint8_t pubKey[256];
uint8_t HXxorHI[32];
};
struct NTCPPhase2
{
uint8_t pubKey[256];
struct
{
uint8_t hxy[32];
uint8_t timestamp[4];
uint8_t filler[12];
} encrypted;
};
const size_t NTCP_MAX_MESSAGE_SIZE = 16384;
const size_t NTCP_BUFFER_SIZE = 1028; // fits 1 tunnel data message
const int NTCP_CONNECT_TIMEOUT = 5; // 5 seconds
const int NTCP_ESTABLISH_TIMEOUT = 10; // 10 seconds
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const int NTCP_TERMINATION_TIMEOUT = 120; // 2 minutes
const int NTCP_TERMINATION_CHECK_TIMEOUT = 30; // 30 seconds
const size_t NTCP_DEFAULT_PHASE3_SIZE = 2/*size*/ + i2p::data::DEFAULT_IDENTITY_SIZE/*387*/ + 4/*ts*/ + 15/*padding*/ + 40/*signature*/; // 448
const int NTCP_CLOCK_SKEW = 60; // in seconds
const int NTCP_MAX_OUTGOING_QUEUE_SIZE = 200; // how many messages we can queue up
class NTCPServer;
class NTCPSession: public TransportSession, public std::enable_shared_from_this<NTCPSession>
{
public:
NTCPSession (NTCPServer& server, std::shared_ptr<const i2p::data::RouterInfo> in_RemoteRouter = nullptr);
~NTCPSession ();
void Terminate ();
void Done ();
boost::asio::ip::tcp::socket& GetSocket () { return m_Socket; };
bool IsEstablished () const { return m_IsEstablished; };
bool IsTerminated () const { return m_IsTerminated; };
void ClientLogin ();
void ServerLogin ();
void SendI2NPMessages (const std::vector<std::shared_ptr<I2NPMessage> >& msgs);
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private:
void PostI2NPMessages (std::vector<std::shared_ptr<I2NPMessage> > msgs);
void Connected ();
void SendTimeSyncMessage ();
void SetIsEstablished (bool isEstablished) { m_IsEstablished = isEstablished; }
void CreateAESKey (uint8_t * pubKey);
// client
void SendPhase3 ();
void HandlePhase1Sent (const boost::system::error_code& ecode, std::size_t bytes_transferred);
void HandlePhase2Received (const boost::system::error_code& ecode, std::size_t bytes_transferred);
void HandlePhase2 ();
void HandlePhase3Sent (const boost::system::error_code& ecode, std::size_t bytes_transferred, uint32_t tsA);
void HandlePhase4Received (const boost::system::error_code& ecode, std::size_t bytes_transferred, uint32_t tsA);
//server
void SendPhase2 ();
void SendPhase4 (uint32_t tsA, uint32_t tsB);
void HandlePhase1Received (const boost::system::error_code& ecode, std::size_t bytes_transferred);
void HandlePhase2Sent (const boost::system::error_code& ecode, std::size_t bytes_transferred, uint32_t tsB);
void HandlePhase3Received (const boost::system::error_code& ecode, std::size_t bytes_transferred, uint32_t tsB);
void HandlePhase3ExtraReceived (const boost::system::error_code& ecode, std::size_t bytes_transferred, uint32_t tsB, size_t paddingLen);
void HandlePhase3 (uint32_t tsB, size_t paddingLen);
void HandlePhase4Sent (const boost::system::error_code& ecode, std::size_t bytes_transferred);
// common
void Receive ();
void HandleReceived (const boost::system::error_code& ecode, std::size_t bytes_transferred);
bool DecryptNextBlock (const uint8_t * encrypted);
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void Send (std::shared_ptr<i2p::I2NPMessage> msg);
boost::asio::const_buffers_1 CreateMsgBuffer (std::shared_ptr<I2NPMessage> msg);
void Send (const std::vector<std::shared_ptr<I2NPMessage> >& msgs);
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void HandleSent (const boost::system::error_code& ecode, std::size_t bytes_transferred, std::vector<std::shared_ptr<I2NPMessage> > msgs);
private:
NTCPServer& m_Server;
boost::asio::ip::tcp::socket m_Socket;
bool m_IsEstablished, m_IsTerminated;
i2p::crypto::CBCDecryption m_Decryption;
i2p::crypto::CBCEncryption m_Encryption;
struct Establisher
{
NTCPPhase1 phase1;
NTCPPhase2 phase2;
} * m_Establisher;
i2p::crypto::AESAlignedBuffer<NTCP_BUFFER_SIZE + 16> m_ReceiveBuffer;
i2p::crypto::AESAlignedBuffer<16> m_TimeSyncBuffer;
int m_ReceiveBufferOffset;
std::shared_ptr<I2NPMessage> m_NextMessage;
size_t m_NextMessageOffset;
i2p::I2NPMessagesHandler m_Handler;
bool m_IsSending;
std::vector<std::shared_ptr<I2NPMessage> > m_SendQueue;
};
// TODO: move to NTCP.h/.cpp
class NTCPServer
{
public:
enum RemoteAddressType
{
eIP4Address,
eIP6Address,
eHostname
};
enum ProxyType
{
eNoProxy,
eSocksProxy,
eHTTPProxy
};
NTCPServer ();
~NTCPServer ();
void Start ();
void Stop ();
bool AddNTCPSession (std::shared_ptr<NTCPSession> session);
void RemoveNTCPSession (std::shared_ptr<NTCPSession> session);
std::shared_ptr<NTCPSession> FindNTCPSession (const i2p::data::IdentHash& ident);
void ConnectWithProxy (const std::string& addr, uint16_t port, RemoteAddressType addrtype, std::shared_ptr<NTCPSession> conn);
void Connect(const boost::asio::ip::address & address, uint16_t port, std::shared_ptr<NTCPSession> conn);
bool IsBoundV4() const { return m_NTCPAcceptor != nullptr; };
bool IsBoundV6() const { return m_NTCPV6Acceptor != nullptr; };
bool NetworkIsReady() const { return IsBoundV4() || IsBoundV6() || UsingProxy(); };
bool UsingProxy() const { return m_ProxyType != eNoProxy; };
void UseProxy(ProxyType proxy, const std::string & address, uint16_t port);
boost::asio::io_service& GetService () { return m_Service; };
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void SetSessionLimits(uint16_t softLimit, uint16_t hardLimit) { m_SoftLimit = softLimit; m_HardLimit = hardLimit; }
bool ShouldLimit() const { return ShouldHardLimit() || ShouldSoftLimit(); }
private:
/** @brief return true for hard limit */
bool ShouldHardLimit() const { return m_HardLimit && m_NTCPSessions.size() >= m_HardLimit; }
/** @brief return true for probabalistic soft backoff */
bool ShouldSoftLimit() const
{
auto sessions = m_NTCPSessions.size();
return sessions && m_SoftLimit && m_SoftLimit < sessions && ( rand() % sessions ) <= m_SoftLimit;
}
void Run ();
void HandleAccept (std::shared_ptr<NTCPSession> conn, const boost::system::error_code& error);
void HandleAcceptV6 (std::shared_ptr<NTCPSession> conn, const boost::system::error_code& error);
void HandleConnect (const boost::system::error_code& ecode, std::shared_ptr<NTCPSession> conn, std::shared_ptr<boost::asio::deadline_timer> timer);
void HandleProxyConnect(const boost::system::error_code& ecode, std::shared_ptr<NTCPSession> conn, std::shared_ptr<boost::asio::deadline_timer> timer, const std::string & host, uint16_t port, RemoteAddressType adddrtype);
void AfterSocksHandshake(std::shared_ptr<NTCPSession> conn, std::shared_ptr<boost::asio::deadline_timer> timer, const std::string & host, uint16_t port, RemoteAddressType adddrtype);
// timer
void ScheduleTermination ();
void HandleTerminationTimer (const boost::system::error_code& ecode);
private:
bool m_IsRunning;
std::thread * m_Thread;
boost::asio::io_service m_Service;
boost::asio::io_service::work m_Work;
boost::asio::deadline_timer m_TerminationTimer;
boost::asio::ip::tcp::acceptor * m_NTCPAcceptor, * m_NTCPV6Acceptor;
std::map<i2p::data::IdentHash, std::shared_ptr<NTCPSession> > m_NTCPSessions; // access from m_Thread only
std::list<std::shared_ptr<NTCPSession> > m_PendingIncomingSessions;
ProxyType m_ProxyType;
std::string m_ProxyAddress;
uint16_t m_ProxyPort;
boost::asio::ip::tcp::resolver m_Resolver;
boost::asio::ip::tcp::endpoint * m_ProxyEndpoint;
uint16_t m_SoftLimit, m_HardLimit;
public:
// for HTTP/I2PControl
const decltype(m_NTCPSessions)& GetNTCPSessions () const { return m_NTCPSessions; };
};
}
}
#endif