I2P: End-to-End encrypted and anonymous Internet https://i2pd.website/
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#ifndef SSU_H__
#define SSU_H__
#include <inttypes.h>
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#include <map>
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#include <boost/asio.hpp>
#include <cryptopp/modes.h>
#include <cryptopp/aes.h>
#include "I2PEndian.h"
#include "RouterInfo.h"
#include "I2NPProtocol.h"
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namespace i2p
{
namespace ssu
{
#pragma pack(1)
struct SSUHeader
{
uint8_t mac[16];
uint8_t iv[16];
uint8_t flag;
uint32_t time;
};
#pragma pack()
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const int SSU_MTU = 1484;
// payload types (4 bits)
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const uint8_t PAYLOAD_TYPE_SESSION_REQUEST = 0;
const uint8_t PAYLOAD_TYPE_SESSION_CREATED = 1;
const uint8_t PAYLOAD_TYPE_SESSION_CONFIRMED = 2;
const uint8_t PAYLOAD_TYPE_RELAY_REQUEST = 3;
const uint8_t PAYLOAD_TYPE_RELAY_RESPONSE = 4;
const uint8_t PAYLOAD_TYPE_RELAY_INTRO = 5;
const uint8_t PAYLOAD_TYPE_DATA = 6;
const uint8_t PAYLOAD_TYPE_TEST = 7;
const uint8_t PAYLOAD_TYPE_SESSION_DESTROY = 8;
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// data flags
const uint8_t DATA_FLAG_EXTENDED_DATA_INCLUDED = 0x02;
const uint8_t DATA_FLAG_WANT_REPLY = 0x04;
const uint8_t DATA_FLAG_REQUEST_PREVIOUS_ACKS = 0x08;
const uint8_t DATA_FLAG_EXPLICIT_CONGESTION_NOTIFICATION = 0x10;
const uint8_t DATA_FLAG_ACK_BITFIELDS_INCLUDED = 0x40;
const uint8_t DATA_FLAG_EXPLICIT_ACKS_INCLUDED = 0x80;
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enum SessionState
{
eSessionStateUnknown,
eSessionStateRequestSent,
eSessionStateRequestReceived,
eSessionStateCreatedSent,
eSessionStateCreatedReceived,
eSessionStateConfirmedSent,
eSessionStateConfirmedReceived,
eSessionStateEstablised
};
class SSUServer;
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class SSUSession
{
public:
SSUSession (SSUServer * server, const boost::asio::ip::udp::endpoint& remoteEndpoint,
i2p::data::RouterInfo * router = nullptr);
void ProcessNextMessage (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& senderEndpoint);
void Connect ();
void SendI2NPMessage (I2NPMessage * msg);
private:
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void CreateAESandMacKey (uint8_t * pubKey, uint8_t * aesKey, uint8_t * macKey);
void ProcessMessage (uint8_t * buf, size_t len); // call for established session
void ProcessSessionRequest (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& senderEndpoint);
void SendSessionRequest ();
void ProcessSessionCreated (uint8_t * buf, size_t len);
void SendSessionCreated (const uint8_t * x);
void ProcessSessionConfirmed (uint8_t * buf, size_t len);
void SendSessionConfirmed (const uint8_t * y, const uint8_t * ourAddress, uint32_t relayTag);
void ProcessData (uint8_t * buf, size_t len);
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void SendMsgAck (uint32_t msgID);
bool ProcessIntroKeyEncryptedMessage (uint8_t expectedPayloadType, i2p::data::RouterInfo& r, uint8_t * buf, size_t len);
void FillHeaderAndEncrypt (uint8_t payloadType, uint8_t * buf, size_t len, uint8_t * aesKey, uint8_t * iv, uint8_t * macKey);
void Decrypt (uint8_t * buf, size_t len, uint8_t * aesKey);
bool Validate (uint8_t * buf, size_t len, uint8_t * macKey);
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private:
SSUServer * m_Server;
boost::asio::ip::udp::endpoint m_RemoteEndpoint;
i2p::data::RouterInfo * m_RemoteRouter;
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SessionState m_State;
CryptoPP::CBC_Mode<CryptoPP::AES>::Encryption m_Encryption;
CryptoPP::CBC_Mode<CryptoPP::AES>::Decryption m_Decryption;
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uint8_t m_SessionKey[32], m_MacKey[32];
std::map<uint32_t, I2NPMessage *> m_IncomleteMessages;
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};
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class SSUServer
{
public:
SSUServer (boost::asio::io_service& service, int port);
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~SSUServer ();
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void Start ();
void Stop ();
SSUSession * GetSession (i2p::data::RouterInfo * router);
const boost::asio::ip::udp::endpoint& GetEndpoint () const { return m_Endpoint; };
void Send (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& to);
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private:
void Receive ();
void HandleReceivedFrom (const boost::system::error_code& ecode, std::size_t bytes_transferred);
private:
boost::asio::ip::udp::endpoint m_Endpoint;
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boost::asio::ip::udp::socket m_Socket;
boost::asio::ip::udp::endpoint m_SenderEndpoint;
uint8_t m_ReceiveBuffer[2*SSU_MTU];
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std::map<boost::asio::ip::udp::endpoint, SSUSession *> m_Sessions;
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};
}
}
#endif