I2P: End-to-End encrypted and anonymous Internet https://i2pd.website/
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/*
* Copyright (c) 2013-2021, The PurpleI2P Project
*
* This file is part of Purple i2pd project and licensed under BSD3
*
* See full license text in LICENSE file at top of project tree
*/
#ifndef SSU_SESSION_H__
#define SSU_SESSION_H__
#include <inttypes.h>
#include <set>
#include <memory>
#include "Crypto.h"
#include "I2NPProtocol.h"
#include "TransportSession.h"
#include "SSUData.h"
namespace i2p
{
namespace transport
{
const uint8_t SSU_HEADER_EXTENDED_OPTIONS_INCLUDED = 0x04;
struct SSUHeader
{
uint8_t mac[16];
uint8_t iv[16];
uint8_t flag;
uint8_t time[4];
uint8_t GetPayloadType () const { return flag >> 4; };
bool IsExtendedOptions () const { return flag & SSU_HEADER_EXTENDED_OPTIONS_INCLUDED; };
};
const int SSU_CONNECT_TIMEOUT = 5; // 5 seconds
const int SSU_TERMINATION_TIMEOUT = 330; // 5.5 minutes
const int SSU_CLOCK_SKEW = 60; // in seconds
const size_t SSU_MAX_I2NP_MESSAGE_SIZE = 32768;
// payload types (4 bits)
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_PEER_TEST = 7;
const uint8_t PAYLOAD_TYPE_SESSION_DESTROYED = 8;
// extended options
const uint16_t EXTENDED_OPTIONS_FLAG_REQUEST_RELAY_TAG = 0x0001;
enum SessionState
{
eSessionStateUnknown,
eSessionStateIntroduced,
eSessionStateEstablished,
eSessionStateClosed,
eSessionStateFailed
};
enum PeerTestParticipant
{
ePeerTestParticipantUnknown = 0,
ePeerTestParticipantAlice1,
ePeerTestParticipantAlice2,
ePeerTestParticipantBob,
ePeerTestParticipantCharlie
};
class SSUServer;
class SSUSession: public TransportSession, public std::enable_shared_from_this<SSUSession>
{
public:
SSUSession (SSUServer& server, boost::asio::ip::udp::endpoint& remoteEndpoint,
std::shared_ptr<const i2p::data::RouterInfo> router = nullptr, bool peerTest = false);
void ProcessNextMessage (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& senderEndpoint);
~SSUSession ();
void Connect ();
void WaitForConnect ();
void Introduce (const i2p::data::RouterInfo::Introducer& introducer,
std::shared_ptr<const i2p::data::RouterInfo> to); // Alice to Charlie
void WaitForIntroduction ();
void Close ();
void Done ();
void Failed ();
const boost::asio::ip::udp::endpoint& GetRemoteEndpoint () { return m_RemoteEndpoint; };
SSUServer& GetServer () { return m_Server; };
bool IsV6 () const { return m_RemoteEndpoint.address ().is_v6 (); };
void SendI2NPMessages (const std::vector<std::shared_ptr<I2NPMessage> >& msgs);
void SendPeerTest (); // Alice
SessionState GetState () const { return m_State; };
size_t GetNumSentBytes () const { return m_NumSentBytes; };
size_t GetNumReceivedBytes () const { return m_NumReceivedBytes; };
void SendKeepAlive ();
uint32_t GetRelayTag () const { return m_RelayTag; };
const i2p::data::RouterInfo::IntroKey& GetIntroKey () const { return m_IntroKey; };
uint32_t GetCreationTime () const { return m_CreationTime; };
void SetCreationTime (uint32_t ts) { m_CreationTime = ts; }; // for introducers
void FlushData ();
void CleanUp (uint64_t ts);
private:
boost::asio::io_service& GetService ();
void CreateAESandMacKey (const uint8_t * pubKey);
size_t GetSSUHeaderSize (const uint8_t * buf) const;
void PostI2NPMessages (std::vector<std::shared_ptr<I2NPMessage> > msgs);
void ProcessMessage (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& senderEndpoint); // call for established session
void ProcessSessionRequest (const uint8_t * buf, size_t len);
void SendSessionRequest ();
void SendRelayRequest (const i2p::data::RouterInfo::Introducer& introducer, uint32_t nonce);
void ProcessSessionCreated (uint8_t * buf, size_t len);
void SendSessionCreated (const uint8_t * x, bool sendRelayTag = true);
void ProcessSessionConfirmed (const uint8_t * buf, size_t len);
void SendSessionConfirmed (const uint8_t * y, const uint8_t * ourAddress, size_t ourAddressLen);
void ProcessRelayRequest (const uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& from);
void SendRelayResponse (uint32_t nonce, const boost::asio::ip::udp::endpoint& from,
const uint8_t * introKey, const boost::asio::ip::udp::endpoint& to);
void SendRelayIntro (std::shared_ptr<SSUSession> session, const boost::asio::ip::udp::endpoint& from);
void ProcessRelayResponse (const uint8_t * buf, size_t len);
void ProcessRelayIntro (const uint8_t * buf, size_t len);
void Established ();
void ScheduleConnectTimer ();
void HandleConnectTimer (const boost::system::error_code& ecode);
void ProcessPeerTest (const uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& senderEndpoint);
void SendPeerTest (uint32_t nonce, const boost::asio::ip::address& address, uint16_t port, const uint8_t * introKey, bool toAddress = true, bool sendAddress = true);
void ProcessData (uint8_t * buf, size_t len);
void SendSessionDestroyed ();
void Send (uint8_t type, const uint8_t * payload, size_t len); // with session key
void Send (const uint8_t * buf, size_t size);
void FillHeaderAndEncrypt (uint8_t payloadType, uint8_t * buf, size_t len, const i2p::crypto::AESKey& aesKey,
const uint8_t * iv, const i2p::crypto::MACKey& macKey, uint8_t flag = 0);
void FillHeaderAndEncrypt (uint8_t payloadType, uint8_t * buf, size_t len); // with session key
void FillHeaderAndEncrypt (uint8_t payloadType, uint8_t * in, size_t len, uint8_t * out); // with session key
void Decrypt (uint8_t * buf, size_t len, const i2p::crypto::AESKey& aesKey);
void DecryptSessionKey (uint8_t * buf, size_t len);
bool Validate (uint8_t * buf, size_t len, const i2p::crypto::MACKey& macKey);
void Reset ();
static size_t ExtractIPAddressAndPort (const uint8_t * buf, size_t len, boost::asio::ip::address& ip, uint16_t& port); // returns actual buf size
private:
friend class SSUData; // TODO: change in later
SSUServer& m_Server;
const boost::asio::ip::udp::endpoint m_RemoteEndpoint;
boost::asio::deadline_timer m_ConnectTimer;
bool m_IsPeerTest;
SessionState m_State;
bool m_IsSessionKey;
uint32_t m_RelayTag; // received from peer
uint32_t m_SentRelayTag; // sent by us
i2p::crypto::CBCEncryption m_SessionKeyEncryption;
i2p::crypto::CBCDecryption m_SessionKeyDecryption;
i2p::crypto::AESKey m_SessionKey;
i2p::crypto::MACKey m_MacKey;
i2p::data::RouterInfo::IntroKey m_IntroKey;
uint32_t m_CreationTime; // seconds since epoch
SSUData m_Data;
bool m_IsDataReceived;
std::unique_ptr<SignedData> m_SignedData; // we need it for SessionConfirmed only
std::map<uint32_t, std::pair <std::shared_ptr<const i2p::data::RouterInfo>, uint64_t > > m_RelayRequests; // nonce->(Charlie, timestamp)
std::shared_ptr<i2p::crypto::DHKeys> m_DHKeysPair; // X - for client and Y - for server
};
}
}
#endif