I2P: End-to-End encrypted and anonymous Internet https://i2pd.website/
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/*
* Copyright (c) 2022, 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 SSU2_SESSION_H__
#define SSU2_SESSION_H__
#include <memory>
#include <functional>
#include <map>
#include <set>
#include <list>
#include <boost/asio.hpp>
#include "Crypto.h"
#include "RouterInfo.h"
#include "TransportSession.h"
namespace i2p
{
namespace transport
{
const int SSU2_CONNECT_TIMEOUT = 5; // 5 seconds
const int SSU2_TERMINATION_TIMEOUT = 330; // 5.5 minutes
const int SSU2_TOKEN_EXPIRATION_TIMEOUT = 9; // in seconds
const int SSU2_RELAY_NONCE_EXPIRATION_TIMEOUT = 10; // in seconds
const int SSU2_PEER_TEST_EXPIRATION_TIMEOUT = 60; // 60 seconds
const size_t SSU2_MTU = 1488;
const size_t SSU2_MAX_PAYLOAD_SIZE = SSU2_MTU - 32;
const int SSU2_RESEND_INTERVAL = 3; // in seconds
const int SSU2_MAX_NUM_RESENDS = 5;
const int SSU2_INCOMPLETE_MESSAGES_CLEANUP_TIMEOUT = 30; // in seconds
const size_t SSU2_MAX_WINDOW_SIZE = 128; // in packets
const int SSU2_MAX_NUM_ACK_RANGES = 32; // to send
enum SSU2MessageType
{
eSSU2SessionRequest = 0,
eSSU2SessionCreated = 1,
eSSU2SessionConfirmed = 2,
eSSU2Data = 6,
eSSU2PeerTest = 7,
eSSU2Retry = 9,
eSSU2TokenRequest = 10,
eSSU2HolePunch = 11
};
enum SSU2BlockType
{
eSSU2BlkDateTime = 0,
eSSU2BlkOptions, // 1
eSSU2BlkRouterInfo, // 2
eSSU2BlkI2NPMessage, // 3
eSSU2BlkFirstFragment, // 4
eSSU2BlkFollowOnFragment, // 5
eSSU2BlkTermination, // 6
eSSU2BlkRelayRequest, // 7
eSSU2BlkRelayResponse, // 8
eSSU2BlkRelayIntro, // 9
eSSU2BlkPeerTest, // 10
eSSU2BlkNextNonce, // 11
eSSU2BlkAck, // 12
eSSU2BlkAddress, // 13
eSSU2BlkIntroKey, // 14
eSSU2BlkRelayTagRequest, // 15
eSSU2BlkRelayTag, // 16
eSSU2BlkNewToken, // 17
eSSU2BlkPathChallenge, // 18
eSSU2BlkPathResponse, // 19
eSSU2BlkFirstPacketNumber, // 20
eSSU2BlkPadding = 254
};
enum SSU2SessionState
{
eSSU2SessionStateUnknown,
eSSU2SessionStateIntroduced,
eSSU2SessionStatePeerTest,
eSSU2SessionStateEstablished,
eSSU2SessionStateTerminated,
eSSU2SessionStateFailed
};
enum SSU2PeerTestCode
{
eSSU2PeerTestCodeAccept = 0,
eSSU2PeerTestCodeBobReasonUnspecified = 1,
eSSU2PeerTestCodeBobNoCharlieAvailable = 2,
eSSU2PeerTestCodeBobLimitExceeded = 3,
eSSU2PeerTestCodeBobSignatureFailure = 4,
eSSU2PeerTestCodeCharlieReasonUnspecified = 64,
eSSU2PeerTestCodeCharlieUnsupportedAddress = 65,
eSSU2PeerTestCodeCharlieLimitExceeded = 66,
eSSU2PeerTestCodeCharlieSignatureFailure = 67,
eSSU2PeerTestCodeCharlieAliceIsAlreadyConnected = 68,
eSSU2PeerTestCodeCharlieAliceIsBanned = 69,
eSSU2PeerTestCodeCharlieAliceIsUnknown = 70,
eSSU2PeerTestCodeUnspecified = 128
};
struct SSU2IncompleteMessage
{
struct Fragment
{
uint8_t buf[SSU2_MTU];
size_t len;
bool isLast;
};
std::shared_ptr<I2NPMessage> msg;
int nextFragmentNum;
uint32_t lastFragmentInsertTime; // in seconds
std::map<int, std::shared_ptr<Fragment> > outOfSequenceFragments;
};
// RouterInfo flags
const uint8_t SSU2_ROUTER_INFO_FLAG_REQUEST_FLOOD = 0x01;
const uint8_t SSU2_ROUTER_INFO_FLAG_GZIP = 0x02;
class SSU2Server;
class SSU2Session: public TransportSession, public std::enable_shared_from_this<SSU2Session>
{
union Header
{
uint64_t ll[2];
uint8_t buf[16];
struct
{
uint64_t connID;
uint32_t packetNum;
uint8_t type;
uint8_t flags[3];
} h;
};
struct SentPacket
{
uint8_t payload[SSU2_MAX_PAYLOAD_SIZE];
size_t payloadSize = 0;
uint32_t nextResendTime; // in seconds
int numResends = 0;
};
struct SessionConfirmedFragment
{
Header header;
uint8_t payload[SSU2_MAX_PAYLOAD_SIZE];
size_t payloadSize;
};
typedef std::function<void ()> OnEstablished;
public:
SSU2Session (SSU2Server& server, std::shared_ptr<const i2p::data::RouterInfo> in_RemoteRouter = nullptr,
std::shared_ptr<const i2p::data::RouterInfo::Address> addr = nullptr);
~SSU2Session ();
void SetRemoteEndpoint (const boost::asio::ip::udp::endpoint& ep) { m_RemoteEndpoint = ep; };
const boost::asio::ip::udp::endpoint& GetRemoteEndpoint () const { return m_RemoteEndpoint; };
i2p::data::RouterInfo::CompatibleTransports GetRemoteTransports () const { return m_RemoteTransports; };
std::shared_ptr<const i2p::data::RouterInfo::Address> GetAddress () const { return m_Address; };
void SetOnEstablished (OnEstablished e) { m_OnEstablished = e; };
void Connect ();
bool Introduce (std::shared_ptr<SSU2Session> session, uint32_t relayTag);
void SendPeerTest (); // Alice, Data message
void Terminate ();
void TerminateByTimeout ();
void CleanUp (uint64_t ts);
void FlushData ();
void Done () override;
void SendLocalRouterInfo (bool update) override;
void SendI2NPMessages (const std::vector<std::shared_ptr<I2NPMessage> >& msgs) override;
void Resend (uint64_t ts);
bool IsEstablished () const { return m_State == eSSU2SessionStateEstablished; };
uint64_t GetConnID () const { return m_SourceConnID; };
SSU2SessionState GetState () const { return m_State; };
void SetState (SSU2SessionState state) { m_State = state; };
bool ProcessFirstIncomingMessage (uint64_t connID, uint8_t * buf, size_t len);
bool ProcessSessionCreated (uint8_t * buf, size_t len);
bool ProcessSessionConfirmed (uint8_t * buf, size_t len);
bool ProcessRetry (uint8_t * buf, size_t len);
bool ProcessHolePunch (uint8_t * buf, size_t len);
bool ProcessPeerTest (uint8_t * buf, size_t len);
void ProcessData (uint8_t * buf, size_t len);
private:
void Established ();
void PostI2NPMessages (std::vector<std::shared_ptr<I2NPMessage> > msgs);
bool SendQueue ();
void SendFragmentedMessage (std::shared_ptr<I2NPMessage> msg);
void ProcessSessionRequest (Header& header, uint8_t * buf, size_t len);
void ProcessTokenRequest (Header& header, uint8_t * buf, size_t len);
void SendSessionRequest (uint64_t token = 0);
void SendSessionCreated (const uint8_t * X);
void SendSessionConfirmed (const uint8_t * Y);
void KDFDataPhase (uint8_t * keydata_ab, uint8_t * keydata_ba);
void SendTokenRequest ();
void SendRetry ();
uint32_t SendData (const uint8_t * buf, size_t len); // returns packet num
void SendQuickAck ();
void SendTermination ();
void SendHolePunch (uint32_t nonce, const boost::asio::ip::udp::endpoint& ep, const uint8_t * introKey);
void SendPeerTest (uint8_t msg, const uint8_t * signedData, size_t signedDataLen, const uint8_t * introKey); // PeerTest message
void HandlePayload (const uint8_t * buf, size_t len);
void HandleAck (const uint8_t * buf, size_t len);
void HandleAckRange (uint32_t firstPacketNum, uint32_t lastPacketNum);
bool ExtractEndpoint (const uint8_t * buf, size_t size, boost::asio::ip::udp::endpoint& ep);
size_t CreateEndpoint (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& ep);
std::shared_ptr<const i2p::data::RouterInfo::Address> FindLocalAddress () const;
std::shared_ptr<const i2p::data::RouterInfo> ExtractRouterInfo (const uint8_t * buf, size_t size);
void CreateNonce (uint64_t seqn, uint8_t * nonce);
bool UpdateReceivePacketNum (uint32_t packetNum); // for Ack, returns false if duplicate
void HandleFirstFragment (const uint8_t * buf, size_t len);
void HandleFollowOnFragment (const uint8_t * buf, size_t len);
bool ConcatOutOfSequenceFragments (std::shared_ptr<SSU2IncompleteMessage> m); // true if message complete
void HandleRelayRequest (const uint8_t * buf, size_t len);
void HandleRelayIntro (const uint8_t * buf, size_t len);
void HandleRelayResponse (const uint8_t * buf, size_t len);
void HandlePeerTest (const uint8_t * buf, size_t len);
size_t CreateAddressBlock (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& ep);
size_t CreateRouterInfoBlock (uint8_t * buf, size_t len, std::shared_ptr<const i2p::data::RouterInfo> r);
size_t CreateAckBlock (uint8_t * buf, size_t len);
size_t CreatePaddingBlock (uint8_t * buf, size_t len, size_t minSize = 0);
size_t CreateI2NPBlock (uint8_t * buf, size_t len, std::shared_ptr<I2NPMessage>&& msg);
size_t CreateFirstFragmentBlock (uint8_t * buf, size_t len, std::shared_ptr<I2NPMessage> msg);
size_t CreateFollowOnFragmentBlock (uint8_t * buf, size_t len, std::shared_ptr<I2NPMessage> msg, uint8_t& fragmentNum, uint32_t msgID);
size_t CreateRelayIntroBlock (uint8_t * buf, size_t len, const uint8_t * introData, size_t introDataLen);
size_t CreateRelayResponseBlock (uint8_t * buf, size_t len, uint32_t nonce); // Charlie
size_t CreatePeerTestBlock (uint8_t * buf, size_t len, uint8_t msg, SSU2PeerTestCode code, const uint8_t * routerHash, const uint8_t * signedData, size_t signedDataLen);
size_t CreatePeerTestBlock (uint8_t * buf, size_t len, uint32_t nonce); // Alice
private:
SSU2Server& m_Server;
std::shared_ptr<i2p::crypto::X25519Keys> m_EphemeralKeys;
std::unique_ptr<i2p::crypto::NoiseSymmetricState> m_NoiseState;
std::unique_ptr<SessionConfirmedFragment> m_SessionConfirmedFragment1; // for Bob if applicable
std::shared_ptr<const i2p::data::RouterInfo::Address> m_Address;
boost::asio::ip::udp::endpoint m_RemoteEndpoint;
i2p::data::RouterInfo::CompatibleTransports m_RemoteTransports; // for peer tests
uint64_t m_DestConnID, m_SourceConnID;
SSU2SessionState m_State;
uint8_t m_KeyDataSend[64], m_KeyDataReceive[64];
uint32_t m_SendPacketNum, m_ReceivePacketNum;
std::set<uint32_t> m_OutOfSequencePackets; // packet nums > receive packet num
std::map<uint32_t, std::shared_ptr<SentPacket> > m_SentPackets; // packetNum -> packet
std::map<uint32_t, std::shared_ptr<SSU2IncompleteMessage> > m_IncompleteMessages; // I2NP
std::map<uint32_t, std::pair <std::shared_ptr<SSU2Session>, uint64_t > > m_RelaySessions; // nonce->(Alice, timestamp) for Bob or nonce->(Charlie, timestamp) for Alice
std::map<uint32_t, std::pair <std::shared_ptr<SSU2Session>, uint64_t > > m_PeerTests; // same as for relay sessions
std::list<std::shared_ptr<I2NPMessage> > m_SendQueue;
i2p::I2NPMessagesHandler m_Handler;
bool m_IsDataReceived;
size_t m_WindowSize;
uint32_t m_RelayTag; // between Bob and Charlie
OnEstablished m_OnEstablished; // callback from Established
};
inline uint64_t CreateHeaderMask (const uint8_t * kh, const uint8_t * nonce)
{
uint64_t data = 0;
i2p::crypto::ChaCha20 ((uint8_t *)&data, 8, kh, nonce, (uint8_t *)&data);
return data;
}
}
}
#endif