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i2pd/libi2pd/SSU2Session.h

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/*
* Copyright (c) 2022-2024, 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 "RouterContext.h"
#include "TransportSession.h"
namespace i2p
{
namespace transport
{
const int SSU2_CONNECT_TIMEOUT = 5; // 5 seconds
const int SSU2_TERMINATION_TIMEOUT = 165; // in seconds
const int SSU2_CLOCK_SKEW = 60; // in seconds
const int SSU2_CLOCK_THRESHOLD = 15; // in seconds, if more we should adjust
const int SSU2_TOKEN_EXPIRATION_TIMEOUT = 9; // for Retry message, in seconds
const int SSU2_NEXT_TOKEN_EXPIRATION_TIMEOUT = 52*60; // for next token block, in seconds
const int SSU2_TOKEN_EXPIRATION_THRESHOLD = 2; // 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_MAX_PACKET_SIZE = 1500;
const size_t SSU2_MIN_PACKET_SIZE = 1280;
const int SSU2_HANDSHAKE_RESEND_INTERVAL = 1000; // in milliseconds
const int SSU2_MAX_NUM_RESENDS = 5;
const int SSU2_INCOMPLETE_MESSAGES_CLEANUP_TIMEOUT = 30; // in seconds
const int SSU2_MAX_NUM_RECEIVED_I2NP_MSGIDS = 5000; // how many msgID we store for duplicates check
const int SSU2_RECEIVED_I2NP_MSGIDS_CLEANUP_TIMEOUT = 10; // in seconds
const int SSU2_DECAY_INTERVAL = 20; // in seconds
const size_t SSU2_MIN_WINDOW_SIZE = 16; // in packets
const size_t SSU2_MAX_WINDOW_SIZE = 256; // in packets
const size_t SSU2_MIN_RTO = 100; // in milliseconds
const size_t SSU2_INITIAL_RTO = 540; // in milliseconds
const size_t SSU2_MAX_RTO = 2500; // in milliseconds
const double SSU2_UNKNOWN_RTT = -1;
const double SSU2_RTT_EWMA_ALPHA = 0.125;
const float SSU2_kAPPA = 1.8;
const int SSU2_MAX_NUM_ACNT = 255; // acnt, acks or nacks
const int SSU2_MAX_NUM_ACK_PACKETS = 511; // ackthrough + acnt + 1 range
const int SSU2_MAX_NUM_ACK_RANGES = 32; // to send
const uint8_t SSU2_MAX_NUM_FRAGMENTS = 64;
const int SSU2_SEND_DATETIME_NUM_PACKETS = 256;
// flags
const uint8_t SSU2_FLAG_IMMEDIATE_ACK_REQUESTED = 0x01;
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,
eSSU2SessionStateTokenReceived,
eSSU2SessionStateSessionRequestSent,
eSSU2SessionStateSessionRequestReceived,
eSSU2SessionStateSessionCreatedSent,
eSSU2SessionStateSessionCreatedReceived,
eSSU2SessionStateSessionConfirmedSent,
eSSU2SessionStateEstablished,
eSSU2SessionStateClosing,
eSSU2SessionStateClosingConfirmed,
eSSU2SessionStateTerminated,
eSSU2SessionStateFailed,
eSSU2SessionStateIntroduced,
eSSU2SessionStatePeerTest,
eSSU2SessionStatePeerTestReceived, // 5 before 4
eSSU2SessionStateTokenRequestReceived
};
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
};
enum SSU2RelayResponseCode
{
eSSU2RelayResponseCodeAccept = 0,
eSSU2RelayResponseCodeBobRelayTagNotFound = 5,
eSSU2RelayResponseCodeCharlieUnsupportedAddress = 65,
eSSU2RelayResponseCodeCharlieSignatureFailure = 67,
eSSU2RelayResponseCodeCharlieAliceIsUnknown = 70
};
enum SSU2TerminationReason
{
eSSU2TerminationReasonNormalClose = 0,
eSSU2TerminationReasonTerminationReceived = 1,
eSSU2TerminationReasonIdleTimeout = 2,
eSSU2TerminationReasonRouterShutdown = 3,
eSSU2TerminationReasonDataPhaseAEADFailure= 4,
eSSU2TerminationReasonIncompatibleOptions = 5,
eSSU2TerminationReasonTncompatibleSignatureType = 6,
eSSU2TerminationReasonClockSkew = 7,
eSSU2TerminationPaddingViolation = 8,
eSSU2TerminationReasonAEADFramingError = 9,
eSSU2TerminationReasonPayloadFormatError = 10,
eSSU2TerminationReasonSessionRequestError = 11,
eSSU2TerminationReasonSessionCreatedError = 12,
eSSU2TerminationReasonSessionConfirmedError = 13,
eSSU2TerminationReasonTimeout = 14,
eSSU2TerminationReasonRouterInfoSignatureVerificationFail = 15,
eSSU2TerminationReasonInvalidS = 16,
eSSU2TerminationReasonBanned = 17,
eSSU2TerminationReasonBadToken = 18,
eSSU2TerminationReasonConnectionLimits = 19,
eSSU2TerminationReasonIncompatibleVersion = 20,
eSSU2TerminationReasonWrongNetID = 21,
eSSU2TerminationReasonReplacedByNewSession = 22
};
struct SSU2IncompleteMessage
{
struct Fragment
{
uint8_t buf[SSU2_MAX_PACKET_SIZE];
size_t len;
int fragmentNum;
bool isLast;
std::shared_ptr<Fragment> next;
};
std::shared_ptr<I2NPMessage> msg;
int nextFragmentNum;
uint32_t lastFragmentInsertTime; // in seconds
std::shared_ptr<Fragment> outOfSequenceFragments; // #1 and more
void AttachNextFragment (const uint8_t * fragment, size_t fragmentSize);
bool ConcatOutOfSequenceFragments (); // true if message complete
void AddOutOfSequenceFragment (std::shared_ptr<Fragment> fragment);
};
struct SSU2SentPacket
{
uint8_t payload[SSU2_MAX_PACKET_SIZE];
size_t payloadSize = 0;
uint64_t sendTime; // in milliseconds
int numResends = 0;
};
// 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 HandshakePacket
{
Header header;
uint8_t headerX[48]; // part1 for SessionConfirmed
uint8_t payload[SSU2_MAX_PACKET_SIZE*2];
size_t payloadSize = 0;
uint64_t sendTime = 0; // in milliseconds
bool isSecondFragment = false; // for SessionConfirmed
};
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; };
i2p::data::RouterInfo::CompatibleTransports GetRemotePeerTestTransports () const { return m_RemotePeerTestTransports; };
std::shared_ptr<const i2p::data::RouterInfo::Address> GetAddress () const { return m_Address; };
void SetOnEstablished (OnEstablished e) { m_OnEstablished = e; };
OnEstablished GetOnEstablished () const { return m_OnEstablished; };
void Connect ();
bool Introduce (std::shared_ptr<SSU2Session> session, uint32_t relayTag);
void WaitForIntroduction ();
void SendPeerTest (); // Alice, Data message
void SendKeepAlive ();
void RequestTermination (SSU2TerminationReason reason);
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;
uint32_t GetRelayTag () const override { return m_RelayTag; };
size_t Resend (uint64_t ts); // return number or resent packets
bool IsEstablished () const override { 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, const boost::asio::ip::udp::endpoint& from);
private:
void Terminate ();
void Established ();
void ScheduleConnectTimer ();
void HandleConnectTimer (const boost::system::error_code& ecode);
void PostI2NPMessages (std::vector<std::shared_ptr<I2NPMessage> > msgs);
bool SendQueue (); // returns true if ack block was sent
bool SendFragmentedMessage (std::shared_ptr<I2NPMessage> msg);
void ResendHandshakePacket ();
void ConnectAfterIntroduction ();
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, uint8_t flags = 0); // returns packet num
void SendQuickAck ();
void SendTermination ();
void SendHolePunch (uint32_t nonce, const boost::asio::ip::udp::endpoint& ep, const uint8_t * introKey, uint64_t token);
void SendPeerTest (uint8_t msg, const uint8_t * signedData, size_t signedDataLen, const uint8_t * introKey); // PeerTest message
void SendPathResponse (const uint8_t * data, size_t len);
void SendPathChallenge ();
void HandlePayload (const uint8_t * buf, size_t len);
void HandleDateTime (const uint8_t * buf, size_t len);
void HandleAck (const uint8_t * buf, size_t len);
void HandleAckRange (uint32_t firstPacketNum, uint32_t lastPacketNum, uint64_t ts);
void HandleAddress (const uint8_t * buf, size_t len);
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;
void AdjustMaxPayloadSize ();
RouterStatus GetRouterStatus () const;
void SetRouterStatus (RouterStatus status) const;
bool GetTestingState () const;
void SetTestingState(bool testing) 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);
void HandleRelayRequest (const uint8_t * buf, size_t len);
void HandleRelayIntro (const uint8_t * buf, size_t len, int attempts = 0);
void HandleRelayResponse (const uint8_t * buf, size_t len);
void HandlePeerTest (const uint8_t * buf, size_t len);
void HandleI2NPMsg (std::shared_ptr<I2NPMessage>&& msg);
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, SSU2RelayResponseCode code, uint32_t nonce, uint64_t token, bool v4);
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
size_t CreateTerminationBlock (uint8_t * buf, size_t len);
private:
SSU2Server& m_Server;
std::shared_ptr<i2p::crypto::X25519Keys> m_EphemeralKeys;
std::unique_ptr<i2p::crypto::NoiseSymmetricState> m_NoiseState;
std::unique_ptr<HandshakePacket> m_SessionConfirmedFragment; // for Bob if applicable or second fragment for Alice
std::unique_ptr<HandshakePacket> m_SentHandshakePacket; // SessionRequest, SessionCreated or SessionConfirmed
std::shared_ptr<const i2p::data::RouterInfo::Address> m_Address;
boost::asio::ip::udp::endpoint m_RemoteEndpoint;
i2p::data::RouterInfo::CompatibleTransports m_RemoteTransports, m_RemotePeerTestTransports;
uint64_t m_DestConnID, m_SourceConnID;
SSU2SessionState m_State;
uint8_t m_KeyDataSend[64], m_KeyDataReceive[64];
uint32_t m_SendPacketNum, m_ReceivePacketNum, m_LastDatetimeSentPacketNum;
std::set<uint32_t> m_OutOfSequencePackets; // packet nums > receive packet num
std::map<uint32_t, std::shared_ptr<SSU2SentPacket> > m_SentPackets; // packetNum -> packet
std::unordered_map<uint32_t, std::shared_ptr<SSU2IncompleteMessage> > m_IncompleteMessages; // msgID -> 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;
double m_RTT;
int m_MsgLocalExpirationTimeout;
int m_MsgLocalSemiExpirationTimeout;
size_t m_WindowSize, m_RTO;
uint32_t m_RelayTag; // between Bob and Charlie
OnEstablished m_OnEstablished; // callback from Established
boost::asio::deadline_timer m_ConnectTimer;
SSU2TerminationReason m_TerminationReason;
size_t m_MaxPayloadSize;
std::unique_ptr<i2p::data::IdentHash> m_PathChallenge;
std::unordered_map<uint32_t, uint32_t> m_ReceivedI2NPMsgIDs; // msgID -> timestamp in seconds
};
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