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i2pd/libi2pd/SSU2Session.cpp

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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
*/
#include <string.h>
#include <openssl/rand.h>
#include "Log.h"
#include "Transports.h"
#include "Gzip.h"
#include "NetDb.hpp"
#include "SSU2.h"
namespace i2p
{
namespace transport
{
void SSU2IncompleteMessage::AttachNextFragment (const uint8_t * fragment, size_t fragmentSize)
{
if (msg->len + fragmentSize > msg->maxLen)
{
LogPrint (eLogInfo, "SSU2: I2NP message size ", msg->maxLen, " is not enough");
auto newMsg = NewI2NPMessage ();
*newMsg = *msg;
msg = newMsg;
}
if (msg->Concat (fragment, fragmentSize) < fragmentSize)
LogPrint (eLogError, "SSU2: I2NP buffer overflow ", msg->maxLen);
nextFragmentNum++;
}
SSU2Session::SSU2Session (SSU2Server& server, std::shared_ptr<const i2p::data::RouterInfo> in_RemoteRouter,
std::shared_ptr<const i2p::data::RouterInfo::Address> addr):
TransportSession (in_RemoteRouter, SSU2_CONNECT_TIMEOUT),
m_Server (server), m_Address (addr), m_RemoteTransports (0),
m_DestConnID (0), m_SourceConnID (0), m_State (eSSU2SessionStateUnknown),
m_SendPacketNum (0), m_ReceivePacketNum (0), m_IsDataReceived (false),
m_WindowSize (SSU2_MIN_WINDOW_SIZE), m_RTT (SSU2_RESEND_INTERVAL),
m_RTO (SSU2_RESEND_INTERVAL*SSU2_kAPPA), m_RelayTag (0),
m_ConnectTimer (server.GetService ()), m_TerminationReason (eSSU2TerminationReasonNormalClose),
m_MaxPayloadSize (SSU2_MIN_PACKET_SIZE - IPV6_HEADER_SIZE - UDP_HEADER_SIZE - 32) // min size
{
m_NoiseState.reset (new i2p::crypto::NoiseSymmetricState);
if (in_RemoteRouter && m_Address)
{
// outgoing
InitNoiseXKState1 (*m_NoiseState, m_Address->s);
m_RemoteEndpoint = boost::asio::ip::udp::endpoint (m_Address->host, m_Address->port);
m_RemoteTransports = in_RemoteRouter->GetCompatibleTransports (false);
RAND_bytes ((uint8_t *)&m_DestConnID, 8);
RAND_bytes ((uint8_t *)&m_SourceConnID, 8);
}
else
{
// incoming
InitNoiseXKState1 (*m_NoiseState, i2p::context.GetSSU2StaticPublicKey ());
}
}
SSU2Session::~SSU2Session ()
{
}
void SSU2Session::Connect ()
{
if (m_State == eSSU2SessionStateUnknown || m_State == eSSU2SessionStateTokenReceived)
{
ScheduleConnectTimer ();
auto token = m_Server.FindOutgoingToken (m_RemoteEndpoint);
if (token)
SendSessionRequest (token);
else
{
m_State = eSSU2SessionStateUnknown;
SendTokenRequest ();
}
}
}
void SSU2Session::ScheduleConnectTimer ()
{
m_ConnectTimer.cancel ();
m_ConnectTimer.expires_from_now (boost::posix_time::seconds(SSU2_CONNECT_TIMEOUT));
m_ConnectTimer.async_wait (std::bind (&SSU2Session::HandleConnectTimer,
shared_from_this (), std::placeholders::_1));
}
void SSU2Session::HandleConnectTimer (const boost::system::error_code& ecode)
{
if (!ecode)
{
// timeout expired
LogPrint (eLogWarning, "SSU2: Session with ", m_RemoteEndpoint, " was not established after ", SSU2_CONNECT_TIMEOUT, " seconds");
Terminate ();
}
}
bool SSU2Session::Introduce (std::shared_ptr<SSU2Session> session, uint32_t relayTag)
{
// we are Alice
if (!session || !relayTag) return false;
// find local adddress to introduce
auto localAddress = session->FindLocalAddress ();
if (!localAddress) return false;
// create nonce
uint32_t nonce;
RAND_bytes ((uint8_t *)&nonce, 4);
auto ts = i2p::util::GetSecondsSinceEpoch ();
// payload
uint8_t payload[SSU2_MAX_PACKET_SIZE];
size_t payloadSize = 0;
payload[0] = eSSU2BlkRelayRequest;
payload[3] = 0; // flag
htobe32buf (payload + 4, nonce);
htobe32buf (payload + 8, relayTag);
htobe32buf (payload + 12, ts);
payload[16] = 2; // ver
size_t asz = CreateEndpoint (payload + 18, m_MaxPayloadSize - 18, boost::asio::ip::udp::endpoint (localAddress->host, localAddress->port));
if (!asz) return false;
payload[17] = asz;
payloadSize += asz + 18;
SignedData s;
s.Insert ((const uint8_t *)"RelayRequestData", 16); // prologue
s.Insert (GetRemoteIdentity ()->GetIdentHash (), 32); // bhash
s.Insert (session->GetRemoteIdentity ()->GetIdentHash (), 32); // chash
s.Insert (payload + 4, 14 + asz); // nonce, relay tag, timestamp, ver, asz and Alice's endpoint
s.Sign (i2p::context.GetPrivateKeys (), payload + payloadSize);
payloadSize += i2p::context.GetIdentity ()->GetSignatureLen ();
htobe16buf (payload + 1, payloadSize - 3); // size
payloadSize += CreatePaddingBlock (payload + payloadSize, m_MaxPayloadSize - payloadSize);
// send
m_RelaySessions.emplace (nonce, std::make_pair (session, ts));
session->m_SourceConnID = htobe64 (((uint64_t)nonce << 32) | nonce);
session->m_DestConnID = ~session->m_SourceConnID;
m_Server.AddSession (session);
SendData (payload, payloadSize);
return true;
}
void SSU2Session::WaitForIntroduction ()
{
m_State = eSSU2SessionStateIntroduced;
ScheduleConnectTimer ();
}
void SSU2Session::SendPeerTest ()
{
// we are Alice
uint32_t nonce;
RAND_bytes ((uint8_t *)&nonce, 4);
auto ts = i2p::util::GetSecondsSinceEpoch ();
// session for message 5
auto session = std::make_shared<SSU2Session> (m_Server);
session->SetState (eSSU2SessionStatePeerTest);
m_PeerTests.emplace (nonce, std::make_pair (session, ts));
session->m_SourceConnID = htobe64 (((uint64_t)nonce << 32) | nonce);
session->m_DestConnID = ~session->m_SourceConnID;
m_Server.AddSession (session);
// peer test block
uint8_t payload[SSU2_MAX_PACKET_SIZE];
size_t payloadSize = CreatePeerTestBlock (payload, m_MaxPayloadSize, nonce);
if (payloadSize > 0)
{
payloadSize += CreatePaddingBlock (payload + payloadSize, m_MaxPayloadSize - payloadSize);
SendData (payload, payloadSize);
}
}
void SSU2Session::SendKeepAlive ()
{
if (IsEstablished ())
{
uint8_t payload[20];
size_t payloadSize = CreatePaddingBlock (payload, 20, 5);
SendData (payload, payloadSize);
}
}
void SSU2Session::Terminate ()
{
if (m_State != eSSU2SessionStateTerminated)
{
m_State = eSSU2SessionStateTerminated;
m_ConnectTimer.cancel ();
m_OnEstablished = nullptr;
if (m_RelayTag)
m_Server.RemoveRelay (m_RelayTag);
m_SentHandshakePacket.reset (nullptr);
m_SendQueue.clear ();
m_SentPackets.clear ();
m_IncompleteMessages.clear ();
m_RelaySessions.clear ();
m_PeerTests.clear ();
m_Server.RemoveSession (m_SourceConnID);
transports.PeerDisconnected (shared_from_this ());
LogPrint (eLogDebug, "SSU2: Session terminated");
}
}
void SSU2Session::RequestTermination (SSU2TerminationReason reason)
{
if (m_State == eSSU2SessionStateEstablished || m_State == eSSU2SessionStateClosing)
{
m_TerminationReason = reason;
SendTermination ();
}
m_State = eSSU2SessionStateClosing;
}
void SSU2Session::Established ()
{
m_State = eSSU2SessionStateEstablished;
m_EphemeralKeys = nullptr;
m_NoiseState.reset (nullptr);
m_SessionConfirmedFragment.reset (nullptr);
m_SentHandshakePacket.reset (nullptr);
m_ConnectTimer.cancel ();
SetTerminationTimeout (SSU2_TERMINATION_TIMEOUT);
transports.PeerConnected (shared_from_this ());
if (m_OnEstablished)
{
m_OnEstablished ();
m_OnEstablished = nullptr;
}
}
void SSU2Session::Done ()
{
m_Server.GetService ().post (std::bind (&SSU2Session::Terminate, shared_from_this ()));
}
void SSU2Session::SendLocalRouterInfo (bool update)
{
if (update || !IsOutgoing ())
{
auto s = shared_from_this ();
m_Server.GetService ().post ([s]()
{
if (!s->IsEstablished ()) return;
uint8_t payload[SSU2_MAX_PACKET_SIZE];
size_t payloadSize = s->CreateRouterInfoBlock (payload, s->m_MaxPayloadSize - 32, i2p::context.GetSharedRouterInfo ());
if (payloadSize)
{
if (payloadSize < s->m_MaxPayloadSize)
payloadSize += s->CreatePaddingBlock (payload + payloadSize, s->m_MaxPayloadSize - payloadSize);
s->SendData (payload, payloadSize);
}
else
s->SendFragmentedMessage (CreateDatabaseStoreMsg ());
});
}
}
void SSU2Session::SendI2NPMessages (const std::vector<std::shared_ptr<I2NPMessage> >& msgs)
{
m_Server.GetService ().post (std::bind (&SSU2Session::PostI2NPMessages, shared_from_this (), msgs));
}
void SSU2Session::PostI2NPMessages (std::vector<std::shared_ptr<I2NPMessage> > msgs)
{
if (m_State == eSSU2SessionStateTerminated) return;
for (auto it: msgs)
m_SendQueue.push_back (it);
SendQueue ();
if (m_SendQueue.size () > SSU2_MAX_OUTGOING_QUEUE_SIZE)
{
LogPrint (eLogWarning, "SSU2: Outgoing messages queue size to ",
GetIdentHashBase64(), " exceeds ", SSU2_MAX_OUTGOING_QUEUE_SIZE);
RequestTermination (eSSU2TerminationReasonTimeout);
}
}
bool SSU2Session::SendQueue ()
{
if (!m_SendQueue.empty () && m_SentPackets.size () <= m_WindowSize)
{
auto ts = i2p::util::GetMillisecondsSinceEpoch ();
auto packet = m_Server.GetSentPacketsPool ().AcquireShared ();
size_t ackBlockSize = CreateAckBlock (packet->payload, m_MaxPayloadSize);
bool ackBlockSent = false;
packet->payloadSize += ackBlockSize;
while (!m_SendQueue.empty () && m_SentPackets.size () <= m_WindowSize)
{
auto msg = m_SendQueue.front ();
size_t len = msg->GetNTCP2Length () + 3;
if (len > m_MaxPayloadSize) // message too long
{
m_SendQueue.pop_front ();
if (SendFragmentedMessage (msg))
ackBlockSent = true;
}
else if (packet->payloadSize + len <= m_MaxPayloadSize)
{
m_SendQueue.pop_front ();
packet->payloadSize += CreateI2NPBlock (packet->payload + packet->payloadSize, m_MaxPayloadSize - packet->payloadSize, std::move (msg));
}
else
{
// create new packet and copy ack block
auto newPacket = m_Server.GetSentPacketsPool ().AcquireShared ();
memcpy (newPacket->payload, packet->payload, ackBlockSize);
newPacket->payloadSize = ackBlockSize;
// complete current packet
if (packet->payloadSize > ackBlockSize) // more than just ack block
{
ackBlockSent = true;
// try to add padding
if (packet->payloadSize + 16 < m_MaxPayloadSize)
packet->payloadSize += CreatePaddingBlock (packet->payload + packet->payloadSize, m_MaxPayloadSize - packet->payloadSize);
}
else
{
// reduce ack block
if (len + 8 < m_MaxPayloadSize)
{
// keep Ack block and drop some ranges
ackBlockSent = true;
packet->payloadSize = m_MaxPayloadSize - len;
if (packet->payloadSize & 0x01) packet->payloadSize--; // make it even
htobe16buf (packet->payload + 1, packet->payloadSize - 3); // new block size
}
else // drop Ack block completely
packet->payloadSize = 0;
// msg fits single packet
m_SendQueue.pop_front ();
packet->payloadSize += CreateI2NPBlock (packet->payload + packet->payloadSize, m_MaxPayloadSize - packet->payloadSize, std::move (msg));
}
// send right a way
uint32_t packetNum = SendData (packet->payload, packet->payloadSize);
packet->sendTime = ts;
m_SentPackets.emplace (packetNum, packet);
packet = newPacket; // just ack block
}
};
if (packet->payloadSize > ackBlockSize)
{
ackBlockSent = true;
if (packet->payloadSize + 16 < m_MaxPayloadSize)
packet->payloadSize += CreatePaddingBlock (packet->payload + packet->payloadSize, m_MaxPayloadSize - packet->payloadSize);
uint32_t packetNum = SendData (packet->payload, packet->payloadSize);
packet->sendTime = ts;
m_SentPackets.emplace (packetNum, packet);
}
return ackBlockSent;
}
return false;
}
bool SSU2Session::SendFragmentedMessage (std::shared_ptr<I2NPMessage> msg)
{
size_t lastFragmentSize = (msg->GetNTCP2Length () + 3 - m_MaxPayloadSize) % (m_MaxPayloadSize - 8);
size_t extraSize = m_MaxPayloadSize - lastFragmentSize;
bool ackBlockSent = false;
uint32_t msgID;
memcpy (&msgID, msg->GetHeader () + I2NP_HEADER_MSGID_OFFSET, 4);
auto ts = i2p::util::GetMillisecondsSinceEpoch ();
auto packet = m_Server.GetSentPacketsPool ().AcquireShared ();
if (extraSize >= 8)
{
packet->payloadSize = CreateAckBlock (packet->payload, extraSize);
ackBlockSent = true;
if (packet->payloadSize + 12 < m_MaxPayloadSize)
{
uint32_t packetNum = SendData (packet->payload, packet->payloadSize);
packet->sendTime = ts;
m_SentPackets.emplace (packetNum, packet);
packet = m_Server.GetSentPacketsPool ().AcquireShared ();
}
else
extraSize -= packet->payloadSize;
}
size_t offset = extraSize > 0 ? (rand () % extraSize) : 0;
if (offset + packet->payloadSize >= m_MaxPayloadSize) offset = 0;
auto size = CreateFirstFragmentBlock (packet->payload + packet->payloadSize, m_MaxPayloadSize - offset - packet->payloadSize, msg);
if (!size) return false;
extraSize -= offset;
packet->payloadSize += size;
uint32_t firstPacketNum = SendData (packet->payload, packet->payloadSize);
packet->sendTime = ts;
m_SentPackets.emplace (firstPacketNum, packet);
uint8_t fragmentNum = 0;
while (msg->offset < msg->len)
{
offset = extraSize > 0 ? (rand () % extraSize) : 0;
packet = m_Server.GetSentPacketsPool ().AcquireShared ();
packet->payloadSize = CreateFollowOnFragmentBlock (packet->payload, m_MaxPayloadSize - offset, msg, fragmentNum, msgID);
extraSize -= offset;
if (msg->offset >= msg->len && packet->payloadSize + 16 < m_MaxPayloadSize) // last fragment
packet->payloadSize += CreatePaddingBlock (packet->payload + packet->payloadSize, m_MaxPayloadSize - packet->payloadSize);
uint32_t followonPacketNum = SendData (packet->payload, packet->payloadSize);
packet->sendTime = ts;
m_SentPackets.emplace (followonPacketNum, packet);
}
return ackBlockSent;
}
void SSU2Session::Resend (uint64_t ts)
{
// resend handshake packet
if (m_SentHandshakePacket && ts >= m_SentHandshakePacket->sendTime + SSU2_HANDSHAKE_RESEND_INTERVAL)
{
LogPrint (eLogDebug, "SSU2: Resending ", (int)m_State);
ResendHandshakePacket ();
m_SentHandshakePacket->sendTime = ts;
return;
}
// resend data packets
if (m_SentPackets.empty ()) return;
std::map<uint32_t, std::shared_ptr<SSU2SentPacket> > resentPackets;
for (auto it = m_SentPackets.begin (); it != m_SentPackets.end (); )
if (ts >= it->second->sendTime + it->second->numResends*m_RTO)
{
if (it->second->numResends > SSU2_MAX_NUM_RESENDS)
{
LogPrint (eLogInfo, "SSU2: Packet was not Acked after ", it->second->numResends, " attempts. Terminate session");
m_SentPackets.clear ();
m_SendQueue.clear ();
RequestTermination (eSSU2TerminationReasonTimeout);
return;
}
else
{
uint32_t packetNum = SendData (it->second->payload, it->second->payloadSize);
it->second->numResends++;
it->second->sendTime = ts;
resentPackets.emplace (packetNum, it->second);
it = m_SentPackets.erase (it);
}
}
else
it++;
if (!resentPackets.empty ())
{
#if (__cplusplus >= 201703L) // C++ 17 or higher
m_SentPackets.merge (resentPackets);
#else
m_SentPackets.insert (resentPackets.begin (), resentPackets.end ());
#endif
m_WindowSize >>= 1; // /2
if (m_WindowSize < SSU2_MIN_WINDOW_SIZE) m_WindowSize = SSU2_MIN_WINDOW_SIZE;
}
SendQueue ();
}
void SSU2Session::ResendHandshakePacket ()
{
if (m_SentHandshakePacket)
{
m_Server.Send (m_SentHandshakePacket->header.buf, 16, m_SentHandshakePacket->headerX, 48,
m_SentHandshakePacket->payload, m_SentHandshakePacket->payloadSize, m_RemoteEndpoint);
if (m_SessionConfirmedFragment && m_State == eSSU2SessionStateSessionConfirmedSent)
// resend second fragment of SessionConfirmed
m_Server.Send (m_SessionConfirmedFragment->header.buf, 16,
m_SessionConfirmedFragment->payload, m_SessionConfirmedFragment->payloadSize, m_RemoteEndpoint);
}
}
bool SSU2Session::ProcessFirstIncomingMessage (uint64_t connID, uint8_t * buf, size_t len)
{
// we are Bob
m_SourceConnID = connID;
Header header;
header.h.connID = connID;
memcpy (header.buf + 8, buf + 8, 8);
header.ll[1] ^= CreateHeaderMask (i2p::context.GetSSU2IntroKey (), buf + (len - 12));
switch (header.h.type)
{
case eSSU2SessionRequest:
ProcessSessionRequest (header, buf, len);
break;
case eSSU2TokenRequest:
ProcessTokenRequest (header, buf, len);
break;
case eSSU2PeerTest:
{
// TODO: remove later
const uint8_t nonce[12] = {0};
uint64_t headerX[2];
i2p::crypto::ChaCha20 (buf + 16, 16, i2p::context.GetSSU2IntroKey (), nonce, (uint8_t *)headerX);
LogPrint (eLogWarning, "SSU2: Unexpected PeerTest message SourceConnID=", connID, " DestConnID=", headerX[0]);
break;
}
default:
{
LogPrint (eLogWarning, "SSU2: Unexpected message type ", (int)header.h.type, " from ", m_RemoteEndpoint, " of ", len, " bytes");
return false;
}
}
return true;
}
void SSU2Session::SendSessionRequest (uint64_t token)
{
// we are Alice
m_EphemeralKeys = i2p::transport::transports.GetNextX25519KeysPair ();
m_SentHandshakePacket.reset (new HandshakePacket);
auto ts = i2p::util::GetMillisecondsSinceEpoch ();
m_SentHandshakePacket->sendTime = ts;
Header& header = m_SentHandshakePacket->header;
uint8_t * headerX = m_SentHandshakePacket->headerX,
* payload = m_SentHandshakePacket->payload;
// fill packet
header.h.connID = m_DestConnID; // dest id
header.h.packetNum = 0;
header.h.type = eSSU2SessionRequest;
header.h.flags[0] = 2; // ver
header.h.flags[1] = (uint8_t)i2p::context.GetNetID (); // netID
header.h.flags[2] = 0; // flag
memcpy (headerX, &m_SourceConnID, 8); // source id
memcpy (headerX + 8, &token, 8); // token
memcpy (headerX + 16, m_EphemeralKeys->GetPublicKey (), 32); // X
// payload
payload[0] = eSSU2BlkDateTime;
htobe16buf (payload + 1, 4);
htobe32buf (payload + 3, ts/1000);
size_t payloadSize = 7;
if (GetRouterStatus () == eRouterStatusFirewalled && m_Address->IsIntroducer ())
{
// relay tag request
payload[payloadSize] = eSSU2BlkRelayTagRequest;
memset (payload + payloadSize + 1, 0, 2); // size = 0
payloadSize += 3;
}
payloadSize += CreatePaddingBlock (payload + payloadSize, 40 - payloadSize, 1);
// KDF for session request
m_NoiseState->MixHash ({ {header.buf, 16}, {headerX, 16} }); // h = SHA256(h || header)
m_NoiseState->MixHash (m_EphemeralKeys->GetPublicKey (), 32); // h = SHA256(h || aepk);
uint8_t sharedSecret[32];
m_EphemeralKeys->Agree (m_Address->s, sharedSecret);
m_NoiseState->MixKey (sharedSecret);
// encrypt
const uint8_t nonce[12] = {0};
i2p::crypto::AEADChaCha20Poly1305 (payload, payloadSize, m_NoiseState->m_H, 32, m_NoiseState->m_CK + 32, nonce, payload, payloadSize + 16, true);
payloadSize += 16;
header.ll[0] ^= CreateHeaderMask (m_Address->i, payload + (payloadSize - 24));
header.ll[1] ^= CreateHeaderMask (m_Address->i, payload + (payloadSize - 12));
i2p::crypto::ChaCha20 (headerX, 48, m_Address->i, nonce, headerX);
m_NoiseState->MixHash (payload, payloadSize); // h = SHA256(h || encrypted payload from Session Request) for SessionCreated
m_SentHandshakePacket->payloadSize = payloadSize;
// send
if (m_State == eSSU2SessionStateTokenReceived || m_Server.AddPendingOutgoingSession (shared_from_this ()))
{
m_State = eSSU2SessionStateSessionRequestSent;
m_Server.Send (header.buf, 16, headerX, 48, payload, payloadSize, m_RemoteEndpoint);
}
else
{
LogPrint (eLogWarning, "SSU2: SessionRequest request to ", m_RemoteEndpoint, " already pending");
Terminate ();
}
}
void SSU2Session::ProcessSessionRequest (Header& header, uint8_t * buf, size_t len)
{
// we are Bob
const uint8_t nonce[12] = {0};
uint8_t headerX[48];
i2p::crypto::ChaCha20 (buf + 16, 48, i2p::context.GetSSU2IntroKey (), nonce, headerX);
memcpy (&m_DestConnID, headerX, 8);
uint64_t token;
memcpy (&token, headerX + 8, 8);
if (!token || token != m_Server.GetIncomingToken (m_RemoteEndpoint))
{
LogPrint (eLogDebug, "SSU2: SessionRequest token mismatch. Retry");
SendRetry ();
return;
}
// KDF for session request
m_NoiseState->MixHash ( { {header.buf, 16}, {headerX, 16} } ); // h = SHA256(h || header)
m_NoiseState->MixHash (headerX + 16, 32); // h = SHA256(h || aepk);
uint8_t sharedSecret[32];
i2p::context.GetSSU2StaticKeys ().Agree (headerX + 16, sharedSecret);
m_NoiseState->MixKey (sharedSecret);
// decrypt
uint8_t * payload = buf + 64;
std::vector<uint8_t> decryptedPayload(len - 80);
if (!i2p::crypto::AEADChaCha20Poly1305 (payload, len - 80, m_NoiseState->m_H, 32,
m_NoiseState->m_CK + 32, nonce, decryptedPayload.data (), decryptedPayload.size (), false))
{
LogPrint (eLogWarning, "SSU2: SessionRequest AEAD verification failed ");
return;
}
m_NoiseState->MixHash (payload, len - 64); // h = SHA256(h || encrypted payload from Session Request) for SessionCreated
// payload
m_State = eSSU2SessionStateSessionRequestReceived;
HandlePayload (decryptedPayload.data (), decryptedPayload.size ());
m_Server.AddSession (shared_from_this ());
SendSessionCreated (headerX + 16);
}
void SSU2Session::SendSessionCreated (const uint8_t * X)
{
// we are Bob
m_EphemeralKeys = i2p::transport::transports.GetNextX25519KeysPair ();
m_SentHandshakePacket.reset (new HandshakePacket);
auto ts = i2p::util::GetMillisecondsSinceEpoch ();
m_SentHandshakePacket->sendTime = ts;
uint8_t kh2[32];
i2p::crypto::HKDF (m_NoiseState->m_CK, nullptr, 0, "SessCreateHeader", kh2, 32); // k_header_2 = HKDF(chainKey, ZEROLEN, "SessCreateHeader", 32)
// fill packet
Header& header = m_SentHandshakePacket->header;
uint8_t * headerX = m_SentHandshakePacket->headerX,
* payload = m_SentHandshakePacket->payload;
header.h.connID = m_DestConnID; // dest id
header.h.packetNum = 0;
header.h.type = eSSU2SessionCreated;
header.h.flags[0] = 2; // ver
header.h.flags[1] = (uint8_t)i2p::context.GetNetID (); // netID
header.h.flags[2] = 0; // flag
memcpy (headerX, &m_SourceConnID, 8); // source id
memset (headerX + 8, 0, 8); // token = 0
memcpy (headerX + 16, m_EphemeralKeys->GetPublicKey (), 32); // Y
// payload
size_t maxPayloadSize = m_MaxPayloadSize - 48;
payload[0] = eSSU2BlkDateTime;
htobe16buf (payload + 1, 4);
htobe32buf (payload + 3, ts/1000);
size_t payloadSize = 7;
payloadSize += CreateAddressBlock (payload + payloadSize, maxPayloadSize - payloadSize, m_RemoteEndpoint);
if (m_RelayTag)
{
payload[payloadSize] = eSSU2BlkRelayTag;
htobe16buf (payload + payloadSize + 1, 4);
htobe32buf (payload + payloadSize + 3, m_RelayTag);
payloadSize += 7;
}
auto token = m_Server.NewIncomingToken (m_RemoteEndpoint);
if (ts + SSU2_TOKEN_EXPIRATION_THRESHOLD > token.second) // not expired?
{
payload[payloadSize] = eSSU2BlkNewToken;
htobe16buf (payload + payloadSize + 1, 12);
htobe32buf (payload + payloadSize + 3, token.second - SSU2_TOKEN_EXPIRATION_THRESHOLD); // expires
memcpy (payload + payloadSize + 7, &token.first, 8); // token
payloadSize += 15;
}
if (m_TerminationReason != eSSU2TerminationReasonNormalClose)
payloadSize += CreateTerminationBlock (payload + payloadSize, maxPayloadSize - payloadSize);
payloadSize += CreatePaddingBlock (payload + payloadSize, maxPayloadSize - payloadSize);
// KDF for SessionCreated
m_NoiseState->MixHash ( { {header.buf, 16}, {headerX, 16} } ); // h = SHA256(h || header)
m_NoiseState->MixHash (headerX + 16, 32); // h = SHA256(h || bepk);
uint8_t sharedSecret[32];
m_EphemeralKeys->Agree (X, sharedSecret);
m_NoiseState->MixKey (sharedSecret);
// encrypt
const uint8_t nonce[12] = {0};
i2p::crypto::AEADChaCha20Poly1305 (payload, payloadSize, m_NoiseState->m_H, 32, m_NoiseState->m_CK + 32, nonce, payload, payloadSize + 16, true);
payloadSize += 16;
m_NoiseState->MixHash (payload, payloadSize); // h = SHA256(h || encrypted Noise payload from Session Created)
header.ll[0] ^= CreateHeaderMask (i2p::context.GetSSU2IntroKey (), payload + (payloadSize - 24));
header.ll[1] ^= CreateHeaderMask (kh2, payload + (payloadSize - 12));
i2p::crypto::ChaCha20 (headerX, 48, kh2, nonce, headerX);
m_State = eSSU2SessionStateSessionCreatedSent;
m_SentHandshakePacket->payloadSize = payloadSize;
// send
m_Server.Send (header.buf, 16, headerX, 48, payload, payloadSize, m_RemoteEndpoint);
// terminate if errors
if (m_TerminationReason != eSSU2TerminationReasonNormalClose)
Terminate ();
}
bool SSU2Session::ProcessSessionCreated (uint8_t * buf, size_t len)
{
// we are Alice
Header header;
memcpy (header.buf, buf, 16);
header.ll[0] ^= CreateHeaderMask (m_Address->i, buf + (len - 24));
uint8_t kh2[32];
i2p::crypto::HKDF (m_NoiseState->m_CK, nullptr, 0, "SessCreateHeader", kh2, 32); // k_header_2 = HKDF(chainKey, ZEROLEN, "SessCreateHeader", 32)
header.ll[1] ^= CreateHeaderMask (kh2, buf + (len - 12));
if (header.h.type != eSSU2SessionCreated)
// this situation is valid, because it might be Retry with different encryption
return false;
const uint8_t nonce[12] = {0};
uint8_t headerX[48];
i2p::crypto::ChaCha20 (buf + 16, 48, kh2, nonce, headerX);
// KDF for SessionCreated
m_NoiseState->MixHash ( { {header.buf, 16}, {headerX, 16} } ); // h = SHA256(h || header)
m_NoiseState->MixHash (headerX + 16, 32); // h = SHA256(h || bepk);
uint8_t sharedSecret[32];
m_EphemeralKeys->Agree (headerX + 16, sharedSecret);
m_NoiseState->MixKey (sharedSecret);
// decrypt
uint8_t * payload = buf + 64;
std::vector<uint8_t> decryptedPayload(len - 80);
if (!i2p::crypto::AEADChaCha20Poly1305 (payload, len - 80, m_NoiseState->m_H, 32,
m_NoiseState->m_CK + 32, nonce, decryptedPayload.data (), decryptedPayload.size (), false))
{
LogPrint (eLogWarning, "SSU2: SessionCreated AEAD verification failed ");
return false;
}
m_NoiseState->MixHash (payload, len - 64); // h = SHA256(h || encrypted payload from SessionCreated) for SessionConfirmed
// payload
HandlePayload (decryptedPayload.data (), decryptedPayload.size ());
m_Server.AddSession (shared_from_this ());
AdjustMaxPayloadSize ();
SendSessionConfirmed (headerX + 16);
KDFDataPhase (m_KeyDataSend, m_KeyDataReceive);
return true;
}
void SSU2Session::SendSessionConfirmed (const uint8_t * Y)
{
// we are Alice
m_SentHandshakePacket.reset (new HandshakePacket);
m_SentHandshakePacket->sendTime = i2p::util::GetMillisecondsSinceEpoch ();
uint8_t kh2[32];
i2p::crypto::HKDF (m_NoiseState->m_CK, nullptr, 0, "SessionConfirmed", kh2, 32); // k_header_2 = HKDF(chainKey, ZEROLEN, "SessionConfirmed", 32)
// fill packet
Header& header = m_SentHandshakePacket->header;
header.h.connID = m_DestConnID; // dest id
header.h.packetNum = 0;
header.h.type = eSSU2SessionConfirmed;
memset (header.h.flags, 0, 3);
header.h.flags[0] = 1; // frag, total fragments always 1
// payload
size_t maxPayloadSize = m_MaxPayloadSize - 48; // for part 2, 48 is part1
uint8_t * payload = m_SentHandshakePacket->payload;
size_t payloadSize = CreateRouterInfoBlock (payload, maxPayloadSize, i2p::context.GetSharedRouterInfo ());
if (!payloadSize)
{
// split by two fragments
maxPayloadSize += m_MaxPayloadSize;
payloadSize = CreateRouterInfoBlock (payload, maxPayloadSize, i2p::context.GetSharedRouterInfo ());
header.h.flags[0] = 0x02; // frag 0, total fragments 2
// TODO: check if we need more fragments
}
if (payloadSize < maxPayloadSize)
payloadSize += CreatePaddingBlock (payload + payloadSize, maxPayloadSize - payloadSize);
// KDF for Session Confirmed part 1
m_NoiseState->MixHash (header.buf, 16); // h = SHA256(h || header)
// Encrypt part 1
uint8_t * part1 = m_SentHandshakePacket->headerX;
uint8_t nonce[12];
CreateNonce (1, nonce);
i2p::crypto::AEADChaCha20Poly1305 (i2p::context.GetSSU2StaticPublicKey (), 32, m_NoiseState->m_H, 32, m_NoiseState->m_CK + 32, nonce, part1, 48, true);
m_NoiseState->MixHash (part1, 48); // h = SHA256(h || ciphertext);
// KDF for Session Confirmed part 2
uint8_t sharedSecret[32];
i2p::context.GetSSU2StaticKeys ().Agree (Y, sharedSecret);
m_NoiseState->MixKey (sharedSecret);
// Encrypt part2
memset (nonce, 0, 12);
i2p::crypto::AEADChaCha20Poly1305 (payload, payloadSize, m_NoiseState->m_H, 32, m_NoiseState->m_CK + 32, nonce, payload, payloadSize + 16, true);
payloadSize += 16;
m_NoiseState->MixHash (payload, payloadSize); // h = SHA256(h || ciphertext);
m_SentHandshakePacket->payloadSize = payloadSize;
if (header.h.flags[0] > 1)
{
if (payloadSize > m_MaxPayloadSize - 48)
{
payloadSize = m_MaxPayloadSize - 48 - (rand () % 16);
if (m_SentHandshakePacket->payloadSize - payloadSize < 24)
payloadSize -= 24;
}
else
header.h.flags[0] = 1;
}
// Encrypt header
header.ll[0] ^= CreateHeaderMask (m_Address->i, payload + (payloadSize - 24));
header.ll[1] ^= CreateHeaderMask (kh2, payload + (payloadSize - 12));
m_State = eSSU2SessionStateSessionConfirmedSent;
// send
m_Server.Send (header.buf, 16, part1, 48, payload, payloadSize, m_RemoteEndpoint);
m_SendPacketNum++;
if (m_SentHandshakePacket->payloadSize > payloadSize)
{
// send second fragment
m_SessionConfirmedFragment.reset (new HandshakePacket);
Header& header = m_SessionConfirmedFragment->header;
header.h.connID = m_DestConnID; // dest id
header.h.packetNum = 0;
header.h.type = eSSU2SessionConfirmed;
memset (header.h.flags, 0, 3);
header.h.flags[0] = 0x12; // frag 1, total fragments 2
m_SessionConfirmedFragment->payloadSize = m_SentHandshakePacket->payloadSize - payloadSize;
memcpy (m_SessionConfirmedFragment->payload, m_SentHandshakePacket->payload + payloadSize, m_SessionConfirmedFragment->payloadSize);
m_SentHandshakePacket->payloadSize = payloadSize;
header.ll[0] ^= CreateHeaderMask (m_Address->i, m_SessionConfirmedFragment->payload + (m_SessionConfirmedFragment->payloadSize - 24));
header.ll[1] ^= CreateHeaderMask (kh2, m_SessionConfirmedFragment->payload + (m_SessionConfirmedFragment->payloadSize - 12));
m_Server.Send (header.buf, 16, m_SessionConfirmedFragment->payload, m_SessionConfirmedFragment->payloadSize, m_RemoteEndpoint);
}
}
bool SSU2Session::ProcessSessionConfirmed (uint8_t * buf, size_t len)
{
// we are Bob
Header header;
memcpy (header.buf, buf, 16);
header.ll[0] ^= CreateHeaderMask (i2p::context.GetSSU2IntroKey (), buf + (len - 24));
uint8_t kh2[32];
i2p::crypto::HKDF (m_NoiseState->m_CK, nullptr, 0, "SessionConfirmed", kh2, 32); // k_header_2 = HKDF(chainKey, ZEROLEN, "SessionConfirmed", 32)
header.ll[1] ^= CreateHeaderMask (kh2, buf + (len - 12));
if (header.h.type != eSSU2SessionConfirmed)
{
LogPrint (eLogInfo, "SSU2: Unexpected message type ", (int)header.h.type, " instead ", (int)eSSU2SessionConfirmed);
// TODO: queue up
return true;
}
// check if fragmented
if ((header.h.flags[0] & 0x0F) > 1)
{
// fragmented
if (!(header.h.flags[0] & 0xF0))
{
// first fragment
if (!m_SessionConfirmedFragment)
{
m_SessionConfirmedFragment.reset (new HandshakePacket);
m_SessionConfirmedFragment->header = header;
memcpy (m_SessionConfirmedFragment->payload, buf + 16, len - 16);
m_SessionConfirmedFragment->payloadSize = len - 16;
return true; // wait for second fragment
}
else if (m_SessionConfirmedFragment->isSecondFragment)
{
// we have second fragment
m_SessionConfirmedFragment->header = header;
memmove (m_SessionConfirmedFragment->payload + (len - 16), m_SessionConfirmedFragment->payload, m_SessionConfirmedFragment->payloadSize);
memcpy (m_SessionConfirmedFragment->payload, buf + 16, len - 16);
m_SessionConfirmedFragment->payloadSize += (len - 16);
buf = m_SessionConfirmedFragment->payload - 16;
len = m_SessionConfirmedFragment->payloadSize + 16;
}
else
return true;
}
else
{
// second fragment
if (!m_SessionConfirmedFragment)
{
// out of sequence, save it
m_SessionConfirmedFragment.reset (new HandshakePacket);
memcpy (m_SessionConfirmedFragment->payload, buf + 16, len - 16);
m_SessionConfirmedFragment->payloadSize = len - 16;
m_SessionConfirmedFragment->isSecondFragment = true;
return true;
}
header = m_SessionConfirmedFragment->header;
memcpy (m_SessionConfirmedFragment->payload + m_SessionConfirmedFragment->payloadSize, buf + 16, len - 16);
m_SessionConfirmedFragment->payloadSize += (len - 16);
buf = m_SessionConfirmedFragment->payload - 16;
len = m_SessionConfirmedFragment->payloadSize + 16;
}
}
// KDF for Session Confirmed part 1
m_NoiseState->MixHash (header.buf, 16); // h = SHA256(h || header)
// decrypt part1
uint8_t nonce[12];
CreateNonce (1, nonce);
uint8_t S[32];
if (!i2p::crypto::AEADChaCha20Poly1305 (buf + 16, 32, m_NoiseState->m_H, 32,
m_NoiseState->m_CK + 32, nonce, S, 32, false))
{
LogPrint (eLogWarning, "SSU2: SessionConfirmed part 1 AEAD verification failed ");
return false;
}
m_NoiseState->MixHash (buf + 16, 48); // h = SHA256(h || ciphertext);
// KDF for Session Confirmed part 2 and data phase
uint8_t sharedSecret[32];
m_EphemeralKeys->Agree (S, sharedSecret);
m_NoiseState->MixKey (sharedSecret);
KDFDataPhase (m_KeyDataReceive, m_KeyDataSend);
// decrypt part2
memset (nonce, 0, 12);
uint8_t * payload = buf + 64;
std::vector<uint8_t> decryptedPayload(len - 80);
if (!i2p::crypto::AEADChaCha20Poly1305 (payload, len - 80, m_NoiseState->m_H, 32,
m_NoiseState->m_CK + 32, nonce, decryptedPayload.data (), decryptedPayload.size (), false))
{
LogPrint (eLogWarning, "SSU2: SessionConfirmed part 2 AEAD verification failed ");
return false;
}
m_NoiseState->MixHash (payload, len - 64); // h = SHA256(h || ciphertext);
// payload
// handle RouterInfo block that must be first
if (decryptedPayload[0] != eSSU2BlkRouterInfo)
{
LogPrint (eLogError, "SSU2: SessionConfirmed unexpected first block type ", (int)decryptedPayload[0]);
return false;
}
size_t riSize = bufbe16toh (decryptedPayload.data () + 1);
if (riSize + 3 > decryptedPayload.size ())
{
LogPrint (eLogError, "SSU2: SessionConfirmed RouterInfo block is too long ", riSize);
return false;
}
LogPrint (eLogDebug, "SSU2: RouterInfo in SessionConfirmed");
auto ri = ExtractRouterInfo (decryptedPayload.data () + 3, riSize);
if (!ri)
{
LogPrint (eLogError, "SSU2: SessionConfirmed malformed RouterInfo block");
return false;
}
m_Address = ri->GetSSU2AddressWithStaticKey (S, m_RemoteEndpoint.address ().is_v6 ());
if (!m_Address)
{
LogPrint (eLogError, "SSU2: No SSU2 address with static key found in SessionConfirmed from ", i2p::data::GetIdentHashAbbreviation (ri->GetIdentHash ()));
return false;
}
// update RouterInfo in netdb
ri = i2p::data::netdb.AddRouterInfo (ri->GetBuffer (), ri->GetBufferLen ()); // ri points to one from netdb now
if (!ri)
{
LogPrint (eLogError, "SSU2: Couldn't update RouterInfo from SessionConfirmed in netdb");
return false;
}
SetRemoteIdentity (ri->GetRouterIdentity ());
AdjustMaxPayloadSize ();
m_Server.AddSessionByRouterHash (shared_from_this ()); // we know remote router now
m_RemoteTransports = ri->GetCompatibleTransports (false);
// handle other blocks
HandlePayload (decryptedPayload.data () + riSize + 3, decryptedPayload.size () - riSize - 3);
Established ();
SendQuickAck ();
return true;
}
void SSU2Session::KDFDataPhase (uint8_t * keydata_ab, uint8_t * keydata_ba)
{
uint8_t keydata[64];
i2p::crypto::HKDF (m_NoiseState->m_CK, nullptr, 0, "", keydata); // keydata = HKDF(chainKey, ZEROLEN, "", 64)
// ab
i2p::crypto::HKDF (keydata, nullptr, 0, "HKDFSSU2DataKeys", keydata_ab); // keydata_ab = HKDF(keydata, ZEROLEN, "HKDFSSU2DataKeys", 64)
// ba
i2p::crypto::HKDF (keydata + 32, nullptr, 0, "HKDFSSU2DataKeys", keydata_ba); // keydata_ba = HKDF(keydata + 32, ZEROLEN, "HKDFSSU2DataKeys", 64)
}
void SSU2Session::SendTokenRequest ()
{
// we are Alice
Header header;
uint8_t h[32], payload[41];
// fill packet
header.h.connID = m_DestConnID; // dest id
RAND_bytes (header.buf + 8, 4); // random packet num
header.h.type = eSSU2TokenRequest;
header.h.flags[0] = 2; // ver
header.h.flags[1] = (uint8_t)i2p::context.GetNetID (); // netID
header.h.flags[2] = 0; // flag
memcpy (h, header.buf, 16);
memcpy (h + 16, &m_SourceConnID, 8); // source id
memset (h + 24, 0, 8); // zero token
// payload
payload[0] = eSSU2BlkDateTime;
htobe16buf (payload + 1, 4);
htobe32buf (payload + 3, i2p::util::GetSecondsSinceEpoch ());
size_t payloadSize = 7;
payloadSize += CreatePaddingBlock (payload + payloadSize, 25 - payloadSize, 1);
// encrypt
uint8_t nonce[12];
CreateNonce (be32toh (header.h.packetNum), nonce);
i2p::crypto::AEADChaCha20Poly1305 (payload, payloadSize, h, 32, m_Address->i, nonce, payload, payloadSize + 16, true);
payloadSize += 16;
header.ll[0] ^= CreateHeaderMask (m_Address->i, payload + (payloadSize - 24));
header.ll[1] ^= CreateHeaderMask (m_Address->i, payload + (payloadSize - 12));
memset (nonce, 0, 12);
i2p::crypto::ChaCha20 (h + 16, 16, m_Address->i, nonce, h + 16);
// send
if (m_Server.AddPendingOutgoingSession (shared_from_this ()))
m_Server.Send (header.buf, 16, h + 16, 16, payload, payloadSize, m_RemoteEndpoint);
else
{
LogPrint (eLogWarning, "SSU2: TokenRequest request to ", m_RemoteEndpoint, " already pending");
Terminate ();
}
}
void SSU2Session::ProcessTokenRequest (Header& header, uint8_t * buf, size_t len)
{
// we are Bob
if (len < 48)
{
LogPrint (eLogWarning, "SSU2: Incorrect TokenRequest len ", len);
return;
}
uint8_t nonce[12] = {0};
uint8_t h[32];
memcpy (h, header.buf, 16);
i2p::crypto::ChaCha20 (buf + 16, 16, i2p::context.GetSSU2IntroKey (), nonce, h + 16);
memcpy (&m_DestConnID, h + 16, 8);
// decrypt
CreateNonce (be32toh (header.h.packetNum), nonce);
uint8_t * payload = buf + 32;
if (!i2p::crypto::AEADChaCha20Poly1305 (payload, len - 48, h, 32,
i2p::context.GetSSU2IntroKey (), nonce, payload, len - 48, false))
{
LogPrint (eLogWarning, "SSU2: TokenRequest AEAD verification failed ");
return;
}
// payload
HandlePayload (payload, len - 48);
SendRetry ();
}
void SSU2Session::SendRetry ()
{
// we are Bob
Header header;
uint8_t h[32], payload[64];
// fill packet
header.h.connID = m_DestConnID; // dest id
RAND_bytes (header.buf + 8, 4); // random packet num
header.h.type = eSSU2Retry;
header.h.flags[0] = 2; // ver
header.h.flags[1] = (uint8_t)i2p::context.GetNetID (); // netID
header.h.flags[2] = 0; // flag
memcpy (h, header.buf, 16);
memcpy (h + 16, &m_SourceConnID, 8); // source id
uint64_t token = m_Server.GetIncomingToken (m_RemoteEndpoint);
memcpy (h + 24, &token, 8); // token
// payload
payload[0] = eSSU2BlkDateTime;
htobe16buf (payload + 1, 4);
htobe32buf (payload + 3, i2p::util::GetSecondsSinceEpoch ());
size_t payloadSize = 7;
payloadSize += CreateAddressBlock (payload + payloadSize, 64 - payloadSize, m_RemoteEndpoint);
payloadSize += CreatePaddingBlock (payload + payloadSize, 64 - payloadSize);
// encrypt
uint8_t nonce[12];
CreateNonce (be32toh (header.h.packetNum), nonce);
i2p::crypto::AEADChaCha20Poly1305 (payload, payloadSize, h, 32, i2p::context.GetSSU2IntroKey (), nonce, payload, payloadSize + 16, true);
payloadSize += 16;
header.ll[0] ^= CreateHeaderMask (i2p::context.GetSSU2IntroKey (), payload + (payloadSize - 24));
header.ll[1] ^= CreateHeaderMask (i2p::context.GetSSU2IntroKey (), payload + (payloadSize - 12));
memset (nonce, 0, 12);
i2p::crypto::ChaCha20 (h + 16, 16, i2p::context.GetSSU2IntroKey (), nonce, h + 16);
// send
m_Server.Send (header.buf, 16, h + 16, 16, payload, payloadSize, m_RemoteEndpoint);
}
bool SSU2Session::ProcessRetry (uint8_t * buf, size_t len)
{
// we are Alice
Header header;
memcpy (header.buf, buf, 16);
header.ll[0] ^= CreateHeaderMask (m_Address->i, buf + (len - 24));
header.ll[1] ^= CreateHeaderMask (m_Address->i, buf + (len - 12));
if (header.h.type != eSSU2Retry)
{
LogPrint (eLogWarning, "SSU2: Unexpected message type ", (int)header.h.type, " instead ", (int)eSSU2Retry);
return false;
}
uint8_t nonce[12] = {0};
uint64_t headerX[2]; // sourceConnID, token
i2p::crypto::ChaCha20 (buf + 16, 16, m_Address->i, nonce, (uint8_t *)headerX);
m_Server.UpdateOutgoingToken (m_RemoteEndpoint, headerX[1], i2p::util::GetSecondsSinceEpoch () + SSU2_TOKEN_EXPIRATION_TIMEOUT);
// decrypt and handle payload
uint8_t * payload = buf + 32;
CreateNonce (be32toh (header.h.packetNum), nonce);
uint8_t h[32];
memcpy (h, header.buf, 16);
memcpy (h + 16, &headerX, 16);
if (!i2p::crypto::AEADChaCha20Poly1305 (payload, len - 48, h, 32,
m_Address->i, nonce, payload, len - 48, false))
{
LogPrint (eLogWarning, "SSU2: Retry AEAD verification failed ");
return false;
}
HandlePayload (payload, len - 48);
m_State = eSSU2SessionStateTokenReceived;
InitNoiseXKState1 (*m_NoiseState, m_Address->s); // reset Noise TODO: check state
SendSessionRequest (headerX[1]);
return true;
}
void SSU2Session::SendHolePunch (uint32_t nonce, const boost::asio::ip::udp::endpoint& ep,
const uint8_t * introKey, uint64_t token)
{
// we are Charlie
LogPrint (eLogDebug, "SSU2: Sending HolePunch to ", ep);
Header header;
uint8_t h[32], payload[SSU2_MAX_PACKET_SIZE];
// fill packet
header.h.connID = htobe64 (((uint64_t)nonce << 32) | nonce); // dest id
RAND_bytes (header.buf + 8, 4); // random packet num
header.h.type = eSSU2HolePunch;
header.h.flags[0] = 2; // ver
header.h.flags[1] = (uint8_t)i2p::context.GetNetID (); // netID
header.h.flags[2] = 0; // flag
memcpy (h, header.buf, 16);
uint64_t c = ~header.h.connID;
memcpy (h + 16, &c, 8); // source id
RAND_bytes (h + 24, 8); // token
// payload
payload[0] = eSSU2BlkDateTime;
htobe16buf (payload + 1, 4);
htobe32buf (payload + 3, i2p::util::GetSecondsSinceEpoch ());
size_t payloadSize = 7;
payloadSize += CreateAddressBlock (payload + payloadSize, m_MaxPayloadSize - payloadSize, ep);
payloadSize += CreateRelayResponseBlock (payload + payloadSize, m_MaxPayloadSize - payloadSize,
eSSU2RelayResponseCodeAccept, nonce, token, ep.address ().is_v4 ());
payloadSize += CreatePaddingBlock (payload + payloadSize, m_MaxPayloadSize - payloadSize);
// encrypt
uint8_t n[12];
CreateNonce (be32toh (header.h.packetNum), n);
i2p::crypto::AEADChaCha20Poly1305 (payload, payloadSize, h, 32, introKey, n, payload, payloadSize + 16, true);
payloadSize += 16;
header.ll[0] ^= CreateHeaderMask (introKey, payload + (payloadSize - 24));
header.ll[1] ^= CreateHeaderMask (introKey, payload + (payloadSize - 12));
memset (n, 0, 12);
i2p::crypto::ChaCha20 (h + 16, 16, introKey, n, h + 16);
// send
m_Server.Send (header.buf, 16, h + 16, 16, payload, payloadSize, ep);
}
bool SSU2Session::ProcessHolePunch (uint8_t * buf, size_t len)
{
// we are Alice
LogPrint (eLogDebug, "SSU2: HolePunch");
Header header;
memcpy (header.buf, buf, 16);
header.ll[0] ^= CreateHeaderMask (i2p::context.GetSSU2IntroKey (), buf + (len - 24));
header.ll[1] ^= CreateHeaderMask (i2p::context.GetSSU2IntroKey (), buf + (len - 12));
if (header.h.type != eSSU2HolePunch)
{
LogPrint (eLogWarning, "SSU2: Unexpected message type ", (int)header.h.type, " instead ", (int)eSSU2HolePunch);
return false;
}
uint8_t nonce[12] = {0};
uint64_t headerX[2]; // sourceConnID, token
i2p::crypto::ChaCha20 (buf + 16, 16, i2p::context.GetSSU2IntroKey (), nonce, (uint8_t *)headerX);
m_DestConnID = headerX[0];
// decrypt and handle payload
uint8_t * payload = buf + 32;
CreateNonce (be32toh (header.h.packetNum), nonce);
uint8_t h[32];
memcpy (h, header.buf, 16);
memcpy (h + 16, &headerX, 16);
if (!i2p::crypto::AEADChaCha20Poly1305 (payload, len - 48, h, 32,
i2p::context.GetSSU2IntroKey (), nonce, payload, len - 48, false))
{
LogPrint (eLogWarning, "SSU2: HolePunch AEAD verification failed ");
return false;
}
HandlePayload (payload, len - 48);
// connect to Charlie
if (m_State == eSSU2SessionStateIntroduced)
{
// create new connID
uint64_t oldConnID = GetConnID ();
RAND_bytes ((uint8_t *)&m_DestConnID, 8);
RAND_bytes ((uint8_t *)&m_SourceConnID, 8);
// connect
m_State = eSSU2SessionStateTokenReceived;
m_Server.AddPendingOutgoingSession (shared_from_this ());
m_Server.RemoveSession (oldConnID);
Connect ();
}
return true;
}
void SSU2Session::SendPeerTest (uint8_t msg, const uint8_t * signedData, size_t signedDataLen, const uint8_t * introKey)
{
Header header;
uint8_t h[32], payload[SSU2_MAX_PACKET_SIZE];
// fill packet
header.h.connID = m_DestConnID; // dest id
RAND_bytes (header.buf + 8, 4); // random packet num
header.h.type = eSSU2PeerTest;
header.h.flags[0] = 2; // ver
header.h.flags[1] = (uint8_t)i2p::context.GetNetID (); // netID
header.h.flags[2] = 0; // flag
memcpy (h, header.buf, 16);
memcpy (h + 16, &m_SourceConnID, 8); // source id
// payload
payload[0] = eSSU2BlkDateTime;
htobe16buf (payload + 1, 4);
htobe32buf (payload + 3, i2p::util::GetSecondsSinceEpoch ());
size_t payloadSize = 7;
if (msg == 6 || msg == 7)
payloadSize += CreateAddressBlock (payload + payloadSize, m_MaxPayloadSize - payloadSize, m_RemoteEndpoint);
payloadSize += CreatePeerTestBlock (payload + payloadSize, m_MaxPayloadSize - payloadSize,
msg, eSSU2PeerTestCodeAccept, nullptr, signedData, signedDataLen);
payloadSize += CreatePaddingBlock (payload + payloadSize, m_MaxPayloadSize - payloadSize);
// encrypt
uint8_t n[12];
CreateNonce (be32toh (header.h.packetNum), n);
i2p::crypto::AEADChaCha20Poly1305 (payload, payloadSize, h, 32, introKey, n, payload, payloadSize + 16, true);
payloadSize += 16;
header.ll[0] ^= CreateHeaderMask (introKey, payload + (payloadSize - 24));
header.ll[1] ^= CreateHeaderMask (introKey, payload + (payloadSize - 12));
memset (n, 0, 12);
i2p::crypto::ChaCha20 (h + 16, 16, introKey, n, h + 16);
// send
m_Server.Send (header.buf, 16, h + 16, 16, payload, payloadSize, m_RemoteEndpoint);
}
bool SSU2Session::ProcessPeerTest (uint8_t * buf, size_t len)
{
// we are Alice or Charlie
Header header;
memcpy (header.buf, buf, 16);
header.ll[0] ^= CreateHeaderMask (i2p::context.GetSSU2IntroKey (), buf + (len - 24));
header.ll[1] ^= CreateHeaderMask (i2p::context.GetSSU2IntroKey (), buf + (len - 12));
if (header.h.type != eSSU2PeerTest)
{
LogPrint (eLogWarning, "SSU2: Unexpected message type ", (int)header.h.type, " instead ", (int)eSSU2PeerTest);
return false;
}
uint8_t nonce[12] = {0};
uint64_t headerX[2]; // sourceConnID, token
i2p::crypto::ChaCha20 (buf + 16, 16, i2p::context.GetSSU2IntroKey (), nonce, (uint8_t *)headerX);
m_DestConnID = headerX[0];
// decrypt and handle payload
uint8_t * payload = buf + 32;
CreateNonce (be32toh (header.h.packetNum), nonce);
uint8_t h[32];
memcpy (h, header.buf, 16);
memcpy (h + 16, &headerX, 16);
if (!i2p::crypto::AEADChaCha20Poly1305 (payload, len - 48, h, 32,
i2p::context.GetSSU2IntroKey (), nonce, payload, len - 48, false))
{
LogPrint (eLogWarning, "SSU2: PeerTest AEAD verification failed ");
return false;
}
HandlePayload (payload, len - 48);
return true;
}
uint32_t SSU2Session::SendData (const uint8_t * buf, size_t len)
{
if (len < 8)
{
LogPrint (eLogWarning, "SSU2: Data message payload is too short ", (int)len);
return 0;
}
Header header;
header.h.connID = m_DestConnID;
header.h.packetNum = htobe32 (m_SendPacketNum);
header.h.type = eSSU2Data;
memset (header.h.flags, 0, 3);
uint8_t nonce[12];
CreateNonce (m_SendPacketNum, nonce);
uint8_t payload[SSU2_MAX_PACKET_SIZE];
i2p::crypto::AEADChaCha20Poly1305 (buf, len, header.buf, 16, m_KeyDataSend, nonce, payload, SSU2_MAX_PACKET_SIZE, true);
header.ll[0] ^= CreateHeaderMask (m_Address->i, payload + (len - 8));
header.ll[1] ^= CreateHeaderMask (m_KeyDataSend + 32, payload + (len + 4));
m_Server.Send (header.buf, 16, payload, len + 16, m_RemoteEndpoint);
m_SendPacketNum++;
m_LastActivityTimestamp = i2p::util::GetSecondsSinceEpoch ();
m_NumSentBytes += len + 32;
return m_SendPacketNum - 1;
}
void SSU2Session::ProcessData (uint8_t * buf, size_t len)
{
Header header;
header.ll[0] = m_SourceConnID;
memcpy (header.buf + 8, buf + 8, 8);
header.ll[1] ^= CreateHeaderMask (m_KeyDataReceive + 32, buf + (len - 12));
if (header.h.type != eSSU2Data)
{
LogPrint (eLogWarning, "SSU2: Unexpected message type ", (int)header.h.type, " instead ", (int)eSSU2Data);
if (IsEstablished ())
SendQuickAck (); // in case it was SessionConfirmed
else
ResendHandshakePacket (); // assume we receive
return;
}
uint8_t payload[SSU2_MAX_PACKET_SIZE];
size_t payloadSize = len - 32;
uint32_t packetNum = be32toh (header.h.packetNum);
uint8_t nonce[12];
CreateNonce (packetNum, nonce);
if (!i2p::crypto::AEADChaCha20Poly1305 (buf + 16, payloadSize, header.buf, 16,
m_KeyDataReceive, nonce, payload, payloadSize, false))
{
LogPrint (eLogWarning, "SSU2: Data AEAD verification failed ");
return;
}
m_LastActivityTimestamp = i2p::util::GetSecondsSinceEpoch ();
m_NumReceivedBytes += len;
if (!packetNum || UpdateReceivePacketNum (packetNum))
HandlePayload (payload, payloadSize);
}
void SSU2Session::HandlePayload (const uint8_t * buf, size_t len)
{
size_t offset = 0;
while (offset < len)
{
uint8_t blk = buf[offset];
offset++;
auto size = bufbe16toh (buf + offset);
offset += 2;
LogPrint (eLogDebug, "SSU2: Block type ", (int)blk, " of size ", size);
if (size > len)
{
LogPrint (eLogError, "SSU2: Unexpected block length ", size);
break;
}
switch (blk)
{
case eSSU2BlkDateTime:
LogPrint (eLogDebug, "SSU2: Datetime");
if (m_State == eSSU2SessionStateSessionRequestReceived)
{
auto ts = i2p::util::GetSecondsSinceEpoch ();
uint32_t signedOnTime = bufbe32toh (buf + offset);
if (signedOnTime < ts - SSU2_CLOCK_SKEW || signedOnTime > ts + SSU2_CLOCK_SKEW)
m_TerminationReason = eSSU2TerminationReasonClockSkew;
};
break;
case eSSU2BlkOptions:
LogPrint (eLogDebug, "SSU2: Options");
break;
case eSSU2BlkRouterInfo:
{
// not from SessionConfirmed, we must add it instantly to use in next block
LogPrint (eLogDebug, "SSU2: RouterInfo");
auto ri = ExtractRouterInfo (buf + offset, size);
if (ri)
i2p::data::netdb.AddRouterInfo (ri->GetBuffer (), ri->GetBufferLen ()); // TODO: add ri
break;
}
case eSSU2BlkI2NPMessage:
{
LogPrint (eLogDebug, "SSU2: I2NP message");
auto nextMsg = (buf[offset] == eI2NPTunnelData) ? NewI2NPTunnelMessage (true) : NewI2NPShortMessage ();
nextMsg->len = nextMsg->offset + size + 7; // 7 more bytes for full I2NP header
memcpy (nextMsg->GetNTCP2Header (), buf + offset, size);
nextMsg->FromNTCP2 (); // SSU2 has the same format as NTCP2
m_Handler.PutNextMessage (std::move (nextMsg));
m_IsDataReceived = true;
break;
}
case eSSU2BlkFirstFragment:
LogPrint (eLogDebug, "SSU2: First fragment");
HandleFirstFragment (buf + offset, size);
m_IsDataReceived = true;
break;
case eSSU2BlkFollowOnFragment:
LogPrint (eLogDebug, "SSU2: Follow-on fragment");
HandleFollowOnFragment (buf + offset, size);
m_IsDataReceived = true;
break;
case eSSU2BlkTermination:
LogPrint (eLogDebug, "SSU2: Termination reason=", (int)buf[11]);
if (IsEstablished () && buf[11] != eSSU2TerminationReasonTerminationReceived)
RequestTermination (eSSU2TerminationReasonTerminationReceived);
else
Done ();
break;
case eSSU2BlkRelayRequest:
LogPrint (eLogDebug, "SSU2: RelayRequest");
HandleRelayRequest (buf + offset, size);
break;
case eSSU2BlkRelayResponse:
LogPrint (eLogDebug, "SSU2: RelayResponse");
HandleRelayResponse (buf + offset, size);
break;
case eSSU2BlkRelayIntro:
LogPrint (eLogDebug, "SSU2: RelayIntro");
HandleRelayIntro (buf + offset, size);
break;
case eSSU2BlkPeerTest:
LogPrint (eLogDebug, "SSU2: PeerTest msg=", (int)buf[offset], " code=", (int)buf[offset+1]);
HandlePeerTest (buf + offset, size);
if (buf[offset] < 5)
m_IsDataReceived = true;
break;
case eSSU2BlkNextNonce:
break;
case eSSU2BlkAck:
LogPrint (eLogDebug, "SSU2: Ack");
HandleAck (buf + offset, size);
break;
case eSSU2BlkAddress:
LogPrint (eLogDebug, "SSU2: Address");
HandleAddress (buf + offset, size);
break;
case eSSU2BlkIntroKey:
break;
case eSSU2BlkRelayTagRequest:
LogPrint (eLogDebug, "SSU2: RelayTagRequest");
if (!m_RelayTag)
{
RAND_bytes ((uint8_t *)&m_RelayTag, 4);
m_Server.AddRelay (m_RelayTag, shared_from_this ());
}
break;
case eSSU2BlkRelayTag:
LogPrint (eLogDebug, "SSU2: RelayTag");
m_RelayTag = bufbe32toh (buf + offset);
break;
case eSSU2BlkNewToken:
{
LogPrint (eLogDebug, "SSU2: New token");
uint64_t token;
memcpy (&token, buf + offset + 4, 8);
m_Server.UpdateOutgoingToken (m_RemoteEndpoint, token, bufbe32toh (buf + offset));
break;
}
case eSSU2BlkPathChallenge:
LogPrint (eLogDebug, "SSU2: Path challenge");
SendPathResponse (buf + offset, size);
break;
case eSSU2BlkPathResponse:
LogPrint (eLogDebug, "SSU2: Path response");
break;
case eSSU2BlkFirstPacketNumber:
break;
case eSSU2BlkPadding:
LogPrint (eLogDebug, "SSU2: Padding");
break;
default:
LogPrint (eLogWarning, "SSU2: Unknown block type ", (int)blk);
}
offset += size;
}
}
void SSU2Session::HandleAck (const uint8_t * buf, size_t len)
{
if (m_State == eSSU2SessionStateSessionConfirmedSent)
{
Established ();
return;
}
if (m_SentPackets.empty ()) return;
if (len < 5) return;
// acnt
uint32_t ackThrough = bufbe32toh (buf);
uint32_t firstPacketNum = ackThrough > buf[4] ? ackThrough - buf[4] : 0;
HandleAckRange (firstPacketNum, ackThrough, i2p::util::GetMillisecondsSinceEpoch ()); // acnt
// ranges
len -= 5;
const uint8_t * ranges = buf + 5;
while (len > 0 && firstPacketNum)
{
uint32_t lastPacketNum = firstPacketNum - 1;
if (*ranges > lastPacketNum) break;
lastPacketNum -= *ranges; ranges++; // nacks
if (*ranges > lastPacketNum + 1) break;
firstPacketNum = lastPacketNum - *ranges + 1; ranges++; // acks
len -= 2;
HandleAckRange (firstPacketNum, lastPacketNum, 0);
}
}
void SSU2Session::HandleAckRange (uint32_t firstPacketNum, uint32_t lastPacketNum, uint64_t ts)
{
if (firstPacketNum > lastPacketNum) return;
auto it = m_SentPackets.begin ();
while (it != m_SentPackets.end () && it->first < firstPacketNum) it++; // find first acked packet
if (it == m_SentPackets.end () || it->first > lastPacketNum) return; // not found
auto it1 = it;
int numPackets = 0;
while (it1 != m_SentPackets.end () && it1->first <= lastPacketNum)
{
if (ts && !it1->second->numResends)
{
if (ts > it1->second->sendTime)
{
auto rtt = ts - it1->second->sendTime;
m_RTT = (m_RTT*m_SendPacketNum + rtt)/(m_SendPacketNum + 1);
m_RTO = m_RTT*SSU2_kAPPA;
if (m_RTO < SSU2_MIN_RTO) m_RTO = SSU2_MIN_RTO;
if (m_RTO > SSU2_MAX_RTO) m_RTO = SSU2_MAX_RTO;
}
ts = 0; // update RTT one time per range
}
it1++;
numPackets++;
}
m_SentPackets.erase (it, it1);
if (numPackets > 0)
{
m_WindowSize += numPackets;
if (m_WindowSize > SSU2_MAX_WINDOW_SIZE) m_WindowSize = SSU2_MAX_WINDOW_SIZE;
}
}
void SSU2Session::HandleAddress (const uint8_t * buf, size_t len)
{
boost::asio::ip::udp::endpoint ep;
if (ExtractEndpoint (buf, len, ep))
{
LogPrint (eLogInfo, "SSU2: Our external address is ", ep);
if (!i2p::util::net::IsInReservedRange (ep.address ()))
{
i2p::context.UpdateAddress (ep.address ());
// check our port
bool isV4 = ep.address ().is_v4 ();
if (ep.port () != m_Server.GetPort (isV4))
{
if (isV4)
{
if (i2p::context.GetStatus () == eRouterStatusTesting)
i2p::context.SetError (eRouterErrorSymmetricNAT);
}
else
{
if (i2p::context.GetStatusV6 () == eRouterStatusTesting)
i2p::context.SetErrorV6 (eRouterErrorSymmetricNAT);
}
}
else
{
if (isV4)
{
if (i2p::context.GetStatus () == eRouterStatusError && i2p::context.GetError () == eRouterErrorSymmetricNAT)
i2p::context.SetStatus (eRouterStatusTesting);
}
else
{
if (i2p::context.GetStatusV6 () == eRouterStatusError && i2p::context.GetErrorV6 () == eRouterErrorSymmetricNAT)
i2p::context.SetStatusV6 (eRouterStatusTesting);
}
}
}
}
}
void SSU2Session::HandleFirstFragment (const uint8_t * buf, size_t len)
{
uint32_t msgID; memcpy (&msgID, buf + 1, 4);
auto msg = NewI2NPShortMessage ();
// same format as I2NP message block
msg->len = msg->offset + len + 7;
memcpy (msg->GetNTCP2Header (), buf, len);
std::shared_ptr<SSU2IncompleteMessage> m;
bool found = false;
auto it = m_IncompleteMessages.find (msgID);
if (it != m_IncompleteMessages.end ())
{
found = true;
m = it->second;
}
else
{
m = std::make_shared<SSU2IncompleteMessage>();
m_IncompleteMessages.emplace (msgID, m);
}
m->msg = msg;
m->nextFragmentNum = 1;
m->lastFragmentInsertTime = i2p::util::GetSecondsSinceEpoch ();
if (found && ConcatOutOfSequenceFragments (m))
{
// we have all follow-on fragments already
m->msg->FromNTCP2 ();
m_Handler.PutNextMessage (std::move (m->msg));
m_IncompleteMessages.erase (it);
}
}
void SSU2Session::HandleFollowOnFragment (const uint8_t * buf, size_t len)
{
if (len < 5) return;
uint8_t fragmentNum = buf[0] >> 1;
bool isLast = buf[0] & 0x01;
uint32_t msgID; memcpy (&msgID, buf + 1, 4);
auto it = m_IncompleteMessages.find (msgID);
if (it != m_IncompleteMessages.end ())
{
if (it->second->nextFragmentNum == fragmentNum && fragmentNum < SSU2_MAX_NUM_FRAGMENTS &&
it->second->msg)
{
// in sequence
it->second->AttachNextFragment (buf + 5, len - 5);
if (isLast)
{
it->second->msg->FromNTCP2 ();
m_Handler.PutNextMessage (std::move (it->second->msg));
m_IncompleteMessages.erase (it);
}
else
{
if (ConcatOutOfSequenceFragments (it->second))
{
m_Handler.PutNextMessage (std::move (it->second->msg));
m_IncompleteMessages.erase (it);
}
else
it->second->lastFragmentInsertTime = i2p::util::GetSecondsSinceEpoch ();
}
return;
}
}
else
{
// follow-on fragment before first fragment
auto msg = std::make_shared<SSU2IncompleteMessage> ();
msg->nextFragmentNum = 0;
it = m_IncompleteMessages.emplace (msgID, msg).first;
}
// insert out of sequence fragment
if (fragmentNum >= SSU2_MAX_NUM_FRAGMENTS)
{
LogPrint (eLogWarning, "SSU2: Fragment number ", fragmentNum, " exceeds ", SSU2_MAX_NUM_FRAGMENTS);
return;
}
auto fragment = std::make_shared<SSU2IncompleteMessage::Fragment> ();
memcpy (fragment->buf, buf + 5, len -5);
fragment->len = len - 5;
fragment->isLast = isLast;
it->second->outOfSequenceFragments.emplace (fragmentNum, fragment);
it->second->lastFragmentInsertTime = i2p::util::GetSecondsSinceEpoch ();
}
bool SSU2Session::ConcatOutOfSequenceFragments (std::shared_ptr<SSU2IncompleteMessage> m)
{
if (!m) return false;
bool isLast = false;
for (auto it = m->outOfSequenceFragments.begin (); it != m->outOfSequenceFragments.end ();)
if (it->first == m->nextFragmentNum)
{
m->AttachNextFragment (it->second->buf, it->second->len);
isLast = it->second->isLast;
it = m->outOfSequenceFragments.erase (it);
}
else
break;
return isLast;
}
void SSU2Session::HandleRelayRequest (const uint8_t * buf, size_t len)
{
// we are Bob
uint32_t relayTag = bufbe32toh (buf + 5); // relay tag
auto session = m_Server.FindRelaySession (relayTag);
if (!session)
{
LogPrint (eLogWarning, "SSU2: RelayRequest session with relay tag ", relayTag, " not found");
// send relay response back to Alice
uint8_t payload[SSU2_MAX_PACKET_SIZE];
size_t payloadSize = CreateRelayResponseBlock (payload, m_MaxPayloadSize,
eSSU2RelayResponseCodeBobRelayTagNotFound, bufbe32toh (buf + 1), 0, false);
payloadSize += CreatePaddingBlock (payload + payloadSize, m_MaxPayloadSize - payloadSize);
SendData (payload, payloadSize);
return;
}
session->m_RelaySessions.emplace (bufbe32toh (buf + 1), // nonce
std::make_pair (shared_from_this (), i2p::util::GetSecondsSinceEpoch ()) );
// send relay intro to Charlie
auto r = i2p::data::netdb.FindRouter (GetRemoteIdentity ()->GetIdentHash ()); // Alice's RI
if (r)
i2p::data::netdb.PopulateRouterInfoBuffer (r);
else
LogPrint (eLogWarning, "SSU2: RelayRequest Alice's router info not found");
uint8_t payload[SSU2_MAX_PACKET_SIZE];
size_t payloadSize = r ? CreateRouterInfoBlock (payload, m_MaxPayloadSize - len - 32, r) : 0;
if (!payloadSize && r)
session->SendFragmentedMessage (CreateDatabaseStoreMsg (r));
payloadSize += CreateRelayIntroBlock (payload + payloadSize, m_MaxPayloadSize - payloadSize, buf + 1, len -1);
if (payloadSize < m_MaxPayloadSize)
payloadSize += CreatePaddingBlock (payload + payloadSize, m_MaxPayloadSize - payloadSize);
session->SendData (payload, payloadSize);
}
void SSU2Session::HandleRelayIntro (const uint8_t * buf, size_t len)
{
// we are Charlie
SSU2RelayResponseCode code = eSSU2RelayResponseCodeAccept;
uint64_t token = 0;
bool isV4 = false;
auto r = i2p::data::netdb.FindRouter (buf + 1); // Alice
if (r)
{
SignedData s;
s.Insert ((const uint8_t *)"RelayRequestData", 16); // prologue
s.Insert (GetRemoteIdentity ()->GetIdentHash (), 32); // bhash
s.Insert (i2p::context.GetIdentHash (), 32); // chash
s.Insert (buf + 33, 14); // nonce, relay tag, timestamp, ver, asz
uint8_t asz = buf[46];
s.Insert (buf + 47, asz); // Alice Port, Alice IP
if (s.Verify (r->GetIdentity (), buf + 47 + asz))
{
// send HolePunch
boost::asio::ip::udp::endpoint ep;
if (ExtractEndpoint (buf + 47, asz, ep))
{
auto addr = ep.address ().is_v6 () ? r->GetSSU2V6Address () : r->GetSSU2V4Address ();
if (addr)
{
if (m_Server.IsSupported (ep.address ()))
{
token = m_Server.GetIncomingToken (ep);
isV4 = ep.address ().is_v4 ();
SendHolePunch (bufbe32toh (buf + 33), ep, addr->i, token);
}
else
{
LogPrint (eLogWarning, "SSU2: RelayIntro unsupported address");
code = eSSU2RelayResponseCodeCharlieUnsupportedAddress;
}
}
else
{
LogPrint (eLogWarning, "SSU2: RelayIntro unknown address");
code = eSSU2RelayResponseCodeCharlieAliceIsUnknown;
}
}
else
{
LogPrint (eLogWarning, "SSU2: RelayIntro can't extract endpoint");
code = eSSU2RelayResponseCodeCharlieAliceIsUnknown;
}
}
else
{
LogPrint (eLogWarning, "SSU2: RelayIntro signature verification failed");
code = eSSU2RelayResponseCodeCharlieSignatureFailure;
}
}
else
{
LogPrint (eLogError, "SSU2: RelayIntro unknown router to introduce");
code = eSSU2RelayResponseCodeCharlieAliceIsUnknown;
}
// send relay response to Bob
uint8_t payload[SSU2_MAX_PACKET_SIZE];
size_t payloadSize = CreateRelayResponseBlock (payload, m_MaxPayloadSize,
code, bufbe32toh (buf + 33), token, isV4);
payloadSize += CreatePaddingBlock (payload + payloadSize, m_MaxPayloadSize - payloadSize);
SendData (payload, payloadSize);
}
void SSU2Session::HandleRelayResponse (const uint8_t * buf, size_t len)
{
uint32_t nonce = bufbe32toh (buf + 2);
if (m_State == eSSU2SessionStateIntroduced)
{
// HolePunch from Charlie
// TODO: verify address and signature
// verify nonce
if (~htobe64 (((uint64_t)nonce << 32) | nonce) != m_DestConnID)
LogPrint (eLogWarning, "SSU2: Relay response nonce mismatch ", nonce, " connID=", m_DestConnID);
if (len >= 8)
{
// new token
uint64_t token;
memcpy (&token, buf + len - 8, 8);
m_Server.UpdateOutgoingToken (m_RemoteEndpoint, token, i2p::util::GetSecondsSinceEpoch () + SSU2_TOKEN_EXPIRATION_TIMEOUT);
}
return;
}
auto it = m_RelaySessions.find (nonce);
if (it != m_RelaySessions.end ())
{
if (it->second.first && it->second.first->IsEstablished ())
{
// we are Bob, message from Charlie
uint8_t payload[SSU2_MAX_PACKET_SIZE];
payload[0] = eSSU2BlkRelayResponse;
htobe16buf (payload + 1, len);
memcpy (payload + 3, buf, len); // forward to Alice as is
size_t payloadSize = len + 3;
payloadSize += CreatePaddingBlock (payload + payloadSize, m_MaxPayloadSize - payloadSize);
it->second.first->SendData (payload, payloadSize);
}
else
{
// we are Alice, message from Bob
if (!buf[1]) // status code accepted?
{
// verify signature
uint8_t csz = buf[11];
SignedData s;
s.Insert ((const uint8_t *)"RelayAgreementOK", 16); // prologue
s.Insert (GetRemoteIdentity ()->GetIdentHash (), 32); // bhash
s.Insert (buf + 2, 10 + csz); // nonce, timestamp, ver, csz and Charlie's endpoint
if (s.Verify (it->second.first->GetRemoteIdentity (), buf + 12 + csz))
{
if (it->second.first->m_State == eSSU2SessionStateIntroduced) // HolePunch not received yet
// update Charlie's endpoint
ExtractEndpoint (buf + 12, csz, it->second.first->m_RemoteEndpoint);
}
else
{
LogPrint (eLogWarning, "SSU2: RelayResponse signature verification failed");
it->second.first->Done ();
}
}
else
{
LogPrint (eLogInfo, "SSU2: RelayResponse status code=", (int)buf[1]);
it->second.first->Done ();
}
}
m_RelaySessions.erase (it);
}
else
LogPrint (eLogWarning, "SSU2: RelayResponse unknown nonce ", bufbe32toh (buf + 2));
}
void SSU2Session::HandlePeerTest (const uint8_t * buf, size_t len)
{
if (len < 3) return;
uint8_t msg = buf[0];
size_t offset = 3; // points to signed data
if (msg == 2 || msg == 4) offset += 32; // hash is presented for msg 2 and 4 only
if (len < offset + 5) return;
uint32_t nonce = bufbe32toh (buf + offset + 1);
switch (msg) // msg
{
case 1: // Bob from Alice
{
auto session = m_Server.GetRandomSession ((buf[12] == 6) ? i2p::data::RouterInfo::eSSU2V4 : i2p::data::RouterInfo::eSSU2V6,
GetRemoteIdentity ()->GetIdentHash ());
if (session) // session with Charlie
{
session->m_PeerTests.emplace (nonce, std::make_pair (shared_from_this (), i2p::util::GetSecondsSinceEpoch ()));
uint8_t payload[SSU2_MAX_PACKET_SIZE];
// Alice's RouterInfo
auto r = i2p::data::netdb.FindRouter (GetRemoteIdentity ()->GetIdentHash ());
if (r) i2p::data::netdb.PopulateRouterInfoBuffer (r);
size_t payloadSize = r ? CreateRouterInfoBlock (payload, m_MaxPayloadSize - len - 32, r) : 0;
if (!payloadSize && r)
session->SendFragmentedMessage (CreateDatabaseStoreMsg (r));
if (payloadSize + len + 48 > m_MaxPayloadSize)
{
// doesn't fit one message, send RouterInfo in separate message
session->SendData (payload, payloadSize);
payloadSize = 0;
}
// PeerTest to Charlie
payloadSize += CreatePeerTestBlock (payload + payloadSize, m_MaxPayloadSize - payloadSize, 2,
eSSU2PeerTestCodeAccept, GetRemoteIdentity ()->GetIdentHash (), buf + offset, len - offset);
payloadSize += CreatePaddingBlock (payload + payloadSize, m_MaxPayloadSize - payloadSize);
session->SendData (payload, payloadSize);
}
else
{
// Charlie not found, send error back to Alice
uint8_t payload[SSU2_MAX_PACKET_SIZE], zeroHash[32] = {0};
size_t payloadSize = CreatePeerTestBlock (payload, m_MaxPayloadSize, 4,
eSSU2PeerTestCodeBobNoCharlieAvailable, zeroHash, buf + offset, len - offset);
payloadSize += CreatePaddingBlock (payload + payloadSize, m_MaxPayloadSize - payloadSize);
SendData (payload, payloadSize);
}
break;
}
case 2: // Charlie from Bob
{
// sign with Charlie's key
uint8_t asz = buf[offset + 9];
std::vector<uint8_t> newSignedData (asz + 10 + i2p::context.GetIdentity ()->GetSignatureLen ());
memcpy (newSignedData.data (), buf + offset, asz + 10);
SignedData s;
s.Insert ((const uint8_t *)"PeerTestValidate", 16); // prologue
s.Insert (GetRemoteIdentity ()->GetIdentHash (), 32); // bhash
s.Insert (buf + 3, 32); // ahash
s.Insert (newSignedData.data (), asz + 10); // ver, nonce, ts, asz, Alice's endpoint
s.Sign (i2p::context.GetPrivateKeys (), newSignedData.data () + 10 + asz);
// send response (msg 3) back and msg 5 if accepted
SSU2PeerTestCode code = eSSU2PeerTestCodeAccept;
auto r = i2p::data::netdb.FindRouter (buf + 3); // find Alice
if (r)
{
size_t signatureLen = r->GetIdentity ()->GetSignatureLen ();
if (len >= offset + asz + 10 + signatureLen)
{
s.Reset ();
s.Insert ((const uint8_t *)"PeerTestValidate", 16); // prologue
s.Insert (GetRemoteIdentity ()->GetIdentHash (), 32); // bhash
s.Insert (buf + offset, asz + 10); // signed data
if (s.Verify (r->GetIdentity (), buf + offset + asz + 10))
{
if (!m_Server.FindSession (r->GetIdentity ()->GetIdentHash ()))
{
boost::asio::ip::udp::endpoint ep;
std::shared_ptr<const i2p::data::RouterInfo::Address> addr;
if (ExtractEndpoint (buf + offset + 10, asz, ep))
addr = r->GetSSU2Address (ep.address ().is_v4 ());
if (addr && m_Server.IsSupported (ep.address ()))
{
// send msg 5 to Alice
auto session = std::make_shared<SSU2Session> (m_Server, r, addr);
session->SetState (eSSU2SessionStatePeerTest);
session->m_RemoteEndpoint = ep; // might be different
session->m_DestConnID = htobe64 (((uint64_t)nonce << 32) | nonce);
session->m_SourceConnID = ~session->m_DestConnID;
m_Server.AddSession (session);
session->SendPeerTest (5, newSignedData.data (), newSignedData.size (), addr->i);
}
else
code = eSSU2PeerTestCodeCharlieUnsupportedAddress;
}
else
code = eSSU2PeerTestCodeCharlieAliceIsAlreadyConnected;
}
else
code = eSSU2PeerTestCodeCharlieSignatureFailure;
}
else // maformed message
code = eSSU2PeerTestCodeCharlieReasonUnspecified;
}
else
code = eSSU2PeerTestCodeCharlieAliceIsUnknown;
// send msg 3 back to Bob
uint8_t payload[SSU2_MAX_PACKET_SIZE];
size_t payloadSize = CreatePeerTestBlock (payload, m_MaxPayloadSize, 3,
code, nullptr, newSignedData.data (), newSignedData.size ());
payloadSize += CreatePaddingBlock (payload + payloadSize, m_MaxPayloadSize - payloadSize);
SendData (payload, payloadSize);
break;
}
case 3: // Bob from Charlie
{
auto it = m_PeerTests.find (nonce);
if (it != m_PeerTests.end () && it->second.first)
{
uint8_t payload[SSU2_MAX_PACKET_SIZE];
// Charlie's RouterInfo
auto r = i2p::data::netdb.FindRouter (GetRemoteIdentity ()->GetIdentHash ());
if (r) i2p::data::netdb.PopulateRouterInfoBuffer (r);
size_t payloadSize = r ? CreateRouterInfoBlock (payload, m_MaxPayloadSize - len - 32, r) : 0;
if (!payloadSize && r)
it->second.first->SendFragmentedMessage (CreateDatabaseStoreMsg (r));
if (payloadSize + len + 16 > m_MaxPayloadSize)
{
// doesn't fit one message, send RouterInfo in separate message
it->second.first->SendData (payload, payloadSize);
payloadSize = 0;
}
// PeerTest to Alice
payloadSize += CreatePeerTestBlock (payload + payloadSize, m_MaxPayloadSize, 4,
(SSU2PeerTestCode)buf[1], GetRemoteIdentity ()->GetIdentHash (), buf + offset, len - offset);
if (payloadSize < m_MaxPayloadSize)
payloadSize += CreatePaddingBlock (payload + payloadSize, m_MaxPayloadSize - payloadSize);
it->second.first->SendData (payload, payloadSize);
m_PeerTests.erase (it);
}
else
LogPrint (eLogWarning, "SSU2: Unknown peer test 3 nonce ", nonce);
break;
}
case 4: // Alice from Bob
{
auto it = m_PeerTests.find (nonce);
if (it != m_PeerTests.end ())
{
if (buf[1] == eSSU2PeerTestCodeAccept)
{
auto r = i2p::data::netdb.FindRouter (buf + 3); // find Charlie
if (r && it->second.first)
{
uint8_t asz = buf[offset + 9];
SignedData s;
s.Insert ((const uint8_t *)"PeerTestValidate", 16); // prologue
s.Insert (GetRemoteIdentity ()->GetIdentHash (), 32); // bhash
s.Insert (i2p::context.GetIdentity ()->GetIdentHash (), 32); // ahash
s.Insert (buf + offset, asz + 10); // ver, nonce, ts, asz, Alice's endpoint
if (s.Verify (r->GetIdentity (), buf + offset + asz + 10))
{
it->second.first->SetRemoteIdentity (r->GetIdentity ());
auto addr = r->GetSSU2Address (m_Address->IsV4 ());
if (addr)
{
it->second.first->m_Address = addr;
if (it->second.first->m_State == eSSU2SessionStatePeerTestReceived)
{
// msg 5 already received. send msg 6
SetRouterStatus (eRouterStatusOK);
it->second.first->m_State = eSSU2SessionStatePeerTest;
it->second.first->SendPeerTest (6, buf + offset, len - offset, addr->i);
}
else
{
if (GetRouterStatus () == eRouterStatusTesting)
{
SetRouterStatus (eRouterStatusFirewalled);
if (m_Address->IsV4 ())
m_Server.RescheduleIntroducersUpdateTimer ();
else
m_Server.RescheduleIntroducersUpdateTimerV6 ();
}
}
}
else
{
LogPrint (eLogWarning, "SSU2: Peer test 4 address not found");
it->second.first->Done ();
}
}
else
{
LogPrint (eLogWarning, "SSU2: Peer test 4 signature verification failed");
it->second.first->Done ();
}
}
}
else
{
LogPrint (eLogInfo, "SSU2: Peer test 4 error code ", (int)buf[1], " from ",
i2p::data::GetIdentHashAbbreviation (buf[1] < 64 ? GetRemoteIdentity ()->GetIdentHash () : i2p::data::IdentHash (buf + 3)));
if (GetRouterStatus () == eRouterStatusTesting)
SetRouterStatus (eRouterStatusUnknown);
it->second.first->Done ();
}
m_PeerTests.erase (it);
}
else
LogPrint (eLogWarning, "SSU2: Unknown peer test 4 nonce ", nonce);
break;
}
case 5: // Alice from Charlie 1
if (htobe64 (((uint64_t)nonce << 32) | nonce) == m_SourceConnID)
{
if (m_Address)
{
SetRouterStatus (eRouterStatusOK);
SendPeerTest (6, buf + offset, len - offset, m_Address->i);
}
else
// we received msg 5 before msg 4
m_State = eSSU2SessionStatePeerTestReceived;
}
else
LogPrint (eLogWarning, "SSU2: Peer test 5 nonce mismatch ", nonce, " connID=", m_SourceConnID);
break;
case 6: // Charlie from Alice
if (m_Address)
SendPeerTest (7, buf + offset, len - offset, m_Address->i);
else
LogPrint (eLogWarning, "SSU2: Unknown address for peer test 6");
m_Server.RemoveSession (~htobe64 (((uint64_t)nonce << 32) | nonce));
break;
case 7: // Alice from Charlie 2
m_Server.RemoveSession (htobe64 (((uint64_t)nonce << 32) | nonce));
if (m_Address->IsV6 ())
i2p::context.SetStatusV6 (eRouterStatusOK); // set status OK for ipv6 even if from SSU2
break;
default:
LogPrint (eLogWarning, "SSU2: PeerTest unexpected msg num ", buf[0]);
}
}
bool SSU2Session::ExtractEndpoint (const uint8_t * buf, size_t size, boost::asio::ip::udp::endpoint& ep)
{
if (size < 2) return false;
int port = bufbe16toh (buf);
if (size == 6)
{
boost::asio::ip::address_v4::bytes_type bytes;
memcpy (bytes.data (), buf + 2, 4);
ep = boost::asio::ip::udp::endpoint (boost::asio::ip::address_v4 (bytes), port);
}
else if (size == 18)
{
boost::asio::ip::address_v6::bytes_type bytes;
memcpy (bytes.data (), buf + 2, 16);
ep = boost::asio::ip::udp::endpoint (boost::asio::ip::address_v6 (bytes), port);
}
else
{
LogPrint (eLogWarning, "SSU2: Address size ", int(size), " is not supported");
return false;
}
return true;
}
size_t SSU2Session::CreateEndpoint (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& ep)
{
if (len < 6) return 0;
htobe16buf (buf, ep.port ());
size_t size = 0;
if (ep.address ().is_v4 ())
{
memcpy (buf + 2, ep.address ().to_v4 ().to_bytes ().data (), 4);
size = 6;
}
else if (ep.address ().is_v6 ())
{
if (len < 18) return 0;
memcpy (buf + 2, ep.address ().to_v6 ().to_bytes ().data (), 16);
size = 18;
}
else
{
LogPrint (eLogWarning, "SSU2: Wrong address type ", ep.address ().to_string ());
return 0;
}
return size;
}
std::shared_ptr<const i2p::data::RouterInfo::Address> SSU2Session::FindLocalAddress () const
{
if (m_Address)
return i2p::context.GetRouterInfo ().GetSSU2Address (m_Address->IsV4 ());
return nullptr;
}
void SSU2Session::AdjustMaxPayloadSize ()
{
auto addr = FindLocalAddress ();
if (addr && addr->ssu)
{
int mtu = addr->ssu->mtu;
if (!mtu && addr->IsV4 ()) mtu = SSU2_MAX_PACKET_SIZE;
if (m_Address && m_Address->ssu && (!mtu || m_Address->ssu->mtu < mtu))
mtu = m_Address->ssu->mtu;
if (mtu)
{
m_MaxPayloadSize = mtu - (addr->IsV6 () ? IPV6_HEADER_SIZE: IPV4_HEADER_SIZE) - UDP_HEADER_SIZE - 32;
LogPrint (eLogDebug, "SSU2: Session MTU=", mtu, ", max payload size=", m_MaxPayloadSize);
}
}
}
RouterStatus SSU2Session::GetRouterStatus () const
{
if (m_Address)
{
if (m_Address->IsV4 ())
return i2p::context.GetStatus ();
if (m_Address->IsV6 ())
return i2p::context.GetStatusV6 ();
}
return eRouterStatusUnknown;
}
void SSU2Session::SetRouterStatus (RouterStatus status) const
{
if (m_Address)
{
if (m_Address->IsV4 ())
i2p::context.SetStatusSSU2 (status);
else if (m_Address->IsV6 ())
i2p::context.SetStatusV6SSU2 (status);
}
}
size_t SSU2Session::CreateAddressBlock (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& ep)
{
if (len < 9) return 0;
buf[0] = eSSU2BlkAddress;
size_t size = CreateEndpoint (buf + 3, len - 3, ep);
if (!size) return 0;
htobe16buf (buf + 1, size);
return size + 3;
}
size_t SSU2Session::CreateRouterInfoBlock (uint8_t * buf, size_t len, std::shared_ptr<const i2p::data::RouterInfo> r)
{
if (!r || !r->GetBuffer () || len < 5) return 0;
buf[0] = eSSU2BlkRouterInfo;
size_t size = r->GetBufferLen ();
if (size + 5 < len)
{
memcpy (buf + 5, r->GetBuffer (), size);
buf[3] = 0; // flag
}
else
{
i2p::data::GzipDeflator deflator;
deflator.SetCompressionLevel (9);
size = deflator.Deflate (r->GetBuffer (), r->GetBufferLen (), buf + 5, len - 5);
if (!size) return 0; // doesn't fit
buf[3] = SSU2_ROUTER_INFO_FLAG_GZIP; // flag
}
htobe16buf (buf + 1, size + 2); // size
buf[4] = 1; // frag
return size + 5;
}
size_t SSU2Session::CreateAckBlock (uint8_t * buf, size_t len)
{
if (len < 8) return 0;
int maxNumRanges = (len - 8) >> 1;
if (maxNumRanges > SSU2_MAX_NUM_ACK_RANGES) maxNumRanges = SSU2_MAX_NUM_ACK_RANGES;
buf[0] = eSSU2BlkAck;
uint32_t ackThrough = m_OutOfSequencePackets.empty () ? m_ReceivePacketNum : *m_OutOfSequencePackets.rbegin ();
htobe32buf (buf + 3, ackThrough); // Ack Through
uint16_t acnt = 0;
int numRanges = 0;
if (ackThrough)
{
if (m_OutOfSequencePackets.empty ())
acnt = std::min ((int)ackThrough, 255); // no gaps
else
{
auto it = m_OutOfSequencePackets.rbegin (); it++; // prev packet num
while (it != m_OutOfSequencePackets.rend () && *it == ackThrough - acnt - 1)
{
acnt++;
it++;
}
// ranges
uint32_t lastNum = ackThrough - acnt;
if (acnt > 255)
{
auto d = std::div (acnt - 255, 255);
acnt = 255;
if (d.quot > maxNumRanges)
{
d.quot = maxNumRanges;
d.rem = 0;
}
// Acks only ragnes for acnt
for (int i = 0; i < d.quot; i++)
{
buf[8 + numRanges*2] = 0; buf[8 + numRanges*2 + 1] = 255; // NACKs 0, Acks 255
numRanges++;
}
if (d.rem > 0)
{
buf[8 + numRanges*2] = 0; buf[8 + numRanges*2 + 1] = d.rem;
numRanges++;
}
}
while (it != m_OutOfSequencePackets.rend () && numRanges < maxNumRanges)
{
if (lastNum - (*it) > 255)
{
// NACKs only ranges
if (lastNum > (*it) + 255*(maxNumRanges - numRanges)) break; // too many NACKs
while (lastNum - (*it) > 255)
{
buf[8 + numRanges*2] = 255; buf[8 + numRanges*2 + 1] = 0; // NACKs 255, Acks 0
lastNum -= 255;
numRanges++;
}
}
// NACKs and Acks ranges
buf[8 + numRanges*2] = lastNum - (*it) - 1; // NACKs
lastNum = *it; it++;
int numAcks = 1;
while (it != m_OutOfSequencePackets.rend () && lastNum > 0 && *it == lastNum - 1)
{
numAcks++; lastNum--;
it++;
}
while (numAcks > 255)
{
// Acks only ranges
buf[8 + numRanges*2 + 1] = 255; // Acks 255
numAcks -= 255;
numRanges++;
buf[8 + numRanges*2] = 0; // NACKs 0
if (numRanges >= maxNumRanges) break;
}
if (numAcks > 255) numAcks = 255;
buf[8 + numRanges*2 + 1] = (uint8_t)numAcks; // Acks
numRanges++;
}
if (numRanges < maxNumRanges && it == m_OutOfSequencePackets.rend ())
{
// add range between out-of-seqence and received
int nacks = *m_OutOfSequencePackets.begin () - m_ReceivePacketNum - 1;
if (nacks > 0)
{
if (nacks > 255) nacks = 255;
buf[8 + numRanges*2] = nacks;
buf[8 + numRanges*2 + 1] = std::min ((int)m_ReceivePacketNum + 1, 255);
numRanges++;
}
}
}
}
buf[7] = (uint8_t)acnt; // acnt
htobe16buf (buf + 1, 5 + numRanges*2);
return 8 + numRanges*2;
}
size_t SSU2Session::CreatePaddingBlock (uint8_t * buf, size_t len, size_t minSize)
{
if (len < minSize) return 0;
uint8_t paddingSize = rand () & 0x0F; // 0 - 15
if (paddingSize > len) paddingSize = len;
else if (paddingSize < minSize) paddingSize = minSize;
if (paddingSize)
{
buf[0] = eSSU2BlkPadding;
htobe16buf (buf + 1, paddingSize);
memset (buf + 3, 0, paddingSize);
}
else
return 0;
return paddingSize + 3;
}
size_t SSU2Session::CreateI2NPBlock (uint8_t * buf, size_t len, std::shared_ptr<I2NPMessage>&& msg)
{
msg->ToNTCP2 ();
auto msgBuf = msg->GetNTCP2Header ();
auto msgLen = msg->GetNTCP2Length ();
if (msgLen + 3 > len) msgLen = len - 3;
buf[0] = eSSU2BlkI2NPMessage;
htobe16buf (buf + 1, msgLen); // size
memcpy (buf + 3, msgBuf, msgLen);
return msgLen + 3;
}
size_t SSU2Session::CreateFirstFragmentBlock (uint8_t * buf, size_t len, std::shared_ptr<I2NPMessage> msg)
{
if (len < 12) return 0;
msg->ToNTCP2 ();
auto msgBuf = msg->GetNTCP2Header ();
auto msgLen = msg->GetNTCP2Length ();
if (msgLen + 3 <= len) return 0;
msgLen = len - 3;
buf[0] = eSSU2BlkFirstFragment;
htobe16buf (buf + 1, msgLen); // size
memcpy (buf + 3, msgBuf, msgLen);
msg->offset = (msgBuf - msg->buf) + msgLen;
return msgLen + 3;
}
size_t SSU2Session::CreateFollowOnFragmentBlock (uint8_t * buf, size_t len, std::shared_ptr<I2NPMessage> msg, uint8_t& fragmentNum, uint32_t msgID)
{
if (len < 8) return 0;
bool isLast = true;
auto msgLen = msg->len - msg->offset;
if (msgLen + 8 > len)
{
msgLen = len - 8;
isLast = false;
}
buf[0] = eSSU2BlkFollowOnFragment;
htobe16buf (buf + 1, msgLen + 5); // size
fragmentNum++;
buf[3] = fragmentNum << 1;
if (isLast) buf[3] |= 0x01;
memcpy (buf + 4, &msgID, 4);
memcpy (buf + 8, msg->buf + msg->offset, msgLen);
msg->offset += msgLen;
return msgLen + 8;
}
size_t SSU2Session::CreateRelayIntroBlock (uint8_t * buf, size_t len, const uint8_t * introData, size_t introDataLen)
{
buf[0] = eSSU2BlkRelayIntro;
size_t payloadSize = 1/* flag */ + 32/* Alice router hash */ + introDataLen;
if (payloadSize + 3 > len) return 0;
htobe16buf (buf + 1, payloadSize); // size
buf[3] = 0; // flag
memcpy (buf + 4, GetRemoteIdentity ()->GetIdentHash (), 32); // Alice router hash
memcpy (buf + 36, introData, introDataLen);
return payloadSize + 3;
}
size_t SSU2Session::CreateRelayResponseBlock (uint8_t * buf, size_t len,
SSU2RelayResponseCode code, uint32_t nonce, uint64_t token, bool v4)
{
buf[0] = eSSU2BlkRelayResponse;
buf[3] = 0; // flag
buf[4] = code; // code
htobe32buf (buf + 5, nonce); // nonce
htobe32buf (buf + 9, i2p::util::GetSecondsSinceEpoch ()); // timestamp
buf[13] = 2; // ver
size_t csz = 0;
if (code == eSSU2RelayResponseCodeAccept)
{
auto addr = i2p::context.GetRouterInfo ().GetSSU2Address (v4);
if (!addr)
{
LogPrint (eLogError, "SSU2: Can't find local address for RelayResponse");
return 0;
}
csz = CreateEndpoint (buf + 15, len - 15, boost::asio::ip::udp::endpoint (addr->host, addr->port));
if (!csz)
{
LogPrint (eLogError, "SSU2: Can't create local endpoint for RelayResponse");
return 0;
}
}
buf[14] = csz; // csz
// signature
size_t signatureLen = i2p::context.GetIdentity ()->GetSignatureLen ();
if (15 + csz + signatureLen > len)
{
LogPrint (eLogError, "SSU2: Buffer for RelayResponse signature is too small ", len);
return 0;
}
SignedData s;
s.Insert ((const uint8_t *)"RelayAgreementOK", 16); // prologue
if (code == eSSU2RelayResponseCodeAccept || code >= 64) // Charlie
s.Insert (GetRemoteIdentity ()->GetIdentHash (), 32); // bhash
else // Bob's reject
s.Insert (i2p::context.GetIdentity ()->GetIdentHash (), 32); // bhash
s.Insert (buf + 5, 10 + csz); // nonce, timestamp, ver, csz and Charlie's endpoint
s.Sign (i2p::context.GetPrivateKeys (), buf + 15 + csz);
size_t payloadSize = 12 + csz + signatureLen;
if (!code)
{
if (payloadSize + 11 > len)
{
LogPrint (eLogError, "SSU2: Buffer for RelayResponse token is too small ", len);
return 0;
}
memcpy (buf + 3 + payloadSize, &token, 8);
payloadSize += 8;
}
htobe16buf (buf + 1, payloadSize); // size
return payloadSize + 3;
}
size_t SSU2Session::CreatePeerTestBlock (uint8_t * buf, size_t len, uint8_t msg, SSU2PeerTestCode code,
const uint8_t * routerHash, const uint8_t * signedData, size_t signedDataLen)
{
buf[0] = eSSU2BlkPeerTest;
size_t payloadSize = 3/* msg, code, flag */ + signedDataLen;
if (routerHash) payloadSize += 32; // router hash
if (payloadSize + 3 > len) return 0;
htobe16buf (buf + 1, payloadSize); // size
buf[3] = msg; // msg
buf[4] = (uint8_t)code; // code
buf[5] = 0; //flag
size_t offset = 6;
if (routerHash)
{
memcpy (buf + offset, routerHash, 32); // router hash
offset += 32;
}
memcpy (buf + offset, signedData, signedDataLen);
return payloadSize + 3;
}
size_t SSU2Session::CreatePeerTestBlock (uint8_t * buf, size_t len, uint32_t nonce)
{
auto localAddress = FindLocalAddress ();
if (!localAddress || !localAddress->port || localAddress->host.is_unspecified () ||
localAddress->host.is_v4 () != m_RemoteEndpoint.address ().is_v4 ())
{
LogPrint (eLogWarning, "SSU2: Can't find local address for peer test");
return 0;
}
// signed data
auto ts = i2p::util::GetSecondsSinceEpoch ();
uint8_t signedData[96];
signedData[0] = 2; // ver
htobe32buf (signedData + 1, nonce);
htobe32buf (signedData + 5, ts);
size_t asz = CreateEndpoint (signedData + 10, 86, boost::asio::ip::udp::endpoint (localAddress->host, localAddress->port));
signedData[9] = asz;
// signature
SignedData s;
s.Insert ((const uint8_t *)"PeerTestValidate", 16); // prologue
s.Insert (GetRemoteIdentity ()->GetIdentHash (), 32); // bhash
s.Insert (signedData, 10 + asz); // ver, nonce, ts, asz, Alice's endpoint
s.Sign (i2p::context.GetPrivateKeys (), signedData + 10 + asz);
return CreatePeerTestBlock (buf, len, 1, eSSU2PeerTestCodeAccept, nullptr,
signedData, 10 + asz + i2p::context.GetIdentity ()->GetSignatureLen ());
}
size_t SSU2Session::CreateTerminationBlock (uint8_t * buf, size_t len)
{
buf[0] = eSSU2BlkTermination;
htobe16buf (buf + 1, 9);
htobe64buf (buf + 3, m_ReceivePacketNum);
buf[11] = (uint8_t)m_TerminationReason;
return 12;
}
std::shared_ptr<const i2p::data::RouterInfo> SSU2Session::ExtractRouterInfo (const uint8_t * buf, size_t size)
{
if (size < 2) return nullptr;
// TODO: handle frag
std::shared_ptr<const i2p::data::RouterInfo> ri;
if (buf[0] & SSU2_ROUTER_INFO_FLAG_GZIP)
{
i2p::data::GzipInflator inflator;
uint8_t uncompressed[i2p::data::MAX_RI_BUFFER_SIZE];
size_t uncompressedSize = inflator.Inflate (buf + 2, size - 2, uncompressed, i2p::data::MAX_RI_BUFFER_SIZE);
if (uncompressedSize && uncompressedSize < i2p::data::MAX_RI_BUFFER_SIZE)
ri = std::make_shared<i2p::data::RouterInfo>(uncompressed, uncompressedSize);
else
LogPrint (eLogInfo, "SSU2: RouterInfo decompression failed ", uncompressedSize);
}
else
ri = std::make_shared<i2p::data::RouterInfo>(buf + 2, size - 2);
return ri;
}
void SSU2Session::CreateNonce (uint64_t seqn, uint8_t * nonce)
{
memset (nonce, 0, 4);
htole64buf (nonce + 4, seqn);
}
bool SSU2Session::UpdateReceivePacketNum (uint32_t packetNum)
{
if (packetNum <= m_ReceivePacketNum) return false; // duplicate
if (packetNum == m_ReceivePacketNum + 1)
{
for (auto it = m_OutOfSequencePackets.begin (); it != m_OutOfSequencePackets.end ();)
{
if (*it == packetNum + 1)
{
packetNum++;
it = m_OutOfSequencePackets.erase (it);
}
else
break;
}
m_ReceivePacketNum = packetNum;
}
else
m_OutOfSequencePackets.insert (packetNum);
return true;
}
void SSU2Session::SendQuickAck ()
{
uint8_t payload[SSU2_MAX_PACKET_SIZE];
size_t payloadSize = CreateAckBlock (payload, m_MaxPayloadSize);
payloadSize += CreatePaddingBlock (payload + payloadSize, m_MaxPayloadSize - payloadSize);
SendData (payload, payloadSize);
}
void SSU2Session::SendTermination ()
{
uint8_t payload[32];
size_t payloadSize = CreateTerminationBlock (payload, 32);
payloadSize += CreatePaddingBlock (payload + payloadSize, 32 - payloadSize);
SendData (payload, payloadSize);
}
void SSU2Session::SendPathResponse (const uint8_t * data, size_t len)
{
if (len < 8 || len > m_MaxPayloadSize - 3)
{
LogPrint (eLogWarning, "SSU2: Incorrect data size for path response ", len);
return;
}
uint8_t payload[SSU2_MAX_PACKET_SIZE];
payload[0] = eSSU2BlkPathResponse;
htobe16buf (payload + 1, len);
SendData (payload, len + 3);
}
void SSU2Session::CleanUp (uint64_t ts)
{
for (auto it = m_IncompleteMessages.begin (); it != m_IncompleteMessages.end ();)
{
if (ts > it->second->lastFragmentInsertTime + SSU2_INCOMPLETE_MESSAGES_CLEANUP_TIMEOUT)
{
LogPrint (eLogWarning, "SSU2: message ", it->first, " was not completed in ", SSU2_INCOMPLETE_MESSAGES_CLEANUP_TIMEOUT, " seconds, deleted");
it = m_IncompleteMessages.erase (it);
}
else
++it;
}
if (!m_OutOfSequencePackets.empty ())
{
if (m_OutOfSequencePackets.size () > 2*SSU2_MAX_NUM_ACK_RANGES ||
*m_OutOfSequencePackets.rbegin () > m_ReceivePacketNum + 255*8)
{
uint32_t packet = *m_OutOfSequencePackets.begin ();
if (packet > m_ReceivePacketNum + 1)
{
// like we've just received all packets before first
packet--;
m_ReceivePacketNum = packet - 1;
UpdateReceivePacketNum (packet);
}
else
LogPrint (eLogError, "SSU2: Out of sequence packet ", packet, " is less than last received ", m_ReceivePacketNum);
}
if (m_OutOfSequencePackets.size () > 255*4)
{
// seems we have a serious network issue
m_ReceivePacketNum = *m_OutOfSequencePackets.rbegin ();
m_OutOfSequencePackets.clear ();
}
}
for (auto it = m_RelaySessions.begin (); it != m_RelaySessions.end ();)
{
if (ts > it->second.second + SSU2_RELAY_NONCE_EXPIRATION_TIMEOUT)
{
LogPrint (eLogWarning, "SSU2: Relay nonce ", it->first, " was not responded in ", SSU2_RELAY_NONCE_EXPIRATION_TIMEOUT, " seconds, deleted");
it = m_RelaySessions.erase (it);
}
else
++it;
}
for (auto it = m_PeerTests.begin (); it != m_PeerTests.end ();)
{
if (ts > it->second.second + SSU2_PEER_TEST_EXPIRATION_TIMEOUT)
{
LogPrint (eLogWarning, "SSU2: Peer test nonce ", it->first, " was not responded in ", SSU2_PEER_TEST_EXPIRATION_TIMEOUT, " seconds, deleted");
it = m_PeerTests.erase (it);
}
else
++it;
}
}
void SSU2Session::FlushData ()
{
bool sent = SendQueue (); // if we have something to send
if (m_IsDataReceived)
{
if (!sent) SendQuickAck ();
m_Handler.Flush ();
m_IsDataReceived = false;
}
}
}
}