I2P: End-to-End encrypted and anonymous Internet https://i2pd.website/
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/*
* Copyright (c) 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
*/
#include "Log.h"
#include "SSU2.h"
#include "SSU2OutOfSession.h"
namespace i2p
{
namespace transport
{
SSU2PeerTestSession::SSU2PeerTestSession (SSU2Server& server, uint64_t sourceConnID, uint64_t destConnID):
SSU2Session (server, nullptr, nullptr, false),
m_MsgNumReceived (0), m_NumResends (0),m_IsConnectedRecently (false), m_IsStatusChanged (false),
m_PeerTestResendTimer (server.GetService ())
{
if (!sourceConnID) sourceConnID = ~destConnID;
if (!destConnID) destConnID = ~sourceConnID;
SetSourceConnID (sourceConnID);
SetDestConnID (destConnID);
SetState (eSSU2SessionStatePeerTest);
SetTerminationTimeout (SSU2_PEER_TEST_EXPIRATION_TIMEOUT);
}
bool SSU2PeerTestSession::ProcessPeerTest (uint8_t * buf, size_t len)
{
// we are Alice or Charlie, msgs 5,6,7
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;
}
if (len < 48)
{
LogPrint (eLogWarning, "SSU2: PeerTest message too short ", len);
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);
SetDestConnID (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);
SetIsDataReceived (false);
return true;
}
void SSU2PeerTestSession::HandleAddress (const uint8_t * buf, size_t len)
{
if (!ExtractEndpoint (buf, len, m_OurEndpoint))
LogPrint (eLogWarning, "SSU2: Can't hanlde address block from peer test message");
}
void SSU2PeerTestSession::HandlePeerTest (const uint8_t * buf, size_t len)
{
// msgs 5-7
if (len < 8) return;
uint8_t msg = buf[0];
if (msg <= m_MsgNumReceived)
{
LogPrint (eLogDebug, "SSU2: PeerTest msg num ", msg, " received after ", m_MsgNumReceived, ". Ignored");
return;
}
size_t offset = 3; // points to signed data after msg + code + flag
uint32_t nonce = bufbe32toh (buf + offset + 1); // 1 - ver
switch (msg) // msg
{
case 5: // Alice from Charlie 1
{
if (htobe64 (((uint64_t)nonce << 32) | nonce) == GetSourceConnID ())
{
m_PeerTestResendTimer.cancel (); // calcel delayed msg 6 if any
m_IsConnectedRecently = GetServer ().IsConnectedRecently (GetRemoteEndpoint ());
if (GetAddress ())
{
if (!m_IsConnectedRecently)
SetRouterStatus (eRouterStatusOK);
else if (m_IsStatusChanged && GetRouterStatus () == eRouterStatusFirewalled)
SetRouterStatus (eRouterStatusUnknown);
SendPeerTest (6, buf + offset, len - offset);
}
}
else
LogPrint (eLogWarning, "SSU2: Peer test 5 nonce mismatch ", nonce, " connID=", GetSourceConnID ());
break;
}
case 6: // Charlie from Alice
{
m_PeerTestResendTimer.cancel (); // no more msg 5 resends
if (GetAddress ())
SendPeerTest (7, buf + offset, len - offset);
else
LogPrint (eLogWarning, "SSU2: Unknown address for peer test 6");
GetServer ().AddConnectedRecently (GetRemoteEndpoint (), i2p::util::GetSecondsSinceEpoch ());
GetServer ().RequestRemoveSession (GetConnID ());
break;
}
case 7: // Alice from Charlie 2
{
m_PeerTestResendTimer.cancel (); // no more msg 6 resends
if (m_MsgNumReceived < 5 && m_OurEndpoint.port ()) // msg 5 was not received
{
if (m_OurEndpoint.address ().is_v4 ()) // ipv4
{
if (i2p::context.GetStatus () == eRouterStatusFirewalled)
{
if (m_OurEndpoint.port () != GetServer ().GetPort (true))
i2p::context.SetError (eRouterErrorSymmetricNAT);
else if (i2p::context.GetError () == eRouterErrorSymmetricNAT)
i2p::context.SetError (eRouterErrorNone);
}
}
else
{
if (i2p::context.GetStatusV6 () == eRouterStatusFirewalled)
{
if (m_OurEndpoint.port () != GetServer ().GetPort (false))
i2p::context.SetErrorV6 (eRouterErrorSymmetricNAT);
else if (i2p::context.GetErrorV6 () == eRouterErrorSymmetricNAT)
i2p::context.SetErrorV6 (eRouterErrorNone);
}
}
}
GetServer ().AddConnectedRecently (GetRemoteEndpoint (), i2p::util::GetSecondsSinceEpoch ());
GetServer ().RequestRemoveSession (GetConnID ());
break;
}
default:
LogPrint (eLogWarning, "SSU2: PeerTest unexpected msg num ", msg);
return;
}
m_MsgNumReceived = msg;
}
void SSU2PeerTestSession::SendPeerTest (uint8_t msg)
{
auto addr = GetAddress ();
if (!addr) return;
Header header;
uint8_t h[32], payload[SSU2_MAX_PACKET_SIZE];
// fill packet
header.h.connID = GetDestConnID (); // 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);
htobuf64 (h + 16, GetSourceConnID ()); // source id
// payload
payload[0] = eSSU2BlkDateTime;
htobe16buf (payload + 1, 4);
htobe32buf (payload + 3, (i2p::util::GetMillisecondsSinceEpoch () + 500)/1000);
size_t payloadSize = 7;
if (msg == 6 || msg == 7)
payloadSize += CreateAddressBlock (payload + payloadSize, GetMaxPayloadSize () - payloadSize, GetRemoteEndpoint ());
payloadSize += CreatePeerTestBlock (payload + payloadSize, GetMaxPayloadSize () - payloadSize,
msg, eSSU2PeerTestCodeAccept, nullptr, m_SignedData.data (), m_SignedData.size ());
payloadSize += CreatePaddingBlock (payload + payloadSize, GetMaxPayloadSize () - payloadSize);
// encrypt
uint8_t n[12];
CreateNonce (be32toh (header.h.packetNum), n);
i2p::crypto::AEADChaCha20Poly1305 (payload, payloadSize, h, 32, addr->i, n, payload, payloadSize + 16, true);
payloadSize += 16;
header.ll[0] ^= CreateHeaderMask (addr->i, payload + (payloadSize - 24));
header.ll[1] ^= CreateHeaderMask (addr->i, payload + (payloadSize - 12));
memset (n, 0, 12);
i2p::crypto::ChaCha20 (h + 16, 16, addr->i, n, h + 16);
// send
GetServer ().Send (header.buf, 16, h + 16, 16, payload, payloadSize, GetRemoteEndpoint ());
}
void SSU2PeerTestSession::SendPeerTest (uint8_t msg, const uint8_t * signedData, size_t signedDataLen, bool delayed)
{
#if __cplusplus >= 202002L // C++20
m_SignedData.assign (signedData, signedData + signedDataLen);
#else
m_SignedData.resize (signedDataLen);
memcpy (m_SignedData.data (), signedData, signedDataLen);
#endif
if (!delayed)
SendPeerTest (msg);
// schedule resend for msgs 5 or 6
if (msg == 5 || msg == 6)
ScheduleResend (msg);
}
void SSU2PeerTestSession::SendPeerTest (uint8_t msg, const uint8_t * signedData, size_t signedDataLen,
std::shared_ptr<const i2p::data::RouterInfo::Address> addr, bool delayed)
{
if (!addr) return;
SetAddress (addr);
SendPeerTest (msg, signedData, signedDataLen, delayed);
}
void SSU2PeerTestSession::Connect ()
{
LogPrint (eLogError, "SSU2: Can't connect peer test session");
}
bool SSU2PeerTestSession::ProcessFirstIncomingMessage (uint64_t connID, uint8_t * buf, size_t len)
{
LogPrint (eLogError, "SSU2: Can't handle incoming message in peer test session");
return false;
}
void SSU2PeerTestSession::ScheduleResend (uint8_t msg)
{
if (m_NumResends < SSU2_PEER_TEST_MAX_NUM_RESENDS)
{
m_PeerTestResendTimer.expires_from_now (boost::posix_time::milliseconds(
SSU2_PEER_TEST_RESEND_INTERVAL + GetServer ().GetRng ()() % SSU2_PEER_TEST_RESEND_INTERVAL_VARIANCE));
std::weak_ptr<SSU2PeerTestSession> s(std::static_pointer_cast<SSU2PeerTestSession>(shared_from_this ()));
m_PeerTestResendTimer.async_wait ([s, msg](const boost::system::error_code& ecode)
{
if (ecode != boost::asio::error::operation_aborted)
{
auto s1 = s.lock ();
if (s1)
{
if (msg > s1->m_MsgNumReceived)
{
s1->SendPeerTest (msg);
s1->m_NumResends++;
s1->ScheduleResend (msg);
}
}
}
});
}
}
SSU2HolePunchSession::SSU2HolePunchSession (SSU2Server& server, uint32_t nonce,
const boost::asio::ip::udp::endpoint& remoteEndpoint,
std::shared_ptr<const i2p::data::RouterInfo::Address> addr):
SSU2Session (server), // we create full incoming session
m_NumResends (0), m_HolePunchResendTimer (server.GetService ())
{
// we are Charlie
uint64_t destConnID = htobe64 (((uint64_t)nonce << 32) | nonce); // dest id
uint32_t sourceConnID = ~destConnID;
SetSourceConnID (sourceConnID);
SetDestConnID (destConnID);
SetState (eSSU2SessionStateHolePunch);
SetRemoteEndpoint (remoteEndpoint);
SetAddress (addr);
SetTerminationTimeout (SSU2_RELAY_NONCE_EXPIRATION_TIMEOUT);
}
void SSU2HolePunchSession::SendHolePunch ()
{
auto addr = GetAddress ();
if (!addr) return;
auto& ep = GetRemoteEndpoint ();
LogPrint (eLogDebug, "SSU2: Sending HolePunch to ", ep);
Header header;
uint8_t h[32], payload[SSU2_MAX_PACKET_SIZE];
// fill packet
header.h.connID = GetDestConnID (); // 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);
htobuf64 (h + 16, GetSourceConnID ()); // source id
RAND_bytes (h + 24, 8); // header token, to be ignored by Alice
// payload
payload[0] = eSSU2BlkDateTime;
htobe16buf (payload + 1, 4);
htobe32buf (payload + 3, (i2p::util::GetMillisecondsSinceEpoch () + 500)/1000);
size_t payloadSize = 7;
payloadSize += CreateAddressBlock (payload + payloadSize, GetMaxPayloadSize () - payloadSize, ep);
// relay response block
if (payloadSize + m_RelayResponseBlock.size () < GetMaxPayloadSize ())
{
memcpy (payload + payloadSize, m_RelayResponseBlock.data (), m_RelayResponseBlock.size ());
payloadSize += m_RelayResponseBlock.size ();
}
payloadSize += CreatePaddingBlock (payload + payloadSize, GetMaxPayloadSize () - payloadSize);
// encrypt
uint8_t n[12];
CreateNonce (be32toh (header.h.packetNum), n);
i2p::crypto::AEADChaCha20Poly1305 (payload, payloadSize, h, 32, addr->i, n, payload, payloadSize + 16, true);
payloadSize += 16;
header.ll[0] ^= CreateHeaderMask (addr->i, payload + (payloadSize - 24));
header.ll[1] ^= CreateHeaderMask (addr->i, payload + (payloadSize - 12));
memset (n, 0, 12);
i2p::crypto::ChaCha20 (h + 16, 16, addr->i, n, h + 16);
// send
GetServer ().Send (header.buf, 16, h + 16, 16, payload, payloadSize, ep);
}
void SSU2HolePunchSession::SendHolePunch (const uint8_t * relayResponseBlock, size_t relayResponseBlockLen)
{
#if __cplusplus >= 202002L // C++20
m_RelayResponseBlock.assign (relayResponseBlock, relayResponseBlock + relayResponseBlockLen);
#else
m_RelayResponseBlock.resize (relayResponseBlockLen);
memcpy (m_RelayResponseBlock.data (), relayResponseBlock, relayResponseBlockLen);
#endif
SendHolePunch ();
ScheduleResend ();
}
void SSU2HolePunchSession::ScheduleResend ()
{
if (m_NumResends < SSU2_HOLE_PUNCH_MAX_NUM_RESENDS)
{
m_HolePunchResendTimer.expires_from_now (boost::posix_time::milliseconds(
SSU2_HOLE_PUNCH_RESEND_INTERVAL + GetServer ().GetRng ()() % SSU2_HOLE_PUNCH_RESEND_INTERVAL_VARIANCE));
std::weak_ptr<SSU2HolePunchSession> s(std::static_pointer_cast<SSU2HolePunchSession>(shared_from_this ()));
m_HolePunchResendTimer.async_wait ([s](const boost::system::error_code& ecode)
{
if (ecode != boost::asio::error::operation_aborted)
{
auto s1 = s.lock ();
if (s1 && s1->GetState () == eSSU2SessionStateHolePunch)
{
s1->SendHolePunch ();
s1->m_NumResends++;
s1->ScheduleResend ();
}
}
});
}
}
bool SSU2HolePunchSession::ProcessFirstIncomingMessage (uint64_t connID, uint8_t * buf, size_t len)
{
m_HolePunchResendTimer.cancel ();
return SSU2Session::ProcessFirstIncomingMessage (connID, buf, len);
}
}
}