std::shared_ptr<I2NPMessage> RequestedDestination::CreateRequestMessage (std::shared_ptr<const RouterInfo> router,
std::shared_ptr<const i2p::tunnel::InboundTunnel> replyTunnel)
{
I2NPMessage * msg = i2p::CreateRouterInfoDatabaseLookupMsg (m_Destination,
replyTunnel->GetNextIdentHash (), replyTunnel->GetNextTunnelID (), m_IsExploratory,
&m_ExcludedPeers);
m_ExcludedPeers.insert (router->GetIdentHash ());
m_CreationTime = i2p::util::GetSecondsSinceEpoch ();
return ToSharedI2NPMessage (msg);
}
void RouterContext::HandleI2NPMessage (const uint8_t * buf, size_t len, std::shared_ptr<i2p::tunnel::InboundTunnel> from)
{
i2p::HandleI2NPMessage (ToSharedI2NPMessage(CreateI2NPMessage (buf, GetI2NPMessageLength (buf), from)));
}
std::shared_ptr<I2NPMessage> GarlicRoutingSession::WrapSingleMessage (std::shared_ptr<const I2NPMessage> msg)
{
auto m = ToSharedI2NPMessage(NewI2NPMessage ());
m->Align (12); // in order to get buf aligned to 16 (12 + 4)
size_t len = 0;
uint8_t * buf = m->GetPayload () + 4; // 4 bytes for length
// find non-expired tag
bool tagFound = false;
SessionTag tag;
if (m_NumTags > 0)
{
uint32_t ts = i2p::util::GetSecondsSinceEpoch ();
while (!m_SessionTags.empty ())
{
if (ts < m_SessionTags.front ().creationTime + OUTGOING_TAGS_EXPIRATION_TIMEOUT)
{
tag = m_SessionTags.front ();
m_SessionTags.pop_front (); // use same tag only once
tagFound = true;
break;
}
else
m_SessionTags.pop_front (); // remove expired tag
}
}
// create message
if (!tagFound) // new session
{
LogPrint ("No garlic tags available. Use ElGamal");
if (!m_Destination)
{
LogPrint ("Can't use ElGamal for unknown destination");
return nullptr;
}
// create ElGamal block
ElGamalBlock elGamal;
memcpy (elGamal.sessionKey, m_SessionKey, 32);
m_Rnd.GenerateBlock (elGamal.preIV, 32); // Pre-IV
uint8_t iv[32]; // IV is first 16 bytes
CryptoPP::SHA256().CalculateDigest(iv, elGamal.preIV, 32);
m_Destination->GetElGamalEncryption ()->Encrypt ((uint8_t *)&elGamal, sizeof(elGamal), buf, true);
m_Encryption.SetIV (iv);
buf += 514;
len += 514;
}
else // existing session
{
// session tag
memcpy (buf, tag, 32);
uint8_t iv[32]; // IV is first 16 bytes
CryptoPP::SHA256().CalculateDigest(iv, tag, 32);
m_Encryption.SetIV (iv);
buf += 32;
len += 32;
}
// AES block
len += CreateAESBlock (buf, msg);
htobe32buf (m->GetPayload (), len);
m->len += len + 4;
m->FillI2NPMessageHeader (eI2NPGarlic);
return m;
}
