#include "util/I2PEndian.h"
#include <string.h>
#include "util/Log.h"
#include "NetDb.h"
#include "I2NPProtocol.h"
#include "transport/Transports.h"
#include "RouterContext.h"
#include "TunnelEndpoint.h"
namespace i2p
{
namespace tunnel
{
TunnelEndpoint::~TunnelEndpoint ()
{
}
void TunnelEndpoint::HandleDecryptedTunnelDataMsg (std::shared_ptr<I2NPMessage> msg)
{
m_NumReceivedBytes += TUNNEL_DATA_MSG_SIZE;
uint8_t * decrypted = msg->GetPayload () + 20; // 4 + 16
uint8_t * zero = (uint8_t *)memchr (decrypted + 4, 0, TUNNEL_DATA_ENCRYPTED_SIZE - 4); // witout 4-byte checksum
if (zero)
{
uint8_t * fragment = zero + 1;
// verify checksum
memcpy (msg->GetPayload () + TUNNEL_DATA_MSG_SIZE, msg->GetPayload () + 4, 16); // copy iv to the end
uint8_t hash[32];
CryptoPP::SHA256().CalculateDigest (hash, fragment, TUNNEL_DATA_MSG_SIZE -(fragment - msg->GetPayload ()) + 16); // payload + iv
if (memcmp (hash, decrypted, 4))
{
LogPrint (eLogError, "TunnelMessage: checksum verification failed");
return;
}
// process fragments
while (fragment < decrypted + TUNNEL_DATA_ENCRYPTED_SIZE)
{
uint8_t flag = fragment[0];
fragment++;
bool isFollowOnFragment = flag & 0x80, isLastFragment = true;
uint32_t msgID = 0;
int fragmentNum = 0;
TunnelMessageBlockEx m;
if (!isFollowOnFragment)
{
// first fragment
m.deliveryType = (TunnelDeliveryType)((flag >> 5) & 0x03);
switch (m.deliveryType)
{
case eDeliveryTypeLocal: // 0
break;
case eDeliveryTypeTunnel: // 1
m.tunnelID = bufbe32toh (fragment);
fragment += 4; // tunnelID
m.hash = i2p::data::IdentHash (fragment);
fragment += 32; // hash
break;
case eDeliveryTypeRouter: // 2
m.hash = i2p::data::IdentHash (fragment);
fragment += 32; // to hash
break;
default:
;
}
bool isFragmented = flag & 0x08;
if (isFragmented)
{
// Message ID
msgID = bufbe32toh (fragment);
fragment += 4;
isLastFragment = false;
}
}
else
{
// follow on
msgID = bufbe32toh (fragment); // MessageID
fragment += 4;
fragmentNum = (flag >> 1) & 0x3F; // 6 bits
isLastFragment = flag & 0x01;
}
uint16_t size = bufbe16toh (fragment);
fragment += 2;
msg->offset = fragment - msg->buf;
msg->len = msg->offset + size;
if (fragment + size < decrypted + TUNNEL_DATA_ENCRYPTED_SIZE)
{
// this is not last message. we have to copy it
m.data = ToSharedI2NPMessage (NewI2NPShortMessage ());
m.data->offset += TUNNEL_GATEWAY_HEADER_SIZE; // reserve room for TunnelGateway header
m.data->len += TUNNEL_GATEWAY_HEADER_SIZE;
*(m.data) = *msg;
}
else
m.data = msg;
if (!isFollowOnFragment && isLastFragment)
HandleNextMessage (m);
else
{
if (msgID) // msgID is presented, assume message is fragmented
{
if (!isFollowOnFragment) // create new incomlete message
{
m.nextFragmentNum = 1;
auto ret = m_IncompleteMessages.insert (std::pair<uint32_t, TunnelMessageBlockEx>(msgID, m));
if (ret.second)
HandleOutOfSequenceFragment (msgID, ret.first->second);
else
LogPrint (eLogError, "Incomplete message ", msgID, "already exists");
}
else
{
m.nextFragmentNum = fragmentNum;
HandleFollowOnFragment (msgID, isLastFragment, m);
}
}
else
LogPrint (eLogError, "Message is fragmented, but msgID is not presented");
}
fragment += size;
}
}
else
LogPrint (eLogError, "TunnelMessage: zero not found");
}
void TunnelEndpoint::HandleFollowOnFragment (uint32_t msgID, bool isLastFragment, const TunnelMessageBlockEx& m)
{
auto fragment = m.data->GetBuffer ();
auto size = m.data->GetLength ();
auto it = m_IncompleteMessages.find (msgID);
if (it != m_IncompleteMessages.end())
{
auto& msg = it->second;
if (m.nextFragmentNum == msg.nextFragmentNum)
{
if (msg.data->len + size < I2NP_MAX_MESSAGE_SIZE) // check if message is not too long
{
if (msg.data->len + size > msg.data->maxLen)
{
LogPrint (eLogInfo, "Tunnel endpoint I2NP message size ", msg.data->maxLen, " is not enough");
auto newMsg = ToSharedI2NPMessage (NewI2NPMessage ());
*newMsg = *(msg.data);
msg.data = newMsg;
}
memcpy (msg.data->buf + msg.data->len, fragment, size); // concatenate fragment
msg.data->len += size;
if (isLastFragment)
{
// message complete
HandleNextMessage (msg);
m_IncompleteMessages.erase (it);
}
else
{
msg.nextFragmentNum++;
HandleOutOfSequenceFragment (msgID, msg);
}
}
else
{
LogPrint (eLogError, "Fragment ", m.nextFragmentNum, " of message ", msgID, "exceeds max I2NP message size. Message dropped");
m_IncompleteMessages.erase (it);
}
}
else
{
LogPrint (eLogInfo, "Unexpected fragment ", (int)m.nextFragmentNum, " instead ", (int)msg.nextFragmentNum, " of message ", msgID, ". Saved");
AddOutOfSequenceFragment (msgID, m.nextFragmentNum, isLastFragment, m.data);
}
}
else
{
LogPrint (eLogInfo, "First fragment of message ", msgID, " not found. Saved");
AddOutOfSequenceFragment (msgID, m.nextFragmentNum, isLastFragment, m.data);
}
}
void TunnelEndpoint::AddOutOfSequenceFragment (uint32_t msgID, uint8_t fragmentNum, bool isLastFragment, std::shared_ptr<I2NPMessage> data)
{
auto it = m_OutOfSequenceFragments.find (msgID);
if (it == m_OutOfSequenceFragments.end ())
m_OutOfSequenceFragments.insert (std::pair<uint32_t, Fragment> (msgID, {fragmentNum, isLastFragment, data}));
}
void TunnelEndpoint::HandleOutOfSequenceFragment (uint32_t msgID, TunnelMessageBlockEx& msg)
{
auto it = m_OutOfSequenceFragments.find (msgID);
if (it != m_OutOfSequenceFragments.end ())
{
if (it->second.fragmentNum == msg.nextFragmentNum)
{
LogPrint (eLogInfo, "Out-of-sequence fragment ", (int)it->second.fragmentNum, " of message ", msgID, " found");
auto size = it->second.data->GetLength ();
if (msg.data->len + size > msg.data->maxLen)
{
LogPrint (eLogInfo, "Tunnel endpoint I2NP message size ", msg.data->maxLen, " is not enough");
auto newMsg = ToSharedI2NPMessage (NewI2NPMessage ());
*newMsg = *(msg.data);
msg.data = newMsg;
}
memcpy (msg.data->buf + msg.data->len, it->second.data->GetBuffer (), size); // concatenate out-of-sync fragment
msg.data->len += size;
if (it->second.isLastFragment)
{
// message complete
HandleNextMessage (msg);
m_IncompleteMessages.erase (msgID);
}
else
msg.nextFragmentNum++;
m_OutOfSequenceFragments.erase (it);
}
}
}
void TunnelEndpoint::HandleNextMessage (const TunnelMessageBlock& msg)
{
LogPrint (eLogInfo, "TunnelMessage: handle fragment of ", msg.data->GetLength ()," bytes. Msg type ", (int)msg.data->GetTypeID ());
switch (msg.deliveryType)
{
case eDeliveryTypeLocal:
i2p::HandleI2NPMessage (msg.data);
break;
case eDeliveryTypeTunnel:
i2p::transport::transports.SendMessage (msg.hash, i2p::CreateTunnelGatewayMsg (msg.tunnelID, msg.data));
break;
case eDeliveryTypeRouter:
if (msg.hash == i2p::context.GetRouterInfo ().GetIdentHash ()) // check if message is sent to us
i2p::HandleI2NPMessage (msg.data);
else
{
// to somebody else
if (!m_IsInbound) // outbound transit tunnel
{
/* auto typeID = msg.data->GetTypeID ();
if (typeID == eI2NPDatabaseStore || typeID == eI2NPDatabaseSearchReply )
// catch RI or reply with new list of routers
i2p::data::netdb.PostI2NPMsg (msg.data);*/
i2p::transport::transports.SendMessage (msg.hash, msg.data);
}
else // we shouldn't send this message. possible leakage
LogPrint (eLogError, "Message to another router arrived from an inbound tunnel. Dropped");
}
break;
default:
LogPrint (eLogError, "TunnelMessage: Unknown delivery type ", (int)msg.deliveryType);
};
}
}
}