I2P: End-to-End encrypted and anonymous Internet https://i2pd.website/
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#include <string.h>
#include <vector>
#include "Crypto.h"
#include "Log.h"
#include "TunnelBase.h"
#include "RouterContext.h"
#include "Destination.h"
#include "Datagram.h"
namespace i2p
{
namespace datagram
{
DatagramDestination::DatagramDestination (std::shared_ptr<i2p::client::ClientDestination> owner):
m_Owner (owner.get()), m_Receiver (nullptr)
{
}
DatagramDestination::~DatagramDestination ()
{
m_Sessions.clear();
}
void DatagramDestination::SendDatagramTo (const uint8_t * payload, size_t len, const i2p::data::IdentHash& ident, uint16_t fromPort, uint16_t toPort)
{
auto owner = m_Owner;
auto i = owner->GetIdentity();
uint8_t buf[MAX_DATAGRAM_SIZE];
auto identityLen = i->ToBuffer (buf, MAX_DATAGRAM_SIZE);
uint8_t * signature = buf + identityLen;
auto signatureLen = i->GetSignatureLen ();
uint8_t * buf1 = signature + signatureLen;
size_t headerLen = identityLen + signatureLen;
memcpy (buf1, payload, len);
if (i->GetSigningKeyType () == i2p::data::SIGNING_KEY_TYPE_DSA_SHA1)
{
uint8_t hash[32];
SHA256(buf1, len, hash);
owner->Sign (hash, 32, signature);
}
else
owner->Sign (buf1, len, signature);
auto msg = CreateDataMessage (buf, len + headerLen, fromPort, toPort);
auto session = ObtainSession(ident);
session->SendMsg(msg);
}
void DatagramDestination::HandleDatagram (uint16_t fromPort, uint16_t toPort, const uint8_t * buf, size_t len)
{
i2p::data::IdentityEx identity;
size_t identityLen = identity.FromBuffer (buf, len);
const uint8_t * signature = buf + identityLen;
size_t headerLen = identityLen + identity.GetSignatureLen ();
bool verified = false;
if (identity.GetSigningKeyType () == i2p::data::SIGNING_KEY_TYPE_DSA_SHA1)
{
uint8_t hash[32];
SHA256(buf + headerLen, len - headerLen, hash);
verified = identity.Verify (hash, 32, signature);
}
else
verified = identity.Verify (buf + headerLen, len - headerLen, signature);
if (verified)
{
auto r = FindReceiver(toPort);
if(r)
r(identity, fromPort, toPort, buf + headerLen, len -headerLen);
else
LogPrint (eLogWarning, "DatagramDestination: no receiver for port ", toPort);
}
else
LogPrint (eLogWarning, "Datagram signature verification failed");
}
DatagramDestination::Receiver DatagramDestination::FindReceiver(uint16_t port)
{
std::lock_guard<std::mutex> lock(m_ReceiversMutex);
Receiver r = m_Receiver;
auto itr = m_ReceiversByPorts.find(port);
if (itr != m_ReceiversByPorts.end())
r = itr->second;
return r;
}
void DatagramDestination::HandleDataMessagePayload (uint16_t fromPort, uint16_t toPort, const uint8_t * buf, size_t len)
{
// unzip it
uint8_t uncompressed[MAX_DATAGRAM_SIZE];
size_t uncompressedLen = m_Inflator.Inflate (buf, len, uncompressed, MAX_DATAGRAM_SIZE);
if (uncompressedLen)
HandleDatagram (fromPort, toPort, uncompressed, uncompressedLen);
}
std::shared_ptr<I2NPMessage> DatagramDestination::CreateDataMessage (const uint8_t * payload, size_t len, uint16_t fromPort, uint16_t toPort)
{
auto msg = NewI2NPMessage ();
uint8_t * buf = msg->GetPayload ();
buf += 4; // reserve for length
size_t size = m_Deflator.Deflate (payload, len, buf, msg->maxLen - msg->len);
if (size)
{
htobe32buf (msg->GetPayload (), size); // length
htobe16buf (buf + 4, fromPort); // source port
htobe16buf (buf + 6, toPort); // destination port
buf[9] = i2p::client::PROTOCOL_TYPE_DATAGRAM; // datagram protocol
msg->len += size + 4;
msg->FillI2NPMessageHeader (eI2NPData);
}
else
msg = nullptr;
return msg;
}
void DatagramDestination::CleanUp ()
{
if (m_Sessions.empty ()) return;
auto now = i2p::util::GetMillisecondsSinceEpoch();
LogPrint(eLogDebug, "DatagramDestination: clean up sessions");
std::lock_guard<std::mutex> lock(m_SessionsMutex);
// for each session ...
for (auto it = m_Sessions.begin (); it != m_Sessions.end (); )
{
// check if expired
if (now - it->second->LastActivity() >= DATAGRAM_SESSION_MAX_IDLE)
{
LogPrint(eLogInfo, "DatagramDestination: expiring idle session with ", it->first.ToBase32());
it = m_Sessions.erase (it); // we are expired
}
else
it++;
}
}
std::shared_ptr<DatagramSession> DatagramDestination::ObtainSession(const i2p::data::IdentHash & ident)
{
std::shared_ptr<DatagramSession> session = nullptr;
std::lock_guard<std::mutex> lock(m_SessionsMutex);
auto itr = m_Sessions.find(ident);
if (itr == m_Sessions.end()) {
// not found, create new session
session = std::make_shared<DatagramSession>(m_Owner, ident);
m_Sessions[ident] = session;
} else {
session = itr->second;
}
return session;
}
std::shared_ptr<DatagramSession::Info> DatagramDestination::GetInfoForRemote(const i2p::data::IdentHash & remote)
{
std::lock_guard<std::mutex> lock(m_SessionsMutex);
for ( auto & item : m_Sessions)
{
if(item.first == remote) return std::make_shared<DatagramSession::Info>(item.second->GetSessionInfo());
}
return nullptr;
}
DatagramSession::DatagramSession(i2p::client::ClientDestination * localDestination,
const i2p::data::IdentHash & remoteIdent) :
m_LocalDestination(localDestination),
m_RemoteIdentity(remoteIdent),
m_LastUse(i2p::util::GetMillisecondsSinceEpoch ()),
m_LastPathChange(0),
m_LastSuccess(0)
{
}
void DatagramSession::SendMsg(std::shared_ptr<I2NPMessage> msg)
{
// we used this session
m_LastUse = i2p::util::GetMillisecondsSinceEpoch();
// schedule send
m_LocalDestination->GetService().post(std::bind(&DatagramSession::HandleSend, this, msg));
}
DatagramSession::Info DatagramSession::GetSessionInfo() const
{
if(!m_RoutingSession)
return DatagramSession::Info(nullptr, nullptr, m_LastUse, m_LastSuccess);
auto routingPath = m_RoutingSession->GetSharedRoutingPath();
if (!routingPath)
return DatagramSession::Info(nullptr, nullptr, m_LastUse, m_LastSuccess);
auto lease = routingPath->remoteLease;
auto tunnel = routingPath->outboundTunnel;
if(lease)
{
if(tunnel)
return DatagramSession::Info(lease->tunnelGateway, tunnel->GetEndpointIdentHash(), m_LastUse, m_LastSuccess);
else
return DatagramSession::Info(lease->tunnelGateway, nullptr, m_LastUse, m_LastSuccess);
}
else if(tunnel)
return DatagramSession::Info(nullptr, tunnel->GetEndpointIdentHash(), m_LastUse, m_LastSuccess);
else
return DatagramSession::Info(nullptr, nullptr, m_LastUse, m_LastSuccess);
}
void DatagramSession::HandleSend(std::shared_ptr<I2NPMessage> msg)
{
if(!m_RoutingSession)
{
// try to get one
if(m_RemoteLeaseSet) m_RoutingSession = m_LocalDestination->GetRoutingSession(m_RemoteLeaseSet, true);
else
{
UpdateLeaseSet(msg);
return;
}
}
// do we have a routing session?
if(m_RoutingSession)
{
// should we switch paths?
if(ShouldUpdateRoutingPath ())
{
LogPrint(eLogDebug, "DatagramSession: try getting new routing path");
// try switching paths
auto path = GetNextRoutingPath();
if(path)
UpdateRoutingPath (path);
else
ResetRoutingPath();
}
auto routingPath = m_RoutingSession->GetSharedRoutingPath ();
// make sure we have a routing path
if (routingPath)
{
auto outboundTunnel = routingPath->outboundTunnel;
if (outboundTunnel)
{
if(outboundTunnel->IsEstablished())
{
m_LastSuccess = i2p::util::GetMillisecondsSinceEpoch ();
// we have a routing path and routing session and the outbound tunnel we are using is good
// wrap message with routing session and send down routing path's outbound tunnel wrapped for the IBGW
auto m = m_RoutingSession->WrapSingleMessage(msg);
routingPath->outboundTunnel->SendTunnelDataMsg({i2p::tunnel::TunnelMessageBlock{
i2p::tunnel::eDeliveryTypeTunnel,
routingPath->remoteLease->tunnelGateway, routingPath->remoteLease->tunnelID,
m
}});
return;
}
}
}
}
auto now = i2p::util::GetMillisecondsSinceEpoch ();
// if this path looks dead reset the routing path since we didn't seem to be able to get a path in time
if (m_LastPathChange && now - m_LastPathChange >= DATAGRAM_SESSION_PATH_TIMEOUT ) ResetRoutingPath();
UpdateLeaseSet(msg);
}
void DatagramSession::UpdateRoutingPath(const std::shared_ptr<i2p::garlic::GarlicRoutingPath> & path)
{
if(m_RoutingSession == nullptr && m_RemoteLeaseSet)
m_RoutingSession = m_LocalDestination->GetRoutingSession(m_RemoteLeaseSet, true);
if(!m_RoutingSession) return;
// set routing path and update time we last updated the routing path
m_RoutingSession->SetSharedRoutingPath (path);
m_LastPathChange = i2p::util::GetMillisecondsSinceEpoch ();
}
bool DatagramSession::ShouldUpdateRoutingPath() const
{
auto now = i2p::util::GetMillisecondsSinceEpoch ();
// we need to rotate paths becuase the routing path is too old
if (now - m_LastPathChange >= DATAGRAM_SESSION_PATH_SWITCH_INTERVAL) return true;
// our path looks dead so we need to rotate paths
if (now - m_LastSuccess >= DATAGRAM_SESSION_PATH_TIMEOUT) return true;
// if we have a routing session and routing path we don't need to switch paths
return m_RoutingSession != nullptr && m_RoutingSession->GetSharedRoutingPath () != nullptr;
}
bool DatagramSession::ShouldSwitchLease() const
{
std::shared_ptr<i2p::garlic::GarlicRoutingPath> routingPath = nullptr;
std::shared_ptr<const i2p::data::Lease> currentLease = nullptr;
if(m_RoutingSession)
routingPath = m_RoutingSession->GetSharedRoutingPath ();
if(routingPath)
currentLease = routingPath->remoteLease;
if(currentLease) // if we have a lease return true if it's about to expire otherwise return false
return currentLease->ExpiresWithin( DATAGRAM_SESSION_LEASE_HANDOVER_WINDOW, DATAGRAM_SESSION_LEASE_HANDOVER_FUDGE );
// we have no current lease, we should switch
return true;
}
std::shared_ptr<i2p::garlic::GarlicRoutingPath> DatagramSession::GetNextRoutingPath()
{
std::shared_ptr<i2p::tunnel::OutboundTunnel> outboundTunnel = nullptr;
std::shared_ptr<i2p::garlic::GarlicRoutingPath> routingPath = nullptr;
// get existing routing path if we have one
if(m_RoutingSession)
routingPath = m_RoutingSession->GetSharedRoutingPath();
// do we have an existing outbound tunnel and routing path?
if(routingPath && routingPath->outboundTunnel)
{
// is the outbound tunnel we are using good?
if (routingPath->outboundTunnel->IsEstablished())
{
// ya so let's stick with it
outboundTunnel = routingPath->outboundTunnel;
}
else
outboundTunnel = m_LocalDestination->GetTunnelPool()->GetNextOutboundTunnel(routingPath->outboundTunnel); // no so we'll switch outbound tunnels
}
// do we have an outbound tunnel that works already ?
if(!outboundTunnel)
outboundTunnel = m_LocalDestination->GetTunnelPool()->GetNextOutboundTunnel(); // no, let's get a new outbound tunnel as we probably just started
if(outboundTunnel)
{
std::shared_ptr<const i2p::data::Lease> lease = nullptr;
// should we switch leases ?
if (ShouldSwitchLease ())
{
// yes, get next available lease
lease = GetNextLease();
}
else if (routingPath)
{
if(routingPath->remoteLease)
{
if(routingPath->remoteLease->ExpiresWithin(DATAGRAM_SESSION_LEASE_HANDOVER_WINDOW, DATAGRAM_SESSION_LEASE_HANDOVER_FUDGE))
lease = GetNextLease();
else
lease = routingPath->remoteLease;
}
}
else
lease = GetNextLease();
if(lease)
{
// we have a valid lease to use and an outbound tunnel
// create new routing path
uint32_t now = i2p::util::GetSecondsSinceEpoch();
routingPath = std::make_shared<i2p::garlic::GarlicRoutingPath>(i2p::garlic::GarlicRoutingPath{
outboundTunnel,
lease,
0,
now,
0
});
}
else // we don't have a new routing path to give
routingPath = nullptr;
}
return routingPath;
}
void DatagramSession::ResetRoutingPath()
{
if(m_RoutingSession)
{
auto routingPath = m_RoutingSession->GetSharedRoutingPath();
if(routingPath && routingPath->remoteLease) // we have a remote lease already specified and a routing path
{
// get outbound tunnel on this path
auto outboundTunnel = routingPath->outboundTunnel;
// is this outbound tunnel there and established
if (outboundTunnel && outboundTunnel->IsEstablished())
m_InvalidIBGW.push_back(routingPath->remoteLease->tunnelGateway); // yes, let's mark remote lease as dead because the outbound tunnel seems fine
}
// reset the routing path
UpdateRoutingPath(nullptr);
}
}
std::shared_ptr<const i2p::data::Lease> DatagramSession::GetNextLease()
{
auto now = i2p::util::GetMillisecondsSinceEpoch ();
std::shared_ptr<const i2p::data::Lease> next = nullptr;
if(m_RemoteLeaseSet)
{
std::vector<i2p::data::IdentHash> exclude;
for(const auto & ident : m_InvalidIBGW)
exclude.push_back(ident);
// find get all leases that are not in our ban list and are not going to expire within our lease set handover window + fudge
auto leases = m_RemoteLeaseSet->GetNonExpiredLeasesExcluding( [&exclude, now] (const i2p::data::Lease & l) -> bool {
if(exclude.size())
{
auto end = std::end(exclude);
return std::find_if(exclude.begin(), end, [l, now] ( const i2p::data::IdentHash & ident) -> bool {
return ident == l.tunnelGateway;
}) != end;
}
else
return false;
});
if(leases.size())
{
// pick random valid next lease
uint32_t idx = rand() % leases.size();
next = leases[idx];
}
else
LogPrint(eLogWarning, "DatagramDestination: no leases to use");
}
return next;
}
void DatagramSession::UpdateLeaseSet(std::shared_ptr<I2NPMessage> msg)
{
LogPrint(eLogInfo, "DatagramSession: updating lease set");
m_LocalDestination->RequestDestination(m_RemoteIdentity, std::bind(&DatagramSession::HandleGotLeaseSet, this, std::placeholders::_1, msg));
}
void DatagramSession::HandleGotLeaseSet(std::shared_ptr<const i2p::data::LeaseSet> remoteIdent, std::shared_ptr<I2NPMessage> msg)
{
if(remoteIdent)
{
// update routing session
if(m_RoutingSession)
m_RoutingSession = nullptr;
m_RoutingSession = m_LocalDestination->GetRoutingSession(remoteIdent, true);
// clear invalid IBGW as we have a new lease set
m_InvalidIBGW.clear();
m_RemoteLeaseSet = remoteIdent;
// update routing path
auto path = GetNextRoutingPath();
if (path)
UpdateRoutingPath(path);
else
ResetRoutingPath();
// send the message that was queued if it was provided
if(msg)
HandleSend(msg);
}
}
}
}