There are some suspicions about threads synchronization. It seems there may be data races.

[LLE8]

NTCP2.cpp

void NTCP2Session::Terminate ()

i2pd/libi2pd/NTCP2.cpp

Line 579 in 22dd724

if (!m_IntermediateQueue.empty ())

Compare with similar code

i2pd/libi2pd/NTCP2.cpp

Line 1666 in 22dd724

std::lock_guard<std::mutex> l(m_IntermediateQueueMutex);

and

i2pd/libi2pd/NTCP2.cpp

Line 1679 in 22dd724

std::lock_guard<std::mutex> l(m_IntermediateQueueMutex);

UDPTunnel.cpp

1
void I2PUDPServerTunnel::Stop ()

i2pd/libi2pd_client/UDPTunnel.cpp

Line 357 in 22dd724

m_Sessions.clear ();

2
void I2PUDPClientTunnel::Stop ()

i2pd/libi2pd_client/UDPTunnel.cpp

Line 436 in 22dd724

m_Sessions.clear();

3
void I2PUDPClientTunnel::HandleRecvFromLocal (const boost::system::error_code & ec, std::size_t transferred)

i2pd/libi2pd_client/UDPTunnel.cpp

Line 499 in 22dd724

auto itr = m_Sessions.find (remotePort);

4
void I2PUDPClientTunnel::HandleRecvFromI2PRaw (uint16_t fromPort, uint16_t toPort, const uint8_t * buf, size_t len)

i2pd/libi2pd_client/UDPTunnel.cpp

Line 640 in 22dd724

auto itr = m_Sessions.find (toPort);

Compare with similar code

i2pd/libi2pd_client/UDPTunnel.cpp

Line 121 in 22dd724

std::lock_guard<std::mutex> lock(m_SessionsMutex);

and

i2pd/libi2pd_client/UDPTunnel.cpp

Line 150 in 22dd724

std::lock_guard<std::mutex> lock(m_SessionsMutex);

Datagram.cpp

1
DatagramDestination::~DatagramDestination ()

i2pd/libi2pd/Datagram.cpp

Line 37 in 22dd724

m_Sessions.clear();

2
void DatagramDestination::CleanUp ()

i2pd/libi2pd/Datagram.cpp

Line 485 in 22dd724

if (m_Sessions.empty ()) return;

[LLE8]

ClientContext.cpp

1
std::shared_ptr ClientContext::CreateNewLocalDestination (const i2p::data::PrivateKeys& keys, bool isPublic,
const i2p::util::Mapping * params)

i2pd/libi2pd_client/ClientContext.cpp

Line 409 in 22b9ad1

auto it = m_Destinations.find (keys.GetPublic ()->GetIdentHash ());

std::shared_ptr ClientContext::CreateNewLocalDestination (boost::asio::io_context& service,
const i2p::data::PrivateKeys& keys, bool isPublic, const i2p::util::Mapping * params)

i2pd/libi2pd_client/ClientContext.cpp

Line 424 in 22b9ad1

auto it = m_Destinations.find (keys.GetPublic ()->GetIdentHash ());

std::shared_ptr ClientContext::FindLocalDestination (const i2p::data::IdentHash& destination) const

i2pd/libi2pd_client/ClientContext.cpp

Line 449 in 22b9ad1

auto it = m_Destinations.find (destination);

Compare with

i2pd/libi2pd_client/ClientContext.cpp

Line 395 in 22b9ad1

std::unique_lock<std::mutex> l(m_DestinationsMutex);

2
void ClientContext::ReadTunnels (const std::string& tunConf, int& numClientTunnels, int& numServerTunnels)

i2pd/libi2pd_client/ClientContext.cpp

Line 682 in 22b9ad1

auto ins = m_ClientForwards.insert (std::make_pair (end, clientTunnel));

void ClientContext::VisitTunnels (bool clean)

i2pd/libi2pd_client/ClientContext.cpp

Line 1112 in 22b9ad1

for (auto it = m_ClientForwards.begin (); it != m_ClientForwards.end ();)

i2pd/libi2pd_client/ClientContext.cpp

Line 1123 in 22b9ad1

for (auto it = m_ServerForwards.begin (); it != m_ServerForwards.end ();)

void ClientContext::Start () - not sure

i2pd/libi2pd_client/ClientContext.cpp

Line 124 in 22b9ad1

if (!m_ServerForwards.empty ())

Compare with

i2pd/libi2pd_client/ClientContext.cpp

Line 1081 in 22b9ad1

std::lock_guard<std::mutex> lock(m_ForwardsMutex);

3
Various m_ClientTunnels and m_ServerTunnels erase(), clear(), insert() - not sure about multithreading

To be continued

[orignal]

DatagramDestination::~DatagramDestination ()

Doesn't make sense in destructor.

[LLE8]

If this destructor is triggered when the statement delete m_DatagramDestination; is executed,
might it need mutex protection somewhere around delete?

i2pd/libi2pd/Destination.cpp

Line 1132 in 34101fb

delete m_DatagramDestination;

May be whole block?

		if (m_DatagramDestination)
		{
			LogPrint(eLogDebug, "Destination: -> Stopping Datagram Destination");
			delete m_DatagramDestination;
			m_DatagramDestination = nullptr;
		}

[orignal]

This situation is even worse. Datagram destination can get delete while UDP tunnels still have pointer to it. Should be changed to shared_ptr/weak_ptr.

[orignal]

7ad86b2