From 828efcc9ebff12efbaa9e74adf4a3ebb9ecde463 Mon Sep 17 00:00:00 2001
From: PobreGato <315121269+pobregat0@users.noreply.github.com>
Date: Mon, 24 Aug 2026 01:09:26 +0300
Subject: [PATCH] hold udp tunnel and session by shared_ptr in socket handlers

---
 libi2pd_client/UDPTunnel.cpp | 18 +++++++++++++-----
 libi2pd_client/UDPTunnel.h   |  4 +++-
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/libi2pd_client/UDPTunnel.cpp b/libi2pd_client/UDPTunnel.cpp
index 300f74ac..6c509c08 100644
--- a/libi2pd_client/UDPTunnel.cpp
+++ b/libi2pd_client/UDPTunnel.cpp
@@ -155,6 +155,7 @@ namespace client
 		auto s = std::make_shared<UDPSession>(boost::asio::ip::udp::endpoint(addr, 0),
 			m_LocalDest, m_RemoteEndpoint, ih, localPort, remotePort);
 		s->SetMaxWindow (m_MaxWindow);
+		s->Receive ();
 		std::lock_guard<std::mutex> lock(m_SessionsMutex);
 		m_Sessions.emplace (idx, s);
 		return s;
@@ -377,14 +378,18 @@ namespace client
 		IPSocket.set_option (boost::asio::socket_base::receive_buffer_size (I2P_UDP_SOCKET_BUFFER_SIZE));
 		IPSocket.set_option (boost::asio::socket_base::send_buffer_size (I2P_UDP_SOCKET_BUFFER_SIZE));
 		IPSocket.non_blocking (true);
-		Receive();
+		// Receive is not called here: it takes a shared pointer to this session,
+		// which does not exist yet while the constructor runs
 	}
 
 	void UDPSession::Receive()
 	{
 		LogPrint(eLogDebug, "UDPSession: Receive");
-		IPSocket.async_receive_from(boost::asio::buffer(m_Buffer, I2P_UDP_MAX_MTU),
-			FromEndpoint, std::bind(&UDPSession::HandleReceived, this, std::placeholders::_1, std::placeholders::_2));
+		IPSocket.async_receive_from(boost::asio::buffer(m_Buffer, I2P_UDP_MAX_MTU), FromEndpoint,
+			[s = std::static_pointer_cast<UDPSession>(shared_from_this ())](const boost::system::error_code& ecode, std::size_t len)
+			{
+				s->HandleReceived (ecode, len);
+			});
 	}
 
 	void UDPSession::HandleReceived(const boost::system::error_code & ecode, std::size_t len)
@@ -662,8 +667,11 @@ namespace client
 
 	void I2PUDPClientTunnel::RecvFromLocal ()
 	{
-		m_LocalSocket->async_receive_from (boost::asio::buffer (m_RecvBuff, I2P_UDP_MAX_MTU),
-			m_RecvEndpoint, std::bind (&I2PUDPClientTunnel::HandleRecvFromLocal, this, std::placeholders::_1, std::placeholders::_2));
+		m_LocalSocket->async_receive_from (boost::asio::buffer (m_RecvBuff, I2P_UDP_MAX_MTU), m_RecvEndpoint,
+			[s = std::static_pointer_cast<I2PUDPClientTunnel>(shared_from_this ())](const boost::system::error_code& ecode, std::size_t transferred)
+			{
+				s->HandleRecvFromLocal (ecode, transferred);
+			});
 	}
 
 	void I2PUDPClientTunnel::HandleRecvFromLocal (const boost::system::error_code & ec, std::size_t transferred)
diff --git a/libi2pd_client/UDPTunnel.h b/libi2pd_client/UDPTunnel.h
index debe1a67..3b77615f 100644
--- a/libi2pd_client/UDPTunnel.h
+++ b/libi2pd_client/UDPTunnel.h
@@ -55,7 +55,9 @@ namespace client
 	/** local socket buffers, not datagram size */
 	const size_t I2P_UDP_SOCKET_BUFFER_SIZE = 4*1024*1024;
 
-	struct UDPConnection
+	// handlers of both sides are queued on sockets and can outlive the object
+	// they belong to, so they hold it by a shared pointer
+	struct UDPConnection: public std::enable_shared_from_this<UDPConnection>
 	{
 		std::shared_ptr<i2p::datagram::DatagramDestination> m_Destination;
 		std::weak_ptr<i2p::datagram::DatagramSession> m_LastDatagramSession;