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// OpenVPN -- An application to securely tunnel IP networks
// over a single port, with support for SSL/TLS-based
// session authentication and key exchange,
// packet encryption, packet authentication, and
// packet compression.
//
// Copyright (C) 2025- OpenVPN Inc.
//
// SPDX-License-Identifier: MPL-2.0 OR AGPL-3.0-only WITH openvpn3-openssl-exception
//
#include <openvpn/io/io.hpp>
#include <openvpn/win/winerr.hpp>
namespace openvpn {
/**
* @brief Wrapper for an asynchronous handle supporting cancellation and closure.
*
* Automatically manages lifecycle by canceling and closing the handle if not already done.
*/
class CancelableHandle
{
public:
/**
* @brief Constructs with the given I/O context.
* @param io_context I/O context for asynchronous operations.
*/
CancelableHandle(openvpn_io::io_context &io_context)
: handle_(io_context)
{
}
/** @brief Destructor ensures handle cancellation and closure. */
~CancelableHandle()
{
cancel_and_close();
}
/**
* @brief Checks if the handle's event is already signaled.
* @throws Exception if event is signaled or abandoned, or on WaitForSingleObject failure.
*/
void check_is_already_signalled()
{
DWORD status = ::WaitForSingleObject(handle_.native_handle(), 0);
const Win::LastError err;
switch (status)
{
case WAIT_TIMEOUT: // expected status
break;
case WAIT_OBJECT_0:
throw Exception("CancelableHandle: destroy event is already signaled");
case WAIT_ABANDONED:
throw Exception("CancelableHandle: destroy event is abandoned");
default:
OPENVPN_THROW_EXCEPTION("CancelableHandle: WaitForSingleObject failed: " << err.message());
}
}
/** @brief Cancels and closes the handle if not already closed. */
void cancel_and_close()
{
if (!*is_closed_)
{
*is_closed_ = true;
try
{
handle_.cancel();
}
catch (const openvpn_io::system_error &)
{
// this is fine, handle is likely not yet initialized
}
handle_.close();
}
}
/**
* @brief Assigns a native Windows handle.
* @param handle The native HANDLE to manage.
*/
void assign(HANDLE handle)
{
handle_.assign(handle);
is_closed_ = std::make_shared<bool>(false);
}
/**
* @brief Initiates an asynchronous wait on the handle.
* @param handler Handler executed on completion, unless closed.
*/
template <typename Handler>
void async_wait(Handler &&handler)
{
handle_.async_wait([is_closed = is_closed_, handler = std::forward<Handler>(handler)](const openvpn_io::error_code &ec)
{
if (!*is_closed)
{
handler(ec);
} });
}
private:
openvpn_io::windows::object_handle handle_; ///< Asynchronous Windows object handle.
std::shared_ptr<bool> is_closed_ = std::make_shared<bool>(false); ///< Indicates if handle is closed.
};
} // namespace openvpn
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