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lib/socket_disconnect_operation.cpp

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+///////////////////////////////////////////////////////////////////////////////
+// Copyright (c) Lewis Baker
+// Licenced under MIT license. See LICENSE.txt for details.
+///////////////////////////////////////////////////////////////////////////////
+
+#include <cppcoro/net/socket_disconnect_operation.hpp>
+#include <cppcoro/net/socket.hpp>
+
+#include "socket_helpers.hpp"
+
+#include <system_error>
+
+#if CPPCORO_OS_WINNT
+# include <WinSock2.h>
+# include <WS2tcpip.h>
+# include <MSWSock.h>
+# include <Windows.h>
+
+bool cppcoro::net::socket_disconnect_operation_impl::try_start(
+	cppcoro::detail::win32_overlapped_operation_base& operation) noexcept
+{
+	// Lookup the address of the DisconnectEx function pointer for this socket.
+	LPFN_DISCONNECTEX disconnectExPtr;
+	{
+		GUID disconnectExGuid = WSAID_DISCONNECTEX;
+		DWORD byteCount = 0;
+		const int result = ::WSAIoctl(
+			m_socket.native_handle(),
+			SIO_GET_EXTENSION_FUNCTION_POINTER,
+			static_cast<void*>(&disconnectExGuid),
+			sizeof(disconnectExGuid),
+			static_cast<void*>(&disconnectExPtr),
+			sizeof(disconnectExPtr),
+			&byteCount,
+			nullptr,
+			nullptr);
+		if (result == SOCKET_ERROR)
+		{
+			operation.m_errorCode = static_cast<DWORD>(::WSAGetLastError());
+			return false;
+		}
+	}
+
+	// Need to read this flag before starting the operation, otherwise
+	// it may be possible that the operation will complete immediately
+	// on another thread and then destroy the socket before we get a
+	// chance to read it.
+	const bool skipCompletionOnSuccess = m_socket.skip_completion_on_success();
+
+	// Need to add TF_REUSE_SOCKET to these flags if we want to allow reusing
+	// a socket for subsequent connections once the disconnect operation
+	// completes.
+	const DWORD flags = 0;
+
+	const BOOL ok = disconnectExPtr(
+		m_socket.native_handle(),
+		operation.get_overlapped(),
+		flags,
+		0);
+	if (!ok)
+	{
+		const int errorCode = ::WSAGetLastError();
+		if (errorCode != ERROR_IO_PENDING)
+		{
+			// Failed synchronously.
+			operation.m_errorCode = static_cast<DWORD>(errorCode);
+			return false;
+		}
+	}
+	else if (skipCompletionOnSuccess)
+	{
+		// Successfully completed synchronously and no completion event
+		// will be posted to an I/O thread so we can return without suspending.
+		operation.m_errorCode = ERROR_SUCCESS;
+		return false;
+	}
+
+	return true;
+}
+
+void cppcoro::net::socket_disconnect_operation_impl::cancel(
+	cppcoro::detail::win32_overlapped_operation_base& operation) noexcept
+{
+	(void)::CancelIoEx(
+		reinterpret_cast<HANDLE>(m_socket.native_handle()),
+		operation.get_overlapped());
+}
+
+void cppcoro::net::socket_disconnect_operation_impl::get_result(
+	cppcoro::detail::win32_overlapped_operation_base& operation)
+{
+	if (operation.m_errorCode != ERROR_SUCCESS)
+	{
+		if (operation.m_errorCode == ERROR_OPERATION_ABORTED)
+		{
+			throw operation_cancelled{};
+		}
+
+		throw std::system_error{
+			static_cast<int>(operation.m_errorCode),
+			std::system_category(),
+			"Disconnect operation failed: DisconnectEx"
+		};
+	}
+}
+
+#endif