IO Completion Ports - error 998

Question

Explain, please, what am I doing wrong?
I am trying to make a simple client based on IOCP:

But, i always get the gatelasterror error 998 when calling GetQueuedCompletionStatus. I just can't understand - what I'm doing wrong. :(

Answer 1

Maybe specify a valid third argument:

ULONG_PTR ck = 999;
. . . GetQueuedCompletionStatus(iocp, &my_DWORD, &ck, &my_WSAOVERLAPPED_1, INFINITE);

Answer 2

int main()
{
//-------------------------------------------------------------------Create port IO-------------------------------------------------------------

int Number_Threads = 4;  

HANDLE My_handle_IOCP = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, NULL, Number_Threads);

//------------------------------------------------------------------------------------------------------------------------------------------------


//-------------------------------------------------------------------Create thread for IOCP-------------------------------------------------------

std::vector<HANDLE>my_vector_Thread;


for (int i = 0; i < Number_Threads; i++)
{
my_vector_Thread.push_back(CreateThread(0, 0, (LPTHREAD_START_ROUTINE)&My_func_for_Thread, My_handle_IOCP, 0, 0));
}


//---------------------------------------------------------------------------------------------------------------------------------------------------


//-------------------------------------------------------------------Initialization Winsock-----------------------------------------------------------

WORD my_version_Winsock = MAKEWORD(2, 2); 

WSADATA my_wsadata_struct; 

int my_WSAStartup = WSAStartup(my_version_Winsock, &my_wsadata_struct);

//------------------------------------------------------------------------------------------------------------------------------------------------------


//-------------------------------------------------------------------Create WSASocket-----------------------------------------------------------------

SOCKET my_WSASocketA = WSASocketA(AF_INET, SOCK_STREAM, IPPROTO_TCP, NULL, 0, WSA_FLAG_OVERLAPPED);

//--------------------------------------------------------------------------------------------------------------------------------------------------------


//-------------------------------------------------------------------

std::string myString_IP = "XX.XXX.XX.XXX";

//--------------------------------------------------------------------------

sockaddr my_sockaddr;                 

my_sockaddr = { 0 };                                            
my_sockaddr.sa_family = 2;                                          // AF_INET.
inet_pton(AF_INET, myString_IP.c_str(), &my_sockaddr.sa_data[2]);   
my_sockaddr.sa_data[1] = 80;                                     //http port

    //--------------------------------------------------------------------------


int status_WSAConnect = WSAConnect(my_WSASocketA, &my_sockaddr, sizeof(my_sockaddr), NULL, NULL, NULL, NULL);

//-----------------------------------------------------------------------------------------------------------------------------------------------------------------------



//-------------------------------------------------------------------Bind socket and port--------------------------------------------------------

My_handle_Create_IOCP = CreateIoCompletionPort((HANDLE)my_WSASocketA, My_handle_IOCP, NULL, 0);

//-------------------------------------------------------------------------------------------------------------------------------------------------



//-------------------------------------------------------------------Send message to serever with WSASend-----------------------------------

     WSABUF my_WSABUF;

 std::string request_text_string = "GET / HTTP/1.1\r\nHost: government.ru\r\nConnection: keep-alive\r\n\r\n";


 my_WSABUF.buf = &request_text_string[0];
 my_WSABUF.len = request_text_string.size();


 WSAOVERLAPPED my_WSAOVERLAPPED;
 my_WSAOVERLAPPED = { 0 };



     int my_WSASend =  WSASend(my_WSASocketA, &my_WSABUF, 1, NULL, 0, &my_WSAOVERLAPPED, NULL);


                 if (my_WSASend == SOCKET_ERROR)
 {
                   std::cout << "WSASend == SOCKET_ERROR:" std::endl;
                 }

                  if (my_WSASend == 0)
 {
                   std::cout << "WSASend == 0: no error" std::endl;
                 }

//-----------------------------------------------------------------------------------------------------------------------------------------------------------

}

Answer 3

void My_func_for_Thread(HANDLE iocp)
{

    DWORD my_DWORD=666;
    PULONG_PTR   my_CompletionKey = 0;

    WSAOVERLAPPED* my_WSAOVERLAPPED_1;


    int my_GetLastError;

    while (1)
    {


        BOOL my_BOOL_GetQueuedCompletionStatus = GetQueuedCompletionStatus(iocp, &my_DWORD, my_CompletionKey, &my_WSAOVERLAPPED_1, INFINITE);


        my_GetLastError = GetLastError();


            if (my_BOOL_GetQueuedCompletionStatus == FALSE)
            {
                std::cout << "GetQueuedCompletionStatus== FALSE" << std::endl;
            }

      }
}

Answer 4

It sounds like you're running into a tricky issue with your IOCP-based client. The error code 998 indicates an "Invalid Access to Memory Location," which could be caused by several things. Here are a few steps to help diagnose and fix the problem:

1. Verify Parameters: Ensure all parameters passed to GetQueuedCompletionStatus are correct, especially the OVERLAPPED structure and any pointers.
2. Initialize OVERLAPPED Structure: Make sure the OVERLAPPED structure is properly initialized before use. Uninitialized structures can cause memory access errors.
3. Check Buffer Validity: Ensure the buffers associated with your I/O operations are valid and remain in scope until the I/O operation completes.
4. Synchronize Access: If multiple threads are accessing shared resources, ensure proper synchronization to avoid race conditions and memory access violations.
5. Error Handling: Add detailed error handling and logging around your I/O operations to capture and analyze any errors leading up to the 998 error.
6. Review Documentation: Double-check the MSDN documentation for GetQueuedCompletionStatus to ensure all requirements and best practices are followed.

If you can share a code snippet, it might help pinpoint the issue more accurately. Don't get discouraged; IOCP can be complex, but you're on the right track by seeking help.