When I try to call:

timeval timeout{ 0, 999 };
::GetAddrInfoExW(L"my_name", L"", NS_DNS, nullptr, nullptr, &pResult, &timeout, nullptr, nullptr, nullptr);

I got 10022 "Invalid params".

However, if I replace "&timeout" with "nullptr", I got 0 (OK).

Why the timeout causes EINVAL error?

UNICODE macro is defined, my system is Windows 10.

CodePudding user response：

if timeout not 0, the lpOverlapped must be also not 0. the code can be next

#include <ws2tcpip.h>

struct QUERY_CONTEXT : OVERLAPPED
{
    PADDRINFOEX _pResult;
    ULONG _dwThreadId = GetCurrentThreadId();

    ~QUERY_CONTEXT()
    {
        if (PADDRINFOEX pResult = _pResult)
        {
            FreeAddrInfoEx(_pResult);
        }
    }

    static void CALLBACK QueryCompleteCallback(   
        _In_ ULONG dwError,   
        _In_ ULONG /*dwBytes*/,   
        _In_ OVERLAPPED* lpOverlapped   
        )
    {
        static_cast<QUERY_CONTEXT*>(lpOverlapped)->OnComplete(dwError);
    }

    void OnComplete(_In_ ULONG dwError)
    {
        DbgPrint("OnComplete(%u)\n");

        if (PADDRINFOEX pResult = _pResult)
        {
            do 
            {
                WCHAR buf[64];
                ULONG len = _countof(buf);
                if (!WSAAddressToStringW(pResult->ai_addr, (ULONG)pResult->ai_addrlen, 0, buf, &len))
                {
                    DbgPrint("%S\n", buf);
                }
            } while (pResult = pResult->ai_next);
        }

        PostThreadMessageW(_dwThreadId, WM_QUIT, dwError, 0);

        delete this;
    }

    ULONG Query(_In_ PCWSTR pName, _In_opt_ timeval *timeout)
    {
        ULONG dwError = GetAddrInfoExW(pName, 0, NS_DNS, 0, 0, 
            &_pResult, timeout, this, QueryCompleteCallback, 0);

        //
        //  If GetAddrInfoExW() returns  WSA_IO_PENDING, GetAddrInfoExW will invoke
        //  the completion routine. If GetAddrInfoExW returned anything else we must
        //  invoke the completion directly.
        //

        if (dwError != WSA_IO_PENDING)
        {
            QueryCompleteCallback(dwError, 0, this);
        }

        return dwError;
    }
};

///////////////////////////////////////

    WSADATA wd;
    if (NOERROR == WSAStartup(WINSOCK_VERSION, &wd))
    {
        if (QUERY_CONTEXT* pqc = new QUERY_CONTEXT {})
        {
            timeval timeout{ 1 };
            pqc->Query(L"stackoverflow.com", &timeout);
        }
        MessageBoxW(0, 0, 0, 0);
        WSACleanup();
    }

also for dns query more efficient direct use DnsQueryEx function (GetAddrInfoExW internally call DnsQueryEx, but before this - alot of another code executed)