How to "CreateChild()".UEFI - c

Question

I wonder, how can I access TCP4Protocol to use in my DXE driver.
I already asked similar question: myFirstQestion
Now I can't find the solution to solve the error.
Because I get my debug string "Can't create child" when trying to load the driver. Picking my code below.
Or maybe somebody knows how to complete my task from the link through dxe driver.
Thank you.
#include "Uefi.h"
#include <Protocol/Tcp4.h>
#include <Library/UefiDriverEntryPoint.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Protocol/ServiceBinding.h>
#include <Protocol/SimpleNetwork.h>
#include <Library/DebugLib.h>
EFI_STATUS
EFIAPI
Net1DriverDxeEntry(IN EFI_HANDLE ImageHandle, IN EFI_SYSTEM_TABLE *SystemTable)
{
EFI_TCP4_PROTOCOL *TCP4protocol = NULL;
EFI_SERVICE_BINDING_PROTOCOL *TCP4ServiceBinding = NULL;
EFI_SIMPLE_NETWORK_PROTOCOL *SimpleNetworkProtocol = NULL;
EFI_HANDLE *HandleBuffer = NULL;
EFI_HANDLE *TCP4Handle = NULL;
UINTN HandleCount;
UINTN i;
CHAR16 *Deb1 = L"Simple network protocol not found\r\n";
CHAR16 *Deb2 = L"TCP4 protocol not found\r\n";
CHAR16 *Deb3 = L"Can't create child\r\n";
CHAR16 *Deb4 = L"Can't handle protocol\n\r\n";
EFI_STATUS Status = gBS->LocateProtocol(&gEfiSimpleNetworkProtocolGuid,NULL, (VOID**) &SimpleNetworkProtocol);
if (EFI_ERROR (Status))
{
DEBUG((-1, "ShowStatus: Simple network protocol not found\n"));
gST->ConOut->OutputString(gST->ConOut, Deb1);
return EFI_UNSUPPORTED;
}
Status = gBS->LocateHandleBuffer(ByProtocol,&gEfiTcp4ProtocolGuid, NULL, &HandleCount,&HandleBuffer);
if (EFI_ERROR (Status))
{
gST->ConOut->OutputString(gST->ConOut, Deb2);
DEBUG((-2, "ShowStatus: TCP4 protocol not found\n"));
return EFI_UNSUPPORTED;
}
for (i = 0; i < HandleCount; i ++)
{
Status = gBS->HandleProtocol(HandleBuffer[i], &gEfiTcp4ServiceBindingProtocolGuid,(VOID **) &TCP4ServiceBinding);
if(EFI_ERROR (Status))
{
DEBUG((-3, "\n"));
gST->ConOut->OutputString(gST->ConOut, Deb3);
return EFI_UNSUPPORTED;
}
TCP4ServiceBinding->CreateChild(TCP4ServiceBinding, TCP4Handle);
Status = gBS->HandleProtocol(TCP4Handle,&gEfiTcp4ProtocolGuid,(VOID **) &TCP4protocol);
if(EFI_ERROR (Status))
{
gST->ConOut->OutputString(gST->ConOut, Deb4);
DEBUG((-4, "ShowStatus: Can't handle protocol\n"));
return EFI_UNSUPPORTED;
}
}
return EFI_SUCCESS;
}

Answer 1

TCP4Handle should be of type EFI_HANDLE not EFI_HANDLE*.
EFI_HANDLE TCP4Handle = NULL;
//....
TCP4ServiceBinding->CreateChild(TCP4ServiceBinding, &TCP4Handle);
And you must look for gEfiTcp4ServiceBindingProtocolGuid not gEfiTcp4ProtocolGuid.
Status = gBS->LocateHandleBuffer(ByProtocol,&gEfiTcp4ServiceBindingProtocolGuid, NULL, &HandleCount,&HandleBuffer);