#ifndef _NTLPCAPI_H

/**
 * The NtRequestWaitReplyPort routine sends a request and waits for a reply.
 *
 * \param PortHandle Handle to the port object.
 * \param RequestMessage Pointer to the message being sent.
 * \param ReplyMessage Receives the reply message.
 * \return NTSTATUS Successful or errant status.
 */
_Kernel_entry_
NTSYSCALLAPI
NTSTATUS
NTAPI
NtRequestWaitReplyPort(
    _In_ HANDLE PortHandle,
    _In_reads_bytes_(RequestMessage->u1.s1.TotalLength) PPORT_MESSAGE RequestMessage,
    _Out_ PPORT_MESSAGE ReplyMessage
    );

#endif
View code on GitHub

#ifndef _NTZWAPI_H

_Kernel_entry_
NTSYSCALLAPI
NTSTATUS
NTAPI
ZwRequestWaitReplyPort(
    _In_ HANDLE PortHandle,
    _In_reads_bytes_(RequestMessage->u1.s1.TotalLength) PPORT_MESSAGE RequestMessage,
    _Out_ PPORT_MESSAGE ReplyMessage
    );

#endif
View code on GitHub