RttcpipfltTransmit

RttcpipfltTransmit is called every time the TCP/IP Stack is about to send an Ethernet frame over the network. The filter can elect to pass the frame down to the NIC by returning TRUE or drop the frame by returning FALSE.

Note: Since this routine is called for every frame to transmit, it should complete its work as fast as possible.

Syntax

Copy

BOOL RttcpipfltTransmit(
  [in]    RTTCPIPFLT_ETHERNET_HEADER *pEthernetHeader,
  [in]    VOID *pData,
  [in]    ULONG ulEthernetDataSize
);

Parameters

pEthernetHeader

Pointer to a data structure representing the 14-byte Ethernet header of the frame to be sent.

pData

Pointer to the first byte of Ethernet payload (just after the 14-byte Ethernet header) of the frame to be sent.

ulEthernetDataSize

Size of the Ethernet payload (this does NOT include the 14-byte Ethernet header).

Return Value

If the frame must be passed to the NIC, it returns TRUE. If the frame must be dropped, it returns FALSE.

Remarks

A filter driver must implement at least one of the following callbacks in each path:

RttcpipfltTransmit or RttcpipfltTransmitEx AND
RttcpipfltReceive or RttcpipfltReceiveEx

At Runtime, if the filter is enabled, the TCP/IP Stack will attempt first to call the -Ex function, if found. Otherwise, it will call the non -Ex function.

Requirements

Minimum supported version	Header	Library
eRTOS 1.0 SDK	Rttcpipflt.h	Rttcpip.lib