FwpsQueryPacketInjectionState0 function

The FwpsQueryPacketInjectionState0 function is called by a callout to query the injection state of packet data.

Note  FwpsQueryPacketInjectionState0 is a specific version of FwpsQueryPacketInjectionState. See WFP Version-Independent Names and Targeting Specific Versions of Windows for more information.


FWPS_PACKET_INJECTION_STATE FwpsQueryPacketInjectionState0(
  HANDLE                injectionHandle,
  const NET_BUFFER_LIST *netBufferList,
  HANDLE                *injectionContext



An injection handle that was previously created by a call to the FwpsInjectionHandleCreate0 function.


A pointer to a NET_BUFFER_LIST structure that describes the packet data that is being classified. The packet can originate from the network stack, or it can be injected into the network stack by a WFP callout driver.


An optional handle to the injection context. If the pointer is specified, and if the packet injection state FWPS_PACKET_INJECTION_STATE associated with the injection handle is FWPS_PACKET_INJECTED_BY_SELF or FWPS_PACKET_PREVIOUSLY_INJECTED_BY_SELF, the injection context supplied when the packet was injected will be returned.

Return Value

The FwpsQueryPacketInjectionState0 function returns one of the constant values of the FWPS_PACKET_INJECTION_STATE enumeration.


Because injected packet data can be reclassified against the callout that injected it, this function allows a callout to inspect the injection history of packet data when necessary, thereby avoiding the need to make repeated inspections of packet data that has already been inspected.

A callout can track other callout-specific information by specifying the optional injectionContext handle in one of the packet injection functions at the time of packet data injection. If the FwpsQueryPacketInjectionState0 function returns FWPS_PACKET_INJECTED_BY_SELF or FWPS_PACKET_PREVIOUSLY_INJECTED_BY_SELF, the supplied injectionContext will be returned as the completionContext parameter of the function that performed the injection.

If the return value is FWPS_PACKET_INJECTED_BY_SELF or FWPS_PACKET_PREVIOUSLY_INJECTED_BY_SELF, the network buffer list pointed to by netBufferList should not be further modified or pended as part of a cloning and injection procedure. In this case, the callout should set the actionType member of the FWPS_CLASSIFY_OUT0 structure pointed to by the classifyOut parameter of the classifyFn function to one of the following values.


Minimum supported client Available starting with Windows Vista.
Target Platform Universal
Header fwpsk.h (include Fwpsk.h)
Library Fwpkclnt.lib

See Also