NDIS_UDP_SEGMENTATION_OFFLOAD_NET_BUFFER_LIST_INFO structure (ndis/nbluso.h)

The NDIS_UDP_SEGMENTATION_OFFLOAD_NET_BUFFER_LIST_INFO structure specifies information that is used in offloading UDP Segmentation Offload (USO) tasks from the TCP/IP transport to a miniport adapter. The NDIS_UDP_SEGMENTATION_OFFLOAD_NET_BUFFER_LIST_INFO structure is part of the NET_BUFFER_LIST OOB information.

Syntax

typedef struct _NDIS_UDP_SEGMENTATION_OFFLOAD_NET_BUFFER_LIST_INFO {
  union {
    struct {
      ULONG MSS : 20;
      ULONG UdpHeaderOffset : 10;
      ULONG Reserved : 1;
      ULONG IPVersion : 1;
    } Transmit;
    PVOID Value;
  };
} NDIS_UDP_SEGMENTATION_OFFLOAD_NET_BUFFER_LIST_INFO, *PNDIS_UDP_SEGMENTATION_OFFLOAD_NET_BUFFER_LIST_INFO;

Members

Transmit

A structure that contains individual bit fields for USO information.

Transmit.MSS

The maximum segment size (MSS), in bytes, for each UDP segment. The TCP/IP transport writes this value before passing a large UDP packet to a miniport driver for segmentation.

Transmit.UdpHeaderOffset

The offset, in bytes, of the UDP header from the beginning of the packet for UDP packets. Miniport drivers can use UdpHeaderOffset to determine the location of the UDP header so that they do not have to parse IP headers.

Transmit.Reserved

Reserved. Miniport drivers must not read or write to this value.

Transmit.IPVersion

The IP version of the packet. For IPv4 packets, IPVersion is set to NDIS_UDP_SEGMENTATION_OFFLOAD_IPV4. For IPv6 packets, IPVersion is set to NDIS_UDP_SEGMENTATION_OFFLOAD_IPV6.

Value

A PVOID version of the USO information. Miniport drivers can use this member to access the raw information instead of the specific fields.

Remarks

The NDIS_UDP_SEGMENTATION_OFFLOAD_NET_BUFFER_LIST_INFO structure is part of the information that is included in a NET_BUFFER_LIST structure.

To set and get USO information, use the UdpSegmentationOffloadInfo index with the NET_BUFFER_LIST_INFO macro. NET_BUFFER_LIST_INFO returns a ULONG value (not a pointer to a ULONG value).

The TCP/IP transport updates the MSS and UdpHeaderOffset members of the NDIS_UDP_SEGMENTATION_OFFLOAD_NET_BUFFER_LIST_INFO structure before sending a large packet to a miniport driver.

Note

Any NET_BUFFER_LIST structure that contains USO information also contains a single NET_BUFFER structure.

Requirements

   
Minimum supported client Windows 10, version 1912
Header ndis/nbluso.h (include ndis.h)

See also

UDP Segmentation Offload (USO)

NET_BUFFER_LIST