NDIS_TCP_IP_CHECKSUM_NET_BUFFER_LIST_INFO structure (ndis/nblchecksum.h)
The NDIS_TCP_IP_CHECKSUM_NET_BUFFER_LIST_INFO structure specifies information used in offloading checksum tasks from the TCP/IP transport to a NIC. The NDIS_TCP_IP_CHECKSUM_NET_BUFFER_LIST_INFO structure is part of the NET_BUFFER_LIST information (out-of-band data) that is associated with a NET_BUFFER_LIST structure.
Syntax
typedef struct _NDIS_TCP_IP_CHECKSUM_NET_BUFFER_LIST_INFO {
union {
struct {
ULONG IsIPv4 : 1;
ULONG IsIPv6 : 1;
ULONG TcpChecksum : 1;
ULONG UdpChecksum : 1;
ULONG IpHeaderChecksum : 1;
ULONG Reserved : 11;
ULONG TcpHeaderOffset : 10;
} Transmit;
struct {
ULONG TcpChecksumFailed : 1;
ULONG UdpChecksumFailed : 1;
ULONG IpChecksumFailed : 1;
ULONG TcpChecksumSucceeded : 1;
ULONG UdpChecksumSucceeded : 1;
ULONG IpChecksumSucceeded : 1;
ULONG Loopback : 1;
ULONG TcpChecksumValueInvalid : 1;
ULONG IpChecksumValueInvalid : 1;
} Receive;
PVOID Value;
};
} NDIS_TCP_IP_CHECKSUM_NET_BUFFER_LIST_INFO, *PNDIS_TCP_IP_CHECKSUM_NET_BUFFER_LIST_INFO;
Members
Transmit
A structure that contains the following members:
Transmit.IsIPv4
Set by the TCP/IP transport to indicate that the send packet contains IPv4 addresses.
Transmit.IsIPv6
Set by the TCP/IP transport to indicate that the send packet contains IPv6 addresses.
Transmit.TcpChecksum
Set by the TCP/IP transport to indicate that the NIC should calculate the packet's TCP checksum.
Transmit.UdpChecksum
Set by the TCP/IP transport to indicate that the NIC should calculate the packet's UDP checksum.
Transmit.IpHeaderChecksum
Set by the TCP/IP transport to indicate that the NIC should calculate the IP checksum for the first IP header in the packet. If the packet contains both a tunnel IP header and a transport IP header, the NIC should calculate the checksum for both IP headers.
Transmit.Reserved
Reserved for NDIS.
Transmit.TcpHeaderOffset
The offset, in bytes, of the TCP header from the beginning of the packet for TCP packets. Miniport drivers can use TcpHeaderOffset to determine the location of the TCP header so that they do not need to parse the MAC and IP header.
Receive
A structure that contains the following members:
Receive.TcpChecksumFailed
Set by the miniport driver to indicate that the TCP checksum calculated by the NIC did not match the checksum in the receive packet's TCP header.
Receive.UdpChecksumFailed
Set by the miniport driver to indicate that the UDP checksum calculated by the NIC did not match the checksum in the receive packet's UDP header.
Receive.IpChecksumFailed
Set by the miniport driver to indicate that the IP checksum calculated by the NIC did not match the checksum in the receive packet's first IP header. If the receive packet contains both a tunnel IP header and a transport IP header, the NIC validates the checksum for both IP headers.
Receive.TcpChecksumSucceeded
Set by the miniport driver to indicate that the TCP checksum calculated by the NIC matched the checksum in the receive packet's TCP header.
Receive.UdpChecksumSucceeded
Set by the miniport driver to indicate that the UDP checksum calculated by the NIC matched the checksum in the receive packet's UDP header.
Receive.IpChecksumSucceeded
Set by the miniport driver to indicate that the IP checksum calculated by the NIC matched the checksum in the receive packet's first IP header. If the receive packet contains both a tunnel IP header and a transport IP header, the NIC validates the checksum for the both IP headers.
Receive.Loopback
NDIS uses this bit. The miniport driver must not examine or set this bit; the miniport driver should just ignore this bit.
Receive.TcpChecksumValueInvalid
A miniport driver that supports Receive Segment Coalescing (RSC) sets this flag to indicate that the TCP header checksum was validated by the NIC but the TCP header checksum value in the packet is not valid. For more information, see Indicating Coalesced Segments.
Miniport drivers that do not support RSC should set this flag to zero.
Receive.IpChecksumValueInvalid
A miniport driver that supports RSC sets this flag to indicate that for an IPv4 packet, the IP header checksum was validated by the NIC but the IP header checksum value in the packet is not valid. For a packet consisting of both a tunnel and a transport IP header, this bit is applicable only to the tunnel IP header. For more information, see Indicating Coalesced Segments.
Miniport drivers that do not support RSC should set this flag to zero.
Value
A PVOID version of the checksum information. Miniport drivers can use this member to access the raw information instead of the specific fields.
Remarks
The NDIS_TCP_IP_CHECKSUM_NET_BUFFER_LIST_INFO structure specifies information that is used in offloading checksum tasks from the TCP/IP transport to a NIC. The NDIS_TCP_IP_CHECKSUM_NET_BUFFER_LIST_INFO structure is part of the NET_BUFFER_LIST information (out-of-band data) that is associated with a NET_BUFFER_LIST structure.
Before the TCP/IP transport passes to the miniport driver a TCP/IP packet on which the miniport driver will perform checksum tasks, the TCP/IP transport updates the NDIS_TCP_IP_CHECKSUM_NET_BUFFER_LIST_INFO structure that is associated with the NET_BUFFER_LIST structure. Specifically, the TCP/IP transport sets the IsIPv4 or IsIPv6 flag to indicate that the send packet is an IPv4 or IPv6 packet.
yyIf the TCP/IP transport does not set either the IsIPv4 or IsIPv6 flag, the miniport driver should not perform checksum tasks on the packet. If the TCP/IP transport sets the IsIPv4 or IsIPv6 flag, it also sets the appropriate flags that are required to indicate which checksums the miniport driver should calculate for the packet. For IPv4, this includes the IpHeaderChecksum, TcpChecksum, or UdpChecksum flags. For IPv6, this includes the TcpChecksum or UdpChecksum flags. In addition, for TCP packets, the TCP/IP transport sets the TcpHeaderOffset field when either the IsIPv4 or IPv6 flag is set. The transport does not set this field for UDP packets.
Before indicating up a receive TCP/IP packet on which it performs checksum tasks, a miniport driver sets the appropriate XxxChecksumFailed or XxxChecksumSucceeded flags in the NDIS_TCP_IP_CHECKSUM_NET_BUFFER_LIST_INFO structure.
Requirements
Requirement | Value |
---|---|
Minimum supported client | Supported in NDIS 6.0 and later. |
Header | ndis/nblchecksum.h (include ndis.h) |
See also
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