mirror of
https://github.com/slackhq/nebula.git
synced 2025-11-22 16:34:25 +01:00
78 lines
2.6 KiB
Go
78 lines
2.6 KiB
Go
package virtio
|
|
|
|
import (
|
|
"errors"
|
|
"unsafe"
|
|
|
|
"golang.org/x/sys/unix"
|
|
)
|
|
|
|
// Workaround to make Go doc links work.
|
|
var _ unix.Errno
|
|
|
|
// NetHdrSize is the number of bytes needed to store a [NetHdr] in memory.
|
|
const NetHdrSize = 12
|
|
|
|
// ErrNetHdrBufferTooSmall is returned when a buffer is too small to fit a
|
|
// virtio_net_hdr.
|
|
var ErrNetHdrBufferTooSmall = errors.New("the buffer is too small to fit a virtio_net_hdr")
|
|
|
|
// NetHdr defines the virtio_net_hdr as described by the virtio specification.
|
|
type NetHdr struct {
|
|
// Flags that describe the packet.
|
|
// Possible values are:
|
|
// - [unix.VIRTIO_NET_HDR_F_NEEDS_CSUM]
|
|
// - [unix.VIRTIO_NET_HDR_F_DATA_VALID]
|
|
// - [unix.VIRTIO_NET_HDR_F_RSC_INFO]
|
|
Flags uint8
|
|
// GSOType contains the type of segmentation offload that should be used for
|
|
// the packet.
|
|
// Possible values are:
|
|
// - [unix.VIRTIO_NET_HDR_GSO_NONE]
|
|
// - [unix.VIRTIO_NET_HDR_GSO_TCPV4]
|
|
// - [unix.VIRTIO_NET_HDR_GSO_UDP]
|
|
// - [unix.VIRTIO_NET_HDR_GSO_TCPV6]
|
|
// - [unix.VIRTIO_NET_HDR_GSO_UDP_L4]
|
|
// - [unix.VIRTIO_NET_HDR_GSO_ECN]
|
|
GSOType uint8
|
|
// HdrLen contains the length of the headers that need to be replicated by
|
|
// segmentation offloads. It's the number of bytes from the beginning of the
|
|
// packet to the beginning of the transport payload.
|
|
// Only used when [FeatureNetDriverHdrLen] is negotiated.
|
|
HdrLen uint16
|
|
// GSOSize contains the maximum size of each segmented packet beyond the
|
|
// header (payload size). In case of TCP, this is the MSS.
|
|
GSOSize uint16
|
|
// CsumStart contains the offset within the packet from which on the
|
|
// checksum should be computed.
|
|
CsumStart uint16
|
|
// CsumOffset specifies how many bytes after [NetHdr.CsumStart] the computed
|
|
// 16-bit checksum should be inserted.
|
|
CsumOffset uint16
|
|
// NumBuffers contains the number of merged descriptor chains when
|
|
// [FeatureNetMergeRXBuffers] is negotiated.
|
|
// This field is only used for packets received by the driver and should be
|
|
// zero for transmitted packets.
|
|
NumBuffers uint16
|
|
}
|
|
|
|
// Decode decodes the [NetHdr] from the given byte slice. The slice must contain
|
|
// at least [NetHdrSize] bytes.
|
|
func (v *NetHdr) Decode(data []byte) error {
|
|
if len(data) < NetHdrSize {
|
|
return ErrNetHdrBufferTooSmall
|
|
}
|
|
copy(unsafe.Slice((*byte)(unsafe.Pointer(v)), NetHdrSize), data[:NetHdrSize])
|
|
return nil
|
|
}
|
|
|
|
// Encode encodes the [NetHdr] into the given byte slice. The slice must have
|
|
// room for at least [NetHdrSize] bytes.
|
|
func (v *NetHdr) Encode(data []byte) error {
|
|
if len(data) < NetHdrSize {
|
|
return ErrNetHdrBufferTooSmall
|
|
}
|
|
copy(data[:NetHdrSize], unsafe.Slice((*byte)(unsafe.Pointer(v)), NetHdrSize))
|
|
return nil
|
|
}
|