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https://github.com/slackhq/nebula.git
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JackDoan
76 lines
2.1 KiB
Go
76 lines
2.1 KiB
Go
//go:build linux && !android
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// +build linux,!android
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package virtio
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import (
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"encoding/binary"
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"golang.org/x/sys/unix"
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)
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// Size is the on-wire length of struct virtio_net_hdr the kernel
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// prepends/expects on a TUN opened with IFF_VNET_HDR (TUNSETVNETHDRSZ
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// not set).
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const Size = 10
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// Hdr is the Go view of the legacy virtio_net_hdr.
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type Hdr struct {
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Flags uint8
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gsoType uint8 //private to avoid mistakes wrt the 0x80 VIRTIO_NET_HDR_GSO_ECN flag, ORed with the other "GSO types"
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HdrLen uint16
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GSOSize uint16
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CsumStart uint16
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CsumOffset uint16
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}
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func NewHeader(flags, gsoType uint8, hdrLen, gsoSize, csumStart, csumOffset uint16) Hdr {
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return Hdr{
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Flags: flags,
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gsoType: gsoType,
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HdrLen: hdrLen,
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GSOSize: gsoSize,
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CsumStart: csumStart,
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CsumOffset: csumOffset,
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}
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}
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// Decode reads a virtio_net_hdr in host byte order (TUN default; we never
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// call TUNSETVNETLE so the kernel matches our endianness).
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func (h *Hdr) Decode(b []byte) {
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h.Flags = b[0]
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h.gsoType = b[1]
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h.HdrLen = binary.NativeEndian.Uint16(b[2:4])
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h.GSOSize = binary.NativeEndian.Uint16(b[4:6])
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h.CsumStart = binary.NativeEndian.Uint16(b[6:8])
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h.CsumOffset = binary.NativeEndian.Uint16(b[8:10])
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}
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func EncodeHeader(b []byte, flags, gsoType uint8, hdrLen, gsoSize, csumStart, csumOffset uint16) {
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b[0] = flags
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b[1] = gsoType
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binary.NativeEndian.PutUint16(b[2:4], hdrLen)
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binary.NativeEndian.PutUint16(b[4:6], gsoSize)
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binary.NativeEndian.PutUint16(b[6:8], csumStart)
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binary.NativeEndian.PutUint16(b[8:10], csumOffset)
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}
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// Encode is the inverse of Decode: writes the virtio_net_hdr fields into b
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// (must be at least Size bytes). Used to emit a TSO superpacket on egress.
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func (h *Hdr) Encode(b []byte) {
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EncodeHeader(b, h.Flags, h.gsoType, h.HdrLen, h.GSOSize, h.CsumStart, h.CsumOffset)
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}
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// GSOType returns gsoType with the ECN-flag masked out
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func (h *Hdr) GSOType() uint8 {
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return h.gsoType &^ unix.VIRTIO_NET_HDR_GSO_ECN
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}
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func (h *Hdr) HasECNFlag() bool {
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return h.gsoType&unix.VIRTIO_NET_HDR_GSO_ECN != 0
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}
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func (h *Hdr) SetGSOType(x uint8) {
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h.gsoType = x
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}
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