vhost

packet/outpacket.go

@@ -0,0 +1,70 @@
+package packet
+
+import (
+	"github.com/slackhq/nebula/util/virtio"
+	"golang.org/x/sys/unix"
+)
+
+type OutPacket struct {
+	Segments        [][]byte
+	SegmentPayloads [][]byte
+	SegmentHeaders  [][]byte
+	SegmentIDs      []uint16
+	//todo virtio header?
+	SegSize      int
+	SegCounter   int
+	Valid        bool
+	wasSegmented bool
+
+	Scratch []byte
+}
+
+func NewOut() *OutPacket {
+	out := new(OutPacket)
+	out.Segments = make([][]byte, 0, 64)
+	out.SegmentHeaders = make([][]byte, 0, 64)
+	out.SegmentPayloads = make([][]byte, 0, 64)
+	out.SegmentIDs = make([]uint16, 0, 64)
+	out.Scratch = make([]byte, Size)
+	return out
+}
+
+func (pkt *OutPacket) Reset() {
+	pkt.Segments = pkt.Segments[:0]
+	pkt.SegmentPayloads = pkt.SegmentPayloads[:0]
+	pkt.SegmentHeaders = pkt.SegmentHeaders[:0]
+	pkt.SegmentIDs = pkt.SegmentIDs[:0]
+	pkt.SegSize = 0
+	pkt.Valid = false
+	pkt.wasSegmented = false
+}
+
+func (pkt *OutPacket) UseSegment(segID uint16, seg []byte, isV6 bool) int {
+	pkt.Valid = true
+	pkt.SegmentIDs = append(pkt.SegmentIDs, segID)
+	pkt.Segments = append(pkt.Segments, seg) //todo do we need this?
+
+	vhdr := virtio.NetHdr{ //todo
+		Flags:      unix.VIRTIO_NET_HDR_F_DATA_VALID,
+		GSOType:    unix.VIRTIO_NET_HDR_GSO_NONE,
+		HdrLen:     0,
+		GSOSize:    0,
+		CsumStart:  0,
+		CsumOffset: 0,
+		NumBuffers: 0,
+	}
+
+	hdr := seg[0 : virtio.NetHdrSize+14]
+	_ = vhdr.Encode(hdr)
+	if isV6 {
+		hdr[virtio.NetHdrSize+14-2] = 0x86
+		hdr[virtio.NetHdrSize+14-1] = 0xdd
+	} else {
+		hdr[virtio.NetHdrSize+14-2] = 0x08
+		hdr[virtio.NetHdrSize+14-1] = 0x00
+	}
+
+	pkt.SegmentHeaders = append(pkt.SegmentHeaders, hdr)
+	pkt.SegmentPayloads = append(pkt.SegmentPayloads, seg[virtio.NetHdrSize+14:])
+	return len(pkt.SegmentIDs) - 1
+}