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vx46
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reduce allocations of OOB data

This commit is contained in:
Johannes Kimmel 2023-08-27 00:10:59 +02:00
parent cd9725276c
commit e61557048b
1 changed files with 40 additions and 25 deletions
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65
main.go
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@ -31,27 +31,36 @@ func (vx *vx46) transform46(msgs4 []ipv4.Message, msgs6 []ipv6.Message) error {
// embed the "client" ipv4 into the src address for the packet to the upstream vxlan ipv6 endpoint
// the destination is the upstream vxlan endpoint
for i := range msgs4 {
cm4 := ipv4.ControlMessage{}
if err := cm4.Parse(msgs4[i].OOB[:msgs4[i].NN]); err != nil {
return err
if len(msgs6[i].OOB) < OOB_SIZE {
msgs6[i].OOB = make([]byte, OOB_SIZE)
msgs6[i].NN = OOB_SIZE
}
var hdr syscall.Cmsghdr
hdr.SetLen(syscall.CmsgLen(syscall.SizeofInet6Pktinfo))
hdr.Level = syscall.IPPROTO_IPV6
hdr.Type = syscall.IPV6_PKTINFO
oobdata := msgs6[i].OOB[:0]
// set cmsg header
oobdata = binary.NativeEndian.AppendUint64(oobdata, hdr.Len)
oobdata = binary.NativeEndian.AppendUint32(oobdata, uint32(hdr.Level))
oobdata = binary.NativeEndian.AppendUint32(oobdata, uint32(hdr.Type))
// set the address
// prefix + embeded v4 + port
oobdata = append(oobdata, vx.natprefix[:10]...)
inUDPAddr4 := msgs4[i].Addr.(*net.UDPAddr)
egressSrcAddr := vx.natprefix.As16()
copy(egressSrcAddr[10:14], inUDPAddr4.IP.To4()[:4]) // panics if To4 returns nil
binary.BigEndian.PutUint16(egressSrcAddr[14:16], uint16(inUDPAddr4.Port))
oobdata = append(oobdata, inUDPAddr4.IP.To4()[:4]...)
oobdata = binary.BigEndian.AppendUint16(oobdata, uint16(inUDPAddr4.Port))
if vx.oobkey != egressSrcAddr {
vx.oobkey = egressSrcAddr
cm6 := ipv6.ControlMessage{Src: net.IP(egressSrcAddr[:])}
vx.oobcache = cm6.Marshal()
}
// let the kernel decide which interface to use
oobdata = binary.NativeEndian.AppendUint32(oobdata, 0) // iface
msgs6[i].Buffers[0] = msgs4[i].Buffers[0][:msgs4[i].N]
msgs6[i].OOB = vx.oobcache
msgs6[i].Addr = vx.upstream
msgs6[i].N = msgs4[i].N
msgs6[i].NN = len(msgs6[i].OOB)
}
return nil
@ -93,21 +102,30 @@ func (vx *vx46) transform64(msgs6 []ipv6.Message, msgs4 []ipv4.Message) error {
// embed the "client" ipv4 into the src address for the packet to the upstream vxlan ipv6 endpoint
// the destination is the upstream vxlan endpoint
for i := range msgs6 {
cm6 := ipv6.ControlMessage{}
if err := cm6.Parse(msgs6[i].OOB[:msgs6[i].NN]); err != nil {
return err
var hdr syscall.Cmsghdr
hdr.Len = binary.NativeEndian.Uint64(msgs6[i].OOB[0:])
hdr.Level = int32(binary.NativeEndian.Uint32(msgs6[i].OOB[8:]))
hdr.Type = int32(binary.NativeEndian.Uint32(msgs6[i].OOB[12:]))
if hdr.Len != uint64(syscall.CmsgLen(syscall.SizeofInet6Pktinfo)) {
log.Fatal("OOB: unexpected Len: ", hdr.Len, syscall.CmsgLen(syscall.SizeofInet6Pktinfo))
}
if cm6.Dst.To16() == nil {
return fmt.Errorf("Destination information not available")
if hdr.Level != syscall.IPPROTO_IPV6 {
log.Fatal("OOB: unexpected Level", hdr.Level)
}
if hdr.Type != syscall.IPV6_PKTINFO {
log.Fatal("OOB: unexpected Type", hdr.Type)
}
dstaddr6 := msgs6[i].OOB[16:32]
msgs4[i].Buffers[0] = msgs6[i].Buffers[0][:msgs6[i].N]
if msgs4[i].Addr == nil {
msgs4[i].Addr = &net.UDPAddr{}
}
addr := msgs4[i].Addr.(*net.UDPAddr)
addr.IP = cm6.Dst[10:14]
addr.Port = int(binary.BigEndian.Uint16(cm6.Dst[14:16]))
addr.IP = dstaddr6[10:14]
addr.Port = int(binary.BigEndian.Uint16(dstaddr6[14:16]))
msgs4[i].N = msgs6[i].N
msgs4[i].OOB = nil
msgs4[i].NN = 0
@ -190,15 +208,12 @@ func (vx *vx46) forward() error {
type vx46 struct {
pc4 *ipv4.PacketConn
pc6 *ipv6.PacketConn
natprefix netip.Addr
natprefix [16]byte
upstreamAddr netip.Addr
upstream *net.UDPAddr
port uint16
mtu uint16
buffers int
oobkey [16]byte
oobcache []byte
}
func vx46forward(natprefix netip.Addr, upstreamAddr netip.Addr, port uint16, mtu uint16) error {
@ -309,7 +324,7 @@ func main() {
log.Println(vx46forward(natprefix, upstreamAddr, port, mtu))
} else {
vx := vx46{
natprefix: natprefix,
natprefix: natprefix.As16(),
upstream: &net.UDPAddr{
IP: net.IP(upstreamAddr.AsSlice()),
Port: *portInt,