func (h *Handle) XfrmPolicyDel(policy *XfrmPolicy) error {
	_, err := h.xfrmPolicyGetOrDelete(policy, nl.XFRM_MSG_DELPOLICY)
	return err
}
XfrmPolicyDel will delete an xfrm policy from the system. Note that
the Tmpls are ignored when matching the policy to delete.
Equivalent to: `ip xfrm policy del $policy`
package netlink
import (
	"github.com/vishvananda/netlink/nl"
	"golang.org/x/sys/unix"
)
func selFromPolicy(sel *nl.XfrmSelector, policy *XfrmPolicy) {
	sel.Family = uint16(nl.FAMILY_V4)
	if policy.Dst != nil {
		sel.Family = uint16(nl.GetIPFamily(policy.Dst.IP))
		sel.Daddr.FromIP(policy.Dst.IP)
		prefixlenD, _ := policy.Dst.Mask.Size()
		sel.PrefixlenD = uint8(prefixlenD)
	}
	if policy.Src != nil {
		sel.Saddr.FromIP(policy.Src.IP)
		prefixlenS, _ := policy.Src.Mask.Size()
		sel.PrefixlenS = uint8(prefixlenS)
	}
	sel.Proto = uint8(policy.Proto)
	sel.Dport = nl.Swap16(uint16(policy.DstPort))
	sel.Sport = nl.Swap16(uint16(policy.SrcPort))
	if sel.Dport != 0 {
		sel.DportMask = ^uint16(0)
	}
	if sel.Sport != 0 {
		sel.SportMask = ^uint16(0)
	}
	sel.Ifindex = int32(policy.Ifindex)
}
func XfrmPolicyAdd(policy *XfrmPolicy) error {
	return pkgHandle.XfrmPolicyAdd(policy)
}
func (h *Handle) XfrmPolicyAdd(policy *XfrmPolicy) error {
	return h.xfrmPolicyAddOrUpdate(policy, nl.XFRM_MSG_NEWPOLICY)
}
func XfrmPolicyUpdate(policy *XfrmPolicy) error {
	return pkgHandle.XfrmPolicyUpdate(policy)
}
func (h *Handle) XfrmPolicyUpdate(policy *XfrmPolicy) error {
	return h.xfrmPolicyAddOrUpdate(policy, nl.XFRM_MSG_UPDPOLICY)
}
func (h *Handle) xfrmPolicyAddOrUpdate(policy *XfrmPolicy, nlProto int) error {
	req := h.newNetlinkRequest(nlProto, unix.NLM_F_CREATE|unix.NLM_F_EXCL|unix.NLM_F_ACK)
	msg := &nl.XfrmUserpolicyInfo{}
	selFromPolicy(&msg.Sel, policy)
	msg.Priority = uint32(policy.Priority)
	msg.Index = uint32(policy.Index)
	msg.Dir = uint8(policy.Dir)
	msg.Action = uint8(policy.Action)
	msg.Lft.SoftByteLimit = nl.XFRM_INF
	msg.Lft.HardByteLimit = nl.XFRM_INF
	msg.Lft.SoftPacketLimit = nl.XFRM_INF
	msg.Lft.HardPacketLimit = nl.XFRM_INF
	req.AddData(msg)
	tmplData := make([]byte, nl.SizeofXfrmUserTmpl*len(policy.Tmpls))
	for i, tmpl := range policy.Tmpls {
		start := i * nl.SizeofXfrmUserTmpl
		userTmpl := nl.DeserializeXfrmUserTmpl(tmplData[start : start+nl.SizeofXfrmUserTmpl])
		userTmpl.XfrmId.Daddr.FromIP(tmpl.Dst)
		userTmpl.Saddr.FromIP(tmpl.Src)
		userTmpl.XfrmId.Proto = uint8(tmpl.Proto)
		userTmpl.XfrmId.Spi = nl.Swap32(uint32(tmpl.Spi))
		userTmpl.Mode = uint8(tmpl.Mode)
		userTmpl.Reqid = uint32(tmpl.Reqid)
		userTmpl.Aalgos = ^uint32(0)
		userTmpl.Ealgos = ^uint32(0)
		userTmpl.Calgos = ^uint32(0)
	}
	if len(tmplData) > 0 {
		tmpls := nl.NewRtAttr(nl.XFRMA_TMPL, tmplData)
		req.AddData(tmpls)
	}
	if policy.Mark != nil {
		out := nl.NewRtAttr(nl.XFRMA_MARK, writeMark(policy.Mark))
		req.AddData(out)
	}
	ifId := nl.NewRtAttr(nl.XFRMA_IF_ID, nl.Uint32Attr(uint32(policy.Ifid)))
	req.AddData(ifId)
	_, err := req.Execute(unix.NETLINK_XFRM, 0)
	return err
}
func XfrmPolicyDel(policy *XfrmPolicy) error {
	return pkgHandle.XfrmPolicyDel(policy)
}