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filter_linux.go
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filter_linux.go
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package netlink
import (
"fmt"
"syscall"
"github.com/vishvananda/netlink/nl"
)
// FilterDel will delete a filter from the system.
// Equivalent to: `tc filter del $filter`
func FilterDel(filter Filter) error {
req := nl.NewNetlinkRequest(syscall.RTM_DELTFILTER, syscall.NLM_F_ACK)
base := filter.Attrs()
msg := &nl.TcMsg{
Family: nl.FAMILY_ALL,
Ifindex: int32(base.LinkIndex),
Handle: base.Handle,
Parent: base.Parent,
Info: MakeHandle(base.Priority, nl.Swap16(base.Protocol)),
}
req.AddData(msg)
_, err := req.Execute(syscall.NETLINK_ROUTE, 0)
return err
}
// FilterAdd will add a filter to the system.
// Equivalent to: `tc filter add $filter`
func FilterAdd(filter Filter) error {
req := nl.NewNetlinkRequest(syscall.RTM_NEWTFILTER, syscall.NLM_F_CREATE|syscall.NLM_F_EXCL|syscall.NLM_F_ACK)
base := filter.Attrs()
msg := &nl.TcMsg{
Family: nl.FAMILY_ALL,
Ifindex: int32(base.LinkIndex),
Handle: base.Handle,
Parent: base.Parent,
Info: MakeHandle(base.Priority, nl.Swap16(base.Protocol)),
}
req.AddData(msg)
req.AddData(nl.NewRtAttr(nl.TCA_KIND, nl.ZeroTerminated(filter.Type())))
options := nl.NewRtAttr(nl.TCA_OPTIONS, nil)
if u32, ok := filter.(*U32); ok {
// match all
sel := nl.TcU32Sel{
Nkeys: 1,
Flags: nl.TC_U32_TERMINAL,
}
sel.Keys = append(sel.Keys, nl.TcU32Key{})
nl.NewRtAttrChild(options, nl.TCA_U32_SEL, sel.Serialize())
actions := nl.NewRtAttrChild(options, nl.TCA_U32_ACT, nil)
table := nl.NewRtAttrChild(actions, nl.TCA_ACT_TAB, nil)
nl.NewRtAttrChild(table, nl.TCA_KIND, nl.ZeroTerminated("mirred"))
// redirect to other interface
mir := nl.TcMirred{
Action: nl.TC_ACT_STOLEN,
Eaction: nl.TCA_EGRESS_REDIR,
Ifindex: uint32(u32.RedirIndex),
}
aopts := nl.NewRtAttrChild(table, nl.TCA_OPTIONS, nil)
nl.NewRtAttrChild(aopts, nl.TCA_MIRRED_PARMS, mir.Serialize())
}
req.AddData(options)
_, err := req.Execute(syscall.NETLINK_ROUTE, 0)
return err
}
// FilterList gets a list of filters in the system.
// Equivalent to: `tc filter show`.
// Generally retunrs nothing if link and parent are not specified.
func FilterList(link Link, parent uint32) ([]Filter, error) {
req := nl.NewNetlinkRequest(syscall.RTM_GETTFILTER, syscall.NLM_F_DUMP)
msg := &nl.TcMsg{
Family: nl.FAMILY_ALL,
Parent: parent,
}
if link != nil {
base := link.Attrs()
ensureIndex(base)
msg.Ifindex = int32(base.Index)
}
req.AddData(msg)
msgs, err := req.Execute(syscall.NETLINK_ROUTE, syscall.RTM_NEWTFILTER)
if err != nil {
return nil, err
}
var res []Filter
for _, m := range msgs {
msg := nl.DeserializeTcMsg(m)
attrs, err := nl.ParseRouteAttr(m[msg.Len():])
if err != nil {
return nil, err
}
base := FilterAttrs{
LinkIndex: int(msg.Ifindex),
Handle: msg.Handle,
Parent: msg.Parent,
}
base.Priority, base.Protocol = MajorMinor(msg.Info)
base.Protocol = nl.Swap16(base.Protocol)
var filter Filter
filterType := ""
detailed := false
for _, attr := range attrs {
switch attr.Attr.Type {
case nl.TCA_KIND:
filterType = string(attr.Value[:len(attr.Value)-1])
switch filterType {
case "u32":
filter = &U32{}
default:
filter = &GenericFilter{FilterType: filterType}
}
case nl.TCA_OPTIONS:
switch filterType {
case "u32":
data, err := nl.ParseRouteAttr(attr.Value)
if err != nil {
return nil, err
}
detailed, err = parseU32Data(filter, data)
if err != nil {
return nil, err
}
}
}
}
// only return the detailed version of the filter
if detailed {
*filter.Attrs() = base
res = append(res, filter)
}
}
return res, nil
}
func parseU32Data(filter Filter, data []syscall.NetlinkRouteAttr) (bool, error) {
native = nl.NativeEndian()
u32 := filter.(*U32)
detailed := false
for _, datum := range data {
switch datum.Attr.Type {
case nl.TCA_U32_SEL:
detailed = true
sel := nl.DeserializeTcU32Sel(datum.Value)
// only parse if we have a very basic redirect
if sel.Flags&nl.TC_U32_TERMINAL == 0 || sel.Nkeys != 1 {
return detailed, nil
}
case nl.TCA_U32_ACT:
table, err := nl.ParseRouteAttr(datum.Value)
if err != nil {
return detailed, err
}
if len(table) != 1 || table[0].Attr.Type != nl.TCA_ACT_TAB {
return detailed, fmt.Errorf("Action table not formed properly")
}
aattrs, err := nl.ParseRouteAttr(table[0].Value)
for _, aattr := range aattrs {
switch aattr.Attr.Type {
case nl.TCA_KIND:
actionType := string(aattr.Value[:len(aattr.Value)-1])
// only parse if the action is mirred
if actionType != "mirred" {
return detailed, nil
}
case nl.TCA_OPTIONS:
adata, err := nl.ParseRouteAttr(aattr.Value)
if err != nil {
return detailed, err
}
for _, adatum := range adata {
switch adatum.Attr.Type {
case nl.TCA_MIRRED_PARMS:
mir := nl.DeserializeTcMirred(adatum.Value)
u32.RedirIndex = int(mir.Ifindex)
}
}
}
}
}
}
return detailed, nil
}