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// Copyright 2020 Google LLC. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package expr
import (
"encoding/binary"
"time"
"github.com/google/nftables/binaryutil"
"github.com/google/nftables/internal/parseexprfunc"
"github.com/mdlayher/netlink"
"golang.org/x/sys/unix"
)
// Not yet supported by unix package
// https://cs.opensource.google/go/x/sys/+/c6bc011c:unix/ztypes_linux.go;l=2027-2036
const (
NFTA_DYNSET_EXPRESSIONS = 0xa
NFT_DYNSET_F_EXPR = (1 << 1)
)
// Dynset represent a rule dynamically adding or updating a set or a map based on an incoming packet.
type Dynset struct {
SrcRegKey uint32
SrcRegData uint32
SetID uint32
SetName string
Operation uint32
Timeout time.Duration
Invert bool
Exprs []Any
}
func (e *Dynset) marshal(fam byte) ([]byte, error) {
// See: https://git.netfilter.org/libnftnl/tree/src/expr/dynset.c
var opAttrs []netlink.Attribute
opAttrs = append(opAttrs, netlink.Attribute{Type: unix.NFTA_DYNSET_SREG_KEY, Data: binaryutil.BigEndian.PutUint32(e.SrcRegKey)})
if e.SrcRegData != 0 {
opAttrs = append(opAttrs, netlink.Attribute{Type: unix.NFTA_DYNSET_SREG_DATA, Data: binaryutil.BigEndian.PutUint32(e.SrcRegData)})
}
opAttrs = append(opAttrs, netlink.Attribute{Type: unix.NFTA_DYNSET_OP, Data: binaryutil.BigEndian.PutUint32(e.Operation)})
if e.Timeout != 0 {
opAttrs = append(opAttrs, netlink.Attribute{Type: unix.NFTA_DYNSET_TIMEOUT, Data: binaryutil.BigEndian.PutUint64(uint64(e.Timeout.Milliseconds()))})
}
var flags uint32
if e.Invert {
flags |= unix.NFT_DYNSET_F_INV
}
opAttrs = append(opAttrs,
netlink.Attribute{Type: unix.NFTA_DYNSET_SET_NAME, Data: []byte(e.SetName + "\x00")},
netlink.Attribute{Type: unix.NFTA_DYNSET_SET_ID, Data: binaryutil.BigEndian.PutUint32(e.SetID)})
// Per https://git.netfilter.org/libnftnl/tree/src/expr/dynset.c?id=84d12cfacf8ddd857a09435f3d982ab6250d250c#n170
if len(e.Exprs) > 0 {
flags |= NFT_DYNSET_F_EXPR
switch len(e.Exprs) {
case 1:
exprData, err := Marshal(fam, e.Exprs[0])
if err != nil {
return nil, err
}
opAttrs = append(opAttrs, netlink.Attribute{Type: unix.NFTA_DYNSET_EXPR, Data: exprData})
default:
var elemAttrs []netlink.Attribute
for _, ex := range e.Exprs {
exprData, err := Marshal(fam, ex)
if err != nil {
return nil, err
}
elemAttrs = append(elemAttrs, netlink.Attribute{Type: unix.NFTA_LIST_ELEM, Data: exprData})
}
elemData, err := netlink.MarshalAttributes(elemAttrs)
if err != nil {
return nil, err
}
opAttrs = append(opAttrs, netlink.Attribute{Type: NFTA_DYNSET_EXPRESSIONS, Data: elemData})
}
}
opAttrs = append(opAttrs, netlink.Attribute{Type: unix.NFTA_DYNSET_FLAGS, Data: binaryutil.BigEndian.PutUint32(flags)})
opData, err := netlink.MarshalAttributes(opAttrs)
if err != nil {
return nil, err
}
return netlink.MarshalAttributes([]netlink.Attribute{
{Type: unix.NFTA_EXPR_NAME, Data: []byte("dynset\x00")},
{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: opData},
})
}
func (e *Dynset) unmarshal(fam byte, data []byte) error {
ad, err := netlink.NewAttributeDecoder(data)
if err != nil {
return err
}
ad.ByteOrder = binary.BigEndian
for ad.Next() {
switch ad.Type() {
case unix.NFTA_DYNSET_SET_NAME:
e.SetName = ad.String()
case unix.NFTA_DYNSET_SET_ID:
e.SetID = ad.Uint32()
case unix.NFTA_DYNSET_SREG_KEY:
e.SrcRegKey = ad.Uint32()
case unix.NFTA_DYNSET_SREG_DATA:
e.SrcRegData = ad.Uint32()
case unix.NFTA_DYNSET_OP:
e.Operation = ad.Uint32()
case unix.NFTA_DYNSET_TIMEOUT:
e.Timeout = time.Duration(time.Millisecond * time.Duration(ad.Uint64()))
case unix.NFTA_DYNSET_FLAGS:
e.Invert = (ad.Uint32() & unix.NFT_DYNSET_F_INV) != 0
case unix.NFTA_DYNSET_EXPR:
exprs, err := parseexprfunc.ParseExprBytesFunc(fam, ad, ad.Bytes())
if err != nil {
return err
}
e.setInterfaceExprs(exprs)
case NFTA_DYNSET_EXPRESSIONS:
exprs, err := parseexprfunc.ParseExprMsgFunc(fam, ad.Bytes())
if err != nil {
return err
}
e.setInterfaceExprs(exprs)
}
}
return ad.Err()
}
func (e *Dynset) setInterfaceExprs(exprs []interface{}) {
e.Exprs = make([]Any, len(exprs))
for i := range exprs {
e.Exprs[i] = exprs[i].(Any)
}
}
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