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// Copyright 2018 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"
"github.com/google/nftables/binaryutil"
"github.com/mdlayher/netlink"
"golang.org/x/sys/unix"
)
type NATType uint32
// Possible NATType values.
const (
NATTypeSourceNAT NATType = unix.NFT_NAT_SNAT
NATTypeDestNAT NATType = unix.NFT_NAT_DNAT
)
type NAT struct {
Type NATType
Family uint32 // TODO: typed const
RegAddrMin uint32
RegAddrMax uint32
RegProtoMin uint32
RegProtoMax uint32
Random bool
FullyRandom bool
Persistent bool
Prefix bool
}
// |00048|N-|00001| |len |flags| type|
// |00008|--|00001| |len |flags| type|
// | 6e 61 74 00 | | data | n a t
// |00036|N-|00002| |len |flags| type|
// |00008|--|00001| |len |flags| type| NFTA_NAT_TYPE
// | 00 00 00 01 | | data | NFT_NAT_DNAT
// |00008|--|00002| |len |flags| type| NFTA_NAT_FAMILY
// | 00 00 00 02 | | data | NFPROTO_IPV4
// |00008|--|00003| |len |flags| type| NFTA_NAT_REG_ADDR_MIN
// | 00 00 00 01 | | data | reg 1
// |00008|--|00005| |len |flags| type| NFTA_NAT_REG_PROTO_MIN
// | 00 00 00 02 | | data | reg 2
func (e *NAT) marshal(fam byte) ([]byte, error) {
attrs := []netlink.Attribute{
{Type: unix.NFTA_NAT_TYPE, Data: binaryutil.BigEndian.PutUint32(uint32(e.Type))},
{Type: unix.NFTA_NAT_FAMILY, Data: binaryutil.BigEndian.PutUint32(e.Family)},
}
if e.RegAddrMin != 0 {
attrs = append(attrs, netlink.Attribute{Type: unix.NFTA_NAT_REG_ADDR_MIN, Data: binaryutil.BigEndian.PutUint32(e.RegAddrMin)})
if e.RegAddrMax != 0 {
attrs = append(attrs, netlink.Attribute{Type: unix.NFTA_NAT_REG_ADDR_MAX, Data: binaryutil.BigEndian.PutUint32(e.RegAddrMax)})
}
}
if e.RegProtoMin != 0 {
attrs = append(attrs, netlink.Attribute{Type: unix.NFTA_NAT_REG_PROTO_MIN, Data: binaryutil.BigEndian.PutUint32(e.RegProtoMin)})
if e.RegProtoMax != 0 {
attrs = append(attrs, netlink.Attribute{Type: unix.NFTA_NAT_REG_PROTO_MAX, Data: binaryutil.BigEndian.PutUint32(e.RegProtoMax)})
}
}
flags := uint32(0)
if e.Random {
flags |= NF_NAT_RANGE_PROTO_RANDOM
}
if e.FullyRandom {
flags |= NF_NAT_RANGE_PROTO_RANDOM_FULLY
}
if e.Persistent {
flags |= NF_NAT_RANGE_PERSISTENT
}
if e.Prefix {
flags |= NF_NAT_RANGE_PREFIX
}
if flags != 0 {
attrs = append(attrs, netlink.Attribute{Type: unix.NFTA_NAT_FLAGS, Data: binaryutil.BigEndian.PutUint32(flags)})
}
data, err := netlink.MarshalAttributes(attrs)
if err != nil {
return nil, err
}
return netlink.MarshalAttributes([]netlink.Attribute{
{Type: unix.NFTA_EXPR_NAME, Data: []byte("nat\x00")},
{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
})
}
func (e *NAT) 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_NAT_TYPE:
e.Type = NATType(ad.Uint32())
case unix.NFTA_NAT_FAMILY:
e.Family = ad.Uint32()
case unix.NFTA_NAT_REG_ADDR_MIN:
e.RegAddrMin = ad.Uint32()
case unix.NFTA_NAT_REG_ADDR_MAX:
e.RegAddrMax = ad.Uint32()
case unix.NFTA_NAT_REG_PROTO_MIN:
e.RegProtoMin = ad.Uint32()
case unix.NFTA_NAT_REG_PROTO_MAX:
e.RegProtoMax = ad.Uint32()
case unix.NFTA_NAT_FLAGS:
flags := ad.Uint32()
e.Persistent = (flags & NF_NAT_RANGE_PERSISTENT) != 0
e.Random = (flags & NF_NAT_RANGE_PROTO_RANDOM) != 0
e.FullyRandom = (flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY) != 0
e.Prefix = (flags & NF_NAT_RANGE_PREFIX) != 0
}
}
return ad.Err()
}
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