84 lines
2.6 KiB
Go
84 lines
2.6 KiB
Go
// Copyright 2018 Google LLC. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package expr
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import (
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"encoding/binary"
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"github.com/google/nftables/binaryutil"
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"github.com/mdlayher/netlink"
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"golang.org/x/sys/unix"
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)
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// Lookup represents a match against the contents of a set.
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type Lookup struct {
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SourceRegister uint32
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DestRegister uint32
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SetID uint32
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SetName string
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Invert bool
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}
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func (e *Lookup) marshal() ([]byte, error) {
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// See: https://git.netfilter.org/libnftnl/tree/src/expr/lookup.c?id=6dc1c3d8bb64077da7f3f28c7368fb087d10a492#n115
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var opAttrs []netlink.Attribute
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if e.SourceRegister != 0 {
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opAttrs = append(opAttrs, netlink.Attribute{Type: unix.NFTA_LOOKUP_SREG, Data: binaryutil.BigEndian.PutUint32(e.SourceRegister)})
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}
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if e.DestRegister != 0 {
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opAttrs = append(opAttrs, netlink.Attribute{Type: unix.NFTA_LOOKUP_DREG, Data: binaryutil.BigEndian.PutUint32(e.DestRegister)})
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}
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if e.Invert {
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opAttrs = append(opAttrs, netlink.Attribute{Type: unix.NFTA_LOOKUP_FLAGS, Data: binaryutil.BigEndian.PutUint32(unix.NFT_LOOKUP_F_INV)})
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}
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opAttrs = append(opAttrs,
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netlink.Attribute{Type: unix.NFTA_LOOKUP_SET, Data: []byte(e.SetName + "\x00")},
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netlink.Attribute{Type: unix.NFTA_LOOKUP_SET_ID, Data: binaryutil.BigEndian.PutUint32(e.SetID)},
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)
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opData, err := netlink.MarshalAttributes(opAttrs)
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if err != nil {
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return nil, err
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}
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return netlink.MarshalAttributes([]netlink.Attribute{
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{Type: unix.NFTA_EXPR_NAME, Data: []byte("lookup\x00")},
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{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: opData},
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})
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}
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func (e *Lookup) unmarshal(data []byte) error {
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ad, err := netlink.NewAttributeDecoder(data)
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if err != nil {
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return err
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}
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ad.ByteOrder = binary.BigEndian
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for ad.Next() {
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switch ad.Type() {
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case unix.NFTA_LOOKUP_SET:
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e.SetName = ad.String()
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case unix.NFTA_LOOKUP_SET_ID:
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e.SetID = ad.Uint32()
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case unix.NFTA_LOOKUP_SREG:
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e.SourceRegister = ad.Uint32()
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case unix.NFTA_LOOKUP_DREG:
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e.DestRegister = ad.Uint32()
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case unix.NFTA_LOOKUP_FLAGS:
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e.Invert = (ad.Uint32() & unix.NFT_LOOKUP_F_INV) != 0
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}
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}
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return ad.Err()
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}
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