Hash expr implementation (#68)
* [expr] Implement Hash expr. * [test] Add Hash test case.
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Minaru
Michael Stapelberg
parent
d379352a0d
commit
35de0a609f
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// 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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type HashType uint32
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const (
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HashTypeJenkins HashType = unix.NFT_HASH_JENKINS
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HashTypeSym HashType = unix.NFT_HASH_SYM
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)
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// Hash defines type for nftables internal hashing functions
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type Hash struct {
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SourceRegister uint32
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DestRegister uint32
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Length uint32
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Modulus uint32
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Seed uint32
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Offset uint32
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Type HashType
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}
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func (e *Hash) marshal() ([]byte, error) {
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data, err := netlink.MarshalAttributes([]netlink.Attribute{
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{Type: unix.NFTA_HASH_SREG, Data: binaryutil.BigEndian.PutUint32(uint32(e.SourceRegister))},
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{Type: unix.NFTA_HASH_DREG, Data: binaryutil.BigEndian.PutUint32(uint32(e.DestRegister))},
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{Type: unix.NFTA_HASH_LEN, Data: binaryutil.BigEndian.PutUint32(uint32(e.Length))},
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{Type: unix.NFTA_HASH_MODULUS, Data: binaryutil.BigEndian.PutUint32(uint32(e.Modulus))},
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{Type: unix.NFTA_HASH_SEED, Data: binaryutil.BigEndian.PutUint32(uint32(e.Seed))},
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{Type: unix.NFTA_HASH_OFFSET, Data: binaryutil.BigEndian.PutUint32(uint32(e.Offset))},
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{Type: unix.NFTA_HASH_TYPE, Data: binaryutil.BigEndian.PutUint32(uint32(e.Type))},
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})
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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("hash\x00")},
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{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
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})
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}
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func (e *Hash) 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_HASH_SREG:
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e.SourceRegister = ad.Uint32()
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case unix.NFTA_HASH_DREG:
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e.DestRegister = ad.Uint32()
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case unix.NFTA_HASH_LEN:
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e.Length = ad.Uint32()
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case unix.NFTA_HASH_MODULUS:
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e.Modulus = ad.Uint32()
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case unix.NFTA_HASH_SEED:
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e.Seed = ad.Uint32()
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case unix.NFTA_HASH_OFFSET:
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e.Offset = ad.Uint32()
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case unix.NFTA_HASH_TYPE:
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e.Type = HashType(ad.Uint32())
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}
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}
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return ad.Err()
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}
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@ -3044,3 +3044,98 @@ func TestVmap(t *testing.T) {
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}
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}
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}
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func TestJHash(t *testing.T) {
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// The want byte sequences come from stracing nft(8), e.g.:
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// strace -f -v -x -s 2048 -eraw=sendto nft add rule filter prerouting mark set jhash ip saddr mod 2
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//
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// The nft(8) command sequence was taken from:
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// https://wiki.nftables.org/wiki-nftables/index.php/Quick_reference-nftables_in_10_minutes#Tcp
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want := [][]byte{
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// batch begin
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[]byte("\x00\x00\x00\x0a"),
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// nft flush ruleset
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[]byte("\x00\x00\x00\x00"),
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// nft add table ip filter
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[]byte("\x02\x00\x00\x00\x0b\x00\x01\x00\x66\x69\x6c\x74\x65\x72\x00\x00\x08\x00\x02\x00\x00\x00\x00\x00"),
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// nft add chain ip filter base-chain { type filter hook prerouting priority 0 \; }
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[]byte("\x02\x00\x00\x00\x0b\x00\x01\x00\x66\x69\x6c\x74\x65\x72\x00\x00\x0f\x00\x03\x00\x62\x61\x73\x65\x2d\x63\x68\x61\x69\x6e\x00\x00\x14\x00\x04\x80\x08\x00\x01\x00\x00\x00\x00\x00\x08\x00\x02\x00\x00\x00\x00\x00\x0b\x00\x07\x00\x66\x69\x6c\x74\x65\x72\x00\x00"),
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// nft add rule filter base_chain mark set jhash ip saddr mod 2 seed 0xfeedcafe offset 1
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[]byte("\x02\x00\x00\x00\x0b\x00\x01\x00\x66\x69\x6c\x74\x65\x72\x00\x00\x0f\x00\x02\x00\x62\x61\x73\x65\x2d\x63\x68\x61\x69\x6e\x00\x00\xa8\x00\x04\x80\x34\x00\x01\x80\x0c\x00\x01\x00\x70\x61\x79\x6c\x6f\x61\x64\x00\x24\x00\x02\x80\x08\x00\x01\x00\x00\x00\x00\x02\x08\x00\x02\x00\x00\x00\x00\x01\x08\x00\x03\x00\x00\x00\x00\x0c\x08\x00\x04\x00\x00\x00\x00\x04\x4c\x00\x01\x80\x09\x00\x01\x00\x68\x61\x73\x68\x00\x00\x00\x00\x3c\x00\x02\x80\x08\x00\x01\x00\x00\x00\x00\x02\x08\x00\x02\x00\x00\x00\x00\x01\x08\x00\x03\x00\x00\x00\x00\x04\x08\x00\x04\x00\x00\x00\x00\x02\x08\x00\x05\x00\xfe\xed\xca\xfe\x08\x00\x06\x00\x00\x00\x00\x01\x08\x00\x07\x00\x00\x00\x00\x00\x24\x00\x01\x80\x09\x00\x01\x00\x6d\x65\x74\x61\x00\x00\x00\x00\x14\x00\x02\x80\x08\x00\x02\x00\x00\x00\x00\x03\x08\x00\x03\x00\x00\x00\x00\x01"),
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// batch end
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[]byte("\x00\x00\x00\x0a"),
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}
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c := &nftables.Conn{
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TestDial: func(req []netlink.Message) ([]netlink.Message, error) {
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for idx, msg := range req {
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b, err := msg.MarshalBinary()
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if err != nil {
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t.Fatal(err)
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}
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if len(b) < 16 {
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continue
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}
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b = b[16:]
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if len(want) == 0 {
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t.Errorf("no want entry for message %d: %x", idx, b)
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continue
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}
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if got, want := b, want[0]; !bytes.Equal(got, want) {
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t.Errorf("message %d: %s", idx, linediff(nfdump(got), nfdump(want)))
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}
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want = want[1:]
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}
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return req, nil
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},
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}
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c.FlushRuleset()
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filter := c.AddTable(&nftables.Table{
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Family: nftables.TableFamilyIPv4,
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Name: "filter",
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})
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forward := c.AddChain(&nftables.Chain{
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Name: "base-chain",
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Table: filter,
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Type: nftables.ChainTypeFilter,
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Hooknum: nftables.ChainHookPrerouting,
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Priority: nftables.ChainPriorityFilter,
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})
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c.AddRule(&nftables.Rule{
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Table: filter,
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Chain: forward,
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Exprs: []expr.Any{
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// [ payload load 4b @ network header + 12 => reg 2 ]
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&expr.Payload{
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DestRegister: 2,
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Base: expr.PayloadBaseNetworkHeader,
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Offset: 12,
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Len: 4,
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},
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// [ hash reg 1 = jhash(reg 2, 4, 0xfeedcafe) % mod 2 offset 1 ]
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&expr.Hash{
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SourceRegister: 2,
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DestRegister: 1,
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Length: 4,
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Modulus: 2,
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Seed: 4276996862,
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Offset: 1,
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Type: expr.HashTypeJenkins,
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},
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// [ meta set mark with reg 1 ]
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&expr.Meta{
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Key: expr.MetaKeyMARK,
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SourceRegister: true,
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Register: 1,
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},
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},
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})
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if err := c.Flush(); err != nil {
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t.Fatal(err)
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}
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}
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