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83fe87c5b0
This go-nft version allows its users to only read particular tables/chains when invoking `ReadConfig`, instead of the entire ruleset. This will make deleting rules from a large ruleset faster, thus speeding up CNI DELs. Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=2175041 Signed-off-by: Miguel Duarte Barroso <mdbarroso@redhat.com>
109 lines
2.8 KiB
Go
109 lines
2.8 KiB
Go
/*
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* This file is part of the go-nft project
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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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*
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* Copyright 2021 Red Hat, Inc.
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*
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*/
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package exec
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import (
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"bytes"
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"context"
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"fmt"
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"io/ioutil"
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"os"
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"os/exec"
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"strings"
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nftconfig "github.com/networkplumbing/go-nft/nft/config"
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)
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const (
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cmdBin = "nft"
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cmdFile = "-f"
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cmdJSON = "-j"
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cmdList = "list"
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cmdRuleset = "ruleset"
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)
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// ReadConfig loads the nftables configuration from the system and
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// returns it as a nftables config structure.
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// The system is expected to have the `nft` executable deployed and nftables enabled in the kernel.
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func ReadConfig(ctx context.Context, filterCommands ...string) (*nftconfig.Config, error) {
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whatToList := cmdRuleset
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if len(filterCommands) > 0 {
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whatToList = strings.Join(filterCommands, " ")
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}
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stdout, err := execCommand(ctx, cmdJSON, cmdList, whatToList)
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if err != nil {
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return nil, err
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}
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config := nftconfig.New()
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if err := config.FromJSON(stdout.Bytes()); err != nil {
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return nil, fmt.Errorf("failed to list ruleset: %v", err)
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}
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return config, nil
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}
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// ApplyConfig applies the given nftables config on the system.
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// The system is expected to have the `nft` executable deployed and nftables enabled in the kernel.
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func ApplyConfig(ctx context.Context, c *nftconfig.Config) error {
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data, err := c.ToJSON()
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if err != nil {
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return err
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}
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tmpFile, err := ioutil.TempFile(os.TempDir(), "spoofcheck-")
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if err != nil {
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return fmt.Errorf("failed to create temporary file: %v", err)
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}
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defer os.Remove(tmpFile.Name())
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if _, err = tmpFile.Write(data); err != nil {
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return fmt.Errorf("failed to write to temporary file: %v", err)
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}
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if err := tmpFile.Close(); err != nil {
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return fmt.Errorf("failed to close temporary file: %v", err)
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}
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if _, err := execCommand(ctx, cmdJSON, cmdFile, tmpFile.Name()); err != nil {
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return err
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}
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return nil
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}
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func execCommand(ctx context.Context, args ...string) (*bytes.Buffer, error) {
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cmd := exec.CommandContext(ctx, cmdBin, args...)
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var stdout, stderr bytes.Buffer
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cmd.Stderr = &stderr
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cmd.Stdout = &stdout
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if err := cmd.Run(); err != nil {
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return nil, fmt.Errorf(
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"failed to execute %s %s: %v stdout:'%s' stderr:'%s'",
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cmd.Path, strings.Join(cmd.Args, " "), err, stdout.String(), stderr.String(),
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)
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}
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return &stdout, nil
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}
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