719f60bb91
Starting with v0.5.0, go-iptables exports a fast ChainExists() which does not rely upon listing all chains and searching the results but probes chain existence by listing its first rule. This should make a significant difference in rulesets with thousands of chains. Signed-off-by: Phil Sutter <psutter@redhat.com>
121 lines
3.5 KiB
Go
121 lines
3.5 KiB
Go
// Copyright 2017 CNI authors
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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 utils
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import (
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"errors"
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"fmt"
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"github.com/coreos/go-iptables/iptables"
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)
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const statusChainExists = 1
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// EnsureChain idempotently creates the iptables chain. It does not
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// return an error if the chain already exists.
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func EnsureChain(ipt *iptables.IPTables, table, chain string) error {
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if ipt == nil {
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return errors.New("failed to ensure iptable chain: IPTables was nil")
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}
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exists, err := ipt.ChainExists(table, chain)
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if err != nil {
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return fmt.Errorf("failed to check iptables chain existence: %v", err)
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}
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if !exists {
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err = ipt.NewChain(table, chain)
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if err != nil {
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eerr, eok := err.(*iptables.Error)
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if eok && eerr.ExitStatus() != statusChainExists {
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return err
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}
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}
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}
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return nil
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}
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// DeleteRule idempotently delete the iptables rule in the specified table/chain.
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// It does not return an error if the referring chain doesn't exist
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func DeleteRule(ipt *iptables.IPTables, table, chain string, rulespec ...string) error {
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if ipt == nil {
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return errors.New("failed to ensure iptable chain: IPTables was nil")
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}
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if err := ipt.Delete(table, chain, rulespec...); err != nil {
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eerr, eok := err.(*iptables.Error)
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switch {
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case eok && eerr.IsNotExist():
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// swallow here, the chain was already deleted
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return nil
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case eok && eerr.ExitStatus() == 2:
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// swallow here, invalid command line parameter because the referring rule is missing
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return nil
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default:
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return fmt.Errorf("Failed to delete referring rule %s %s: %v", table, chain, err)
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}
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}
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return nil
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}
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// DeleteChain idempotently deletes the specified table/chain.
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// It does not return an errors if the chain does not exist
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func DeleteChain(ipt *iptables.IPTables, table, chain string) error {
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if ipt == nil {
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return errors.New("failed to ensure iptable chain: IPTables was nil")
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}
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err := ipt.DeleteChain(table, chain)
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eerr, eok := err.(*iptables.Error)
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switch {
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case eok && eerr.IsNotExist():
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// swallow here, the chain was already deleted
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return nil
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default:
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return err
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}
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}
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// ClearChain idempotently clear the iptables rules in the specified table/chain.
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// If the chain does not exist, a new one will be created
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func ClearChain(ipt *iptables.IPTables, table, chain string) error {
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if ipt == nil {
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return errors.New("failed to ensure iptable chain: IPTables was nil")
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}
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err := ipt.ClearChain(table, chain)
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eerr, eok := err.(*iptables.Error)
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switch {
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case eok && eerr.IsNotExist():
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// swallow here, the chain was already deleted
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return EnsureChain(ipt, table, chain)
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default:
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return err
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}
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}
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// InsertUnique will add a rule to a chain if it does not already exist.
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// By default the rule is appended, unless prepend is true.
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func InsertUnique(ipt *iptables.IPTables, table, chain string, prepend bool, rule []string) error {
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exists, err := ipt.Exists(table, chain, rule...)
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if err != nil {
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return err
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}
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if exists {
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return nil
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}
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if prepend {
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return ipt.Insert(table, chain, 1, rule...)
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}
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return ipt.Append(table, chain, rule...)
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}
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