67 lines
2 KiB
Go
67 lines
2 KiB
Go
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// Copyright 2015 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 ip
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import (
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"fmt"
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"net"
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"github.com/coreos/go-iptables/iptables"
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)
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// SetupIPMasq installs iptables rules to masquerade traffic
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// coming from ipn and going outside of it
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func SetupIPMasq(ipn *net.IPNet, chain string, comment string) error {
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ipt, err := iptables.New()
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if err != nil {
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return fmt.Errorf("failed to locate iptables: %v", err)
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}
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if err = ipt.NewChain("nat", chain); err != nil {
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if err.(*iptables.Error).ExitStatus() != 1 {
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// TODO(eyakubovich): assumes exit status 1 implies chain exists
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return err
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}
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}
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if err = ipt.AppendUnique("nat", chain, "-d", ipn.String(), "-j", "ACCEPT", "-m", "comment", "--comment", comment); err != nil {
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return err
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}
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if err = ipt.AppendUnique("nat", chain, "!", "-d", "224.0.0.0/4", "-j", "MASQUERADE", "-m", "comment", "--comment", comment); err != nil {
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return err
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}
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return ipt.AppendUnique("nat", "POSTROUTING", "-s", ipn.String(), "-j", chain, "-m", "comment", "--comment", comment)
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}
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// TeardownIPMasq undoes the effects of SetupIPMasq
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func TeardownIPMasq(ipn *net.IPNet, chain string, comment string) error {
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ipt, err := iptables.New()
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if err != nil {
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return fmt.Errorf("failed to locate iptables: %v", err)
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}
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if err = ipt.Delete("nat", "POSTROUTING", "-s", ipn.String(), "-j", chain, "-m", "comment", "--comment", comment); err != nil {
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return err
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}
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if err = ipt.ClearChain("nat", chain); err != nil {
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return err
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}
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return ipt.DeleteChain("nat", chain)
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}
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