Dragonfly2

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//go:build linux
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/*
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 *     Copyright 2020 The Dragonfly 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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 */
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package daemon
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import (
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	"fmt"
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	"os"
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	"golang.org/x/sys/unix"
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	logger "d7y.io/dragonfly/v2/internal/dflog"
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)
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func switchNetNamespace(target string) (func() error, error) {
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	fd, err := unix.Open(target, unix.O_RDONLY, 0)
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	if err != nil {
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		return nil, err
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	}
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	defer unix.Close(fd)
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	orgNS := fmt.Sprintf("/proc/%d/ns/net", os.Getpid())
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	// hold the original net namespace
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	orgFD, err := unix.Open(orgNS, unix.O_RDONLY, 0)
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	if err != nil {
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		return nil, err
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	}
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	logger.Infof("switch net namespace, from %s to %s", orgNS, target)
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	err = unix.Setns(fd, unix.CLONE_NEWNET)
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	if err != nil {
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		return nil, err
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	}
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	return func() error {
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		if err := unix.Setns(orgFD, unix.CLONE_NEWNET); err != nil {
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			logger.Errorf("recover net namespace, from %s to %s, error: %s", target, orgNS, err)
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			return err
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		}
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		logger.Infof("recover net namespace, from %s to %s", target, orgNS)
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		if err := unix.Close(orgFD); err != nil {
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			logger.Errorf("recover net namespace, close fd error: %s", err)
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			return err
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		}
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		logger.Infof("recover net namespace, close original fd")
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		return nil
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	}, nil
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}
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