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/
dns_config.go
97 lines (86 loc) · 2.36 KB
/
dns_config.go
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// Copyright 2016 The rkt Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package common
import (
"bufio"
"fmt"
"os"
"path/filepath"
"strings"
_common "github.com/rkt/rkt/common"
"github.com/rkt/rkt/pkg/fs"
)
/*
Bind-mount the hosts /etc/resolv.conf in to the stage1's /etc/rkt-resolv.conf.
That file will then be bind-mounted in to the stage2 by perpare-app.c
*/
func UseHostResolv(mnt fs.MountUnmounter, podRoot string) error {
return BindMount(
mnt,
"/etc/resolv.conf",
filepath.Join(_common.Stage1RootfsPath(podRoot), "etc/rkt-resolv.conf"),
true)
}
/*
Bind-mount the hosts /etc/hosts in to the stage1's /etc/rkt-hosts
That file will then be bind-mounted in to the stage2 by perpare-app.c
*/
func UseHostHosts(mnt fs.MountUnmounter, podRoot string) error {
return BindMount(
mnt,
"/etc/hosts",
filepath.Join(_common.Stage1RootfsPath(podRoot), "etc/rkt-hosts"),
true)
}
// AddHostsEntry adds an entry to an *existing* hosts file, appending
// to the existing IP if needed
func AddHostsEntry(filename string, ip string, hostname string) error {
fp, err := os.OpenFile(filename, os.O_RDWR, 0644)
if err != nil {
return err
}
defer fp.Close()
out := ""
found := false
scanner := bufio.NewScanner(fp)
for scanner.Scan() {
line := scanner.Text()
words := strings.Fields(line)
if !found && len(words) > 0 && words[0] == ip {
found = true
out += fmt.Sprintf("%s %s\n", line, hostname)
} else {
out += line
out += "\n"
}
}
if err := scanner.Err(); err != nil {
return err
}
// If that IP was not found, add a new line
if !found {
out += fmt.Sprintf("%s\t%s\n", ip, hostname)
}
// Seek to the beginning, truncate, and write again
if _, err := fp.Seek(0, 0); err != nil {
return err
}
if err := fp.Truncate(0); err != nil {
return err
}
if _, err := fp.Write([]byte(out)); err != nil {
return err
}
return nil
}