58 lines
1.5 KiB
Go
58 lines
1.5 KiB
Go
/*
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Copyright 2015 The Kubernetes Authors.
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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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http://www.apache.org/licenses/LICENSE-2.0
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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 dns
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import (
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"io/ioutil"
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"net"
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"strings"
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"k8s.io/klog/v2"
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)
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var defResolvConf = "/etc/resolv.conf"
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// GetSystemNameServers returns the list of nameservers located in the file /etc/resolv.conf
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func GetSystemNameServers() ([]net.IP, error) {
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var nameservers []net.IP
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file, err := ioutil.ReadFile(defResolvConf)
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if err != nil {
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return nameservers, err
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}
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// Lines of the form "nameserver 1.2.3.4" accumulate.
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lines := strings.Split(string(file), "\n")
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for l := range lines {
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trimmed := strings.TrimSpace(lines[l])
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if len(trimmed) == 0 || trimmed[0] == '#' || trimmed[0] == ';' {
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continue
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}
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fields := strings.Fields(trimmed)
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if len(fields) < 2 {
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continue
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}
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if fields[0] == "nameserver" {
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ip := net.ParseIP(fields[1])
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if ip != nil {
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nameservers = append(nameservers, ip)
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}
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}
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}
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klog.V(3).InfoS("Nameservers", "hosts", nameservers)
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return nameservers, nil
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}
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