62 lines
1.5 KiB
Go
62 lines
1.5 KiB
Go
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// Copyright 2021 The Prometheus 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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//
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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 osutil
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import (
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"encoding"
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"net"
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"os"
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)
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// GetFQDN returns a FQDN if it's possible, otherwise falls back to hostname.
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func GetFQDN() (string, error) {
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hostname, err := os.Hostname()
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if err != nil {
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return "", err
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}
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ips, err := net.LookupIP(hostname)
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if err != nil {
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// Return the system hostname if we can't look up the IP address.
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return hostname, nil
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}
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lookup := func(ipStr encoding.TextMarshaler) (string, error) {
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ip, err := ipStr.MarshalText()
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if err != nil {
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return "", err
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}
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hosts, err := net.LookupAddr(string(ip))
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if err != nil || len(hosts) == 0 {
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return "", err
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}
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return hosts[0], nil
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}
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for _, addr := range ips {
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if ip := addr.To4(); ip != nil {
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if fqdn, err := lookup(ip); err == nil {
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return fqdn, nil
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}
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}
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if ip := addr.To16(); ip != nil {
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if fqdn, err := lookup(ip); err == nil {
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return fqdn, nil
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}
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}
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}
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return hostname, nil
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}
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