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host.go
35 lines (30 loc) · 810 Bytes
/
host.go
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// Unless explicitly stated otherwise all files in this repository are licensed
// under the Apache License Version 2.0.
// This product includes software developed at Datadog (https://www.datadoghq.com/).
// Copyright 2016-present Datadog, Inc.
//go:build !serverless
package util
import (
"net"
)
// Fqdn returns the FQDN for the host if any (this uses a DNS forward and reverse round trip).
func Fqdn(hostname string) string {
addrs, err := net.LookupIP(hostname)
if err != nil {
return hostname
}
for _, addr := range addrs {
if ipv4 := addr.To4(); ipv4 != nil {
ip, err := ipv4.MarshalText()
if err != nil {
return hostname
}
hosts, err := net.LookupAddr(string(ip))
if err != nil || len(hosts) == 0 {
return hostname
}
return hosts[0]
}
}
return hostname
}