vendor/upspin.io/serverutil/addr.go

// Copyright 2016 The Upspin Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package serverutil

import (
	"net"

	"upspin.io/config"
)

// IsLoopback returns true if the name only resolves to loopback addresses.
func IsLoopback(addr string) bool {
	host, _, err := net.SplitHostPort(addr)
	if err != nil {
		host = addr
	}
	if host == "localhost" || host == "127.0.0.1" || host == "::1" {
		return true
	}
	// Check for local IPC.
	if config.IsLocal(host) {
		return true
	}
	// Check for loopback network.
	ips, err := net.LookupIP(host)
	if err != nil {
		return false
	}
	for _, ip := range ips {
		if !ip.IsLoopback() {
			return false
		}
	}
	return true
}