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tailscale/wgengine/router/dns.go

75 lines
1.8 KiB
Go

// Copyright (c) 2020 Tailscale Inc & 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 router
import (
"inet.af/netaddr"
)
// DNSConfig is the subset of Config that contains DNS parameters.
type DNSConfig struct {
// Nameservers are the IP addresses of the nameservers to use.
Nameservers []netaddr.IP
// Domains are the search domains to use.
Domains []string
}
// EquivalentTo determines whether its argument and receiver
// represent equivalent DNS configurations (then DNS reconfig is a no-op).
func (lhs DNSConfig) EquivalentTo(rhs DNSConfig) bool {
if len(lhs.Nameservers) != len(rhs.Nameservers) {
return false
}
if len(lhs.Domains) != len(rhs.Domains) {
return false
}
// With how we perform resolution order shouldn't matter,
// but it is unlikely that we will encounter different orders.
for i, server := range lhs.Nameservers {
if rhs.Nameservers[i] != server {
return false
}
}
for i, domain := range lhs.Domains {
if rhs.Domains[i] != domain {
return false
}
}
return true
}
// dnsMode determines how DNS settings are managed.
type dnsMode uint8
const (
// dnsDirect indicates that /etc/resolv.conf is edited directly.
dnsDirect dnsMode = iota
// dnsResolvconf indicates that a resolvconf binary is used.
dnsResolvconf
// dnsNetworkManager indicates that the NetworkManaer DBus API is used.
dnsNetworkManager
// dnsResolved indicates that the systemd-resolved DBus API is used.
dnsResolved
)
func (m dnsMode) String() string {
switch m {
case dnsDirect:
return "direct"
case dnsResolvconf:
return "resolvconf"
case dnsNetworkManager:
return "networkmanager"
case dnsResolved:
return "resolved"
default:
return "???"
}
}