mirror of
https://github.com/tailscale/tailscale.git
synced 2024-12-05 16:05:36 +00:00
7dcf65a10a
Discovered this while investigating the following issue; I think it's unrelated, but might as well fix it. Also, add a test helper for checking things that have an IsZero method using the reflect package. Updates tailscale/support-escalations#55 Signed-off-by: Andrew Dunham <andrew@du.nham.ca> Change-Id: I57b7adde43bcef9483763b561da173b4c35f49e2
197 lines
5.2 KiB
Go
197 lines
5.2 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
|
|
// SPDX-License-Identifier: BSD-3-Clause
|
|
|
|
package dns
|
|
|
|
import (
|
|
"bufio"
|
|
"errors"
|
|
"fmt"
|
|
"net/netip"
|
|
"slices"
|
|
"strings"
|
|
|
|
"tailscale.com/types/logger"
|
|
"tailscale.com/util/dnsname"
|
|
)
|
|
|
|
// An OSConfigurator applies DNS settings to the operating system.
|
|
type OSConfigurator interface {
|
|
// SetDNS updates the OS's DNS configuration to match cfg.
|
|
// If cfg is the zero value, all Tailscale-related DNS
|
|
// configuration is removed.
|
|
// SetDNS must not be called after Close.
|
|
// SetDNS takes ownership of cfg.
|
|
SetDNS(cfg OSConfig) error
|
|
// SupportsSplitDNS reports whether the configurator is capable of
|
|
// installing a resolver only for specific DNS suffixes. If false,
|
|
// the configurator can only set a global resolver.
|
|
SupportsSplitDNS() bool
|
|
// GetBaseConfig returns the OS's "base" configuration, i.e. the
|
|
// resolver settings the OS would use without Tailscale
|
|
// contributing any configuration.
|
|
// GetBaseConfig must return the tailscale-free base config even
|
|
// after SetDNS has been called to set a Tailscale configuration.
|
|
// Only works when SupportsSplitDNS=false.
|
|
|
|
// Implementations that don't support getting the base config must
|
|
// return ErrGetBaseConfigNotSupported.
|
|
GetBaseConfig() (OSConfig, error)
|
|
// Close removes Tailscale-related DNS configuration from the OS.
|
|
Close() error
|
|
}
|
|
|
|
// HostEntry represents a single line in the OS's hosts file.
|
|
type HostEntry struct {
|
|
Addr netip.Addr
|
|
Hosts []string
|
|
}
|
|
|
|
// OSConfig is an OS DNS configuration.
|
|
type OSConfig struct {
|
|
// Hosts is a map of DNS FQDNs to their IPs, which should be added to the
|
|
// OS's hosts file. Currently, (2022-08-12) it is only populated for Windows
|
|
// in SplitDNS mode and with Smart Name Resolution turned on.
|
|
Hosts []*HostEntry
|
|
// Nameservers are the IP addresses of the nameservers to use.
|
|
Nameservers []netip.Addr
|
|
// SearchDomains are the domain suffixes to use when expanding
|
|
// single-label name queries. SearchDomains is additive to
|
|
// whatever non-Tailscale search domains the OS has.
|
|
SearchDomains []dnsname.FQDN
|
|
// MatchDomains are the DNS suffixes for which Nameservers should
|
|
// be used. If empty, Nameservers is installed as the "primary" resolver.
|
|
// A non-empty MatchDomains requests a "split DNS" configuration
|
|
// from the OS, which will only work with OSConfigurators that
|
|
// report SupportsSplitDNS()=true.
|
|
MatchDomains []dnsname.FQDN
|
|
}
|
|
|
|
func (o *OSConfig) WriteToBufioWriter(w *bufio.Writer) {
|
|
if o == nil {
|
|
w.WriteString("<nil>")
|
|
return
|
|
}
|
|
w.WriteString("{")
|
|
if len(o.Hosts) > 0 {
|
|
fmt.Fprintf(w, "Hosts:%v ", o.Hosts)
|
|
}
|
|
if len(o.Nameservers) > 0 {
|
|
fmt.Fprintf(w, "Nameservers:%v ", o.Nameservers)
|
|
}
|
|
if len(o.SearchDomains) > 0 {
|
|
fmt.Fprintf(w, "SearchDomains:%v ", o.SearchDomains)
|
|
}
|
|
if len(o.MatchDomains) > 0 {
|
|
w.WriteString("MatchDomains:[")
|
|
sp := ""
|
|
var numARPA int
|
|
for _, s := range o.MatchDomains {
|
|
if strings.HasSuffix(string(s), ".arpa.") {
|
|
numARPA++
|
|
continue
|
|
}
|
|
w.WriteString(sp)
|
|
w.WriteString(string(s))
|
|
sp = " "
|
|
}
|
|
w.WriteString("]")
|
|
if numARPA > 0 {
|
|
fmt.Fprintf(w, "+%darpa", numARPA)
|
|
}
|
|
}
|
|
w.WriteString("}")
|
|
}
|
|
|
|
func (o OSConfig) IsZero() bool {
|
|
return len(o.Hosts) == 0 &&
|
|
len(o.Nameservers) == 0 &&
|
|
len(o.SearchDomains) == 0 &&
|
|
len(o.MatchDomains) == 0
|
|
}
|
|
|
|
func (a OSConfig) Equal(b OSConfig) bool {
|
|
if len(a.Hosts) != len(b.Hosts) {
|
|
return false
|
|
}
|
|
if len(a.Nameservers) != len(b.Nameservers) {
|
|
return false
|
|
}
|
|
if len(a.SearchDomains) != len(b.SearchDomains) {
|
|
return false
|
|
}
|
|
if len(a.MatchDomains) != len(b.MatchDomains) {
|
|
return false
|
|
}
|
|
|
|
for i := range a.Hosts {
|
|
ha, hb := a.Hosts[i], b.Hosts[i]
|
|
if ha.Addr != hb.Addr {
|
|
return false
|
|
}
|
|
if !slices.Equal(ha.Hosts, hb.Hosts) {
|
|
return false
|
|
}
|
|
}
|
|
for i := range a.Nameservers {
|
|
if a.Nameservers[i] != b.Nameservers[i] {
|
|
return false
|
|
}
|
|
}
|
|
for i := range a.SearchDomains {
|
|
if a.SearchDomains[i] != b.SearchDomains[i] {
|
|
return false
|
|
}
|
|
}
|
|
for i := range a.MatchDomains {
|
|
if a.MatchDomains[i] != b.MatchDomains[i] {
|
|
return false
|
|
}
|
|
}
|
|
|
|
return true
|
|
}
|
|
|
|
// Format implements the fmt.Formatter interface to ensure that Hosts is
|
|
// printed correctly (i.e. not as a bunch of pointers).
|
|
//
|
|
// Fixes https://github.com/tailscale/tailscale/issues/5669
|
|
func (a OSConfig) Format(f fmt.State, verb rune) {
|
|
logger.ArgWriter(func(w *bufio.Writer) {
|
|
w.WriteString(`{Nameservers:[`)
|
|
for i, ns := range a.Nameservers {
|
|
if i != 0 {
|
|
w.WriteString(" ")
|
|
}
|
|
fmt.Fprintf(w, "%+v", ns)
|
|
}
|
|
w.WriteString(`] SearchDomains:[`)
|
|
for i, domain := range a.SearchDomains {
|
|
if i != 0 {
|
|
w.WriteString(" ")
|
|
}
|
|
fmt.Fprintf(w, "%+v", domain)
|
|
}
|
|
w.WriteString(`] MatchDomains:[`)
|
|
for i, domain := range a.MatchDomains {
|
|
if i != 0 {
|
|
w.WriteString(" ")
|
|
}
|
|
fmt.Fprintf(w, "%+v", domain)
|
|
}
|
|
w.WriteString(`] Hosts:[`)
|
|
for i, host := range a.Hosts {
|
|
if i != 0 {
|
|
w.WriteString(" ")
|
|
}
|
|
fmt.Fprintf(w, "%+v", host)
|
|
}
|
|
w.WriteString(`]}`)
|
|
}).Format(f, verb)
|
|
}
|
|
|
|
// ErrGetBaseConfigNotSupported is the error
|
|
// OSConfigurator.GetBaseConfig returns when the OSConfigurator
|
|
// doesn't support reading the underlying configuration out of the OS.
|
|
var ErrGetBaseConfigNotSupported = errors.New("getting OS base config is not supported")
|