// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
package dns
import (
"errors"
"io/fs"
"os"
"strings"
"testing"
"tailscale.com/tstest"
"tailscale.com/util/cmpver"
)
func TestLinuxDNSMode(t *testing.T) {
tests := []struct {
name string
env newOSConfigEnv
wantLog string
want string
}{
{
name: "no_obvious_resolv.conf_owner",
env: env(resolvDotConf("nameserver 10.0.0.1")),
wantLog: "dns: [rc=unknown ret=direct]",
want: "direct",
},
{
name: "network_manager",
env: env(
resolvDotConf(
"# Managed by NetworkManager",
"nameserver 10.0.0.1")),
wantLog: "dns: resolvedIsActuallyResolver error: resolv.conf doesn't point to systemd-resolved; points to [10.0.0.1]\n" +
"dns: [rc=nm resolved=not-in-use ret=direct]",
want: "direct",
},
{
name: "resolvconf_but_no_resolvconf_binary",
env: env(resolvDotConf("# Managed by resolvconf", "nameserver 10.0.0.1")),
wantLog: "dns: [rc=resolvconf resolvconf=no ret=direct]",
want: "direct",
},
{
name: "debian_resolvconf",
env: env(
resolvDotConf("# Managed by resolvconf", "nameserver 10.0.0.1"),
resolvconf("debian")),
wantLog: "dns: [rc=resolvconf resolvconf=debian ret=debian-resolvconf]",
want: "debian-resolvconf",
},
{
name: "openresolv",
env: env(
resolvDotConf("# Managed by resolvconf", "nameserver 10.0.0.1"),
resolvconf("openresolv")),
wantLog: "dns: [rc=resolvconf resolvconf=openresolv ret=openresolv]",
want: "openresolv",
},
{
name: "unknown_resolvconf_flavor",
env: env(
resolvDotConf("# Managed by resolvconf", "nameserver 10.0.0.1"),
resolvconf("daves-discount-resolvconf")),
wantLog: "[unexpected] got unknown flavor of resolvconf \"daves-discount-resolvconf\", falling back to direct manager\ndns: [rc=resolvconf resolvconf=daves-discount-resolvconf ret=direct]",
want: "direct",
},
{
name: "resolved_alone_without_ping",
env: env(resolvDotConf("# Managed by systemd-resolved", "nameserver 127.0.0.53")),
wantLog: "dns: ResolvConfMode error: dbus property not found\ndns: [rc=resolved resolved=file nm=no resolv-conf-mode=error ret=systemd-resolved]",
want: "systemd-resolved",
},
{
name: "resolved_alone_with_ping",
env: env(
resolvDotConf("# Managed by systemd-resolved", "nameserver 127.0.0.53"),
resolvedRunning()),
wantLog: "dns: [resolved-ping=yes rc=resolved resolved=file nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
name: "resolved_and_nsswitch_resolve",
env: env(
resolvDotConf("# Managed by systemd-resolved", "nameserver 1.1.1.1"),
resolvedRunning(),
nsswitchDotConf("hosts: files resolve [!UNAVAIL=return] dns"),
),
wantLog: "dns: [resolved-ping=yes rc=resolved resolved=nss nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
name: "resolved_and_nsswitch_dns",
env: env(
resolvDotConf("# Managed by systemd-resolved", "nameserver 1.1.1.1"),
resolvedRunning(),
nsswitchDotConf("hosts: files dns resolve [!UNAVAIL=return]"),
),
wantLog: "dns: resolvedIsActuallyResolver error: resolv.conf doesn't point to systemd-resolved; points to [1.1.1.1]\ndns: [resolved-ping=yes rc=resolved resolved=not-in-use ret=direct]",
want: "direct",
},
{
name: "resolved_and_nsswitch_none",
env: env(
resolvDotConf("# Managed by systemd-resolved", "nameserver 1.1.1.1"),
resolvedRunning(),
nsswitchDotConf("hosts:"),
),
wantLog: "dns: resolvedIsActuallyResolver error: resolv.conf doesn't point to systemd-resolved; points to [1.1.1.1]\ndns: [resolved-ping=yes rc=resolved resolved=not-in-use ret=direct]",
want: "direct",
},
{
name: "resolved_and_networkmanager_not_using_resolved",
env: env(
resolvDotConf("# Managed by systemd-resolved", "nameserver 127.0.0.53"),
resolvedRunning(),
nmRunning("1.2.3", false)),
wantLog: "dns: [resolved-ping=yes rc=resolved resolved=file nm=yes nm-resolved=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
name: "resolved_and_mid_2020_networkmanager",
env: env(
resolvDotConf("# Managed by systemd-resolved", "nameserver 127.0.0.53"),
resolvedRunning(),
nmRunning("1.26.2", true)),
wantLog: "dns: [resolved-ping=yes rc=resolved resolved=file nm=yes nm-resolved=yes nm-safe=yes ret=network-manager]",
want: "network-manager",
},
{
name: "resolved_and_2021_networkmanager",
env: env(
resolvDotConf("# Managed by systemd-resolved", "nameserver 127.0.0.53"),
resolvedRunning(),
nmRunning("1.27.0", true)),
wantLog: "dns: [resolved-ping=yes rc=resolved resolved=file nm=yes nm-resolved=yes nm-safe=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
name: "resolved_and_ancient_networkmanager",
env: env(
resolvDotConf("# Managed by systemd-resolved", "nameserver 127.0.0.53"),
resolvedRunning(),
nmRunning("1.22.0", true)),
wantLog: "dns: [resolved-ping=yes rc=resolved resolved=file nm=yes nm-resolved=yes nm-safe=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
// Regression tests for extreme corner cases below.
{
// One user reported a configuration whose comment string
// alleged that it was managed by systemd-resolved, but it
// was actually a completely static config file pointing
// elsewhere.
name: "allegedly_resolved_but_not_in_resolv.conf",
env: env(resolvDotConf("# Managed by systemd-resolved", "nameserver 10.0.0.1")),
wantLog: "dns: resolvedIsActuallyResolver error: resolv.conf doesn't point to systemd-resolved; points to [10.0.0.1]\n" +
"dns: [rc=resolved resolved=not-in-use ret=direct]",
want: "direct",
},
{
// We used to incorrectly decide that resolved wasn't in
// charge when handed this (admittedly weird and bugged)
// resolv.conf.
name: "resolved_with_duplicates_in_resolv.conf",
env: env(
resolvDotConf(
"# Managed by systemd-resolved",
"nameserver 127.0.0.53",
"nameserver 127.0.0.53"),
resolvedRunning()),
wantLog: "dns: [resolved-ping=yes rc=resolved resolved=file nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
// More than one user has had resolvconf write a config that points to
// systemd-resolved. We're better off using systemd-resolved.
// regression test for https://github.com/tailscale/tailscale/issues/3026
name: "allegedly_resolvconf_but_actually_systemd-resolved",
env: env(resolvDotConf(
"# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)",
"# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN",
"# 127.0.0.53 is the systemd-resolved stub resolver.",
"# run \"systemd-resolve --status\" to see details about the actual nameservers.",
"nameserver 127.0.0.53"),
resolvedRunning()),
wantLog: "dns: [resolved-ping=yes rc=resolved resolved=file nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
// More than one user has had resolvconf write a config that points to
// systemd-resolved. We're better off using systemd-resolved.
// and assuming that even if the ping doesn't show that env is correct
// regression test for https://github.com/tailscale/tailscale/issues/3026
name: "allegedly_resolvconf_but_actually_systemd-resolved_but_no_ping",
env: env(resolvDotConf(
"# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)",
"# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN",
"# 127.0.0.53 is the systemd-resolved stub resolver.",
"# run \"systemd-resolve --status\" to see details about the actual nameservers.",
"nameserver 127.0.0.53")),
wantLog: "dns: ResolvConfMode error: dbus property not found\ndns: [rc=resolved resolved=file nm=no resolv-conf-mode=error ret=systemd-resolved]",
want: "systemd-resolved",
},
{
// regression test for https://github.com/tailscale/tailscale/issues/3304
name: "networkmanager_but_pointing_at_systemd-resolved",
env: env(resolvDotConf(
"# Generated by NetworkManager",
"nameserver 127.0.0.53",
"options edns0 trust-ad"),
resolvedRunning(),
nmRunning("1.32.12", true)),
wantLog: "dns: [resolved-ping=yes rc=nm resolved=file nm-resolved=yes nm-safe=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
// regression test for https://github.com/tailscale/tailscale/issues/3304
name: "networkmanager_but_pointing_at_systemd-resolved_but_no_resolved_ping",
env: env(resolvDotConf(
"# Generated by NetworkManager",
"nameserver 127.0.0.53",
"options edns0 trust-ad"),
nmRunning("1.32.12", true)),
wantLog: "dns: ResolvConfMode error: dbus property not found\ndns: [rc=nm resolved=file nm-resolved=yes nm-safe=no resolv-conf-mode=error ret=systemd-resolved]",
want: "systemd-resolved",
},
{
// regression test for https://github.com/tailscale/tailscale/issues/3304
name: "networkmanager_but_pointing_at_systemd-resolved_and_safe_nm",
env: env(resolvDotConf(
"# Generated by NetworkManager",
"nameserver 127.0.0.53",
"options edns0 trust-ad"),
resolvedRunning(),
nmRunning("1.26.3", true)),
wantLog: "dns: [resolved-ping=yes rc=nm resolved=file nm-resolved=yes nm-safe=yes ret=network-manager]",
want: "network-manager",
},
{
// regression test for https://github.com/tailscale/tailscale/issues/3304
name: "networkmanager_but_pointing_at_systemd-resolved_and_no_networkmanager",
env: env(resolvDotConf(
"# Generated by NetworkManager",
"nameserver 127.0.0.53",
"options edns0 trust-ad"),
resolvedRunning()),
wantLog: "dns: [resolved-ping=yes rc=nm resolved=file nm-resolved=yes nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
// regression test for https://github.com/tailscale/tailscale/issues/3531
name: "networkmanager_but_systemd-resolved_with_search_domain",
env: env(resolvDotConf(
"# Generated by NetworkManager",
"search lan",
"nameserver 127.0.0.53"),
resolvedRunning()),
wantLog: "dns: [resolved-ping=yes rc=nm resolved=file nm-resolved=yes nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
// Make sure that we ping systemd-resolved to let it start up and write its resolv.conf
// before we read its file.
env: env(resolvedStartOnPingAndThen(
resolvDotConf("# Managed by systemd-resolved", "nameserver 127.0.0.53"),
resolvedDbusProperty(),
)),
wantLog: "dns: [resolved-ping=yes rc=resolved resolved=file nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
// regression test for https://github.com/tailscale/tailscale/issues/9687
name: "networkmanager_endeavouros",
env: env(resolvDotConf(
"# Generated by NetworkManager",
"search example.com localdomain",
"nameserver 10.0.0.1"),
nmRunning("1.44.2", false)),
wantLog: "dns: resolvedIsActuallyResolver error: resolv.conf doesn't point to systemd-resolved; points to [10.0.0.1]\n" +
"dns: [rc=nm resolved=not-in-use ret=direct]",
want: "direct",
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
var logBuf tstest.MemLogger
got, err := dnsMode(logBuf.Logf, nil, tt.env)
if err != nil {
t.Fatal(err)
}
if got != tt.want {
t.Errorf("got %s; want %s", got, tt.want)
}
if got := strings.TrimSpace(logBuf.String()); got != tt.wantLog {
t.Errorf("log output mismatch:\n got: %q\nwant: %q\n", got, tt.wantLog)
}
})
}
}
type memFS map[string]any // full path => string for regular files
func (m memFS) Stat(name string) (isRegular bool, err error) {
v, ok := m[name]
if !ok {
return false, fs.ErrNotExist
}
if _, ok := v.(string); ok {
return true, nil
}
return false, nil
}
func (m memFS) Rename(oldName, newName string) error { panic("TODO") }
func (m memFS) Remove(name string) error { panic("TODO") }
func (m memFS) ReadFile(name string) ([]byte, error) {
v, ok := m[name]
if !ok {
return nil, fs.ErrNotExist
}
if s, ok := v.(string); ok {
return []byte(s), nil
}
panic("TODO")
}
func (m memFS) Truncate(name string) error {
v, ok := m[name]
if !ok {
return fs.ErrNotExist
}
if s, ok := v.(string); ok {
m[name] = s[:0]
}
return nil
}
func (m memFS) WriteFile(name string, contents []byte, perm os.FileMode) error {
m[name] = string(contents)
return nil
}
type dbusService struct {
name, path string
hook func() // if non-nil, run on ping
}
type dbusProperty struct {
name, path string
iface, member string
hook func() (string, error) // what to return
}
type envBuilder struct {
fs memFS
dbus []dbusService
dbusProperties []dbusProperty
nmUsingResolved bool
nmVersion string
resolvconfStyle string
}
type envOption interface {
apply(*envBuilder)
}
type envOpt func(*envBuilder)
func (e envOpt) apply(b *envBuilder) {
e(b)
}
func env(opts ...envOption) newOSConfigEnv {
b := &envBuilder{
fs: memFS{},
}
for _, opt := range opts {
opt.apply(b)
}
return newOSConfigEnv{
fs: b.fs,
dbusPing: func(name, path string) error {
for _, svc := range b.dbus {
if svc.name == name && svc.path == path {
if svc.hook != nil {
svc.hook()
}
return nil
}
}
return errors.New("dbus service not found")
},
dbusReadString: func(name, path, iface, member string) (string, error) {
for _, svc := range b.dbusProperties {
if svc.name == name && svc.path == path && svc.iface == iface && svc.member == member {
return svc.hook()
}
}
return "", errors.New("dbus property not found")
},
nmIsUsingResolved: func() error {
if !b.nmUsingResolved {
return errors.New("networkmanager not using resolved")
}
return nil
},
nmVersionBetween: func(first, last string) (bool, error) {
outside := cmpver.Compare(b.nmVersion, first) < 0 || cmpver.Compare(b.nmVersion, last) > 0
return !outside, nil
},
resolvconfStyle: func() string { return b.resolvconfStyle },
}
}
func resolvDotConf(ss ...string) envOption {
return envOpt(func(b *envBuilder) {
b.fs["/etc/resolv.conf"] = strings.Join(ss, "\n")
})
}
func nsswitchDotConf(ss ...string) envOption {
return envOpt(func(b *envBuilder) {
b.fs["/etc/nsswitch.conf"] = strings.Join(ss, "\n")
})
}
// resolvedRunning returns an option that makes resolved reply to a dbusPing
// and the ResolvConfMode property.
func resolvedRunning() envOption {
return resolvedStartOnPingAndThen(resolvedDbusProperty())
}
// resolvedDbusProperty returns an option that responds to the ResolvConfMode
// property that resolved exposes.
func resolvedDbusProperty() envOption {
return setDbusProperty("org.freedesktop.resolve1", "/org/freedesktop/resolve1", "org.freedesktop.resolve1.Manager", "ResolvConfMode", "fortests")
}
// resolvedStartOnPingAndThen returns an option that makes resolved be
// active but not yet running. On a dbus ping, it then applies the
// provided options.
func resolvedStartOnPingAndThen(opts ...envOption) envOption {
return envOpt(func(b *envBuilder) {
b.dbus = append(b.dbus, dbusService{
name: "org.freedesktop.resolve1",
path: "/org/freedesktop/resolve1",
hook: func() {
for _, opt := range opts {
opt.apply(b)
}
},
})
})
}
func nmRunning(version string, usingResolved bool) envOption {
return envOpt(func(b *envBuilder) {
b.nmUsingResolved = usingResolved
b.nmVersion = version
b.dbus = append(b.dbus, dbusService{name: "org.freedesktop.NetworkManager", path: "/org/freedesktop/NetworkManager/DnsManager"})
})
}
func resolvconf(s string) envOption {
return envOpt(func(b *envBuilder) {
b.resolvconfStyle = s
})
}
func setDbusProperty(name, path, iface, member, value string) envOption {
return envOpt(func(b *envBuilder) {
b.dbusProperties = append(b.dbusProperties, dbusProperty{
name: name,
path: path,
iface: iface,
member: member,
hook: func() (string, error) {
return value, nil
},
})
})
}