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net/dns: exhaustively test DNS selection paths for linux.

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Signed-off-by: David Anderson <danderson@tailscale.com>
This commit is contained in:
David Anderson
2021-09-04 23:40:48 -07:00
parent c071bcda33
commit 10547d989d
4 changed files with 290 additions and 73 deletions
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219
net/dns/manager_linux_test.go
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@@ -6,29 +6,142 @@ package dns
import (
"bytes"
"errors"
"fmt"
"io/fs"
"os"
"strings"
"testing"
"tailscale.com/util/cmpver"
)
func TestLinuxNewOSConfigurator(t *testing.T) {
func TestLinuxDNSMode(t *testing.T) {
tests := []struct {
name string
env newOSConfigEnv
wantLog string
want string // reflect type string
want string
}{
{
name: "no_obvious_resolv.conf_owner",
env: newOSConfigEnv{
fs: memFS{
"/etc/resolv.conf": "nameserver 10.0.0.1\n",
},
resolvOwner: resolvOwner,
},
wantLog: "dns: [rc=unknown ret=dns.directManager]\n",
want: "dns.directManager",
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: [rc=nm 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_not_running",
env: env(resolvDotConf("# Managed by systemd-resolved", "nameserver 127.0.0.53")),
wantLog: "dns: [rc=resolved resolved=no ret=direct]",
want: "direct",
},
{
name: "resolved_alone",
env: env(
resolvDotConf("# Managed by systemd-resolved", "nameserver 127.0.0.53"),
resolvedRunning()),
wantLog: "dns: [rc=resolved nm=no ret=systemd-resolved]",
want: "systemd-resolved",
},
{
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: [rc=resolved nm=yes nm-resolved=no 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: [rc=resolved 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: [rc=resolved nm=yes nm-resolved=yes nm-safe=no 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: [rc=resolved nm=yes nm-resolved=yes nm-safe=no 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: [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: [rc=resolved nm=no ret=systemd-resolved]",
want: "systemd-resolved",
},
}
for _, tt := range tests {
@@ -38,15 +151,15 @@ func TestLinuxNewOSConfigurator(t *testing.T) {
fmt.Fprintf(&logBuf, format, a...)
logBuf.WriteByte('\n')
}
osc, err := newOSConfigurator(logf, "unused_if_name0", tt.env)
got, err := dnsMode(logf, tt.env)
if err != nil {
t.Fatal(err)
}
if got := fmt.Sprintf("%T", osc); got != tt.want {
if got != tt.want {
t.Errorf("got %s; want %s", got, tt.want)
}
if tt.wantLog != string(logBuf.Bytes()) {
t.Errorf("log output mismatch:\n got: %q\nwant: %q\n", logBuf.Bytes(), tt.wantLog)
if got := strings.TrimSpace(logBuf.String()); got != tt.wantLog {
t.Errorf("log output mismatch:\n got: %q\nwant: %q\n", got, tt.wantLog)
}
})
}
@@ -82,3 +195,79 @@ func (fs memFS) WriteFile(name string, contents []byte, perm os.FileMode) error
fs[name] = string(contents)
return nil
}
type envBuilder struct {
fs memFS
dbus []struct{ name, path string }
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 {
return nil
}
}
return errors.New("dbus service 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 resolvedRunning() envOption {
return envOpt(func(b *envBuilder) {
b.dbus = append(b.dbus, struct{ name, path string }{"org.freedesktop.resolve1", "/org/freedesktop/resolve1"})
})
}
func nmRunning(version string, usingResolved bool) envOption {
return envOpt(func(b *envBuilder) {
b.nmUsingResolved = usingResolved
b.nmVersion = version
b.dbus = append(b.dbus, struct{ name, path string }{"org.freedesktop.NetworkManager", "/org/freedesktop/NetworkManager/DnsManager"})
})
}
func resolvconf(s string) envOption {
return envOpt(func(b *envBuilder) {
b.resolvconfStyle = s
})
}