TheArchive/tailscale
1
0
Fork 0
mirror of https://github.com/tailscale/tailscale.git synced 2024-11-29 04:55:31 +00:00
Code Issues Packages Projects Releases Wiki Activity

net/dns: print systemd-resolved ResolvConfMode

Browse Source 
The ResolvConfMode property is documented to return how systemd-resolved
is currently managing /etc/resolv.conf. Include that information in the
debug line, when available, to assist in debugging DNS issues.

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I1ae3a257df1d318d0193a8c7f135c458ec45093e
This commit is contained in:
Andrew Dunham 2022-10-14 20:25:22 +02:00
parent 223126fe5b
commit e966f024b0
2 changed files with 100 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

48
net/dns/manager_linux.go
View File

@ -31,6 +31,7 @@ func NewOSConfigurator(logf logger.Logf, interfaceName string) (ret OSConfigurat
env := newOSConfigEnv{
fs: directFS{},
dbusPing: dbusPing,
dbusReadString: dbusReadString,
nmIsUsingResolved: nmIsUsingResolved,
nmVersionBetween: nmVersionBetween,
resolvconfStyle: resolvconfStyle,
@ -60,6 +61,7 @@ func NewOSConfigurator(logf logger.Logf, interfaceName string) (ret OSConfigurat
type newOSConfigEnv struct {
fs wholeFileFS
dbusPing func(string, string) error
dbusReadString func(string, string, string, string) (string, error)
nmIsUsingResolved func() error
nmVersionBetween func(v1, v2 string) (safe bool, err error)
resolvconfStyle func() string
@ -78,6 +80,25 @@ func dnsMode(logf logger.Logf, env newOSConfigEnv) (ret string, err error) {
logf("dns: %v", debug)
}()
// In all cases that we detect systemd-resolved, try asking it what it
// thinks the current resolv.conf mode is so we can add it to our logs.
defer func() {
if ret != "systemd-resolved" {
return
}
// Try to ask systemd-resolved what it thinks the current
// status of resolv.conf is. This is documented at:
// https://www.freedesktop.org/software/systemd/man/org.freedesktop.resolve1.html
mode, err := env.dbusReadString("org.freedesktop.resolve1", "/org/freedesktop/resolve1", "org.freedesktop.resolve1.Manager", "ResolvConfMode")
if err != nil {
logf("dns: ResolvConfMode error: %v", err)
dbg("resolv-conf-mode", "error")
} else {
dbg("resolv-conf-mode", mode)
}
}()
// Before we read /etc/resolv.conf (which might be in a broken
// or symlink-dangling state), try to ping the D-Bus service
// for systemd-resolved. If it's active on the machine, this
@ -102,6 +123,7 @@ func dnsMode(logf logger.Logf, env newOSConfigEnv) (ret string, err error) {
switch resolvOwner(bs) {
case "systemd-resolved":
dbg("rc", "resolved")
// Some systems, for reasons known only to them, have a
// resolv.conf that has the word "systemd-resolved" in its
// header, but doesn't actually point to resolved. We mustn't
@ -327,3 +349,29 @@ func dbusPing(name, objectPath string) error {
call := obj.CallWithContext(ctx, "org.freedesktop.DBus.Peer.Ping", 0)
return call.Err
}
// dbusReadString reads a string property from the provided name and object
// path. property must be in "interface.member" notation.
func dbusReadString(name, objectPath, iface, member string) (string, error) {
conn, err := dbus.SystemBus()
if err != nil {
// DBus probably not running.
return "", err
}
ctx, cancel := context.WithTimeout(context.Background(), time.Second)
defer cancel()
obj := conn.Object(name, dbus.ObjectPath(objectPath))
var result dbus.Variant
err = obj.CallWithContext(ctx, "org.freedesktop.DBus.Properties.Get", 0, iface, member).Store(&result)
if err != nil {
return "", err
}
if s, ok := result.Value().(string); ok {
return s, nil
}
return result.String(), nil
}

67
net/dns/manager_linux_test.go
View File

@ -71,7 +71,7 @@ func TestLinuxDNSMode(t *testing.T) {
{
name: "resolved_alone_without_ping",
env: env(resolvDotConf("# Managed by systemd-resolved", "nameserver 127.0.0.53")),
wantLog: "dns: [rc=resolved nm=no ret=systemd-resolved]",
wantLog: "dns: ResolvConfMode error: dbus property not found\ndns: [rc=resolved nm=no resolv-conf-mode=error ret=systemd-resolved]",
want: "systemd-resolved",
},
{
@ -79,7 +79,7 @@ func TestLinuxDNSMode(t *testing.T) {
env: env(
resolvDotConf("# Managed by systemd-resolved", "nameserver 127.0.0.53"),
resolvedRunning()),
wantLog: "dns: [resolved-ping=yes rc=resolved nm=no ret=systemd-resolved]",
wantLog: "dns: [resolved-ping=yes rc=resolved nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
@ -88,7 +88,7 @@ func TestLinuxDNSMode(t *testing.T) {
resolvDotConf("# Managed by systemd-resolved", "nameserver 127.0.0.53"),
resolvedRunning(),
nmRunning("1.2.3", false)),
wantLog: "dns: [resolved-ping=yes rc=resolved nm=yes nm-resolved=no ret=systemd-resolved]",
wantLog: "dns: [resolved-ping=yes rc=resolved nm=yes nm-resolved=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
@ -106,7 +106,7 @@ func TestLinuxDNSMode(t *testing.T) {
resolvDotConf("# Managed by systemd-resolved", "nameserver 127.0.0.53"),
resolvedRunning(),
nmRunning("1.27.0", true)),
wantLog: "dns: [resolved-ping=yes rc=resolved nm=yes nm-resolved=yes nm-safe=no ret=systemd-resolved]",
wantLog: "dns: [resolved-ping=yes rc=resolved nm=yes nm-resolved=yes nm-safe=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
@ -115,7 +115,7 @@ func TestLinuxDNSMode(t *testing.T) {
resolvDotConf("# Managed by systemd-resolved", "nameserver 127.0.0.53"),
resolvedRunning(),
nmRunning("1.22.0", true)),
wantLog: "dns: [resolved-ping=yes rc=resolved nm=yes nm-resolved=yes nm-safe=no ret=systemd-resolved]",
wantLog: "dns: [resolved-ping=yes rc=resolved 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.
@ -141,7 +141,7 @@ func TestLinuxDNSMode(t *testing.T) {
"nameserver 127.0.0.53",
"nameserver 127.0.0.53"),
resolvedRunning()),
wantLog: "dns: [resolved-ping=yes rc=resolved nm=no ret=systemd-resolved]",
wantLog: "dns: [resolved-ping=yes rc=resolved nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
@ -156,7 +156,7 @@ func TestLinuxDNSMode(t *testing.T) {
"# run \"systemd-resolve --status\" to see details about the actual nameservers.",
"nameserver 127.0.0.53"),
resolvedRunning()),
wantLog: "dns: [resolved-ping=yes rc=resolved nm=no ret=systemd-resolved]",
wantLog: "dns: [resolved-ping=yes rc=resolved nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
@ -171,7 +171,7 @@ func TestLinuxDNSMode(t *testing.T) {
"# 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: [rc=resolved nm=no ret=systemd-resolved]",
wantLog: "dns: ResolvConfMode error: dbus property not found\ndns: [rc=resolved nm=no resolv-conf-mode=error ret=systemd-resolved]",
want: "systemd-resolved",
},
{
@ -183,7 +183,7 @@ func TestLinuxDNSMode(t *testing.T) {
"options edns0 trust-ad"),
resolvedRunning(),
nmRunning("1.32.12", true)),
wantLog: "dns: [resolved-ping=yes rc=nm nm-resolved=yes nm-safe=no ret=systemd-resolved]",
wantLog: "dns: [resolved-ping=yes rc=nm nm-resolved=yes nm-safe=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
@ -194,7 +194,7 @@ func TestLinuxDNSMode(t *testing.T) {
"nameserver 127.0.0.53",
"options edns0 trust-ad"),
nmRunning("1.32.12", true)),
wantLog: "dns: [rc=nm nm-resolved=yes nm-safe=no ret=systemd-resolved]",
wantLog: "dns: ResolvConfMode error: dbus property not found\ndns: [rc=nm nm-resolved=yes nm-safe=no resolv-conf-mode=error ret=systemd-resolved]",
want: "systemd-resolved",
},
{
@ -217,7 +217,7 @@ func TestLinuxDNSMode(t *testing.T) {
"nameserver 127.0.0.53",
"options edns0 trust-ad"),
resolvedRunning()),
wantLog: "dns: [resolved-ping=yes rc=nm nm-resolved=yes nm=no ret=systemd-resolved]",
wantLog: "dns: [resolved-ping=yes rc=nm nm-resolved=yes nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
@ -228,7 +228,7 @@ func TestLinuxDNSMode(t *testing.T) {
"search lan",
"nameserver 127.0.0.53"),
resolvedRunning()),
wantLog: "dns: [resolved-ping=yes rc=nm nm-resolved=yes nm=no ret=systemd-resolved]",
wantLog: "dns: [resolved-ping=yes rc=nm nm-resolved=yes nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
@ -236,8 +236,9 @@ func TestLinuxDNSMode(t *testing.T) {
// 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 nm=no ret=systemd-resolved]",
wantLog: "dns: [resolved-ping=yes rc=resolved nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
}
@ -306,9 +307,16 @@ type dbusService struct {
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
@ -345,6 +353,14 @@ func env(opts ...envOption) newOSConfigEnv {
}
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")
@ -365,9 +381,16 @@ func resolvDotConf(ss ...string) envOption {
})
}
// resolvedRunning returns an option that makes resolved reply to a dbusPing.
// resolvedRunning returns an option that makes resolved reply to a dbusPing
// and the ResolvConfMode property.
func resolvedRunning() envOption {
return resolvedStartOnPingAndThen( /* nothing */ )
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
@ -400,3 +423,17 @@ func resolvconf(s string) envOption {
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
},
})
})
}