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Restore dns on unclean shutdown (#1494)

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This commit is contained in:
Viktor Liu
2024-01-30 09:58:56 +01:00
committed by GitHub
parent 9c56f74235
commit 846d486366
29 changed files with 660 additions and 143 deletions
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60
client/internal/dns/systemd_linux.go
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@@ -4,6 +4,7 @@ package dns
import (
"context"
"errors"
"fmt"
"net"
"net/netip"
@@ -30,6 +31,8 @@ const (
systemdDbusSetDefaultRouteMethodSuffix = systemdDbusLinkInterface + ".SetDefaultRoute"
systemdDbusSetDomainsMethodSuffix = systemdDbusLinkInterface + ".SetDomains"
systemdDbusResolvConfModeForeign = "foreign"
dbusErrorUnknownObject = "org.freedesktop.DBus.Error.UnknownObject"
)
type systemdDbusConfigurator struct {
@@ -52,22 +55,22 @@ type systemdDbusLinkDomainsInput struct {
MatchOnly bool
}
func newSystemdDbusConfigurator(wgInterface WGIface) (hostManager, error) {
iface, err := net.InterfaceByName(wgInterface.Name())
func newSystemdDbusConfigurator(wgInterface string) (hostManager, error) {
iface, err := net.InterfaceByName(wgInterface)
if err != nil {
return nil, err
return nil, fmt.Errorf("get interface: %w", err)
}
obj, closeConn, err := getDbusObject(systemdResolvedDest, systemdDbusObjectNode)
if err != nil {
return nil, err
return nil, fmt.Errorf("get dbus resolved dest: %w", err)
}
defer closeConn()
var s string
err = obj.Call(systemdDbusGetLinkMethod, dbusDefaultFlag, iface.Index).Store(&s)
if err != nil {
return nil, err
return nil, fmt.Errorf("get dbus link method: %w", err)
}
log.Debugf("got dbus Link interface: %s from net interface %s and index %d", s, iface.Name, iface.Index)
@@ -84,7 +87,7 @@ func (s *systemdDbusConfigurator) supportCustomPort() bool {
func (s *systemdDbusConfigurator) applyDNSConfig(config HostDNSConfig) error {
parsedIP, err := netip.ParseAddr(config.ServerIP)
if err != nil {
return fmt.Errorf("unable to parse ip address, error: %s", err)
return fmt.Errorf("unable to parse ip address, error: %w", err)
}
ipAs4 := parsedIP.As4()
defaultLinkInput := systemdDbusDNSInput{
@@ -93,7 +96,7 @@ func (s *systemdDbusConfigurator) applyDNSConfig(config HostDNSConfig) error {
}
err = s.callLinkMethod(systemdDbusSetDNSMethodSuffix, []systemdDbusDNSInput{defaultLinkInput})
if err != nil {
return fmt.Errorf("setting the interface DNS server %s:%d failed with error: %s", config.ServerIP, config.ServerPort, err)
return fmt.Errorf("setting the interface DNS server %s:%d failed with error: %w", config.ServerIP, config.ServerPort, err)
}
var (
@@ -121,7 +124,7 @@ func (s *systemdDbusConfigurator) applyDNSConfig(config HostDNSConfig) error {
log.Infof("configured %s:%d as main DNS forwarder for this peer", config.ServerIP, config.ServerPort)
err = s.callLinkMethod(systemdDbusSetDefaultRouteMethodSuffix, true)
if err != nil {
return fmt.Errorf("setting link as default dns router, failed with error: %s", err)
return fmt.Errorf("setting link as default dns router, failed with error: %w", err)
}
domainsInput = append(domainsInput, systemdDbusLinkDomainsInput{
Domain: nbdns.RootZone,
@@ -132,6 +135,12 @@ func (s *systemdDbusConfigurator) applyDNSConfig(config HostDNSConfig) error {
log.Infof("removing %s:%d as main DNS forwarder for this peer", config.ServerIP, config.ServerPort)
}
// create a backup for unclean shutdown detection before adding domains, as these might end up in the resolv.conf file.
// The file content itself is not important for systemd restoration
if err := createUncleanShutdownIndicator(defaultResolvConfPath, systemdManager, parsedIP.String()); err != nil {
log.Errorf("failed to create unclean shutdown resolv.conf backup: %s", err)
}
log.Infof("adding %d search domains and %d match domains. Search list: %s , Match list: %s", len(searchDomains), len(matchDomains), searchDomains, matchDomains)
err = s.setDomainsForInterface(domainsInput)
if err != nil {
@@ -143,7 +152,7 @@ func (s *systemdDbusConfigurator) applyDNSConfig(config HostDNSConfig) error {
func (s *systemdDbusConfigurator) setDomainsForInterface(domainsInput []systemdDbusLinkDomainsInput) error {
err := s.callLinkMethod(systemdDbusSetDomainsMethodSuffix, domainsInput)
if err != nil {
return fmt.Errorf("setting domains configuration failed with error: %s", err)
return fmt.Errorf("setting domains configuration failed with error: %w", err)
}
return s.flushCaches()
}
@@ -153,17 +162,29 @@ func (s *systemdDbusConfigurator) restoreHostDNS() error {
if !isDbusListenerRunning(systemdResolvedDest, s.dbusLinkObject) {
return nil
}
// this call is required for DNS cleanup, even if it fails
err := s.callLinkMethod(systemdDbusRevertMethodSuffix, nil)
if err != nil {
return fmt.Errorf("unable to revert link configuration, got error: %s", err)
var dbusErr dbus.Error
if errors.As(err, &dbusErr) && dbusErr.Name == dbusErrorUnknownObject {
// interface is gone already
return nil
}
return fmt.Errorf("unable to revert link configuration, got error: %w", err)
}
if err := removeUncleanShutdownIndicator(); err != nil {
log.Errorf("failed to remove unclean shutdown resolv.conf backup: %s", err)
}
return s.flushCaches()
}
func (s *systemdDbusConfigurator) flushCaches() error {
obj, closeConn, err := getDbusObject(systemdResolvedDest, systemdDbusObjectNode)
if err != nil {
return fmt.Errorf("got error while attempting to retrieve the object %s, err: %s", systemdDbusObjectNode, err)
return fmt.Errorf("attempting to retrieve the object %s, err: %w", systemdDbusObjectNode, err)
}
defer closeConn()
ctx, cancel := context.WithTimeout(context.TODO(), 5*time.Second)
@@ -171,7 +192,7 @@ func (s *systemdDbusConfigurator) flushCaches() error {
err = obj.CallWithContext(ctx, systemdDbusFlushCachesMethod, dbusDefaultFlag).Store()
if err != nil {
return fmt.Errorf("got error while calling the FlushCaches method with context, err: %s", err)
return fmt.Errorf("calling the FlushCaches method with context, err: %w", err)
}
return nil
@@ -180,7 +201,7 @@ func (s *systemdDbusConfigurator) flushCaches() error {
func (s *systemdDbusConfigurator) callLinkMethod(method string, value any) error {
obj, closeConn, err := getDbusObject(systemdResolvedDest, s.dbusLinkObject)
if err != nil {
return fmt.Errorf("got error while attempting to retrieve the object, err: %s", err)
return fmt.Errorf("attempting to retrieve the object, err: %w", err)
}
defer closeConn()
@@ -194,22 +215,29 @@ func (s *systemdDbusConfigurator) callLinkMethod(method string, value any) error
}
if err != nil {
return fmt.Errorf("got error while calling command with context, err: %s", err)
return fmt.Errorf("calling command with context, err: %w", err)
}
return nil
}
func (s *systemdDbusConfigurator) restoreUncleanShutdownDNS(*netip.Addr) error {
if err := s.restoreHostDNS(); err != nil {
return fmt.Errorf("restoring dns via systemd: %w", err)
}
return nil
}
func getSystemdDbusProperty(property string, store any) error {
obj, closeConn, err := getDbusObject(systemdResolvedDest, systemdDbusObjectNode)
if err != nil {
return fmt.Errorf("got error while attempting to retrieve the systemd dns manager object, error: %s", err)
return fmt.Errorf("attempting to retrieve the systemd dns manager object, error: %w", err)
}
defer closeConn()
v, e := obj.GetProperty(property)
if e != nil {
return fmt.Errorf("got an error getting property %s: %v", property, e)
return fmt.Errorf("getting property %s: %w", property, e)
}
return v.Store(store)