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unclean_shutdown_linux.go
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unclean_shutdown_linux.go
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//go:build !android
package dns
import (
"errors"
"fmt"
"io/fs"
"net/netip"
"os"
"path/filepath"
"strings"
log "github.com/sirupsen/logrus"
)
const (
fileUncleanShutdownResolvConfLocation = "/var/lib/netbird/resolv.conf"
fileUncleanShutdownManagerTypeLocation = "/var/lib/netbird/manager"
)
func CheckUncleanShutdown(wgIface string) error {
if _, err := os.Stat(fileUncleanShutdownResolvConfLocation); err != nil {
if errors.Is(err, fs.ErrNotExist) {
// no file -> clean shutdown
return nil
} else {
return fmt.Errorf("state: %w", err)
}
}
log.Warnf("detected unclean shutdown, file %s exists", fileUncleanShutdownResolvConfLocation)
managerData, err := os.ReadFile(fileUncleanShutdownManagerTypeLocation)
if err != nil {
return fmt.Errorf("read %s: %w", fileUncleanShutdownManagerTypeLocation, err)
}
managerFields := strings.Split(string(managerData), ",")
if len(managerFields) < 2 {
return errors.New("split manager data: insufficient number of fields")
}
osManagerTypeStr, dnsAddressStr := managerFields[0], managerFields[1]
dnsAddress, err := netip.ParseAddr(dnsAddressStr)
if err != nil {
return fmt.Errorf("parse dns address %s failed: %w", dnsAddressStr, err)
}
log.Warnf("restoring unclean shutdown dns settings via previously detected manager: %s", osManagerTypeStr)
// determine os manager type, so we can invoke the respective restore action
osManagerType, err := newOsManagerType(osManagerTypeStr)
if err != nil {
return fmt.Errorf("detect previous host manager: %w", err)
}
manager, err := newHostManagerFromType(wgIface, osManagerType)
if err != nil {
return fmt.Errorf("create previous host manager: %w", err)
}
if err := manager.restoreUncleanShutdownDNS(&dnsAddress); err != nil {
return fmt.Errorf("restore unclean shutdown backup: %w", err)
}
return nil
}
func createUncleanShutdownIndicator(sourcePath string, managerType osManagerType, dnsAddress string) error {
dir := filepath.Dir(fileUncleanShutdownResolvConfLocation)
if err := os.MkdirAll(dir, os.FileMode(0755)); err != nil {
return fmt.Errorf("create dir %s: %w", dir, err)
}
if err := copyFile(sourcePath, fileUncleanShutdownResolvConfLocation); err != nil {
return fmt.Errorf("create %s: %w", sourcePath, err)
}
managerData := fmt.Sprintf("%s,%s", managerType, dnsAddress)
if err := os.WriteFile(fileUncleanShutdownManagerTypeLocation, []byte(managerData), 0644); err != nil { //nolint:gosec
return fmt.Errorf("create %s: %w", fileUncleanShutdownManagerTypeLocation, err)
}
return nil
}
func removeUncleanShutdownIndicator() error {
if err := os.Remove(fileUncleanShutdownResolvConfLocation); err != nil && !errors.Is(err, fs.ErrNotExist) {
return fmt.Errorf("remove %s: %w", fileUncleanShutdownResolvConfLocation, err)
}
if err := os.Remove(fileUncleanShutdownManagerTypeLocation); err != nil && !errors.Is(err, fs.ErrNotExist) {
return fmt.Errorf("remove %s: %w", fileUncleanShutdownManagerTypeLocation, err)
}
return nil
}