336 lines
8.2 KiB
Go
336 lines
8.2 KiB
Go
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package daemon
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import (
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"context"
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"fmt"
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"net"
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"os"
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"os/signal"
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"regexp"
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"strings"
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"sync"
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"syscall"
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"time"
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"git.cryptic.systems/volker.raschek/dyndns-client/pkg/types"
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"git.cryptic.systems/volker.raschek/dyndns-client/pkg/updater"
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"github.com/asaskevich/govalidator"
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log "github.com/sirupsen/logrus"
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"github.com/vishvananda/netlink"
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)
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func Start(cnf *types.Config) {
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addrUpdates := make(chan netlink.AddrUpdate, 1)
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done := make(chan struct{}, 1)
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err := netlink.AddrSubscribeWithOptions(addrUpdates, done, netlink.AddrSubscribeOptions{
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ListExisting: true,
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})
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if err != nil {
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log.Fatalf("failed to subscribe netlink notifications from kernel: %v", err.Error())
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}
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interuptChannel := make(chan os.Signal, 1)
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signal.Notify(interuptChannel, syscall.SIGINT, syscall.SIGTERM)
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ctx := context.Background()
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daemonCtx, cancle := context.WithCancel(ctx)
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defer cancle()
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updaters, err := getUpdaterForEachZone(cnf)
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if err != nil {
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log.Fatalf("%v", err.Error())
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}
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if err := pruneRecords(daemonCtx, updaters, cnf.Zones); err != nil {
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log.Fatalf("%v", err.Error())
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}
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for {
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interfaces, err := netlink.LinkList()
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if err != nil {
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log.Fatal("%v", err.Error())
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}
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select {
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case update := <-addrUpdates:
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interfaceLogger := log.WithFields(log.Fields{
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"ip": update.LinkAddress.IP.String(),
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})
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// search interface by index
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iface, err := searchInterfaceByIndex(update.LinkIndex, interfaces)
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if err != nil {
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log.Errorf("%v", err.Error())
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continue
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}
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interfaceLogger = interfaceLogger.WithField("device", iface.Attrs().Name)
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var recordType string
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switch {
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case govalidator.IsIPv4(strings.TrimRight(update.LinkAddress.IP.String(), "/")):
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recordType = "A"
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case govalidator.IsIPv6(strings.TrimRight(update.LinkAddress.IP.String(), "/")):
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recordType = "AAAA"
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default:
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interfaceLogger.Error("failed to detect record type")
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continue
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}
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interfaceLogger = interfaceLogger.WithField("rr", recordType)
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interfaceLogger.Debug("receive kernel notification for interface")
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// filter out not configured interfaces
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if !matchInterfaces(iface.Attrs().Name, cnf.Ifaces) {
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interfaceLogger.Warn("interface is not part of the allowed interface list")
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continue
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}
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// filter out notification for a bad interface ip address, for example link-local-addresses
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if update.LinkAddress.IP.IsLoopback() || strings.HasPrefix(update.LinkAddress.IP.String(), "fe80") {
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interfaceLogger.Warn("interface is a loopback device or part of a loopback network")
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continue
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}
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// decide if trigger a add or delete event
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if update.NewAddr {
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err = addIPRecords(daemonCtx, interfaceLogger, updaters, cnf.Zones, recordType, update.LinkAddress.IP)
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if err != nil {
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interfaceLogger.Error(err.Error())
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}
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} else {
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err = removeIPRecords(daemonCtx, interfaceLogger, updaters, cnf.Zones, recordType, update.LinkAddress.IP)
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if err != nil {
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interfaceLogger.Error(err.Error())
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}
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}
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case killSignal := <-interuptChannel:
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log.Debugf("got signal: %v", killSignal)
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log.Debugf("daemon was killed by: %v", killSignal)
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return
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}
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}
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}
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func getUpdaterForEachZone(config *types.Config) (map[string]updater.Updater, error) {
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updaterCollection := make(map[string]updater.Updater)
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for zoneName, zone := range config.Zones {
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nsUpdater, err := updater.NewNSUpdate(zone.DNSServer, config.TSIGKeys[zone.TSIGKeyName])
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if err != nil {
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return nil, err
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}
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updaterCollection[zoneName] = nsUpdater
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}
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return updaterCollection, nil
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}
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func matchInterfaces(iface string, ifaces []string) bool {
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for _, i := range ifaces {
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if i == iface {
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return true
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}
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}
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return false
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}
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func searchInterfaceByIndex(index int, interfaces []netlink.Link) (netlink.Link, error) {
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for _, iface := range interfaces {
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if iface.Attrs().Index == index {
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return iface, nil
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}
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}
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return nil, fmt.Errorf("can not find interface by index %v", index)
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}
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func addIPRecords(ctx context.Context, logEntry *log.Entry, updaters map[string]updater.Updater, zones map[string]*types.Zone, recordType string, ip net.IP) error {
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var (
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errorChannel = make(chan error, len(zones))
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wg = new(sync.WaitGroup)
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)
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hostname, err := os.Hostname()
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if err != nil {
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return fmt.Errorf("failed to get host name from kernel: %w", err)
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}
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hostname = strings.ToLower(hostname)
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if !verifyHostname(hostname) {
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return fmt.Errorf("host name not valid: %w", err)
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}
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for zoneName := range zones {
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wg.Add(1)
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go func(ctx context.Context, zoneName string, hostname string, recordType string, ip net.IP, wg *sync.WaitGroup) {
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zoneLogger := logEntry.WithFields(log.Fields{
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"zone": zoneName,
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"hostname": hostname,
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})
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defer wg.Done()
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pruneRecordCtx, cancle := context.WithTimeout(ctx, time.Second*15)
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defer cancle()
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fqdn := fmt.Sprintf("%v.%v", hostname, zoneName)
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err := updaters[zoneName].AddRecord(pruneRecordCtx, fqdn, 60, recordType, ip.String())
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if err != nil {
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errorChannel <- fmt.Errorf("failed to remove record type %v for %v: %v", recordType, fqdn, err.Error())
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return
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}
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zoneLogger.Info("dns-record successfully updated")
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}(ctx, zoneName, hostname, recordType, ip, wg)
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}
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wg.Wait()
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close(errorChannel)
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for err := range errorChannel {
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if err != nil {
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return err
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}
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}
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return nil
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}
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func pruneRecords(ctx context.Context, updaters map[string]updater.Updater, zones map[string]*types.Zone) error {
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var (
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errorChannel = make(chan error, len(zones))
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wg = new(sync.WaitGroup)
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)
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hostname, err := os.Hostname()
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if err != nil {
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return fmt.Errorf("failed to get host name from kernel: %w", err)
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}
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hostname = strings.ToLower(hostname)
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if !verifyHostname(hostname) {
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return fmt.Errorf("host name not valid: %w", err)
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}
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for zoneName := range zones {
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wg.Add(1)
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go func(zoneName string, hostname string, errorChannel chan<- error, wg *sync.WaitGroup) {
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defer wg.Done()
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pruneRecordCtx, cancle := context.WithTimeout(ctx, time.Second*15)
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defer cancle()
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fqdn := fmt.Sprintf("%v.%v", hostname, zoneName)
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err := updaters[zoneName].PruneRecords(pruneRecordCtx, fqdn)
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if err != nil {
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errorChannel <- fmt.Errorf("failed to prune %v: %v", fqdn, err)
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return
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}
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}(zoneName, hostname, errorChannel, wg)
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}
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wg.Wait()
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close(errorChannel)
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for err := range errorChannel {
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if err != nil {
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return err
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}
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}
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return nil
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}
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func removeIPRecords(ctx context.Context, logEntry *log.Entry, updaters map[string]updater.Updater, zones map[string]*types.Zone, recordType string, ip net.IP) error {
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var (
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errorChannel = make(chan error, len(zones))
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wg = new(sync.WaitGroup)
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)
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hostname, err := os.Hostname()
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if err != nil {
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return fmt.Errorf("failed to get host name from kernel: %w", err)
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}
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hostname = strings.ToLower(hostname)
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if !verifyHostname(hostname) {
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return fmt.Errorf("host name not valid: %w", err)
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}
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for zoneName := range zones {
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wg.Add(1)
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go func(ctx context.Context, zoneName string, hostname string, recordType string, wg *sync.WaitGroup) {
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defer wg.Done()
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zoneLogger := logEntry.WithFields(log.Fields{
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"zone": zoneName,
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"hostname": hostname,
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})
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pruneRecordCtx, cancle := context.WithTimeout(ctx, time.Second*15)
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defer cancle()
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fqdn := fmt.Sprintf("%v.%v", hostname, zoneName)
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err := updaters[zoneName].DeleteRecord(pruneRecordCtx, fqdn, recordType)
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if err != nil {
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errorChannel <- fmt.Errorf("failed to remove record type %v for %v: %v", recordType, fqdn, err.Error())
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return
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}
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zoneLogger.Info("dns-record successfully removed")
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}(ctx, zoneName, hostname, recordType, wg)
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}
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wg.Wait()
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close(errorChannel)
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for err := range errorChannel {
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if err != nil {
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return err
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}
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}
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return nil
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}
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// verifyHostname returns a boolean if the hostname id valid. The hostname does
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// not contains any dot or local, localhost, localdomain.
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func verifyHostname(hostname string) bool {
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if !validHostname.MatchString(hostname) {
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return false
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}
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hostnames := []string{
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"local",
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"localhost",
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"localdomain",
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"orbisos",
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}
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for i := range hostnames {
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if hostnames[i] == hostname {
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return false
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}
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}
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return true
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}
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var (
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validHostname = regexp.MustCompile(`^[a-zA-Z0-9]+([\-][a-zA-Z0-9]+)*$`)
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)
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