/
ddnsman.go
123 lines (110 loc) · 3.24 KB
/
ddnsman.go
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package ddnsman
import (
"context"
"fmt"
"log/slog"
"time"
"github.com/containrrr/shoutrrr/pkg/router"
externalip "github.com/glendc/go-external-ip"
"github.com/libdns/libdns"
"golang.org/x/sync/errgroup"
)
type Updater struct {
config *Configuration
consensus *externalip.Consensus
sender *router.ServiceRouter
currentIP string // strings are comparable.
}
func New(config *Configuration) (*Updater, error) {
// Use consensus to acquire external IP.
consensus := externalip.DefaultConsensus(nil, nil)
consensus.UseIPProtocol(4)
// Use shoutrrr to send notifications.
urls, err := config.shoutrrrURLs()
if err != nil {
return nil, err
}
sender, err := router.New(nil, urls...)
if err != nil {
return nil, fmt.Errorf("create shoutrrr router: %w", err)
}
return &Updater{
config: config,
consensus: consensus,
sender: sender,
}, nil
}
func (u *Updater) Start(ctx context.Context) error {
slog.Info("start DDNS updater", slog.Duration("interval", u.config.Interval))
u.sender.Send(fmt.Sprintf("Watching records every %s", u.config.Interval), nil)
if err := u.process(ctx); err != nil {
return err
}
ticker := time.NewTicker(time.Duration(u.config.Interval))
defer ticker.Stop()
for {
select {
case <-ticker.C:
if err := u.process(ctx); err != nil {
u.sender.Send(fmt.Sprintf("Error occured: `%s`. Shutting down.", err), nil)
return err
}
case <-ctx.Done():
u.sender.Send("Shutting down.", nil)
slog.Info("shutting down")
return nil
}
}
}
func (u *Updater) process(ctx context.Context) error {
externalIP, err := u.consensus.ExternalIP()
if err != nil {
return fmt.Errorf("unable to fetch external ip: %w", err)
}
if externalIP.String() == u.currentIP {
// Skip check if external IP hasn't changed.
return nil
}
wg, ctx := errgroup.WithContext(ctx)
for _, setting := range u.config.Settings {
setting := setting
wg.Go(func() error {
return u.checkRecord(ctx, externalIP.String(), setting)
})
}
if err := wg.Wait(); err != nil {
return err
}
u.currentIP = externalIP.String()
return nil
}
func (u *Updater) checkRecord(ctx context.Context, externalIP string, setting Setting) error {
logger := slog.Default().With("provider", setting.Provider.Name)
providerRecords, err := setting.provider.GetRecords(ctx, setting.Domain)
if err != nil {
return fmt.Errorf("getting records for zone %q: %w", setting.Domain, err)
}
var records []libdns.Record
for _, providerRecord := range providerRecords {
for _, targetRecord := range setting.Records {
providerName := libdns.RelativeName(providerRecord.Name, setting.Domain)
if providerName == targetRecord && providerRecord.Type == "A" && providerRecord.Value != externalIP {
logger.Info("IP address mismatch",
slog.String("record", providerName),
slog.String("record IP", providerRecord.Value),
slog.String("external IP", externalIP),
)
providerRecord.Value = externalIP
records = append(records, providerRecord)
}
}
}
if len(records) == 0 {
return nil
}
u.sender.Send(fmt.Sprintf("Setting IP `%s` for zone `%s`.", externalIP, setting.Domain), nil)
if _, err := setting.provider.SetRecords(ctx, setting.Domain, records); err != nil {
return fmt.Errorf("setting records: %w", err)
}
return nil
}