fix(update): fetch IPv6 AAAA records and not only IPv4

internal/update/service.go

@@ -3,8 +3,10 @@ package update
 import (
 	"context"
 	"fmt"
+	"net"
 	"net/netip"
 	"strconv"
+	"strings"
 	"time"
 
 	"github.com/qdm12/ddns-updater/internal/constants"
@@ -34,7 +36,8 @@ type Service struct {
 
 func NewService(db Database, updater UpdaterInterface, ipGetter PublicIPFetcher,
 	period time.Duration, cooldown time.Duration, logger Logger, resolver LookupIPer,
-	timeNow func() time.Time, hioClient HealthchecksIOClient) *Service {
+	timeNow func() time.Time, hioClient HealthchecksIOClient,
+) *Service {
 	return &Service{
 		period:      period,
 		db:          db,
@@ -50,37 +53,59 @@ func NewService(db Database, updater UpdaterInterface, ipGetter PublicIPFetcher,
 	}
 }
 
-func (s *Service) lookupIPsResilient(ctx context.Context, hostname string, tries int) (
-	ipv4, ipv6 []netip.Addr, err error) {
-	for i := 0; i < tries; i++ {
-		ipv4, ipv6, err = s.lookupIPs(ctx, hostname)
-		if err == nil {
-			return ipv4, ipv6, nil
+func (s *Service) lookupIPsResilient(ctx context.Context, hostname string, tries uint) (
+	ipv4, ipv6 []netip.Addr, err error,
+) {
+	type result struct {
+		network string
+		ips     []net.IP
+		err     error
+	}
+	results := make(chan result)
+	networks := []string{"ip4", "ip6"}
+	lookupCtx, cancel := context.WithCancel(ctx)
+	for _, network := range networks {
+		go func(ctx context.Context, network string, results chan<- result) {
+			for range tries {
+				ips, err := s.resolver.LookupIP(ctx, network, hostname)
+				if err != nil {
+					if strings.HasSuffix(err.Error(), "no such host") {
+						results <- result{network: network} // no IP address for this network
+						return
+					}
+					continue // retry
+				}
+				results <- result{network: network, ips: ips, err: err}
+				return
+			}
+		}(lookupCtx, network, results)
+	}
+
+	for range networks {
+		result := <-results
+		if result.err != nil {
+			if err == nil {
+				cancel()
+				err = fmt.Errorf("looking up %s addresses: %w", result.network, result.err)
+			}
+			continue
+		}
+		switch result.network {
+		case "ip4":
+			ipv4 = make([]netip.Addr, len(result.ips))
+			for i, ip := range result.ips {
+				ipv4[i] = netip.AddrFrom4([4]byte(ip))
+			}
+		case "ip6":
+			ipv6 = make([]netip.Addr, len(result.ips))
+			for i, ip := range result.ips {
+				ipv6[i] = netip.AddrFrom16([16]byte(ip))
+			}
 		}
 	}
-	return nil, nil, err
-}
+	cancel()
 
-func (s *Service) lookupIPs(ctx context.Context, hostname string) (
-	ipv4, ipv6 []netip.Addr, err error) {
-	netIPs, err := s.resolver.LookupIP(ctx, "ip", hostname)
-	if err != nil {
-		return nil, nil, err
-	}
-
-	ipv4 = make([]netip.Addr, 0, len(netIPs))
-	ipv6 = make([]netip.Addr, 0, len(netIPs))
-	for _, netIP := range netIPs {
-		switch {
-		case netIP == nil:
-		case netIP.To4() != nil:
-			ipv4 = append(ipv4, netip.AddrFrom4([4]byte(netIP.To4())))
-		default: // IPv6
-			ipv6 = append(ipv6, netip.AddrFrom16([16]byte(netIP.To16())))
-		}
-	}
-
-	return ipv4, ipv6, nil
+	return ipv4, ipv6, err
 }
 
 func doIPVersion(records []librecords.Record) (doIP, doIPv4, doIPv6 bool) {
@@ -101,7 +126,8 @@ func doIPVersion(records []librecords.Record) (doIP, doIPv4, doIPv6 bool) {
 }
 
 func (s *Service) getNewIPs(ctx context.Context, doIP, doIPv4, doIPv6 bool) (
-	ip, ipv4, ipv6 netip.Addr, errors []error) {
+	ip, ipv4, ipv6 netip.Addr, errors []error,
+) {
 	var err error
 	if doIP {
 		ip, err = tryAndRepeatGettingIP(ctx, s.ipGetter.IP, s.logger, ipversion.IP4or6)
@@ -125,7 +151,8 @@ func (s *Service) getNewIPs(ctx context.Context, doIP, doIPv4, doIPv6 bool) (
 }
 
 func (s *Service) getRecordIDsToUpdate(ctx context.Context, records []librecords.Record,
-	ip, ipv4, ipv6 netip.Addr) (recordIDs map[uint]struct{}) {
+	ip, ipv4, ipv6 netip.Addr,
+) (recordIDs map[uint]struct{}) {
 	recordIDs = make(map[uint]struct{})
 	for i, record := range records {
 		shouldUpdate := s.shouldUpdateRecord(ctx, record, ip, ipv4, ipv6)
@@ -138,7 +165,8 @@ func (s *Service) getRecordIDsToUpdate(ctx context.Context, records []librecords
 }
 
 func (s *Service) shouldUpdateRecord(ctx context.Context, record librecords.Record,
-	ip, ipv4, ipv6 netip.Addr) (update bool) {
+	ip, ipv4, ipv6 netip.Addr,
+) (update bool) {
 	now := s.timeNow()
 
 	isWithinCooldown := now.Sub(record.History.GetSuccessTime()) < s.cooldown
@@ -178,7 +206,8 @@ func (s *Service) shouldUpdateRecord(ctx context.Context, record librecords.Reco
 }
 
 func (s *Service) shouldUpdateRecordNoLookup(hostname string, ipVersion ipversion.IPVersion,
-	lastIP, publicIP netip.Addr) (update bool) {
+	lastIP, publicIP netip.Addr,
+) (update bool) {
 	ipKind := ipVersionToIPKind(ipVersion)
 	if publicIP.IsValid() && publicIP.Compare(lastIP) != 0 {
 		s.logInfoNoLookupUpdate(hostname, ipKind, lastIP, publicIP)
@@ -189,7 +218,8 @@ func (s *Service) shouldUpdateRecordNoLookup(hostname string, ipVersion ipversio
 }
 
 func (s *Service) shouldUpdateRecordWithLookup(ctx context.Context, hostname string,
-	ipVersion ipversion.IPVersion, publicIP netip.Addr) (update bool) {
+	ipVersion ipversion.IPVersion, publicIP netip.Addr,
+) (update bool) {
 	const tries = 5
 	recordIPv4s, recordIPv6s, err := s.lookupIPsResilient(ctx, hostname, tries)
 	if err != nil {
@@ -375,7 +405,8 @@ func (s *Service) Start(ctx context.Context) (runError <-chan error, startErr er
 }
 
 func (s *Service) run(ctx context.Context, ready chan<- struct{},
-	done chan<- struct{}) {
+	done chan<- struct{},
+) {
 	defer close(done)
 	ticker := time.NewTicker(s.period)
 	close(ready)