frostfs: Expire saved tokens automatically

Signed-off-by: Vitaliy Potyarkin <v.potyarkin@yadro.com>

providers/http/frostfs/client.go

@@ -7,6 +7,7 @@ import (
 	"crypto/rand"
 	"errors"
 	"fmt"
+	"math"
 	"time"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client"
@@ -26,6 +27,7 @@ type Storage struct {
 	container containerid.ID
 	key       *ecdsa.PrivateKey
 	user      user.ID
+	epoch     epochCalc
 }
 
 const storageRequestTimeout = 10 * time.Second
@@ -215,3 +217,59 @@ func getKey(walletPath, walletAccount, walletPassword string) (*ecdsa.PrivateKey
 	key := account.PrivateKey().PrivateKey
 	return &key, nil
 }
+
+// Epoch converts human time value into FrostFS epoch that is expected to be
+// current at that time.
+//
+// Due to nonlinear nature of FrostFS time these calculations are approximate
+// for the future and are likely wrong for the past.
+func (s *Storage) Epoch(ctx context.Context, t time.Time) (epoch uint64, err error) {
+	if !s.epoch.Ready() {
+		var cancel context.CancelFunc
+		ctx, cancel = context.WithTimeout(ctx, storageRequestTimeout)
+		defer cancel()
+		c, err := s.dial(ctx)
+		if err != nil {
+			return 0, fmt.Errorf("connecting to storage node: %w", err)
+		}
+		res, err := c.NetworkInfo(ctx, client.PrmNetworkInfo{})
+		if err != nil {
+			return 0, fmt.Errorf("network info request: %w", err)
+		}
+		stat := res.Status()
+		if !status.IsSuccessful(stat) {
+			return 0, fmt.Errorf("network info: %w", stat.(error))
+		}
+		info := res.Info()
+		s.epoch = epochCalc{
+			timestamp:     time.Now(),
+			epoch:         info.CurrentEpoch(),
+			blockPerEpoch: info.EpochDuration(),
+			msPerBlock:    info.MsPerBlock(),
+		}
+	}
+	if !s.epoch.Ready() {
+		return 0, errors.New("failed to initialize epoch calculator")
+	}
+	return s.epoch.At(t), nil
+}
+
+type epochCalc struct {
+	timestamp     time.Time
+	epoch         uint64
+	msPerBlock    int64
+	blockPerEpoch uint64
+}
+
+func (e epochCalc) At(t time.Time) uint64 {
+	return uint64(
+		int64(e.epoch) +
+			int64(math.Ceil(
+				float64(t.Sub(e.timestamp).Milliseconds())/
+					float64(e.msPerBlock)/
+					float64(e.blockPerEpoch))))
+}
+
+func (e epochCalc) Ready() bool {
+	return !e.timestamp.IsZero() && e.epoch != 0 && e.msPerBlock != 0 && e.blockPerEpoch != 0
+}

providers/http/frostfs/client_test.go

@@ -10,6 +10,7 @@ import (
 	"os"
 	"sync"
 	"testing"
+	"time"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/user"
 	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
@@ -188,3 +189,23 @@ func TestLoadWalletAndSign(t *testing.T) {
 		t.Errorf("signature %x (%d bytes): check failed: wallet key", sig, len(sig))
 	}
 }
+
+// Show epoch values for nearby times.
+//
+// This test is barely useful when run unattended: it will only validate "no
+// errors, no panic" result.
+// Human operator is required to check if epoch calculations actually make
+// sense for network configuration being used.
+func TestEpoch(t *testing.T) {
+	storage := openStorage(t)
+	now := time.Now()
+	var i time.Duration
+	for i = -10; i < 10; i++ {
+		timestamp := now.Add(i * time.Minute) //nolint:durationcheck
+		epoch, err := storage.Epoch(context.Background(), timestamp)
+		if err != nil {
+			t.Fatal(err)
+		}
+		t.Logf("%s: %d", timestamp, epoch)
+	}
+}

providers/http/frostfs/frostfs.go

@@ -7,10 +7,18 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"strconv"
+	"time"
 
 	"github.com/go-acme/lego/v4/challenge"
 )
 
+const (
+	// Challenge token will be garbage collected sometime after this interval
+	// even if Cleanup() call fails for whatever reason.
+	tokenLifetime = 1 * time.Hour
+)
+
 // HTTPProvider is a custom solver for HTTP-01 challenge that saves token to FrostFS.
 type HTTPProvider struct {
 	frostfs *Storage
@@ -42,11 +50,20 @@ func (w *HTTPProvider) Present(domain, token, keyAuth string) error {
 	if w.oid != "" {
 		return fmt.Errorf("%T is not safe to re-enter: object was saved and not yet cleaned up: %s", w, w.oid)
 	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	expires, err := w.frostfs.Epoch(ctx, time.Now().Add(tokenLifetime))
+	if err != nil {
+		return fmt.Errorf("failed to calculate token expiration: %w", err)
+	}
 	w.oid, err = w.frostfs.Save(
-		context.TODO(),
+		ctx,
 		[]byte(keyAuth),
 		"FileName", token,
 		"ACME", token,
+		"__SYSTEM__EXPIRATION_EPOCH", strconv.FormatUint(expires, 10),
 	)
 	return err
 }