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Merge pull request #4803 from restic/permanent-retry-failure 

Do not retry permanent backend failures
This commit is contained in:
Michael Eischer 2024-05-18 20:07:06 +02:00 committed by GitHub
parent 7ed560a201 53d15bcd1b
commit dcd151147c
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
25 changed files with 407 additions and 75 deletions
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8
changelog/unreleased/issue-4515
View File

@ -1,8 +0,0 @@
Change: Don't retry to load files that don't exist
Restic used to always retry to load files. It now only retries to load
files if they exist.
https://github.com/restic/restic/issues/4515
https://github.com/restic/restic/issues/1523
https://github.com/restic/restic/pull/4520

18
changelog/unreleased/issue-4627
View File

@ -1,4 +1,4 @@
Enhancement: Improve reliability of backend operations
Change: Redesign backend error handling to improve reliability
Restic now downloads pack files in large chunks instead of using a streaming
download. This prevents failures due to interrupted streams. The `restore`
@ -6,12 +6,20 @@ command now also retries downloading individual blobs that cannot be retrieved.
HTTP requests that are stuck for more than two minutes while uploading or
downloading are now forcibly interrupted. This ensures that stuck requests are
retried after a short timeout. These new request timeouts can temporarily be
disabled by setting the environment variable
`RESTIC_FEATURES=http-timeouts=false`. Note that this feature flag will be
removed in the next minor restic version.
retried after a short timeout.
Attempts to access a missing file or a truncated file will no longer be retried.
This avoids unnecessary retries in those cases.
Most parts of the new backend error handling can temporarily be disabled by
setting the environment variable
`RESTIC_FEATURES=backend-error-redesign=false`. Note that this feature flag will
be removed in the next minor restic version.
https://github.com/restic/restic/issues/4627
https://github.com/restic/restic/issues/4193
https://github.com/restic/restic/pull/4605
https://github.com/restic/restic/pull/4792
https://github.com/restic/restic/issues/4515
https://github.com/restic/restic/issues/1523
https://github.com/restic/restic/pull/4520

19
internal/backend/azure/azure.go
View File

@ -167,6 +167,20 @@ func (be *Backend) IsNotExist(err error) bool {
return bloberror.HasCode(err, bloberror.BlobNotFound)
}
func (be *Backend) IsPermanentError(err error) bool {
if be.IsNotExist(err) {
return true
}
var aerr *azcore.ResponseError
if errors.As(err, &aerr) {
if aerr.StatusCode == http.StatusRequestedRangeNotSatisfiable || aerr.StatusCode == http.StatusUnauthorized || aerr.StatusCode == http.StatusForbidden {
return true
}
}
return false
}
// Join combines path components with slashes.
func (be *Backend) Join(p ...string) string {
return path.Join(p...)
@ -313,6 +327,11 @@ func (be *Backend) openReader(ctx context.Context, h backend.Handle, length int,
return nil, err
}
if length > 0 && (resp.ContentLength == nil || *resp.ContentLength != int64(length)) {
_ = resp.Body.Close()
return nil, &azcore.ResponseError{ErrorCode: "restic-file-too-short", StatusCode: http.StatusRequestedRangeNotSatisfiable}
}
return resp.Body, err
}

28
internal/backend/b2/b2.go
View File

@ -2,6 +2,7 @@ package b2
import (
"context"
"fmt"
"hash"
"io"
"net/http"
@ -31,6 +32,8 @@ type b2Backend struct {
canDelete bool
}
var errTooShort = fmt.Errorf("file is too short")
// Billing happens in 1000 item granularity, but we are more interested in reducing the number of network round trips
const defaultListMaxItems = 10 * 1000
@ -186,13 +189,36 @@ func (be *b2Backend) IsNotExist(err error) bool {
return false
}
func (be *b2Backend) IsPermanentError(err error) bool {
// the library unfortunately endlessly retries authentication errors
return be.IsNotExist(err) || errors.Is(err, errTooShort)
}
// Load runs fn with a reader that yields the contents of the file at h at the
// given offset.
func (be *b2Backend) Load(ctx context.Context, h backend.Handle, length int, offset int64, fn func(rd io.Reader) error) error {
ctx, cancel := context.WithCancel(ctx)
defer cancel()
return util.DefaultLoad(ctx, h, length, offset, be.openReader, fn)
return util.DefaultLoad(ctx, h, length, offset, be.openReader, func(rd io.Reader) error {
if length == 0 {
return fn(rd)
}
// there is no direct way to efficiently check whether the file is too short
// use a LimitedReader to track the number of bytes read
limrd := &io.LimitedReader{R: rd, N: int64(length)}
err := fn(limrd)
// check the underlying reader to be agnostic to however fn() handles the returned error
_, rderr := rd.Read([]byte{0})
if rderr == io.EOF && limrd.N != 0 {
// file is too short
return fmt.Errorf("%w: %v", errTooShort, err)
}
return err
})
}
func (be *b2Backend) openReader(ctx context.Context, h backend.Handle, length int, offset int64) (io.ReadCloser, error) {

10
internal/backend/backend.go
View File

@ -38,7 +38,9 @@ type Backend interface {
// Load runs fn with a reader that yields the contents of the file at h at the
// given offset. If length is larger than zero, only a portion of the file
// is read.
// is read. If the length is larger than zero and the file is too short to return
// the requested length bytes, then an error MUST be returned that is recognized
// by IsPermanentError().
//
// The function fn may be called multiple times during the same Load invocation
// and therefore must be idempotent.
@ -66,6 +68,12 @@ type Backend interface {
// for unwrapping it.
IsNotExist(err error) bool
// IsPermanentError returns true if the error can very likely not be resolved
// by retrying the operation. Backends should return true if the file is missing,
// the requested range does not (completely) exist in the file or the user is
// not authorized to perform the requested operation.
IsPermanentError(err error) bool
// Delete removes all data in the backend.
Delete(ctx context.Context) error
}

4
internal/backend/dryrun/dry_backend.go
View File

@ -72,6 +72,10 @@ func (be *Backend) IsNotExist(err error) bool {
return be.b.IsNotExist(err)
}
func (be *Backend) IsPermanentError(err error) bool {
return be.b.IsPermanentError(err)
}
func (be *Backend) List(ctx context.Context, t backend.FileType, fn func(backend.FileInfo) error) error {
return be.b.List(ctx, t, fn)
}

2
internal/backend/dryrun/dry_backend_test.go
View File

@ -96,7 +96,7 @@ func TestDry(t *testing.T) {
}
case "load":
data := ""
err = step.be.Load(ctx, handle, 100, 0, func(rd io.Reader) error {
err = step.be.Load(ctx, handle, 0, 0, func(rd io.Reader) error {
buf, err := io.ReadAll(rd)
data = string(buf)
return err

20
internal/backend/gs/gs.go
View File

@ -173,6 +173,21 @@ func (be *Backend) IsNotExist(err error) bool {
return errors.Is(err, storage.ErrObjectNotExist)
}
func (be *Backend) IsPermanentError(err error) bool {
if be.IsNotExist(err) {
return true
}
var gerr *googleapi.Error
if errors.As(err, &gerr) {
if gerr.Code == http.StatusRequestedRangeNotSatisfiable || gerr.Code == http.StatusUnauthorized || gerr.Code == http.StatusForbidden {
return true
}
}
return false
}
// Join combines path components with slashes.
func (be *Backend) Join(p ...string) string {
return path.Join(p...)
@ -273,6 +288,11 @@ func (be *Backend) openReader(ctx context.Context, h backend.Handle, length int,
return nil, err
}
if length > 0 && r.Attrs.Size < offset+int64(length) {
_ = r.Close()
return nil, &googleapi.Error{Code: http.StatusRequestedRangeNotSatisfiable, Message: "restic-file-too-short"}
}
return r, err
}

4
internal/backend/http_transport.go
View File

@ -89,7 +89,7 @@ func Transport(opts TransportOptions) (http.RoundTripper, error) {
if err != nil {
panic(err)
}
if feature.Flag.Enabled(feature.HTTPTimeouts) {
if feature.Flag.Enabled(feature.BackendErrorRedesign) {
h2.WriteByteTimeout = 120 * time.Second
h2.ReadIdleTimeout = 60 * time.Second
h2.PingTimeout = 60 * time.Second
@ -132,7 +132,7 @@ func Transport(opts TransportOptions) (http.RoundTripper, error) {
}
rt := http.RoundTripper(tr)
if feature.Flag.Enabled(feature.HTTPTimeouts) {
if feature.Flag.Enabled(feature.BackendErrorRedesign) {
rt = newWatchdogRoundtripper(rt, 120*time.Second, 128*1024)
}

19
internal/backend/local/local.go
View File

@ -2,6 +2,7 @@ package local
import (
"context"
"fmt"
"hash"
"io"
"os"
@ -30,6 +31,8 @@ type Local struct {
// ensure statically that *Local implements backend.Backend.
var _ backend.Backend = &Local{}
var errTooShort = fmt.Errorf("file is too short")
func NewFactory() location.Factory {
return location.NewLimitedBackendFactory("local", ParseConfig, location.NoPassword, limiter.WrapBackendConstructor(Create), limiter.WrapBackendConstructor(Open))
}
@ -110,6 +113,10 @@ func (b *Local) IsNotExist(err error) bool {
return errors.Is(err, os.ErrNotExist)
}
func (b *Local) IsPermanentError(err error) bool {
return b.IsNotExist(err) || errors.Is(err, errTooShort) || errors.Is(err, os.ErrPermission)
}
// Save stores data in the backend at the handle.
func (b *Local) Save(_ context.Context, h backend.Handle, rd backend.RewindReader) (err error) {
finalname := b.Filename(h)
@ -219,6 +226,18 @@ func (b *Local) openReader(_ context.Context, h backend.Handle, length int, offs
return nil, err
}
fi, err := f.Stat()
if err != nil {
_ = f.Close()
return nil, err
}
size := fi.Size()
if size < offset+int64(length) {
_ = f.Close()
return nil, errTooShort
}
if offset > 0 {
_, err = f.Seek(offset, 0)
if err != nil {

11
internal/backend/mem/mem_backend.go
View File

@ -43,6 +43,7 @@ func NewFactory() location.Factory {
}
var errNotFound = fmt.Errorf("not found")
var errTooSmall = errors.New("access beyond end of file")
const connectionCount = 2
@ -69,6 +70,10 @@ func (be *MemoryBackend) IsNotExist(err error) bool {
return errors.Is(err, errNotFound)
}
func (be *MemoryBackend) IsPermanentError(err error) bool {
return be.IsNotExist(err) || errors.Is(err, errTooSmall)
}
// Save adds new Data to the backend.
func (be *MemoryBackend) Save(ctx context.Context, h backend.Handle, rd backend.RewindReader) error {
be.m.Lock()
@ -131,12 +136,12 @@ func (be *MemoryBackend) openReader(ctx context.Context, h backend.Handle, lengt
}
buf := be.data[h]
if offset > int64(len(buf)) {
return nil, errors.New("offset beyond end of file")
if offset+int64(length) > int64(len(buf)) {
return nil, errTooSmall
}
buf = buf[offset:]
if length > 0 && len(buf) > length {
if length > 0 {
buf = buf[:length]
}

9
internal/backend/mock/backend.go
View File

@ -13,6 +13,7 @@ import (
type Backend struct {
CloseFn func() error
IsNotExistFn func(err error) bool
IsPermanentErrorFn func(err error) bool
SaveFn func(ctx context.Context, h backend.Handle, rd backend.RewindReader) error
OpenReaderFn func(ctx context.Context, h backend.Handle, length int, offset int64) (io.ReadCloser, error)
StatFn func(ctx context.Context, h backend.Handle) (backend.FileInfo, error)
@ -83,6 +84,14 @@ func (m *Backend) IsNotExist(err error) bool {
return m.IsNotExistFn(err)
}
func (m *Backend) IsPermanentError(err error) bool {
if m.IsPermanentErrorFn == nil {
return false
}
return m.IsPermanentErrorFn(err)
}
// Save data in the backend.
func (m *Backend) Save(ctx context.Context, h backend.Handle, rd backend.RewindReader) error {
if m.SaveFn == nil {

73
internal/backend/rest/rest.go
View File

@ -17,6 +17,7 @@ import (
"github.com/restic/restic/internal/backend/util"
"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/errors"
"github.com/restic/restic/internal/feature"
)
// make sure the rest backend implements backend.Backend
@ -30,6 +31,20 @@ type Backend struct {
layout.Layout
}
// restError is returned whenever the server returns a non-successful HTTP status.
type restError struct {
backend.Handle
StatusCode int
Status string
}
func (e *restError) Error() string {
if e.StatusCode == http.StatusNotFound && e.Handle.Type.String() != "invalid" {
return fmt.Sprintf("%v does not exist", e.Handle)
}
return fmt.Sprintf("unexpected HTTP response (%v): %v", e.StatusCode, e.Status)
}
func NewFactory() location.Factory {
return location.NewHTTPBackendFactory("rest", ParseConfig, StripPassword, Create, Open)
}
@ -96,7 +111,7 @@ func Create(ctx context.Context, cfg Config, rt http.RoundTripper) (*Backend, er
}
if resp.StatusCode != http.StatusOK {
return nil, fmt.Errorf("server response unexpected: %v (%v)", resp.Status, resp.StatusCode)
return nil, &restError{backend.Handle{}, resp.StatusCode, resp.Status}
}
return be, nil
@ -150,26 +165,31 @@ func (b *Backend) Save(ctx context.Context, h backend.Handle, rd backend.RewindR
}
if resp.StatusCode != http.StatusOK {
return errors.Errorf("server response unexpected: %v (%v)", resp.Status, resp.StatusCode)
return &restError{h, resp.StatusCode, resp.Status}
}
return nil
}
// notExistError is returned whenever the requested file does not exist on the
// server.
type notExistError struct {
backend.Handle
}
func (e *notExistError) Error() string {
return fmt.Sprintf("%v does not exist", e.Handle)
}
// IsNotExist returns true if the error was caused by a non-existing file.
func (b *Backend) IsNotExist(err error) bool {
var e *notExistError
return errors.As(err, &e)
var e *restError
return errors.As(err, &e) && e.StatusCode == http.StatusNotFound
}
func (b *Backend) IsPermanentError(err error) bool {
if b.IsNotExist(err) {
return true
}
var rerr *restError
if errors.As(err, &rerr) {
if rerr.StatusCode == http.StatusRequestedRangeNotSatisfiable || rerr.StatusCode == http.StatusUnauthorized || rerr.StatusCode == http.StatusForbidden {
return true
}
}
return false
}
// Load runs fn with a reader that yields the contents of the file at h at the
@ -221,14 +241,13 @@ func (b *Backend) openReader(ctx context.Context, h backend.Handle, length int,
return nil, errors.Wrap(err, "client.Do")
}
if resp.StatusCode == http.StatusNotFound {
_ = drainAndClose(resp)
return nil, &notExistError{h}
}
if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusPartialContent {
_ = drainAndClose(resp)
return nil, errors.Errorf("unexpected HTTP response (%v): %v", resp.StatusCode, resp.Status)
return nil, &restError{h, resp.StatusCode, resp.Status}
}
if feature.Flag.Enabled(feature.BackendErrorRedesign) && length > 0 && resp.ContentLength != int64(length) {
return nil, &restError{h, http.StatusRequestedRangeNotSatisfiable, "partial out of bounds read"}
}
return resp.Body, nil
@ -251,12 +270,8 @@ func (b *Backend) Stat(ctx context.Context, h backend.Handle) (backend.FileInfo,
return backend.FileInfo{}, err
}
if resp.StatusCode == http.StatusNotFound {
return backend.FileInfo{}, &notExistError{h}
}
if resp.StatusCode != http.StatusOK {
return backend.FileInfo{}, errors.Errorf("unexpected HTTP response (%v): %v", resp.StatusCode, resp.Status)
return backend.FileInfo{}, &restError{h, resp.StatusCode, resp.Status}
}
if resp.ContentLength < 0 {
@ -288,12 +303,8 @@ func (b *Backend) Remove(ctx context.Context, h backend.Handle) error {
return err
}
if resp.StatusCode == http.StatusNotFound {
return &notExistError{h}
}
if resp.StatusCode != http.StatusOK {
return errors.Errorf("blob not removed, server response: %v (%v)", resp.Status, resp.StatusCode)
return &restError{h, resp.StatusCode, resp.Status}
}
return nil
@ -330,7 +341,7 @@ func (b *Backend) List(ctx context.Context, t backend.FileType, fn func(backend.
if resp.StatusCode != http.StatusOK {
_ = drainAndClose(resp)
return errors.Errorf("List failed, server response: %v (%v)", resp.Status, resp.StatusCode)
return &restError{backend.Handle{Type: t}, resp.StatusCode, resp.Status}
}
if resp.Header.Get("Content-Type") == ContentTypeV2 {

48
internal/backend/retry/backend_retry.go
View File

@ -2,13 +2,16 @@ package retry
import (
"context"
"errors"
"fmt"
"io"
"sync"
"time"
"github.com/cenkalti/backoff/v4"
"github.com/restic/restic/internal/backend"
"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/feature"
)
// Backend retries operations on the backend in case of an error with a
@ -18,6 +21,8 @@ type Backend struct {
MaxTries int
Report func(string, error, time.Duration)
Success func(string, int)
failedLoads sync.Map
}
// statically ensure that RetryBackend implements backend.Backend.
@ -74,7 +79,16 @@ func (be *Backend) retry(ctx context.Context, msg string, f func() error) error
bo.InitialInterval = 1 * time.Millisecond
}
err := retryNotifyErrorWithSuccess(f,
err := retryNotifyErrorWithSuccess(
func() error {
err := f()
// don't retry permanent errors as those very likely cannot be fixed by retrying
// TODO remove IsNotExist(err) special cases when removing the feature flag
if feature.Flag.Enabled(feature.BackendErrorRedesign) && !errors.Is(err, &backoff.PermanentError{}) && be.Backend.IsPermanentError(err) {
return backoff.Permanent(err)
}
return err
},
backoff.WithContext(backoff.WithMaxRetries(bo, uint64(be.MaxTries)), ctx),
func(err error, d time.Duration) {
if be.Report != nil {
@ -121,19 +135,39 @@ func (be *Backend) Save(ctx context.Context, h backend.Handle, rd backend.Rewind
})
}
// Failed loads expire after an hour
var failedLoadExpiry = time.Hour
// Load returns a reader that yields the contents of the file at h at the
// given offset. If length is larger than zero, only a portion of the file
// is returned. rd must be closed after use. If an error is returned, the
// ReadCloser must be nil.
func (be *Backend) Load(ctx context.Context, h backend.Handle, length int, offset int64, consumer func(rd io.Reader) error) (err error) {
return be.retry(ctx, fmt.Sprintf("Load(%v, %v, %v)", h, length, offset),
key := h
key.IsMetadata = false
// Implement the circuit breaker pattern for files that exhausted all retries due to a non-permanent error
if v, ok := be.failedLoads.Load(key); ok {
if time.Since(v.(time.Time)) > failedLoadExpiry {
be.failedLoads.Delete(key)
} else {
// fail immediately if the file was already problematic during the last hour
return fmt.Errorf("circuit breaker open for file %v", h)
}
}
err = be.retry(ctx, fmt.Sprintf("Load(%v, %v, %v)", h, length, offset),
func() error {
err := be.Backend.Load(ctx, h, length, offset, consumer)
if be.Backend.IsNotExist(err) {
return backoff.Permanent(err)
}
return err
return be.Backend.Load(ctx, h, length, offset, consumer)
})
if feature.Flag.Enabled(feature.BackendErrorRedesign) && err != nil && !be.IsPermanentError(err) {
// We've exhausted the retries, the file is likely inaccessible. By excluding permanent
// errors, not found or truncated files are not recorded.
be.failedLoads.LoadOrStore(key, time.Now())
}
return err
}
// Stat returns information about the File identified by h.

86
internal/backend/retry/backend_retry_test.go
View File

@ -4,6 +4,7 @@ import (
"bytes"
"context"
"io"
"strings"
"testing"
"time"
@ -289,7 +290,7 @@ func TestBackendLoadNotExists(t *testing.T) {
}
return nil, notFound
}
be.IsNotExistFn = func(err error) bool {
be.IsPermanentErrorFn = func(err error) bool {
return errors.Is(err, notFound)
}
@ -299,10 +300,61 @@ func TestBackendLoadNotExists(t *testing.T) {
err := retryBackend.Load(context.TODO(), backend.Handle{}, 0, 0, func(rd io.Reader) (err error) {
return nil
})
test.Assert(t, be.IsNotExistFn(err), "unexpected error %v", err)
test.Assert(t, be.IsPermanentErrorFn(err), "unexpected error %v", err)
test.Equals(t, 1, attempt)
}
func TestBackendLoadCircuitBreaker(t *testing.T) {
// retry should not retry if the error matches IsPermanentError
notFound := errors.New("not found")
otherError := errors.New("something")
attempt := 0
be := mock.NewBackend()
be.IsPermanentErrorFn = func(err error) bool {
return errors.Is(err, notFound)
}
be.OpenReaderFn = func(ctx context.Context, h backend.Handle, length int, offset int64) (io.ReadCloser, error) {
attempt++
return nil, otherError
}
nilRd := func(rd io.Reader) (err error) {
return nil
}
TestFastRetries(t)
retryBackend := New(be, 2, nil, nil)
// trip the circuit breaker for file "other"
err := retryBackend.Load(context.TODO(), backend.Handle{Name: "other"}, 0, 0, nilRd)
test.Equals(t, otherError, err, "unexpected error")
test.Equals(t, 3, attempt)
attempt = 0
err = retryBackend.Load(context.TODO(), backend.Handle{Name: "other"}, 0, 0, nilRd)
test.Assert(t, strings.Contains(err.Error(), "circuit breaker open for file"), "expected circuit breaker error, got %v")
test.Equals(t, 0, attempt)
// don't trip for permanent errors
be.OpenReaderFn = func(ctx context.Context, h backend.Handle, length int, offset int64) (io.ReadCloser, error) {
attempt++
return nil, notFound
}
err = retryBackend.Load(context.TODO(), backend.Handle{Name: "notfound"}, 0, 0, nilRd)
test.Equals(t, notFound, err, "expected circuit breaker to only affect other file, got %v")
err = retryBackend.Load(context.TODO(), backend.Handle{Name: "notfound"}, 0, 0, nilRd)
test.Equals(t, notFound, err, "persistent error must not trigger circuit breaker, got %v")
// wait for circuit breaker to expire
time.Sleep(5 * time.Millisecond)
old := failedLoadExpiry
defer func() {
failedLoadExpiry = old
}()
failedLoadExpiry = 3 * time.Millisecond
err = retryBackend.Load(context.TODO(), backend.Handle{Name: "other"}, 0, 0, nilRd)
test.Equals(t, notFound, err, "expected circuit breaker to reset, got %v")
}
func TestBackendStatNotExists(t *testing.T) {
// stat should not retry if the error matches IsNotExist
notFound := errors.New("not found")
@ -329,6 +381,36 @@ func TestBackendStatNotExists(t *testing.T) {
test.Equals(t, 1, attempt)
}
func TestBackendRetryPermanent(t *testing.T) {
// retry should not retry if the error matches IsPermanentError
notFound := errors.New("not found")
attempt := 0
be := mock.NewBackend()
be.IsPermanentErrorFn = func(err error) bool {
return errors.Is(err, notFound)
}
TestFastRetries(t)
retryBackend := New(be, 2, nil, nil)
err := retryBackend.retry(context.TODO(), "test", func() error {
attempt++
return notFound
})
test.Assert(t, be.IsPermanentErrorFn(err), "unexpected error %v", err)
test.Equals(t, 1, attempt)
attempt = 0
err = retryBackend.retry(context.TODO(), "test", func() error {
attempt++
return errors.New("something")
})
test.Assert(t, !be.IsPermanentErrorFn(err), "error unexpectedly considered permanent %v", err)
test.Equals(t, 3, attempt)
}
func assertIsCanceled(t *testing.T, err error) {
test.Assert(t, err == context.Canceled, "got unexpected err %v", err)
}

25
internal/backend/s3/s3.go
View File

@ -17,6 +17,7 @@ import (
"github.com/restic/restic/internal/backend/util"
"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/errors"
"github.com/restic/restic/internal/feature"
"github.com/minio/minio-go/v7"
"github.com/minio/minio-go/v7/pkg/credentials"
@ -229,6 +230,21 @@ func (be *Backend) IsNotExist(err error) bool {
return errors.As(err, &e) && e.Code == "NoSuchKey"
}
func (be *Backend) IsPermanentError(err error) bool {
if be.IsNotExist(err) {
return true
}
var merr minio.ErrorResponse
if errors.As(err, &merr) {
if merr.Code == "InvalidRange" || merr.Code == "AccessDenied" {
return true
}
}
return false
}
// Join combines path components with slashes.
func (be *Backend) Join(p ...string) string {
return path.Join(p...)
@ -384,11 +400,18 @@ func (be *Backend) openReader(ctx context.Context, h backend.Handle, length int,
}
coreClient := minio.Core{Client: be.client}
rd, _, _, err := coreClient.GetObject(ctx, be.cfg.Bucket, objName, opts)
rd, info, _, err := coreClient.GetObject(ctx, be.cfg.Bucket, objName, opts)
if err != nil {
return nil, err
}
if feature.Flag.Enabled(feature.BackendErrorRedesign) && length > 0 {
if info.Size > 0 && info.Size != int64(length) {
_ = rd.Close()
return nil, minio.ErrorResponse{Code: "InvalidRange", Message: "restic-file-too-short"}
}
}
return rd, err
}

26
internal/backend/sftp/sftp.go
View File

@ -20,6 +20,7 @@ import (
"github.com/restic/restic/internal/backend/util"
"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/errors"
"github.com/restic/restic/internal/feature"
"github.com/cenkalti/backoff/v4"
"github.com/pkg/sftp"
@ -43,6 +44,8 @@ type SFTP struct {
var _ backend.Backend = &SFTP{}
var errTooShort = fmt.Errorf("file is too short")
func NewFactory() location.Factory {
return location.NewLimitedBackendFactory("sftp", ParseConfig, location.NoPassword, limiter.WrapBackendConstructor(Create), limiter.WrapBackendConstructor(Open))
}
@ -212,6 +215,10 @@ func (r *SFTP) IsNotExist(err error) bool {
return errors.Is(err, os.ErrNotExist)
}
func (r *SFTP) IsPermanentError(err error) bool {
return r.IsNotExist(err) || errors.Is(err, errTooShort) || errors.Is(err, os.ErrPermission)
}
func buildSSHCommand(cfg Config) (cmd string, args []string, err error) {
if cfg.Command != "" {
args, err := backend.SplitShellStrings(cfg.Command)
@ -419,7 +426,24 @@ func (r *SFTP) checkNoSpace(dir string, size int64, origErr error) error {
// Load runs fn with a reader that yields the contents of the file at h at the
// given offset.
func (r *SFTP) Load(ctx context.Context, h backend.Handle, length int, offset int64, fn func(rd io.Reader) error) error {
return util.DefaultLoad(ctx, h, length, offset, r.openReader, fn)
return util.DefaultLoad(ctx, h, length, offset, r.openReader, func(rd io.Reader) error {
if length == 0 || !feature.Flag.Enabled(feature.BackendErrorRedesign) {
return fn(rd)
}
// there is no direct way to efficiently check whether the file is too short
// rd is already a LimitedReader which can be used to track the number of bytes read
err := fn(rd)
// check the underlying reader to be agnostic to however fn() handles the returned error
_, rderr := rd.Read([]byte{0})
if rderr == io.EOF && rd.(*backend.LimitedReadCloser).N != 0 {
// file is too short
return fmt.Errorf("%w: %v", errTooShort, err)
}
return err
})
}
func (r *SFTP) openReader(_ context.Context, h backend.Handle, length int, offset int64) (io.ReadCloser, error) {

29
internal/backend/swift/swift.go
View File

@ -19,6 +19,7 @@ import (
"github.com/restic/restic/internal/backend/util"
"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/errors"
"github.com/restic/restic/internal/feature"
"github.com/ncw/swift/v2"
)
@ -153,7 +154,18 @@ func (be *beSwift) openReader(ctx context.Context, h backend.Handle, length int,
obj, _, err := be.conn.ObjectOpen(ctx, be.container, objName, false, headers)
if err != nil {
return nil, errors.Wrap(err, "conn.ObjectOpen")
return nil, fmt.Errorf("conn.ObjectOpen: %w", err)
}
if feature.Flag.Enabled(feature.BackendErrorRedesign) && length > 0 {
// get response length, but don't cause backend calls
cctx, cancel := context.WithCancel(context.Background())
cancel()
objLength, e := obj.Length(cctx)
if e == nil && objLength != int64(length) {
_ = obj.Close()
return nil, &swift.Error{StatusCode: http.StatusRequestedRangeNotSatisfiable, Text: "restic-file-too-short"}
}
}
return obj, nil
@ -242,6 +254,21 @@ func (be *beSwift) IsNotExist(err error) bool {
return errors.As(err, &e) && e.StatusCode == http.StatusNotFound
}
func (be *beSwift) IsPermanentError(err error) bool {
if be.IsNotExist(err) {
return true
}
var serr *swift.Error
if errors.As(err, &serr) {
if serr.StatusCode == http.StatusRequestedRangeNotSatisfiable || serr.StatusCode == http.StatusUnauthorized || serr.StatusCode == http.StatusForbidden {
return true
}
}
return false
}
// Delete removes all restic objects in the container.
// It will not remove the container itself.
func (be *beSwift) Delete(ctx context.Context) error {

25
internal/backend/test/tests.go
View File

@ -99,6 +99,7 @@ func (s *Suite[C]) TestConfig(t *testing.T) {
t.Fatalf("did not get expected error for non-existing config")
}
test.Assert(t, b.IsNotExist(err), "IsNotExist() did not recognize error from LoadAll(): %v", err)
test.Assert(t, b.IsPermanentError(err), "IsPermanentError() did not recognize error from LoadAll(): %v", err)
err = b.Save(context.TODO(), backend.Handle{Type: backend.ConfigFile}, backend.NewByteReader([]byte(testString), b.Hasher()))
if err != nil {
@ -135,6 +136,7 @@ func (s *Suite[C]) TestLoad(t *testing.T) {
t.Fatalf("Load() did not return an error for non-existing blob")
}
test.Assert(t, b.IsNotExist(err), "IsNotExist() did not recognize non-existing blob: %v", err)
test.Assert(t, b.IsPermanentError(err), "IsPermanentError() did not recognize non-existing blob: %v", err)
length := rand.Intn(1<<24) + 2000
@ -181,8 +183,12 @@ func (s *Suite[C]) TestLoad(t *testing.T) {
}
getlen := l
if l >= len(d) && rand.Float32() >= 0.5 {
getlen = 0
if l >= len(d) {
if rand.Float32() >= 0.5 {
getlen = 0
} else {
getlen = len(d)
}
}
if l > 0 && l < len(d) {
@ -225,6 +231,18 @@ func (s *Suite[C]) TestLoad(t *testing.T) {
}
}
// test error checking for partial and fully out of bounds read
// only test for length > 0 as we currently do not need strict out of bounds handling for length==0
for _, offset := range []int{length - 99, length - 50, length, length + 100} {
err = b.Load(context.TODO(), handle, 100, int64(offset), func(rd io.Reader) (ierr error) {
_, ierr = io.ReadAll(rd)
return ierr
})
test.Assert(t, err != nil, "Load() did not return error on out of bounds read! o %v, l %v, filelength %v", offset, 100, length)
test.Assert(t, b.IsPermanentError(err), "IsPermanentError() did not recognize out of range read: %v", err)
test.Assert(t, !b.IsNotExist(err), "IsNotExist() must not recognize out of range read: %v", err)
}
test.OK(t, b.Remove(context.TODO(), handle))
}
@ -762,6 +780,7 @@ func (s *Suite[C]) TestBackend(t *testing.T) {
defer s.close(t, b)
test.Assert(t, !b.IsNotExist(nil), "IsNotExist() recognized nil error")
test.Assert(t, !b.IsPermanentError(nil), "IsPermanentError() recognized nil error")
for _, tpe := range []backend.FileType{
backend.PackFile, backend.KeyFile, backend.LockFile,
@ -782,11 +801,13 @@ func (s *Suite[C]) TestBackend(t *testing.T) {
_, err = b.Stat(context.TODO(), h)
test.Assert(t, err != nil, "blob data could be extracted before creation")
test.Assert(t, b.IsNotExist(err), "IsNotExist() did not recognize Stat() error: %v", err)
test.Assert(t, b.IsPermanentError(err), "IsPermanentError() did not recognize Stat() error: %v", err)
// try to read not existing blob
err = testLoad(b, h)
test.Assert(t, err != nil, "blob could be read before creation")
test.Assert(t, b.IsNotExist(err), "IsNotExist() did not recognize Load() error: %v", err)
test.Assert(t, b.IsPermanentError(err), "IsPermanentError() did not recognize Load() error: %v", err)
// try to get string out, should fail
ret, err = beTest(context.TODO(), b, h)

2
internal/cache/file.go vendored
View File

@ -61,7 +61,7 @@ func (c *Cache) load(h backend.Handle, length int, offset int64) (io.ReadCloser,
if size < offset+int64(length) {
_ = f.Close()
_ = c.remove(h)
return nil, errors.Errorf("cached file %v is too small, removing", h)
return nil, errors.Errorf("cached file %v is too short, removing", h)
}
if offset > 0 {

2
internal/crypto/crypto.go
View File

@ -299,7 +299,7 @@ func (k *Key) Open(dst, nonce, ciphertext, _ []byte) ([]byte, error) {
// check for plausible length
if len(ciphertext) < k.Overhead() {
return nil, errors.Errorf("trying to decrypt invalid data: ciphertext too small")
return nil, errors.Errorf("trying to decrypt invalid data: ciphertext too short")
}
l := len(ciphertext) - macSize

4
internal/feature/registry.go
View File

@ -5,17 +5,17 @@ var Flag = New()
// flag names are written in kebab-case
const (
BackendErrorRedesign FlagName = "backend-error-redesign"
DeprecateLegacyIndex FlagName = "deprecate-legacy-index"
DeprecateS3LegacyLayout FlagName = "deprecate-s3-legacy-layout"
DeviceIDForHardlinks FlagName = "device-id-for-hardlinks"
HTTPTimeouts FlagName = "http-timeouts"
)
func init() {
Flag.SetFlags(map[FlagName]FlagDesc{
BackendErrorRedesign: {Type: Beta, Description: "enforce timeouts for stuck HTTP requests and use new backend error handling design."},
DeprecateLegacyIndex: {Type: Beta, Description: "disable support for index format used by restic 0.1.0. Use `restic repair index` to update the index if necessary."},
DeprecateS3LegacyLayout: {Type: Beta, Description: "disable support for S3 legacy layout used up to restic 0.7.0. Use `RESTIC_FEATURES=deprecate-s3-legacy-layout=false restic migrate s3_layout` to migrate your S3 repository if necessary."},
DeviceIDForHardlinks: {Type: Alpha, Description: "store deviceID only for hardlinks to reduce metadata changes for example when using btrfs subvolumes. Will be removed in a future restic version after repository format 3 is available"},
HTTPTimeouts: {Type: Beta, Description: "enforce timeouts for stuck HTTP requests."},
})
}

2
internal/index/indexmap.go
View File

@ -204,7 +204,7 @@ func (h *hashedArrayTree) Size() uint {
func (h *hashedArrayTree) grow() {
idx, subIdx := h.index(h.size)
if int(idx) == len(h.blockList) {
// blockList is too small -> double list and block size
// blockList is too short -> double list and block size
h.blockSize *= 2
h.mask = h.mask*2 + 1
h.maskShift++

6
internal/pack/pack.go
View File

@ -239,7 +239,7 @@ func readRecords(rd io.ReaderAt, size int64, bufsize int) ([]byte, int, error) {
case hlen == 0:
err = InvalidFileError{Message: "header length is zero"}
case hlen < crypto.Extension:
err = InvalidFileError{Message: "header length is too small"}
err = InvalidFileError{Message: "header length is too short"}
case int64(hlen) > size-int64(headerLengthSize):
err = InvalidFileError{Message: "header is larger than file"}
case int64(hlen) > MaxHeaderSize-int64(headerLengthSize):
@ -263,7 +263,7 @@ func readRecords(rd io.ReaderAt, size int64, bufsize int) ([]byte, int, error) {
func readHeader(rd io.ReaderAt, size int64) ([]byte, error) {
debug.Log("size: %v", size)
if size < int64(minFileSize) {
err := InvalidFileError{Message: "file is too small"}
err := InvalidFileError{Message: "file is too short"}
return nil, errors.Wrap(err, "readHeader")
}
@ -305,7 +305,7 @@ func List(k *crypto.Key, rd io.ReaderAt, size int64) (entries []restic.Blob, hdr
}
if len(buf) < crypto.CiphertextLength(0) {
return nil, 0, errors.New("invalid header, too small")
return nil, 0, errors.New("invalid header, too short")
}
hdrSize = headerLengthSize + uint32(len(buf))

2
internal/repository/prune.go
View File

@ -444,7 +444,7 @@ func decidePackAction(ctx context.Context, opts PruneOptions, repo restic.Reposi
// This is equivalent to sorting by unused / total space.
// Instead of unused[i] / used[i] > unused[j] / used[j] we use
// unused[i] * used[j] > unused[j] * used[i] as uint32*uint32 < uint64
// Moreover packs containing trees and too small packs are sorted to the beginning
// Moreover packs containing trees and too short packs are sorted to the beginning
sort.Slice(repackCandidates, func(i, j int) bool {
pi := repackCandidates[i].packInfo
pj := repackCandidates[j].packInfo