package b2 import ( "context" "hash" "io" "net/http" "path" "sync" "time" "github.com/restic/restic/internal/backend" "github.com/restic/restic/internal/backend/layout" "github.com/restic/restic/internal/backend/sema" "github.com/restic/restic/internal/debug" "github.com/restic/restic/internal/errors" "github.com/restic/restic/internal/restic" "github.com/cenkalti/backoff/v4" "github.com/kurin/blazer/b2" "github.com/kurin/blazer/base" ) // b2Backend is a backend which stores its data on Backblaze B2. type b2Backend struct { client *b2.Client bucket *b2.Bucket cfg Config listMaxItems int layout.Layout sem sema.Semaphore canDelete bool } // Billing happens in 1000 item granlarity, but we are more interested in reducing the number of network round trips const defaultListMaxItems = 10 * 1000 // ensure statically that *b2Backend implements restic.Backend. var _ restic.Backend = &b2Backend{} type sniffingRoundTripper struct { sync.Mutex lastErr error http.RoundTripper } func (s *sniffingRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) { res, err := s.RoundTripper.RoundTrip(req) if err != nil { s.Lock() s.lastErr = err s.Unlock() } return res, err } func newClient(ctx context.Context, cfg Config, rt http.RoundTripper) (*b2.Client, error) { sniffer := &sniffingRoundTripper{RoundTripper: rt} opts := []b2.ClientOption{b2.Transport(sniffer)} // if the connection B2 fails, this can cause the client to hang // cancel the connection after a minute to at least provide some feedback to the user ctx, cancel := context.WithTimeout(ctx, time.Minute) defer cancel() c, err := b2.NewClient(ctx, cfg.AccountID, cfg.Key.Unwrap(), opts...) if err == context.DeadlineExceeded { if sniffer.lastErr != nil { return nil, sniffer.lastErr } return nil, errors.New("connection to B2 failed") } else if err != nil { return nil, errors.Wrap(err, "b2.NewClient") } return c, nil } // Open opens a connection to the B2 service. func Open(ctx context.Context, cfg Config, rt http.RoundTripper) (restic.Backend, error) { debug.Log("cfg %#v", cfg) ctx, cancel := context.WithCancel(ctx) defer cancel() client, err := newClient(ctx, cfg, rt) if err != nil { return nil, err } bucket, err := client.Bucket(ctx, cfg.Bucket) if err != nil { return nil, errors.Wrap(err, "Bucket") } sem, err := sema.New(cfg.Connections) if err != nil { return nil, err } be := &b2Backend{ client: client, bucket: bucket, cfg: cfg, Layout: &layout.DefaultLayout{ Join: path.Join, Path: cfg.Prefix, }, listMaxItems: defaultListMaxItems, sem: sem, canDelete: true, } return be, nil } // Create opens a connection to the B2 service. If the bucket does not exist yet, // it is created. func Create(ctx context.Context, cfg Config, rt http.RoundTripper) (restic.Backend, error) { debug.Log("cfg %#v", cfg) ctx, cancel := context.WithCancel(ctx) defer cancel() client, err := newClient(ctx, cfg, rt) if err != nil { return nil, err } attr := b2.BucketAttrs{ Type: b2.Private, } bucket, err := client.NewBucket(ctx, cfg.Bucket, &attr) if err != nil { return nil, errors.Wrap(err, "NewBucket") } sem, err := sema.New(cfg.Connections) if err != nil { return nil, err } be := &b2Backend{ client: client, bucket: bucket, cfg: cfg, Layout: &layout.DefaultLayout{ Join: path.Join, Path: cfg.Prefix, }, listMaxItems: defaultListMaxItems, sem: sem, } _, err = be.Stat(ctx, restic.Handle{Type: restic.ConfigFile}) if err != nil && !be.IsNotExist(err) { return nil, err } if err == nil { return nil, errors.New("config already exists") } return be, nil } // SetListMaxItems sets the number of list items to load per request. func (be *b2Backend) SetListMaxItems(i int) { be.listMaxItems = i } func (be *b2Backend) Connections() uint { return be.cfg.Connections } // Location returns the location for the backend. func (be *b2Backend) Location() string { return be.cfg.Bucket } // Hasher may return a hash function for calculating a content hash for the backend func (be *b2Backend) Hasher() hash.Hash { return nil } // HasAtomicReplace returns whether Save() can atomically replace files func (be *b2Backend) HasAtomicReplace() bool { return true } // IsNotExist returns true if the error is caused by a non-existing file. func (be *b2Backend) IsNotExist(err error) bool { // blazer/b2 does not export its error types and values, // so we can't use errors.{As,Is}. for ; err != nil; err = errors.Unwrap(err) { if b2.IsNotExist(err) { return true } } return false } // 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 restic.Handle, length int, offset int64, fn func(rd io.Reader) error) error { return backend.DefaultLoad(ctx, h, length, offset, be.openReader, fn) } func (be *b2Backend) openReader(ctx context.Context, h restic.Handle, length int, offset int64) (io.ReadCloser, error) { ctx, cancel := context.WithCancel(ctx) be.sem.GetToken() name := be.Layout.Filename(h) obj := be.bucket.Object(name) if offset == 0 && length == 0 { rd := obj.NewReader(ctx) return be.sem.ReleaseTokenOnClose(rd, cancel), nil } // pass a negative length to NewRangeReader so that the remainder of the // file is read. if length == 0 { length = -1 } rd := obj.NewRangeReader(ctx, offset, int64(length)) return be.sem.ReleaseTokenOnClose(rd, cancel), nil } // Save stores data in the backend at the handle. func (be *b2Backend) Save(ctx context.Context, h restic.Handle, rd restic.RewindReader) error { ctx, cancel := context.WithCancel(ctx) defer cancel() if err := h.Valid(); err != nil { return backoff.Permanent(err) } be.sem.GetToken() defer be.sem.ReleaseToken() name := be.Filename(h) debug.Log("Save %v, name %v", h, name) obj := be.bucket.Object(name) // b2 always requires sha1 checksums for uploaded file parts w := obj.NewWriter(ctx) n, err := io.Copy(w, rd) if err != nil { _ = w.Close() return errors.Wrap(err, "Copy") } // sanity check if n != rd.Length() { return errors.Errorf("wrote %d bytes instead of the expected %d bytes", n, rd.Length()) } return errors.Wrap(w.Close(), "Close") } // Stat returns information about a blob. func (be *b2Backend) Stat(ctx context.Context, h restic.Handle) (bi restic.FileInfo, err error) { be.sem.GetToken() defer be.sem.ReleaseToken() name := be.Filename(h) obj := be.bucket.Object(name) info, err := obj.Attrs(ctx) if err != nil { return restic.FileInfo{}, errors.Wrap(err, "Stat") } return restic.FileInfo{Size: info.Size, Name: h.Name}, nil } // Remove removes the blob with the given name and type. func (be *b2Backend) Remove(ctx context.Context, h restic.Handle) error { be.sem.GetToken() defer be.sem.ReleaseToken() // the retry backend will also repeat the remove method up to 10 times for i := 0; i < 3; i++ { obj := be.bucket.Object(be.Filename(h)) var err error if be.canDelete { err = obj.Delete(ctx) if err == nil { // keep deleting until we are sure that no leftover file versions exist continue } code, _ := base.Code(err) if code == 401 { // unauthorized // fallback to hide if not allowed to delete files be.canDelete = false debug.Log("Removing %v failed, falling back to b2_hide_file.", h) continue } } else { // hide adds a new file version hiding all older ones, thus retries are not necessary err = obj.Hide(ctx) } // consider a file as removed if b2 informs us that it does not exist if b2.IsNotExist(err) { return nil } return errors.Wrap(err, "Delete") } return errors.New("failed to delete all file versions") } type semLocker struct { sema.Semaphore } func (sm *semLocker) Lock() { sm.GetToken() } func (sm *semLocker) Unlock() { sm.ReleaseToken() } // List returns a channel that yields all names of blobs of type t. func (be *b2Backend) List(ctx context.Context, t restic.FileType, fn func(restic.FileInfo) error) error { ctx, cancel := context.WithCancel(ctx) defer cancel() prefix, _ := be.Basedir(t) iter := be.bucket.List(ctx, b2.ListPrefix(prefix), b2.ListPageSize(be.listMaxItems), b2.ListLocker(&semLocker{be.sem})) for iter.Next() { obj := iter.Object() attrs, err := obj.Attrs(ctx) if err != nil { return err } fi := restic.FileInfo{ Name: path.Base(obj.Name()), Size: attrs.Size, } if err := fn(fi); err != nil { return err } } if err := iter.Err(); err != nil { return err } return nil } // Remove keys for a specified backend type. func (be *b2Backend) removeKeys(ctx context.Context, t restic.FileType) error { return be.List(ctx, t, func(fi restic.FileInfo) error { return be.Remove(ctx, restic.Handle{Type: t, Name: fi.Name}) }) } // Delete removes all restic keys in the bucket. It will not remove the bucket itself. func (be *b2Backend) Delete(ctx context.Context) error { alltypes := []restic.FileType{ restic.PackFile, restic.KeyFile, restic.LockFile, restic.SnapshotFile, restic.IndexFile} for _, t := range alltypes { err := be.removeKeys(ctx, t) if err != nil { return nil } } err := be.Remove(ctx, restic.Handle{Type: restic.ConfigFile}) if err != nil && be.IsNotExist(err) { err = nil } return err } // Close does nothing func (be *b2Backend) Close() error { return nil }