Golang backend.Hash函數代碼示例

func TestSave(t *testing.T) {
	repo := SetupRepo()
	defer TeardownRepo(repo)

	for _, size := range testSizes {
		data := make([]byte, size)
		_, err := io.ReadFull(rand.Reader, data)
		OK(t, err)

		id := backend.Hash(data)

		// save
		sid, err := repo.SaveAndEncrypt(pack.Data, data, nil)
		OK(t, err)

		Equals(t, id, sid)

		OK(t, repo.Flush())
		// OK(t, repo.SaveIndex())

		// read back
		buf, err := repo.LoadBlob(pack.Data, id, make([]byte, size))
		OK(t, err)

		Assert(t, len(buf) == len(data),
			"number of bytes read back does not match: expected %d, got %d",
			len(data), len(buf))

		Assert(t, bytes.Equal(buf, data),
			"data does not match: expected %02x, got %02x",
			data, buf)
	}
}

func TestLoadLargeBuffer(t *testing.T) {
	b := mem.New()

	for i := 0; i < 20; i++ {
		data := Random(23+i, rand.Intn(MiB)+500*KiB)

		id := backend.Hash(data)
		err := b.Save(backend.Handle{Name: id.String(), Type: backend.Data}, data)
		OK(t, err)

		buf := make([]byte, len(data)+100)
		buf, err = backend.LoadAll(b, backend.Handle{Type: backend.Data, Name: id.String()}, buf)
		OK(t, err)

		if len(buf) != len(data) {
			t.Errorf("length of returned buffer does not match, want %d, got %d", len(data), len(buf))
			continue
		}

		if !bytes.Equal(buf, data) {
			t.Errorf("wrong data returned")
			continue
		}
	}
}

func TestSaveFrom(t *testing.T) {
	repo := SetupRepo()
	defer TeardownRepo(repo)

	for _, size := range testSizes {
		data := make([]byte, size)
		_, err := io.ReadFull(rand.Reader, data)
		OK(t, err)

		id := backend.Hash(data)

		// save
		err = repo.SaveFrom(pack.Data, id[:], uint(size), bytes.NewReader(data))
		OK(t, err)

		OK(t, repo.Flush())

		// read back
		buf, err := repo.LoadBlob(pack.Data, id[:])

		Assert(t, len(buf) == len(data),
			"number of bytes read back does not match: expected %d, got %d",
			len(data), len(buf))

		Assert(t, bytes.Equal(buf, data),
			"data does not match: expected %02x, got %02x",
			data, buf)
	}
}

// savePacker stores p in the backend.
func (r *Repository) savePacker(p *pack.Packer) error {
	debug.Log("Repo.savePacker", "save packer with %d blobs\n", p.Count())
	data, err := p.Finalize()
	if err != nil {
		return err
	}

	id := backend.Hash(data)
	h := backend.Handle{Type: backend.Data, Name: id.String()}

	err = r.be.Save(h, data)
	if err != nil {
		debug.Log("Repo.savePacker", "Save(%v) error: %v", h, err)
		return err
	}

	debug.Log("Repo.savePacker", "saved as %v", h)

	// update blobs in the index
	for _, b := range p.Blobs() {
		debug.Log("Repo.savePacker", "  updating blob %v to pack %v", b.ID.Str(), id.Str())
		r.idx.Current().Store(PackedBlob{
			Type:   b.Type,
			ID:     b.ID,
			PackID: id,
			Offset: b.Offset,
			Length: uint(b.Length),
		})
	}

	return nil
}

// LoadAndDecrypt loads and decrypts data identified by t and id from the
// backend.
func (r *Repository) LoadAndDecrypt(t backend.Type, id backend.ID) ([]byte, error) {
	debug.Log("Repo.Load", "load %v with id %v", t, id.Str())

	rd, err := r.be.Get(t, id.String())
	if err != nil {
		debug.Log("Repo.Load", "error loading %v: %v", id.Str(), err)
		return nil, err
	}

	buf, err := ioutil.ReadAll(rd)
	if err != nil {
		return nil, err
	}

	err = rd.Close()
	if err != nil {
		return nil, err
	}

	// check hash
	if !backend.Hash(buf).Equal(id) {
		return nil, errors.New("invalid data returned")
	}

	// decrypt
	plain, err := r.Decrypt(buf)
	if err != nil {
		return nil, err
	}

	return plain, nil
}

// checkPack reads a pack and checks the integrity of all blobs.
func checkPack(r *repository.Repository, id backend.ID) error {
	debug.Log("Checker.checkPack", "checking pack %v", id.Str())
	h := backend.Handle{Type: backend.Data, Name: id.String()}
	buf, err := backend.LoadAll(r.Backend(), h, nil)
	if err != nil {
		return err
	}

	hash := backend.Hash(buf)
	if !hash.Equal(id) {
		debug.Log("Checker.checkPack", "Pack ID does not match, want %v, got %v", id.Str(), hash.Str())
		return fmt.Errorf("Pack ID does not match, want %v, got %v", id.Str(), hash.Str())
	}

	unpacker, err := pack.NewUnpacker(r.Key(), bytes.NewReader(buf))
	if err != nil {
		return err
	}

	var errs []error
	for i, blob := range unpacker.Entries {
		debug.Log("Checker.checkPack", "  check blob %d: %v", i, blob.ID.Str())

		plainBuf := make([]byte, blob.Length)
		plainBuf, err = crypto.Decrypt(r.Key(), plainBuf, buf[blob.Offset:blob.Offset+blob.Length])
		if err != nil {
			debug.Log("Checker.checkPack", "  error decrypting blob %v: %v", blob.ID.Str(), err)
			errs = append(errs, fmt.Errorf("blob %v: %v", i, err))
			continue
		}

		hash := backend.Hash(plainBuf)
		if !hash.Equal(blob.ID) {
			debug.Log("Checker.checkPack", "  Blob ID does not match, want %v, got %v", blob.ID.Str(), hash.Str())
			errs = append(errs, fmt.Errorf("Blob ID does not match, want %v, got %v", blob.ID.Str(), hash.Str()))
			continue
		}
	}

	if len(errs) > 0 {
		return fmt.Errorf("pack %v contains %v errors: %v", id.Str(), len(errs), errs)
	}

	return nil
}

func store(t testing.TB, b backend.Backend, tpe backend.Type, data []byte) {
	id := backend.Hash(data)

	blob, err := b.Create()
	OK(t, err)

	_, err = blob.Write([]byte(data))
	OK(t, err)
	OK(t, blob.Finalize(tpe, id.String()))
}

func genTestContent() map[backend.ID][]byte {
	m := make(map[backend.ID][]byte)

	for _, length := range testContentLengths {
		buf := Random(int(length), int(length))
		id := backend.Hash(buf)
		m[id] = buf
		testMaxFileSize += length
	}

	return m
}

// LoadBlob tries to load and decrypt content identified by t and id from a
// pack from the backend, the result is stored in plaintextBuf, which must be
// large enough to hold the complete blob.
func (r *Repository) LoadBlob(t pack.BlobType, id backend.ID, plaintextBuf []byte) ([]byte, error) {
	debug.Log("Repo.LoadBlob", "load %v with id %v", t, id.Str())
	// lookup pack
	blob, err := r.idx.Lookup(id)
	if err != nil {
		debug.Log("Repo.LoadBlob", "id %v not found in index: %v", id.Str(), err)
		return nil, err
	}

	plaintextBufSize := uint(cap(plaintextBuf))
	if blob.PlaintextLength() > plaintextBufSize {
		return nil, fmt.Errorf("buf is too small, need %d more bytes", blob.PlaintextLength()-plaintextBufSize)
	}

	if blob.Type != t {
		debug.Log("Repo.LoadBlob", "wrong type returned for %v: wanted %v, got %v", id.Str(), t, blob.Type)
		return nil, fmt.Errorf("blob has wrong type %v (wanted: %v)", blob.Type, t)
	}

	debug.Log("Repo.LoadBlob", "id %v found: %v", id.Str(), blob)

	// load blob from pack
	rd, err := r.be.GetReader(backend.Data, blob.PackID.String(), blob.Offset, blob.Length)
	if err != nil {
		debug.Log("Repo.LoadBlob", "error loading blob %v: %v", blob, err)
		return nil, err
	}

	// make buffer that is large enough for the complete blob
	ciphertextBuf := make([]byte, blob.Length)
	_, err = io.ReadFull(rd, ciphertextBuf)
	if err != nil {
		return nil, err
	}

	err = rd.Close()
	if err != nil {
		return nil, err
	}

	// decrypt
	plaintextBuf, err = r.decryptTo(plaintextBuf, ciphertextBuf)
	if err != nil {
		return nil, err
	}

	// check hash
	if !backend.Hash(plaintextBuf).Equal(id) {
		return nil, errors.New("invalid data returned")
	}

	return plaintextBuf, nil
}

// LoadBlob tries to load and decrypt content identified by t and id from a
// pack from the backend, the result is stored in plaintextBuf, which must be
// large enough to hold the complete blob.
func (r *Repository) LoadBlob(t pack.BlobType, id backend.ID, plaintextBuf []byte) ([]byte, error) {
	debug.Log("Repo.LoadBlob", "load %v with id %v", t, id.Str())
	// lookup pack
	packID, tpe, offset, length, err := r.idx.Lookup(id)
	if err != nil {
		debug.Log("Repo.LoadBlob", "id %v not found in index: %v", id.Str(), err)
		return nil, err
	}

	if length > uint(cap(plaintextBuf))+crypto.Extension {
		return nil, fmt.Errorf("buf is too small, need %d more bytes", length-uint(cap(plaintextBuf))-crypto.Extension)
	}

	if tpe != t {
		debug.Log("Repo.LoadBlob", "wrong type returned for %v: wanted %v, got %v", id.Str(), t, tpe)
		return nil, fmt.Errorf("blob has wrong type %v (wanted: %v)", tpe, t)
	}

	debug.Log("Repo.LoadBlob", "id %v found in pack %v at offset %v (length %d)", id.Str(), packID.Str(), offset, length)

	// load blob from pack
	rd, err := r.be.GetReader(backend.Data, packID.String(), offset, length)
	if err != nil {
		debug.Log("Repo.LoadBlob", "error loading pack %v for %v: %v", packID.Str(), id.Str(), err)
		return nil, err
	}

	// make buffer that is large enough for the complete blob
	ciphertextBuf := make([]byte, length)
	_, err = io.ReadFull(rd, ciphertextBuf)
	if err != nil {
		return nil, err
	}

	err = rd.Close()
	if err != nil {
		return nil, err
	}

	// decrypt
	plaintextBuf, err = r.decryptTo(plaintextBuf, ciphertextBuf)
	if err != nil {
		return nil, err
	}

	// check hash
	if !backend.Hash(plaintextBuf).Equal(id) {
		return nil, errors.New("invalid data returned")
	}

	return plaintextBuf, nil
}

// LoadBlob tries to load and decrypt content identified by t and id from a
// pack from the backend, the result is stored in plaintextBuf, which must be
// large enough to hold the complete blob.
func (r *Repository) LoadBlob(t pack.BlobType, id backend.ID, plaintextBuf []byte) ([]byte, error) {
	debug.Log("Repo.LoadBlob", "load %v with id %v", t, id.Str())
	// lookup pack
	blob, err := r.idx.Lookup(id)
	if err != nil {
		debug.Log("Repo.LoadBlob", "id %v not found in index: %v", id.Str(), err)
		return nil, err
	}

	plaintextBufSize := uint(cap(plaintextBuf))
	if blob.PlaintextLength() > plaintextBufSize {
		debug.Log("Repo.LoadBlob", "need to expand buffer: want %d bytes, got %d",
			blob.PlaintextLength(), plaintextBufSize)
		plaintextBuf = make([]byte, blob.PlaintextLength())
	}

	if blob.Type != t {
		debug.Log("Repo.LoadBlob", "wrong type returned for %v: wanted %v, got %v", id.Str(), t, blob.Type)
		return nil, fmt.Errorf("blob has wrong type %v (wanted: %v)", blob.Type, t)
	}

	debug.Log("Repo.LoadBlob", "id %v found: %v", id.Str(), blob)

	// load blob from pack
	h := backend.Handle{Type: backend.Data, Name: blob.PackID.String()}
	ciphertextBuf := make([]byte, blob.Length)
	n, err := r.be.Load(h, ciphertextBuf, int64(blob.Offset))
	if err != nil {
		debug.Log("Repo.LoadBlob", "error loading blob %v: %v", blob, err)
		return nil, err
	}

	if uint(n) != blob.Length {
		debug.Log("Repo.LoadBlob", "error loading blob %v: wrong length returned, want %d, got %d",
			blob.Length, uint(n))
		return nil, errors.New("wrong length returned")
	}

	// decrypt
	plaintextBuf, err = r.decryptTo(plaintextBuf, ciphertextBuf)
	if err != nil {
		return nil, err
	}

	// check hash
	if !backend.Hash(plaintextBuf).Equal(id) {
		return nil, errors.New("invalid data returned")
	}

	return plaintextBuf, nil
}

// SaveAndEncrypt encrypts data and stores it to the backend as type t. If data is small
// enough, it will be packed together with other small blobs.
func (r *Repository) SaveAndEncrypt(t pack.BlobType, data []byte, id *backend.ID) (backend.ID, error) {
	if id == nil {
		// compute plaintext hash
		hashedID := backend.Hash(data)
		id = &hashedID
	}

	debug.Log("Repo.Save", "save id %v (%v, %d bytes)", id.Str(), t, len(data))

	// get buf from the pool
	ciphertext := getBuf()
	defer freeBuf(ciphertext)

	// encrypt blob
	ciphertext, err := r.Encrypt(ciphertext, data)
	if err != nil {
		return backend.ID{}, err
	}

	// add this id to the list of in-flight chunk ids.
	debug.Log("Repo.Save", "add %v to list of in-flight IDs", id.Str())
	err = r.idx.AddInFlight(*id)
	if err != nil {
		debug.Log("Repo.Save", "another goroutine is already working on %v (%v) does already exist", id.Str, t)
		return *id, nil
	}

	// find suitable packer and add blob
	packer, err := r.findPacker(uint(len(ciphertext)))
	if err != nil {
		r.idx.RemoveFromInFlight(*id)
		return backend.ID{}, err
	}

	// save ciphertext
	_, err = packer.Add(t, *id, bytes.NewReader(ciphertext))
	if err != nil {
		return backend.ID{}, err
	}

	// if the pack is not full enough and there are less than maxPackers
	// packers, put back to the list
	if packer.Size() < minPackSize && r.countPacker() < maxPackers {
		debug.Log("Repo.Save", "pack is not full enough (%d bytes)", packer.Size())
		r.insertPacker(packer)
		return *id, nil
	}

	// else write the pack to the backend
	return *id, r.savePacker(packer)
}

// SaveTreeJSON stores a tree in the repository.
func (arch *Archiver) SaveTreeJSON(item interface{}) (backend.ID, error) {
	data, err := json.Marshal(item)
	if err != nil {
		return nil, err
	}
	data = append(data, '\n')

	// check if tree has been saved before
	id := backend.Hash(data)
	if arch.repo.Index().Has(id) {
		return id, nil
	}

	return arch.repo.SaveJSON(pack.Tree, item)
}

// LoadBlob tries to load and decrypt content identified by t and id from a
// pack from the backend.
func (s *Repository) LoadBlob(t pack.BlobType, id backend.ID) ([]byte, error) {
	debug.Log("Repo.LoadBlob", "load %v with id %v", t, id.Str())
	// lookup pack
	packID, tpe, offset, length, err := s.idx.Lookup(id)
	if err != nil {
		debug.Log("Repo.LoadBlob", "id %v not found in index: %v", id.Str(), err)
		return nil, err
	}

	if tpe != t {
		debug.Log("Repo.LoadBlob", "wrong type returned for %v: wanted %v, got %v", id.Str(), t, tpe)
		return nil, fmt.Errorf("blob has wrong type %v (wanted: %v)", tpe, t)
	}

	debug.Log("Repo.LoadBlob", "id %v found in pack %v at offset %v (length %d)", id.Str(), packID.Str(), offset, length)

	// load blob from pack
	rd, err := s.be.GetReader(backend.Data, packID.String(), offset, length)
	if err != nil {
		debug.Log("Repo.LoadBlob", "error loading pack %v for %v: %v", packID.Str(), id.Str(), err)
		return nil, err
	}

	buf, err := ioutil.ReadAll(rd)
	if err != nil {
		return nil, err
	}

	err = rd.Close()
	if err != nil {
		return nil, err
	}

	// decrypt
	plain, err := s.Decrypt(buf)
	if err != nil {
		return nil, err
	}

	// check hash
	if !backend.Hash(plain).Equal(id) {
		return nil, errors.New("invalid data returned")
	}

	return plain, nil
}

func testWrite(b backend.Backend, t testing.TB) {
	length := rand.Intn(1<<23) + 2000

	data := make([]byte, length)
	_, err := io.ReadFull(crand.Reader, data)
	OK(t, err)
	id := backend.Hash(data)

	for i := 0; i < 10; i++ {
		blob, err := b.Create()
		OK(t, err)

		o := 0
		for o < len(data) {
			l := rand.Intn(len(data) - o)
			if len(data)-o < 20 {
				l = len(data) - o
			}

			n, err := blob.Write(data[o : o+l])
			OK(t, err)
			if n != l {
				t.Fatalf("wrong number of bytes written, want %v, got %v", l, n)
			}

			o += l
		}

		name := fmt.Sprintf("%s-%d", id, i)
		OK(t, blob.Finalize(backend.Data, name))

		rd, err := b.Get(backend.Data, name)
		OK(t, err)

		buf, err := ioutil.ReadAll(rd)
		OK(t, err)

		if len(buf) != len(data) {
			t.Fatalf("number of bytes does not match, want %v, got %v", len(data), len(buf))
		}

		if !bytes.Equal(buf, data) {
			t.Fatalf("data not equal")
		}
	}
}