restic/server.go

411 lines
8.9 KiB
Go

package restic
import (
"compress/zlib"
"crypto/sha256"
"encoding/json"
"errors"
"fmt"
"io"
"sync"
"github.com/restic/restic/backend"
"github.com/restic/restic/debug"
)
type Server struct {
be backend.Backend
key *Key
}
func NewServer(be backend.Backend) Server {
return Server{be: be}
}
func NewServerWithKey(be backend.Backend, key *Key) Server {
return Server{be: be, key: key}
}
// Each lists all entries of type t in the backend and calls function f() with
// the id and data.
func (s Server) Each(t backend.Type, f func(id backend.ID, data []byte, err error)) error {
return backend.Each(s.be, t, f)
}
// Each lists all entries of type t in the backend and calls function f() with
// the id.
func (s Server) EachID(t backend.Type, f func(backend.ID)) error {
return backend.EachID(s.be, t, f)
}
// Find loads the list of all blobs of type t and searches for IDs which start
// with prefix. If none is found, nil and ErrNoIDPrefixFound is returned. If
// more than one is found, nil and ErrMultipleIDMatches is returned.
func (s Server) Find(t backend.Type, prefix string) (backend.ID, error) {
return backend.Find(s.be, t, prefix)
}
// FindSnapshot takes a string and tries to find a snapshot whose ID matches
// the string as closely as possible.
func (s Server) FindSnapshot(id string) (backend.ID, error) {
return backend.FindSnapshot(s.be, id)
}
// PrefixLength returns the number of bytes required so that all prefixes of
// all IDs of type t are unique.
func (s Server) PrefixLength(t backend.Type) (int, error) {
return backend.PrefixLength(s.be, t)
}
// Load tries to load and decrypt content identified by t and blob from the backend.
func (s Server) Load(t backend.Type, blob Blob) ([]byte, error) {
// load data
buf, err := s.Get(t, blob.Storage)
if err != nil {
return nil, err
}
// check length
if len(buf) != int(blob.StorageSize) {
return nil, errors.New("Invalid storage length")
}
// decrypt
buf, err = s.Decrypt(buf)
if err != nil {
return nil, err
}
// check length
if len(buf) != int(blob.Size) {
return nil, errors.New("Invalid length")
}
// check SHA256 sum
id := backend.Hash(buf)
if !blob.ID.Equal(id) {
return nil, fmt.Errorf("load %v: expected plaintext hash %v, got %v", blob.Storage, blob.ID, id)
}
return buf, nil
}
// Load tries to load and decrypt content identified by t and id from the backend.
func (s Server) LoadID(t backend.Type, storageID backend.ID) ([]byte, error) {
// load data
buf, err := s.Get(t, storageID)
if err != nil {
return nil, err
}
// decrypt
buf, err = s.Decrypt(buf)
if err != nil {
return nil, err
}
return buf, nil
}
// LoadJSON calls Load() to get content from the backend and afterwards calls
// json.Unmarshal on the item.
func (s Server) LoadJSON(t backend.Type, blob Blob, item interface{}) error {
return s.LoadJSONID(t, blob.Storage, item)
}
// LoadJSONID calls Load() to get content from the backend and afterwards calls
// json.Unmarshal on the item.
func (s Server) LoadJSONID(t backend.Type, storageID backend.ID, item interface{}) error {
// read
rd, err := s.GetReader(t, storageID)
if err != nil {
return err
}
// decrypt
decryptRd, err := s.key.DecryptFrom(rd)
if err != nil {
return err
}
// unzip
unzipRd, err := zlib.NewReader(decryptRd)
if err != nil {
return err
}
// decode
decoder := json.NewDecoder(unzipRd)
err = decoder.Decode(item)
if err != nil {
return err
}
return nil
}
// Save encrypts data and stores it to the backend as type t.
func (s Server) Save(t backend.Type, data []byte, id backend.ID) (Blob, error) {
if id == nil {
// compute plaintext hash
id = backend.Hash(data)
}
// create a new blob
blob := Blob{
ID: id,
Size: uint64(len(data)),
}
var ciphertext []byte
// if the data is small enough, use a slice from the pool
if len(data) <= maxCiphertextSize-ivSize-hmacSize {
ciphertext = GetChunkBuf("ch.Save()")
defer FreeChunkBuf("ch.Save()", ciphertext)
} else {
l := len(data) + ivSize + hmacSize
debug.Log("Server.Save", "create large slice of %d bytes for ciphertext", l)
// use a new slice
ciphertext = make([]byte, l)
}
// encrypt blob
n, err := s.Encrypt(ciphertext, data)
if err != nil {
return Blob{}, err
}
ciphertext = ciphertext[:n]
// save blob
backendBlob, err := s.Create(t)
if err != nil {
return Blob{}, err
}
_, err = backendBlob.Write(ciphertext)
if err != nil {
return Blob{}, err
}
err = backendBlob.Close()
if err != nil {
return Blob{}, err
}
sid, err := backendBlob.ID()
if err != nil {
return Blob{}, err
}
blob.Storage = sid
blob.StorageSize = uint64(len(ciphertext))
return blob, nil
}
// SaveFrom encrypts data read from rd and stores it to the backend as type t.
func (s Server) SaveFrom(t backend.Type, id backend.ID, length uint, rd io.Reader) (Blob, error) {
if id == nil {
return Blob{}, errors.New("id is nil")
}
backendBlob, err := s.Create(t)
if err != nil {
return Blob{}, err
}
encWr := s.key.EncryptTo(backendBlob)
_, err = io.Copy(encWr, rd)
if err != nil {
return Blob{}, err
}
// finish encryption
err = encWr.Close()
if err != nil {
return Blob{}, fmt.Errorf("EncryptedWriter.Close(): %v", err)
}
// finish backend blob
err = backendBlob.Close()
if err != nil {
return Blob{}, fmt.Errorf("backend.Blob.Close(): %v", err)
}
storageID, err := backendBlob.ID()
if err != nil {
return Blob{}, fmt.Errorf("backend.Blob.ID(): %v", err)
}
return Blob{
ID: id,
Size: uint64(length),
Storage: storageID,
StorageSize: uint64(backendBlob.Size()),
}, nil
}
var zWriterPool = sync.Pool{
New: func() interface{} {
return zlib.NewWriter(nil)
},
}
// SaveJSON serialises item as JSON and encrypts and saves it in the backend as
// type t.
func (s Server) SaveJSON(t backend.Type, item interface{}) (Blob, error) {
backendBlob, err := s.Create(t)
if err != nil {
return Blob{}, fmt.Errorf("Create: %v", err)
}
encWr := s.key.EncryptTo(backendBlob)
wr := zWriterPool.Get().(*zlib.Writer)
defer zWriterPool.Put(wr)
wr.Reset(encWr)
if err != nil {
return Blob{}, fmt.Errorf("zlib.NewWriter: %v", err)
}
hw := backend.NewHashingWriter(wr, sha256.New())
enc := json.NewEncoder(hw)
err = enc.Encode(item)
if err != nil {
return Blob{}, fmt.Errorf("json.NewEncoder: %v", err)
}
// flush zlib writer
err = wr.Close()
if err != nil {
return Blob{}, fmt.Errorf("zlib.Writer.Close(): %v", err)
}
// finish encryption
err = encWr.Close()
if err != nil {
return Blob{}, fmt.Errorf("EncryptedWriter.Close(): %v", err)
}
// finish backend blob
err = backendBlob.Close()
if err != nil {
return Blob{}, fmt.Errorf("backend.Blob.Close(): %v", err)
}
id := hw.Sum(nil)
storageID, err := backendBlob.ID()
if err != nil {
return Blob{}, fmt.Errorf("backend.Blob.ID(): %v", err)
}
return Blob{
ID: id,
Size: uint64(hw.Size()),
Storage: storageID,
StorageSize: uint64(backendBlob.Size()),
}, nil
}
// Returns the backend used for this server.
func (s Server) Backend() backend.Backend {
return s.be
}
func (s *Server) SearchKey(password string) error {
key, err := SearchKey(*s, password)
if err != nil {
return err
}
s.key = key
return nil
}
func (s Server) Decrypt(ciphertext []byte) ([]byte, error) {
if s.key == nil {
return nil, errors.New("key for server not set")
}
return s.key.Decrypt([]byte{}, ciphertext)
}
func (s Server) Encrypt(ciphertext, plaintext []byte) (int, error) {
if s.key == nil {
return 0, errors.New("key for server not set")
}
return s.key.Encrypt(ciphertext, plaintext)
}
func (s Server) Key() *Key {
return s.key
}
// Each calls Each() with the given parameters, Decrypt() on the ciphertext
// and, on successful decryption, f with the plaintext.
func (s Server) EachDecrypted(t backend.Type, f func(backend.ID, []byte, error)) error {
if s.key == nil {
return errors.New("key for server not set")
}
return s.Each(t, func(id backend.ID, data []byte, e error) {
if e != nil {
f(id, nil, e)
return
}
buf, err := s.key.Decrypt([]byte{}, data)
if err != nil {
f(id, nil, err)
return
}
f(id, buf, nil)
})
}
// Proxy methods to backend
func (s Server) List(t backend.Type) (backend.IDs, error) {
return s.be.List(t)
}
func (s Server) Get(t backend.Type, id backend.ID) ([]byte, error) {
return s.be.Get(t, id)
}
func (s Server) GetReader(t backend.Type, id backend.ID) (io.ReadCloser, error) {
return s.be.GetReader(t, id)
}
func (s Server) Create(t backend.Type) (backend.Blob, error) {
return s.be.Create(t)
}
func (s Server) Test(t backend.Type, id backend.ID) (bool, error) {
return s.be.Test(t, id)
}
func (s Server) Remove(t backend.Type, id backend.ID) error {
return s.be.Remove(t, id)
}
func (s Server) Close() error {
return s.be.Close()
}
func (s Server) Delete() error {
if b, ok := s.be.(backend.Deleter); ok {
return b.Delete()
}
return errors.New("Delete() called for backend that does not implement this method")
}