restic/server.go

419 lines
9.2 KiB
Go

package restic
import (
"crypto/sha256"
"encoding/json"
"errors"
"fmt"
"io"
"io/ioutil"
"sync"
"github.com/restic/restic/backend"
"github.com/restic/restic/chunker"
"github.com/restic/restic/crypto"
"github.com/restic/restic/debug"
)
type Server struct {
be backend.Backend
key *Key
}
func NewServer(be backend.Backend) Server {
return Server{be: be}
}
func (s *Server) SetKey(k *Key) {
s.key = k
}
// ChunkerPolynomial returns the secret polynomial used for content defined chunking.
func (s *Server) ChunkerPolynomial() chunker.Pol {
return chunker.Pol(s.key.Master().ChunkerPolynomial)
}
// Find loads the list of all blobs of type t and searches for names 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) (string, 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(name string) (string, error) {
return backend.FindSnapshot(s.be, name)
}
// 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. If the blob specifies an ID, the decrypted plaintext is checked
// against this ID. The same goes for blob.Size and blob.StorageSize: If they
// are set to a value > 0, this value is checked.
func (s Server) Load(t backend.Type, blob Blob) ([]byte, error) {
// load data
rd, err := s.be.Get(t, blob.Storage.String())
if err != nil {
return nil, err
}
buf, err := ioutil.ReadAll(rd)
if err != nil {
return nil, err
}
// check hash
if !backend.Hash(buf).Equal(blob.Storage) {
return nil, errors.New("invalid data returned")
}
// check length
if blob.StorageSize > 0 && 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 blob.Size > 0 && len(buf) != int(blob.Size) {
return nil, errors.New("Invalid length")
}
// check SHA256 sum
if blob.ID != nil {
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) {
return s.Load(t, Blob{Storage: storageID})
}
// 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 {
buf, err := s.Load(t, blob)
if err != nil {
return err
}
return json.Unmarshal(buf, 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, id backend.ID, item interface{}) error {
// read
rd, err := s.be.Get(t, id.String())
if err != nil {
return err
}
defer rd.Close()
// decrypt
decryptRd, err := s.key.DecryptFrom(rd)
defer decryptRd.Close()
if err != nil {
return err
}
// decode
decoder := json.NewDecoder(decryptRd)
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-crypto.Extension {
ciphertext = GetChunkBuf("ch.Save()")
defer FreeChunkBuf("ch.Save()", ciphertext)
} else {
l := len(data) + crypto.Extension
debug.Log("Server.Save", "create large slice of %d bytes for ciphertext", l)
// use a new slice
ciphertext = make([]byte, l)
}
// encrypt blob
ciphertext, err := s.Encrypt(ciphertext, data)
if err != nil {
return Blob{}, err
}
// compute ciphertext hash
sid := backend.Hash(ciphertext)
// save blob
backendBlob, err := s.be.Create()
if err != nil {
return Blob{}, err
}
_, err = backendBlob.Write(ciphertext)
if err != nil {
return Blob{}, err
}
err = backendBlob.Finalize(t, sid.String())
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.be.Create()
if err != nil {
return Blob{}, err
}
hw := backend.NewHashingWriter(backendBlob, sha256.New())
encWr := s.key.EncryptTo(hw)
_, 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
sid := backend.ID(hw.Sum(nil))
err = backendBlob.Finalize(t, sid.String())
if err != nil {
return Blob{}, fmt.Errorf("backend.Blob.Close(): %v", err)
}
return Blob{
ID: id,
Size: uint64(length),
Storage: sid,
StorageSize: uint64(backendBlob.Size()),
}, 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.be.Create()
if err != nil {
return Blob{}, fmt.Errorf("Create: %v", err)
}
storagehw := backend.NewHashingWriter(backendBlob, sha256.New())
encWr := s.key.EncryptTo(storagehw)
plainhw := backend.NewHashingWriter(encWr, sha256.New())
enc := json.NewEncoder(plainhw)
err = enc.Encode(item)
if err != nil {
return Blob{}, fmt.Errorf("json.NewEncoder: %v", err)
}
// finish encryption
err = encWr.Close()
if err != nil {
return Blob{}, fmt.Errorf("EncryptedWriter.Close(): %v", err)
}
// finish backend blob
sid := backend.ID(storagehw.Sum(nil))
err = backendBlob.Finalize(t, sid.String())
if err != nil {
return Blob{}, fmt.Errorf("backend.Blob.Close(): %v", err)
}
id := backend.ID(plainhw.Sum(nil))
return Blob{
ID: id,
Size: uint64(plainhw.Size()),
Storage: sid,
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) ([]byte, error) {
if s.key == nil {
return nil, errors.New("key for server not set")
}
return s.key.Encrypt(ciphertext, plaintext)
}
func (s Server) Key() *Key {
return s.key
}
type ServerStats struct {
Blobs, Trees uint
}
// Stats returns statistics for this backend and the server.
func (s Server) Stats() (ServerStats, error) {
blobs := backend.NewIDSet()
// load all trees, in parallel
worker := func(wg *sync.WaitGroup, b <-chan Blob) {
for blob := range b {
tree, err := LoadTree(s, blob)
// ignore error and advance to next tree
if err != nil {
return
}
for _, id := range tree.Map.StorageIDs() {
blobs.Insert(id)
}
}
wg.Done()
}
blobCh := make(chan Blob)
// start workers
var wg sync.WaitGroup
for i := 0; i < maxConcurrency; i++ {
wg.Add(1)
go worker(&wg, blobCh)
}
// list ids
trees := 0
done := make(chan struct{})
defer close(done)
for name := range s.List(backend.Tree, done) {
trees++
id, err := backend.ParseID(name)
if err != nil {
debug.Log("Server.Stats", "unable to parse name %v as id: %v", name, err)
continue
}
blobCh <- Blob{Storage: id}
}
close(blobCh)
// wait for workers
wg.Wait()
return ServerStats{Blobs: uint(blobs.Len()), Trees: uint(trees)}, nil
}
// Count returns the number of blobs of a given type in the backend.
func (s Server) Count(t backend.Type) (n int) {
for _ = range s.List(t, nil) {
n++
}
return
}
// Proxy methods to backend
func (s Server) List(t backend.Type, done <-chan struct{}) <-chan string {
return s.be.List(t, done)
}
func (s Server) Test(t backend.Type, name string) (bool, error) {
return s.be.Test(t, name)
}
func (s Server) Remove(t backend.Type, name string) error {
return s.be.Remove(t, name)
}
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")
}
func (s Server) ID() string {
return s.be.ID()
}
func (s Server) Location() string {
return s.be.Location()
}