restic/server/server.go

607 lines
14 KiB
Go

package server
import (
"bytes"
"crypto/sha256"
"encoding/json"
"errors"
"fmt"
"io"
"io/ioutil"
"sync"
"github.com/restic/restic/backend"
"github.com/restic/restic/chunker"
"github.com/restic/restic/debug"
"github.com/restic/restic/pack"
)
type Server struct {
be backend.Backend
key *Key
idx *Index
pm sync.Mutex
packs []*pack.Packer
}
func NewServer(be backend.Backend) *Server {
return &Server{
be: be,
idx: NewIndex(),
}
}
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 id from the
// backend.
func (s *Server) Load(t backend.Type, id backend.ID) ([]byte, error) {
debug.Log("Server.Load", "load %v with id %v", t, id.Str())
// load blob from pack
rd, err := s.be.Get(t, id.String())
if err != nil {
debug.Log("Server.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 := s.Decrypt(buf)
if err != nil {
return nil, err
}
return plain, nil
}
// LoadBlob tries to load and decrypt content identified by t and id from a
// pack from the backend.
func (s *Server) LoadBlob(t pack.BlobType, id backend.ID) ([]byte, error) {
debug.Log("Server.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("Server.LoadBlob", "id %v not found in index: %v", id.Str(), err)
return nil, err
}
if tpe != t {
debug.Log("Server.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("Server.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("Server.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
}
// LoadJSONEncrypted decrypts the data and afterwards calls json.Unmarshal on
// the item.
func (s *Server) LoadJSONEncrypted(t backend.Type, id backend.ID, item interface{}) error {
// load blob from backend
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
}
// LoadJSONPack calls LoadBlob() to load a blob from the backend, decrypt the
// data and afterwards call json.Unmarshal on the item.
func (s *Server) LoadJSONPack(t pack.BlobType, id backend.ID, item interface{}) error {
// lookup pack
packID, _, offset, length, err := s.idx.Lookup(id)
if err != nil {
return err
}
// load blob from pack
rd, err := s.be.GetReader(backend.Data, packID.String(), offset, length)
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
}
const minPackSize = 4 * chunker.MiB
const maxPackSize = 16 * chunker.MiB
const maxPackers = 200
// findPacker returns a packer for a new blob of size bytes. Either a new one is
// created or one is returned that already has some blobs.
func (s *Server) findPacker(size uint) (*pack.Packer, error) {
s.pm.Lock()
defer s.pm.Unlock()
// search for a suitable packer
if len(s.packs) > 0 {
debug.Log("Server.findPacker", "searching packer for %d bytes\n", size)
for i, p := range s.packs {
if p.Size()+size < maxPackSize {
debug.Log("Server.findPacker", "found packer %v", p)
// remove from list
s.packs = append(s.packs[:i], s.packs[i+1:]...)
return p, nil
}
}
}
// no suitable packer found, return new
blob, err := s.be.Create()
if err != nil {
return nil, err
}
debug.Log("Server.findPacker", "create new pack %p", blob)
return pack.NewPacker(s.key.Master(), blob), nil
}
// insertPacker appends p to s.packs.
func (s *Server) insertPacker(p *pack.Packer) {
s.pm.Lock()
defer s.pm.Unlock()
s.packs = append(s.packs, p)
debug.Log("Server.insertPacker", "%d packers\n", len(s.packs))
}
// savePacker stores p in the backend.
func (s *Server) savePacker(p *pack.Packer) error {
debug.Log("Server.savePacker", "save packer with %d blobs\n", p.Count())
_, err := p.Finalize()
if err != nil {
return err
}
// move file to the final location
sid := p.ID()
err = p.Writer().(backend.Blob).Finalize(backend.Data, sid.String())
if err != nil {
debug.Log("Server.savePacker", "blob Finalize() error: %v", err)
return err
}
debug.Log("Server.savePacker", "saved as %v", sid.Str())
// update blobs in the index
for _, b := range p.Blobs() {
debug.Log("Server.savePacker", " updating blob %v to pack %v", b.ID.Str(), sid.Str())
s.idx.Store(b.Type, b.ID, sid, b.Offset, uint(b.Length))
}
return nil
}
// countPacker returns the number of open (unfinished) packers.
func (s *Server) countPacker() int {
s.pm.Lock()
defer s.pm.Unlock()
return len(s.packs)
}
// Save 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 (s *Server) Save(t pack.BlobType, data []byte, id backend.ID) (backend.ID, error) {
if id == nil {
// compute plaintext hash
id = backend.Hash(data)
}
debug.Log("Server.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 := s.Encrypt(ciphertext, data)
if err != nil {
return nil, err
}
// find suitable packer and add blob
packer, err := s.findPacker(uint(len(ciphertext)))
if err != nil {
return nil, err
}
// save ciphertext
packer.Add(t, id, bytes.NewReader(ciphertext))
// add this id to the index, although we don't know yet in which pack it
// will be saved, the entry will be updated when the pack is written.
s.idx.Store(t, id, nil, 0, 0)
debug.Log("Server.Save", "saving stub for %v (%v) in index", id.Str, t)
// if the pack is not full enough and there are less than maxPackers
// packers, put back to the list
if packer.Size() < minPackSize && s.countPacker() < maxPackers {
debug.Log("Server.Save", "pack is not full enough (%d bytes)", packer.Size())
s.insertPacker(packer)
return id, nil
}
// else write the pack to the backend
return id, s.savePacker(packer)
}
// SaveFrom encrypts data read from rd and stores it in a pack in the backend as type t.
func (s *Server) SaveFrom(t pack.BlobType, id backend.ID, length uint, rd io.Reader) error {
debug.Log("Server.SaveFrom", "save id %v (%v, %d bytes)", id.Str(), t, length)
if id == nil {
return errors.New("id is nil")
}
buf, err := ioutil.ReadAll(rd)
if err != nil {
return err
}
_, err = s.Save(t, buf, id)
if err != nil {
return err
}
return nil
}
// SaveJSON serialises item as JSON and encrypts and saves it in a pack in the
// backend as type t.
func (s *Server) SaveJSON(t pack.BlobType, item interface{}) (backend.ID, error) {
debug.Log("Server.SaveJSON", "save %v blob", t)
buf := getBuf()[:0]
defer freeBuf(buf)
wr := bytes.NewBuffer(buf)
enc := json.NewEncoder(wr)
err := enc.Encode(item)
if err != nil {
return nil, fmt.Errorf("json.Encode: %v", err)
}
buf = wr.Bytes()
return s.Save(t, buf, nil)
}
// SaveJSONUnpacked serialises item as JSON and encrypts and saves it in the
// backend as type t, without a pack. It returns the storage hash.
func (s *Server) SaveJSONUnpacked(t backend.Type, item interface{}) (backend.ID, error) {
// create blob
blob, err := s.be.Create()
if err != nil {
return nil, err
}
debug.Log("Server.SaveJSONUnpacked", "create new pack %p", blob)
// hash
hw := backend.NewHashingWriter(blob, sha256.New())
// encrypt blob
ewr := s.key.EncryptTo(hw)
enc := json.NewEncoder(ewr)
err = enc.Encode(item)
if err != nil {
return nil, fmt.Errorf("json.Encode: %v", err)
}
err = ewr.Close()
if err != nil {
return nil, err
}
// finalize blob in the backend
sid := backend.ID(hw.Sum(nil))
err = blob.Finalize(t, sid.String())
if err != nil {
return nil, err
}
return sid, nil
}
// Flush saves all remaining packs.
func (s *Server) Flush() error {
s.pm.Lock()
defer s.pm.Unlock()
debug.Log("Server.Flush", "manually flushing %d packs", len(s.packs))
for _, p := range s.packs {
err := s.savePacker(p)
if err != nil {
return err
}
}
s.packs = s.packs[:0]
return nil
}
// Returns the backend used for this server.
func (s *Server) Backend() backend.Backend {
return s.be
}
// Returns the index of this server.
func (s *Server) Index() *Index {
return s.idx
}
// SetIndex instructs the server to use the given index.
func (s *Server) SetIndex(i *Index) {
s.idx = i
}
// SaveIndex saves all new packs in the index in the backend, returned is the
// storage ID.
func (s *Server) SaveIndex() (backend.ID, error) {
debug.Log("Server.SaveIndex", "Saving index")
// create blob
blob, err := s.be.Create()
if err != nil {
return nil, err
}
debug.Log("Server.SaveIndex", "create new pack %p", blob)
// hash
hw := backend.NewHashingWriter(blob, sha256.New())
// encrypt blob
ewr := s.key.EncryptTo(hw)
err = s.idx.Encode(ewr)
if err != nil {
return nil, err
}
err = ewr.Close()
if err != nil {
return nil, err
}
// finalize blob in the backend
sid := backend.ID(hw.Sum(nil))
err = blob.Finalize(backend.Index, sid.String())
if err != nil {
return nil, err
}
debug.Log("Server.SaveIndex", "Saved index as %v", sid.Str())
return sid, nil
}
// LoadIndex loads all index files from the backend and merges them with the
// current index.
func (s *Server) LoadIndex() error {
debug.Log("Server.LoadIndex", "Loading index")
done := make(chan struct{})
defer close(done)
for id := range s.be.List(backend.Index, done) {
err := s.loadIndex(id)
if err != nil {
return err
}
}
return nil
}
// loadIndex loads the index id and merges it with the currently used index.
func (s *Server) loadIndex(id string) error {
debug.Log("Server.loadIndex", "Loading index %v", id[:8])
before := len(s.idx.pack)
rd, err := s.be.Get(backend.Index, id)
defer rd.Close()
if err != nil {
return err
}
// decrypt
decryptRd, err := s.key.DecryptFrom(rd)
defer decryptRd.Close()
if err != nil {
return err
}
idx, err := DecodeIndex(decryptRd)
if err != nil {
debug.Log("Server.loadIndex", "error while decoding index %v: %v", id, err)
return err
}
s.idx.Merge(idx)
after := len(s.idx.pack)
debug.Log("Server.loadIndex", "Loaded index %v, added %v blobs", id[:8], after-before)
return nil
}
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(nil, 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
}
// Count returns the number of blobs of a given type in the backend.
func (s *Server) Count(t backend.Type) (n uint) {
for _ = range s.be.List(t, nil) {
n++
}
return
}
// Proxy methods to backend
func (s *Server) Get(t backend.Type, name string) (io.ReadCloser, error) {
return s.be.Get(t, name)
}
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()
}