package transformer import ( "crypto/sha256" "fmt" "hash" "io" "github.com/nspcc-dev/neofs-sdk-go/checksum" "github.com/nspcc-dev/neofs-sdk-go/object" oid "github.com/nspcc-dev/neofs-sdk-go/object/id" "github.com/nspcc-dev/tzhash/tz" ) type payloadSizeLimiter struct { maxSize, written uint64 withoutHomomorphicHash bool targetInit func() ObjectTarget target ObjectTarget current, parent *object.Object currentHashers, parentHashers []*payloadChecksumHasher previous []oid.ID chunkWriter io.Writer splitID *object.SplitID parAttrs []object.Attribute } type payloadChecksumHasher struct { hasher hash.Hash checksumWriter func([]byte) } // NewPayloadSizeLimiter returns ObjectTarget instance that restricts payload length // of the writing object and writes generated objects to targets from initializer. // // Calculates and adds homomorphic hash to resulting objects only if withoutHomomorphicHash // is false. // // Objects w/ payload size less or equal than max size remain untouched. func NewPayloadSizeLimiter(maxSize uint64, withoutHomomorphicHash bool, targetInit TargetInitializer) ObjectTarget { return &payloadSizeLimiter{ maxSize: maxSize, withoutHomomorphicHash: withoutHomomorphicHash, targetInit: targetInit, splitID: object.NewSplitID(), } } func (s *payloadSizeLimiter) WriteHeader(hdr *object.Object) error { s.current = fromObject(hdr) s.initialize() return nil } func (s *payloadSizeLimiter) Write(p []byte) (int, error) { if err := s.writeChunk(p); err != nil { return 0, err } return len(p), nil } func (s *payloadSizeLimiter) Close() (*AccessIdentifiers, error) { return s.release(true) } func (s *payloadSizeLimiter) initialize() { // if it is an object after the 1st if ln := len(s.previous); ln > 0 { // initialize parent object once (after 1st object) if ln == 1 { s.detachParent() } // set previous object to the last previous identifier s.current.SetPreviousID(s.previous[ln-1]) } s.initializeCurrent() } func fromObject(obj *object.Object) *object.Object { cnr, _ := obj.ContainerID() res := object.New() res.SetContainerID(cnr) res.SetOwnerID(obj.OwnerID()) res.SetAttributes(obj.Attributes()...) res.SetType(obj.Type()) // obj.SetSplitID creates splitHeader but we don't need to do it in case // of small objects, so we should make nil check. if obj.SplitID() != nil { res.SetSplitID(obj.SplitID()) } return res } func (s *payloadSizeLimiter) initializeCurrent() { // initialize current object target s.target = s.targetInit() // create payload hashers s.currentHashers = payloadHashersForObject(s.current, s.withoutHomomorphicHash) // compose multi-writer from target and all payload hashers ws := make([]io.Writer, 0, 1+len(s.currentHashers)+len(s.parentHashers)) ws = append(ws, s.target) for i := range s.currentHashers { ws = append(ws, s.currentHashers[i].hasher) } for i := range s.parentHashers { ws = append(ws, s.parentHashers[i].hasher) } s.chunkWriter = io.MultiWriter(ws...) } func payloadHashersForObject(obj *object.Object, withoutHomomorphicHash bool) []*payloadChecksumHasher { hashers := make([]*payloadChecksumHasher, 0, 2) hashers = append(hashers, &payloadChecksumHasher{ hasher: sha256.New(), checksumWriter: func(binChecksum []byte) { if ln := len(binChecksum); ln != sha256.Size { panic(fmt.Sprintf("wrong checksum length: expected %d, has %d", sha256.Size, ln)) } csSHA := [sha256.Size]byte{} copy(csSHA[:], binChecksum) var cs checksum.Checksum cs.SetSHA256(csSHA) obj.SetPayloadChecksum(cs) }, }) if !withoutHomomorphicHash { hashers = append(hashers, &payloadChecksumHasher{ hasher: tz.New(), checksumWriter: func(binChecksum []byte) { if ln := len(binChecksum); ln != tz.Size { panic(fmt.Sprintf("wrong checksum length: expected %d, has %d", tz.Size, ln)) } csTZ := [tz.Size]byte{} copy(csTZ[:], binChecksum) var cs checksum.Checksum cs.SetTillichZemor(csTZ) obj.SetPayloadHomomorphicHash(cs) }, }) } return hashers } func (s *payloadSizeLimiter) release(finalize bool) (*AccessIdentifiers, error) { // Arg finalize is true only when called from Close method. // We finalize parent and generate linking objects only if it is more // than 1 object in split-chain. withParent := finalize && len(s.previous) > 0 if withParent { writeHashes(s.parentHashers) s.parent.SetPayloadSize(s.written) s.current.SetParent(s.parent) } // release current object writeHashes(s.currentHashers) // release current, get its id if err := s.target.WriteHeader(s.current); err != nil { return nil, fmt.Errorf("could not write header: %w", err) } ids, err := s.target.Close() if err != nil { return nil, fmt.Errorf("could not close target: %w", err) } // save identifier of the released object s.previous = append(s.previous, ids.SelfID()) if withParent { // generate and release linking object s.initializeLinking(ids.Parent()) s.initializeCurrent() if _, err := s.release(false); err != nil { return nil, fmt.Errorf("could not release linking object: %w", err) } } return ids, nil } func writeHashes(hashers []*payloadChecksumHasher) { for i := range hashers { hashers[i].checksumWriter(hashers[i].hasher.Sum(nil)) } } func (s *payloadSizeLimiter) initializeLinking(parHdr *object.Object) { s.current = fromObject(s.current) s.current.SetParent(parHdr) s.current.SetChildren(s.previous...) s.current.SetSplitID(s.splitID) } func (s *payloadSizeLimiter) writeChunk(chunk []byte) error { // statement is true if the previous write of bytes reached exactly the boundary. if s.written > 0 && s.written%s.maxSize == 0 { if s.written == s.maxSize { s.prepareFirstChild() } // we need to release current object if _, err := s.release(false); err != nil { return fmt.Errorf("could not release object: %w", err) } // initialize another object s.initialize() } var ( ln = uint64(len(chunk)) cut = ln leftToEdge = s.maxSize - s.written%s.maxSize ) // write bytes no further than the boundary of the current object if ln > leftToEdge { cut = leftToEdge } if _, err := s.chunkWriter.Write(chunk[:cut]); err != nil { return fmt.Errorf("could not write chunk to target: %w", err) } // increase written bytes counter s.written += cut // if there are more bytes in buffer we call method again to start filling another object if ln > leftToEdge { return s.writeChunk(chunk[cut:]) } return nil } func (s *payloadSizeLimiter) prepareFirstChild() { // initialize split header with split ID on first object in chain s.current.InitRelations() s.current.SetSplitID(s.splitID) // cut source attributes s.parAttrs = s.current.Attributes() s.current.SetAttributes() // attributes will be added to parent in detachParent } func (s *payloadSizeLimiter) detachParent() { s.parent = s.current s.current = fromObject(s.parent) s.parent.ResetRelations() s.parent.SetSignature(nil) s.parentHashers = s.currentHashers // return source attributes s.parent.SetAttributes(s.parAttrs...) }