api/data/info.go

@@ -45,6 +45,7 @@ type (
 		Created       time.Time
 		CreationEpoch uint64
 		HashSum       string
+		MD5Sum        string
 		Owner         user.ID
 		Headers       map[string]string
 	}
@@ -81,12 +82,12 @@ type (
 )
 
 // NotificationInfoFromObject creates new NotificationInfo from ObjectInfo.
-func NotificationInfoFromObject(objInfo *ObjectInfo) *NotificationInfo {
+func NotificationInfoFromObject(objInfo *ObjectInfo, md5Enabled bool) *NotificationInfo {
 	return &NotificationInfo{
 		Name:    objInfo.Name,
 		Version: objInfo.VersionID(),
 		Size:    objInfo.Size,
-		HashSum: objInfo.HashSum,
+		HashSum: objInfo.ETag(md5Enabled),
 	}
 }
 
@@ -115,6 +116,13 @@ func (o *ObjectInfo) Address() oid.Address {
 	return addr
 }
 
+func (o *ObjectInfo) ETag(md5Enabled bool) string {
+	if md5Enabled && len(o.MD5Sum) > 0 {
+		return o.MD5Sum
+	}
+	return o.HashSum
+}
+
 func (b BucketSettings) Unversioned() bool {
 	return b.Versioning == VersioningUnversioned
 }

api/data/tree.go

@@ -56,6 +56,7 @@ type BaseNodeVersion struct {
 	Timestamp uint64
 	Size      uint64
 	ETag      string
+	MD5       string
 	FilePath  string
 }
 
@@ -86,14 +87,23 @@ type PartInfo struct {
 	OID      oid.ID    `json:"oid"`
 	Size     uint64    `json:"size"`
 	ETag     string    `json:"etag"`
+	MD5      string    `json:"md5"`
 	Created  time.Time `json:"created"`
 }
 
 // ToHeaderString form short part representation to use in S3-Completed-Parts header.
 func (p *PartInfo) ToHeaderString() string {
+	// ETag value contains SHA256 checksum which is used while getting object parts attributes.
 	return strconv.Itoa(p.Number) + "-" + strconv.FormatUint(p.Size, 10) + "-" + p.ETag
 }
 
+func (p *PartInfo) GetETag(md5Enabled bool) string {
+	if md5Enabled && len(p.MD5) > 0 {
+		return p.MD5
+	}
+	return p.ETag
+}
+
 // LockInfo is lock information to create appropriate tree node.
 type LockInfo struct {
 	id uint64

api/handler/acl.go

@@ -466,7 +466,7 @@ func (h *handler) PutObjectACLHandler(w http.ResponseWriter, r *http.Request) {
 	if updated {
 		s := &SendNotificationParams{
 			Event:            EventObjectACLPut,
-			NotificationInfo: data.NotificationInfoFromObject(objInfo),
+			NotificationInfo: data.NotificationInfoFromObject(objInfo, h.cfg.Features.MD5Enabled()),
 			BktInfo:          bktInfo,
 			ReqInfo:          reqInfo,
 		}

api/handler/api.go

@@ -39,6 +39,7 @@ type (
 		IsResolveListAllow         bool // True if ResolveZoneList contains allowed zones
 		CompleteMultipartKeepalive time.Duration
 		Kludge                     KludgeSettings
+		Features                   layer.FeatureSettings
 	}
 
 	PlacementPolicy interface {

api/handler/attributes.go

@@ -1,6 +1,8 @@
 package handler
 
 import (
+	"encoding/base64"
+	"encoding/hex"
 	"fmt"
 	"net/http"
 	"strconv"
@@ -106,7 +108,7 @@ func (h *handler) GetObjectAttributesHandler(w http.ResponseWriter, r *http.Requ
 		return
 	}
 
-	if err = checkPreconditions(info, params.Conditional); err != nil {
+	if err = checkPreconditions(info, params.Conditional, h.cfg.Features.MD5Enabled()); err != nil {
 		h.logAndSendError(w, "precondition failed", reqInfo, err)
 		return
 	}
@@ -117,7 +119,7 @@ func (h *handler) GetObjectAttributesHandler(w http.ResponseWriter, r *http.Requ
 		return
 	}
 
-	response, err := encodeToObjectAttributesResponse(info, params)
+	response, err := encodeToObjectAttributesResponse(info, params, h.cfg.Features.MD5Enabled())
 	if err != nil {
 		h.logAndSendError(w, "couldn't encode object info to response", reqInfo, err)
 		return
@@ -179,19 +181,23 @@ func parseGetObjectAttributeArgs(r *http.Request) (*GetObjectAttributesArgs, err
 	return res, err
 }
 
-func encodeToObjectAttributesResponse(info *data.ObjectInfo, p *GetObjectAttributesArgs) (*GetObjectAttributesResponse, error) {
+func encodeToObjectAttributesResponse(info *data.ObjectInfo, p *GetObjectAttributesArgs, md5Enabled bool) (*GetObjectAttributesResponse, error) {
 	resp := &GetObjectAttributesResponse{}
 
 	for _, attr := range p.Attributes {
 		switch attr {
 		case eTag:
-			resp.ETag = info.HashSum
+			resp.ETag = info.ETag(md5Enabled)
 		case storageClass:
 			resp.StorageClass = "STANDARD"
 		case objectSize:
 			resp.ObjectSize = info.Size
 		case checksum:
-			resp.Checksum = &Checksum{ChecksumSHA256: info.HashSum}
+			checksumBytes, err := hex.DecodeString(info.HashSum)
+			if err != nil {
+				return nil, fmt.Errorf("form upload attributes: %w", err)
+			}
+			resp.Checksum = &Checksum{ChecksumSHA256: base64.StdEncoding.EncodeToString(checksumBytes)}
 		case objectParts:
 			parts, err := formUploadAttributes(info, p.MaxParts, p.PartNumberMarker)
 			if err != nil {
@@ -219,10 +225,15 @@ func formUploadAttributes(info *data.ObjectInfo, maxParts, marker int) (*ObjectP
 		if err != nil {
 			return nil, fmt.Errorf("invalid completed part: %w", err)
 		}
+		// ETag value contains SHA256 checksum.
+		checksumBytes, err := hex.DecodeString(part.ETag)
+		if err != nil {
+			return nil, fmt.Errorf("invalid sha256 checksum in completed part: %w", err)
+		}
 		parts[i] = Part{
 			PartNumber:     part.PartNumber,
 			Size:           int(part.Size),
-			ChecksumSHA256: part.ETag,
+			ChecksumSHA256: base64.StdEncoding.EncodeToString(checksumBytes),
 		}
 	}
 

api/handler/attributes_test.go

@@ -1,6 +1,8 @@
 package handler
 
 import (
+	"encoding/base64"
+	"encoding/hex"
 	"strings"
 	"testing"
 
@@ -24,11 +26,13 @@ func TestGetObjectPartsAttributes(t *testing.T) {
 	multipartUpload := createMultipartUpload(hc, bktName, objMultipartName, map[string]string{})
 	etag, _ := uploadPart(hc, bktName, objMultipartName, multipartUpload.UploadID, 1, partSize)
 	completeMultipartUpload(hc, bktName, objMultipartName, multipartUpload.UploadID, []string{etag})
+	etagBytes, err := hex.DecodeString(etag)
+	require.NoError(t, err)
 
 	result = getObjectAttributes(hc, bktName, objMultipartName, objectParts)
 	require.NotNil(t, result.ObjectParts)
 	require.Len(t, result.ObjectParts.Parts, 1)
-	require.Equal(t, etag, result.ObjectParts.Parts[0].ChecksumSHA256)
+	require.Equal(t, base64.StdEncoding.EncodeToString(etagBytes), result.ObjectParts.Parts[0].ChecksumSHA256)
 	require.Equal(t, partSize, result.ObjectParts.Parts[0].Size)
 	require.Equal(t, 1, result.ObjectParts.PartsCount)
 }

api/handler/copy.go

@@ -164,7 +164,7 @@ func (h *handler) CopyObjectHandler(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
-	if err = checkPreconditions(srcObjInfo, args.Conditional); err != nil {
+	if err = checkPreconditions(srcObjInfo, args.Conditional, h.cfg.Features.MD5Enabled()); err != nil {
 		h.logAndSendError(w, "precondition failed", reqInfo, errors.GetAPIError(errors.ErrPreconditionFailed))
 		return
 	}
@@ -210,7 +210,7 @@ func (h *handler) CopyObjectHandler(w http.ResponseWriter, r *http.Request) {
 	}
 	dstObjInfo := extendedDstObjInfo.ObjectInfo
 
-	if err = middleware.EncodeToResponse(w, &CopyObjectResponse{LastModified: dstObjInfo.Created.UTC().Format(time.RFC3339), ETag: dstObjInfo.HashSum}); err != nil {
+	if err = middleware.EncodeToResponse(w, &CopyObjectResponse{LastModified: dstObjInfo.Created.UTC().Format(time.RFC3339), ETag: dstObjInfo.ETag(h.cfg.Features.MD5Enabled())}); err != nil {
 		h.logAndSendError(w, "something went wrong", reqInfo, err, additional...)
 		return
 	}
@@ -254,7 +254,7 @@ func (h *handler) CopyObjectHandler(w http.ResponseWriter, r *http.Request) {
 
 	s := &SendNotificationParams{
 		Event:            EventObjectCreatedCopy,
-		NotificationInfo: data.NotificationInfoFromObject(dstObjInfo),
+		NotificationInfo: data.NotificationInfoFromObject(dstObjInfo, h.cfg.Features.MD5Enabled()),
 		BktInfo:          dstBktInfo,
 		ReqInfo:          reqInfo,
 	}

api/handler/get.go

@@ -78,7 +78,8 @@ func addSSECHeaders(responseHeader http.Header, requestHeader http.Header) {
 	responseHeader.Set(api.AmzServerSideEncryptionCustomerKeyMD5, requestHeader.Get(api.AmzServerSideEncryptionCustomerKeyMD5))
 }
 
-func writeHeaders(h http.Header, requestHeader http.Header, extendedInfo *data.ExtendedObjectInfo, tagSetLength int, isBucketUnversioned bool) {
+func writeHeaders(h http.Header, requestHeader http.Header, extendedInfo *data.ExtendedObjectInfo, tagSetLength int,
+	isBucketUnversioned, md5Enabled bool) {
 	info := extendedInfo.ObjectInfo
 	if len(info.ContentType) > 0 && h.Get(api.ContentType) == "" {
 		h.Set(api.ContentType, info.ContentType)
@@ -94,7 +95,8 @@ func writeHeaders(h http.Header, requestHeader http.Header, extendedInfo *data.E
 		h.Set(api.ContentLength, strconv.FormatUint(info.Size, 10))
 	}
 
-	h.Set(api.ETag, info.HashSum)
+	h.Set(api.ETag, info.ETag(md5Enabled))
+
 	h.Set(api.AmzTaggingCount, strconv.Itoa(tagSetLength))
 
 	if !isBucketUnversioned {
@@ -151,7 +153,7 @@ func (h *handler) GetObjectHandler(w http.ResponseWriter, r *http.Request) {
 	}
 	info := extendedInfo.ObjectInfo
 
-	if err = checkPreconditions(info, conditional); err != nil {
+	if err = checkPreconditions(info, conditional, h.cfg.Features.MD5Enabled()); err != nil {
 		h.logAndSendError(w, "precondition failed", reqInfo, err)
 		return
 	}
@@ -219,7 +221,7 @@ func (h *handler) GetObjectHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	writeHeaders(w.Header(), r.Header, extendedInfo, len(tagSet), bktSettings.Unversioned())
+	writeHeaders(w.Header(), r.Header, extendedInfo, len(tagSet), bktSettings.Unversioned(), h.cfg.Features.MD5Enabled())
 	if params != nil {
 		writeRangeHeaders(w, params, fullSize)
 	} else {
@@ -232,12 +234,13 @@ func (h *handler) GetObjectHandler(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
-func checkPreconditions(info *data.ObjectInfo, args *conditionalArgs) error {
+func checkPreconditions(info *data.ObjectInfo, args *conditionalArgs, md5Enabled bool) error {
-	if len(args.IfMatch) > 0 && args.IfMatch != info.HashSum {
+	etag := info.ETag(md5Enabled)
-		return fmt.Errorf("%w: etag mismatched: '%s', '%s'", errors.GetAPIError(errors.ErrPreconditionFailed), args.IfMatch, info.HashSum)
+	if len(args.IfMatch) > 0 && args.IfMatch != etag {
+		return fmt.Errorf("%w: etag mismatched: '%s', '%s'", errors.GetAPIError(errors.ErrPreconditionFailed), args.IfMatch, etag)
 	}
-	if len(args.IfNoneMatch) > 0 && args.IfNoneMatch == info.HashSum {
+	if len(args.IfNoneMatch) > 0 && args.IfNoneMatch == etag {
-		return fmt.Errorf("%w: etag matched: '%s', '%s'", errors.GetAPIError(errors.ErrNotModified), args.IfNoneMatch, info.HashSum)
+		return fmt.Errorf("%w: etag matched: '%s', '%s'", errors.GetAPIError(errors.ErrNotModified), args.IfNoneMatch, etag)
 	}
 	if args.IfModifiedSince != nil && info.Created.Before(*args.IfModifiedSince) {
 		return fmt.Errorf("%w: not modified since '%s', last modified '%s'", errors.GetAPIError(errors.ErrNotModified),

api/handler/get_test.go

@@ -147,7 +147,7 @@ func TestPreconditions(t *testing.T) {
 		},
 	} {
 		t.Run(tc.name, func(t *testing.T) {
-			actual := checkPreconditions(tc.info, tc.args)
+			actual := checkPreconditions(tc.info, tc.args, false)
 			if tc.expected == nil {
 				require.NoError(t, actual)
 			} else {
@@ -197,6 +197,19 @@ func TestGetObject(t *testing.T) {
 	getObjectAssertS3Error(hc, bktName, objName, emptyVersion, errors.ErrNoSuchKey)
 }
 
+func TestGetObjectEnabledMD5(t *testing.T) {
+	hc := prepareHandlerContext(t)
+	bktName, objName := "bucket", "obj"
+	_, objInfo := createBucketAndObject(hc, bktName, objName)
+
+	_, headers := getObject(hc, bktName, objName)
+	require.Equal(t, objInfo.HashSum, headers.Get(api.ETag))
+
+	hc.features.SetMD5Enabled(true)
+	_, headers = getObject(hc, bktName, objName)
+	require.Equal(t, objInfo.MD5Sum, headers.Get(api.ETag))
+}
+
 func putObjectContent(hc *handlerContext, bktName, objName, content string) {
 	body := bytes.NewReader([]byte(content))
 	w, r := prepareTestPayloadRequest(hc, bktName, objName, body)

api/handler/handlers_test.go

@@ -39,7 +39,7 @@ type handlerContext struct {
 	context context.Context
 	kludge  *kludgeSettingsMock
 
-	layerFeatures *layer.FeatureSettingsMock
+	features *layer.FeatureSettingsMock
 }
 
 func (hc *handlerContext) Handler() *handler {
@@ -148,6 +148,7 @@ func prepareHandlerContextBase(t *testing.T, minCache bool) *handlerContext {
 			Policy:     &placementPolicyMock{defaultPolicy: pp},
 			XMLDecoder: &xmlDecoderProviderMock{},
 			Kludge:     kludge,
+			Features:   features,
 		},
 	}
 
@@ -160,7 +161,7 @@ func prepareHandlerContextBase(t *testing.T, minCache bool) *handlerContext {
 		context: middleware.SetBoxData(context.Background(), newTestAccessBox(t, key)),
 		kludge:  kludge,
 
-		layerFeatures: features,
+		features: features,
 	}
 }
 

api/handler/head.go

@@ -65,7 +65,7 @@ func (h *handler) HeadObjectHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	if err = checkPreconditions(info, conditional); err != nil {
+	if err = checkPreconditions(info, conditional, h.cfg.Features.MD5Enabled()); err != nil {
 		h.logAndSendError(w, "precondition failed", reqInfo, err)
 		return
 	}
@@ -118,7 +118,7 @@ func (h *handler) HeadObjectHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	writeHeaders(w.Header(), r.Header, extendedInfo, len(tagSet), bktSettings.Unversioned())
+	writeHeaders(w.Header(), r.Header, extendedInfo, len(tagSet), bktSettings.Unversioned(), h.cfg.Features.MD5Enabled())
 	w.WriteHeader(http.StatusOK)
 }
 

api/handler/multipart_upload.go

@@ -243,6 +243,7 @@ func (h *handler) UploadPartHandler(w http.ResponseWriter, r *http.Request) {
 		PartNumber: partNumber,
 		Size:       size,
 		Reader:     body,
+		ContentMD5: r.Header.Get(api.ContentMD5),
 	}
 
 	p.Info.Encryption, err = formEncryptionParams(r)
@@ -336,7 +337,7 @@ func (h *handler) UploadPartCopy(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	if err = checkPreconditions(srcInfo, args.Conditional); err != nil {
+	if err = checkPreconditions(srcInfo, args.Conditional, h.cfg.Features.MD5Enabled()); err != nil {
 		h.logAndSendError(w, "precondition failed", reqInfo, errors.GetAPIError(errors.ErrPreconditionFailed),
 			additional...)
 		return
@@ -373,8 +374,8 @@ func (h *handler) UploadPartCopy(w http.ResponseWriter, r *http.Request) {
 	}
 
 	response := UploadPartCopyResponse{
-		ETag:         info.HashSum,
 		LastModified: info.Created.UTC().Format(time.RFC3339),
+		ETag:         info.ETag(h.cfg.Features.MD5Enabled()),
 	}
 
 	if p.Info.Encryption.Enabled() {
@@ -449,8 +450,8 @@ func (h *handler) CompleteMultipartUploadHandler(w http.ResponseWriter, r *http.
 
 	response := CompleteMultipartUploadResponse{
 		Bucket: objInfo.Bucket,
-		ETag:   objInfo.HashSum,
 		Key:    objInfo.Name,
+		ETag:   objInfo.ETag(h.cfg.Features.MD5Enabled()),
 	}
 
 	// Here we previously set api.AmzVersionID header for versioned bucket.
@@ -514,7 +515,7 @@ func (h *handler) completeMultipartUpload(r *http.Request, c *layer.CompleteMult
 
 	s := &SendNotificationParams{
 		Event:            EventObjectCreatedCompleteMultipartUpload,
-		NotificationInfo: data.NotificationInfoFromObject(objInfo),
+		NotificationInfo: data.NotificationInfoFromObject(objInfo, h.cfg.Features.MD5Enabled()),
 		BktInfo:          bktInfo,
 		ReqInfo:          reqInfo,
 	}

api/handler/multipart_upload_test.go

@@ -2,6 +2,8 @@ package handler
 
 import (
 	"bytes"
+	"crypto/md5"
+	"encoding/hex"
 	"encoding/xml"
 	"fmt"
 	"net/http"
@@ -255,6 +257,32 @@ func TestListParts(t *testing.T) {
 	require.Len(t, list.Parts, 0)
 }
 
+func TestMultipartUploadEnabledMD5(t *testing.T) {
+	hc := prepareHandlerContext(t)
+	hc.features.SetMD5Enabled(true)
+
+	bktName, objName := "bucket-md5", "object-md5"
+	createTestBucket(hc, bktName)
+
+	partSize := 5 * 1024 * 1024
+	multipartUpload := createMultipartUpload(hc, bktName, objName, map[string]string{})
+	etag1, partBody1 := uploadPart(hc, bktName, objName, multipartUpload.UploadID, 1, partSize)
+	md5Sum1 := md5.Sum(partBody1)
+	require.Equal(t, hex.EncodeToString(md5Sum1[:]), etag1)
+
+	etag2, partBody2 := uploadPart(hc, bktName, objName, multipartUpload.UploadID, 2, partSize)
+	md5Sum2 := md5.Sum(partBody2)
+	require.Equal(t, hex.EncodeToString(md5Sum2[:]), etag2)
+
+	w := completeMultipartUploadBase(hc, bktName, objName, multipartUpload.UploadID, []string{etag1, etag2})
+	assertStatus(t, w, http.StatusOK)
+	resp := &CompleteMultipartUploadResponse{}
+	err := xml.NewDecoder(w.Result().Body).Decode(resp)
+	require.NoError(t, err)
+	completeMD5Sum := md5.Sum(append(md5Sum1[:], md5Sum2[:]...))
+	require.Equal(t, hex.EncodeToString(completeMD5Sum[:])+"-2", resp.ETag)
+}
+
 func uploadPartCopy(hc *handlerContext, bktName, objName, uploadID string, num int, srcObj string, start, end int) *UploadPartCopyResponse {
 	return uploadPartCopyBase(hc, bktName, objName, false, uploadID, num, srcObj, start, end)
 }

api/handler/object_list.go

@@ -33,12 +33,12 @@ func (h *handler) ListObjectsV1Handler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	if err = middleware.EncodeToResponse(w, encodeV1(params, list)); err != nil {
+	if err = middleware.EncodeToResponse(w, h.encodeV1(params, list)); err != nil {
 		h.logAndSendError(w, "something went wrong", reqInfo, err)
 	}
 }
 
-func encodeV1(p *layer.ListObjectsParamsV1, list *layer.ListObjectsInfoV1) *ListObjectsV1Response {
+func (h *handler) encodeV1(p *layer.ListObjectsParamsV1, list *layer.ListObjectsInfoV1) *ListObjectsV1Response {
 	res := &ListObjectsV1Response{
 		Name:         p.BktInfo.Name,
 		EncodingType: p.Encode,
@@ -52,7 +52,7 @@ func encodeV1(p *layer.ListObjectsParamsV1, list *layer.ListObjectsInfoV1) *List
 
 	res.CommonPrefixes = fillPrefixes(list.Prefixes, p.Encode)
 
-	res.Contents = fillContentsWithOwner(list.Objects, p.Encode)
+	res.Contents = fillContentsWithOwner(list.Objects, p.Encode, h.cfg.Features.MD5Enabled())
 
 	return res
 }
@@ -77,12 +77,12 @@ func (h *handler) ListObjectsV2Handler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	if err = middleware.EncodeToResponse(w, encodeV2(params, list)); err != nil {
+	if err = middleware.EncodeToResponse(w, h.encodeV2(params, list)); err != nil {
 		h.logAndSendError(w, "something went wrong", reqInfo, err)
 	}
 }
 
-func encodeV2(p *layer.ListObjectsParamsV2, list *layer.ListObjectsInfoV2) *ListObjectsV2Response {
+func (h *handler) encodeV2(p *layer.ListObjectsParamsV2, list *layer.ListObjectsInfoV2) *ListObjectsV2Response {
 	res := &ListObjectsV2Response{
 		Name:                  p.BktInfo.Name,
 		EncodingType:          p.Encode,
@@ -98,7 +98,7 @@ func encodeV2(p *layer.ListObjectsParamsV2, list *layer.ListObjectsInfoV2) *List
 
 	res.CommonPrefixes = fillPrefixes(list.Prefixes, p.Encode)
 
-	res.Contents = fillContents(list.Objects, p.Encode, p.FetchOwner)
+	res.Contents = fillContents(list.Objects, p.Encode, p.FetchOwner, h.cfg.Features.MD5Enabled())
 
 	return res
 }
@@ -184,18 +184,18 @@ func fillPrefixes(src []string, encode string) []CommonPrefix {
 	return dst
 }
 
-func fillContentsWithOwner(src []*data.ObjectInfo, encode string) []Object {
+func fillContentsWithOwner(src []*data.ObjectInfo, encode string, md5Enabled bool) []Object {
-	return fillContents(src, encode, true)
+	return fillContents(src, encode, true, md5Enabled)
 }
 
-func fillContents(src []*data.ObjectInfo, encode string, fetchOwner bool) []Object {
+func fillContents(src []*data.ObjectInfo, encode string, fetchOwner, md5Enabled bool) []Object {
 	var dst []Object
 	for _, obj := range src {
 		res := Object{
 			Key:          s3PathEncode(obj.Name, encode),
 			Size:         obj.Size,
 			LastModified: obj.Created.UTC().Format(time.RFC3339),
-			ETag:         obj.HashSum,
+			ETag:         obj.ETag(md5Enabled),
 		}
 
 		if size, err := layer.GetObjectSize(obj); err == nil {
@@ -233,7 +233,7 @@ func (h *handler) ListBucketObjectVersionsHandler(w http.ResponseWriter, r *http
 		return
 	}
 
-	response := encodeListObjectVersionsToResponse(info, p.BktInfo.Name)
+	response := encodeListObjectVersionsToResponse(info, p.BktInfo.Name, h.cfg.Features.MD5Enabled())
 	if err = middleware.EncodeToResponse(w, response); err != nil {
 		h.logAndSendError(w, "something went wrong", reqInfo, err)
 	}
@@ -261,7 +261,7 @@ func parseListObjectVersionsRequest(reqInfo *middleware.ReqInfo) (*layer.ListObj
 	return &res, nil
 }
 
-func encodeListObjectVersionsToResponse(info *layer.ListObjectVersionsInfo, bucketName string) *ListObjectsVersionsResponse {
+func encodeListObjectVersionsToResponse(info *layer.ListObjectVersionsInfo, bucketName string, md5Enabled bool) *ListObjectsVersionsResponse {
 	res := ListObjectsVersionsResponse{
 		Name:                bucketName,
 		IsTruncated:         info.IsTruncated,
@@ -286,7 +286,7 @@ func encodeListObjectVersionsToResponse(info *layer.ListObjectVersionsInfo, buck
 			},
 			Size:      ver.ObjectInfo.Size,
 			VersionID: ver.Version(),
-			ETag:      ver.ObjectInfo.HashSum,
+			ETag:      ver.ObjectInfo.ETag(md5Enabled),
 		})
 	}
 	// this loop is not starting till versioning is not implemented

api/handler/put.go

@@ -242,6 +242,7 @@ func (h *handler) PutObjectHandler(w http.ResponseWriter, r *http.Request) {
 		Size:       size,
 		Header:     metadata,
 		Encryption: encryptionParams,
+		ContentMD5: r.Header.Get(api.ContentMD5),
 	}
 
 	params.CopiesNumbers, err = h.pickCopiesNumbers(metadata, bktInfo.LocationConstraint)
@@ -273,7 +274,7 @@ func (h *handler) PutObjectHandler(w http.ResponseWriter, r *http.Request) {
 
 	s := &SendNotificationParams{
 		Event:            EventObjectCreatedPut,
-		NotificationInfo: data.NotificationInfoFromObject(objInfo),
+		NotificationInfo: data.NotificationInfoFromObject(objInfo, h.cfg.Features.MD5Enabled()),
 		BktInfo:          bktInfo,
 		ReqInfo:          reqInfo,
 	}
@@ -324,7 +325,8 @@ func (h *handler) PutObjectHandler(w http.ResponseWriter, r *http.Request) {
 		addSSECHeaders(w.Header(), r.Header)
 	}
 
-	w.Header().Set(api.ETag, objInfo.HashSum)
+	w.Header().Set(api.ETag, objInfo.ETag(h.cfg.Features.MD5Enabled()))
+
 	middleware.WriteSuccessResponseHeadersOnly(w)
 }
 
@@ -490,7 +492,7 @@ func (h *handler) PostObject(w http.ResponseWriter, r *http.Request) {
 
 	s := &SendNotificationParams{
 		Event:            EventObjectCreatedPost,
-		NotificationInfo: data.NotificationInfoFromObject(objInfo),
+		NotificationInfo: data.NotificationInfoFromObject(objInfo, h.cfg.Features.MD5Enabled()),
 		BktInfo:          bktInfo,
 		ReqInfo:          reqInfo,
 	}
@@ -559,7 +561,7 @@ func (h *handler) PostObject(w http.ResponseWriter, r *http.Request) {
 			resp := &PostResponse{
 				Bucket: objInfo.Bucket,
 				Key:    objInfo.Name,
-				ETag:   objInfo.HashSum,
+				ETag:   objInfo.ETag(h.cfg.Features.MD5Enabled()),
 			}
 			w.WriteHeader(status)
 			if _, err = w.Write(middleware.EncodeResponse(resp)); err != nil {
@@ -569,7 +571,7 @@ func (h *handler) PostObject(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
-	w.Header().Set(api.ETag, objInfo.HashSum)
+	w.Header().Set(api.ETag, objInfo.ETag(h.cfg.Features.MD5Enabled()))
 	w.WriteHeader(status)
 }
 

api/handler/put_test.go

@@ -3,7 +3,10 @@ package handler
 import (
 	"bytes"
 	"context"
+	"crypto/md5"
 	"crypto/rand"
+	"encoding/base64"
+	"encoding/hex"
 	"encoding/json"
 	"errors"
 	"io"
@@ -194,6 +197,37 @@ func TestPutObjectWithWrapReaderDiscardOnError(t *testing.T) {
 	require.Equal(t, numGoroutineBefore, numGoroutineAfter, "goroutines shouldn't leak during put object")
 }
 
+func TestPutObjectWithInvalidContentMD5(t *testing.T) {
+	tc := prepareHandlerContext(t)
+	tc.features.SetMD5Enabled(true)
+
+	bktName, objName := "bucket-for-put", "object-for-put"
+	createTestBucket(tc, bktName)
+
+	content := []byte("content")
+	w, r := prepareTestPayloadRequest(tc, bktName, objName, bytes.NewReader(content))
+	r.Header.Set(api.ContentMD5, base64.StdEncoding.EncodeToString([]byte("invalid")))
+	tc.Handler().PutObjectHandler(w, r)
+	assertS3Error(t, w, s3errors.GetAPIError(s3errors.ErrInvalidDigest))
+
+	checkNotFound(t, tc, bktName, objName, emptyVersion)
+}
+
+func TestPutObjectWithEnabledMD5(t *testing.T) {
+	tc := prepareHandlerContext(t)
+	tc.features.SetMD5Enabled(true)
+
+	bktName, objName := "bucket-for-put", "object-for-put"
+	createTestBucket(tc, bktName)
+
+	content := []byte("content")
+	md5Hash := md5.New()
+	md5Hash.Write(content)
+	w, r := prepareTestPayloadRequest(tc, bktName, objName, bytes.NewReader(content))
+	tc.Handler().PutObjectHandler(w, r)
+	require.Equal(t, hex.EncodeToString(md5Hash.Sum(nil)), w.Header().Get(api.ETag))
+}
+
 func TestPutObjectWithStreamBodyAWSExample(t *testing.T) {
 	hc := prepareHandlerContext(t)
 
@@ -320,7 +354,7 @@ func TestPutObjectClientCut(t *testing.T) {
 	obj1 := getObjectFromLayer(hc, objName1)[0]
 	require.Empty(t, getObjectAttribute(obj1, "s3-client-cut"))
 
-	hc.layerFeatures.SetClientCut(true)
+	hc.features.SetClientCut(true)
 	putObject(hc, bktName, objName2)
 	obj2 := getObjectFromLayer(hc, objName2)[0]
 	require.Equal(t, "true", getObjectAttribute(obj2, "s3-client-cut"))

api/layer/cors.go

@@ -45,7 +45,7 @@ func (n *layer) PutBucketCORS(ctx context.Context, p *PutCORSParams) error {
 		CopiesNumber: p.CopiesNumbers,
 	}
 
-	_, objID, _, err := n.objectPutAndHash(ctx, prm, p.BktInfo)
+	_, objID, _, _, err := n.objectPutAndHash(ctx, prm, p.BktInfo)
 	if err != nil {
 		return fmt.Errorf("put system object: %w", err)
 	}

api/layer/frostfs_mock.go

@@ -26,7 +26,8 @@ import (
 )
 
 type FeatureSettingsMock struct {
-	clientCut bool
+	clientCut  bool
+	md5Enabled bool
 }
 
 func (k *FeatureSettingsMock) ClientCut() bool {
@@ -37,6 +38,14 @@ func (k *FeatureSettingsMock) SetClientCut(clientCut bool) {
 	k.clientCut = clientCut
 }
 
+func (k *FeatureSettingsMock) MD5Enabled() bool {
+	return k.md5Enabled
+}
+
+func (k *FeatureSettingsMock) SetMD5Enabled(md5Enabled bool) {
+	k.md5Enabled = md5Enabled
+}
+
 type TestFrostFS struct {
 	FrostFS
 

api/layer/layer.go

@@ -48,6 +48,7 @@ type (
 
 	FeatureSettings interface {
 		ClientCut() bool
+		MD5Enabled() bool
 	}
 
 	layer struct {
@@ -109,14 +110,16 @@ type (
 
 	// PutObjectParams stores object put request parameters.
 	PutObjectParams struct {
-		BktInfo       *data.BucketInfo
+		BktInfo         *data.BucketInfo
-		Object        string
+		Object          string
-		Size          uint64
+		Size            uint64
-		Reader        io.Reader
+		Reader          io.Reader
-		Header        map[string]string
+		Header          map[string]string
-		Lock          *data.ObjectLock
+		Lock            *data.ObjectLock
-		Encryption    encryption.Params
+		Encryption      encryption.Params
-		CopiesNumbers []uint32
+		CopiesNumbers   []uint32
+		CompleteMD5Hash string
+		ContentMD5      string
 	}
 
 	PutCombinedObjectParams struct {

api/layer/multipart_upload.go

@@ -3,6 +3,8 @@ package layer
 import (
 	"bytes"
 	"context"
+	"crypto/md5"
+	"encoding/base64"
 	"encoding/hex"
 	"encoding/json"
 	"errors"
@@ -68,6 +70,7 @@ type (
 		PartNumber int
 		Size       uint64
 		Reader     io.Reader
+		ContentMD5 string
 	}
 
 	UploadCopyParams struct {
@@ -197,7 +200,7 @@ func (n *layer) UploadPart(ctx context.Context, p *UploadPartParams) (string, er
 		return "", err
 	}
 
-	return objInfo.HashSum, nil
+	return objInfo.ETag(n.features.MD5Enabled()), nil
 }
 
 func (n *layer) uploadPart(ctx context.Context, multipartInfo *data.MultipartInfo, p *UploadPartParams) (*data.ObjectInfo, error) {
@@ -230,10 +233,28 @@ func (n *layer) uploadPart(ctx context.Context, multipartInfo *data.MultipartInf
 	prm.Attributes[0][0], prm.Attributes[0][1] = UploadIDAttributeName, p.Info.UploadID
 	prm.Attributes[1][0], prm.Attributes[1][1] = UploadPartNumberAttributeName, strconv.Itoa(p.PartNumber)
 
-	size, id, hash, err := n.objectPutAndHash(ctx, prm, bktInfo)
+	size, id, hash, md5Hash, err := n.objectPutAndHash(ctx, prm, bktInfo)
 	if err != nil {
 		return nil, err
 	}
+	if len(p.ContentMD5) > 0 {
+		hashBytes, err := base64.StdEncoding.DecodeString(p.ContentMD5)
+		if err != nil {
+			return nil, s3errors.GetAPIError(s3errors.ErrInvalidDigest)
+		}
+		if hex.EncodeToString(hashBytes) != hex.EncodeToString(md5Hash) {
+			prm := PrmObjectDelete{
+				Object:    id,
+				Container: bktInfo.CID,
+			}
+			n.prepareAuthParameters(ctx, &prm.PrmAuth, bktInfo.Owner)
+			err = n.frostFS.DeleteObject(ctx, prm)
+			if err != nil {
+				n.reqLogger(ctx).Debug(logs.FailedToDeleteObject, zap.Stringer("cid", bktInfo.CID), zap.Stringer("oid", id))
+			}
+			return nil, s3errors.GetAPIError(s3errors.ErrInvalidDigest)
+		}
+	}
 	if p.Info.Encryption.Enabled() {
 		size = decSize
 	}
@@ -250,6 +271,7 @@ func (n *layer) uploadPart(ctx context.Context, multipartInfo *data.MultipartInf
 		Size:     size,
 		ETag:     hex.EncodeToString(hash),
 		Created:  prm.CreationTime,
+		MD5:      hex.EncodeToString(md5Hash),
 	}
 
 	oldPartID, err := n.treeService.AddPart(ctx, bktInfo, multipartInfo.ID, partInfo)
@@ -274,6 +296,7 @@ func (n *layer) uploadPart(ctx context.Context, multipartInfo *data.MultipartInf
 		Size:    partInfo.Size,
 		Created: partInfo.Created,
 		HashSum: partInfo.ETag,
+		MD5Sum:  partInfo.MD5,
 	}
 
 	return objInfo, nil
@@ -347,9 +370,10 @@ func (n *layer) CompleteMultipartUpload(ctx context.Context, p *CompleteMultipar
 	parts := make([]*data.PartInfo, 0, len(p.Parts))
 
 	var completedPartsHeader strings.Builder
+	md5Hash := md5.New()
 	for i, part := range p.Parts {
 		partInfo := partsInfo[part.PartNumber]
-		if partInfo == nil || part.ETag != partInfo.ETag {
+		if partInfo == nil || strings.Trim(part.ETag, "\"") != partInfo.GetETag(n.features.MD5Enabled()) {
 			return nil, nil, fmt.Errorf("%w: unknown part %d or etag mismatched", s3errors.GetAPIError(s3errors.ErrInvalidPart), part.PartNumber)
 		}
 		delete(partsInfo, part.PartNumber)
@@ -376,6 +400,12 @@ func (n *layer) CompleteMultipartUpload(ctx context.Context, p *CompleteMultipar
 		if _, err = completedPartsHeader.WriteString(partInfoStr); err != nil {
 			return nil, nil, err
 		}
+
+		bytesHash, err := hex.DecodeString(partInfo.MD5)
+		if err != nil {
+			return nil, nil, fmt.Errorf("couldn't decode MD5 checksum of part: %w", err)
+		}
+		md5Hash.Write(bytesHash)
 	}
 
 	initMetadata := make(map[string]string, len(multipartInfo.Meta)+1)
@@ -410,13 +440,14 @@ func (n *layer) CompleteMultipartUpload(ctx context.Context, p *CompleteMultipar
 	}
 
 	extObjInfo, err := n.PutObject(ctx, &PutObjectParams{
-		BktInfo:       p.Info.Bkt,
+		BktInfo:         p.Info.Bkt,
-		Object:        p.Info.Key,
+		Object:          p.Info.Key,
-		Reader:        bytes.NewReader(partsData),
+		Reader:          bytes.NewReader(partsData),
-		Header:        initMetadata,
+		Header:          initMetadata,
-		Size:          multipartObjetSize,
+		Size:            multipartObjetSize,
-		Encryption:    p.Info.Encryption,
+		Encryption:      p.Info.Encryption,
-		CopiesNumbers: multipartInfo.CopiesNumbers,
+		CopiesNumbers:   multipartInfo.CopiesNumbers,
+		CompleteMD5Hash: hex.EncodeToString(md5Hash.Sum(nil)) + "-" + strconv.Itoa(len(p.Parts)),
 	})
 	if err != nil {
 		n.reqLogger(ctx).Error(logs.CouldNotPutCompletedObject,
@@ -537,7 +568,7 @@ func (n *layer) ListParts(ctx context.Context, p *ListPartsParams) (*ListPartsIn
 
 	for _, partInfo := range partsInfo {
 		parts = append(parts, &Part{
-			ETag:         partInfo.ETag,
+			ETag:         partInfo.GetETag(n.features.MD5Enabled()),
 			LastModified: partInfo.Created.UTC().Format(time.RFC3339),
 			PartNumber:   partInfo.Number,
 			Size:         partInfo.Size,

api/layer/notifications.go

@@ -34,7 +34,7 @@ func (n *layer) PutBucketNotificationConfiguration(ctx context.Context, p *PutBu
 		CopiesNumber: p.CopiesNumbers,
 	}
 
-	_, objID, _, err := n.objectPutAndHash(ctx, prm, p.BktInfo)
+	_, objID, _, _, err := n.objectPutAndHash(ctx, prm, p.BktInfo)
 	if err != nil {
 		return err
 	}

api/layer/object.go

@@ -1,8 +1,11 @@
 package layer
 
 import (
+	"bytes"
 	"context"
+	"crypto/md5"
 	"crypto/sha256"
+	"encoding/base64"
 	"encoding/hex"
 	"encoding/json"
 	"errors"
@@ -287,10 +290,23 @@ func (n *layer) PutObject(ctx context.Context, p *PutObjectParams) (*data.Extend
 		prm.Attributes = append(prm.Attributes, [2]string{k, v})
 	}
 
-	size, id, hash, err := n.objectPutAndHash(ctx, prm, p.BktInfo)
+	size, id, hash, md5Hash, err := n.objectPutAndHash(ctx, prm, p.BktInfo)
 	if err != nil {
 		return nil, err
 	}
+	if len(p.ContentMD5) > 0 {
+		headerMd5Hash, err := base64.StdEncoding.DecodeString(p.ContentMD5)
+		if err != nil {
+			return nil, apiErrors.GetAPIError(apiErrors.ErrInvalidDigest)
+		}
+		if !bytes.Equal(headerMd5Hash, md5Hash) {
+			err = n.objectDelete(ctx, p.BktInfo, id)
+			if err != nil {
+				n.reqLogger(ctx).Debug(logs.FailedToDeleteObject, zap.Stringer("cid", p.BktInfo.CID), zap.Stringer("oid", id))
+			}
+			return nil, apiErrors.GetAPIError(apiErrors.ErrInvalidDigest)
+		}
+	}
 
 	n.reqLogger(ctx).Debug(logs.PutObject, zap.Stringer("cid", p.BktInfo.CID), zap.Stringer("oid", id))
 
@@ -304,6 +320,11 @@ func (n *layer) PutObject(ctx context.Context, p *PutObjectParams) (*data.Extend
 		IsUnversioned: !bktSettings.VersioningEnabled(),
 		IsCombined:    p.Header[MultipartObjectSize] != "",
 	}
+	if len(p.CompleteMD5Hash) > 0 {
+		newVersion.MD5 = p.CompleteMD5Hash
+	} else {
+		newVersion.MD5 = hex.EncodeToString(md5Hash)
+	}
 
 	if newVersion.ID, err = n.treeService.AddVersion(ctx, p.BktInfo, newVersion); err != nil {
 		return nil, fmt.Errorf("couldn't add new verion to tree service: %w", err)
@@ -340,6 +361,7 @@ func (n *layer) PutObject(ctx context.Context, p *PutObjectParams) (*data.Extend
 		Headers:     p.Header,
 		ContentType: p.Header[api.ContentType],
 		HashSum:     newVersion.ETag,
+		MD5Sum:      newVersion.MD5,
 	}
 
 	extendedObjInfo := &data.ExtendedObjectInfo{
@@ -378,6 +400,7 @@ func (n *layer) headLastVersionIfNotDeleted(ctx context.Context, bkt *data.Bucke
 		return nil, err
 	}
 	objInfo := objectInfoFromMeta(bkt, meta)
+	objInfo.MD5Sum = node.MD5
 
 	extObjInfo := &data.ExtendedObjectInfo{
 		ObjectInfo:  objInfo,
@@ -430,6 +453,7 @@ func (n *layer) headVersion(ctx context.Context, bkt *data.BucketInfo, p *HeadOb
 		return nil, err
 	}
 	objInfo := objectInfoFromMeta(bkt, meta)
+	objInfo.MD5Sum = foundVersion.MD5
 
 	extObjInfo := &data.ExtendedObjectInfo{
 		ObjectInfo:  objInfo,
@@ -457,14 +481,16 @@ func (n *layer) objectDelete(ctx context.Context, bktInfo *data.BucketInfo, idOb
 
 // objectPutAndHash prepare auth parameters and invoke frostfs.CreateObject.
 // Returns object ID and payload sha256 hash.
-func (n *layer) objectPutAndHash(ctx context.Context, prm PrmObjectCreate, bktInfo *data.BucketInfo) (uint64, oid.ID, []byte, error) {
+func (n *layer) objectPutAndHash(ctx context.Context, prm PrmObjectCreate, bktInfo *data.BucketInfo) (uint64, oid.ID, []byte, []byte, error) {
 	n.prepareAuthParameters(ctx, &prm.PrmAuth, bktInfo.Owner)
 	prm.ClientCut = n.features.ClientCut()
 	var size uint64
 	hash := sha256.New()
+	md5Hash := md5.New()
 	prm.Payload = wrapReader(prm.Payload, 64*1024, func(buf []byte) {
 		size += uint64(len(buf))
 		hash.Write(buf)
+		md5Hash.Write(buf)
 	})
 	id, err := n.frostFS.CreateObject(ctx, prm)
 	if err != nil {
@@ -472,9 +498,9 @@ func (n *layer) objectPutAndHash(ctx context.Context, prm PrmObjectCreate, bktIn
 			n.reqLogger(ctx).Warn(logs.FailedToDiscardPutPayloadProbablyGoroutineLeaks, zap.Error(errDiscard))
 		}
 
-		return 0, oid.ID{}, nil, err
+		return 0, oid.ID{}, nil, nil, err
 	}
-	return size, id, hash.Sum(nil), nil
+	return size, id, hash.Sum(nil), md5Hash.Sum(nil), nil
 }
 
 // ListObjectsV1 returns objects in a bucket for requests of Version 1.
@@ -805,6 +831,7 @@ func (n *layer) objectInfoFromObjectsCacheOrFrostFS(ctx context.Context, bktInfo
 	}
 
 	oi = objectInfoFromMeta(bktInfo, meta)
+	oi.MD5Sum = node.MD5
 	n.cache.PutObject(owner, &data.ExtendedObjectInfo{ObjectInfo: oi, NodeVersion: node})
 
 	return oi

api/layer/system_object.go

@@ -125,7 +125,7 @@ func (n *layer) putLockObject(ctx context.Context, bktInfo *data.BucketInfo, obj
 		return oid.ID{}, err
 	}
 
-	_, id, _, err := n.objectPutAndHash(ctx, prm, bktInfo)
+	_, id, _, _, err := n.objectPutAndHash(ctx, prm, bktInfo)
 	return id, err
 }
 

cmd/s3-gw/app.go

@@ -73,6 +73,7 @@ type (
 		maxClient                     maxClientsConfig
 		bypassContentEncodingInChunks atomic.Bool
 		clientCut                     atomic.Bool
+		md5Enabled                    atomic.Bool
 	}
 
 	maxClientsConfig struct {
@@ -176,6 +177,7 @@ func newAppSettings(log *Logger, v *viper.Viper) *appSettings {
 
 	settings.setBypassContentEncodingInChunks(v.GetBool(cfgKludgeBypassContentEncodingCheckInChunks))
 	settings.setClientCut(v.GetBool(cfgClientCut))
+	settings.setMD5Enabled(v.GetBool(cfgMD5Enabled))
 
 	return settings
 }
@@ -196,6 +198,14 @@ func (s *appSettings) setClientCut(clientCut bool) {
 	s.clientCut.Store(clientCut)
 }
 
+func (s *appSettings) MD5Enabled() bool {
+	return s.md5Enabled.Load()
+}
+
+func (s *appSettings) setMD5Enabled(md5Enabled bool) {
+	s.md5Enabled.Store(md5Enabled)
+}
+
 func (a *App) initAPI(ctx context.Context) {
 	a.initLayer(ctx)
 	a.initHandler()
@@ -536,6 +546,7 @@ func (a *App) updateSettings() {
 	a.settings.xmlDecoder.UseDefaultNamespaceForCompleteMultipart(a.cfg.GetBool(cfgKludgeUseDefaultXMLNSForCompleteMultipartUpload))
 	a.settings.setBypassContentEncodingInChunks(a.cfg.GetBool(cfgKludgeBypassContentEncodingCheckInChunks))
 	a.settings.setClientCut(a.cfg.GetBool(cfgClientCut))
+	a.settings.setMD5Enabled(a.cfg.GetBool(cfgMD5Enabled))
 }
 
 func (a *App) startServices() {
@@ -679,6 +690,7 @@ func (a *App) initHandler() {
 
 	cfg.CompleteMultipartKeepalive = a.cfg.GetDuration(cfgKludgeCompleteMultipartUploadKeepalive)
 	cfg.Kludge = a.settings
+	cfg.Features = a.settings
 
 	var err error
 	a.api, err = handler.New(a.log, a.obj, a.nc, cfg)

cmd/s3-gw/app_settings.go

@@ -160,6 +160,9 @@ const ( // Settings.
 	// Runtime.
 	cfgSoftMemoryLimit = "runtime.soft_memory_limit"
 
+	// Enable return MD5 checksum in ETag.
+	cfgMD5Enabled = "features.md5.enabled"
+
 	// envPrefix is an environment variables prefix used for configuration.
 	envPrefix = "S3_GW"
 )

config/config.env

@@ -148,3 +148,5 @@ S3_GW_TRACING_ENDPOINT="localhost:4318"
 S3_GW_TRACING_EXPORTER="otlp_grpc"
 
 S3_GW_RUNTIME_SOFT_MEMORY_LIMIT=1073741824
+
+S3_GW_FEATURES_MD5_ENABLED=false

config/config.yaml

@@ -174,3 +174,7 @@ kludge:
 
 runtime:
   soft_memory_limit: 1gb
+
+features:
+  md5:
+    enabled: false

docs/configuration.md

@@ -186,6 +186,7 @@ There are some custom types used for brevity:
 | `resolve_bucket`   | [Bucket name resolving configuration](#resolve_bucket-section) |
 | `kludge`           | [Different kludge configuration](#kludge-section)              |
 | `runtime`          | [Runtime configuration](#runtime-section)                      |
+| `features`         | [Features configuration](#features-section)                    |
 
 ### General section
 
@@ -560,3 +561,16 @@ runtime:
 | Parameter           | Type   | SIGHUP reload | Default value | Description                                                                                                                                                                  |
 |---------------------|--------|---------------|---------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | `soft_memory_limit` | `size` | yes           | maxint64      | Soft memory limit for the runtime. Zero or no value stands for no limit. If `GOMEMLIMIT` environment variable is set, the value from the configuration file will be ignored. |
+
+# `features` section
+Contains parameters for enabling features.
+
+```yaml
+features:
+   md5:
+      enabled: false
+```
+
+| Parameter     | Type   | SIGHUP reload | Default value | Description                                                    |
+|---------------|--------|---------------|---------------|----------------------------------------------------------------|
+| `md5.enabled` | `bool` | yes           | false         | Flag to enable return MD5 checksum in ETag headers and fields. |

internal/logs/logs.go

@@ -75,6 +75,7 @@ const (
 	ResolveBucket                                        = "resolve bucket"                                                                                    // Info in ../../api/layer/layer.go
 	CouldntDeleteCorsObject                              = "couldn't delete cors object"                                                                       // Error in ../../api/layer/cors.go
 	PutObject                                            = "put object"                                                                                        // Debug in ../../api/layer/object.go
+	FailedToDeleteObject                                 = "failed to delete object"                                                                           // Debug in ../../api/layer/object.go
 	FailedToDiscardPutPayloadProbablyGoroutineLeaks      = "failed to discard put payload, probably goroutine leaks"                                           // Warn in ../../api/layer/object.go
 	FailedToSubmitTaskToPool                             = "failed to submit task to pool"                                                                     // Warn in ../../api/layer/object.go
 	CouldNotFetchObjectMeta                              = "could not fetch object meta"                                                                       // Warn in ../../api/layer/object.go

pkg/service/tree/tree.go

@@ -81,6 +81,7 @@ const (
 	partNumberKV    = "Number"
 	sizeKV          = "Size"
 	etagKV          = "ETag"
+	md5KV           = "MD5"
 
 	// keys for lock.
 	isLockKV       = "IsLock"
@@ -185,6 +186,7 @@ func newNodeVersionFromTreeNode(filePath string, treeNode *treeNode) *data.NodeV
 	_, isDeleteMarker := treeNode.Get(isDeleteMarkerKV)
 	_, isCombined := treeNode.Get(isCombinedKV)
 	eTag, _ := treeNode.Get(etagKV)
+	md5, _ := treeNode.Get(md5KV)
 
 	version := &data.NodeVersion{
 		BaseNodeVersion: data.BaseNodeVersion{
@@ -193,6 +195,7 @@ func newNodeVersionFromTreeNode(filePath string, treeNode *treeNode) *data.NodeV
 			OID:       treeNode.ObjID,
 			Timestamp: treeNode.TimeStamp,
 			ETag:      eTag,
+			MD5:       md5,
 			Size:      treeNode.Size,
 			FilePath:  filePath,
 		},
@@ -302,6 +305,8 @@ func newPartInfo(node NodeResponse) (*data.PartInfo, error) {
 				return nil, fmt.Errorf("invalid created timestamp: %w", err)
 			}
 			partInfo.Created = time.UnixMilli(utcMilli)
+		case md5KV:
+			partInfo.MD5 = value
 		}
 	}
 
@@ -560,7 +565,7 @@ func (c *Tree) GetVersions(ctx context.Context, bktInfo *data.BucketInfo, filepa
 }
 
 func (c *Tree) GetLatestVersion(ctx context.Context, bktInfo *data.BucketInfo, objectName string) (*data.NodeVersion, error) {
-	meta := []string{oidKV, isUnversionedKV, isDeleteMarkerKV, etagKV, sizeKV}
+	meta := []string{oidKV, isUnversionedKV, isDeleteMarkerKV, etagKV, sizeKV, md5KV}
 	path := pathFromName(objectName)
 
 	p := &GetNodesParams{
@@ -1006,6 +1011,7 @@ func (c *Tree) AddPart(ctx context.Context, bktInfo *data.BucketInfo, multipartN
 		sizeKV:       strconv.FormatUint(info.Size, 10),
 		createdKV:    strconv.FormatInt(info.Created.UTC().UnixMilli(), 10),
 		etagKV:       info.ETag,
+		md5KV:        info.MD5,
 	}
 
 	for _, part := range parts {
@@ -1138,6 +1144,9 @@ func (c *Tree) addVersion(ctx context.Context, bktInfo *data.BucketInfo, treeID
 	if len(version.ETag) > 0 {
 		meta[etagKV] = version.ETag
 	}
+	if len(version.MD5) > 0 {
+		meta[md5KV] = version.MD5
+	}
 
 	if version.IsDeleteMarker() {
 		meta[isDeleteMarkerKV] = "true"
@@ -1182,7 +1191,7 @@ func (c *Tree) clearOutdatedVersionInfo(ctx context.Context, bktInfo *data.Bucke
 }
 
 func (c *Tree) getVersions(ctx context.Context, bktInfo *data.BucketInfo, treeID, filepath string, onlyUnversioned bool) ([]*data.NodeVersion, error) {
-	keysToReturn := []string{oidKV, isUnversionedKV, isDeleteMarkerKV, etagKV, sizeKV}
+	keysToReturn := []string{oidKV, isUnversionedKV, isDeleteMarkerKV, etagKV, sizeKV, md5KV}
 	path := pathFromName(filepath)
 	p := &GetNodesParams{
 		BktInfo:    bktInfo,