[server] Version check support during ml data put (#5895)

## Description

## Tests

server/ente/filedata/filedata.go

@@ -26,6 +26,7 @@ type Entity struct {
 	Type             ente.ObjectType `json:"type"`
 	EncryptedData    string          `json:"encryptedData"`
 	DecryptionHeader string          `json:"decryptionHeader"`
+	UpdatedAt        int64           `json:"updatedAt"`
 }
 
 type FDDiffRequest struct {

server/ente/filedata/putfiledata.go

@@ -11,6 +11,8 @@ type PutFileDataRequest struct {
 	EncryptedData    *string         `json:"encryptedData,omitempty"`
 	DecryptionHeader *string         `json:"decryptionHeader,omitempty"`
 	Version          *int            `json:"version,omitempty"`
+	// Used to ensure that the client has correct state before it tries to update the metadata
+	LastUpdatedAt *int64 `json:"lastUpdatedAt,omitempty"`
 }
 
 func (r PutFileDataRequest) isEncDataPresent() bool {

server/pkg/controller/filedata/controller.go

@@ -3,6 +3,7 @@ package filedata
 import (
 	"context"
 	"errors"
+	"fmt"
 	"github.com/aws/aws-sdk-go/aws/awserr"
 	"github.com/aws/aws-sdk-go/service/s3"
 	"github.com/aws/aws-sdk-go/service/s3/s3manager"
@@ -20,6 +21,7 @@ import (
 	"github.com/gin-contrib/requestid"
 	"github.com/gin-gonic/gin"
 	log "github.com/sirupsen/logrus"
+	"net/http"
 	"sync"
 	gTime "time"
 )
@@ -95,6 +97,9 @@ func (c *Controller) InsertOrUpdateMetadata(ctx *gin.Context, req *fileData.PutF
 	if req.Type != ente.MlData {
 		return stacktrace.Propagate(ente.NewBadRequestWithMessage("unsupported object type "+string(req.Type)), "")
 	}
+	if versionErr := c._validateLastUpdatedAt(ctx, req.LastUpdatedAt, req.FileID, req.Type); versionErr != nil {
+		return stacktrace.Propagate(versionErr, "")
+	}
 
 	bucketID := c.S3Config.GetBucketID(req.Type)
 	objectKey := fileData.ObjectMetadataKey(req.FileID, fileOwnerID, req.Type, nil)
@@ -161,6 +166,7 @@ func (c *Controller) GetFileData(ctx *gin.Context, actorUser int64, req fileData
 		Type:             doRows[0].Type,
 		EncryptedData:    s3MetaObject.EncryptedData,
 		DecryptionHeader: s3MetaObject.DecryptionHeader,
+		UpdatedAt:        doRows[0].UpdatedAt,
 	}, nil
 }
 
@@ -205,6 +211,7 @@ func (c *Controller) GetFilesData(ctx *gin.Context, req fileData.GetFilesData) (
 				Type:             obj.dbEntry.Type,
 				EncryptedData:    obj.s3MetaObject.EncryptedData,
 				DecryptionHeader: obj.s3MetaObject.DecryptionHeader,
+				UpdatedAt:        obj.dbEntry.UpdatedAt,
 			})
 		}
 	}
@@ -317,6 +324,38 @@ func (c *Controller) _checkMetadataReadOrWritePerm(ctx *gin.Context, userID int6
 	return nil
 }
 
+func (c *Controller) _validateLastUpdatedAt(ctx *gin.Context, lastUpdatedAt *int64, fileID int64, oType ente.ObjectType) error {
+	if lastUpdatedAt == nil {
+		return nil
+	}
+	doRows, err := c.Repo.GetFilesData(ctx, oType, []int64{fileID})
+	if err != nil {
+		return stacktrace.Propagate(err, "failed to get data")
+	}
+	var invalidVersionErr = &ente.ApiError{
+		HttpStatusCode: http.StatusConflict,
+		Code:           "INVALID_VERSION",
+		Message:        "",
+	}
+	if len(doRows) == 0 {
+		if *lastUpdatedAt == 0 {
+			return nil
+		}
+		invalidVersionErr.Message = "non zero version empty data"
+		return invalidVersionErr
+	}
+	if doRows[0].IsDeleted {
+		invalidVersionErr.Message = "data deleted"
+		return invalidVersionErr
+	}
+	dbUpdatedAt := doRows[0].UpdatedAt
+	if dbUpdatedAt != *lastUpdatedAt {
+		invalidVersionErr.Message = fmt.Sprintf("version mismatch expected %d, found %d", dbUpdatedAt, *lastUpdatedAt)
+		return invalidVersionErr
+	}
+	return nil
+}
+
 // _checkPreviewWritePerm is
 func (c *Controller) _checkPreviewWritePerm(ctx *gin.Context, fileID int64, actorID int64) error {
 	err := c.AccessCtrl.VerifyFileOwnership(ctx, &access.VerifyFileOwnershipParams{

server/pkg/repo/passkey/passkey.go

@@ -13,8 +13,8 @@ import (
 	"github.com/ente-io/stacktrace"
 	"github.com/go-webauthn/webauthn/protocol"
 	"github.com/google/uuid"
-	"github.com/spf13/viper"
 	"github.com/sirupsen/logrus"
+	"github.com/spf13/viper"
 
 	"github.com/ente-io/museum/ente"
 	"github.com/ente-io/museum/pkg/utils/byteMarshaller"