add validation for uploadMeta and updateMeta request data

code/go/0chain.net/blobbercore/allocation/newfilechange.go

@@ -9,22 +9,23 @@ import (
 	"0chain.net/blobbercore/filestore"
 	"0chain.net/blobbercore/reference"
 	"0chain.net/blobbercore/stats"
+	"0chain.net/blobbercore/util"
 	"0chain.net/core/common"
 )
 
 type NewFileChange struct {
-	ConnectionID        string               `json:"connection_id"`
+	ConnectionID        string               `json:"connection_id" validation:"required"`
 	AllocationID        string               `json:"allocation_id"`
-	Filename            string               `json:"filename"`
+	Filename            string               `json:"filename" validation:"required"`
 	ThumbnailFilename   string               `json:"thumbnail_filename"`
-	Path                string               `json:"filepath"`
+	Path                string               `json:"filepath" validation:"required"`
 	Size                int64                `json:"size"`
 	Hash                string               `json:"content_hash,omitempty"`
 	ThumbnailSize       int64                `json:"thumbnail_size"`
 	ThumbnailHash       string               `json:"thumbnail_content_hash,omitempty"`
 	MerkleRoot          string               `json:"merkle_root,omitempty"`
-	ActualHash          string               `json:"actual_hash,omitempty"`
-	ActualSize          int64                `json:"actual_size,omitempty"`
+	ActualHash          string               `json:"actual_hash,omitempty" validation:"required"`
+	ActualSize          int64                `json:"actual_size,omitempty" validation:"required"`
 	ActualThumbnailSize int64                `json:"actual_thumb_size"`
 	ActualThumbnailHash string               `json:"actual_thumb_hash"`
 	MimeType            string               `json:"mimetype,omitempty"`
@@ -120,8 +121,11 @@ func (nf *NewFileChange) Marshal() (string, error) {
 }
 
 func (nf *NewFileChange) Unmarshal(input string) error {
-	err := json.Unmarshal([]byte(input), nf)
-	return err
+	if err := json.Unmarshal([]byte(input), nf); err != nil {
+		return err
+	}
+
+	return util.UnmarshalValidation(nf)
 }
 
 func (nf *NewFileChange) DeleteTempFile() error {

code/go/0chain.net/blobbercore/allocation/updatefilechange.go

@@ -7,8 +7,8 @@ import (
 
 	"0chain.net/blobbercore/filestore"
 	"0chain.net/blobbercore/stats"
-
 	"0chain.net/blobbercore/reference"
+	"0chain.net/blobbercore/util"
 	"0chain.net/core/common"
 	. "0chain.net/core/logging"
 
@@ -94,8 +94,11 @@ func (nf *UpdateFileChange) Marshal() (string, error) {
 }
 
 func (nf *UpdateFileChange) Unmarshal(input string) error {
-	err := json.Unmarshal([]byte(input), nf)
-	return err
+	if err := json.Unmarshal([]byte(input), nf); err != nil {
+		return err
+	}
+
+	return util.UnmarshalValidation(nf)
 }
 
 func (nf *UpdateFileChange) DeleteTempFile() error {

code/go/0chain.net/blobbercore/util/json.go

@@ -0,0 +1,28 @@
+package util
+
+import (
+	"fmt"
+	"strings"
+	"reflect"
+	"errors"
+)
+
+// Validate unmarshalled data with tag-based rules
+// Example:
+// struct {
+//	Name string `json:"name" validation:"required"`
+// }
+func UnmarshalValidation(v interface{}) error {
+	fields := reflect.ValueOf(v).Elem()
+
+	for i := 0; i < fields.NumField(); i++ {
+		validation := fields.Type().Field(i).Tag.Get("validation")
+		if strings.Contains(validation, "required") && fields.Field(i).IsZero() {
+			// todo: better try this first:
+			// jsonFieldName := fields.Type().Field(i).Tag.Get("json")
+			return errors.New(fmt.Sprintf("The '%s' field is required", fields.Type().Field(i).Name))
+		}
+	}
+
+	return nil
+}