From dd2343a0b5b21fccb220e21cbaf6e1d08912c12a Mon Sep 17 00:00:00 2001
From: Evgenii Baidakov <evgenii@nspcc.io>
Date: Thu, 12 Oct 2023 15:27:09 +0400
Subject: [PATCH 1/2] layer: Return unsupported error if meta parameter is
 empty

Closes #846.

Signed-off-by: Evgenii Baidakov <evgenii@nspcc.io>
---
 CHANGELOG.md          | 3 +++
 api/handler/util.go   | 4 ++++
 api/layer/neofs.go    | 3 +++
 api/layer/object.go   | 6 ++++++
 docs/aws_s3_compat.md | 6 ++++++
 5 files changed, 22 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d93ddff6..c0f35c29 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,9 @@ This document outlines major changes between releases.
 
 ## [Unreleased]
 
+### Added
+- Passing an empty meta parameter value raises "Your metadata headers are not supported." error.
+
 ## [0.29.0] - 2023-09-28
 
 ### Added
diff --git a/api/handler/util.go b/api/handler/util.go
index 9ae3e7c6..be4eccc3 100644
--- a/api/handler/util.go
+++ b/api/handler/util.go
@@ -39,6 +39,10 @@ func transformToS3Error(err error) error {
 		return s3errors.GetAPIError(s3errors.ErrAccessDenied)
 	}
 
+	if errorsStd.Is(err, layer.ErrMetaEmptyParameterValue) {
+		return s3errors.GetAPIError(s3errors.ErrUnsupportedMetadata)
+	}
+
 	return s3errors.GetAPIError(s3errors.ErrInternalError)
 }
 
diff --git a/api/layer/neofs.go b/api/layer/neofs.go
index 5a7dcd78..c06481d2 100644
--- a/api/layer/neofs.go
+++ b/api/layer/neofs.go
@@ -127,6 +127,9 @@ type PrmObjectDelete struct {
 // ErrAccessDenied is returned from NeoFS in case of access violation.
 var ErrAccessDenied = errors.New("access denied")
 
+// ErrMetaEmptyParameterValue describes situation when meta parameter was passed but with empty value.
+var ErrMetaEmptyParameterValue = errors.New("meta empty parameter value")
+
 // NeoFS represents virtual connection to NeoFS network.
 type NeoFS interface {
 	// CreateContainer creates and saves parameterized container in NeoFS.
diff --git a/api/layer/object.go b/api/layer/object.go
index c272be4a..173d9188 100644
--- a/api/layer/object.go
+++ b/api/layer/object.go
@@ -183,6 +183,8 @@ func ParseCompletedPartHeader(hdr string) (*Part, error) {
 }
 
 // PutObject stores object into NeoFS, took payload from io.Reader.
+//
+// Returns [ErrMetaEmptyParameterValue] error if any attribute parameter is empty.
 func (n *layer) PutObject(ctx context.Context, p *PutObjectParams) (*data.ExtendedObjectInfo, error) {
 	owner := n.Owner(ctx)
 
@@ -240,6 +242,10 @@ func (n *layer) PutObject(ctx context.Context, p *PutObjectParams) (*data.Extend
 	prm.Attributes = make([][2]string, 0, len(p.Header))
 
 	for k, v := range p.Header {
+		if v == "" {
+			return nil, ErrMetaEmptyParameterValue
+		}
+
 		prm.Attributes = append(prm.Attributes, [2]string{k, v})
 	}
 
diff --git a/docs/aws_s3_compat.md b/docs/aws_s3_compat.md
index e7712c46..a67c2f86 100644
--- a/docs/aws_s3_compat.md
+++ b/docs/aws_s3_compat.md
@@ -255,3 +255,9 @@ See also `GetObject` and other method parameters.
 | 🔵 | DeleteBucketWebsite |          |
 | 🔵 | GetBucketWebsite    |          |
 | 🔵 | PutBucketWebsite    |          |
+
+
+## Metadata
+
+Each meta parameter value must be non-empty. If any parameter value is an empty,
+then "Your metadata headers are not supported." error will be returned on the object put operation.

From 4e5a06acfb0d43bf976916e6a4a614d58a1b3e05 Mon Sep 17 00:00:00 2001
From: Evgenii Baidakov <evgenii@nspcc.io>
Date: Thu, 12 Oct 2023 15:27:52 +0400
Subject: [PATCH 2/2] handler: Remove unnecessary prefix for system package

Signed-off-by: Evgenii Baidakov <evgenii@nspcc.io>
---
 api/handler/util.go | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/api/handler/util.go b/api/handler/util.go
index be4eccc3..4c75beff 100644
--- a/api/handler/util.go
+++ b/api/handler/util.go
@@ -2,7 +2,7 @@ package handler
 
 import (
 	"context"
-	errorsStd "errors"
+	"errors"
 	"net/http"
 	"strconv"
 	"strings"
@@ -34,12 +34,12 @@ func transformToS3Error(err error) error {
 		return err
 	}
 
-	if errorsStd.Is(err, layer.ErrAccessDenied) ||
-		errorsStd.Is(err, layer.ErrNodeAccessDenied) {
+	if errors.Is(err, layer.ErrAccessDenied) ||
+		errors.Is(err, layer.ErrNodeAccessDenied) {
 		return s3errors.GetAPIError(s3errors.ErrAccessDenied)
 	}
 
-	if errorsStd.Is(err, layer.ErrMetaEmptyParameterValue) {
+	if errors.Is(err, layer.ErrMetaEmptyParameterValue) {
 		return s3errors.GetAPIError(s3errors.ErrUnsupportedMetadata)
 	}