[#188] Improve content-type detector

Signed-off-by: Aleksey Kravchenko <al.kravchenko@yadro.com>

internal/handler/head.go

@@ -45,7 +45,11 @@ func (h *Handler) headObject(ctx context.Context, req request, objectAddress oid
 	}
 
 	req.Response.Header.Set(fasthttp.HeaderContentLength, strconv.FormatUint(obj.PayloadSize(), 10))
-	var contentType string
+	var (
+		contentType string
+		filename    string
+		filepath    string
+	)
 	for _, attr := range obj.Attributes() {
 		key := attr.Key()
 		val := attr.Value()
@@ -69,8 +73,15 @@ func (h *Handler) headObject(ctx context.Context, req request, objectAddress oid
 			req.Response.Header.Set(fasthttp.HeaderLastModified, time.Unix(value, 0).UTC().Format(http.TimeFormat))
 		case object.AttributeContentType:
 			contentType = val
+		case object.AttributeFilePath:
+			filepath = val
+		case object.AttributeFileName:
+			filename = val
 		}
 	}
+	if filename == "" {
+		filename = filepath
+	}
 
 	idsToResponse(&req.Response, obj)
 
@@ -85,7 +96,7 @@ func (h *Handler) headObject(ctx context.Context, req request, objectAddress oid
 			}
 
 			return h.frostfs.RangeObject(ctx, prmRange)
-		})
+		}, filename)
 		if err != nil && err != io.EOF {
 			req.handleFrostFSErr(err, start)
 			return