[#217] Add errors for cors

Signed-off-by: Angira Kekteeva <kira@nspcc.ru>

api/errors/errors.go

@@ -312,6 +312,10 @@ const (
 	ErrAdminAccountNotEligible
 	ErrServiceAccountNotFound
 	ErrPostPolicyConditionInvalidFormat
+
+	//CORS configuration errors.
+	ErrCORSUnsupportedMethod
+	ErrCORSWildcardExposeHeaders
 )
 
 // error code to Error structure, these fields carry respective
@@ -1909,6 +1913,18 @@ var errorCodes = errorCodeMap{
 		Description:    "Invalid according to Policy: Policy Condition failed",
 		HTTPStatusCode: http.StatusForbidden,
 	},
+	ErrCORSUnsupportedMethod: {
+		ErrCode:        ErrCORSUnsupportedMethod,
+		Code:           "InvalidRequest",
+		Description:    "Found unsupported HTTP method in CORS config",
+		HTTPStatusCode: http.StatusBadRequest,
+	},
+	ErrCORSWildcardExposeHeaders: {
+		ErrCode:        ErrCORSWildcardExposeHeaders,
+		Code:           "InvalidRequest",
+		Description:    "ExposeHeader \"*\" contains wildcard. We currently do not support wildcard for ExposeHeader",
+		HTTPStatusCode: http.StatusBadRequest,
+	},
 	// Add your error structure here.
 }
 
@@ -1945,6 +1961,11 @@ func GetAPIError(code ErrorCode) Error {
 	return errorCodes.toAPIErr(ErrInternalError)
 }
 
+// GetAPIErrorWithError provides API Error with additional error message for input API error code.
+func GetAPIErrorWithError(code ErrorCode, err error) Error {
+	return errorCodes.toAPIErrWithErr(code, err)
+}
+
 // ObjectError - error that linked to specific object.
 type ObjectError struct {
 	Err     error

api/handler/cors.go

@@ -262,13 +262,12 @@ func checkCORS(cors *CORSConfiguration) error {
 	for _, r := range cors.CORSRules {
 		for _, m := range r.AllowedMethods {
 			if _, ok := supportedMethods[m]; !ok {
-				return fmt.Errorf("unsupported HTTP method in CORS config %s", m)
+				return errors.GetAPIErrorWithError(errors.ErrCORSUnsupportedMethod, fmt.Errorf("unsupported method is %s", m))
 			}
 		}
 		for _, h := range r.ExposeHeaders {
 			if h == wildcard {
-				return fmt.Errorf("ExposeHeader \"*\" contains wildcard. We currently do not support wildcard " +
+				return errors.GetAPIError(errors.ErrCORSWildcardExposeHeaders)
-					"for ExposeHeader")
 			}
 		}
 	}