[netmod] [Errata Verified] RFC7950 (5698)

RFC Errata System <rfc-editor@rfc-editor.org> Wed, 24 April 2019 11:19 UTC

To: andy@yumaworks.com, mbj@tail-f.com
From: RFC Errata System <rfc-editor@rfc-editor.org>
Cc: ibagdona@gmail.com, iesg@ietf.org, netmod@ietf.org, rfc-editor@rfc-editor.org
Content-Type: text/plain; charset="UTF-8"
Message-Id: <20190424111859.35E2EB80D43@rfc-editor.org>
Date: Wed, 24 Apr 2019 04:18:59 -0700
Archived-At: <https://mailarchive.ietf.org/arch/msg/netmod/quwa-75NhW3uO5Gz9oVBwXXN19U>
Subject: [netmod] [Errata Verified] RFC7950 (5698)
Precedence: list

The following errata report has been verified for RFC7950,
"The YANG 1.1 Data Modeling Language". 

--------------------------------------
You may review the report below and at:
http://www.rfc-editor.org/errata/eid5698

--------------------------------------
Status: Verified
Type: Editorial

Reported by: Andy Bierman <andy@yumaworks.com>
Date Reported: 2019-04-18
Verified by: Ignas Bagdonas (IESG)

Section: 7.5.4.3

Original Text
-------------
     container interface {
       leaf ifType {
         type enumeration {
           enum ethernet;
           enum atm;
         }
       }
       leaf ifMTU {
         type uint32;
       }
       must 'ifType != "ethernet" or ifMTU = 1500' {
         error-message "An Ethernet MTU must be 1500";
       }
       must 'ifType != "atm" or'
          + ' (ifMTU <= 17966 and ifMTU >= 64)' {
         error-message "An ATM MTU must be 64 .. 17966";
       }
     }


Corrected Text
--------------
     container interface {
       leaf ifType {
         type enumeration {
           enum ethernet;
           enum atm;
         }
       }
       leaf ifMTU {
         type uint32;
       }
       must 'string(ifType) != "ethernet" or ifMTU = 1500' {
         error-message "An Ethernet MTU must be 1500";
       }
       must 'string(ifType) != "atm" or'
          + ' (ifMTU <= 17966 and ifMTU >= 64)' {
         error-message "An ATM MTU must be 64 .. 17966";
       }
     }


Notes
-----
The intent of the example is for each must-stmt to be false if the ifType leaf does not exist.
However the XPath is incorrect.

>From the XPath 1.0 spec, section 3.4, para 5

If one object to be compared is a node-set and the other is a string, then the comparison will be true if and only if there is a node in the node-set such that the result of performing the comparison on the string-value of the node and the other string is true. 

The empty node-set is not implicitly converted to an empty string for a = or != comparison.
Instead the string() function must explicitly convert the node-set to a string

--------------------------------------
RFC7950 (draft-ietf-netmod-rfc6020bis-14)
--------------------------------------
Title               : The YANG 1.1 Data Modeling Language
Publication Date    : August 2016
Author(s)           : M. Bjorklund, Ed.
Category            : PROPOSED STANDARD
Source              : Network Modeling
Area                : Operations and Management
Stream              : IETF
Verifying Party     : IESG

[netmod] [Errata Verified] RFC7950 (5698) RFC Errata System