Re: [netmod] escapes - WAS: [Netconf] [Technical Errata Reported] RFC6536 (3862)

[Jernej Tuljak <[e-mail]>]

I've read that section a couple of times now and I now agree with Martin 
that "\*" is currently equivalent to '\*'. My reading would probably be 
correct if there was no second comma in the text I quoted. Oh, well...

    Within a double-quoted string (enclosed within " "), a backslash
    character may introduce a special character, which depends on the
    character that immediately follows the backslash:

would be better, no?

Jernej

Dne 10.1.2014 15:31, piše Ladislav Lhotka:
> On 10 Jan 2014, at 14:58, Jernej Tuljak <[e-mail]> wrote:
>
>> If this is true, then it is RFC6020 that needs a clarification on this. Namely, that the "special character" which follows a backslash need not be special and that it does not represent an escape sequence in such a case.
>>
>>    Within a double-quoted string (enclosed within " "), a backslash
>>    character introduces a special character, which depends on the
>>    character that immediately follows the backslash:
>>
>>     \n      new line
>>     \t      a tab character
>>     \"      a double quote
>>     \\      a single backslash
>>
>> My reading is that a backslash starts a YANG escape sequence and may therefore be removed during string dequoting. A "\*" ends up as *, which is not equivalent to '\*’.
> In XSD regular expressions, which are also used by YANG, it is an error if a backslash plus something is not defined as an escape sequence. So I think YANG should behave the same for double-quoted string, i.e. a backslash followed by something else than the four characters listed above should be flagged as an error (“illegal escape”).
>
> Lada
>
>> Please move this discussion over to NETMOD it that's the case.
>>
>> Jernej
>>
>> Dne 10.1.2014 14:40, piše Martin Bjorklund:
>>> Hi,
>>>
>>> This errata should be rejected.  "\*" is equvalent to '\*'.  \* in a
>>> double quoted string is not an escape sequence, which means that the
>>> characters are interpreted literally, i.e. the two characters \
>>> followed by *.
>>>
>>> The same goes for errata 3863.
>>>
>>> /martin
>>>
>>> RFC Errata System <[e-mail]> wrote:
>>>> The following errata report has been submitted for RFC6536,
>>>> "Network Configuration Protocol (NETCONF) Access Control Model".
>>>>
>>>> --------------------------------------
>>>> You may review the report below and at:
>>>> http://www.rfc-editor.org/errata_search.php?rfc=6536&eid=3862
>>>>
>>>> --------------------------------------
>>>> Type: Technical
>>>> Reported by: Jernej Tuljak <[e-mail]>
>>>>
>>>> Section: 3.5.2.
>>>>
>>>> Original Text
>>>> -------------
>>>>       typedef matchall-string-type {
>>>>         type string {
>>>>           pattern "\*";
>>>>         }
>>>>         description
>>>>           "The string containing a single asterisk '*' is used
>>>>            to conceptually represent all possible values
>>>>            for the particular leaf using this data type.";
>>>>       }
>>>>
>>>> Corrected Text
>>>> --------------
>>>>       typedef matchall-string-type {
>>>>         type string {
>>>>           pattern '\*';
>>>>         }
>>>>         description
>>>>           "The string containing a single asterisk '*' is used
>>>>            to conceptually represent all possible values
>>>>            for the particular leaf using this data type.";
>>>>       }
>>>>
>>>> Notes
>>>> -----
>>>> As per RFC6020, Section 6.1.3., a backslash within a double-quoted
>>>> string introduces a special character. The only valid escape sequences
>>>> inside a double-quoted YANG string are: \n, \t, \" and \. As \* is not
>>>> a valid escape sequence, a single quoted string should be used to
>>>> specify the offending pattern statement's argument. The quotes could
>>>> also be omitted.
>>>>
>>>> Instructions:
>>>> -------------
>>>> This errata is currently posted as "Reported". If necessary, please
>>>> use "Reply All" to discuss whether it should be verified or
>>>> rejected. When a decision is reached, the verifying party (IESG)
>>>> can log in to change the status and edit the report, if necessary.
>>>>
>>>> --------------------------------------
>>>> RFC6536 (draft-ietf-netconf-access-control-07)
>>>> --------------------------------------
>>>> Title : Network Configuration Protocol (NETCONF) Access Control Model
>>>> Publication Date    : March 2012
>>>> Author(s)           : A. Bierman, M. Bjorklund
>>>> Category            : PROPOSED STANDARD
>>>> Source              : Network Configuration
>>>> Area                : Operations and Management
>>>> Stream              : IETF
>>>> Verifying Party     : IESG
>>>>
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> --
> Ladislav Lhotka, CZ.NIC Labs
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