Re: [lisp-snmp] Patch to asn.1 to change from parsergen to a modified cl-yacc

[John F. <jf...@ms...>]

"Chun Tian (binghe)" <bin...@gm...> writes:

> On 2009-2-9, at 14:44, John Fremlin wrote:
>
>> Dear Chun Tian,
>>
>> "Chun Tian (binghe)" <bin...@gm...> writes:
>> [...]
>>>> To support the cool (oid ..) syntax you can easily add "asn.1/" to
>>>> the
>>>> start of the string processed by OID method.
>>>
>>> It's not so easy when you've found following syntax is also well
>>> supported:
>>>
>>> ASN.1 10 > (oid "SNMPv2-SMI::mib-2.SNMPv2-MIB::system")
>>> #<OBJECT-ID SNMPv2-MIB::system (1) [9]>
>>
>> This syntax can easily be supported as follows
>>
>> (defmethod oid-parse ((source string))
>>  (or
>>   (with-input-from-string (s source)
>>     (oid-parse s))
>>   (with-input-from-string (s (concatenate 'string *asn.1-package-
>> prefix* source))
>>     (oid-parse s))))
>
> I'm afraid this function cannot work for (oid "SNMPv2-
> SMI::mib-2.SNMPv2-MIB::system") correctly, you just change it into:

Why do think that?

Look at the function.

First it tries the old way, then it tries with an ASN.1/ prefix.

> (oid "ASN.1/SNMPv2-SMI::mib-2.SNMPv2-MIB::system")

Will this work with the old function? I don't think so, because of
the .

>
> How can you solve the second package name "SNMPv2-MIB" in that string?
>
>>
>>
>> However, *asn.1-package-prefix* cannot contain a "." because of your
>> strange readtable. So it must be changed to something other than
>> "ASN.1/", perhaps "ASN1/"
>
> The strange *oid-readtable* is my way to avoid the use of SPLIT-
> SEQUENCE, it just let #\. be treat as a separator. However, this
> method can cause unnecessary synbol intern in ASN.1 package, not the
> best way to read a OID string.
>
> Give me more time to think out a better solution please.

Cool

>
>>
>>> Well, contact me if you really found your customers use such a MIB
>>> module name, I think we can talk about this issue later:)
>>
>> It's kind of strange that you talk about making your package perfect
>> but
>> have it so arranged that by loading in an MIB file one can overwrite
>> your package itself . . .
>>
>> I guess it's not just C programmers who don't care about security ;-)
>
> The *asn.1-package-prefix* was learnt from Common Lisp's CORBA
> language mapping. I think you've persuaded me, but I cannot change it
> until I can solve the OID reader syntax issue above.

Yes, the "." problem is annoying but it can be avoided by using "ASN1/"
instead . . .

Thanks for your time

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