On Wed, Aug 10, 2005 at 08:44:22AM +0100, saifulla Mohd Abdul wrote:
>
> Hi,
>
> Yes, we don't need to process request with
> OID (sub-id count more than 128).
>
> RFC 3416 says:
>
> SNMP limits OBJECT IDENTIFIER values to a maximum
> of 128 sub-identifiers, where each sub-identifier has
> a maximum value of
> 2**32-1.
>
> Any PDU with an OID having More than 128
> sub-identifiers is an illegal PDU, and causes an
> ASN.1 Parse error which is counted by RFC 3418's
> snmpInASNParseErrs.
<snip>
Now this is a different matter than I was commenting on
earlier (previous email in thread quoted):
> > SMA> As per the SNMP standard, the MAX OID length
> > should
> > SMA> not be > 128 bytes.
So.. was the original question regarding sub-identifiers,
or bytes? I have seen objects in the wild with greater than 128 bytes,
but not 128 sub-identifiers. It seems like maybe MAX_OID_LEN used to refer
to the maximum byte count. There's a reference in include/types.h to setting
the oid type to u_char where EIGHTBIT_SUBIDS is set.
#ifndef MAX_SUBID /* temporary - duplicate definition protection
*/
#ifndef EIGHTBIT_SUBIDS
typedef u_long oid;
#define MAX_SUBID 0xFFFFFFFF
#else
typedef u_char oid;
#define MAX_SUBID 0xFF
#endif
#endif
I'm unable to find any further reference to EIGHTBIT_SUBIDS anywhere
in the source code, so perhaps it's an obsolete artifact. If it is, maybe
it should be removed.
So.. the max oid size should be MAX_OID_LEN * sizeof(u_long),
which is a much bigger string than MAX_OID_LEN * sizeof(u_char): 512 vs. 128.
Probably everyone else but me already knew all that. :-)
Btw, according to the gcc docs int is always 32 bits, long can
be 64 on 64 bit platforms. If the spec says the max val is 2 ** 32 - 1,
then shouldn't that be u_int instead of u_long?
Austin
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