On 06/07/07, Need Help <[EMAIL PROTECTED]> wrote:
> typedef struct MIB_OCTET_STRING_s {
> u_long length;
> u_char textStr[50];
>
> } MIB_OCTET_STRING;
Note that 'textStr' is effective a "char *", pointing to the start
of the string value.
> snmp_set_var_typed_value(requests->requestvb,
> ASN_OCTET_STR,
> (u_char *)&serialNumber.textStr,
> serialNumber.length);
> }
Not quite. serialNumber.textStr is already a pointer to the
string value, so you don't need to take the address of it.
Try
snmp_set_var_typed_value(requests->requestvb,
ASN_OCTET_STR,
(u_char *)serialNumber.textStr,
serialNumber.length);
}
> Now, in the "handle_ocStbHostCapabilities()" routine (not shown), I noticed
> I need to supply the scalar value via the same exact
> "snmp_set_var_typed_value" routine interface using a pointer/length
> combination.
That will work, yes.
> Since the "HostCapabilities" value is defined as an "Integer"
> value in the MIB file, I was expecting to call a new routine which had an
> interface allowing me to provide "u_int" value instead of a pointer/length
> combination.
You can do that as well - see snmp_set_var_typed_integer()
(though we don't currently have an unsigned version of this routine)
> Are all scalar values treated the same in that I will need to
> provide a pointer and byte length for each?
Fundamentally, yes. This is how *all* values are handled internally,
for both scalar and table objects. There are various higher-level
convenience routines that accept values in a more "natural" format,
but they are then converted to this pointer/length format behind
the scenes.
> If so, then I guess NetSNMP
> figures out the byte is really not a character, but is in fact an Integer
Don't think of this as a character pointer. It would be more appropriate
to regard it as "void*" - as an arbitrary (opaque) pointer that needs to
be cast to the appropriate form before using.
The reason for using "char*" rather than "void*" is historical.
> Also, what is the "maximum length" of a scalar value which can be passed
> into the "snmp_set_var_typed_value" routine?
For integer-based values, either 32-bit or 64-bit, depending on the syntax.
For character-based values (including opaque), the theoretical maximum
is 65K (although particular MIB objects may have a smaller maximum size).
For OID-based values, the maximum length is 128 subidentifiers (each of
which is up to 32-bits).
Dave
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