On Thu, 2013-10-03 at 18:14 +0000, Rafael Ratacheski wrote:
> Hello, I'm having troubles in request and save the value of the
> ipNetToMediaPhysAddress OID.
>
> My routine get the MAC Adress, but only a half of the value.
>
> What I'm doing wrong? Can you help me?
>
> if (vars->type == ASN_OCTET_STR) {
> u_long *sp = malloc(1+id_len);
What is the value of id_len? I'll guess it is 6 for further analysis.
In that case you have just allocated 7 bytes of memory for a 32-bit
unsigned integer (or a 64-bit one - even worse...)
> memcpy(sp, vars->val.string, id_len);
You then copy the six bytes of the mac address to the newly allocated
memory. This is actually correct, but rather odd given the types.
> const char *teste = htonl(*sp);
And then you assign the byte swapped value of the first four octets of
the mac address to the pointer variable teste. This is undefined
according to the C standard.
> printf("value #%d is a string: %x \n", count++, teste);
Then you print the address that teste refers to,
> free(sp);
Finally you frees the allocated memory. Good.
> }
>
So, to answer your questions:
> What am I doing wrong?
Just about everything.
> Can you help me?
Well...
I would write that snippet as
if (vars->type == ASN_OCTET_STR) {
int i;
printf("value #%d is a string: ", count++);
for (i = 0; i < vars->val_len; ++i)
printf("%x", vars->val.string[i]);
puts("");
}
(Ok, I probably would put it in a char buffer and print it all at once
rather than repeatedly call printf but this is the easy version)
... but that probably isn't what you really wanted to know.
/MF
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