Re: perl agent problem with COUNTER64

I have managed to modify "perl/agent/agent.xs" and it seems working right so
far.
Here's the patch.

Best regards,
Neptune Ning

2009/6/14 Neptune Ning (plan) <[email protected]>

> HI, All:
>
> I'am recently writing extension using perl. I've came across a problem with
> ASN_COUNTER64 type.
> when I use COUNTER64 to return a value, I will get a wired value from
> snmpwalk.  The machine I used is X86_64 and perl was compiled to support a
> 64bit number.
> Even when I uses setValue (ASN_COUNTER64, 1) ,  the value I get from
> snmpwalk is quite large.
>
> I've looked into the code of net-snmp-5.4.2.1 for some answers.
> In "perl/agent/agent.xs:833-863":  it gets a numeric "utmp" from SvIV or
> converts from a string. and call
>
> snmp_set_var_typed_value(request->requestvb, (u_char)type,
>                                        (u_char *) &utmp, sizeof(utmp));
>
> I printed the value of "utmp", it was right.
> then I followed into "snmp_set_var_value()" which called by
> snmp_set_var_typed_value(), between line 916-925 handels COUNTER64 type:
>
>  vars->val_len = sizeof(struct counter64);
>  memmove(vars->val.counter64, value, vars->val_len);
>
> It seemed directly copy the 64bit value into a struct counter64,
> but I found the definition of struct counter64 in
> "include/net-snmp/library/asn1.h"
>
>    struct counter64 {
>         u_long          high;
>         u_long          low;
>    };
>
> In X86_64 platform sizeof (struct counter64) will be 16 (128bit), therefor
> setValue (ASN_COUNTER64, 0x100000002),
> might get :
> high=0x100000002, low=unexpected value
>
> If I change the definition of struct counter64 into
>
> struct counter64 {
>         uint32_t        low;
>         uint32_t        high;
> }
>
> my perl extension which use counter64 will work, but other OIDs  like
> IF-MIB::ifHCInOctets will be broken. the log was like:
>
> snmp_build: unknown failuresend response: Error building ASN.1
> representation (build uint64 size 16: s/b 8)
>     -- ifHCInOctets.1
>
> Do you have any suggestion? I would appreciate a quick solution because the
> time I get for my project is limited.
>
> -------------------
>
> Best regards,
> Neptune Ning
>
>

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*** net-snmp-5.4.2.1-1/perl/agent/agent.xs	2009-06-14 22:14:31.000000000 +0800
--- net-snmp-5.4.2.1-2/perl/agent/agent.xs	2009-06-14 22:15:49.000000000 +0800
***************
*** 771,776 ****
--- 771,777 ----
          u_char *oidbuf = NULL;
          size_t ob_len = 0, oo_len = 0;
          netsnmp_request_info *request;
+ 	struct counter64 _c64;
          u_long utmp;
          long ltmp;
  	oid myoid[MAX_OID_LEN];
***************
*** 835,842 ****
                     SvIOK(value)) {
  		  /* Good - got a real one (or a blessed scalar which we have to hope will turn out OK) */
  		  utmp = SvIV(value);
                    snmp_set_var_typed_value(request->requestvb, (u_char)type,
!                                        (u_char *) &utmp, sizeof(utmp));
  		  RETVAL = 1;
  		  break;
  	      }
--- 836,846 ----
                     SvIOK(value)) {
  		  /* Good - got a real one (or a blessed scalar which we have to hope will turn out OK) */
  		  utmp = SvIV(value);
+ 		  _c64.high = utmp >> 32;
+ 		  _c64.low = utmp & 0xFFFFFFFF;
                    snmp_set_var_typed_value(request->requestvb, (u_char)type,
!                                        (u_char *) &_c64, sizeof(_c64));
! 
  		  RETVAL = 1;
  		  break;
  	      }
***************
*** 849,857 ****
  			RETVAL = 0;
  			break;
  		  }
! 
                    snmp_set_var_typed_value(request->requestvb, (u_char)type,
!                                        (u_char *) &utmp, sizeof(utmp));
  		  RETVAL = 1;
  		  break;
  	      }
--- 853,863 ----
  			RETVAL = 0;
  			break;
  		  }
! 		  _c64.high = utmp >> 32;
! 		  _c64.low = utmp & 0xFFFFFFFF;
                    snmp_set_var_typed_value(request->requestvb, (u_char)type,
!                                        (u_char *) &_c64, sizeof(_c64));
! 
  		  RETVAL = 1;
  		  break;
  	      }