Re: SNMPv3 - problem with auth/encr sessions with Perl module

Dnia poniedzia=B3ek, 9 pa=BCdziernika 2006 18:58, ML napisa=B3:

> So, this looks like some Windows-specific issue - I had some time to
> experiment and it not only fails to run properly using 5.3.1 "official"
> version from windows installer, but also on my own, private build built
> with MS VC++ Express 2005.
>
> Are there any easy ways to debug a binary part of a perl module (maybe
> except for poor man's debugging, i.e. printf() ;))?

Having nothing else, I tried the poor man's debug, and here's what I found =

out.
It looks like there's some strange variable visibility problem here =

(threads?). I'm not sure of the exact cause of this, because I don't know t=
he =

architecture of Net-SNMP as a whole, but the following dirty-hacky patch =

allows the Perl module to work for us.

---8<---
--- SNMP.xs.orig 2006-10-10 18:55:47.894372444 +0200
+++ SNMP.xs 2006-10-10 19:00:19.851368694 +0200
@@ -2700,6 +2700,10 @@
/* u_char context_eng_id_buf[ENG_ID_BUF_SIZE]; */
SnmpSession session =3D {0};
SnmpSession *ss =3D NULL;
+
+ oid mySHAOID[10] =3D { 1, 3, 6, 1, 6, 3, 10, 1, 1, 3 };
+ oid myAESOID[10] =3D { 1, 3, 6, 1, 6, 3, 10, 1, 2, 4 };
+
int verbose =3D SvIV(perl_get_sv("SNMP::verbose", 0x01 | 0x04));

__libraries_init("perl");
@@ -2742,7 +2746,7 @@
#endif
if (!strcmp(auth_proto, "SHA")) {
session.securityAuthProto =3D
- snmp_duplicate_objid(usmHMACSHA1AuthProtocol,
+ snmp_duplicate_objid(/*usmHMACSHA1AuthProtocol*/ mySHAO=
ID,
USM_AUTH_PROTO_SHA_LEN);
session.securityAuthProtoLen =3D USM_AUTH_PROTO_SHA_LEN;
} else if (!strcmp(auth_proto, "DEFAULT")) {
@@ -2792,7 +2796,7 @@
#endif
if (!strncmp(priv_proto, "AES", 3)) {
session.securityPrivProto =3D
- snmp_duplicate_objid(usmAESPrivProtocol,
+ snmp_duplicate_objid(/*usmAESPrivProtocol*/ myAESOID,
USM_PRIV_PROTO_AES_LEN);
session.securityPrivProtoLen =3D USM_PRIV_PROTO_AES_LEN;
} else if (!strcmp(priv_proto, "DEFAULT")) {
---8<---

(we were only interested in SHA and AES)
Without this, usm... variables are pure garbage, and that's the reason why =

generate_Ku fails (actually, it's snmp_oid_compare() causing the fault).
This may have something to do with ActiveState's Perl - if I get this right=
, =

Perl is loading SNMP.dll when it needs something what SNMP.pm needs. And =

usm... variables apparently are in netsnmp.dll and they are using the very =

dll's stack (?), and they cannot be accessed from SNMP.dll (? right?).
Anyway, I'm sure that would be a very straightforward fix for you knowing h=
ow =

Net-SNMP is structured. Please keep me informed about any news.

-- =

best regards,
ML

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