On Fri, Feb 10, 2012 at 7:16 PM, Bart Van Assche <[email protected]> wrote:
> However, I found this in RFC 3414 (http://tools.ietf.org/html/rfc3414):
>
> When an SNMP engine is first installed, it sets its local values of
> snmpEngineBoots and snmpEngineTime to zero. If snmpEngineTime ever
> reaches its maximum value (2147483647), then snmpEngineBoots is
> incremented as if the SNMP engine has re-booted and snmpEngineTime is
> reset to zero and starts incrementing again.
>
> I'll see what needs to be changed in the patch to make it compliant with
> RFC 3414.
>
Any comments about the follow-up patch below ?
---
snmplib/snmpv3.c | 18 +++++++++++++++---
1 files changed, 15 insertions(+), 3 deletions(-)
diff --git a/snmplib/snmpv3.c b/snmplib/snmpv3.c
index e98a3e9..01941e1 100644
--- a/snmplib/snmpv3.c
+++ b/snmplib/snmpv3.c
@@ -1160,8 +1160,14 @@ snmpv3_generate_engineID(size_t * length)
} /* end snmpv3_generate_engineID() */
/**
- * Return the number of seconds since the SNMPv3 engine last incremented
- * engine_boots.
+ * Return the value of snmpEngineTime. According to RFC 3414 snmpEngineTime
+ * is a 31-bit counter. engineBoots must be incremented every time that
+ * counter wraps around.
+ *
+ * @see See also <a href="http://tools.ietf.org/html/rfc3414";>RFC 3414</a>.
+ *
+ * @note It is assumed that this function is called at least once every
+ * 2**31 seconds.
*/
u_long
snmpv3_local_snmpEngineTime(void)
@@ -1170,10 +1176,16 @@ snmpv3_local_snmpEngineTime(void)
netsnmp_feature_require(calculate_sectime_diff)
#endif /* NETSNMP_FEATURE_CHECKING */
+ static uint32_t last_engineTime;
struct timeval now;
+ uint32_t engineTime;
netsnmp_get_monotonic_clock(&now);
- return calculate_sectime_diff(&now, &snmpv3starttime);
+ engineTime = calculate_sectime_diff(&now, &snmpv3starttime) &
0x7fffffffL;
+ if (engineTime < last_engineTime)
+ engineBoots++;
+ last_engineTime = engineTime;
+ return engineTime;
}
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