[SNMP4J] Agent bug

[Frank Fock]

Hi William,

The  correct implementation of the MOScalar.isVolatileByDefault method
should have read as follows:

  private static boolean isVolatileByDefault(Variable value) {
    if (value == null) {
      return true;
    }
    switch (value.getSyntax()) {
      case SMIConstants.SYNTAX_COUNTER32:
      case SMIConstants.SYNTAX_COUNTER64: {
        return true;
      }
      default:
        return false;
    }
  }

This fix will be of course in the next alpha.

Best regards,
Frank

Simakis, William wrote:

>Hi,
>
>I am trying to implement a simple agent and I am trying to familiarize myself with the API etc. I am getting the following exception when I run the TestAgent example.
>
>Exception in thread "main" java.lang.NullPointerException
>	at org.snmp4j.agent.mo.MOScalar.isVolatileByDefault(MOScalar.java:54)
>	at org.snmp4j.agent.mo.MOScalar.<init>(MOScalar.java:50)
>	at org.snmp4j.agent.mo.snmp.SnmpFrameworkMIB$1.<init>(SnmpFrameworkMIB.java:56)
>	at org.snmp4j.agent.mo.snmp.SnmpFrameworkMIB.createMOs(SnmpFrameworkMIB.java:56)
>	at org.snmp4j.agent.mo.snmp.SnmpFrameworkMIB.<init>(SnmpFrameworkMIB.java:52)
>	at org.snmp4j.agent.BaseAgent.init(BaseAgent.java:80)
>	at org.snmp4j.agent.test.TestAgent.main(TestAgent.java:270)
>
>Here is the problem in the code:
>
>1) In SnmpFrameworkMIB.createMOs, a MOScalar is created and passed null to the constructor for the value parameter. 
>2) The MOScalar constructor calls isVolatileByDefault with the null reference
>3) isVolatileByDefault tries to call value.getSyntax without checking if the reference is null. 
>
>from the name I would guess it should return false if the value is null but I am not that familiar with what it is used for.
>
>Bill
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