/**
* Decodes a <code>Variable</code> from an <code>InputStream</code>.
*
* @param inputStream an <code>InputStream</code> containing a BER encoded byte stream.
* @throws IOException
*/
@Override
public void decodeBER(BERInputStream inputStream) throws IOException {
MutableByte pduType = new MutableByte();
int length = BER.decodeHeader(inputStream, pduType);
int pduStartPos = (int) inputStream.getPosition();
switch (pduType.getValue()) {
case PDU.SET:
case PDU.GET:
case PDU.GETNEXT:
case PDU.V1TRAP:
case PDU.RESPONSE:
break;
// The following PDU types are not supported by the SNMPv1 standard!
case PDU.NOTIFICATION:
case PDU.INFORM:
if (SNMP4JSettings.isAllowSNMPv2InV1()) {
break;
}
// fall through
default:
throw new IOException("Unsupported PDU type: " + pduType.getValue());
}
this.setType(pduType.getValue());
if (getType() == PDU.V1TRAP) {
enterprise.decodeBER(inputStream);
agentAddress.decodeBER(inputStream);
genericTrap.decodeBER(inputStream);
specificTrap.decodeBER(inputStream);
timestamp.decodeBER(inputStream);
} else {
requestID.decodeBER(inputStream);
errorStatus.decodeBER(inputStream);
errorIndex.decodeBER(inputStream);
}
// reusing pduType here to save memory ;-)
pduType = new BER.MutableByte();
int vbLength = BER.decodeHeader(inputStream, pduType);
if (pduType.getValue() != BER.SEQUENCE) {
throw new IOException("Encountered invalid tag, SEQUENCE expected: " + pduType.getValue());
}
// rest read count
int startPos = (int) inputStream.getPosition();
variableBindings = new Vector<>();
while (inputStream.getPosition() - startPos < vbLength) {
VariableBinding vb = new VariableBinding();
vb.decodeBER(inputStream);
if (!isVariableV1(vb.getVariable())) {
throw new MessageException("Counter64 encountered in SNMPv1 PDU " + "(RFC 2576 §4.1.2.1)");
}
variableBindings.add(vb);
}
if (BER.isCheckSequenceLength()) {
BER.checkSequenceLength(vbLength, (int) inputStream.getPosition() - startPos, this);
BER.checkSequenceLength(length, (int) inputStream.getPosition() - pduStartPos, this);
}
}
/**
* Check if the given variable can be encoded into a SNMPv1 PDU.
*
* @param v a variable value (must not be <code>null</code>).
* @return <code>true</code> if the variable is SNMPv1 compatible (or {@link
* org.snmp4j.SNMP4JSettings#isAllowSNMPv2InV1()} is true), <code>false</code> otherwise, i.e.
* if <code>v</code> is an instance of {@link Counter64}.
* @since 1.9.1c
*/
protected boolean isVariableV1(Variable v) {
return !(v instanceof Counter64) || SNMP4JSettings.isAllowSNMPv2InV1();
}