/// <summary>Decode BER encoded Pdu</summary>
/// <remarks>
/// Decodes the protocol data unit from the passed buffer. If an error
/// occurs during the decoding sequence then an AsnDecodingException is
/// thrown by the method. The value is decoded using the AsnEncoder
/// passed to the object.
/// </remarks>
/// <param name="buffer">BER encoded buffer</param>
/// <param name="offset">The offset byte to begin decoding</param>
/// <returns>Buffer position after the decoded value</returns>
/// <exception cref="OverflowException">Thrown when header points to more data then is available.</exception>
public override int Decode(byte[] buffer, int offset)
{
byte asnType = ParseHeader(buffer, ref offset, out int headerLength);
if (offset + headerLength > buffer.Length)
{
throw new OverflowException("Insufficient data in packet");
}
base.Type = asnType;
// request id
offset = requestId.Decode(buffer, offset);
// error status
offset = errorStatus.Decode(buffer, offset);
// error index
offset = errorIndex.Decode(buffer, offset);
// clean out the current variables
VbList.Clear();
// decode the Variable binding collection
offset = VbList.Decode(buffer, offset);
// if Pdu is an SNMP version 2 TRAP, remove sysUpTime and trapObjectID from the VarBinds array
if (Type == EPduType.V2Trap || Type == EPduType.Inform)
{
if (VbList.Count > 0)
{
if (VbList[0].Oid.Equals(SnmpConstants.SysUpTime))
{
TrapSysUpTime.Set(VbList[0].Value);
VbList.RemoveAt(0); // remove sysUpTime
}
}
if (VbList.Count > 0)
{
if (VbList[0].Oid.Equals(SnmpConstants.TrapObjectId))
{
trapObjectID.Set((Oid)VbList[0].Value);
VbList.RemoveAt(0); // remove sysUpTime
}
}
}
return(offset);
}
/// <summary>Return string dump of the Pdu class.</summary>
/// <returns>String content of the Pdu class.</returns>
public override string ToString()
{
StringBuilder str = new StringBuilder();
str.Append("PDU-");
switch (base.Type)
{
case (byte)EPduType.Get:
str.Append("Get");
break;
case (byte)EPduType.GetNext:
str.Append("GetNext");
break;
case (byte)EPduType.GetBulk:
str.Append("GetBulk");
break;
case (byte)EPduType.V2Trap:
str.Append("V2Trap");
break;
case (byte)EPduType.Response:
str.Append("Response");
break;
case (byte)EPduType.Inform:
str.Append("Inform");
break;
default:
str.Append("Unknown");
break;
}
str.Append("\n");
str.AppendFormat("RequestId: {0}\n", RequestId);
if (Type != EPduType.GetBulk)
{
str.AppendFormat("ErrorStatus: {0}\nError Index: {1}\n", ErrorStatus, ErrorIndex);
}
else
{
str.AppendFormat("MaxRepeaters: {0}\nNonRepeaters: {1}\n", MaxRepetitions, NonRepeaters);
}
if (Type == EPduType.V2Trap || Type == EPduType.Inform)
{
str.AppendFormat("TimeStamp: {0}\nTrapOID: {1}\n", TrapSysUpTime.ToString(), TrapObjectID.ToString());
}
str.AppendFormat("VbList entries: {0}\n", VbCount);
if (VbCount > 0)
{
foreach (Vb v in VbList)
{
str.AppendFormat("Vb: {0}\n", v.ToString());
}
}
return(str.ToString());
}
