Package uk.co.westhawk.snmp.stack

Class TimeWindow

java.lang.Object
uk.co.westhawk.snmp.stack.TimeWindow
public class TimeWindow extends Object
TimeWindow contains the lookup tables for the engine Id information. TimeWindow should be created only once. Use the getCurrent() method to access any other method, i.e. 
 if (TimeWindow.getCurrent() == null)
 {
     TimeWindow timew = new TimeWindow();
 }
 boolean known = TimeWindow.getCurrent().isSnmpEngineIdKnown(hostaddr, port);

This class contains two lookup tables. One that maps the host address+port onto the SNMP engine ID and one that keeps the SNMP engine ID with the timeline details about this engine.

Version:
$Revision: 3.15 $ $Date: 2007/04/12 12:55:28 $
Author:
Birgit Arkesteijn
See Also:

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final int
    MaxTimeDifference
    The maximum number of seconds the engine time in the PDU is allowed to differ from my estimated engine time.

  • Constructor Summary

    Constructors
    Constructor
    Description
    TimeWindow()
    Constructor.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    clearTimeWindow(String snmpEngineId)
    Clear all timing information for the given engine ID.
    static TimeWindow
    getCurrent()
    Returns the current reference to this class.
    String
    getSnmpEngineId(String hostaddr, int port)
    Returns the snmp engine ID.
    boolean
    isEngineIdOK(String hostaddr, int port, String snmpEngineId)
    Checks if the engine ID is OK.
    boolean
    isOutsideTimeWindow(String snmpEngineId, int bootsA, int timeA)
    Returns if the time details are outside the time window.
    boolean
    isSnmpEngineIdKnown(String hostaddr, int port)
    Returns if the snmp engine ID is known.
    boolean
    isTimeLineKnown(String snmpEngineId)
    Returns if the timeline details of this snmp engine ID are known.
    void
    setSnmpEngineId(String hostaddr, int port, String snmpEngineId)
    Sets the SNMP engine ID that belongs to the specified hostaddr and port.
    String
    toString()
    Returns the string representation.
    boolean
    updateTimeWindow(String snmpEngineId, int bootsA, int timeA, boolean isAuthentic)
    Tries to update the time window and returns if succeeded.

    Methods inherited from class java.lang.Object

    equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

  • Field Details

    • MaxTimeDifference

      public static final int MaxTimeDifference
      The maximum number of seconds the engine time in the PDU is allowed to differ from my estimated engine time. Values 150.
      See Also:

  • Constructor Details

    • TimeWindow

      public TimeWindow()
      Constructor.

  • Method Details

    • getCurrent

      public static TimeWindow getCurrent()
      Returns the current reference to this class. TimeWindow should be created only once. Use this method to access any other method, i.e. 
       if (TimeWindow.getCurrent() == null) {
     TimeWindow timew = new TimeWindow();
 }
 boolean known = TimeWindow.getCurrent().isSnmpEngineIdKnown(hostaddr, port);
      Returns:
      the current time window

    • getSnmpEngineId

      public String getSnmpEngineId(String hostaddr, int port)
      Returns the snmp engine ID. This method will lookup the engine ID based on the host address and port. If it the engine ID is not known, null will be returned.
      Parameters:
      hostaddr - The host address of the engine ID
      port - The port number of the engine ID
      Returns:
      the snmp engine ID
      See Also:

    • isSnmpEngineIdKnown

      public boolean isSnmpEngineIdKnown(String hostaddr, int port)
      Returns if the snmp engine ID is known. This method will lookup if the engine ID belonging to this hostaddr and port is known.

      When the SNMP engine ID is known, this doesn't necessarily mean that the timeline details of this engine ID are known, since it takes a second discovery step to find out.

      Parameters:
      hostaddr - The host address of the engine ID
      port - The port number of the engine ID
      Returns:
      whether the snmp engine ID is known

    • setSnmpEngineId

      public void setSnmpEngineId(String hostaddr, int port, String snmpEngineId)
      Sets the SNMP engine ID that belongs to the specified hostaddr and port. The old SNMP engine ID (if any) will be overwritten.
      Parameters:
      hostaddr - The host address of the engine ID
      port - The port number of the engine ID
      snmpEngineId - The engine ID

    • isEngineIdOK

      public boolean isEngineIdOK(String hostaddr, int port, String snmpEngineId)
      Checks if the engine ID is OK. If there is no engine ID known for this hostaddr and port, the specified engine ID is added to the table.

      If there is already an engine ID for this hostaddr and port, the method returns true if the specified engine ID is the same as the existing one, and false if they differ. In the latter case the engine ID in the table is not updated.

      Parameters:
      hostaddr - The host address of the engine ID
      port - The port number of the engine ID
      snmpEngineId - The engine ID
      Returns:
      whether the engine ID matches the stored engine ID
      See Also:

    • isTimeLineKnown

      public boolean isTimeLineKnown(String snmpEngineId)
      Returns if the timeline details of this snmp engine ID are known.
      Parameters:
      snmpEngineId - The engine ID
      Returns:
      whether the timeline details are known

    • isOutsideTimeWindow

      public boolean isOutsideTimeWindow(String snmpEngineId, int bootsA, int timeA)
      Returns if the time details are outside the time window. When a response or report is received, the stack first checks the time window before updating it. It always does an update afterwards, even if the message was outside the time window!
      Parameters:
      snmpEngineId - The SNMP engine ID
      bootsA - The SNMP engine boots
      timeA - The SNMP engine time
      Returns:
      true if outside or when no details can be found, false if inside time window
      See Also:

    • updateTimeWindow

      public boolean updateTimeWindow(String snmpEngineId, int bootsA, int timeA, boolean isAuthentic)
      Tries to update the time window and returns if succeeded. When a response or report is received, first check the time window before updating it.

      An update will only occur if the message was authentic and the bootsA and timeA meet the requirements. New data will be inserted if the (bootsA > 0), irrespectively whether the message was authentic or not.

      Parameters:
      snmpEngineId - The SNMP engine ID
      bootsA - The SNMP engine boots
      timeA - The SNMP engine time
      Returns:
      true if update succeeded, or false when not succeeded or when no details could be found.
      See Also:

    • clearTimeWindow

      public void clearTimeWindow(String snmpEngineId)
      Clear all timing information for the given engine ID. This stinks, but occasionally the router's time window will slip outside of the acceptable window or will reboot without updating its "reboots" parameter. If you care more about security than functionality then never ever use this. Added on request of Steve A Cochran (steve@more.net).
      Parameters:
      snmpEngineId - The engine to clear
      Since:
      5_2

    • toString

      public String toString()
      Returns the string representation.
      Overrides:
      toString in class Object
      Since:
      4_14