uk.co.westhawk.snmp.stack

Class TimeWindow

java.lang.Object

uk.co.westhawk.snmp.stack.TimeWindow

public class TimeWindow
extends java.lang.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:

$Revision$ $Date$

Author:

Birgit Arkesteijn

See Also:

getCurrent()

Field Summary

Fields

Modifier and Type	Field and Description
static 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 and Description
TimeWindow() Constructor.

Method Summary

Modifier and Type	Method and Description
void	clearTimeWindow(java.lang.String snmpEngineId) Clear all timing information for the given engine ID.
static TimeWindow	getCurrent() Returns the current reference to this class.
protected java.lang.String	getKey(java.lang.String hostaddr, int port) Returns the key to the engine ID lookup table, based on the specified host address and port.
java.lang.String	getSnmpEngineId(java.lang.String hostaddr, int port) Returns the snmp engine ID.
protected uk.co.westhawk.snmp.stack.TimeWindowNode	getTimeLine(java.lang.String snmpEngineId) Returns the timeline details of the snmp engine ID.
boolean	isEngineIdOK(java.lang.String hostaddr, int port, java.lang.String snmpEngineId) Checks if the engine ID is OK.
boolean	isOutsideTimeWindow(java.lang.String snmpEngineId, int bootsA, int timeA) Returns if the time details are outside the time window.
boolean	isSnmpEngineIdKnown(java.lang.String hostaddr, int port) Returns if the snmp engine ID is known.
boolean	isTimeLineKnown(java.lang.String snmpEngineId) Returns if the timeline details of this snmp engine ID are known.
void	setSnmpEngineId(java.lang.String hostaddr, int port, java.lang.String snmpEngineId) Sets the SNMP engine ID that belongs to the specified hostaddr and port.
protected uk.co.westhawk.snmp.stack.TimeWindowNode	setTimeLine(java.lang.String snmpEngineId, uk.co.westhawk.snmp.stack.TimeWindowNode newNode) Sets the timeline details of the snmp engine ID.
java.lang.String	toString() Returns the string representation.
boolean	updateTimeWindow(java.lang.String snmpEngineId, int bootsA, int timeA, boolean isAuthentic) Tries to update the time window and returns if succeeded.
protected void	updateTimeWindows() Updates the estimated engine time of all gathered time details.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

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:

Constant Field Values

Constructor Detail

TimeWindow

public TimeWindow()

Constructor.

Method Detail

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 java.lang.String getSnmpEngineId(java.lang.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(String, int)

isSnmpEngineIdKnown

public boolean isSnmpEngineIdKnown(java.lang.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(java.lang.String hostaddr,
                            int port,
                            java.lang.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(java.lang.String hostaddr,
                            int port,
                            java.lang.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:

setSnmpEngineId(String, int, String)

isTimeLineKnown

public boolean isTimeLineKnown(java.lang.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(java.lang.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(String, int, int, boolean)

updateTimeWindow

public boolean updateTimeWindow(java.lang.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:

isOutsideTimeWindow(String, int, int)

clearTimeWindow

public void clearTimeWindow(java.lang.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

updateTimeWindows

protected void updateTimeWindows()

Updates the estimated engine time of all gathered time details. It calculates the seconds that passed since the last call and updates all time window nodes accordingly.

See Also:

setTimeLine(String, TimeWindowNode), getTimeLine(String)

getKey

protected java.lang.String getKey(java.lang.String hostaddr,
                                  int port)

Returns the key to the engine ID lookup table, based on the specified host address and port.

Parameters:

hostaddr - The host address

port - The port

Returns:

the key

getTimeLine

protected uk.co.westhawk.snmp.stack.TimeWindowNode getTimeLine(java.lang.String snmpEngineId)

Returns the timeline details of the snmp engine ID. If there are no matching timeline details for this engine ID, null will be returned. The timeline details will be updated before the node is retrieved from the table.

Parameters:

snmpEngineId - The engine ID

Returns:

The timeline details

See Also:

updateTimeWindows()

setTimeLine

protected uk.co.westhawk.snmp.stack.TimeWindowNode setTimeLine(java.lang.String snmpEngineId,
                                                               uk.co.westhawk.snmp.stack.TimeWindowNode newNode)

Sets the timeline details of the snmp engine ID. The timeline details will be updated before the node is put in the table.

Parameters:

snmpEngineId - The engine ID

newNode - The added time window node node

Returns:

The timeline details

See Also:

updateTimeWindows()

toString

public java.lang.String toString()

Returns the string representation.

Overrides:

toString in class java.lang.Object

Since:

4_14