Package uk.co.westhawk.snmp.stack

Class AbstractSnmpContext

java.lang.Object

uk.co.westhawk.snmp.stack.AbstractSnmpContext

All Implemented Interfaces:

Runnable, EventListener, RawPduListener, SnmpContextBasisFace

Direct Known Subclasses:

SnmpContext, SnmpContextv3Basis

public abstract class AbstractSnmpContext
extends Object
implements SnmpContextBasisFace, Runnable, RawPduListener

This class contains the abstract SNMP context that is needed by every Pdu to send a SNMP v1, v2c or v3 request. The context also provides functionality to receive PDUs.

destroy() should be called when the context is no longer used. This is the only way the threads will be stopped and garbage collected.

Version:

$Revision: 3.33 $ $Date: 2009/03/05 12:48:04 $

Author:

Tim Panton

See Also:

• SnmpContext
• SnmpContextv2c
• SnmpContextv3

Field Summary

Fields inherited from interface uk.co.westhawk.snmp.stack.SnmpContextBasisFace

DEFAULT_PORT, MAXPDU, MSS, STANDARD_SOCKET, TCP_SOCKET

Method Summary

Modifier and Type	Method	Description
boolean	addPdu(Pdu p)	Adds a PDU to the context.
void	addRequestPduListener(RequestPduListener l)	Adds the specified request pdu listener to receive PDUs on the default request pdu port 161 from the host that matches this context.
void	addRequestPduListener(RequestPduListener l, int port)	Adds the specified request pdu listener to receive PDUs on the specified port from the host that matches this context.
void	addRequestPduListener(RequestPduListener l, ListeningContextPool lcontext)	Adds the specified request pdu listener to receive PDUs on the specified listening context that matches this context.
void	addTrapListener(TrapListener l)	Adds the specified trap listener to receive traps on the default trap port 162 from the host that matches this context.
void	addTrapListener(TrapListener l, int port)	Adds the specified trap listener to receive traps on the specified port from the host that matches this context.
void	addTrapListener(TrapListener l, ListeningContextPool lcontext)	Adds the specified trap listener to receive traps on the specified listening context that matches this context.
abstract Object	clone()	Returns a clone of this SnmpContext.
void	destroy()	This method will stop the thread.
abstract byte[]	encodePacket(byte msg_type, int rId, int errstat, int errind, Enumeration ve, Object obj)	Encodes a PDU.
String	getBindAddress()	Returns the local bind address.
String	getDebugString()	Returns the thread usage of the AbstractSnmpContext.
abstract String	getHashKey()	Returns the hash key.
String	getHost()	Returns the host.
String	getHostAddress()	Deprecated. As of 4_14, use getSendToHostAddress()
int	getMaxRecvSize()	Returns the maximum number of bytes this context will read from the socket.
int	getPort()	Returns the port number.
String	getReceivedFromHostAddress()	Returns the IP address string aaa.bbb.ccc.ddd (IPv4) or a:b:c:d:e:f:g:h (IPv6) of the (latest) host the packets where received from.
String	getSendToHostAddress()	Returns the IP address string aaa.bbb.ccc.ddd (IPv4) or a:b:c:d:e:f:g:h (IPv6) of the host the packets where sent to.
String	getTypeSocket()	Returns the type of socket.
abstract int	getVersion()	Returns the SNMP version of this context.
boolean	isDestroyed()	Returns whether or not this context has been destroyed.
abstract Pdu	processIncomingPdu(byte[] message)	Processes an incoming pdu (but not a response).
void	rawPduReceived(RawPduEvent evt)	Invoked when an undecoded pdu is received.
boolean	removePdu(int rid)	Removes a PDU from the context.
void	removeRequestPduListener(RequestPduListener l)	Removes the specified request pdu listener from listening for packets on the default request pdu port 161.
void	removeRequestPduListener(RequestPduListener l, int port)	Removes the specified request pdu listener from listening for packets on the specified port.
void	removeRequestPduListener(RequestPduListener l, ListeningContextPool lcontext)	Removes the specified request pdu listener from listening for packets on the specified listening context.
void	removeTrapListener(TrapListener l)	Removes the specified trap listener from listening for packets on the default trap port 162.
void	removeTrapListener(TrapListener l, int port)	Removes the specified trap listener from listening for packets on the specified port.
void	removeTrapListener(TrapListener l, ListeningContextPool lcontext)	Removes the specified trap listener from listening for packets on the specified listening context.
void	run()	We wait for any incoming packets.
void	sendPacket(byte[] p)	Sends an encoded PDU.
void	setMaxRecvSize(int no)	Sets the maximum number of bytes this context will read from the socket.
void	stop()	Deprecated. As of version 4_12, should use destroy()

Methods inherited from class java.lang.Object

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

Method Details

encodePacket

public abstract byte[] encodePacket(byte msg_type,
 int rId,
 int errstat,
 int errind,
 Enumeration ve,
 Object obj)
                             throws IOException,
EncodingException

Encodes a PDU. This is for internal use only and should NOT be called by the developer. This is called by the the PDU itself and is added to the interface to cover the different kind of Contexts. Has to be overload by each context.

Specified by:

encodePacket in interface SnmpContextBasisFace

Parameters:

msg_type - The message type

rId - The message id

errstat - The error status

errind - The error index

ve - The varbind list

obj - Additional object (only used in SNMPv3)

Returns:

The encoded packet

Throws:

IOException

EncodingException

processIncomingPdu

public abstract Pdu processIncomingPdu(byte[] message)
                                throws DecodingException,
IOException

Processes an incoming pdu (but not a response). Has to be overload by each context.

Specified by:

processIncomingPdu in interface SnmpContextBasisFace

Throws:

DecodingException

IOException

See Also:

• rawPduReceived(uk.co.westhawk.snmp.event.RawPduEvent)

getVersion

public abstract int getVersion()

Returns the SNMP version of this context. Has to be overload by each context.

Specified by:

getVersion in interface SnmpContextBasisFace

Returns:

The version

See Also:

• SnmpConstants.SNMP_VERSION_1
• SnmpConstants.SNMP_VERSION_2c
• SnmpConstants.SNMP_VERSION_3

getHost

public String getHost()

Description copied from interface: SnmpContextBasisFace

Returns the host.

Specified by:

getHost in interface SnmpContextBasisFace

Returns:

The host

getHostAddress

public String getHostAddress()

Deprecated.

As of 4_14, use getSendToHostAddress()

Returns the IP address string aaa.bbb.ccc.ddd (IPv4) or a:b:c:d:e:f:g:h (IPv6) of the host.

Returns:

The IP address of the host

getSendToHostAddress

public String getSendToHostAddress()

Description copied from interface: SnmpContextBasisFace

Returns the IP address string aaa.bbb.ccc.ddd (IPv4) or a:b:c:d:e:f:g:h (IPv6) of the host the packets where sent to.

Specified by:

getSendToHostAddress in interface SnmpContextBasisFace

Returns:

The IP address of the host the packets where sent to.

See Also:

• ContextSocketFace.getSendToHostAddress()

getReceivedFromHostAddress

public String getReceivedFromHostAddress()

Description copied from interface: SnmpContextBasisFace

Returns the IP address string aaa.bbb.ccc.ddd (IPv4) or a:b:c:d:e:f:g:h (IPv6) of the (latest) host the packets where received from.

Specified by:

getReceivedFromHostAddress in interface SnmpContextBasisFace

Returns:

The IP address of the (latest) host the packets where received from.

See Also:

• ContextSocketFace.getReceivedFromHostAddress()

getPort

public int getPort()

Description copied from interface: SnmpContextBasisFace

Returns the port number.

Specified by:

getPort in interface SnmpContextBasisFace

Returns:

The port no

getBindAddress

public String getBindAddress()

Description copied from interface: SnmpContextBasisFace

Returns the local bind address. If bindAddress is null, then the system will pick up a valid local address to bind the socket.

Specified by:

getBindAddress in interface SnmpContextBasisFace

Returns:

The local bind address

getTypeSocket

public String getTypeSocket()

Description copied from interface: SnmpContextBasisFace

Returns the type of socket.

Specified by:

getTypeSocket in interface SnmpContextBasisFace

Returns:

The type of socket

See Also:

• SnmpContextBasisFace.STANDARD_SOCKET
• SnmpContextBasisFace.TCP_SOCKET

getMaxRecvSize

public int getMaxRecvSize()

Returns the maximum number of bytes this context will read from the socket. By default this will be set to MSS (i.e. 1300).

Returns:

The number

Since:

4_12

See Also:

• SnmpContextBasisFace.MSS
• setMaxRecvSize(int)

setMaxRecvSize

public void setMaxRecvSize(int no)

Sets the maximum number of bytes this context will read from the socket. By default this will be set to MSS (i.e. 1300). The default size seems a reasonable size. The problem usually occurs when sending Bulk requests.

If a packet arrives that is bigger than the maximum size of received bytes, the stack will try to decode it nevertheless. The usual error that will occur is:

 Error message: "Incorrect packet. No of bytes received less than packet length."
 

Although UDP datagrams can be fragmented (fragmentation is part of the network layer (IP), not the transport layer (UDP/TCP)), some firewalls reject incoming fragments. Therefor it is best not to set maxRecvSize higher than the largest packet size you can get through your network topology.

Thanks to Pete Kazmier (pete@kazmier.com) for the suggestion.

Note, this property is NOT supported in any of the SNMPContextXXPool classes.

Parameters:

no - The new number

Since:

4_12

See Also:

• SnmpContextBasisFace.MSS
• getMaxRecvSize()

getDebugString

public String getDebugString()

Returns the thread usage of the AbstractSnmpContext. It returns a String in the form of =PO=QR--------------0.

The String represents the array of transmitters. Each character represents a transmitter slot. The transmitters form a thread pool of a maximum size, MAXPDU. Each transmitter is used to wait for one PDU response at a given moment in time. When the response is received the transmitter will stop running, but is not destroyed. It will be reused.

Meaning of each character:

• - a transmitter slot has not yet been allocated a thread
• = there is a thread but it is idle
• A->Z the thread is transmitting a Pdu
• The last character represents the context's recv thread:
  • 0 there isn't one
  • 1 it exists but isn't running
  • 2 it exists and is alive.

Returns:

The thread usage of the AbstractSnmpContext

Since:

4_12

destroy

public void destroy()

This method will stop the thread. All transmitters, PDUs in flight and traplisteners will be removed when run() finishes.

It closes the socket. The thread will actually stop/finish when the run() finishes. Since the socket is closed, the run() will fall through almost instantly.

Note: The thread(s) will not die immediately; this will take about half a minute.

Specified by:

destroy in interface SnmpContextBasisFace

See Also:

• ListeningContext.destroy()
• ListeningContextPool.destroyPool()

isDestroyed

public boolean isDestroyed()

Description copied from interface: SnmpContextBasisFace

Returns whether or not this context has been destroyed.

Specified by:

isDestroyed in interface SnmpContextBasisFace

stop

public void stop()

Deprecated.

As of version 4_12, should use destroy()

This method will stop the thread. All transmitters, PDUs in flight and traplisteners will be removed when run() finishes.

It does NOT close the socket. The thread will actually stop/finish when the run() finishes. That is when a packet arrives on the socket or when the socket times out.

We have deprecated this method since there is no point in stopping the context, but not destroying it. The context cannot start again anyway. The difference between destroy() and stop() was not very clear.

See Also:

• destroy()

run

public void run()

We wait for any incoming packets. After receiving one, decode the packet into an Pdu. The Pdu will notify the observers waiting for an response.

Thanks to Chris Barlock <barlock@us.ibm.com> who reported a NullPointerException in run() on variable 'me' and introduced the variable stopRequested.

Specified by:

run in interface Runnable

sendPacket

public void sendPacket(byte[] p)

Description copied from interface: SnmpContextBasisFace

Sends an encoded PDU. This is for internal use only and should NOT be called by the developer. This is called by the the PDU itself and is added to the interface to cover the different kind of Contexts.

Specified by:

sendPacket in interface SnmpContextBasisFace

Parameters:

p - The encoded packet

removePdu

public boolean removePdu(int rid)

Description copied from interface: SnmpContextBasisFace

Removes a PDU from the context. This is for internal use only and should NOT be called by the developer. This is called by the the PDU itself and is added to the interface to cover the different kind of Contexts.

Specified by:

removePdu in interface SnmpContextBasisFace

Parameters:

rid - the PDU request id

Returns:

whether the PDU has been successfully removed

addPdu

public boolean addPdu(Pdu p)
               throws IOException,
PduException

Description copied from interface: SnmpContextBasisFace

Adds a PDU to the context. This is for internal use only and should NOT be called by the developer. This is called by the the Pdu itself and is added to the interface to cover the different kind of Contexts.

Specified by:

addPdu in interface SnmpContextBasisFace

Parameters:

p - the PDU

Returns:

whether the PDU has been successfully added

Throws:

IOException

PduException

addTrapListener

public void addTrapListener(TrapListener l)
                     throws IOException

Description copied from interface: SnmpContextBasisFace

Adds the specified trap listener to receive traps on the default trap port 162 from the host that matches this context.

The ListeningContext class will do the actual listening for traps. This context will add itself to a ListeningContextPool object and will only pass the event to its listeners if the pdu matches this context and is a trap pdu.

Specified by:

addTrapListener in interface SnmpContextBasisFace

Parameters:

l - The trap listener

Throws:

IOException

See Also:

• SnmpContextBasisFace.addTrapListener(TrapListener, int)
• ListeningContextFace.DEFAULT_TRAP_PORT

removeTrapListener

public void removeTrapListener(TrapListener l)
                        throws IOException

Description copied from interface: SnmpContextBasisFace

Removes the specified trap listener from listening for packets on the default trap port 162.

The listener will not be removed from all ListeningContext objects that are in the ListeningContextPool. In order to do that, use ListeningContextPool.removeTrapListenerFromPool()

Specified by:

removeTrapListener in interface SnmpContextBasisFace

Parameters:

l - The trap listener

Throws:

IOException

See Also:

• SnmpContextBasisFace.removeTrapListener(TrapListener, int)
• ListeningContextFace.DEFAULT_TRAP_PORT

addTrapListener

public void addTrapListener(TrapListener l,
 int port)
                     throws IOException

Description copied from interface: SnmpContextBasisFace

Adds the specified trap listener to receive traps on the specified port from the host that matches this context.

The ListeningContext class will do the actual listening for traps. This context will add itself to a ListeningContextPool object and will only pass the event to its listeners if the pdu matches this context and is a trap pdu.

Specified by:

addTrapListener in interface SnmpContextBasisFace

Parameters:

l - The trap listener

port - The port the traps are received on

Throws:

IOException

See Also:

• ListeningContextPool(int, String, String)
• ListeningContextPool.addRawPduListener(RawPduListener)

removeTrapListener

public void removeTrapListener(TrapListener l,
 int port)
                        throws IOException

Description copied from interface: SnmpContextBasisFace

Removes the specified trap listener from listening for packets on the specified port.

The listener will not be removed from all ListeningContext objects that are in the ListeningContextPool. In order to do that, use ListeningContextPool.removeTrapListenerFromPool()

Specified by:

removeTrapListener in interface SnmpContextBasisFace

Parameters:

l - The trap listener

port - The port the traps are received on

Throws:

IOException

See Also:

• ListeningContextPool(int, String, String)
• ListeningContextPool.removeRawPduListener(RawPduListener)
• ListeningContextPool.removeRawPduListenerFromPool(RawPduListener)

addTrapListener

public void addTrapListener(TrapListener l,
 ListeningContextPool lcontext)
                     throws IOException

Description copied from interface: SnmpContextBasisFace

Adds the specified trap listener to receive traps on the specified listening context that matches this context.

The ListeningContext class will do the actual listening for traps. This context will add itself to a ListeningContextPool object and will only pass the event to its listeners if the pdu matches this context and is a trap pdu.

Specified by:

addTrapListener in interface SnmpContextBasisFace

Parameters:

l - The trap listener

lcontext - The listening context

Throws:

IOException

See Also:

• ListeningContextPool(int, String, String)
• ListeningContextPool.addRawPduListener(RawPduListener)

removeTrapListener

public void removeTrapListener(TrapListener l,
 ListeningContextPool lcontext)
                        throws IOException

Description copied from interface: SnmpContextBasisFace

Removes the specified trap listener from listening for packets on the specified listening context.

The listener will not be removed from all ListeningContext objects that are in the ListeningContextPool. In order to do that, use ListeningContextPool.removeTrapListenerFromPool()

Specified by:

removeTrapListener in interface SnmpContextBasisFace

Parameters:

l - The trap listener

lcontext - The listening context

Throws:

IOException

See Also:

• ListeningContextPool(int, String, String)
• ListeningContextPool.removeRawPduListener(RawPduListener)
• ListeningContextPool.removeRawPduListenerFromPool(RawPduListener)

addRequestPduListener

public void addRequestPduListener(RequestPduListener l)
                           throws IOException

Description copied from interface: SnmpContextBasisFace

Adds the specified request pdu listener to receive PDUs on the default request pdu port 161 from the host that matches this context.

The ListeningContext class will do the actual listening for PDUs. This context will add itself to a ListeningContextPool object and will only pass the event to its listeners if the pdu matches this context and is a request pdu.

Don't use the TCP_SOCKET when listening for request PDUs. It doesn't provide functionality to send a response back.

Specified by:

addRequestPduListener in interface SnmpContextBasisFace

Parameters:

l - The request PDU listener

Throws:

IOException

See Also:

• SnmpContextBasisFace.addRequestPduListener(RequestPduListener, int)
• SnmpContextBasisFace.DEFAULT_PORT

removeRequestPduListener

public void removeRequestPduListener(RequestPduListener l)
                              throws IOException

Description copied from interface: SnmpContextBasisFace

Removes the specified request pdu listener from listening for packets on the default request pdu port 161.

The listener will not be removed from all ListeningContext objects that are in the ListeningContextPool. In order to do that, use ListeningContextPool.removeRequestPduListenerFromPool()

Specified by:

removeRequestPduListener in interface SnmpContextBasisFace

Parameters:

l - The request PDU listener

Throws:

IOException

See Also:

• SnmpContextBasisFace.removeRequestPduListener(RequestPduListener, int)
• SnmpContextBasisFace.DEFAULT_PORT

addRequestPduListener

public void addRequestPduListener(RequestPduListener l,
 int port)
                           throws IOException

Description copied from interface: SnmpContextBasisFace

Adds the specified request pdu listener to receive PDUs on the specified port from the host that matches this context.

The ListeningContext class will do the actual listening for PDUs. This context will add itself to a ListeningContextPool object and will only pass the event to its listeners if the pdu matches this context and is a request pdu.

Don't use the TCP_SOCKET when listening for request PDUs. It doesn't provide functionality to send a response back.

Specified by:

addRequestPduListener in interface SnmpContextBasisFace

Parameters:

l - The request PDU listener

port - The port the request PDUs are received on

Throws:

IOException

See Also:

• ListeningContextPool(int, String, String)
• ListeningContextPool.addRawPduListener(RawPduListener)

removeRequestPduListener

public void removeRequestPduListener(RequestPduListener l,
 int port)
                              throws IOException

Description copied from interface: SnmpContextBasisFace

Removes the specified request pdu listener from listening for packets on the specified port.

The listener will not be removed from all ListeningContext objects that are in the ListeningContextPool. In order to do that, use ListeningContextPool.removeRequestPduListenerFromPool()

Specified by:

removeRequestPduListener in interface SnmpContextBasisFace

Parameters:

l - The request PDU listener

port - The port the request PDUs are received on

Throws:

IOException

See Also:

• ListeningContextPool(int, String, String)
• ListeningContextPool.removeRawPduListener(RawPduListener)
• ListeningContextPool.removeRawPduListenerFromPool(RawPduListener)

addRequestPduListener

public void addRequestPduListener(RequestPduListener l,
 ListeningContextPool lcontext)
                           throws IOException

Description copied from interface: SnmpContextBasisFace

Adds the specified request pdu listener to receive PDUs on the specified listening context that matches this context.

The ListeningContext class will do the actual listening for PDUs. This context will add itself to a ListeningContextPool object and will only pass the event to its listeners if the pdu matches this context and is a request pdu.

Don't use the TCP_SOCKET when listening for request PDUs. It doesn't provide functionality to send a response back.

Specified by:

addRequestPduListener in interface SnmpContextBasisFace

Parameters:

l - The request PDU listener

lcontext - The listening context

Throws:

IOException

See Also:

• ListeningContextPool(int, String, String)
• ListeningContextPool.addRawPduListener(RawPduListener)

removeRequestPduListener

public void removeRequestPduListener(RequestPduListener l,
 ListeningContextPool lcontext)
                              throws IOException

Description copied from interface: SnmpContextBasisFace

Removes the specified request pdu listener from listening for packets on the specified listening context.

The listener will not be removed from all ListeningContext objects that are in the ListeningContextPool. In order to do that, use ListeningContextPool.removeRequestPduListenerFromPool()

Specified by:

removeRequestPduListener in interface SnmpContextBasisFace

Parameters:

l - The request PDU listener

lcontext - The listening context

Throws:

IOException

See Also:

• ListeningContextPool(int, String, String)
• ListeningContextPool.removeRawPduListener(RawPduListener)
• ListeningContextPool.removeRawPduListenerFromPool(RawPduListener)

rawPduReceived

public void rawPduReceived(RawPduEvent evt)

Invoked when an undecoded pdu is received. First the version and the hostaddress are checked, if correct an attempt is made to decode the pdu. When successful the original event is consumed and a decoded pdu event is passed on the listeners.

Specified by:

rawPduReceived in interface RawPduListener

See Also:

• RawPduReceivedSupport.fireRawPduReceived(int, java.lang.String, int, byte[])
• RequestPduReceivedSupport.fireRequestPduReceived(uk.co.westhawk.snmp.stack.Pdu, int)
• TrapReceivedSupport.fireTrapReceived(uk.co.westhawk.snmp.stack.Pdu, int)

clone

public abstract Object clone()
                      throws CloneNotSupportedException

Returns a clone of this SnmpContext.

Specified by:

clone in interface SnmpContextBasisFace

Throws:

CloneNotSupportedException - Thrown when the constructor generates an IOException or when in one of the Pool classes.

Since:

4_14

getHashKey

public abstract String getHashKey()

Returns the hash key. This key is built out of all properties.

Specified by:

getHashKey in interface SnmpContextBasisFace

Returns:

The hash key

Since:

4_14