org.dhcp4java

Class DHCPServlet

java.lang.Object

org.dhcp4java.DHCPServlet

Direct Known Subclasses:

DHCPSnifferServlet

public class DHCPServlet
extends Object

General Interface for a "DHCP Servlet"

Normal use is to override the doXXX() or service() method to provide your own application logic.

For simple servers or test purpose, it as also a good idea to provide a main() method so you can easily launch the server by running the servlet.

Version:

1.00

Author:

Stephan Hadinger

Field Summary

Fields

Modifier and Type	Field and Description
protected DHCPCoreServer	m_aServer the server instance running this servlet

Constructor Summary

Constructors

Constructor and Description
DHCPServlet()

Method Summary

Modifier and Type	Method and Description
protected DHCPPacket	doDecline(DHCPPacket request) Process DECLINE request.
protected DHCPPacket	doDiscover(DHCPPacket request) Process DISCOVER request.
protected DHCPPacket	doInform(DHCPPacket request) Process INFORM request.
protected DHCPPacket	doRelease(DHCPPacket request) Process RELEASE request.
protected DHCPPacket	doRequest(DHCPPacket request) Process REQUEST request.
DHCPCoreServer	getServer()
void	init(Properties props) Initialize servlet.
protected void	postProcess(DatagramPacket requestDatagram, DatagramPacket responseDatagram) You have a chance to catch response before it is sent back to client.
protected DHCPPacket	service(DHCPPacket request) General method for parsing a DHCP request.
DatagramPacket	serviceDatagram(DatagramPacket requestDatagram) Low-level method for receiving a UDP Daragram and sending one back.
void	setServer(DHCPCoreServer server)

Methods inherited from class java.lang.Object

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

Field Detail

m_aServer

protected DHCPCoreServer m_aServer

the server instance running this servlet

Constructor Detail

DHCPServlet

public DHCPServlet()

Method Detail

init

public void init(Properties props)

Initialize servlet. Override this method to implement any initialization you may need.

This method is called once at stratup, before any request is passed to the servlet. A properties is passed to the servlet to read whatever parameters it needs.

There is no default behaviour.

Parameters:

props - a Properties containing parameters, as passed to DHCPCoreServer

serviceDatagram

public DatagramPacket serviceDatagram(DatagramPacket requestDatagram)

Low-level method for receiving a UDP Daragram and sending one back.

This methode normally does not need to be overriden and passes control to service() for DHCP packets handling. Howerever the service() method is not called if the DHCP request is invalid (i.e. could not be parsed). So overriding this method gives you control on every datagram received, not only valid DHCP packets.

Parameters:

requestDatagram - the datagram received from the client

Returns:

response the datagram to send back, or null if no answer

service

protected DHCPPacket service(DHCPPacket request)

General method for parsing a DHCP request.

Returns the DHCPPacket to send back to the client, or null if we silently ignore the request.

Default behaviour: ignore BOOTP packets, and dispatch to doXXX() methods.

Parameters:

request - DHCP request from the client

Returns:

response DHCP response to send back to client, null if no response

doDiscover

protected DHCPPacket doDiscover(DHCPPacket request)

Process DISCOVER request.

Parameters:

request - DHCP request received from client

Returns:

DHCP response to send back, or null if no response.

doRequest

protected DHCPPacket doRequest(DHCPPacket request)

Process REQUEST request.

Parameters:

request - DHCP request received from client

Returns:

DHCP response to send back, or null if no response.

doInform

protected DHCPPacket doInform(DHCPPacket request)

Process INFORM request.

Parameters:

request - DHCP request received from client

Returns:

DHCP response to send back, or null if no response.

doDecline

protected DHCPPacket doDecline(DHCPPacket request)

Process DECLINE request.

Parameters:

request - DHCP request received from client

Returns:

DHCP response to send back, or null if no response.

doRelease

protected DHCPPacket doRelease(DHCPPacket request)

Process RELEASE request.

Parameters:

request - DHCP request received from client

Returns:

DHCP response to send back, or null if no response.

postProcess

protected void postProcess(DatagramPacket requestDatagram,
                           DatagramPacket responseDatagram)

You have a chance to catch response before it is sent back to client.

This allows for example for last minute modification (who knows?) or for specific logging.

Default behaviour is to do nothing.

The only way to block the response from being sent is to raise an exception.

Parameters:

requestDatagram - datagram received from client

responseDatagram - datagram sent back to client

getServer

public DHCPCoreServer getServer()

Returns:

Returns the server.

setServer

public void setServer(DHCPCoreServer server)

Parameters:

server - The server to set.