At 01:36 PM 11/21/99 +0100, Ranieri Argentini
<[EMAIL PROTECTED]> wrote:
>If anyone knows where to find an example of an OO tcp/ip stack, please tell
>me. I could really use some more info in analysing this..
Building a prototype in Java code might explain how the IP stack does what
it does. The "source" of the packets can be a OS file. Or, a program can
create packets pseudo-randomly. A TCP/IP stack is a sparsely populated
array of IP packet queues and a kind of IP packet listener.
While it manages 65,536 ports, all of these ports are rarely used at once.
In addition, the low-level network driver is not complex. It is a packet
source; it passes the raw packet from native code to an entry point in
bytecode. The bytecode constructs a incoming packet queue, so that no
packets are lost.
The first class is a model of a network packet.
public interface Packet {
:
int getSourceHost();
int getSourcePort();
int getTargetHost();
int getTargetPort();
:
byte[] getData();
}
public class BasicPacket
implements Packet {
public BasicPacket( byte[] v ) {
}
:
private byte[] raw_data;
}
public interface PacketListener {
public void onPacket( Packet v );
}
A TCP/IP stack is used by a network card driver. All incoming packets are
stuffed into a Packet object and passed to the TCP/IP stack.
public void incoming_packet( byte[] v ) {
listener.onPacket( new Packet( v ) );
}
>From the other perspective of a sparsely populated array of PacketQueues, a
PacketQueue is also a PacketListener. A packet queue is available
(virtually) at every IP port (from 0 to 65,565).
I believe the TCP/IP project is important for the future of the JOS project
because it enables critical inter-process communication (IPC) and
inter-machine communication. With a TCP/IP stack, a single-step mechanism
and non-console trace can be introduced into a JOS JVM for additional
debugging.
While the driver software constantly reads all incoming packets, throws
away packets that are not targeted for this TCP/IP stack, throws away
packets that have no corresponding packet queue associated with a port.
When a ServerSocket "opens" a port, a PacketQueue is opened for that port.
Only that ServerSocket can read the packets in its PacketQueue. Each
connection, of course, creates an incoming packet queue for the
stack-assigned port. Only that Socket can read the packets in its PacketQueue.
Almost all of this OO design can be written and refined in Java. Incoming
packets can be single- or double-queued. Outgoing packets should be
single-queued, one outgoing queue for the stack instead of one outgoing
queue for each port.
The only non-Java part is between the NIC and native code that calls
incoming_packet( byte[] v ).
Interface
Packet
Stack
PacketQueue
PacketSource
Socket
ServerSocket
Class
BasicPacket
BasicStack
BasicPacketQueue
BasicSocket
BasicServerSocket
FilePacketSource
RandomPacketSource
I look forward to using it.
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