package javaforce;

import java.io.*;

import java.net.*;

public class DatagramInputStream extends InputStream {

private static final int MAX = 1460;

private DatagramSocket ds;

private byte buffer[];

private int buffersize = 0, bufferpos = 0;

private boolean fillBuffer() {

while (buffersize == 0) {

byte data[] = new byte[MAX];

DatagramPacket pack = new DatagramPacket(data, MAX);

try {

ds.receive(pack);

} catch (Exception e) {

return false;

}

buffer = pack.getData();

buffersize = pack.getLength();

bufferpos = 0;

}

return true;

}

public DatagramInputStream(DatagramSocket ds) {

this.ds = ds;

}

public boolean markSupported() {

return false;

}

public int read() {

if (!fillBuffer()) {

return -1;

}

int ret = ((int) buffer[bufferpos++]) & 0xff;

buffersize--;

return ret;

}

public int read(byte buf[]) {

return read(buf, 0, buf.length);

}

public int read(byte buf[], int pos, int len) {

int ret;

if (!fillBuffer()) {

return -1;

}

if (len > buffersize) {

ret = buffersize;

System.arraycopy(buffer, bufferpos, buf, pos, buffersize);

buffersize = 0;

bufferpos = 0;

} else {

ret = len;

System.arraycopy(buffer, bufferpos, buf, pos, len);

buffersize -= len;

bufferpos += len;

}

return ret;

}

}