On Panther, you could send UDP packets > 16356 bytes from Java, and
receive them without issue.
On Tiger, any UDP packets > 16356 bytes are dropped. You just never
receive them.
I've included two classes Send.java and Receive.java, to demonstrate
this.
Basically, you open two terminals. In one, you do:
java -cp . Receive
In the other:
java -cp . Send <SIZE>
eg. java -cp . Send 16356
On Panther you can send packets up to around 64k as expected. On
Tiger anything above 16356 (just under 16k) is dropped.
Does that makes sense to anyone?
We thought it was a sysctl issue, as sysctl -a shows:
net.inet.udp.maxdgram: 9216
But that is the same on Panther, and changing it via sysctl makes no
difference.
Any help appreciated.
Thanks.
Jamie
------ Receive.java ------
import java.net.*;
import java.io.*;
public class Receive
{
public static void main(String args[])
{
String host = "localhost";
int port = 9999;
InetAddress addr = null;
try {
addr = InetAddress.getByName(host);
} catch (UnknownHostException uhe) { }
try {
DatagramSocket ds = new DatagramSocket(port);
DatagramPacket rec = new DatagramPacket(new byte[65530],
65530);
rec.setLength(65530);
ds.receive(rec);
String line = new String(rec.getData(), 0, rec.getLength());
System.out.println(line);
System.out.println("Received " + rec.getLength() + " bytes");
} catch (IOException ie) { }
}
}
------ Send.java ------
import java.net.*;
import java.io.*;
public class Send
{
public static void main(String args[])
{
String host = "localhost";
int port = 9999;
int max = 1;
if (args.length > 0) {
try {
max = Integer.parseInt(args[0]);
} catch (NumberFormatException nfe) { }
}
try {
DatagramSocket ds = new DatagramSocket();
byte[] buf = new byte[max];
for (int i = 0; i < buf.length; i++) {
buf[i] = '.';
}
ds.send(new DatagramPacket(buf, buf.length, addr, port));
} catch (IOException ie) { }
}
}
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