Package net.i2p.client.streaming.impl

Class PcapWriter

java.lang.Object

net.i2p.client.streaming.impl.PcapWriter

All Implemented Interfaces:

Closeable, Flushable, AutoCloseable

public class PcapWriter
extends Object
implements Closeable, Flushable

Write a standard pcap file with a "TCP" packet that can be analyzed with standard tools such as wireshark. The source and dest "IP" and "port" are fake but are generated from the hashes of the Destinations and stream ID's, so they will be consistent. The local "IP" will always be of the form 127.0.x.y Initial IP for a conn will be 127.0.0.0 for the local and 0.0.0.0 for the remote. Reference: http://wiki.wireshark.org/Development/LibpcapFileFormat The Jpcap library http://netresearch.ics.uci.edu/kfujii/jpcap/doc/ was close to what I want, but it requires you to instantiate a "captor" before you can write a file, and it requires a native lib to do so, and even then, it only wants to read the file, not write it. We even calculate a correct TCP header checksum to keep the tools happy. We don't, however, convert I2P-style sequence numbers, which count packets, to TCP-style byte counts. We don't track a lowest-acked-thru byte count atm, really. We do represent the window size in bytes though, so that's real confusing. This is designed to debug the streaming lib, but there are not log calls for every single packet - pings and pongs, and various odd cases where received packets are dropped, are not logged. Yes we could dump it natively and write a wireshark dissector. That sounds hard. And we wouldn't get the TCP stream analysis built into the tools.

Since:

0.9.4

Constructor Summary

Constructors

Constructor	Description
PcapWriter(I2PAppContext ctx, String file)

Method Summary

Modifier and Type	Method	Description
void	close()
void	flush()
void	write(PacketLocal pkt)	For outbound packets
void	write(Packet pkt, Connection con)	For inbound packets

Methods inherited from class java.lang.Object

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

Constructor Detail

PcapWriter

public PcapWriter(I2PAppContext ctx,
                  String file)
           throws IOException

Throws:

IOException

Method Detail

close

public void close()

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

flush

public void flush()

Specified by:

flush in interface Flushable

write

public void write(PacketLocal pkt)
           throws IOException

For outbound packets

Throws:

IOException

write

public void write(Packet pkt,
                  Connection con)
           throws IOException

For inbound packets

Parameters:

con - may be null

Throws:

IOException