This is an I2P port of snark [http://klomp.org/snark], a GPL'ed bittorrent client

The build in tracker has been removed for simplicity.

Example usage:
  java -jar lib/i2psnark.jar myFile.torrent

or, a more verbose setting:
  java -jar lib/i2psnark.jar --eepproxy 127.0.0.1 4444 \
       --i2cp 127.0.0.1 7654 "inbound.length=2 outbound.length=2" \
       --debug 6 myFile.torrent

apps/i2psnark/java/src/org/klomp/snark/PeerID.java

@@ -0,0 +1,208 @@
+/* PeerID - All public information concerning a peer.
+   Copyright (C) 2003 Mark J. Wielaard
+
+   This file is part of Snark.
+   
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+ 
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+ 
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+*/
+
+package org.klomp.snark;
+
+import java.io.IOException;
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.util.Map;
+
+import org.klomp.snark.bencode.*;
+
+import net.i2p.data.Base64;
+import net.i2p.data.Destination;
+import net.i2p.data.DataFormatException;
+
+public class PeerID implements Comparable
+{
+  private final byte[] id;
+  private final Destination address;
+  private final int port;
+
+  private final int hash;
+
+  public PeerID(byte[] id, Destination address)
+  {
+    this.id = id;
+    this.address = address;
+    this.port = 6881;
+
+    hash = calculateHash();
+  }
+
+  /**
+   * Creates a PeerID from a BDecoder.
+   */
+  public PeerID(BDecoder be)
+    throws IOException
+  {
+    this(be.bdecodeMap().getMap());
+  }
+
+  /**
+   * Creates a PeerID from a Map containing BEncoded peer id, ip and
+   * port.
+   */
+  public PeerID(Map m)
+    throws InvalidBEncodingException, UnknownHostException
+  {
+    BEValue bevalue = (BEValue)m.get("peer id");
+    if (bevalue == null)
+      throw new InvalidBEncodingException("peer id missing");
+    id = bevalue.getBytes();
+
+    bevalue = (BEValue)m.get("ip");
+    if (bevalue == null)
+      throw new InvalidBEncodingException("ip missing");
+    address = I2PSnarkUtil.instance().getDestination(bevalue.getString());
+    if (address == null)
+        throw new InvalidBEncodingException("Invalid destination [" + bevalue.getString() + "]");
+
+    port = 6881;
+
+    hash = calculateHash();
+  }
+
+  public byte[] getID()
+  {
+    return id;
+  }
+
+  public Destination getAddress()
+  {
+    return address;
+  }
+
+  public int getPort()
+  {
+    return port;
+  }
+
+  private int calculateHash()
+  {
+    int b = 0;
+    for (int i = 0; i < id.length; i++)
+      b ^= id[i];
+    return (b ^ address.hashCode()) ^ port;
+  }
+
+  /**
+   * The hash code of a PeerID is the exclusive or of all id bytes.
+   */
+  public int hashCode()
+  {
+    return hash;
+  }
+
+  /**
+   * Returns true if and only if this peerID and the given peerID have
+   * the same 20 bytes as ID.
+   */
+  public boolean sameID(PeerID pid)
+  {
+    boolean equal = true;
+    for (int i = 0; equal && i < id.length; i++)
+      equal = id[i] == pid.id[i];
+    return equal;
+  }
+
+  /**
+   * Two PeerIDs are equal when they have the same id, address and port.
+   */
+  public boolean equals(Object o)
+  {
+    if (o instanceof PeerID)
+      {
+        PeerID pid = (PeerID)o;
+
+        return port == pid.port
+          && address.equals(pid.address)
+          && sameID(pid);
+      }
+    else
+      return false;
+  }
+
+  /**
+   * Compares port, address and id.
+   */
+  public int compareTo(Object o)
+  {
+    PeerID pid = (PeerID)o;
+
+    int result = port - pid.port;
+    if (result != 0)
+      return result;
+
+    result = address.hashCode() - pid.address.hashCode();
+    if (result != 0)
+      return result;
+
+    for (int i = 0; i < id.length; i++)
+      {
+        result = id[i] - pid.id[i];
+        if (result != 0)
+          return result;
+      }
+
+    return 0;
+  }
+
+  /**
+   * Returns the String "id@address" where id is the base64 encoded id.
+   */
+  public String toString()
+  {
+    int nonZero = 0;
+    for (int i = 0; i < id.length; i++) {
+        if (id[i] != 0) {
+            nonZero = i;
+            break;
+        }
+    }
+    return Base64.encode(id, nonZero, id.length-nonZero).substring(0,4) + "@" + address.calculateHash().toBase64().substring(0,6);
+  }
+
+  /**
+   * Encode an id as a hex encoded string and remove leading zeros.
+   */
+  public static String idencode(byte[] bs)
+  {
+    boolean leading_zeros = true;
+
+    StringBuffer sb = new StringBuffer(bs.length*2);
+    for (int i = 0; i < bs.length; i++)
+      {
+        int c = bs[i] & 0xFF;
+        if (leading_zeros && c == 0)
+          continue;
+        else
+          leading_zeros = false;
+
+        if (c < 16)
+          sb.append('0');
+        sb.append(Integer.toHexString(c));
+      }
+
+    return sb.toString();
+  }
+
+}