chayapan / dhtplay

A python client for browsing the bittorrent DHT.

DHTPlay

DHTPlay is an application for walking/exploring the Bittorrent DHT. Simply clone and run ./dhtplay to try it out.

Note this program only lets you browse the bittorrent DHT, which only contains info hashes of torrents. There is no way to browse the bittorrent DHT in such a way that you can actually retrieve the information about the torrents, unless you also implement the actual bittorrent protocol including the extension for transmitting torrents in-band. Right now you can get a magnet link only.

Running

To run DHTPlay, you will need the python gtk2 (pygtk) library and the python gupnp idg library. In debian/ubuntu, these are available as python-gtk2 and python-gupnp-igd, respectively.

The "new server" button creates a new DHT Server. If you install python-gupnp-igd (this is the name of the package in debian/ubuntu at least) the UPnP check box will be available and this will be a lot easier for you.

Alternatively, if you want to forward the port manually, I believe the correct settings are:

Bind Address: 0.0.0.0
Bind Port: 12345
Hash: <whatever>
External Addr: <your external IP>
External Port: 12345

Essentially, the external address+port are used to tell other DHT nodes what your address is. The bind address+bind port are used locally to create the listening port on your own computer. When you're behind a NAT (like you are) the external address and the bind address have to be different. "0.0.0.0" essentially says - listen on all interfaces.

After you make a server, you need to connect to the dht network by adding peers. From there, you can look around.

Notes on design

As of the time of writing this, DHTPlay uses three threads of control at any given time. The first is the main thread of control that is started by the python interpreter which enters a gtk main loop after doing a bit of initialization. The second is a thread that is bootstrapped by the main thread that I call the 'server wrangler'. This thread polls the server sockets and notifies the server threads when they have received new packets. It also spawns the new server threads that are created for each DHT server. There is also a thread that is used for dispatching queries to the SQLite Database. Some of the methods of this thread are for syncronous access and some are for async access. This thread is used because sqlite connections cannot be shared across threads and because I wasn't interested in making an implimentation that used locks. In order for the server threads/server wrangler thread to communicate with the gui thread the glib.idle_add function is used. When the GUI thread needs to communicate with the server thread a special udp message is sent to the server.

To recap - Threads:

• 1 Main Thread (GTK/GDK ui thread (can be locked using gtk.gdk.lock))
• 1 Server Wrangler thread (polls file descriptors to check for packets)
• 1 SQLite Thread (holds sqlite cursor and connection, has query functions)
• x DHT Server threads (one for each server)

Documents that this program aims to impliment:

• BEP_0005 (DHT Protocol): http://www.bittorrent.org/beps/bep_0005.html
• BEP_0033 (DHT Scrapes): http://www.bittorrent.org/beps/bep_0033.html
• "Minor Extensions to the Bitorrent DHT": http://www.pps.jussieu.fr/~jch/software/bittorrent/bep-dht-minor-extensions.html
• The undocumented 'v' version extension that uTorrent and rTorrent impliment in addition to other clients. Note: there is a bit about the version key here - http://www.rasterbar.com/products/libtorrent/dht_extensions.html

Contact

For bug reports, patches, questions, etc. feel free to send me an email at [email protected].

Copyright notes

The file util/bencode.py is not under the same license as the other files. It was previously released in 2011 as FreeBencode and is licensed under the MIT/Expat license.

The Magnet Icon is sourced from http://commons.wikimedia.org/wiki/File:Magnet-icon.gif. It is listed as No Rights Reserved.

All other files are licensed under the GPLv3+. See COPYING for license details.