Kademlua is a Kademlia style distributed hash table written in Lua
with some support code written in C.
The code works as in "provides a DHT to store and retrieve values" but
it is very untidy. It's actually my first big project in Lua and I
guess it shows a little. The code is not really organized into
modules...
Overview:
=========
Kademlua defines its own RPC format which uses BEncoding (like
BitTorrent) and closely resembles the one used by the Entangled DHT.
Kademlua is easily integrated into other applications. Kademlua
completely runs in coroutines and is, therefore, re-entrant. Kademlua
code is mostly written in Lua, with the notable exception of the "ec"
library provided by the kademlua.c file. With the exception of the
getevent() function everything in the "ec" library could also be done
in Lua. getevent() handles reading from and to the network via a UDP
socket.
I believe Kademlua to be quite fast and acceptably economical* with
memory, it needs few hundred kilobytes when it has made contacts with
around 100 nodes, even though there still are a number of pretty low
hanging fruit, like the queue of the coroutine scheduler or the whole
LivelinessManager thing.
* In contrast with today's RAM sizes in personal computers.
If you have questions, don't hesitate to contact me.
Dependencies:
=============
* Lua 5.1
* openssl's libcrypto (only for SHA-1 implementation, could be
implemented directly)
Usage:
======
0. Edit the Makefile to suit your Lua/OpenSSL installation.
1. Compile the C code:
$ make
2. Start control node:
$ ./kademlua 8001
2.5. create a log directory for step 3:
$ mkdir log
3. In another shell: Start a network of 100 Kademlua nodes:
$ ./start.sh
Step 3 may open too much files for the taste of your OS. In this case
either raise the maximum number of open files or decrease the amount
of started nodes in start.sh
The control node created in step 2 provides command shell which
accepts Lua programs, e.g.:
add(sha1("key"), "value")
findvalue(sha1("key"))
The command prompt looks like
20~40 | 496 >
which means that our node has 20 other nodes in its routing table,
which leads to an estimated 40 nodes in the whole network. Our node
consumes 496 kbyte of Lua memory.
Platforms:
==========
Kademlua has been successfully run on Mac OS X 10.5.x/i386, Linux/amd64 and Linux/mipsel (on an OpenWRT router :D).
License:
========
As of 2010/1/3 essentially all code, with the exception of some parts
of the bdecoder, are written by me, Michael Meier, but I am still
unsure about which license to choose. The three main candidates are
the MIT License, the LGPL license or the GPL license. Right now I'm
tending towards the MIT license.