This repository contains a partially implemented node for a DHT based on Kademlia. It uses LMDB for file storage and OpenSSL for generating safe random numbers. The code should compile on any POSIX compatible system on which the mentioned dependencies are available.

The purpose of this application was originally to serve as foundation for various kinds of peer-to-peer network experiments. Its future is, however, currently not certain.

Building requires CMAKE 3.8 or later, git, the OpenSSL development headers, and the LMDB development headers. If on Ubuntu, the following commands should install all required dependencies:

$ sudo apt install cmake git libssl-dev liblmdb-dev

On a POSIX system, the following commands should be enough to download and build the project, assuming all dependencies are installed.

$ git clone https://github.com/emanuelpalm/kdt.git
$ cd kdt
$ mkdir build
$ cd build
$ cmake ../
$ make

Two binaries are produced: namely, kdt-test and kdt. The former runs a unit test suite, while the latter starts the application. No command line arguments are read, so any configuration data has to be provided via environment variables. The two most significant such are KDT_INTERFACE and KDT_PEER. The former selects which local network interface to use, what port, as well as what internet and transport protocols to use. The latter variable determines what node, if any, to use for joining the network after the application has started.

The following example, also assuming a POSIX environment, could be suitable for joining a local KDT network:

KDT_INTERFACE="IPv4/TCP 0.0.0.0:39882" KDT_PEER="IPv4/TCP 192.168.0.4" ./kdt

The only communication method currently implemented uses TCP for reliable datagram transmission. Both IPv4 and IPv6 are supported, but not at once. To improve performance, all message buffers are pre-allocated. Custom allocators are provided for allocating memory for outgoing and ingoing messages, respectively.

The cmake/ folder contains CMAKE modules.

The src/main/ folder contains the application code. Significantly, it contains the following entries:

Each folder and .c/.h file pair in the src/main/kdt folder is considered as being a module. Folders contain a .h file with the same name as the folder serving as entry-point for the module. If a module folder contains a folder named internal/, the contents of that folder must only be accessed directly from within the module.

The src/test/ folder contains a unit test library called unit as well as unit tests for some of the main folder modules.

Contributions may be considered from any source.

If you are interested in finishing the implementation, a good start could be to search for TODO statements. The following command should list them, if executed from the project root folder via a POSIX terminal:

grep -irn --include="*.c" TODO .