OpenDHT

A lightweight C++11 Distributed Hash Table implementation originally based on https://github.com/jech/dht by Juliusz Chroboczek.

• Light and fast C++11 Kademlia DHT library.
• Distributed shared key->value data-store
• Clean and powerfull distributed map API with storage of arbitrary binary values of up to 56 KB.
• Optional public key cryptography layer providing data signature and encryption (using GnuTLS).
• IPv4 and IPv6 support.
• Python binding.

Documentation

See the wiki: https://github.com/savoirfairelinux/opendht/wiki

How-to build and install

Build instructions : https://github.com/savoirfairelinux/opendht/wiki/Build-the-library

How-to build a simple client app

g++ main.cpp -std=c++11 -lopendht -lgnutls

Examples

C++ example

The tools directory includes simple example programs :

• dhtnode, a command line tool, mostly used for debuging, allowing to perform operations supported by the library (get, put etc.) with text values.
• dhtchat, a very simple IM client working over the dht.

Example program launching a DHT node, connecting to the network and performing some basic operations:

#include <opendht.h>
#include <vector>

int main()
{
    dht::DhtRunner node;

    // Launch a dht node on a new thread, using a
    // generated RSA key pair, and listen on port 4222.
    node.run(4222, dht::crypto::generateIdentity(), true);

    // Join the network through any running node,
    // here using a known bootstrap node.
    node.bootstrap("bootstrap.ring.cx", "4222");

    // put some data on the dht
    std::vector<uint8_t> some_data(5, 10);
    node.put("unique_key", some_data);

    // put some data on the dht, signed with our generated private key
    node.putSigned("unique_key_42", some_data);

    // get data from the dht
    node.get("other_unique_key", [](const std::vector<std::shared_ptr<dht::Value>>& values) {
        // Callback called when values are found
        for (const auto& value : values)
            std::cout << "Found value: " << *value << std::endl;
        return true; // return false to stop the search
    });

    // wait for dht threads to end
    node.join();
    return 0;
}

Python 3 example

import opendht as dht

r = dht.DhtRunner()
r.run()

# Join the network through any running node,
# here using a known bootstrap node.
r.bootstrap("bootstrap.ring.cx", "4222")

r.put(dht.InfoHash.get("unique_key"), dht.Value(b'some binary data'))

# blocking call (provide callback arguments to make the call non-blocking)
results = r.get(dht.InfoHash.get("unique_key"))
for r in results:
    print(r)

Licence

Copyright (C) 2014-2016 Savoir-faire Linux Inc.

Licenced under the GNU General Public License version 3, though the core routing library (dht.cpp) is licenced under the MIT licence.

This project is independent from another project called OpenDHT (Sean Rhea. Ph.D. Thesis, 2005), now extinct.

Dependencies

• msgpack-c 1.2+, used for data serialization.
• GnuTLS 3.1+, used for cryptographic operations.
• Nettle 2.4+, a GnuTLS dependency for crypto.
• Build tested with GCC 4.8+ (GNU/Linux, Android, Windows with MinGW), Clang/LLVM (Linux, OS X).