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Using mldht as a library

Initialization of a DHT Node

  1. create one lbms.plugins.mldht.kad.DHT instance per IP address family
  2. addStatusListener to get notified when initialization is complete
  3. (optional) provide custom Executors, logging, tie IPv4 and IPv6 instances together as siblings. See the8472.mldht.Launcher as an advanced example for initialization.
  4. start() them
  5. use dht.getServerManager().awaitActiveServer() to wait for a socket to become ready for use

Performing basic tasks

While mldht implements low level concepts such as individual DHT messages and query-response exchanges on top of them, most common tasks will require dozens of such message exchanges. The necessary logic is encapsulated in Task subclasses. The most common actions are the PeerLookupTask and AnnounceTask which fetch peer lists for torrents and announce your torrent listening port.

You can find examples how most Tasks, including BEP44 get and put, are used in the the8472.mldht.cli.commands package.

The utility methods DHT.createPeerLookup(byte[]) and DHT.announce(PeerLookupTask, boolean, int) can be used to avoid some boilerplate for simple uses.

Bootstrapping

Depending on the configuration passed during startup the DHT will try to read previously stored contacts from disk or contact well-known bootstrap nodes. If neither mechanism works you can manually bootstrap by adding nodes via lbms.plugins.mldht.kad.DHT.addDHTNode(String, int).

Debugging

The the8472.mldht.Diagnostics class can be used to write out most of the DHT state to a log directory in a human-readable format. DHT.setLogger(DHTLogger) and DHT.setLogLevel(LogLevel) can log most events, down to individual messages.

Multihoming, IPv4, IPv6

Tasks are always bound to a single socket. If you want to announce multiple interfaces or multiple address families you will have to run the tasks in question on each available RPCServer instance.

Hooking into stream of incoming messages

After creating DHT instances, register a callback via addIncomingMessageListener(DHT.IncomingMessageListener l). It will be called for most incoming messages. Some but not all bogus/invalid ones will be prefiltered.

The callback is called from the message processing threads, so it should be non-blocking and thread-safe.

Message objects and their contents should not be modified.