DHT Protocol

General notes:

1. Libtorrent’s DHT security extension is enforced, requiring the Node ID to be restricted by the external IP.
2. Default’s libtorrent’s parameters are used: search_branching (alpha) = 5, bucket_size (k) = 8 and agressive_lookup = true.
3. Stored resources meant for persistence in DHT network (like profile, avatar etc) are refreshed every hour. Previous studies have shown (Paper: Profiling a million user dht) that, under some assumptions and configurations, long-term data persistence may be achieved by refreshing every couple of hours.
4. Persisted resources are also saved to disk and restored when twister daemon restarts.

• DHT command: ping

  ping query = {“t”:”aa”, “z”:”q”, “q”:”ping”, “x”:{“id”:”abcdefghij0123456789″}}

  Response = {“t”:”aa”, “z”:”r”, “r”: {“id”:”mnopqrstuvwxyz123456″}}

• DHT command: findNode

  findNode Query = {“t”:”aa”, “z”:”q”, “q”:”findNode”, “x”: {“id”:”abcdefghij0123456789″, “target”:”mnopqrstuvwxyz123456″}}

  Response = {“t”:”aa”, “z”:”r”, “r”: {“id”:”0123456789abcdefghij”, “nodes”: “def456…”}}

• DHT command: announcePeer

  Note: this command may be removed in future.

  announcePeer Query = {“t”:”aa”, “z”:”q”, “q”:”announce_peer”, “x”: {“id”:”abcdefghij0123456789″, “implied_port”: 1, “info_hash”:”mnopqrstuvwxyz123456″, “port”: 6881, “token”: “aoeusnth”}}

  Response = {“t”:”aa”, “z”:”r”, “r”: {“id”:”mnopqrstuvwxyz123456″}}

• DHT command: getPeers

  Unlike BitTorrent DHT, getPeers command doesn’t exist. Use command getData with “target”={“username”,”tracker”,”m”} instead.

• DHT command: putData

  putData Query = {“t”:”aa”, “z”:”q”, “q”:”putData”, “x”: {
      “id”:”abcdefghij0123456789″, “sig_p”:”34fdd3wdw”, “sig_user”:”nobody”, “token”: “aoeusnth”, “p”: {
          “v” : “arbitrary-value”, “seq” : “10″, “time” : “13131321321″, height : “1000″, “target”: {
              “n”:”name”, “r”:”resource”, “t”:”m” }}}}

  Response = {“t”:”aa”, “z”:”r”, “r”: {“id”:”mnopqrstuvwxyz123456″}}

  Note: target_id is the hash of bencoded “target” field.

• DHT command: getData

  getData Query = {“t”:”aa”, “z”:”q”, “q”:”getData”, “x”: {
      “id”:”abcdefghij0123456789″, “justtoken”:”0″, “target”: {
          “n”:”name”, “r”:”resource”, “t”:”m” }}}}

  Response = {“t”:”aa”, “z”:”r”, “r”: {“id”:”mnopqrstuvwxyz123456″, “token”: “aoeusnth”, “data”: [
     {"p":"data1", "sig_p":"34fdd3wdw", "sig_user":"nobody",
     {"p":"data2", "sig_p":"fg40958ejfdg", "sig_user":"twister" ] }}

  Note: target_id is the hash of bencoded “target” field.