====== DHT protocol APIs ======

===== General notes =====

  - [[http://www.libtorrent.org/dht_sec.html|Libtorrent’s DHT security extension]] is enforced, requiring the Node ID to be restricted by the external IP.
  - Default’s libtorrent’s parameters are used: search_branching (alpha) = 5, bucket_size (k) = 8 and agressive_lookup = true.
  - Stored resources meant for persistence in DHT network (like profile, avatar etc) are refreshed every hour. Previous studies have shown ([[http://dl.acm.org/citation.cfm?id=1298325|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.
  -  Persisted resources are also saved to disk and restored when twister daemon restarts.

===== DHT commands =====

==== ping ====

<code javascript>
query = {"t":"aa", "z":"q", "q":"ping", "x":{"id":"abcdefghij0123456789"}}  

response = {"t":"aa", "z":"r", "r": {"id":"mnopqrstuvwxyz123456"}}
</code>

==== findNode ====

<code javascript>
query = {"t":"aa", "z":"q", "q":"findNode", "x": {
  "id":"abcdefghij0123456789", "target":"mnopqrstuvwxyz123456"}}

response = {"t":"aa", "z":"r", "r": {"id":"0123456789abcdefghij", "nodes": "def456..."}}
</code>

==== announcePeer ====

//Note: this command may be removed in future.//

<code javascript>
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"}}
</code>

==== getPeers ====

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

==== putData ====

<code javascript>
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"}}
</code>

See [[development:dht_protocol:structures#general structure]] for content detail.

Note: target_id is the hash of bencoded ''"target"'' field.

==== getData ====

<code javascript>
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" ] }}
</code>

See [[development:dht_protocol:structures#general structure]] for content detail.

Note: target_id is the hash of bencoded ''"target"'' field.