dht interface beginnings

Author: jbenet

README.md

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+package dht
+
+// TODO. SEE https://github.com/jbenet/node-ipfs/blob/master/submodules/ipfs-dht/index.js
+
+
+// IpfsDHT is an implementation of Kademlia with Coral and S/Kademlia modifications.
+// It is used to implement the base IpfsRouting module.
+type IpfsDHT struct {
+  routes RoutingTable
+}

dht.go

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+package dht
+
+import (
+  "time"
+  peer "github.com/jbenet/go-ipfs/peer"
+  u "github.com/jbenet/go-ipfs/util"
+)
+
+
+// This file implements the Routing interface for the IpfsDHT struct.
+
+// Basic Put/Get
+
+// PutValue adds value corresponding to given Key.
+func (s *IpfsDHT) PutValue(key u.Key, value []byte) (error) {
+  return u.ErrNotImplemented
+}
+
+// GetValue searches for the value corresponding to given Key.
+func (s *IpfsDHT) GetValue(key u.Key, timeout time.Duration) ([]byte, error) {
+  return nil, u.ErrNotImplemented
+}
+
+
+// Value provider layer of indirection.
+// This is what DSHTs (Coral and MainlineDHT) do to store large values in a DHT.
+
+// Announce that this node can provide value for given key
+func (s *IpfsDHT) Provide(key u.Key) (error) {
+  return u.ErrNotImplemented
+}
+
+// FindProviders searches for peers who can provide the value for given key.
+func (s *IpfsDHT) FindProviders(key u.Key, timeout time.Duration) (*peer.Peer, error) {
+  return nil, u.ErrNotImplemented
+}
+
+
+// Find specific Peer
+
+// FindPeer searches for a peer with given ID.
+func (s *IpfsDHT) FindPeer(id peer.ID, timeout time.Duration) (*peer.Peer, error) {
+  return nil, u.ErrNotImplemented
+}

routing.go

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+package dht
+
+import (
+  "container/list"
+)
+
+
+// ID for IpfsDHT should be a byte slice, to allow for simpler operations
+// (xor). DHT ids are based on the peer.IDs.
+//
+// NOTE: peer.IDs are biased because they are (a) multihashes (first bytes
+// biased), and (b) first bits are zeroes when using the S/Kademlia PoW.
+// Thus, may need to re-hash keys (uniform dist). TODO(jbenet)
+type ID []byte
+
+// Bucket holds a list of peers.
+type Bucket []*list.List
+
+
+// RoutingTable defines the routing table.
+type RoutingTable struct {
+
+  // kBuckets define all the fingers to other nodes.
+  Buckets []Bucket
+}
+
+
+func (id ID) commonPrefixLen() int {
+  for i := 0; i < len(id); i++ {
+    for j := 0; j < 8; j++ {
+      if (id[i] >> uint8(7 - j)) & 0x1 != 0 {
+        return i * 8 + j;
+      }
+    }
+  }
+  return len(id) * 8 - 1;
+}
+
+func xor(a, b ID) ID {
+
+  // ids may actually be of different sizes.
+  var ba ID
+  var bb ID
+  if len(a) >= len(b) {
+    ba = a
+    bb = b
+  } else {
+    ba = b
+    bb = a
+  }
+
+  c := make(ID, len(ba))
+  for i := 0; i < len(ba); i++ {
+    if len(bb) > i {
+      c[i] = ba[i] ^ bb[i]
+    } else {
+      c[i] = ba[i] ^ 0
+    }
+  }
+  return c
+}