initial commit, node ids

README.md

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+# go-dht
+
+Kademlia DHT Go implementation.
+
+Following the specification from https://pdos.csail.mit.edu/~petar/papers/maymounkov-kademlia-lncs.pdf and http://xlattice.sourceforge.net/components/protocol/kademlia/specs.html

go.mod

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+module go-dht
+
+go 1.12
+
+require github.com/stretchr/testify v1.4.0

go.sum

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+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
+github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

id.go

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+package main
+
+import (
+	"crypto/rand"
+	"encoding/hex"
+)
+
+type ID [B]byte
+
+func NewID() (ID, error) {
+	b := make([]byte, 32)
+	_, err := rand.Read(b)
+	if err != nil {
+		return ID{}, err
+	}
+	var id ID
+	copy(id[:], b[:B])
+	return id, nil
+}
+
+func (id ID) String() string {
+	return hex.EncodeToString(id[:])
+}
+
+func IDFromString(s string) (ID, error) {
+	b, err := hex.DecodeString(s)
+	if err != nil {
+		return ID{}, err
+	}
+	var id ID
+	copy(id[:], b[:B])
+	return id, nil
+}
+
+// Cmp returns true if idA > idB
+func (idA ID) Cmp(idB ID) bool {
+	for i := 0; i < len(idA); i++ {
+		if idA[i] != idB[i] {
+			return idA[i] > idB[i]
+		}
+	}
+	return false
+}
+
+func (idA ID) Distance(idB ID) ID {
+	var d ID
+	for i := 0; i < B; i++ {
+		d[i] = idA[i] ^ idB[i]
+	}
+	return d
+}

id_test.go

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+package main
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNewID(t *testing.T) {
+	_, err := NewID()
+	assert.Nil(t, err)
+
+	idA, err := IDFromString("0fd85ddddf15aeec2d5d8b01b013dbca030a18d7")
+	assert.Nil(t, err)
+	assert.Equal(t, "0fd85ddddf15aeec2d5d8b01b013dbca030a18d7", idA.String())
+}
+
+func TestIDCmp(t *testing.T) {
+	idA, err := IDFromString("0fd85ddddf15aeec2d5d8b01b013dbca030a18d7")
+	assert.Nil(t, err)
+	idB, err := IDFromString("c48d8b53dbefb609ed4e94d386dd5b22efcb2c5b")
+	assert.Nil(t, err)
+	assert.True(t, !idA.Cmp(idB))
+}
+
+func TestIDDistance(t *testing.T) {
+	idA, err := IDFromString("0fd85ddddf15aeec2d5d8b01b013dbca030a18d7")
+	assert.Nil(t, err)
+	idB, err := IDFromString("c48d8b53dbefb609ed4e94d386dd5b22efcb2c5b")
+	assert.Nil(t, err)
+	assert.Equal(t, "cb55d68e04fa18e5c0131fd236ce80e8ecc1348c", idA.Distance(idB).String())
+}