1package kademlia
 2
 3import (
 4	"bytes"
 5	"crypto/rand"
 6	"crypto/sha256"
 7	"encoding/hex"
 8)
 9
10type ID [B]byte
11
12func NewID() (ID, error) {
13	b := make([]byte, 32)
14	_, err := rand.Read(b)
15	if err != nil {
16		return ID{}, err
17	}
18	var id ID
19	copy(id[:], b[:B])
20	return id, nil
21}
22
23func (id ID) String() string {
24	return hex.EncodeToString(id[:])
25}
26
27func (id ID) MarshalText() ([]byte, error) {
28	return []byte(hex.EncodeToString(id[:])), nil
29}
30
31func (id *ID) UnmarshalText(data []byte) error {
32	var err error
33	var idFromStr ID
34	idFromStr, err = IDFromString(string(data))
35	if err != nil {
36		return err
37	}
38	copy(id[:], idFromStr[:])
39	return nil
40}
41
42func IDFromString(s string) (ID, error) {
43	b, err := hex.DecodeString(s)
44	if err != nil {
45		return ID{}, err
46	}
47	var id ID
48	copy(id[:], b[:B])
49	return id, nil
50}
51
52func (idA ID) Equal(idB ID) bool {
53	return bytes.Equal(idA[:], idB[:])
54}
55
56// Cmp returns true if idA > idB
57func (idA ID) Cmp(idB ID) bool {
58	for i := 0; i < len(idA); i++ {
59		if idA[i] != idB[i] {
60			return idA[i] > idB[i]
61		}
62	}
63	return false
64}
65
66func (idA ID) Distance(idB ID) ID {
67	var d ID
68	for i := 0; i < B; i++ {
69		d[i] = idA[i] ^ idB[i]
70	}
71	return d
72}
73
74func HashData(d []byte) ID {
75	h := sha256.Sum256(d)
76	var r ID
77	copy(r[:], h[:20])
78	return r
79}