1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
|
package resolver
import (
"encoding/binary"
"fmt"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/crypto"
xe "github.com/ethereum/go-ethereum/xeth"
)
/*
Resolver implements the Ethereum DNS mapping
HashReg : Key Hash (hash of domain name or contract code) -> Content Hash
UrlHint : Content Hash -> Url Hint
The resolver is meant to be called by the roundtripper transport implementation
of a url scheme
*/
// contract addresses will be hardcoded after they're created
var URLHintContractAddress string = "0000000000000000000000000000000000000000000000000000000000001234"
var HashRegContractAddress string = "0000000000000000000000000000000000000000000000000000000000005678"
func CreateContracts(xeth *xe.XEth, addr string) {
var err error
URLHintContractAddress, err = xeth.Transact(addr, "", "100000000000", "1000000", "100000", ContractCodeURLhint)
if err != nil {
panic(err)
}
HashRegContractAddress, err = xeth.Transact(addr, "", "100000000000", "1000000", "100000", ContractCodeHashReg)
if err != nil {
panic(err)
}
URLHintContractAddress = URLHintContractAddress[2:]
HashRegContractAddress = HashRegContractAddress[2:]
}
type Resolver struct {
backend Backend
urlHintContractAddress string
hashRegContractAddress string
}
type Backend interface {
StorageAt(string, string) string
}
func New(eth Backend, uhca, nrca string) *Resolver {
return &Resolver{eth, uhca, nrca}
}
func (self *Resolver) KeyToContentHash(khash common.Hash) (chash common.Hash, err error) {
// look up in hashReg
key := storageAddress(storageMapping(storageIdx2Addr(1), khash[:]))
hash := self.backend.StorageAt("0x"+self.hashRegContractAddress, key)
if hash == "0x0" || len(hash) < 3 {
err = fmt.Errorf("GetHashReg: content hash not found")
return
}
copy(chash[:], common.Hex2BytesFixed(hash[2:], 32))
return
}
func (self *Resolver) ContentHashToUrl(chash common.Hash) (uri string, err error) {
// look up in URL reg
var str string = " "
var idx uint32
for len(str) > 0 {
mapaddr := storageMapping(storageIdx2Addr(1), chash[:])
key := storageAddress(storageFixedArray(mapaddr, storageIdx2Addr(idx)))
hex := self.backend.StorageAt("0x"+self.urlHintContractAddress, key)
str = string(common.Hex2Bytes(hex[2:]))
l := len(str)
for (l > 0) && (str[l-1] == 0) {
l--
}
str = str[:l]
uri = uri + str
idx++
}
if len(uri) == 0 {
err = fmt.Errorf("GetURLhint: URL hint not found")
}
return
}
func (self *Resolver) KeyToUrl(key common.Hash) (uri string, hash common.Hash, err error) {
// look up in urlHint
hash, err = self.KeyToContentHash(key)
if err != nil {
return
}
uri, err = self.ContentHashToUrl(hash)
return
}
func storageIdx2Addr(varidx uint32) []byte {
data := make([]byte, 32)
binary.BigEndian.PutUint32(data[28:32], varidx)
return data
}
func storageMapping(addr, key []byte) []byte {
data := make([]byte, 64)
copy(data[0:32], key[0:32])
copy(data[32:64], addr[0:32])
return crypto.Sha3(data)
}
func storageFixedArray(addr, idx []byte) []byte {
var carry byte
for i := 31; i >= 0; i-- {
var b byte = addr[i] + idx[i] + carry
if b < addr[i] {
carry = 1
} else {
carry = 0
}
addr[i] = b
}
return addr
}
func storageAddress(addr []byte) string {
return "0x" + common.Bytes2Hex(addr)
}
|
