129 lines
3.1 KiB
Go
129 lines
3.1 KiB
Go
package resolver
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import (
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"encoding/binary"
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"fmt"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/crypto"
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xe "github.com/ethereum/go-ethereum/xeth"
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)
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/*
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Resolver implements the Ethereum DNS mapping
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HashReg : Key Hash (hash of domain name or contract code) -> Content Hash
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UrlHint : Content Hash -> Url Hint
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The resolver is meant to be called by the roundtripper transport implementation
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of a url scheme
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*/
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// contract addresses will be hardcoded after they're created
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var URLHintContractAddress string = "0000000000000000000000000000000000000000000000000000000000001234"
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var HashRegContractAddress string = "0000000000000000000000000000000000000000000000000000000000005678"
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func CreateContracts(xeth *xe.XEth, addr string) {
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var err error
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URLHintContractAddress, err = xeth.Transact(addr, "", "", "100000000000", "1000000", "100000", ContractCodeURLhint)
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if err != nil {
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panic(err)
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}
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HashRegContractAddress, err = xeth.Transact(addr, "", "", "100000000000", "1000000", "100000", ContractCodeHashReg)
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if err != nil {
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panic(err)
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}
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}
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type Resolver struct {
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backend Backend
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urlHintContractAddress string
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hashRegContractAddress string
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}
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type Backend interface {
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StorageAt(string, string) string
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}
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func New(eth Backend, uhca, nrca string) *Resolver {
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return &Resolver{eth, uhca, nrca}
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}
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func (self *Resolver) KeyToContentHash(khash common.Hash) (chash common.Hash, err error) {
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// look up in hashReg
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key := storageAddress(storageMapping(storageIdx2Addr(1), khash[:]))
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hash := self.backend.StorageAt(self.hashRegContractAddress, key)
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if hash == "0x0" || len(hash) < 3 {
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err = fmt.Errorf("GetHashReg: content hash not found")
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return
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}
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copy(chash[:], common.Hex2BytesFixed(hash[2:], 32))
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return
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}
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func (self *Resolver) ContentHashToUrl(chash common.Hash) (uri string, err error) {
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// look up in URL reg
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var str string = " "
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var idx uint32
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for len(str) > 0 {
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mapaddr := storageMapping(storageIdx2Addr(1), chash[:])
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key := storageAddress(storageFixedArray(mapaddr, storageIdx2Addr(idx)))
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hex := self.backend.StorageAt(self.urlHintContractAddress, key)
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str = string(common.Hex2Bytes(hex[2:]))
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l := len(str)
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for (l > 0) && (str[l-1] == 0) {
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l--
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}
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str = str[:l]
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uri = uri + str
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idx++
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}
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if len(uri) == 0 {
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err = fmt.Errorf("GetURLhint: URL hint not found")
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}
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return
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}
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func (self *Resolver) KeyToUrl(key common.Hash) (uri string, hash common.Hash, err error) {
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// look up in urlHint
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hash, err = self.KeyToContentHash(key)
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if err != nil {
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return
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}
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uri, err = self.ContentHashToUrl(hash)
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return
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}
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func storageIdx2Addr(varidx uint32) []byte {
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data := make([]byte, 32)
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binary.BigEndian.PutUint32(data[28:32], varidx)
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return data
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}
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func storageMapping(addr, key []byte) []byte {
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data := make([]byte, 64)
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copy(data[0:32], key[0:32])
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copy(data[32:64], addr[0:32])
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return crypto.Sha3(data)
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}
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func storageFixedArray(addr, idx []byte) []byte {
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var carry byte
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for i := 31; i >= 0; i-- {
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var b byte = addr[i] + idx[i] + carry
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if b < addr[i] {
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carry = 1
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} else {
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carry = 0
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}
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addr[i] = b
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}
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return addr
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}
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func storageAddress(addr []byte) string {
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return common.ToHex(addr)
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}
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