forked from cerc-io/plugeth
86 lines
2.0 KiB
Go
86 lines
2.0 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/core"
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"github.com/ethereum/go-ethereum/crypto"
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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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const (
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URLHintContractAddress = core.ContractAddrURLhint
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HashRegContractAddress = core.ContractAddrHashReg
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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(1, khash[:])
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hash := self.backend.StorageAt("0x"+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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key := storageAddress(1, chash[:])
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hex := self.backend.StorageAt("0x"+self.urlHintContractAddress, key)
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uri = string(common.Hex2Bytes(hex[2:]))
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l := len(uri)
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for (l > 0) && (uri[l-1] == 0) {
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l--
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}
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uri = uri[:l]
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if l == 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 storageAddress(varidx uint32, key []byte) string {
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data := make([]byte, 64)
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binary.BigEndian.PutUint32(data[60:64], varidx)
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copy(data[0:32], key[0:32])
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return "0x" + common.Bytes2Hex(crypto.Sha3(data))
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}
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