81 lines
2.2 KiB
Go
81 lines
2.2 KiB
Go
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// Copyright 2017 Weald Technology Trading
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package ens
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import (
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"strings"
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"golang.org/x/net/idna"
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"golang.org/x/crypto/sha3"
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)
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var p = idna.New(idna.MapForLookup(), idna.StrictDomainName(false), idna.Transitional(false))
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var pStrict = idna.New(idna.MapForLookup(), idna.StrictDomainName(true), idna.Transitional(false))
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// Normalize normalizes a name according to the ENS rules
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func Normalize(input string) (output string, err error) {
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output, err = p.ToUnicode(input)
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if err != nil {
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return
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}
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// If the name started with a period then ToUnicode() removes it, but we want to keep it
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if strings.HasPrefix(input, ".") && !strings.HasPrefix(output, ".") {
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output = "." + output
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}
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return
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}
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// LabelHash generates a simple hash for a piece of a name.
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func LabelHash(label string) (hash [32]byte, err error) {
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normalizedLabel, err := Normalize(label)
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if err != nil {
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return
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}
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sha := sha3.NewLegacyKeccak256()
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sha.Write([]byte(normalizedLabel))
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sha.Sum(hash[:0])
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return
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}
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// NameHash generates a hash from a name that can be used to
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// look up the name in ENS
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func NameHash(name string) (hash [32]byte, err error) {
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if name == "" {
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return
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}
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normalizedName, err := Normalize(name)
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if err != nil {
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return
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}
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parts := strings.Split(normalizedName, ".")
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for i := len(parts) - 1; i >= 0; i-- {
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hash = nameHashPart(hash, parts[i])
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}
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return
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}
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func nameHashPart(currentHash [32]byte, name string) (hash [32]byte) {
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sha := sha3.NewLegacyKeccak256()
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sha.Write(currentHash[:])
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nameSha := sha3.NewLegacyKeccak256()
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nameSha.Write([]byte(name))
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nameHash := nameSha.Sum(nil)
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sha.Write(nameHash)
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sha.Sum(hash[:0])
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return
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}
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