140 lines
3.9 KiB
Go
140 lines
3.9 KiB
Go
// Copyright 2017-2019 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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"fmt"
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"strings"
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"github.com/ethereum/go-ethereum/accounts/abi/bind"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/core/types"
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"github.com/wealdtech/go-ens/v3/contracts/dnsresolver"
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"golang.org/x/crypto/sha3"
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)
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// DNSResolver is the structure for the DNS resolver contract
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type DNSResolver struct {
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backend bind.ContractBackend
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domain string
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Contract *dnsresolver.Contract
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ContractAddr common.Address
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}
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// NewDNSResolver creates a new DNS resolver for a given domain
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func NewDNSResolver(backend bind.ContractBackend, domain string) (*DNSResolver, error) {
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registry, err := NewRegistry(backend)
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if err != nil {
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return nil, err
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}
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address, err := registry.ResolverAddress(domain)
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if err != nil {
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return nil, err
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}
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return NewDNSResolverAt(backend, domain, address)
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}
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// NewDNSResolverAt creates a new DNS resolver for a given domain at a given address
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func NewDNSResolverAt(backend bind.ContractBackend, domain string, address common.Address) (*DNSResolver, error) {
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contract, err := dnsresolver.NewContract(address, backend)
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if err != nil {
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return nil, err
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}
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// Ensure that this is a DNS resolver
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supported, err := contract.SupportsInterface(nil, [4]byte{0xa8, 0xfa, 0x56, 0x82})
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if err != nil {
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return nil, err
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}
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if !supported {
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return nil, fmt.Errorf("%s is not a DNS resolver contract", address.Hex())
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}
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return &DNSResolver{
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backend: backend,
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domain: domain,
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Contract: contract,
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ContractAddr: address,
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}, nil
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}
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// Record obtains an RRSet for a name
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func (r *DNSResolver) Record(name string, rrType uint16) ([]byte, error) {
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nameHash, err := NameHash(r.domain)
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if err != nil {
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return nil, err
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}
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return r.Contract.DnsRecord(nil, nameHash, DNSWireFormatDomainHash(name), rrType)
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}
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// HasRecords returns true if the given name has any RRsets
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func (r *DNSResolver) HasRecords(name string) (bool, error) {
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nameHash, err := NameHash(r.domain)
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if err != nil {
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return false, err
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}
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return r.Contract.HasDNSRecords(nil, nameHash, DNSWireFormatDomainHash(name))
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}
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// SetRecords sets one or more RRSets
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func (r *DNSResolver) SetRecords(opts *bind.TransactOpts, data []byte) (*types.Transaction, error) {
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nameHash, err := NameHash(r.domain)
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if err != nil {
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return nil, err
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}
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return r.Contract.SetDNSRecords(opts, nameHash, data)
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}
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// ClearDNSZone clears all records in the zone
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func (r *DNSResolver) ClearDNSZone(opts *bind.TransactOpts) (*types.Transaction, error) {
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nameHash, err := NameHash(r.domain)
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if err != nil {
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return nil, err
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}
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return r.Contract.ClearDNSZone(opts, nameHash)
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}
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// DNSWireFormatDomainHash hashes a domain name in wire format
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func DNSWireFormatDomainHash(domain string) (hash [32]byte) {
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sha := sha3.NewLegacyKeccak256()
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sha.Write(DNSWireFormat(domain))
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sha.Sum(hash[:0])
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return
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}
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// DNSWireFormat turns a domain name in to wire format
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func DNSWireFormat(domain string) []byte {
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// Remove leading and trailing dots
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domain = strings.TrimLeft(domain, ".")
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domain = strings.TrimRight(domain, ".")
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domain = strings.ToLower(domain)
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if domain == "" {
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return []byte{0x00}
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}
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bytes := make([]byte, len(domain)+2)
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pieces := strings.Split(domain, ".")
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offset := 0
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for _, piece := range pieces {
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bytes[offset] = byte(len(piece))
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offset++
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copy(bytes[offset:offset+len(piece)], []byte(piece))
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offset += len(piece)
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}
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return bytes
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}
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