status-go/vendor/github.com/wealdtech/go-ens/v3/dnsresolver.go

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// Copyright 2017-2019 Weald Technology Trading
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package ens
import (
"fmt"
"strings"
"github.com/ethereum/go-ethereum/accounts/abi/bind"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
"github.com/wealdtech/go-ens/v3/contracts/dnsresolver"
"golang.org/x/crypto/sha3"
)
// DNSResolver is the structure for the DNS resolver contract
type DNSResolver struct {
backend bind.ContractBackend
domain string
Contract *dnsresolver.Contract
ContractAddr common.Address
}
// NewDNSResolver creates a new DNS resolver for a given domain
func NewDNSResolver(backend bind.ContractBackend, domain string) (*DNSResolver, error) {
registry, err := NewRegistry(backend)
if err != nil {
return nil, err
}
address, err := registry.ResolverAddress(domain)
if err != nil {
return nil, err
}
return NewDNSResolverAt(backend, domain, address)
}
// NewDNSResolverAt creates a new DNS resolver for a given domain at a given address
func NewDNSResolverAt(backend bind.ContractBackend, domain string, address common.Address) (*DNSResolver, error) {
contract, err := dnsresolver.NewContract(address, backend)
if err != nil {
return nil, err
}
// Ensure that this is a DNS resolver
supported, err := contract.SupportsInterface(nil, [4]byte{0xa8, 0xfa, 0x56, 0x82})
if err != nil {
return nil, err
}
if !supported {
return nil, fmt.Errorf("%s is not a DNS resolver contract", address.Hex())
}
return &DNSResolver{
backend: backend,
domain: domain,
Contract: contract,
ContractAddr: address,
}, nil
}
// Record obtains an RRSet for a name
func (r *DNSResolver) Record(name string, rrType uint16) ([]byte, error) {
nameHash, err := NameHash(r.domain)
if err != nil {
return nil, err
}
return r.Contract.DnsRecord(nil, nameHash, DNSWireFormatDomainHash(name), rrType)
}
// HasRecords returns true if the given name has any RRsets
func (r *DNSResolver) HasRecords(name string) (bool, error) {
nameHash, err := NameHash(r.domain)
if err != nil {
return false, err
}
return r.Contract.HasDNSRecords(nil, nameHash, DNSWireFormatDomainHash(name))
}
// SetRecords sets one or more RRSets
func (r *DNSResolver) SetRecords(opts *bind.TransactOpts, data []byte) (*types.Transaction, error) {
nameHash, err := NameHash(r.domain)
if err != nil {
return nil, err
}
return r.Contract.SetDNSRecords(opts, nameHash, data)
}
// ClearDNSZone clears all records in the zone
func (r *DNSResolver) ClearDNSZone(opts *bind.TransactOpts) (*types.Transaction, error) {
nameHash, err := NameHash(r.domain)
if err != nil {
return nil, err
}
return r.Contract.ClearDNSZone(opts, nameHash)
}
// DNSWireFormatDomainHash hashes a domain name in wire format
func DNSWireFormatDomainHash(domain string) (hash [32]byte) {
sha := sha3.NewLegacyKeccak256()
sha.Write(DNSWireFormat(domain))
sha.Sum(hash[:0])
return
}
// DNSWireFormat turns a domain name in to wire format
func DNSWireFormat(domain string) []byte {
// Remove leading and trailing dots
domain = strings.TrimLeft(domain, ".")
domain = strings.TrimRight(domain, ".")
domain = strings.ToLower(domain)
if domain == "" {
return []byte{0x00}
}
bytes := make([]byte, len(domain)+2)
pieces := strings.Split(domain, ".")
offset := 0
for _, piece := range pieces {
bytes[offset] = byte(len(piece))
offset++
copy(bytes[offset:offset+len(piece)], []byte(piece))
offset += len(piece)
}
return bytes
}