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121 lines
3.5 KiB
121 lines
3.5 KiB
// Copyright 2016 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package ens
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import (
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"encoding/binary"
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"errors"
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"fmt"
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"github.com/ethereum/go-ethereum/common"
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)
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const (
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cidv1 = 0x1
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nsIpfs = 0xe3
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nsSwarm = 0xe4
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swarmTypecode = 0xfa // swarm manifest, see https://github.com/multiformats/multicodec/blob/master/table.csv
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swarmHashtype = 0x1b // keccak256, see https://github.com/multiformats/multicodec/blob/master/table.csv
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hashLength = 32
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)
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// deocodeEIP1577ContentHash decodes a chain-stored content hash from an ENS record according to EIP-1577
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// a successful decode will result the different parts of the content hash in accordance to the CID spec
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// Note: only CIDv1 is supported
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func decodeEIP1577ContentHash(buf []byte) (storageNs, contentType, hashType, hashLength uint64, hash []byte, err error) {
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if len(buf) < 10 {
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return 0, 0, 0, 0, nil, errors.New("buffer too short")
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}
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storageNs, n := binary.Uvarint(buf)
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buf = buf[n:]
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vers, n := binary.Uvarint(buf)
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if vers != 1 {
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return 0, 0, 0, 0, nil, fmt.Errorf("expected cid v1, got: %d", vers)
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}
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buf = buf[n:]
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contentType, n = binary.Uvarint(buf)
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buf = buf[n:]
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hashType, n = binary.Uvarint(buf)
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buf = buf[n:]
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hashLength, n = binary.Uvarint(buf)
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hash = buf[n:]
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if len(hash) != int(hashLength) {
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return 0, 0, 0, 0, nil, errors.New("hash length mismatch")
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}
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return storageNs, contentType, hashType, hashLength, hash, nil
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}
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func extractContentHash(buf []byte) (common.Hash, error) {
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storageNs, _ /*contentType*/, _ /* hashType*/, decodedHashLength, hashBytes, err := decodeEIP1577ContentHash(buf)
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if err != nil {
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return common.Hash{}, err
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}
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if storageNs != nsSwarm {
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return common.Hash{}, errors.New("unknown storage system")
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}
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//todo: for the time being we implement loose enforcement for the EIP rules until ENS manager is updated
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/*if contentType != swarmTypecode {
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return common.Hash{}, errors.New("unknown content type")
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}
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if hashType != swarmHashtype {
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return common.Hash{}, errors.New("unknown multihash type")
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}*/
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if decodedHashLength != hashLength {
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return common.Hash{}, errors.New("odd hash length, swarm expects 32 bytes")
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}
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if len(hashBytes) != int(hashLength) {
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return common.Hash{}, errors.New("hash length mismatch")
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}
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return common.BytesToHash(buf), nil
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}
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func EncodeSwarmHash(hash common.Hash) ([]byte, error) {
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var cidBytes []byte
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var headerBytes = []byte{
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nsSwarm, //swarm namespace
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cidv1, // CIDv1
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swarmTypecode, // swarm hash
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swarmHashtype, // keccak256 hash
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hashLength, //hash length. 32 bytes
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}
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varintbuf := make([]byte, binary.MaxVarintLen64)
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for _, v := range headerBytes {
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n := binary.PutUvarint(varintbuf, uint64(v))
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cidBytes = append(cidBytes, varintbuf[:n]...)
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}
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cidBytes = append(cidBytes, hash[:]...)
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return cidBytes, nil
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}
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