118 lines
4.2 KiB
Go
118 lines
4.2 KiB
Go
// Copyright 2018 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 mru
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import (
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"encoding/binary"
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"hash"
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"github.com/ethereum/go-ethereum/swarm/storage"
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)
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// LookupParams is used to specify constraints when performing an update lookup
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// Limit defines whether or not the lookup should be limited
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// If Limit is set to true then Max defines the amount of hops that can be performed
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type LookupParams struct {
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UpdateLookup
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Limit uint32
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}
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// RootAddr returns the metadata chunk address
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func (r *LookupParams) RootAddr() storage.Address {
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return r.rootAddr
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}
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func NewLookupParams(rootAddr storage.Address, period, version uint32, limit uint32) *LookupParams {
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return &LookupParams{
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UpdateLookup: UpdateLookup{
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period: period,
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version: version,
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rootAddr: rootAddr,
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},
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Limit: limit,
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}
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}
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// LookupLatest generates lookup parameters that look for the latest version of a resource
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func LookupLatest(rootAddr storage.Address) *LookupParams {
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return NewLookupParams(rootAddr, 0, 0, 0)
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}
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// LookupLatestVersionInPeriod generates lookup parameters that look for the latest version of a resource in a given period
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func LookupLatestVersionInPeriod(rootAddr storage.Address, period uint32) *LookupParams {
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return NewLookupParams(rootAddr, period, 0, 0)
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}
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// LookupVersion generates lookup parameters that look for a specific version of a resource
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func LookupVersion(rootAddr storage.Address, period, version uint32) *LookupParams {
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return NewLookupParams(rootAddr, period, version, 0)
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}
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// UpdateLookup represents the components of a resource update search key
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type UpdateLookup struct {
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period uint32
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version uint32
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rootAddr storage.Address
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}
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// 4 bytes period
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// 4 bytes version
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// storage.Keylength for rootAddr
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const updateLookupLength = 4 + 4 + storage.KeyLength
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// UpdateAddr calculates the resource update chunk address corresponding to this lookup key
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func (u *UpdateLookup) UpdateAddr() (updateAddr storage.Address) {
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serializedData := make([]byte, updateLookupLength)
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u.binaryPut(serializedData)
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hasher := hashPool.Get().(hash.Hash)
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defer hashPool.Put(hasher)
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hasher.Reset()
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hasher.Write(serializedData)
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return hasher.Sum(nil)
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}
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// binaryPut serializes this UpdateLookup instance into the provided slice
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func (u *UpdateLookup) binaryPut(serializedData []byte) error {
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if len(serializedData) != updateLookupLength {
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return NewErrorf(ErrInvalidValue, "Incorrect slice size to serialize UpdateLookup. Expected %d, got %d", updateLookupLength, len(serializedData))
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}
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if len(u.rootAddr) != storage.KeyLength {
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return NewError(ErrInvalidValue, "UpdateLookup.binaryPut called without rootAddr set")
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}
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binary.LittleEndian.PutUint32(serializedData[:4], u.period)
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binary.LittleEndian.PutUint32(serializedData[4:8], u.version)
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copy(serializedData[8:], u.rootAddr[:])
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return nil
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}
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// binaryLength returns the expected size of this structure when serialized
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func (u *UpdateLookup) binaryLength() int {
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return updateLookupLength
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}
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// binaryGet restores the current instance from the information contained in the passed slice
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func (u *UpdateLookup) binaryGet(serializedData []byte) error {
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if len(serializedData) != updateLookupLength {
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return NewErrorf(ErrInvalidValue, "Incorrect slice size to read UpdateLookup. Expected %d, got %d", updateLookupLength, len(serializedData))
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}
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u.period = binary.LittleEndian.Uint32(serializedData[:4])
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u.version = binary.LittleEndian.Uint32(serializedData[4:8])
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u.rootAddr = storage.Address(make([]byte, storage.KeyLength))
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copy(u.rootAddr[:], serializedData[8:])
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return nil
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}
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