// Copyright 2018 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
// Handler is the API for Mutable Resources
// It enables creating, updating, syncing and retrieving resources and their update data
package mru
import (
"bytes"
"context"
"sync"
"time"
"unsafe"
"github.com/ethereum/go-ethereum/swarm/chunk"
"github.com/ethereum/go-ethereum/swarm/log"
"github.com/ethereum/go-ethereum/swarm/storage"
)
type Handler struct {
chunkStore *storage.NetStore
HashSize int
resources map[uint64]*resource
resourceLock sync.RWMutex
storeTimeout time.Duration
queryMaxPeriods uint32
}
// HandlerParams pass parameters to the Handler constructor NewHandler
// Signer and TimestampProvider are mandatory parameters
type HandlerParams struct {
QueryMaxPeriods uint32
}
// hashPool contains a pool of ready hashers
var hashPool sync.Pool
var minimumChunkLength int
// init initializes the package and hashPool
func init() {
hashPool = sync.Pool{
New: func() interface{} {
return storage.MakeHashFunc(resourceHashAlgorithm)()
},
}
if minimumMetadataLength < minimumUpdateDataLength {
minimumChunkLength = minimumMetadataLength
} else {
minimumChunkLength = minimumUpdateDataLength
}
}
// NewHandler creates a new Mutable Resource API
func NewHandler(params *HandlerParams) *Handler {
rh := &Handler{
resources: make(map[uint64]*resource),
storeTimeout: defaultStoreTimeout,
queryMaxPeriods: params.QueryMaxPeriods,
}
for i := 0; i < hasherCount; i++ {
hashfunc := storage.MakeHashFunc(resourceHashAlgorithm)()
if rh.HashSize == 0 {
rh.HashSize = hashfunc.Size()
}
hashPool.Put(hashfunc)
}
return rh
}
// SetStore sets the store backend for the Mutable Resource API
func (h *Handler) SetStore(store *storage.NetStore) {
h.chunkStore = store
}
// Validate is a chunk validation method
// If it looks like a resource update, the chunk address is checked against the ownerAddr of the update's signature
// It implements the storage.ChunkValidator interface
func (h *Handler) Validate(chunkAddr storage.Address, data []byte) bool {
dataLength := len(data)
if dataLength < minimumChunkLength || dataLength > chunk.DefaultSize+8 {
return false
}
//metadata chunks have the first two bytes set to zero
if data[0] == 0 && data[1] == 0 && dataLength >= minimumMetadataLength {
//metadata chunk
rootAddr, _ := metadataHash(data)
valid := bytes.Equal(chunkAddr, rootAddr)
if !valid {
log.Debug("Invalid root metadata chunk with address", "addr", chunkAddr.Hex())
}
return valid
}
// if it is not a metadata chunk, check if it is a properly formatted update chunk with
// valid signature and proof of ownership of the resource it is trying
// to update
// First, deserialize the chunk
var r SignedResourceUpdate
if err := r.fromChunk(chunkAddr, data); err != nil {
log.Debug("Invalid resource chunk", "addr", chunkAddr.Hex(), "err", err.Error())
return false
}
// check that the lookup information contained in the chunk matches the updateAddr (chunk search key)
// that was used to retrieve this chunk
// if this validation fails, someone forged a chunk.
if !bytes.Equal(chunkAddr, r.updateHeader.UpdateAddr()) {
log.Debug("period,version,rootAddr contained in update chunk do not match updateAddr", "addr", chunkAddr.Hex())
return false
}
// Verify signatures and that the signer actually owns the resource
// If it fails, it means either the signature is not valid, data is corrupted
// or someone is trying to update someone else's resource.
if err := r.Verify(); err != nil {
log.Debug("Invalid signature", "err", err)
return false
}
return true
}
// GetContent retrieves the data payload of the last synced update of the Mutable Resource
func (h *Handler) GetContent(rootAddr storage.Address) (storage.Address, []byte, error) {
rsrc := h.get(rootAddr)
if rsrc == nil || !rsrc.isSynced() {
return nil, nil, NewError(ErrNotFound, " does not exist or is not synced")
}
return rsrc.lastKey, rsrc.data, nil
}
// GetLastPeriod retrieves the period of the last synced update of the Mutable Resource
func (h *Handler) GetLastPeriod(rootAddr storage.Address) (uint32, error) {
rsrc := h.get(rootAddr)
if rsrc == nil {
return 0, NewError(ErrNotFound, " does not exist")
} else if !rsrc.isSynced() {
return 0, NewError(ErrNotSynced, " is not synced")
}
return rsrc.period, nil
}
// GetVersion retrieves the period of the last synced update of the Mutable Resource
func (h *Handler) GetVersion(rootAddr storage.Address) (uint32, error) {
rsrc := h.get(rootAddr)
if rsrc == nil {
return 0, NewError(ErrNotFound, " does not exist")
} else if !rsrc.isSynced() {
return 0, NewError(ErrNotSynced, " is not synced")
}
return rsrc.version, nil
}
// New creates a new metadata chunk out of the request passed in.
func (h *Handler) New(ctx context.Context, request *Request) error {
// frequency 0 is invalid
if request.metadata.Frequency == 0 {
return NewError(ErrInvalidValue, "frequency cannot be 0 when creating a resource")
}
// make sure owner is set to something
if request.metadata.Owner == zeroAddr {
return NewError(ErrInvalidValue, "ownerAddr must be set to create a new metadata chunk")
}
// create the meta chunk and store it in swarm
chunk, metaHash, err := request.metadata.newChunk()
if err != nil {
return err
}
if request.metaHash != nil && !bytes.Equal(request.metaHash, metaHash) ||
request.rootAddr != nil && !bytes.Equal(request.rootAddr, chunk.Addr) {
return NewError(ErrInvalidValue, "metaHash in UpdateRequest does not match actual metadata")
}
request.metaHash = metaHash
request.rootAddr = chunk.Addr
h.chunkStore.Put(ctx, chunk)
log.Debug("new resource", "name", request.metadata.Name, "startTime", request.metadata.StartTime, "frequency", request.metadata.Frequency, "owner", request.metadata.Owner)
// create the internal index for the resource and populate it with its metadata
rsrc := &resource{
resourceUpdate: resourceUpdate{
updateHeader: updateHeader{
UpdateLookup: UpdateLookup{
rootAddr: chunk.Addr,
},
},
},
ResourceMetadata: request.metadata,
updated: time.Now(),
}
h.set(chunk.Addr, rsrc)
return nil
}
// NewUpdateRequest prepares an UpdateRequest structure with all the necessary information to
// just add the desired data and sign it.
// The resulting structure can then be signed and passed to Handler.Update to be verified and sent
func (h *Handler) NewUpdateRequest(ctx context.Context, rootAddr storage.Address) (updateRequest *Request, err error) {
if rootAddr == nil {
return nil, NewError(ErrInvalidValue, "rootAddr cannot be nil")
}
// Make sure we have a cache of the metadata chunk
rsrc, err := h.Load(ctx, rootAddr)
if err != nil {
return nil, err
}
now := TimestampProvider.Now()
updateRequest = new(Request)
updateRequest.period, err = getNextPeriod(rsrc.StartTime.Time, now.Time, rsrc.Frequency)
if err != nil {
return nil, err
}
if _, err = h.lookup(rsrc, LookupLatestVersionInPeriod(rsrc.rootAddr, updateRequest.period)); err != nil {
if err.(*Error).code != ErrNotFound {
return nil, err
}
// not finding updates means that there is a network error
// or that the resource really does not have updates in this period.
}
updateRequest.multihash = rsrc.multihash
updateRequest.rootAddr = rsrc.rootAddr
updateRequest.metaHash = rsrc.metaHash
updateRequest.metadata = rsrc.ResourceMetadata
// if we already have an update for this period then increment version
// resource object MUST be in sync for version to be correct, but we checked this earlier in the method already
if h.hasUpdate(rootAddr, updateRequest.period) {
updateRequest.version = rsrc.version + 1
} else {
updateRequest.version = 1
}
return updateRequest, nil
}
// Lookup retrieves a specific or latest version of the resource update with metadata chunk at params.Root
// Lookup works differently depending on the configuration of `LookupParams`
// See the `LookupParams` documentation and helper functions:
// `LookupLatest`, `LookupLatestVersionInPeriod` and `LookupVersion`
// When looking for the latest update, it starts at the next period after the current time.
// upon failure tries the corresponding keys of each previous period until one is found
// (or startTime is reached, in which case there are no updates).
func (h *Handler) Lookup(ctx context.Context, params *LookupParams) (*resource, error) {
rsrc := h.get(params.rootAddr)
if rsrc == nil {
return nil, NewError(ErrNothingToReturn, "resource not loaded")
}
return h.lookup(rsrc, params)
}
// LookupPrevious returns the resource before the one currently loaded in the resource cache
// This is useful where resource updates are used incrementally in contrast to
// merely replacing content.
// Requires a cached resource object to determine the current state of the resource.
func (h *Handler) LookupPrevious(ctx context.Context, params *LookupParams) (*resource, error) {
rsrc := h.get(params.rootAddr)
if rsrc == nil {
return nil, NewError(ErrNothingToReturn, "resource not loaded")
}
if !rsrc.isSynced() {
return nil, NewError(ErrNotSynced, "LookupPrevious requires synced resource.")
} else if rsrc.period == 0 {
return nil, NewError(ErrNothingToReturn, " not found")
}
var version, period uint32
if rsrc.version > 1 {
version = rsrc.version - 1
period = rsrc.period
} else if rsrc.period == 1 {
return nil, NewError(ErrNothingToReturn, "Current update is the oldest")
} else {
version = 0
period = rsrc.period - 1
}
return h.lookup(rsrc, NewLookupParams(rsrc.rootAddr, period, version, params.Limit))
}
// base code for public lookup methods
func (h *Handler) lookup(rsrc *resource, params *LookupParams) (*resource, error) {
lp := *params
// we can't look for anything without a store
if h.chunkStore == nil {
return nil, NewError(ErrInit, "Call Handler.SetStore() before performing lookups")
}
var specificperiod bool
if lp.period > 0 {
specificperiod = true
} else {
// get the current time and the next period
now := TimestampProvider.Now()
var period uint32
period, err := getNextPeriod(rsrc.StartTime.Time, now.Time, rsrc.Frequency)
if err != nil {
return nil, err
}
lp.period = period
}
// start from the last possible period, and iterate previous ones
// (unless we want a specific period only) until we find a match.
// If we hit startTime we're out of options
var specificversion bool
if lp.version > 0 {
specificversion = true
} else {
lp.version = 1
}
var hops uint32
if lp.Limit == 0 {
lp.Limit = h.queryMaxPeriods
}
log.Trace("resource lookup", "period", lp.period, "version", lp.version, "limit", lp.Limit)
for lp.period > 0 {
if lp.Limit != 0 && hops > lp.Limit {
return nil, NewErrorf(ErrPeriodDepth, "Lookup exceeded max period hops (%d)", lp.Limit)
}
updateAddr := lp.UpdateAddr()
chunk, err := h.chunkStore.GetWithTimeout(context.TODO(), updateAddr, defaultRetrieveTimeout)
if err == nil {
if specificversion {
return h.updateIndex(rsrc, chunk)
}
// check if we have versions > 1. If a version fails, the previous version is used and returned.
log.Trace("rsrc update version 1 found, checking for version updates", "period", lp.period, "updateAddr", updateAddr)
for {
newversion := lp.version + 1
updateAddr := lp.UpdateAddr()
newchunk, err := h.chunkStore.GetWithTimeout(context.TODO(), updateAddr, defaultRetrieveTimeout)
if err != nil {
return h.updateIndex(rsrc, chunk)
}
chunk = newchunk
lp.version = newversion
log.Trace("version update found, checking next", "version", lp.version, "period", lp.period, "updateAddr", updateAddr)
}
}
if specificperiod {
break
}
log.Trace("rsrc update not found, checking previous period", "period", lp.period, "updateAddr", updateAddr)
lp.period--
hops++
}
return nil, NewError(ErrNotFound, "no updates found")
}
// Load retrieves the Mutable Resource metadata chunk stored at rootAddr
// Upon retrieval it creates/updates the index entry for it with metadata corresponding to the chunk contents
func (h *Handler) Load(ctx context.Context, rootAddr storage.Address) (*resource, error) {
chunk, err := h.chunkStore.GetWithTimeout(ctx, rootAddr, defaultRetrieveTimeout)
if err != nil {
return nil, NewError(ErrNotFound, err.Error())
}
// create the index entry
rsrc := &resource{}
if err := rsrc.ResourceMetadata.binaryGet(chunk.SData); err != nil { // Will fail if this is not really a metadata chunk
return nil, err
}
rsrc.rootAddr, rsrc.metaHash = metadataHash(chunk.SData)
if !bytes.Equal(rsrc.rootAddr, rootAddr) {
return nil, NewError(ErrCorruptData, "Corrupt metadata chunk")
}
h.set(rootAddr, rsrc)
log.Trace("resource index load", "rootkey", rootAddr, "name", rsrc.ResourceMetadata.Name, "starttime", rsrc.ResourceMetadata.StartTime, "frequency", rsrc.ResourceMetadata.Frequency)
return rsrc, nil
}
// update mutable resource index map with specified content
func (h *Handler) updateIndex(rsrc *resource, chunk *storage.Chunk) (*resource, error) {
// retrieve metadata from chunk data and check that it matches this mutable resource
var r SignedResourceUpdate
if err := r.fromChunk(chunk.Addr, chunk.SData); err != nil {
return nil, err
}
log.Trace("resource index update", "name", rsrc.ResourceMetadata.Name, "updatekey", chunk.Addr, "period", r.period, "version", r.version)
// update our rsrcs entry map
rsrc.lastKey = chunk.Addr
rsrc.period = r.period
rsrc.version = r.version
rsrc.updated = time.Now()
rsrc.data = make([]byte, len(r.data))
rsrc.multihash = r.multihash
copy(rsrc.data, r.data)
rsrc.Reader = bytes.NewReader(rsrc.data)
log.Debug("resource synced", "name", rsrc.ResourceMetadata.Name, "updateAddr", chunk.Addr, "period", rsrc.period, "version", rsrc.version)
h.set(chunk.Addr, rsrc)
return rsrc, nil
}
// Update adds an actual data update
// Uses the Mutable Resource metadata currently loaded in the resources map entry.
// It is the caller's responsibility to make sure that this data is not stale.
// Note that a Mutable Resource update cannot span chunks, and thus has a MAX NET LENGTH 4096, INCLUDING update header data and signature. An error will be returned if the total length of the chunk payload will exceed this limit.
// Update can only check if the caller is trying to overwrite the very last known version, otherwise it just puts the update
// on the network.
func (h *Handler) Update(ctx context.Context, r *SignedResourceUpdate) (storage.Address, error) {
return h.update(ctx, r)
}
// create and commit an update
func (h *Handler) update(ctx context.Context, r *SignedResourceUpdate) (updateAddr storage.Address, err error) {
// we can't update anything without a store
if h.chunkStore == nil {
return nil, NewError(ErrInit, "Call Handler.SetStore() before updating")
}
rsrc := h.get(r.rootAddr)
if rsrc != nil && rsrc.period != 0 && rsrc.version != 0 && // This is the only cheap check we can do for sure
rsrc.period == r.period && rsrc.version >= r.version { // without having to lookup update chunks
return nil, NewError(ErrInvalidValue, "A former update in this period is already known to exist")
}
chunk, err := r.toChunk() // Serialize the update into a chunk. Fails if data is too big
if err != nil {
return nil, err
}
// send the chunk
h.chunkStore.Put(ctx, chunk)
log.Trace("resource update", "updateAddr", r.updateAddr, "lastperiod", r.period, "version", r.version, "data", chunk.SData, "multihash", r.multihash)
// update our resources map entry if the new update is older than the one we have, if we have it.
if rsrc != nil && (r.period > rsrc.period || (rsrc.period == r.period && r.version > rsrc.version)) {
rsrc.period = r.period
rsrc.version = r.version
rsrc.data = make([]byte, len(r.data))
rsrc.updated = time.Now()
rsrc.lastKey = r.updateAddr
rsrc.multihash = r.multihash
copy(rsrc.data, r.data)
rsrc.Reader = bytes.NewReader(rsrc.data)
}
return r.updateAddr, nil
}
// Retrieves the resource index value for the given nameHash
func (h *Handler) get(rootAddr storage.Address) *resource {
if len(rootAddr) < storage.KeyLength {
log.Warn("Handler.get with invalid rootAddr")
return nil
}
hashKey := *(*uint64)(unsafe.Pointer(&rootAddr[0]))
h.resourceLock.RLock()
defer h.resourceLock.RUnlock()
rsrc := h.resources[hashKey]
return rsrc
}
// Sets the resource index value for the given nameHash
func (h *Handler) set(rootAddr storage.Address, rsrc *resource) {
if len(rootAddr) < storage.KeyLength {
log.Warn("Handler.set with invalid rootAddr")
return
}
hashKey := *(*uint64)(unsafe.Pointer(&rootAddr[0]))
h.resourceLock.Lock()
defer h.resourceLock.Unlock()
h.resources[hashKey] = rsrc
}
// Checks if we already have an update on this resource, according to the value in the current state of the resource index
func (h *Handler) hasUpdate(rootAddr storage.Address, period uint32) bool {
rsrc := h.get(rootAddr)
return rsrc != nil && rsrc.period == period
}
