neo-go/pkg/services/notary/notary.go
2022-06-01 15:03:29 +03:00

520 lines
17 KiB
Go

package notary
import (
"bytes"
"crypto/elliptic"
"encoding/hex"
"errors"
"fmt"
"sync"
"github.com/nspcc-dev/neo-go/pkg/config"
"github.com/nspcc-dev/neo-go/pkg/config/netmode"
"github.com/nspcc-dev/neo-go/pkg/core/block"
"github.com/nspcc-dev/neo-go/pkg/core/mempool"
"github.com/nspcc-dev/neo-go/pkg/core/mempoolevent"
"github.com/nspcc-dev/neo-go/pkg/core/transaction"
"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
"github.com/nspcc-dev/neo-go/pkg/io"
"github.com/nspcc-dev/neo-go/pkg/network/payload"
"github.com/nspcc-dev/neo-go/pkg/util"
"github.com/nspcc-dev/neo-go/pkg/vm"
"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
"github.com/nspcc-dev/neo-go/pkg/wallet"
"go.uber.org/zap"
)
type (
// Ledger is the interface to Blockchain sufficient for Notary.
Ledger interface {
BlockHeight() uint32
GetMaxVerificationGAS() int64
GetNotaryContractScriptHash() util.Uint160
SubscribeForBlocks(ch chan<- *block.Block)
UnsubscribeFromBlocks(ch chan<- *block.Block)
VerifyWitness(util.Uint160, hash.Hashable, *transaction.Witness, int64) (int64, error)
}
// Notary represents a Notary module.
Notary struct {
Config Config
Network netmode.Magic
// onTransaction is a callback for completed transactions (mains or fallbacks) sending.
onTransaction func(tx *transaction.Transaction) error
// newTxs is a channel where new transactions are sent
// to be processed in an `onTransaction` callback.
newTxs chan txHashPair
// reqMtx protects requests list.
reqMtx sync.RWMutex
// requests represents a map of main transactions which needs to be completed
// with the associated fallback transactions grouped by the main transaction hash
requests map[util.Uint256]*request
// accMtx protects account.
accMtx sync.RWMutex
currAccount *wallet.Account
wallet *wallet.Wallet
mp *mempool.Pool
// requests channel
reqCh chan mempoolevent.Event
blocksCh chan *block.Block
stopCh chan struct{}
}
// Config represents external configuration for Notary module.
Config struct {
MainCfg config.P2PNotary
Chain Ledger
Log *zap.Logger
}
)
const defaultTxChannelCapacity = 100
type (
// request represents Notary service request.
request struct {
// isSent indicates whether the main transaction was successfully sent to the network.
isSent bool
main *transaction.Transaction
// minNotValidBefore is the minimum NVB value among fallbacks transactions.
// We stop trying to send the mainTx to the network if the chain reaches the minNotValidBefore height.
minNotValidBefore uint32
fallbacks []*transaction.Transaction
witnessInfo []witnessInfo
}
// witnessInfo represents information about the signer and its witness.
witnessInfo struct {
typ RequestType
// nSigsLeft is the number of signatures left to collect to complete the main transaction.
// Initial nSigsLeft value is defined as following:
// nSigsLeft == nKeys for standard signature request;
// nSigsLeft <= nKeys for multisignature request;
nSigsLeft uint8
// sigs is a map of partial multisig invocation scripts [opcode.PUSHDATA1+64+signatureBytes] grouped by public keys.
sigs map[*keys.PublicKey][]byte
// pubs is a set of public keys participating in the multisignature witness collection.
pubs keys.PublicKeys
}
)
// isMainCompleted denotes whether all signatures for the main transaction were collected.
func (r request) isMainCompleted() bool {
if r.witnessInfo == nil {
return false
}
for _, wi := range r.witnessInfo {
if wi.nSigsLeft != 0 {
return false
}
}
return true
}
// NewNotary returns a new Notary module.
func NewNotary(cfg Config, net netmode.Magic, mp *mempool.Pool, onTransaction func(tx *transaction.Transaction) error) (*Notary, error) {
w := cfg.MainCfg.UnlockWallet
wallet, err := wallet.NewWalletFromFile(w.Path)
if err != nil {
return nil, err
}
haveAccount := false
for _, acc := range wallet.Accounts {
if err := acc.Decrypt(w.Password, wallet.Scrypt); err == nil {
haveAccount = true
break
}
}
if !haveAccount {
return nil, errors.New("no wallet account could be unlocked")
}
return &Notary{
requests: make(map[util.Uint256]*request),
Config: cfg,
Network: net,
wallet: wallet,
onTransaction: onTransaction,
newTxs: make(chan txHashPair, defaultTxChannelCapacity),
mp: mp,
reqCh: make(chan mempoolevent.Event),
blocksCh: make(chan *block.Block),
stopCh: make(chan struct{}),
}, nil
}
// Name returns service name.
func (n *Notary) Name() string {
return "notary"
}
// Start runs a Notary module in a separate goroutine.
func (n *Notary) Start() {
n.Config.Log.Info("starting notary service")
n.Config.Chain.SubscribeForBlocks(n.blocksCh)
n.mp.SubscribeForTransactions(n.reqCh)
go n.newTxCallbackLoop()
go n.mainLoop()
}
func (n *Notary) mainLoop() {
for {
select {
case <-n.stopCh:
n.mp.UnsubscribeFromTransactions(n.reqCh)
n.Config.Chain.UnsubscribeFromBlocks(n.blocksCh)
return
case event := <-n.reqCh:
if req, ok := event.Data.(*payload.P2PNotaryRequest); ok {
switch event.Type {
case mempoolevent.TransactionAdded:
n.OnNewRequest(req)
case mempoolevent.TransactionRemoved:
n.OnRequestRemoval(req)
}
}
case <-n.blocksCh:
// a new block was added, we need to check for valid fallbacks
n.PostPersist()
}
}
}
// Shutdown stops the Notary module.
func (n *Notary) Shutdown() {
close(n.stopCh)
}
// OnNewRequest is a callback method which is called after a new notary request is added to the notary request pool.
func (n *Notary) OnNewRequest(payload *payload.P2PNotaryRequest) {
acc := n.getAccount()
if acc == nil {
return
}
nvbFallback := payload.FallbackTransaction.GetAttributes(transaction.NotValidBeforeT)[0].Value.(*transaction.NotValidBefore).Height
nKeys := payload.MainTransaction.GetAttributes(transaction.NotaryAssistedT)[0].Value.(*transaction.NotaryAssisted).NKeys
newInfo, validationErr := n.verifyIncompleteWitnesses(payload.MainTransaction, nKeys)
if validationErr != nil {
n.Config.Log.Info("verification of main notary transaction failed; fallback transaction will be completed",
zap.String("main hash", payload.MainTransaction.Hash().StringLE()),
zap.String("fallback hash", payload.FallbackTransaction.Hash().StringLE()),
zap.String("verification error", validationErr.Error()))
}
n.reqMtx.Lock()
defer n.reqMtx.Unlock()
r, exists := n.requests[payload.MainTransaction.Hash()]
if exists {
for _, fb := range r.fallbacks {
if fb.Hash().Equals(payload.FallbackTransaction.Hash()) {
return // then we already have processed this request
}
}
if nvbFallback < r.minNotValidBefore {
r.minNotValidBefore = nvbFallback
}
} else {
// Avoid changes in the main transaction witnesses got from the notary request pool to
// keep the pooled tx valid. We will update its copy => the copy's size will be changed.
cp := *payload.MainTransaction
cp.Scripts = make([]transaction.Witness, len(payload.MainTransaction.Scripts))
copy(cp.Scripts, payload.MainTransaction.Scripts)
r = &request{
main: &cp,
minNotValidBefore: nvbFallback,
}
n.requests[payload.MainTransaction.Hash()] = r
}
if r.witnessInfo == nil && validationErr == nil {
r.witnessInfo = newInfo
}
// Allow modification of a fallback transaction got from the notary request pool.
// It has dummy Notary witness attached => its size won't be changed.
r.fallbacks = append(r.fallbacks, payload.FallbackTransaction)
if exists && r.isMainCompleted() || validationErr != nil {
return
}
mainHash := hash.NetSha256(uint32(n.Network), r.main).BytesBE()
for i, w := range payload.MainTransaction.Scripts {
if len(w.InvocationScript) == 0 || // check that signature for this witness was provided
(r.witnessInfo[i].nSigsLeft == 0 && r.witnessInfo[i].typ != Contract) { // check that signature wasn't yet added (consider receiving the same payload multiple times)
continue
}
switch r.witnessInfo[i].typ {
case Contract:
// Need to check even if r.main.Scripts[i].InvocationScript is already filled in.
_, err := n.Config.Chain.VerifyWitness(r.main.Signers[i].Account, r.main, &w, n.Config.Chain.GetMaxVerificationGAS())
if err != nil {
continue
}
r.main.Scripts[i].InvocationScript = w.InvocationScript
case Signature:
if r.witnessInfo[i].pubs[0].Verify(w.InvocationScript[2:], mainHash) {
r.main.Scripts[i] = w
r.witnessInfo[i].nSigsLeft--
}
case MultiSignature:
if r.witnessInfo[i].sigs == nil {
r.witnessInfo[i].sigs = make(map[*keys.PublicKey][]byte)
}
for _, pub := range r.witnessInfo[i].pubs {
if r.witnessInfo[i].sigs[pub] != nil {
continue // signature for this pub has already been added
}
if pub.Verify(w.InvocationScript[2:], mainHash) { // then pub is the owner of the signature
r.witnessInfo[i].sigs[pub] = w.InvocationScript
r.witnessInfo[i].nSigsLeft--
if r.witnessInfo[i].nSigsLeft == 0 {
var invScript []byte
for j := range r.witnessInfo[i].pubs {
if sig, ok := r.witnessInfo[i].sigs[r.witnessInfo[i].pubs[j]]; ok {
invScript = append(invScript, sig...)
}
}
r.main.Scripts[i].InvocationScript = invScript
}
break
}
}
// pubKey was not found for the signature (i.e. signature is bad) or the signature has already
// been added - we're OK with that, let the fallback TX to be added
}
}
if r.isMainCompleted() && r.minNotValidBefore > n.Config.Chain.BlockHeight() {
if err := n.finalize(acc, r.main, payload.MainTransaction.Hash()); err != nil {
n.Config.Log.Error("failed to finalize main transaction",
zap.String("hash", r.main.Hash().StringLE()),
zap.Error(err))
}
}
}
// OnRequestRemoval is a callback which is called after fallback transaction is removed
// from the notary payload pool due to expiration, main tx appliance or any other reason.
func (n *Notary) OnRequestRemoval(pld *payload.P2PNotaryRequest) {
if n.getAccount() == nil {
return
}
n.reqMtx.Lock()
defer n.reqMtx.Unlock()
r, ok := n.requests[pld.MainTransaction.Hash()]
if !ok {
return
}
for i, fb := range r.fallbacks {
if fb.Hash().Equals(pld.FallbackTransaction.Hash()) {
r.fallbacks = append(r.fallbacks[:i], r.fallbacks[i+1:]...)
break
}
}
if len(r.fallbacks) == 0 {
delete(n.requests, r.main.Hash())
}
}
// PostPersist is a callback which is called after a new block event is received.
// PostPersist must not be called under the blockchain lock, because it uses finalization function.
func (n *Notary) PostPersist() {
acc := n.getAccount()
if acc == nil {
return
}
n.reqMtx.Lock()
defer n.reqMtx.Unlock()
currHeight := n.Config.Chain.BlockHeight()
for h, r := range n.requests {
if !r.isSent && r.isMainCompleted() && r.minNotValidBefore > currHeight {
if err := n.finalize(acc, r.main, h); err != nil {
n.Config.Log.Error("failed to finalize main transaction", zap.Error(err))
}
continue
}
if r.minNotValidBefore <= currHeight { // then at least one of the fallbacks can already be sent.
for _, fb := range r.fallbacks {
if nvb := fb.GetAttributes(transaction.NotValidBeforeT)[0].Value.(*transaction.NotValidBefore).Height; nvb <= currHeight {
// Ignore the error, wait for the next block to resend them
_ = n.finalize(acc, fb, h)
}
}
}
}
}
// finalize adds missing Notary witnesses to the transaction (main or fallback) and pushes it to the network.
func (n *Notary) finalize(acc *wallet.Account, tx *transaction.Transaction, h util.Uint256) error {
notaryWitness := transaction.Witness{
InvocationScript: append([]byte{byte(opcode.PUSHDATA1), 64}, acc.PrivateKey().SignHashable(uint32(n.Network), tx)...),
VerificationScript: []byte{},
}
for i, signer := range tx.Signers {
if signer.Account == n.Config.Chain.GetNotaryContractScriptHash() {
tx.Scripts[i] = notaryWitness
break
}
}
newTx, err := updateTxSize(tx)
if err != nil {
return fmt.Errorf("failed to update completed transaction's size: %w", err)
}
n.pushNewTx(newTx, h)
return nil
}
type txHashPair struct {
tx *transaction.Transaction
mainHash util.Uint256
}
func (n *Notary) pushNewTx(tx *transaction.Transaction, h util.Uint256) {
select {
case n.newTxs <- txHashPair{tx, h}:
default:
}
}
func (n *Notary) newTxCallbackLoop() {
for {
select {
case tx := <-n.newTxs:
isMain := tx.tx.Hash() == tx.mainHash
n.reqMtx.Lock()
r, ok := n.requests[tx.mainHash]
if !ok || isMain && (r.isSent || r.minNotValidBefore <= n.Config.Chain.BlockHeight()) {
n.reqMtx.Unlock()
continue
}
if !isMain {
// Ensure that fallback was not already completed.
var isPending bool
for _, fb := range r.fallbacks {
if fb.Hash() == tx.tx.Hash() {
isPending = true
break
}
}
if !isPending {
n.reqMtx.Unlock()
continue
}
}
n.reqMtx.Unlock()
err := n.onTransaction(tx.tx)
if err != nil {
n.Config.Log.Error("new transaction callback finished with error", zap.Error(err))
continue
}
n.reqMtx.Lock()
if isMain {
r.isSent = true
} else {
for i := range r.fallbacks {
if r.fallbacks[i].Hash() == tx.tx.Hash() {
r.fallbacks = append(r.fallbacks[:i], r.fallbacks[i+1:]...)
break
}
}
if len(r.fallbacks) == 0 {
delete(n.requests, tx.mainHash)
}
}
n.reqMtx.Unlock()
case <-n.stopCh:
return
}
}
}
// updateTxSize returns a transaction with re-calculated size and an error.
func updateTxSize(tx *transaction.Transaction) (*transaction.Transaction, error) {
bw := io.NewBufBinWriter()
tx.EncodeBinary(bw.BinWriter)
if bw.Err != nil {
return nil, fmt.Errorf("encode binary: %w", bw.Err)
}
return transaction.NewTransactionFromBytes(tx.Bytes())
}
// verifyIncompleteWitnesses checks that the tx either doesn't have all witnesses attached (in this case none of them
// can be multisignature) or it only has a partial multisignature. It returns the request type (sig/multisig), the
// number of signatures to be collected, sorted public keys (for multisig request only) and an error.
func (n *Notary) verifyIncompleteWitnesses(tx *transaction.Transaction, nKeysExpected uint8) ([]witnessInfo, error) {
var nKeysActual uint8
if len(tx.Signers) < 2 {
return nil, errors.New("transaction should have at least 2 signers")
}
if !tx.HasSigner(n.Config.Chain.GetNotaryContractScriptHash()) {
return nil, fmt.Errorf("P2PNotary contract should be a signer of the transaction")
}
result := make([]witnessInfo, len(tx.Signers))
for i, w := range tx.Scripts {
// Do not check witness for a Notary contract -- it will be replaced by proper witness in any case.
// Also, do not check other contract-based witnesses (they can be combined with anything)
if len(w.VerificationScript) == 0 {
result[i] = witnessInfo{
typ: Contract,
nSigsLeft: 0,
}
continue
}
if !tx.Signers[i].Account.Equals(hash.Hash160(w.VerificationScript)) { // https://github.com/nspcc-dev/neo-go/pull/1658#discussion_r564265987
return nil, fmt.Errorf("transaction should have valid verification script for signer #%d", i)
}
// Each verification script is allowed to have either one signature or zero signatures. If signature is provided, then need to verify it.
if len(w.InvocationScript) != 0 {
if len(w.InvocationScript) != 66 || !bytes.HasPrefix(w.InvocationScript, []byte{byte(opcode.PUSHDATA1), 64}) {
return nil, fmt.Errorf("witness #%d: invocation script should have length = 66 and be of the form [PUSHDATA1, 64, signatureBytes...]", i)
}
}
if nSigs, pubsBytes, ok := vm.ParseMultiSigContract(w.VerificationScript); ok {
result[i] = witnessInfo{
typ: MultiSignature,
nSigsLeft: uint8(nSigs),
pubs: make(keys.PublicKeys, len(pubsBytes)),
}
for j, pBytes := range pubsBytes {
pub, err := keys.NewPublicKeyFromBytes(pBytes, elliptic.P256())
if err != nil {
return nil, fmt.Errorf("witness #%d: invalid bytes of #%d public key: %s", i, j, hex.EncodeToString(pBytes))
}
result[i].pubs[j] = pub
}
nKeysActual += uint8(len(pubsBytes))
continue
}
if pBytes, ok := vm.ParseSignatureContract(w.VerificationScript); ok {
pub, err := keys.NewPublicKeyFromBytes(pBytes, elliptic.P256())
if err != nil {
return nil, fmt.Errorf("witness #%d: invalid bytes of public key: %s", i, hex.EncodeToString(pBytes))
}
result[i] = witnessInfo{
typ: Signature,
nSigsLeft: 1,
pubs: keys.PublicKeys{pub},
}
nKeysActual++
continue
}
return nil, fmt.Errorf("witness #%d: unable to detect witness type, only sig/multisig/contract are supported", i)
}
if nKeysActual != nKeysExpected {
return nil, fmt.Errorf("expected and actual NKeys mismatch: %d vs %d", nKeysExpected, nKeysActual)
}
return result, nil
}