neoneo-go/pkg/services/notary/notary.go

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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"
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"github.com/nspcc-dev/neo-go/pkg/core/block"
"github.com/nspcc-dev/neo-go/pkg/core/blockchainer"
"github.com/nspcc-dev/neo-go/pkg/core/mempool"
"github.com/nspcc-dev/neo-go/pkg/core/mempoolevent"
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"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"
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"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 (
// Notary represents Notary module.
Notary struct {
Config Config
Network netmode.Magic
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// onTransaction is a callback for completed transactions (mains or fallbacks) sending.
onTransaction func(tx *transaction.Transaction) error
// reqMtx protects requests list.
reqMtx sync.RWMutex
// requests represents the 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
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mp *mempool.Pool
// requests channel
reqCh chan mempoolevent.Event
blocksCh chan *block.Block
stopCh chan struct{}
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}
// Config represents external configuration for Notary module.
Config struct {
MainCfg config.P2PNotary
Chain blockchainer.Blockchainer
Log *zap.Logger
}
)
// request represents Notary service request.
type request struct {
typ RequestType
// isSent indicates whether 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 mainTx to the network if the chain reaches minNotValidBefore height.
minNotValidBefore uint32
fallbacks []*transaction.Transaction
// nSigs is the number of signatures to be collected.
// nSigs == nKeys for standard signature request;
// nSigs <= nKeys for multisignature request.
// nSigs is 0 when all received requests were invalid, so check request.typ before access to nSigs.
nSigs uint8
// nSigsCollected is the number of already collected signatures
nSigsCollected uint8
// sigs is a map of partial multisig invocation scripts [opcode.PUSHDATA1+64+signatureBytes] grouped by public keys
sigs map[*keys.PublicKey][]byte
}
// NewNotary returns 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
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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 {
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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,
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wallet: wallet,
onTransaction: onTransaction,
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mp: mp,
reqCh: make(chan mempoolevent.Event),
blocksCh: make(chan *block.Block),
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stopCh: make(chan struct{}),
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}, nil
}
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// Run runs Notary module and should be called in a separate goroutine.
func (n *Notary) Run() {
n.Config.Log.Info("starting notary service")
n.Config.Chain.SubscribeForBlocks(n.blocksCh)
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n.mp.SubscribeForTransactions(n.reqCh)
for {
select {
case <-n.stopCh:
n.mp.UnsubscribeFromTransactions(n.reqCh)
n.Config.Chain.UnsubscribeFromBlocks(n.blocksCh)
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return
case event := <-n.reqCh:
if req, ok := event.Data.(*payload.P2PNotaryRequest); ok {
switch event.Type {
case mempoolevent.TransactionAdded:
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n.OnNewRequest(req)
case mempoolevent.TransactionRemoved:
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n.OnRequestRemoval(req)
}
}
case <-n.blocksCh:
// new block was added, need to check for valid fallbacks
n.PostPersist()
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}
}
}
// Stop shutdowns Notary module.
func (n *Notary) Stop() {
close(n.stopCh)
}
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// OnNewRequest is a callback method which is called after new notary request is added to the notary request pool.
func (n *Notary) OnNewRequest(payload *payload.P2PNotaryRequest) {
if n.getAccount() == nil {
return
}
nvbFallback := payload.FallbackTransaction.GetAttributes(transaction.NotValidBeforeT)[0].Value.(*transaction.NotValidBefore).Height
nKeys := payload.MainTransaction.GetAttributes(transaction.NotaryAssistedT)[0].Value.(*transaction.NotaryAssisted).NKeys
typ, nSigs, pubs, validationErr := n.verifyIncompleteWitnesses(payload.MainTransaction, nKeys)
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
}
if r.typ == Unknown && validationErr == nil {
r.typ = typ
r.nSigs = nSigs
}
} else {
r = &request{
nSigs: nSigs,
main: payload.MainTransaction,
typ: typ,
minNotValidBefore: nvbFallback,
}
n.requests[payload.MainTransaction.Hash()] = r
}
r.fallbacks = append(r.fallbacks, payload.FallbackTransaction)
if exists && r.typ != Unknown && r.nSigsCollected >= r.nSigs { // already collected sufficient number of signatures to complete main transaction
return
}
if validationErr == nil {
loop:
for i, w := range payload.MainTransaction.Scripts {
if payload.MainTransaction.Signers[i].Account.Equals(n.Config.Chain.GetNotaryContractScriptHash()) {
continue
}
if len(w.InvocationScript) != 0 && len(w.VerificationScript) != 0 {
switch r.typ {
case Signature:
if !exists {
r.nSigsCollected++
} else if len(r.main.Scripts[i].InvocationScript) == 0 { // need this check because signature can already be added (consider receiving the same payload multiple times)
r.main.Scripts[i] = w
r.nSigsCollected++
}
if r.nSigsCollected == r.nSigs {
break loop
}
case MultiSignature:
if r.sigs == nil {
r.sigs = make(map[*keys.PublicKey][]byte)
}
hash := hash.NetSha256(uint32(n.Network), r.main).BytesBE()
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for _, pub := range pubs {
if r.sigs[pub] != nil {
continue // signature for this pub has already been added
}
if pub.Verify(w.InvocationScript[2:], hash) { // then pub is the owner of the signature
r.sigs[pub] = w.InvocationScript
r.nSigsCollected++
if r.nSigsCollected == r.nSigs {
var invScript []byte
for j := range pubs {
if sig, ok := r.sigs[pubs[j]]; ok {
invScript = append(invScript, sig...)
}
}
r.main.Scripts[i].InvocationScript = invScript
}
break loop
}
}
// pubKey was not found for the signature i.e. signature is bad - we're OK with that, let the fallback TX to be added
break loop // only one multisignature is allowed
}
}
}
}
if r.typ != Unknown && r.nSigsCollected == nSigs && r.minNotValidBefore > n.Config.Chain.BlockHeight() {
if err := n.finalize(r.main); err != nil {
n.Config.Log.Error("failed to finalize main transaction", zap.Error(err))
} else {
r.isSent = true
}
}
}
// 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 new block event is received.
// PostPersist must not be called under the blockchain lock, because it uses finalization function.
func (n *Notary) PostPersist() {
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if n.getAccount() == nil {
return
}
n.reqMtx.Lock()
defer n.reqMtx.Unlock()
currHeight := n.Config.Chain.BlockHeight()
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for h, r := range n.requests {
if !r.isSent && r.typ != Unknown && r.nSigs == r.nSigsCollected && r.minNotValidBefore > currHeight {
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if err := n.finalize(r.main); err != nil {
n.Config.Log.Error("failed to finalize main transaction", zap.Error(err))
} else {
r.isSent = true
}
continue
}
if r.minNotValidBefore <= currHeight { // then at least one of the fallbacks can already be sent.
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newFallbacks := r.fallbacks[:0]
for _, fb := range r.fallbacks {
if nvb := fb.GetAttributes(transaction.NotValidBeforeT)[0].Value.(*transaction.NotValidBefore).Height; nvb <= currHeight {
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if err := n.finalize(fb); err != nil {
newFallbacks = append(newFallbacks, fb) // wait for the next block to resend them
}
} else {
newFallbacks = append(newFallbacks, fb)
}
}
if len(newFallbacks) == 0 {
delete(n.requests, h)
} else {
r.fallbacks = newFallbacks
}
}
}
}
// finalize adds missing Notary witnesses to the transaction (main or fallback) and pushes it to the network.
func (n *Notary) finalize(tx *transaction.Transaction) error {
acc := n.getAccount()
if acc == nil {
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panic(errors.New("no available Notary account")) // unreachable code, because all callers of `finalize` check that acc != nil
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}
notaryWitness := transaction.Witness{
InvocationScript: append([]byte{byte(opcode.PUSHDATA1), 64}, acc.PrivateKey().SignHashable(uint32(n.Network), tx)...),
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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)
}
return n.onTransaction(newTx)
}
// updateTxSize returns 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())
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}
// verifyIncompleteWitnesses checks that 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, nKeys uint8) (RequestType, uint8, keys.PublicKeys, error) {
var (
typ RequestType
nSigs int
nKeysActual uint8
pubsBytes [][]byte
pubs keys.PublicKeys
ok bool
)
if len(tx.Signers) < 2 {
return Unknown, 0, nil, errors.New("transaction should have at least 2 signers")
}
if !tx.HasSigner(n.Config.Chain.GetNotaryContractScriptHash()) {
return Unknown, 0, nil, fmt.Errorf("P2PNotary contract should be a signer of the transaction")
}
for i, w := range tx.Scripts {
// do not check witness for Notary contract -- it will be replaced by proper witness in any case.
if tx.Signers[i].Account == n.Config.Chain.GetNotaryContractScriptHash() {
continue
}
if len(w.VerificationScript) == 0 {
// then it's a contract verification (can be combined with anything)
continue
}
if !tx.Signers[i].Account.Equals(hash.Hash160(w.VerificationScript)) { // https://github.com/nspcc-dev/neo-go/pull/1658#discussion_r564265987
return Unknown, 0, nil, fmt.Errorf("transaction should have valid verification script for signer #%d", i)
}
if nSigs, pubsBytes, ok = vm.ParseMultiSigContract(w.VerificationScript); ok {
if typ == Signature || typ == MultiSignature {
return Unknown, 0, nil, fmt.Errorf("bad type of witness #%d: only one multisignature witness is allowed", i)
}
typ = MultiSignature
nKeysActual = uint8(len(pubsBytes))
if len(w.InvocationScript) != 66 || !bytes.HasPrefix(w.InvocationScript, []byte{byte(opcode.PUSHDATA1), 64}) {
return Unknown, 0, nil, fmt.Errorf("multisignature invocation script should have length = 66 and be of the form [PUSHDATA1, 64, signatureBytes...]")
}
continue
}
if vm.IsSignatureContract(w.VerificationScript) {
if typ == MultiSignature {
return Unknown, 0, nil, fmt.Errorf("bad type of witness #%d: multisignature witness can not be combined with other witnesses", i)
}
typ = Signature
nSigs = int(nKeys)
continue
}
return Unknown, 0, nil, fmt.Errorf("unable to define the type of witness #%d", i)
}
switch typ {
case Signature:
if len(tx.Scripts) < int(nKeys+1) {
return Unknown, 0, nil, fmt.Errorf("transaction should comtain at least %d witnesses (1 for notary + nKeys)", nKeys+1)
}
case MultiSignature:
if nKeysActual != nKeys {
return Unknown, 0, nil, fmt.Errorf("bad m out of n partial multisignature witness: expected n = %d, got n = %d", nKeys, nKeysActual)
}
pubs = make(keys.PublicKeys, len(pubsBytes))
for i, pBytes := range pubsBytes {
pub, err := keys.NewPublicKeyFromBytes(pBytes, elliptic.P256())
if err != nil {
return Unknown, 0, nil, fmt.Errorf("invalid bytes of #%d public key: %s", i, hex.EncodeToString(pBytes))
}
pubs[i] = pub
}
default:
return Unknown, 0, nil, errors.New("unexpected Notary request type")
}
return typ, uint8(nSigs), pubs, nil
}