mirror of
https://github.com/nspcc-dev/neo-go.git
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417 lines
14 KiB
Go
417 lines
14 KiB
Go
package notary
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import (
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"bytes"
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"crypto/elliptic"
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"encoding/hex"
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"errors"
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"fmt"
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"sync"
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"github.com/nspcc-dev/neo-go/pkg/config"
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"github.com/nspcc-dev/neo-go/pkg/config/netmode"
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"github.com/nspcc-dev/neo-go/pkg/core/block"
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"github.com/nspcc-dev/neo-go/pkg/core/blockchainer"
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"github.com/nspcc-dev/neo-go/pkg/core/mempool"
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"github.com/nspcc-dev/neo-go/pkg/core/mempoolevent"
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"github.com/nspcc-dev/neo-go/pkg/core/transaction"
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"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
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"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
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"github.com/nspcc-dev/neo-go/pkg/io"
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"github.com/nspcc-dev/neo-go/pkg/network/payload"
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"github.com/nspcc-dev/neo-go/pkg/util"
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"github.com/nspcc-dev/neo-go/pkg/vm"
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"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
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"github.com/nspcc-dev/neo-go/pkg/wallet"
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"go.uber.org/zap"
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)
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type (
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// Notary represents Notary module.
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Notary struct {
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Config Config
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Network netmode.Magic
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// onTransaction is a callback for completed transactions (mains or fallbacks) sending.
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onTransaction func(tx *transaction.Transaction) error
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// reqMtx protects requests list.
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reqMtx sync.RWMutex
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// requests represents the map of main transactions which needs to be completed
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// with the associated fallback transactions grouped by the main transaction hash
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requests map[util.Uint256]*request
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// accMtx protects account.
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accMtx sync.RWMutex
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currAccount *wallet.Account
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wallet *wallet.Wallet
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mp *mempool.Pool
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// requests channel
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reqCh chan mempoolevent.Event
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blocksCh chan *block.Block
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stopCh chan struct{}
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}
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// Config represents external configuration for Notary module.
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Config struct {
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MainCfg config.P2PNotary
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Chain blockchainer.Blockchainer
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Log *zap.Logger
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}
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)
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// request represents Notary service request.
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type request struct {
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typ RequestType
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// isSent indicates whether main transaction was successfully sent to the network.
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isSent bool
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main *transaction.Transaction
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// minNotValidBefore is the minimum NVB value among fallbacks transactions.
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// We stop trying to send mainTx to the network if the chain reaches minNotValidBefore height.
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minNotValidBefore uint32
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fallbacks []*transaction.Transaction
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// nSigs is the number of signatures to be collected.
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// nSigs == nKeys for standard signature request;
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// nSigs <= nKeys for multisignature request.
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// nSigs is 0 when all received requests were invalid, so check request.typ before access to nSigs.
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nSigs uint8
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// nSigsCollected is the number of already collected signatures
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nSigsCollected uint8
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// sigs is a map of partial multisig invocation scripts [opcode.PUSHDATA1+64+signatureBytes] grouped by public keys
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sigs map[*keys.PublicKey][]byte
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}
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// NewNotary returns new Notary module.
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func NewNotary(cfg Config, net netmode.Magic, mp *mempool.Pool, onTransaction func(tx *transaction.Transaction) error) (*Notary, error) {
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w := cfg.MainCfg.UnlockWallet
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wallet, err := wallet.NewWalletFromFile(w.Path)
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if err != nil {
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return nil, err
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}
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haveAccount := false
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for _, acc := range wallet.Accounts {
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if err := acc.Decrypt(w.Password); err == nil {
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haveAccount = true
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break
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}
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}
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if !haveAccount {
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return nil, errors.New("no wallet account could be unlocked")
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}
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return &Notary{
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requests: make(map[util.Uint256]*request),
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Config: cfg,
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Network: net,
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wallet: wallet,
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onTransaction: onTransaction,
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mp: mp,
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reqCh: make(chan mempoolevent.Event),
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blocksCh: make(chan *block.Block),
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stopCh: make(chan struct{}),
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}, nil
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}
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// Run runs Notary module and should be called in a separate goroutine.
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func (n *Notary) Run() {
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n.Config.Log.Info("starting notary service")
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n.Config.Chain.SubscribeForBlocks(n.blocksCh)
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n.mp.SubscribeForTransactions(n.reqCh)
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for {
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select {
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case <-n.stopCh:
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n.mp.UnsubscribeFromTransactions(n.reqCh)
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n.Config.Chain.UnsubscribeFromBlocks(n.blocksCh)
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return
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case event := <-n.reqCh:
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if req, ok := event.Data.(*payload.P2PNotaryRequest); ok {
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switch event.Type {
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case mempoolevent.TransactionAdded:
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n.OnNewRequest(req)
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case mempoolevent.TransactionRemoved:
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n.OnRequestRemoval(req)
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}
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}
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case <-n.blocksCh:
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// new block was added, need to check for valid fallbacks
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n.PostPersist()
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}
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}
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}
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// Stop shutdowns Notary module.
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func (n *Notary) Stop() {
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close(n.stopCh)
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}
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// OnNewRequest is a callback method which is called after new notary request is added to the notary request pool.
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func (n *Notary) OnNewRequest(payload *payload.P2PNotaryRequest) {
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if n.getAccount() == nil {
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return
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}
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nvbFallback := payload.FallbackTransaction.GetAttributes(transaction.NotValidBeforeT)[0].Value.(*transaction.NotValidBefore).Height
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nKeys := payload.MainTransaction.GetAttributes(transaction.NotaryAssistedT)[0].Value.(*transaction.NotaryAssisted).NKeys
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typ, nSigs, pubs, validationErr := n.verifyIncompleteWitnesses(payload.MainTransaction, nKeys)
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n.reqMtx.Lock()
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defer n.reqMtx.Unlock()
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r, exists := n.requests[payload.MainTransaction.Hash()]
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if exists {
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for _, fb := range r.fallbacks {
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if fb.Hash().Equals(payload.FallbackTransaction.Hash()) {
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return // then we already have processed this request
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}
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}
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if nvbFallback < r.minNotValidBefore {
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r.minNotValidBefore = nvbFallback
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}
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if r.typ == Unknown && validationErr == nil {
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r.typ = typ
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r.nSigs = nSigs
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}
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} else {
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r = &request{
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nSigs: nSigs,
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main: payload.MainTransaction,
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typ: typ,
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minNotValidBefore: nvbFallback,
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}
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n.requests[payload.MainTransaction.Hash()] = r
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}
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r.fallbacks = append(r.fallbacks, payload.FallbackTransaction)
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if exists && r.typ != Unknown && r.nSigsCollected >= r.nSigs { // already collected sufficient number of signatures to complete main transaction
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return
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}
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if validationErr == nil {
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loop:
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for i, w := range payload.MainTransaction.Scripts {
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if payload.MainTransaction.Signers[i].Account.Equals(n.Config.Chain.GetNotaryContractScriptHash()) {
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continue
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}
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if len(w.InvocationScript) != 0 && len(w.VerificationScript) != 0 {
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switch r.typ {
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case Signature:
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if !exists {
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r.nSigsCollected++
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} 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)
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r.main.Scripts[i] = w
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r.nSigsCollected++
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}
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if r.nSigsCollected == r.nSigs {
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break loop
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}
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case MultiSignature:
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if r.sigs == nil {
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r.sigs = make(map[*keys.PublicKey][]byte)
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}
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hash := hash.NetSha256(uint32(n.Network), r.main).BytesBE()
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for _, pub := range pubs {
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if r.sigs[pub] != nil {
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continue // signature for this pub has already been added
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}
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if pub.Verify(w.InvocationScript[2:], hash) { // then pub is the owner of the signature
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r.sigs[pub] = w.InvocationScript
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r.nSigsCollected++
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if r.nSigsCollected == r.nSigs {
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var invScript []byte
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for j := range pubs {
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if sig, ok := r.sigs[pubs[j]]; ok {
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invScript = append(invScript, sig...)
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}
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}
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r.main.Scripts[i].InvocationScript = invScript
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}
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break loop
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}
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}
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// pubKey was not found for the signature i.e. signature is bad - we're OK with that, let the fallback TX to be added
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break loop // only one multisignature is allowed
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}
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}
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}
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}
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if r.typ != Unknown && r.nSigsCollected == nSigs && r.minNotValidBefore > n.Config.Chain.BlockHeight() {
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if err := n.finalize(r.main); err != nil {
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n.Config.Log.Error("failed to finalize main transaction", zap.Error(err))
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} else {
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r.isSent = true
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}
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}
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}
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// OnRequestRemoval is a callback which is called after fallback transaction is removed
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// from the notary payload pool due to expiration, main tx appliance or any other reason.
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func (n *Notary) OnRequestRemoval(pld *payload.P2PNotaryRequest) {
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if n.getAccount() == nil {
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return
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}
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n.reqMtx.Lock()
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defer n.reqMtx.Unlock()
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r, ok := n.requests[pld.MainTransaction.Hash()]
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if !ok {
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return
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}
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for i, fb := range r.fallbacks {
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if fb.Hash().Equals(pld.FallbackTransaction.Hash()) {
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r.fallbacks = append(r.fallbacks[:i], r.fallbacks[i+1:]...)
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break
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}
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}
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if len(r.fallbacks) == 0 {
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delete(n.requests, r.main.Hash())
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}
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}
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// PostPersist is a callback which is called after new block event is received.
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// PostPersist must not be called under the blockchain lock, because it uses finalization function.
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func (n *Notary) PostPersist() {
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if n.getAccount() == nil {
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return
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}
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n.reqMtx.Lock()
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defer n.reqMtx.Unlock()
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currHeight := n.Config.Chain.BlockHeight()
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for h, r := range n.requests {
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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 {
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n.Config.Log.Error("failed to finalize main transaction", zap.Error(err))
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} else {
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r.isSent = true
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}
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continue
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}
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if r.minNotValidBefore <= currHeight { // then at least one of the fallbacks can already be sent.
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newFallbacks := r.fallbacks[:0]
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for _, fb := range r.fallbacks {
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if nvb := fb.GetAttributes(transaction.NotValidBeforeT)[0].Value.(*transaction.NotValidBefore).Height; nvb <= currHeight {
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if err := n.finalize(fb); err != nil {
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newFallbacks = append(newFallbacks, fb) // wait for the next block to resend them
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}
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} else {
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newFallbacks = append(newFallbacks, fb)
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}
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}
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if len(newFallbacks) == 0 {
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delete(n.requests, h)
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} else {
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r.fallbacks = newFallbacks
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}
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}
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}
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}
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// finalize adds missing Notary witnesses to the transaction (main or fallback) and pushes it to the network.
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func (n *Notary) finalize(tx *transaction.Transaction) error {
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acc := n.getAccount()
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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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}
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notaryWitness := transaction.Witness{
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InvocationScript: append([]byte{byte(opcode.PUSHDATA1), 64}, acc.PrivateKey().SignHashable(uint32(n.Network), tx)...),
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VerificationScript: []byte{},
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}
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for i, signer := range tx.Signers {
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if signer.Account == n.Config.Chain.GetNotaryContractScriptHash() {
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tx.Scripts[i] = notaryWitness
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break
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}
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}
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newTx, err := updateTxSize(tx)
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if err != nil {
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return fmt.Errorf("failed to update completed transaction's size: %w", err)
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}
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return n.onTransaction(newTx)
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}
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// updateTxSize returns transaction with re-calculated size and an error.
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func updateTxSize(tx *transaction.Transaction) (*transaction.Transaction, error) {
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bw := io.NewBufBinWriter()
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tx.EncodeBinary(bw.BinWriter)
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if bw.Err != nil {
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return nil, fmt.Errorf("encode binary: %w", bw.Err)
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}
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return transaction.NewTransactionFromBytes(tx.Bytes())
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}
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// verifyIncompleteWitnesses checks that tx either doesn't have all witnesses attached (in this case none of them
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// can be multisignature), or it only has a partial multisignature. It returns the request type (sig/multisig), the
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// number of signatures to be collected, sorted public keys (for multisig request only) and an error.
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func (n *Notary) verifyIncompleteWitnesses(tx *transaction.Transaction, nKeys uint8) (RequestType, uint8, keys.PublicKeys, error) {
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var (
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typ RequestType
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nSigs int
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nKeysActual uint8
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pubsBytes [][]byte
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pubs keys.PublicKeys
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ok bool
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)
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if len(tx.Signers) < 2 {
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return Unknown, 0, nil, errors.New("transaction should have at least 2 signers")
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}
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if !tx.HasSigner(n.Config.Chain.GetNotaryContractScriptHash()) {
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return Unknown, 0, nil, fmt.Errorf("P2PNotary contract should be a signer of the transaction")
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}
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for i, w := range tx.Scripts {
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// do not check witness for Notary contract -- it will be replaced by proper witness in any case.
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if tx.Signers[i].Account == n.Config.Chain.GetNotaryContractScriptHash() {
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continue
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}
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if len(w.VerificationScript) == 0 {
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// then it's a contract verification (can be combined with anything)
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continue
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}
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if !tx.Signers[i].Account.Equals(hash.Hash160(w.VerificationScript)) { // https://github.com/nspcc-dev/neo-go/pull/1658#discussion_r564265987
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return Unknown, 0, nil, fmt.Errorf("transaction should have valid verification script for signer #%d", i)
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}
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if nSigs, pubsBytes, ok = vm.ParseMultiSigContract(w.VerificationScript); ok {
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if typ == Signature || typ == MultiSignature {
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return Unknown, 0, nil, fmt.Errorf("bad type of witness #%d: only one multisignature witness is allowed", i)
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}
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typ = MultiSignature
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nKeysActual = uint8(len(pubsBytes))
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if len(w.InvocationScript) != 66 || !bytes.HasPrefix(w.InvocationScript, []byte{byte(opcode.PUSHDATA1), 64}) {
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return Unknown, 0, nil, fmt.Errorf("multisignature invocation script should have length = 66 and be of the form [PUSHDATA1, 64, signatureBytes...]")
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}
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continue
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}
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if vm.IsSignatureContract(w.VerificationScript) {
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if typ == MultiSignature {
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return Unknown, 0, nil, fmt.Errorf("bad type of witness #%d: multisignature witness can not be combined with other witnesses", i)
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}
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typ = Signature
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nSigs = int(nKeys)
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continue
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}
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return Unknown, 0, nil, fmt.Errorf("unable to define the type of witness #%d", i)
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}
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switch typ {
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case Signature:
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if len(tx.Scripts) < int(nKeys+1) {
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return Unknown, 0, nil, fmt.Errorf("transaction should comtain at least %d witnesses (1 for notary + nKeys)", nKeys+1)
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}
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case MultiSignature:
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if nKeysActual != nKeys {
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return Unknown, 0, nil, fmt.Errorf("bad m out of n partial multisignature witness: expected n = %d, got n = %d", nKeys, nKeysActual)
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}
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pubs = make(keys.PublicKeys, len(pubsBytes))
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for i, pBytes := range pubsBytes {
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pub, err := keys.NewPublicKeyFromBytes(pBytes, elliptic.P256())
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if err != nil {
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return Unknown, 0, nil, fmt.Errorf("invalid bytes of #%d public key: %s", i, hex.EncodeToString(pBytes))
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}
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pubs[i] = pub
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}
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default:
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return Unknown, 0, nil, errors.New("unexpected Notary request type")
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}
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return typ, uint8(nSigs), pubs, nil
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}
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