neoneo-go/pkg/core/native/oracle.go

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package native
import (
"encoding/binary"
"errors"
"fmt"
"math"
"math/big"
"strings"
"sync/atomic"
"github.com/nspcc-dev/neo-go/pkg/core/blockchainer/services"
"github.com/nspcc-dev/neo-go/pkg/core/dao"
"github.com/nspcc-dev/neo-go/pkg/core/interop"
"github.com/nspcc-dev/neo-go/pkg/core/interop/contract"
"github.com/nspcc-dev/neo-go/pkg/core/interop/interopnames"
"github.com/nspcc-dev/neo-go/pkg/core/native/nativenames"
"github.com/nspcc-dev/neo-go/pkg/core/state"
"github.com/nspcc-dev/neo-go/pkg/core/storage"
"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/encoding/bigint"
"github.com/nspcc-dev/neo-go/pkg/io"
"github.com/nspcc-dev/neo-go/pkg/smartcontract"
"github.com/nspcc-dev/neo-go/pkg/smartcontract/callflag"
"github.com/nspcc-dev/neo-go/pkg/smartcontract/manifest"
"github.com/nspcc-dev/neo-go/pkg/util"
"github.com/nspcc-dev/neo-go/pkg/vm/emit"
"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
)
// Oracle represents Oracle native contract.
type Oracle struct {
interop.ContractMD
GAS *GAS
NEO *NEO
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Desig *Designate
oracleScript []byte
// Module is an oracle module capable of talking with the external world.
Module atomic.Value
// newRequests contains new requests created during current block.
newRequests map[uint64]*state.OracleRequest
}
const (
oracleContractID = -7
maxURLLength = 256
maxFilterLength = 128
maxCallbackLength = 32
maxUserDataLength = 512
// maxRequestsCount is the maximum number of requests per URL
maxRequestsCount = 256
oracleRequestPrice = 5000_0000
)
var (
prefixIDList = []byte{6}
prefixRequest = []byte{7}
prefixRequestID = []byte{9}
)
// Various validation errors.
var (
ErrBigArgument = errors.New("some of the arguments are invalid")
ErrInvalidWitness = errors.New("witness check failed")
ErrNotEnoughGas = errors.New("gas limit exceeded")
ErrRequestNotFound = errors.New("oracle request not found")
ErrResponseNotFound = errors.New("oracle response not found")
)
func newOracle() *Oracle {
o := &Oracle{ContractMD: *interop.NewContractMD(nativenames.Oracle, oracleContractID)}
w := io.NewBufBinWriter()
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emit.Opcodes(w.BinWriter, opcode.NEWARRAY0)
emit.Int(w.BinWriter, int64(callflag.All))
emit.String(w.BinWriter, "finish")
emit.Bytes(w.BinWriter, o.Hash.BytesBE())
emit.Syscall(w.BinWriter, interopnames.SystemContractCall)
o.oracleScript = w.Bytes()
desc := newDescriptor("request", smartcontract.VoidType,
manifest.NewParameter("url", smartcontract.StringType),
manifest.NewParameter("filter", smartcontract.StringType),
manifest.NewParameter("callback", smartcontract.StringType),
manifest.NewParameter("userData", smartcontract.AnyType),
manifest.NewParameter("gasForResponse", smartcontract.IntegerType))
md := newMethodAndPrice(o.request, oracleRequestPrice, callflag.States|callflag.AllowNotify)
o.AddMethod(md, desc)
desc = newDescriptor("finish", smartcontract.VoidType)
md = newMethodAndPrice(o.finish, 0, callflag.States|callflag.AllowCall|callflag.AllowNotify)
o.AddMethod(md, desc)
desc = newDescriptor("verify", smartcontract.BoolType)
md = newMethodAndPrice(o.verify, 100_0000, callflag.NoneFlag)
o.AddMethod(md, desc)
o.AddEvent("OracleRequest", manifest.NewParameter("Id", smartcontract.IntegerType),
manifest.NewParameter("RequestContract", smartcontract.Hash160Type),
manifest.NewParameter("Url", smartcontract.StringType),
manifest.NewParameter("Filter", smartcontract.StringType))
o.AddEvent("OracleResponse", manifest.NewParameter("Id", smartcontract.IntegerType),
manifest.NewParameter("OriginalTx", smartcontract.Hash256Type))
return o
}
// GetOracleResponseScript returns script for transaction with oracle response.
func (o *Oracle) GetOracleResponseScript() []byte {
b := make([]byte, len(o.oracleScript))
copy(b, o.oracleScript)
return b
}
// OnPersist implements Contract interface.
func (o *Oracle) OnPersist(ic *interop.Context) error {
var err error
if o.newRequests == nil {
o.newRequests, err = o.getRequests(ic.DAO)
}
return err
}
// PostPersist represents `postPersist` method.
func (o *Oracle) PostPersist(ic *interop.Context) error {
var nodes keys.PublicKeys
var reward []big.Int
single := new(big.Int).SetUint64(oracleRequestPrice)
var removedIDs []uint64
orc, _ := o.Module.Load().(services.Oracle)
for _, tx := range ic.Block.Transactions {
resp := getResponse(tx)
if resp == nil {
continue
}
reqKey := makeRequestKey(resp.ID)
req := new(state.OracleRequest)
if err := o.getSerializableFromDAO(ic.DAO, reqKey, req); err != nil {
continue
}
if err := ic.DAO.DeleteStorageItem(o.ID, reqKey); err != nil {
return err
}
if orc != nil {
removedIDs = append(removedIDs, resp.ID)
}
idKey := makeIDListKey(req.URL)
idList := new(IDList)
if err := o.getSerializableFromDAO(ic.DAO, idKey, idList); err != nil {
return err
}
if !idList.Remove(resp.ID) {
return errors.New("response ID wasn't found")
}
var err error
if len(*idList) == 0 {
err = ic.DAO.DeleteStorageItem(o.ID, idKey)
} else {
si := &state.StorageItem{Value: idList.Bytes()}
err = ic.DAO.PutStorageItem(o.ID, idKey, si)
}
if err != nil {
return err
}
if nodes == nil {
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nodes, err = o.GetOracleNodes(ic.DAO)
if err != nil {
return err
}
reward = make([]big.Int, len(nodes))
}
if len(reward) > 0 {
index := resp.ID % uint64(len(nodes))
reward[index].Add(&reward[index], single)
}
}
for i := range reward {
o.GAS.mint(ic, nodes[i].GetScriptHash(), &reward[i], false)
}
if len(removedIDs) != 0 && orc != nil {
orc.RemoveRequests(removedIDs)
}
return o.updateCache(ic.DAO)
}
// Metadata returns contract metadata.
func (o *Oracle) Metadata() *interop.ContractMD {
return &o.ContractMD
}
// Initialize initializes Oracle contract.
func (o *Oracle) Initialize(ic *interop.Context) error {
return setIntWithKey(o.ID, ic.DAO, prefixRequestID, 0)
}
func getResponse(tx *transaction.Transaction) *transaction.OracleResponse {
for i := range tx.Attributes {
if tx.Attributes[i].Type == transaction.OracleResponseT {
return tx.Attributes[i].Value.(*transaction.OracleResponse)
}
}
return nil
}
func (o *Oracle) finish(ic *interop.Context, _ []stackitem.Item) stackitem.Item {
err := o.FinishInternal(ic)
if err != nil {
panic(err)
}
return stackitem.Null{}
}
// FinishInternal processes oracle response.
func (o *Oracle) FinishInternal(ic *interop.Context) error {
resp := getResponse(ic.Tx)
if resp == nil {
return ErrResponseNotFound
}
req, err := o.GetRequestInternal(ic.DAO, resp.ID)
if err != nil {
return ErrRequestNotFound
}
ic.Notifications = append(ic.Notifications, state.NotificationEvent{
ScriptHash: o.Hash,
Name: "OracleResponse",
Item: stackitem.NewArray([]stackitem.Item{
stackitem.Make(resp.ID),
stackitem.Make(req.OriginalTxID.BytesBE()),
}),
})
r := io.NewBinReaderFromBuf(req.UserData)
userData := stackitem.DecodeBinaryStackItem(r)
args := []stackitem.Item{
stackitem.Make(req.URL),
stackitem.Make(userData),
stackitem.Make(resp.Code),
stackitem.Make(resp.Result),
}
cs, err := ic.GetContract(req.CallbackContract)
if err != nil {
return err
}
return contract.CallFromNative(ic, o.Hash, cs, req.CallbackMethod, args, false)
}
func (o *Oracle) request(ic *interop.Context, args []stackitem.Item) stackitem.Item {
url, err := stackitem.ToString(args[0])
if err != nil {
panic(err)
}
var filter *string
_, ok := args[1].(stackitem.Null)
if !ok {
// Check UTF-8 validity.
str, err := stackitem.ToString(args[1])
if err != nil {
panic(err)
}
filter = &str
}
cb, err := stackitem.ToString(args[2])
if err != nil {
panic(err)
}
userData := args[3]
gas, err := args[4].TryInteger()
if err != nil {
panic(err)
}
if err := o.RequestInternal(ic, url, filter, cb, userData, gas); err != nil {
panic(err)
}
return stackitem.Null{}
}
// RequestInternal processes oracle request.
func (o *Oracle) RequestInternal(ic *interop.Context, url string, filter *string, cb string, userData stackitem.Item, gas *big.Int) error {
if len(url) > maxURLLength || (filter != nil && len(*filter) > maxFilterLength) || len(cb) > maxCallbackLength || gas.Uint64() < 1000_0000 {
return ErrBigArgument
}
if strings.HasPrefix(cb, "_") {
return errors.New("disallowed callback method (starts with '_')")
}
if !ic.VM.AddGas(gas.Int64()) {
return ErrNotEnoughGas
}
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callingHash := ic.VM.GetCallingScriptHash()
o.GAS.mint(ic, o.Hash, gas, false)
si := ic.DAO.GetStorageItem(o.ID, prefixRequestID)
itemID := bigint.FromBytes(si.Value)
id := itemID.Uint64()
itemID.Add(itemID, intOne)
si.Value = bigint.ToPreallocatedBytes(itemID, si.Value)
if err := ic.DAO.PutStorageItem(o.ID, prefixRequestID, si); err != nil {
return err
}
// Should be executed from contract.
_, err := ic.GetContract(ic.VM.GetCallingScriptHash())
if err != nil {
return err
}
w := io.NewBufBinWriter()
stackitem.EncodeBinaryStackItem(userData, w.BinWriter)
if w.Err != nil {
return w.Err
}
data := w.Bytes()
if len(data) > maxUserDataLength {
return ErrBigArgument
}
var filterNotif stackitem.Item
if filter != nil {
filterNotif = stackitem.Make(*filter)
} else {
filterNotif = stackitem.Null{}
}
ic.Notifications = append(ic.Notifications, state.NotificationEvent{
ScriptHash: o.Hash,
Name: "OracleRequest",
Item: stackitem.NewArray([]stackitem.Item{
stackitem.Make(id),
stackitem.Make(ic.VM.GetCallingScriptHash().BytesBE()),
stackitem.Make(url),
filterNotif,
}),
})
req := &state.OracleRequest{
OriginalTxID: o.getOriginalTxID(ic.DAO, ic.Tx),
GasForResponse: gas.Uint64(),
URL: url,
Filter: filter,
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CallbackContract: callingHash,
CallbackMethod: cb,
UserData: data,
}
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return o.PutRequestInternal(id, req, ic.DAO)
}
// PutRequestInternal puts oracle request with the specified id to d.
func (o *Oracle) PutRequestInternal(id uint64, req *state.OracleRequest, d dao.DAO) error {
reqItem := &state.StorageItem{Value: req.Bytes()}
reqKey := makeRequestKey(id)
if err := d.PutStorageItem(o.ID, reqKey, reqItem); err != nil {
return err
}
o.newRequests[id] = req
// Add request ID to the id list.
lst := new(IDList)
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key := makeIDListKey(req.URL)
if err := o.getSerializableFromDAO(d, key, lst); err != nil && !errors.Is(err, storage.ErrKeyNotFound) {
return err
}
if len(*lst) >= maxRequestsCount {
return fmt.Errorf("there are too many pending requests for %s url", req.URL)
}
*lst = append(*lst, id)
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si := &state.StorageItem{Value: lst.Bytes()}
return d.PutStorageItem(o.ID, key, si)
}
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// GetScriptHash returns script hash or oracle nodes.
func (o *Oracle) GetScriptHash(d dao.DAO) (util.Uint160, error) {
return o.Desig.GetLastDesignatedHash(d, RoleOracle)
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}
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// GetOracleNodes returns public keys of oracle nodes.
func (o *Oracle) GetOracleNodes(d dao.DAO) (keys.PublicKeys, error) {
nodes, _, err := o.Desig.GetDesignatedByRole(d, RoleOracle, math.MaxUint32)
return nodes, err
}
// GetRequestInternal returns request by ID and key under which it is stored.
func (o *Oracle) GetRequestInternal(d dao.DAO, id uint64) (*state.OracleRequest, error) {
key := makeRequestKey(id)
req := new(state.OracleRequest)
return req, o.getSerializableFromDAO(d, key, req)
}
// GetIDListInternal returns request by ID and key under which it is stored.
func (o *Oracle) GetIDListInternal(d dao.DAO, url string) (*IDList, error) {
key := makeIDListKey(url)
idList := new(IDList)
return idList, o.getSerializableFromDAO(d, key, idList)
}
func (o *Oracle) verify(ic *interop.Context, _ []stackitem.Item) stackitem.Item {
return stackitem.NewBool(ic.Tx.HasAttribute(transaction.OracleResponseT))
}
func (o *Oracle) getOriginalTxID(d dao.DAO, tx *transaction.Transaction) util.Uint256 {
for i := range tx.Attributes {
if tx.Attributes[i].Type == transaction.OracleResponseT {
id := tx.Attributes[i].Value.(*transaction.OracleResponse).ID
req, _ := o.GetRequestInternal(d, id)
return req.OriginalTxID
}
}
return tx.Hash()
}
// getRequests returns all requests which have not been finished yet.
func (o *Oracle) getRequests(d dao.DAO) (map[uint64]*state.OracleRequest, error) {
m, err := d.GetStorageItemsWithPrefix(o.ID, prefixRequest)
if err != nil {
return nil, err
}
reqs := make(map[uint64]*state.OracleRequest, len(m))
for k, si := range m {
if len(k) != 8 {
return nil, errors.New("invalid request ID")
}
r := io.NewBinReaderFromBuf(si.Value)
req := new(state.OracleRequest)
req.DecodeBinary(r)
if r.Err != nil {
return nil, r.Err
}
id := binary.BigEndian.Uint64([]byte(k))
reqs[id] = req
}
return reqs, nil
}
func makeRequestKey(id uint64) []byte {
k := make([]byte, 9)
k[0] = prefixRequest[0]
binary.BigEndian.PutUint64(k[1:], id)
return k
}
func makeIDListKey(url string) []byte {
return append(prefixIDList, hash.Hash160([]byte(url)).BytesBE()...)
}
func (o *Oracle) getSerializableFromDAO(d dao.DAO, key []byte, item io.Serializable) error {
return getSerializableFromDAO(o.ID, d, key, item)
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}
// updateCache updates cached Oracle values if they've been changed
func (o *Oracle) updateCache(d dao.DAO) error {
orc, _ := o.Module.Load().(services.Oracle)
if orc == nil {
return nil
}
reqs := o.newRequests
o.newRequests = make(map[uint64]*state.OracleRequest)
for id := range reqs {
key := makeRequestKey(id)
if si := d.GetStorageItem(o.ID, key); si == nil { // tx has failed
delete(reqs, id)
}
}
orc.AddRequests(reqs)
return nil
}