neo-go/pkg/core/native/native_nep17.go

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package native
import (
"errors"
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"math"
"math/big"
"github.com/nspcc-dev/neo-go/pkg/core/dao"
"github.com/nspcc-dev/neo-go/pkg/core/interop"
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"github.com/nspcc-dev/neo-go/pkg/core/interop/contract"
"github.com/nspcc-dev/neo-go/pkg/core/interop/runtime"
"github.com/nspcc-dev/neo-go/pkg/core/state"
"github.com/nspcc-dev/neo-go/pkg/encoding/bigint"
"github.com/nspcc-dev/neo-go/pkg/smartcontract"
"github.com/nspcc-dev/neo-go/pkg/smartcontract/manifest"
"github.com/nspcc-dev/neo-go/pkg/util"
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"github.com/nspcc-dev/neo-go/pkg/vm"
"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
)
// prefixAccount is the standard prefix used to store account data.
const prefixAccount = 20
// makeAccountKey creates a key from account script hash.
func makeAccountKey(h util.Uint160) []byte {
return makeUint160Key(prefixAccount, h)
}
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// nep17TokenNative represents NEP-17 token contract.
type nep17TokenNative struct {
interop.ContractMD
symbol string
decimals int64
factor int64
incBalance func(*interop.Context, util.Uint160, *state.StorageItem, *big.Int) error
}
// totalSupplyKey is the key used to store totalSupply value.
var totalSupplyKey = []byte{11}
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func (c *nep17TokenNative) Metadata() *interop.ContractMD {
return &c.ContractMD
}
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func newNEP17Native(name string) *nep17TokenNative {
n := &nep17TokenNative{ContractMD: *interop.NewContractMD(name)}
n.Manifest.SupportedStandards = []string{manifest.NEP17StandardName}
desc := newDescriptor("symbol", smartcontract.StringType)
md := newMethodAndPrice(n.Symbol, 0, smartcontract.NoneFlag)
n.AddMethod(md, desc)
desc = newDescriptor("decimals", smartcontract.IntegerType)
md = newMethodAndPrice(n.Decimals, 0, smartcontract.NoneFlag)
n.AddMethod(md, desc)
desc = newDescriptor("totalSupply", smartcontract.IntegerType)
md = newMethodAndPrice(n.TotalSupply, 1000000, smartcontract.ReadStates)
n.AddMethod(md, desc)
desc = newDescriptor("balanceOf", smartcontract.IntegerType,
manifest.NewParameter("account", smartcontract.Hash160Type))
md = newMethodAndPrice(n.balanceOf, 1000000, smartcontract.ReadStates)
n.AddMethod(md, desc)
transferParams := []manifest.Parameter{
manifest.NewParameter("from", smartcontract.Hash160Type),
manifest.NewParameter("to", smartcontract.Hash160Type),
manifest.NewParameter("amount", smartcontract.IntegerType),
}
desc = newDescriptor("transfer", smartcontract.BoolType,
append(transferParams, manifest.NewParameter("data", smartcontract.AnyType))...,
)
md = newMethodAndPrice(n.Transfer, 9000000, smartcontract.WriteStates|smartcontract.AllowCall|smartcontract.AllowNotify)
n.AddMethod(md, desc)
n.AddEvent("Transfer", transferParams...)
return n
}
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func (c *nep17TokenNative) Initialize(_ *interop.Context) error {
return nil
}
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func (c *nep17TokenNative) Symbol(_ *interop.Context, _ []stackitem.Item) stackitem.Item {
return stackitem.NewByteArray([]byte(c.symbol))
}
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func (c *nep17TokenNative) Decimals(_ *interop.Context, _ []stackitem.Item) stackitem.Item {
return stackitem.NewBigInteger(big.NewInt(c.decimals))
}
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func (c *nep17TokenNative) TotalSupply(ic *interop.Context, _ []stackitem.Item) stackitem.Item {
return stackitem.NewBigInteger(c.getTotalSupply(ic.DAO))
}
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func (c *nep17TokenNative) getTotalSupply(d dao.DAO) *big.Int {
si := d.GetStorageItem(c.ContractID, totalSupplyKey)
if si == nil {
return big.NewInt(0)
}
return bigint.FromBytes(si.Value)
}
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func (c *nep17TokenNative) saveTotalSupply(d dao.DAO, supply *big.Int) error {
si := &state.StorageItem{Value: bigint.ToBytes(supply)}
return d.PutStorageItem(c.ContractID, totalSupplyKey, si)
}
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func (c *nep17TokenNative) Transfer(ic *interop.Context, args []stackitem.Item) stackitem.Item {
from := toUint160(args[0])
to := toUint160(args[1])
amount := toBigInt(args[2])
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err := c.TransferInternal(ic, from, to, amount, args[3])
return stackitem.NewBool(err == nil)
}
func addrToStackItem(u *util.Uint160) stackitem.Item {
if u == nil {
return stackitem.Null{}
}
return stackitem.NewByteArray(u.BytesBE())
}
func (c *nep17TokenNative) postTransfer(ic *interop.Context, from, to *util.Uint160, amount *big.Int,
data stackitem.Item, callOnPayment bool) {
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c.emitTransfer(ic, from, to, amount)
if to == nil || !callOnPayment {
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return
}
cs, err := ic.GetContract(*to)
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if err != nil {
return
}
fromArg := stackitem.Item(stackitem.Null{})
if from != nil {
fromArg = stackitem.NewByteArray((*from).BytesBE())
}
args := []stackitem.Item{
fromArg,
stackitem.NewBigInteger(amount),
data,
}
if err := contract.CallFromNative(ic, c.Hash, cs, manifest.MethodOnPayment, args, vm.EnsureIsEmpty); err != nil {
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panic(err)
}
}
func (c *nep17TokenNative) emitTransfer(ic *interop.Context, from, to *util.Uint160, amount *big.Int) {
ne := state.NotificationEvent{
ScriptHash: c.Hash,
Name: "Transfer",
Item: stackitem.NewArray([]stackitem.Item{
addrToStackItem(from),
addrToStackItem(to),
stackitem.NewBigInteger(amount),
}),
}
ic.Notifications = append(ic.Notifications, ne)
}
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func (c *nep17TokenNative) updateAccBalance(ic *interop.Context, acc util.Uint160, amount *big.Int) error {
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key := makeAccountKey(acc)
si := ic.DAO.GetStorageItem(c.ContractID, key)
if si == nil {
if amount.Sign() <= 0 {
return errors.New("insufficient funds")
}
si = new(state.StorageItem)
}
err := c.incBalance(ic, acc, si, amount)
if err != nil {
return err
}
if si.Value == nil {
err = ic.DAO.DeleteStorageItem(c.ContractID, key)
} else {
err = ic.DAO.PutStorageItem(c.ContractID, key, si)
}
return err
}
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// TransferInternal transfers NEO between accounts.
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func (c *nep17TokenNative) TransferInternal(ic *interop.Context, from, to util.Uint160, amount *big.Int, data stackitem.Item) error {
if amount.Sign() == -1 {
return errors.New("negative amount")
}
caller := ic.VM.GetCallingScriptHash()
if caller.Equals(util.Uint160{}) || !from.Equals(caller) {
ok, err := runtime.CheckHashedWitness(ic, from)
if err != nil {
return err
} else if !ok {
return errors.New("invalid signature")
}
}
isEmpty := from.Equals(to) || amount.Sign() == 0
inc := amount
if isEmpty {
inc = big.NewInt(0)
} else {
inc = new(big.Int).Neg(inc)
}
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if err := c.updateAccBalance(ic, from, inc); err != nil {
return err
}
if !isEmpty {
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if err := c.updateAccBalance(ic, to, amount); err != nil {
return err
}
}
c.postTransfer(ic, &from, &to, amount, data, true)
return nil
}
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func (c *nep17TokenNative) balanceOf(ic *interop.Context, args []stackitem.Item) stackitem.Item {
h := toUint160(args[0])
bs, err := ic.DAO.GetNEP17Balances(h)
if err != nil {
panic(err)
}
balance := bs.Trackers[c.ContractID].Balance
return stackitem.NewBigInteger(&balance)
}
func (c *nep17TokenNative) mint(ic *interop.Context, h util.Uint160, amount *big.Int, callOnPayment bool) {
if amount.Sign() == 0 {
return
}
c.addTokens(ic, h, amount)
c.postTransfer(ic, nil, &h, amount, stackitem.Null{}, callOnPayment)
}
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func (c *nep17TokenNative) burn(ic *interop.Context, h util.Uint160, amount *big.Int) {
if amount.Sign() == 0 {
return
}
c.addTokens(ic, h, new(big.Int).Neg(amount))
c.postTransfer(ic, &h, nil, amount, stackitem.Null{}, false)
}
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func (c *nep17TokenNative) addTokens(ic *interop.Context, h util.Uint160, amount *big.Int) {
if amount.Sign() == 0 {
return
}
key := makeAccountKey(h)
si := ic.DAO.GetStorageItem(c.ContractID, key)
if si == nil {
si = new(state.StorageItem)
}
if err := c.incBalance(ic, h, si, amount); err != nil {
panic(err)
}
if err := ic.DAO.PutStorageItem(c.ContractID, key, si); err != nil {
panic(err)
}
supply := c.getTotalSupply(ic.DAO)
supply.Add(supply, amount)
err := c.saveTotalSupply(ic.DAO, supply)
if err != nil {
panic(err)
}
}
func newDescriptor(name string, ret smartcontract.ParamType, ps ...manifest.Parameter) *manifest.Method {
return &manifest.Method{
Name: name,
Parameters: ps,
ReturnType: ret,
}
}
func newMethodAndPrice(f interop.Method, price int64, flags smartcontract.CallFlag) *interop.MethodAndPrice {
return &interop.MethodAndPrice{
Func: f,
Price: price,
RequiredFlags: flags,
}
}
func toBigInt(s stackitem.Item) *big.Int {
bi, err := s.TryInteger()
if err != nil {
panic(err)
}
return bi
}
func toUint160(s stackitem.Item) util.Uint160 {
buf, err := s.TryBytes()
if err != nil {
panic(err)
}
u, err := util.Uint160DecodeBytesBE(buf)
if err != nil {
panic(err)
}
return u
}
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func toUint32(s stackitem.Item) uint32 {
bigInt := toBigInt(s)
if !bigInt.IsInt64() {
panic("bigint is not an int64")
}
int64Value := bigInt.Int64()
if int64Value < 0 || int64Value > math.MaxUint32 {
panic("bigint does not fit into uint32")
}
return uint32(int64Value)
}