neoneo-go/pkg/core/native/native_nep5.go

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package native
import (
"errors"
"math/big"
"github.com/nspcc-dev/neo-go/pkg/core/interop"
"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/smartcontract"
"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"
"github.com/nspcc-dev/neo-go/pkg/vm/emit"
)
// 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 {
k := make([]byte, util.Uint160Size+1)
k[0] = prefixAccount
copy(k[1:], h.BytesBE())
return k
}
// nep5TokenNative represents NEP-5 token contract.
type nep5TokenNative struct {
interop.ContractMD
name string
symbol string
decimals int64
factor int64
onPersist func(*interop.Context) error
incBalance func(*interop.Context, util.Uint160, *state.StorageItem, *big.Int) error
}
// totalSupplyKey is the key used to store totalSupply value.
var totalSupplyKey = []byte{11}
func (c *nep5TokenNative) Metadata() *interop.ContractMD {
return &c.ContractMD
}
var _ interop.Contract = (*nep5TokenNative)(nil)
func newNEP5Native(name string) *nep5TokenNative {
n := &nep5TokenNative{ContractMD: *interop.NewContractMD(name)}
desc := newDescriptor("name", smartcontract.StringType)
md := newMethodAndPrice(n.Name, 1, smartcontract.NoneFlag)
n.AddMethod(md, desc, true)
desc = newDescriptor("symbol", smartcontract.StringType)
md = newMethodAndPrice(n.Symbol, 1, smartcontract.NoneFlag)
n.AddMethod(md, desc, true)
desc = newDescriptor("decimals", smartcontract.IntegerType)
md = newMethodAndPrice(n.Decimals, 1, smartcontract.NoneFlag)
n.AddMethod(md, desc, true)
desc = newDescriptor("totalSupply", smartcontract.IntegerType)
md = newMethodAndPrice(n.TotalSupply, 1, smartcontract.NoneFlag)
n.AddMethod(md, desc, true)
desc = newDescriptor("balanceOf", smartcontract.IntegerType,
manifest.NewParameter("account", smartcontract.Hash160Type))
md = newMethodAndPrice(n.balanceOf, 1, smartcontract.NoneFlag)
n.AddMethod(md, desc, true)
desc = newDescriptor("transfer", smartcontract.BoolType,
manifest.NewParameter("from", smartcontract.Hash160Type),
manifest.NewParameter("to", smartcontract.Hash160Type),
manifest.NewParameter("amount", smartcontract.IntegerType),
)
md = newMethodAndPrice(n.Transfer, 1, smartcontract.NoneFlag)
n.AddMethod(md, desc, false)
n.AddEvent("Transfer", desc.Parameters...)
return n
}
func (c *nep5TokenNative) Initialize(_ *interop.Context) error {
return nil
}
func (c *nep5TokenNative) Name(_ *interop.Context, _ []vm.StackItem) vm.StackItem {
return vm.NewByteArrayItem([]byte(c.name))
}
func (c *nep5TokenNative) Symbol(_ *interop.Context, _ []vm.StackItem) vm.StackItem {
return vm.NewByteArrayItem([]byte(c.symbol))
}
func (c *nep5TokenNative) Decimals(_ *interop.Context, _ []vm.StackItem) vm.StackItem {
return vm.NewBigIntegerItem(big.NewInt(c.decimals))
}
func (c *nep5TokenNative) TotalSupply(ic *interop.Context, _ []vm.StackItem) vm.StackItem {
return vm.NewBigIntegerItem(c.getTotalSupply(ic))
}
func (c *nep5TokenNative) getTotalSupply(ic *interop.Context) *big.Int {
si := ic.DAO.GetStorageItem(c.Hash, totalSupplyKey)
if si == nil {
return big.NewInt(0)
}
return emit.BytesToInt(si.Value)
}
func (c *nep5TokenNative) saveTotalSupply(ic *interop.Context, supply *big.Int) error {
si := &state.StorageItem{Value: emit.IntToBytes(supply)}
return ic.DAO.PutStorageItem(c.Hash, totalSupplyKey, si)
}
func (c *nep5TokenNative) Transfer(ic *interop.Context, args []vm.StackItem) vm.StackItem {
from := toUint160(args[0])
to := toUint160(args[1])
amount := toBigInt(args[2])
err := c.transfer(ic, from, to, amount)
return vm.NewBoolItem(err == nil)
}
func addrToStackItem(u *util.Uint160) vm.StackItem {
if u == nil {
return vm.NullItem{}
}
return vm.NewByteArrayItem(u.BytesBE())
}
func (c *nep5TokenNative) emitTransfer(ic *interop.Context, from, to *util.Uint160, amount *big.Int) {
ne := state.NotificationEvent{
ScriptHash: c.Hash,
Item: vm.NewArrayItem([]vm.StackItem{
vm.NewByteArrayItem([]byte("Transfer")),
addrToStackItem(from),
addrToStackItem(to),
vm.NewBigIntegerItem(amount),
}),
}
ic.Notifications = append(ic.Notifications, ne)
}
func (c *nep5TokenNative) transfer(ic *interop.Context, from, to util.Uint160, amount *big.Int) error {
if amount.Sign() == -1 {
return errors.New("negative amount")
}
ok, err := runtime.CheckHashedWitness(ic, nep5ScriptHash{
callingScriptHash: c.Hash,
entryScriptHash: c.Hash,
currentScriptHash: c.Hash,
}, from)
if err != nil {
return err
} else if !ok {
return errors.New("invalid signature")
}
keyFrom := makeAccountKey(from)
siFrom := ic.DAO.GetStorageItem(c.Hash, keyFrom)
if siFrom == nil {
return errors.New("insufficient funds")
}
isEmpty := from.Equals(to) || amount.Sign() == 0
inc := amount
if isEmpty {
inc = big.NewInt(0)
} else {
inc = new(big.Int).Neg(inc)
}
if err := c.incBalance(ic, from, siFrom, inc); err != nil {
return err
}
if err := ic.DAO.PutStorageItem(c.Hash, keyFrom, siFrom); err != nil {
return err
}
if !isEmpty {
keyTo := makeAccountKey(to)
siTo := ic.DAO.GetStorageItem(c.Hash, keyTo)
if siTo == nil {
siTo = new(state.StorageItem)
}
if err := c.incBalance(ic, to, siTo, amount); err != nil {
return err
}
if err := ic.DAO.PutStorageItem(c.Hash, keyTo, siTo); err != nil {
return err
}
}
c.emitTransfer(ic, &from, &to, amount)
return nil
}
func (c *nep5TokenNative) balanceOf(ic *interop.Context, args []vm.StackItem) vm.StackItem {
h := toUint160(args[0])
bs, err := ic.DAO.GetNEP5Balances(h)
if err != nil {
panic(err)
}
balance := bs.Trackers[c.Hash].Balance
return vm.NewBigIntegerItem(big.NewInt(balance))
}
func (c *nep5TokenNative) mint(ic *interop.Context, h util.Uint160, amount *big.Int) {
if amount.Sign() == 0 {
return
}
c.addTokens(ic, h, amount)
c.emitTransfer(ic, nil, &h, amount)
}
func (c *nep5TokenNative) burn(ic *interop.Context, h util.Uint160, amount *big.Int) {
if amount.Sign() == 0 {
return
}
amount = new(big.Int).Neg(amount)
c.addTokens(ic, h, amount)
c.emitTransfer(ic, &h, nil, amount)
}
func (c *nep5TokenNative) addTokens(ic *interop.Context, h util.Uint160, amount *big.Int) {
if amount.Sign() == 0 {
return
}
key := makeAccountKey(h)
si := ic.DAO.GetStorageItem(c.Hash, 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.Hash, key, si); err != nil {
panic(err)
}
supply := c.getTotalSupply(ic)
supply.Add(supply, amount)
err := c.saveTotalSupply(ic, supply)
if err != nil {
panic(err)
}
}
func (c *nep5TokenNative) OnPersist(ic *interop.Context) error {
return c.onPersist(ic)
}
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 vm.StackItem) *big.Int {
bi, err := s.TryInteger()
if err != nil {
panic(err)
}
return bi
}
func toUint160(s vm.StackItem) util.Uint160 {
buf, err := s.TryBytes()
if err != nil {
panic(err)
}
u, err := util.Uint160DecodeBytesBE(buf)
if err != nil {
panic(err)
}
return u
}
// scriptHash is an auxiliary structure which implements ScriptHashGetter
// interface over NEP5 native contract and is used for runtime.CheckHashedWitness
type nep5ScriptHash struct {
callingScriptHash util.Uint160
entryScriptHash util.Uint160
currentScriptHash util.Uint160
}
// GetCallingScriptHash implements ScriptHashGetter interface
func (s nep5ScriptHash) GetCallingScriptHash() util.Uint160 {
return s.callingScriptHash
}
// GetEntryScriptHash implements ScriptHashGetter interface
func (s nep5ScriptHash) GetEntryScriptHash() util.Uint160 {
return s.entryScriptHash
}
// GetCurrentScriptHash implements ScriptHashGetter interface
func (s nep5ScriptHash) GetCurrentScriptHash() util.Uint160 {
return s.currentScriptHash
}