package native import ( "errors" "fmt" "math/big" "github.com/nspcc-dev/neo-go/pkg/core/interop" "github.com/nspcc-dev/neo-go/pkg/core/state" "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/smartcontract" "github.com/nspcc-dev/neo-go/pkg/util" ) // GAS represents GAS native contract. type GAS struct { nep5TokenNative NEO *NEO } const gasSyscallName = "Neo.Native.Tokens.GAS" // GASFactor is a divisor for finding GAS integral value. const GASFactor = NEOTotalSupply const initialGAS = 30000000 // NewGAS returns GAS native contract. func NewGAS() *GAS { g := &GAS{} nep5 := newNEP5Native(gasSyscallName) nep5.name = "GAS" nep5.symbol = "gas" nep5.decimals = 8 nep5.factor = GASFactor nep5.onPersist = chainOnPersist(g.onPersist, g.OnPersist) nep5.incBalance = g.increaseBalance g.nep5TokenNative = *nep5 return g } func (g *GAS) increaseBalance(_ *interop.Context, _ util.Uint160, si *state.StorageItem, amount *big.Int) error { acc, err := state.NEP5BalanceStateFromBytes(si.Value) if err != nil { return err } if sign := amount.Sign(); sign == 0 { return nil } else if sign == -1 && acc.Balance.Cmp(new(big.Int).Neg(amount)) == -1 { return errors.New("insufficient funds") } acc.Balance.Add(&acc.Balance, amount) si.Value = acc.Bytes() return nil } // Initialize initializes GAS contract. func (g *GAS) Initialize(ic *interop.Context) error { if err := g.nep5TokenNative.Initialize(ic); err != nil { return err } if g.nep5TokenNative.getTotalSupply(ic).Sign() != 0 { return errors.New("already initialized") } h, _, err := getStandbyValidatorsHash(ic) if err != nil { return err } g.mint(ic, h, big.NewInt(initialGAS*GASFactor)) return nil } // OnPersist implements Contract interface. func (g *GAS) OnPersist(ic *interop.Context) error { for _, tx := range ic.Block.Transactions { absAmount := big.NewInt(int64(tx.SystemFee + tx.NetworkFee)) g.burn(ic, tx.Sender, absAmount) } validators, err := g.NEO.GetValidatorsInternal(ic.Chain, ic.DAO) if err != nil { return fmt.Errorf("cannot get block validators: %v", err) } primary := validators[ic.Block.ConsensusData.PrimaryIndex].GetScriptHash() var netFee util.Fixed8 for _, tx := range ic.Block.Transactions { netFee += tx.NetworkFee } g.mint(ic, primary, big.NewInt(int64(netFee))) return nil } func getStandbyValidatorsHash(ic *interop.Context) (util.Uint160, []*keys.PublicKey, error) { vs, err := ic.Chain.GetStandByValidators() if err != nil { return util.Uint160{}, nil, err } s, err := smartcontract.CreateMultiSigRedeemScript(len(vs)/2+1, vs) if err != nil { return util.Uint160{}, nil, err } return hash.Hash160(s), vs, nil } func chainOnPersist(fs ...func(*interop.Context) error) func(*interop.Context) error { return func(ic *interop.Context) error { for i := range fs { if fs[i] != nil { if err := fs[i](ic); err != nil { return err } } } return nil } }