예제 #1
0
// If the tx is invalid, an error will be returned.
// Unlike ExecBlock(), state will not be altered.
func ExecTx(blockCache *BlockCache, tx types.Tx, runCall bool, evc events.Fireable) (err error) {

	// TODO: do something with fees
	fees := int64(0)
	_s := blockCache.State() // hack to access validators and block height

	// Exec tx
	switch tx := tx.(type) {
	case *types.SendTx:
		accounts, err := getInputs(blockCache, tx.Inputs)
		if err != nil {
			return err
		}

		// ensure all inputs have send permissions
		if !hasSendPermission(blockCache, accounts) {
			return fmt.Errorf("At least one input lacks permission for SendTx")
		}

		// add outputs to accounts map
		// if any outputs don't exist, all inputs must have CreateAccount perm
		accounts, err = getOrMakeOutputs(blockCache, accounts, tx.Outputs)
		if err != nil {
			return err
		}

		signBytes := acm.SignBytes(_s.ChainID, tx)
		inTotal, err := validateInputs(accounts, signBytes, tx.Inputs)
		if err != nil {
			return err
		}
		outTotal, err := validateOutputs(tx.Outputs)
		if err != nil {
			return err
		}
		if outTotal > inTotal {
			return types.ErrTxInsufficientFunds
		}
		fee := inTotal - outTotal
		fees += fee

		// Good! Adjust accounts
		adjustByInputs(accounts, tx.Inputs)
		adjustByOutputs(accounts, tx.Outputs)
		for _, acc := range accounts {
			blockCache.UpdateAccount(acc)
		}

		// if the evc is nil, nothing will happen
		if evc != nil {
			for _, i := range tx.Inputs {
				evc.FireEvent(types.EventStringAccInput(i.Address), types.EventDataTx{tx, nil, ""})
			}

			for _, o := range tx.Outputs {
				evc.FireEvent(types.EventStringAccOutput(o.Address), types.EventDataTx{tx, nil, ""})
			}
		}
		return nil

	case *types.CallTx:
		var inAcc, outAcc *acm.Account

		// Validate input
		inAcc = blockCache.GetAccount(tx.Input.Address)
		if inAcc == nil {
			log.Info(Fmt("Can't find in account %X", tx.Input.Address))
			return types.ErrTxInvalidAddress
		}

		createContract := len(tx.Address) == 0
		if createContract {
			if !hasCreateContractPermission(blockCache, inAcc) {
				return fmt.Errorf("Account %X does not have CreateContract permission", tx.Input.Address)
			}
		} else {
			if !hasCallPermission(blockCache, inAcc) {
				return fmt.Errorf("Account %X does not have Call permission", tx.Input.Address)
			}
		}

		// pubKey should be present in either "inAcc" or "tx.Input"
		if err := checkInputPubKey(inAcc, tx.Input); err != nil {
			log.Info(Fmt("Can't find pubkey for %X", tx.Input.Address))
			return err
		}
		signBytes := acm.SignBytes(_s.ChainID, tx)
		err := validateInput(inAcc, signBytes, tx.Input)
		if err != nil {
			log.Info(Fmt("validateInput failed on %X: %v", tx.Input.Address, err))
			return err
		}
		if tx.Input.Amount < tx.Fee {
			log.Info(Fmt("Sender did not send enough to cover the fee %X", tx.Input.Address))
			return types.ErrTxInsufficientFunds
		}

		if !createContract {
			// Validate output
			if len(tx.Address) != 20 {
				log.Info(Fmt("Destination address is not 20 bytes %X", tx.Address))
				return types.ErrTxInvalidAddress
			}
			// check if its a native contract
			if vm.RegisteredNativeContract(LeftPadWord256(tx.Address)) {
				return fmt.Errorf("NativeContracts can not be called using CallTx. Use a contract or the appropriate tx type (eg. PermissionsTx, NameTx)")
			}

			// Output account may be nil if we are still in mempool and contract was created in same block as this tx
			// but that's fine, because the account will be created properly when the create tx runs in the block
			// and then this won't return nil. otherwise, we take their fee
			outAcc = blockCache.GetAccount(tx.Address)
		}

		log.Info(Fmt("Out account: %v", outAcc))

		// Good!
		value := tx.Input.Amount - tx.Fee
		inAcc.Sequence += 1
		inAcc.Balance -= tx.Fee
		blockCache.UpdateAccount(inAcc)

		// The logic in runCall MUST NOT return.
		if runCall {

			// VM call variables
			var (
				gas     int64       = tx.GasLimit
				err     error       = nil
				caller  *vm.Account = toVMAccount(inAcc)
				callee  *vm.Account = nil // initialized below
				code    []byte      = nil
				ret     []byte      = nil
				txCache             = NewTxCache(blockCache)
				params              = vm.Params{
					BlockHeight: int64(_s.LastBlockHeight),
					BlockHash:   LeftPadWord256(_s.LastBlockHash),
					BlockTime:   _s.LastBlockTime.Unix(),
					GasLimit:    _s.GetGasLimit(),
				}
			)

			if !createContract && (outAcc == nil || len(outAcc.Code) == 0) {
				// if you call an account that doesn't exist
				// or an account with no code then we take fees (sorry pal)
				// NOTE: it's fine to create a contract and call it within one
				// block (nonce will prevent re-ordering of those txs)
				// but to create with one contract and call with another
				// you have to wait a block to avoid a re-ordering attack
				// that will take your fees
				if outAcc == nil {
					log.Info(Fmt("%X tries to call %X but it does not exist.",
						inAcc.Address, tx.Address))
				} else {
					log.Info(Fmt("%X tries to call %X but code is blank.",
						inAcc.Address, tx.Address))
				}
				err = types.ErrTxInvalidAddress
				goto CALL_COMPLETE
			}

			// get or create callee
			if createContract {
				// We already checked for permission
				callee = txCache.CreateAccount(caller)
				log.Info(Fmt("Created new contract %X", callee.Address))
				code = tx.Data
			} else {
				callee = toVMAccount(outAcc)
				log.Info(Fmt("Calling contract %X with code %X", callee.Address, callee.Code))
				code = callee.Code
			}
			log.Info(Fmt("Code for this contract: %X", code))

			// Run VM call and sync txCache to blockCache.
			{ // Capture scope for goto.
				// Write caller/callee to txCache.
				txCache.UpdateAccount(caller)
				txCache.UpdateAccount(callee)
				vmach := vm.NewVM(txCache, params, caller.Address, types.TxID(_s.ChainID, tx))
				vmach.SetFireable(evc)
				// NOTE: Call() transfers the value from caller to callee iff call succeeds.
				ret, err = vmach.Call(caller, callee, code, tx.Data, value, &gas)
				if err != nil {
					// Failure. Charge the gas fee. The 'value' was otherwise not transferred.
					log.Info(Fmt("Error on execution: %v", err))
					goto CALL_COMPLETE
				}

				log.Info("Successful execution")
				if createContract {
					callee.Code = ret
				}
				txCache.Sync()
			}

		CALL_COMPLETE: // err may or may not be nil.

			// Create a receipt from the ret and whether errored.
			log.Notice("VM call complete", "caller", caller, "callee", callee, "return", ret, "err", err)

			// Fire Events for sender and receiver
			// a separate event will be fired from vm for each additional call
			if evc != nil {
				exception := ""
				if err != nil {
					exception = err.Error()
				}
				evc.FireEvent(types.EventStringAccInput(tx.Input.Address), types.EventDataTx{tx, ret, exception})
				evc.FireEvent(types.EventStringAccOutput(tx.Address), types.EventDataTx{tx, ret, exception})
			}
		} else {
			// The mempool does not call txs until
			// the proposer determines the order of txs.
			// So mempool will skip the actual .Call(),
			// and only deduct from the caller's balance.
			inAcc.Balance -= value
			if createContract {
				inAcc.Sequence += 1
			}
			blockCache.UpdateAccount(inAcc)
		}

		return nil

	case *types.NameTx:
		var inAcc *acm.Account

		// Validate input
		inAcc = blockCache.GetAccount(tx.Input.Address)
		if inAcc == nil {
			log.Info(Fmt("Can't find in account %X", tx.Input.Address))
			return types.ErrTxInvalidAddress
		}
		// check permission
		if !hasNamePermission(blockCache, inAcc) {
			return fmt.Errorf("Account %X does not have Name permission", tx.Input.Address)
		}
		// pubKey should be present in either "inAcc" or "tx.Input"
		if err := checkInputPubKey(inAcc, tx.Input); err != nil {
			log.Info(Fmt("Can't find pubkey for %X", tx.Input.Address))
			return err
		}
		signBytes := acm.SignBytes(_s.ChainID, tx)
		err := validateInput(inAcc, signBytes, tx.Input)
		if err != nil {
			log.Info(Fmt("validateInput failed on %X: %v", tx.Input.Address, err))
			return err
		}
		// fee is in addition to the amount which is used to determine the TTL
		if tx.Input.Amount < tx.Fee {
			log.Info(Fmt("Sender did not send enough to cover the fee %X", tx.Input.Address))
			return types.ErrTxInsufficientFunds
		}

		// validate the input strings
		if err := tx.ValidateStrings(); err != nil {
			return err
		}

		value := tx.Input.Amount - tx.Fee

		// let's say cost of a name for one block is len(data) + 32
		costPerBlock := types.NameCostPerBlock(types.NameBaseCost(tx.Name, tx.Data))
		expiresIn := int(value / costPerBlock)
		lastBlockHeight := _s.LastBlockHeight

		log.Info("New NameTx", "value", value, "costPerBlock", costPerBlock, "expiresIn", expiresIn, "lastBlock", lastBlockHeight)

		// check if the name exists
		entry := blockCache.GetNameRegEntry(tx.Name)

		if entry != nil {
			var expired bool
			// if the entry already exists, and hasn't expired, we must be owner
			if entry.Expires > lastBlockHeight {
				// ensure we are owner
				if bytes.Compare(entry.Owner, tx.Input.Address) != 0 {
					log.Info(Fmt("Sender %X is trying to update a name (%s) for which he is not owner", tx.Input.Address, tx.Name))
					return types.ErrTxPermissionDenied
				}
			} else {
				expired = true
			}

			// no value and empty data means delete the entry
			if value == 0 && len(tx.Data) == 0 {
				// maybe we reward you for telling us we can delete this crap
				// (owners if not expired, anyone if expired)
				log.Info("Removing namereg entry", "name", entry.Name)
				blockCache.RemoveNameRegEntry(entry.Name)
			} else {
				// update the entry by bumping the expiry
				// and changing the data
				if expired {
					if expiresIn < types.MinNameRegistrationPeriod {
						return errors.New(Fmt("Names must be registered for at least %d blocks", types.MinNameRegistrationPeriod))
					}
					entry.Expires = lastBlockHeight + expiresIn
					entry.Owner = tx.Input.Address
					log.Info("An old namereg entry has expired and been reclaimed", "name", entry.Name, "expiresIn", expiresIn, "owner", entry.Owner)
				} else {
					// since the size of the data may have changed
					// we use the total amount of "credit"
					oldCredit := int64(entry.Expires-lastBlockHeight) * types.NameBaseCost(entry.Name, entry.Data)
					credit := oldCredit + value
					expiresIn = int(credit / costPerBlock)
					if expiresIn < types.MinNameRegistrationPeriod {
						return errors.New(Fmt("Names must be registered for at least %d blocks", types.MinNameRegistrationPeriod))
					}
					entry.Expires = lastBlockHeight + expiresIn
					log.Info("Updated namereg entry", "name", entry.Name, "expiresIn", expiresIn, "oldCredit", oldCredit, "value", value, "credit", credit)
				}
				entry.Data = tx.Data
				blockCache.UpdateNameRegEntry(entry)
			}
		} else {
			if expiresIn < types.MinNameRegistrationPeriod {
				return errors.New(Fmt("Names must be registered for at least %d blocks", types.MinNameRegistrationPeriod))
			}
			// entry does not exist, so create it
			entry = &types.NameRegEntry{
				Name:    tx.Name,
				Owner:   tx.Input.Address,
				Data:    tx.Data,
				Expires: lastBlockHeight + expiresIn,
			}
			log.Info("Creating namereg entry", "name", entry.Name, "expiresIn", expiresIn)
			blockCache.UpdateNameRegEntry(entry)
		}

		// TODO: something with the value sent?

		// Good!
		inAcc.Sequence += 1
		inAcc.Balance -= value
		blockCache.UpdateAccount(inAcc)

		// TODO: maybe we want to take funds on error and allow txs in that don't do anythingi?

		if evc != nil {
			evc.FireEvent(types.EventStringAccInput(tx.Input.Address), types.EventDataTx{tx, nil, ""})
			evc.FireEvent(types.EventStringNameReg(tx.Name), types.EventDataTx{tx, nil, ""})
		}

		return nil

	case *types.BondTx:
		valInfo := blockCache.State().GetValidatorInfo(tx.PubKey.Address())
		if valInfo != nil {
			// TODO: In the future, check that the validator wasn't destroyed,
			// add funds, merge UnbondTo outputs, and unbond validator.
			return errors.New("Adding coins to existing validators not yet supported")
		}

		accounts, err := getInputs(blockCache, tx.Inputs)
		if err != nil {
			return err
		}

		// add outputs to accounts map
		// if any outputs don't exist, all inputs must have CreateAccount perm
		// though outputs aren't created until unbonding/release time
		canCreate := hasCreateAccountPermission(blockCache, accounts)
		for _, out := range tx.UnbondTo {
			acc := blockCache.GetAccount(out.Address)
			if acc == nil && !canCreate {
				return fmt.Errorf("At least one input does not have permission to create accounts")
			}
		}

		bondAcc := blockCache.GetAccount(tx.PubKey.Address())
		if !hasBondPermission(blockCache, bondAcc) {
			return fmt.Errorf("The bonder does not have permission to bond")
		}

		if !hasBondOrSendPermission(blockCache, accounts) {
			return fmt.Errorf("At least one input lacks permission to bond")
		}

		signBytes := acm.SignBytes(_s.ChainID, tx)
		inTotal, err := validateInputs(accounts, signBytes, tx.Inputs)
		if err != nil {
			return err
		}
		if !tx.PubKey.VerifyBytes(signBytes, tx.Signature) {
			return types.ErrTxInvalidSignature
		}
		outTotal, err := validateOutputs(tx.UnbondTo)
		if err != nil {
			return err
		}
		if outTotal > inTotal {
			return types.ErrTxInsufficientFunds
		}
		fee := inTotal - outTotal
		fees += fee

		// Good! Adjust accounts
		adjustByInputs(accounts, tx.Inputs)
		for _, acc := range accounts {
			blockCache.UpdateAccount(acc)
		}
		// Add ValidatorInfo
		_s.SetValidatorInfo(&types.ValidatorInfo{
			Address:         tx.PubKey.Address(),
			PubKey:          tx.PubKey,
			UnbondTo:        tx.UnbondTo,
			FirstBondHeight: _s.LastBlockHeight + 1,
			FirstBondAmount: outTotal,
		})
		// Add Validator
		added := _s.BondedValidators.Add(&types.Validator{
			Address:     tx.PubKey.Address(),
			PubKey:      tx.PubKey,
			BondHeight:  _s.LastBlockHeight + 1,
			VotingPower: outTotal,
			Accum:       0,
		})
		if !added {
			PanicCrisis("Failed to add validator")
		}
		if evc != nil {
			// TODO: fire for all inputs
			evc.FireEvent(types.EventStringBond(), types.EventDataTx{tx, nil, ""})
		}
		return nil

	case *types.UnbondTx:
		// The validator must be active
		_, val := _s.BondedValidators.GetByAddress(tx.Address)
		if val == nil {
			return types.ErrTxInvalidAddress
		}

		// Verify the signature
		signBytes := acm.SignBytes(_s.ChainID, tx)
		if !val.PubKey.VerifyBytes(signBytes, tx.Signature) {
			return types.ErrTxInvalidSignature
		}

		// tx.Height must be greater than val.LastCommitHeight
		if tx.Height <= val.LastCommitHeight {
			return errors.New("Invalid unbond height")
		}

		// Good!
		_s.unbondValidator(val)
		if evc != nil {
			evc.FireEvent(types.EventStringUnbond(), types.EventDataTx{tx, nil, ""})
		}
		return nil

	case *types.RebondTx:
		// The validator must be inactive
		_, val := _s.UnbondingValidators.GetByAddress(tx.Address)
		if val == nil {
			return types.ErrTxInvalidAddress
		}

		// Verify the signature
		signBytes := acm.SignBytes(_s.ChainID, tx)
		if !val.PubKey.VerifyBytes(signBytes, tx.Signature) {
			return types.ErrTxInvalidSignature
		}

		// tx.Height must be in a suitable range
		minRebondHeight := _s.LastBlockHeight - (validatorTimeoutBlocks / 2)
		maxRebondHeight := _s.LastBlockHeight + 2
		if !((minRebondHeight <= tx.Height) && (tx.Height <= maxRebondHeight)) {
			return errors.New(Fmt("Rebond height not in range.  Expected %v <= %v <= %v",
				minRebondHeight, tx.Height, maxRebondHeight))
		}

		// Good!
		_s.rebondValidator(val)
		if evc != nil {
			evc.FireEvent(types.EventStringRebond(), types.EventDataTx{tx, nil, ""})
		}
		return nil

	case *types.DupeoutTx:
		// Verify the signatures
		_, accused := _s.BondedValidators.GetByAddress(tx.Address)
		if accused == nil {
			_, accused = _s.UnbondingValidators.GetByAddress(tx.Address)
			if accused == nil {
				return types.ErrTxInvalidAddress
			}
		}
		voteASignBytes := acm.SignBytes(_s.ChainID, &tx.VoteA)
		voteBSignBytes := acm.SignBytes(_s.ChainID, &tx.VoteB)
		if !accused.PubKey.VerifyBytes(voteASignBytes, tx.VoteA.Signature) ||
			!accused.PubKey.VerifyBytes(voteBSignBytes, tx.VoteB.Signature) {
			return types.ErrTxInvalidSignature
		}

		// Verify equivocation
		// TODO: in the future, just require one vote from a previous height that
		// doesn't exist on this chain.
		if tx.VoteA.Height != tx.VoteB.Height {
			return errors.New("DupeoutTx heights don't match")
		}
		if tx.VoteA.Round != tx.VoteB.Round {
			return errors.New("DupeoutTx rounds don't match")
		}
		if tx.VoteA.Type != tx.VoteB.Type {
			return errors.New("DupeoutTx types don't match")
		}
		if bytes.Equal(tx.VoteA.BlockHash, tx.VoteB.BlockHash) {
			return errors.New("DupeoutTx blockhashes shouldn't match")
		}

		// Good! (Bad validator!)
		_s.destroyValidator(accused)
		if evc != nil {
			evc.FireEvent(types.EventStringDupeout(), types.EventDataTx{tx, nil, ""})
		}
		return nil

	case *types.PermissionsTx:
		var inAcc *acm.Account

		// Validate input
		inAcc = blockCache.GetAccount(tx.Input.Address)
		if inAcc == nil {
			log.Debug(Fmt("Can't find in account %X", tx.Input.Address))
			return types.ErrTxInvalidAddress
		}

		permFlag := tx.PermArgs.PermFlag()
		// check permission
		if !HasPermission(blockCache, inAcc, permFlag) {
			return fmt.Errorf("Account %X does not have moderator permission %s (%b)", tx.Input.Address, ptypes.PermFlagToString(permFlag), permFlag)
		}

		// pubKey should be present in either "inAcc" or "tx.Input"
		if err := checkInputPubKey(inAcc, tx.Input); err != nil {
			log.Debug(Fmt("Can't find pubkey for %X", tx.Input.Address))
			return err
		}
		signBytes := acm.SignBytes(_s.ChainID, tx)
		err := validateInput(inAcc, signBytes, tx.Input)
		if err != nil {
			log.Debug(Fmt("validateInput failed on %X: %v", tx.Input.Address, err))
			return err
		}

		value := tx.Input.Amount

		log.Debug("New PermissionsTx", "function", ptypes.PermFlagToString(permFlag), "args", tx.PermArgs)

		var permAcc *acm.Account
		switch args := tx.PermArgs.(type) {
		case *ptypes.HasBaseArgs:
			// this one doesn't make sense from txs
			return fmt.Errorf("HasBase is for contracts, not humans. Just look at the blockchain")
		case *ptypes.SetBaseArgs:
			if permAcc = blockCache.GetAccount(args.Address); permAcc == nil {
				return fmt.Errorf("Trying to update permissions for unknown account %X", args.Address)
			}
			err = permAcc.Permissions.Base.Set(args.Permission, args.Value)
		case *ptypes.UnsetBaseArgs:
			if permAcc = blockCache.GetAccount(args.Address); permAcc == nil {
				return fmt.Errorf("Trying to update permissions for unknown account %X", args.Address)
			}
			err = permAcc.Permissions.Base.Unset(args.Permission)
		case *ptypes.SetGlobalArgs:
			if permAcc = blockCache.GetAccount(ptypes.GlobalPermissionsAddress); permAcc == nil {
				PanicSanity("can't find global permissions account")
			}
			err = permAcc.Permissions.Base.Set(args.Permission, args.Value)
		case *ptypes.HasRoleArgs:
			return fmt.Errorf("HasRole is for contracts, not humans. Just look at the blockchain")
		case *ptypes.AddRoleArgs:
			if permAcc = blockCache.GetAccount(args.Address); permAcc == nil {
				return fmt.Errorf("Trying to update roles for unknown account %X", args.Address)
			}
			if !permAcc.Permissions.AddRole(args.Role) {
				return fmt.Errorf("Role (%s) already exists for account %X", args.Role, args.Address)
			}
		case *ptypes.RmRoleArgs:
			if permAcc = blockCache.GetAccount(args.Address); permAcc == nil {
				return fmt.Errorf("Trying to update roles for unknown account %X", args.Address)
			}
			if !permAcc.Permissions.RmRole(args.Role) {
				return fmt.Errorf("Role (%s) does not exist for account %X", args.Role, args.Address)
			}
		default:
			PanicSanity(Fmt("invalid permission function: %s", ptypes.PermFlagToString(permFlag)))
		}

		// TODO: maybe we want to take funds on error and allow txs in that don't do anythingi?
		if err != nil {
			return err
		}

		// Good!
		inAcc.Sequence += 1
		inAcc.Balance -= value
		blockCache.UpdateAccount(inAcc)
		if permAcc != nil {
			blockCache.UpdateAccount(permAcc)
		}

		if evc != nil {
			evc.FireEvent(types.EventStringAccInput(tx.Input.Address), types.EventDataTx{tx, nil, ""})
			evc.FireEvent(types.EventStringPermissions(ptypes.PermFlagToString(permFlag)), types.EventDataTx{tx, nil, ""})
		}

		return nil

	default:
		// binary decoding should not let this happen
		PanicSanity("Unknown Tx type")
		return nil
	}
}
예제 #2
0
// If the tx is invalid, an error will be returned.
// Unlike ExecBlock(), state will not be altered.
func ExecTx(blockCache *BlockCache, tx_ types.Tx, runCall bool, evc events.Fireable) error {

	// TODO: do something with fees
	fees := uint64(0)
	_s := blockCache.State() // hack to access validators and event switch.

	// Exec tx
	switch tx := tx_.(type) {
	case *types.SendTx:
		accounts, err := getOrMakeAccounts(blockCache, tx.Inputs, tx.Outputs)
		if err != nil {
			return err
		}
		signBytes := account.SignBytes(tx)
		inTotal, err := validateInputs(accounts, signBytes, tx.Inputs)
		if err != nil {
			return err
		}
		outTotal, err := validateOutputs(tx.Outputs)
		if err != nil {
			return err
		}
		if outTotal > inTotal {
			return types.ErrTxInsufficientFunds
		}
		fee := inTotal - outTotal
		fees += fee

		// Good! Adjust accounts
		adjustByInputs(accounts, tx.Inputs)
		adjustByOutputs(accounts, tx.Outputs)
		for _, acc := range accounts {
			blockCache.UpdateAccount(acc)
		}

		// if the evc is nil, nothing will happen
		if evc != nil {
			for _, i := range tx.Inputs {
				evc.FireEvent(types.EventStringAccInput(i.Address), tx)
			}

			for _, o := range tx.Outputs {
				evc.FireEvent(types.EventStringAccOutput(o.Address), tx)
			}
		}
		return nil

	case *types.CallTx:
		var inAcc, outAcc *account.Account

		// Validate input
		inAcc = blockCache.GetAccount(tx.Input.Address)
		if inAcc == nil {
			log.Debug(Fmt("Can't find in account %X", tx.Input.Address))
			return types.ErrTxInvalidAddress
		}
		// pubKey should be present in either "inAcc" or "tx.Input"
		if err := checkInputPubKey(inAcc, tx.Input); err != nil {
			log.Debug(Fmt("Can't find pubkey for %X", tx.Input.Address))
			return err
		}
		signBytes := account.SignBytes(tx)
		err := validateInput(inAcc, signBytes, tx.Input)
		if err != nil {
			log.Debug(Fmt("validateInput failed on %X:", tx.Input.Address))
			return err
		}
		if tx.Input.Amount < tx.Fee {
			log.Debug(Fmt("Sender did not send enough to cover the fee %X", tx.Input.Address))
			return types.ErrTxInsufficientFunds
		}

		createAccount := len(tx.Address) == 0
		if !createAccount {
			// Validate output
			if len(tx.Address) != 20 {
				log.Debug(Fmt("Destination address is not 20 bytes %X", tx.Address))
				return types.ErrTxInvalidAddress
			}
			// this may be nil if we are still in mempool and contract was created in same block as this tx
			// but that's fine, because the account will be created properly when the create tx runs in the block
			// and then this won't return nil. otherwise, we take their fee
			outAcc = blockCache.GetAccount(tx.Address)
		}

		log.Debug(Fmt("Out account: %v", outAcc))

		// Good!
		value := tx.Input.Amount - tx.Fee
		inAcc.Sequence += 1

		if runCall {

			var (
				gas     uint64      = tx.GasLimit
				err     error       = nil
				caller  *vm.Account = toVMAccount(inAcc)
				callee  *vm.Account = nil
				code    []byte      = nil
				txCache             = NewTxCache(blockCache)
				params              = vm.Params{
					BlockHeight: uint64(_s.LastBlockHeight),
					BlockHash:   LeftPadWord256(_s.LastBlockHash),
					BlockTime:   _s.LastBlockTime.Unix(),
					GasLimit:    10000000,
				}
			)

			// Maybe create a new callee account if
			// this transaction is creating a new contract.
			if !createAccount {
				if outAcc == nil || len(outAcc.Code) == 0 {
					// if you call an account that doesn't exist
					// or an account with no code then we take fees (sorry pal)
					// NOTE: it's fine to create a contract and call it within one
					// block (nonce will prevent re-ordering of those txs)
					// but to create with one account and call with another
					// you have to wait a block to avoid a re-ordering attack
					// that will take your fees
					inAcc.Balance -= tx.Fee
					blockCache.UpdateAccount(inAcc)
					if outAcc == nil {
						log.Debug(Fmt("Cannot find destination address %X. Deducting fee from caller", tx.Address))
					} else {
						log.Debug(Fmt("Attempting to call an account (%X) with no code. Deducting fee from caller", tx.Address))
					}
					return types.ErrTxInvalidAddress

				}
				callee = toVMAccount(outAcc)
				code = callee.Code
				log.Debug(Fmt("Calling contract %X with code %X", callee.Address, callee.Code))
			} else {
				callee = txCache.CreateAccount(caller)
				log.Debug(Fmt("Created new account %X", callee.Address))
				code = tx.Data
			}
			log.Debug(Fmt("Code for this contract: %X", code))

			txCache.UpdateAccount(caller) // because we adjusted by input above, and bumped nonce maybe.
			txCache.UpdateAccount(callee) // because we adjusted by input above.
			vmach := vm.NewVM(txCache, params, caller.Address, account.HashSignBytes(tx))
			vmach.SetFireable(evc)
			// NOTE: Call() transfers the value from caller to callee iff call succeeds.

			ret, err := vmach.Call(caller, callee, code, tx.Data, value, &gas)
			exception := ""
			if err != nil {
				exception = err.Error()
				// Failure. Charge the gas fee. The 'value' was otherwise not transferred.
				log.Debug(Fmt("Error on execution: %v", err))
				inAcc.Balance -= tx.Fee
				blockCache.UpdateAccount(inAcc)
				// Throw away 'txCache' which holds incomplete updates (don't sync it).
			} else {
				log.Debug("Successful execution")
				// Success
				if createAccount {
					callee.Code = ret
				}

				txCache.Sync()
			}
			// Create a receipt from the ret and whether errored.
			log.Info("VM call complete", "caller", caller, "callee", callee, "return", ret, "err", err)

			// Fire Events for sender and receiver
			// a separate event will be fired from vm for each additional call
			if evc != nil {
				evc.FireEvent(types.EventStringAccInput(tx.Input.Address), types.EventMsgCallTx{tx, ret, exception})
				evc.FireEvent(types.EventStringAccOutput(tx.Address), types.EventMsgCallTx{tx, ret, exception})
			}
		} else {
			// The mempool does not call txs until
			// the proposer determines the order of txs.
			// So mempool will skip the actual .Call(),
			// and only deduct from the caller's balance.
			inAcc.Balance -= value
			if createAccount {
				inAcc.Sequence += 1
			}
			blockCache.UpdateAccount(inAcc)
		}

		return nil

	case *types.BondTx:
		valInfo := blockCache.State().GetValidatorInfo(tx.PubKey.Address())
		if valInfo != nil {
			// TODO: In the future, check that the validator wasn't destroyed,
			// add funds, merge UnbondTo outputs, and unbond validator.
			return errors.New("Adding coins to existing validators not yet supported")
		}
		accounts, err := getOrMakeAccounts(blockCache, tx.Inputs, nil)
		if err != nil {
			return err
		}
		signBytes := account.SignBytes(tx)
		inTotal, err := validateInputs(accounts, signBytes, tx.Inputs)
		if err != nil {
			return err
		}
		if err := tx.PubKey.ValidateBasic(); err != nil {
			return err
		}
		outTotal, err := validateOutputs(tx.UnbondTo)
		if err != nil {
			return err
		}
		if outTotal > inTotal {
			return types.ErrTxInsufficientFunds
		}
		fee := inTotal - outTotal
		fees += fee

		// Good! Adjust accounts
		adjustByInputs(accounts, tx.Inputs)
		for _, acc := range accounts {
			blockCache.UpdateAccount(acc)
		}
		// Add ValidatorInfo
		_s.SetValidatorInfo(&ValidatorInfo{
			Address:         tx.PubKey.Address(),
			PubKey:          tx.PubKey,
			UnbondTo:        tx.UnbondTo,
			FirstBondHeight: _s.LastBlockHeight + 1,
			FirstBondAmount: outTotal,
		})
		// Add Validator
		added := _s.BondedValidators.Add(&Validator{
			Address:     tx.PubKey.Address(),
			PubKey:      tx.PubKey,
			BondHeight:  _s.LastBlockHeight + 1,
			VotingPower: outTotal,
			Accum:       0,
		})
		if !added {
			panic("Failed to add validator")
		}
		if evc != nil {
			evc.FireEvent(types.EventStringBond(), tx)
		}
		return nil

	case *types.UnbondTx:
		// The validator must be active
		_, val := _s.BondedValidators.GetByAddress(tx.Address)
		if val == nil {
			return types.ErrTxInvalidAddress
		}

		// Verify the signature
		signBytes := account.SignBytes(tx)
		if !val.PubKey.VerifyBytes(signBytes, tx.Signature) {
			return types.ErrTxInvalidSignature
		}

		// tx.Height must be greater than val.LastCommitHeight
		if tx.Height <= val.LastCommitHeight {
			return errors.New("Invalid unbond height")
		}

		// Good!
		_s.unbondValidator(val)
		if evc != nil {
			evc.FireEvent(types.EventStringUnbond(), tx)
		}
		return nil

	case *types.RebondTx:
		// The validator must be inactive
		_, val := _s.UnbondingValidators.GetByAddress(tx.Address)
		if val == nil {
			return types.ErrTxInvalidAddress
		}

		// Verify the signature
		signBytes := account.SignBytes(tx)
		if !val.PubKey.VerifyBytes(signBytes, tx.Signature) {
			return types.ErrTxInvalidSignature
		}

		// tx.Height must be equal to the next height
		if tx.Height != _s.LastBlockHeight+1 {
			return errors.New(Fmt("Invalid rebond height.  Expected %v, got %v", _s.LastBlockHeight+1, tx.Height))
		}

		// Good!
		_s.rebondValidator(val)
		if evc != nil {
			evc.FireEvent(types.EventStringRebond(), tx)
		}
		return nil

	case *types.DupeoutTx:
		// Verify the signatures
		_, accused := _s.BondedValidators.GetByAddress(tx.Address)
		if accused == nil {
			_, accused = _s.UnbondingValidators.GetByAddress(tx.Address)
			if accused == nil {
				return types.ErrTxInvalidAddress
			}
		}
		voteASignBytes := account.SignBytes(&tx.VoteA)
		voteBSignBytes := account.SignBytes(&tx.VoteB)
		if !accused.PubKey.VerifyBytes(voteASignBytes, tx.VoteA.Signature) ||
			!accused.PubKey.VerifyBytes(voteBSignBytes, tx.VoteB.Signature) {
			return types.ErrTxInvalidSignature
		}

		// Verify equivocation
		// TODO: in the future, just require one vote from a previous height that
		// doesn't exist on this chain.
		if tx.VoteA.Height != tx.VoteB.Height {
			return errors.New("DupeoutTx heights don't match")
		}
		if tx.VoteA.Type == types.VoteTypeCommit && tx.VoteA.Round < tx.VoteB.Round {
			// Check special case (not an error, validator must be slashed!)
			// Validators should not sign another vote after committing.
		} else if tx.VoteB.Type == types.VoteTypeCommit && tx.VoteB.Round < tx.VoteA.Round {
			// We need to check both orderings of the votes
		} else {
			if tx.VoteA.Round != tx.VoteB.Round {
				return errors.New("DupeoutTx rounds don't match")
			}
			if tx.VoteA.Type != tx.VoteB.Type {
				return errors.New("DupeoutTx types don't match")
			}
			if bytes.Equal(tx.VoteA.BlockHash, tx.VoteB.BlockHash) {
				return errors.New("DupeoutTx blockhashes shouldn't match")
			}
		}

		// Good! (Bad validator!)
		_s.destroyValidator(accused)
		if evc != nil {
			evc.FireEvent(types.EventStringDupeout(), tx)
		}
		return nil

	default:
		panic("Unknown Tx type")
	}
}