// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package bind
import (
"context"
"errors"
"fmt"
"math/big"
"github.com/ethereum/go-ethereum"
"github.com/ethereum/go-ethereum/accounts/abi"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/crypto"
)
// SignerFn is a signer function callback when a contract requires a method to
// sign the transaction before submission.
type SignerFn func(types.Signer, common.Address, *types.Transaction) (*types.Transaction, error)
// CallOpts is the collection of options to fine tune a contract call request.
type CallOpts struct {
Pending bool // Whether to operate on the pending state or the last known one
From common.Address // Optional the sender address, otherwise the first account is used
Context context.Context // Network context to support cancellation and timeouts (nil = no timeout)
}
// TransactOpts is the collection of authorization data required to create a
// valid Ethereum transaction.
type TransactOpts struct {
From common.Address // Ethereum account to send the transaction from
Nonce *big.Int // Nonce to use for the transaction execution (nil = use pending state)
Signer SignerFn // Method to use for signing the transaction (mandatory)
Value *big.Int // Funds to transfer along along the transaction (nil = 0 = no funds)
GasPrice *big.Int // Gas price to use for the transaction execution (nil = gas price oracle)
GasLimit *big.Int // Gas limit to set for the transaction execution (nil = estimate + 10%)
Context context.Context // Network context to support cancellation and timeouts (nil = no timeout)
}
// BoundContract is the base wrapper object that reflects a contract on the
// Ethereum network. It contains a collection of methods that are used by the
// higher level contract bindings to operate.
type BoundContract struct {
address common.Address // Deployment address of the contract on the Ethereum blockchain
abi abi.ABI // Reflect based ABI to access the correct Ethereum methods
caller ContractCaller // Read interface to interact with the blockchain
transactor ContractTransactor // Write interface to interact with the blockchain
}
// NewBoundContract creates a low level contract interface through which calls
// and transactions may be made through.
func NewBoundContract(address common.Address, abi abi.ABI, caller ContractCaller, transactor ContractTransactor) *BoundContract {
return &BoundContract{
address: address,
abi: abi,
caller: caller,
transactor: transactor,
}
}
// DeployContract deploys a contract onto the Ethereum blockchain and binds the
// deployment address with a Go wrapper.
func DeployContract(opts *TransactOpts, abi abi.ABI, bytecode []byte, backend ContractBackend, params ...interface{}) (common.Address, *types.Transaction, *BoundContract, error) {
// Otherwise try to deploy the contract
c := NewBoundContract(common.Address{}, abi, backend, backend)
input, err := c.abi.Pack("", params...)
if err != nil {
return common.Address{}, nil, nil, err
}
tx, err := c.transact(opts, nil, append(bytecode, input...))
if err != nil {
return common.Address{}, nil, nil, err
}
c.address = crypto.CreateAddress(opts.From, tx.Nonce())
return c.address, tx, c, nil
}
// Call invokes the (constant) contract method with params as input values and
// sets the output to result. The result type might be a single field for simple
// returns, a slice of interfaces for anonymous returns and a struct for named
// returns.
func (c *BoundContract) Call(opts *CallOpts, result interface{}, method string, params ...interface{}) error {
// Don't crash on a lazy user
if opts == nil {
opts = new(CallOpts)
}
// Pack the input, call and unpack the results
input, err := c.abi.Pack(method, params...)
if err != nil {
return err
}
var (
msg = ethereum.CallMsg{From: opts.From, To: &c.address, Data: input}
ctx = ensureContext(opts.Context)
code []byte
output []byte
)
if opts.Pending {
pb, ok := c.caller.(PendingContractCaller)
if !ok {
return ErrNoPendingState
}
output, err = pb.PendingCallContract(ctx, msg)
if err == nil && len(output) == 0 {
// Make sure we have a contract to operate on, and bail out otherwise.
if code, err = pb.PendingCodeAt(ctx, c.address); err != nil {
return err
} else if len(code) == 0 {
return ErrNoCode
}
}
} else {
output, err = c.caller.CallContract(ctx, msg, nil)
if err == nil && len(output) == 0 {
// Make sure we have a contract to operate on, and bail out otherwise.
if code, err = c.caller.CodeAt(ctx, c.address, nil); err != nil {
return err
} else if len(code) == 0 {
return ErrNoCode
}
}
}
if err != nil {
return err
}
return c.abi.Unpack(result, method, output)
}
// Transact invokes the (paid) contract method with params as input values.
func (c *BoundContract) Transact(opts *TransactOpts, method string, params ...interface{}) (*types.Transaction, error) {
// Otherwise pack up the parameters and invoke the contract
input, err := c.abi.Pack(method, params...)
if err != nil {
return nil, err
}
return c.transact(opts, &c.address, input)
}
// Transfer initiates a plain transaction to move funds to the contract, calling
// its default method if one is available.
func (c *BoundContract) Transfer(opts *TransactOpts) (*types.Transaction, error) {
return c.transact(opts, &c.address, nil)
}
// transact executes an actual transaction invocation, first deriving any missing
// authorization fields, and then scheduling the transaction for execution.
func (c *BoundContract) transact(opts *TransactOpts, contract *common.Address, input []byte) (*types.Transaction, error) {
var err error
// Ensure a valid value field and resolve the account nonce
value := opts.Value
if value == nil {
value = new(big.Int)
}
var nonce uint64
if opts.Nonce == nil {
nonce, err = c.transactor.PendingNonceAt(ensureContext(opts.Context), opts.From)
if err != nil {
return nil, fmt.Errorf("failed to retrieve account nonce: %v", err)
}
} else {
nonce = opts.Nonce.Uint64()
}
// Figure out the gas allowance and gas price values
gasPrice := opts.GasPrice
if gasPrice == nil {
gasPrice, err = c.transactor.SuggestGasPrice(ensureContext(opts.Context))
if err != nil {
return nil, fmt.Errorf("failed to suggest gas price: %v", err)
}
}
gasLimit := opts.GasLimit
if gasLimit == nil {
// Gas estimation cannot succeed without code for method invocations
if contract != nil {
if code, err := c.transactor.PendingCodeAt(ensureContext(opts.Context), c.address); err != nil {
return nil, err
} else if len(code) == 0 {
return nil, ErrNoCode
}
}
// If the contract surely has code (or code is not needed), estimate the transaction
msg := ethereum.CallMsg{From: opts.From, To: contract, Value: value, Data: input}
gasLimit, err = c.transactor.EstimateGas(ensureContext(opts.Context), msg)
if err != nil {
return nil, fmt.Errorf("failed to estimate gas needed: %v", err)
}
}
// Create the transaction, sign it and schedule it for execution
var rawTx *types.Transaction
if contract == nil {
rawTx = types.NewContractCreation(nonce, value, gasLimit, gasPrice, input)
} else {
rawTx = types.NewTransaction(nonce, c.address, value, gasLimit, gasPrice, input)
}
if opts.Signer == nil {
return nil, errors.New("no signer to authorize the transaction with")
}
signedTx, err := opts.Signer(types.HomesteadSigner{}, opts.From, rawTx)
if err != nil {
return nil, err
}
if err := c.transactor.SendTransaction(ensureContext(opts.Context), signedTx); err != nil {
return nil, err
}
return signedTx, nil
}
func ensureContext(ctx context.Context) context.Context {
if ctx == nil {
return context.TODO()
}
return ctx
}
