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// Copyright 2016 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 eth
import (
"math/big"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/rlp"
"github.com/ethereum/go-ethereum/rpc"
)
// ContractBackend implements bind.ContractBackend with direct calls to Ethereum
// internals to support operating on contracts within subprotocols like eth and
// swarm.
//
// Internally this backend uses the already exposed API endpoints of the Ethereum
// object. These should be rewritten to internal Go method calls when the Go API
// is refactored to support a clean library use.
type ContractBackend struct {
eapi *PublicEthereumAPI // Wrapper around the Ethereum object to access metadata
bcapi *PublicBlockChainAPI // Wrapper around the blockchain to access chain data
txapi *PublicTransactionPoolAPI // Wrapper around the transaction pool to access transaction data
}
// NewContractBackend creates a new native contract backend using an existing
// Etheruem object.
func NewContractBackend(eth *Ethereum) *ContractBackend {
return &ContractBackend{
eapi: NewPublicEthereumAPI(eth),
bcapi: NewPublicBlockChainAPI(eth.chainConfig, eth.blockchain, eth.miner, eth.chainDb, eth.gpo, eth.eventMux, eth.accountManager),
txapi: NewPublicTransactionPoolAPI(eth),
}
}
// HasCode implements bind.ContractVerifier.HasCode by retrieving any code associated
// with the contract from the local API, and checking its size.
func (b *ContractBackend) HasCode(contract common.Address, pending bool) (bool, error) {
block := rpc.LatestBlockNumber
if pending {
block = rpc.PendingBlockNumber
}
out, err := b.bcapi.GetCode(contract, block)
return len(common.FromHex(out)) > 0, err
}
// ContractCall implements bind.ContractCaller executing an Ethereum contract
// call with the specified data as the input. The pending flag requests execution
// against the pending block, not the stable head of the chain.
func (b *ContractBackend) ContractCall(contract common.Address, data []byte, pending bool) ([]byte, error) {
// Convert the input args to the API spec
args := CallArgs{
To: &contract,
Data: common.ToHex(data),
}
block := rpc.LatestBlockNumber
if pending {
block = rpc.PendingBlockNumber
}
// Execute the call and convert the output back to Go types
out, err := b.bcapi.Call(args, block)
return common.FromHex(out), err
}
// PendingAccountNonce implements bind.ContractTransactor retrieving the current
// pending nonce associated with an account.
func (b *ContractBackend) PendingAccountNonce(account common.Address) (uint64, error) {
out, err := b.txapi.GetTransactionCount(account, rpc.PendingBlockNumber)
return out.Uint64(), err
}
// SuggestGasPrice implements bind.ContractTransactor retrieving the currently
// suggested gas price to allow a timely execution of a transaction.
func (b *ContractBackend) SuggestGasPrice() (*big.Int, error) {
return b.eapi.GasPrice(), nil
}
// EstimateGasLimit implements bind.ContractTransactor triing to estimate the gas
// needed to execute a specific transaction based on the current pending state of
// the backend blockchain. There is no guarantee that this is the true gas limit
// requirement as other transactions may be added or removed by miners, but it
// should provide a basis for setting a reasonable default.
func (b *ContractBackend) EstimateGasLimit(sender common.Address, contract *common.Address, value *big.Int, data []byte) (*big.Int, error) {
out, err := b.bcapi.EstimateGas(CallArgs{
From: sender,
To: contract,
Value: *rpc.NewHexNumber(value),
Data: common.ToHex(data),
})
return out.BigInt(), err
}
// SendTransaction implements bind.ContractTransactor injects the transaction
// into the pending pool for execution.
func (b *ContractBackend) SendTransaction(tx *types.Transaction) error {
raw, _ := rlp.EncodeToBytes(tx)
_, err := b.txapi.SendRawTransaction(common.ToHex(raw))
return err
}
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