path: root/eth/bind.go

// 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/internal/ethapi"
    "github.com/ethereum/go-ethereum/rlp"
    "github.com/ethereum/go-ethereum/rpc"
    "golang.org/x/net/context"
)

// 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  *ethapi.PublicEthereumAPI        // Wrapper around the Ethereum object to access metadata
    bcapi *ethapi.PublicBlockChainAPI      // Wrapper around the blockchain to access chain data
    txapi *ethapi.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:  ethapi.NewPublicEthereumAPI(eth.apiBackend),
        bcapi: ethapi.NewPublicBlockChainAPI(eth.apiBackend),
        txapi: ethapi.NewPublicTransactionPoolAPI(eth.apiBackend),
    }
}

// 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(ctx context.Context, contract common.Address, pending bool) (bool, error) {
    if ctx == nil {
        ctx = context.Background()
    }
    block := rpc.LatestBlockNumber
    if pending {
        block = rpc.PendingBlockNumber
    }
    out, err := b.bcapi.GetCode(ctx, 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(ctx context.Context, contract common.Address, data []byte, pending bool) ([]byte, error) {
    if ctx == nil {
        ctx = context.Background()
    }
    // Convert the input args to the API spec
    args := ethapi.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(ctx, args, block)
    return common.FromHex(out), err
}

// PendingAccountNonce implements bind.ContractTransactor retrieving the current
// pending nonce associated with an account.
func (b *ContractBackend) PendingAccountNonce(ctx context.Context, account common.Address) (uint64, error) {
    if ctx == nil {
        ctx = context.Background()
    }
    out, err := b.txapi.GetTransactionCount(ctx, 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(ctx context.Context) (*big.Int, error) {
    if ctx == nil {
        ctx = context.Background()
    }
    return b.eapi.GasPrice(ctx)
}

// 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(ctx context.Context, sender common.Address, contract *common.Address, value *big.Int, data []byte) (*big.Int, error) {
    if ctx == nil {
        ctx = context.Background()
    }
    out, err := b.bcapi.EstimateGas(ctx, ethapi.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(ctx context.Context, tx *types.Transaction) error {
    if ctx == nil {
        ctx = context.Background()
    }
    raw, _ := rlp.EncodeToBytes(tx)
    _, err := b.txapi.SendRawTransaction(ctx, common.ToHex(raw))
    return err
}