// 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 ethclient provides a client for the Ethereum RPC API.
package ethclient
import (
"encoding/json"
"fmt"
"math/big"
"github.com/ethereum/go-ethereum"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/core/vm"
"github.com/ethereum/go-ethereum/rlp"
"github.com/ethereum/go-ethereum/rpc"
"golang.org/x/net/context"
)
// Client defines typed wrappers for the Ethereum RPC API.
type Client struct {
c *rpc.Client
}
// Dial connects a client to the given URL.
func Dial(rawurl string) (*Client, error) {
c, err := rpc.Dial(rawurl)
if err != nil {
return nil, err
}
return NewClient(c), nil
}
// NewClient creates a client that uses the given RPC client.
func NewClient(c *rpc.Client) *Client {
return &Client{c}
}
// Blockchain Access
// BlockByHash returns the given full block.
//
// Note that loading full blocks requires two requests. Use HeaderByHash
// if you don't need all transactions or uncle headers.
func (ec *Client) BlockByHash(ctx context.Context, hash common.Hash) (*types.Block, error) {
return ec.getBlock(ctx, "eth_getBlockByHash", hash, true)
}
// BlockByNumber returns a block from the current canonical chain. If number is nil, the
// latest known block is returned.
//
// Note that loading full blocks requires two requests. Use HeaderByNumber
// if you don't need all transactions or uncle headers.
func (ec *Client) BlockByNumber(ctx context.Context, number *big.Int) (*types.Block, error) {
return ec.getBlock(ctx, "eth_getBlockByNumber", toBlockNumArg(number), true)
}
type rpcBlock struct {
Hash common.Hash `json:"hash"`
Transactions []*types.Transaction `json:"transactions"`
UncleHashes []common.Hash `json:"uncles"`
}
func (ec *Client) getBlock(ctx context.Context, method string, args ...interface{}) (*types.Block, error) {
var raw json.RawMessage
err := ec.c.CallContext(ctx, &raw, method, args...)
if err != nil {
return nil, err
}
// Decode header and transactions.
var head *types.Header
var body rpcBlock
if err := json.Unmarshal(raw, &head); err != nil {
return nil, err
}
if err := json.Unmarshal(raw, &body); err != nil {
return nil, err
}
// Quick-verify transaction and uncle lists. This mostly helps with debugging the server.
if head.UncleHash == types.EmptyUncleHash && len(body.UncleHashes) > 0 {
return nil, fmt.Errorf("server returned non-empty uncle list but block header indicates no uncles")
}
if head.UncleHash != types.EmptyUncleHash && len(body.UncleHashes) == 0 {
return nil, fmt.Errorf("server returned empty uncle list but block header indicates uncles")
}
if head.TxHash == types.EmptyRootHash && len(body.Transactions) > 0 {
return nil, fmt.Errorf("server returned non-empty transaction list but block header indicates no transactions")
}
if head.TxHash != types.EmptyRootHash && len(body.Transactions) == 0 {
return nil, fmt.Errorf("server returned empty transaction list but block header indicates transactions")
}
// Load uncles because they are not included in the block response.
var uncles []*types.Header
if len(body.UncleHashes) > 0 {
uncles = make([]*types.Header, len(body.UncleHashes))
reqs := make([]rpc.BatchElem, len(body.UncleHashes))
for i := range reqs {
reqs[i] = rpc.BatchElem{
Method: "eth_getUncleByBlockHashAndIndex",
Args: []interface{}{body.Hash, fmt.Sprintf("%#x", i)},
Result: &uncles[i],
}
}
if err := ec.c.BatchCallContext(ctx, reqs); err != nil {
return nil, err
}
for i := range reqs {
if reqs[i].Error != nil {
return nil, reqs[i].Error
}
}
}
return types.NewBlockWithHeader(head).WithBody(body.Transactions, uncles), nil
}
// HeaderByHash returns the block header with the given hash.
func (ec *Client) HeaderByHash(ctx context.Context, hash common.Hash) (*types.Header, error) {
var head *types.Header
err := ec.c.CallContext(ctx, &head, "eth_getBlockByHash", hash, false)
return head, err
}
// HeaderByNumber returns a block header from the current canonical chain. If number is
// nil, the latest known header is returned.
func (ec *Client) HeaderByNumber(ctx context.Context, number *big.Int) (*types.Header, error) {
var head *types.Header
err := ec.c.CallContext(ctx, &head, "eth_getBlockByNumber", toBlockNumArg(number), false)
return head, err
}
// TransactionByHash returns the transaction with the given hash.
func (ec *Client) TransactionByHash(ctx context.Context, hash common.Hash) (*types.Transaction, error) {
var tx *types.Transaction
err := ec.c.CallContext(ctx, &tx, "eth_getTransactionByHash", hash)
if err == nil {
if _, r, _ := tx.RawSignatureValues(); r == nil {
return nil, fmt.Errorf("server returned transaction without signature")
}
}
return tx, err
}
// TransactionCount returns the total number of transactions in the given block.
func (ec *Client) TransactionCount(ctx context.Context, blockHash common.Hash) (uint, error) {
var num rpc.HexNumber
err := ec.c.CallContext(ctx, &num, "eth_getBlockTransactionCountByHash", blockHash)
return num.Uint(), err
}
// TransactionInBlock returns a single transaction at index in the given block.
func (ec *Client) TransactionInBlock(ctx context.Context, blockHash common.Hash, index uint) (*types.Transaction, error) {
var tx *types.Transaction
err := ec.c.CallContext(ctx, &tx, "eth_getTransactionByBlockHashAndIndex", blockHash, index)
if err == nil {
var signer types.Signer = types.HomesteadSigner{}
if tx.Protected() {
signer = types.NewEIP155Signer(tx.ChainId())
}
if _, r, _ := types.SignatureValues(signer, tx); r == nil {
return nil, fmt.Errorf("server returned transaction without signature")
}
}
return tx, err
}
// TransactionReceipt returns the receipt of a transaction by transaction hash.
// Note that the receipt is not available for pending transactions.
func (ec *Client) TransactionReceipt(ctx context.Context, txHash common.Hash) (*types.Receipt, error) {
var r *types.Receipt
err := ec.c.CallContext(ctx, &r, "eth_getTransactionReceipt", txHash)
if err == nil && r != nil && len(r.PostState) == 0 {
return nil, fmt.Errorf("server returned receipt without post state")
}
return r, err
}
func toBlockNumArg(number *big.Int) string {
if number == nil {
return "latest"
}
return fmt.Sprintf("%#x", number)
}
type rpcProgress struct {
StartingBlock rpc.HexNumber
CurrentBlock rpc.HexNumber
HighestBlock rpc.HexNumber
PulledStates rpc.HexNumber
KnownStates rpc.HexNumber
}
// SyncProgress retrieves the current progress of the sync algorithm. If there's
// no sync currently running, it returns nil.
func (ec *Client) SyncProgress(ctx context.Context) (*ethereum.SyncProgress, error) {
var raw json.RawMessage
if err := ec.c.CallContext(ctx, &raw, "eth_syncing"); err != nil {
return nil, err
}
// Handle the possible response types
var syncing bool
if err := json.Unmarshal(raw, &syncing); err == nil {
return nil, nil // Not syncing (always false)
}
var progress *rpcProgress
if err := json.Unmarshal(raw, &progress); err != nil {
return nil, err
}
return ðereum.SyncProgress{
StartingBlock: progress.StartingBlock.Uint64(),
CurrentBlock: progress.CurrentBlock.Uint64(),
HighestBlock: progress.HighestBlock.Uint64(),
PulledStates: progress.PulledStates.Uint64(),
KnownStates: progress.KnownStates.Uint64(),
}, nil
}
// SubscribeNewHead subscribes to notifications about the current blockchain head
// on the given channel.
func (ec *Client) SubscribeNewHead(ctx context.Context, ch chan<- *types.Header) (ethereum.Subscription, error) {
return ec.c.EthSubscribe(ctx, ch, "newHeads", map[string]struct{}{})
}
// State Access
// BalanceAt returns the wei balance of the given account.
// The block number can be nil, in which case the balance is taken from the latest known block.
func (ec *Client) BalanceAt(ctx context.Context, account common.Address, blockNumber *big.Int) (*big.Int, error) {
var result rpc.HexNumber
err := ec.c.CallContext(ctx, &result, "eth_getBalance", account, toBlockNumArg(blockNumber))
return (*big.Int)(&result), err
}
// StorageAt returns the value of key in the contract storage of the given account.
// The block number can be nil, in which case the value is taken from the latest known block.
func (ec *Client) StorageAt(ctx context.Context, account common.Address, key common.Hash, blockNumber *big.Int) ([]byte, error) {
var result rpc.HexBytes
err := ec.c.CallContext(ctx, &result, "eth_getStorageAt", account, key, toBlockNumArg(blockNumber))
return result, err
}
// CodeAt returns the contract code of the given account.
// The block number can be nil, in which case the code is taken from the latest known block.
func (ec *Client) CodeAt(ctx context.Context, account common.Address, blockNumber *big.Int) ([]byte, error) {
var result rpc.HexBytes
err := ec.c.CallContext(ctx, &result, "eth_getCode", account, toBlockNumArg(blockNumber))
return result, err
}
// NonceAt returns the account nonce of the given account.
// The block number can be nil, in which case the nonce is taken from the latest known block.
func (ec *Client) NonceAt(ctx context.Context, account common.Address, blockNumber *big.Int) (uint64, error) {
var result rpc.HexNumber
err := ec.c.CallContext(ctx, &result, "eth_getTransactionCount", account, toBlockNumArg(blockNumber))
return result.Uint64(), err
}
// Filters
// FilterLogs executes a filter query.
func (ec *Client) FilterLogs(ctx context.Context, q ethereum.FilterQuery) ([]vm.Log, error) {
var result []vm.Log
err := ec.c.CallContext(ctx, &result, "eth_getLogs", toFilterArg(q))
return result, err
}
// SubscribeFilterLogs subscribes to the results of a streaming filter query.
func (ec *Client) SubscribeFilterLogs(ctx context.Context, q ethereum.FilterQuery, ch chan<- vm.Log) (ethereum.Subscription, error) {
return ec.c.EthSubscribe(ctx, ch, "logs", toFilterArg(q))
}
func toFilterArg(q ethereum.FilterQuery) interface{} {
arg := map[string]interface{}{
"fromBlock": toBlockNumArg(q.FromBlock),
"toBlock": toBlockNumArg(q.ToBlock),
"addresses": q.Addresses,
"topics": q.Topics,
}
if q.FromBlock == nil {
arg["fromBlock"] = "0x0"
}
return arg
}
// Pending State
// PendingBalanceAt returns the wei balance of the given account in the pending state.
func (ec *Client) PendingBalanceAt(ctx context.Context, account common.Address) (*big.Int, error) {
var result rpc.HexNumber
err := ec.c.CallContext(ctx, &result, "eth_getBalance", account, "pending")
return (*big.Int)(&result), err
}
// PendingStorageAt returns the value of key in the contract storage of the given account in the pending state.
func (ec *Client) PendingStorageAt(ctx context.Context, account common.Address, key common.Hash) ([]byte, error) {
var result rpc.HexBytes
err := ec.c.CallContext(ctx, &result, "eth_getStorageAt", account, key, "pending")
return result, err
}
// PendingCodeAt returns the contract code of the given account in the pending state.
func (ec *Client) PendingCodeAt(ctx context.Context, account common.Address) ([]byte, error) {
var result rpc.HexBytes
err := ec.c.CallContext(ctx, &result, "eth_getCode", account, "pending")
return result, err
}
// PendingNonceAt returns the account nonce of the given account in the pending state.
// This is the nonce that should be used for the next transaction.
func (ec *Client) PendingNonceAt(ctx context.Context, account common.Address) (uint64, error) {
var result rpc.HexNumber
err := ec.c.CallContext(ctx, &result, "eth_getTransactionCount", account, "pending")
return result.Uint64(), err
}
// PendingTransactionCount returns the total number of transactions in the pending state.
func (ec *Client) PendingTransactionCount(ctx context.Context) (uint, error) {
var num rpc.HexNumber
err := ec.c.CallContext(ctx, &num, "eth_getBlockTransactionCountByNumber", "pending")
return num.Uint(), err
}
// TODO: SubscribePendingTransactions (needs server side)
// Contract Calling
// CallContract executes a message call transaction, which is directly executed in the VM
// of the node, but never mined into the blockchain.
//
// blockNumber selects the block height at which the call runs. It can be nil, in which
// case the code is taken from the latest known block. Note that state from very old
// blocks might not be available.
func (ec *Client) CallContract(ctx context.Context, msg ethereum.CallMsg, blockNumber *big.Int) ([]byte, error) {
var hex string
err := ec.c.CallContext(ctx, &hex, "eth_call", toCallArg(msg), toBlockNumArg(blockNumber))
if err != nil {
return nil, err
}
return common.FromHex(hex), nil
}
// PendingCallContract executes a message call transaction using the EVM.
// The state seen by the contract call is the pending state.
func (ec *Client) PendingCallContract(ctx context.Context, msg ethereum.CallMsg) ([]byte, error) {
var hex string
err := ec.c.CallContext(ctx, &hex, "eth_call", toCallArg(msg), "pending")
if err != nil {
return nil, err
}
return common.FromHex(hex), nil
}
// SuggestGasPrice retrieves the currently suggested gas price to allow a timely
// execution of a transaction.
func (ec *Client) SuggestGasPrice(ctx context.Context) (*big.Int, error) {
var hex rpc.HexNumber
if err := ec.c.CallContext(ctx, &hex, "eth_gasPrice"); err != nil {
return nil, err
}
return (*big.Int)(&hex), nil
}
// EstimateGas tries 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 (ec *Client) EstimateGas(ctx context.Context, msg ethereum.CallMsg) (*big.Int, error) {
var hex rpc.HexNumber
err := ec.c.CallContext(ctx, &hex, "eth_estimateGas", toCallArg(msg))
if err != nil {
return nil, err
}
return (*big.Int)(&hex), nil
}
// SendTransaction injects a signed transaction into the pending pool for execution.
//
// If the transaction was a contract creation use the TransactionReceipt method to get the
// contract address after the transaction has been mined.
func (ec *Client) SendTransaction(ctx context.Context, tx *types.Transaction) error {
data, err := rlp.EncodeToBytes(tx)
if err != nil {
return err
}
return ec.c.CallContext(ctx, nil, "eth_sendRawTransaction", common.ToHex(data))
}
func toCallArg(msg ethereum.CallMsg) interface{} {
arg := map[string]interface{}{
"from": msg.From,
"to": msg.To,
}
if len(msg.Data) > 0 {
arg["data"] = fmt.Sprintf("%#x", msg.Data)
}
if msg.Value != nil {
arg["value"] = fmt.Sprintf("%#x", msg.Value)
}
if msg.Gas != nil {
arg["gas"] = fmt.Sprintf("%#x", msg.Gas)
}
if msg.GasPrice != nil {
arg["gasPrice"] = fmt.Sprintf("%#x", msg.GasPrice)
}
return arg
}
