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client.go
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client.go
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package bridge
import (
"context"
"errors"
"fmt"
"math/big"
"path/filepath"
"sync"
"time"
"github.com/ethereum/go-ethereum/light"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core"
tfeth "github.com/threefoldfoundation/tft-stellar/eth-bridge/api"
"github.com/ethereum/go-ethereum/accounts"
"github.com/ethereum/go-ethereum/accounts/keystore"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/eth"
"github.com/ethereum/go-ethereum/eth/downloader"
"github.com/ethereum/go-ethereum/ethclient"
"github.com/ethereum/go-ethereum/ethstats"
"github.com/ethereum/go-ethereum/les"
"github.com/ethereum/go-ethereum/node"
"github.com/ethereum/go-ethereum/p2p"
"github.com/ethereum/go-ethereum/p2p/enode"
"github.com/ethereum/go-ethereum/params"
)
// LightClient creates a light client that can be used to interact with the Ethereum network,
// for ERC20 purposes. By default it is read-only, in order to also write to the network,
// you'll need load an account using the LoadAccount method.
type LightClient struct {
*ethclient.Client // Client connection to the Ethereum chain
stack *node.Node
lesc *les.LightEthereum
datadir string
// optional account info
accountLock sync.RWMutex
account *clientAccountInfo
}
type clientAccountInfo struct {
keystore *keystore.KeyStore // Keystore containing the signing info
account accounts.Account // Account funding the bridge requests
}
// LightClientConfig combines all configuration required for
// creating and configuring a LightClient.
type LightClientConfig struct {
Port uint16
DataDir string
BootstrapNodes []*enode.Node
NetworkName string
NetworkID uint64
GenesisBlock *core.Genesis
}
func (lccfg *LightClientConfig) validate() error {
if lccfg.Port == 0 {
return errors.New("invalid LightClientConfig: no port defined")
}
if lccfg.DataDir == "" {
return errors.New("invalid LightClientConfig: no data directory defined")
}
if len(lccfg.BootstrapNodes) == 0 {
return errors.New("invalid LightClientConfig: no bootstrap nodes defined")
}
if lccfg.NetworkName == "" {
return errors.New("invalid LightClientConfig: no network name defined")
}
if lccfg.NetworkID == 0 {
return errors.New("invalid LightClientConfig: no network ID defined")
}
if lccfg.GenesisBlock == nil {
return errors.New("invalid LightClientConfig: no genesis block defined")
}
return nil
}
func addPeers(ethNode *node.Node, peers []*enode.Node) {
for _, peer := range peers {
old, err := enode.ParseV4(peer.String())
if err != nil {
ethNode.Server().AddPeer(old)
}
}
}
// NewLightClient creates a new light client that can be used to interact with the ETH network.
// See `LightClient` for more information.
func NewLightClient(lccfg LightClientConfig) (*LightClient, error) {
// validate the cfg, as to provide better error reporting for obvious errors
err := lccfg.validate()
if err != nil {
return nil, err
}
// separate saved data per network
datadir := filepath.Join(lccfg.DataDir, lccfg.NetworkName)
// Assemble the raw devp2p protocol stack
stack, err := node.New(&node.Config{
Name: "chain",
Version: params.VersionWithMeta,
DataDir: datadir,
P2P: p2p.Config{
NAT: nil,
NoDiscovery: false,
DiscoveryV5: true,
ListenAddr: fmt.Sprintf(":%d", lccfg.Port),
MaxPeers: 25,
BootstrapNodes: lccfg.BootstrapNodes,
},
})
if err != nil {
return nil, err
}
// Assemble the Ethereum light client protocol
var lesc *les.LightEthereum
if err := stack.Register(func(ctx *node.ServiceContext) (node.Service, error) {
cfg := eth.DefaultConfig
cfg.Ethash.DatasetDir = filepath.Join(datadir, "ethash")
cfg.SyncMode = downloader.LightSync
cfg.NetworkId = lccfg.NetworkID
cfg.Genesis = lccfg.GenesisBlock
var err error
lesc, err = les.New(ctx, &cfg)
return lesc, err
}); err != nil {
return nil, err
}
stats := "" // Todo: should this stay in here?
// Assemble the ethstats monitoring and reporting service'
if stats != "" {
if err := stack.Register(func(ctx *node.ServiceContext) (node.Service, error) {
var serv *les.LightEthereum
ctx.Service(&serv)
return ethstats.New(stats, nil, serv)
}); err != nil {
return nil, err
}
}
// Boot up the client and ensure it connects to bootnodes
if err := stack.Start(); err != nil {
return nil, err
}
// add bootnodes
addPeers(stack, lccfg.BootstrapNodes)
// Attach to the client and retrieve any interesting metadata
api, err := stack.Attach()
if err != nil {
stack.Stop()
return nil, err
}
// create a client for the stack
client := ethclient.NewClient(api)
// return created light client
return &LightClient{
Client: client,
stack: stack,
lesc: lesc,
datadir: datadir,
}, nil
}
// Close terminates the Ethereum connection and tears down the stack.
func (lc *LightClient) Close() error {
return lc.stack.Stop()
}
// FetchTransaction fetches a transaction from a remote peer using its block hash and tx index (within that block).
// Together with a found transactions it also returns the confirmations available for that Tx.
func (lc *LightClient) FetchTransaction(ctx context.Context, blockHash common.Hash, txHash common.Hash) (*types.Transaction, uint64, error) {
block, err := lc.lesc.ApiBackend.BlockByHash(ctx, blockHash)
if err != nil {
return nil, 0, err
}
chainHeight := lc.lesc.BlockChain().CurrentHeader().Number.Uint64()
blockHeight := block.Header().Number.Uint64()
if blockHeight > chainHeight {
return nil, 0, fmt.Errorf(
"Tx %q is in block %d while the current chain height is only %d",
txHash.String(), blockHeight, chainHeight)
}
tx := block.Transaction(txHash)
if tx == nil {
return nil, 0, errors.New("transaction could not be found")
}
confirmations := (chainHeight - blockHeight) + 1
return tx, confirmations, nil
}
// LoadAccount loads an account into this light client,
// allowing writeable operations using the loaded account.
// An error is returned in case no account could be loaded.
func (lc *LightClient) LoadAccount(accountJSON, accountPass string) error {
// create keystore
ks, err := tfeth.InitializeKeystore(lc.datadir, accountJSON, accountPass)
if err != nil {
return err
}
lc.accountLock.Lock()
lc.account = &clientAccountInfo{
keystore: ks,
account: ks.Accounts()[0],
}
lc.accountLock.Unlock()
return nil
}
var (
// ErrNoAccountLoaded is an error returned for all Light Client methods
// that require an account and for which no account is loaded.
ErrNoAccountLoaded = errors.New("no account was loaded into the light client")
)
// AccountBalanceAt returns the balance for the account at the given block height.
func (lc *LightClient) AccountBalanceAt(ctx context.Context, blockNumber *big.Int) (*big.Int, error) {
lc.accountLock.RLock()
defer lc.accountLock.RUnlock()
if lc.account == nil {
return nil, ErrNoAccountLoaded
}
return lc.Client.BalanceAt(ctx, lc.account.account.Address, blockNumber)
}
// SignTx signs a given traction with the loaded account, returning the signed transaction and no error on success.
func (lc *LightClient) SignTx(tx *types.Transaction, chainID *big.Int) (*types.Transaction, error) {
lc.accountLock.RLock()
defer lc.accountLock.RUnlock()
if lc.account == nil {
return nil, ErrNoAccountLoaded
}
return lc.account.keystore.SignTx(lc.account.account, tx, chainID)
}
// AccountAddress returns the address of the loaded account,
// returning an error only if no account was loaded.
func (lc *LightClient) AccountAddress() (common.Address, error) {
lc.accountLock.RLock()
defer lc.accountLock.RUnlock()
var addr common.Address
if lc.account == nil {
return addr, ErrNoAccountLoaded
}
copy(addr[:], lc.account.account.Address[:])
return addr, nil
}
// Synchronising returns a boolean if the ethereum client is syncing or not
func (lc *LightClient) Synchronising() bool {
downloader := lc.lesc.Downloader()
return downloader != nil && downloader.Synchronising()
}
// IsNoPeerErr checks if an error is means an ethereum client could not execute
// a call because it has no valid peers
func IsNoPeerErr(err error) bool {
return err == light.ErrNoPeers
}
// GetStatus implements ERC20TransactionValidator.GetStatus
func (lc *LightClient) GetStatus() (*ERC20SyncStatus, error) {
downloader := lc.lesc.Downloader()
if downloader == nil {
return nil, errors.New("Downloader is not available")
}
syncStatus := downloader.Progress()
status := ERC20SyncStatus{
StartingBlock: syncStatus.StartingBlock,
CurrentBlock: syncStatus.CurrentBlock,
HighestBlock: syncStatus.HighestBlock,
}
if status.CurrentBlock > status.HighestBlock {
status.HighestBlock = status.CurrentBlock
}
return &status, nil
}
// GetBalanceInfo returns bridge ethereum address and balance
func (lc *LightClient) GetBalanceInfo() (*ERC20BalanceInfo, error) {
lc.accountLock.RLock()
defer lc.accountLock.RUnlock()
var addr common.Address
if lc.account == nil {
return nil, ErrNoAccountLoaded
}
copy(addr[:], lc.account.account.Address[:])
balance, err := lc.Client.BalanceAt(context.Background(), addr, nil)
if err != nil {
return nil, err
}
return &ERC20BalanceInfo{
Balance: balance,
Address: lc.account.account.Address,
}, nil
}
func (lc *LightClient) Wait(ctx context.Context) error {
// wait until (light) client is fully synced
downloader := lc.lesc.Downloader()
for {
progress := downloader.Progress()
if progress.HighestBlock == 0 {
log.Info(
"LightClient needs to start to sync",
"current_block", progress.CurrentBlock, "peers", lc.stack.Server().Peers())
} else if downloader.Synchronising() || progress.CurrentBlock < progress.HighestBlock {
log.Debug(
"LightClient is still syncing, waiting 10 seconds...",
"current_block", progress.CurrentBlock, "highest_block", progress.HighestBlock)
} else {
log.Info(
"LightClient is synced",
"current_block", progress.CurrentBlock, "highest_block", progress.HighestBlock, "starting_block", progress.StartingBlock)
break
}
select {
case <-time.After(time.Second * 10):
case <-ctx.Done():
return errors.New("failed to create light client, call got cancelled")
}
}
return nil
}
// ERC20SyncStatus provides a definition for the current status of the ehtereum network sync.
type ERC20SyncStatus struct {
StartingBlock uint64 `json:"startingblock"`
CurrentBlock uint64 `json:"currentblock"`
HighestBlock uint64 `json:"highestblock"`
}
// ERC20BalanceInfo provides a definition for the ethereum bridge address balance
type ERC20BalanceInfo struct {
Balance *big.Int `json:"balance"`
Address common.Address `json:"address"`
}