5.5 以太坊源码详解5
交易步骤
发起交易：制定目标地址和交易金额，以及gas和gaslimit
交易签名：使用账户的私钥对交易进行签名
提交交易：把交易添加到交易缓冲池中(会先对签名进行验证)
广播交易：通知EVM执行，同时把交易广播到其他节点
具体分析
1、发起交易
func (s *PublicTransactionPoolAPI) SendTransaction(ctx context.Context, args SendTxArgs) (common.Hash, error) {
// Look up the wallet containing the requested signer
account := accounts.Account{Address: args.From}
// 得到钱包
wallet, err := s.b.AccountManager().Find(account)
if err != nil {
return common.Hash{}, err
}
if args.Nonce == nil {
// Hold the addresse's mutex around signing to prevent concurrent assignment of
// the same nonce to multiple accounts.
s.nonceLock.LockAddr(args.From)
defer s.nonceLock.UnlockAddr(args.From)
}
// Set some sanity defaults and terminate on failure
if err := args.setDefaults(ctx, s.b); err != nil {
return common.Hash{}, err
}
// Assemble the transaction and sign with the wallet
tx := args.toTransaction()// 创建交易
var chainID *big.Int
if config := s.b.ChainConfig(); config.IsEIP155(s.b.CurrentBlock().Number()) {
chainID = config.ChainID
}
signed, err := wallet.SignTx(account, tx, chainID) // 对交易签名(接口函数)
if err != nil {
return common.Hash{}, err
}
return submitTransaction(ctx, s.b, signed) // 提交交易(到内存池中)
}2、创建交易
func (args *SendTxArgs) toTransaction() *types.Transaction {
var input []byte
if args.Data != nil {
input = *args.Data
} else if args.Input != nil {
input = *args.Input
}
if args.To == nil {
return types.NewContractCreation(uint64(*args.Nonce), (*big.Int)(args.Value), uint64(*args.Gas), (*big.Int)(args.GasPrice), input)
}
// 调用创建交易函数
return types.NewTransaction(uint64(*args.Nonce), *args.To, (*big.Int)(args.Value), uint64(*args.Gas), (*big.Int)(args.GasPrice), input)
}3、发送的交易结构
type SendTxArgs struct {
From common.Address `json:"from"`
To *common.Address `json:"to"`
Gas *hexutil.Uint64 `json:"gas"`
GasPrice *hexutil.Big `json:"gasPrice"`
Value *hexutil.Big `json:"value"`
Nonce *hexutil.Uint64 `json:"nonce"`
// We accept "data" and "input" for backwards-compatibility reasons. "input" is the
// newer name and should be preferred by clients.
Data *hexutil.Bytes `json:"data"`
Input *hexutil.Bytes `json:"input"`
}4、新建交易的内部实现
func newTransaction(nonce uint64, to *common.Address, amount *big.Int, gasLimit uint64, gasPrice *big.Int, data []byte) *Transaction {
if len(data) > 0 {
data = common.CopyBytes(data)
}
// 交易结构
d := txdata{
AccountNonce: nonce,
Recipient: to,
Payload: data,
Amount: new(big.Int),
GasLimit: gasLimit,
Price: new(big.Int),
V: new(big.Int),
R: new(big.Int),
S: new(big.Int),
}
if amount != nil {
d.Amount.Set(amount)
}
if gasPrice != nil {
d.Price.Set(gasPrice)
}
return &Transaction{data: d}
}5、交易签名
func (s *PublicTransactionPoolAPI) SignTransaction(ctx context.Context, args SendTxArgs) (*SignTransactionResult, error) {
if args.Gas == nil {
return nil, fmt.Errorf("gas not specified")
}
if args.GasPrice == nil {
return nil, fmt.Errorf("gasPrice not specified")
}
if args.Nonce == nil {
return nil, fmt.Errorf("nonce not specified")
}
if err := args.setDefaults(ctx, s.b); err != nil {
return nil, err
}
tx, err := s.sign(args.From, args.toTransaction())
if err != nil {
return nil, err
}
data, err := rlp.EncodeToBytes(tx)
if err != nil {
return nil, err
}
return &SignTransactionResult{data, tx}, nil
}
// sign is a helper function that signs a transaction with the private key of the given address.
func (s *PublicTransactionPoolAPI) sign(addr common.Address, tx *types.Transaction) (*types.Transaction, error) {
// Look up the wallet containing the requested signer
account := accounts.Account{Address: addr}
wallet, err := s.b.AccountManager().Find(account)
if err != nil {
return nil, err
}
// Request the wallet to sign the transaction
var chainID *big.Int
if config := s.b.ChainConfig(); config.IsEIP155(s.b.CurrentBlock().Number()) {
chainID = config.ChainID
}
return wallet.SignTx(account, tx, chainID)
}6、最终完成交易签名
func SignTx(tx *Transaction, s Signer, prv *ecdsa.PrivateKey) (*Transaction, error) {
h := s.Hash(tx)
sig, err := crypto.Sign(h[:], prv)
if err != nil {
return nil, err
}
return tx.WithSignature(s, sig)
}7、具体步骤
生成哈希
根据哈希值和私钥生成签名
把签名数据填充到交易实例中
8、提交交易到内存池中
func submitTransaction(ctx context.Context, b Backend, tx *types.Transaction) (common.Hash, error) {
if err := b.SendTx(ctx, tx); err != nil {
return common.Hash{}, err
}
if tx.To() == nil {
signer := types.MakeSigner(b.ChainConfig(), b.CurrentBlock().Number())
from, err := types.Sender(signer, tx)
if err != nil {
return common.Hash{}, err
}
addr := crypto.CreateAddress(from, tx.Nonce())
log.Info("Submitted contract creation", "fullhash", tx.Hash().Hex(), "contract", addr.Hex())
} else {
log.Info("Submitted transaction", "fullhash", tx.Hash().Hex(), "recipient", tx.To())
}
return tx.Hash(), nil //返回交易的哈希
}9、交易缓存池的结构体
type TxPool struct {
config TxPoolConfig
chainconfig *params.ChainConfig
chain blockChain
gasPrice *big.Int
txFeed event.Feed
scope event.SubscriptionScope
chainHeadCh chan ChainHeadEvent
chainHeadSub event.Subscription
signer types.Signer
mu sync.RWMutex
currentState *state.StateDB // Current state in the blockchain head
pendingState *state.ManagedState // Pending state tracking virtual nonces
currentMaxGas uint64 // Current gas limit for transaction caps
locals *accountSet // Set of local transaction to exempt from eviction rules
journal *txJournal // Journal of local transaction to back up to disk
pending map[common.Address]*txList // All currently processable transactions 当前等待处理的交易
queue map[common.Address]*txList // Queued but non-processable transactions
beats map[common.Address]time.Time // Last heartbeat from each known account
all *txLookup // All transactions to allow lookups 所有的交易列表
priced *txPricedList // All transactions sorted by price // 通过gas价格进行排序的交易列表,如果交易的gas price一样则按照nonce值从小到大排列
wg sync.WaitGroup // for shutdown sync
homestead bool
}10、默认的交易池配置
var DefaultTxPoolConfig = TxPoolConfig{
Journal: "transactions.rlp",
Rejournal: time.Hour,
PriceLimit: 1,
PriceBump: 10,
AccountSlots: 16, pending中每个账户存储的交易阈值
GlobalSlots: 4096, // 列表的最大长度
AccountQueue: 64, // queue中 每个账户允许存储的最大交易树
GlobalQueue: 1024,
Lifetime: 3 * time.Hour,
}11、提交交易的内部调用
func (b *EthAPIBackend) SendTx(ctx context.Context, signedTx *types.Transaction) error {
return b.eth.txPool.AddLocal(signedTx)
}12、添加到交易池中
func (pool *TxPool) addTx(tx *types.Transaction, local bool) error {
pool.mu.Lock()
defer pool.mu.Unlock()
// Try to inject the transaction and update any state
replace, err := pool.add(tx, local) // 判断是否应该把当前交易加入到交易列表中
if err != nil {
return err
}
// If we added a new transaction, run promotion checks and return
if !replace {
from, _ := types.Sender(pool.signer, tx) // already validated
pool.promoteExecutables([]common.Address{from}) // 选区一部分交易、放到pending中去
}
return nil
}13、add 内部实现
func (pool *TxPool) add(tx *types.Transaction, local bool) (bool, error) {
// If the transaction is already known, discard it
// 判断交易是否已经存在、有就直接退出
hash := tx.Hash()
if pool.all.Get(hash) != nil {
log.Trace("Discarding already known transaction", "hash", hash)
return false, fmt.Errorf("known transaction: %x", hash)
}
// If the transaction fails basic validation, discard it
// 如果校验交易有效性检查不通过，退出
if err := pool.validateTx(tx, local); err != nil {
log.Trace("Discarding invalid transaction", "hash", hash, "err", err)
invalidTxCounter.Inc(1)
return false, err
}
// If the transaction pool is full, discard underpriced transactions 如果交易池满了、找出一些价格比较低的推掉
if uint64(pool.all.Count()) >= pool.config.GlobalSlots+pool.config.GlobalQueue {
// If the new transaction is underpriced, don't accept it
if !local && pool.priced.Underpriced(tx, pool.locals) {
log.Trace("Discarding underpriced transaction", "hash", hash, "price", tx.GasPrice())
underpricedTxCounter.Inc(1)
return false, ErrUnderpriced
}
// New transaction is better than our worse ones, make room for it
drop := pool.priced.Discard(pool.all.Count()-int(pool.config.GlobalSlots+pool.config.GlobalQueue-1), pool.locals)
for _, tx := range drop {
log.Trace("Discarding freshly underpriced transaction", "hash", tx.Hash(), "price", tx.GasPrice())
underpricedTxCounter.Inc(1)
pool.removeTx(tx.Hash(), false)
}
}
// If the transaction is replacing an already pending one, do directly
from, _ := types.Sender(pool.signer, tx) // already validated
if list := pool.pending[from]; list != nil && list.Overlaps(tx) {
// Nonce already pending, check if required price bump is met
inserted, old := list.Add(tx, pool.config.PriceBump)
if !inserted {
pendingDiscardCounter.Inc(1)
return false, ErrReplaceUnderpriced
}
// New transaction is better, replace old one
if old != nil {
pool.all.Remove(old.Hash())
pool.priced.Removed()
pendingReplaceCounter.Inc(1)
}
pool.all.Add(tx)
pool.priced.Put(tx)
pool.journalTx(from, tx)
log.Trace("Pooled new executable transaction", "hash", hash, "from", from, "to", tx.To())
// We've directly injected a replacement transaction, notify subsystems
go pool.txFeed.Send(NewTxsEvent{types.Transactions{tx}})
return old != nil, nil
}
// New transaction isn't replacing a pending one, push into queue 把当前交易加入到队列里面去
replace, err := pool.enqueueTx(hash, tx)
if err != nil {
return false, err
}
// Mark local addresses and journal local transactions
if local {
pool.locals.add(from)
}
pool.journalTx(from, tx)
log.Trace("Pooled new future transaction", "hash", hash, "from", from, "to", tx.To())
return replace, nil
}14、交易有效性检查
func (pool *TxPool) validateTx(tx *types.Transaction, local bool) error {
// Heuristic limit, reject transactions over 32KB to prevent DOS attacks
if tx.Size() > 32*1024 {
return ErrOversizedData
}
// Transactions can't be negative. This may never happen using RLP decoded
// transactions but may occur if you create a transaction using the RPC.
if tx.Value().Sign() < 0 {
return ErrNegativeValue
}
// Ensure the transaction doesn't exceed the current block limit gas.
if pool.currentMaxGas < tx.Gas() {
return ErrGasLimit
}
// Make sure the transaction is signed properly
from, err := types.Sender(pool.signer, tx)
if err != nil {
return ErrInvalidSender
}
// Drop non-local transactions under our own minimal accepted gas price
local = local || pool.locals.contains(from) // account may be local even if the transaction arrived from the network
if !local && pool.gasPrice.Cmp(tx.GasPrice()) > 0 {
return ErrUnderpriced
}
// Ensure the transaction adheres to nonce ordering
if pool.currentState.GetNonce(from) > tx.Nonce() {
return ErrNonceTooLow
}
// Transactor should have enough funds to cover the costs
// cost == V + GP * GL
if pool.currentState.GetBalance(from).Cmp(tx.Cost()) < 0 {
return ErrInsufficientFunds
}
intrGas, err := IntrinsicGas(tx.Data(), tx.To() == nil, pool.homestead)
if err != nil {
return err
}
if tx.Gas() < intrGas {
return ErrIntrinsicGas
}
return nil
}15、具体步骤：
1：数据量必须小于32KB
2：交易金额必须非负
3：交易gas limit必须低于block 的gas limit
4：签名必须有效，能够解析出发送者的地址
5：交易的gas price 必须高于最低的gas price
6：账户余额必须大于交易金额加上交易燃料费
7：gas limit必须大于所需的gas 水平
8：交易的nonce值必须高于链上的nonce值，如果低于则说明该交易已经被打包过了
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