## 1.personal.newAccount创建账户方法
用户在控制台输入personal.newAccount会创建一个新的账户，会进入到ethapi.api中的newAccount方法中，这个方法会返回一个地址。
```
func (s *PrivateAccountAPI) NewAccount(password string) (common.Address, error) {
acc, err := fetchKeystore(s.am).NewAccount(password)
if err == nil {
return acc.Address, nil
}
return common.Address{}, err
}
```
创建账户过程中，首先会通过账户管理系统（account manager）来获取Keystore，然后通过椭圆加密算法产生公私钥对，并获取地址
```
func newKey(rand io.Reader) (*Key, error) {
privateKeyECDSA, err := ecdsa.GenerateKey(crypto.S256(), rand)
if err != nil {
return nil, err
}
return newKeyFromECDSA(privateKeyECDSA), nil
}
```
在获取到公私钥对后，会对用户输入的密码进行加密，并保存入文件。
```
func (ks keyStorePassphrase) StoreKey(filename string, key *Key, auth string) error {
keyjson, err := EncryptKey(key, auth, ks.scryptN, ks.scryptP)
if err != nil {
return err
}
return writeKeyFile(filename, keyjson)
}
```
在保存文件的同时，会将新创建的账户加入到缓存中。
```
func (ks *KeyStore) NewAccount(passphrase string) (accounts.Account, error) {
_, account, err := storeNewKey(ks.storage, crand.Reader, passphrase)
if err != nil {
return accounts.Account{}, err
}
// Add the account to the cache immediately rather
// than waiting for file system notifications to pick it up.
ks.cache.add(account)
ks.refreshWallets()
return account, nil
}
```
## 2.personal.listAccounts列出所有账户方法
用户在控制台输入personal.listAccounts，会进入到ethapi.api中的listAccounts方法中，这个方法会从用户管理中读取所有钱包信息，返回所有注册钱包下的所有地址信息。
```
func (s *PrivateAccountAPI) ListAccounts() []common.Address {
addresses := make([]common.Address, 0) // return [] instead of nil if empty
for _, wallet := range s.am.Wallets() {
for _, account := range wallet.Accounts() {
addresses = append(addresses, account.Address)
}
}
return addresses
}
```
## 3.eth.sendTransaction
sendTransaction经过RPC调用之后，最终会调用ethapi.api.go中的sendTransaction方法。
```
// SendTransaction will create a transaction from the given arguments and
// tries to sign it with the key associated with args.To. If the given passwd isn't
// able to decrypt the key it fails.
func (s *PrivateAccountAPI) SendTransaction(ctx context.Context, args SendTxArgs, passwd string) (common.Hash, error) {
// Look up the wallet containing the requested signer
account := accounts.Account{Address: args.From}
wallet, err := s.am.Find(account)
if err != nil {
return common.Hash{}, err
}
//对于每一个账户，Nonce会随着转账数的增加而增加，这个参数主要是为了防止双花攻击。
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()
...
```
这个方法利用传入的参数from构造一个account，表示转出方。接着会通过账户管理系统accountManager获得该账户的钱包（wallet）。
am.Find方法会从账户管理系统中对钱包进行遍历，找到包含这个account的钱包。
```
// Find attempts to locate the wallet corresponding to a specific account. Since
// accounts can be dynamically added to and removed from wallets, this method has
// a linear runtime in the number of wallets.
func (am *Manager) Find(account Account) (Wallet, error) {
am.lock.RLock()
defer am.lock.RUnlock()
for _, wallet := range am.wallets {
if wallet.Contains(account) {
return wallet, nil
}
}
return nil, ErrUnknownAccount
}
```
接下来会调用setDefaults方法设置一些交易的默认值。如果没有设置Gas，GasPrice，Nonce等，那么它们将会被设置为默认值。
当交易的这些参数都设置好之后，会利用toTransaction方法创建一笔交易。
```
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)
}
return types.NewTransaction(uint64(*args.Nonce), *args.To, (*big.Int)(args.Value), uint64(*args.Gas), (*big.Int)(args.GasPrice), input)
}
```
这里会对传入的交易信息的to参数进行判断。如果没有to值，那么这是一笔合约转账；而如果有to值，那么就是发起的一笔转账。最终，代码会调用NewTransaction创建一笔交易信息。
```
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)
}
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}
}
```
这里就是填充了交易结构体中的一些参数，来创建一个交易。到这里，我们的交易就已经创建成功了。
回到sendTransaction方法中，此时我们已经创建好了一笔交易，接着我们获取区块链的配置信息，检查是否是EIP155的配置，并获取链ID。
```
...
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)
if err != nil {
return common.Hash{}, err
}
return submitTransaction(ctx, s.b, signed)
}
```
接下来就要对这笔交易签名来确保这笔交易的真实有效。这里调用SignTx实现签名。
```
// SignTx signs the given transaction with the requested account.
func (ks *KeyStore) SignTx(a accounts.Account, tx *types.Transaction, chainID *big.Int) (*types.Transaction, error) {
// Look up the key to sign with and abort if it cannot be found
ks.mu.RLock()
defer ks.mu.RUnlock()
unlockedKey, found := ks.unlocked[a.Address]
if !found {
return nil, ErrLocked
}
// Depending on the presence of the chain ID, sign with EIP155 or homestead
if chainID != nil {
return types.SignTx(tx, types.NewEIP155Signer(chainID), unlockedKey.PrivateKey)
}
return types.SignTx(tx, types.HomesteadSigner{}, unlockedKey.PrivateKey)
}
```
这里首先我们先验证账户是否已解锁。若没有解锁，则直接则异常退出。接下来我们检查chainID，判断是使用哪一种签名的方式,调用SignTx方法进行签名。
```
// SignTx signs the transaction using the given signer and private key
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)
}
```
在签名时，首先获取交易的RLP哈希值，然后用传入的私钥进行椭圆加密。接着调用WithSignature方法进行初始化。
进行到这里，我们交易的签名已经完成，并且封装成为一个带签名的交易。
然后，我们就需要将这笔交易提交出去。调用SubmitTransaction方法提交交易。
```
// submitTransaction is a helper function that submits tx to txPool and logs a message.
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
}
```
submitTransaction方法会将交易发送给backend进行处理，返回经过签名后的交易的hash值。这里主要是SendTx方法对交易进行处理。
sendTx方法会将参数转给txpool的Addlocal方法进行处理，而AddLocal方法会将该笔交易放入到交易池中进行等待。这里我们看将交易放入到交易池中的方法。
```
// addTx enqueues a single transaction into the pool if it is valid.
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)
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})
}
return nil
}
```
这里一共有两部操作，第一步操作是调用add方法将交易放入到交易池中，第二步是判断replace参数。如果该笔交易合法并且交易原来不存在在交易池中，则执行promoteExecutables方法，将可处理的交易变为待处理（pending）。
首先看第一步add方法。
```
// add validates a transaction and inserts it into the non-executable queue for
// later pending promotion and execution. If the transaction is a replacement for
// an already pending or queued one, it overwrites the previous and returns this
// so outer code doesn't uselessly call promote.
//
// If a newly added transaction is marked as local, its sending account will be
// whitelisted, preventing any associated transaction from being dropped out of
// the pool due to pricing constraints.
func (pool *TxPool) add(tx *types.Transaction, local bool) (bool, error) {
// If the transaction is already known, discard it
hash := tx.Hash()
if pool.all[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
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
if uint64(len(pool.all)) >= pool.config.GlobalSlots+pool.config.GlobalQueue {
// If the new transaction is underpriced, don't accept it
if 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(len(pool.all)-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())
}
}
// 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 {
delete(pool.all, old.Hash())
pool.priced.Removed()
pendingReplaceCounter.Inc(1)
}
pool.all[tx.Hash()] = 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(TxPreEvent{tx})
return old != nil, nil
}
// New transaction isn't replacing a pending one, push into queue
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
}
```
这个方法主要执行以下操作：
1.检查交易池是否含有这笔交易，如果有这笔交易，则异常退出。
2.调用validateTx方法对交易的合法性进行验证。如果是非法的交易，则异常退出。
3.接下来判断交易池是否超过容量。
<1>如果超过容量，并且该笔交易的费用低于当前交易池中列表的最小值，则拒绝这一笔交易。
<2>如果超过容量，并且该笔交易的费用比当前交易池中列表最小值高，那么从交易池中移除交易费用最低的交易，为当前这一笔交易留出空间。
4.接着继续调用Overlaps方法检查该笔交易的Nonce值，确认该用户下的交易是否存在该笔交易。
<1>如果已经存在这笔交易，则删除之前的交易，并将该笔交易放入交易池中，然后返回。
<2>如果不存在，则调用enqueueTx将该笔交易放入交易池中。如果交易是本地发出的，则将发送者保存在交易池的local中。
接下来看看validateTx方法会怎样验证交易的合法性。
```
// validateTx checks whether a transaction is valid according to the consensus
// rules and adheres to some heuristic limits of the local node (price and size).
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
}
```
validateTx会验证一笔交易的以下几个特性：
1.首先验证这笔交易的大小，如果大于32kb则拒绝这笔交易，这样主要是为了防止DDOS攻击。
2.接着验证转账金额。如果金额小于0则拒绝这笔交易。
3.这笔交易的gas不能超过交易池的gas上限。
4.验证这笔交易的签名是否合法。
5.如果这笔交易不是来自本地并且这笔交易的gas小于当前交易池中的gas，则拒绝这笔交易。
6.当前用户的nonce如果大于这笔交易的nonce，则拒绝这笔交易。
7.当前用户的余额是否充足，如果不充足则拒绝该笔交易。
8.验证这笔交易的固有花费，如果小于交易池的gas，则拒绝该笔交易。
以上就是在进行交易验证时所需验证的参数。这一系列的验证操作结束后，回到addTx的第二步。
会判断replace。如果replace是false，则会执行promoteExecutables方法。
promoteExecutables会将所有可处理的交易放入pending区，并移除所有非法的交易。
```
// promoteExecutables moves transactions that have become processable from the
// future queue to the set of pending transactions. During this process, all
// invalidated transactions (low nonce, low balance) are deleted.
func (pool *TxPool) promoteExecutables(accounts []common.Address) {
// Gather all the accounts potentially needing updates
if accounts == nil {
accounts = make([]common.Address, 0, len(pool.queue))
for addr := range pool.queue {
accounts = append(accounts, addr)
}
}
// Iterate over all accounts and promote any executable transactions
for _, addr := range accounts {
list := pool.queue[addr]
if list == nil {
continue // Just in case someone calls with a non existing account
}
// Drop all transactions that are deemed too old (low nonce)
for _, tx := range list.Forward(pool.currentState.GetNonce(addr)) {
hash := tx.Hash()
log.Trace("Removed old queued transaction", "hash", hash)
delete(pool.all, hash)
pool.priced.Removed()
}
// Drop all transactions that are too costly (low balance or out of gas)
drops, _ := list.Filter(pool.currentState.GetBalance(addr), pool.currentMaxGas)
for _, tx := range drops {
hash := tx.Hash()
log.Trace("Removed unpayable queued transaction", "hash", hash)
delete(pool.all, hash)
pool.priced.Removed()
queuedNofundsCounter.Inc(1)
}
// Gather all executable transactions and promote them
for _, tx := range list.Ready(pool.pendingState.GetNonce(addr)) {
hash := tx.Hash()
log.Trace("Promoting queued transaction", "hash", hash)
pool.promoteTx(addr, hash, tx)
}
// Drop all transactions over the allowed limit
if !pool.locals.contains(addr) {
for _, tx := range list.Cap(int(pool.config.AccountQueue)) {
hash := tx.Hash()
delete(pool.all, hash)
pool.priced.Removed()
queuedRateLimitCounter.Inc(1)
log.Trace("Removed cap-exceeding queued transaction", "hash", hash)
}
}
// Delete the entire queue entry if it became empty.
if list.Empty() {
delete(pool.queue, addr)
}
}
// If the pending limit is overflown, start equalizing allowances
pending := uint64(0)
for _, list := range pool.pending {
pending += uint64(list.Len())
}
if pending > pool.config.GlobalSlots {
pendingBeforeCap := pending
// Assemble a spam order to penalize large transactors first
spammers := prque.New()
for addr, list := range pool.pending {
// Only evict transactions from high rollers
if !pool.locals.contains(addr) && uint64(list.Len()) > pool.config.AccountSlots {
spammers.Push(addr, float32(list.Len()))
}
}
// Gradually drop transactions from offenders
offenders := []common.Address{}
for pending > pool.config.GlobalSlots && !spammers.Empty() {
// Retrieve the next offender if not local address
offender, _ := spammers.Pop()
offenders = append(offenders, offender.(common.Address))
// Equalize balances until all the same or below threshold
if len(offenders) > 1 {
// Calculate the equalization threshold for all current offenders
threshold := pool.pending[offender.(common.Address)].Len()
// Iteratively reduce all offenders until below limit or threshold reached
for pending > pool.config.GlobalSlots && pool.pending[offenders[len(offenders)-2]].Len() > threshold {
for i := 0; i < len(offenders)-1; i++ {
list := pool.pending[offenders[i]]
for _, tx := range list.Cap(list.Len() - 1) {
// Drop the transaction from the global pools too
hash := tx.Hash()
delete(pool.all, hash)
pool.priced.Removed()
// Update the account nonce to the dropped transaction
if nonce := tx.Nonce(); pool.pendingState.GetNonce(offenders[i]) > nonce {
pool.pendingState.SetNonce(offenders[i], nonce)
}
log.Trace("Removed fairness-exceeding pending transaction", "hash", hash)
}
pending--
}
}
}
}
// If still above threshold, reduce to limit or min allowance
if pending > pool.config.GlobalSlots && len(offenders) > 0 {
for pending > pool.config.GlobalSlots && uint64(pool.pending[offenders[len(offenders)-1]].Len()) > pool.config.AccountSlots {
for _, addr := range offenders {
list := pool.pending[addr]
for _, tx := range list.Cap(list.Len() - 1) {
// Drop the transaction from the global pools too
hash := tx.Hash()
delete(pool.all, hash)
pool.priced.Removed()
// Update the account nonce to the dropped transaction
if nonce := tx.Nonce(); pool.pendingState.GetNonce(addr) > nonce {
pool.pendingState.SetNonce(addr, nonce)
}
log.Trace("Removed fairness-exceeding pending transaction", "hash", hash)
}
pending--
}
}
}
pendingRateLimitCounter.Inc(int64(pendingBeforeCap - pending))
}
// If we've queued more transactions than the hard limit, drop oldest ones
queued := uint64(0)
for _, list := range pool.queue {
queued += uint64(list.Len())
}
if queued > pool.config.GlobalQueue {
// Sort all accounts with queued transactions by heartbeat
addresses := make(addresssByHeartbeat, 0, len(pool.queue))
for addr := range pool.queue {
if !pool.locals.contains(addr) { // don't drop locals
addresses = append(addresses, addressByHeartbeat{addr, pool.beats[addr]})
}
}
sort.Sort(addresses)
// Drop transactions until the total is below the limit or only locals remain
for drop := queued - pool.config.GlobalQueue; drop > 0 && len(addresses) > 0; {
addr := addresses[len(addresses)-1]
list := pool.queue[addr.address]
addresses = addresses[:len(addresses)-1]
// Drop all transactions if they are less than the overflow
if size := uint64(list.Len()); size <= drop {
for _, tx := range list.Flatten() {
pool.removeTx(tx.Hash())
}
drop -= size
queuedRateLimitCounter.Inc(int64(size))
continue
}
// Otherwise drop only last few transactions
txs := list.Flatten()
for i := len(txs) - 1; i >= 0 && drop > 0; i-- {
pool.removeTx(txs[i].Hash())
drop--
queuedRateLimitCounter.Inc(1)
}
}
}
}
```
这个方法首先会迭代所有当前账户的交易，检查当前交易的nonce。如果nonce太低，则删除该笔交易。（list.Forward方法）
接下来检查余额不足或者gas不足的交易并删除。（list.Filter方法）
然后将剩余的交易状态更新为pending并放在pending集合中。然后将当前消息池该用户的nonce值+1，接着广播TxPreEvent事件，告诉他们本地有一笔新的合法交易等待处理。（pool.promoteTx方法）
接着检查消息池的pending列表是否超过容量，如果超过将进行扩容操作。如果一个账户进行的状态超过限制，从交易池中删除最先添加的交易。
在promoteExecutable中有一个promoteTx方法，这个方法是将交易防区pending区方法中。在promoteTx方法中，最后一步执行的是一个Send方法。
这个Send方法会同步将pending区的交易广播至它所连接到的节点，并返回通知到的节点的数量。
然后被通知到的节点继续通知到它添加的节点，继而广播至全网。
至此，发送交易就结束了。此时交易池中的交易等待挖矿打包处理。
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