package eth
// XXX Fair warning, most of the code is re-used from the old protocol. Please be aware that most of this will actually change
// The idea is that most of the calls within the protocol will become synchronous.
// Block downloading and block processing will be complete seperate processes
/*
# Possible scenarios
// Synching scenario
// Use the best peer to synchronise
blocks, err := pm.downloader.Synchronise()
if err != nil {
// handle
break
}
pm.chainman.InsertChain(blocks)
// Receiving block with known parent
if parent_exist {
if err := pm.chainman.InsertChain(block); err != nil {
// handle
break
}
pm.BroadcastBlock(block)
}
// Receiving block with unknown parent
blocks, err := pm.downloader.SynchroniseWithPeer(peer)
if err != nil {
// handle
break
}
pm.chainman.InsertChain(blocks)
*/
import (
"fmt"
"math"
"math/big"
"sync"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/eth/downloader"
"github.com/ethereum/go-ethereum/event"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
"github.com/ethereum/go-ethereum/p2p"
"github.com/ethereum/go-ethereum/rlp"
)
const (
peerCountTimeout = 12 * time.Second // Amount of time it takes for the peer handler to ignore minDesiredPeerCount
minDesiredPeerCount = 5 // Amount of peers desired to start syncing
)
func errResp(code errCode, format string, v ...interface{}) error {
return fmt.Errorf("%v - %v", code, fmt.Sprintf(format, v...))
}
type hashFetcherFn func(common.Hash) error
type blockFetcherFn func([]common.Hash) error
// extProt is an interface which is passed around so we can expose GetHashes and GetBlock without exposing it to the rest of the protocol
// extProt is passed around to peers which require to GetHashes and GetBlocks
type extProt struct {
getHashes hashFetcherFn
getBlocks blockFetcherFn
}
func (ep extProt) GetHashes(hash common.Hash) error { return ep.getHashes(hash) }
func (ep extProt) GetBlock(hashes []common.Hash) error { return ep.getBlocks(hashes) }
type ProtocolManager struct {
protVer, netId int
txpool txPool
chainman *core.ChainManager
downloader *downloader.Downloader
pmu sync.Mutex
peers map[string]*peer
SubProtocol p2p.Protocol
eventMux *event.TypeMux
txSub event.Subscription
minedBlockSub event.Subscription
newPeerCh chan *peer
quitSync chan struct{}
}
// NewProtocolManager returns a new ethereum sub protocol manager. The Ethereum sub protocol manages peers capable
// with the ethereum network.
func NewProtocolManager(protocolVersion, networkId int, mux *event.TypeMux, txpool txPool, chainman *core.ChainManager, downloader *downloader.Downloader) *ProtocolManager {
manager := &ProtocolManager{
eventMux: mux,
txpool: txpool,
chainman: chainman,
downloader: downloader,
peers: make(map[string]*peer),
newPeerCh: make(chan *peer, 1),
quitSync: make(chan struct{}),
}
manager.SubProtocol = p2p.Protocol{
Name: "eth",
Version: uint(protocolVersion),
Length: ProtocolLength,
Run: func(p *p2p.Peer, rw p2p.MsgReadWriter) error {
peer := manager.newPeer(protocolVersion, networkId, p, rw)
manager.newPeerCh <- peer
return manager.handle(peer)
},
}
return manager
}
func (pm *ProtocolManager) syncHandler() {
// itimer is used to determine when to start ignoring `minDesiredPeerCount`
itimer := time.NewTimer(peerCountTimeout)
out:
for {
select {
case <-pm.newPeerCh:
// Meet the `minDesiredPeerCount` before we select our best peer
if len(pm.peers) < minDesiredPeerCount {
break
}
// Find the best peer
peer := getBestPeer(pm.peers)
if peer == nil {
glog.V(logger.Debug).Infoln("Sync attempt cancelled. No peers available")
}
itimer.Stop()
go pm.synchronise(peer)
case <-itimer.C:
// The timer will make sure that the downloader keeps an active state
// in which it attempts to always check the network for highest td peers
// Either select the peer or restart the timer if no peers could
// be selected.
if peer := getBestPeer(pm.peers); peer != nil {
go pm.synchronise(peer)
} else {
itimer.Reset(5 * time.Second)
}
case <-pm.quitSync:
break out
}
}
}
func (pm *ProtocolManager) synchronise(peer *peer) {
// Get the hashes from the peer (synchronously)
err := pm.downloader.Synchronise(peer.id, peer.recentHash)
if err != nil {
// handle error
glog.V(logger.Debug).Infoln("error downloading:", err)
}
}
func (pm *ProtocolManager) Start() {
// broadcast transactions
pm.txSub = pm.eventMux.Subscribe(core.TxPreEvent{})
go pm.txBroadcastLoop()
// broadcast mined blocks
pm.minedBlockSub = pm.eventMux.Subscribe(core.NewMinedBlockEvent{})
go pm.minedBroadcastLoop()
// sync handler
go pm.syncHandler()
}
func (pm *ProtocolManager) Stop() {
pm.txSub.Unsubscribe() // quits txBroadcastLoop
pm.minedBlockSub.Unsubscribe() // quits blockBroadcastLoop
close(pm.quitSync) // quits the sync handler
}
func (pm *ProtocolManager) newPeer(pv, nv int, p *p2p.Peer, rw p2p.MsgReadWriter) *peer {
td, current, genesis := pm.chainman.Status()
return newPeer(pv, nv, genesis, current, td, p, rw)
}
func (pm *ProtocolManager) handle(p *peer) error {
if err := p.handleStatus(); err != nil {
return err
}
pm.pmu.Lock()
pm.peers[p.id] = p
pm.pmu.Unlock()
pm.downloader.RegisterPeer(p.id, p.recentHash, p.requestHashes, p.requestBlocks)
defer func() {
pm.pmu.Lock()
defer pm.pmu.Unlock()
delete(pm.peers, p.id)
pm.downloader.UnregisterPeer(p.id)
}()
// propagate existing transactions. new transactions appearing
// after this will be sent via broadcasts.
if err := p.sendTransactions(pm.txpool.GetTransactions()); err != nil {
return err
}
// main loop. handle incoming messages.
for {
if err := pm.handleMsg(p); err != nil {
return err
}
}
return nil
}
func (self *ProtocolManager) handleMsg(p *peer) error {
msg, err := p.rw.ReadMsg()
if err != nil {
return err
}
if msg.Size > ProtocolMaxMsgSize {
return errResp(ErrMsgTooLarge, "%v > %v", msg.Size, ProtocolMaxMsgSize)
}
// make sure that the payload has been fully consumed
defer msg.Discard()
switch msg.Code {
case GetTxMsg: // ignore
case StatusMsg:
return errResp(ErrExtraStatusMsg, "uncontrolled status message")
case TxMsg:
// TODO: rework using lazy RLP stream
var txs []*types.Transaction
if err := msg.Decode(&txs); err != nil {
return errResp(ErrDecode, "msg %v: %v", msg, err)
}
for i, tx := range txs {
if tx == nil {
return errResp(ErrDecode, "transaction %d is nil", i)
}
jsonlogger.LogJson(&logger.EthTxReceived{
TxHash: tx.Hash().Hex(),
RemoteId: p.ID().String(),
})
}
self.txpool.AddTransactions(txs)
case GetBlockHashesMsg:
var request getBlockHashesMsgData
if err := msg.Decode(&request); err != nil {
return errResp(ErrDecode, "->msg %v: %v", msg, err)
}
if request.Amount > maxHashes {
request.Amount = maxHashes
}
hashes := self.chainman.GetBlockHashesFromHash(request.Hash, request.Amount)
if glog.V(logger.Debug) {
if len(hashes) == 0 {
glog.Infof("invalid block hash %x", request.Hash.Bytes()[:4])
}
}
// returns either requested hashes or nothing (i.e. not found)
return p.sendBlockHashes(hashes)
case BlockHashesMsg:
msgStream := rlp.NewStream(msg.Payload, uint64(msg.Size))
var hashes []common.Hash
if err := msgStream.Decode(&hashes); err != nil {
break
}
err := self.downloader.AddHashes(p.id, hashes)
if err != nil {
glog.V(logger.Debug).Infoln(err)
}
case GetBlocksMsg:
var blocks []*types.Block
msgStream := rlp.NewStream(msg.Payload, uint64(msg.Size))
if _, err := msgStream.List(); err != nil {
return err
}
var i int
for {
i++
var hash common.Hash
err := msgStream.Decode(&hash)
if err == rlp.EOL {
break
} else if err != nil {
return errResp(ErrDecode, "msg %v: %v", msg, err)
}
block := self.chainman.GetBlock(hash)
if block != nil {
blocks = append(blocks, block)
}
if i == maxBlocks {
break
}
}
return p.sendBlocks(blocks)
case BlocksMsg:
var blocks []*types.Block
msgStream := rlp.NewStream(msg.Payload, uint64(msg.Size))
if err := msgStream.Decode(&blocks); err != nil {
glog.V(logger.Detail).Infoln("Decode error", err)
blocks = nil
}
self.downloader.DeliverChunk(p.id, blocks)
case NewBlockMsg:
var request newBlockMsgData
if err := msg.Decode(&request); err != nil {
return errResp(ErrDecode, "%v: %v", msg, err)
}
if err := request.Block.ValidateFields(); err != nil {
return errResp(ErrDecode, "block validation %v: %v", msg, err)
}
hash := request.Block.Hash()
// Add the block hash as a known hash to the peer. This will later be used to determine
// who should receive this.
p.blockHashes.Add(hash)
_, chainHead, _ := self.chainman.Status()
jsonlogger.LogJson(&logger.EthChainReceivedNewBlock{
BlockHash: hash.Hex(),
BlockNumber: request.Block.Number(), // this surely must be zero
ChainHeadHash: chainHead.Hex(),
BlockPrevHash: request.Block.ParentHash().Hex(),
RemoteId: p.ID().String(),
})
// Make sure the block isn't already known. If this is the case simply drop
// the message and move on. If the TD is < currentTd; drop it as well. If this
// chain at some point becomes canonical, the downloader will fetch it.
if self.chainman.HasBlock(hash) {
break
}
if self.chainman.Td().Cmp(request.TD) > 0 && new(big.Int).Add(request.Block.Number(), big.NewInt(7)).Cmp(self.chainman.CurrentBlock().Number()) < 0 {
glog.V(logger.Debug).Infof("[%s] dropped block %v due to low TD %v\n", p.id, request.Block.Number(), request.TD)
break
}
// Attempt to insert the newly received by checking if the parent exists.
// if the parent exists we process the block and propagate to our peers
// if the parent does not exists we delegate to the downloader.
if self.chainman.HasBlock(request.Block.ParentHash()) {
if err := self.chainman.InsertChain(types.Blocks{request.Block}); err != nil {
// handle error
return nil
}
self.BroadcastBlock(hash, request.Block)
} else {
// adding blocks is synchronous
go func() {
// TODO check parent error
err := self.downloader.AddBlock(p.id, request.Block, request.TD)
if err != nil {
glog.V(logger.Detail).Infoln("downloader err:", err)
return
}
self.BroadcastBlock(hash, request.Block)
}()
}
default:
return errResp(ErrInvalidMsgCode, "%v", msg.Code)
}
return nil
}
// BroadcastBlock will propagate the block to its connected peers. It will sort
// out which peers do not contain the block in their block set and will do a
// sqrt(peers) to determine the amount of peers we broadcast to.
func (pm *ProtocolManager) BroadcastBlock(hash common.Hash, block *types.Block) {
pm.pmu.Lock()
defer pm.pmu.Unlock()
// Find peers who don't know anything about the given hash. Peers that
// don't know about the hash will be a candidate for the broadcast loop
var peers []*peer
for _, peer := range pm.peers {
if !peer.blockHashes.Has(hash) {
peers = append(peers, peer)
}
}
// Broadcast block to peer set
peers = peers[:int(math.Sqrt(float64(len(peers))))]
for _, peer := range peers {
peer.sendNewBlock(block)
}
glog.V(logger.Detail).Infoln("broadcast block to", len(peers), "peers")
}
// BroadcastTx will propagate the block to its connected peers. It will sort
// out which peers do not contain the block in their block set and will do a
// sqrt(peers) to determine the amount of peers we broadcast to.
func (pm *ProtocolManager) BroadcastTx(hash common.Hash, tx *types.Transaction) {
pm.pmu.Lock()
defer pm.pmu.Unlock()
// Find peers who don't know anything about the given hash. Peers that
// don't know about the hash will be a candidate for the broadcast loop
var peers []*peer
for _, peer := range pm.peers {
if !peer.txHashes.Has(hash) {
peers = append(peers, peer)
}
}
// Broadcast block to peer set
peers = peers[:int(math.Sqrt(float64(len(peers))))]
for _, peer := range peers {
peer.sendTransaction(tx)
}
glog.V(logger.Detail).Infoln("broadcast tx to", len(peers), "peers")
}
// Mined broadcast loop
func (self *ProtocolManager) minedBroadcastLoop() {
// automatically stops if unsubscribe
for obj := range self.minedBlockSub.Chan() {
switch ev := obj.(type) {
case core.NewMinedBlockEvent:
self.BroadcastBlock(ev.Block.Hash(), ev.Block)
}
}
}
func (self *ProtocolManager) txBroadcastLoop() {
// automatically stops if unsubscribe
for obj := range self.txSub.Chan() {
event := obj.(core.TxPreEvent)
self.BroadcastTx(event.Tx.Hash(), event.Tx)
}
}
