path: root/eth/handler.go

package eth

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 (
    forceSyncCycle      = 10 * time.Second       // Time interval to force syncs, even if few peers are available
    blockProcCycle      = 500 * time.Millisecond // Time interval to check for new blocks to process
    minDesiredPeerCount = 5                      // Amount of peers desired to start syncing
    blockProcAmount     = 256
)

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
    peers          *peerSet

    SubProtocol p2p.Protocol

    eventMux      *event.TypeMux
    txSub         event.Subscription
    minedBlockSub event.Subscription

    newPeerCh chan *peer
    quitSync  chan struct{}
    // wait group is used for graceful shutdowns during downloading
    // and processing
    wg   sync.WaitGroup
    quit bool
}

// 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:      newPeerSet(),
        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) removePeer(id string) {
    // Unregister the peer from the downloader
    pm.downloader.UnregisterPeer(id)

    // Remove the peer from the Ethereum peer set too
    glog.V(logger.Detail).Infoln("Removing peer", id)
    if err := pm.peers.Unregister(id); err != nil {
        glog.V(logger.Error).Infoln("Removal failed:", 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()

    go pm.update()
}

func (pm *ProtocolManager) Stop() {
    // Showing a log message. During download / process this could actually
    // take between 5 to 10 seconds and therefor feedback is required.
    glog.V(logger.Info).Infoln("Stopping ethereum protocol handler...")

    pm.quit = true
    pm.txSub.Unsubscribe()         // quits txBroadcastLoop
    pm.minedBlockSub.Unsubscribe() // quits blockBroadcastLoop
    close(pm.quitSync)             // quits the sync handler

    // Wait for any process action
    pm.wg.Wait()

    glog.V(logger.Info).Infoln("Ethereum protocol handler stopped")
}

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 {
    // Execute the Ethereum handshake, short circuit if fails
    if err := p.handleStatus(); err != nil {
        return err
    }
    // Register the peer locally and in the downloader too
    glog.V(logger.Detail).Infoln("Adding peer", p.id)
    if err := pm.peers.Register(p); err != nil {
        glog.V(logger.Error).Infoln("Addition failed:", err)
        return err
    }
    defer pm.removePeer(p.id)

    if err := pm.downloader.RegisterPeer(p.id, p.recentHash, p.requestHashes, p.requestBlocks); err != nil {
        return err
    }
    // 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 > downloader.MaxHashFetch {
            request.Amount = downloader.MaxHashFetch
        }

        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.DeliverHashes(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 == downloader.MaxBlockFetch {
                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.DeliverBlocks(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)
        }
        request.Block.ReceivedAt = msg.ReceivedAt

        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)
        // update the peer info
        p.recentHash = hash
        p.td = request.TD

        _, 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
        // otherwise synchronize with the peer
        if self.chainman.HasBlock(request.Block.ParentHash()) {
            if _, err := self.chainman.InsertChain(types.Blocks{request.Block}); err != nil {
                glog.V(logger.Error).Infoln("removed peer (", p.id, ") due to block error")

                self.removePeer(p.id)

                return nil
            }

            if err := self.verifyTd(p, request); err != nil {
                glog.V(logger.Error).Infoln(err)
                // XXX for now return nil so it won't disconnect (we should in the future)
                return nil
            }
            self.BroadcastBlock(hash, request.Block)
        } else {
            go self.synchronise(p)
        }
    default:
        return errResp(ErrInvalidMsgCode, "%v", msg.Code)
    }
    return nil
}

func (pm *ProtocolManager) verifyTd(peer *peer, request newBlockMsgData) error {
    if request.Block.Td.Cmp(request.TD) != 0 {
        glog.V(logger.Detail).Infoln(peer)

        return fmt.Errorf("invalid TD on block(%v) from peer(%s): block.td=%v, request.td=%v", request.Block.Number(), peer.id, request.Block.Td, request.TD)
    }

    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) {
    // Broadcast block to a batch of peers not knowing about it
    peers := pm.peers.PeersWithoutBlock(hash)
    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. Total processing time:", time.Since(block.ReceivedAt))
}

// 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) {
    // Broadcast transaction to a batch of peers not knowing about it
    peers := pm.peers.PeersWithoutTx(hash)
    //FIXME include this again: 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)
    }
}