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"
)

// This is the target maximum size of returned blocks for the
// getBlocks message. The reply message may exceed it
// if a single block is larger than the limit.
const maxBlockRespSize = 2 * 1024 * 1024

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

    // channels for fetcher, syncer, txsyncLoop
    newPeerCh  chan *peer
    newHashCh  chan []*blockAnnounce
    newBlockCh chan chan []*types.Block
    txsyncCh   chan *txsync
    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) *ProtocolManager {
    manager := &ProtocolManager{
        eventMux:   mux,
        txpool:     txpool,
        chainman:   chainman,
        peers:      newPeerSet(),
        newPeerCh:  make(chan *peer, 1),
        newHashCh:  make(chan []*blockAnnounce, 1),
        newBlockCh: make(chan chan []*types.Block),
        txsyncCh:   make(chan *txsync),
        quitSync:   make(chan struct{}),
    }
    manager.downloader = downloader.New(manager.eventMux, manager.chainman.HasBlock, manager.chainman.GetBlock, manager.removePeer)
    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) {
    // Short circuit if the peer was already removed
    peer := pm.peers.Peer(id)
    if peer == nil {
        return
    }
    glog.V(logger.Debug).Infoln("Removing peer", id)

    // Unregister the peer from the downloader and Ethereum peer set
    pm.downloader.UnregisterPeer(id)
    if err := pm.peers.Unregister(id); err != nil {
        glog.V(logger.Error).Infoln("Removal failed:", err)
    }
    // Hard disconnect at the networking layer
    if peer != nil {
        peer.Peer.Disconnect(p2p.DiscUselessPeer)
    }
}

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()

    // start sync handlers
    go pm.syncer()
    go pm.fetcher()
    go pm.txsyncLoop()
}

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 syncer, fetcher, txsyncLoop

    // 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.
    if err := p.handleStatus(); err != nil {
        return err
    }

    // Register the peer locally.
    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)

    // Register the peer in the downloader. If the downloader
    // considers it banned, we disconnect.
    if err := pm.downloader.RegisterPeer(p.id, p.Head(), p.requestHashes, p.requestBlocks); err != nil {
        return err
    }

    // Propagate existing transactions. new transactions appearing
    // after this will be sent via broadcasts.
    pm.syncTransactions(p)

    // 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 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 > uint64(downloader.MaxHashFetch) {
            request.Amount = uint64(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
            totalsize common.StorageSize
        )
        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)
                totalsize += block.Size()
            }
            if i == downloader.MaxBlockFetch || totalsize > maxBlockRespSize {
                break
            }
        }
        return p.sendBlocks(blocks)

    case BlocksMsg:
        // Decode the arrived block message
        msgStream := rlp.NewStream(msg.Payload, uint64(msg.Size))

        var blocks []*types.Block
        if err := msgStream.Decode(&blocks); err != nil {
            glog.V(logger.Detail).Infoln("Decode error", err)
            blocks = nil
        }
        // Filter out any explicitly requested blocks (cascading select to get blocking back to peer)
        filter := make(chan []*types.Block)
        select {
        case <-self.quitSync:
        case self.newBlockCh <- filter:
            select {
            case <-self.quitSync:
            case filter <- blocks:
                select {
                case <-self.quitSync:
                case blocks := <-filter:
                    self.downloader.DeliverBlocks(p.id, blocks)
                }
            }
        }

    case NewBlockHashesMsg:
        // Retrieve and deseralize the remote new block hashes notification
        msgStream := rlp.NewStream(msg.Payload, uint64(msg.Size))

        var hashes []common.Hash
        if err := msgStream.Decode(&hashes); err != nil {
            break
        }
        // Mark the hashes as present at the remote node
        for _, hash := range hashes {
            p.blockHashes.Add(hash)
            p.SetHead(hash)
        }
        // Schedule all the unknown hashes for retrieval
        unknown := make([]common.Hash, 0, len(hashes))
        for _, hash := range hashes {
            if !self.chainman.HasBlock(hash) {
                unknown = append(unknown, hash)
            }
        }
        announces := make([]*blockAnnounce, len(unknown))
        for i, hash := range unknown {
            announces[i] = &blockAnnounce{
                hash: hash,
                peer: p,
                time: time.Now(),
            }
        }
        if len(announces) > 0 {
            select {
            case self.newHashCh <- announces:
            case <-self.quitSync:
            }
        }

    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

        if err := self.importBlock(p, request.Block, request.TD); err != nil {
            return err
        }

    default:
        return errResp(ErrInvalidMsgCode, "%v", msg.Code)
    }
    return nil
}

// importBlocks injects a new block retrieved from the given peer into the chain
// manager.
func (pm *ProtocolManager) importBlock(p *peer, block *types.Block, td *big.Int) error {
    hash := block.Hash()

    // Mark the block as present at the remote node (don't duplicate already held data)
    p.blockHashes.Add(hash)
    p.SetHead(hash)
    if td != nil {
        p.SetTd(td)
    }
    // Log the block's arrival
    _, chainHead, _ := pm.chainman.Status()
    jsonlogger.LogJson(&logger.EthChainReceivedNewBlock{
        BlockHash:     hash.Hex(),
        BlockNumber:   block.Number(),
        ChainHeadHash: chainHead.Hex(),
        BlockPrevHash: block.ParentHash().Hex(),
        RemoteId:      p.ID().String(),
    })
    // If the block's already known or its difficulty is lower than ours, drop
    if pm.chainman.HasBlock(hash) {
        p.SetTd(pm.chainman.GetBlock(hash).Td) // update the peer's TD to the real value
        return nil
    }
    if td != nil && pm.chainman.Td().Cmp(td) > 0 && new(big.Int).Add(block.Number(), big.NewInt(7)).Cmp(pm.chainman.CurrentBlock().Number()) < 0 {
        glog.V(logger.Debug).Infof("[%s] dropped block %v due to low TD %v\n", p.id, block.Number(), td)
        return nil
    }
    // Attempt to insert the newly received block and propagate to our peers
    if pm.chainman.HasBlock(block.ParentHash()) {
        if _, err := pm.chainman.InsertChain(types.Blocks{block}); err != nil {
            glog.V(logger.Error).Infoln("removed peer (", p.id, ") due to block error", err)
            return err
        }
        if td != nil && block.Td.Cmp(td) != 0 {
            err := fmt.Errorf("invalid TD on block(%v) from peer(%s): block.td=%v, request.td=%v", block.Number(), p.id, block.Td, td)
            glog.V(logger.Error).Infoln(err)
            return err
        }
        pm.BroadcastBlock(hash, block)
        return nil
    }
    // Parent of the block is unknown, try to sync with this peer if it seems to be good
    if td != nil {
        go pm.synchronise(p)
    }
    return nil
}

// BroadcastBlock will propagate the block to a subset of its connected peers,
// only notifying the rest of the block's appearance.
func (pm *ProtocolManager) BroadcastBlock(hash common.Hash, block *types.Block) {
    // Retrieve all the target peers and split between full broadcast or only notification
    peers := pm.peers.PeersWithoutBlock(hash)
    split := int(math.Sqrt(float64(len(peers))))

    transfer := peers[:split]
    notify := peers[split:]

    // Send out the data transfers and the notifications
    for _, peer := range notify {
        peer.sendNewBlockHashes([]common.Hash{hash})
    }
    glog.V(logger.Detail).Infoln("broadcast hash to", len(notify), "peers.")

    for _, peer := range transfer {
        peer.sendNewBlock(block)
    }
    glog.V(logger.Detail).Infoln("broadcast block to", len(transfer), "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)
    }
}