path: root/eth/handler.go

// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

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/eth/fetcher"
    "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/pow"
    "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
    fetcher        *fetcher.Fetcher
    peers          *peerSet

    SubProtocols []p2p.Protocol

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

    // channels for fetcher, syncer, txsyncLoop
    newPeerCh chan *peer
    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(networkId int, mux *event.TypeMux, txpool txPool, pow pow.PoW, chainman *core.ChainManager) *ProtocolManager {
    // Create the protocol manager with the base fields
    manager := &ProtocolManager{
        eventMux:  mux,
        txpool:    txpool,
        chainman:  chainman,
        peers:     newPeerSet(),
        newPeerCh: make(chan *peer, 1),
        txsyncCh:  make(chan *txsync),
        quitSync:  make(chan struct{}),
    }
    // Initiate a sub-protocol for every implemented version we can handle
    manager.SubProtocols = make([]p2p.Protocol, len(ProtocolVersions))
    for i := 0; i < len(manager.SubProtocols); i++ {
        version := ProtocolVersions[i]

        manager.SubProtocols[i] = p2p.Protocol{
            Name:    "eth",
            Version: version,
            Length:  ProtocolLengths[i],
            Run: func(p *p2p.Peer, rw p2p.MsgReadWriter) error {
                peer := manager.newPeer(int(version), networkId, p, rw)
                manager.newPeerCh <- peer
                return manager.handle(peer)
            },
        }
    }
    // Construct the different synchronisation mechanisms
    manager.downloader = downloader.New(manager.eventMux, manager.chainman.HasBlock, manager.chainman.GetBlock, manager.chainman.CurrentBlock, manager.chainman.InsertChain, manager.removePeer)

    validator := func(block *types.Block, parent *types.Block) error {
        return core.ValidateHeader(pow, block.Header(), parent, true)
    }
    heighter := func() uint64 {
        return manager.chainman.CurrentBlock().NumberU64()
    }
    manager.fetcher = fetcher.New(manager.chainman.GetBlock, validator, manager.BroadcastBlock, heighter, manager.chainman.InsertChain, manager.removePeer)

    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.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 {
    return newPeer(pv, nv, p, rw)
}

// handle is the callback invoked to manage the life cycle of an eth peer. When
// this function terminates, the peer is disconnected.
func (pm *ProtocolManager) handle(p *peer) error {
    glog.V(logger.Debug).Infof("%v: peer connected [%s]", p, p.Name())

    // Execute the Ethereum handshake
    td, head, genesis := pm.chainman.Status()
    if err := p.Handshake(td, head, genesis); err != nil {
        glog.V(logger.Debug).Infof("%v: handshake failed: %v", p, err)
        return err
    }
    // Register the peer locally
    glog.V(logger.Detail).Infof("%v: adding peer", p)
    if err := pm.peers.Register(p); err != nil {
        glog.V(logger.Error).Infof("%v: addition failed: %v", p, 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.version, p.Head(), p.RequestHashes, p.RequestHashesFromNumber, 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 {
            glog.V(logger.Debug).Infof("%v: message handling failed: %v", p, err)
            return err
        }
    }
    return nil
}

// handleMsg is invoked whenever an inbound message is received from a remote
// peer. The remote connection is torn down upon returning any error.
func (pm *ProtocolManager) handleMsg(p *peer) error {
    // Read the next message from the remote peer, and ensure it's fully consumed
    msg, err := p.rw.ReadMsg()
    if err != nil {
        return err
    }
    if msg.Size > ProtocolMaxMsgSize {
        return errResp(ErrMsgTooLarge, "%v > %v", msg.Size, ProtocolMaxMsgSize)
    }
    defer msg.Discard()

    // Handle the message depending on its contents
    switch msg.Code {
    case StatusMsg:
        // Status messages should never arrive after the handshake
        return errResp(ErrExtraStatusMsg, "uncontrolled status message")

    case GetBlockHashesMsg:
        // Retrieve the number of hashes to return and from which origin hash
        var request getBlockHashesData
        if err := msg.Decode(&request); err != nil {
            return errResp(ErrDecode, "%v: %v", msg, err)
        }
        if request.Amount > uint64(downloader.MaxHashFetch) {
            request.Amount = uint64(downloader.MaxHashFetch)
        }
        // Retrieve the hashes from the block chain and return them
        hashes := pm.chainman.GetBlockHashesFromHash(request.Hash, request.Amount)
        if len(hashes) == 0 {
            glog.V(logger.Debug).Infof("invalid block hash %x", request.Hash.Bytes()[:4])
        }
        return p.SendBlockHashes(hashes)

    case GetBlockHashesFromNumberMsg:
        // Retrieve and decode the number of hashes to return and from which origin number
        var request getBlockHashesFromNumberData
        if err := msg.Decode(&request); err != nil {
            return errResp(ErrDecode, "%v: %v", msg, err)
        }
        if request.Amount > uint64(downloader.MaxHashFetch) {
            request.Amount = uint64(downloader.MaxHashFetch)
        }
        // Calculate the last block that should be retrieved, and short circuit if unavailable
        last := pm.chainman.GetBlockByNumber(request.Number + request.Amount - 1)
        if last == nil {
            last = pm.chainman.CurrentBlock()
            request.Amount = last.NumberU64() - request.Number + 1
        }
        if last.NumberU64() < request.Number {
            return p.SendBlockHashes(nil)
        }
        // Retrieve the hashes from the last block backwards, reverse and return
        hashes := []common.Hash{last.Hash()}
        hashes = append(hashes, pm.chainman.GetBlockHashesFromHash(last.Hash(), request.Amount-1)...)

        for i := 0; i < len(hashes)/2; i++ {
            hashes[i], hashes[len(hashes)-1-i] = hashes[len(hashes)-1-i], hashes[i]
        }
        return p.SendBlockHashes(hashes)

    case BlockHashesMsg:
        // A batch of hashes arrived to one of our previous requests
        msgStream := rlp.NewStream(msg.Payload, uint64(msg.Size))
        reqHashInPacketsMeter.Mark(1)

        var hashes []common.Hash
        if err := msgStream.Decode(&hashes); err != nil {
            break
        }
        reqHashInTrafficMeter.Mark(int64(32 * len(hashes)))

        // Deliver them all to the downloader for queuing
        err := pm.downloader.DeliverHashes(p.id, hashes)
        if err != nil {
            glog.V(logger.Debug).Infoln(err)
        }

    case GetBlocksMsg:
        // Decode the retrieval message
        msgStream := rlp.NewStream(msg.Payload, uint64(msg.Size))
        if _, err := msgStream.List(); err != nil {
            return err
        }
        // Gather blocks until the fetch or network limits is reached
        var (
            hash   common.Hash
            bytes  common.StorageSize
            hashes []common.Hash
            blocks []*types.Block
        )
        for {
            err := msgStream.Decode(&hash)
            if err == rlp.EOL {
                break
            } else if err != nil {
                return errResp(ErrDecode, "msg %v: %v", msg, err)
            }
            hashes = append(hashes, hash)

            // Retrieve the requested block, stopping if enough was found
            if block := pm.chainman.GetBlock(hash); block != nil {
                blocks = append(blocks, block)
                bytes += block.Size()
                if len(blocks) >= downloader.MaxBlockFetch || bytes > maxBlockRespSize {
                    break
                }
            }
        }
        if glog.V(logger.Detail) && len(blocks) == 0 && len(hashes) > 0 {
            list := "["
            for _, hash := range hashes {
                list += fmt.Sprintf("%x, ", hash[:4])
            }
            list = list[:len(list)-2] + "]"

            glog.Infof("%v: no blocks found for requested hashes %s", p, list)
        }
        return p.SendBlocks(blocks)

    case BlocksMsg:
        // Decode the arrived block message
        msgStream := rlp.NewStream(msg.Payload, uint64(msg.Size))
        reqBlockInPacketsMeter.Mark(1)

        var blocks []*types.Block
        if err := msgStream.Decode(&blocks); err != nil {
            glog.V(logger.Detail).Infoln("Decode error", err)
            blocks = nil
        }
        // Update the receive timestamp of each block
        for _, block := range blocks {
            reqBlockInTrafficMeter.Mark(block.Size().Int64())
            block.ReceivedAt = msg.ReceivedAt
        }
        // Filter out any explicitly requested blocks, deliver the rest to the downloader
        if blocks := pm.fetcher.Filter(blocks); len(blocks) > 0 {
            pm.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
        }
        propHashInPacketsMeter.Mark(1)
        propHashInTrafficMeter.Mark(int64(32 * len(hashes)))

        // Mark the hashes as present at the remote node
        for _, hash := range hashes {
            p.MarkBlock(hash)
            p.SetHead(hash)
        }
        // Schedule all the unknown hashes for retrieval
        unknown := make([]common.Hash, 0, len(hashes))
        for _, hash := range hashes {
            if !pm.chainman.HasBlock(hash) {
                unknown = append(unknown, hash)
            }
        }
        for _, hash := range unknown {
            pm.fetcher.Notify(p.id, hash, time.Now(), p.RequestBlocks)
        }

    case NewBlockMsg:
        // Retrieve and decode the propagated block
        var request newBlockData
        if err := msg.Decode(&request); err != nil {
            return errResp(ErrDecode, "%v: %v", msg, err)
        }
        propBlockInPacketsMeter.Mark(1)
        propBlockInTrafficMeter.Mark(request.Block.Size().Int64())

        if err := request.Block.ValidateFields(); err != nil {
            return errResp(ErrDecode, "block validation %v: %v", msg, err)
        }
        request.Block.ReceivedAt = msg.ReceivedAt

        // Mark the block's arrival for whatever reason
        _, chainHead, _ := pm.chainman.Status()
        jsonlogger.LogJson(&logger.EthChainReceivedNewBlock{
            BlockHash:     request.Block.Hash().Hex(),
            BlockNumber:   request.Block.Number(),
            ChainHeadHash: chainHead.Hex(),
            BlockPrevHash: request.Block.ParentHash().Hex(),
            RemoteId:      p.ID().String(),
        })
        // Mark the peer as owning the block and schedule it for import
        p.MarkBlock(request.Block.Hash())
        p.SetHead(request.Block.Hash())

        pm.fetcher.Enqueue(p.id, request.Block)

        // TODO: Schedule a sync to cover potential gaps (this needs proto update)
        if request.TD.Cmp(p.Td()) > 0 {
            p.SetTd(request.TD)
            go pm.synchronise(p)
        }

    case TxMsg:
        // Transactions arrived, parse all of them and deliver to the pool
        var txs []*types.Transaction
        if err := msg.Decode(&txs); err != nil {
            return errResp(ErrDecode, "msg %v: %v", msg, err)
        }
        propTxnInPacketsMeter.Mark(1)
        for i, tx := range txs {
            // Validate and mark the remote transaction
            if tx == nil {
                return errResp(ErrDecode, "transaction %d is nil", i)
            }
            p.MarkTransaction(tx.Hash())

            // Log it's arrival for later analysis
            propTxnInTrafficMeter.Mark(tx.Size().Int64())
            jsonlogger.LogJson(&logger.EthTxReceived{
                TxHash:   tx.Hash().Hex(),
                RemoteId: p.ID().String(),
            })
        }
        pm.txpool.AddTransactions(txs)

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

// BroadcastBlock will either propagate a block to a subset of it's peers, or
// will only announce it's availability (depending what's requested).
func (pm *ProtocolManager) BroadcastBlock(block *types.Block, propagate bool) {
    hash := block.Hash()
    peers := pm.peers.PeersWithoutBlock(hash)

    // If propagation is requested, send to a subset of the peer
    if propagate {
        // Calculate the TD of the block (it's not imported yet, so block.Td is not valid)
        var td *big.Int
        if parent := pm.chainman.GetBlock(block.ParentHash()); parent != nil {
            td = new(big.Int).Add(parent.Td, block.Difficulty())
        } else {
            glog.V(logger.Error).Infof("propagating dangling block #%d [%x]", block.NumberU64(), hash[:4])
            return
        }
        // Send the block to a subset of our peers
        transfer := peers[:int(math.Sqrt(float64(len(peers))))]
        for _, peer := range transfer {
            peer.SendNewBlock(block, td)
        }
        glog.V(logger.Detail).Infof("propagated block %x to %d peers in %v", hash[:4], len(transfer), time.Since(block.ReceivedAt))
    }
    // Otherwise if the block is indeed in out own chain, announce it
    if pm.chainman.HasBlock(hash) {
        for _, peer := range peers {
            peer.SendNewBlockHashes([]common.Hash{hash})
        }
        glog.V(logger.Detail).Infof("announced block %x to %d peers in %v", hash[:4], len(peers), time.Since(block.ReceivedAt))
    }
}

// BroadcastTx will propagate a transaction to all peers which are not known to
// already have the given transaction.
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.SendTransactions(types.Transactions{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, true)  // First propagate block to peers
            self.BroadcastBlock(ev.Block, false) // Only then announce to the rest
        }
    }
}

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)
    }
}