path: root/dex/handler.go

// Copyright 2018 The dexon-consensus Authors
// This file is part of the dexon-consensus library.
//
// The dexon-consensus 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 dexon-consensus 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 dexon-consensus library. If not, see
// <http://www.gnu.org/licenses/>.

// 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 dex

import (
    "bytes"
    "encoding/json"
    "errors"
    "fmt"
    "math"
    "math/rand"
    "sync"
    "sync/atomic"
    "time"

    coreCommon "github.com/dexon-foundation/dexon-consensus/common"
    dexCore "github.com/dexon-foundation/dexon-consensus/core"
    coreCrypto "github.com/dexon-foundation/dexon-consensus/core/crypto"
    coreTypes "github.com/dexon-foundation/dexon-consensus/core/types"
    dkgTypes "github.com/dexon-foundation/dexon-consensus/core/types/dkg"

    "github.com/dexon-foundation/dexon/common"
    "github.com/dexon-foundation/dexon/consensus"
    "github.com/dexon-foundation/dexon/core"
    "github.com/dexon-foundation/dexon/core/types"
    "github.com/dexon-foundation/dexon/crypto"
    dexDB "github.com/dexon-foundation/dexon/dex/db"
    "github.com/dexon-foundation/dexon/dex/downloader"
    "github.com/dexon-foundation/dexon/dex/fetcher"
    "github.com/dexon-foundation/dexon/ethdb"
    "github.com/dexon-foundation/dexon/event"
    "github.com/dexon-foundation/dexon/log"
    "github.com/dexon-foundation/dexon/metrics"
    "github.com/dexon-foundation/dexon/p2p"
    "github.com/dexon-foundation/dexon/p2p/enode"
    "github.com/dexon-foundation/dexon/p2p/enr"
    "github.com/dexon-foundation/dexon/params"
    "github.com/dexon-foundation/dexon/rlp"
)

const (
    softResponseLimit = 2 * 1024 * 1024 // Target maximum size of returned blocks, headers or node data.
    estHeaderRlpSize  = 500             // Approximate size of an RLP encoded block header

    // txChanSize is the size of channel listening to NewTxsEvent.
    // The number is referenced from the size of tx pool.
    txChanSize = 4096

    finalizedBlockChanSize = 128

    recordChanSize = 10240

    maxPullPeers     = 3
    maxPullVotePeers = 1

    pullVoteRateLimit = 10 * time.Second
)

// errIncompatibleConfig is returned if the requested protocols and configs are
// not compatible (low protocol version restrictions and high requirements).
var errIncompatibleConfig = errors.New("incompatible configuration")

func errResp(code errCode, format string, v ...interface{}) error {
    return fmt.Errorf("%v - %v", code, fmt.Sprintf(format, v...))
}

type ProtocolManager struct {
    networkID uint64

    fastSync  uint32 // Flag whether fast sync is enabled (gets disabled if we already have blocks)
    acceptTxs uint32 // Flag whether we're considered synchronised (enables transaction processing)

    txpool       txPool
    nodeTable    *nodeTable
    gov          governance
    blockchain   *core.BlockChain
    chainconfig  *params.ChainConfig
    cache        *cache
    nextPullVote *sync.Map
    maxPeers     int

    downloader *downloader.Downloader
    fetcher    *fetcher.Fetcher
    peers      *peerSet

    SubProtocols []p2p.Protocol

    eventMux   *event.TypeMux
    txsCh      chan core.NewTxsEvent
    txsSub     event.Subscription
    recordsCh  chan newRecordsEvent
    recordsSub event.Subscription

    // channels for fetcher, syncer, txsyncLoop
    newPeerCh    chan *peer
    txsyncCh     chan *txsync
    recordsyncCh chan *recordsync
    quitSync     chan struct{}
    noMorePeers  chan struct{}

    // channels for peerSetLoop
    chainHeadCh  chan core.ChainHeadEvent
    chainHeadSub event.Subscription

    // channels for dexon consensus core
    receiveCh chan interface{}

    srvr p2pServer

    // wait group is used for graceful shutdowns during downloading
    // and processing
    wg sync.WaitGroup

    // Dexcon
    isBlockProposer bool
    app             dexconApp

    finalizedBlockCh  chan core.NewFinalizedBlockEvent
    finalizedBlockSub event.Subscription

    // metrics
    blockNumberGauge metrics.Gauge
}

// NewProtocolManager returns a new Ethereum sub protocol manager. The Ethereum sub protocol manages peers capable
// with the Ethereum network.
func NewProtocolManager(
    config *params.ChainConfig, mode downloader.SyncMode, networkID uint64,
    mux *event.TypeMux, txpool txPool, engine consensus.Engine,
    blockchain *core.BlockChain, chaindb ethdb.Database,
    isBlockProposer bool, gov governance, app dexconApp) (*ProtocolManager, error) {
    tab := newNodeTable()
    // Create the protocol manager with the base fields
    manager := &ProtocolManager{
        networkID:        networkID,
        eventMux:         mux,
        txpool:           txpool,
        nodeTable:        tab,
        gov:              gov,
        blockchain:       blockchain,
        cache:            newCache(5120, dexDB.NewDatabase(chaindb)),
        nextPullVote:     &sync.Map{},
        chainconfig:      config,
        newPeerCh:        make(chan *peer),
        noMorePeers:      make(chan struct{}),
        txsyncCh:         make(chan *txsync),
        recordsyncCh:     make(chan *recordsync),
        quitSync:         make(chan struct{}),
        receiveCh:        make(chan interface{}, 1024),
        isBlockProposer:  isBlockProposer,
        app:              app,
        blockNumberGauge: metrics.GetOrRegisterGauge("dex/blocknumber", nil),
    }

    // Figure out whether to allow fast sync or not
    if mode == downloader.FastSync && blockchain.CurrentBlock().NumberU64() > 0 {
        log.Warn("Blockchain not empty, fast sync disabled")
        mode = downloader.FullSync
    }
    if mode == downloader.FastSync {
        manager.fastSync = uint32(1)
    }
    // Initiate a sub-protocol for every implemented version we can handle
    manager.SubProtocols = make([]p2p.Protocol, 0, len(ProtocolVersions))
    for i, version := range ProtocolVersions {
        version := version // Closure for the run
        manager.SubProtocols = append(manager.SubProtocols, p2p.Protocol{
            Name:    ProtocolName,
            Version: version,
            Length:  ProtocolLengths[i],
            Run: func(p *p2p.Peer, rw p2p.MsgReadWriter) error {
                peer := manager.newPeer(int(version), p, rw)
                select {
                case manager.newPeerCh <- peer:
                    manager.wg.Add(1)
                    defer manager.wg.Done()
                    return manager.handle(peer)
                case <-manager.quitSync:
                    return p2p.DiscQuitting
                }
            },
            NodeInfo: func() interface{} {
                return manager.NodeInfo()
            },
            PeerInfo: func(id enode.ID) interface{} {
                if p := manager.peers.Peer(id.String()); p != nil {
                    return p.Info()
                }
                return nil
            },
        })
    }
    if len(manager.SubProtocols) == 0 {
        return nil, errIncompatibleConfig
    }
    // Construct the different synchronisation mechanisms
    manager.downloader = downloader.New(mode, chaindb, manager.eventMux, blockchain, nil, manager.removePeer)

    validator := func(header *types.Header) error {
        return blockchain.VerifyDexonHeader(header)
    }
    heighter := func() uint64 {
        return blockchain.CurrentBlock().NumberU64()
    }
    inserter := func(blocks types.Blocks) (int, error) {
        // If fast sync is running, deny importing weird blocks
        if atomic.LoadUint32(&manager.fastSync) == 1 {
            log.Warn("Discarded bad propagated block", "number", blocks[0].Number(), "hash", blocks[0].Hash())
            return 0, nil
        }
        atomic.StoreUint32(&manager.acceptTxs, 1) // Mark initial sync done on any fetcher import
        return manager.blockchain.InsertDexonChain(blocks)
    }
    manager.fetcher = fetcher.New(blockchain.GetBlockByHash, validator, manager.BroadcastBlock, heighter, inserter, manager.removePeer)

    return manager, nil
}

func (pm *ProtocolManager) removePeer(id string) {
    // Short circuit if the peer was already removed
    peer := pm.peers.Peer(id)
    if peer == nil {
        return
    }
    log.Debug("Removing Ethereum peer", "peer", id)

    pm.nextPullVote.Delete(peer.ID())

    // Unregister the peer from the downloader and Ethereum peer set
    pm.downloader.UnregisterPeer(id)
    log.Debug("after downloader unregister peer", "id", id)
    if err := pm.peers.Unregister(id); err != nil {
        log.Error("Peer removal failed", "peer", id, "err", err)
    }
    log.Debug("after unregister peer", "id", id)
    // Hard disconnect at the networking layer
    if peer != nil {
        log.Debug("removePeer: peer disconnect")
        peer.Peer.Disconnect(p2p.DiscUselessPeer)
    }
    log.Debug("peer removed", "id", id)
}

func (pm *ProtocolManager) Start(srvr p2pServer, maxPeers int) {
    pm.maxPeers = maxPeers
    pm.srvr = srvr
    pm.peers = newPeerSet(pm.gov, pm.srvr, pm.nodeTable)

    // broadcast transactions
    pm.txsCh = make(chan core.NewTxsEvent, txChanSize)
    pm.txsSub = pm.txpool.SubscribeNewTxsEvent(pm.txsCh)
    go pm.txBroadcastLoop()

    if pm.isBlockProposer {
        // broadcast finalized blocks
        pm.finalizedBlockCh = make(chan core.NewFinalizedBlockEvent,
            finalizedBlockChanSize)
        pm.finalizedBlockSub = pm.app.SubscribeNewFinalizedBlockEvent(
            pm.finalizedBlockCh)
        go pm.finalizedBlockBroadcastLoop()
    }

    // broadcast node records
    pm.recordsCh = make(chan newRecordsEvent, recordChanSize)
    pm.recordsSub = pm.nodeTable.SubscribeNewRecordsEvent(pm.recordsCh)
    go pm.recordBroadcastLoop()

    // run the peer set loop
    pm.chainHeadCh = make(chan core.ChainHeadEvent)
    pm.chainHeadSub = pm.blockchain.SubscribeChainHeadEvent(pm.chainHeadCh)
    go pm.peerSetLoop()

    // start sync handlers
    go pm.syncer()
    go pm.txsyncLoop()
    go pm.recordsyncLoop()

}

func (pm *ProtocolManager) Stop() {
    log.Info("Stopping DEXON protocol")

    pm.txsSub.Unsubscribe() // quits txBroadcastLoop
    pm.chainHeadSub.Unsubscribe()

    if pm.isBlockProposer {
        pm.finalizedBlockSub.Unsubscribe()
    }

    // Quit the sync loop.
    // After this send has completed, no new peers will be accepted.
    pm.noMorePeers <- struct{}{}

    // Quit fetcher, txsyncLoop.
    close(pm.quitSync)

    // Disconnect existing sessions.
    // This also closes the gate for any new registrations on the peer set.
    // sessions which are already established but not added to pm.peers yet
    // will exit when they try to register.
    pm.peers.Close()

    // Wait for all peer handler goroutines and the loops to come down.
    pm.wg.Wait()

    log.Info("DEXON protocol stopped")
}

func (pm *ProtocolManager) ReceiveChan() <-chan interface{} {
    return pm.receiveCh
}

func (pm *ProtocolManager) newPeer(pv int, p *p2p.Peer, rw p2p.MsgReadWriter) *peer {
    return newPeer(pv, p, newMeteredMsgWriter(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 {
    // Ignore maxPeers if this is a trusted peer
    if pm.peers.Len() >= pm.maxPeers && !p.Peer.Info().Network.Trusted {
        return p2p.DiscTooManyPeers
    }
    p.Log().Debug("Ethereum peer connected", "name", p.Name())

    // Execute the Ethereum handshake
    var (
        genesis = pm.blockchain.Genesis()
        head    = pm.blockchain.CurrentHeader()
        hash    = head.Hash()
        number  = head.Number.Uint64()
    )
    if err := p.Handshake(pm.networkID, number, hash, genesis.Hash()); err != nil {
        p.Log().Debug("Ethereum handshake failed", "err", err)
        return err
    }
    if rw, ok := p.rw.(*meteredMsgReadWriter); ok {
        rw.Init(p.version)
    }
    // Register the peer locally
    if err := pm.peers.Register(p); err != nil {
        p.Log().Error("Ethereum peer registration failed", "err", 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); err != nil {
        return err
    }
    // Propagate existing transactions. new transactions appearing
    // after this will be sent via broadcasts.
    pm.syncTransactions(p)
    pm.syncNodeRecords(p)

    // main loop. handle incoming messages.
    for {
        if err := pm.handleMsg(p); err != nil {
            p.Log().Debug("Ethereum message handling failed", "err", err)
            return err
        }
    }
}

// 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 {
    ch := make(chan struct{})
    defer close(ch)

    go func() {
        n := 0
        for {
            select {
            case <-time.After(time.Second):
                p.Log().Debug("no msg more than 1s", "n", n)
                n++
            case <-ch:
                return
            }
        }
    }()

    // Read the next message from the remote peer, and ensure it's fully consumed
    msg, err := p.rw.ReadMsg()
    if err != nil {
        return err
    }
    ch <- struct{}{}
    if msg.Size > ProtocolMaxMsgSize {
        return errResp(ErrMsgTooLarge, "%v > %v", msg.Size, ProtocolMaxMsgSize)
    }
    defer msg.Discard()

    go func() {
        n := 0
        for {
            select {
            case <-time.After(100 * time.Millisecond):
                p.Log().Debug("handle msg more than 100ms", "n", n, "code", msg.Code)
                n++
            case <-ch:
                return
            }
        }
    }()

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

    // Block header query, collect the requested headers and reply
    case msg.Code == GetBlockHeadersMsg:
        // Decode the complex header query
        var query getBlockHeadersData
        if err := msg.Decode(&query); err != nil {
            return errResp(ErrDecode, "%v: %v", msg, err)
        }
        hashMode := query.Origin.Hash != (common.Hash{})
        first := true
        maxNonCanonical := uint64(100)

        round := map[uint64]uint64{}
        // Gather headers until the fetch or network limits is reached
        var (
            bytes   common.StorageSize
            headers []*types.HeaderWithGovState
            unknown bool
        )
        for !unknown && len(headers) < int(query.Amount) && bytes < softResponseLimit && len(headers) < downloader.MaxHeaderFetch {
            // Retrieve the next header satisfying the query
            var origin *types.Header
            if hashMode {
                if first {
                    first = false
                    origin = pm.blockchain.GetHeaderByHash(query.Origin.Hash)
                    if origin != nil {
                        query.Origin.Number = origin.Number.Uint64()
                    }
                } else {
                    origin = pm.blockchain.GetHeader(query.Origin.Hash, query.Origin.Number)
                }
            } else {
                origin = pm.blockchain.GetHeaderByNumber(query.Origin.Number)
            }
            if origin == nil {
                break
            }
            headers = append(headers, &types.HeaderWithGovState{Header: origin})
            if round[origin.Round] == 0 {
                round[origin.Round] = origin.Number.Uint64()
            }
            bytes += estHeaderRlpSize

            // Advance to the next header of the query
            switch {
            case hashMode && query.Reverse:
                // Hash based traversal towards the genesis block
                ancestor := query.Skip + 1
                if ancestor == 0 {
                    unknown = true
                } else {
                    query.Origin.Hash, query.Origin.Number = pm.blockchain.GetAncestor(query.Origin.Hash, query.Origin.Number, ancestor, &maxNonCanonical)
                    unknown = (query.Origin.Hash == common.Hash{})
                }
            case hashMode && !query.Reverse:
                // Hash based traversal towards the leaf block
                var (
                    current = origin.Number.Uint64()
                    next    = current + query.Skip + 1
                )
                if next <= current {
                    infos, _ := json.MarshalIndent(p.Peer.Info(), "", "  ")
                    p.Log().Warn("GetBlockHeaders skip overflow attack", "current", current, "skip", query.Skip, "next", next, "attacker", infos)
                    unknown = true
                } else {
                    if header := pm.blockchain.GetHeaderByNumber(next); header != nil {
                        nextHash := header.Hash()
                        expOldHash, _ := pm.blockchain.GetAncestor(nextHash, next, query.Skip+1, &maxNonCanonical)
                        if expOldHash == query.Origin.Hash {
                            query.Origin.Hash, query.Origin.Number = nextHash, next
                        } else {
                            unknown = true
                        }
                    } else {
                        unknown = true
                    }
                }
            case query.Reverse:
                // Number based traversal towards the genesis block
                if query.Origin.Number >= query.Skip+1 {
                    query.Origin.Number -= query.Skip + 1
                } else {
                    unknown = true
                }

            case !query.Reverse:
                // Number based traversal towards the leaf block
                query.Origin.Number += query.Skip + 1
            }
        }

        if query.WithGov && len(headers) > 0 {
            last := headers[len(headers)-1]
            currentBlock := pm.blockchain.CurrentBlock()

            // Do not reply if we don't have current gov state
            if currentBlock.NumberU64() < last.Number.Uint64() {
                log.Debug("Current block < last request",
                    "current", currentBlock.NumberU64(), "last", last.Number.Uint64())
                return p.SendBlockHeaders(query.Flag, []*types.HeaderWithGovState{})
            }

            snapshotHeight := map[uint64]struct{}{}
            for r, height := range round {
                log.Trace("#Include round", "round", r)
                if r == 0 {
                    continue
                }
                h := pm.gov.GetRoundHeight(r)
                log.Trace("#Snapshot height", "height", h)
                if h == 0 {
                    h = height
                }
                snapshotHeight[h] = struct{}{}
            }

            for _, header := range headers {
                if _, exist := snapshotHeight[header.Number.Uint64()]; exist {
                    s, err := pm.blockchain.GetGovStateByHash(header.Hash())
                    if err != nil {
                        log.Warn("Get gov state by hash fail", "number", header.Number.Uint64(), "err", err)
                        return p.SendBlockHeaders(query.Flag, []*types.HeaderWithGovState{})
                    }
                    header.GovState = s
                }
                log.Trace("Send header", "round", header.Round, "number", header.Number.Uint64(), "gov state == nil", header.GovState == nil)
            }
        }
        return p.SendBlockHeaders(query.Flag, headers)

    case msg.Code == BlockHeadersMsg:
        // A batch of headers arrived to one of our previous requests
        var data headersData
        if err := msg.Decode(&data); err != nil {
            return errResp(ErrDecode, "msg %v: %v", msg, err)
        }

        switch data.Flag {
        case fetcherReq:
            if len(data.Headers) > 0 {
                pm.fetcher.FilterHeaders(p.id, []*types.Header{data.Headers[0].Header}, time.Now())
            }
        case downloaderReq:
            err := pm.downloader.DeliverHeaders(p.id, data.Headers)
            if err != nil {
                log.Debug("Failed to deliver headers", "err", err)
            }
        default:
            log.Debug("Got headers with unexpected flag", "flag", data.Flag)
        }

    case msg.Code == GetBlockBodiesMsg:
        // Decode the retrieval message
        var query getBlockBodiesData
        if err := msg.Decode(&query); err != nil {
            return errResp(ErrDecode, "msg %v: %v", msg, err)
        }

        msgStream := rlp.NewStream(bytes.NewBuffer(query.Hashes), uint64(len(query.Hashes)))
        if _, err := msgStream.List(); err != nil {
            return err
        }
        // Gather blocks until the fetch or network limits is reached
        var (
            hash   common.Hash
            bytes  int
            bodies []rlp.RawValue
        )
        for bytes < softResponseLimit && len(bodies) < downloader.MaxBlockFetch {
            // Retrieve the hash of the next block
            if err := msgStream.Decode(&hash); err == rlp.EOL {
                break
            } else if err != nil {
                return errResp(ErrDecode, "msg %v: %v", msg, err)
            }
            // Retrieve the requested block body, stopping if enough was found
            if data := pm.blockchain.GetBodyRLP(hash); len(data) != 0 {
                bodies = append(bodies, data)
                bytes += len(data)
            }
        }
        return p.SendBlockBodiesRLP(query.Flag, bodies)

    case msg.Code == BlockBodiesMsg:
        // A batch of block bodies arrived to one of our previous requests
        var request blockBodiesData
        if err := msg.Decode(&request); err != nil {
            return errResp(ErrDecode, "msg %v: %v", msg, err)
        }
        // Deliver them all to the downloader for queuing
        transactions := make([][]*types.Transaction, len(request.Bodies))
        uncles := make([][]*types.Header, len(request.Bodies))

        for i, body := range request.Bodies {
            transactions[i] = body.Transactions
            uncles[i] = body.Uncles
        }

        switch request.Flag {
        case fetcherReq:
            if len(transactions) > 0 || len(uncles) > 0 {
                pm.fetcher.FilterBodies(p.id, transactions, uncles, time.Now())
            }
        case downloaderReq:
            err := pm.downloader.DeliverBodies(p.id, transactions, uncles)
            if err != nil {
                log.Debug("Failed to deliver bodies", "err", err)
            }
        default:
            log.Debug("Got bodies with unexpected flag", "flag", request.Flag)
        }

    case msg.Code == GetNodeDataMsg:
        // Decode the retrieval message
        msgStream := rlp.NewStream(msg.Payload, uint64(msg.Size))
        if _, err := msgStream.List(); err != nil {
            return err
        }
        // Gather state data until the fetch or network limits is reached
        var (
            hash  common.Hash
            bytes int
            data  [][]byte
        )
        for bytes < softResponseLimit && len(data) < downloader.MaxStateFetch {
            // Retrieve the hash of the next state entry
            if err := msgStream.Decode(&hash); err == rlp.EOL {
                break
            } else if err != nil {
                return errResp(ErrDecode, "msg %v: %v", msg, err)
            }
            // Retrieve the requested state entry, stopping if enough was found
            if entry, err := pm.blockchain.TrieNode(hash); err == nil {
                data = append(data, entry)
                bytes += len(entry)
            }
        }
        return p.SendNodeData(data)

    case msg.Code == NodeDataMsg:
        // A batch of node state data arrived to one of our previous requests
        var data [][]byte
        if err := msg.Decode(&data); err != nil {
            return errResp(ErrDecode, "msg %v: %v", msg, err)
        }
        // Deliver all to the downloader
        if err := pm.downloader.DeliverNodeData(p.id, data); err != nil {
            log.Debug("Failed to deliver node state data", "err", err)
        }

    case msg.Code == GetReceiptsMsg:
        // Decode the retrieval message
        msgStream := rlp.NewStream(msg.Payload, uint64(msg.Size))
        if _, err := msgStream.List(); err != nil {
            return err
        }
        // Gather state data until the fetch or network limits is reached
        var (
            hash     common.Hash
            bytes    int
            receipts []rlp.RawValue
        )
        for bytes < softResponseLimit && len(receipts) < downloader.MaxReceiptFetch {
            // Retrieve the hash of the next block
            if err := msgStream.Decode(&hash); err == rlp.EOL {
                break
            } else if err != nil {
                return errResp(ErrDecode, "msg %v: %v", msg, err)
            }
            // Retrieve the requested block's receipts, skipping if unknown to us
            results := pm.blockchain.GetReceiptsByHash(hash)
            if results == nil {
                if header := pm.blockchain.GetHeaderByHash(hash); header == nil || header.ReceiptHash != types.EmptyRootHash {
                    continue
                }
            }
            // If known, encode and queue for response packet
            if encoded, err := rlp.EncodeToBytes(results); err != nil {
                log.Error("Failed to encode receipt", "err", err)
            } else {
                receipts = append(receipts, encoded)
                bytes += len(encoded)
            }
        }
        return p.SendReceiptsRLP(receipts)

    case msg.Code == ReceiptsMsg:
        // A batch of receipts arrived to one of our previous requests
        var receipts [][]*types.Receipt
        if err := msg.Decode(&receipts); err != nil {
            return errResp(ErrDecode, "msg %v: %v", msg, err)
        }
        // Deliver all to the downloader
        if err := pm.downloader.DeliverReceipts(p.id, receipts); err != nil {
            log.Debug("Failed to deliver receipts", "err", err)
        }

    case msg.Code == NewBlockHashesMsg:
        var announces newBlockHashesData
        if err := msg.Decode(&announces); err != nil {
            return errResp(ErrDecode, "%v: %v", msg, err)
        }
        // Mark the hashes as present at the remote node
        for _, block := range announces {
            p.MarkBlock(block.Hash)
        }
        // Schedule all the unknown hashes for retrieval
        unknown := make(newBlockHashesData, 0, len(announces))
        for _, block := range announces {
            if !pm.blockchain.HasBlock(block.Hash, block.Number) {
                unknown = append(unknown, block)
            }
        }
        for _, block := range unknown {
            pm.fetcher.Notify(p.id, block.Hash, block.Number, time.Now(), p.RequestOneHeader, p.FetchBodies)
        }

    case msg.Code == NewBlockMsg:
        // Retrieve and decode the propagated block
        var block types.Block
        if err := msg.Decode(&block); err != nil {
            return errResp(ErrDecode, "%v: %v", msg, err)
        }
        block.ReceivedAt = msg.ReceivedAt
        block.ReceivedFrom = p

        // Mark the peer as owning the block and schedule it for import
        p.MarkBlock(block.Hash())
        pm.fetcher.Enqueue(p.id, &block)

        // Assuming the block is importable by the peer, but possibly not yet done so,
        // calculate the head hash and number that the peer truly must have.
        var (
            trueHead   = block.ParentHash()
            trueNumber = block.NumberU64() - 1
        )
        // Update the peers number if better than the previous
        if _, number := p.Head(); trueNumber > number {
            p.SetHead(trueHead, trueNumber)

            // Schedule a sync if above ours. Note, this will not fire a sync for a gap of
            // a singe block (as the true number is below the propagated block), however this
            // scenario should easily be covered by the fetcher.
            currentBlock := pm.blockchain.CurrentBlock()
            if trueNumber > currentBlock.NumberU64() {
                go pm.synchronise(p)
            }
        }

    case msg.Code == TxMsg:
        // Transactions arrived, make sure we have a valid and fresh chain to handle them
        if atomic.LoadUint32(&pm.acceptTxs) == 0 {
            break
        }
        // Transactions can be processed, 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)
        }
        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())
        }
        types.GlobalSigCache.Add(types.NewEIP155Signer(pm.blockchain.Config().ChainID), txs)
        pm.txpool.AddRemotes(txs)

    case msg.Code == RecordMsg:
        var records []*enr.Record
        if err := msg.Decode(&records); err != nil {
            return errResp(ErrDecode, "msg %v: %v", msg, err)
        }
        for i, record := range records {
            if record == nil {
                return errResp(ErrDecode, "node record %d is nil", i)
            }
            p.MarkNodeRecord(rlpHash(record))
        }
        pm.nodeTable.AddRecords(records)

    // Block proposer-only messages.

    case msg.Code == CoreBlockMsg:
        if !pm.isBlockProposer {
            break
        }
        var blocks []*coreTypes.Block
        if err := msg.Decode(&blocks); err != nil {
            return errResp(ErrDecode, "msg %v: %v", msg, err)
        }
        for _, block := range blocks {
            pm.cache.addBlock(block)
            pm.receiveCh <- block
        }
    case msg.Code == VoteMsg:
        if !pm.isBlockProposer {
            break
        }
        var votes []*coreTypes.Vote
        if err := msg.Decode(&votes); err != nil {
            return errResp(ErrDecode, "msg %v: %v", msg, err)
        }
        for _, vote := range votes {
            if vote.Type >= coreTypes.VotePreCom {
                pm.cache.addVote(vote)
            }
            pm.receiveCh <- vote
        }
    case msg.Code == AgreementMsg:
        if !pm.isBlockProposer {
            break
        }
        // DKG set is receiver
        var agreement coreTypes.AgreementResult
        if err := msg.Decode(&agreement); err != nil {
            return errResp(ErrDecode, "msg %v: %v", msg, err)
        }
        p.MarkAgreement(rlpHash(agreement))
        pm.receiveCh <- &agreement
    case msg.Code == RandomnessMsg:
        if !pm.isBlockProposer {
            break
        }
        // Broadcast this to all peer
        var randomnesses []*coreTypes.BlockRandomnessResult
        if err := msg.Decode(&randomnesses); err != nil {
            return errResp(ErrDecode, "msg %v: %v", msg, err)
        }
        for _, randomness := range randomnesses {
            p.MarkRandomness(rlpHash(randomness))
            pm.receiveCh <- randomness
        }
    case msg.Code == DKGPrivateShareMsg:
        if !pm.isBlockProposer {
            break
        }
        // Do not relay this msg
        var ps dkgTypes.PrivateShare
        if err := msg.Decode(&ps); err != nil {
            return errResp(ErrDecode, "msg %v: %v", msg, err)
        }
        p.MarkDKGPrivateShares(rlpHash(ps))
        pm.receiveCh <- &ps
    case msg.Code == DKGPartialSignatureMsg:
        if !pm.isBlockProposer {
            break
        }
        // broadcast in DKG set
        var psig dkgTypes.PartialSignature
        if err := msg.Decode(&psig); err != nil {
            return errResp(ErrDecode, "msg %v: %v", msg, err)
        }
        pm.receiveCh <- &psig
    case msg.Code == PullBlocksMsg:
        if !pm.isBlockProposer {
            break
        }
        var hashes coreCommon.Hashes
        if err := msg.Decode(&hashes); err != nil {
            return errResp(ErrDecode, "msg %v: %v", msg, err)
        }
        blocks := pm.cache.blocks(hashes)
        log.Debug("Push blocks", "blocks", blocks)
        return p.SendCoreBlocks(blocks)
    case msg.Code == PullVotesMsg:
        if !pm.isBlockProposer {
            break
        }
        next, ok := pm.nextPullVote.Load(p.ID())
        if ok {
            nextTime := next.(time.Time)
            if nextTime.After(time.Now()) {
                break
            }
        }
        pm.nextPullVote.Store(p.ID(), time.Now().Add(pullVoteRateLimit))
        var pos coreTypes.Position
        if err := msg.Decode(&pos); err != nil {
            return errResp(ErrDecode, "msg %v: %v", msg, err)
        }
        votes := pm.cache.votes(pos)
        log.Debug("Push votes", "votes", votes)
        return p.SendVotes(votes)
    case msg.Code == PullRandomnessMsg:
        if !pm.isBlockProposer {
            break
        }
        var hashes coreCommon.Hashes
        if err := msg.Decode(&hashes); err != nil {
            return errResp(ErrDecode, "msg %v: %v", msg, err)
        }
        randomnesses := pm.cache.randomness(hashes)
        log.Debug("Push randomness", "randomness", randomnesses)
        return p.SendRandomnesses(randomnesses)
    case msg.Code == GetGovStateMsg:
        var hash common.Hash
        if err := msg.Decode(&hash); err != nil {
            return errResp(ErrDecode, "msg %v: %v", msg, err)
        }
        govState, err := pm.blockchain.GetGovStateByHash(hash)
        if err != nil {
            panic(err)
        }
        return p.SendGovState(govState)
    case msg.Code == GovStateMsg:
        var govState types.GovState
        if err := msg.Decode(&govState); err != nil {
            return errResp(ErrDecode, "msg %v: %v", msg, err)
        }
        if err := pm.downloader.DeliverGovState(p.id, &govState); err != nil {
            log.Debug("Failed to deliver govstates", "err", err)
        }
    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 {
        if parent := pm.blockchain.GetBlock(block.ParentHash(), block.NumberU64()-1); parent == nil {
            log.Error("Propagating dangling block", "number", block.Number(), "hash", hash)
            return
        }
        // Send the block to a subset of our peers
        transfer := peers[:int(math.Sqrt(float64(len(peers))))]
        for _, peer := range transfer {
            peer.AsyncSendNewBlock(block)
        }
        log.Trace("Propagated block", "hash", hash, "recipients", len(transfer), "duration", common.PrettyDuration(time.Since(block.ReceivedAt)))
        return
    }
    // Otherwise if the block is indeed in out own chain, announce it
    if pm.blockchain.HasBlock(hash, block.NumberU64()) {
        for _, peer := range peers {
            peer.AsyncSendNewBlockHash(block)
        }
        log.Trace("Announced block", "hash", hash, "recipients", len(peers), "duration", common.PrettyDuration(time.Since(block.ReceivedAt)))
    }
}

// BroadcastTxs will propagate a batch of transactions to all peers which are not known to
// already have the given transaction.
func (pm *ProtocolManager) BroadcastTxs(txs types.Transactions) {
    var txset = make(map[*peer]types.Transactions)

    // Broadcast transactions to a batch of peers not knowing about it
    for _, tx := range txs {
        peers := pm.peers.PeersWithoutTx(tx.Hash())
        for _, peer := range peers {
            txset[peer] = append(txset[peer], tx)
        }
        log.Trace("Broadcast transaction", "hash", tx.Hash(), "recipients", len(peers))
    }
    // FIXME include this again: peers = peers[:int(math.Sqrt(float64(len(peers))))]
    for peer, txs := range txset {
        peer.AsyncSendTransactions(txs)
    }
}

// BroadcastRecords will propagate node records to its peers.
func (pm *ProtocolManager) BroadcastRecords(records []*enr.Record) {
    var recordset = make(map[*peer][]*enr.Record)

    for _, record := range records {
        peers := pm.peers.PeersWithoutNodeRecord(rlpHash(record))
        for _, peer := range peers {
            recordset[peer] = append(recordset[peer], record)
        }
        log.Trace("Broadcast record", "recipients", len(peers))
    }

    for peer, records := range recordset {
        peer.AsyncSendNodeRecords(records)
    }
}

// BroadcastCoreBlock broadcasts the core block to all its peers.
func (pm *ProtocolManager) BroadcastCoreBlock(block *coreTypes.Block) {
    pm.cache.addBlock(block)
    for _, peer := range pm.peers.Peers() {
        peer.AsyncSendCoreBlocks([]*coreTypes.Block{block})
    }
}

// BroadcastVote broadcasts the given vote to all peers in same notary set
func (pm *ProtocolManager) BroadcastVote(vote *coreTypes.Vote) {
    if vote.Type >= coreTypes.VotePreCom {
        pm.cache.addVote(vote)
    }
    label := peerLabel{
        set:   notaryset,
        round: vote.Position.Round,
    }
    for _, peer := range pm.peers.PeersWithLabel(label) {
        peer.AsyncSendVotes([]*coreTypes.Vote{vote})
    }
}

func (pm *ProtocolManager) BroadcastAgreementResult(
    agreement *coreTypes.AgreementResult) {
    // send to dkg nodes first (direct)
    label := peerLabel{
        set:   dkgset,
        round: agreement.Position.Round,
    }
    for _, peer := range pm.peers.PeersWithLabel(label) {
        if !peer.knownAgreements.Contains(rlpHash(agreement)) {
            peer.AsyncSendAgreement(agreement)
        }
    }

    for _, peer := range pm.peers.PeersWithoutAgreement(rlpHash(agreement)) {
        peer.AsyncSendAgreement(agreement)
    }
}

func (pm *ProtocolManager) BroadcastRandomnessResult(
    randomness *coreTypes.BlockRandomnessResult) {
    pm.cache.addRandomness(randomness)
    // send to notary nodes first (direct)
    label := peerLabel{
        set:   notaryset,
        round: randomness.Position.Round,
    }
    randomnesses := []*coreTypes.BlockRandomnessResult{randomness}
    for _, peer := range pm.peers.PeersWithLabel(label) {
        if !peer.knownRandomnesses.Contains(rlpHash(randomness)) {
            peer.AsyncSendRandomnesses(randomnesses)
        }
    }

    for _, peer := range pm.peers.PeersWithoutRandomness(rlpHash(randomness)) {
        peer.AsyncSendRandomnesses(randomnesses)
    }
}

func (pm *ProtocolManager) SendDKGPrivateShare(
    pub coreCrypto.PublicKey, privateShare *dkgTypes.PrivateShare) {

    pk, err := crypto.UnmarshalPubkey(pub.Bytes())
    if err != nil {
        panic(err)
    }

    id := enode.PubkeyToIDV4(pk)

    if p := pm.peers.Peer(id.String()); p != nil {
        p.AsyncSendDKGPrivateShare(privateShare)
    } else {
        log.Error("Failed to send DKG private share", "publicKey", id.String())
    }
}

func (pm *ProtocolManager) BroadcastDKGPrivateShare(
    privateShare *dkgTypes.PrivateShare) {
    label := peerLabel{set: dkgset, round: privateShare.Round}
    for _, peer := range pm.peers.PeersWithLabel(label) {
        if !peer.knownDKGPrivateShares.Contains(rlpHash(privateShare)) {
            peer.AsyncSendDKGPrivateShare(privateShare)
        }
    }
}

func (pm *ProtocolManager) BroadcastDKGPartialSignature(
    psig *dkgTypes.PartialSignature) {
    label := peerLabel{set: dkgset, round: psig.Round}
    for _, peer := range pm.peers.PeersWithLabel(label) {
        peer.AsyncSendDKGPartialSignature(psig)
    }
}

func (pm *ProtocolManager) BroadcastPullBlocks(
    hashes coreCommon.Hashes) {
    // TODO(jimmy-dexon): pull from notary set only.
    for idx, peer := range pm.peers.Peers() {
        if idx >= maxPullPeers {
            break
        }
        peer.AsyncSendPullBlocks(hashes)
    }
}

func (pm *ProtocolManager) BroadcastPullVotes(
    pos coreTypes.Position) {
    label := peerLabel{
        set:   notaryset,
        round: pos.Round,
    }
    for idx, peer := range pm.peers.PeersWithLabel(label) {
        if idx >= maxPullVotePeers {
            break
        }
        peer.AsyncSendPullVotes(pos)
    }
}

func (pm *ProtocolManager) BroadcastPullRandomness(
    hashes coreCommon.Hashes) {
    // TODO(jimmy-dexon): pull from dkg set only.
    for idx, peer := range pm.peers.Peers() {
        if idx >= maxPullPeers {
            break
        }
        peer.AsyncSendPullRandomness(hashes)
    }
}

func (pm *ProtocolManager) txBroadcastLoop() {
    queueSizeMax := common.StorageSize(100 * 1024) // 100 KB
    currentSize := common.StorageSize(0)
    txs := make(types.Transactions, 0)
    for {
        select {
        case <-time.After(100 * time.Millisecond):
            pm.BroadcastTxs(txs)
            txs = txs[:0]
            currentSize = 0
        case event := <-pm.txsCh:
            txs = append(txs, event.Txs...)
            for _, tx := range event.Txs {
                currentSize += tx.Size()
            }
            if currentSize >= queueSizeMax {
                pm.BroadcastTxs(txs)
                txs = txs[:0]
                currentSize = 0
            }

        // Err() channel will be closed when unsubscribing.
        case <-pm.txsSub.Err():
            return
        }
    }
}

func (pm *ProtocolManager) finalizedBlockBroadcastLoop() {
    for {
        select {
        case event := <-pm.finalizedBlockCh:
            pm.BroadcastBlock(event.Block, true)
            pm.BroadcastBlock(event.Block, false)

        // Err() channel will be closed when unsubscribing.
        case <-pm.finalizedBlockSub.Err():
            return
        }
    }
}

func (pm *ProtocolManager) recordBroadcastLoop() {
    r := rand.New(rand.NewSource(time.Now().Unix()))
    t := time.NewTimer(0)
    defer t.Stop()

    for {
        select {
        case event := <-pm.recordsCh:
            pm.BroadcastRecords(event.Records)
            pm.peers.Refresh()

        case <-t.C:
            record := pm.srvr.Self().Record()
            log.Debug("refresh our node record", "seq", record.Seq())
            pm.nodeTable.AddRecords([]*enr.Record{record})

            // Log current peers connection status.
            pm.peers.Status()

            // Reset timer.
            d := 1*time.Minute + time.Duration(r.Int63n(60))*time.Second
            t.Reset(d)

        // Err() channel will be closed when unsubscribing.
        case <-pm.recordsSub.Err():
            return
        }
    }
}

// a loop keep building and maintaining peers in notary set.
// TODO: finish this
func (pm *ProtocolManager) peerSetLoop() {
    log.Debug("ProtocolManager: started peer set loop")

    round := pm.gov.Round()
    log.Trace("ProtocolManager: startup round", "round", round)

    if round < dexCore.DKGDelayRound {
        for i := round; i <= dexCore.DKGDelayRound; i++ {
            pm.peers.BuildConnection(i)
        }
    } else {
        pm.peers.BuildConnection(round)
    }

    for {
        select {
        case event := <-pm.chainHeadCh:
            pm.blockNumberGauge.Update(int64(event.Block.NumberU64()))

            if !pm.isBlockProposer {
                break
            }

            newRound := pm.gov.CRSRound()
            if newRound == 0 {
                break
            }

            log.Debug("ProtocolManager: new round", "round", newRound)
            if newRound == round {
                break
            }

            if newRound == round+1 {
                pm.peers.BuildConnection(newRound)
                if round >= 1 {
                    pm.peers.ForgetConnection(round - 1)
                }
            } else {
                // just forget all network connection and rebuild.
                pm.peers.ForgetConnection(round)

                if newRound >= 1 {
                    pm.peers.BuildConnection(newRound - 1)
                }
                pm.peers.BuildConnection(newRound)
            }
            round = newRound
        case <-pm.chainHeadSub.Err():
            return
        }
    }
}

// NodeInfo represents a short summary of the Ethereum sub-protocol metadata
// known about the host peer.
type NodeInfo struct {
    Network uint64              `json:"network"` // DEXON network ID (237=Mainnet, 238=Taiwan, 239=Taipei, 240=Yilan)
    Number  uint64              `json:"number"`  // Total difficulty of the host's blockchain
    Genesis common.Hash         `json:"genesis"` // SHA3 hash of the host's genesis block
    Config  *params.ChainConfig `json:"config"`  // Chain configuration for the fork rules
    Head    common.Hash         `json:"head"`    // SHA3 hash of the host's best owned block
}

// NodeInfo retrieves some protocol metadata about the running host node.
func (pm *ProtocolManager) NodeInfo() *NodeInfo {
    currentBlock := pm.blockchain.CurrentBlock()
    return &NodeInfo{
        Network: pm.networkID,
        Number:  currentBlock.NumberU64(),
        Genesis: pm.blockchain.Genesis().Hash(),
        Config:  pm.blockchain.Config(),
        Head:    currentBlock.Hash(),
    }
}