path: root/les/peer.go

// Copyright 2016 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 les implements the Light Ethereum Subprotocol.
package les

import (
    "errors"
    "fmt"
    "math/big"
    "sync"
    "time"

    "github.com/dexon-foundation/dexon/common"
    "github.com/dexon-foundation/dexon/core/types"
    "github.com/dexon-foundation/dexon/eth"
    "github.com/dexon-foundation/dexon/les/flowcontrol"
    "github.com/dexon-foundation/dexon/light"
    "github.com/dexon-foundation/dexon/p2p"
    "github.com/dexon-foundation/dexon/rlp"
)

var (
    errClosed             = errors.New("peer set is closed")
    errAlreadyRegistered  = errors.New("peer is already registered")
    errNotRegistered      = errors.New("peer is not registered")
    errInvalidHelpTrieReq = errors.New("invalid help trie request")
)

const maxResponseErrors = 50 // number of invalid responses tolerated (makes the protocol less brittle but still avoids spam)

const (
    announceTypeNone = iota
    announceTypeSimple
    announceTypeSigned
)

type peer struct {
    *p2p.Peer

    rw p2p.MsgReadWriter

    version int    // Protocol version negotiated
    network uint64 // Network ID being on

    announceType, requestAnnounceType uint64

    id string

    headInfo *announceData
    lock     sync.RWMutex

    announceChn chan announceData
    sendQueue   *execQueue

    poolEntry      *poolEntry
    hasBlock       func(common.Hash, uint64, bool) bool
    responseErrors int

    fcClient       *flowcontrol.ClientNode // nil if the peer is server only
    fcServer       *flowcontrol.ServerNode // nil if the peer is client only
    fcServerParams *flowcontrol.ServerParams
    fcCosts        requestCostTable
}

func newPeer(version int, network uint64, p *p2p.Peer, rw p2p.MsgReadWriter) *peer {
    id := p.ID()

    return &peer{
        Peer:        p,
        rw:          rw,
        version:     version,
        network:     network,
        id:          fmt.Sprintf("%x", id[:8]),
        announceChn: make(chan announceData, 20),
    }
}

func (p *peer) canQueue() bool {
    return p.sendQueue.canQueue()
}

func (p *peer) queueSend(f func()) {
    p.sendQueue.queue(f)
}

// Info gathers and returns a collection of metadata known about a peer.
func (p *peer) Info() *eth.PeerInfo {
    return &eth.PeerInfo{
        Version:    p.version,
        Difficulty: p.Td(),
        Head:       fmt.Sprintf("%x", p.Head()),
    }
}

// Head retrieves a copy of the current head (most recent) hash of the peer.
func (p *peer) Head() (hash common.Hash) {
    p.lock.RLock()
    defer p.lock.RUnlock()

    copy(hash[:], p.headInfo.Hash[:])
    return hash
}

func (p *peer) HeadAndTd() (hash common.Hash, td *big.Int) {
    p.lock.RLock()
    defer p.lock.RUnlock()

    copy(hash[:], p.headInfo.Hash[:])
    return hash, p.headInfo.Td
}

func (p *peer) headBlockInfo() blockInfo {
    p.lock.RLock()
    defer p.lock.RUnlock()

    return blockInfo{Hash: p.headInfo.Hash, Number: p.headInfo.Number, Td: p.headInfo.Td}
}

// Td retrieves the current total difficulty of a peer.
func (p *peer) Td() *big.Int {
    p.lock.RLock()
    defer p.lock.RUnlock()

    return new(big.Int).Set(p.headInfo.Td)
}

// waitBefore implements distPeer interface
func (p *peer) waitBefore(maxCost uint64) (time.Duration, float64) {
    return p.fcServer.CanSend(maxCost)
}

func sendRequest(w p2p.MsgWriter, msgcode, reqID, cost uint64, data interface{}) error {
    type req struct {
        ReqID uint64
        Data  interface{}
    }
    return p2p.Send(w, msgcode, req{reqID, data})
}

func sendResponse(w p2p.MsgWriter, msgcode, reqID, bv uint64, data interface{}) error {
    type resp struct {
        ReqID, BV uint64
        Data      interface{}
    }
    return p2p.Send(w, msgcode, resp{reqID, bv, data})
}

func (p *peer) GetRequestCost(msgcode uint64, amount int) uint64 {
    p.lock.RLock()
    defer p.lock.RUnlock()

    cost := p.fcCosts[msgcode].baseCost + p.fcCosts[msgcode].reqCost*uint64(amount)
    if cost > p.fcServerParams.BufLimit {
        cost = p.fcServerParams.BufLimit
    }
    return cost
}

// HasBlock checks if the peer has a given block
func (p *peer) HasBlock(hash common.Hash, number uint64, hasState bool) bool {
    p.lock.RLock()
    hasBlock := p.hasBlock
    p.lock.RUnlock()
    return hasBlock != nil && hasBlock(hash, number, hasState)
}

// SendAnnounce announces the availability of a number of blocks through
// a hash notification.
func (p *peer) SendAnnounce(request announceData) error {
    return p2p.Send(p.rw, AnnounceMsg, request)
}

// SendBlockHeaders sends a batch of block headers to the remote peer.
func (p *peer) SendBlockHeaders(reqID, bv uint64, headers []*types.Header) error {
    return sendResponse(p.rw, BlockHeadersMsg, reqID, bv, headers)
}

// SendBlockBodiesRLP sends a batch of block contents to the remote peer from
// an already RLP encoded format.
func (p *peer) SendBlockBodiesRLP(reqID, bv uint64, bodies []rlp.RawValue) error {
    return sendResponse(p.rw, BlockBodiesMsg, reqID, bv, bodies)
}

// SendCodeRLP sends a batch of arbitrary internal data, corresponding to the
// hashes requested.
func (p *peer) SendCode(reqID, bv uint64, data [][]byte) error {
    return sendResponse(p.rw, CodeMsg, reqID, bv, data)
}

// SendReceiptsRLP sends a batch of transaction receipts, corresponding to the
// ones requested from an already RLP encoded format.
func (p *peer) SendReceiptsRLP(reqID, bv uint64, receipts []rlp.RawValue) error {
    return sendResponse(p.rw, ReceiptsMsg, reqID, bv, receipts)
}

// SendProofs sends a batch of legacy LES/1 merkle proofs, corresponding to the ones requested.
func (p *peer) SendProofs(reqID, bv uint64, proofs proofsData) error {
    return sendResponse(p.rw, ProofsV1Msg, reqID, bv, proofs)
}

// SendProofsV2 sends a batch of merkle proofs, corresponding to the ones requested.
func (p *peer) SendProofsV2(reqID, bv uint64, proofs light.NodeList) error {
    return sendResponse(p.rw, ProofsV2Msg, reqID, bv, proofs)
}

// SendHeaderProofs sends a batch of legacy LES/1 header proofs, corresponding to the ones requested.
func (p *peer) SendHeaderProofs(reqID, bv uint64, proofs []ChtResp) error {
    return sendResponse(p.rw, HeaderProofsMsg, reqID, bv, proofs)
}

// SendHelperTrieProofs sends a batch of HelperTrie proofs, corresponding to the ones requested.
func (p *peer) SendHelperTrieProofs(reqID, bv uint64, resp HelperTrieResps) error {
    return sendResponse(p.rw, HelperTrieProofsMsg, reqID, bv, resp)
}

// SendTxStatus sends a batch of transaction status records, corresponding to the ones requested.
func (p *peer) SendTxStatus(reqID, bv uint64, stats []txStatus) error {
    return sendResponse(p.rw, TxStatusMsg, reqID, bv, stats)
}

// RequestHeadersByHash fetches a batch of blocks' headers corresponding to the
// specified header query, based on the hash of an origin block.
func (p *peer) RequestHeadersByHash(reqID, cost uint64, origin common.Hash, amount int, skip int, reverse bool) error {
    p.Log().Debug("Fetching batch of headers", "count", amount, "fromhash", origin, "skip", skip, "reverse", reverse)
    return sendRequest(p.rw, GetBlockHeadersMsg, reqID, cost, &getBlockHeadersData{Origin: hashOrNumber{Hash: origin}, Amount: uint64(amount), Skip: uint64(skip), Reverse: reverse})
}

// RequestHeadersByNumber fetches a batch of blocks' headers corresponding to the
// specified header query, based on the number of an origin block.
func (p *peer) RequestHeadersByNumber(reqID, cost, origin uint64, amount int, skip int, reverse bool) error {
    p.Log().Debug("Fetching batch of headers", "count", amount, "fromnum", origin, "skip", skip, "reverse", reverse)
    return sendRequest(p.rw, GetBlockHeadersMsg, reqID, cost, &getBlockHeadersData{Origin: hashOrNumber{Number: origin}, Amount: uint64(amount), Skip: uint64(skip), Reverse: reverse})
}

// RequestBodies fetches a batch of blocks' bodies corresponding to the hashes
// specified.
func (p *peer) RequestBodies(reqID, cost uint64, hashes []common.Hash) error {
    p.Log().Debug("Fetching batch of block bodies", "count", len(hashes))
    return sendRequest(p.rw, GetBlockBodiesMsg, reqID, cost, hashes)
}

// RequestCode fetches a batch of arbitrary data from a node's known state
// data, corresponding to the specified hashes.
func (p *peer) RequestCode(reqID, cost uint64, reqs []CodeReq) error {
    p.Log().Debug("Fetching batch of codes", "count", len(reqs))
    return sendRequest(p.rw, GetCodeMsg, reqID, cost, reqs)
}

// RequestReceipts fetches a batch of transaction receipts from a remote node.
func (p *peer) RequestReceipts(reqID, cost uint64, hashes []common.Hash) error {
    p.Log().Debug("Fetching batch of receipts", "count", len(hashes))
    return sendRequest(p.rw, GetReceiptsMsg, reqID, cost, hashes)
}

// RequestProofs fetches a batch of merkle proofs from a remote node.
func (p *peer) RequestProofs(reqID, cost uint64, reqs []ProofReq) error {
    p.Log().Debug("Fetching batch of proofs", "count", len(reqs))
    switch p.version {
    case lpv1:
        return sendRequest(p.rw, GetProofsV1Msg, reqID, cost, reqs)
    case lpv2:
        return sendRequest(p.rw, GetProofsV2Msg, reqID, cost, reqs)
    default:
        panic(nil)
    }
}

// RequestHelperTrieProofs fetches a batch of HelperTrie merkle proofs from a remote node.
func (p *peer) RequestHelperTrieProofs(reqID, cost uint64, data interface{}) error {
    switch p.version {
    case lpv1:
        reqs, ok := data.([]ChtReq)
        if !ok {
            return errInvalidHelpTrieReq
        }
        p.Log().Debug("Fetching batch of header proofs", "count", len(reqs))
        return sendRequest(p.rw, GetHeaderProofsMsg, reqID, cost, reqs)
    case lpv2:
        reqs, ok := data.([]HelperTrieReq)
        if !ok {
            return errInvalidHelpTrieReq
        }
        p.Log().Debug("Fetching batch of HelperTrie proofs", "count", len(reqs))
        return sendRequest(p.rw, GetHelperTrieProofsMsg, reqID, cost, reqs)
    default:
        panic(nil)
    }
}

// RequestTxStatus fetches a batch of transaction status records from a remote node.
func (p *peer) RequestTxStatus(reqID, cost uint64, txHashes []common.Hash) error {
    p.Log().Debug("Requesting transaction status", "count", len(txHashes))
    return sendRequest(p.rw, GetTxStatusMsg, reqID, cost, txHashes)
}

// SendTxStatus sends a batch of transactions to be added to the remote transaction pool.
func (p *peer) SendTxs(reqID, cost uint64, txs types.Transactions) error {
    p.Log().Debug("Fetching batch of transactions", "count", len(txs))
    switch p.version {
    case lpv1:
        return p2p.Send(p.rw, SendTxMsg, txs) // old message format does not include reqID
    case lpv2:
        return sendRequest(p.rw, SendTxV2Msg, reqID, cost, txs)
    default:
        panic(nil)
    }
}

type keyValueEntry struct {
    Key   string
    Value rlp.RawValue
}
type keyValueList []keyValueEntry
type keyValueMap map[string]rlp.RawValue

func (l keyValueList) add(key string, val interface{}) keyValueList {
    var entry keyValueEntry
    entry.Key = key
    if val == nil {
        val = uint64(0)
    }
    enc, err := rlp.EncodeToBytes(val)
    if err == nil {
        entry.Value = enc
    }
    return append(l, entry)
}

func (l keyValueList) decode() keyValueMap {
    m := make(keyValueMap)
    for _, entry := range l {
        m[entry.Key] = entry.Value
    }
    return m
}

func (m keyValueMap) get(key string, val interface{}) error {
    enc, ok := m[key]
    if !ok {
        return errResp(ErrMissingKey, "%s", key)
    }
    if val == nil {
        return nil
    }
    return rlp.DecodeBytes(enc, val)
}

func (p *peer) sendReceiveHandshake(sendList keyValueList) (keyValueList, error) {
    // Send out own handshake in a new thread
    errc := make(chan error, 1)
    go func() {
        errc <- p2p.Send(p.rw, StatusMsg, sendList)
    }()
    // In the mean time retrieve the remote status message
    msg, err := p.rw.ReadMsg()
    if err != nil {
        return nil, err
    }
    if msg.Code != StatusMsg {
        return nil, errResp(ErrNoStatusMsg, "first msg has code %x (!= %x)", msg.Code, StatusMsg)
    }
    if msg.Size > ProtocolMaxMsgSize {
        return nil, errResp(ErrMsgTooLarge, "%v > %v", msg.Size, ProtocolMaxMsgSize)
    }
    // Decode the handshake
    var recvList keyValueList
    if err := msg.Decode(&recvList); err != nil {
        return nil, errResp(ErrDecode, "msg %v: %v", msg, err)
    }
    if err := <-errc; err != nil {
        return nil, err
    }
    return recvList, nil
}

// Handshake executes the les protocol handshake, negotiating version number,
// network IDs, difficulties, head and genesis blocks.
func (p *peer) Handshake(td *big.Int, head common.Hash, headNum uint64, genesis common.Hash, server *LesServer) error {
    p.lock.Lock()
    defer p.lock.Unlock()

    var send keyValueList
    send = send.add("protocolVersion", uint64(p.version))
    send = send.add("networkId", p.network)
    send = send.add("headTd", td)
    send = send.add("headHash", head)
    send = send.add("headNum", headNum)
    send = send.add("genesisHash", genesis)
    if server != nil {
        send = send.add("serveHeaders", nil)
        send = send.add("serveChainSince", uint64(0))
        send = send.add("serveStateSince", uint64(0))
        send = send.add("txRelay", nil)
        send = send.add("flowControl/BL", server.defParams.BufLimit)
        send = send.add("flowControl/MRR", server.defParams.MinRecharge)
        list := server.fcCostStats.getCurrentList()
        send = send.add("flowControl/MRC", list)
        p.fcCosts = list.decode()
    } else {
        p.requestAnnounceType = announceTypeSimple // set to default until "very light" client mode is implemented
        send = send.add("announceType", p.requestAnnounceType)
    }
    recvList, err := p.sendReceiveHandshake(send)
    if err != nil {
        return err
    }
    recv := recvList.decode()

    var rGenesis, rHash common.Hash
    var rVersion, rNetwork, rNum uint64
    var rTd *big.Int

    if err := recv.get("protocolVersion", &rVersion); err != nil {
        return err
    }
    if err := recv.get("networkId", &rNetwork); err != nil {
        return err
    }
    if err := recv.get("headTd", &rTd); err != nil {
        return err
    }
    if err := recv.get("headHash", &rHash); err != nil {
        return err
    }
    if err := recv.get("headNum", &rNum); err != nil {
        return err
    }
    if err := recv.get("genesisHash", &rGenesis); err != nil {
        return err
    }

    if rGenesis != genesis {
        return errResp(ErrGenesisBlockMismatch, "%x (!= %x)", rGenesis[:8], genesis[:8])
    }
    if rNetwork != p.network {
        return errResp(ErrNetworkIdMismatch, "%d (!= %d)", rNetwork, p.network)
    }
    if int(rVersion) != p.version {
        return errResp(ErrProtocolVersionMismatch, "%d (!= %d)", rVersion, p.version)
    }
    if server != nil {
        // until we have a proper peer connectivity API, allow LES connection to other servers
        /*if recv.get("serveStateSince", nil) == nil {
            return errResp(ErrUselessPeer, "wanted client, got server")
        }*/
        if recv.get("announceType", &p.announceType) != nil {
            p.announceType = announceTypeSimple
        }
        p.fcClient = flowcontrol.NewClientNode(server.fcManager, server.defParams)
    } else {
        if recv.get("serveChainSince", nil) != nil {
            return errResp(ErrUselessPeer, "peer cannot serve chain")
        }
        if recv.get("serveStateSince", nil) != nil {
            return errResp(ErrUselessPeer, "peer cannot serve state")
        }
        if recv.get("txRelay", nil) != nil {
            return errResp(ErrUselessPeer, "peer cannot relay transactions")
        }
        params := &flowcontrol.ServerParams{}
        if err := recv.get("flowControl/BL", &params.BufLimit); err != nil {
            return err
        }
        if err := recv.get("flowControl/MRR", &params.MinRecharge); err != nil {
            return err
        }
        var MRC RequestCostList
        if err := recv.get("flowControl/MRC", &MRC); err != nil {
            return err
        }
        p.fcServerParams = params
        p.fcServer = flowcontrol.NewServerNode(params)
        p.fcCosts = MRC.decode()
    }

    p.headInfo = &announceData{Td: rTd, Hash: rHash, Number: rNum}
    return nil
}

// String implements fmt.Stringer.
func (p *peer) String() string {
    return fmt.Sprintf("Peer %s [%s]", p.id,
        fmt.Sprintf("les/%d", p.version),
    )
}

// peerSetNotify is a callback interface to notify services about added or
// removed peers
type peerSetNotify interface {
    registerPeer(*peer)
    unregisterPeer(*peer)
}

// peerSet represents the collection of active peers currently participating in
// the Light Ethereum sub-protocol.
type peerSet struct {
    peers      map[string]*peer
    lock       sync.RWMutex
    notifyList []peerSetNotify
    closed     bool
}

// newPeerSet creates a new peer set to track the active participants.
func newPeerSet() *peerSet {
    return &peerSet{
        peers: make(map[string]*peer),
    }
}

// notify adds a service to be notified about added or removed peers
func (ps *peerSet) notify(n peerSetNotify) {
    ps.lock.Lock()
    ps.notifyList = append(ps.notifyList, n)
    peers := make([]*peer, 0, len(ps.peers))
    for _, p := range ps.peers {
        peers = append(peers, p)
    }
    ps.lock.Unlock()

    for _, p := range peers {
        n.registerPeer(p)
    }
}

// Register injects a new peer into the working set, or returns an error if the
// peer is already known.
func (ps *peerSet) Register(p *peer) error {
    ps.lock.Lock()
    if ps.closed {
        ps.lock.Unlock()
        return errClosed
    }
    if _, ok := ps.peers[p.id]; ok {
        ps.lock.Unlock()
        return errAlreadyRegistered
    }
    ps.peers[p.id] = p
    p.sendQueue = newExecQueue(100)
    peers := make([]peerSetNotify, len(ps.notifyList))
    copy(peers, ps.notifyList)
    ps.lock.Unlock()

    for _, n := range peers {
        n.registerPeer(p)
    }
    return nil
}

// Unregister removes a remote peer from the active set, disabling any further
// actions to/from that particular entity. It also initiates disconnection at the networking layer.
func (ps *peerSet) Unregister(id string) error {
    ps.lock.Lock()
    if p, ok := ps.peers[id]; !ok {
        ps.lock.Unlock()
        return errNotRegistered
    } else {
        delete(ps.peers, id)
        peers := make([]peerSetNotify, len(ps.notifyList))
        copy(peers, ps.notifyList)
        ps.lock.Unlock()

        for _, n := range peers {
            n.unregisterPeer(p)
        }
        p.sendQueue.quit()
        p.Peer.Disconnect(p2p.DiscUselessPeer)
        return nil
    }
}

// AllPeerIDs returns a list of all registered peer IDs
func (ps *peerSet) AllPeerIDs() []string {
    ps.lock.RLock()
    defer ps.lock.RUnlock()

    res := make([]string, len(ps.peers))
    idx := 0
    for id := range ps.peers {
        res[idx] = id
        idx++
    }
    return res
}

// Peer retrieves the registered peer with the given id.
func (ps *peerSet) Peer(id string) *peer {
    ps.lock.RLock()
    defer ps.lock.RUnlock()

    return ps.peers[id]
}

// Len returns if the current number of peers in the set.
func (ps *peerSet) Len() int {
    ps.lock.RLock()
    defer ps.lock.RUnlock()

    return len(ps.peers)
}

// BestPeer retrieves the known peer with the currently highest total difficulty.
func (ps *peerSet) BestPeer() *peer {
    ps.lock.RLock()
    defer ps.lock.RUnlock()

    var (
        bestPeer *peer
        bestTd   *big.Int
    )
    for _, p := range ps.peers {
        if td := p.Td(); bestPeer == nil || td.Cmp(bestTd) > 0 {
            bestPeer, bestTd = p, td
        }
    }
    return bestPeer
}

// AllPeers returns all peers in a list
func (ps *peerSet) AllPeers() []*peer {
    ps.lock.RLock()
    defer ps.lock.RUnlock()

    list := make([]*peer, len(ps.peers))
    i := 0
    for _, peer := range ps.peers {
        list[i] = peer
        i++
    }
    return list
}

// Close disconnects all peers.
// No new peers can be registered after Close has returned.
func (ps *peerSet) Close() {
    ps.lock.Lock()
    defer ps.lock.Unlock()

    for _, p := range ps.peers {
        p.Disconnect(p2p.DiscQuitting)
    }
    ps.closed = true
}