path: root/whisper/whisperv6/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 whisperv6

import (
    "fmt"
    "math"
    "time"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/log"
    "github.com/ethereum/go-ethereum/p2p"
    "github.com/ethereum/go-ethereum/rlp"
    set "gopkg.in/fatih/set.v0"
)

// Peer represents a whisper protocol peer connection.
type Peer struct {
    host *Whisper
    peer *p2p.Peer
    ws   p2p.MsgReadWriter

    trusted        bool
    powRequirement float64
    bloomFilter    []byte
    fullNode       bool

    known *set.Set // Messages already known by the peer to avoid wasting bandwidth

    quit chan struct{}
}

// newPeer creates a new whisper peer object, but does not run the handshake itself.
func newPeer(host *Whisper, remote *p2p.Peer, rw p2p.MsgReadWriter) *Peer {
    return &Peer{
        host:           host,
        peer:           remote,
        ws:             rw,
        trusted:        false,
        powRequirement: 0.0,
        known:          set.New(),
        quit:           make(chan struct{}),
        bloomFilter:    makeFullNodeBloom(),
        fullNode:       true,
    }
}

// start initiates the peer updater, periodically broadcasting the whisper packets
// into the network.
func (peer *Peer) start() {
    go peer.update()
    log.Trace("start", "peer", peer.ID())
}

// stop terminates the peer updater, stopping message forwarding to it.
func (peer *Peer) stop() {
    close(peer.quit)
    log.Trace("stop", "peer", peer.ID())
}

// handshake sends the protocol initiation status message to the remote peer and
// verifies the remote status too.
func (peer *Peer) handshake() error {
    // Send the handshake status message asynchronously
    errc := make(chan error, 1)
    go func() {
        pow := peer.host.MinPow()
        powConverted := math.Float64bits(pow)
        bloom := peer.host.BloomFilter()
        errc <- p2p.SendItems(peer.ws, statusCode, ProtocolVersion, powConverted, bloom)
    }()

    // Fetch the remote status packet and verify protocol match
    packet, err := peer.ws.ReadMsg()
    if err != nil {
        return err
    }
    if packet.Code != statusCode {
        return fmt.Errorf("peer [%x] sent packet %x before status packet", peer.ID(), packet.Code)
    }
    s := rlp.NewStream(packet.Payload, uint64(packet.Size))
    _, err = s.List()
    if err != nil {
        return fmt.Errorf("peer [%x] sent bad status message: %v", peer.ID(), err)
    }
    peerVersion, err := s.Uint()
    if err != nil {
        return fmt.Errorf("peer [%x] sent bad status message (unable to decode version): %v", peer.ID(), err)
    }
    if peerVersion != ProtocolVersion {
        return fmt.Errorf("peer [%x]: protocol version mismatch %d != %d", peer.ID(), peerVersion, ProtocolVersion)
    }

    // only version is mandatory, subsequent parameters are optional
    powRaw, err := s.Uint()
    if err == nil {
        pow := math.Float64frombits(powRaw)
        if math.IsInf(pow, 0) || math.IsNaN(pow) || pow < 0.0 {
            return fmt.Errorf("peer [%x] sent bad status message: invalid pow", peer.ID())
        }
        peer.powRequirement = pow

        var bloom []byte
        err = s.Decode(&bloom)
        if err == nil {
            sz := len(bloom)
            if sz != bloomFilterSize && sz != 0 {
                return fmt.Errorf("peer [%x] sent bad status message: wrong bloom filter size %d", peer.ID(), sz)
            }
            peer.setBloomFilter(bloom)
        }
    }

    if err := <-errc; err != nil {
        return fmt.Errorf("peer [%x] failed to send status packet: %v", peer.ID(), err)
    }
    return nil
}

// update executes periodic operations on the peer, including message transmission
// and expiration.
func (peer *Peer) update() {
    // Start the tickers for the updates
    expire := time.NewTicker(expirationCycle)
    transmit := time.NewTicker(transmissionCycle)

    // Loop and transmit until termination is requested
    for {
        select {
        case <-expire.C:
            peer.expire()

        case <-transmit.C:
            if err := peer.broadcast(); err != nil {
                log.Trace("broadcast failed", "reason", err, "peer", peer.ID())
                return
            }

        case <-peer.quit:
            return
        }
    }
}

// mark marks an envelope known to the peer so that it won't be sent back.
func (peer *Peer) mark(envelope *Envelope) {
    peer.known.Add(envelope.Hash())
}

// marked checks if an envelope is already known to the remote peer.
func (peer *Peer) marked(envelope *Envelope) bool {
    return peer.known.Has(envelope.Hash())
}

// expire iterates over all the known envelopes in the host and removes all
// expired (unknown) ones from the known list.
func (peer *Peer) expire() {
    unmark := make(map[common.Hash]struct{})
    peer.known.Each(func(v interface{}) bool {
        if !peer.host.isEnvelopeCached(v.(common.Hash)) {
            unmark[v.(common.Hash)] = struct{}{}
        }
        return true
    })
    // Dump all known but no longer cached
    for hash := range unmark {
        peer.known.Remove(hash)
    }
}

// broadcast iterates over the collection of envelopes and transmits yet unknown
// ones over the network.
func (peer *Peer) broadcast() error {
    envelopes := peer.host.Envelopes()
    bundle := make([]*Envelope, 0, len(envelopes))
    for _, envelope := range envelopes {
        if !peer.marked(envelope) && envelope.PoW() >= peer.powRequirement && peer.bloomMatch(envelope) {
            bundle = append(bundle, envelope)
        }
    }

    if len(bundle) > 0 {
        // transmit the batch of envelopes
        if err := p2p.Send(peer.ws, messagesCode, bundle); err != nil {
            return err
        }

        // mark envelopes only if they were successfully sent
        for _, e := range bundle {
            peer.mark(e)
        }

        log.Trace("broadcast", "num. messages", len(bundle))
    }
    return nil
}

// ID returns a peer's id
func (peer *Peer) ID() []byte {
    id := peer.peer.ID()
    return id[:]
}

func (peer *Peer) notifyAboutPowRequirementChange(pow float64) error {
    i := math.Float64bits(pow)
    return p2p.Send(peer.ws, powRequirementCode, i)
}

func (peer *Peer) notifyAboutBloomFilterChange(bloom []byte) error {
    return p2p.Send(peer.ws, bloomFilterExCode, bloom)
}

func (peer *Peer) bloomMatch(env *Envelope) bool {
    return peer.fullNode || bloomFilterMatch(peer.bloomFilter, env.Bloom())
}

func (peer *Peer) setBloomFilter(bloom []byte) {
    peer.bloomFilter = bloom
    peer.fullNode = isFullNode(bloom)
    if peer.fullNode && peer.bloomFilter == nil {
        peer.bloomFilter = makeFullNodeBloom()
    }
}

func makeFullNodeBloom() []byte {
    bloom := make([]byte, bloomFilterSize)
    for i := 0; i < bloomFilterSize; i++ {
        bloom[i] = 0xFF
    }
    return bloom
}