path: root/dashboard/peers.go

// Copyright 2019 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 dashboard

import (
    "container/list"
    "strings"
    "time"

    "github.com/ethereum/go-ethereum/metrics"

    "github.com/ethereum/go-ethereum/log"
    "github.com/ethereum/go-ethereum/p2p"
)

const (
    eventBufferLimit = 128 // Maximum number of buffered peer events.
    knownPeerLimit   = 100 // Maximum number of stored peers, which successfully made the handshake.
    attemptLimit     = 200 // Maximum number of stored peers, which failed to make the handshake.

    // eventLimit is the maximum number of the dashboard's custom peer events,
    // that are collected between two metering period and sent to the clients
    // as one message.
    // TODO (kurkomisi): Limit the number of events.
    eventLimit = knownPeerLimit << 2
)

// peerContainer contains information about the node's peers. This data structure
// maintains the metered peer data based on the different behaviours of the peers.
//
// Every peer has an IP address, and the peers that manage to make the handshake
// (known peers) have node IDs too. There can appear more peers with the same IP,
// therefore the peer container data structure is a tree consisting of a map of
// maps, where the first key groups the peers by IP, while the second one groups
// them by the node ID. The known peers can be active if their connection is still
// open, or inactive otherwise. The peers failing before the handshake (unknown
// peers) only have IP addresses, so their connection attempts are stored as part
// of the value of the outer map.
//
// Another criteria is to limit the number of metered peers so that
// they don't fill the memory. The selection order is based on the
// peers activity: the peers that are inactive for the longest time
// are thrown first. For the selection a fifo list is used which is
// linked to the bottom of the peer tree in a way that every activity
// of the peer pushes the peer to the end of the list, so the inactive
// ones come to the front. When a peer has some activity, it is removed
// from and reinserted into the list. When the length of the list reaches
// the limit, the first element is removed from the list, as well as from
// the tree.
//
// The active peers have priority over the inactive ones, therefore
// they have their own list. The separation makes it sure that the
// inactive peers are always removed before the active ones.
//
// The peers that don't manage to make handshake are not inserted into the list,
// only their connection attempts are appended to the array belonging to their IP.
// In order to keep the fifo principle, a super array contains the order of the
// attempts, and when the overall count reaches the limit, the earliest attempt is
// removed from the beginning of its array.
//
// This data structure makes it possible to marshal the peer
// history simply by passing it to the JSON marshaler.
type peerContainer struct {
    // Bundles is the outer map using the peer's IP address as key.
    Bundles map[string]*peerBundle `json:"bundles,omitempty"`

    activeCount int // Number of the still connected peers

    // inactivePeers contains the peers with closed connection in chronological order.
    inactivePeers *list.List

    // attemptOrder is the super array containing the IP addresses, from which
    // the peers attempted to connect then failed before/during the handshake.
    // Its values are appended in chronological order, which means that the
    // oldest attempt is at the beginning of the array. When the first element
    // is removed, the first element of the related bundle's attempt array is
    // removed too, ensuring that always the latest attempts are stored.
    attemptOrder []string

    // geodb is the geoip database used to retrieve the peers' geographical location.
    geodb *geoDB
}

// newPeerContainer returns a new instance of the peer container.
func newPeerContainer(geodb *geoDB) *peerContainer {
    return &peerContainer{
        Bundles:       make(map[string]*peerBundle),
        inactivePeers: list.New(),
        attemptOrder:  make([]string, 0, attemptLimit),
        geodb:         geodb,
    }
}

// bundle inserts a new peer bundle into the map, if the peer belonging
// to the given IP wasn't metered so far. In this case retrieves the location of
// the IP address from the database and creates a corresponding peer event.
// Returns the bundle belonging to the given IP and the events occurring during
// the initialization.
func (pc *peerContainer) bundle(ip string) (*peerBundle, []*peerEvent) {
    var events []*peerEvent
    if _, ok := pc.Bundles[ip]; !ok {
        location := pc.geodb.location(ip)
        events = append(events, &peerEvent{
            IP:       ip,
            Location: location,
        })
        pc.Bundles[ip] = &peerBundle{
            Location:   location,
            KnownPeers: make(map[string]*knownPeer),
        }
    }
    return pc.Bundles[ip], events
}

// extendKnown handles the events of the successfully connected peers.
// Returns the events occurring during the extension.
func (pc *peerContainer) extendKnown(event *peerEvent) []*peerEvent {
    bundle, events := pc.bundle(event.IP)
    peer, peerEvents := bundle.knownPeer(event.IP, event.ID)
    events = append(events, peerEvents...)
    // Append the connect and the disconnect events to
    // the corresponding arrays keeping the limit.
    switch {
    case event.Connected != nil:
        peer.Connected = append(peer.Connected, event.Connected)
        if first := len(peer.Connected) - sampleLimit; first > 0 {
            peer.Connected = peer.Connected[first:]
        }
        peer.Active = true
        events = append(events, &peerEvent{
            Activity: Active,
            IP:       peer.ip,
            ID:       peer.id,
        })
        pc.activeCount++
        if peer.listElement != nil {
            _ = pc.inactivePeers.Remove(peer.listElement)
            peer.listElement = nil
        }
    case event.Disconnected != nil:
        peer.Disconnected = append(peer.Disconnected, event.Disconnected)
        if first := len(peer.Disconnected) - sampleLimit; first > 0 {
            peer.Disconnected = peer.Disconnected[first:]
        }
        peer.Active = false
        events = append(events, &peerEvent{
            Activity: Inactive,
            IP:       peer.ip,
            ID:       peer.id,
        })
        pc.activeCount--
        if peer.listElement != nil {
            // If the peer is already in the list, remove and reinsert it.
            _ = pc.inactivePeers.Remove(peer.listElement)
        }
        // Insert the peer into the list.
        peer.listElement = pc.inactivePeers.PushBack(peer)
    }
    for pc.inactivePeers.Len() > 0 && pc.activeCount+pc.inactivePeers.Len() > knownPeerLimit {
        // While the count of the known peers is greater than the limit,
        // remove the first element from the inactive peer list and from the map.
        if removedPeer, ok := pc.inactivePeers.Remove(pc.inactivePeers.Front()).(*knownPeer); ok {
            events = append(events, pc.removeKnown(removedPeer.ip, removedPeer.id)...)
        } else {
            log.Warn("Failed to parse the removed peer")
        }
    }
    if pc.activeCount > knownPeerLimit {
        log.Warn("Number of active peers is greater than the limit")
    }
    return events
}

// handleAttempt handles the events of the peers failing before/during the handshake.
// Returns the events occurring during the extension.
func (pc *peerContainer) handleAttempt(event *peerEvent) []*peerEvent {
    bundle, events := pc.bundle(event.IP)
    bundle.Attempts = append(bundle.Attempts, &peerAttempt{
        Connected:    *event.Connected,
        Disconnected: *event.Disconnected,
    })
    pc.attemptOrder = append(pc.attemptOrder, event.IP)
    for len(pc.attemptOrder) > attemptLimit {
        // While the length of the connection attempt order array is greater
        // than the limit, remove the first element from the involved peer's
        // array and also from the super array.
        events = append(events, pc.removeAttempt(pc.attemptOrder[0])...)
        pc.attemptOrder = pc.attemptOrder[1:]
    }
    return events
}

// peerBundle contains the peers belonging to a given IP address.
type peerBundle struct {
    // Location contains the geographical location based on the bundle's IP address.
    Location *geoLocation `json:"location,omitempty"`

    // KnownPeers is the inner map of the metered peer
    // maintainer data structure using the node ID as key.
    KnownPeers map[string]*knownPeer `json:"knownPeers,omitempty"`

    // Attempts contains the failed connection attempts of the
    // peers belonging to a given IP address in chronological order.
    Attempts []*peerAttempt `json:"attempts,omitempty"`
}

// removeKnown removes the known peer belonging to the
// given IP address and node ID from the peer tree.
func (pc *peerContainer) removeKnown(ip, id string) (events []*peerEvent) {
    // TODO (kurkomisi): Remove peers that don't have traffic samples anymore.
    if bundle, ok := pc.Bundles[ip]; ok {
        if _, ok := bundle.KnownPeers[id]; ok {
            events = append(events, &peerEvent{
                Remove: RemoveKnown,
                IP:     ip,
                ID:     id,
            })
            delete(bundle.KnownPeers, id)
        } else {
            log.Warn("No peer to remove", "ip", ip, "id", id)
        }
        if len(bundle.KnownPeers) < 1 && len(bundle.Attempts) < 1 {
            events = append(events, &peerEvent{
                Remove: RemoveBundle,
                IP:     ip,
            })
            delete(pc.Bundles, ip)
        }
    } else {
        log.Warn("No bundle to remove", "ip", ip)
    }
    return events
}

// removeAttempt removes the peer attempt belonging to the
// given IP address and node ID from the peer tree.
func (pc *peerContainer) removeAttempt(ip string) (events []*peerEvent) {
    if bundle, ok := pc.Bundles[ip]; ok {
        if len(bundle.Attempts) > 0 {
            events = append(events, &peerEvent{
                Remove: RemoveAttempt,
                IP:     ip,
            })
            bundle.Attempts = bundle.Attempts[1:]
        }
        if len(bundle.Attempts) < 1 && len(bundle.KnownPeers) < 1 {
            events = append(events, &peerEvent{
                Remove: RemoveBundle,
                IP:     ip,
            })
            delete(pc.Bundles, ip)
        }
    }
    return events
}

// knownPeer inserts a new peer into the map, if the peer belonging
// to the given IP address and node ID wasn't metered so far. Returns the peer
// belonging to the given IP and ID as well as the events occurring during the
// initialization.
func (bundle *peerBundle) knownPeer(ip, id string) (*knownPeer, []*peerEvent) {
    var events []*peerEvent
    if _, ok := bundle.KnownPeers[id]; !ok {
        now := time.Now()
        ingress := emptyChartEntries(now, sampleLimit)
        egress := emptyChartEntries(now, sampleLimit)
        events = append(events, &peerEvent{
            IP:      ip,
            ID:      id,
            Ingress: append([]*ChartEntry{}, ingress...),
            Egress:  append([]*ChartEntry{}, egress...),
        })
        bundle.KnownPeers[id] = &knownPeer{
            ip:      ip,
            id:      id,
            Ingress: ingress,
            Egress:  egress,
        }
    }
    return bundle.KnownPeers[id], events
}

// knownPeer contains the metered data of a particular peer.
type knownPeer struct {
    // Connected contains the timestamps of the peer's connection events.
    Connected []*time.Time `json:"connected,omitempty"`

    // Disconnected contains the timestamps of the peer's disconnection events.
    Disconnected []*time.Time `json:"disconnected,omitempty"`

    // Ingress and Egress contain the peer's traffic samples, which are collected
    // periodically from the metrics registry.
    //
    // A peer can connect multiple times, and we want to visualize the time
    // passed between two connections, so after the first connection a 0 value
    // is appended to the traffic arrays even if the peer is inactive until the
    // peer is removed.
    Ingress ChartEntries `json:"ingress,omitempty"`
    Egress  ChartEntries `json:"egress,omitempty"`

    Active bool `json:"active"` // Denotes if the peer is still connected.

    listElement *list.Element // Pointer to the peer element in the list.
    ip, id      string        // The IP and the ID by which the peer can be accessed in the tree.
    prevIngress float64
    prevEgress  float64
}

// peerAttempt contains a failed peer connection attempt's attributes.
type peerAttempt struct {
    // Connected contains the timestamp of the connection attempt's moment.
    Connected time.Time `json:"connected"`

    // Disconnected contains the timestamp of the
    // moment when the connection attempt failed.
    Disconnected time.Time `json:"disconnected"`
}

type RemovedPeerType string
type ActivityType string

const (
    RemoveKnown   RemovedPeerType = "known"
    RemoveAttempt RemovedPeerType = "attempt"
    RemoveBundle  RemovedPeerType = "bundle"

    Active   ActivityType = "active"
    Inactive ActivityType = "inactive"
)

// peerEvent contains the attributes of a peer event.
type peerEvent struct {
    IP           string          `json:"ip,omitempty"`           // IP address of the peer.
    ID           string          `json:"id,omitempty"`           // Node ID of the peer.
    Remove       RemovedPeerType `json:"remove,omitempty"`       // Type of the peer that is to be removed.
    Location     *geoLocation    `json:"location,omitempty"`     // Geographical location of the peer.
    Connected    *time.Time      `json:"connected,omitempty"`    // Timestamp of the connection moment.
    Disconnected *time.Time      `json:"disconnected,omitempty"` // Timestamp of the disonnection moment.
    Ingress      ChartEntries    `json:"ingress,omitempty"`      // Ingress samples.
    Egress       ChartEntries    `json:"egress,omitempty"`       // Egress samples.
    Activity     ActivityType    `json:"activity,omitempty"`     // Connection status change.
}

// trafficMap is a container for the periodically collected peer traffic.
type trafficMap map[string]map[string]float64

// insert inserts a new value to the traffic map. Overwrites
// the value at the given ip and id if that already exists.
func (m *trafficMap) insert(ip, id string, val float64) {
    if _, ok := (*m)[ip]; !ok {
        (*m)[ip] = make(map[string]float64)
    }
    (*m)[ip][id] = val
}

// collectPeerData gathers data about the peers and sends it to the clients.
func (db *Dashboard) collectPeerData() {
    defer db.wg.Done()

    // Open the geodb database for IP to geographical information conversions.
    var err error
    db.geodb, err = openGeoDB()
    if err != nil {
        log.Warn("Failed to open geodb", "err", err)
        return
    }
    defer db.geodb.close()

    peerCh := make(chan p2p.MeteredPeerEvent, eventBufferLimit) // Peer event channel.
    subPeer := p2p.SubscribeMeteredPeerEvent(peerCh)            // Subscribe to peer events.
    defer subPeer.Unsubscribe()                                 // Unsubscribe at the end.

    ticker := time.NewTicker(db.config.Refresh)
    defer ticker.Stop()

    type registryFunc func(name string, i interface{})
    type collectorFunc func(traffic *trafficMap) registryFunc

    // trafficCollector generates a function that can be passed to
    // the prefixed peer registry in order to collect the metered
    // traffic data from each peer meter.
    trafficCollector := func(prefix string) collectorFunc {
        // This part makes is possible to collect the
        // traffic data into a map from outside.
        return func(traffic *trafficMap) registryFunc {
            // The function which can be passed to the registry.
            return func(name string, i interface{}) {
                if m, ok := i.(metrics.Meter); ok {
                    // The name of the meter has the format: <common traffic prefix><IP>/<ID>
                    if k := strings.Split(strings.TrimPrefix(name, prefix), "/"); len(k) == 2 {
                        traffic.insert(k[0], k[1], float64(m.Count()))
                    } else {
                        log.Warn("Invalid meter name", "name", name, "prefix", prefix)
                    }
                } else {
                    log.Warn("Invalid meter type", "name", name)
                }
            }
        }
    }
    collectIngress := trafficCollector(p2p.MetricsInboundTraffic + "/")
    collectEgress := trafficCollector(p2p.MetricsOutboundTraffic + "/")

    peers := newPeerContainer(db.geodb)
    db.peerLock.Lock()
    db.history.Network = &NetworkMessage{
        Peers: peers,
    }
    db.peerLock.Unlock()

    // newPeerEvents contains peer events, which trigger operations that
    // will be executed on the peer tree after a metering period.
    newPeerEvents := make([]*peerEvent, 0, eventLimit)
    ingress, egress := new(trafficMap), new(trafficMap)
    *ingress, *egress = make(trafficMap), make(trafficMap)

    for {
        select {
        case event := <-peerCh:
            now := time.Now()
            switch event.Type {
            case p2p.PeerConnected:
                connected := now.Add(-event.Elapsed)
                newPeerEvents = append(newPeerEvents, &peerEvent{
                    IP:        event.IP.String(),
                    ID:        event.ID.String(),
                    Connected: &connected,
                })
            case p2p.PeerDisconnected:
                ip, id := event.IP.String(), event.ID.String()
                newPeerEvents = append(newPeerEvents, &peerEvent{
                    IP:           ip,
                    ID:           id,
                    Disconnected: &now,
                })
                // The disconnect event comes with the last metered traffic count,
                // because after the disconnection the peer's meter is removed
                // from the registry. It can happen, that between two metering
                // period the same peer disconnects multiple times, and appending
                // all the samples to the traffic arrays would shift the metering,
                // so only the last metering is stored, overwriting the previous one.
                ingress.insert(ip, id, float64(event.Ingress))
                egress.insert(ip, id, float64(event.Egress))
            case p2p.PeerHandshakeFailed:
                connected := now.Add(-event.Elapsed)
                newPeerEvents = append(newPeerEvents, &peerEvent{
                    IP:           event.IP.String(),
                    Connected:    &connected,
                    Disconnected: &now,
                })
            default:
                log.Error("Unknown metered peer event type", "type", event.Type)
            }
        case <-ticker.C:
            // Collect the traffic samples from the registry.
            p2p.PeerIngressRegistry.Each(collectIngress(ingress))
            p2p.PeerEgressRegistry.Each(collectEgress(egress))

            // Protect 'peers', because it is part of the history.
            db.peerLock.Lock()

            var diff []*peerEvent
            for i := 0; i < len(newPeerEvents); i++ {
                if newPeerEvents[i].IP == "" {
                    log.Warn("Peer event without IP", "event", *newPeerEvents[i])
                    continue
                }
                diff = append(diff, newPeerEvents[i])
                // There are two main branches of peer events coming from the event
                // feed, one belongs to the known peers, one to the unknown peers.
                // If the event has node ID, it belongs to a known peer, otherwise
                // to an unknown one, which is considered as connection attempt.
                //
                // The extension can produce additional peer events, such
                // as remove, location and initial samples events.
                if newPeerEvents[i].ID == "" {
                    diff = append(diff, peers.handleAttempt(newPeerEvents[i])...)
                    continue
                }
                diff = append(diff, peers.extendKnown(newPeerEvents[i])...)
            }
            // Update the peer tree using the traffic maps.
            for ip, bundle := range peers.Bundles {
                for id, peer := range bundle.KnownPeers {
                    // Value is 0 if the traffic map doesn't have the
                    // entry corresponding to the given IP and ID.
                    curIngress, curEgress := (*ingress)[ip][id], (*egress)[ip][id]
                    deltaIngress, deltaEgress := curIngress, curEgress
                    if deltaIngress >= peer.prevIngress {
                        deltaIngress -= peer.prevIngress
                    }
                    if deltaEgress >= peer.prevEgress {
                        deltaEgress -= peer.prevEgress
                    }
                    peer.prevIngress, peer.prevEgress = curIngress, curEgress
                    i := &ChartEntry{
                        Value: deltaIngress,
                    }
                    e := &ChartEntry{
                        Value: deltaEgress,
                    }
                    peer.Ingress = append(peer.Ingress, i)
                    peer.Egress = append(peer.Egress, e)
                    if first := len(peer.Ingress) - sampleLimit; first > 0 {
                        peer.Ingress = peer.Ingress[first:]
                    }
                    if first := len(peer.Egress) - sampleLimit; first > 0 {
                        peer.Egress = peer.Egress[first:]
                    }
                    // Creating the traffic sample events.
                    diff = append(diff, &peerEvent{
                        IP:      ip,
                        ID:      id,
                        Ingress: ChartEntries{i},
                        Egress:  ChartEntries{e},
                    })
                }
            }
            db.peerLock.Unlock()

            if len(diff) > 0 {
                db.sendToAll(&Message{Network: &NetworkMessage{
                    Diff: diff,
                }})
            }
            // Clear the traffic maps, and the event array,
            // prepare them for the next metering.
            *ingress, *egress = make(trafficMap), make(trafficMap)
            newPeerEvents = newPeerEvents[:0]
        case err := <-subPeer.Err():
            log.Warn("Peer subscription error", "err", err)
            return
        case errc := <-db.quit:
            errc <- nil
            return
        }
    }
}