path: root/p2p/simulations/network.go

// Copyright 2017 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 simulations

import (
    "bytes"
    "context"
    "encoding/json"
    "fmt"
    "sync"
    "time"

    "github.com/ethereum/go-ethereum/event"
    "github.com/ethereum/go-ethereum/log"
    "github.com/ethereum/go-ethereum/p2p"
    "github.com/ethereum/go-ethereum/p2p/discover"
    "github.com/ethereum/go-ethereum/p2p/simulations/adapters"
)

var dialBanTimeout = 200 * time.Millisecond

// NetworkConfig defines configuration options for starting a Network
type NetworkConfig struct {
    ID             string `json:"id"`
    DefaultService string `json:"default_service,omitempty"`
}

// Network models a p2p simulation network which consists of a collection of
// simulated nodes and the connections which exist between them.
//
// The Network has a single NodeAdapter which is responsible for actually
// starting nodes and connecting them together.
//
// The Network emits events when nodes are started and stopped, when they are
// connected and disconnected, and also when messages are sent between nodes.
type Network struct {
    NetworkConfig

    Nodes   []*Node `json:"nodes"`
    nodeMap map[discover.NodeID]int

    Conns   []*Conn `json:"conns"`
    connMap map[string]int

    nodeAdapter adapters.NodeAdapter
    events      event.Feed
    lock        sync.RWMutex
    quitc       chan struct{}
}

// NewNetwork returns a Network which uses the given NodeAdapter and NetworkConfig
func NewNetwork(nodeAdapter adapters.NodeAdapter, conf *NetworkConfig) *Network {
    return &Network{
        NetworkConfig: *conf,
        nodeAdapter:   nodeAdapter,
        nodeMap:       make(map[discover.NodeID]int),
        connMap:       make(map[string]int),
        quitc:         make(chan struct{}),
    }
}

// Events returns the output event feed of the Network.
func (self *Network) Events() *event.Feed {
    return &self.events
}

// NewNode adds a new node to the network with a random ID
func (self *Network) NewNode() (*Node, error) {
    conf := adapters.RandomNodeConfig()
    conf.Services = []string{self.DefaultService}
    return self.NewNodeWithConfig(conf)
}

// NewNodeWithConfig adds a new node to the network with the given config,
// returning an error if a node with the same ID or name already exists
func (self *Network) NewNodeWithConfig(conf *adapters.NodeConfig) (*Node, error) {
    self.lock.Lock()
    defer self.lock.Unlock()

    // create a random ID and PrivateKey if not set
    if conf.ID == (discover.NodeID{}) {
        c := adapters.RandomNodeConfig()
        conf.ID = c.ID
        conf.PrivateKey = c.PrivateKey
    }
    id := conf.ID
    if conf.Reachable == nil {
        conf.Reachable = func(otherID discover.NodeID) bool {
            _, err := self.InitConn(conf.ID, otherID)
            return err == nil
        }
    }

    // assign a name to the node if not set
    if conf.Name == "" {
        conf.Name = fmt.Sprintf("node%02d", len(self.Nodes)+1)
    }

    // check the node doesn't already exist
    if node := self.getNode(id); node != nil {
        return nil, fmt.Errorf("node with ID %q already exists", id)
    }
    if node := self.getNodeByName(conf.Name); node != nil {
        return nil, fmt.Errorf("node with name %q already exists", conf.Name)
    }

    // if no services are configured, use the default service
    if len(conf.Services) == 0 {
        conf.Services = []string{self.DefaultService}
    }

    // use the NodeAdapter to create the node
    adapterNode, err := self.nodeAdapter.NewNode(conf)
    if err != nil {
        return nil, err
    }
    node := &Node{
        Node:   adapterNode,
        Config: conf,
    }
    log.Trace(fmt.Sprintf("node %v created", id))
    self.nodeMap[id] = len(self.Nodes)
    self.Nodes = append(self.Nodes, node)

    // emit a "control" event
    self.events.Send(ControlEvent(node))

    return node, nil
}

// Config returns the network configuration
func (self *Network) Config() *NetworkConfig {
    return &self.NetworkConfig
}

// StartAll starts all nodes in the network
func (self *Network) StartAll() error {
    for _, node := range self.Nodes {
        if node.Up {
            continue
        }
        if err := self.Start(node.ID()); err != nil {
            return err
        }
    }
    return nil
}

// StopAll stops all nodes in the network
func (self *Network) StopAll() error {
    for _, node := range self.Nodes {
        if !node.Up {
            continue
        }
        if err := self.Stop(node.ID()); err != nil {
            return err
        }
    }
    return nil
}

// Start starts the node with the given ID
func (self *Network) Start(id discover.NodeID) error {
    return self.startWithSnapshots(id, nil)
}

// startWithSnapshots starts the node with the given ID using the give
// snapshots
func (self *Network) startWithSnapshots(id discover.NodeID, snapshots map[string][]byte) error {
    node := self.GetNode(id)
    if node == nil {
        return fmt.Errorf("node %v does not exist", id)
    }
    if node.Up {
        return fmt.Errorf("node %v already up", id)
    }
    log.Trace(fmt.Sprintf("starting node %v: %v using %v", id, node.Up, self.nodeAdapter.Name()))
    if err := node.Start(snapshots); err != nil {
        log.Warn(fmt.Sprintf("start up failed: %v", err))
        return err
    }
    node.Up = true
    log.Info(fmt.Sprintf("started node %v: %v", id, node.Up))

    self.events.Send(NewEvent(node))

    // subscribe to peer events
    client, err := node.Client()
    if err != nil {
        return fmt.Errorf("error getting rpc client  for node %v: %s", id, err)
    }
    events := make(chan *p2p.PeerEvent)
    sub, err := client.Subscribe(context.Background(), "admin", events, "peerEvents")
    if err != nil {
        return fmt.Errorf("error getting peer events for node %v: %s", id, err)
    }
    go self.watchPeerEvents(id, events, sub)
    return nil
}

// watchPeerEvents reads peer events from the given channel and emits
// corresponding network events
func (self *Network) watchPeerEvents(id discover.NodeID, events chan *p2p.PeerEvent, sub event.Subscription) {
    defer func() {
        sub.Unsubscribe()

        // assume the node is now down
        self.lock.Lock()
        node := self.getNode(id)
        node.Up = false
        self.lock.Unlock()
        self.events.Send(NewEvent(node))
    }()
    for {
        select {
        case event, ok := <-events:
            if !ok {
                return
            }
            peer := event.Peer
            switch event.Type {

            case p2p.PeerEventTypeAdd:
                self.DidConnect(id, peer)

            case p2p.PeerEventTypeDrop:
                self.DidDisconnect(id, peer)

            case p2p.PeerEventTypeMsgSend:
                self.DidSend(id, peer, event.Protocol, *event.MsgCode)

            case p2p.PeerEventTypeMsgRecv:
                self.DidReceive(peer, id, event.Protocol, *event.MsgCode)

            }

        case err := <-sub.Err():
            if err != nil {
                log.Error(fmt.Sprintf("error getting peer events for node %v", id), "err", err)
            }
            return
        }
    }
}

// Stop stops the node with the given ID
func (self *Network) Stop(id discover.NodeID) error {
    node := self.GetNode(id)
    if node == nil {
        return fmt.Errorf("node %v does not exist", id)
    }
    if !node.Up {
        return fmt.Errorf("node %v already down", id)
    }
    if err := node.Stop(); err != nil {
        return err
    }
    node.Up = false
    log.Info(fmt.Sprintf("stop node %v: %v", id, node.Up))

    self.events.Send(ControlEvent(node))
    return nil
}

// Connect connects two nodes together by calling the "admin_addPeer" RPC
// method on the "one" node so that it connects to the "other" node
func (self *Network) Connect(oneID, otherID discover.NodeID) error {
    log.Debug(fmt.Sprintf("connecting %s to %s", oneID, otherID))
    conn, err := self.InitConn(oneID, otherID)
    if err != nil {
        return err
    }
    client, err := conn.one.Client()
    if err != nil {
        return err
    }
    self.events.Send(ControlEvent(conn))
    return client.Call(nil, "admin_addPeer", string(conn.other.Addr()))
}

// Disconnect disconnects two nodes by calling the "admin_removePeer" RPC
// method on the "one" node so that it disconnects from the "other" node
func (self *Network) Disconnect(oneID, otherID discover.NodeID) error {
    conn := self.GetConn(oneID, otherID)
    if conn == nil {
        return fmt.Errorf("connection between %v and %v does not exist", oneID, otherID)
    }
    if !conn.Up {
        return fmt.Errorf("%v and %v already disconnected", oneID, otherID)
    }
    client, err := conn.one.Client()
    if err != nil {
        return err
    }
    self.events.Send(ControlEvent(conn))
    return client.Call(nil, "admin_removePeer", string(conn.other.Addr()))
}

// DidConnect tracks the fact that the "one" node connected to the "other" node
func (self *Network) DidConnect(one, other discover.NodeID) error {
    conn, err := self.GetOrCreateConn(one, other)
    if err != nil {
        return fmt.Errorf("connection between %v and %v does not exist", one, other)
    }
    if conn.Up {
        return fmt.Errorf("%v and %v already connected", one, other)
    }
    conn.Up = true
    self.events.Send(NewEvent(conn))
    return nil
}

// DidDisconnect tracks the fact that the "one" node disconnected from the
// "other" node
func (self *Network) DidDisconnect(one, other discover.NodeID) error {
    conn := self.GetConn(one, other)
    if conn == nil {
        return fmt.Errorf("connection between %v and %v does not exist", one, other)
    }
    if !conn.Up {
        return fmt.Errorf("%v and %v already disconnected", one, other)
    }
    conn.Up = false
    conn.initiated = time.Now().Add(-dialBanTimeout)
    self.events.Send(NewEvent(conn))
    return nil
}

// DidSend tracks the fact that "sender" sent a message to "receiver"
func (self *Network) DidSend(sender, receiver discover.NodeID, proto string, code uint64) error {
    msg := &Msg{
        One:      sender,
        Other:    receiver,
        Protocol: proto,
        Code:     code,
        Received: false,
    }
    self.events.Send(NewEvent(msg))
    return nil
}

// DidReceive tracks the fact that "receiver" received a message from "sender"
func (self *Network) DidReceive(sender, receiver discover.NodeID, proto string, code uint64) error {
    msg := &Msg{
        One:      sender,
        Other:    receiver,
        Protocol: proto,
        Code:     code,
        Received: true,
    }
    self.events.Send(NewEvent(msg))
    return nil
}

// GetNode gets the node with the given ID, returning nil if the node does not
// exist
func (self *Network) GetNode(id discover.NodeID) *Node {
    self.lock.Lock()
    defer self.lock.Unlock()
    return self.getNode(id)
}

// GetNode gets the node with the given name, returning nil if the node does
// not exist
func (self *Network) GetNodeByName(name string) *Node {
    self.lock.Lock()
    defer self.lock.Unlock()
    return self.getNodeByName(name)
}

func (self *Network) getNode(id discover.NodeID) *Node {
    i, found := self.nodeMap[id]
    if !found {
        return nil
    }
    return self.Nodes[i]
}

func (self *Network) getNodeByName(name string) *Node {
    for _, node := range self.Nodes {
        if node.Config.Name == name {
            return node
        }
    }
    return nil
}

// GetNodes returns the existing nodes
func (self *Network) GetNodes() (nodes []*Node) {
    self.lock.Lock()
    defer self.lock.Unlock()

    nodes = append(nodes, self.Nodes...)
    return nodes
}

// GetConn returns the connection which exists between "one" and "other"
// regardless of which node initiated the connection
func (self *Network) GetConn(oneID, otherID discover.NodeID) *Conn {
    self.lock.Lock()
    defer self.lock.Unlock()
    return self.getConn(oneID, otherID)
}

// GetOrCreateConn is like GetConn but creates the connection if it doesn't
// already exist
func (self *Network) GetOrCreateConn(oneID, otherID discover.NodeID) (*Conn, error) {
    self.lock.Lock()
    defer self.lock.Unlock()
    return self.getOrCreateConn(oneID, otherID)
}

func (self *Network) getOrCreateConn(oneID, otherID discover.NodeID) (*Conn, error) {
    if conn := self.getConn(oneID, otherID); conn != nil {
        return conn, nil
    }

    one := self.getNode(oneID)
    if one == nil {
        return nil, fmt.Errorf("node %v does not exist", oneID)
    }
    other := self.getNode(otherID)
    if other == nil {
        return nil, fmt.Errorf("node %v does not exist", otherID)
    }
    conn := &Conn{
        One:   oneID,
        Other: otherID,
        one:   one,
        other: other,
    }
    label := ConnLabel(oneID, otherID)
    self.connMap[label] = len(self.Conns)
    self.Conns = append(self.Conns, conn)
    return conn, nil
}

func (self *Network) getConn(oneID, otherID discover.NodeID) *Conn {
    label := ConnLabel(oneID, otherID)
    i, found := self.connMap[label]
    if !found {
        return nil
    }
    return self.Conns[i]
}

// InitConn(one, other) retrieves the connectiton model for the connection between
// peers one and other, or creates a new one if it does not exist
// the order of nodes does not matter, i.e., Conn(i,j) == Conn(j, i)
// it checks if the connection is already up, and if the nodes are running
// NOTE:
// it also checks whether there has been recent attempt to connect the peers
// this is cheating as the simulation is used as an oracle and know about
// remote peers attempt to connect to a node which will then not initiate the connection
func (self *Network) InitConn(oneID, otherID discover.NodeID) (*Conn, error) {
    self.lock.Lock()
    defer self.lock.Unlock()
    if oneID == otherID {
        return nil, fmt.Errorf("refusing to connect to self %v", oneID)
    }
    conn, err := self.getOrCreateConn(oneID, otherID)
    if err != nil {
        return nil, err
    }
    if time.Since(conn.initiated) < dialBanTimeout {
        return nil, fmt.Errorf("connection between %v and %v recently attempted", oneID, otherID)
    }
    if conn.Up {
        return nil, fmt.Errorf("%v and %v already connected", oneID, otherID)
    }
    err = conn.nodesUp()
    if err != nil {
        return nil, fmt.Errorf("nodes not up: %v", err)
    }
    conn.initiated = time.Now()
    return conn, nil
}

// Shutdown stops all nodes in the network and closes the quit channel
func (self *Network) Shutdown() {
    for _, node := range self.Nodes {
        log.Debug(fmt.Sprintf("stopping node %s", node.ID().TerminalString()))
        if err := node.Stop(); err != nil {
            log.Warn(fmt.Sprintf("error stopping node %s", node.ID().TerminalString()), "err", err)
        }
    }
    close(self.quitc)
}

//Reset resets all network properties:
//emtpies the nodes and the connection list
func (self *Network) Reset() {
    self.lock.Lock()
    defer self.lock.Unlock()

    //re-initialize the maps
    self.connMap = make(map[string]int)
    self.nodeMap = make(map[discover.NodeID]int)

    self.Nodes = nil
    self.Conns = nil
}

// Node is a wrapper around adapters.Node which is used to track the status
// of a node in the network
type Node struct {
    adapters.Node `json:"-"`

    // Config if the config used to created the node
    Config *adapters.NodeConfig `json:"config"`

    // Up tracks whether or not the node is running
    Up bool `json:"up"`
}

// ID returns the ID of the node
func (self *Node) ID() discover.NodeID {
    return self.Config.ID
}

// String returns a log-friendly string
func (self *Node) String() string {
    return fmt.Sprintf("Node %v", self.ID().TerminalString())
}

// NodeInfo returns information about the node
func (self *Node) NodeInfo() *p2p.NodeInfo {
    // avoid a panic if the node is not started yet
    if self.Node == nil {
        return nil
    }
    info := self.Node.NodeInfo()
    info.Name = self.Config.Name
    return info
}

// MarshalJSON implements the json.Marshaler interface so that the encoded
// JSON includes the NodeInfo
func (self *Node) MarshalJSON() ([]byte, error) {
    return json.Marshal(struct {
        Info   *p2p.NodeInfo        `json:"info,omitempty"`
        Config *adapters.NodeConfig `json:"config,omitempty"`
        Up     bool                 `json:"up"`
    }{
        Info:   self.NodeInfo(),
        Config: self.Config,
        Up:     self.Up,
    })
}

// Conn represents a connection between two nodes in the network
type Conn struct {
    // One is the node which initiated the connection
    One discover.NodeID `json:"one"`

    // Other is the node which the connection was made to
    Other discover.NodeID `json:"other"`

    // Up tracks whether or not the connection is active
    Up bool `json:"up"`
    // Registers when the connection was grabbed to dial
    initiated time.Time

    one   *Node
    other *Node
}

// nodesUp returns whether both nodes are currently up
func (self *Conn) nodesUp() error {
    if !self.one.Up {
        return fmt.Errorf("one %v is not up", self.One)
    }
    if !self.other.Up {
        return fmt.Errorf("other %v is not up", self.Other)
    }
    return nil
}

// String returns a log-friendly string
func (self *Conn) String() string {
    return fmt.Sprintf("Conn %v->%v", self.One.TerminalString(), self.Other.TerminalString())
}

// Msg represents a p2p message sent between two nodes in the network
type Msg struct {
    One      discover.NodeID `json:"one"`
    Other    discover.NodeID `json:"other"`
    Protocol string          `json:"protocol"`
    Code     uint64          `json:"code"`
    Received bool            `json:"received"`
}

// String returns a log-friendly string
func (self *Msg) String() string {
    return fmt.Sprintf("Msg(%d) %v->%v", self.Code, self.One.TerminalString(), self.Other.TerminalString())
}

// ConnLabel generates a deterministic string which represents a connection
// between two nodes, used to compare if two connections are between the same
// nodes
func ConnLabel(source, target discover.NodeID) string {
    var first, second discover.NodeID
    if bytes.Compare(source.Bytes(), target.Bytes()) > 0 {
        first = target
        second = source
    } else {
        first = source
        second = target
    }
    return fmt.Sprintf("%v-%v", first, second)
}

// Snapshot represents the state of a network at a single point in time and can
// be used to restore the state of a network
type Snapshot struct {
    Nodes []NodeSnapshot `json:"nodes,omitempty"`
    Conns []Conn         `json:"conns,omitempty"`
}

// NodeSnapshot represents the state of a node in the network
type NodeSnapshot struct {
    Node Node `json:"node,omitempty"`

    // Snapshots is arbitrary data gathered from calling node.Snapshots()
    Snapshots map[string][]byte `json:"snapshots,omitempty"`
}

// Snapshot creates a network snapshot
func (self *Network) Snapshot() (*Snapshot, error) {
    self.lock.Lock()
    defer self.lock.Unlock()
    snap := &Snapshot{
        Nodes: make([]NodeSnapshot, len(self.Nodes)),
        Conns: make([]Conn, len(self.Conns)),
    }
    for i, node := range self.Nodes {
        snap.Nodes[i] = NodeSnapshot{Node: *node}
        if !node.Up {
            continue
        }
        snapshots, err := node.Snapshots()
        if err != nil {
            return nil, err
        }
        snap.Nodes[i].Snapshots = snapshots
    }
    for i, conn := range self.Conns {
        snap.Conns[i] = *conn
    }
    return snap, nil
}

// Load loads a network snapshot
func (self *Network) Load(snap *Snapshot) error {
    for _, n := range snap.Nodes {
        if _, err := self.NewNodeWithConfig(n.Node.Config); err != nil {
            return err
        }
        if !n.Node.Up {
            continue
        }
        if err := self.startWithSnapshots(n.Node.Config.ID, n.Snapshots); err != nil {
            return err
        }
    }
    for _, conn := range snap.Conns {

        if !self.GetNode(conn.One).Up || !self.GetNode(conn.Other).Up {
            //in this case, at least one of the nodes of a connection is not up,
            //so it would result in the snapshot `Load` to fail
            continue
        }
        if err := self.Connect(conn.One, conn.Other); err != nil {
            return err
        }
    }
    return nil
}

// Subscribe reads control events from a channel and executes them
func (self *Network) Subscribe(events chan *Event) {
    for {
        select {
        case event, ok := <-events:
            if !ok {
                return
            }
            if event.Control {
                self.executeControlEvent(event)
            }
        case <-self.quitc:
            return
        }
    }
}

func (self *Network) executeControlEvent(event *Event) {
    log.Trace("execute control event", "type", event.Type, "event", event)
    switch event.Type {
    case EventTypeNode:
        if err := self.executeNodeEvent(event); err != nil {
            log.Error("error executing node event", "event", event, "err", err)
        }
    case EventTypeConn:
        if err := self.executeConnEvent(event); err != nil {
            log.Error("error executing conn event", "event", event, "err", err)
        }
    case EventTypeMsg:
        log.Warn("ignoring control msg event")
    }
}

func (self *Network) executeNodeEvent(e *Event) error {
    if !e.Node.Up {
        return self.Stop(e.Node.ID())
    }

    if _, err := self.NewNodeWithConfig(e.Node.Config); err != nil {
        return err
    }
    return self.Start(e.Node.ID())
}

func (self *Network) executeConnEvent(e *Event) error {
    if e.Conn.Up {
        return self.Connect(e.Conn.One, e.Conn.Other)
    } else {
        return self.Disconnect(e.Conn.One, e.Conn.Other)
    }
}