path: root/p2p/simulations/adapters/inproc.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 adapters

import (
    "errors"
    "fmt"
    "math"
    "net"
    "sync"

    "github.com/ethereum/go-ethereum/event"
    "github.com/ethereum/go-ethereum/log"
    "github.com/ethereum/go-ethereum/node"
    "github.com/ethereum/go-ethereum/p2p"
    "github.com/ethereum/go-ethereum/p2p/discover"
    "github.com/ethereum/go-ethereum/rpc"
)

// SimAdapter is a NodeAdapter which creates in-memory simulation nodes and
// connects them using in-memory net.Pipe connections
type SimAdapter struct {
    mtx      sync.RWMutex
    nodes    map[discover.NodeID]*SimNode
    services map[string]ServiceFunc
}

// NewSimAdapter creates a SimAdapter which is capable of running in-memory
// simulation nodes running any of the given services (the services to run on a
// particular node are passed to the NewNode function in the NodeConfig)
func NewSimAdapter(services map[string]ServiceFunc) *SimAdapter {
    return &SimAdapter{
        nodes:    make(map[discover.NodeID]*SimNode),
        services: services,
    }
}

// Name returns the name of the adapter for logging purposes
func (s *SimAdapter) Name() string {
    return "sim-adapter"
}

// NewNode returns a new SimNode using the given config
func (s *SimAdapter) NewNode(config *NodeConfig) (Node, error) {
    s.mtx.Lock()
    defer s.mtx.Unlock()

    // check a node with the ID doesn't already exist
    id := config.ID
    if _, exists := s.nodes[id]; exists {
        return nil, fmt.Errorf("node already exists: %s", id)
    }

    // check the services are valid
    if len(config.Services) == 0 {
        return nil, errors.New("node must have at least one service")
    }
    for _, service := range config.Services {
        if _, exists := s.services[service]; !exists {
            return nil, fmt.Errorf("unknown node service %q", service)
        }
    }

    n, err := node.New(&node.Config{
        P2P: p2p.Config{
            PrivateKey:      config.PrivateKey,
            MaxPeers:        math.MaxInt32,
            NoDiscovery:     true,
            Dialer:          s,
            EnableMsgEvents: true,
        },
        NoUSB:  true,
        Logger: log.New("node.id", id.String()),
    })
    if err != nil {
        return nil, err
    }

    simNode := &SimNode{
        ID:      id,
        config:  config,
        node:    n,
        adapter: s,
        running: make(map[string]node.Service),
    }
    s.nodes[id] = simNode
    return simNode, nil
}

// Dial implements the p2p.NodeDialer interface by connecting to the node using
// an in-memory net.Pipe connection
func (s *SimAdapter) Dial(dest *discover.Node) (conn net.Conn, err error) {
    node, ok := s.GetNode(dest.ID)
    if !ok {
        return nil, fmt.Errorf("unknown node: %s", dest.ID)
    }
    srv := node.Server()
    if srv == nil {
        return nil, fmt.Errorf("node not running: %s", dest.ID)
    }
    pipe1, pipe2 := net.Pipe()
    go srv.SetupConn(pipe1, 0, nil)
    return pipe2, nil
}

// DialRPC implements the RPCDialer interface by creating an in-memory RPC
// client of the given node
func (s *SimAdapter) DialRPC(id discover.NodeID) (*rpc.Client, error) {
    node, ok := s.GetNode(id)
    if !ok {
        return nil, fmt.Errorf("unknown node: %s", id)
    }
    handler, err := node.node.RPCHandler()
    if err != nil {
        return nil, err
    }
    return rpc.DialInProc(handler), nil
}

// GetNode returns the node with the given ID if it exists
func (s *SimAdapter) GetNode(id discover.NodeID) (*SimNode, bool) {
    s.mtx.RLock()
    defer s.mtx.RUnlock()
    node, ok := s.nodes[id]
    return node, ok
}

// SimNode is an in-memory simulation node which connects to other nodes using
// an in-memory net.Pipe connection (see SimAdapter.Dial), running devp2p
// protocols directly over that pipe
type SimNode struct {
    lock         sync.RWMutex
    ID           discover.NodeID
    config       *NodeConfig
    adapter      *SimAdapter
    node         *node.Node
    running      map[string]node.Service
    client       *rpc.Client
    registerOnce sync.Once
}

// Addr returns the node's discovery address
func (sn *SimNode) Addr() []byte {
    return []byte(sn.Node().String())
}

// Node returns a discover.Node representing the SimNode
func (sn *SimNode) Node() *discover.Node {
    return discover.NewNode(sn.ID, net.IP{127, 0, 0, 1}, 30303, 30303)
}

// Client returns an rpc.Client which can be used to communicate with the
// underlying services (it is set once the node has started)
func (sn *SimNode) Client() (*rpc.Client, error) {
    sn.lock.RLock()
    defer sn.lock.RUnlock()
    if sn.client == nil {
        return nil, errors.New("node not started")
    }
    return sn.client, nil
}

// ServeRPC serves RPC requests over the given connection by creating an
// in-memory client to the node's RPC server
func (sn *SimNode) ServeRPC(conn net.Conn) error {
    handler, err := sn.node.RPCHandler()
    if err != nil {
        return err
    }
    handler.ServeCodec(rpc.NewJSONCodec(conn), rpc.OptionMethodInvocation|rpc.OptionSubscriptions)
    return nil
}

// Snapshots creates snapshots of the services by calling the
// simulation_snapshot RPC method
func (sn *SimNode) Snapshots() (map[string][]byte, error) {
    sn.lock.RLock()
    services := make(map[string]node.Service, len(sn.running))
    for name, service := range sn.running {
        services[name] = service
    }
    sn.lock.RUnlock()
    if len(services) == 0 {
        return nil, errors.New("no running services")
    }
    snapshots := make(map[string][]byte)
    for name, service := range services {
        if s, ok := service.(interface {
            Snapshot() ([]byte, error)
        }); ok {
            snap, err := s.Snapshot()
            if err != nil {
                return nil, err
            }
            snapshots[name] = snap
        }
    }
    return snapshots, nil
}

// Start registers the services and starts the underlying devp2p node
func (sn *SimNode) Start(snapshots map[string][]byte) error {
    newService := func(name string) func(ctx *node.ServiceContext) (node.Service, error) {
        return func(nodeCtx *node.ServiceContext) (node.Service, error) {
            ctx := &ServiceContext{
                RPCDialer:   sn.adapter,
                NodeContext: nodeCtx,
                Config:      sn.config,
            }
            if snapshots != nil {
                ctx.Snapshot = snapshots[name]
            }
            serviceFunc := sn.adapter.services[name]
            service, err := serviceFunc(ctx)
            if err != nil {
                return nil, err
            }
            sn.running[name] = service
            return service, nil
        }
    }

    // ensure we only register the services once in the case of the node
    // being stopped and then started again
    var regErr error
    sn.registerOnce.Do(func() {
        for _, name := range sn.config.Services {
            if err := sn.node.Register(newService(name)); err != nil {
                regErr = err
                return
            }
        }
    })
    if regErr != nil {
        return regErr
    }

    if err := sn.node.Start(); err != nil {
        return err
    }

    // create an in-process RPC client
    handler, err := sn.node.RPCHandler()
    if err != nil {
        return err
    }

    sn.lock.Lock()
    sn.client = rpc.DialInProc(handler)
    sn.lock.Unlock()

    return nil
}

// Stop closes the RPC client and stops the underlying devp2p node
func (sn *SimNode) Stop() error {
    sn.lock.Lock()
    if sn.client != nil {
        sn.client.Close()
        sn.client = nil
    }
    sn.lock.Unlock()
    return sn.node.Stop()
}

// Services returns a copy of the underlying services
func (sn *SimNode) Services() []node.Service {
    sn.lock.RLock()
    defer sn.lock.RUnlock()
    services := make([]node.Service, 0, len(sn.running))
    for _, service := range sn.running {
        services = append(services, service)
    }
    return services
}

// Server returns the underlying p2p.Server
func (sn *SimNode) Server() *p2p.Server {
    return sn.node.Server()
}

// SubscribeEvents subscribes the given channel to peer events from the
// underlying p2p.Server
func (sn *SimNode) SubscribeEvents(ch chan *p2p.PeerEvent) event.Subscription {
    srv := sn.Server()
    if srv == nil {
        panic("node not running")
    }
    return srv.SubscribeEvents(ch)
}

// NodeInfo returns information about the node
func (sn *SimNode) NodeInfo() *p2p.NodeInfo {
    server := sn.Server()
    if server == nil {
        return &p2p.NodeInfo{
            ID:    sn.ID.String(),
            Enode: sn.Node().String(),
        }
    }
    return server.NodeInfo()
}