path: root/p2p/simulations/http.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 (
    "bufio"
    "bytes"
    "context"
    "encoding/json"
    "fmt"
    "io"
    "io/ioutil"
    "net/http"
    "strconv"
    "strings"
    "sync"

    "github.com/ethereum/go-ethereum/event"
    "github.com/ethereum/go-ethereum/p2p"
    "github.com/ethereum/go-ethereum/p2p/discover"
    "github.com/ethereum/go-ethereum/p2p/simulations/adapters"
    "github.com/ethereum/go-ethereum/rpc"
    "github.com/julienschmidt/httprouter"
    "golang.org/x/net/websocket"
)

// DefaultClient is the default simulation API client which expects the API
// to be running at http://localhost:8888
var DefaultClient = NewClient("http://localhost:8888")

// Client is a client for the simulation HTTP API which supports creating
// and managing simulation networks
type Client struct {
    URL string

    client *http.Client
}

// NewClient returns a new simulation API client
func NewClient(url string) *Client {
    return &Client{
        URL:    url,
        client: http.DefaultClient,
    }
}

// GetNetwork returns details of the network
func (c *Client) GetNetwork() (*Network, error) {
    network := &Network{}
    return network, c.Get("/", network)
}

// StartNetwork starts all existing nodes in the simulation network
func (c *Client) StartNetwork() error {
    return c.Post("/start", nil, nil)
}

// StopNetwork stops all existing nodes in a simulation network
func (c *Client) StopNetwork() error {
    return c.Post("/stop", nil, nil)
}

// CreateSnapshot creates a network snapshot
func (c *Client) CreateSnapshot() (*Snapshot, error) {
    snap := &Snapshot{}
    return snap, c.Get("/snapshot", snap)
}

// LoadSnapshot loads a snapshot into the network
func (c *Client) LoadSnapshot(snap *Snapshot) error {
    return c.Post("/snapshot", snap, nil)
}

// SubscribeOpts is a collection of options to use when subscribing to network
// events
type SubscribeOpts struct {
    // Current instructs the server to send events for existing nodes and
    // connections first
    Current bool

    // Filter instructs the server to only send a subset of message events
    Filter string
}

// SubscribeNetwork subscribes to network events which are sent from the server
// as a server-sent-events stream, optionally receiving events for existing
// nodes and connections and filtering message events
func (c *Client) SubscribeNetwork(events chan *Event, opts SubscribeOpts) (event.Subscription, error) {
    url := fmt.Sprintf("%s/events?current=%t&filter=%s", c.URL, opts.Current, opts.Filter)
    req, err := http.NewRequest("GET", url, nil)
    if err != nil {
        return nil, err
    }
    req.Header.Set("Accept", "text/event-stream")
    res, err := c.client.Do(req)
    if err != nil {
        return nil, err
    }
    if res.StatusCode != http.StatusOK {
        response, _ := ioutil.ReadAll(res.Body)
        res.Body.Close()
        return nil, fmt.Errorf("unexpected HTTP status: %s: %s", res.Status, response)
    }

    // define a producer function to pass to event.Subscription
    // which reads server-sent events from res.Body and sends
    // them to the events channel
    producer := func(stop <-chan struct{}) error {
        defer res.Body.Close()

        // read lines from res.Body in a goroutine so that we are
        // always reading from the stop channel
        lines := make(chan string)
        errC := make(chan error, 1)
        go func() {
            s := bufio.NewScanner(res.Body)
            for s.Scan() {
                select {
                case lines <- s.Text():
                case <-stop:
                    return
                }
            }
            errC <- s.Err()
        }()

        // detect any lines which start with "data:", decode the data
        // into an event and send it to the events channel
        for {
            select {
            case line := <-lines:
                if !strings.HasPrefix(line, "data:") {
                    continue
                }
                data := strings.TrimSpace(strings.TrimPrefix(line, "data:"))
                event := &Event{}
                if err := json.Unmarshal([]byte(data), event); err != nil {
                    return fmt.Errorf("error decoding SSE event: %s", err)
                }
                select {
                case events <- event:
                case <-stop:
                    return nil
                }
            case err := <-errC:
                return err
            case <-stop:
                return nil
            }
        }
    }

    return event.NewSubscription(producer), nil
}

// GetNodes returns all nodes which exist in the network
func (c *Client) GetNodes() ([]*p2p.NodeInfo, error) {
    var nodes []*p2p.NodeInfo
    return nodes, c.Get("/nodes", &nodes)
}

// CreateNode creates a node in the network using the given configuration
func (c *Client) CreateNode(config *adapters.NodeConfig) (*p2p.NodeInfo, error) {
    node := &p2p.NodeInfo{}
    return node, c.Post("/nodes", config, node)
}

// GetNode returns details of a node
func (c *Client) GetNode(nodeID string) (*p2p.NodeInfo, error) {
    node := &p2p.NodeInfo{}
    return node, c.Get(fmt.Sprintf("/nodes/%s", nodeID), node)
}

// StartNode starts a node
func (c *Client) StartNode(nodeID string) error {
    return c.Post(fmt.Sprintf("/nodes/%s/start", nodeID), nil, nil)
}

// StopNode stops a node
func (c *Client) StopNode(nodeID string) error {
    return c.Post(fmt.Sprintf("/nodes/%s/stop", nodeID), nil, nil)
}

// ConnectNode connects a node to a peer node
func (c *Client) ConnectNode(nodeID, peerID string) error {
    return c.Post(fmt.Sprintf("/nodes/%s/conn/%s", nodeID, peerID), nil, nil)
}

// DisconnectNode disconnects a node from a peer node
func (c *Client) DisconnectNode(nodeID, peerID string) error {
    return c.Delete(fmt.Sprintf("/nodes/%s/conn/%s", nodeID, peerID))
}

// RPCClient returns an RPC client connected to a node
func (c *Client) RPCClient(ctx context.Context, nodeID string) (*rpc.Client, error) {
    baseURL := strings.Replace(c.URL, "http", "ws", 1)
    return rpc.DialWebsocket(ctx, fmt.Sprintf("%s/nodes/%s/rpc", baseURL, nodeID), "")
}

// Get performs a HTTP GET request decoding the resulting JSON response
// into "out"
func (c *Client) Get(path string, out interface{}) error {
    return c.Send("GET", path, nil, out)
}

// Post performs a HTTP POST request sending "in" as the JSON body and
// decoding the resulting JSON response into "out"
func (c *Client) Post(path string, in, out interface{}) error {
    return c.Send("POST", path, in, out)
}

// Delete performs a HTTP DELETE request
func (c *Client) Delete(path string) error {
    return c.Send("DELETE", path, nil, nil)
}

// Send performs a HTTP request, sending "in" as the JSON request body and
// decoding the JSON response into "out"
func (c *Client) Send(method, path string, in, out interface{}) error {
    var body []byte
    if in != nil {
        var err error
        body, err = json.Marshal(in)
        if err != nil {
            return err
        }
    }
    req, err := http.NewRequest(method, c.URL+path, bytes.NewReader(body))
    if err != nil {
        return err
    }
    req.Header.Set("Content-Type", "application/json")
    req.Header.Set("Accept", "application/json")
    res, err := c.client.Do(req)
    if err != nil {
        return err
    }
    defer res.Body.Close()
    if res.StatusCode != http.StatusOK && res.StatusCode != http.StatusCreated {
        response, _ := ioutil.ReadAll(res.Body)
        return fmt.Errorf("unexpected HTTP status: %s: %s", res.Status, response)
    }
    if out != nil {
        if err := json.NewDecoder(res.Body).Decode(out); err != nil {
            return err
        }
    }
    return nil
}

// Server is an HTTP server providing an API to manage a simulation network
type Server struct {
    router     *httprouter.Router
    network    *Network
    mockerStop chan struct{} // when set, stops the current mocker
    mockerMtx  sync.Mutex    // synchronises access to the mockerStop field
}

// NewServer returns a new simulation API server
func NewServer(network *Network) *Server {
    s := &Server{
        router:  httprouter.New(),
        network: network,
    }

    s.OPTIONS("/", s.Options)
    s.GET("/", s.GetNetwork)
    s.POST("/start", s.StartNetwork)
    s.POST("/stop", s.StopNetwork)
    s.POST("/mocker/start", s.StartMocker)
    s.POST("/mocker/stop", s.StopMocker)
    s.GET("/mocker", s.GetMockers)
    s.POST("/reset", s.ResetNetwork)
    s.GET("/events", s.StreamNetworkEvents)
    s.GET("/snapshot", s.CreateSnapshot)
    s.POST("/snapshot", s.LoadSnapshot)
    s.POST("/nodes", s.CreateNode)
    s.GET("/nodes", s.GetNodes)
    s.GET("/nodes/:nodeid", s.GetNode)
    s.POST("/nodes/:nodeid/start", s.StartNode)
    s.POST("/nodes/:nodeid/stop", s.StopNode)
    s.POST("/nodes/:nodeid/conn/:peerid", s.ConnectNode)
    s.DELETE("/nodes/:nodeid/conn/:peerid", s.DisconnectNode)
    s.GET("/nodes/:nodeid/rpc", s.NodeRPC)

    return s
}

// GetNetwork returns details of the network
func (s *Server) GetNetwork(w http.ResponseWriter, req *http.Request) {
    s.JSON(w, http.StatusOK, s.network)
}

// StartNetwork starts all nodes in the network
func (s *Server) StartNetwork(w http.ResponseWriter, req *http.Request) {
    if err := s.network.StartAll(); err != nil {
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }

    w.WriteHeader(http.StatusOK)
}

// StopNetwork stops all nodes in the network
func (s *Server) StopNetwork(w http.ResponseWriter, req *http.Request) {
    if err := s.network.StopAll(); err != nil {
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }

    w.WriteHeader(http.StatusOK)
}

// StartMocker starts the mocker node simulation
func (s *Server) StartMocker(w http.ResponseWriter, req *http.Request) {
    s.mockerMtx.Lock()
    defer s.mockerMtx.Unlock()
    if s.mockerStop != nil {
        http.Error(w, "mocker already running", http.StatusInternalServerError)
        return
    }
    mockerType := req.FormValue("mocker-type")
    mockerFn := LookupMocker(mockerType)
    if mockerFn == nil {
        http.Error(w, fmt.Sprintf("unknown mocker type %q", mockerType), http.StatusBadRequest)
        return
    }
    nodeCount, err := strconv.Atoi(req.FormValue("node-count"))
    if err != nil {
        http.Error(w, "invalid node-count provided", http.StatusBadRequest)
        return
    }
    s.mockerStop = make(chan struct{})
    go mockerFn(s.network, s.mockerStop, nodeCount)

    w.WriteHeader(http.StatusOK)
}

// StopMocker stops the mocker node simulation
func (s *Server) StopMocker(w http.ResponseWriter, req *http.Request) {
    s.mockerMtx.Lock()
    defer s.mockerMtx.Unlock()
    if s.mockerStop == nil {
        http.Error(w, "stop channel not initialized", http.StatusInternalServerError)
        return
    }
    close(s.mockerStop)
    s.mockerStop = nil

    w.WriteHeader(http.StatusOK)
}

// GetMockerList returns a list of available mockers
func (s *Server) GetMockers(w http.ResponseWriter, req *http.Request) {

    list := GetMockerList()
    s.JSON(w, http.StatusOK, list)
}

// ResetNetwork resets all properties of a network to its initial (empty) state
func (s *Server) ResetNetwork(w http.ResponseWriter, req *http.Request) {
    s.network.Reset()

    w.WriteHeader(http.StatusOK)
}

// StreamNetworkEvents streams network events as a server-sent-events stream
func (s *Server) StreamNetworkEvents(w http.ResponseWriter, req *http.Request) {
    events := make(chan *Event)
    sub := s.network.events.Subscribe(events)
    defer sub.Unsubscribe()

    // stop the stream if the client goes away
    var clientGone <-chan bool
    if cn, ok := w.(http.CloseNotifier); ok {
        clientGone = cn.CloseNotify()
    }

    // write writes the given event and data to the stream like:
    //
    // event: <event>
    // data: <data>
    //
    write := func(event, data string) {
        fmt.Fprintf(w, "event: %s\n", event)
        fmt.Fprintf(w, "data: %s\n\n", data)
        if fw, ok := w.(http.Flusher); ok {
            fw.Flush()
        }
    }
    writeEvent := func(event *Event) error {
        data, err := json.Marshal(event)
        if err != nil {
            return err
        }
        write("network", string(data))
        return nil
    }
    writeErr := func(err error) {
        write("error", err.Error())
    }

    // check if filtering has been requested
    var filters MsgFilters
    if filterParam := req.URL.Query().Get("filter"); filterParam != "" {
        var err error
        filters, err = NewMsgFilters(filterParam)
        if err != nil {
            http.Error(w, err.Error(), http.StatusBadRequest)
            return
        }
    }

    w.Header().Set("Content-Type", "text/event-stream; charset=utf-8")
    w.WriteHeader(http.StatusOK)
    fmt.Fprintf(w, "\n\n")
    if fw, ok := w.(http.Flusher); ok {
        fw.Flush()
    }

    // optionally send the existing nodes and connections
    if req.URL.Query().Get("current") == "true" {
        snap, err := s.network.Snapshot()
        if err != nil {
            writeErr(err)
            return
        }
        for _, node := range snap.Nodes {
            event := NewEvent(&node.Node)
            if err := writeEvent(event); err != nil {
                writeErr(err)
                return
            }
        }
        for _, conn := range snap.Conns {
            event := NewEvent(&conn)
            if err := writeEvent(event); err != nil {
                writeErr(err)
                return
            }
        }
    }

    for {
        select {
        case event := <-events:
            // only send message events which match the filters
            if event.Msg != nil && !filters.Match(event.Msg) {
                continue
            }
            if err := writeEvent(event); err != nil {
                writeErr(err)
                return
            }
        case <-clientGone:
            return
        }
    }
}

// NewMsgFilters constructs a collection of message filters from a URL query
// parameter.
//
// The parameter is expected to be a dash-separated list of individual filters,
// each having the format '<proto>:<codes>', where <proto> is the name of a
// protocol and <codes> is a comma-separated list of message codes.
//
// A message code of '*' or '-1' is considered a wildcard and matches any code.
func NewMsgFilters(filterParam string) (MsgFilters, error) {
    filters := make(MsgFilters)
    for _, filter := range strings.Split(filterParam, "-") {
        protoCodes := strings.SplitN(filter, ":", 2)
        if len(protoCodes) != 2 || protoCodes[0] == "" || protoCodes[1] == "" {
            return nil, fmt.Errorf("invalid message filter: %s", filter)
        }
        proto := protoCodes[0]
        for _, code := range strings.Split(protoCodes[1], ",") {
            if code == "*" || code == "-1" {
                filters[MsgFilter{Proto: proto, Code: -1}] = struct{}{}
                continue
            }
            n, err := strconv.ParseUint(code, 10, 64)
            if err != nil {
                return nil, fmt.Errorf("invalid message code: %s", code)
            }
            filters[MsgFilter{Proto: proto, Code: int64(n)}] = struct{}{}
        }
    }
    return filters, nil
}

// MsgFilters is a collection of filters which are used to filter message
// events
type MsgFilters map[MsgFilter]struct{}

// Match checks if the given message matches any of the filters
func (m MsgFilters) Match(msg *Msg) bool {
    // check if there is a wildcard filter for the message's protocol
    if _, ok := m[MsgFilter{Proto: msg.Protocol, Code: -1}]; ok {
        return true
    }

    // check if there is a filter for the message's protocol and code
    if _, ok := m[MsgFilter{Proto: msg.Protocol, Code: int64(msg.Code)}]; ok {
        return true
    }

    return false
}

// MsgFilter is used to filter message events based on protocol and message
// code
type MsgFilter struct {
    // Proto is matched against a message's protocol
    Proto string

    // Code is matched against a message's code, with -1 matching all codes
    Code int64
}

// CreateSnapshot creates a network snapshot
func (s *Server) CreateSnapshot(w http.ResponseWriter, req *http.Request) {
    snap, err := s.network.Snapshot()
    if err != nil {
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }

    s.JSON(w, http.StatusOK, snap)
}

// LoadSnapshot loads a snapshot into the network
func (s *Server) LoadSnapshot(w http.ResponseWriter, req *http.Request) {
    snap := &Snapshot{}
    if err := json.NewDecoder(req.Body).Decode(snap); err != nil {
        http.Error(w, err.Error(), http.StatusBadRequest)
        return
    }

    if err := s.network.Load(snap); err != nil {
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }

    s.JSON(w, http.StatusOK, s.network)
}

// CreateNode creates a node in the network using the given configuration
func (s *Server) CreateNode(w http.ResponseWriter, req *http.Request) {
    config := adapters.RandomNodeConfig()
    err := json.NewDecoder(req.Body).Decode(config)
    if err != nil && err != io.EOF {
        http.Error(w, err.Error(), http.StatusBadRequest)
        return
    }

    node, err := s.network.NewNodeWithConfig(config)
    if err != nil {
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }

    s.JSON(w, http.StatusCreated, node.NodeInfo())
}

// GetNodes returns all nodes which exist in the network
func (s *Server) GetNodes(w http.ResponseWriter, req *http.Request) {
    nodes := s.network.GetNodes()

    infos := make([]*p2p.NodeInfo, len(nodes))
    for i, node := range nodes {
        infos[i] = node.NodeInfo()
    }

    s.JSON(w, http.StatusOK, infos)
}

// GetNode returns details of a node
func (s *Server) GetNode(w http.ResponseWriter, req *http.Request) {
    node := req.Context().Value("node").(*Node)

    s.JSON(w, http.StatusOK, node.NodeInfo())
}

// StartNode starts a node
func (s *Server) StartNode(w http.ResponseWriter, req *http.Request) {
    node := req.Context().Value("node").(*Node)

    if err := s.network.Start(node.ID()); err != nil {
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }

    s.JSON(w, http.StatusOK, node.NodeInfo())
}

// StopNode stops a node
func (s *Server) StopNode(w http.ResponseWriter, req *http.Request) {
    node := req.Context().Value("node").(*Node)

    if err := s.network.Stop(node.ID()); err != nil {
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }

    s.JSON(w, http.StatusOK, node.NodeInfo())
}

// ConnectNode connects a node to a peer node
func (s *Server) ConnectNode(w http.ResponseWriter, req *http.Request) {
    node := req.Context().Value("node").(*Node)
    peer := req.Context().Value("peer").(*Node)

    if err := s.network.Connect(node.ID(), peer.ID()); err != nil {
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }

    s.JSON(w, http.StatusOK, node.NodeInfo())
}

// DisconnectNode disconnects a node from a peer node
func (s *Server) DisconnectNode(w http.ResponseWriter, req *http.Request) {
    node := req.Context().Value("node").(*Node)
    peer := req.Context().Value("peer").(*Node)

    if err := s.network.Disconnect(node.ID(), peer.ID()); err != nil {
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }

    s.JSON(w, http.StatusOK, node.NodeInfo())
}

// Options responds to the OPTIONS HTTP method by returning a 200 OK response
// with the "Access-Control-Allow-Headers" header set to "Content-Type"
func (s *Server) Options(w http.ResponseWriter, req *http.Request) {
    w.Header().Set("Access-Control-Allow-Headers", "Content-Type")
    w.WriteHeader(http.StatusOK)
}

// NodeRPC forwards RPC requests to a node in the network via a WebSocket
// connection
func (s *Server) NodeRPC(w http.ResponseWriter, req *http.Request) {
    node := req.Context().Value("node").(*Node)

    handler := func(conn *websocket.Conn) {
        node.ServeRPC(conn)
    }

    websocket.Server{Handler: handler}.ServeHTTP(w, req)
}

// ServeHTTP implements the http.Handler interface by delegating to the
// underlying httprouter.Router
func (s *Server) ServeHTTP(w http.ResponseWriter, req *http.Request) {
    s.router.ServeHTTP(w, req)
}

// GET registers a handler for GET requests to a particular path
func (s *Server) GET(path string, handle http.HandlerFunc) {
    s.router.GET(path, s.wrapHandler(handle))
}

// POST registers a handler for POST requests to a particular path
func (s *Server) POST(path string, handle http.HandlerFunc) {
    s.router.POST(path, s.wrapHandler(handle))
}

// DELETE registers a handler for DELETE requests to a particular path
func (s *Server) DELETE(path string, handle http.HandlerFunc) {
    s.router.DELETE(path, s.wrapHandler(handle))
}

// OPTIONS registers a handler for OPTIONS requests to a particular path
func (s *Server) OPTIONS(path string, handle http.HandlerFunc) {
    s.router.OPTIONS("/*path", s.wrapHandler(handle))
}

// JSON sends "data" as a JSON HTTP response
func (s *Server) JSON(w http.ResponseWriter, status int, data interface{}) {
    w.Header().Set("Content-Type", "application/json")
    w.WriteHeader(status)
    json.NewEncoder(w).Encode(data)
}

// wrapHandler returns a httprouter.Handle which wraps a http.HandlerFunc by
// populating request.Context with any objects from the URL params
func (s *Server) wrapHandler(handler http.HandlerFunc) httprouter.Handle {
    return func(w http.ResponseWriter, req *http.Request, params httprouter.Params) {
        w.Header().Set("Access-Control-Allow-Origin", "*")
        w.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS")

        ctx := context.Background()

        if id := params.ByName("nodeid"); id != "" {
            var node *Node
            if nodeID, err := discover.HexID(id); err == nil {
                node = s.network.GetNode(nodeID)
            } else {
                node = s.network.GetNodeByName(id)
            }
            if node == nil {
                http.NotFound(w, req)
                return
            }
            ctx = context.WithValue(ctx, "node", node)
        }

        if id := params.ByName("peerid"); id != "" {
            var peer *Node
            if peerID, err := discover.HexID(id); err == nil {
                peer = s.network.GetNode(peerID)
            } else {
                peer = s.network.GetNodeByName(id)
            }
            if peer == nil {
                http.NotFound(w, req)
                return
            }
            ctx = context.WithValue(ctx, "peer", peer)
        }

        handler(w, req.WithContext(ctx))
    }
}