path: root/rpc/comms/http.go

// Copyright 2015 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 comms

import (
    "encoding/json"
    "fmt"
    "net"
    "net/http"
    "strings"
    "sync"
    "time"

    "bytes"
    "io"
    "io/ioutil"

    "github.com/ethereum/go-ethereum/logger"
    "github.com/ethereum/go-ethereum/logger/glog"
    "github.com/ethereum/go-ethereum/rpc/codec"
    "github.com/ethereum/go-ethereum/rpc/shared"
    "github.com/rs/cors"
)

const (
    serverIdleTimeout  = 10 * time.Second // idle keep-alive connections
    serverReadTimeout  = 15 * time.Second // per-request read timeout
    serverWriteTimeout = 15 * time.Second // per-request read timeout
)

var (
    httpServerMu sync.Mutex
    httpServer   *stopServer
)

type HttpConfig struct {
    ListenAddress string
    ListenPort    uint
    CorsDomain    string
}

// stopServer augments http.Server with idle connection tracking.
// Idle keep-alive connections are shut down when Close is called.
type stopServer struct {
    *http.Server
    l net.Listener
    // connection tracking state
    mu       sync.Mutex
    shutdown bool // true when Stop has returned
    idle     map[net.Conn]struct{}
}

type handler struct {
    codec codec.Codec
    api   shared.EthereumApi
}

// StartHTTP starts listening for RPC requests sent via HTTP.
func StartHttp(cfg HttpConfig, codec codec.Codec, api shared.EthereumApi) error {
    httpServerMu.Lock()
    defer httpServerMu.Unlock()

    addr := fmt.Sprintf("%s:%d", cfg.ListenAddress, cfg.ListenPort)
    if httpServer != nil {
        if addr != httpServer.Addr {
            return fmt.Errorf("RPC service already running on %s ", httpServer.Addr)
        }
        return nil // RPC service already running on given host/port
    }
    // Set up the request handler, wrapping it with CORS headers if configured.
    handler := http.Handler(&handler{codec, api})
    if len(cfg.CorsDomain) > 0 {
        opts := cors.Options{
            AllowedMethods: []string{"POST"},
            AllowedOrigins: strings.Split(cfg.CorsDomain, " "),
        }
        handler = cors.New(opts).Handler(handler)
    }
    // Start the server.
    s, err := listenHTTP(addr, handler)
    if err != nil {
        glog.V(logger.Error).Infof("Can't listen on %s:%d: %v", cfg.ListenAddress, cfg.ListenPort, err)
        return err
    }
    httpServer = s
    return nil
}

func (h *handler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
    w.Header().Set("Content-Type", "application/json")

    // Limit request size to resist DoS
    if req.ContentLength > maxHttpSizeReqLength {
        err := fmt.Errorf("Request too large")
        response := shared.NewRpcErrorResponse(-1, shared.JsonRpcVersion, -32700, err)
        sendJSON(w, &response)
        return
    }

    defer req.Body.Close()
    payload, err := ioutil.ReadAll(req.Body)
    if err != nil {
        err := fmt.Errorf("Could not read request body")
        response := shared.NewRpcErrorResponse(-1, shared.JsonRpcVersion, -32700, err)
        sendJSON(w, &response)
        return
    }

    c := h.codec.New(nil)
    var rpcReq shared.Request
    if err = c.Decode(payload, &rpcReq); err == nil {
        reply, err := h.api.Execute(&rpcReq)
        res := shared.NewRpcResponse(rpcReq.Id, rpcReq.Jsonrpc, reply, err)
        sendJSON(w, &res)
        return
    }

    var reqBatch []shared.Request
    if err = c.Decode(payload, &reqBatch); err == nil {
        resBatch := make([]*interface{}, len(reqBatch))
        resCount := 0
        for i, rpcReq := range reqBatch {
            reply, err := h.api.Execute(&rpcReq)
            if rpcReq.Id != nil { // this leaves nil entries in the response batch for later removal
                resBatch[i] = shared.NewRpcResponse(rpcReq.Id, rpcReq.Jsonrpc, reply, err)
                resCount += 1
            }
        }
        // make response omitting nil entries
        sendJSON(w, resBatch[:resCount])
        return
    }

    // invalid request
    err = fmt.Errorf("Could not decode request")
    res := shared.NewRpcErrorResponse(-1, shared.JsonRpcVersion, -32600, err)
    sendJSON(w, res)
}

func sendJSON(w io.Writer, v interface{}) {
    if glog.V(logger.Detail) {
        if payload, err := json.MarshalIndent(v, "", "\t"); err == nil {
            glog.Infof("Sending payload: %s", payload)
        }
    }
    if err := json.NewEncoder(w).Encode(v); err != nil {
        glog.V(logger.Error).Infoln("Error sending JSON:", err)
    }
}

// Stop closes all active HTTP connections and shuts down the server.
func StopHttp() {
    httpServerMu.Lock()
    defer httpServerMu.Unlock()
    if httpServer != nil {
        httpServer.Close()
        httpServer = nil
    }
}

func listenHTTP(addr string, h http.Handler) (*stopServer, error) {
    l, err := net.Listen("tcp", addr)
    if err != nil {
        return nil, err
    }
    s := &stopServer{l: l, idle: make(map[net.Conn]struct{})}
    s.Server = &http.Server{
        Addr:         addr,
        Handler:      h,
        ReadTimeout:  serverReadTimeout,
        WriteTimeout: serverWriteTimeout,
        ConnState:    s.connState,
    }
    go s.Serve(l)
    return s, nil
}

func (s *stopServer) connState(c net.Conn, state http.ConnState) {
    s.mu.Lock()
    defer s.mu.Unlock()
    // Close c immediately if we're past shutdown.
    if s.shutdown {
        if state != http.StateClosed {
            c.Close()
        }
        return
    }
    if state == http.StateIdle {
        s.idle[c] = struct{}{}
    } else {
        delete(s.idle, c)
    }
}

func (s *stopServer) Close() {
    s.mu.Lock()
    defer s.mu.Unlock()
    // Shut down the acceptor. No new connections can be created.
    s.l.Close()
    // Drop all idle connections. Non-idle connections will be
    // closed by connState as soon as they become idle.
    s.shutdown = true
    for c := range s.idle {
        glog.V(logger.Detail).Infof("closing idle connection %v", c.RemoteAddr())
        c.Close()
        delete(s.idle, c)
    }
}

type httpClient struct {
    address string
    port    uint
    codec   codec.ApiCoder
    lastRes interface{}
    lastErr error
}

// Create a new in process client
func NewHttpClient(cfg HttpConfig, c codec.Codec) *httpClient {
    return &httpClient{
        address: cfg.ListenAddress,
        port:    cfg.ListenPort,
        codec:   c.New(nil),
    }
}

func (self *httpClient) Close() {
    // do nothing
}

func (self *httpClient) Send(req interface{}) error {
    var body []byte
    var err error

    self.lastRes = nil
    self.lastErr = nil

    if body, err = self.codec.Encode(req); err != nil {
        return err
    }

    httpReq, err := http.NewRequest("POST", fmt.Sprintf("%s:%d", self.address, self.port), bytes.NewBuffer(body))
    if err != nil {
        return err
    }
    httpReq.Header.Set("Content-Type", "application/json")

    client := http.Client{}
    resp, err := client.Do(httpReq)
    if err != nil {
        return err
    }

    defer resp.Body.Close()

    if resp.Status == "200 OK" {
        reply, _ := ioutil.ReadAll(resp.Body)
        var rpcSuccessResponse shared.SuccessResponse
        if err = self.codec.Decode(reply, &rpcSuccessResponse); err == nil {
            self.lastRes = &rpcSuccessResponse
            self.lastErr = err
            return nil
        } else {
            var rpcErrorResponse shared.ErrorResponse
            if err = self.codec.Decode(reply, &rpcErrorResponse); err == nil {
                self.lastRes = &rpcErrorResponse
                self.lastErr = err
                return nil
            } else {
                return err
            }
        }
    }

    return fmt.Errorf("Not implemented")
}

func (self *httpClient) Recv() (interface{}, error) {
    return self.lastRes, self.lastErr
}

func (self *httpClient) SupportedModules() (map[string]string, error) {
    var body []byte
    var err error

    payload := shared.Request{
        Id:      1,
        Jsonrpc: "2.0",
        Method:  "modules",
    }

    if body, err = self.codec.Encode(payload); err != nil {
        return nil, err
    }

    req, err := http.NewRequest("POST", fmt.Sprintf("%s:%d", self.address, self.port), bytes.NewBuffer(body))
    if err != nil {
        return nil, err
    }
    req.Header.Set("Content-Type", "application/json")

    client := http.Client{}
    resp, err := client.Do(req)
    if err != nil {
        return nil, err
    }

    defer resp.Body.Close()

    if resp.Status == "200 OK" {
        reply, _ := ioutil.ReadAll(resp.Body)
        var rpcRes shared.SuccessResponse
        if err = self.codec.Decode(reply, &rpcRes); err != nil {
            return nil, err
        }

        result := make(map[string]string)
        if modules, ok := rpcRes.Result.(map[string]interface{}); ok {
            for a, v := range modules {
                result[a] = fmt.Sprintf("%s", v)
            }
            return result, nil
        }
        err = fmt.Errorf("Unable to parse module response - %v", rpcRes.Result)
    } else {
        fmt.Printf("resp.Status = %s\n", resp.Status)
        fmt.Printf("err = %v\n", err)
    }

    return nil, err
}