// 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 rpc
import (
"context"
"encoding/base64"
"fmt"
"net/http"
"net/url"
"os"
"strings"
"sync"
"time"
mapset "github.com/deckarep/golang-set"
"github.com/ethereum/go-ethereum/log"
"github.com/gorilla/websocket"
)
const (
wsReadBuffer = 1024
wsWriteBuffer = 1024
wsPingInterval = 60 * time.Second
wsPingWriteTimeout = 5 * time.Second
)
var wsBufferPool = new(sync.Pool)
// WebsocketHandler returns a handler that serves JSON-RPC to WebSocket connections.
//
// allowedOrigins should be a comma-separated list of allowed origin URLs.
// To allow connections with any origin, pass "*".
func (s *Server) WebsocketHandler(allowedOrigins []string) http.Handler {
var upgrader = websocket.Upgrader{
ReadBufferSize: wsReadBuffer,
WriteBufferSize: wsWriteBuffer,
WriteBufferPool: wsBufferPool,
CheckOrigin: wsHandshakeValidator(allowedOrigins),
}
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
conn, err := upgrader.Upgrade(w, r, nil)
if err != nil {
log.Debug("WebSocket upgrade failed", "err", err)
return
}
codec := newWebsocketCodec(conn)
s.ServeCodec(codec, 0)
})
}
// wsHandshakeValidator returns a handler that verifies the origin during the
// websocket upgrade process. When a '*' is specified as an allowed origins all
// connections are accepted.
func wsHandshakeValidator(allowedOrigins []string) func(*http.Request) bool {
origins := mapset.NewSet()
allowAllOrigins := false
for _, origin := range allowedOrigins {
if origin == "*" {
allowAllOrigins = true
}
if origin != "" {
origins.Add(strings.ToLower(origin))
}
}
// allow localhost if no allowedOrigins are specified.
if len(origins.ToSlice()) == 0 {
origins.Add("http://localhost")
if hostname, err := os.Hostname(); err == nil {
origins.Add("http://" + strings.ToLower(hostname))
}
}
log.Debug(fmt.Sprintf("Allowed origin(s) for WS RPC interface %v", origins.ToSlice()))
f := func(req *http.Request) bool {
// Skip origin verification if no Origin header is present. The origin check
// is supposed to protect against browser based attacks. Browsers always set
// Origin. Non-browser software can put anything in origin and checking it doesn't
// provide additional security.
if _, ok := req.Header["Origin"]; !ok {
return true
}
// Verify origin against whitelist.
origin := strings.ToLower(req.Header.Get("Origin"))
if allowAllOrigins || origins.Contains(origin) {
return true
}
log.Warn("Rejected WebSocket connection", "origin", origin)
return false
}
return f
}
type wsHandshakeError struct {
err error
status string
}
func (e wsHandshakeError) Error() string {
s := e.err.Error()
if e.status != "" {
s += " (HTTP status " + e.status + ")"
}
return s
}
// DialWebsocketWithDialer creates a new RPC client that communicates with a JSON-RPC server
// that is listening on the given endpoint using the provided dialer.
func DialWebsocketWithDialer(ctx context.Context, endpoint, origin string, dialer websocket.Dialer) (*Client, error) {
endpoint, header, err := wsClientHeaders(endpoint, origin)
if err != nil {
return nil, err
}
return newClient(ctx, func(ctx context.Context) (ServerCodec, error) {
conn, resp, err := dialer.DialContext(ctx, endpoint, header)
if err != nil {
hErr := wsHandshakeError{err: err}
if resp != nil {
hErr.status = resp.Status
}
return nil, hErr
}
return newWebsocketCodec(conn), nil
})
}
// DialWebsocket creates a new RPC client that communicates with a JSON-RPC server
// that is listening on the given endpoint.
//
// The context is used for the initial connection establishment. It does not
// affect subsequent interactions with the client.
func DialWebsocket(ctx context.Context, endpoint, origin string) (*Client, error) {
dialer := websocket.Dialer{
ReadBufferSize: wsReadBuffer,
WriteBufferSize: wsWriteBuffer,
WriteBufferPool: wsBufferPool,
}
return DialWebsocketWithDialer(ctx, endpoint, origin, dialer)
}
func wsClientHeaders(endpoint, origin string) (string, http.Header, error) {
endpointURL, err := url.Parse(endpoint)
if err != nil {
return endpoint, nil, err
}
header := make(http.Header)
if origin != "" {
header.Add("origin", origin)
}
if endpointURL.User != nil {
b64auth := base64.StdEncoding.EncodeToString([]byte(endpointURL.User.String()))
header.Add("authorization", "Basic "+b64auth)
endpointURL.User = nil
}
return endpointURL.String(), header, nil
}
type websocketCodec struct {
*jsonCodec
conn *websocket.Conn
wg sync.WaitGroup
pingReset chan struct{}
}
func newWebsocketCodec(conn *websocket.Conn) ServerCodec {
conn.SetReadLimit(maxRequestContentLength)
wc := &websocketCodec{
jsonCodec: NewFuncCodec(conn, conn.WriteJSON, conn.ReadJSON).(*jsonCodec),
conn: conn,
pingReset: make(chan struct{}, 1),
}
wc.wg.Add(1)
go wc.pingLoop()
return wc
}
func (wc *websocketCodec) close() {
wc.jsonCodec.close()
wc.wg.Wait()
}
func (wc *websocketCodec) writeJSON(ctx context.Context, v interface{}) error {
err := wc.jsonCodec.writeJSON(ctx, v)
if err == nil {
// Notify pingLoop to delay the next idle ping.
select {
case wc.pingReset <- struct{}{}:
default:
}
}
return err
}
// pingLoop sends periodic ping frames when the connection is idle.
func (wc *websocketCodec) pingLoop() {
var timer = time.NewTimer(wsPingInterval)
defer wc.wg.Done()
defer timer.Stop()
for {
select {
case <-wc.closed():
return
case <-wc.pingReset:
if !timer.Stop() {
<-timer.C
}
timer.Reset(wsPingInterval)
case <-timer.C:
wc.jsonCodec.encMu.Lock()
wc.conn.SetWriteDeadline(time.Now().Add(wsPingWriteTimeout))
wc.conn.WriteMessage(websocket.PingMessage, nil)
wc.jsonCodec.encMu.Unlock()
timer.Reset(wsPingInterval)
}
}
}