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websockethandlers.go
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websockethandlers.go
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// Copyright (c) 2017, The dcrdata developers
// See LICENSE for details.
package explorer
import (
"bytes"
"encoding/json"
"fmt"
"net/http"
"strconv"
"time"
"golang.org/x/net/websocket"
)
// RootWebsocket is the websocket handler for all pages
func (exp *explorerUI) RootWebsocket(w http.ResponseWriter, r *http.Request) {
wsHandler := websocket.Handler(func(ws *websocket.Conn) {
// Create channel to signal updated data availability
updateSig := make(hubSpoke)
// register websocket client with our signal channel
exp.wsHub.RegisterClient(&updateSig)
// unregister (and close signal channel) before return
defer exp.wsHub.UnregisterClient(&updateSig)
requestLimit := 1 << 20
// set the max payload size to 1 MB
ws.MaxPayloadBytes = requestLimit
// Ticker for a regular ping
ticker := time.NewTicker(pingInterval)
defer ticker.Stop()
// Periodically ping clients over websocket connection
go func() {
for range ticker.C {
exp.wsHub.HubRelay <- sigPingAndUserCount
}
}()
// Start listening for websocket messages from client with raw
// transaction bytes (hex encoded) to decode or broadcast.
go func() {
for {
// Wait to receive a message on the websocket
msg := &WebSocketMessage{}
ws.SetReadDeadline(time.Now().Add(wsReadTimeout))
if err := websocket.JSON.Receive(ws, &msg); err != nil {
log.Warnf("websocket client receive error: %v", err)
return
}
// handle received message according to event ID
var webData WebSocketMessage
switch msg.EventId {
case "decodetx":
webData.EventId = msg.EventId + "Resp"
if len(msg.Message) > requestLimit {
log.Debug("Request size over limit")
webData.Message = "Request too large"
break
}
log.Debugf("Received decodetx signal for hex: %.40s...", msg.Message)
tx, err := exp.blockData.DecodeRawTransaction(msg.Message)
if err == nil {
message, err := json.MarshalIndent(tx, "", " ")
if err != nil {
log.Warn("Invalid JSON message: ", err)
webData.Message = fmt.Sprintf("Error: Could not encode JSON message")
break
}
webData.Message = string(message)
} else {
log.Debugf("Could not decode raw tx")
webData.Message = fmt.Sprintf("Error: %v", err)
}
case "sendtx":
webData.EventId = msg.EventId + "Resp"
if len(msg.Message) > requestLimit {
log.Debugf("Request size over limit")
webData.Message = "Request too large"
break
}
log.Debugf("Received sendtx signal for hex: %.40s...", msg.Message)
txid, err := exp.blockData.SendRawTransaction(msg.Message)
if err != nil {
webData.Message = fmt.Sprintf("Error: %v", err)
} else {
webData.Message = fmt.Sprintf("Transaction sent: %s", txid)
}
case "ping":
log.Tracef("We've been pinged: %.40s...", msg.Message)
continue
default:
log.Warnf("Unrecognized event ID: %v", msg.EventId)
continue
}
// send the response back on the websocket
ws.SetWriteDeadline(time.Now().Add(wsWriteTimeout))
if err := websocket.JSON.Send(ws, webData); err != nil {
log.Debugf("Failed to encode WebSocketMessage %s: %v",
webData.EventId, err)
// If the send failed, the client is probably gone, so close
// the connection and quit.
return
}
}
}()
// Ping and block update loop (send only)
loop:
for {
// Wait for signal from the hub to update
select {
case sig, ok := <-updateSig:
// Check if the update channel was closed. Either the websocket
// hub will do it after unregistering the client, or forcibly in
// response to (http.CloseNotifier).CloseNotify() and only then if
// the hub has somehow lost track of the client.
if !ok {
//ws.WriteClose(1)
exp.wsHub.UnregisterClient(&updateSig)
break loop
}
if _, ok = eventIDs[sig]; !ok {
break loop
}
log.Tracef("signaling client: %p", &updateSig)
// Write block data to websocket client
exp.NewBlockDataMtx.RLock()
exp.MempoolData.RLock()
webData := WebSocketMessage{
EventId: eventIDs[sig],
}
buff := new(bytes.Buffer)
enc := json.NewEncoder(buff)
switch sig {
case sigNewBlock:
enc.Encode(WebsocketBlock{
Block: exp.NewBlockData,
Extra: exp.ExtraInfo,
})
webData.Message = buff.String()
case sigMempoolUpdate:
enc.Encode(exp.MempoolData)
webData.Message = buff.String()
case sigPingAndUserCount:
// ping and send user count
webData.Message = strconv.Itoa(exp.wsHub.NumClients())
}
ws.SetWriteDeadline(time.Now().Add(wsWriteTimeout))
err := websocket.JSON.Send(ws, webData)
exp.MempoolData.RUnlock()
exp.NewBlockDataMtx.RUnlock()
if err != nil {
log.Debugf("Failed to encode WebSocketMessage %v: %v", sig, err)
// If the send failed, the client is probably gone, so close
// the connection and quit.
return
}
case <-exp.wsHub.quitWSHandler:
break loop
}
}
})
wsHandler.ServeHTTP(w, r)
}