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//
// dolmetschctl
//
//
// Copyright (C) 2019 Christian Pointner <equinox@spreadspace.org>
//
// This file is part of dolmetschctl.
//
// dolmetschctl is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// any later version.
//
// dolmetschctl 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with dolmetschctl. If not, see <http://www.gnu.org/licenses/>.
//
package main
import (
"encoding/json"
"io"
"io/ioutil"
"log"
"net/http"
"github.com/gorilla/websocket"
)
type webSocketRequest struct {
Command string `json:"command"`
Args []string `json:"arguments"`
}
type webSocketResponseBase struct {
ResponseCode int `json:"response-code"`
Type string `json:"type"`
}
type webSocketResponseError struct {
webSocketResponseBase
ErrorString string `json:"error"`
}
type webSocketResponseState struct {
webSocketResponseBase
webState
}
type webSocketResponseLanguages struct {
webSocketResponseBase
Languages []Language `json:"languages"`
}
func sendWebSocketResponse(ws *websocket.Conn, rd interface{}) {
if err := ws.WriteJSON(rd); err != nil {
log.Println("Web(socket) client", ws.RemoteAddr(), "write error:", err)
}
}
func sendWebSocketErrorResponse(ws *websocket.Conn, code int, errStr string) {
rd := &webSocketResponseError{}
rd.ResponseCode = code
rd.Type = "error"
rd.ErrorString = errStr
sendWebSocketResponse(ws, rd)
}
func webSocketHandleRequest(ws *websocket.Conn, sm *StateMachine, req webSocketRequest, subCh chan<- FullState) {
switch req.Command {
case "state":
if len(req.Args) != 0 {
sendWebSocketErrorResponse(ws, http.StatusBadRequest, "command 'state' expects no arguments")
return
}
var result webSocketResponseState
result.ResponseCode = http.StatusOK
result.Type = "state"
result.State, result.Ratio, result.Lang = sm.GetState()
sendWebSocketResponse(ws, result)
case "subscribe":
if len(req.Args) != 0 {
sendWebSocketErrorResponse(ws, http.StatusBadRequest, "command 'subscribe' expects no arguments")
return
}
if err := sm.SubscribeState(subCh); err != nil {
sendWebSocketErrorResponse(ws, http.StatusInternalServerError, err.Error())
return
}
var result webSocketResponseState
result.ResponseCode = http.StatusOK
result.Type = "state"
result.State, result.Ratio, result.Lang = sm.GetState()
sendWebSocketResponse(ws, result)
case "languages":
if len(req.Args) != 0 {
sendWebSocketErrorResponse(ws, http.StatusBadRequest, "command 'languages' expects no arguments")
return
}
var result webSocketResponseLanguages
result.ResponseCode = http.StatusOK
result.Type = "languages"
result.Languages = sm.GetLanguages()
sendWebSocketResponse(ws, result)
case "language":
if len(req.Args) != 1 {
sendWebSocketErrorResponse(ws, http.StatusBadRequest, "command 'language' expects exatly one argument")
return
}
if err := sm.SetLanguage(Language(req.Args[0])); err != nil {
sendWebSocketErrorResponse(ws, http.StatusBadRequest, err.Error())
return
}
var result webSocketResponseState
result.ResponseCode = http.StatusOK
result.Type = "state"
result.State, result.Ratio, result.Lang = sm.GetState()
sendWebSocketResponse(ws, result)
default:
sendWebSocketErrorResponse(ws, http.StatusBadRequest, "unkown command: '"+req.Command+"'")
}
}
func webSocketSessionHandler(ws *websocket.Conn, sm *StateMachine, reqCh <-chan webSocketRequest) {
defer ws.Close()
subCh := make(chan FullState, 100)
for {
select {
case state, ok := <-subCh:
if !ok {
return
}
var result webSocketResponseState
result.ResponseCode = http.StatusOK
result.Type = "state"
result.State = state.state
result.Ratio = state.ratio
result.Lang = state.language
sendWebSocketResponse(ws, result)
case req, ok := <-reqCh:
if !ok {
return
}
webSocketHandleRequest(ws, sm, req, subCh)
}
}
}
func webSocketHandler(sm *StateMachine, w http.ResponseWriter, r *http.Request) {
ws, err := websocket.Upgrade(w, r, nil, 64*1024, 64*1024)
if _, ok := err.(websocket.HandshakeError); ok {
http.Error(w, "Not a websocket handshake", 400)
return
} else if err != nil {
log.Println("Web(socket) client", ws.RemoteAddr(), "error:", err)
return
}
log.Println("Web(socket) client", ws.RemoteAddr(), "connected")
reqCh := make(chan webSocketRequest)
go webSocketSessionHandler(ws, sm, reqCh)
defer close(reqCh)
for {
t, r, err := ws.NextReader()
if err != nil {
log.Println("Web(socket) Client", ws.RemoteAddr(), "disconnected:", err)
return
}
switch t {
case websocket.TextMessage:
var req webSocketRequest
dec := json.NewDecoder(r)
dec.DisallowUnknownFields()
if err := dec.Decode(&req); err != nil {
if err == io.EOF {
err = io.ErrUnexpectedEOF
}
log.Println("Web(socket) client", ws.RemoteAddr(), "request error:", err)
sendWebSocketErrorResponse(ws, http.StatusBadRequest, err.Error())
return
}
reqCh <- req
case websocket.BinaryMessage:
sendWebSocketErrorResponse(ws, http.StatusBadRequest, "binary messages are not allowed")
io.Copy(ioutil.Discard, r) // consume all the data
}
}
}
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