func (wp *wsPty) Start() {
var err error
args := flag.Args()
wp.Cmd = exec.Command(cmdFlag, args...)
env := os.Environ()
env = append(env, "TERM=xterm")
wp.Cmd.Env = env
wp.Pty, err = pty.Start(wp.Cmd)
if err != nil {
log.Fatalf("Failed to start command: %s\n", err)
}
//Set the size of the pty
pty.Setsize(wp.Pty, 60, 200)
}
func ptyHandler(w http.ResponseWriter, r *http.Request) {
conn, err := upgrader.Upgrade(w, r, nil)
if err != nil {
log.Fatalf("Websocket upgrade failed: %s\n", err)
}
defer conn.Close()
wp := wsPty{}
// TODO: check for errors, return 500 on fail
wp.Start()
// copy everything from the pty master to the websocket
// using base64 encoding for now due to limitations in term.js
go func() {
buf := make([]byte, 8192)
reader := bufio.NewReader(wp.Pty)
var buffer bytes.Buffer
// TODO: more graceful exit on socket close / process exit
for {
n, err := reader.Read(buf)
if err != nil {
log.Printf("Failed to read from pty master: %s", err)
return
}
//read byte array as Unicode code points (rune in go)
bufferBytes := buffer.Bytes()
runeReader := bufio.NewReader(bytes.NewReader(append(bufferBytes[:], buf[:n]...)))
buffer.Reset()
i := 0
for i < n {
char, charLen, e := runeReader.ReadRune()
if e != nil {
log.Printf("Failed to read from pty master: %s", err)
return
}
if char == utf8.RuneError {
runeReader.UnreadRune()
break
}
i += charLen
buffer.WriteRune(char)
}
err = conn.WriteMessage(websocket.TextMessage, buffer.Bytes())
if err != nil {
log.Printf("Failed to send UTF8 char: %s", err)
return
}
buffer.Reset()
if i < n {
buffer.Write(buf[i:n])
}
}
}()
type Message struct {
Type string `json:"type"`
Data json.RawMessage `json:"data"`
}
// read from the web socket, copying to the pty master
// messages are expected to be text and base64 encoded
for {
mt, payload, err := conn.ReadMessage()
if err != nil {
if err != io.EOF {
log.Printf("conn.ReadMessage failed: %s\n", err)
return
}
}
var msg Message
switch mt {
case websocket.BinaryMessage:
log.Printf("Ignoring binary message: %q\n", payload)
case websocket.TextMessage:
err := json.Unmarshal(payload, &msg)
if err != nil {
log.Printf("Invalid message %s\n", err)
continue
}
switch msg.Type {
case "resize":
var size []float64
err := json.Unmarshal(msg.Data, &size)
if err != nil {
log.Printf("Invalid resize message: %s\n", err)
} else {
pty.Setsize(wp.Pty, uint16(size[1]), uint16(size[0]))
}
case "data":
var dat string
err := json.Unmarshal(msg.Data, &dat)
if err != nil {
log.Printf("Invalid data message %s\n", err)
} else {
wp.Pty.Write([]byte(dat))
}
default:
log.Printf("Invalid message type %d\n", mt)
return
}
default:
log.Printf("Invalid message type %d\n", mt)
return
}
}
wp.Stop()
}