package app import ( "encoding/json" "log" "net/http" "os" "os/exec" "strings" "syscall" "unsafe" "github.com/gorilla/websocket" "github.com/yudai/utf8reader" ) type clientContext struct { app *App request *http.Request connection *websocket.Conn command *exec.Cmd pty *os.File } const ( Input = '0' ResizeTerminal = '1' ) const ( Output = '0' SetWindowTitle = '1' SetPreferences = '2' SetReconnect = '3' ) type argResizeTerminal struct { Columns float64 Rows float64 } type ContextVars struct { Command string Pid int Hostname string RemoteAddr string } func (context *clientContext) goHandleClient() { exit := make(chan bool, 2) go func() { defer func() { exit <- true }() context.processSend() }() go func() { defer func() { exit <- true }() context.processReceive() }() context.app.server.StartRoutine() if context.app.options.Once { log.Printf("Last client accepted, closing the listener.") context.app.server.Close() } go func() { defer context.app.server.FinishRoutine() <-exit context.pty.Close() // Even if the PTY has been closed, // Read(0 in processSend() keeps blocking and the process doen't exit context.command.Process.Signal(syscall.SIGHUP) context.command.Wait() context.connection.Close() log.Printf("Connection closed: %s", context.request.RemoteAddr) }() } func (context *clientContext) processSend() { if err := context.sendInitialize(); err != nil { log.Printf(err.Error()) return } buf := make([]byte, 1024) utf8f := utf8reader.New(context.pty) for { size, err := utf8f.Read(buf) if err != nil { log.Printf("Command exited for: %s", context.request.RemoteAddr) return } err = context.connection.WriteMessage(websocket.TextMessage, append([]byte{Output}, buf[:size]...)) if err != nil { return } } } func (context *clientContext) sendInitialize() error { hostname, _ := os.Hostname() titleVars := ContextVars{ Command: strings.Join(context.app.command, " "), Pid: context.command.Process.Pid, Hostname: hostname, RemoteAddr: context.request.RemoteAddr, } writer, err := context.connection.NextWriter(websocket.TextMessage) if err != nil { return err } writer.Write([]byte{SetWindowTitle}) if err = context.app.titleTemplate.Execute(writer, titleVars); err != nil { return err } writer.Close() prefs, _ := json.Marshal(context.app.preferences) context.connection.WriteMessage( websocket.TextMessage, append([]byte{SetPreferences}, prefs...), ) if context.app.options.EnableReconnect { reconnect, _ := json.Marshal(context.app.options.ReconnectTime) context.connection.WriteMessage( websocket.TextMessage, append([]byte{SetReconnect}, reconnect...), ) } return nil } func (context *clientContext) processReceive() { for { _, data, err := context.connection.ReadMessage() if err != nil { return } switch data[0] { case Input: if !context.app.options.PermitWrite { break } _, err := context.pty.Write(data[1:]) if err != nil { return } case ResizeTerminal: var args argResizeTerminal err = json.Unmarshal(data[1:], &args) if err != nil { log.Print("Malformed remote command") return } window := struct { row uint16 col uint16 x uint16 y uint16 }{ uint16(args.Rows), uint16(args.Columns), 0, 0, } syscall.Syscall( syscall.SYS_IOCTL, context.pty.Fd(), syscall.TIOCSWINSZ, uintptr(unsafe.Pointer(&window)), ) default: log.Print("Unknown message type") return } } }