refactor: decouple gotty app with terminal backends

app/app.go

@@ -13,20 +13,18 @@ import (
 	"net"
 	"net/http"
 	"net/url"
-	"os/exec"
 	"strconv"
 	"strings"
 	"sync"
 	"sync/atomic"
-	"text/template"
 	"time"
 
+	"github.com/yudai/gotty/backends"
 	"github.com/yudai/gotty/utils"
 
 	"github.com/braintree/manners"
 	"github.com/elazarl/go-bindata-assetfs"
 	"github.com/gorilla/websocket"
-	"github.com/kr/pty"
 	"github.com/yudai/umutex"
 )
 
@@ -36,14 +34,12 @@ type InitMessage struct {
 }
 
 type App struct {
-	command []string
+	manager backends.ClientContextManager
 	options *Options
 
 	upgrader *websocket.Upgrader
 	server   *manners.GracefulServer
 
-	titleTemplate *template.Template
-
 	onceMutex *umutex.UnblockingMutex
 	timer     *time.Timer
 
@@ -66,14 +62,12 @@ type Options struct {
 	TLSKeyFile          string                 `hcl:"tls_key_file" flagName:"tls-key" flagDescribe:"TLS/SSL key file path" default:"~/.gotty.key"`
 	EnableTLSClientAuth bool                   `hcl:"enable_tls_client_auth" default:"false"`
 	TLSCACrtFile        string                 `hcl:"tls_ca_crt_file" flagName:"tls-ca-crt" flagDescribe:"TLS/SSL CA certificate file for client certifications" default:"~/.gotty.ca.crt"`
-	TitleFormat         string                 `hcl:"title_format" flagName:"title-format" flagDescribe:"Title format of browser window" default:"GoTTY - {{ .Command }} ({{ .Hostname }})"`
 	EnableReconnect     bool                   `hcl:"enable_reconnect" flagName:"reconnect" flagDescribe:"Enable reconnection" default:"false"`
 	ReconnectTime       int                    `hcl:"reconnect_time" flagName:"reconnect-time" flagDescribe:"Time to reconnect" default:"10"`
 	MaxConnection       int                    `hcl:"max_connection" flagName:"max-connection" flagDescribe:"Maximum connection to gotty" default:"0"`
 	Once                bool                   `hcl:"once" flagName:"once" flagDescribe:"Accept only one client and exit on disconnection" default:"false"`
 	Timeout             int                    `hcl:"timeout" flagName:"timeout" flagDescribe:"Timeout seconds for waiting a client(0 to disable)" default:"0"`
 	PermitArguments     bool                   `hcl:"permit_arguments" flagName:"permit-arguments" flagDescribe:"Permit clients to send command line arguments in URL (e.g. http://example.com:8080/?arg=AAA&arg=BBB)" default:"true"`
-	CloseSignal         int                    `hcl:"close_signal" flagName:"close-signal" flagDescribe:"Signal sent to the command process when gotty close it (default: SIGHUP)" default:"1"`
 	Preferences         HtermPrefernces        `hcl:"preferences"`
 	RawPreferences      map[string]interface{} `hcl:"preferences"`
 	Width               int                    `hcl:"width" flagName:"width" flagDescribe:"Static width of the screen, 0(default) means dynamically resize" default:"0"`
@@ -82,16 +76,10 @@ type Options struct {
 
 var Version = "1.0.0"
 
-func New(command []string, options *Options) (*App, error) {
-	titleTemplate, err := template.New("title").Parse(options.TitleFormat)
-	if err != nil {
-		return nil, errors.New("Title format string syntax error")
-	}
-
+func New(manager backends.ClientContextManager, options *Options) (*App, error) {
 	connections := int64(0)
-
 	return &App{
-		command: command,
+		manager: manager,
 		options: options,
 
 		upgrader: &websocket.Upgrader{
@@ -99,9 +87,6 @@ func New(command []string, options *Options) (*App, error) {
 			WriteBufferSize: 1024,
 			Subprotocols:    []string{"gotty"},
 		},
-
-		titleTemplate: titleTemplate,
-
 		onceMutex:   umutex.New(),
 		connections: &connections,
 	}, nil
@@ -169,10 +154,6 @@ func (app *App) Run() error {
 	if app.options.EnableTLS {
 		scheme = "https"
 	}
-	log.Printf(
-		"Server is starting with command: %s",
-		strings.Join(app.command, " "),
-	)
 	if app.options.Address != "" {
 		log.Printf(
 			"URL: %s",
@@ -267,8 +248,23 @@ func (app *App) restartTimer() {
 
 func (app *App) handleWS(w http.ResponseWriter, r *http.Request) {
 	app.stopTimer()
-
 	connections := atomic.AddInt64(app.connections, 1)
+	defer func() {
+		connections := atomic.AddInt64(app.connections, -1)
+
+		if app.options.MaxConnection != 0 {
+			log.Printf("Connection closed: %s, connections: %d/%d",
+				r.RemoteAddr, connections, app.options.MaxConnection)
+		} else {
+			log.Printf("Connection closed: %s, connections: %d",
+				r.RemoteAddr, connections)
+		}
+
+		if connections == 0 {
+			app.restartTimer()
+		}
+	}()
+
 	if int64(app.options.MaxConnection) != 0 {
 		if connections > int64(app.options.MaxConnection) {
 			log.Printf("Reached max connection: %d", app.options.MaxConnection)
@@ -287,11 +283,11 @@ func (app *App) handleWS(w http.ResponseWriter, r *http.Request) {
 		log.Print("Failed to upgrade connection: " + err.Error())
 		return
 	}
+	defer conn.Close()
 
 	_, stream, err := conn.ReadMessage()
 	if err != nil {
 		log.Print("Failed to authenticate websocket connection")
-		conn.Close()
 		return
 	}
 	var init InitMessage
@@ -299,32 +295,34 @@ func (app *App) handleWS(w http.ResponseWriter, r *http.Request) {
 	err = json.Unmarshal(stream, &init)
 	if err != nil {
 		log.Printf("Failed to parse init message %v", err)
-		conn.Close()
 		return
 	}
 	if init.AuthToken != app.options.Credential {
 		log.Print("Failed to authenticate websocket connection")
-		conn.Close()
 		return
 	}
-	argv := app.command[1:]
-	if app.options.PermitArguments {
-		if init.Arguments == "" {
-			init.Arguments = "?"
+
+	var queryPath string
+	if app.options.PermitArguments && init.Arguments != "" {
+		queryPath = init.Arguments
+	} else {
+		queryPath = "?"
 	}
-		query, err := url.Parse(init.Arguments)
+
+	query, err := url.Parse(queryPath)
 	if err != nil {
 		log.Print("Failed to parse arguments")
-			conn.Close()
 		return
 	}
-		params := query.Query()["arg"]
-		if len(params) != 0 {
-			argv = append(argv, params...)
-		}
+	params := query.Query()
+	ctx, err := app.manager.New(params)
+	if err != nil {
+		log.Printf("Failed to new client context %v", err)
+		return
 	}
 
 	app.server.StartRoutine()
+	defer app.server.FinishRoutine()
 
 	if app.options.Once {
 		if app.onceMutex.TryLock() { // no unlock required, it will die soon
@@ -337,30 +335,7 @@ func (app *App) handleWS(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
-	cmd := exec.Command(app.command[0], argv...)
-	ptyIo, err := pty.Start(cmd)
-	if err != nil {
-		log.Print("Failed to execute command")
-		return
-	}
-
-	if app.options.MaxConnection != 0 {
-		log.Printf("Command is running for client %s with PID %d (args=%q), connections: %d/%d",
-			r.RemoteAddr, cmd.Process.Pid, strings.Join(argv, " "), connections, app.options.MaxConnection)
-	} else {
-		log.Printf("Command is running for client %s with PID %d (args=%q), connections: %d",
-			r.RemoteAddr, cmd.Process.Pid, strings.Join(argv, " "), connections)
-	}
-
-	context := &clientContext{
-		app:        app,
-		request:    r,
-		connection: conn,
-		command:    cmd,
-		pty:        ptyIo,
-		writeMutex: &sync.Mutex{},
-	}
-
+	context := &clientContext{app: app, connection: conn, writeMutex: &sync.Mutex{}, ClientContext: ctx}
 	context.goHandleClient()
 }
 

app/client_context.go

@@ -1,29 +1,21 @@
 package app
 
 import (
-	"bytes"
 	"encoding/base64"
 	"encoding/json"
 	"log"
-	"net/http"
-	"os"
-	"os/exec"
 	"strings"
 	"sync"
-	"sync/atomic"
-	"syscall"
-	"unsafe"
 
 	"github.com/fatih/structs"
 	"github.com/gorilla/websocket"
+	"github.com/yudai/gotty/backends"
 )
 
 type clientContext struct {
+	backends.ClientContext
 	app        *App
-	request    *http.Request
 	connection *websocket.Conn
-	command    *exec.Cmd
-	pty        *os.File
 	writeMutex *sync.Mutex
 }
 
@@ -46,56 +38,23 @@ type argResizeTerminal struct {
 	Rows    float64
 }
 
-type ContextVars struct {
-	Command    string
-	Pid        int
-	Hostname   string
-	RemoteAddr string
-}
-
 func (context *clientContext) goHandleClient() {
-	exit := make(chan bool, 2)
+	exit := make(chan bool, 3)
+
+	context.Start(exit)
 
 	go func() {
 		defer func() { exit <- true }()
-
 		context.processSend()
 	}()
 
 	go func() {
 		defer func() { exit <- true }()
-
 		context.processReceive()
 	}()
 
-	go func() {
-		defer context.app.server.FinishRoutine()
-		defer func() {
-			connections := atomic.AddInt64(context.app.connections, -1)
-
-			if context.app.options.MaxConnection != 0 {
-				log.Printf("Connection closed: %s, connections: %d/%d",
-					context.request.RemoteAddr, connections, context.app.options.MaxConnection)
-			} else {
-				log.Printf("Connection closed: %s, connections: %d",
-					context.request.RemoteAddr, connections)
-			}
-
-			if connections == 0 {
-				context.app.restartTimer()
-			}
-		}()
-
 	<-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.Signal(context.app.options.CloseSignal))
-
-		context.command.Wait()
-		context.connection.Close()
-	}()
+	context.TearDown()
 }
 
 func (context *clientContext) processSend() {
@@ -107,9 +66,9 @@ func (context *clientContext) processSend() {
 	buf := make([]byte, 1024)
 
 	for {
-		size, err := context.pty.Read(buf)
+		size, err := context.OutputReader().Read(buf)
 		if err != nil {
-			log.Printf("Command exited for: %s", context.request.RemoteAddr)
+			log.Printf("failed to read output from terminal backend: %v", err)
 			return
 		}
 		safeMessage := base64.StdEncoding.EncodeToString([]byte(buf[:size]))
@@ -127,19 +86,11 @@ func (context *clientContext) write(data []byte) error {
 }
 
 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,
-	}
-
-	titleBuffer := new(bytes.Buffer)
-	if err := context.app.titleTemplate.Execute(titleBuffer, titleVars); err != nil {
+	windowTitle, err := context.WindowTitle()
+	if err != nil {
 		return err
 	}
-	if err := context.write(append([]byte{SetWindowTitle}, titleBuffer.Bytes()...)); err != nil {
+	if err := context.write(append([]byte{SetWindowTitle}, []byte(windowTitle)...)); err != nil {
 		return err
 	}
 
@@ -187,7 +138,7 @@ func (context *clientContext) processReceive() {
 				break
 			}
 
-			_, err := context.pty.Write(data[1:])
+			_, err := context.InputWriter().Write(data[1:])
 			if err != nil {
 				return
 			}
@@ -204,7 +155,6 @@ func (context *clientContext) processReceive() {
 				log.Print("Malformed remote command")
 				return
 			}
-
 			rows := uint16(context.app.options.Height)
 			if rows == 0 {
 				rows = uint16(args.Rows)
@@ -215,24 +165,7 @@ func (context *clientContext) processReceive() {
 				columns = uint16(args.Columns)
 			}
 
-			window := struct {
-				row uint16
-				col uint16
-				x   uint16
-				y   uint16
-			}{
-				rows,
-				columns,
-				0,
-				0,
-			}
-			syscall.Syscall(
-				syscall.SYS_IOCTL,
-				context.pty.Fd(),
-				syscall.TIOCSWINSZ,
-				uintptr(unsafe.Pointer(&window)),
-			)
-
+			context.ResizeTerminal(columns, rows)
 		default:
 			log.Print("Unknown message type")
 			return

backends/interface.go

@@ -0,0 +1,19 @@
+package backends
+
+import (
+	"io"
+	"net/url"
+)
+
+type ClientContextManager interface {
+	New(params url.Values) (ClientContext, error)
+}
+
+type ClientContext interface {
+	WindowTitle() (string, error)
+	Start(exitCh chan bool)
+	InputWriter() io.Writer
+	OutputReader() io.Reader
+	ResizeTerminal(width, height uint16) error
+	TearDown() error
+}

backends/ptycommand/command.go

@@ -0,0 +1,130 @@
+package ptycommand
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"log"
+	"net/url"
+	"os"
+	"os/exec"
+	"syscall"
+	"text/template"
+	"unsafe"
+
+	"github.com/yudai/gotty/backends"
+
+	"github.com/kr/pty"
+)
+
+type Options struct {
+	CloseSignal int    `hcl:"close_signal" flagName:"close-signal" flagSName:"" flagDescribe:"Signal sent to the command process when gotty close it (default: SIGHUP)" default:"1"`
+	TitleFormat string `hcl:"title_format" flagName:"title-format" flagSName:"" flagDescribe:"Title format of browser window" default:"GoTTY - {{ .Command }} ({{ .Hostname }})"`
+}
+
+type CommandClientContextManager struct {
+	command []string
+
+	options       *Options
+	titleTemplate *template.Template
+}
+
+func NewCommandClientContextManager(command []string, options *Options) (*CommandClientContextManager, error) {
+	titleTemplate, err := template.New("title").Parse(options.TitleFormat)
+	if err != nil {
+		return nil, fmt.Errorf("Title format string syntax error: %v", options.TitleFormat)
+	}
+	return &CommandClientContextManager{command: command, options: options, titleTemplate: titleTemplate}, nil
+}
+
+type CommandClientContext struct {
+	cmd *exec.Cmd
+	pty *os.File
+	mgr *CommandClientContextManager
+}
+
+func (mgr *CommandClientContextManager) New(params url.Values) (backends.ClientContext, error) {
+	argv := mgr.command[1:]
+	args := params["arg"]
+	if len(args) != 0 {
+		argv = append(argv, args...)
+	}
+
+	cmd := exec.Command(mgr.command[0], argv...)
+	return &CommandClientContext{cmd: cmd, mgr: mgr}, nil
+}
+
+func (context *CommandClientContext) WindowTitle() (title string, err error) {
+	hostname, _ := os.Hostname()
+
+	titleVars := struct {
+		Command  string
+		Pid      int
+		Hostname string
+	}{
+		Command:  context.cmd.Path,
+		Pid:      context.cmd.Process.Pid,
+		Hostname: hostname,
+	}
+
+	titleBuffer := new(bytes.Buffer)
+	if err := context.mgr.titleTemplate.Execute(titleBuffer, titleVars); err != nil {
+		return "", err
+	}
+	return titleBuffer.String(), nil
+}
+
+func (context *CommandClientContext) Start(exitCh chan bool) {
+	ptyIo, err := pty.Start(context.cmd)
+	if err != nil {
+		log.Printf("failed to start command %v", err)
+		exitCh <- true
+	} else {
+		context.pty = ptyIo
+	}
+}
+
+func (context *CommandClientContext) InputWriter() io.Writer {
+	return context.pty
+}
+
+func (context *CommandClientContext) OutputReader() io.Reader {
+	return context.pty
+}
+
+func (context *CommandClientContext) ResizeTerminal(width, height uint16) error {
+	window := struct {
+		row uint16
+		col uint16
+		x   uint16
+		y   uint16
+	}{
+		height,
+		width,
+		0,
+		0,
+	}
+	_, _, errno := syscall.Syscall(
+		syscall.SYS_IOCTL,
+		context.pty.Fd(),
+		syscall.TIOCSWINSZ,
+		uintptr(unsafe.Pointer(&window)),
+	)
+	if errno != 0 {
+		return errno
+	} else {
+		return nil
+	}
+}
+
+func (context *CommandClientContext) TearDown() error {
+	context.pty.Close()
+
+	// Even if the PTY has been closed,
+	// Read(0 in processSend() keeps blocking and the process doen't exit
+	if context.cmd != nil && context.cmd.Process != nil {
+		context.cmd.Process.Signal(syscall.Signal(context.mgr.options.CloseSignal))
+		context.cmd.Wait()
+	}
+	return nil
+}

main.go

@@ -9,22 +9,28 @@ import (
 	"github.com/codegangsta/cli"
 
 	"github.com/yudai/gotty/app"
+	"github.com/yudai/gotty/backends/ptycommand"
 	"github.com/yudai/gotty/utils"
 )
 
 func main() {
 	cmd := cli.NewApp()
-	cmd.Version = app.Version
 	cmd.Name = "gotty"
+	cmd.Version = app.Version
 	cmd.Usage = "Share your terminal as a web application"
 	cmd.HideHelp = true
+	cli.AppHelpTemplate = helpTemplate
 
-	options := &app.Options{}
-	if err := utils.ApplyDefaultValues(options); err != nil {
+	appOptions := &app.Options{}
+	if err := utils.ApplyDefaultValues(appOptions); err != nil {
+		exit(err, 1)
+	}
+	backendOptions := &ptycommand.Options{}
+	if err := utils.ApplyDefaultValues(backendOptions); err != nil {
 		exit(err, 1)
 	}
 
-	cliFlags, flagMappings, err := utils.GenerateFlags(options)
+	cliFlags, flagMappings, err := utils.GenerateFlags(appOptions, backendOptions)
 	if err != nil {
 		exit(err, 3)
 	}
@@ -41,28 +47,33 @@ func main() {
 
 	cmd.Action = func(c *cli.Context) {
 		if len(c.Args()) == 0 {
+			msg := "Error: No command given."
 			cli.ShowAppHelp(c)
-			exit(fmt.Errorf("Error: No command given."), 1)
+			exit(fmt.Errorf(msg), 1)
 		}
 
 		configFile := c.String("config")
 		_, err := os.Stat(utils.ExpandHomeDir(configFile))
 		if configFile != "~/.gotty" || !os.IsNotExist(err) {
-			if err := utils.ApplyConfigFile(configFile, options); err != nil {
+			if err := utils.ApplyConfigFile(configFile, appOptions, backendOptions); err != nil {
 				exit(err, 2)
 			}
 		}
 
-		utils.ApplyFlags(cliFlags, flagMappings, c, options)
+		utils.ApplyFlags(cliFlags, flagMappings, c, appOptions, backendOptions)
 
-		options.EnableBasicAuth = c.IsSet("credential")
-		options.EnableTLSClientAuth = c.IsSet("tls-ca-crt")
+		appOptions.EnableBasicAuth = c.IsSet("credential")
+		appOptions.EnableTLSClientAuth = c.IsSet("tls-ca-crt")
 
-		if err := app.CheckConfig(options); err != nil {
+		if err := app.CheckConfig(appOptions); err != nil {
 			exit(err, 6)
 		}
 
-		app, err := app.New(c.Args(), options)
+		manager, err := ptycommand.NewCommandClientContextManager(c.Args(), backendOptions)
+		if err != nil {
+			exit(err, 3)
+		}
+		app, err := app.New(manager, appOptions)
 		if err != nil {
 			exit(err, 3)
 		}
@@ -74,9 +85,6 @@ func main() {
 			exit(err, 4)
 		}
 	}
-
-	cli.AppHelpTemplate = helpTemplate
-
 	cmd.Run(os.Args)
 }