package server import ( "bytes" "context" "encoding/json" "fmt" "log" "net/http" "net/url" "sync/atomic" "github.com/gorilla/websocket" "github.com/pkg/errors" "github.com/sorenisanerd/gotty/webtty" ) func (server *Server) generateHandleWS(ctx context.Context, cancel context.CancelFunc, counter *counter) http.HandlerFunc { once := new(int64) go func() { select { case <-counter.timer().C: cancel() case <-ctx.Done(): } }() return func(w http.ResponseWriter, r *http.Request) { if server.options.Once { success := atomic.CompareAndSwapInt64(once, 0, 1) if !success { http.Error(w, "Server is shutting down", http.StatusServiceUnavailable) return } } num := counter.add(1) closeReason := "unknown reason" defer func() { num := counter.done() log.Printf( "Connection closed by %s: %s, connections: %d/%d", closeReason, r.RemoteAddr, num, server.options.MaxConnection, ) if server.options.Once { cancel() } }() if int64(server.options.MaxConnection) != 0 { if num > server.options.MaxConnection { closeReason = "exceeding max number of connections" return } } log.Printf("New client connected: %s, connections: %d/%d", r.RemoteAddr, num, server.options.MaxConnection) if r.Method != "GET" { http.Error(w, "Method not allowed", 405) return } conn, err := server.upgrader.Upgrade(w, r, nil) if err != nil { closeReason = err.Error() return } defer conn.Close() if server.options.PassHeaders { err = server.processWSConn(ctx, conn, r.Header) } else { err = server.processWSConn(ctx, conn, nil) } switch err { case ctx.Err(): closeReason = "cancelation" case webtty.ErrSlaveClosed: closeReason = server.factory.Name() case webtty.ErrMasterClosed: closeReason = "client" default: closeReason = fmt.Sprintf("an error: %s", err) } } } func (server *Server) processWSConn(ctx context.Context, conn *websocket.Conn, headers map[string][]string) error { typ, initLine, err := conn.ReadMessage() if err != nil { return errors.Wrapf(err, "failed to authenticate websocket connection") } if typ != websocket.TextMessage { return errors.New("failed to authenticate websocket connection: invalid message type") } var init InitMessage err = json.Unmarshal(initLine, &init) if err != nil { return errors.Wrapf(err, "failed to authenticate websocket connection") } if init.AuthToken != server.options.Credential { return errors.New("failed to authenticate websocket connection") } queryPath := "?" if server.options.PermitArguments && init.Arguments != "" { queryPath = init.Arguments } query, err := url.Parse(queryPath) if err != nil { return errors.Wrapf(err, "failed to parse arguments") } params := query.Query() var slave Slave slave, err = server.factory.New(params, headers) if err != nil { return errors.Wrapf(err, "failed to create backend") } defer slave.Close() titleVars := server.titleVariables( []string{"server", "master", "slave"}, map[string]map[string]interface{}{ "server": server.options.TitleVariables, "master": map[string]interface{}{ "remote_addr": conn.RemoteAddr(), }, "slave": slave.WindowTitleVariables(), }, ) titleBuf := new(bytes.Buffer) err = server.titleTemplate.Execute(titleBuf, titleVars) if err != nil { return errors.Wrapf(err, "failed to fill window title template") } opts := []webtty.Option{ webtty.WithWindowTitle(titleBuf.Bytes()), webtty.WithArguments(params), } if server.options.PermitWrite { opts = append(opts, webtty.WithPermitWrite()) } if server.options.EnableReconnect { opts = append(opts, webtty.WithReconnect(server.options.ReconnectTime)) } if server.options.Width > 0 { opts = append(opts, webtty.WithFixedColumns(server.options.Width)) } if server.options.Height > 0 { opts = append(opts, webtty.WithFixedRows(server.options.Height)) } tty, err := webtty.New(&wsWrapper{conn}, slave, opts...) if err != nil { return errors.Wrapf(err, "failed to create webtty") } err = tty.Run(ctx) return err } func (server *Server) handleIndex(w http.ResponseWriter, r *http.Request) { indexVars, err := server.indexVariables(r) if err != nil { http.Error(w, "Internal Server Error", 500) return } indexBuf := new(bytes.Buffer) err = server.indexTemplate.Execute(indexBuf, indexVars) if err != nil { http.Error(w, "Internal Server Error", 500) return } w.Write(indexBuf.Bytes()) } func (server *Server) handleManifest(w http.ResponseWriter, r *http.Request) { indexVars, err := server.indexVariables(r) if err != nil { http.Error(w, "Internal Server Error", 500) return } indexBuf := new(bytes.Buffer) err = server.manifestTemplate.Execute(indexBuf, indexVars) if err != nil { http.Error(w, "Internal Server Error", 500) return } w.Write(indexBuf.Bytes()) } func (server *Server) indexVariables(r *http.Request) (map[string]interface{}, error) { titleVars := server.titleVariables( []string{"server", "master"}, map[string]map[string]interface{}{ "server": server.options.TitleVariables, "master": map[string]interface{}{ "remote_addr": r.RemoteAddr, }, }, ) titleBuf := new(bytes.Buffer) err := server.titleTemplate.Execute(titleBuf, titleVars) if err != nil { return nil, err } indexVars := map[string]interface{}{ "title": titleBuf.String(), } return indexVars, err } func (server *Server) handleAuthToken(w http.ResponseWriter, r *http.Request) { w.Header().Set("Content-Type", "application/javascript") // @TODO hashing? w.Write([]byte("var gotty_auth_token = '" + server.options.Credential + "';")) } func (server *Server) handleConfig(w http.ResponseWriter, r *http.Request) { w.Header().Set("Content-Type", "application/javascript") w.Write([]byte("var gotty_term = 'xterm';")) } // titleVariables merges maps in a specified order. // varUnits are name-keyed maps, whose names will be iterated using order. func (server *Server) titleVariables(order []string, varUnits map[string]map[string]interface{}) map[string]interface{} { titleVars := map[string]interface{}{} for _, name := range order { vars, ok := varUnits[name] if !ok { panic("title variable name error") } for key, val := range vars { titleVars[key] = val } } // safe net for conflicted keys for _, name := range order { titleVars[name] = varUnits[name] } return titleVars }