package client import ( "context" "encoding/json" "errors" "time" "github.com/gorilla/websocket" "github.com/nspcc-dev/neo-go/pkg/core/block" "github.com/nspcc-dev/neo-go/pkg/core/transaction" "github.com/nspcc-dev/neo-go/pkg/rpc/request" "github.com/nspcc-dev/neo-go/pkg/rpc/response" "github.com/nspcc-dev/neo-go/pkg/rpc/response/result" "github.com/nspcc-dev/neo-go/pkg/util" ) // WSClient is a websocket-enabled RPC client that can be used with appropriate // servers. It's supposed to be faster than Client because it has persistent // connection to the server and at the same time is exposes some functionality // that is only provided via websockets (like event subscription mechanism). type WSClient struct { Client // Notifications is a channel that is used to send events received from // server. Client's code is supposed to be reading from this channel if // it wants to use subscription mechanism, failing to do so will cause // WSClient to block even regular requests. This channel is not buffered. // In case of protocol error or upon connection closure this channel will // be closed, so make sure to handle this. Notifications chan Notification ws *websocket.Conn done chan struct{} responses chan *response.Raw requests chan *request.Raw shutdown chan struct{} subscriptions map[string]bool } // Notification represents server-generated notification for client subscriptions. // Value can be one of block.Block, result.ApplicationLog, result.NotificationEvent // or transaction.Transaction based on Type. type Notification struct { Type response.EventID Value interface{} } // requestResponse is a combined type for request and response since we can get // any of them here. type requestResponse struct { request.In Error *response.Error `json:"error,omitempty"` Result json.RawMessage `json:"result,omitempty"` } const ( // Message limit for receiving side. wsReadLimit = 10 * 1024 * 1024 // Disconnection timeout. wsPongLimit = 60 * time.Second // Ping period for connection liveness check. wsPingPeriod = wsPongLimit / 2 // Write deadline. wsWriteLimit = wsPingPeriod / 2 ) // NewWS returns a new WSClient ready to use (with established websocket // connection). You need to use websocket URL for it like `ws://1.2.3.4/ws`. func NewWS(ctx context.Context, endpoint string, opts Options) (*WSClient, error) { cl, err := New(ctx, endpoint, opts) if err != nil { return nil, err } cl.cli = nil dialer := websocket.Dialer{HandshakeTimeout: opts.DialTimeout} ws, _, err := dialer.Dial(endpoint, nil) if err != nil { return nil, err } wsc := &WSClient{ Client: *cl, Notifications: make(chan Notification), ws: ws, shutdown: make(chan struct{}), done: make(chan struct{}), responses: make(chan *response.Raw), requests: make(chan *request.Raw), subscriptions: make(map[string]bool), } go wsc.wsReader() go wsc.wsWriter() wsc.requestF = wsc.makeWsRequest return wsc, nil } // Close closes connection to the remote side rendering this client instance // unusable. func (c *WSClient) Close() { // Closing shutdown channel send signal to wsWriter to break out of the // loop. In doing so it does ws.Close() closing the network connection // which in turn makes wsReader receieve err from ws,ReadJSON() and also // break out of the loop closing c.done channel in its shutdown sequence. close(c.shutdown) <-c.done } func (c *WSClient) wsReader() { c.ws.SetReadLimit(wsReadLimit) c.ws.SetPongHandler(func(string) error { c.ws.SetReadDeadline(time.Now().Add(wsPongLimit)); return nil }) readloop: for { rr := new(requestResponse) c.ws.SetReadDeadline(time.Now().Add(wsPongLimit)) err := c.ws.ReadJSON(rr) if err != nil { // Timeout/connection loss/malformed response. break } if rr.RawID == nil && rr.Method != "" { event, err := response.GetEventIDFromString(rr.Method) if err != nil { // Bad event received. break } var slice []json.RawMessage err = json.Unmarshal(rr.RawParams, &slice) if err != nil || (event != response.MissedEventID && len(slice) != 1) { // Bad event received. break } var val interface{} switch event { case response.BlockEventID: val = block.New(c.opts.Network) case response.TransactionEventID: val = &transaction.Transaction{Network: c.opts.Network} case response.NotificationEventID: val = new(result.NotificationEvent) case response.ExecutionEventID: val = new(result.ApplicationLog) case response.MissedEventID: // No value. default: // Bad event received. break readloop } if event != response.MissedEventID { err = json.Unmarshal(slice[0], val) if err != nil { // Bad event received. break } } c.Notifications <- Notification{event, val} } else if rr.RawID != nil && (rr.Error != nil || rr.Result != nil) { resp := new(response.Raw) resp.ID = rr.RawID resp.JSONRPC = rr.JSONRPC resp.Error = rr.Error resp.Result = rr.Result c.responses <- resp } else { // Malformed response, neither valid request, nor valid response. break } } close(c.done) close(c.responses) close(c.Notifications) } func (c *WSClient) wsWriter() { pingTicker := time.NewTicker(wsPingPeriod) defer c.ws.Close() defer pingTicker.Stop() for { select { case <-c.shutdown: return case <-c.done: return case req, ok := <-c.requests: if !ok { return } c.ws.SetWriteDeadline(time.Now().Add(c.opts.RequestTimeout)) if err := c.ws.WriteJSON(req); err != nil { return } case <-pingTicker.C: c.ws.SetWriteDeadline(time.Now().Add(wsWriteLimit)) if err := c.ws.WriteMessage(websocket.PingMessage, []byte{}); err != nil { return } } } } func (c *WSClient) makeWsRequest(r *request.Raw) (*response.Raw, error) { select { case <-c.done: return nil, errors.New("connection lost") case c.requests <- r: } select { case <-c.done: return nil, errors.New("connection lost") case resp := <-c.responses: return resp, nil } } func (c *WSClient) performSubscription(params request.RawParams) (string, error) { var resp string if err := c.performRequest("subscribe", params, &resp); err != nil { return "", err } c.subscriptions[resp] = true return resp, nil } func (c *WSClient) performUnsubscription(id string) error { var resp bool if !c.subscriptions[id] { return errors.New("no subscription with this ID") } if err := c.performRequest("unsubscribe", request.NewRawParams(id), &resp); err != nil { return err } if !resp { return errors.New("unsubscribe method returned false result") } delete(c.subscriptions, id) return nil } // SubscribeForNewBlocks adds subscription for new block events to this instance // of client. It can filtered by primary consensus node index, nil value doesn't // add any filters. func (c *WSClient) SubscribeForNewBlocks(primary *int) (string, error) { params := request.NewRawParams("block_added") if primary != nil { params.Values = append(params.Values, request.BlockFilter{Primary: *primary}) } return c.performSubscription(params) } // SubscribeForNewTransactions adds subscription for new transaction events to // this instance of client. It can be filtered by sender and/or signer, nil // value is treated as missing filter. func (c *WSClient) SubscribeForNewTransactions(sender *util.Uint160, signer *util.Uint160) (string, error) { params := request.NewRawParams("transaction_added") if sender != nil || signer != nil { params.Values = append(params.Values, request.TxFilter{Sender: sender, Signer: signer}) } return c.performSubscription(params) } // SubscribeForExecutionNotifications adds subscription for notifications // generated during transaction execution to this instance of client. It can be // filtered by contract's hash (that emits notifications), nil value puts no such // restrictions. func (c *WSClient) SubscribeForExecutionNotifications(contract *util.Uint160, name *string) (string, error) { params := request.NewRawParams("notification_from_execution") if contract != nil || name != nil { params.Values = append(params.Values, request.NotificationFilter{Contract: contract, Name: name}) } return c.performSubscription(params) } // SubscribeForTransactionExecutions adds subscription for application execution // results generated during transaction execution to this instance of client. Can // be filtered by state (HALT/FAULT) to check for successful or failing // transactions, nil value means no filtering. func (c *WSClient) SubscribeForTransactionExecutions(state *string) (string, error) { params := request.NewRawParams("transaction_executed") if state != nil { if *state != "HALT" && *state != "FAULT" { return "", errors.New("bad state parameter") } params.Values = append(params.Values, request.ExecutionFilter{State: *state}) } return c.performSubscription(params) } // Unsubscribe removes subscription for given event stream. func (c *WSClient) Unsubscribe(id string) error { return c.performUnsubscription(id) } // UnsubscribeAll removes all active subscriptions of current client. func (c *WSClient) UnsubscribeAll() error { for id := range c.subscriptions { err := c.performUnsubscription(id) if err != nil { return err } } return nil }