neoneo-go/pkg/rpc/client/wsclient.go

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package client
import (
"context"
"encoding/json"
"errors"
"fmt"
"strconv"
"sync"
"time"
"github.com/gorilla/websocket"
"github.com/nspcc-dev/neo-go/pkg/core/block"
"github.com/nspcc-dev/neo-go/pkg/core/state"
"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/subscriptions"
"github.com/nspcc-dev/neo-go/pkg/util"
"go.uber.org/atomic"
)
// 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 it exposes some functionality
// that is only provided via websockets (like event subscription mechanism).
// WSClient is thread-safe and can be used from multiple goroutines to perform
// RPC requests.
type WSClient struct {
Client
// Notifications is a channel that is used to send events received from
// the 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{}
requests chan *request.Raw
shutdown chan struct{}
closeCalled atomic.Bool
closeErrLock sync.RWMutex
closeErr error
subscriptionsLock sync.RWMutex
subscriptions map[string]bool
respLock sync.RWMutex
respChannels map[uint64]chan *response.Raw
}
// Notification represents a server-generated notification for client subscriptions.
// Value can be one of block.Block, state.AppExecResult, subscriptions.NotificationEvent
// transaction.Transaction or subscriptions.NotaryRequestEvent 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 {
response.Raw
Method string `json:"method"`
RawParams []json.RawMessage `json:"params,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
)
// errConnClosedByUser is a WSClient error used iff the user calls (*WSClient).Close method by himself.
var errConnClosedByUser = errors.New("connection closed by user")
// 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`.
// You should call Init method to initialize the network magic the client is
// operating on.
func NewWS(ctx context.Context, endpoint string, opts Options) (*WSClient, error) {
dialer := websocket.Dialer{HandshakeTimeout: opts.DialTimeout}
ws, _, err := dialer.Dial(endpoint, nil)
if err != nil {
return nil, err
}
wsc := &WSClient{
Client: Client{},
Notifications: make(chan Notification),
ws: ws,
shutdown: make(chan struct{}),
done: make(chan struct{}),
closeCalled: *atomic.NewBool(false),
respChannels: make(map[uint64]chan *response.Raw),
requests: make(chan *request.Raw),
subscriptions: make(map[string]bool),
}
err = initClient(ctx, &wsc.Client, endpoint, opts)
if err != nil {
return nil, err
}
wsc.Client.cli = nil
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() {
if c.closeCalled.CAS(false, true) {
c.setCloseErr(errConnClosedByUser)
// Closing shutdown channel sends a 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 receive an 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 {
err := c.ws.SetReadDeadline(time.Now().Add(wsPongLimit))
if err != nil {
c.setCloseErr(fmt.Errorf("failed to set pong read deadline: %w", err))
}
return err
})
var connCloseErr error
readloop:
for {
rr := new(requestResponse)
err := c.ws.SetReadDeadline(time.Now().Add(wsPongLimit))
if err != nil {
connCloseErr = fmt.Errorf("failed to set response read deadline: %w", err)
break readloop
}
err = c.ws.ReadJSON(rr)
if err != nil {
// Timeout/connection loss/malformed response.
connCloseErr = fmt.Errorf("failed to read JSON response (timeout/connection loss/malformed response): %w", err)
break readloop
}
if rr.ID == nil && rr.Method != "" {
event, err := response.GetEventIDFromString(rr.Method)
if err != nil {
// Bad event received.
connCloseErr = fmt.Errorf("failed to perse event ID from string %s: %w", rr.Method, err)
break readloop
}
if event != response.MissedEventID && len(rr.RawParams) != 1 {
// Bad event received.
connCloseErr = fmt.Errorf("bad event received: %s / %d", event, len(rr.RawParams))
break readloop
}
var val interface{}
switch event {
case response.BlockEventID:
sr, err := c.StateRootInHeader()
if err != nil {
// Client is not initialized.
connCloseErr = fmt.Errorf("failed to fetch StateRootInHeader: %w", err)
break readloop
}
val = block.New(sr)
case response.TransactionEventID:
val = &transaction.Transaction{}
case response.NotificationEventID:
val = new(subscriptions.NotificationEvent)
case response.ExecutionEventID:
val = new(state.AppExecResult)
case response.NotaryRequestEventID:
val = new(subscriptions.NotaryRequestEvent)
case response.MissedEventID:
// No value.
default:
// Bad event received.
connCloseErr = fmt.Errorf("unknown event received: %d", event)
break readloop
}
if event != response.MissedEventID {
err = json.Unmarshal(rr.RawParams[0], val)
if err != nil {
// Bad event received.
connCloseErr = fmt.Errorf("failed to unmarshal event of type %s from JSON: %w", event, err)
break readloop
}
}
c.Notifications <- Notification{event, val}
} else if rr.ID != nil && (rr.Error != nil || rr.Result != nil) {
id, err := strconv.ParseUint(string(rr.ID), 10, 64)
if err != nil {
connCloseErr = fmt.Errorf("failed to retrieve response ID from string %s: %w", string(rr.ID), err)
break readloop // Malformed response (invalid response ID).
}
ch := c.getResponseChannel(id)
if ch == nil {
connCloseErr = fmt.Errorf("unknown response channel for response %d", id)
break readloop // Unknown response (unexpected response ID).
}
ch <- &rr.Raw
} else {
// Malformed response, neither valid request, nor valid response.
connCloseErr = fmt.Errorf("malformed response")
break readloop
}
}
if connCloseErr != nil {
c.setCloseErr(connCloseErr)
}
close(c.done)
c.respLock.Lock()
for _, ch := range c.respChannels {
close(ch)
}
c.respChannels = nil
c.respLock.Unlock()
close(c.Notifications)
}
func (c *WSClient) wsWriter() {
pingTicker := time.NewTicker(wsPingPeriod)
defer c.ws.Close()
defer pingTicker.Stop()
var connCloseErr error
writeloop:
for {
select {
case <-c.shutdown:
return
case <-c.done:
return
case req, ok := <-c.requests:
if !ok {
return
}
if err := c.ws.SetWriteDeadline(time.Now().Add(c.opts.RequestTimeout)); err != nil {
connCloseErr = fmt.Errorf("failed to set request write deadline: %w", err)
break writeloop
}
if err := c.ws.WriteJSON(req); err != nil {
connCloseErr = fmt.Errorf("failed to write JSON request (%s / %d): %w", req.Method, len(req.Params), err)
break writeloop
}
case <-pingTicker.C:
if err := c.ws.SetWriteDeadline(time.Now().Add(wsWriteLimit)); err != nil {
connCloseErr = fmt.Errorf("failed to set ping write deadline: %w", err)
break writeloop
}
if err := c.ws.WriteMessage(websocket.PingMessage, []byte{}); err != nil {
connCloseErr = fmt.Errorf("failed to write ping message: %w", err)
break writeloop
}
}
}
if connCloseErr != nil {
c.setCloseErr(connCloseErr)
}
}
func (c *WSClient) unregisterRespChannel(id uint64) {
c.respLock.Lock()
defer c.respLock.Unlock()
if ch, ok := c.respChannels[id]; ok {
delete(c.respChannels, id)
close(ch)
}
}
func (c *WSClient) getResponseChannel(id uint64) chan *response.Raw {
c.respLock.RLock()
defer c.respLock.RUnlock()
return c.respChannels[id]
}
func (c *WSClient) makeWsRequest(r *request.Raw) (*response.Raw, error) {
ch := make(chan *response.Raw)
c.respLock.Lock()
select {
case <-c.done:
c.respLock.Unlock()
return nil, errors.New("connection lost before registering response channel")
default:
c.respChannels[r.ID] = ch
c.respLock.Unlock()
}
select {
case <-c.done:
return nil, errors.New("connection lost before sending the request")
case c.requests <- r:
}
select {
case <-c.done:
return nil, errors.New("connection lost while waiting for the response")
case resp := <-ch:
c.unregisterRespChannel(r.ID)
return resp, nil
}
}
func (c *WSClient) performSubscription(params []interface{}) (string, error) {
var resp string
if err := c.performRequest("subscribe", params, &resp); err != nil {
return "", err
}
c.subscriptionsLock.Lock()
defer c.subscriptionsLock.Unlock()
c.subscriptions[resp] = true
return resp, nil
}
func (c *WSClient) performUnsubscription(id string) error {
var resp bool
c.subscriptionsLock.Lock()
defer c.subscriptionsLock.Unlock()
if !c.subscriptions[id] {
return errors.New("no subscription with this ID")
}
if err := c.performRequest("unsubscribe", []interface{}{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 the client. It can be filtered by primary consensus node index, nil value doesn't
// add any filters.
func (c *WSClient) SubscribeForNewBlocks(primary *int) (string, error) {
params := []interface{}{"block_added"}
if primary != nil {
params = append(params, request.BlockFilter{Primary: *primary})
}
return c.performSubscription(params)
}
// SubscribeForNewTransactions adds subscription for new transaction events to
// this instance of the client. It can be filtered by the sender and/or the signer, nil
// value is treated as missing filter.
func (c *WSClient) SubscribeForNewTransactions(sender *util.Uint160, signer *util.Uint160) (string, error) {
params := []interface{}{"transaction_added"}
if sender != nil || signer != nil {
params = append(params, request.TxFilter{Sender: sender, Signer: signer})
}
return c.performSubscription(params)
}
// SubscribeForExecutionNotifications adds subscription for notifications
// generated during transaction execution to this instance of the client. It can be
// filtered by the contract's hash (that emits notifications), nil value puts no such
// restrictions.
func (c *WSClient) SubscribeForExecutionNotifications(contract *util.Uint160, name *string) (string, error) {
params := []interface{}{"notification_from_execution"}
if contract != nil || name != nil {
params = append(params, 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 the client. It 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 := []interface{}{"transaction_executed"}
if state != nil {
if *state != "HALT" && *state != "FAULT" {
return "", errors.New("bad state parameter")
}
params = append(params, request.ExecutionFilter{State: *state})
}
return c.performSubscription(params)
}
// SubscribeForNotaryRequests adds subscription for notary request payloads
// addition or removal events to this instance of client. It can be filtered by
// request sender's hash, or main tx signer's hash, nil value puts no such
// restrictions.
func (c *WSClient) SubscribeForNotaryRequests(sender *util.Uint160, mainSigner *util.Uint160) (string, error) {
params := []interface{}{"notary_request_event"}
if sender != nil {
params = append(params, request.TxFilter{Sender: sender, Signer: mainSigner})
}
return c.performSubscription(params)
}
// Unsubscribe removes subscription for the given event stream.
func (c *WSClient) Unsubscribe(id string) error {
return c.performUnsubscription(id)
}
// UnsubscribeAll removes all active subscriptions of the current client.
func (c *WSClient) UnsubscribeAll() error {
c.subscriptionsLock.Lock()
defer c.subscriptionsLock.Unlock()
for id := range c.subscriptions {
var resp bool
if err := c.performRequest("unsubscribe", []interface{}{id}, &resp); err != nil {
return err
}
if !resp {
return errors.New("unsubscribe method returned false result")
}
delete(c.subscriptions, id)
}
return nil
}
// setCloseErr is a thread-safe method setting closeErr in case if it's not yet set.
func (c *WSClient) setCloseErr(err error) {
c.closeErrLock.Lock()
defer c.closeErrLock.Unlock()
if c.closeErr == nil {
c.closeErr = err
}
}
// GetError returns the reason of WS connection closing. It returns nil in case if connection
// was closed by the use via Close() method calling.
func (c *WSClient) GetError() error {
c.closeErrLock.RLock()
defer c.closeErrLock.RUnlock()
if c.closeErr != nil && errors.Is(c.closeErr, errConnClosedByUser) {
return nil
}
return c.closeErr
}