rpc: protect supscriptions of RPC WSClient from concurrent access

pkg/rpc/client/wsclient.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"sync"
 	"time"
 
 	"github.com/gorilla/websocket"
@@ -30,12 +31,14 @@ type WSClient struct {
 	// 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
+	ws        *websocket.Conn
+	done      chan struct{}
+	responses chan *response.Raw
+	requests  chan *request.Raw
+	shutdown  chan struct{}
+
+	subscriptionsLock sync.RWMutex
+	subscriptions     map[string]bool
 }
 
 // Notification represents server-generated notification for client subscriptions.
@@ -237,6 +240,10 @@ func (c *WSClient) performSubscription(params request.RawParams) (string, error)
 	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
 }
@@ -244,6 +251,9 @@ func (c *WSClient) performSubscription(params request.RawParams) (string, error)
 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")
 	}
@@ -325,11 +335,18 @@ func (c *WSClient) Unsubscribe(id string) error {
 
 // UnsubscribeAll removes all active subscriptions of current client.
 func (c *WSClient) UnsubscribeAll() error {
+	c.subscriptionsLock.Lock()
+	defer c.subscriptionsLock.Unlock()
+
 	for id := range c.subscriptions {
-		err := c.performUnsubscription(id)
-		if err != nil {
+		var resp bool
+		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
 }