Merge pull request #306 from bloXroute-Labs/fix-subscription-panic

Fix race condition that leads to panic

Author: HealthyBuilder

rpc/ws/client.go

@@ -254,10 +254,11 @@ func (c *Client) handleSubscriptionMessage(subID uint64, message []byte) {
 		return
 	}
 
+	sub.mutex.Lock()
+	defer sub.mutex.Unlock()
 	if !sub.closed {
 		sub.stream <- result
 	}
-	return
 }
 
 func (c *Client) closeAllSubscription(err error) {

rpc/ws/subscription.go

@@ -17,14 +17,18 @@
 
 package ws
 
-import "context"
+import (
+	"context"
+	"sync"
+)
 
 type Subscription struct {
 	req               *request
 	subID             uint64
 	stream            chan result
 	err               chan error
 	closeFunc         func(err error)
+	mutex             sync.Mutex
 	closed            bool
 	unsubscribeMethod string
 	decoderFunc       decoderFunc
@@ -65,6 +69,8 @@ func (s *Subscription) Unsubscribe() {
 }
 
 func (s *Subscription) unsubscribe(err error) {
+	s.mutex.Lock()
+	defer s.mutex.Unlock()
 	s.closeFunc(err)
 	s.closed = true
 	close(s.stream)