swarm/network/simulation: fix New function for-loop scope (#18161)

1 files changed, 7 insertions, 0 deletions

diff --git a/swarm/network/simulation/simulation.go b/swarm/network/simulation/simulation.go
index f6d3ce229..e5435b9f0 100644
--- a/swarm/network/simulation/simulation.go
+++ b/swarm/network/simulation/simulation.go
@@ -68,6 +68,10 @@ type ServiceFunc func(ctx *adapters.ServiceContext, bucket *sync.Map) (s node.Se
 
 // New creates a new Simulation instance with new
 // simulations.Network initialized with provided services.
+// Services map must have unique keys as service names and
+// every ServiceFunc must return a node.Service of the unique type.
+// This restriction is required by node.Node.Start() function
+// which is used to start node.Service returned by ServiceFunc.
 func New(services map[string]ServiceFunc) (s *Simulation) {
 	s = &Simulation{
 		buckets: make(map[enode.ID]*sync.Map),
@@ -76,6 +80,9 @@ func New(services map[string]ServiceFunc) (s *Simulation) {
 
 	adapterServices := make(map[string]adapters.ServiceFunc, len(services))
 	for name, serviceFunc := range services {
+		// Scope this variables correctly
+		// as they will be in the adapterServices[name] function accessed later.
+		name, serviceFunc := name, serviceFunc
 		s.serviceNames = append(s.serviceNames, name)
 		adapterServices[name] = func(ctx *adapters.ServiceContext) (node.Service, error) {
 			b := new(sync.Map)