all: replace some cases of strings.SplitN with strings.Cut (#28446)

p2p/nat/nat.go

@@ -61,12 +61,12 @@ type Interface interface {
 //	"pmp:192.168.0.1"    uses NAT-PMP with the given gateway address
 func Parse(spec string) (Interface, error) {
 	var (
-		parts = strings.SplitN(spec, ":", 2)
-		mech  = strings.ToLower(parts[0])
-		ip    net.IP
+		before, after, found = strings.Cut(spec, ":")
+		mech                 = strings.ToLower(before)
+		ip                   net.IP
 	)
-	if len(parts) > 1 {
-		ip = net.ParseIP(parts[1])
+	if found {
+		ip = net.ParseIP(after)
 		if ip == nil {
 			return nil, errors.New("invalid IP address")
 		}
@@ -86,7 +86,7 @@ func Parse(spec string) (Interface, error) {
 	case "pmp", "natpmp", "nat-pmp":
 		return PMP(ip), nil
 	default:
-		return nil, fmt.Errorf("unknown mechanism %q", parts[0])
+		return nil, fmt.Errorf("unknown mechanism %q", before)
 	}
 }
 

p2p/simulations/http.go

@@ -479,12 +479,12 @@ func (s *Server) StreamNetworkEvents(w http.ResponseWriter, req *http.Request) {
 func NewMsgFilters(filterParam string) (MsgFilters, error) {
 	filters := make(MsgFilters)
 	for _, filter := range strings.Split(filterParam, "-") {
-		protoCodes := strings.SplitN(filter, ":", 2)
-		if len(protoCodes) != 2 || protoCodes[0] == "" || protoCodes[1] == "" {
+		proto, codes, found := strings.Cut(filter, ":")
+		if !found || proto == "" || codes == "" {
 			return nil, fmt.Errorf("invalid message filter: %s", filter)
 		}
-		proto := protoCodes[0]
-		for _, code := range strings.Split(protoCodes[1], ",") {
+
+		for _, code := range strings.Split(codes, ",") {
 			if code == "*" || code == "-1" {
 				filters[MsgFilter{Proto: proto, Code: -1}] = struct{}{}
 				continue