do not crash if no tcp connections are desired

internet/definitions.go

@@ -42,7 +42,7 @@ type node struct {
 }
 
 var (
-	errZeroMaxNodes    = errors.New("zero max ports")
+	errZeroMaxNodesArg = errors.New("zero max nodes arg")
 	errZeroPort        = errors.New("port must be greater than zero")
 	errInvalidProto    = errors.New("invalid protocol")
 	errProtoRegistered = errors.New("protocol already registered")

internet/stack-ethernet.go

@@ -41,7 +41,7 @@ func (ls *StackEthernet) Reset6(mac, gateway [6]byte, mtu, maxNodes int) error {
 	if mtu > math.MaxUint16 || mtu < 256 {
 		return errors.New("invalid MTU")
 	} else if maxNodes <= 0 {
-		return errZeroMaxNodes
+		return errZeroMaxNodesArg
 	}
 	ls.handlers = slices.Grow(ls.handlers[:0], maxNodes)
 	*ls = StackEthernet{

internet/stack-ip.go

@@ -30,7 +30,7 @@ type StackIP struct {
 
 func (sb *StackIP) Reset(addr netip.Addr, maxNodes int) error {
 	if maxNodes <= 0 {
-		return errZeroMaxNodes
+		return errZeroMaxNodesArg
 	}
 	err := sb.SetAddr(addr)
 	if err != nil {

internet/stack-ports.go

@@ -28,7 +28,7 @@ func (ps *StackPorts) Reset(protocol uint64, dstPortOffset uint16, maxNodes int)
 	if protocol > math.MaxUint16 {
 		return errInvalidProto
 	} else if maxNodes <= 0 {
-		return errZeroMaxNodes
+		return errZeroMaxNodesArg
 	}
 	ps.handlers = slices.Grow(ps.handlers[:0], maxNodes)
 	*ps = StackPorts{

x/xnet/stack-async.go

@@ -123,14 +123,15 @@ func (s *StackAsync) Reset(cfg StackConfig) error {
 	}
 
 	// Enable TCP if connections present.
-
-	err = s.tcps.ResetTCP(cfg.MaxTCPConns)
-	if err != nil {
-		return err
-	}
-	err = s.ip.Register(&s.tcps)
-	if err != nil {
-		return err
+	if cfg.MaxTCPConns > 0 {
+		err = s.tcps.ResetTCP(cfg.MaxTCPConns)
+		if err != nil {
+			return err
+		}
+		err = s.ip.Register(&s.tcps)
+		if err != nil {
+			return err
+		}
 	}
 
 	// Now setup stacks.

x/xnet/stack-retrying.go

@@ -85,13 +85,19 @@ func (s StackRetrying) DoResolveHardwareAddress6(addr netip.Addr, timeout time.D
 
 func (s StackRetrying) DoDialTCP(conn *tcp.Conn, localPort uint16, addrp netip.AddrPort, timeout time.Duration, retries int) (err error) {
 	expectEnd := time.Now().Add(timeout * time.Duration(retries))
+	var firstErr error
 	for i := 0; i < retries; i++ {
 		err = s.block.DoDialTCP(conn, localPort, addrp, timeout)
 		if err == nil {
 			return nil
+		} else if firstErr == nil {
+			firstErr = err
 		}
 	}
 	if time.Now().Before(expectEnd) {
+		if err != firstErr {
+			return errors.Join(firstErr, err)
+		}
 		return err
 	}
 	return errRetriesExceeded