StackPorts: set MAC destination when node has MAC

internet/definitions.go

@@ -174,7 +174,7 @@ func (h *handlers) demuxByPort(buf []byte, offset int, port uint16) (*node, erro
 func (h *handlers) encapsulateAny(buf []byte, offsetIP, offsetThisFrame int) (_ *node, n int, err error) {
 	for i := range h.nodes {
 		node := &h.nodes[i]
-		if node.IsInvalid() {
+		if node.IsInvalid() || (len(node.remoteAddr) > 0 && isAllZeros(node.remoteAddr)) {
 			continue
 		}
 		n, err = node.encapsulate(buf, offsetIP, offsetThisFrame)
@@ -191,6 +191,15 @@ func (h *handlers) encapsulateAny(buf []byte, offsetIP, offsetThisFrame int) (_
 	return nil, 0, err // Return last written error.
 }
 
+func isAllZeros(b []byte) bool {
+	for i := range b {
+		if b[i] != 0 {
+			return false
+		}
+	}
+	return true
+}
+
 var (
 	errZeroMaxNodesArg = errors.New("zero max nodes arg")
 	errZeroPort        = errors.New("port must be greater than zero")
@@ -224,7 +233,7 @@ func nodeFromStackNode(s StackNode, port uint16, protocol uint64, remoteAddr []b
 		encapsulate: s.Encapsulate,
 		proto:       uint16(protocol),
 		port:        port,
-		remoteAddr:  append([]byte{}, remoteAddr...),
+		remoteAddr:  remoteAddr, // SHARED MEMORY- used to signal.
 	}
 }
 

internet/stack-ports.go

@@ -2,11 +2,13 @@ package internet
 
 import (
 	"encoding/binary"
+	"errors"
 	"io"
 	"math"
 	"strconv"
 
 	"github.com/soypat/lneto"
+	"github.com/soypat/lneto/ethernet"
 )
 
 type StackPorts struct {
@@ -50,7 +52,12 @@ func (ps *StackPorts) Encapsulate(carrierData []byte, offsetToIP, offsetToFrame
 	if int(ps.dstPortOff)+offsetToFrame+2 > len(carrierData) {
 		return 0, io.ErrShortBuffer
 	}
-	_, n, err = ps.handlers.encapsulateAny(carrierData, offsetToIP, offsetToFrame)
+	var node *node
+	node, n, err = ps.handlers.encapsulateAny(carrierData, offsetToIP, offsetToFrame)
+	if n > 0 && len(node.remoteAddr) == 6 && offsetToIP >= 14 {
+		efrm, _ := ethernet.NewFrame(carrierData[offsetToIP-14:])
+		*efrm.DestinationHardwareAddr() = [6]byte(node.remoteAddr)
+	}
 	return n, err
 }
 
@@ -63,13 +70,17 @@ func (ps *StackPorts) Demux(b []byte, offset int) (err error) {
 	return err
 }
 
-func (ps *StackPorts) Register(h StackNode) error {
+// Register registers a port StackNode on StackPorts.
+// If dstMAC is set to non-nil, length six buffer then
+func (ps *StackPorts) Register(h StackNode, dstMAC []byte) error {
 	port := h.LocalPort()
 	proto := h.Protocol()
 	if port <= 0 {
 		return errZeroPort
 	} else if proto != uint64(ps.protocol) {
 		return errInvalidProto
+	} else if dstMAC != nil && len(dstMAC) != 6 {
+		return errors.New("invalid MAC")
 	}
-	return ps.handlers.registerByPortProto(nodeFromStackNode(h, port, proto, nil))
+	return ps.handlers.registerByPortProto(nodeFromStackNode(h, port, proto, dstMAC))
 }