StackPorts: set MAC destination when node has MAC

examples/bridge/main.go

@@ -359,7 +359,7 @@ func (s *Stack) StartLookupIP(host string) error {
 	var u internet.StackUDPPort
 	dns4 := dnsSrvs.As4()
 	u.SetStackNode(&s.dns, dns4[:], dns.ServerPort)
-	err = s.udps.Register(&u)
+	err = s.udps.Register(&u, nil)
 	if err != nil {
 		return err
 	}
@@ -405,7 +405,7 @@ func (s *Stack) BeginDHCPRequest(request [4]byte) error {
 	}
 	var u internet.StackUDPPort
 	u.SetStackNode(&s.dhcp, nil, dhcpv4.DefaultServerPort)
-	err = s.udps.Register(&u)
+	err = s.udps.Register(&u, nil)
 	if err != nil {
 		return err
 	}
@@ -417,7 +417,7 @@ func (s *Stack) StartNTP(addr netip.Addr) error {
 	var u internet.StackUDPPort
 	addr4 := addr.As4()
 	u.SetStackNode(&s.ntp, addr4[:], ntp.ServerPort)
-	err := s.udps.Register(&u)
+	err := s.udps.Register(&u, nil)
 	return err
 }
 

examples/stack/main.go

@@ -239,7 +239,7 @@ func (stack *Stack) OpenTCPListener(port uint16) (*internet.NodeTCPListener, err
 	if err != nil {
 		return nil, err
 	}
-	err = stack.tcpports.Register(&listener)
+	err = stack.tcpports.Register(&listener, nil) // Passive TCP requires no MAC setting.
 	if err != nil {
 		return nil, err
 	}
@@ -261,7 +261,7 @@ func (stack *Stack) OpenPassiveTCP(port uint16, iss tcp.Value) (*tcp.Conn, error
 	if err != nil {
 		return nil, err
 	}
-	err = stack.tcpports.Register(conn)
+	err = stack.tcpports.Register(conn, nil) // Passive MAC with no listening.
 	if err != nil {
 		return nil, err
 	}

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))
 }

x/xnet/stack-async.go

@@ -234,11 +234,23 @@ func (s *StackAsync) Gateway6() [6]byte {
 func (s *StackAsync) DialTCP(conn *tcp.Conn, localPort uint16, addrp netip.AddrPort) (err error) {
 	s.mu.Lock()
 	defer s.mu.Unlock()
+	var mac []byte
+	if s.dhcpResults.Subnet.Contains(addrp.Addr()) {
+		mac = make([]byte, 6)
+		ip := addrp.Addr().As4()
+		// StartQuery starts an ARP query for addresses in this network.
+		// On finishing query MAC is set and thus the StackPort will allow encapsulating
+		// data on that connection.
+		err = s.arp.StartQuery(mac, ip[:])
+		if err != nil {
+			return err
+		}
+	}
 	err = conn.OpenActive(localPort, addrp, tcp.Value(s.Prand32()))
 	if err != nil {
 		return err
 	}
-	err = s.tcps.Register(conn)
+	err = s.tcps.Register(conn, mac) // MAC is set later on by ARP response arriving to our network.
 	if err != nil {
 		conn.Abort()
 		return err
@@ -253,7 +265,7 @@ func (s *StackAsync) ListenTCP(conn *tcp.Conn, localPort uint16) (err error) {
 	if err != nil {
 		return err
 	}
-	err = s.tcps.Register(conn)
+	err = s.tcps.Register(conn, nil)
 	if err != nil {
 		conn.Abort()
 		return err
@@ -294,7 +306,7 @@ func (s *StackAsync) StartLookupIP(host string) error {
 	}
 	dns4 := s.dnssv.As4()
 	s.dnsUDP.SetStackNode(&s.dns, dns4[:], dns.ServerPort)
-	err = s.udps.Register(&s.dnsUDP)
+	err = s.udps.Register(&s.dnsUDP, nil)
 	return err
 }
 
@@ -341,7 +353,7 @@ func (s *StackAsync) StartDHCPv4Request(request [4]byte) error {
 	}
 
 	s.dhcpUDP.SetStackNode(&s.dhcp, nil, dhcpv4.DefaultServerPort)
-	err = s.udps.Register(&s.dhcpUDP)
+	err = s.udps.Register(&s.dhcpUDP, nil)
 	if err != nil {
 		return err
 	}
@@ -355,7 +367,7 @@ func (s *StackAsync) StartNTP(addr netip.Addr) error {
 
 	addr4 := addr.As4()
 	s.ntpUDP.SetStackNode(&s.ntp, addr4[:], ntp.ServerPort)
-	err := s.udps.Register(&s.ntpUDP)
+	err := s.udps.Register(&s.ntpUDP, nil)
 	return err
 }