major ARP Handler refactor; DNS improvements; bridge example rework

arp/handler.go

@@ -9,13 +9,13 @@ import (
 )
 
 type Handler struct {
-	connID       uint64
-	ourHWAddr    []byte
-	ourProtoAddr []byte
-	htype        uint16
-	protoType    ethernet.Type
-	pending      [][sizeHeaderv6]byte
-	queries      []queryResult
+	connID          uint64
+	ourHWAddr       []byte
+	ourProtoAddr    []byte
+	htype           uint16
+	protoType       ethernet.Type
+	pendingResponse [][sizeHeaderv6]byte
+	queries         []queryResult
 }
 
 type HandlerConfig struct {
@@ -27,29 +27,35 @@ type HandlerConfig struct {
 	ProtocolType ethernet.Type
 }
 
-func (c *Handler) Reset(cfg HandlerConfig) error {
+func (h *Handler) LocalPort() uint16 { return 0 }
+
+func (h *Handler) Protocol() uint64 { return uint64(ethernet.TypeARP) }
+
+func (h *Handler) ConnectionID() *uint64 { return &h.connID }
+
+func (h *Handler) Reset(cfg HandlerConfig) error {
 	if len(cfg.HardwareAddr) == 0 || len(cfg.HardwareAddr) > 255 ||
 		len(cfg.ProtocolAddr) == 0 || len(cfg.ProtocolAddr) > 255 {
 		return errors.New("invalid Handler address config")
 	} else if cfg.MaxQueries <= 0 || cfg.MaxPending <= 0 {
 		return errors.New("invalid Handler query or pending config")
 	}
-	*c = Handler{
-		connID:       c.connID + 1,
-		ourHWAddr:    c.ourHWAddr[:0],
-		ourProtoAddr: c.ourProtoAddr[:0],
-		htype:        cfg.HardwareType,
-		protoType:    cfg.ProtocolType,
-		pending:      c.pending[:0],
-		queries:      c.queries[:0],
+	*h = Handler{
+		connID:          h.connID + 1,
+		ourHWAddr:       h.ourHWAddr[:0],
+		ourProtoAddr:    h.ourProtoAddr[:0],
+		htype:           cfg.HardwareType,
+		protoType:       cfg.ProtocolType,
+		pendingResponse: h.pendingResponse[:0],
+		queries:         h.queries[:0],
 	}
-	c.ourHWAddr = append(c.ourHWAddr, cfg.HardwareAddr...)
-	c.ourProtoAddr = append(c.ourProtoAddr, cfg.ProtocolAddr...)
-	if cap(c.pending) < cfg.MaxPending {
-		c.pending = make([][52]byte, cfg.MaxPending)[:0]
+	h.ourHWAddr = append(h.ourHWAddr, cfg.HardwareAddr...)
+	h.ourProtoAddr = append(h.ourProtoAddr, cfg.ProtocolAddr...)
+	if cap(h.pendingResponse) < cfg.MaxPending {
+		h.pendingResponse = make([][52]byte, cfg.MaxPending)[:0]
 	}
-	if cap(c.queries) < cfg.MaxQueries {
-		c.queries = make([]queryResult, cfg.MaxQueries)[:0]
+	if cap(h.queries) < cfg.MaxQueries {
+		h.queries = make([]queryResult, cfg.MaxQueries)[:0]
 	}
 	return nil
 }
@@ -61,88 +67,91 @@ type queryResult struct {
 }
 
 // AbortPending drops pending queries and incoming requests.
-func (c *Handler) AbortPending() {
-	c.pending = c.pending[:0]
-	c.queries = c.queries[:0]
+func (h *Handler) AbortPending() {
+	h.pendingResponse = h.pendingResponse[:0]
+	h.queries = h.queries[:0]
 }
 
-func (c *Handler) expectSize() int {
-	return sizeHeader + 2*len(c.ourHWAddr) + 2*len(c.ourProtoAddr)
+func (h *Handler) expectSize() int {
+	return sizeHeader + 2*len(h.ourHWAddr) + 2*len(h.ourProtoAddr)
 }
 
-func (c *Handler) ConnectionID() *uint64 {
-	return &c.connID
-}
-
-func (c *Handler) QueryResult(protoAddr []byte) (hwAddr []byte, err error) {
-	for i := range c.queries {
-		if bytes.Equal(protoAddr, c.queries[i].protoaddr) {
-			if !c.queries[i].querysent {
+func (h *Handler) QueryResult(protoAddr []byte) (hwAddr []byte, err error) {
+	for i := range h.queries {
+		if bytes.Equal(protoAddr, h.queries[i].protoaddr) {
+			if !h.queries[i].querysent {
 				return nil, errors.New("query not yet sent")
-			} else if len(c.queries[i].hwaddr) == 0 {
+			} else if len(h.queries[i].hwaddr) == 0 {
 				return nil, errors.New("no response yet")
 			}
-			return c.queries[i].hwaddr, nil
+			return h.queries[i].hwaddr, nil
 		}
 	}
 	return nil, errors.New("query not exist or dropped")
 }
 
-func (c *Handler) StartQuery(proto []byte) error {
-	if len(proto) != len(c.ourProtoAddr) {
+func (h *Handler) StartQuery(proto []byte) error {
+	if len(proto) != len(h.ourProtoAddr) {
 		return errors.New("bad protocol address length")
-	} else if len(c.queries) == cap(c.queries) {
+	} else if len(h.queries) == cap(h.queries) {
 		return errors.New("too many ongoing queries")
 	}
-	c.queries = c.queries[:len(c.queries)+1]
-	q := &c.queries[len(c.queries)-1]
+	h.queries = h.queries[:len(h.queries)+1]
+	q := &h.queries[len(h.queries)-1]
 	q.hwaddr = q.hwaddr[:0]
 	q.querysent = false
 	q.protoaddr = append(q.protoaddr[:0], proto...)
 	return nil
 }
 
-func (c *Handler) Send(b []byte) (int, error) {
-	n := c.expectSize()
+func (h *Handler) Encapsulate(eth []byte, frameOffset int) (int, error) {
+	b := eth[frameOffset:]
+	n := h.expectSize()
 	if len(b) < n {
 		return 0, errShortARP
 	}
-	if len(c.pending) > 0 {
+	if len(h.pendingResponse) > 0 {
 		// pop frame.
-		afrm, _ := NewFrame(c.pending[len(c.pending)-1][:])
-		c.pending = c.pending[:len(c.pending)-1]
+		afrm, _ := NewFrame(h.pendingResponse[len(h.pendingResponse)-1][:])
+		h.pendingResponse = h.pendingResponse[:len(h.pendingResponse)-1]
 		afrm.SetOperation(OpReply)
 		afrm.SwapTargetSender()
 		hwsender, _ := afrm.Sender()
-		copy(hwsender, c.ourHWAddr)
+		copy(hwsender, h.ourHWAddr)
 		n := copy(b, afrm.Clip().RawData())
+		tgt, _ := afrm.Target()
+		trySetEthernetDst(eth[:frameOffset], tgt)
 		return n, nil
 	}
-	for i := range c.queries {
-		if !c.queries[i].querysent {
-			c.queries[i].querysent = true
+	for i := range h.queries {
+		if !h.queries[i].querysent {
+			h.queries[i].querysent = true
 			afrm, _ := NewFrame(b)
-			afrm.SetHardware(c.htype, uint8(len(c.ourHWAddr)))
-			afrm.SetProtocol(c.protoType, uint8(len(c.ourProtoAddr)))
+			afrm.SetHardware(h.htype, uint8(len(h.ourHWAddr)))
+			afrm.SetProtocol(h.protoType, uint8(len(h.ourProtoAddr)))
 			afrm.SetOperation(OpRequest)
 			hwSender, protoSender := afrm.Sender()
-			copy(hwSender, c.ourHWAddr)
-			copy(protoSender, c.ourProtoAddr)
+			copy(hwSender, h.ourHWAddr)
+			copy(protoSender, h.ourProtoAddr)
 			hwTarget, protoTarget := afrm.Target()
-			copy(protoTarget, c.queries[i].protoaddr)
+			copy(protoTarget, h.queries[i].protoaddr)
 			for j := range hwTarget {
 				hwTarget[j] = 0
 			}
+			broadcast := ethernet.BroadcastAddr()
+			trySetEthernetDst(eth[:frameOffset], broadcast[:])
 			return n, nil
 		}
 	}
 	return 0, nil
 }
 
-func (c *Handler) Recv(b []byte) error {
-	if len(c.pending) == cap(c.pending) {
+func (h *Handler) Demux(ethFrame []byte, frameOffset int) error {
+	if len(h.pendingResponse) == cap(h.pendingResponse) {
 		return errARPBufferFull
 	}
+
+	b := ethFrame[frameOffset:]
 	afrm, err := NewFrame(b)
 	if err != nil {
 		return err
@@ -153,27 +162,27 @@ func (c *Handler) Recv(b []byte) error {
 		return vld.ErrPop()
 	}
 	htype, hlen := afrm.Hardware()
-	if htype != c.htype || int(hlen) != len(c.ourHWAddr) {
+	if htype != h.htype || int(hlen) != len(h.ourHWAddr) {
 		return errors.New("bad ARP hardware")
 	}
 	protoType, protoLen := afrm.Protocol()
-	if protoType != c.protoType || int(protoLen) != len(c.ourProtoAddr) {
+	if protoType != h.protoType || int(protoLen) != len(h.ourProtoAddr) {
 		return errors.New("bad ARP proto")
 	}
 	switch afrm.Operation() {
 	case OpRequest:
 		_, protoaddr := afrm.Target()
-		if !bytes.Equal(protoaddr, c.ourProtoAddr) {
+		if !bytes.Equal(protoaddr, h.ourProtoAddr) {
 			return nil // Not for us.
 		}
-		c.pending = c.pending[:len(c.pending)+1]       // Extend pending buffer.
-		copy(c.pending[len(c.pending)-1][:], afrm.buf) // Set pending buffer.
+		h.pendingResponse = h.pendingResponse[:len(h.pendingResponse)+1] // Extend pending buffer.
+		copy(h.pendingResponse[len(h.pendingResponse)-1][:], afrm.buf)   // Set pending buffer.
 
 	case OpReply:
 		hwaddr, protoaddr := afrm.Sender()
-		for i := range c.queries {
-			if len(c.queries[i].hwaddr) == 0 && bytes.Equal(c.queries[i].protoaddr, protoaddr) {
-				c.queries[i].hwaddr = append(c.queries[i].hwaddr[:0], hwaddr...)
+		for i := range h.queries {
+			if len(h.queries[i].hwaddr) == 0 && bytes.Equal(h.queries[i].protoaddr, protoaddr) {
+				h.queries[i].hwaddr = append(h.queries[i].hwaddr[:0], hwaddr...)
 				return nil
 			}
 		}
@@ -183,3 +192,9 @@ func (c *Handler) Recv(b []byte) error {
 	}
 	return nil
 }
+
+func trySetEthernetDst(ethFrame []byte, dst []byte) {
+	if len(ethFrame) > 14 {
+		copy(ethFrame[:6], dst)
+	}
+}

arp/handler_test.go

@@ -34,13 +34,13 @@ func TestHandler(t *testing.T) {
 		t.Fatal(err)
 	}
 	var buf, discard [64]byte
-	n, err := c1.Send(buf[:])
+	n, err := c1.Encapsulate(buf[:], 0)
 	if err != nil {
 		t.Fatal("error on should be nop send:", err)
 	} else if n > 0 {
 		t.Fatal("should not send if no query")
 	}
-	n, err = c2.Send(buf[:])
+	n, err = c2.Encapsulate(buf[:], 0)
 	if err != nil {
 		t.Fatal("error on should be nop send:", err)
 	} else if n > 0 {
@@ -54,33 +54,33 @@ func TestHandler(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	n, err = c1.Send(buf[:]) // Send Request.
+	n, err = c1.Encapsulate(buf[:], 0) // Send Request.
 	if err != nil {
 		t.Fatal(err)
 	} else if n == 0 {
 		t.Fatal("expected send of data after first query")
 	}
 	validateARP(t, buf[:])
-	err = c2.Recv(buf[:n]) // Receive request.
+	err = c2.Demux(buf[:n], 0) // Receive request.
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	n, err = c2.Send(buf[:]) //  Send response.
+	n, err = c2.Encapsulate(buf[:], 0) //  Send response.
 	if err != nil {
 		t.Fatal(err)
 	} else if n == 0 {
 		t.Fatal("got no response to request")
 	}
 	validateARP(t, buf[:])
-	n, err = c2.Send(discard[:]) // Double tap check, should send nothing.
+	n, err = c2.Encapsulate(discard[:], 0) // Double tap check, should send nothing.
 	if err != nil {
 		t.Fatal("double tap send error:", err)
 	} else if n > 0 {
 		t.Fatal("wanted no data sent after response sent")
 	}
 
-	err = c1.Recv(buf[:]) // Receive response.
+	err = c1.Demux(buf[:], 0) // Receive response.
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -90,13 +90,13 @@ func TestHandler(t *testing.T) {
 	} else if !bytes.Equal(hwaddr, expectHWAddr) {
 		log.Fatalf("expected to get hwaddr %x!=%x", hwaddr, expectHWAddr)
 	}
-	n, err = c1.Send(buf[:])
+	n, err = c1.Encapsulate(buf[:], 0)
 	if err != nil {
 		t.Fatal(err)
 	} else if n > 0 {
 		t.Fatal("expected no data")
 	}
-	n, err = c2.Send(buf[:])
+	n, err = c2.Encapsulate(buf[:], 0)
 	if err != nil {
 		t.Fatal(err)
 	} else if n > 0 {

dhcpv4/client.go

@@ -8,6 +8,7 @@ import (
 	"math"
 	"math/bits"
 	"net"
+	"net/netip"
 
 	"github.com/soypat/lneto"
 	"github.com/soypat/lneto/ipv4"
@@ -17,7 +18,7 @@ type Client struct {
 	connID      uint64
 	reqHostname string
 	hostname    []byte
-	dns         [][4]byte
+	dns         []netip.Addr
 
 	svIPtos    ipv4.ToS
 	tRenew     uint32
@@ -253,7 +254,7 @@ func (c *Client) setOptions(frm Frame) error {
 				return nil // No DNS parsing if already got in previous exchange.
 			}
 			for i := 0; i < len(data); i += 4 {
-				c.dns = append(c.dns, [4]byte(data[i:i+4]))
+				c.dns = append(c.dns, netip.AddrFrom4([4]byte(data[i:i+4])))
 			}
 		}
 		return nil
@@ -301,16 +302,22 @@ func (c *Client) reset(xid uint32) {
 
 func (d *Client) State() ClientState { return d.state }
 
-func (d *Client) BroadcastAddr() [4]byte                   { return d.broadcast }
-func (d *Client) AssignedAddr() [4]byte                    { return d.offer }
-func (d *Client) ServerAddr() [4]byte                      { return d.svip }
-func (d *Client) RouterAddr() [4]byte                      { return d.router }
-func (d *Client) GatewayAddr() [4]byte                     { return d.gateway }
-func (d *Client) RebindingSeconds() uint32                 { return d.tRebind }
-func (d *Client) RenewalSeconds() uint32                   { return d.tRenew }
-func (d *Client) IPLeaseSeconds() uint32                   { return d.tIPLease }
-func (d *Client) AppendDNSServers(dst [][4]byte) [][4]byte { return append(dst, d.dns...) }
-
+func (d *Client) BroadcastAddr() [4]byte                         { return d.broadcast }
+func (d *Client) AssignedAddr() [4]byte                          { return d.offer }
+func (d *Client) ServerAddr() [4]byte                            { return d.svip }
+func (d *Client) RouterAddr() [4]byte                            { return d.router }
+func (d *Client) GatewayAddr() [4]byte                           { return d.gateway }
+func (d *Client) RebindingSeconds() uint32                       { return d.tRebind }
+func (d *Client) RenewalSeconds() uint32                         { return d.tRenew }
+func (d *Client) IPLeaseSeconds() uint32                         { return d.tIPLease }
+func (d *Client) AppendDNSServers(dst []netip.Addr) []netip.Addr { return append(dst, d.dns...) }
+func (d *Client) NumDNSServers() int                             { return len(d.dns) }
+func (d *Client) DNSServerFirst() netip.Addr {
+	if len(d.dns) < 1 {
+		return netip.Addr{}
+	}
+	return d.dns[0]
+}
 func (d *Client) CIDRBits() uint8 {
 	if d.subnet == [4]byte{} {
 		return 0

dns/client.go

@@ -2,11 +2,11 @@ package dns
 
 import (
 	"errors"
+	"fmt"
 	"math"
 	"net"
 
 	"github.com/soypat/lneto"
-	"github.com/soypat/lneto/internal"
 )
 
 type Client struct {
@@ -29,12 +29,12 @@ func (sudp *Client) LocalPort() uint16 { return ClientPort }
 
 func (sudp *Client) ConnectionID() *uint64 { return &sudp.connID }
 
-func (c *Client) StartResolve(cfg ResolveConfig) error {
+func (c *Client) StartResolve(txid uint16, cfg ResolveConfig) error {
 	nd := len(cfg.Questions)
 	if nd > math.MaxUint16 {
 		return errors.New("overflow uint16 in DNS questions")
 	}
-	c.reset(internal.Prand16(c.txid^uint16(c.connID)), dnsSendQuery, cfg.EnableRecursion)
+	c.reset(txid, dnsSendQuery, cfg.EnableRecursion)
 	c.msg.LimitResourceDecoding(uint16(nd), uint16(nd), 0, 0)
 	c.msg.AddQuestions(cfg.Questions)
 	return nil
@@ -46,17 +46,19 @@ func (c *Client) Encapsulate(carrierData []byte, frameOffset int) (int, error) {
 	} else if c.state != dnsSendQuery {
 		return 0, nil
 	}
+
 	msg := &c.msg
 	frame := carrierData[frameOffset:]
 	msglen := msg.Len()
 	if msglen > uint16(len(frame)) {
 		return 0, errCalcLen
 	}
-	data, err := msg.AppendTo(frame, c.txid, NewClientHeaderFlags(OpCodeQuery, c.enableRecursion))
+
+	data, err := msg.AppendTo(frame[:0], c.txid, NewClientHeaderFlags(OpCodeQuery, c.enableRecursion))
 	if err != nil {
 		return 0, err
 	} else if len(data) > int(msglen) {
-		return 0, errors.New("unexpected write")
+		return 0, fmt.Errorf("unexpected write %d v %d", len(data), msglen)
 	}
 	c.state = dnsAwaitResponse
 	return len(data), nil

dns/definitions.go

@@ -31,6 +31,7 @@ var (
 	errNonCanonicalName   = errors.New("name is not in canonical format (it must end with a .)")
 	errStringTooLong      = errors.New("character string exceeds maximum length (255)")
 	errCompressedSRV      = errors.New("compressed name in SRV resource data")
+	errEmptyDomainName    = errors.New("empty domain name")
 )
 
 // Frame encapsulates the raw data of a DNS packet

dns/dns.go

@@ -386,10 +386,15 @@ func MustNewName(s string) Name {
 	return name
 }
 
+var emptyDomain = []byte{0}
+
 // NewName parses a domain name and returns a new Name.
 func NewName(domain string) (Name, error) {
+	if domain == "" {
+		return Name{}, errEmptyDomainName
+	}
 	if len(domain) == 1 && domain[0] == '.' {
-		return Name{data: []byte{0}}, nil
+		return Name{data: emptyDomain}, nil
 	}
 	var name Name
 	for len(domain) > 0 {

examples/bridge/main.go

@@ -10,6 +10,7 @@ import (
 	"net"
 	"net/netip"
 	"os"
+	"runtime"
 	"strconv"
 	"strings"
 	"time"
@@ -100,26 +101,49 @@ func run() (err error) {
 	}
 	buf := make([]byte, mtu)
 	lastAction := time.Now()
-	dnsOngoing := false
+	const (
+		stateDHCP = iota
+		stateInitARP
+		stateDNS
+		stateDone
+	)
+	state := stateDHCP
 	for {
-		dhcpIsDone := stack.dhcp.State() == dhcpv4.StateBound
-		if dhcpIsDone {
-			if !dnsOngoing {
+		switch state {
+		case stateDHCP:
+			dhcpIsDone := stack.dhcp.State() == dhcpv4.StateBound
+			if dhcpIsDone {
+				state = stateInitARP
+				err = stack.ip.SetAddr(netip.AddrFrom4(stack.dhcp.AssignedAddr()))
+				if err != nil {
+					return err
+				}
+				err = stack.StartResolveHardwareAddress6(netip.AddrFrom4(stack.dhcp.RouterAddr()))
+				if err != nil {
+					return err
+				}
+			}
+
+		case stateInitARP:
+			router := stack.dhcp.RouterAddr()
+			hw, err := stack.ResultResolveHardwareAddress6(netip.AddrFrom4(router))
+			if err == nil {
+				state = stateDNS
+				stack.link.SetGateway6(hw)
 				err = stack.StartLookupIP(flagHostToResolve)
 				if err != nil {
 					return err
 				}
-				dnsOngoing = true
-			} else {
-				addrs, err := stack.ResultLookupIP()
-				if err == nil {
-					// END PROGRAM.
-					fmt.Println(flagHostToResolve, "resolved to", addrs)
-					return nil
-				}
+			}
+
+		case stateDNS:
+			addrs, err := stack.ResultLookupIP()
+			if err == nil {
+				fmt.Println(flagHostToResolve, "resolved to", addrs)
+				return nil
 			}
 		}
-		_ = dhcpIsDone
+
 		clear(buf)
 		nwrite, err := stack.Encapsulate(buf[:], 0)
 		if err != nil {
@@ -148,6 +172,7 @@ func run() (err error) {
 			time.Sleep(5 * time.Millisecond)
 		} else {
 			lastAction = time.Now()
+			runtime.Gosched()
 		}
 	}
 	return nil
@@ -169,7 +194,11 @@ type Stack struct {
 
 func (s *Stack) Demux(b []byte, _ int) (err error) {
 	s.aux, err = s.shark.CaptureEthernet(s.aux[:0], b, 0)
-	if s.aux[len(s.aux)-1].Protocol != "DHCPv4" {
+	baseFrame := s.aux[len(s.aux)-1]
+	isOK := baseFrame.Protocol == "DHCPv4" ||
+		(baseFrame.Protocol == lneto.IPProtoUDP && getField(baseFrame, b, pcap.FieldClassDst) == 53) ||
+		baseFrame.Protocol == ethernet.TypeARP
+	if !isOK {
 		return nil
 	}
 	if err != nil {
@@ -241,11 +270,15 @@ func (s *Stack) Reset(mac [6]byte, addr netip.Addr, mtu uint16) error {
 }
 
 func (s *Stack) StartLookupIP(host string) error {
+	dnsSrvs := s.dhcp.DNSServerFirst()
+	if !dnsSrvs.IsValid() {
+		return errors.New("no valid DNS server")
+	}
 	name, err := dns.NewName(host)
 	if err != nil {
 		return err
 	}
-	err = s.dns.StartResolve(dns.ResolveConfig{
+	err = s.dns.StartResolve(uint16(softRand), dns.ResolveConfig{
 		Questions: []dns.Question{
 			{
 				Name:  name,
@@ -259,12 +292,12 @@ func (s *Stack) StartLookupIP(host string) error {
 		return err
 	}
 	var u internet.StackUDPPort
-	u.SetStackNode(&s.dns, nil, dns.ServerPort)
+	dns4 := dnsSrvs.As4()
+	u.SetStackNode(&s.dns, dns4[:], dns.ServerPort)
 	err = s.udps.Register(&u)
 	if err != nil {
 		return err
 	}
-	return err
 	return nil
 }
 
@@ -309,8 +342,39 @@ func (s *Stack) BeginDHCPRequest(request [4]byte) error {
 	return err
 }
 
+func (s *Stack) StartResolveHardwareAddress6(ip netip.Addr) error {
+	if !ip.Is4() {
+		return errors.New("unsupported or invalid IP address")
+	}
+	addr := ip.As4()
+	return s.arp.StartQuery(addr[:])
+}
+
+func (s *Stack) ResultResolveHardwareAddress6(ip netip.Addr) (hw [6]byte, err error) {
+	if !ip.Is4() {
+		return hw, errors.New("unsupported or invalid IP address")
+	}
+	addr := ip.As4()
+	hwslice, err := s.arp.QueryResult(addr[:])
+	if err != nil {
+		return hw, err
+	} else if len(hwslice) != 6 {
+		panic("unreachable slice hw leng")
+	}
+	return [6]byte(hwslice), nil
+}
+
 func clear(buf []byte) {
 	for i := range buf {
 		buf[i] = 0
 	}
 }
+
+func getField(frame pcap.Frame, pkt []byte, class pcap.FieldClass) uint64 {
+	idx, err := frame.FieldByClass(class)
+	if err != nil {
+		return 0
+	}
+	v, _ := frame.FieldAsUint(idx, pkt)
+	return v
+}

examples/stackbasic/main.go

@@ -319,11 +319,11 @@ func (as *ARPStack) Protocol() uint32 { return uint32(ethernet.TypeARP) }
 func (as *ARPStack) Recv(EtherFrame []byte, arpOff int) error {
 	afrm, _ := arp.NewFrame(EtherFrame[arpOff:])
 	slog.Info("recv", slog.String("in", afrm.String()))
-	return as.handler.Recv(EtherFrame[arpOff:])
+	return as.handler.Demux(EtherFrame, arpOff)
 }
 
 func (as *ARPStack) Handle(EtherFrame []byte, arpOff int) (int, error) {
-	n, err := as.handler.Send(EtherFrame[arpOff:])
+	n, err := as.handler.Encapsulate(EtherFrame, arpOff)
 	if err != nil || n == 0 {
 		return 0, err
 	}

internet/node-arp.go

@@ -24,28 +24,23 @@ func (narp *NodeARP) Protocol() uint64 { return uint64(ethernet.TypeARP) }
 func (narp *NodeARP) ConnectionID() *uint64 { return narp.handler.ConnectionID() }
 
 func (narp *NodeARP) Demux(EtherFrame []byte, arpOff int) error {
-	afrm, err := arp.NewFrame(EtherFrame[arpOff:])
-	if err != nil {
-		slog.Error("bad-ARP", slog.String("err", err.Error()))
-		return nil
-	}
-	afrm.ValidateSize(&narp.vld)
-	if narp.vld.HasError() {
-		slog.Error("invalid-ARP", slog.String("err", narp.vld.ErrPop().Error()))
-		return nil
-	}
-	return narp.handler.Recv(EtherFrame[arpOff:])
+	return narp.handler.Demux(EtherFrame, arpOff)
 }
 
 func (narp *NodeARP) Encapsulate(EtherFrame []byte, arpOff int) (int, error) {
-	n, err := narp.handler.Send(EtherFrame[arpOff:])
+	n, err := narp.handler.Encapsulate(EtherFrame, arpOff)
 	if err != nil || n == 0 {
 		return 0, err // end with error.
 	}
 	afrm, _ := arp.NewFrame(EtherFrame[arpOff:])
-	hwaddr, _ := afrm.Target()
-	efrm, _ := ethernet.NewFrame(EtherFrame)
-	copy(efrm.DestinationHardwareAddr()[:], hwaddr)
 	slog.Info("handle", slog.String("out", afrm.String()))
 	return n, err
 }
+
+func (narp *NodeARP) StartQuery(proto []byte) error {
+	return narp.handler.StartQuery(proto)
+}
+
+func (narp *NodeARP) QueryResult(proto []byte) ([]byte, error) {
+	return narp.handler.QueryResult(proto)
+}

internet/stack-udpport.go

@@ -5,6 +5,7 @@ import (
 	"net"
 
 	"github.com/soypat/lneto"
+	"github.com/soypat/lneto/internal"
 	"github.com/soypat/lneto/udp"
 )
 
@@ -71,6 +72,12 @@ func (sudp *StackUDPPort) Encapsulate(carrierData []byte, frameOffset int) (int,
 	}
 	ufrm.SetSourcePort(sudp.h.port)
 	ufrm.SetDestinationPort(sudp.rmport)
+	if len(sudp.raddr) > 0 && frameOffset >= 20 {
+		err = internal.SetIPAddrs(carrierData, 0, nil, sudp.raddr)
+		if err != nil {
+			return 0, err
+		}
+	}
 	n, err := sudp.h.encapsulate(carrierData, frameOffset+8)
 	if n == 0 {
 		if err != nil {