Add ICMPv4 and lneto.StackNode and deprecate internet.StackNode (#65)

* begin adding icmp client

* rely on anon structs

* add tests

* tests passing

* icmp fleshed out

* rework icmp to include ip addr

* rename StackAsync.Demux/Encapsulate to RecvEthernet and SendEthernet

* remove legacy unreachable TCP tests

* remove uses of deprecated internet.StackNode in preference of lneto.StackNode

* documentation

* rename methods to signal no I/O happening

internet/definitions.go

@@ -1,7 +1,6 @@
 package internet
 
 import (
-	"errors"
 	"log/slog"
 	"math"
 	"net"
@@ -10,34 +9,6 @@ import (
 	"github.com/soypat/lneto"
 )
 
-// StackNode is an abstraction of a packet exchanging protocol controller. This is the building block for all protocols,
-// from Ethernet to IP to TCP, practically any protocol can be expressed as a StackNode and function completely.
-type StackNode interface {
-	// Encapsulate writes the stack node's frame into carrierData[offsetToFrame:]
-	// along with any other frame or payload the stack node encapsulates.
-	// The returned integer is amount of bytes written such that carrierData[offsetToFrame:offsetToFrame+n]
-	// contains written data. Data inside carrierData[:offsetToFrame] usually contains data necessary for
-	// a StackNode to correctly emit valid frame data: such is the case for TCP packets which require IP
-	// frame data for checksum calculation. Thus StackNodes must provide fields in their own frame
-	// required by sub-stacknodes for correct encapsulation; in the case of IPv4/6 this means including fields
-	// used in pseudo-header checksum like local IP (see [ipv4.CRCWriteUDPPseudo]).
-	//
-	// offsetToIP is the offset to the IP frame, if present, else its value should be -1.
-	// The relation offsetToIP<=offsetToFrame should always hold.
-	//
-	// When [net.ErrClosed] is returned the StackNode should be discarded and any written data passed up normally.
-	// Errors returned by Encapsulate are "extraordinary" and should not be returned unless the StackNode is receiving invalid carrierData/frameOffset.
-	Encapsulate(carrierData []byte, offsetToIP, offsetToFrame int) (int, error)
-	// Demux reads from the argument buffer where frameOffset is the offset of this StackNode's frame first byte.
-	// The stack node then dispatches(demuxes) the encapsulated frames to its corresponding sub-stack-node(s).
-	Demux(carrierData []byte, frameOffset int) error
-	LocalPort() uint16
-	Protocol() uint64
-	// Connect
-	ConnectionID() *uint64
-	// SetFlagPending(flagPending func(numPendingEncapsulations int))
-}
-
 // node is a concrete StackNode as stored in Stacks. Methods are devirtualized for performance benefits, especially on TinyGo.
 type node struct {
 	currConnID uint64
@@ -71,7 +42,7 @@ func (h *handlers) registerByProto(n node) error {
 		return err
 	}
 	if h.nodeByProto(n.proto) != nil {
-		return errProtoRegistered
+		return lneto.ErrAlreadyRegistered
 	}
 	h.nodes = append(h.nodes, n)
 	return nil
@@ -83,7 +54,7 @@ func (h *handlers) registerByPortProto(n node) error {
 		return err
 	}
 	if h.nodeByPortProto(n.port, n.proto) != nil {
-		return errProtoRegistered
+		return lneto.ErrAlreadyRegistered
 	}
 	h.nodes = append(h.nodes, n)
 	return nil
@@ -200,8 +171,7 @@ func (h *handlers) encapsulateAny(buf []byte, offsetIP, offsetThisFrame int) (_
 }
 
 var (
-	errProtoRegistered = errors.New("protocol already registered")
-	_                  = net.ErrClosed
+	_ = net.ErrClosed
 )
 
 func (node *node) IsInvalid() bool {
@@ -212,7 +182,7 @@ func checkNodeErr(node *node, err error) (discard bool) {
 	return node.IsInvalid() || (err != nil && err == net.ErrClosed)
 }
 
-func nodeFromStackNode(s StackNode, port uint16, protocol uint64, remoteAddr []byte) node {
+func nodeFromStackNode(s lneto.StackNode, port uint16, protocol uint64, remoteAddr []byte) node {
 	if protocol > math.MaxUint16 {
 		panic(">16bit protocol number unsupported")
 	}

internet/definitions_go.go

@@ -2,7 +2,9 @@
 
 package internet
 
-func makecbnode(s StackNode) cbnode {
+import "github.com/soypat/lneto"
+
+func makecbnode(s lneto.StackNode) cbnode {
 	return cbnode{
 		_s: s,
 	}
@@ -10,7 +12,7 @@ func makecbnode(s StackNode) cbnode {
 
 type cbnode struct {
 	// Do not access outside of handlers/node logic.
-	_s StackNode
+	_s lneto.StackNode
 }
 
 func (s cbnode) Encapsulate(carrierData []byte, offsetToIP, offsetToFrame int) (int, error) {

internet/stack-ethernet.go

@@ -101,6 +101,19 @@ func (ls *StackEthernet) Configure(cfg StackEthernetConfig) error {
 	return nil
 }
 
+// MaxFrameLength returns the maximum ethernet frame length in bytes, which is the MTU plus the Ethernet header (14 bytes) and CRC (4 bytes if enabled).
+// This is the maximum size of an Ethernet frame that can be sent from the stack.
+func (ls *StackEthernet) MaxFrameLength() int {
+	base := int(ls.mtu) + 14
+	if ls.crcupdate != nil {
+		base += 4
+	}
+	return base
+}
+
+// MTU is the Maximum Transmission Unit of the stack corresponding
+// to the maximum payload size of an ethernet frame that can be sent through the stack.
+// Important to note that the actual ethernet frame size is MTU + Ethernet header (14) + CRC (4 if enabled), this is known as the Maximum Frame Length.
 func (ls *StackEthernet) MTU() int { return int(ls.mtu) }
 
 func (ls *StackEthernet) ConnectionID() *uint64 { return &ls.connID }
@@ -109,7 +122,7 @@ func (ls *StackEthernet) LocalPort() uint16 { return 0 }
 
 func (ls *StackEthernet) Protocol() uint64 { return 1 }
 
-func (ls *StackEthernet) Register(h StackNode) error {
+func (ls *StackEthernet) Register(h lneto.StackNode) error {
 	proto := h.Protocol()
 	if proto > math.MaxUint16 || proto <= 1500 {
 		return lneto.ErrInvalidConfig

internet/stack-ip.go

@@ -13,7 +13,7 @@ import (
 	"github.com/soypat/lneto/udp"
 )
 
-var _ StackNode = (*StackIP)(nil)
+var _ lneto.StackNode = (*StackIP)(nil)
 
 type StackIP struct {
 	connID          uint64
@@ -205,7 +205,7 @@ func (sb *StackIP) Encapsulate(carrierData []byte, offsetToIP, offsetToFrame int
 	return totalLen, err
 }
 
-func (sb *StackIP) Register(h StackNode) error {
+func (sb *StackIP) Register(h lneto.StackNode) error {
 	proto := h.Protocol()
 	if proto > 255 {
 		return lneto.ErrInvalidConfig
@@ -213,6 +213,10 @@ func (sb *StackIP) Register(h StackNode) error {
 	return sb.handlers.registerByPortProto(nodeFromStackNode(h, h.LocalPort(), proto, nil))
 }
 
+func (sb *StackIP) IsRegistered(proto lneto.IPProto) bool {
+	return sb.handlers.nodeByProto(uint16(proto)) != nil
+}
+
 func (sb *StackIP) recvicmp(icmpData []byte) error {
 	var crc lneto.CRC791
 	if crc.PayloadSum16(icmpData) != 0 {

internet/stack-ports.go

@@ -87,7 +87,7 @@ func (ps *StackPorts) Demux(b []byte, offset int) (err 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) error {
+func (ps *StackPorts) Register(h lneto.StackNode) error {
 	port := h.LocalPort()
 	proto := h.Protocol()
 	if port <= 0 {
@@ -105,7 +105,7 @@ type StackPortsMACFiltered struct {
 	sp StackPorts
 }
 
-func (mfsp *StackPortsMACFiltered) Register(h StackNode, addr []byte) error {
+func (mfsp *StackPortsMACFiltered) Register(h lneto.StackNode, addr []byte) error {
 	port := h.LocalPort()
 	proto := h.Protocol()
 	if port <= 0 {

internet/stack-udpport.go

@@ -16,7 +16,7 @@ type StackUDPPort struct {
 	raddr  []byte
 }
 
-func (sudp *StackUDPPort) SetStackNode(node StackNode, raddr []byte, rmport uint16) {
+func (sudp *StackUDPPort) SetStackNode(node lneto.StackNode, raddr []byte, rmport uint16) {
 	sudp.h = nodeFromStackNode(node, node.LocalPort(), node.Protocol(), raddr)
 	sudp.rmport = rmport
 	sudp.raddr = append(sudp.raddr[:0], raddr...)