changes to TCP stack to enable xnet functionality

examples/stack/main.go

@@ -249,7 +249,7 @@ func (stack *Stack) OpenTCPListener(port uint16) (*internet.NodeTCPListener, err
 func (stack *Stack) OpenPassiveTCP(port uint16, iss tcp.Value) (*tcp.Conn, error) {
 	mtu := stack.ethernet.MTU()
 	conn := new(tcp.Conn)
-	err := conn.Configure(&tcp.ConnConfig{
+	err := conn.Configure(tcp.ConnConfig{
 		RxBuf:             make([]byte, mtu),
 		TxBuf:             make([]byte, mtu),
 		TxPacketQueueSize: 3,
@@ -296,7 +296,7 @@ func (naiveTCPPool) GetTCP() (*tcp.Conn, tcp.Value) {
 	rand.Read(buf[:])
 	randVal := binary.LittleEndian.Uint32(buf[:])
 	var conn tcp.Conn
-	err := conn.Configure(&tcp.ConnConfig{
+	err := conn.Configure(tcp.ConnConfig{
 		RxBuf:             make([]byte, 1024),
 		TxBuf:             make([]byte, 1024),
 		TxPacketQueueSize: 3,

examples/stackbasic/main.go

@@ -182,7 +182,7 @@ func NewEthernetTCPStack(ourMAC, gwMAC [6]byte, ip netip.AddrPort, mtu uint16, s
 		lport:  0,
 	})
 	var conn tcp.Conn
-	err = conn.Configure(&tcp.ConnConfig{
+	err = conn.Configure(tcp.ConnConfig{
 		RxBuf:             make([]byte, mtu),
 		TxBuf:             make([]byte, mtu),
 		TxPacketQueueSize: 3,

examples/tap/main.go

@@ -32,6 +32,7 @@ func run() error {
 		flagInterface = "tap0"
 	)
 	flag.StringVar(&flagInterface, "i", flagInterface, "Interface to select. tap* creates a tap interface. Any other name will create a bridge to the name of the interface i.e: 'enp7s0', 'wlp8s0', 'lo'")
+	flag.Parse()
 	var (
 		flagNet             = "192.168.10.1/24"
 		flagiface           = "tap0"

examples/xnet/main.go

@@ -12,8 +12,10 @@ import (
 	"time"
 
 	"github.com/soypat/lneto/dns"
+	"github.com/soypat/lneto/http/httpraw"
 	"github.com/soypat/lneto/internal"
 	"github.com/soypat/lneto/internal/ltesto"
+	"github.com/soypat/lneto/internet/pcap"
 	"github.com/soypat/lneto/x/xnet"
 )
 
@@ -35,9 +37,11 @@ func run() (err error) {
 		flagHostToResolve = ""
 		flagRequestedIP   = ""
 		flagDoNTP         = false
+		flagHTTPGet       = false
 	)
+	flag.BoolVar(&flagHTTPGet, "httpget", flagHTTPGet, "Do an HTTP GET request ")
 	flag.StringVar(&flagInterface, "i", flagInterface, "Interface to use. Either tap* or the name of an existing interface to bridge to.")
-	flag.BoolVar(&flagUseHTTP, "http", flagUseHTTP, "Use HTTP tap interface.")
+	flag.BoolVar(&flagUseHTTP, "ihttp", flagUseHTTP, "Use HTTP tap interface.")
 	flag.StringVar(&flagHostToResolve, "host", flagHostToResolve, "Hostname to resolve via DNS.")
 	flag.StringVar(&flagRequestedIP, "addr", flagRequestedIP, "IP address to request via DHCP.")
 	flag.BoolVar(&flagDoNTP, "ntp", flagDoNTP, "Do NTP round and print result time")
@@ -89,6 +93,9 @@ func run() (err error) {
 		RandSeed:        softRand,
 		HardwareAddress: brHW,
 		MTU:             uint16(mtu),
+		MaxTCPConns:     1,
+		TCPBufferSizeTx: 2048,
+		TCPBufferSizeRx: 2048,
 	})
 	if err != nil {
 		return err
@@ -97,12 +104,17 @@ func run() (err error) {
 	go func() {
 		lastAction := time.Now()
 		buf := make([]byte, mtu)
+		var cap pcap.PacketBreakdown
 		for {
 			clear(buf)
 			nwrite, err := stack.Encapsulate(buf[:], 0)
 			if err != nil {
 				fmt.Println("ERR:ENCAPSULATE", err)
 			} else if nwrite > 0 {
+				frames, err := cap.CaptureEthernet(nil, buf[:nwrite], 0)
+				if len(frames) > 0 {
+					fmt.Println("OUT", frames)
+				}
 				n, err := iface.Write(buf[:nwrite])
 				if err != nil {
 					log.Fatal("groutine encapsulate:", err)
@@ -179,6 +191,43 @@ func run() (err error) {
 		return fmt.Errorf("DNS of host %q failed: %w", flagHostToResolve, err)
 	}
 	fmt.Printf("DNS resolution of %q complete and resolved to %v\n", flagHostToResolve, addrs)
+	if flagHTTPGet {
+		var hdr httpraw.Header
+		hdr.SetMethod("GET")
+		hdr.SetRequestURI("/")
+		hdr.SetProtocol("HTTP/1.1")
+		hdr.Set("Host", flagHostToResolve)
+		hdr.Set("User-Agent", "lneto")
+		hdr.Set("Accept-Language", "en-US,en;q=0.5")
+		req, err := hdr.AppendRequest(nil)
+		if err != nil {
+			return err
+		}
+		target := netip.AddrPortFrom(addrs[0], 80)
+		conn, err := rstack.DoDialTCP(uint16(softRand&0xefff)+1024, target, internetTimeout, internetRetries)
+		if err != nil {
+			return fmt.Errorf("TCP failed: %w", err)
+		}
+		conn.SetDeadline(time.Now().Add(internetTimeout))
+		_, err = conn.Write(req)
+		if err != nil {
+			return err
+		}
+		rxbuf := make([]byte, 2048)
+		var page []byte
+		for {
+			var n int
+			n, err = conn.Read(rxbuf)
+			page = append(page, rxbuf[:n]...)
+			if err != nil {
+				break
+			}
+		}
+		if len(page) == 0 {
+			return err
+		}
+		os.Stdout.Write(page)
+	}
 	return nil
 }
 

internet/stack-ports.go

@@ -93,15 +93,24 @@ func (ps *StackPorts) Demux(b []byte, offset int) (err error) {
 func (ps *StackPorts) Register(h StackNode) error {
 	port := h.LocalPort()
 	proto := h.Protocol()
+
 	if port <= 0 {
 		return errZeroPort
 	} else if proto != uint64(ps.protocol) {
 		return errInvalidProto
 	}
+	var cid uint64
+	cidPtr := h.ConnectionID()
+	if cidPtr != nil {
+		cid = *cidPtr
+	}
 	return registerNode(&ps.handlers, node{
 		demux:       h.Demux,
 		encapsulate: h.Encapsulate,
 		port:        port,
+		currConnID:  cid,
+		connID:      cidPtr,
+		proto:       uint16(proto),
 	})
 }
 

internet/stackbasic_test.go

@@ -94,7 +94,7 @@ func setupClientServer(t *testing.T, rng *rand.Rand, client, server *StackIP, co
 	server.Reset(svip.Addr(), maxNodes)
 	client.Reset(clip.Addr(), maxNodes)
 
-	err := connServer.Configure(&tcp.ConnConfig{
+	err := connServer.Configure(tcp.ConnConfig{
 		RxBuf:             make([]byte, bufsize),
 		TxBuf:             make([]byte, bufsize),
 		TxPacketQueueSize: 3,
@@ -103,7 +103,7 @@ func setupClientServer(t *testing.T, rng *rand.Rand, client, server *StackIP, co
 	if err != nil {
 		t.Fatal(err)
 	}
-	err = connClient.Configure(&tcp.ConnConfig{
+	err = connClient.Configure(tcp.ConnConfig{
 		RxBuf:             make([]byte, bufsize),
 		TxBuf:             make([]byte, bufsize),
 		TxPacketQueueSize: 3,

tcp/conn.go

@@ -44,7 +44,7 @@ type ConnConfig struct {
 	Logger            *slog.Logger
 }
 
-func (conn *Conn) Configure(config *ConnConfig) (err error) {
+func (conn *Conn) Configure(config ConnConfig) (err error) {
 	err = conn.h.SetBuffers(config.TxBuf, config.RxBuf, config.TxPacketQueueSize)
 	if err != nil {
 		return err
@@ -109,9 +109,17 @@ func (conn *Conn) Abort() {
 		h:          conn.h,
 		remoteAddr: conn.remoteAddr[:0],
 		logger:     conn.logger,
+		ipID:       conn.ipID,
 	}
 }
 
+// InternalHandler returns the internal [Handler] instance. The Handler contains lower level implementation logic for a TCP connection.
+// Typical users should not be using this method unless implementing a stack which manages several TCP connections and thus need
+// access to low level internals for careful memory management.
+func (conn *Conn) InternalHandler() *Handler {
+	return &conn.h
+}
+
 // Write writes argument data to the TCPConns's output buffer which is queued to be sent.
 func (conn *Conn) Write(b []byte) (int, error) {
 	err := conn.checkPipeOpen()

tcp/handler.go

@@ -53,16 +53,17 @@ func (h *Handler) ConnectionID() *uint64 {
 func (h *Handler) State() State { return h.scb.State() }
 
 // SetBuffers sets the internal buffers used to receive and transmit bytes asynchronously via [Handler.Write] and [Handler.Read] calls.
+// If the argument buffer is nil then the respective currently set buffer will be reused.
 func (h *Handler) SetBuffers(txbuf, rxbuf []byte, packets int) error {
+	if h.bufRx.Buf == nil && (len(rxbuf) < minBufferSize || len(txbuf) < minBufferSize) {
+		return errors.New("tcp: short buffer")
+	}
 	if !h.scb.State().IsClosed() {
 		return errors.New("tcp.Handler must be closed before setting buffers")
 	}
 	if rxbuf != nil {
 		h.bufRx.Buf = rxbuf
 	}
-	if len(h.bufRx.Buf) < minBufferSize {
-		return errors.New("short rx buffer")
-	}
 	h.scb.SetRecvWindow(Size(h.bufRx.Size()))
 	h.bufRx.Reset()
 	return h.bufTx.ResetOrReuse(txbuf, packets, 0)
@@ -270,11 +271,16 @@ func (h *Handler) Send(b []byte) (int, error) {
 	return int(offset)*4 + int(segment.DATALEN), nil
 }
 
-// Free returns the amount of space free in the transmit buffer. A call to [Handler.Write] with a larger buffer will fail.
+// FreeTx returns the amount of space free in the transmit buffer. A call to [Handler.Write] with a larger buffer will fail.
-func (h *Handler) Free() int {
+func (h *Handler) FreeTx() int {
 	return h.bufTx.Free()
 }
 
+// SizeRx returns the size of the TCP receive ring buffer.
+func (h *Handler) SizeRx() int {
+	return h.bufRx.Size()
+}
+
 // Write implements [io.Writer] by copying b to a internal buffer to be sent over the network on the next
 // [Handler.Send] call that can send data to remote peer. Use [Handler.Free] to know the maximum length the argument slice can be before erroring.
 func (h *Handler) Write(b []byte) (int, error) {

x/xnet/stack-async.go

@@ -2,6 +2,7 @@ package xnet
 
 import (
 	"errors"
+	"io"
 	"net/netip"
 	"sync"
 	"time"
@@ -16,6 +17,10 @@ import (
 	"github.com/soypat/lneto/tcp"
 )
 
+const (
+	minTCPBuffer = 256
+)
+
 type StackAsync struct {
 	mu       sync.Mutex
 	hostname string
@@ -52,6 +57,8 @@ type StackConfig struct {
 	NTPServer       netip.Addr
 	Hostname        string
 	MaxTCPConns     int
+	TCPBufferSizeTx int // Size of transmit buffer for TCP connections.
+	TCPBufferSizeRx int // Size of receive buffer for TCP connections.
 	RandSeed        int64
 	HardwareAddress [6]byte
 	MTU             uint16
@@ -112,9 +119,35 @@ func (s *StackAsync) Reset(cfg StackConfig) error {
 
 	// Enable TCP if connections present.
 	if cfg.MaxTCPConns > 0 {
+		if cfg.TCPBufferSizeRx < minTCPBuffer || cfg.TCPBufferSizeTx < minTCPBuffer {
+			return io.ErrShortBuffer
+		}
 		if cap(s.tcpconns) < cfg.MaxTCPConns {
 			s.tcpconns = make([]tcp.Conn, cfg.MaxTCPConns)
 		}
+		s.tcpconns = s.tcpconns[:cfg.MaxTCPConns]
+		for i := range s.tcpconns {
+			c := &s.tcpconns[i]
+			c.Abort() // Abort forcibly closes connection to allow buffer setting and reduce risk of race conditions.
+			h := c.InternalHandler()
+			sizetx := h.FreeTx()
+			sizerx := h.SizeRx()
+			// If size is sufficient then buffers will remain nil and memory will be reused.
+			var rxbuf, txbuf []byte
+			if sizetx < cfg.TCPBufferSizeTx || sizerx < cfg.TCPBufferSizeRx {
+				buf := make([]byte, cfg.TCPBufferSizeTx+cfg.TCPBufferSizeRx)
+				rxbuf = buf[:cfg.TCPBufferSizeRx]
+				txbuf = buf[cfg.TCPBufferSizeRx : cfg.TCPBufferSizeRx+cfg.TCPBufferSizeTx]
+			}
+			err = c.Configure(tcp.ConnConfig{
+				RxBuf:             rxbuf,
+				TxBuf:             txbuf,
+				TxPacketQueueSize: 4,
+			})
+			if err != nil {
+				return err
+			}
+		}
 		err = s.tcps.ResetTCP(cfg.MaxTCPConns)
 		if err != nil {
 			return err
@@ -213,7 +246,7 @@ func (s *StackAsync) DialTCP(localPort uint16, addrp netip.AddrPort) (conn *tcp.
 	}
 	for i := range s.tcpconns {
 		maybeFreeConn := &s.tcpconns[i]
-		state := conn.State()
+		state := maybeFreeConn.State()
 		if state.IsClosed() {
 			conn = maybeFreeConn
 			break // Can be used!

x/xnet/stack-blocking.go

@@ -122,21 +122,20 @@ func (s StackBlocking) DoDialTCP(localPort uint16, addrp netip.AddrPort, timeout
 	deadline := time.Now().Add(timeout)
 	for i := 0; i < maxIter; i++ {
 		state := conn.State()
-		switch state {
+		if state == tcp.StateEstablished {
-		case tcp.StateEstablished:
+			return conn, nil
-			break
+		} else if state == tcp.StateSynSent || state == tcp.StateSynRcvd || conn.InternalHandler().AwaitingSynSend() {
-		case tcp.StateSynSent, tcp.StateSynRcvd:
 			if err = s.checkDeadline(deadline); err != nil {
 				return nil, err
 			}
 			time.Sleep(sleep)
-		default:
+		} else {
 			// Unexpected state, abort and terminate connection.
 			conn.Abort()
 			return nil, errTCPFailedToConnect
 		}
 	}
-	return conn, nil
+	return conn, errDeadlineExceed
 }
 
 func (s StackBlocking) checkDeadline(deadline time.Time) error {