add TCPConn Read+Write and ancilliary methods; looks like IP mux is broken

examples/stackbasic/main.go

@@ -14,9 +14,11 @@ import (
 	"github.com/soypat/lneto"
 	"github.com/soypat/lneto/arp"
 	"github.com/soypat/lneto/ethernet"
+	"github.com/soypat/lneto/http/httpraw"
 	"github.com/soypat/lneto/internal"
 	"github.com/soypat/lneto/internal/ltesto"
 	"github.com/soypat/lneto/internet"
+	"github.com/soypat/lneto/tcp"
 )
 
 const (
@@ -57,6 +59,7 @@ func main() {
 
 	fmt.Println("hosting server at ", addrPort.String())
 	var buf [mtu]byte
+	var hdr httpraw.Header
 	for {
 		nread, err := tap.Read(buf[:])
 		if err != nil {
@@ -81,6 +84,23 @@ func main() {
 				slogger.info("write", slog.Int("plen", nw))
 			}
 		}
+		if handler.State() == tcp.StateEstablished {
+			data := handler.BufferedInput()
+			if data > 0 {
+				n, err := handler.Read(buf[:])
+				if err != nil {
+					slogger.error("tcp-read", slog.String("err", err.Error()))
+				} else {
+					hdr.Reset(buf[:n])
+					err = hdr.Parse(false)
+					if err != nil {
+						slogger.error("http-parse", slog.String("err", err.Error()))
+					} else {
+						fmt.Println(hdr.String())
+					}
+				}
+			}
+		}
 		if nread == 0 && nw == 0 {
 			time.Sleep(5 * time.Millisecond)
 		}

internal/backoff.go

@@ -0,0 +1,59 @@
+package internal
+
+import "time"
+
+type BackoffFlags uint8
+
+const (
+	BackoffHasPriority BackoffFlags = 1 << iota
+	BackoffCriticalPath
+)
+
+func NewBackoff(priority BackoffFlags) Backoff {
+	if priority&BackoffCriticalPath != 0 {
+		return Backoff{
+			maxWait: uint32(1 * time.Millisecond),
+		}
+	}
+	return Backoff{
+		maxWait: uint32(time.Second) >> (priority & BackoffHasPriority),
+	}
+}
+
+// A Backoff with a non-zero MaxWait is ready for use.
+type Backoff struct {
+	// wait defines the amount of time that Miss will wait on next call.
+	wait uint32
+	// Maximum allowable value for Wait.
+	maxWait uint32
+	// startWait is the value that Wait takes after a call to Hit.
+	startWait uint32
+	// expMinusOne is the shift performed on Wait minus one, so the zero value performs a shift of 1.
+	expMinusOne uint32
+}
+
+// Hit sets eb.Wait to the StartWait value.
+func (eb *Backoff) Hit() {
+	if eb.maxWait == 0 {
+		panic("MaxWait cannot be zero")
+	}
+	eb.wait = eb.startWait
+}
+
+// Miss sleeps for eb.Wait and increases eb.Wait exponentially.
+func (eb *Backoff) Miss() {
+	const k = 1
+	wait := eb.wait
+	maxWait := eb.maxWait
+	exp := eb.expMinusOne + 1
+	if maxWait == 0 {
+		panic("MaxWait cannot be zero")
+	}
+	time.Sleep(time.Duration(wait))
+	wait |= k
+	wait <<= exp
+	if wait > maxWait {
+		wait = maxWait
+	}
+	eb.wait = wait
+}

internet/basicstack.go

@@ -63,6 +63,7 @@ func (sb *StackBasic) Recv(frame []byte) error {
 		h := &sb.handlers[i]
 		proto := ifrm.Protocol()
 		if h.proto == proto {
+			sb.info("iprecv", slog.String("ipproto", proto.String()), slog.Int("plen", int(totalLen)))
 			return h.recv(frame[:totalLen], off)
 		}
 	}

internet/tcpconn.go

@@ -4,24 +4,35 @@ import (
 	"bytes"
 	"errors"
 	"log/slog"
+	"net"
 	"net/netip"
+	"os"
+	"runtime"
 	"time"
 
+	"github.com/soypat/lneto/internal"
 	"github.com/soypat/lneto/ipv4"
 	"github.com/soypat/lneto/ipv6"
 	"github.com/soypat/lneto/tcp"
 )
 
+var (
+	errDeadlineExceeded = os.ErrDeadlineExceeded
+)
+
 type TCPConn struct {
 	h          tcp.Handler
 	remoteAddr []byte
-	logger
 
 	rdead  time.Time
 	wdead  time.Time
 	lastTx time.Time
 	lastRx time.Time
+
+	abortErr error
+	logger
 }
+
 type TCPConnConfig struct {
 	RxBuf             []byte
 	TxBuf             []byte
@@ -80,6 +91,11 @@ func (conn *TCPConn) OpenListen(localPort uint16, iss tcp.Value) error {
 	return nil
 }
 
+func (conn *TCPConn) Close() error {
+	conn.trace("TCPConn.Close")
+	return conn.h.Close()
+}
+
 func (conn *TCPConn) RecvIP(buf []byte, off int) (err error) {
 	conn.trace("tcpconn.Recv:start")
 	if off >= len(buf) {
@@ -102,6 +118,83 @@ func (conn *TCPConn) RecvIP(buf []byte, off int) (err error) {
 	return nil
 }
 
+// Write writes argument data to the TCPConns's output buffer which is queued to be sent.
+func (conn *TCPConn) Write(b []byte) (int, error) {
+	err := conn.checkPipeOpen()
+	if err != nil {
+		return 0, err
+	}
+	plen := len(b)
+	conn.trace("TCPConn.Write:start")
+	connid := conn.h.ConnectionID()
+	if conn.deadlineExceeded(conn.wdead) {
+		return 0, errDeadlineExceeded
+	} else if plen == 0 {
+		return 0, nil
+	}
+	backoff := internal.NewBackoff(internal.BackoffHasPriority)
+	n := 0
+	for {
+		if conn.abortErr != nil {
+			return n, conn.abortErr
+		} else if connid != conn.h.ConnectionID() {
+			return n, net.ErrClosed
+		}
+		ngot, _ := conn.h.Write(b)
+		n += ngot
+		b = b[ngot:]
+		if n == plen {
+			break
+		} else if ngot > 0 {
+			backoff.Hit()
+			runtime.Gosched() // Do a little yield since we won't have data for sure otherwise.
+		} else {
+			backoff.Miss()
+		}
+		conn.trace("TCPConn.Write:insuf-buf", slog.Int("missing", plen-n))
+		if conn.deadlineExceeded(conn.wdead) {
+			return n, errDeadlineExceeded
+		}
+	}
+	return n, nil
+}
+
+// Read reads data from the socket's input buffer. If the buffer is empty,
+// Read will block until data is available or connection closes.
+func (conn *TCPConn) Read(b []byte) (int, error) {
+	err := conn.checkPipeOpen()
+	if err != nil {
+		return 0, err
+	}
+	conn.trace("TCPConn.Read:start")
+	connid := conn.h.ConnectionID()
+	backoff := internal.NewBackoff(internal.BackoffHasPriority)
+	for conn.h.BufferedInput() == 0 && conn.State() == tcp.StateEstablished {
+		if conn.abortErr != nil {
+			return 0, conn.abortErr
+		} else if connid != conn.h.ConnectionID() {
+			return 0, net.ErrClosed
+		}
+		if conn.deadlineExceeded(conn.rdead) {
+			return 0, errDeadlineExceeded
+		}
+		backoff.Miss()
+	}
+	n, err := conn.h.Read(b)
+	return n, err
+}
+
+func (conn *TCPConn) checkPipeOpen() error {
+	if conn.abortErr != nil {
+		return conn.abortErr
+	}
+	state := conn.State()
+	if state.IsClosed() {
+		return net.ErrClosed
+	}
+	return nil
+}
+
 func (conn *TCPConn) HandleIP(buf []byte, off int) (n int, err error) {
 	if len(conn.remoteAddr) == 0 {
 		return 0, errors.New("unset IP address")
@@ -184,3 +277,43 @@ func (conn *TCPConn) reset(h tcp.Handler) {
 		logger:     conn.logger,
 	}
 }
+
+// SetDeadline sets the read and write deadlines associated
+// with the connection. It is equivalent to calling both
+// SetReadDeadline and SetWriteDeadline. Implements [net.Conn].
+func (conn *TCPConn) SetDeadline(t time.Time) error {
+	err := conn.SetReadDeadline(t)
+	if err != nil {
+		return err
+	}
+	return conn.SetWriteDeadline(t)
+}
+
+// SetReadDeadline sets the deadline for future Read calls
+// and any currently-blocked Read call. A zero value for t means Read will not time out.
+func (conn *TCPConn) SetReadDeadline(t time.Time) error {
+	conn.trace("TCPConn.SetReadDeadline:start")
+	err := conn.checkPipeOpen()
+	if err == nil {
+		conn.rdead = t
+	}
+	return err
+}
+
+// SetWriteDeadline sets the deadline for future Write calls
+// and any currently-blocked Write call.
+// Even if write times out, it may return n > 0, indicating that
+// some of the data was successfully written.
+// A zero value for t means Write will not time out.
+func (conn *TCPConn) SetWriteDeadline(t time.Time) error {
+	conn.trace("TCPConn.SetWriteDeadline:start")
+	err := conn.checkPipeOpen()
+	if err == nil {
+		conn.wdead = t
+	}
+	return err
+}
+
+func (conn *TCPConn) deadlineExceeded(deadline time.Time) bool {
+	return !deadline.IsZero() && time.Since(deadline) > 0
+}

tcp/handler.go

@@ -30,7 +30,7 @@ type Handler struct {
 	// connid is a conenction counter that is incremented each time a new
 	// connection is established via Open calls. This disambiguate's whether
 	// Read and Write calls belong to the current connection.
-	connid  uint8
+	connid  uint16
 	closing bool
 }
 
@@ -39,6 +39,11 @@ func (h *Handler) SetLoggers(handler, scb *slog.Logger) {
 	h.scb.logger.log = scb
 }
 
+// ConnectionID returns the connection identifier which is incremented every time the connection is closed or open.
+func (h *Handler) ConnectionID() int {
+	return int(h.connid)
+}
+
 // State returns the state of the TCP state machine as per RFC9293. See [State].
 func (h *Handler) State() State { return h.scb.State() }
 
@@ -99,6 +104,13 @@ func (h *Handler) OpenListen(localPort uint16, iss Value) error {
 	return nil
 }
 
+// Abort forcibly terminates all state associated to current connection.
+// After a call to abort no more data can be sent nor received over the connection.
+func (h *Handler) Abort() {
+	h.scb.Abort()
+	h.reset(0, 0, 0)
+}
+
 func (h *Handler) reset(localPort, remotePort uint16, iss Value) {
 	*h = Handler{
 		scb:        h.scb,
@@ -177,6 +189,11 @@ func (h *Handler) Recv(incomingPacket []byte) error {
 	return nil
 }
 
+func (h *Handler) Close() error {
+	h.trace("tcp.Handler.Close")
+	return h.scb.Close()
+}
+
 // Send writes TCP frame to be sent over the network to the remote peer to `b`.
 // It does no IP interfacing or CRC calculation of packet, which is left to the caller to perform.
 // The returned integer is the length written to the argument buffer.