Fix slow exchanges on linux by adding polling and other improvements (#14)

* add prints to investigate slowness

* add loop sleep for blocking Stack

* add connection close http attribute and detect end of HTML page

* add timeout to bridge read

* examples/xnet: add ntp timestamp to prints and show output in readme

* add polling to http tap interface

* more digits in ntp format

* prevent crashes on non-8 timestamp

internet/pcap/capture.go

@@ -671,6 +671,7 @@ const (
 	// FieldClassBinaryText represents long stretches of binary data such as BOOTP DHCPv4 field.
 	FieldClassBinaryText // binary-text
 	FieldClassOperation  // op
+	FieldClassTimestamp  // timestamp
 )
 
 const octet = 8
@@ -1058,25 +1059,25 @@ var baseNTPFields = [...]FrameField{
 	},
 	{
 		Name:           "Reference Time",
-		Class:          FieldClassText,
+		Class:          FieldClassTimestamp,
 		FrameBitOffset: 16 * octet,
 		BitLength:      8 * octet,
 	},
 	{
 		Name:           "Origin Time",
-		Class:          FieldClassText,
+		Class:          FieldClassTimestamp,
 		FrameBitOffset: 24 * octet,
 		BitLength:      8 * octet,
 	},
 	{
 		Name:           "Receive Time",
-		Class:          FieldClassText,
+		Class:          FieldClassTimestamp,
 		FrameBitOffset: 32 * octet,
 		BitLength:      8 * octet,
 	},
 	{
 		Name:           "Transit Time",
-		Class:          FieldClassText,
+		Class:          FieldClassTimestamp,
 		FrameBitOffset: 40 * octet,
 		BitLength:      8 * octet,
 	},

internet/pcap/format.go

@@ -1,15 +1,19 @@
 package pcap
 
 import (
+	"encoding/binary"
 	"encoding/hex"
+	"errors"
 	"fmt"
 	"net/netip"
 	"slices"
 	"strconv"
 	"strings"
+	_ "time"
 
 	"github.com/soypat/lneto"
 	"github.com/soypat/lneto/ethernet"
+	"github.com/soypat/lneto/ntp"
 	"github.com/soypat/lneto/tcp"
 )
 
@@ -106,6 +110,14 @@ func (f *Formatter) formatField(dst []byte, pktStartOff int, field FrameField, p
 	switch field.Class {
 	default:
 		fallthrough
+	case FieldClassTimestamp:
+		// inspired by [time.RFC3339]
+		const littlerfc3339 = "2006-01-02T15:04:05.9999"
+		if len(f.buf) != 8 {
+			return dst, errors.New("only timestamp8 supported")
+		}
+		ts := ntp.TimestampFromUint64(binary.BigEndian.Uint64(f.buf))
+		dst = ts.Time().AppendFormat(dst, littlerfc3339)
 	case FieldClassChecksum, FieldClassID, FieldClassFlags, FieldClassOptions:
 		// Binary data to be printed as hexadecimal.
 		dst = append(dst, "0x"...)