path: root/ui/qt/follow_stream_dialog.cpp

/* follow_stream_dialog.cpp
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#include "follow_stream_dialog.h"
#include <ui_follow_stream_dialog.h>

#include "main_application.h"
#include "main_window.h"

#include "frame_tvbuff.h"
#include "epan/follow.h"
#include "epan/prefs.h"
#include "epan/addr_resolv.h"
#include "epan/charsets.h"
#include "epan/epan_dissect.h"
#include "epan/tap.h"

#include "ui/alert_box.h"
#include "ui/simple_dialog.h"
#include <ui/recent.h>
#include <wsutil/utf8_entities.h>
#include <wsutil/ws_assert.h>

#include "wsutil/file_util.h"
#include "wsutil/str_util.h"

#include "ws_symbol_export.h"

#include <ui/qt/utils/color_utils.h>
#include <ui/qt/utils/qt_ui_utils.h>

#include "progress_frame.h"

#include "ui/qt/widgets/wireshark_file_dialog.h"

#include <QElapsedTimer>
#include <QKeyEvent>
#include <QMessageBox>
#include <QMutex>
#include <QPrintDialog>
#include <QPrinter>
#include <QScrollBar>
#include <QTextCodec>

// To do:
// - Show text while tapping.
// - Instead of calling QMessageBox, display the error message in the text
//   box and disable the appropriate controls.
// - Add a progress bar and connect captureCaptureUpdateContinue to it
// - User's Guide documents the "Raw" type as "same as ASCII, but saving binary
//   data". However it currently displays hex-encoded data.

// Matches SplashOverlay.
static int info_update_freq_ = 100;

// Handle the loop breaking notification properly
static QMutex loop_break_mutex;

// Indicates that a Follow Stream is currently running
static gboolean isReadRunning;

Q_DECLARE_METATYPE(bytes_show_type)

FollowStreamDialog::FollowStreamDialog(QWidget &parent, CaptureFile &cf, int proto_id) :
    WiresharkDialog(parent, cf),
    ui(new Ui::FollowStreamDialog),
    b_find_(NULL),
    follower_(NULL),
    truncated_(false),
    client_buffer_count_(0),
    server_buffer_count_(0),
    client_packet_count_(0),
    server_packet_count_(0),
    last_packet_(0),
    last_from_server_(0),
    turns_(0),
    use_regex_find_(false),
    terminating_(false),
    previous_sub_stream_num_(0)
{
    ui->setupUi(this);
    loadGeometry(parent.width() * 2 / 3, parent.height());

    ui->streamNumberSpinBox->setStyleSheet("QSpinBox { min-width: 2em; }");
    ui->subStreamNumberSpinBox->setStyleSheet("QSpinBox { min-width: 2em; }");
    ui->streamNumberSpinBox->setKeyboardTracking(false);
    ui->subStreamNumberSpinBox->setKeyboardTracking(false);

    follower_ = get_follow_by_proto_id(proto_id);
    if (follower_ == NULL) {
        ws_assert_not_reached();
    }

    memset(&follow_info_, 0, sizeof(follow_info_));
    follow_info_.show_stream = BOTH_HOSTS;
    follow_info_.substream_id = SUBSTREAM_UNUSED;

    ui->teStreamContent->installEventFilter(this);

    connect(ui->leFind, SIGNAL(useRegexFind(bool)), this, SLOT(useRegexFind(bool)));

    QComboBox *cbcs = ui->cbCharset;
    cbcs->blockSignals(true);
    cbcs->addItem(tr("ASCII"), SHOW_ASCII);
    cbcs->addItem(tr("C Arrays"), SHOW_CARRAY);
    cbcs->addItem(tr("EBCDIC"), SHOW_EBCDIC);
    cbcs->addItem(tr("Hex Dump"), SHOW_HEXDUMP);
    cbcs->addItem(tr("Raw"), SHOW_RAW);
    // UTF-8 is guaranteed to exist as a QTextCodec
    cbcs->addItem(tr("UTF-8"), SHOW_CODEC);
    cbcs->addItem(tr("YAML"), SHOW_YAML);
    cbcs->setCurrentIndex(cbcs->findData(recent.gui_follow_show));
    cbcs->blockSignals(false);

    b_filter_out_ = ui->buttonBox->addButton(tr("Filter Out This Stream"), QDialogButtonBox::ActionRole);
    connect(b_filter_out_, SIGNAL(clicked()), this, SLOT(filterOut()));

    b_print_ = ui->buttonBox->addButton(tr("Print"), QDialogButtonBox::ActionRole);
    connect(b_print_, SIGNAL(clicked()), this, SLOT(printStream()));

    b_save_ = ui->buttonBox->addButton(tr("Save as…"), QDialogButtonBox::ActionRole);
    connect(b_save_, SIGNAL(clicked()), this, SLOT(saveAs()));

    b_back_ = ui->buttonBox->addButton(tr("Back"), QDialogButtonBox::ActionRole);
    connect(b_back_, SIGNAL(clicked()), this, SLOT(backButton()));

    ProgressFrame::addToButtonBox(ui->buttonBox, &parent);

    connect(ui->buttonBox, SIGNAL(helpRequested()), this, SLOT(helpButton()));
    connect(ui->teStreamContent, SIGNAL(mouseMovedToTextCursorPosition(int)),
            this, SLOT(fillHintLabel(int)));
    connect(ui->teStreamContent, SIGNAL(mouseClickedOnTextCursorPosition(int)),
            this, SLOT(goToPacketForTextPos(int)));

    fillHintLabel(-1);
}

FollowStreamDialog::~FollowStreamDialog()
{
    delete ui;
    resetStream(); // Frees payload
}

void FollowStreamDialog::addCodecs(const QMap<QString, QTextCodec *> &codecMap)
{
    // Make the combobox respect max visible items?
    //ui->cbCharset->setStyleSheet("QComboBox { combobox-popup: 0;}");
    ui->cbCharset->insertSeparator(ui->cbCharset->count());
    for (const auto &codec : codecMap) {
        // This is already in the menu and handled separately
        if (codec->name() != "US-ASCII" && codec->name() != "UTF-8")
            ui->cbCharset->addItem(tr(codec->name()), SHOW_CODEC);
    }
}

void FollowStreamDialog::printStream()
{
#ifndef QT_NO_PRINTER
    QPrinter printer(QPrinter::HighResolution);
    QPrintDialog dialog(&printer, this);
    if (dialog.exec() == QDialog::Accepted)
        ui->teStreamContent->print(&printer);
#endif
}

void FollowStreamDialog::fillHintLabel(int text_pos)
{
    QString hint;
    int pkt = -1;

    if (text_pos >= 0) {
        QMap<int, guint32>::iterator it = text_pos_to_packet_.upperBound(text_pos);
        if (it != text_pos_to_packet_.end()) {
            pkt = it.value();
        }
    }

    if (pkt > 0) {
        hint = QString(tr("Packet %1. ")).arg(pkt);
    }

    hint += tr("%Ln <span style=\"color: %1; background-color:%2\">client</span> pkt(s), ", "", client_packet_count_)
            .arg(ColorUtils::fromColorT(prefs.st_client_fg).name())
            .arg(ColorUtils::fromColorT(prefs.st_client_bg).name())
            + tr("%Ln <span style=\"color: %1; background-color:%2\">server</span> pkt(s), ", "", server_packet_count_)
            .arg(ColorUtils::fromColorT(prefs.st_server_fg).name())
            .arg(ColorUtils::fromColorT(prefs.st_server_bg).name())
            + tr("%Ln turn(s).", "", turns_);

    if (pkt > 0) {
        hint.append(QString(tr(" Click to select.")));
    }

    hint.prepend("<small><i>");
    hint.append("</i></small>");
    ui->hintLabel->setText(hint);
}

void FollowStreamDialog::goToPacketForTextPos(int text_pos)
{
    int pkt = -1;
    if (file_closed_) {
        return;
    }

    if (text_pos >= 0) {
        QMap<int, guint32>::iterator it = text_pos_to_packet_.upperBound(text_pos);
        if (it != text_pos_to_packet_.end()) {
            pkt = it.value();
        }
    }

    if (pkt > 0) {
        emit goToPacket(pkt);
    }
}

void FollowStreamDialog::updateWidgets(bool follow_in_progress)
{
    // XXX: If follow_in_progress set cursor to Qt::BusyCursor or WaitCursor,
    // otherwise unset cursor?
    bool enable = !follow_in_progress;
    if (file_closed_) {
        ui->teStreamContent->setEnabled(true);
        enable = false;
    }

    ui->cbDirections->setEnabled(enable);
    ui->cbCharset->setEnabled(enable);
    ui->streamNumberSpinBox->setReadOnly(!enable);
    if (get_follow_sub_stream_id_func(follower_) != NULL) {
        ui->subStreamNumberSpinBox->setReadOnly(!enable);
    }
    ui->leFind->setEnabled(enable);
    ui->bFind->setEnabled(enable);
    b_filter_out_->setEnabled(enable);
    b_print_->setEnabled(enable);
    b_save_->setEnabled(enable);

    WiresharkDialog::updateWidgets();
}

void FollowStreamDialog::useRegexFind(bool use_regex)
{
    use_regex_find_ = use_regex;
    if (use_regex_find_)
        ui->lFind->setText(tr("Regex Find:"));
    else
        ui->lFind->setText(tr("Find:"));
}

void FollowStreamDialog::findText(bool go_back)
{
    if (ui->leFind->text().isEmpty()) return;

    bool found;
    if (use_regex_find_) {
#if (QT_VERSION >= QT_VERSION_CHECK(5, 13, 0))
        QRegularExpression regex(ui->leFind->text(), QRegularExpression::UseUnicodePropertiesOption);
#else
        QRegExp regex(ui->leFind->text());
#endif
        found = ui->teStreamContent->find(regex);
    } else {
        found = ui->teStreamContent->find(ui->leFind->text());
    }

    if (found) {
        ui->teStreamContent->setFocus();
    } else if (go_back) {
        ui->teStreamContent->moveCursor(QTextCursor::Start);
        findText(false);
    }
}

void FollowStreamDialog::saveAs()
{
    QString file_name = WiresharkFileDialog::getSaveFileName(this, mainApp->windowTitleString(tr("Save Stream Content As…")));
    if (file_name.isEmpty()) {
        return;
    }

    QFile file(file_name);
    if (!file.open(QIODevice::WriteOnly)) {
        open_failure_alert_box(file_name.toUtf8().constData(), errno, TRUE);
        return;
    }

    // Unconditionally save data as UTF-8 (even if data is decoded otherwise).
    QByteArray bytes = ui->teStreamContent->toPlainText().toUtf8();
    if (recent.gui_follow_show == SHOW_RAW) {
        // The "Raw" format is currently displayed as hex data and needs to be
        // converted to binary data.
        bytes = QByteArray::fromHex(bytes);
    }

    QDataStream out(&file);
    out.writeRawData(bytes.constData(), static_cast<int>(bytes.size()));
}

void FollowStreamDialog::helpButton()
{
    mainApp->helpTopicAction(HELP_FOLLOW_STREAM_DIALOG);
}

void FollowStreamDialog::backButton()
{
    if (terminating_)
        return;

    output_filter_ = previous_filter_;

    close();
}

void FollowStreamDialog::filterOut()
{
    if (terminating_)
        return;

    output_filter_ = filter_out_filter_;

    close();
}

void FollowStreamDialog::close()
{
    terminating_ = true;

    // Update filter - Use:
    //     previous_filter if 'Close' (passed in follow() method)
    //     filter_out_filter_ if 'Filter Out This Stream' (built by appending !current_stream to previous_filter)
    //     leave filter alone if window closed. (current stream)
    emit updateFilter(output_filter_, TRUE);

    WiresharkDialog::close();
}

void FollowStreamDialog::on_cbDirections_currentIndexChanged(int idx)
{
    switch(idx)
    {
    case 0 :
        follow_info_.show_stream = BOTH_HOSTS;
        break;
    case 1 :
        follow_info_.show_stream = FROM_SERVER;
        break;
    case 2 :
        follow_info_.show_stream = FROM_CLIENT;
        break;
    default:
        return;
    }

    readStream();
}

void FollowStreamDialog::on_cbCharset_currentIndexChanged(int idx)
{
    if (idx < 0) return;
    recent.gui_follow_show = ui->cbCharset->currentData().value<bytes_show_type>();
    readStream();
}

void FollowStreamDialog::on_bFind_clicked()
{
    findText();
}

void FollowStreamDialog::on_leFind_returnPressed()
{
    findText();
}

void FollowStreamDialog::on_streamNumberSpinBox_valueChanged(int stream_num)
{
    if (file_closed_) return;

    int sub_stream_num = 0;
    ui->subStreamNumberSpinBox->blockSignals(true);
    sub_stream_num = ui->subStreamNumberSpinBox->value();
    ui->subStreamNumberSpinBox->blockSignals(false);

    gboolean ok;
    if (ui->subStreamNumberSpinBox->isVisible()) {
        /* We need to find a suitable sub stream for the new stream */
        follow_sub_stream_id_func sub_stream_func;
        sub_stream_func = get_follow_sub_stream_id_func(follower_);

        if (sub_stream_func == NULL) {
            // Should not happen, this field is only visible for suitable protocols.
            return;
        }

        guint sub_stream_num_new = static_cast<guint>(sub_stream_num);
        if (sub_stream_num < 0) {
            // Stream ID 0 should always exist as it is used for control messages.
            // XXX: That is only guaranteed for HTTP2. For example, in QUIC,
            // stream ID 0 is a normal stream used by the first standard client-
            // initiated bidirectional stream (if it exists, and it might not)
            // and we might have a stream (connection) but only the CRYPTO
            // stream, which does not have a (sub) stream ID.
            // What should we do if there is a stream with no substream to
            // follow? Right now the substream spinbox is left active and
            // the user can change the value to no effect.
            sub_stream_num_new = 0;
            ok = TRUE;
        } else {
            ok = sub_stream_func(static_cast<guint>(stream_num), sub_stream_num_new, FALSE, &sub_stream_num_new);
            if (!ok) {
                ok = sub_stream_func(static_cast<guint>(stream_num), sub_stream_num_new, TRUE, &sub_stream_num_new);
            }
        }
        sub_stream_num = static_cast<gint>(sub_stream_num_new);
    } else {
        /* XXX: For HTTP and TLS, we use the TCP stream index, and really should
         * return false if the TCP stream doesn't have HTTP or TLS. (Or we could
         * switch to having separate HTTP and TLS stream numbers.)
         */
        ok = true;
    }

    if (stream_num >= 0 && ok) {
        follow(previous_filter_, true, stream_num, sub_stream_num);
        previous_sub_stream_num_ = sub_stream_num;
    }
}


void FollowStreamDialog::on_subStreamNumberSpinBox_valueChanged(int sub_stream_num)
{
    if (file_closed_) return;

    int stream_num = 0;
    ui->streamNumberSpinBox->blockSignals(true);
    stream_num = ui->streamNumberSpinBox->value();
    ui->streamNumberSpinBox->blockSignals(false);

    follow_sub_stream_id_func sub_stream_func;
    sub_stream_func = get_follow_sub_stream_id_func(follower_);

    if (sub_stream_func == NULL) {
        // Should not happen, this field is only visible for suitable protocols.
        return;
    }

    guint sub_stream_num_new = static_cast<guint>(sub_stream_num);
    gboolean ok;
    /* previous_sub_stream_num_ is a hack to track which buttons was pressed without event handling */
    if (sub_stream_num < 0) {
        // Stream ID 0 should always exist as it is used for control messages.
        // XXX: That is only guaranteed for HTTP2, see above.
        sub_stream_num_new = 0;
        ok = TRUE;
    } else if (previous_sub_stream_num_ < sub_stream_num) {
        ok = sub_stream_func(static_cast<guint>(stream_num), sub_stream_num_new, FALSE, &sub_stream_num_new);
    } else {
        ok = sub_stream_func(static_cast<guint>(stream_num), sub_stream_num_new, TRUE, &sub_stream_num_new);
    }
    sub_stream_num = static_cast<gint>(sub_stream_num_new);

    if (ok) {
        follow(previous_filter_, true, stream_num, sub_stream_num);
        previous_sub_stream_num_ = sub_stream_num;
    }
}

void FollowStreamDialog::on_buttonBox_rejected()
{
    // Ignore the close button if FollowStreamDialog::close() is running.
    if (terminating_)
        return;

    WiresharkDialog::reject();
}

void FollowStreamDialog::removeStreamControls()
{
    ui->horizontalLayout->removeItem(ui->streamNumberSpacer);
    ui->streamNumberLabel->setVisible(false);
    ui->streamNumberSpinBox->setVisible(false);
    ui->subStreamNumberLabel->setVisible(false);
    ui->subStreamNumberSpinBox->setVisible(false);
}

void FollowStreamDialog::resetStream()
{
    GList *cur;
    follow_record_t *follow_record;

    filter_out_filter_.clear();
    text_pos_to_packet_.clear();
    if (!data_out_filename_.isEmpty()) {
        ws_unlink(data_out_filename_.toUtf8().constData());
    }
    for (cur = follow_info_.payload; cur; cur = gxx_list_next(cur)) {
        follow_record = gxx_list_data(follow_record_t *, cur);
        if (follow_record->data) {
            g_byte_array_free(follow_record->data, TRUE);
        }
        g_free(follow_record);
    }
    g_list_free(follow_info_.payload);

    //Only TCP stream uses fragments
    for (cur = follow_info_.fragments[0]; cur; cur = gxx_list_next(cur)) {
        follow_record = gxx_list_data(follow_record_t *, cur);
        if (follow_record->data) {
            g_byte_array_free(follow_record->data, TRUE);
        }
        g_free(follow_record);
    }
    follow_info_.fragments[0] = Q_NULLPTR;
    for (cur = follow_info_.fragments[1]; cur; cur = gxx_list_next(cur)) {
        follow_record = gxx_list_data(follow_record_t *, cur);
        if (follow_record->data) {
            g_byte_array_free(follow_record->data, TRUE);
        }
        g_free(follow_record);
    }
    follow_info_.fragments[1] = Q_NULLPTR;

    free_address(&follow_info_.client_ip);
    free_address(&follow_info_.server_ip);
    follow_info_.payload = Q_NULLPTR;
    follow_info_.client_port = 0;
}

frs_return_t
FollowStreamDialog::readStream()
{

    // interrupt any reading already running
    loop_break_mutex.lock();
    isReadRunning = FALSE;
    loop_break_mutex.unlock();

    ui->teStreamContent->clear();
    text_pos_to_packet_.clear();
    switch (recent.gui_follow_show) {

    case SHOW_CARRAY:
    case SHOW_HEXDUMP:
    case SHOW_YAML:
        /* We control the width and insert line breaks in these formats. */
        ui->teStreamContent->setWordWrapMode(QTextOption::WrapAtWordBoundaryOrAnywhere);
        break;

    default:
        /* Everything else might have extremely long lines without whitespace,
         * (SHOW_RAW almost surely so), and QTextEdit is O(N^2) trying
         * to search for word boundaries on long lines when adding text.
         */
        ui->teStreamContent->setWordWrapMode(QTextOption::WrapAnywhere);
    }

    truncated_ = false;
    frs_return_t ret;

    client_buffer_count_ = 0;
    server_buffer_count_ = 0;
    client_packet_count_ = 0;
    server_packet_count_ = 0;
    last_packet_ = 0;
    turns_ = 0;

    if (follower_) {
        ret = readFollowStream();
    } else {
        ret = (frs_return_t)0;
        ws_assert_not_reached();
    }

    ui->teStreamContent->moveCursor(QTextCursor::Start);

    return ret;
}

void
FollowStreamDialog::followStream()
{
    readStream();
}

const int FollowStreamDialog::max_document_length_ = 500 * 1000 * 1000; // Just a guess
void FollowStreamDialog::addText(QString text, gboolean is_from_server, guint32 packet_num, gboolean colorize)
{
    if (truncated_) {
        return;
    }

    int char_count = ui->teStreamContent->document()->characterCount();
    if (char_count + text.length() > max_document_length_) {
        text.truncate(max_document_length_ - char_count);
        truncated_ = true;
    }

    setUpdatesEnabled(false);
    int cur_pos = ui->teStreamContent->verticalScrollBar()->value();
    ui->teStreamContent->moveCursor(QTextCursor::End);

    QTextCharFormat tcf = ui->teStreamContent->currentCharFormat();
    if (!colorize) {
        tcf.setBackground(palette().window().color());
        tcf.setForeground(palette().windowText().color());
    } else if (is_from_server) {
        tcf.setForeground(ColorUtils::fromColorT(prefs.st_server_fg));
        tcf.setBackground(ColorUtils::fromColorT(prefs.st_server_bg));
    } else {
        tcf.setForeground(ColorUtils::fromColorT(prefs.st_client_fg));
        tcf.setBackground(ColorUtils::fromColorT(prefs.st_client_bg));
    }
    ui->teStreamContent->setCurrentCharFormat(tcf);

    ui->teStreamContent->insertPlainText(text);
    text_pos_to_packet_[ui->teStreamContent->textCursor().anchor()] = packet_num;

    if (truncated_) {
        tcf = ui->teStreamContent->currentCharFormat();
        tcf.setBackground(palette().window().color());
        tcf.setForeground(palette().windowText().color());
        ui->teStreamContent->insertPlainText("\n" + tr("[Stream output truncated]"));
        ui->teStreamContent->moveCursor(QTextCursor::End);
    } else {
        ui->teStreamContent->verticalScrollBar()->setValue(cur_pos);
    }
    setUpdatesEnabled(true);
}

// The following keyboard shortcuts should work (although
// they may not work consistently depending on focus):
// / (slash), Ctrl-F - Focus and highlight the search box
// Ctrl-G, Ctrl-N, F3 - Find next
// Should we make it so that typing any text starts searching?
bool FollowStreamDialog::eventFilter(QObject *, QEvent *event)
{
    if (ui->teStreamContent->hasFocus() && event->type() == QEvent::KeyPress) {
        QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event);
        if (keyEvent->matches(QKeySequence::SelectAll) || keyEvent->matches(QKeySequence::Copy)
                || keyEvent->text().isEmpty()) {
            return false;
        }
        ui->leFind->setFocus();
        if (keyEvent->matches(QKeySequence::Find)) {
            return true;
        } else if (keyEvent->matches(QKeySequence::FindNext)) {
            findText();
            return true;
        }
    }

    return false;
}

void FollowStreamDialog::keyPressEvent(QKeyEvent *event)
{
    if (ui->leFind->hasFocus()) {
        if (event->key() == Qt::Key_Enter || event->key() == Qt::Key_Return) {
            findText();
            return;
        }
    } else {
        if (event->key() == Qt::Key_Slash || event->matches(QKeySequence::Find)) {
            ui->leFind->setFocus();
            ui->leFind->selectAll();
        }
        return;
    }

    if (event->key() == Qt::Key_F3 || (event->key() == Qt::Key_N && event->modifiers() & Qt::ControlModifier)) {
        findText();
        return;
    }

    QDialog::keyPressEvent(event);
}

static inline void sanitize_buffer(char *buffer, size_t nchars) {
    for (size_t i = 0; i < nchars; i++) {
        if (buffer[i] == '\n' || buffer[i] == '\r' || buffer[i] == '\t')
            continue;
        if (! g_ascii_isprint((guchar)buffer[i])) {
            buffer[i] = '.';
        }
    }
}

frs_return_t
FollowStreamDialog::showBuffer(char *buffer, size_t nchars, gboolean is_from_server, guint32 packet_num,
                                nstime_t abs_ts, guint32 *global_pos)
{
    gchar initbuf[256];
    guint32 current_pos;
    static const gchar hexchars[16] = {'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f'};

    switch (recent.gui_follow_show) {

    case SHOW_EBCDIC:
    {
        /* If our native arch is ASCII, call: */
        EBCDIC_to_ASCII((guint8*)buffer, (guint) nchars);
        sanitize_buffer(buffer, nchars);
        QByteArray ba = QByteArray(buffer, (int)nchars);
        addText(ba, is_from_server, packet_num);
        break;
    }

    case SHOW_ASCII:
    {
        /* If our native arch is EBCDIC, call:
         * ASCII_TO_EBCDIC(buffer, nchars);
         */
        sanitize_buffer(buffer, nchars);
        QByteArray ba = QByteArray(buffer, (int)nchars);
        addText(ba, is_from_server, packet_num);
        break;
    }

    case SHOW_CODEC:
    {
        // This assumes that multibyte characters don't span packets in the
        // stream. To handle that case properly (which might occur with fixed
        // block sizes, e.g. transferring over TFTP, we would need to create
        // two stateful QTextDecoders, one for each direction, presumably in
        // on_cbCharset_currentIndexChanged()
        QTextCodec *codec = QTextCodec::codecForName(ui->cbCharset->currentText().toUtf8());
        QByteArray ba = QByteArray(buffer, (int)nchars);
        QString decoded = codec->toUnicode(ba);
        addText(decoded, is_from_server, packet_num);
        break;
    }

    case SHOW_HEXDUMP:
        current_pos = 0;
        while (current_pos < nchars) {
            gchar hexbuf[256];
            int i;
            gchar *cur = hexbuf, *ascii_start;

            /* is_from_server indentation : put 4 spaces at the
             * beginning of the string */
            /* XXX - We might want to prepend each line with "C" or "S" instead. */
            if (is_from_server && follow_info_.show_stream == BOTH_HOSTS) {
                memset(cur, ' ', 4);
                cur += 4;
            }
            cur += snprintf(cur, 20, "%08X  ", *global_pos);
            /* 49 is space consumed by hex chars */
            ascii_start = cur + 49 + 2;
            for (i = 0; i < 16 && current_pos + i < nchars; i++) {
                *cur++ =
                        hexchars[(buffer[current_pos + i] & 0xf0) >> 4];
                *cur++ =
                        hexchars[buffer[current_pos + i] & 0x0f];
                *cur++ = ' ';
                if (i == 7)
                    *cur++ = ' ';
            }
            /* Fill it up if column isn't complete */
            while (cur < ascii_start)
                *cur++ = ' ';

            /* Now dump bytes as text */
            for (i = 0; i < 16 && current_pos + i < nchars; i++) {
                *cur++ =
                        (g_ascii_isprint((guchar)buffer[current_pos + i]) ?
                            buffer[current_pos + i] : '.');
                if (i == 7) {
                    *cur++ = ' ';
                }
            }
            current_pos += i;
            (*global_pos) += i;
            *cur++ = '\n';
            *cur = 0;

            addText(hexbuf, is_from_server, packet_num);
        }
        break;

    case SHOW_CARRAY:
        current_pos = 0;
        snprintf(initbuf, sizeof(initbuf), "char peer%d_%d[] = { /* Packet %u */\n",
                   is_from_server ? 1 : 0,
                   is_from_server ? server_buffer_count_++ : client_buffer_count_++,
                   packet_num);
        addText(initbuf, is_from_server, packet_num);

        while (current_pos < nchars) {
            gchar hexbuf[256];
            int i, cur;

            cur = 0;
            for (i = 0; i < 8 && current_pos + i < nchars; i++) {
                /* Prepend entries with "0x" */
                hexbuf[cur++] = '0';
                hexbuf[cur++] = 'x';
                hexbuf[cur++] =
                        hexchars[(buffer[current_pos + i] & 0xf0) >> 4];
                hexbuf[cur++] =
                        hexchars[buffer[current_pos + i] & 0x0f];

                /* Delimit array entries with a comma */
                if (current_pos + i + 1 < nchars)
                    hexbuf[cur++] = ',';

                hexbuf[cur++] = ' ';
            }

            /* Terminate the array if we are at the end */
            if (current_pos + i == nchars) {
                hexbuf[cur++] = '}';
                hexbuf[cur++] = ';';
            }

            current_pos += i;
            (*global_pos) += i;
            hexbuf[cur++] = '\n';
            hexbuf[cur] = 0;
            addText(hexbuf, is_from_server, packet_num);
        }
        break;

    case SHOW_YAML:
    {
        QString yaml_text;

        const int base64_raw_len = 57; // Encodes to 76 bytes, common in RFCs
        current_pos = 0;

        if (last_packet_ == 0) {
            // Header with general info about peers
            const char *hostname0 = address_to_name(&follow_info_.client_ip);
            const char *hostname1 = address_to_name(&follow_info_.server_ip);

            char *port0 = get_follow_port_to_display(follower_)(NULL, follow_info_.client_port);
            char *port1 = get_follow_port_to_display(follower_)(NULL, follow_info_.server_port);

            addText("peers:\n", false, 0, false);

            addText(QString(
                "  - peer: 0\n"
                "    host: %1\n"
                "    port: %2\n")
                .arg(hostname0)
                .arg(port0), false, 0);

            addText(QString(
                "  - peer: 1\n"
                "    host: %1\n"
                "    port: %2\n")
                .arg(hostname1)
                .arg(port1), true, 0);

            wmem_free(NULL, port0);
            wmem_free(NULL, port1);

            addText("packets:\n", false, 0, false);
        }

        if (packet_num != last_packet_) {
            yaml_text.append(QString("  - packet: %1\n")
                    .arg(packet_num));
            yaml_text.append(QString("    peer: %1\n")
                    .arg(is_from_server ? 1 : 0));
            yaml_text.append(QString("    index: %1\n")
                    .arg(is_from_server ? server_buffer_count_++ : client_buffer_count_++));
            yaml_text.append(QString("    timestamp: %1.%2\n")
                    .arg(abs_ts.secs)
                    .arg(abs_ts.nsecs, 9, 10, QChar('0')));
            yaml_text.append(QString("    data: !!binary |\n"));
        }
        while (current_pos < nchars) {
            int len = current_pos + base64_raw_len < nchars ? base64_raw_len : (int) nchars - current_pos;
            QByteArray base64_data(&buffer[current_pos], len);

            /* XXX: GCC 12.1 has a bogus stringop-overread warning using the Qt
             * conversions from QByteArray to QString at -O2 and higher due to
             * computing a branch that will never be taken.
             */
#if WS_IS_AT_LEAST_GNUC_VERSION(12,1)
DIAG_OFF(stringop-overread)
#endif
            yaml_text += "      " + base64_data.toBase64() + "\n";
#if WS_IS_AT_LEAST_GNUC_VERSION(12,1)
DIAG_ON(stringop-overread)
#endif

            current_pos += len;
            (*global_pos) += len;
        }
        addText(yaml_text, is_from_server, packet_num);
        break;
    }

    case SHOW_RAW:
    {
        QByteArray ba = QByteArray(buffer, (int)nchars).toHex();
        ba += '\n';
        addText(ba, is_from_server, packet_num);
        break;
    }

    default:
        /* The other Show types are supported in Show Packet Bytes but
         * not here in Follow. (XXX: Maybe some could be added?)
         */
        ws_assert_not_reached();
    }

    if (last_packet_ == 0) {
        last_from_server_ = is_from_server;
    }

    if (packet_num != last_packet_) {
        last_packet_ = packet_num;
        if (is_from_server) {
            server_packet_count_++;
        } else {
            client_packet_count_++;
        }
        if (last_from_server_ != is_from_server) {
            last_from_server_ = is_from_server;
            turns_++;
        }
    }

    return FRS_OK;
}

bool FollowStreamDialog::follow(QString previous_filter, bool use_stream_index, guint stream_num, guint sub_stream_num)
{
    QString             follow_filter;
    const char          *hostname0 = NULL, *hostname1 = NULL;
    char                *port0 = NULL, *port1 = NULL;
    QString             server_to_client_string;
    QString             client_to_server_string;
    QString             both_directions_string;
    gboolean            is_follower = FALSE;
    int                 stream_count;
    follow_stream_count_func stream_count_func = NULL;

    resetStream();

    if (file_closed_)
    {
        QMessageBox::warning(this, tr("No capture file."), tr("Please make sure you have a capture file opened."));
        return false;
    }

    if (!use_stream_index) {
        if (cap_file_.capFile()->edt == NULL)
        {
            QMessageBox::warning(this, tr("Error following stream."), tr("Capture file invalid."));
            return false;
        }
        is_follower = proto_is_frame_protocol(cap_file_.capFile()->edt->pi.layers, proto_get_protocol_filter_name(get_follow_proto_id(follower_)));
        if (!is_follower) {
            QMessageBox::warning(this, tr("Error following stream."), tr("Please make sure you have a %1 packet selected.").arg
                                    (proto_get_protocol_short_name(find_protocol_by_id(get_follow_proto_id(follower_)))));
            return false;
        }
    }

    follow_reset_stream(&follow_info_);

    /* Create a new filter that matches all packets in the TCP stream,
        and set the display filter entry accordingly */
    if (use_stream_index) {
        follow_filter = gchar_free_to_qstring(get_follow_index_func(follower_)(stream_num, sub_stream_num));
    } else {
        follow_filter = gchar_free_to_qstring(get_follow_conv_func(follower_)(cap_file_.capFile()->edt, &cap_file_.capFile()->edt->pi, &stream_num, &sub_stream_num));
    }
    if (follow_filter.isEmpty()) {
        // XXX: This error probably has to do with tunneling (#18231), where
        // the addresses or ports changed after the TCP or UDP layer.
        // (The appropriate layer must be present, or else the GUI
        // doesn't allow the option to be selected.)
        QMessageBox::warning(this,
                             tr("Error creating filter for this stream."),
                             tr("%1 stream not found on the selected packet.").arg(proto_get_protocol_short_name(find_protocol_by_id(get_follow_proto_id(follower_)))));
        return false;
    }

    previous_filter_ = previous_filter;
    /* append the negation */
    if (!previous_filter.isEmpty()) {
        filter_out_filter_ = QString("%1 and !(%2)")
                .arg(previous_filter).arg(follow_filter);
    }
    else
    {
        filter_out_filter_ = QString("!(%1)").arg(follow_filter);
    }

    follow_info_.substream_id = sub_stream_num;

    /* data will be passed via tap callback*/
    if (!registerTapListener(get_follow_tap_string(follower_), &follow_info_,
                                follow_filter.toUtf8().constData(),
                                0, NULL, get_follow_tap_handler(follower_), NULL)) {
        return false;
    }

    stream_count_func = get_follow_stream_count_func(follower_);

    if (stream_count_func == NULL) {
        removeStreamControls();
    } else {
        stream_count = stream_count_func();
        ui->streamNumberSpinBox->blockSignals(true);
        ui->streamNumberSpinBox->setMaximum(stream_count-1);
        ui->streamNumberSpinBox->setValue(stream_num);
        ui->streamNumberSpinBox->blockSignals(false);
        ui->streamNumberSpinBox->setToolTip(tr("%Ln total stream(s).", "", stream_count));
        ui->streamNumberLabel->setToolTip(ui->streamNumberSpinBox->toolTip());
    }

    follow_sub_stream_id_func sub_stream_func;
    sub_stream_func = get_follow_sub_stream_id_func(follower_);
    if (sub_stream_func != NULL) {
        guint substream_max_id = 0;
        sub_stream_func(static_cast<guint>(stream_num), G_MAXINT32, TRUE, &substream_max_id);
        stream_count = static_cast<gint>(substream_max_id);
        ui->subStreamNumberSpinBox->blockSignals(true);
        ui->subStreamNumberSpinBox->setEnabled(true);
        ui->subStreamNumberSpinBox->setMaximum(stream_count);
        ui->subStreamNumberSpinBox->setValue(sub_stream_num);
        ui->subStreamNumberSpinBox->blockSignals(false);
        ui->subStreamNumberSpinBox->setToolTip(tr("Max sub stream ID for the selected stream: %Ln", "", stream_count));
        ui->subStreamNumberSpinBox->setToolTip(ui->subStreamNumberSpinBox->toolTip());
        ui->subStreamNumberSpinBox->setVisible(true);
        ui->subStreamNumberLabel->setVisible(true);
    } else {
        /* disable substream spin box for protocols without substreams */
        ui->subStreamNumberSpinBox->blockSignals(true);
        ui->subStreamNumberSpinBox->setEnabled(false);
        ui->subStreamNumberSpinBox->setValue(0);
        ui->subStreamNumberSpinBox->setKeyboardTracking(false);
        ui->subStreamNumberSpinBox->blockSignals(false);
        ui->subStreamNumberSpinBox->setVisible(false);
        ui->subStreamNumberLabel->setVisible(false);
    }

    beginRetapPackets();
    updateWidgets(true);

    /* Run the display filter so it goes in effect - even if it's the
       same as the previous display filter. */
    emit updateFilter(follow_filter, TRUE);

    removeTapListeners();

    hostname0 = address_to_name(&follow_info_.client_ip);
    hostname1 = address_to_name(&follow_info_.server_ip);

    port0 = get_follow_port_to_display(follower_)(NULL, follow_info_.client_port);
    port1 = get_follow_port_to_display(follower_)(NULL, follow_info_.server_port);

    server_to_client_string =
            QString("%1:%2 %3 %4:%5 (%6)")
            .arg(hostname0).arg(port0)
            .arg(UTF8_RIGHTWARDS_ARROW)
            .arg(hostname1).arg(port1)
            .arg(gchar_free_to_qstring(format_size(
                                            follow_info_.bytes_written[0],
                                        FORMAT_SIZE_UNIT_BYTES, FORMAT_SIZE_PREFIX_SI)));

    client_to_server_string =
            QString("%1:%2 %3 %4:%5 (%6)")
            .arg(hostname1).arg(port1)
            .arg(UTF8_RIGHTWARDS_ARROW)
            .arg(hostname0).arg(port0)
            .arg(gchar_free_to_qstring(format_size(
                                            follow_info_.bytes_written[1],
                                        FORMAT_SIZE_UNIT_BYTES, FORMAT_SIZE_PREFIX_SI)));

    wmem_free(NULL, port0);
    wmem_free(NULL, port1);

    both_directions_string = tr("Entire conversation (%1)")
            .arg(gchar_free_to_qstring(format_size(
                                            follow_info_.bytes_written[0] + follow_info_.bytes_written[1],
                    FORMAT_SIZE_UNIT_BYTES, FORMAT_SIZE_PREFIX_SI)));
    setWindowSubtitle(tr("Follow %1 Stream (%2)").arg(proto_get_protocol_short_name(find_protocol_by_id(get_follow_proto_id(follower_))))
                                                 .arg(follow_filter));

    ui->cbDirections->blockSignals(true);
    ui->cbDirections->clear();
    ui->cbDirections->addItem(both_directions_string);
    ui->cbDirections->addItem(client_to_server_string);
    ui->cbDirections->addItem(server_to_client_string);
    ui->cbDirections->blockSignals(false);

    followStream();
    fillHintLabel(-1);

    updateWidgets(false);
    endRetapPackets();

    if (prefs.restore_filter_after_following_stream) {
        emit updateFilter(previous_filter_, TRUE);
    }

    return true;
}

void FollowStreamDialog::captureFileClosed()
{
    QString tooltip = tr("File closed.");
    ui->streamNumberSpinBox->setToolTip(tooltip);
    ui->streamNumberLabel->setToolTip(tooltip);
    WiresharkDialog::captureFileClosed();
}

/*
 * XXX - the routine pointed to by "print_line_fcn_p" doesn't get handed lines,
 * it gets handed bufferfuls.  That's fine for "follow_write_raw()"
 * and "follow_add_to_gtk_text()", but, as "follow_print_text()" calls
 * the "print_line()" routine from "print.c", and as that routine might
 * genuinely expect to be handed a line (if, for example, it's using
 * some OS or desktop environment's printing API, and that API expects
 * to be handed lines), "follow_print_text()" should probably accumulate
 * lines in a buffer and hand them "print_line()".  (If there's a
 * complete line in a buffer - i.e., there's nothing of the line in
 * the previous buffer or the next buffer - it can just hand that to
 * "print_line()" after filtering out non-printables, as an
 * optimization.)
 *
 * This might or might not be the reason why C arrays display
 * correctly but get extra blank lines very other line when printed.
 */
frs_return_t
FollowStreamDialog::readFollowStream()
{
    guint32 global_client_pos = 0, global_server_pos = 0;
    guint32 *global_pos;
    gboolean skip;
    GList* cur;
    frs_return_t frs_return;
    follow_record_t *follow_record;
    QElapsedTimer elapsed_timer;

    elapsed_timer.start();

    loop_break_mutex.lock();
    isReadRunning = TRUE;
    loop_break_mutex.unlock();

    for (cur = g_list_last(follow_info_.payload); cur; cur = g_list_previous(cur)) {
        if (dialogClosed() || !isReadRunning) break;

        follow_record = (follow_record_t *)cur->data;
        skip = FALSE;
        if (!follow_record->is_server) {
            global_pos = &global_client_pos;
            if (follow_info_.show_stream == FROM_SERVER) {
                skip = TRUE;
            }
        } else {
            global_pos = &global_server_pos;
            if (follow_info_.show_stream == FROM_CLIENT) {
                skip = TRUE;
            }
        }

        QByteArray buffer;
        if (!skip) {
            // We want a deep copy.
            buffer.clear();
            buffer.append((const char *) follow_record->data->data,
                                     follow_record->data->len);
            frs_return = showBuffer(
                        buffer.data(),
                        follow_record->data->len,
                        follow_record->is_server,
                        follow_record->packet_num,
                        follow_record->abs_ts,
                        global_pos);
            if (frs_return == FRS_PRINT_ERROR)
                return frs_return;
            if (elapsed_timer.elapsed() > info_update_freq_) {
                fillHintLabel(ui->teStreamContent->textCursor().position());
                mainApp->processEvents();
                elapsed_timer.start();
            }
        }
    }

    loop_break_mutex.lock();
    isReadRunning = FALSE;
    loop_break_mutex.unlock();

    return FRS_OK;
}