/*
    This file is part of the KDE project
    SPDX-FileCopyrightText: 2000 Alex Zepeda <zipzippy@sonic.net>
    SPDX-FileCopyrightText: 2001-2003 George Staikos <staikos@kde.org>
    SPDX-FileCopyrightText: 2001 Dawit Alemayehu <adawit@kde.org>
    SPDX-FileCopyrightText: 2007, 2008 Andreas Hartmetz <ahartmetz@gmail.com>
    SPDX-FileCopyrightText: 2008 Roland Harnau <tau@gmx.eu>
    SPDX-FileCopyrightText: 2010 Richard Moore <rich@kde.org>

    SPDX-License-Identifier: LGPL-2.0-or-later
*/

#include "tcpslavebase.h"
#include "kiocoredebug.h"

#include <KConfigGroup>
#include <KLocalizedString>
#include <ksslcertificatemanager.h>
#include <ksslsettings.h>

#include <QSslCipher>
#include <QSslSocket>

#include <QDBusConnection>

using namespace KIO;
// using namespace KNetwork;

namespace KIO
{
Q_DECLARE_OPERATORS_FOR_FLAGS(TCPSlaveBase::SslResult)
}

// TODO Proxy support whichever way works; KPAC reportedly does *not* work.
// NOTE kded_proxyscout may or may not be interesting

// TODO resurrect SSL session recycling; this means save the session on disconnect and look
// for a reusable session on connect. Consider how HTTP persistent connections interact with that.

// TODO in case we support SSL-lessness we need static KTcpSocket::sslAvailable() and check it
// in most places we ATM check for d->isSSL.

// TODO check if d->isBlocking is honored everywhere it makes sense

// TODO fold KSSLSetting and KSSLCertificateHome into KSslSettings and use that everywhere.

// TODO recognize partially encrypted websites as "somewhat safe"

/* List of dialogs/messageboxes we need to use (current code location in parentheses)
   - Can the "dontAskAgainName" thing be improved?

   - "SSLCertDialog" [select client cert] (SlaveInterface)
   - Enter password for client certificate (inline)
   - Password for client cert was wrong. Please reenter. (inline)
   - Setting client cert failed. [doesn't give reason] (inline)
   - "SSLInfoDialog" [mostly server cert info] (SlaveInterface)
   - You are about to enter secure mode. Security information/Display SSL information/Connect (inline)
   - You are about to leave secure mode. Security information/Continue loading/Abort (inline)
   - Hostname mismatch: Continue/Details/Cancel (inline)
   - IP address mismatch: Continue/Details/Cancel (inline)
   - Certificate failed authenticity check: Continue/Details/Cancel (inline)
   - Would you like to accept this certificate forever: Yes/No/Current sessions only (inline)
 */

/** @internal */
class Q_DECL_HIDDEN TCPSlaveBase::TcpSlaveBasePrivate
{
public:
    explicit TcpSlaveBasePrivate(TCPSlaveBase *qq)
        : q(qq)
    {
    }

    void setSslMetaData()
    {
        sslMetaData.insert(QStringLiteral("ssl_in_use"), QStringLiteral("TRUE"));
        QSslCipher cipher = socket.sessionCipher();
        sslMetaData.insert(QStringLiteral("ssl_protocol_version"), cipher.protocolString());
        sslMetaData.insert(QStringLiteral("ssl_cipher"), cipher.name());
        sslMetaData.insert(QStringLiteral("ssl_cipher_used_bits"), QString::number(cipher.usedBits()));
        sslMetaData.insert(QStringLiteral("ssl_cipher_bits"), QString::number(cipher.supportedBits()));
        sslMetaData.insert(QStringLiteral("ssl_peer_ip"), ip);

        const QList<QSslCertificate> peerCertificateChain = socket.peerCertificateChain();
        // try to fill in the blanks, i.e. missing certificates, and just assume that
        // those belong to the peer (==website or similar) certificate.
        for (int i = 0; i < sslErrors.count(); i++) {
            if (sslErrors[i].certificate().isNull()) {
                sslErrors[i] = QSslError(sslErrors[i].error(), peerCertificateChain[0]);
            }
        }

        QString errorStr;
        // encode the two-dimensional numeric error list using '\n' and '\t' as outer and inner separators
        for (const QSslCertificate &cert : peerCertificateChain) {
            for (const QSslError &error : std::as_const(sslErrors)) {
                if (error.certificate() == cert) {
                    errorStr += QString::number(static_cast<int>(error.error())) + QLatin1Char('\t');
                }
            }
            if (errorStr.endsWith(QLatin1Char('\t'))) {
                errorStr.chop(1);
            }
            errorStr += QLatin1Char('\n');
        }
        errorStr.chop(1);
        sslMetaData.insert(QStringLiteral("ssl_cert_errors"), errorStr);

        QString peerCertChain;
        for (const QSslCertificate &cert : peerCertificateChain) {
            peerCertChain += QString::fromUtf8(cert.toPem()) + QLatin1Char('\x01');
        }
        peerCertChain.chop(1);
        sslMetaData.insert(QStringLiteral("ssl_peer_chain"), peerCertChain);
        sendSslMetaData();
    }

    void clearSslMetaData()
    {
        sslMetaData.clear();
        sslMetaData.insert(QStringLiteral("ssl_in_use"), QStringLiteral("FALSE"));
        sendSslMetaData();
    }

    void sendSslMetaData()
    {
        MetaData::ConstIterator it = sslMetaData.constBegin();
        for (; it != sslMetaData.constEnd(); ++it) {
            q->setMetaData(it.key(), it.value());
        }
    }

    SslResult startTLSInternal(QSsl::SslProtocol sslVersion, int waitForEncryptedTimeout = -1);

    TCPSlaveBase *const q;

    bool isBlocking;

    QSslSocket socket;

    QString host;
    QString ip;
    quint16 port;
    QByteArray serviceName;

    KSSLSettings sslSettings;
    bool usingSSL;
    bool autoSSL;
    bool sslNoUi; // If true, we just drop the connection silently
    // if SSL certificate check fails in some way.
    QList<QSslError> sslErrors;

    MetaData sslMetaData;
};

#if KIOCORE_BUILD_DEPRECATED_SINCE(5, 83)
QIODevice *TCPSlaveBase::socket() const
{
    return &d->socket;
}
#endif

QAbstractSocket *TCPSlaveBase::tcpSocket() const
{
    return &d->socket;
}

TCPSlaveBase::TCPSlaveBase(const QByteArray &protocol, const QByteArray &poolSocket, const QByteArray &appSocket, bool autoSSL)
    : SlaveBase(protocol, poolSocket, appSocket)
    , d(new TcpSlaveBasePrivate(this))
{
    d->isBlocking = true;
    d->port = 0;
    d->serviceName = protocol;
    d->usingSSL = false;
    d->autoSSL = autoSSL;
    d->sslNoUi = false;
    // Limit the read buffer size to 14 MB (14*1024*1024) (based on the upload limit
    // in TransferJob::slotDataReq). See the docs for QAbstractSocket::setReadBufferSize
    // and the BR# 187876 to understand why setting this limit is necessary.
    d->socket.setReadBufferSize(14680064);
}

TCPSlaveBase::~TCPSlaveBase()
{
    delete d;
}

ssize_t TCPSlaveBase::write(const char *data, ssize_t len)
{
    ssize_t written = d->socket.write(data, len);
    if (written == -1) {
        /*qDebug() << "d->socket.write() returned -1! Socket error is"
          << d->socket.error() << ", Socket state is" << d->socket.state();*/
    }

    bool success = false;
    if (d->isBlocking) {
        // Drain the tx buffer
        success = d->socket.waitForBytesWritten(-1);
    } else {
        // ### I don't know how to make sure that all data does get written at some point
        // without doing it now. There is no event loop to do it behind the scenes.
        // Polling in the dispatch() loop? Something timeout based?
        success = d->socket.waitForBytesWritten(0);
    }

    d->socket.flush(); // this is supposed to get the data on the wire faster

    if (d->socket.state() != QAbstractSocket::ConnectedState || !success) {
        /*qDebug() << "Write failed, will return -1! Socket error is"
          << d->socket.error() << ", Socket state is" << d->socket.state()
          << "Return value of waitForBytesWritten() is" << success;*/
        return -1;
    }

    return written;
}

ssize_t TCPSlaveBase::read(char *data, ssize_t len)
{
    if (d->usingSSL && (d->socket.mode() != QSslSocket::SslClientMode)) {
        d->clearSslMetaData();
        // qDebug() << "lost SSL connection.";
        return -1;
    }

    if (!d->socket.bytesAvailable()) {
        const int timeout = d->isBlocking ? -1 : (readTimeout() * 1000);
        d->socket.waitForReadyRead(timeout);
    }
    return d->socket.read(data, len);
}

ssize_t TCPSlaveBase::readLine(char *data, ssize_t len)
{
    if (d->usingSSL && (d->socket.mode() != QSslSocket::SslClientMode)) {
        d->clearSslMetaData();
        // qDebug() << "lost SSL connection.";
        return -1;
    }

    const int timeout = (d->isBlocking ? -1 : (readTimeout() * 1000));
    ssize_t readTotal = 0;
    do {
        if (!d->socket.bytesAvailable()) {
            d->socket.waitForReadyRead(timeout);
        }
        ssize_t readStep = d->socket.readLine(&data[readTotal], len - readTotal);
        if (readStep == -1 || (readStep == 0 && d->socket.state() != QAbstractSocket::ConnectedState)) {
            return -1;
        }
        readTotal += readStep;
    } while (readTotal == 0 || data[readTotal - 1] != '\n');

    return readTotal;
}

bool TCPSlaveBase::connectToHost(const QString & /*protocol*/, const QString &host, quint16 port)
{
    QString errorString;
    const int errCode = connectToHost(host, port, &errorString);
    if (errCode == 0) {
        return true;
    }

    error(errCode, errorString);
    return false;
}

int TCPSlaveBase::connectToHost(const QString &host, quint16 port, QString *errorString)
{
    d->clearSslMetaData(); // We have separate connection and SSL setup phases

    if (errorString) {
        errorString->clear(); // clear prior error messages.
    }

    d->socket.setPeerVerifyName(host); // Used for ssl certificate verification (SNI)

    //  - leaving SSL - warn before we even connect
    //### see if it makes sense to move this into the HTTP ioslave which is the only
    //    user.
    if (metaData(QStringLiteral("main_frame_request")) == QLatin1String("TRUE") //### this looks *really* unreliable
        && metaData(QStringLiteral("ssl_activate_warnings")) == QLatin1String("TRUE") && metaData(QStringLiteral("ssl_was_in_use")) == QLatin1String("TRUE")
        && !d->autoSSL) {
        if (d->sslSettings.warnOnLeave()) {
            int result = messageBox(i18n("You are about to leave secure "
                                         "mode. Transmissions will no "
                                         "longer be encrypted.\nThis "
                                         "means that a third party could "
                                         "observe your data in transit."),
                                    WarningContinueCancel,
                                    i18n("Security Information"),
                                    i18n("C&ontinue Loading"),
                                    QString(),
                                    QStringLiteral("WarnOnLeaveSSLMode"));

            if (result == SlaveBase::Cancel) {
                if (errorString) {
                    *errorString = host;
                }
                return ERR_USER_CANCELED;
            }
        }
    }

    const int timeout = (connectTimeout() * 1000); // 20 sec timeout value

    disconnectFromHost(); // Reset some state, even if we are already disconnected
    d->host = host;

    d->socket.connectToHost(host, port);
    /*const bool connectOk = */ d->socket.waitForConnected(timeout > -1 ? timeout : -1);

    /*qDebug() << "Socket: state=" << d->socket.state()
        << ", error=" << d->socket.error()
        << ", connected?" << connectOk;*/

    if (d->socket.state() != QAbstractSocket::ConnectedState) {
        if (errorString) {
            *errorString = host + QLatin1String(": ") + d->socket.errorString();
        }
        switch (d->socket.error()) {
        case QAbstractSocket::UnsupportedSocketOperationError:
            return ERR_UNSUPPORTED_ACTION;
        case QAbstractSocket::RemoteHostClosedError:
            return ERR_CONNECTION_BROKEN;
        case QAbstractSocket::SocketTimeoutError:
            return ERR_SERVER_TIMEOUT;
        case QAbstractSocket::HostNotFoundError:
            return ERR_UNKNOWN_HOST;
        default:
            return ERR_CANNOT_CONNECT;
        }
    }

    //### check for proxyAuthenticationRequiredError

    d->ip = d->socket.peerAddress().toString();
    d->port = d->socket.peerPort();

    if (d->autoSSL) {
        const SslResult res = d->startTLSInternal(QSsl::SecureProtocols, timeout);

        if (res & ResultFailed) {
            if (errorString) {
                *errorString = i18nc("%1 is a host name", "%1: SSL negotiation failed", host);
            }
            return ERR_CANNOT_CONNECT;
        }
    }
    return 0;
}

void TCPSlaveBase::disconnectFromHost()
{
    // qDebug();
    d->host.clear();
    d->ip.clear();
    d->usingSSL = false;

    if (d->socket.state() == QAbstractSocket::UnconnectedState) {
        // discard incoming data - the remote host might have disconnected us in the meantime
        // but the visible effect of disconnectFromHost() should stay the same.
        d->socket.close();
        return;
    }

    //### maybe save a session for reuse on SSL shutdown if and when QSslSocket
    //    does that. QCA::TLS can do it apparently but that is not enough if
    //    we want to present that as KDE API. Not a big loss in any case.
    d->socket.disconnectFromHost();
    if (d->socket.state() != QAbstractSocket::UnconnectedState) {
        d->socket.waitForDisconnected(-1); // wait for unsent data to be sent
    }
    d->socket.close(); // whatever that means on a socket
}

bool TCPSlaveBase::isAutoSsl() const
{
    return d->autoSSL;
}

bool TCPSlaveBase::isUsingSsl() const
{
    return d->usingSSL;
}

quint16 TCPSlaveBase::port() const
{
    return d->port;
}

bool TCPSlaveBase::atEnd() const
{
    return d->socket.atEnd();
}

bool TCPSlaveBase::startSsl()
{
    if (d->usingSSL) {
        return false;
    }
    return d->startTLSInternal(QSsl::SecureProtocols) & ResultOk;
}

TCPSlaveBase::SslResult TCPSlaveBase::TcpSlaveBasePrivate::startTLSInternal(QSsl::SslProtocol sslVersion, int waitForEncryptedTimeout)
{
    // setMetaData("ssl_session_id", d->kssl->session()->toString());
    //### we don't support session reuse for now...
    usingSSL = true;

    // Set the SSL protocol version to use...
    socket.setProtocol(sslVersion);

    /* Usually ignoreSslErrors() would be called in the slot invoked by the sslErrors()
       signal but that would mess up the flow of control. We will check for errors
       anyway to decide if we want to continue connecting. Otherwise ignoreSslErrors()
       before connecting would be very insecure. */
    socket.ignoreSslErrors();
    socket.startClientEncryption();
    const bool encryptionStarted = socket.waitForEncrypted(waitForEncryptedTimeout);

    // Set metadata, among other things for the "SSL Details" dialog
    QSslCipher cipher = socket.sessionCipher();

    if (!encryptionStarted || socket.mode() != QSslSocket::SslClientMode || cipher.isNull() || cipher.usedBits() == 0
        || socket.peerCertificateChain().isEmpty()) {
        usingSSL = false;
        clearSslMetaData();
        /*qDebug() << "Initial SSL handshake failed. encryptionStarted is"
          << encryptionStarted << ", cipher.isNull() is" << cipher.isNull()
          << ", cipher.usedBits() is" << cipher.usedBits()
          << ", length of certificate chain is" << socket.peerCertificateChain().count()
          << ", the socket says:" << socket.errorString()
          << "and the list of SSL errors contains"
          << socket.sslErrors().count() << "items.";*/
        /*for (const QSslError &sslError : socket.sslErrors()) {
          qDebug() << "SSL ERROR: (" << sslError.error() << ")" << sslError.errorString();
          }*/
        return ResultFailed | ResultFailedEarly;
    }

    /*qDebug() << "Cipher info - "
      << " advertised SSL protocol version" << socket.protocol()
      << " negotiated SSL protocol version" << socket.sessionProtocol()
      << " authenticationMethod:" << cipher.authenticationMethod()
      << " encryptionMethod:" << cipher.encryptionMethod()
      << " keyExchangeMethod:" << cipher.keyExchangeMethod()
      << " name:" << cipher.name()
      << " supportedBits:" << cipher.supportedBits()
      << " usedBits:" << cipher.usedBits();*/

    sslErrors = socket.sslHandshakeErrors();

    // TODO: review / rewrite / remove the comment
    // The app side needs the metadata now for the SSL error dialog (if any) but
    // the same metadata will be needed later, too. When "later" arrives the slave
    // may actually be connected to a different application that doesn't know
    // the metadata the slave sent to the previous application.
    // The quite important SSL indicator icon in Konqi's URL bar relies on metadata
    // from here, for example. And Konqi will be the second application to connect
    // to the slave.
    // Therefore we choose to have our metadata and send it, too :)
    setSslMetaData();
    q->sendAndKeepMetaData();

    SslResult rc = q->verifyServerCertificate();
    if (rc & ResultFailed) {
        usingSSL = false;
        clearSslMetaData();
        // qDebug() << "server certificate verification failed.";
        socket.disconnectFromHost(); // Make the connection fail (cf. ignoreSslErrors())
        return ResultFailed;
    } else if (rc & ResultOverridden) {
        // qDebug() << "server certificate verification failed but continuing at user's request.";
    }

    //"warn" when starting SSL/TLS
    if (q->metaData(QStringLiteral("ssl_activate_warnings")) == QLatin1String("TRUE") && q->metaData(QStringLiteral("ssl_was_in_use")) == QLatin1String("FALSE")
        && sslSettings.warnOnEnter()) {
        int msgResult = q->messageBox(i18n("You are about to enter secure mode. "
                                           "All transmissions will be encrypted "
                                           "unless otherwise noted.\nThis means "
                                           "that no third party will be able to "
                                           "easily observe your data in transit."),
                                      WarningYesNo,
                                      i18n("Security Information"),
                                      i18n("Display SSL &Information"),
                                      i18n("C&onnect"),
                                      QStringLiteral("WarnOnEnterSSLMode"));
        if (msgResult == SlaveBase::Yes) {
            q->messageBox(SSLMessageBox /*==the SSL info dialog*/, host);
        }
    }

    return rc;
}

TCPSlaveBase::SslResult TCPSlaveBase::verifyServerCertificate()
{
    d->sslNoUi = hasMetaData(QStringLiteral("ssl_no_ui")) && (metaData(QStringLiteral("ssl_no_ui")) != QLatin1String("FALSE"));

    if (d->sslErrors.isEmpty()) {
        return ResultOk;
    } else if (d->sslNoUi) {
        return ResultFailed;
    }

    const QList<QSslError> fatalErrors = KSslCertificateManager::nonIgnorableErrors(d->sslErrors);
    if (!fatalErrors.isEmpty()) {
        // TODO message "sorry, fatal error, you can't override it"
        return ResultFailed;
    }
    QList<QSslCertificate> peerCertificationChain = d->socket.peerCertificateChain();
    KSslCertificateManager *const cm = KSslCertificateManager::self();
    KSslCertificateRule rule = cm->rule(peerCertificationChain.first(), d->host);

    // remove previously seen and acknowledged errors
    const QList<QSslError> remainingErrors = rule.filterErrors(d->sslErrors);
    if (remainingErrors.isEmpty()) {
        // qDebug() << "Error list empty after removing errors to be ignored. Continuing.";
        return ResultOk | ResultOverridden;
    }

    //### We don't ask to permanently reject the certificate

    QString message = i18n("The server failed the authenticity check (%1).\n\n", d->host);
    for (const QSslError &err : std::as_const(d->sslErrors)) {
        message += err.errorString() + QLatin1Char('\n');
    }
    message = message.trimmed();

    int msgResult;
    QDateTime ruleExpiry = QDateTime::currentDateTime();
    do {
        msgResult = messageBox(WarningYesNoCancel, message, i18n("Server Authentication"), i18n("&Details"), i18n("Co&ntinue"));
        switch (msgResult) {
        case SlaveBase::Yes:
            // Details was chosen- show the certificate and error details
            messageBox(SSLMessageBox /*the SSL info dialog*/, d->host);
            break;
        case SlaveBase::No: {
            // fall through on SlaveBase::No
            const int result = messageBox(WarningYesNoCancel,
                                          i18n("Would you like to accept this "
                                               "certificate forever without "
                                               "being prompted?"),
                                          i18n("Server Authentication"),
                                          i18n("&Forever"),
                                          i18n("&Current Session only"));
            if (result == SlaveBase::Yes) {
                // accept forever ("for a very long time")
                ruleExpiry = ruleExpiry.addYears(1000);
            } else if (result == SlaveBase::No) {
                // accept "for a short time", half an hour.
                ruleExpiry = ruleExpiry.addSecs(30 * 60);
            } else {
                msgResult = SlaveBase::Yes;
            }
            break;
        }
        case SlaveBase::Cancel:
            return ResultFailed;
        default:
            qCWarning(KIO_CORE) << "Unexpected MessageBox response received:" << msgResult;
            return ResultFailed;
        }
    } while (msgResult == SlaveBase::Yes);

    // TODO special cases for wildcard domain name in the certificate!
    // rule = KSslCertificateRule(d->socket.peerCertificateChain().first(), whatever);

    rule.setExpiryDateTime(ruleExpiry);
    rule.setIgnoredErrors(d->sslErrors);
    cm->setRule(rule);

    return ResultOk | ResultOverridden;
}

bool TCPSlaveBase::isConnected() const
{
    // QSslSocket::isValid() is shady...
    return d->socket.state() == QAbstractSocket::ConnectedState;
}

bool TCPSlaveBase::waitForResponse(int t)
{
    if (d->socket.bytesAvailable()) {
        return true;
    }
    return d->socket.waitForReadyRead(t * 1000);
}

void TCPSlaveBase::setBlocking(bool b)
{
    if (!b) {
        qCWarning(KIO_CORE) << "Caller requested non-blocking mode, but that doesn't work";
        return;
    }
    d->isBlocking = b;
}

void TCPSlaveBase::virtual_hook(int id, void *data)
{
    if (id == SlaveBase::AppConnectionMade) {
        d->sendSslMetaData();
    } else {
        SlaveBase::virtual_hook(id, data);
    }
}
