/*
 * tlshandler.cpp - abstract wrapper for TLS
 * Copyright (C) 2003  Justin Karneges
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library.  If not, see <https://www.gnu.org/licenses/>.
 *
 */

#include "qca.h"
#include "xmpp.h"

#include <qtimer.h>
#include <qurl.h>

using namespace XMPP;
// FIXME: remove this code once qca cert host checking works ...
using namespace QCA;

// ip address string to binary (msb), adapted from jdns (adapted from qt)
// return: size 4 = ipv4, size 16 = ipv6, size 0 = error
static QByteArray ipaddr_str2bin(const QString &str)
{
    // ipv6
    if (str.contains(':')) {
#if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0)
        QStringList parts = str.split(':', Qt::KeepEmptyParts);
#else
        QStringList parts = str.split(':', QString::KeepEmptyParts);
#endif
        if (parts.count() < 3 || parts.count() > 8)
            return QByteArray();

        QByteArray ipv6(16, 0);
        int        at   = 16;
        int        fill = 9 - parts.count();
        for (int n = parts.count() - 1; n >= 0; --n) {
            if (at <= 0)
                return QByteArray();

            if (parts[n].isEmpty()) {
                if (n == parts.count() - 1) {
                    if (!parts[n - 1].isEmpty())
                        return QByteArray();
                    ipv6[--at] = 0;
                    ipv6[--at] = 0;
                } else if (n == 0) {
                    if (!parts[n + 1].isEmpty())
                        return QByteArray();
                    ipv6[--at] = 0;
                    ipv6[--at] = 0;
                } else {
                    for (int i = 0; i < fill; ++i) {
                        if (at <= 0)
                            return QByteArray();
                        ipv6[--at] = 0;
                        ipv6[--at] = 0;
                    }
                }
            } else {
                if (parts[n].indexOf('.') == -1) {
                    bool ok;
                    int  x = parts[n].toInt(&ok, 16);
                    if (!ok || x < 0 || x > 0xffff)
                        return QByteArray();
                    ipv6[--at] = x & 0xff;
                    ipv6[--at] = (x >> 8) & 0xff;
                } else {
                    if (n != parts.count() - 1)
                        return QByteArray();

                    QByteArray buf = ipaddr_str2bin(parts[n]);
                    if (buf.isEmpty())
                        return QByteArray();

                    ipv6[--at] = buf[3];
                    ipv6[--at] = buf[2];
                    ipv6[--at] = buf[1];
                    ipv6[--at] = buf[0];
                    --fill;
                }
            }
        }

        return ipv6;
    } else if (str.contains('.')) {
#if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0)
        QStringList parts = str.split('.', Qt::KeepEmptyParts);
#else
        QStringList parts = str.split('.', QString::KeepEmptyParts);
#endif
        if (parts.count() != 4)
            return QByteArray();

        QByteArray out(4, 0);
        for (int n = 0; n < 4; ++n) {
            bool ok;
            int  x = parts[n].toInt(&ok);
            if (!ok || x < 0 || x > 0xff)
                return QByteArray();
            out[n] = (unsigned char)x;
        }
        return out;
    } else
        return QByteArray();
}

// acedomain must be all lowercase, with no trailing dot or wildcards
static bool cert_match_domain(const QString &certname, const QString &acedomain)
{
    // KSSL strips start/end whitespace, even though such whitespace is
    //   probably not legal anyway. (compat)
    QString name = certname.trimmed();

    // KSSL strips trailing dot, even though the dot is probably not
    //   legal anyway. (compat)
    if (name.length() > 0 && name[name.length() - 1] == '.')
        name.truncate(name.length() - 1);

    // after our compatibility modifications, make sure the name isn't
    //   empty.
    if (name.isEmpty())
        return false;

    // lowercase, for later performing case insensitive matching
    name = name.toLower();

    // ensure the cert field contains valid characters only
    if (QRegExp("[^a-z0-9\\.\\*\\-]").indexIn(name) >= 0)
        return false;

        // hack into parts, and require at least 1 part
#if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0)
    QStringList parts_name = name.split('.', Qt::KeepEmptyParts);
#else
    QStringList parts_name = name.split('.', QString::KeepEmptyParts);
#endif
    if (parts_name.isEmpty())
        return false;

    // KSSL checks to make sure the last two parts don't contain
    //   wildcards.  I don't know where it is written that this
    //   should be done, but for compat sake we'll do it.
    if (parts_name[parts_name.count() - 1].contains('*'))
        return false;
    if (parts_name.count() >= 2 && parts_name[parts_name.count() - 2].contains('*'))
        return false;
#if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0)
    QStringList parts_compare = acedomain.split('.', Qt::KeepEmptyParts);
#else
    QStringList parts_compare = acedomain.split('.', QString::KeepEmptyParts);
#endif
    if (parts_compare.isEmpty())
        return false;

    // don't allow empty parts
    for (const QString &s : qAsConst(parts_name)) {
        if (s.isEmpty())
            return false;
    }
    for (const QString &s : parts_compare) {
        if (s.isEmpty())
            return false;
    }

    // RFC2818: "Names may contain the wildcard character * which is
    //   considered to match any single domain name component or
    //   component fragment. E.g., *.a.com matches foo.a.com but not
    //   bar.foo.a.com. f*.com matches foo.com but not bar.com."
    //
    // This means that for the domain to match it must have the
    //   same number of components, wildcards or not.  If there are
    //   wildcards, their scope must only be within the component
    //   they reside in.
    //
    // First, make sure the number of parts is equal.
    if (parts_name.count() != parts_compare.count())
        return false;

    // Now compare each part
    for (int n = 0; n < parts_name.count(); ++n) {
        const QString &p1 = parts_name[n];
        const QString &p2 = parts_compare[n];

        if (!QRegExp(p1, Qt::CaseSensitive, QRegExp::Wildcard).exactMatch(p2))
            return false;
    }

    return true;
}

// ipaddress must be an ipv4 or ipv6 address in binary format
static bool cert_match_ipaddress(const QString &certname, const QByteArray &ipaddress)
{
    // KSSL strips start/end whitespace, even though such whitespace is
    //   probably not legal anyway. (compat)
    QString name = certname.trimmed();

    // KSSL accepts IPv6 in brackets, which is usually done for URIs, but
    //   IMO sounds very strange for a certificate.  We'll follow this
    //   behavior anyway. (compat)
    if (name.length() >= 2 && name[0] == '[' && name[name.length() - 1] == ']')
        name = name.mid(1, name.length() - 2); // chop off brackets

    // after our compatibility modifications, make sure the name isn't
    //   empty.
    if (name.isEmpty())
        return false;

    // convert to binary form
    QByteArray addr = ipaddr_str2bin(name);
    if (addr.isEmpty())
        return false;

    // not the same?
    return addr == ipaddress;
}

static bool matchesHostName(const QCA::Certificate &cert, const QString &host)
{
    QByteArray ipaddr = ipaddr_str2bin(host);
    if (!ipaddr.isEmpty()) // ip address
    {
        // check iPAddress
        const auto ipAddresses = cert.subjectInfo().values(IPAddress);
        for (const QString &s : ipAddresses) {
            if (cert_match_ipaddress(s, ipaddr))
                return true;
        }

        // check dNSName
        const auto dnsNames = cert.subjectInfo().values(DNS);
        for (const QString &s : dnsNames) {
            if (cert_match_ipaddress(s, ipaddr))
                return true;
        }

        // check commonName
        const auto commonNames = cert.subjectInfo().values(CommonName);
        for (const QString &s : commonNames) {
            if (cert_match_ipaddress(s, ipaddr))
                return true;
        }
    } else // domain
    {
        // lowercase
        QString name = host.toLower();

        // ACE
        name = QString::fromLatin1(QUrl::toAce(name));

        // don't allow wildcards in the comparison host
        if (name.contains('*'))
            return false;

        // strip out trailing dot
        if (name.length() > 0 && name[name.length() - 1] == '.')
            name.truncate(name.length() - 1);

        // make sure the name is not empty after our modifications
        if (name.isEmpty())
            return false;

        // check dNSName
        const auto dnsNames = cert.subjectInfo().values(DNS);
        for (const QString &s : dnsNames) {
            if (cert_match_domain(s, name))
                return true;
        }

        // check commonName
        const auto commonNames = cert.subjectInfo().values(CommonName);
        for (const QString &s : commonNames) {
            if (cert_match_domain(s, name))
                return true;
        }
    }

    return false;
}

//----------------------------------------------------------------------------
// TLSHandler
//----------------------------------------------------------------------------
TLSHandler::TLSHandler(QObject *parent) : QObject(parent) { }

TLSHandler::~TLSHandler() { }

//----------------------------------------------------------------------------
// QCATLSHandler
//----------------------------------------------------------------------------
class QCATLSHandler::Private {
public:
    QCA::TLS *tls;
    int       state, err;
    QString   host;
    bool      internalHostMatch;
};

QCATLSHandler::QCATLSHandler(QCA::TLS *parent) : TLSHandler(parent)
{
    d      = new Private;
    d->tls = parent;
    connect(d->tls, SIGNAL(handshaken()), SLOT(tls_handshaken()));
    connect(d->tls, SIGNAL(readyRead()), SLOT(tls_readyRead()));
    connect(d->tls, SIGNAL(readyReadOutgoing()), SLOT(tls_readyReadOutgoing()));
    connect(d->tls, SIGNAL(closed()), SLOT(tls_closed()));
    connect(d->tls, SIGNAL(error()), SLOT(tls_error()));
    d->state             = 0;
    d->err               = -1;
    d->internalHostMatch = false;
}

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

void QCATLSHandler::setXMPPCertCheck(bool enable) { d->internalHostMatch = enable; }
bool QCATLSHandler::XMPPCertCheck() { return d->internalHostMatch; }
bool QCATLSHandler::certMatchesHostname()
{
    if (!d->internalHostMatch)
        return false;
    QCA::CertificateChain peerCert = d->tls->peerCertificateChain();

    if (matchesHostName(peerCert.primary(), d->host))
        return true;

    Jid host(d->host);

    const auto hosts = peerCert.primary().subjectInfo().values(QCA::XMPP);
    for (const QString &idOnXmppAddr : hosts) {
        if (host.compare(Jid(idOnXmppAddr)))
            return true;
    }

    return false;
}

QCA::TLS *QCATLSHandler::tls() const { return d->tls; }

int QCATLSHandler::tlsError() const { return d->err; }

void QCATLSHandler::reset()
{
    d->tls->reset();
    d->state = 0;
}

void QCATLSHandler::startClient(const QString &host)
{
    d->state = 0;
    d->err   = -1;
    if (d->internalHostMatch)
        d->host = host;
    d->tls->startClient(d->internalHostMatch ? QString() : host);
}

void QCATLSHandler::write(const QByteArray &a) { d->tls->write(a); }

void QCATLSHandler::writeIncoming(const QByteArray &a) { d->tls->writeIncoming(a); }

void QCATLSHandler::continueAfterHandshake()
{
    if (d->state == 2) {
        d->tls->continueAfterStep();
        emit success();
        d->state = 3;
    }
}

void QCATLSHandler::tls_handshaken()
{
    d->state = 2;
    emit tlsHandshaken();
}

void QCATLSHandler::tls_readyRead() { emit readyRead(d->tls->read()); }

void QCATLSHandler::tls_readyReadOutgoing()
{
    int        plainBytes;
    QByteArray buf = d->tls->readOutgoing(&plainBytes);
    emit       readyReadOutgoing(buf, plainBytes);
}

void QCATLSHandler::tls_closed() { emit closed(); }

void QCATLSHandler::tls_error()
{
    d->err   = d->tls->errorCode();
    d->state = 0;
    emit fail();
}
