/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Qt Software Information (qt-info@nokia.com)
**
** This file is part of the QtNetwork module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the either Technology Preview License Agreement or the
** Beta Release License Agreement.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain
** additional rights. These rights are described in the Nokia Qt LGPL
** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
** package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you are unsure which license is appropriate for your use, please
** contact the sales department at qt-sales@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/

#include <qauthenticator.h>
#include <qauthenticator_p.h>
#include <qdebug.h>
#include <qhash.h>
#include <qbytearray.h>
#include <qcryptographichash.h>
#include <qhttp.h>
#include <qdatastream.h>
#include <qendian.h>
#include <qstring.h>

QT_BEGIN_NAMESPACE

#include "../../3rdparty/des/des.cpp"

static QByteArray qNtlmPhase1();
static QByteArray qNtlmPhase3(QAuthenticatorPrivate *ctx, const QByteArray& phase2data);

/*!
  \class QAuthenticator
  \brief The QAuthenticator class provides an authentication object.
  \since 4.3

  \reentrant
  \ingroup io
  \inmodule QtNetwork

  The QAuthenticator class is usually used in the
  \l{QHttp::}{authenticationRequired()} and
  \l{QHttp::}{proxyAuthenticationRequired()} signals of QHttp and
  QAbstractSocket. The class provides a way to pass back the required
  authentication information to the socket when accessing services that
  require authentication.

  QAuthenticator supports the following authentication methods:
  \list
    \o Basic
    \o NTLM version 1
    \o Digest-MD5
  \endlist

  Note that, in particular, NTLM version 2 is not supported.

  \sa QSslSocket
*/


/*!
  Constructs an empty authentication object
*/
QAuthenticator::QAuthenticator()
    : d(0)
{
}

/*!
  Destructs the object
*/
QAuthenticator::~QAuthenticator()
{
    if (d && !d->ref.deref())
        delete d;
}

/*!
    Constructs a copy of \a other.
*/
QAuthenticator::QAuthenticator(const QAuthenticator &other)
    : d(other.d)
{
    if (d)
        d->ref.ref();
}

/*!
    Assigns the contents of \a other to this authenticator.
*/
QAuthenticator &QAuthenticator::operator=(const QAuthenticator &other)
{
    if (d == other.d)
        return *this;
    detach();
    d->user = other.d->user;
    d->password = other.d->password;
    return *this;
}

/*!
    Returns true if this authenticator is identical to \a other; otherwise
    returns false.
*/
bool QAuthenticator::operator==(const QAuthenticator &other) const
{
    if (d == other.d)
        return true;
    return d->user == other.d->user
        && d->password == other.d->password
        && d->realm == other.d->realm
        && d->method == other.d->method;
}

/*!
    \fn bool QAuthenticator::operator!=(const QAuthenticator &other) const

    Returns true if this authenticator is different from \a other; otherwise
    returns false.
*/

/*!
  returns the user used for authentication.
*/
QString QAuthenticator::user() const
{
    return d ? d->user : QString();
}

/*!
  Sets the \a user used for authentication.
*/
void QAuthenticator::setUser(const QString &user)
{
    detach();
    d->user = user;
}

/*!
  returns the password used for authentication.
*/
QString QAuthenticator::password() const
{
    return d ? d->password : QString();
}

/*!
  Sets the \a password used for authentication.
*/
void QAuthenticator::setPassword(const QString &password)
{
    detach();
    d->password = password;
}

/*!
  \internal
*/
void QAuthenticator::detach()
{
    if (!d) {
        d = new QAuthenticatorPrivate;
        d->ref = 1;
        return;
    }

    qAtomicDetach(d);
    d->phase = QAuthenticatorPrivate::Start;
}

/*!
  returns the realm requiring authentication.
*/
QString QAuthenticator::realm() const
{
    return d ? d->realm : QString();
}


/*!
  returns true if the authenticator is null.
*/
bool QAuthenticator::isNull() const
{
    return !d;
}

QAuthenticatorPrivate::QAuthenticatorPrivate()
    : ref(0)
    , method(None)
    , phase(Start)
    , nonceCount(0)
{
    cnonce = QCryptographicHash::hash(QByteArray::number(qrand(), 16) + QByteArray::number(qrand(), 16),
                                      QCryptographicHash::Md5).toHex();
    nonceCount = 0;
}

#ifndef QT_NO_HTTP
void QAuthenticatorPrivate::parseHttpResponse(const QHttpResponseHeader &header, bool isProxy)
{
    QList<QPair<QString, QString> > values = header.values();
    const char *search = isProxy ? "proxy-authenticate" : "www-authenticate";

    method = None;
    /*
      Fun from the HTTP 1.1 specs, that we currently ignore:

      User agents are advised to take special care in parsing the WWW-
      Authenticate field value as it might contain more than one challenge,
      or if more than one WWW-Authenticate header field is provided, the
      contents of a challenge itself can contain a comma-separated list of
      authentication parameters.
    */

    QString headerVal;
    for (int i = 0; i < values.size(); ++i) {
        const QPair<QString, QString> &current = values.at(i);
        if (current.first.toLower() != QLatin1String(search))
            continue;
        QString str = current.second;
        if (method < Basic && str.startsWith(QLatin1String("Basic"), Qt::CaseInsensitive)) {
            method = Basic; headerVal = str.mid(6);
        } else if (method < Ntlm && str.startsWith(QLatin1String("NTLM"), Qt::CaseInsensitive)) {
            method = Ntlm;
            headerVal = str.mid(5);
        } else if (method < DigestMd5 && str.startsWith(QLatin1String("Digest"), Qt::CaseInsensitive)) {
            method = DigestMd5;
            headerVal = str.mid(7);
        }
    }

    challenge = headerVal.trimmed().toLatin1();
    QHash<QByteArray, QByteArray> options = parseDigestAuthenticationChallenge(challenge);

    switch(method) {
    case Basic:
        realm = QString::fromLatin1(options.value("realm"));
        if (user.isEmpty())
            phase = Done;
        break;
    case Ntlm:
        // #### extract from header
        realm = QString();
        break;
    case DigestMd5: {
        realm = QString::fromLatin1(options.value("realm"));
        if (options.value("stale").toLower() == "true")
            phase = Start;
        if (user.isEmpty())
            phase = Done;
        break;
    }
    default:
        realm = QString();
        challenge = QByteArray();
        phase = Invalid;
    }
}
#endif

QByteArray QAuthenticatorPrivate::calculateResponse(const QByteArray &requestMethod, const QByteArray &path)
{
    QByteArray response;
    const char *methodString = 0;
    switch(method) {
    case QAuthenticatorPrivate::None:
        methodString = "";
        phase = Done;
        break;
    case QAuthenticatorPrivate::Plain:
        response = '\0' + user.toUtf8() + '\0' + password.toUtf8();
        phase = Done;
        break;
    case QAuthenticatorPrivate::Basic:
        methodString = "Basic ";
        response = user.toLatin1() + ':' + password.toLatin1();
        response = response.toBase64();
        phase = Done;
        break;
    case QAuthenticatorPrivate::Login:
        if (challenge.contains("VXNlciBOYW1lAA==")) {
            response = user.toUtf8().toBase64();
            phase = Phase2;
        } else if (challenge.contains("UGFzc3dvcmQA")) {
            response = password.toUtf8().toBase64();
            phase = Done;
        }
        break;
    case QAuthenticatorPrivate::CramMd5:
        break;
    case QAuthenticatorPrivate::DigestMd5:
        methodString = "Digest ";
        response = digestMd5Response(challenge, requestMethod, path);
        phase = Done;
        break;
    case QAuthenticatorPrivate::Ntlm:
        methodString = "NTLM ";
        if (challenge.isEmpty()) {
            response = qNtlmPhase1().toBase64();
            if (user.isEmpty())
                phase = Done;
            else
                phase = Phase2;
        } else {
            response = qNtlmPhase3(this, QByteArray::fromBase64(challenge)).toBase64();
            phase = Done;
        }

        break;
    }
    return QByteArray(methodString) + response;
}


// ---------------------------- Digest Md5 code ----------------------------------------

QHash<QByteArray, QByteArray> QAuthenticatorPrivate::parseDigestAuthenticationChallenge(const QByteArray &challenge)
{
    QHash<QByteArray, QByteArray> options;
    // parse the challenge
    const char *d = challenge.constData();
    const char *end = d + challenge.length();
    while (d < end) {
        while (d < end && (*d == ' ' || *d == '\n' || *d == '\r'))
            ++d;
        const char *start = d;
        while (d < end && *d != '=')
            ++d;
        QByteArray key = QByteArray(start, d - start);
        ++d;
        if (d >= end)
            break;
        bool quote = (*d == '"');
        if (quote)
            ++d;
        if (d >= end)
            break;
        start = d;
        QByteArray value;
        while (d < end) {
            bool backslash = false;
            if (*d == '\\' && d < end - 1) {
                ++d;
                backslash = true;
            }
            if (!backslash) {
                if (quote) {
                    if (*d == '"')
                        break;
                } else {
                    if (*d == ',')
                        break;
                }
            }
            value += *d;
            ++d;
        }
        while (d < end && *d != ',')
            ++d;
        ++d;
        options[key] = value;
    }

    QByteArray qop = options.value("qop");
    if (!qop.isEmpty()) {
        QList<QByteArray> qopoptions = qop.split(',');
        if (!qopoptions.contains("auth"))
            return QHash<QByteArray, QByteArray>();
        // #### can't do auth-int currently
//         if (qop.contains("auth-int"))
//             qop = "auth-int";
//         else if (qop.contains("auth"))
//             qop = "auth";
//         else
//             qop = QByteArray();
        options["qop"] = "auth";
    }

    return options;
}

/*
  Digest MD5 implementation

  Code taken from RFC 2617

  Currently we don't support the full SASL authentication mechanism (which includes cyphers)
*/


/* calculate request-digest/response-digest as per HTTP Digest spec */
static QByteArray digestMd5ResponseHelper(
    const QByteArray &alg,
    const QByteArray &userName,
    const QByteArray &realm,
    const QByteArray &password,
    const QByteArray &nonce,       /* nonce from server */
    const QByteArray &nonceCount,  /* 8 hex digits */
    const QByteArray &cNonce,      /* client nonce */
    const QByteArray &qop,         /* qop-value: "", "auth", "auth-int" */
    const QByteArray &method,      /* method from the request */
    const QByteArray &digestUri,   /* requested URL */
    const QByteArray &hEntity       /* H(entity body) if qop="auth-int" */
    )
{
    QCryptographicHash hash(QCryptographicHash::Md5);
    hash.addData(userName);
    hash.addData(":", 1);
    hash.addData(realm);
    hash.addData(":", 1);
    hash.addData(password);
    QByteArray ha1 = hash.result();
    if (alg.toLower() == "md5-sess") {
        hash.reset();
        // RFC 2617 contains an error, it was:
        // hash.addData(ha1);
        // but according to the errata page at http://www.rfc-editor.org/errata_list.php, ID 1649, it
        // must be the following line:
        hash.addData(ha1.toHex());
        hash.addData(":", 1);
        hash.addData(nonce);
        hash.addData(":", 1);
        hash.addData(cNonce);
        ha1 = hash.result();
    };
    ha1 = ha1.toHex();

    // calculate H(A2)
    hash.reset();
    hash.addData(method);
    hash.addData(":", 1);
    hash.addData(digestUri);
    if (qop.toLower() == "auth-int") {
        hash.addData(":", 1);
        hash.addData(hEntity);
    }
    QByteArray ha2hex = hash.result().toHex();

    // calculate response
    hash.reset();
    hash.addData(ha1);
    hash.addData(":", 1);
    hash.addData(nonce);
    hash.addData(":", 1);
    if (!qop.isNull()) {
        hash.addData(nonceCount);
        hash.addData(":", 1);
        hash.addData(cNonce);
        hash.addData(":", 1);
        hash.addData(qop);
        hash.addData(":", 1);
    }
    hash.addData(ha2hex);
    return hash.result().toHex();
}

QByteArray QAuthenticatorPrivate::digestMd5Response(const QByteArray &challenge, const QByteArray &method, const QByteArray &path)
{
    QHash<QByteArray,QByteArray> options = parseDigestAuthenticationChallenge(challenge);

    ++nonceCount;
    QByteArray nonceCountString = QByteArray::number(nonceCount, 16);
    while (nonceCountString.length() < 8)
        nonceCountString.prepend('0');

    QByteArray nonce = options.value("nonce");
    QByteArray opaque = options.value("opaque");
    QByteArray qop = options.value("qop");

//    qDebug() << "calculating digest: method=" << method << "path=" << path;
    QByteArray response = digestMd5ResponseHelper(options.value("algorithm"), user.toLatin1(),
                                              realm.toLatin1(), password.toLatin1(),
                                              nonce, nonceCountString,
                                              cnonce, qop, method,
                                              path, QByteArray());


    QByteArray credentials;
    credentials += "username=\"" + user.toLatin1() + "\", ";
    credentials += "realm=\"" + realm.toLatin1() + "\", ";
    credentials += "nonce=\"" + nonce + "\", ";
    credentials += "uri=\"" + path + "\", ";
    if (!opaque.isEmpty())
        credentials += "opaque=\"" + opaque + "\", ";
    credentials += "response=\"" + response + "\"";
    if (!options.value("algorithm").isEmpty())
        credentials += ", algorithm=" + options.value("algorithm");
    if (!options.value("qop").isEmpty()) {
        credentials += ", qop=" + qop + ", ";
        credentials += "nc=" + nonceCountString + ", ";
        credentials += "cnonce=\"" + cnonce + "\"";
    }

    return credentials;
}

// ---------------------------- Digest Md5 code ----------------------------------------



/*
 * NTLM message flags.
 *
 * Copyright (c) 2004 Andrey Panin <pazke@donpac.ru>
 *
 * This software is released under the MIT license.
 */

/*
 * Indicates that Unicode strings are supported for use in security
 * buffer data.
 */
#define NTLMSSP_NEGOTIATE_UNICODE 0x00000001

/*
 * Indicates that OEM strings are supported for use in security buffer data.
 */
#define NTLMSSP_NEGOTIATE_OEM 0x00000002

/*
 * Requests that the server's authentication realm be included in the
 * Type 2 message.
 */
#define NTLMSSP_REQUEST_TARGET 0x00000004

/*
 * Specifies that authenticated communication between the client and server
 * should carry a digital signature (message integrity).
 */
#define NTLMSSP_NEGOTIATE_SIGN 0x00000010

/*
 * Specifies that authenticated communication between the client and server
 * should be encrypted (message confidentiality).
 */
#define NTLMSSP_NEGOTIATE_SEAL 0x00000020

/*
 * Indicates that datagram authentication is being used.
 */
#define NTLMSSP_NEGOTIATE_DATAGRAM 0x00000040

/*
 * Indicates that the LAN Manager session key should be
 * used for signing and sealing authenticated communications.
 */
#define NTLMSSP_NEGOTIATE_LM_KEY 0x00000080

/*
 * Indicates that NTLM authentication is being used.
 */
#define NTLMSSP_NEGOTIATE_NTLM 0x00000200

/*
 * Sent by the client in the Type 1 message to indicate that the name of the
 * domain in which the client workstation has membership is included in the
 * message. This is used by the server to determine whether the client is
 * eligible for local authentication.
 */
#define NTLMSSP_NEGOTIATE_DOMAIN_SUPPLIED 0x00001000

/*
 * Sent by the client in the Type 1 message to indicate that the client
 * workstation's name is included in the message. This is used by the server
 * to determine whether the client is eligible for local authentication.
 */
#define NTLMSSP_NEGOTIATE_WORKSTATION_SUPPLIED 0x00002000

/*
 * Sent by the server to indicate that the server and client are on the same
 * machine. Implies that the client may use the established local credentials
 * for authentication instead of calculating a response to the challenge.
 */
#define NTLMSSP_NEGOTIATE_LOCAL_CALL 0x00004000

/*
 * Indicates that authenticated communication between the client and server
 * should be signed with a "dummy" signature.
 */
#define NTLMSSP_NEGOTIATE_ALWAYS_SIGN 0x00008000

/*
 * Sent by the server in the Type 2 message to indicate that the target
 * authentication realm is a domain.
 */
#define NTLMSSP_TARGET_TYPE_DOMAIN 0x00010000

/*
 * Sent by the server in the Type 2 message to indicate that the target
 * authentication realm is a server.
 */
#define NTLMSSP_TARGET_TYPE_SERVER 0x00020000

/*
 * Sent by the server in the Type 2 message to indicate that the target
 * authentication realm is a share. Presumably, this is for share-level
 * authentication. Usage is unclear.
 */
#define NTLMSSP_TARGET_TYPE_SHARE 0x00040000

/*
 * Indicates that the NTLM2 signing and sealing scheme should be used for
 * protecting authenticated communications. Note that this refers to a
 * particular session security scheme, and is not related to the use of
 * NTLMv2 authentication.
 */
#define NTLMSSP_NEGOTIATE_NTLM2 0x00080000

/*
 * Sent by the server in the Type 2 message to indicate that it is including
 * a Target Information block in the message. The Target Information block
 * is used in the calculation of the NTLMv2 response.
 */
#define NTLMSSP_NEGOTIATE_TARGET_INFO 0x00800000

/*
 * Indicates that 128-bit encryption is supported.
 */
#define NTLMSSP_NEGOTIATE_128 0x20000000

/*
 * Indicates that the client will provide an encrypted master session key in
 * the "Session Key" field of the Type 3 message. This is used in signing and
 * sealing, and is RC4-encrypted using the previous session key as the
 * encryption key.
 */
#define NTLMSSP_NEGOTIATE_KEY_EXCHANGE 0x40000000

/*
 * Indicates that 56-bit encryption is supported.
 */
#define NTLMSSP_NEGOTIATE_56 0x80000000


/* usage:
   // fill up ctx with what we know.
   QByteArray response = qNtlmPhase1(ctx);
   // send response (b64 encoded??)
   // get response from server (b64 decode?)
   Phase2Block pb;
   qNtlmDecodePhase2(response, pb);
   response = qNtlmPhase3(ctx, pb);
   // send response (b64 encoded??)
*/

/*
   TODO:
    - Fix unicode handling
    - add v2 handling
*/

class QNtlmBuffer {
public:
    QNtlmBuffer() : len(0), maxLen(0), offset(0) {}
    quint16 len;
    quint16 maxLen;
    quint32 offset;
    enum { Size = 8 };
};

class QNtlmPhase1BlockBase
{
public:
    char magic[8];
    quint32 type;
    quint32 flags;
    QNtlmBuffer domain;
    QNtlmBuffer workstation;
    enum { Size = 32 };
};

// ################# check paddings
class QNtlmPhase2BlockBase
{
public:
    char magic[8];
    quint32 type;
    QNtlmBuffer targetName;
    quint32 flags;
    unsigned char challenge[8];
    quint32 context[2];
    QNtlmBuffer targetInfo;
    enum { Size = 48 };
};

class QNtlmPhase3BlockBase {
public:
    char magic[8];
    quint32 type;
    QNtlmBuffer lmResponse;
    QNtlmBuffer ntlmResponse;
    QNtlmBuffer domain;
    QNtlmBuffer user;
    QNtlmBuffer workstation;
    QNtlmBuffer sessionKey;
    quint32 flags;
    enum { Size = 64 };
};

static void qStreamNtlmBuffer(QDataStream& ds, const QByteArray& s)
{
    ds.writeRawData(s.constData(), s.size());
}


static void qStreamNtlmString(QDataStream& ds, const QString& s, bool unicode)
{
    if (!unicode) {
        qStreamNtlmBuffer(ds, s.toLatin1());
        return;
    }
    const ushort *d = s.utf16();
    for (int i = 0; i < s.length(); ++i)
        ds << d[i];
}



static int qEncodeNtlmBuffer(QNtlmBuffer& buf, int offset, const QByteArray& s)
{
    buf.len = s.size();
    buf.maxLen = buf.len;
    buf.offset = (offset + 1) & ~1;
    return buf.offset + buf.len;
}


static int qEncodeNtlmString(QNtlmBuffer& buf, int offset, const QString& s, bool unicode)
{
    if (!unicode)
        return qEncodeNtlmBuffer(buf, offset, s.toLatin1());
    buf.len = 2 * s.length();
    buf.maxLen = buf.len;
    buf.offset = (offset + 1) & ~1;
    return buf.offset + buf.len;
}


static QDataStream& operator<<(QDataStream& s, const QNtlmBuffer& b)
{
    s << b.len << b.maxLen << b.offset;
    return s;
}

static QDataStream& operator>>(QDataStream& s, QNtlmBuffer& b)
{
    s >> b.len >> b.maxLen >> b.offset;
    return s;
}


class QNtlmPhase1Block : public QNtlmPhase1BlockBase
{  // request
public:
    QNtlmPhase1Block() {
        qstrncpy(magic, "NTLMSSP", 8);
        type = 1;
        flags = NTLMSSP_NEGOTIATE_UNICODE | NTLMSSP_NEGOTIATE_NTLM | NTLMSSP_REQUEST_TARGET;
    }

    // extracted
    QString domainStr, workstationStr;
};


class QNtlmPhase2Block : public QNtlmPhase2BlockBase
{  // challenge
public:
    QNtlmPhase2Block() {
        magic[0] = 0;
        type = 0xffffffff;
    }

    // extracted
    QString targetNameStr, targetInfoStr;
};



class QNtlmPhase3Block : public QNtlmPhase3BlockBase {  // response
public:
    QNtlmPhase3Block() {
        qstrncpy(magic, "NTLMSSP", 8);
        type = 3;
        flags = NTLMSSP_NEGOTIATE_UNICODE | NTLMSSP_NEGOTIATE_NTLM | NTLMSSP_NEGOTIATE_TARGET_INFO;
    }

    // extracted
    QByteArray lmResponseBuf, ntlmResponseBuf;
    QString domainStr, userStr, workstationStr, sessionKeyStr;
};


static QDataStream& operator<<(QDataStream& s, const QNtlmPhase1Block& b) {
    bool unicode = (b.flags & NTLMSSP_NEGOTIATE_UNICODE);

    s.writeRawData(b.magic, sizeof(b.magic));
    s << b.type;
    s << b.flags;
    s << b.domain;
    s << b.workstation;
    if (!b.domainStr.isEmpty())
        qStreamNtlmString(s, b.domainStr, unicode);
    if (!b.workstationStr.isEmpty())
        qStreamNtlmString(s, b.workstationStr, unicode);
    return s;
}


static QDataStream& operator<<(QDataStream& s, const QNtlmPhase3Block& b) {
    bool unicode = (b.flags & NTLMSSP_NEGOTIATE_UNICODE);
    s.writeRawData(b.magic, sizeof(b.magic));
    s << b.type;
    s << b.lmResponse;
    s << b.ntlmResponse;
    s << b.domain;
    s << b.user;
    s << b.workstation;
    s << b.sessionKey;
    s << b.flags;

    if (!b.domainStr.isEmpty())
        qStreamNtlmString(s, b.domainStr, unicode);

    qStreamNtlmString(s, b.userStr, unicode);

    if (!b.workstationStr.isEmpty())
        qStreamNtlmString(s, b.workstationStr, unicode);

    // Send auth info
    qStreamNtlmBuffer(s, b.lmResponseBuf);
    qStreamNtlmBuffer(s, b.ntlmResponseBuf);


    return s;
}


static QByteArray qNtlmPhase1()
{
    QByteArray rc;
    QDataStream ds(&rc, QIODevice::WriteOnly);
    ds.setByteOrder(QDataStream::LittleEndian);
    QNtlmPhase1Block pb;
    ds << pb;
    return rc;
}


static QByteArray qStringAsUcs2Le(const QString& src)
{
    QByteArray rc(2*src.length(), 0);
    const unsigned short *s = src.utf16();
    unsigned short *d = (unsigned short*)rc.data();
    for (int i = 0; i < src.length(); ++i) {
        d[i] = qToLittleEndian(s[i]);
    }
    return rc;
}


static QString qStringFromUcs2Le(const QByteArray& src)
{
    Q_ASSERT(src.size() % 2 == 0);
    unsigned short *d = (unsigned short*)src.data();
    for (int i = 0; i < src.length() / 2; ++i) {
        d[i] = qFromLittleEndian(d[i]);
    }
    return QString((const QChar *)src.data(), src.size()/2);
}


static QByteArray qEncodeNtlmResponse(const QAuthenticatorPrivate *ctx, const QNtlmPhase2Block& ch)
{
    QCryptographicHash md4(QCryptographicHash::Md4);
    QByteArray asUcs2Le = qStringAsUcs2Le(ctx->password);
    md4.addData(asUcs2Le.data(), asUcs2Le.size());

    unsigned char md4hash[22];
    memset(md4hash, 0, sizeof(md4hash));
    QByteArray hash = md4.result();
    Q_ASSERT(hash.size() == 16);
    memcpy(md4hash, hash.constData(), 16);

    QByteArray rc(24, 0);
    deshash((unsigned char *)rc.data(), md4hash, (unsigned char *)ch.challenge);
    deshash((unsigned char *)rc.data() + 8, md4hash + 7, (unsigned char *)ch.challenge);
    deshash((unsigned char *)rc.data() + 16, md4hash + 14, (unsigned char *)ch.challenge);

    hash.fill(0);
    return rc;
}


static QByteArray qEncodeLmResponse(const QAuthenticatorPrivate *ctx, const QNtlmPhase2Block& ch)
{
    QByteArray hash(21, 0);
    QByteArray key(14, 0);
    qstrncpy(key.data(), ctx->password.toUpper().toLatin1(), 14);
    const char *block = "KGS!@#$%";

    deshash((unsigned char *)hash.data(), (unsigned char *)key.data(), (unsigned char *)block);
    deshash((unsigned char *)hash.data() + 8, (unsigned char *)key.data() + 7, (unsigned char *)block);
    key.fill(0);

    QByteArray rc(24, 0);
    deshash((unsigned char *)rc.data(), (unsigned char *)hash.data(), ch.challenge);
    deshash((unsigned char *)rc.data() + 8, (unsigned char *)hash.data() + 7, ch.challenge);
    deshash((unsigned char *)rc.data() + 16, (unsigned char *)hash.data() + 14, ch.challenge);

    hash.fill(0);
    return rc;
}


static bool qNtlmDecodePhase2(const QByteArray& data, QNtlmPhase2Block& ch)
{
    Q_ASSERT(QNtlmPhase2BlockBase::Size == sizeof(QNtlmPhase2BlockBase));
    if (data.size() < QNtlmPhase2BlockBase::Size)
        return false;


    QDataStream ds(data);
    ds.setByteOrder(QDataStream::LittleEndian);
    if (ds.readRawData(ch.magic, 8) < 8)
        return false;
    if (strncmp(ch.magic, "NTLMSSP", 8) != 0)
        return false;

    ds >> ch.type;
    if (ch.type != 2)
        return false;

    ds >> ch.targetName;
    ds >> ch.flags;
    if (ds.readRawData((char *)ch.challenge, 8) < 8)
        return false;
    ds >> ch.context[0] >> ch.context[1];
    ds >> ch.targetInfo;

    if (ch.targetName.len > 0) {
        if (ch.targetName.len + ch.targetName.offset >= (unsigned)data.size())
            return false;

        ch.targetNameStr = qStringFromUcs2Le(data.mid(ch.targetName.offset, ch.targetName.len));
    }

    if (ch.targetInfo.len > 0) {
        // UNUSED right now
    }

    return true;
}


static QByteArray qNtlmPhase3(QAuthenticatorPrivate *ctx, const QByteArray& phase2data)
{
    QNtlmPhase2Block ch;
    if (!qNtlmDecodePhase2(phase2data, ch))
        return QByteArray();

    QByteArray rc;
    QDataStream ds(&rc, QIODevice::WriteOnly);
    ds.setByteOrder(QDataStream::LittleEndian);
    QNtlmPhase3Block pb;

    bool unicode = ch.flags & NTLMSSP_NEGOTIATE_UNICODE;

    ctx->realm = ch.targetNameStr;

    pb.flags = NTLMSSP_NEGOTIATE_NTLM;
    if (unicode)
        pb.flags |= NTLMSSP_NEGOTIATE_UNICODE;
    else
        pb.flags |= NTLMSSP_NEGOTIATE_OEM;


    int offset = QNtlmPhase3BlockBase::Size;
    Q_ASSERT(QNtlmPhase3BlockBase::Size == sizeof(QNtlmPhase3BlockBase));
    
    offset = qEncodeNtlmString(pb.domain, offset, ctx->realm, unicode);
    pb.domainStr = ctx->realm;
    offset = qEncodeNtlmString(pb.user, offset, ctx->user, unicode);
    pb.userStr = ctx->user;

    offset = qEncodeNtlmString(pb.workstation, offset, ctx->workstation, unicode);
    pb.workstationStr = ctx->workstation;

    // Get LM response
    pb.lmResponseBuf = qEncodeLmResponse(ctx, ch);
    offset = qEncodeNtlmBuffer(pb.lmResponse, offset, pb.lmResponseBuf);

    // Get NTLM response
    pb.ntlmResponseBuf = qEncodeNtlmResponse(ctx, ch);
    offset = qEncodeNtlmBuffer(pb.ntlmResponse, offset, pb.ntlmResponseBuf);


    // Encode and send
    ds << pb;

    return rc;
}



QT_END_NAMESPACE