// Copyright (C) 2015 Mikkel Krautz <mikkel@krautz.dk>

// Copyright (C) 2016 Richard J. Moore <rich@kde.org>

// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only

// Qt-Security score:critical reason:cryptography

#include "qsslsocket_openssl_symbols_p.h"

#include "qtlsbackend_openssl_p.h"

#include <QtNetwork/private/qsslsocket_p.h>

#include <QtCore/qscopeguard.h>

#include <QtCore/qbytearray.h>

#include <QtCore/qiodevice.h>

#include <QtCore/qdebug.h>

#include <openssl/bn.h>

#include <openssl/dh.h>

QT_BEGIN_NAMESPACE

#ifndef OPENSSL_NO_DEPRECATED_3_0

namespace {

bool isSafeDH(DH *dh)

{

    int status = 0;

    int bad = 0;

    // TLSTODO: check it's needed or if supportsSsl()

    // is enough.

    QSslSocketPrivate::ensureInitialized();

    // From https://wiki.openssl.org/index.php/Diffie-Hellman_parameters:

    //

    //     The additional call to BN_mod_word(dh->p, 24)

    //     (and unmasking of DH_NOT_SUITABLE_GENERATOR)

    //     is performed to ensure your program accepts

    //     IETF group parameters. OpenSSL checks the prime

    //     is congruent to 11 when g = 2; while the IETF's

    //     primes are congruent to 23 when g = 2.

    //     Without the test, the IETF parameters would

    //     fail validation. For details, see Diffie-Hellman

    //     Parameter Check (when g = 2, must p mod 24 == 11?).

    // Mark p < 1024 bits as unsafe.

    if (q_DH_bits(dh) < 1024)

        return false;

    if (q_DH_check(dh, &status) != 1)

        return false;

    const BIGNUM *p = nullptr;

    const BIGNUM *q = nullptr;

    const BIGNUM *g = nullptr;

    q_DH_get0_pqg(dh, &p, &q, &g);

    if (q_BN_is_word(const_cast<BIGNUM *>(g), DH_GENERATOR_2)) {

        const unsigned long residue = q_BN_mod_word(p, 24);

        if (residue == 11 || residue == 23)

            status &= ~DH_NOT_SUITABLE_GENERATOR;

    }

    bad |= DH_CHECK_P_NOT_PRIME;

    bad |= DH_CHECK_P_NOT_SAFE_PRIME;

    bad |= DH_NOT_SUITABLE_GENERATOR;

    return !(status & bad);

}

} // unnamed namespace

#endif

int QTlsBackendOpenSSL::dhParametersFromDer(const QByteArray &der, QByteArray *derData) const

{

#ifndef OPENSSL_NO_DEPRECATED_3_0

    Q_ASSERT(derData);

    if (der.isEmpty())

        return DHParams::InvalidInputDataError;

    const unsigned char *data = reinterpret_cast<const unsigned char *>(der.data());

    const int len = der.size();

    // TLSTODO: check it's needed (loading ciphers and certs in

    // addition to the library!)

    QSslSocketPrivate::ensureInitialized();

    DH *dh = q_d2i_DHparams(nullptr, &data, len);

    if (dh) {

        const auto dhRaii = qScopeGuard([dh] {q_DH_free(dh);});

        if (isSafeDH(dh))

            *derData = der;

        else

            return DHParams::UnsafeParametersError;

    } else {

        return DHParams::InvalidInputDataError;

    }

#else

    Q_UNUSED(der);

    Q_UNUSED(derData);

    qCWarning(lcTlsBackend, "Diffie-Hellman parameters are not supported, because OpenSSL v3 was built with deprecated API removed");

#endif

    return DHParams::NoError;

}

int QTlsBackendOpenSSL::dhParametersFromPem(const QByteArray &pem, QByteArray *data) const

{

#ifndef OPENSSL_NO_DEPRECATED_3_0

    Q_ASSERT(data);

    if (pem.isEmpty())

        return DHParams::InvalidInputDataError;

    // TLSTODO: check it was not a cargo-cult programming in case of

    // DH ...

    QSslSocketPrivate::ensureInitialized();

    BIO *bio = q_BIO_new_mem_buf(const_cast<char *>(pem.data()), pem.size());

    if (!bio)

        return DHParams::InvalidInputDataError;

    const auto bioRaii = qScopeGuard([bio]

    {

        q_BIO_free(bio);

    });

    DH *dh = nullptr;

    q_PEM_read_bio_DHparams(bio, &dh, nullptr, nullptr);

    if (dh) {

        const auto dhGuard = qScopeGuard([dh]

        {

            q_DH_free(dh);

        });

        if (isSafeDH(dh)) {

            char *buf = nullptr;

            const int len = q_i2d_DHparams(dh, reinterpret_cast<unsigned char **>(&buf));

            const auto freeBuf = qScopeGuard([&] { q_OPENSSL_free(buf); });

            if (len > 0)

                data->assign({buf, len});

            else

                return DHParams::InvalidInputDataError;

        } else {

            return DHParams::UnsafeParametersError;

        }

    } else {

        return DHParams::InvalidInputDataError;

    }

#else

    Q_UNUSED(pem);

    Q_UNUSED(data);

    qCWarning(lcTlsBackend, "Diffie-Hellman parameters are not supported, because OpenSSL v3 was built with deprecated API removed");

#endif

    return DHParams::NoError;

}

QT_END_NAMESPACE