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diffie-hellman.cpp

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    diffie-hellman.cpp 4.73 KiB
    /*
     *  Copyright (C) 2004-2023 Savoir-faire Linux Inc.
     *
     *  This program is free software: you can redistribute it and/or modify
     *  it under the terms of the GNU General Public License as published by
     *  the Free Software Foundation, either version 3 of the License, or
     *  (at your option) any later version.
     *
     *  This program 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 General Public License for more details.
     *
     *  You should have received a copy of the GNU General Public License
     *  along with this program. If not, see <https://www.gnu.org/licenses/>.
     */
    #include "diffie-hellman.h"
    #include "fileutils.h"
    
    #include <chrono>
    #include <ciso646>
    
    namespace dhtnet {
    namespace tls {
    
    DhParams::DhParams(const std::vector<uint8_t>& data)
    {
        gnutls_dh_params_t new_params_;
        int ret = gnutls_dh_params_init(&new_params_);
        if (ret)
            throw std::runtime_error(std::string("Error initializing DH params: ")
                                     + gnutls_strerror(ret));
        params_.reset(new_params_);
        const gnutls_datum_t dat {(uint8_t*) data.data(), (unsigned) data.size()};
        if (int ret_pem = gnutls_dh_params_import_pkcs3(params_.get(), &dat, GNUTLS_X509_FMT_PEM))
            if (int ret_der = gnutls_dh_params_import_pkcs3(params_.get(), &dat, GNUTLS_X509_FMT_DER))
                throw std::runtime_error(std::string("Error importing DH params: ")
                                         + gnutls_strerror(ret_pem) + " " + gnutls_strerror(ret_der));
    }
    
    DhParams&
    DhParams::operator=(const DhParams& other)
    {
        if (not params_) {
            // We need a valid DH params pointer for the copy
            gnutls_dh_params_t new_params_;
            auto err = gnutls_dh_params_init(&new_params_);
            if (err != GNUTLS_E_SUCCESS)
                throw std::runtime_error(std::string("Error initializing DH params: ")
                                         + gnutls_strerror(err));
            params_.reset(new_params_);
        }
    
        auto err = gnutls_dh_params_cpy(params_.get(), other.get());
        if (err != GNUTLS_E_SUCCESS)
            throw std::runtime_error(std::string("Error copying DH params: ") + gnutls_strerror(err));
    
        return *this;
    }
    
    std::vector<uint8_t>
    DhParams::serialize() const
    {
        if (!params_) {
            // JAMI_WARN("serialize() called on an empty DhParams");
            return {};
        }
        gnutls_datum_t out;
        if (gnutls_dh_params_export2_pkcs3(params_.get(), GNUTLS_X509_FMT_PEM, &out))
            return {};
        std::vector<uint8_t> ret {out.data, out.data + out.size};
        gnutls_free(out.data);
        return ret;
    }
    
    DhParams
    DhParams::generate()
    {
        using clock = std::chrono::high_resolution_clock;
    
        auto bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH,
                                                /* GNUTLS_SEC_PARAM_HIGH */ GNUTLS_SEC_PARAM_HIGH);
        // JAMI_DBG("Generating DH params with %u bits", bits);
        auto start = clock::now();
    
        gnutls_dh_params_t new_params_;
        int ret = gnutls_dh_params_init(&new_params_);
        if (ret != GNUTLS_E_SUCCESS) {
            // JAMI_ERR("Error initializing DH params: %s", gnutls_strerror(ret));
            return {};
        }
        DhParams params {new_params_};
    
        ret = gnutls_dh_params_generate2(params.get(), bits);
        if (ret != GNUTLS_E_SUCCESS) {
            // JAMI_ERR("Error generating DH params: %s", gnutls_strerror(ret));
            return {};
        }
    
        std::chrono::duration<double> time_span = clock::now() - start;
        // JAMI_DBG("Generated DH params with %u bits in %lfs", bits, time_span.count());
        return params;
    }
    
    DhParams
    DhParams::loadDhParams(const std::string& path)
    {
        std::lock_guard<std::mutex> l(fileutils::getFileLock(path));
        try {
            // writeTime throw exception if file doesn't exist
            auto duration = std::chrono::system_clock::now() - fileutils::writeTime(path);
            if (duration >= std::chrono::hours(24 * 3)) // file is valid only 3 days
                throw std::runtime_error("file too old");
    
            // JAMI_DBG("Loading DhParams from file '%s'", path.c_str());
            return {fileutils::loadFile(path)};
        } catch (const std::exception& e) {
            // JAMI_DBG("Failed to load DhParams file '%s': %s", path.c_str(), e.what());
            if (auto params = tls::DhParams::generate()) {
                try {
                    fileutils::saveFile(path, params.serialize(), 0600);
                    // JAMI_DBG("Saved DhParams to file '%s'", path.c_str());
                } catch (const std::exception& ex) {
                    // JAMI_WARN("Failed to save DhParams in file '%s': %s", path.c_str(), ex.what());
                }
                return params;
            }
            // JAMI_ERR("Can't generate DH params.");
            return {};
        }
    }
    
    } // namespace tls
    } // namespace jami