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C++

// OpenVPN -- An application to securely tunnel IP networks
// over a single port, with support for SSL/TLS-based
// session authentication and key exchange,
// packet encryption, packet authentication, and
// packet compression.
//
// Copyright (C) 2012-2017 OpenVPN Inc.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License Version 3
// as published by the Free Software Foundation.
//
// 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 Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program in the COPYING file.
// If not, see <http://www.gnu.org/licenses/>.
// Wrap a mbed TLS dhm_context object (Diffie Hellman parameters).
#ifndef OPENVPN_MBEDTLS_PKI_DH_H
#define OPENVPN_MBEDTLS_PKI_DH_H
#include <string>
#include <sstream>
#include <cstring>
#include <mbedtls/x509.h>
#include <openvpn/common/size.hpp>
#include <openvpn/common/exception.hpp>
#include <openvpn/common/rc.hpp>
#include <openvpn/mbedtls/util/error.hpp>
namespace openvpn {
namespace MbedTLSPKI {
class DH : public RC<thread_unsafe_refcount>
{
public:
typedef RCPtr<DH> Ptr;
DH() : dhc(nullptr) {}
DH(const std::string& dh_txt, const std::string& title)
: dhc(nullptr)
{
try {
parse(dh_txt, title);
}
catch (...)
{
dealloc();
throw;
}
}
void parse(const std::string& dh_txt, const std::string& title)
{
alloc();
// dh_txt.length() is increased by 1 as it does not include the NULL-terminator
// which mbedtls_dhm_parse_dhm() expects to see.
const int status = mbedtls_dhm_parse_dhm(dhc,
(const unsigned char *)dh_txt.c_str(),
dh_txt.length() + 1);
if (status < 0)
{
throw MbedTLSException("error parsing " + title + " DH parameters", status);
}
if (status > 0)
{
std::ostringstream os;
os << status << " DH parameters in " << title << " failed to parse";
throw MbedTLSException(os.str());
}
// store PEM data to allow extraction
pem_dhc = dh_txt;
}
std::string extract() const
{
return std::string(pem_dhc);
}
mbedtls_dhm_context* get() const
{
return dhc;
}
~DH()
{
dealloc();
}
private:
void alloc()
{
if (!dhc)
{
dhc = new mbedtls_dhm_context;
mbedtls_dhm_init(dhc);
}
}
void dealloc()
{
if (dhc)
{
mbedtls_dhm_free(dhc);
delete dhc;
dhc = nullptr;
}
}
mbedtls_dhm_context *dhc;
std::string pem_dhc;
};
}
}
#endif