openvpn3/openvpn/win/reg.hpp

//    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) 2012-2022 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/>.

// registry utilities for Windows

#ifndef OPENVPN_WIN_REG_H
#define OPENVPN_WIN_REG_H

#include <windows.h>
#include <openvpn/win/winerr.hpp>
#include <openvpn/common/size.hpp>

namespace openvpn {
namespace Win {

template <typename E>
static void check_reg_error(DWORD status, const std::string &key)
{
    if (status != ERROR_SUCCESS)
    {
        const Win::Error err(status);
        OPENVPN_THROW(E, "registry key " << key << " error: " << err.message());
    }
}

// HKEY wrapper
class RegKey
{
    RegKey(const RegKey &) = delete;
    RegKey &operator=(const RegKey &) = delete;

  public:
    RegKey()
        : key(nullptr)
    {
    }
    bool defined() const
    {
        return key != nullptr && key != INVALID_HANDLE_VALUE;
    }
    HKEY *ref()
    {
        return &key;
    }
    HKEY operator()()
    {
        return key;
    }

    ~RegKey()
    {
        if (defined())
            ::RegCloseKey(key);
    }

  private:
    HKEY key;
};

class RegKeyEnumerator : public std::vector<std::string>
{
  public:
    RegKeyEnumerator(HKEY hkey, const std::string &path)
    {
        RegKey regKey;
        auto status = ::RegOpenKeyExA(hkey,
                                      path.c_str(),
                                      0,
                                      KEY_QUERY_VALUE | KEY_ENUMERATE_SUB_KEYS,
                                      regKey.ref());
        if (status != ERROR_SUCCESS)
            return;

        DWORD subkeys_num;
        status = ::RegQueryInfoKeyA(regKey(),
                                    nullptr,
                                    nullptr,
                                    NULL,
                                    &subkeys_num,
                                    nullptr,
                                    nullptr,
                                    nullptr,
                                    nullptr,
                                    nullptr,
                                    nullptr,
                                    nullptr);

        if (status != ERROR_SUCCESS)
            return;

        const int MAX_KEY_LENGTH = 255;
        for (DWORD i = 0; i < subkeys_num; ++i)
        {
            DWORD subkey_size = MAX_KEY_LENGTH;
            char subkey[MAX_KEY_LENGTH];
            status = ::RegEnumKeyExA(regKey(),
                                     i,
                                     subkey,
                                     &subkey_size,
                                     nullptr,
                                     nullptr,
                                     nullptr,
                                     nullptr);
            if (status == ERROR_SUCCESS)
                push_back(subkey);
        }
    }
};
} // namespace Win
} // namespace openvpn

#endif