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/**
* Copyright (C) 2021-2024 Saturneric <eric@bktus.com>
*
* This file is part of GpgFrontend.
*
* GpgFrontend 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.
*
* GpgFrontend 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 GpgFrontend. If not, see <https://www.gnu.org/licenses/>.
*
* The initial version of the source code is inherited from
* the gpg4usb project, which is under GPL-3.0-or-later.
*
* All the source code of GpgFrontend was modified and released by
* Saturneric <eric@bktus.com> starting on May 12, 2021.
*
* SPDX-License-Identifier: GPL-3.0-or-later
*
*/
#include "EMailSecret.h"
#include <QByteArray>
#include <QString>
#include <cstring>
#include "GFModule.h"
namespace {
/// Overwrites in a way the compiler may not elide.
///
/// A plain memset over memory that is about to be freed is dead-store-
/// eliminable, and optimisers do eliminate it. The volatile pointer is what
/// stops that; it is the reason this is not simply std::fill.
void SecureZero(char* data, size_t size) {
if (data == nullptr || size == 0) return;
volatile char* p = data;
while (size-- > 0) *p++ = 0;
}
} // namespace
void EMailSecret::Wipe() {
if (bytes_.empty()) return;
SecureZero(bytes_.data(), bytes_.size());
bytes_.clear();
bytes_.shrink_to_fit();
}
auto EMailSecret::AdoptBuffer(GFSDKContext* ctx, GFBufferRef source)
-> std::shared_ptr<EMailSecret> {
auto secret = std::make_shared<EMailSecret>();
if (source == nullptr) return secret;
const auto* data = static_cast<const char*>(GFBufferData(ctx, source));
const auto size = GFBufferSize(ctx, source);
if (data != nullptr && size != 0) {
secret->bytes_.assign(data, data + size);
}
// Release wipes: the secret exists in exactly one place from here on, and
// that place is a vector this class can erase.
GFBufferRelease(ctx, source);
return secret;
}
auto EMailSecret::CopyFrom(const QString& text)
-> std::shared_ptr<EMailSecret> {
auto secret = std::make_shared<EMailSecret>();
// A freshly built temporary, so its buffer is unshared and overwriting it
// reaches the bytes rather than detaching a copy -- which is exactly the
// distinction this class exists to make. The QString the caller holds is
// still beyond reach; that is theirs to let go of quickly.
auto utf8 = text.toUtf8();
secret->bytes_.assign(utf8.constData(), utf8.constData() + utf8.size());
SecureZero(utf8.data(), static_cast<size_t>(utf8.size()));
return secret;
}
auto EMailSecret::ToSecureCString() const -> char* {
auto* buffer =
static_cast<char*>(GFMemAlloc(GFModuleSdkContext(), GF_ARENA_SECURE,
static_cast<uint32_t>(bytes_.size() + 1)));
if (buffer == nullptr) return nullptr;
if (!bytes_.empty()) std::memcpy(buffer, bytes_.data(), bytes_.size());
buffer[bytes_.size()] = '\0';
return buffer;
}
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