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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
*
*/
#pragma once
#include <QString>
#include <memory>
// The test target defines this on the command line; the module build does
// not, so it is set here and guarded rather than assumed either way.
#ifndef VMIME_STATIC
#define VMIME_STATIC
#endif
#include <vmime/vmime.hpp>
#include "EMailAccountModel.h"
/**
* @brief Everything that decides how secure a mail connection is.
*
* Collected in one place on purpose. vmime's defaults are wrong for our
* purposes in two ways that are easy to miss and expensive to get wrong:
*
* - its certificate verifier trusts nothing, because its root list starts
* empty, so verification has to be supplied rather than merely left on;
* - `connection.tls.required` defaults to false, so a server that refuses
* STARTTLS silently yields a cleartext session that then sends the
* password.
*
* Neither is configurable here, and neither should become configurable.
*/
namespace EMailTlsSetup {
/**
* @brief The certificate ONE connection was offered.
*
* Per connection, deliberately. This used to be a single process-global slot
* written by every verification in the process, so two connections in flight
* -- a settings-page probe and a mailbox browser, say -- overwrote each
* other's. A mutex made that free of data races and no less wrong: the
* "trust this certificate?" dialog could show one server's fingerprint and
* then pin it to a different account.
*/
struct SeenCertificate {
/// Lowercase hex SHA-256, or empty when nothing was captured.
QString fingerprint;
/// Validity dates, subject, and whether it names the host asked for.
QString summary;
};
using SeenCertificatePtr = std::shared_ptr<SeenCertificate>;
/**
* @brief Apply this application's security policy to a session and service.
*
* Sets the transport properties that make TLS mandatory, requires
* authentication where the protocol treats it as optional, installs the
* certificate verifier, and applies any certificate the user has pinned for
* this transport.
*
* @param session the vmime session whose properties are being set
* @param service the store or transport to attach the verifier to
* @param prefix property prefix, e.g. "store.imaps" or "transport.smtp"
* @param config the transport being connected
* @param imap true for IMAP, false for SMTP. Only SMTP treats authentication
* as optional, so only SMTP needs it demanded; see the property below.
* @return the slot this connection's verifier records what it saw in. Keep it
* for as long as the connection attempt lasts and read it if the attempt
* fails on a certificate.
*/
auto Apply(const vmime::shared_ptr<vmime::net::session>& session,
const vmime::shared_ptr<vmime::net::service>& service,
const QString& prefix, const MailTransportConfig& config, bool imap)
-> SeenCertificatePtr;
/**
* @brief The vmime protocol name for a transport.
*
* @param imap true for IMAP, false for SMTP
* @param mode the chosen security
* @return "imaps"/"imap" or "smtps"/"smtp"
*/
auto ProtocolName(bool imap, MailTlsMode mode) -> QString;
/**
* @brief Whether a connection actually ended up encrypted.
*
* Asked before a credential is handed over, so that a policy failure can never
* become a leaked password. vmime reports a secured connection by the concrete
* type of its connection infos rather than by a flag.
*
* @param service a connected store or transport
* @return true when the link is TLS-protected
*/
auto IsSecured(const vmime::shared_ptr<vmime::net::service>& service) -> bool;
} // namespace EMailTlsSetup
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