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// SPDX-FileCopyrightText: 2022 Linus Jahn <lnj@kaidan.im>
//
// SPDX-License-Identifier: LGPL-2.1-or-later
#include "QXmppCarbonManagerV2.h"
#include "QXmppClient.h"
#include "QXmppConstants_p.h"
#include "QXmppFutureUtils_p.h"
#include "QXmppMessage.h"
#include <QDomElement>
#include <QStringBuilder>
using namespace QXmpp;
using namespace QXmpp::Private;
class CarbonEnableIq : public QXmppIq
{
public:
CarbonEnableIq()
: QXmppIq()
{
setType(QXmppIq::Set);
}
// parsing not implemented
void parseElementFromChild(const QDomElement &) override
{
}
void toXmlElementFromChild(QXmlStreamWriter *writer) const override
{
writer->writeStartElement(QStringLiteral("enable"));
writer->writeDefaultNamespace(ns_carbons);
writer->writeEndElement();
}
};
auto firstXmlnsElement(const QDomElement &el, const char *xmlns)
{
for (auto child = el.firstChildElement();
!child.isNull();
child = child.nextSiblingElement()) {
if (child.namespaceURI() == xmlns) {
return child;
}
}
return QDomElement();
}
auto firstChildElement(const QDomElement &el, const char *tagName, const char *xmlns)
{
for (auto child = el.firstChild();
!child.isNull();
child = child.nextSibling()) {
if (child.isElement() && child.namespaceURI() == xmlns) {
auto childEl = child.toElement();
if (childEl.tagName() == tagName) {
return childEl;
}
}
}
return QDomElement();
}
auto parseIq(std::variant<QDomElement, QXmppError> &&sendResult) -> std::optional<QXmppError>
{
if (auto el = std::get_if<QDomElement>(&sendResult)) {
auto iqType = el->attribute(QStringLiteral("type"));
if (iqType == "result") {
return {};
}
QXmppIq iq;
iq.parse(*el);
if (auto error = iq.errorOptional()) {
return QXmppError { error->text(), std::move(*error) };
}
// Only happens with IQs with type=error, but no <error/> element
return QXmppError { QStringLiteral("Unknown error received."), QXmppStanza::Error() };
} else if (auto err = std::get_if<QXmppError>(&sendResult)) {
return *err;
}
return {};
}
///
/// \class QXmppCarbonManagerV2
///
/// \brief The QXmppCarbonManagerV2 class handles message carbons as described in \xep{0280,
/// Message Carbons}.
///
/// The manager automatically enables carbons when a connection is established. If the connection
/// could be resumed, no new request is done. Carbon copied messages from other devices of the same
/// account and carbon copied messages from other accounts are injected into the QXmppClient. This
/// way you can handle them like any other incoming message by implementing QXmppMessageHandler or
/// using QXmppClient::messageReceived().
///
/// Checks are done to ensure that the entity sending the carbon copy is allowed to send the
/// forwarded message.
///
/// You don't need to do anything other than adding the extension to the client to use it.
/// \code
/// QXmppClient client;
/// client.addNewExtension<QXmppCarbonManagerV2>();
/// \endcode
///
/// To distinguish carbon messages, you can use QXmppMessage::isCarbonMessage().
///
/// \ingroup Managers
///
/// \since QXmpp 1.5
///
QXmppCarbonManagerV2::QXmppCarbonManagerV2() = default;
QXmppCarbonManagerV2::~QXmppCarbonManagerV2() = default;
bool QXmppCarbonManagerV2::handleStanza(const QDomElement &element, const std::optional<QXmppE2eeMetadata> &)
{
if (element.tagName() != "message") {
return false;
}
auto carbon = firstXmlnsElement(element, ns_carbons);
if (carbon.isNull() || (carbon.tagName() != "sent" && carbon.tagName() != "received")) {
return false;
}
// carbon copies must always come from our bare JID
auto from = element.attribute(QStringLiteral("from"));
if (from != client()->configuration().jidBare()) {
info("Received carbon copy from attacker or buggy client '" % from %
"' trying to use CVE-2017-5603.");
return false;
}
auto forwarded = firstChildElement(carbon, "forwarded", ns_forwarding);
auto messageElement = firstChildElement(forwarded, "message", ns_client);
if (messageElement.isNull()) {
return false;
}
QXmppMessage message;
message.parse(messageElement);
message.setCarbonForwarded(true);
injectMessage(std::move(message));
return true;
}
void QXmppCarbonManagerV2::setClient(QXmppClient *newClient)
{
if (client()) {
disconnect(client(), &QXmppClient::connected, this, &QXmppCarbonManagerV2::enableCarbons);
}
QXmppClientExtension::setClient(newClient);
connect(newClient, &QXmppClient::connected, this, &QXmppCarbonManagerV2::enableCarbons);
}
void QXmppCarbonManagerV2::enableCarbons()
{
if (client()->streamManagementState() == QXmppClient::ResumedStream) {
// skip re-enabling for resumed streams
return;
}
client()->sendIq(CarbonEnableIq()).then(this, [this](QXmppClient::IqResult domResult) {
if (auto err = parseIq(std::move(domResult))) {
warning("Could not enable message carbons: " % err->description);
} else {
info("Message Carbons enabled.");
}
});
}
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