Suggest anti-spoof logic for CustomURLs

Telegram/Resources/langs/lang.strings

@@ -3070,6 +3070,12 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 "lng_url_auth_login_option" = "Log in to {domain} as {user}";
 "lng_url_auth_allow_messages" = "Allow {bot} to send me messages";
 
+"lng_open_spoof_title" = "⚠️ URL Spoofing";
+"lng_open_spoof_link" = "Do you want to open link that is masked to look like different link?";
+"lng_open_spoof_link_confirm" = "It is Safe";
+"lng_open_spoof_link_label" = "Link is shown as";
+"lng_open_spoof_link_url" = "Actual link is";
+
 "lng_bot_start" = "Start";
 "lng_bot_choose_group" = "Select a Group";
 "lng_bot_no_groups" = "You have no groups";

Telegram/SourceFiles/core/click_handler_types.cpp

@@ -27,6 +27,8 @@ For license and copyright information please follow this link:
 #include "window/window_session_controller_link_info.h"
 #include "styles/style_layers.h"
 
+#include <QUrlQuery>
+
 namespace {
 
 // Possible context owners: media viewer, profile, history widget.
@@ -81,6 +83,83 @@ bool UrlRequiresConfirmation(const QUrl &url) {
 		RegExOption::CaseInsensitive);
 }
 
+bool IsLabelImpersonateUrl(QString url, QString label) {
+	using namespace qthelp;
+	if (url == label) {
+		return false;
+	}
+
+	// avoid ' @username' workaround
+	label = label.trimmed();
+	QUrl urlObj(Core::TryConvertUrlToLocal(url));
+	QUrl labelObj(Core::TryConvertUrlToLocal(label));
+	if (labelObj.host().isEmpty()) {
+		static const auto IsHost = QRegularExpression(
+			"^\\w[\\w\\d_]+\\.\\w[^\\s]+$",
+			QRegularExpression::CaseInsensitiveOption);
+		const auto match1 = IsHost.match(labelObj.path());
+		if (match1.hasMatch()) {
+			labelObj = QUrl("https://" + label);
+		}
+	}
+
+	// check if tg username
+	if (label.startsWith("@")) {
+		// username?
+		if (urlObj.scheme() != "tg") {
+			// external website? ok
+			return false;
+		}
+	}
+
+	if (urlObj.scheme() == "tg")
+	{
+		if (label.startsWith("@")) {
+			// check tg name
+			QUrlQuery args(urlObj);
+			if (args.queryItemValue("domain").compare(label.mid(1), Qt::CaseInsensitive) != 0) {
+				return true;
+			}
+		}
+		else if (labelObj.scheme() == "tg") {
+			// tg:// urls should be exactly the same
+			return (labelObj != urlObj);
+		}
+	}
+
+	if (label.startsWith("#")) {
+		// hash tags should be EntityType::Hashtag, not CustomUrl
+		return true;
+	}
+
+	if (!labelObj.host().isEmpty()) {
+		// check matching for schema and domain
+		if (!labelObj.scheme().isEmpty() 
+			&& (urlObj.scheme() != labelObj.scheme())) {
+			if ((urlObj.scheme() == "https") && (labelObj.scheme() == "http")) {
+				// accept this case, but not vice versa
+			}
+			else {
+				// schema is different (tg!=http, or https!=http)
+				return true;
+			}
+		}
+		if (urlObj.host() != labelObj.host()) {
+			return true;
+		}
+		// urls are different somewhere in path?query - fine
+		// potentially - accept only shorten version of url
+		return false;
+	}
+	return false;
+}
+
+HiddenUrlClickHandler::HiddenUrlClickHandler(QString url, QString label)
+	: UrlClickHandler(url, false)
+	, _label(label)
+	, _isSpoof(IsLabelImpersonateUrl(url, label)) {
+}
+
 QString HiddenUrlClickHandler::copyToClipboardText() const {
 	return url().startsWith(u"internal:url:"_q)
 		? url().mid(u"internal:url:"_q.size())
@@ -102,7 +181,7 @@ QString HiddenUrlClickHandler::dragText() const {
 	return result.startsWith(u"internal:"_q) ? QString() : result;
 }
 
-void HiddenUrlClickHandler::Open(QString url, QVariant context) {
+void HiddenUrlClickHandler::Open(QString url, QVariant context, bool IsSpoof, QString label) {
 	url = Core::TryConvertUrlToLocal(url);
 	if (Core::InternalPassportLink(url)) {
 		return;
@@ -111,6 +190,45 @@ void HiddenUrlClickHandler::Open(QString url, QVariant context) {
 	const auto open = [=] {
 		UrlClickHandler::Open(url, context);
 	};
+
+	if (IsSpoof) {
+		Core::App().hideMediaView();
+		const auto displayed = url;
+		const auto displayUrl = ShowEncoded(displayed);
+		const auto my = context.value<ClickHandlerContext>();
+		const auto controller = my.sessionWindow.get();
+		const auto use = controller
+			? &controller->window()
+			: Core::App().activeWindow();
+		auto box = Box([=](not_null<Ui::GenericBox*> box) {
+			Ui::ConfirmBox(box, {
+				.text = (tr::lng_open_spoof_link(tr::now)),
+				.confirmed = [=](Fn<void()> hide) { hide(); open(); },
+				.confirmText = tr::lng_open_spoof_link_confirm(),
+				.title = (tr::lng_open_spoof_title(tr::now))
+				});
+			const auto& st = st::boxLabel;
+			const auto& stdiv = st::boxDividerLabel;
+			box->addSkip(st.style.lineHeight - st::boxPadding.bottom());
+			box->addRow(object_ptr<Ui::FlatLabel>(box, tr::lng_open_spoof_link_label(), stdiv));
+			const auto url = box->addRow(object_ptr<Ui::FlatLabel>(box, label, st));
+			box->addRow(object_ptr<Ui::FlatLabel>(box, tr::lng_open_spoof_link_url(), stdiv));
+			const auto actual_url = box->addRow(object_ptr<Ui::FlatLabel>(box, displayUrl, st));
+			url->setSelectable(true);
+			url->setContextCopyText(tr::lng_context_copy_link(tr::now));
+			actual_url->setSelectable(true);
+			actual_url->setContextCopyText(tr::lng_context_copy_link(tr::now));
+			});
+		if (my.show) {
+			my.show->showBox(std::move(box));
+		}
+		else if (use) {
+			use->show(std::move(box));
+			use->activate();
+		}
+		return;
+	}
+
 	if (url.startsWith(u"tg://"_q, Qt::CaseInsensitive)
 		|| url.startsWith(u"internal:"_q, Qt::CaseInsensitive)) {
 		UrlClickHandler::Open(url, QVariant::fromValue([&] {

Telegram/SourceFiles/core/click_handler_types.h

@@ -56,22 +56,24 @@ class PhoneClickHandler;
 
 class HiddenUrlClickHandler : public UrlClickHandler {
 public:
-	HiddenUrlClickHandler(QString url) : UrlClickHandler(url, false) {
-	}
+	HiddenUrlClickHandler(QString url, QString label);
 	QString copyToClipboardText() const override;
 	QString copyToClipboardContextItemText() const override;
 	QString dragText() const override;
 
-	static void Open(QString url, QVariant context = {});
+	static void Open(QString url, QVariant context = {}, bool IsSpoof = false, QString label = QString());
 	void onClick(ClickContext context) const override {
 		const auto button = context.button;
 		if (button == Qt::LeftButton || button == Qt::MiddleButton) {
-			Open(url(), context.other);
+			Open(url(), context.other, _isSpoof, _label);
 		}
 	}
 
 	TextEntity getTextEntity() const override;
 
+private:
+	QString _label;
+	bool _isSpoof;
 };
 
 class UserData;

Telegram/SourceFiles/core/ui_integration.cpp

@@ -155,12 +155,12 @@ std::shared_ptr<ClickHandler> UiIntegration::createLinkHandler(
 	case EntityType::Url:
 		return (!data.data.isEmpty()
 			&& UrlClickHandler::IsSuspicious(data.data))
-			? std::make_shared<HiddenUrlClickHandler>(data.data)
+			? std::make_shared<HiddenUrlClickHandler>(data.data, data.data)
 			: Integration::createLinkHandler(data, context);
 
 	case EntityType::CustomUrl:
 		return !data.data.isEmpty()
-			? std::make_shared<HiddenUrlClickHandler>(data.data)
+			? std::make_shared<HiddenUrlClickHandler>(data.data, data.text)
 			: Integration::createLinkHandler(data, context);
 
 	case EntityType::BotCommand:

Telegram/SourceFiles/history/view/media/history_view_web_page.cpp

@@ -435,7 +435,7 @@ QSize WebPage::countOptimalSize() {
 				? IvClickHandler(_data, original)
 				: (previewOfHiddenUrl || UrlClickHandler::IsSuspicious(
 					_data->url))
-				? std::make_shared<HiddenUrlClickHandler>(_data->url)
+				? std::make_shared<HiddenUrlClickHandler>(_data->url, _data->url)
 				: std::make_shared<UrlClickHandler>(_data->url, true);
 			if (_data->document
 				&& (_data->document->isWallPaper()

Telegram/SourceFiles/overview/overview_layout.cpp

@@ -1663,7 +1663,7 @@ Link::Link(
 
 	const auto createHandler = [](const QString &url) {
 		return UrlClickHandler::IsSuspicious(url)
-			? std::make_shared<HiddenUrlClickHandler>(url)
+			? std::make_shared<HiddenUrlClickHandler>(url, url)
 			: std::make_shared<UrlClickHandler>(url, false);
 	};
 	_page = media ? media->webpage() : nullptr;
@@ -1993,7 +1993,7 @@ Link::LinkEntry::LinkEntry(const QString &url, const QString &text)
 : text(text)
 , width(st::normalFont->width(text))
 , lnk(UrlClickHandler::IsSuspicious(url)
-	? std::make_shared<HiddenUrlClickHandler>(url)
+	? std::make_shared<HiddenUrlClickHandler>(url, text)
 	: std::make_shared<UrlClickHandler>(url)) {
 }