Allow restricting forwards in groups / channels.

Telegram/Resources/langs/lang.strings

@@ -148,6 +148,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 "lng_error_admin_limit" = "Sorry, you've reached the maximum number of admins for this group.";
 "lng_error_admin_limit_channel" = "Sorry, you've reached the maximum number of admins for this channel.";
 "lng_error_post_link_invalid" = "Unfortunately, you can't access this message. You are not a member of the chat where it was posted.";
+"lng_error_noforwards_group" = "Sorry, forwarding is disabled from this group.";
+"lng_error_noforwards_channel" = "Sorry, forwarding is disabled from this channel.";
 "lng_sure_add_admin_invite" = "This user is not a member of this group. Add them to the group and promote them to admin?";
 "lng_sure_add_admin_invite_channel" = "This user is not a subscriber of this channel. Add them to the channel and promote them to admin?";
 "lng_sure_add_admin_unremove" = "This user is currently restricted or removed. Are you sure you want to promote them?";
@@ -1808,6 +1810,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 "lng_edit_contact_title" = "Edit contact name";
 "lng_edit_channel_title" = "Edit channel";
 "lng_edit_sign_messages" = "Sign messages";
+"lng_edit_allow_forwards" = "Allow saving content";
 "lng_edit_group" = "Edit group";
 "lng_edit_self_title" = "Edit your name";
 "lng_confirm_contact_data" = "New Contact";

Telegram/SourceFiles/apiwrap.cpp

@@ -504,6 +504,11 @@ void ApiWrap::sendMessageFail(
 			scheduled.removeSending(item);
 			Ui::show(Box<Ui::InformBox>(tr::lng_cant_do_this(tr::now)));
 		}
+	} else if (error.type() == qstr("CHAT_FORWARDS_RESTRICTED")) {
+		Ui::ShowMultilineToast({ .text = { peer->isBroadcast()
+			? tr::lng_error_noforwards_channel(tr::now)
+			: tr::lng_error_noforwards_group(tr::now)
+		}, .duration = kJoinErrorDuration });
 	}
 	if (const auto item = _session->data().message(itemId)) {
 		Assert(randomId != 0);

Telegram/SourceFiles/boxes/peers/edit_peer_info_box.cpp

@@ -277,6 +277,7 @@ private:
 		std::optional<QString> description;
 		std::optional<bool> hiddenPreHistory;
 		std::optional<bool> signatures;
+		std::optional<bool> forwards;
 		std::optional<ChannelData*> linkedChat;
 	};
 
@@ -296,6 +297,7 @@ private:
 	void fillLinkedChatButton();
 	//void fillInviteLinkButton();
 	void fillSignaturesButton();
+	void fillForwardsButton();
 	void fillHistoryVisibilityButton();
 	void fillManageSection();
 	void fillPendingRequestsButton();
@@ -312,6 +314,7 @@ private:
 	bool validateDescription(Saving &to) const;
 	bool validateHistoryVisibility(Saving &to) const;
 	bool validateSignatures(Saving &to) const;
+	bool validateForwards(Saving &to) const;
 
 	void save();
 	void saveUsername();
@@ -320,6 +323,7 @@ private:
 	void saveDescription();
 	void saveHistoryVisibility();
 	void saveSignatures();
+	void saveForwards();
 	void savePhoto();
 	void pushSaveStage(FnMut<void()> &&lambda);
 	void continueSave();
@@ -341,6 +345,7 @@ private:
 	std::optional<HistoryVisibility> _historyVisibilitySavedValue;
 	std::optional<QString> _usernameSavedValue;
 	std::optional<bool> _signaturesSavedValue;
+	std::optional<bool> _forwardsSavedValue;
 
 	const not_null<Window::SessionNavigation*> _navigation;
 	const not_null<Ui::BoxContent*> _box;
@@ -795,6 +800,21 @@ void Controller::fillSignaturesButton() {
 	}, _controls.buttonsLayout->lifetime());
 }
 
+void Controller::fillForwardsButton() {
+	Expects(_controls.buttonsLayout != nullptr);
+
+	AddButtonWithText(
+		_controls.buttonsLayout,
+		tr::lng_edit_allow_forwards(),
+		rpl::single(QString()),
+		[=] {}
+	)->toggleOn(rpl::single(_peer->allowsForwarding())
+	)->toggledValue(
+	) | rpl::start_with_next([=](bool toggled) {
+		_forwardsSavedValue = toggled;
+	}, _controls.buttonsLayout->lifetime());
+}
+
 void Controller::fillHistoryVisibilityButton() {
 	Expects(_controls.buttonsLayout != nullptr);
 
@@ -864,6 +884,9 @@ void Controller::fillManageSection() {
 			? (channel->canEditSignatures() && !channel->isMegagroup())
 			: false;
 	}();
+	const auto canEditForwards = [&] {
+		return isChannel ? channel->amCreator() : chat->amCreator();
+	}();
 	const auto canEditPreHistoryHidden = [&] {
 		return isChannel
 			? channel->canEditPreHistoryHidden()
@@ -937,8 +960,12 @@ void Controller::fillManageSection() {
 	if (canEditSignatures) {
 		fillSignaturesButton();
 	}
+	if (canEditForwards) {
+		fillForwardsButton();
+	}
 	if (canEditPreHistoryHidden
 		|| canEditSignatures
+		|| canEditForwards
 		//|| canEditInviteLinks
 		|| canViewOrEditLinkedChat
 		|| canEditUsername) {
@@ -1154,7 +1181,8 @@ std::optional<Controller::Saving> Controller::validate() const {
 		&& validateTitle(result)
 		&& validateDescription(result)
 		&& validateHistoryVisibility(result)
-		&& validateSignatures(result)) {
+		&& validateSignatures(result)
+		&& validateForwards(result)) {
 		return result;
 	}
 	return {};
@@ -1229,6 +1257,14 @@ bool Controller::validateSignatures(Saving &to) const {
 	return true;
 }
 
+bool Controller::validateForwards(Saving &to) const {
+	if (!_forwardsSavedValue.has_value()) {
+		return true;
+	}
+	to.forwards = _forwardsSavedValue;
+	return true;
+}
+
 void Controller::save() {
 	Expects(_wrap != nullptr);
 
@@ -1243,6 +1279,7 @@ void Controller::save() {
 		pushSaveStage([=] { saveDescription(); });
 		pushSaveStage([=] { saveHistoryVisibility(); });
 		pushSaveStage([=] { saveSignatures(); });
+		pushSaveStage([=] { saveForwards(); });
 		pushSaveStage([=] { savePhoto(); });
 		continueSave();
 	}
@@ -1499,6 +1536,26 @@ void Controller::saveSignatures() {
 	}).send();
 }
 
+void Controller::saveForwards() {
+	if (!_savingData.forwards
+		|| *_savingData.forwards == _peer->allowsForwarding()) {
+		return continueSave();
+	}
+	_api.request(MTPmessages_ToggleNoForwards(
+		_peer->input,
+		MTP_bool(!*_savingData.forwards)
+	)).done([=](const MTPUpdates &result) {
+		_peer->session().api().applyUpdates(result);
+		continueSave();
+	}).fail([=](const MTP::Error &error) {
+		if (error.type() == qstr("CHAT_NOT_MODIFIED")) {
+			continueSave();
+		} else {
+			cancelSave();
+		}
+	}).send();
+}
+
 void Controller::savePhoto() {
 	auto image = _controls.photo
 		? _controls.photo->takeResultImage()

Telegram/SourceFiles/data/data_channel.cpp

@@ -470,6 +470,10 @@ bool ChannelData::canWrite() const {
 				&& !amRestricted(Restriction::SendMessages)));
 }
 
+bool ChannelData::allowsForwarding() const {
+	return !(flags() & Flag::NoForwards);
+}
+
 bool ChannelData::canViewMembers() const {
 	return flags() & Flag::CanViewParticipants;
 }

Telegram/SourceFiles/data/data_channel.h

@@ -50,6 +50,7 @@ enum class ChannelDataFlag {
 	CanViewParticipants = (1 << 17),
 	HasLink = (1 << 18),
 	SlowmodeEnabled = (1 << 19),
+	NoForwards = (1 << 20),
 };
 inline constexpr bool is_flag_type(ChannelDataFlag) { return true; };
 using ChannelDataFlags = base::flags<ChannelDataFlag>;
@@ -293,6 +294,7 @@ public:
 
 	// Like in ChatData.
 	[[nodiscard]] bool canWrite() const;
+	[[nodiscard]] bool allowsForwarding() const;
 	[[nodiscard]] bool canEditInformation() const;
 	[[nodiscard]] bool canEditPermissions() const;
 	[[nodiscard]] bool canEditUsername() const;

Telegram/SourceFiles/data/data_chat.cpp

@@ -28,7 +28,7 @@ ChatData::ChatData(not_null<Data::Session*> owner, PeerId id)
 , inputChat(MTP_long(peerToChat(id).bare)) {
 	_flags.changes(
 	) | rpl::start_with_next([=](const Flags::Change &change) {
-		if (change.diff & ChatDataFlag::CallNotEmpty) {
+		if (change.diff & Flag::CallNotEmpty) {
 			if (const auto history = this->owner().historyLoaded(this)) {
 				history->updateChatListEntry();
 			}
@@ -63,6 +63,10 @@ bool ChatData::canWrite() const {
 	return amIn() && !amRestricted(Restriction::SendMessages);
 }
 
+bool ChatData::allowsForwarding() const {
+	return !(flags() & Flag::NoForwards);
+}
+
 bool ChatData::canEditInformation() const {
 	return amIn() && !amRestricted(Restriction::ChangeInfo);
 }
@@ -74,7 +78,7 @@ bool ChatData::canEditPermissions() const {
 
 bool ChatData::canEditUsername() const {
 	return amCreator()
-		&& (flags() & ChatDataFlag::CanSetUsername);
+		&& (flags() & Flag::CanSetUsername);
 }
 
 bool ChatData::canEditPreHistoryHidden() const {
@@ -222,7 +226,7 @@ void ChatData::setGroupCall(
 			scheduleDate);
 		owner().registerGroupCall(_call.get());
 		session().changes().peerUpdated(this, UpdateFlag::GroupCall);
-		addFlags(ChatDataFlag::CallActive);
+		addFlags(Flag::CallActive);
 	});
 }
 
@@ -236,7 +240,7 @@ void ChatData::clearGroupCall() {
 		_call = nullptr;
 	}
 	session().changes().peerUpdated(this, UpdateFlag::GroupCall);
-	removeFlags(ChatDataFlag::CallActive | ChatDataFlag::CallNotEmpty);
+	removeFlags(Flag::CallActive | Flag::CallNotEmpty);
 }
 
 void ChatData::setGroupCallDefaultJoinAs(PeerId peerId) {

Telegram/SourceFiles/data/data_chat.h

@@ -18,6 +18,7 @@ enum class ChatDataFlag {
 	CallActive = (1 << 5),
 	CallNotEmpty = (1 << 6),
 	CanSetUsername = (1 << 7),
+	NoForwards = (1 << 8),
 };
 inline constexpr bool is_flag_type(ChatDataFlag) { return true; };
 using ChatDataFlags = base::flags<ChatDataFlag>;
@@ -109,6 +110,7 @@ public:
 
 	// Like in ChannelData.
 	[[nodiscard]] bool canWrite() const;
+	[[nodiscard]] bool allowsForwarding() const;
 	[[nodiscard]] bool canEditInformation() const;
 	[[nodiscard]] bool canEditPermissions() const;
 	[[nodiscard]] bool canEditUsername() const;

Telegram/SourceFiles/data/data_peer.cpp

@@ -848,6 +848,17 @@ bool PeerData::canWrite() const {
 	return false;
 }
 
+bool PeerData::allowsForwarding() const {
+	if (const auto user = asUser()) {
+		return true;
+	} else if (const auto channel = asChannel()) {
+		return channel->allowsForwarding();
+	} else if (const auto chat = asChat()) {
+		return chat->allowsForwarding();
+	}
+	return false;
+}
+
 Data::RestrictionCheckResult PeerData::amRestricted(
 		ChatRestriction right) const {
 	using Result = Data::RestrictionCheckResult;

Telegram/SourceFiles/data/data_peer.h

@@ -274,6 +274,7 @@ public:
 	}
 
 	[[nodiscard]] bool canWrite() const;
+	[[nodiscard]] bool allowsForwarding() const;
 	[[nodiscard]] Data::RestrictionCheckResult amRestricted(
 		ChatRestriction right) const;
 	[[nodiscard]] bool amAnonymous() const;

Telegram/SourceFiles/data/data_session.cpp

@@ -641,7 +641,8 @@ not_null<PeerData*> Session::processChat(const MTPChat &data) {
 			| Flag::Deactivated
 			| Flag::Forbidden
 			| Flag::CallActive
-			| Flag::CallNotEmpty;
+			| Flag::CallNotEmpty
+			| Flag::NoForwards;
 		const auto flagsSet = (data.is_left() ? Flag::Left : Flag())
 			| (data.is_kicked() ? Flag::Kicked : Flag())
 			| (data.is_creator() ? Flag::Creator : Flag())
@@ -651,7 +652,8 @@ not_null<PeerData*> Session::processChat(const MTPChat &data) {
 				|| (chat->groupCall()
 					&& chat->groupCall()->fullCount() > 0))
 				? Flag::CallNotEmpty
-				: Flag());
+				: Flag())
+			| (data.is_noforwards() ? Flag::NoForwards : Flag());
 		chat->setFlags((chat->flags() & ~flagsMask) | flagsSet);
 		chat->count = data.vparticipants_count().v;
 
@@ -739,10 +741,8 @@ not_null<PeerData*> Session::processChat(const MTPChat &data) {
 			| Flag::CallActive
 			| Flag::CallNotEmpty
 			| Flag::Forbidden
-			| (!minimal
+			| (!minimal ? (Flag::Left | Flag::Creator) : Flag())
-				? Flag::Left
+			| Flag::NoForwards;
-				| Flag::Creator
-				: Flag());
 		const auto flagsSet = (data.is_broadcast() ? Flag::Broadcast : Flag())
 			| (data.is_verified() ? Flag::Verified : Flag())
 			| (data.is_scam() ? Flag::Scam : Flag())
@@ -762,7 +762,8 @@ not_null<PeerData*> Session::processChat(const MTPChat &data) {
 			| (!minimal
 				? (data.is_left() ? Flag::Left : Flag())
 				| (data.is_creator() ? Flag::Creator : Flag())
-				: Flag());
+				: Flag())
+			| (data.is_noforwards() ? Flag::NoForwards : Flag());
 		channel->setFlags((channel->flags() & ~flagsMask) | flagsSet);
 
 		channel->setName(

Telegram/SourceFiles/history/history_message.cpp

@@ -1038,7 +1038,9 @@ void HistoryMessage::applySentMessage(
 }
 
 bool HistoryMessage::allowsForward() const {
-	return isRegular() && (!_media || _media->allowsForward());
+	return isRegular()
+		&& history()->peer->allowsForwarding()
+		&& (!_media || _media->allowsForward());
 }
 
 bool HistoryMessage::allowsSendNow() const {