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Telegram/SourceFiles/mtproto/details/mtproto_serialized_request.cpp

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+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#include "mtproto/details/mtproto_serialized_request.h"
+
+#include "base/random.h"
+
+namespace MTP::details {
+namespace {
+
+uint32 CountPaddingPrimesCount(
+		uint32 requestSize,
+		bool forAuthKeyInner) {
+	if (forAuthKeyInner) {
+		return ((8 + requestSize) & 0x03)
+			? (4 - ((8 + requestSize) & 0x03))
+			: 0;
+	}
+	auto result = ((8 + requestSize) & 0x03)
+		? (4 - ((8 + requestSize) & 0x03))
+		: 0;
+
+	// At least 12 bytes of random padding.
+	if (result < 3) {
+		result += 4;
+	}
+
+	// Some more random padding.
+	return result + ((base::RandomValue<uchar>() & 0x0F) << 2);
+}
+
+} // namespace
+
+SerializedRequest::SerializedRequest(const RequestConstructHider::Tag &tag)
+: _data(std::make_shared<RequestData>(tag)) {
+}
+
+SerializedRequest SerializedRequest::Prepare(
+		uint32 size,
+		uint32 reserveSize) {
+	Expects(size > 0);
+
+	const auto finalSize = std::max(size, reserveSize);
+
+	auto result = SerializedRequest(RequestConstructHider::Tag{});
+	result->reserve(kMessageBodyPosition + finalSize);
+	result->resize(kMessageBodyPosition);
+	result->back() = (size << 2);
+	result->lastSentTime = crl::now();
+	return result;
+}
+
+RequestData *SerializedRequest::operator->() const {
+	Expects(_data != nullptr);
+
+	return _data.get();
+}
+
+RequestData &SerializedRequest::operator*() const {
+	Expects(_data != nullptr);
+
+	return *_data;
+}
+
+SerializedRequest::operator bool() const {
+	return (_data != nullptr);
+}
+
+void SerializedRequest::setMsgId(mtpMsgId msgId) {
+	Expects(_data != nullptr);
+	Expects(_data->size() > kMessageBodyPosition);
+
+	memcpy(_data->data() + kMessageIdPosition, &msgId, sizeof(mtpMsgId));
+}
+
+mtpMsgId SerializedRequest::getMsgId() const {
+	Expects(_data != nullptr);
+	Expects(_data->size() > kMessageBodyPosition);
+
+	return *(mtpMsgId*)(_data->constData() + kMessageIdPosition);
+}
+
+void SerializedRequest::setSeqNo(uint32 seqNo) {
+	Expects(_data != nullptr);
+	Expects(_data->size() > kMessageBodyPosition);
+
+	(*_data)[kSeqNoPosition] = mtpPrime(seqNo);
+}
+
+uint32 SerializedRequest::getSeqNo() const {
+	Expects(_data != nullptr);
+	Expects(_data->size() > kMessageBodyPosition);
+
+	return uint32((*_data)[kSeqNoPosition]);
+}
+
+void SerializedRequest::addPadding(bool forAuthKeyInner) {
+	Expects(_data != nullptr);
+	Expects(_data->size() > kMessageBodyPosition);
+
+	const auto requestSize = (tl::count_length(*this) >> 2);
+	const auto padding = CountPaddingPrimesCount(
+		requestSize,
+		forAuthKeyInner);
+	const auto fullSize = kMessageBodyPosition + requestSize + padding;
+	if (uint32(_data->size()) != fullSize) {
+		_data->resize(fullSize);
+		if (padding > 0) {
+			bytes::set_random(bytes::make_span(*_data).subspan(
+				(fullSize - padding) * sizeof(mtpPrime)));
+		}
+	}
+}
+
+uint32 SerializedRequest::messageSize() const {
+	Expects(_data != nullptr);
+	Expects(_data->size() > kMessageBodyPosition);
+
+	const auto ints = (tl::count_length(*this) >> 2);
+	return kMessageIdInts + kSeqNoInts + kMessageLengthInts + ints;
+}
+
+bool SerializedRequest::needAck() const {
+	Expects(_data != nullptr);
+	Expects(_data->size() > kMessageBodyPosition);
+
+	const auto type = mtpTypeId((*_data)[kMessageBodyPosition]);
+	switch (type) {
+	case mtpc_msg_container:
+	case mtpc_msgs_ack:
+	case mtpc_http_wait:
+	case mtpc_bad_msg_notification:
+	case mtpc_msgs_all_info:
+	case mtpc_msgs_state_info:
+	case mtpc_msg_detailed_info:
+	case mtpc_msg_new_detailed_info:
+		return false;
+	}
+	return true;
+}
+
+size_t SerializedRequest::sizeInBytes() const {
+	Expects(!_data || _data->size() > kMessageBodyPosition);
+	return _data ? (*_data)[kMessageLengthPosition] : 0;
+}
+
+const void *SerializedRequest::dataInBytes() const {
+	Expects(!_data || _data->size() > kMessageBodyPosition);
+	return _data ? (_data->constData() + kMessageBodyPosition) : nullptr;
+}
+
+} // namespace MTP