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tdlib-fork/td/mtproto/TcpTransport.cpp

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//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#include "td/mtproto/TcpTransport.h"
namespace td {
namespace mtproto {
namespace tcp {
size_t IntermediateTransport::read_from_stream(ChainBufferReader *stream, BufferSlice *message, uint32 *quick_ack) {
CHECK(message);
size_t stream_size = stream->size();
size_t header_size = 4;
if (stream->size() < header_size) {
return header_size;
}
uint32 data_size;
auto it = stream->clone();
it.advance(header_size, MutableSlice(reinterpret_cast<uint8 *>(&data_size), sizeof(data_size)));
if (data_size & (1u << 31)) {
if (quick_ack) {
*quick_ack = data_size;
}
stream->advance(header_size);
return 0;
}
size_t total_size = data_size + header_size;
if (stream_size < total_size) {
// optimization
// stream->make_solid(total_size);
return total_size;
}
stream->advance(header_size);
*message = stream->cut_head(data_size).move_as_buffer_slice();
return 0;
}
void IntermediateTransport::write_prepare_inplace(BufferWriter *message, bool quick_ack) {
size_t size = message->size();
CHECK(size % 4 == 0);
CHECK(size < (1 << 24));
if (quick_ack) {
size |= static_cast<size_t>(1) << 31;
}
size_t prepend_size = 4;
MutableSlice prepend = message->prepare_prepend();
CHECK(prepend.size() >= prepend_size);
message->confirm_prepend(prepend_size);
as<uint32>(message->as_slice().begin()) = static_cast<uint32>(size);
}
void IntermediateTransport::init_output_stream(ChainBufferWriter *stream) {
const uint32 magic = 0xeeeeeeee;
stream->append(Slice(reinterpret_cast<const char *>(&magic), 4));
}
size_t AbridgedTransport::read_from_stream(ChainBufferReader *stream, BufferSlice *message, uint32 *quick_ack) {
if (stream->empty()) {
return 1;
}
uint8 byte = 0;
stream->clone().advance(1, MutableSlice(&byte, 1));
size_t header_size;
uint32 data_size;
if (byte < 0x7f) {
header_size = 1;
data_size = byte * 4u;
} else {
if (stream->size() < 4) {
return 4;
}
header_size = 4;
stream->clone().advance(4, MutableSlice(reinterpret_cast<char *>(&data_size), sizeof(data_size)));
data_size >>= 8;
data_size = data_size * 4;
}
size_t total_size = header_size + data_size;
if (stream->size() < total_size) {
// optimization
// stream->make_solid(total_size);
return total_size;
}
stream->advance(header_size);
*message = stream->cut_head(data_size).move_as_buffer_slice();
return 0;
}
void AbridgedTransport::write_prepare_inplace(BufferWriter *message, bool quick_ack) {
CHECK(!quick_ack);
size_t size = message->size() / 4;
CHECK(size % 4 == 0);
CHECK(size < 1 << 24);
size_t prepend_size = size >= 0x7f ? 4 : 1;
MutableSlice prepend = message->prepare_prepend();
CHECK(prepend.size() >= prepend_size);
message->confirm_prepend(prepend_size);
MutableSlice data = message->as_slice();
if (size >= 0x7f) {
uint32 size_encoded = 0x7f + (static_cast<uint32>(size) << 8);
as<uint32>(data.begin()) = size_encoded;
} else {
as<uint8>(data.begin()) = static_cast<uint8>(size);
}
}
void AbridgedTransport::init_output_stream(ChainBufferWriter *stream) {
const uint8 magic = 0xef;
stream->append(Slice(&magic, 1));
}
} // namespace tcp
} // namespace mtproto
} // namespace td