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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)
//
#pragma once
#include "td/mtproto/IStreamTransport.h"
#include "td/utils/AesCtrByteFlow.h"
#include "td/utils/buffer.h"
#include "td/utils/ByteFlow.h"
#include "td/utils/common.h"
#include "td/utils/crypto.h"
#include "td/utils/port/Fd.h"
#include "td/utils/Status.h"
namespace td {
namespace mtproto {
namespace tcp {
class ITransport {
// Writes packet into message.
// Returns 0 if everything is ok, and [expected_size] otherwise.
// There is no sense to call this function when [stream->size > expected_size]
//
// (tpc is stream-base protocol. So the input message is a stream, not a slice)
virtual size_t read_from_stream(ChainBufferReader *stream, BufferSlice *message, uint32 *quick_ack) = 0;
// Writes header inplace.
virtual void write_prepare_inplace(BufferWriter *message, bool quick_ack) = 0;
// Writes first several bytes into output stream.
virtual void init_output_stream(ChainBufferWriter *stream) = 0;
virtual bool support_quick_ack() const = 0;
public:
ITransport() = default;
ITransport(const ITransport &) = delete;
ITransport &operator=(const ITransport &) = delete;
ITransport(ITransport &&) = delete;
ITransport &operator=(ITransport &&) = delete;
virtual ~ITransport() = default;
};
class AbridgedTransport : public ITransport {
public:
size_t read_from_stream(ChainBufferReader *stream, BufferSlice *message, uint32 *quick_ack) override;
void write_prepare_inplace(BufferWriter *message, bool quick_ack) override;
void init_output_stream(ChainBufferWriter *stream) override;
bool support_quick_ack() const override {
return false;
}
};
class IntermediateTransport : ITransport {
public:
size_t read_from_stream(ChainBufferReader *stream, BufferSlice *message, uint32 *quick_ack) override;
void write_prepare_inplace(BufferWriter *message, bool quick_ack) override;
void init_output_stream(ChainBufferWriter *stream) override;
bool support_quick_ack() const override {
return true;
}
};
using TransportImpl = IntermediateTransport;
class OldTransport : public IStreamTransport {
public:
OldTransport() = default;
Result<size_t> read_next(BufferSlice *message, uint32 *quick_ack) override TD_WARN_UNUSED_RESULT {
return impl_.read_from_stream(input_, message, quick_ack);
}
bool support_quick_ack() const override {
return impl_.support_quick_ack();
}
void write(BufferWriter &&message, bool quick_ack) override {
impl_.write_prepare_inplace(&message, quick_ack);
output_->append(message.as_buffer_slice());
}
void init(ChainBufferReader *input, ChainBufferWriter *output) override {
input_ = input;
output_ = output;
impl_.init_output_stream(output_);
}
bool can_read() const override {
return true;
}
bool can_write() const override {
return true;
}
size_t max_prepend_size() const override {
return 4;
}
TransportType get_type() const override {
return TransportType::Tcp;
}
private:
TransportImpl impl_;
ChainBufferReader *input_;
ChainBufferWriter *output_;
};
class ObfuscatedTransport : public IStreamTransport {
public:
ObfuscatedTransport() = default;
Result<size_t> read_next(BufferSlice *message, uint32 *quick_ack) override TD_WARN_UNUSED_RESULT {
aes_ctr_byte_flow_.wakeup();
return impl_.read_from_stream(byte_flow_sink_.get_output(), message, quick_ack);
}
bool support_quick_ack() const override {
return impl_.support_quick_ack();
}
void write(BufferWriter &&message, bool quick_ack) override {
impl_.write_prepare_inplace(&message, quick_ack);
auto slice = message.as_buffer_slice();
output_state_.encrypt(slice.as_slice(), slice.as_slice());
output_->append(std::move(slice));
}
void init(ChainBufferReader *input, ChainBufferWriter *output) override;
bool can_read() const override {
return true;
}
bool can_write() const override {
return true;
}
size_t max_prepend_size() const override {
return 4;
}
TransportType get_type() const override {
return TransportType::ObfuscatedTcp;
}
private:
TransportImpl impl_;
AesCtrByteFlow aes_ctr_byte_flow_;
ByteFlowSink byte_flow_sink_;
ChainBufferReader *input_;
// TODO: use ByteFlow?
// One problem is that BufferedFd owns output_buffer_
// The other problem is that first 56 bytes must be sent unencrypted.
UInt256 output_key_;
AesCtrState output_state_;
ChainBufferWriter *output_;
};
using Transport = ObfuscatedTransport;
} // namespace tcp
} // namespace mtproto
} // namespace td
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