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Diffstat (limited to 'src/lib/tls/asio/asio_async_ops.h')
| -rw-r--r-- | src/lib/tls/asio/asio_async_ops.h | 368 |
1 files changed, 368 insertions, 0 deletions
diff --git a/src/lib/tls/asio/asio_async_ops.h b/src/lib/tls/asio/asio_async_ops.h new file mode 100644 index 000000000..34d9ce0dd --- /dev/null +++ b/src/lib/tls/asio/asio_async_ops.h @@ -0,0 +1,368 @@ +/* +* Helpers for TLS ASIO Stream +* (C) 2018-2019 Jack Lloyd +* 2018-2019 Hannes Rantzsch, Tim Oesterreich, Rene Meusel +* +* Botan is released under the Simplified BSD License (see license.txt) +*/ + +#ifndef BOTAN_ASIO_ASYNC_OPS_H_ +#define BOTAN_ASIO_ASYNC_OPS_H_ + +#include <botan/build.h> + +#include <boost/version.hpp> +#if BOOST_VERSION >= 106600 + +#include <botan/asio_error.h> + +// We need to define BOOST_ASIO_DISABLE_SERIAL_PORT before any asio imports. Otherwise asio will include <termios.h>, +// which interferes with Botan's amalgamation by defining macros like 'B0' and 'FF1'. +#define BOOST_ASIO_DISABLE_SERIAL_PORT +#include <boost/asio.hpp> +#include <boost/asio/yield.hpp> + +namespace Botan { +namespace TLS { +namespace detail { + +/** + * Base class for asynchronous stream operations. + * + * Asynchronous operations, used for example to implement an interface for boost::asio::async_read_some and + * boost::asio::async_write_some, are based on boost::asio::coroutines. + * Derived operations should implement a call operator and invoke it with the correct parameters upon construction. The + * call operator needs to make sure that the user-provided handler is not called directly. Typically, yield / reenter is + * used for this in the following fashion: + * + * ``` + * void operator()(boost::system::error_code ec, std::size_t bytes_transferred, bool isContinuation = true) + * { + * reenter(this) + * { + * // operation specific logic, repeatedly interacting with the stream_core and the next_layer (socket) + * + * // make sure intermediate initiating function is called + * if(!isContinuation) + * { + * yield next_layer.async_operation(empty_buffer, this); + * } + * + * // call the completion handler + * complete_now(error_code, bytes_transferred); + * } + * } + * ``` + * + * Once the operation is completed and ready to call the completion handler it checks if an intermediate initiating + * function has been called using the `isContinuation` parameter. If not, it will call an asynchronous operation, such + * as `async_read_some`, with and empty buffer, set the object itself as the handler, and `yield`. As a result, the call + * operator will be invoked again, this time as a continuation, and will jump to the location where it yielded before + * using `reenter`. It is now safe to call the handler function via `complete_now`. + * + * \tparam Handler Type of the completion handler + * \tparam Executor1 Type of the asio executor (usually derived from the lower layer) + * \tparam Allocator Type of the allocator to be used + */ +template <class Handler, class Executor1, class Allocator> +class AsyncBase : public boost::asio::coroutine + { + public: + using allocator_type = boost::asio::associated_allocator_t<Handler, Allocator>; + using executor_type = boost::asio::associated_executor_t<Handler, Executor1>; + + allocator_type get_allocator() const noexcept + { + return boost::asio::get_associated_allocator(m_handler); + } + + executor_type get_executor() const noexcept + { + return boost::asio::get_associated_executor(m_handler, m_work_guard_1.get_executor()); + } + + protected: + template <class HandlerT> + AsyncBase(HandlerT&& handler, const Executor1& executor) + : m_handler(std::forward<HandlerT>(handler)) + , m_work_guard_1(executor) + { + } + + /** + * Call the completion handler. + * + * This function should only be called after an intermediate initiating function has been called. + * + * @param args Arguments forwarded to the completion handler function. + */ + template<class... Args> + void complete_now(Args&& ... args) + { + m_work_guard_1.reset(); + m_handler(std::forward<Args>(args)...); + } + + Handler m_handler; + boost::asio::executor_work_guard<Executor1> m_work_guard_1; + }; + +template <class Handler, class Stream, class MutableBufferSequence, class Allocator = std::allocator<void>> +class AsyncReadOperation : public AsyncBase<Handler, typename Stream::executor_type, Allocator> + { + public: + /** + * Construct and invoke an AsyncWriteOperation. + * + * @param handler Handler function to be called upon completion. + * @param stream The stream from which the data will be read + * @param buffers The buffers into which the data will be read. + * @param ec Optional error code; used to report an error to the handler function. + */ + template <class HandlerT> + AsyncReadOperation(HandlerT&& handler, + Stream& stream, + const MutableBufferSequence& buffers, + const boost::system::error_code& ec = {}) + : AsyncBase<Handler, typename Stream::executor_type, Allocator>( + std::forward<HandlerT>(handler), + stream.get_executor()) + , m_stream(stream) + , m_buffers(buffers) + , m_decodedBytes(0) + { + this->operator()(ec, std::size_t(0), false); + } + + AsyncReadOperation(AsyncReadOperation&&) = default; + + void operator()(boost::system::error_code ec, std::size_t bytes_transferred, bool isContinuation = true) + { + reenter(this) + { + if(bytes_transferred > 0 && !ec) + { + // We have received encrypted data from the network, now hand it to TLS::Channel for decryption. + boost::asio::const_buffer read_buffer{m_stream.input_buffer().data(), bytes_transferred}; + try + { + m_stream.native_handle()->received_data( + static_cast<const uint8_t*>(read_buffer.data()), read_buffer.size() + ); + } + catch(const TLS_Exception& e) + { + ec = e.type(); + } + catch(const Botan::Exception& e) + { + ec = e.error_type(); + } + catch(...) + { + ec = Botan::ErrorType::Unknown; + } + } + + if(!m_stream.has_received_data() && !ec && boost::asio::buffer_size(m_buffers) > 0) + { + // The channel did not decrypt a complete record yet, we need more data from the socket. + m_stream.next_layer().async_read_some(m_stream.input_buffer(), std::move(*this)); + return; + } + + if(m_stream.has_received_data() && !ec) + { + // The channel has decrypted a TLS record, now copy it to the output buffers. + m_decodedBytes = m_stream.copy_received_data(m_buffers); + } + + if(!isContinuation) + { + // Make sure the handler is not called without an intermediate initiating function. + // "Reading" into a zero-byte buffer will complete immediately. + m_ec = ec; + yield m_stream.next_layer().async_read_some(boost::asio::mutable_buffer(), std::move(*this)); + ec = m_ec; + } + + this->complete_now(ec, m_decodedBytes); + } + } + + private: + Stream& m_stream; + MutableBufferSequence m_buffers; + std::size_t m_decodedBytes; + boost::system::error_code m_ec; + }; + +template <typename Handler, class Stream, class Allocator = std::allocator<void>> +class AsyncWriteOperation : public AsyncBase<Handler, typename Stream::executor_type, Allocator> + { + public: + /** + * Construct and invoke an AsyncWriteOperation. + * + * @param handler Handler function to be called upon completion. + * @param stream The stream from which the data will be read + * @param plainBytesTransferred Number of bytes to be reported to the user-provided handler function as + * bytes_transferred. This needs to be provided since the amount of plaintext data + * consumed from the input buffer can differ from the amount of encrypted data written + * to the next layer. + * @param ec Optional error code; used to report an error to the handler function. + */ + template <class HandlerT> + AsyncWriteOperation(HandlerT&& handler, + Stream& stream, + std::size_t plainBytesTransferred, + const boost::system::error_code& ec = {}) + : AsyncBase<Handler, typename Stream::executor_type, Allocator>( + std::forward<HandlerT>(handler), + stream.get_executor()) + , m_stream(stream) + , m_plainBytesTransferred(plainBytesTransferred) + { + this->operator()(ec, std::size_t(0), false); + } + + AsyncWriteOperation(AsyncWriteOperation&&) = default; + + void operator()(boost::system::error_code ec, std::size_t bytes_transferred, bool isContinuation = true) + { + reenter(this) + { + // mark the number of encrypted bytes sent to the network as "consumed" + // Note: bytes_transferred will be zero on first call + m_stream.consume_send_buffer(bytes_transferred); + + if(m_stream.has_data_to_send() && !ec) + { + m_stream.next_layer().async_write_some(m_stream.send_buffer(), std::move(*this)); + return; + } + + if(!isContinuation) + { + // Make sure the handler is not called without an intermediate initiating function. + // "Writing" to a zero-byte buffer will complete immediately. + m_ec = ec; + yield m_stream.next_layer().async_write_some(boost::asio::const_buffer(), std::move(*this)); + ec = m_ec; + } + + // The size of the sent TLS record can differ from the size of the payload due to TLS encryption. We need to + // tell the handler how many bytes of the original data we already processed. + this->complete_now(ec, m_plainBytesTransferred); + } + } + + private: + Stream& m_stream; + std::size_t m_plainBytesTransferred; + boost::system::error_code m_ec; + }; + +template <class Handler, class Stream, class Allocator = std::allocator<void>> +class AsyncHandshakeOperation : public AsyncBase<Handler, typename Stream::executor_type, Allocator> + { + public: + /** + * Construct and invoke an AsyncHandshakeOperation. + * + * @param handler Handler function to be called upon completion. + * @param stream The stream from which the data will be read + * @param ec Optional error code; used to report an error to the handler function. + */ + template<class HandlerT> + AsyncHandshakeOperation( + HandlerT&& handler, + Stream& stream, + const boost::system::error_code& ec = {}) + : AsyncBase<Handler, typename Stream::executor_type, Allocator>( + std::forward<HandlerT>(handler), + stream.get_executor()) + , m_stream(stream) + { + this->operator()(ec, std::size_t(0), false); + } + + AsyncHandshakeOperation(AsyncHandshakeOperation&&) = default; + + void operator()(boost::system::error_code ec, std::size_t bytesTransferred, bool isContinuation = true) + { + reenter(this) + { + if(bytesTransferred > 0 && !ec) + { + // Provide encrypted TLS data received from the network to TLS::Channel for decryption + boost::asio::const_buffer read_buffer {m_stream.input_buffer().data(), bytesTransferred}; + try + { + m_stream.native_handle()->received_data( + static_cast<const uint8_t*>(read_buffer.data()), read_buffer.size() + ); + } + catch(const TLS_Exception& e) + { + ec = e.type(); + } + catch(const Botan::Exception& e) + { + ec = e.error_type(); + } + catch(...) + { + ec = Botan::ErrorType::Unknown; + } + } + + if(m_stream.has_data_to_send() && !ec) + { + // Write encrypted TLS data provided by the TLS::Channel on the wire + + // Note: we construct `AsyncWriteOperation` with 0 as its last parameter (`plainBytesTransferred`). This + // operation will eventually call `*this` as its own handler, passing the 0 back to this call operator. + // This is necessary because the check of `bytesTransferred > 0` assumes that `bytesTransferred` bytes + // were just read and are available in input_buffer for further processing. + AsyncWriteOperation< + AsyncHandshakeOperation<typename std::decay<Handler>::type, Stream, Allocator>, + Stream, + Allocator> + op{std::move(*this), m_stream, 0}; + return; + } + + if(!m_stream.native_handle()->is_active() && !ec) + { + // Read more encrypted TLS data from the network + m_stream.next_layer().async_read_some(m_stream.input_buffer(), std::move(*this)); + return; + } + + if(!isContinuation) + { + // Make sure the handler is not called without an intermediate initiating function. + // "Reading" into a zero-byte buffer will complete immediately. + m_ec = ec; + yield m_stream.next_layer().async_read_some(boost::asio::mutable_buffer(), std::move(*this)); + ec = m_ec; + } + + this->complete_now(ec); + } + } + + private: + Stream& m_stream; + boost::system::error_code m_ec; + }; + +} // namespace detail +} // namespace TLS +} // namespace Botan + +#include <boost/asio/unyield.hpp> + +#endif // BOOST_VERSION +#endif // BOTAN_ASIO_ASYNC_OPS_H_ |