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Diffstat (limited to 'src/lib/asiolink/tcp_socket.h')
| -rw-r--r-- | src/lib/asiolink/tcp_socket.h | 503 |
1 files changed, 503 insertions, 0 deletions
diff --git a/src/lib/asiolink/tcp_socket.h b/src/lib/asiolink/tcp_socket.h new file mode 100644 index 0000000..c8ea454 --- /dev/null +++ b/src/lib/asiolink/tcp_socket.h @@ -0,0 +1,503 @@ +// Copyright (C) 2011-2022 Internet Systems Consortium, Inc. ("ISC") +// +// This Source Code Form is subject to the terms of the Mozilla Public +// License, v. 2.0. If a copy of the MPL was not distributed with this +// file, You can obtain one at http://mozilla.org/MPL/2.0/. + +#ifndef TCP_SOCKET_H +#define TCP_SOCKET_H 1 + +#ifndef BOOST_ASIO_HPP +#error "asio.hpp must be included before including this, see asiolink.h as to why" +#endif + +#include <netinet/in.h> +#include <sys/socket.h> +#include <unistd.h> // for some IPC/network system calls + +#include <algorithm> +#include <cstddef> + +#include <boost/numeric/conversion/cast.hpp> + +#include <util/buffer.h> +#include <util/io_utilities.h> + +#include <asiolink/io_asio_socket.h> +#include <asiolink/io_endpoint.h> +#include <asiolink/io_service.h> +#include <asiolink/tcp_endpoint.h> + +#include <exceptions/isc_assert.h> + +namespace isc { +namespace asiolink { + +/// \brief Buffer Too Large +/// +/// Thrown on an attempt to send a buffer > 64k +class BufferTooLarge : public IOError { +public: + BufferTooLarge(const char* file, size_t line, const char* what) : + IOError(file, line, what) {} +}; + +/// \brief The \c TCPSocket class is a concrete derived class of \c IOAsioSocket +/// that represents a TCP socket. +/// +/// \param C Callback type +template <typename C> +class TCPSocket : public IOAsioSocket<C> { +private: + /// \brief Class is non-copyable + TCPSocket(const TCPSocket&); + TCPSocket& operator=(const TCPSocket&); + +public: + + /// \brief Constructor from an ASIO TCP socket. + /// + /// \param socket The ASIO representation of the TCP socket. It is assumed + /// that the caller will open and close the socket, so these + /// operations are a no-op for that socket. + TCPSocket(boost::asio::ip::tcp::socket& socket); + + /// \brief Constructor + /// + /// Used when the TCPSocket is being asked to manage its own internal + /// socket. In this case, the open() and close() methods are used. + /// + /// \param service I/O Service object used to manage the socket. + TCPSocket(IOService& service); + + /// \brief Destructor + virtual ~TCPSocket(); + + /// \brief Return file descriptor of underlying socket + virtual int getNative() const { +#if BOOST_VERSION < 106600 + return (socket_.native()); +#else + return (socket_.native_handle()); +#endif + } + + /// \brief Return protocol of socket + virtual int getProtocol() const { + return (IPPROTO_TCP); + } + + /// \brief Is "open()" synchronous? + /// + /// Indicates that the opening of a TCP socket is asynchronous. + virtual bool isOpenSynchronous() const { + return (false); + } + + /// \brief Checks if the connection is usable. + /// + /// The connection is usable if the socket is open and the peer has not + /// closed its connection. + /// + /// \return true if the connection is usable. + bool isUsable() const { + // If the socket is open it doesn't mean that it is still usable. The connection + // could have been closed on the other end. We have to check if we can still + // use this socket. + if (socket_.is_open()) { + // Remember the current non blocking setting. + const bool non_blocking_orig = socket_.non_blocking(); + // Set the socket to non blocking mode. We're going to test if the socket + // returns would_block status on the attempt to read from it. + socket_.non_blocking(true); + + boost::system::error_code ec; + char data[2]; + + // Use receive with message peek flag to avoid removing the data awaiting + // to be read. + socket_.receive(boost::asio::buffer(data, sizeof(data)), + boost::asio::socket_base::message_peek, + ec); + + // Revert the original non_blocking flag on the socket. + socket_.non_blocking(non_blocking_orig); + + // If the connection is alive we'd typically get would_block status code. + // If there are any data that haven't been read we may also get success + // status. We're guessing that try_again may also be returned by some + // implementations in some situations. Any other error code indicates a + // problem with the connection so we assume that the connection has been + // closed. + return (!ec || (ec.value() == boost::asio::error::try_again) || + (ec.value() == boost::asio::error::would_block)); + } + + return (false); + } + + /// \brief Open Socket + /// + /// Opens the TCP socket. This is an asynchronous operation, completion of + /// which will be signalled via a call to the callback function. + /// + /// \param endpoint Endpoint to which the socket will connect. + /// \param callback Callback object. + virtual void open(const IOEndpoint* endpoint, C& callback); + + /// \brief Send Asynchronously + /// + /// Calls the underlying socket's async_send() method to send a packet of + /// data asynchronously to the remote endpoint. The callback will be called + /// on completion. + /// + /// \param data Data to send + /// \param length Length of data to send + /// \param endpoint Target of the send. (Unused for a TCP socket because + /// that was determined when the connection was opened.) + /// \param callback Callback object. + /// \throw BufferTooLarge on attempt to send a buffer larger than 64kB. + virtual void asyncSend(const void* data, size_t length, + const IOEndpoint* endpoint, C& callback); + + /// \brief Send Asynchronously without count. + /// + /// This variant of the method sends data over the TCP socket without + /// preceding the data with a data count. Eventually, we should migrate + /// the virtual method to not insert the count but there are existing + /// classes using the count. Once this migration is done, the existing + /// virtual method should be replaced by this method. + /// + /// \param data Data to send + /// \param length Length of data to send + /// \param callback Callback object. + /// \throw BufferTooLarge on attempt to send a buffer larger than 64kB. + void asyncSend(const void* data, size_t length, C& callback); + + /// \brief Receive Asynchronously + /// + /// Calls the underlying socket's async_receive() method to read a packet + /// of data from a remote endpoint. Arrival of the data is signalled via a + /// call to the callback function. + /// + /// \param data Buffer to receive incoming message + /// \param length Length of the data buffer + /// \param offset Offset into buffer where data is to be put + /// \param endpoint Source of the communication + /// \param callback Callback object + virtual void asyncReceive(void* data, size_t length, size_t offset, + IOEndpoint* endpoint, C& callback); + + /// \brief Process received data packet + /// + /// See the description of IOAsioSocket::receiveComplete for a complete + /// description of this method. + /// + /// \param staging Pointer to the start of the staging buffer. + /// \param length Amount of data in the staging buffer. + /// \param cumulative Amount of data received before the staging buffer is + /// processed. + /// \param offset Unused. + /// \param expected unused. + /// \param outbuff Output buffer. Data in the staging buffer is be copied + /// to this output buffer in the call. + /// + /// \return Always true + virtual bool processReceivedData(const void* staging, size_t length, + size_t& cumulative, size_t& offset, + size_t& expected, + isc::util::OutputBufferPtr& outbuff); + + /// \brief Cancel I/O On Socket + virtual void cancel(); + + /// \brief Close socket + virtual void close(); + + /// \brief Returns reference to the underlying ASIO socket. + /// + /// \return Reference to underlying ASIO socket. + virtual boost::asio::ip::tcp::socket& getASIOSocket() const { + return (socket_); + } + +private: + /// Two variables to hold the socket - a socket and a pointer to it. This + /// handles the case where a socket is passed to the TCPSocket on + /// construction, or where it is asked to manage its own socket. + + /// Pointer to own socket + std::unique_ptr<boost::asio::ip::tcp::socket> socket_ptr_; + + /// Socket + boost::asio::ip::tcp::socket& socket_; + + /// @todo Remove temporary buffer + /// The current implementation copies the buffer passed to asyncSend() into + /// a temporary buffer and precedes it with a two-byte count field. As + /// ASIO should really be just about sending and receiving data, the TCP + /// code should not do this. If the protocol using this requires a two-byte + /// count, it should add it before calling this code. (This may be best + /// achieved by altering isc::dns::buffer to have pairs of methods: + /// getLength()/getTCPLength(), getData()/getTCPData(), with the getTCPXxx() + /// methods taking into account a two-byte count field.) + /// + /// The option of sending the data in two operations, the count followed by + /// the data was discounted as that would lead to two callbacks which would + /// cause problems with the stackless coroutine code. + + /// Send buffer + isc::util::OutputBufferPtr send_buffer_; +}; + +// Constructor - caller manages socket + +template <typename C> +TCPSocket<C>::TCPSocket(boost::asio::ip::tcp::socket& socket) : + socket_ptr_(), socket_(socket), send_buffer_() +{ +} + +// Constructor - create socket on the fly + +template <typename C> +TCPSocket<C>::TCPSocket(IOService& service) : + socket_ptr_(new boost::asio::ip::tcp::socket(service.get_io_service())), + socket_(*socket_ptr_) +{ +} + +// Destructor. + +template <typename C> +TCPSocket<C>::~TCPSocket() +{ +} + +// Open the socket. + +template <typename C> void +TCPSocket<C>::open(const IOEndpoint* endpoint, C& callback) { + // If socket is open on this end but has been closed by the peer, + // we need to reconnect. + if (socket_.is_open() && !isUsable()) { + close(); + } + // Ignore opens on already-open socket. Don't throw a failure because + // of uncertainties as to what precedes when using asynchronous I/O. + // Also allows us a treat a passed-in socket as a self-managed socket. + if (!socket_.is_open()) { + if (endpoint->getFamily() == AF_INET) { + socket_.open(boost::asio::ip::tcp::v4()); + } else { + socket_.open(boost::asio::ip::tcp::v6()); + } + + // Set options on the socket: + + // Reuse address - allow the socket to bind to a port even if the port + // is in the TIMED_WAIT state. + socket_.set_option(boost::asio::socket_base::reuse_address(true)); + } + + // Upconvert to a TCPEndpoint. We need to do this because although + // IOEndpoint is the base class of UDPEndpoint and TCPEndpoint, it does not + // contain a method for getting at the underlying endpoint type - that is in + /// the derived class and the two classes differ on return type. + isc_throw_assert(endpoint->getProtocol() == IPPROTO_TCP); + const TCPEndpoint* tcp_endpoint = + static_cast<const TCPEndpoint*>(endpoint); + + // Connect to the remote endpoint. On success, the handler will be + // called (with one argument - the length argument will default to + // zero). + socket_.async_connect(tcp_endpoint->getASIOEndpoint(), callback); +} + +// Send a message. Should never do this if the socket is not open, so throw +// an exception if this is the case. + +template <typename C> void +TCPSocket<C>::asyncSend(const void* data, size_t length, C& callback) +{ + if (socket_.is_open()) { + + try { + send_buffer_.reset(new isc::util::OutputBuffer(length)); + send_buffer_->writeData(data, length); + + // Send the data. + socket_.async_send(boost::asio::buffer(send_buffer_->getData(), + send_buffer_->getLength()), + callback); + } catch (const boost::numeric::bad_numeric_cast&) { + isc_throw(BufferTooLarge, + "attempt to send buffer larger than 64kB"); + } + + } else { + isc_throw(SocketNotOpen, + "attempt to send on a TCP socket that is not open"); + } +} + +template <typename C> void +TCPSocket<C>::asyncSend(const void* data, size_t length, + const IOEndpoint*, C& callback) +{ + if (socket_.is_open()) { + + /// Need to copy the data into a temporary buffer and precede it with + /// a two-byte count field. + /// @todo arrange for the buffer passed to be preceded by the count + try { + /// Ensure it fits into 16 bits + uint16_t count = boost::numeric_cast<uint16_t>(length); + + /// Copy data into a buffer preceded by the count field. + send_buffer_.reset(new isc::util::OutputBuffer(length + 2)); + send_buffer_->writeUint16(count); + send_buffer_->writeData(data, length); + + /// ... and send it + socket_.async_send(boost::asio::buffer(send_buffer_->getData(), + send_buffer_->getLength()), callback); + } catch (const boost::numeric::bad_numeric_cast&) { + isc_throw(BufferTooLarge, + "attempt to send buffer larger than 64kB"); + } + + } else { + isc_throw(SocketNotOpen, + "attempt to send on a TCP socket that is not open"); + } +} + +// Receive a message. Note that the "offset" argument is used as an index +// into the buffer in order to decide where to put the data. It is up to the +// caller to initialize the data to zero +template <typename C> void +TCPSocket<C>::asyncReceive(void* data, size_t length, size_t offset, + IOEndpoint* endpoint, C& callback) +{ + if (socket_.is_open()) { + // Upconvert to a TCPEndpoint. We need to do this because although + // IOEndpoint is the base class of UDPEndpoint and TCPEndpoint, it + // does not contain a method for getting at the underlying endpoint + // type - that is in the derived class and the two classes differ on + // return type. + isc_throw_assert(endpoint->getProtocol() == IPPROTO_TCP); + TCPEndpoint* tcp_endpoint = static_cast<TCPEndpoint*>(endpoint); + + // Write the endpoint details from the communications link. Ideally + // we should make IOEndpoint assignable, but this runs in to all sorts + // of problems concerning the management of the underlying Boost + // endpoint (e.g. if it is not self-managed, is the copied one + // self-managed?) The most pragmatic solution is to let Boost take care + // of everything and copy details of the underlying endpoint. + tcp_endpoint->getASIOEndpoint() = socket_.remote_endpoint(); + + // Ensure we can write into the buffer and if so, set the pointer to + // where the data will be written. + if (offset >= length) { + isc_throw(BufferOverflow, "attempt to read into area beyond end of " + "TCP receive buffer"); + } + void* buffer_start = static_cast<void*>(static_cast<uint8_t*>(data) + offset); + + // ... and kick off the read. + socket_.async_receive(boost::asio::buffer(buffer_start, length - offset), callback); + + } else { + isc_throw(SocketNotOpen, + "attempt to receive from a TCP socket that is not open"); + } +} + +// Is the receive complete? + +template <typename C> bool +TCPSocket<C>::processReceivedData(const void* staging, size_t length, + size_t& cumulative, size_t& offset, + size_t& expected, + isc::util::OutputBufferPtr& outbuff) +{ + // Point to the data in the staging buffer and note how much there is. + const uint8_t* data = static_cast<const uint8_t*>(staging); + size_t data_length = length; + + // Is the number is "expected" valid? It won't be unless we have received + // at least two bytes of data in total for this set of receives. + if (cumulative < 2) { + + // "expected" is not valid. Did this read give us enough data to + // work it out? + cumulative += length; + if (cumulative < 2) { + + // Nope, still not valid. This must have been the first packet and + // was only one byte long. Tell the fetch code to read the next + // packet into the staging buffer beyond the data that is already + // there so that the next time we are called we have a complete + // TCP count. + offset = cumulative; + return (false); + } + + // Have enough data to interpret the packet count, so do so now. + expected = isc::util::readUint16(data, cumulative); + + // We have two bytes less of data to process. Point to the start of the + // data and adjust the packet size. Note that at this point, + // "cumulative" is the true amount of data in the staging buffer, not + // "length". + data += 2; + data_length = cumulative - 2; + } else { + + // Update total amount of data received. + cumulative += length; + } + + // Regardless of anything else, the next read goes into the start of the + // staging buffer. + offset = 0; + + // Work out how much data we still have to put in the output buffer. (This + // could be zero if we have just interpreted the TCP count and that was + // set to zero.) + if (expected >= outbuff->getLength()) { + + // Still need data in the output packet. Copy what we can from the + // staging buffer to the output buffer. + size_t copy_amount = std::min(expected - outbuff->getLength(), data_length); + outbuff->writeData(data, copy_amount); + } + + // We can now say if we have all the data. + return (expected == outbuff->getLength()); +} + +// Cancel I/O on the socket. No-op if the socket is not open. + +template <typename C> void +TCPSocket<C>::cancel() { + if (socket_.is_open()) { + socket_.cancel(); + } +} + +// Close the socket down. Can only do this if the socket is open and we are +// managing it ourself. + +template <typename C> void +TCPSocket<C>::close() { + if (socket_.is_open() && socket_ptr_) { + socket_.close(); + } +} + +} // namespace asiolink +} // namespace isc + +#endif // TCP_SOCKET_H |