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Diffstat (limited to '')
| -rw-r--r-- | src/net/zmq.cpp | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/src/net/zmq.cpp b/src/net/zmq.cpp new file mode 100644 index 000000000..d02a22983 --- /dev/null +++ b/src/net/zmq.cpp @@ -0,0 +1,188 @@ +// Copyright (c) 2019, The Monero Project +// +// All rights reserved. +// +// Redistribution and use in source and binary forms, with or without modification, are +// permitted provided that the following conditions are met: +// +// 1. Redistributions of source code must retain the above copyright notice, this list of +// conditions and the following disclaimer. +// +// 2. Redistributions in binary form must reproduce the above copyright notice, this list +// of conditions and the following disclaimer in the documentation and/or other +// materials provided with the distribution. +// +// 3. Neither the name of the copyright holder nor the names of its contributors may be +// used to endorse or promote products derived from this software without specific +// prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY +// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF +// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL +// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, +// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS +// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, +// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF +// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +#include "net/zmq.h" + +#include <cassert> +#include <cerrno> +#include <limits> +#include <utility> + +namespace net +{ +namespace zmq +{ + const std::error_category& error_category() noexcept + { + struct category final : std::error_category + { + virtual const char* name() const noexcept override final + { + return "error::error_category()"; + } + + virtual std::string message(int value) const override final + { + char const* const msg = zmq_strerror(value); + if (msg) + return msg; + return "zmq_strerror failure"; + } + + virtual std::error_condition default_error_condition(int value) const noexcept override final + { + // maps specific errors to generic `std::errc` cases. + switch (value) + { + case EFSM: + case ETERM: + break; + default: + /* zmq is using cerrno errors. C++ spec indicates that + `std::errc` values must be identical to the cerrno value. + So just map every zmq specific error to the generic errc + equivalent. zmq extensions must be in the switch or they + map to a non-existent errc enum value. */ + return std::errc(value); + } + return std::error_condition{value, *this}; + } + + }; + static const category instance{}; + return instance; + } + + void terminate::call(void* ptr) noexcept + { + assert(ptr != nullptr); // see header + while (zmq_term(ptr)) + { + if (zmq_errno() != EINTR) + break; + } + } + + namespace + { + //! RAII wrapper for `zmq_msg_t`. + class message + { + zmq_msg_t handle_; + + public: + message() noexcept + : handle_() + { + zmq_msg_init(handle()); + } + + message(message&& rhs) = delete; + message(const message& rhs) = delete; + message& operator=(message&& rhs) = delete; + message& operator=(const message& rhs) = delete; + + ~message() noexcept + { + zmq_msg_close(handle()); + } + + zmq_msg_t* handle() noexcept + { + return std::addressof(handle_); + } + + const char* data() noexcept + { + return static_cast<const char*>(zmq_msg_data(handle())); + } + + std::size_t size() noexcept + { + return zmq_msg_size(handle()); + } + }; + + struct do_receive + { + /* ZMQ documentation states that message parts are atomic - either + all are received or none are. Looking through ZMQ code and + Github discussions indicates that after part 1 is returned, + `EAGAIN` cannot be returned to meet these guarantees. Unit tests + verify (for the `inproc://` case) that this is the behavior. + Therefore, read errors after the first part are treated as a + failure for the entire message (probably `ETERM`). */ + int operator()(std::string& payload, void* const socket, const int flags) const + { + static constexpr const int max_out = std::numeric_limits<int>::max(); + const std::string::size_type initial = payload.size(); + message part{}; + for (;;) + { + int last = 0; + if ((last = zmq_msg_recv(part.handle(), socket, flags)) < 0) + return last; + + payload.append(part.data(), part.size()); + if (!zmq_msg_more(part.handle())) + break; + } + const std::string::size_type added = payload.size() - initial; + return unsigned(max_out) < added ? max_out : int(added); + } + }; + + template<typename F, typename... T> + expect<void> retry_op(F op, T&&... args) noexcept(noexcept(op(args...))) + { + for (;;) + { + if (0 <= op(args...)) + return success(); + + const int error = zmq_errno(); + if (error != EINTR) + return make_error_code(error); + } + } + } // anonymous + + expect<std::string> receive(void* const socket, const int flags) + { + std::string payload{}; + MONERO_CHECK(retry_op(do_receive{}, payload, socket, flags)); + return {std::move(payload)}; + } + + expect<void> send(const epee::span<const std::uint8_t> payload, void* const socket, const int flags) noexcept + { + return retry_op(zmq_send, socket, payload.data(), payload.size(), flags); + } +} // zmq +} // net + |