Initial NTP protocol functionality

wxdata/source/scwx/network/ntp_client.cpp

@@ -0,0 +1,143 @@
+#include <scwx/network/ntp_client.hpp>
+#include <scwx/types/ntp_types.hpp>
+#include <scwx/util/logger.hpp>
+#include <scwx/util/threads.hpp>
+
+#include <boost/asio/ip/udp.hpp>
+#include <boost/asio/thread_pool.hpp>
+#include <boost/asio/use_future.hpp>
+
+namespace scwx::network
+{
+
+static const std::string logPrefix_ = "scwx::network::ntp_client";
+static const auto        logger_    = scwx::util::Logger::Create(logPrefix_);
+
+static constexpr std::size_t kReceiveBufferSize_ {48u};
+
+class NtpClient::Impl
+{
+public:
+   explicit Impl();
+   ~Impl();
+   Impl(const Impl&)             = delete;
+   Impl& operator=(const Impl&)  = delete;
+   Impl(const Impl&&)            = delete;
+   Impl& operator=(const Impl&&) = delete;
+
+   void Open(std::string_view host, std::string_view service);
+   void Poll();
+   void ReceivePacket(std::size_t length);
+
+   boost::asio::thread_pool threadPool_ {2u};
+
+   types::ntp::NtpPacket transmitPacket_ {};
+
+   boost::asio::ip::udp::socket                  socket_;
+   std::optional<boost::asio::ip::udp::endpoint> serverEndpoint_ {};
+   std::array<std::uint8_t, kReceiveBufferSize_> receiveBuffer_ {};
+
+   std::vector<std::string> serverList_ {
+      "time.nist.gov", "ntp.pool.org", "time.windows.com"};
+};
+
+NtpClient::NtpClient() : p(std::make_unique<Impl>()) {}
+NtpClient::~NtpClient() = default;
+
+NtpClient::NtpClient(NtpClient&&) noexcept            = default;
+NtpClient& NtpClient::operator=(NtpClient&&) noexcept = default;
+
+void NtpClient::Open(std::string_view host, std::string_view service)
+{
+   p->Open(host, service);
+}
+
+void NtpClient::Poll()
+{
+   p->Poll();
+}
+
+NtpClient::Impl::Impl() : socket_ {threadPool_}
+{
+   transmitPacket_.fields.vn   = 3; // Version
+   transmitPacket_.fields.mode = 3; // Client (3)
+}
+
+NtpClient::Impl::~Impl()
+{
+   threadPool_.join();
+}
+
+void NtpClient::Impl::Open(std::string_view host, std::string_view service)
+{
+   boost::asio::ip::udp::resolver resolver(threadPool_);
+   boost::system::error_code      ec;
+
+   auto results = resolver.resolve(host, service, ec);
+   if (ec.value() == boost::system::errc::success && !results.empty())
+   {
+      logger_->info("Using NTP server: {}", host);
+      serverEndpoint_ = *results.begin();
+      socket_.open(serverEndpoint_->protocol());
+   }
+   else
+   {
+      serverEndpoint_ = std::nullopt;
+      logger_->warn("Could not resolve host {}: {}", host, ec.message());
+   }
+}
+
+void NtpClient::Impl::Poll()
+{
+   using namespace std::chrono_literals;
+
+   static constexpr auto kTimeout_ = 15s;
+
+   try
+   {
+      std::size_t transmitPacketSize = sizeof(transmitPacket_);
+      // Send NTP request
+      socket_.send_to(boost::asio::buffer(&transmitPacket_, transmitPacketSize),
+         *serverEndpoint_);
+
+      // Receive NTP response
+      auto future =
+         socket_.async_receive_from(boost::asio::buffer(receiveBuffer_),
+                                    *serverEndpoint_,
+                                    boost::asio::use_future);
+      std::size_t bytesReceived = 0;
+
+      switch (future.wait_for(kTimeout_))
+      {
+      case std::future_status::ready:
+         bytesReceived = future.get();
+         ReceivePacket(bytesReceived);
+         break;
+
+      case std::future_status::timeout:
+      case std::future_status::deferred:
+         logger_->warn("Timeout waiting for NTP response");
+         socket_.cancel();
+         break;
+      }
+   }
+   catch (const std::exception& ex)
+   {
+      logger_->error("Error polling: {}", ex.what());
+   }
+}
+
+void NtpClient::Impl::ReceivePacket(std::size_t length)
+{
+   if (length >= sizeof(types::ntp::NtpPacket))
+   {
+      auto packet = types::ntp::NtpPacket::Parse(receiveBuffer_);
+      (void) packet;
+   }
+   else
+   {
+      logger_->warn("Received too few bytes: {}", length);
+   }
+}
+
+} // namespace scwx::network