util: Add DNS resolver utility class
refs: #1918
Change-Id: Ia393498febfb8e3a7473d5390ba6a378be71f412
diff --git a/src/util/dns.cpp b/src/util/dns.cpp
new file mode 100644
index 0000000..8df097f
--- /dev/null
+++ b/src/util/dns.cpp
@@ -0,0 +1,167 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file. If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#include "dns.hpp"
+
+#include "scheduler.hpp"
+
+namespace ndn {
+namespace dns {
+
+typedef boost::asio::ip::udp::endpoint EndPoint;
+typedef boost::asio::ip::basic_resolver<boost::asio::ip::udp> BoostResolver;
+
+class Resolver : noncopyable
+{
+public:
+ Resolver(const SuccessCallback& onSuccess,
+ const ErrorCallback& onError,
+ const ndn::dns::AddressSelector& addressSelector,
+ boost::asio::io_service& ioService)
+ : m_resolver(ioService)
+ , m_addressSelector(addressSelector)
+ , m_onSuccess(onSuccess)
+ , m_onError(onError)
+ , m_scheduler(ioService)
+ {
+ }
+
+ void
+ asyncResolve(const std::string& host,
+ const time::nanoseconds& timeout,
+ const shared_ptr<Resolver>& self)
+ {
+ BoostResolver::query query(host, NULL_PORT
+
+#if not defined(__FreeBSD__)
+ , BoostResolver::query::all_matching
+#endif
+ );
+
+ m_resolver.async_resolve(query, bind(&Resolver::onResolveSuccess, this, _1, _2, self));
+
+ m_resolveTimeout = m_scheduler.scheduleEvent(timeout,
+ bind(&Resolver::onResolveError, this,
+ "Timeout", self));
+ }
+
+ BoostResolver::iterator
+ syncResolve(BoostResolver::query query)
+ {
+ return m_resolver.resolve(query);
+ }
+
+ void
+ onResolveSuccess(const boost::system::error_code& error,
+ BoostResolver::iterator remoteEndpoint,
+ const shared_ptr<Resolver>& self)
+ {
+ m_scheduler.cancelEvent(m_resolveTimeout);
+
+ if (error)
+ {
+ if (error == boost::system::errc::operation_canceled)
+ {
+ return;
+ }
+
+ return m_onError("Remote endpoint hostname or port cannot be resolved: " +
+ error.category().message(error.value()));
+ }
+
+ BoostResolver::iterator end;
+ for (; remoteEndpoint != end; ++remoteEndpoint)
+ {
+ IpAddress address(EndPoint(*remoteEndpoint).address());
+
+ if (m_addressSelector(address))
+ {
+ return m_onSuccess(address);
+ }
+ }
+
+ m_onError("No endpoint matching the specified address selector found");
+ }
+
+ void
+ onResolveError(const std::string& errorInfo, const shared_ptr<Resolver>& self)
+ {
+ m_resolver.cancel();
+ m_onError(errorInfo);
+ }
+
+public:
+ static const std::string NULL_PORT;
+
+private:
+ BoostResolver m_resolver;
+ EventId m_resolveTimeout;
+
+ ndn::dns::AddressSelector m_addressSelector;
+ SuccessCallback m_onSuccess;
+ ErrorCallback m_onError;
+
+ Scheduler m_scheduler;
+};
+
+const std::string Resolver::NULL_PORT = "";
+
+void
+asyncResolve(const std::string& host,
+ const SuccessCallback& onSuccess,
+ const ErrorCallback& onError,
+ boost::asio::io_service& ioService,
+ const ndn::dns::AddressSelector& addressSelector,
+ const time::nanoseconds& timeout)
+{
+ shared_ptr<Resolver> resolver = make_shared<Resolver>(onSuccess, onError,
+ addressSelector, ndn::ref(ioService));
+ resolver->asyncResolve(host, timeout, resolver);
+ // resolver will be destroyed when async operation finishes or global IO service stops
+}
+
+IpAddress
+syncResolve(const std::string& host, boost::asio::io_service& ioService,
+ const ndn::dns::AddressSelector& addressSelector)
+{
+ Resolver resolver(SuccessCallback(), ErrorCallback(), addressSelector, ioService);
+
+ BoostResolver::query query(host, Resolver::NULL_PORT
+#if not defined(__FreeBSD__)
+ , BoostResolver::query::all_matching
+#endif
+ );
+
+ BoostResolver::iterator remoteEndpoint = resolver.syncResolve(query);
+
+ BoostResolver::iterator end;
+ for (; remoteEndpoint != end; ++remoteEndpoint)
+ {
+ if (addressSelector(EndPoint(*remoteEndpoint).address()))
+ {
+ return EndPoint(*remoteEndpoint).address();
+ }
+ }
+ throw Error("No endpoint matching the specified address selector found");
+}
+
+} // namespace dns
+} // namespace ndn