net: move network-related files to src/net

Some namespaces are changed:

* ndn::util::FaceUri is now ndn::FaceUri
* ndn::util::ethernet is now ndn::ethernet
* ndn::util::NetworkMonitor and related classes are now in ndn::net

refs #3940

Change-Id: Ia4754caef9726efc73f5a303cec46fc95c744d70
diff --git a/src/net/dns.cpp b/src/net/dns.cpp
new file mode 100644
index 0000000..0043ec9
--- /dev/null
+++ b/src/net/dns.cpp
@@ -0,0 +1,160 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2017 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 "../util/scheduler.hpp"
+
+#include <boost/asio/io_service.hpp>
+#include <boost/asio/ip/udp.hpp>
+
+namespace ndn {
+namespace dns {
+
+class Resolver : noncopyable
+{
+public:
+  typedef boost::asio::ip::udp protocol;
+  typedef protocol::resolver::iterator iterator;
+  typedef protocol::resolver::query query;
+
+public:
+  Resolver(boost::asio::io_service& ioService,
+           const AddressSelector& addressSelector)
+    : m_resolver(ioService)
+    , m_addressSelector(addressSelector)
+    , m_scheduler(ioService)
+  {
+    BOOST_ASSERT(m_addressSelector != nullptr);
+  }
+
+  void
+  asyncResolve(const query& q,
+               const SuccessCallback& onSuccess,
+               const ErrorCallback& onError,
+               time::nanoseconds timeout,
+               const shared_ptr<Resolver>& self)
+  {
+    m_onSuccess = onSuccess;
+    m_onError = onError;
+
+    m_resolver.async_resolve(q, bind(&Resolver::onResolveResult, this, _1, _2, self));
+
+    m_resolveTimeout = m_scheduler.scheduleEvent(timeout, bind(&Resolver::onResolveTimeout, this, self));
+  }
+
+  iterator
+  syncResolve(const query& q)
+  {
+    return selectAddress(m_resolver.resolve(q));
+  }
+
+private:
+  void
+  onResolveResult(const boost::system::error_code& error,
+                  iterator it, const shared_ptr<Resolver>& self)
+  {
+    m_scheduler.cancelEvent(m_resolveTimeout);
+    // ensure the Resolver isn't destructed while callbacks are still pending, see #2653
+    m_resolver.get_io_service().post(bind([] (const shared_ptr<Resolver>&) {}, self));
+
+    if (error) {
+      if (error == boost::asio::error::operation_aborted)
+        return;
+
+      if (m_onError)
+        m_onError("Hostname cannot be resolved: " + error.message());
+
+      return;
+    }
+
+    it = selectAddress(it);
+
+    if (it != iterator() && m_onSuccess) {
+      m_onSuccess(it->endpoint().address());
+    }
+    else if (m_onError) {
+      m_onError("No endpoints match the specified address selector");
+    }
+  }
+
+  void
+  onResolveTimeout(const shared_ptr<Resolver>& self)
+  {
+    m_resolver.cancel();
+    // ensure the Resolver isn't destructed while callbacks are still pending, see #2653
+    m_resolver.get_io_service().post(bind([] (const shared_ptr<Resolver>&) {}, self));
+
+    if (m_onError)
+      m_onError("Hostname resolution timed out");
+  }
+
+  iterator
+  selectAddress(iterator it) const
+  {
+    while (it != iterator() &&
+           !m_addressSelector(it->endpoint().address())) {
+      ++it;
+    }
+
+    return it;
+  }
+
+private:
+  protocol::resolver m_resolver;
+
+  AddressSelector m_addressSelector;
+  SuccessCallback m_onSuccess;
+  ErrorCallback m_onError;
+
+  util::scheduler::Scheduler m_scheduler;
+  util::scheduler::EventId m_resolveTimeout;
+};
+
+void
+asyncResolve(const std::string& host,
+             const SuccessCallback& onSuccess,
+             const ErrorCallback& onError,
+             boost::asio::io_service& ioService,
+             const AddressSelector& addressSelector,
+             time::nanoseconds timeout)
+{
+  auto resolver = make_shared<Resolver>(ref(ioService), addressSelector);
+  resolver->asyncResolve(Resolver::query(host, ""), onSuccess, onError, timeout, resolver);
+  // resolver will be destroyed when async operation finishes or ioService stops
+}
+
+IpAddress
+syncResolve(const std::string& host,
+            boost::asio::io_service& ioService,
+            const AddressSelector& addressSelector)
+{
+  Resolver resolver(ioService, addressSelector);
+  auto it = resolver.syncResolve(Resolver::query(host, ""));
+
+  if (it == Resolver::iterator()) {
+    BOOST_THROW_EXCEPTION(Error("No endpoints match the specified address selector"));
+  }
+
+  return it->endpoint().address();
+}
+
+} // namespace dns
+} // namespace ndn