ndn-cxx/net/detail/network-monitor-impl-osx.cpp - ndn-cxx - Gitiles

 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
  * Copyright (c) 2013-2018 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.
  *
  *
  * Parts of this implementation is based on daemondo command of MacPorts
  * (https://www.macports.org/):
  *
  *    Copyright (c) 2005-2007 James Berry <jberry@macports.org>
  *   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 MacPorts Project 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 OWNER 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 "ndn-cxx/net/detail/network-monitor-impl-osx.hpp"
 #include "ndn-cxx/net/network-address.hpp"
 #include "ndn-cxx/name.hpp"
 #include "ndn-cxx/util/cf-string-osx.hpp"
 #include "ndn-cxx/util/logger.hpp"

 #include <ifaddrs.h>      // for getifaddrs()
 #include <net/if.h>       // for if_nametoindex()
 #include <net/if_dl.h>    // for struct sockaddr_dl
 #include <net/if_types.h> // for IFT_* constants
 #include <netinet/in.h>   // for struct sockaddr_in{,6}

 #include <boost/asio/io_service.hpp>
 #include <boost/asio/ip/address.hpp>
 #include <boost/asio/ip/udp.hpp>

 NDN_LOG_INIT(ndn.NetworkMonitor);

 namespace ndn {
 namespace net {

 using util::CFReleaser;

 class IfAddrs : noncopyable
 {
 public:
   IfAddrs()
   {
     if (::getifaddrs(&m_ifaList) < 0) {
       BOOST_THROW_EXCEPTION(NetworkMonitorImplOsx::Error("getifaddrs() failed: "s + strerror(errno)));
     }
   }

   ~IfAddrs()
   {
     if (m_ifaList != nullptr) {
       ::freeifaddrs(m_ifaList);
     }
   }

   ifaddrs*
   get() const noexcept
   {
     return m_ifaList;
   }

 private:
   ifaddrs* m_ifaList = nullptr;
 };

 NetworkMonitorImplOsx::NetworkMonitorImplOsx(boost::asio::io_service& io)
   : m_scheduler(io)
   , m_cfLoopEvent(m_scheduler)
   , m_context{0, this, nullptr, nullptr, nullptr}
   , m_scStore(SCDynamicStoreCreate(nullptr, CFSTR("net.named-data.ndn-cxx.NetworkMonitor"),
                                    &NetworkMonitorImplOsx::onConfigChanged, &m_context))
   , m_loopSource(SCDynamicStoreCreateRunLoopSource(nullptr, m_scStore.get(), 0))
   , m_ioctlSocket(io, boost::asio::ip::udp::v4())
 {
   scheduleCfLoop();

   // Notifications from Darwin Notify Center:
   //
   // com.apple.system.config.network_change
   //
   CFNotificationCenterAddObserver(CFNotificationCenterGetDarwinNotifyCenter(),
                                   static_cast<void*>(this),
                                   &NetworkMonitorImplOsx::afterNotificationCenterEvent,
                                   CFSTR("com.apple.system.config.network_change"),
                                   nullptr, // object to observe
                                   CFNotificationSuspensionBehaviorDeliverImmediately);

   CFRunLoopAddSource(CFRunLoopGetCurrent(), m_loopSource.get(), kCFRunLoopDefaultMode);

   // Notifications from SystemConfiguration:
   //
   // State:/Network/Interface/.*/Link
   // State:/Network/Interface/.*/IPv4
   // State:/Network/Interface/.*/IPv6
   // State:/Network/Interface/.*/AirPort (not used)
   //
   // https://developer.apple.com/library/content/documentation/Networking/Conceptual/SystemConfigFrameworks/SC_UnderstandSchema/SC_UnderstandSchema.html
   //
   auto patterns = CFArrayCreateMutable(nullptr, 0, &kCFTypeArrayCallBacks);
   CFArrayAppendValue(patterns, CFSTR("State:/Network/Interface/.*/Link"));
   CFArrayAppendValue(patterns, CFSTR("State:/Network/Interface/.*/IPv4"));
   CFArrayAppendValue(patterns, CFSTR("State:/Network/Interface/.*/IPv6"));

   if (!SCDynamicStoreSetNotificationKeys(m_scStore.get(), nullptr, patterns)) {
     BOOST_THROW_EXCEPTION(Error("SCDynamicStoreSetNotificationKeys failed"));
   }

   io.post([this] { enumerateInterfaces(); });
 }

 NetworkMonitorImplOsx::~NetworkMonitorImplOsx()
 {
   CFRunLoopRemoveSource(CFRunLoopGetCurrent(), m_loopSource.get(), kCFRunLoopDefaultMode);

   CFNotificationCenterRemoveEveryObserver(CFNotificationCenterGetDarwinNotifyCenter(),
                                           static_cast<void*>(this));
 }

 shared_ptr<const NetworkInterface>
 NetworkMonitorImplOsx::getNetworkInterface(const std::string& ifname) const
 {
   auto it = m_interfaces.find(ifname);
   return it == m_interfaces.end() ? nullptr : it->second;
 }

 std::vector<shared_ptr<const NetworkInterface>>
 NetworkMonitorImplOsx::listNetworkInterfaces() const
 {
   std::vector<shared_ptr<const NetworkInterface>> v;
   v.reserve(m_interfaces.size());

   for (const auto& e : m_interfaces) {
     v.push_back(e.second);
   }
   return v;
 }

 void
 NetworkMonitorImplOsx::afterNotificationCenterEvent(CFNotificationCenterRef center,
                                                     void* observer,
                                                     CFStringRef name,
                                                     const void* object,
                                                     CFDictionaryRef userInfo)
 {
   static_cast<NetworkMonitorImplOsx*>(observer)->emitSignal(onNetworkStateChanged);
 }

 void
 NetworkMonitorImplOsx::scheduleCfLoop()
 {
   // poll each second for new events
   m_cfLoopEvent = m_scheduler.scheduleEvent(1_s, [this] {
     // this should dispatch ready events and exit
     CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0, true);
     scheduleCfLoop();
   });
 }

 void
 NetworkMonitorImplOsx::enumerateInterfaces()
 {
   IfAddrs ifaList;
   for (const auto& ifName : getInterfaceNames()) {
     addNewInterface(ifName, ifaList);
   }
   this->emitSignal(onEnumerationCompleted);
 }

 std::set<std::string>
 NetworkMonitorImplOsx::getInterfaceNames() const
 {
   CFReleaser<CFDictionaryRef> dict =
     (CFDictionaryRef)SCDynamicStoreCopyValue(m_scStore.get(), CFSTR("State:/Network/Interface"));
   if (dict.get() == nullptr) {
     return {};
   }

   CFArrayRef interfaces = (CFArrayRef)CFDictionaryGetValue(dict.get(), CFSTR("Interfaces"));
   if (interfaces == nullptr) {
     return {};
   }

   std::set<std::string> ifNames;
   size_t count = CFArrayGetCount(interfaces);
   for (size_t i = 0; i != count; ++i) {
     auto ifName = (CFStringRef)CFArrayGetValueAtIndex(interfaces, i);
     ifNames.insert(util::cfstring::toStdString(ifName));
   }
   return ifNames;
 }

 void
 NetworkMonitorImplOsx::addNewInterface(const std::string& ifName, const IfAddrs& ifaList)
 {
   shared_ptr<NetworkInterface> interface = makeNetworkInterface();
   interface->setName(ifName);
   interface->setState(getInterfaceState(*interface));
   updateInterfaceInfo(*interface, ifaList);

   if (interface->getType() == InterfaceType::UNKNOWN) {
     NDN_LOG_DEBUG("ignoring " << ifName << " due to unhandled interface type");
     return;
   }

   NDN_LOG_DEBUG("adding interface " << interface->getName());
   m_interfaces[interface->getName()] = interface;
   this->emitSignal(onInterfaceAdded, interface);
 }

 InterfaceState
 NetworkMonitorImplOsx::getInterfaceState(const NetworkInterface& netif) const
 {
   CFReleaser<CFStringRef> linkName =
     util::cfstring::fromStdString("State:/Network/Interface/" + netif.getName() + "/Link");

   CFReleaser<CFDictionaryRef> dict =
     (CFDictionaryRef)SCDynamicStoreCopyValue(m_scStore.get(), linkName.get());
   if (dict.get() == nullptr) {
     return InterfaceState::UNKNOWN;
   }

   CFBooleanRef isActive = (CFBooleanRef)CFDictionaryGetValue(dict.get(), CFSTR("Active"));
   if (isActive == nullptr) {
     return InterfaceState::UNKNOWN;
   }

   return CFBooleanGetValue(isActive) ? InterfaceState::RUNNING : InterfaceState::DOWN;
 }

 size_t
 NetworkMonitorImplOsx::getInterfaceMtu(const NetworkInterface& netif)
 {
   ifreq ifr{};
   std::strncpy(ifr.ifr_name, netif.getName().data(), sizeof(ifr.ifr_name) - 1);

   if (::ioctl(m_ioctlSocket.native_handle(), SIOCGIFMTU, &ifr) == 0) {
     return static_cast<size_t>(ifr.ifr_mtu);
   }

   NDN_LOG_WARN("failed to get MTU of " << netif.getName() << ": " << std::strerror(errno));
   return ethernet::MAX_DATA_LEN;
 }

 template<typename AddressBytes>
 static uint8_t
 computePrefixLength(const AddressBytes& mask)
 {
   uint8_t prefixLength = 0;
   for (auto byte : mask) {
     while (byte != 0) {
       ++prefixLength;
       byte <<= 1;
     }
   }
   return prefixLength;
 }

 void
 NetworkMonitorImplOsx::updateInterfaceInfo(NetworkInterface& netif, const IfAddrs& ifaList)
 {
   BOOST_ASSERT(!netif.getName().empty());

   netif.setMtu(getInterfaceMtu(netif));

   for (ifaddrs* ifa = ifaList.get(); ifa != nullptr; ifa = ifa->ifa_next) {
     if (ifa->ifa_name != netif.getName())
       continue;

     netif.setFlags(ifa->ifa_flags);

     if (ifa->ifa_addr == nullptr)
       continue;

     namespace ip = boost::asio::ip;
     AddressFamily addrFamily = AddressFamily::UNSPECIFIED;
     ip::address ipAddr, broadcastAddr;
     uint8_t prefixLength = 0;

     switch (ifa->ifa_addr->sa_family) {
       case AF_INET: {
         addrFamily = AddressFamily::V4;

         const sockaddr_in* sin = reinterpret_cast<sockaddr_in*>(ifa->ifa_addr);
         ip::address_v4::bytes_type bytes;
         std::copy_n(reinterpret_cast<const unsigned char*>(&sin->sin_addr), bytes.size(), bytes.begin());
         ipAddr = ip::address_v4(bytes);

         const sockaddr_in* sinMask = reinterpret_cast<sockaddr_in*>(ifa->ifa_netmask);
         std::copy_n(reinterpret_cast<const unsigned char*>(&sinMask->sin_addr), bytes.size(), bytes.begin());
         prefixLength = computePrefixLength(bytes);
         break;
       }

       case AF_INET6: {
         addrFamily = AddressFamily::V6;

         const sockaddr_in6* sin6 = reinterpret_cast<sockaddr_in6*>(ifa->ifa_addr);
         ip::address_v6::bytes_type bytes;
         std::copy_n(reinterpret_cast<const unsigned char*>(&sin6->sin6_addr), bytes.size(), bytes.begin());
         ip::address_v6 v6Addr(bytes);
         if (v6Addr.is_link_local())
           v6Addr.scope_id(if_nametoindex(netif.getName().data()));
         ipAddr = v6Addr;

         const sockaddr_in6* sinMask = reinterpret_cast<sockaddr_in6*>(ifa->ifa_netmask);
         std::copy_n(reinterpret_cast<const unsigned char*>(&sinMask->sin6_addr), bytes.size(), bytes.begin());
         prefixLength = computePrefixLength(bytes);
         break;
       }

       case AF_LINK: {
         const sockaddr_dl* sdl = reinterpret_cast<sockaddr_dl*>(ifa->ifa_addr);
         netif.setIndex(sdl->sdl_index);

         if (sdl->sdl_type == IFT_ETHER && sdl->sdl_alen == ethernet::ADDR_LEN) {
           netif.setType(InterfaceType::ETHERNET);
           netif.setEthernetAddress(ethernet::Address(reinterpret_cast<uint8_t*>(LLADDR(sdl))));
           NDN_LOG_TRACE(netif.getName() << " has Ethernet address " << netif.getEthernetAddress());
         }
         else if (sdl->sdl_type == IFT_LOOP) {
           netif.setType(InterfaceType::LOOPBACK);
         }
         else {
           netif.setType(InterfaceType::UNKNOWN);
         }
         break;
       }
     }

     if (netif.canBroadcast()) {
       netif.setEthernetBroadcastAddress(ethernet::getBroadcastAddress());

       if (addrFamily == AddressFamily::V4 && ifa->ifa_broadaddr != nullptr) {
         const sockaddr_in* sin = reinterpret_cast<sockaddr_in*>(ifa->ifa_broadaddr);
         ip::address_v4::bytes_type bytes;
         std::copy_n(reinterpret_cast<const unsigned char*>(&sin->sin_addr), bytes.size(), bytes.begin());
         broadcastAddr = ip::address_v4(bytes);
       }
     }

     if (addrFamily == AddressFamily::UNSPECIFIED)
       continue;

     AddressScope scope = AddressScope::GLOBAL;
     if (ipAddr.is_loopback()) {
       scope = AddressScope::HOST;
     }
     else if ((ipAddr.is_v4() && (ipAddr.to_v4().to_ulong() & 0xFFFF0000) == 0xA9FE0000) ||
              (ipAddr.is_v6() && ipAddr.to_v6().is_link_local())) {
       scope = AddressScope::LINK;
     }

     netif.addNetworkAddress(NetworkAddress(addrFamily, ipAddr, broadcastAddr, prefixLength, scope, 0));
   }
 }

 void
 NetworkMonitorImplOsx::onConfigChanged(SCDynamicStoreRef m_scStore, CFArrayRef changedKeys, void* context)
 {
   static_cast<NetworkMonitorImplOsx*>(context)->onConfigChanged(changedKeys);
 }

 void
 NetworkMonitorImplOsx::onConfigChanged(CFArrayRef changedKeys)
 {
   IfAddrs ifaList;

   size_t count = CFArrayGetCount(changedKeys);
   for (size_t i = 0; i != count; ++i) {
     Name key(util::cfstring::toStdString((CFStringRef)CFArrayGetValueAtIndex(changedKeys, i)));
     std::string ifName = key.at(-2).toUri();

     auto ifIt = m_interfaces.find(ifName);
     if (ifIt == m_interfaces.end()) {
       addNewInterface(ifName, ifaList);
       return;
     }

     auto removeInterface = [&] {
       NDN_LOG_DEBUG("removing interface " << ifName);
       shared_ptr<NetworkInterface> removedNetif = ifIt->second;
       m_interfaces.erase(ifIt);
       this->emitSignal(onInterfaceRemoved, removedNetif);
     };

     NetworkInterface& netif = *ifIt->second;
     std::string changedItem = key.at(-1).toUri();
     if (changedItem == "Link") {
       auto newState = getInterfaceState(netif);
       if (newState == InterfaceState::UNKNOWN) {
         // check if it is really unknown or interface removed
         if (getInterfaceNames().count(ifName) == 0) {
           removeInterface();
           return;
         }
       }
       NDN_LOG_TRACE(ifName << " status changed from " << netif.getState() << " to " << newState);
       netif.setState(newState);
     }
     else if (changedItem == "IPv4" || changedItem == "IPv6") {
       auto updatedNetif = makeNetworkInterface();
       updatedNetif->setName(ifName);
       updateInterfaceInfo(*updatedNetif, ifaList);
       if (updatedNetif->getType() == InterfaceType::UNKNOWN) {
         NDN_LOG_DEBUG(ifName << " type changed to unknown");
         removeInterface();
         return;
       }

       const auto& newAddrs = updatedNetif->getNetworkAddresses();
       const auto& oldAddrs = netif.getNetworkAddresses();
       std::set<NetworkAddress> added;
       std::set<NetworkAddress> removed;
       std::set_difference(newAddrs.begin(), newAddrs.end(),
                           oldAddrs.begin(), oldAddrs.end(), std::inserter(added, added.end()));
       std::set_difference(oldAddrs.begin(), oldAddrs.end(),
                           newAddrs.begin(), newAddrs.end(), std::inserter(removed, removed.end()));

       for (const auto& addr : removed) {
         netif.removeNetworkAddress(addr);
       }
       for (const auto& addr : added) {
         netif.addNetworkAddress(addr);
       }
     }
   }
 }

 } // namespace net
 } // namespace ndn
	/* -- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -- */
	/*
	* Copyright (c) 2013-2018 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.
	*
	*
	* Parts of this implementation is based on daemondo command of MacPorts
	* (https://www.macports.org/):
	*
	* Copyright (c) 2005-2007 James Berry <jberry@macports.org>
	* 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 MacPorts Project 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 OWNER 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 "ndn-cxx/net/detail/network-monitor-impl-osx.hpp"
	#include "ndn-cxx/net/network-address.hpp"
	#include "ndn-cxx/name.hpp"
	#include "ndn-cxx/util/cf-string-osx.hpp"
	#include "ndn-cxx/util/logger.hpp"

	#include <ifaddrs.h> // for getifaddrs()
	#include <net/if.h> // for if_nametoindex()
	#include <net/if_dl.h> // for struct sockaddr_dl
	#include <net/if_types.h> // for IFT_* constants
	#include <netinet/in.h> // for struct sockaddr_in{,6}

	#include <boost/asio/io_service.hpp>
	#include <boost/asio/ip/address.hpp>
	#include <boost/asio/ip/udp.hpp>

	NDN_LOG_INIT(ndn.NetworkMonitor);

	namespace ndn {
	namespace net {

	using util::CFReleaser;

	class IfAddrs : noncopyable
	{
	public:
	IfAddrs()
	{
	if (::getifaddrs(&m_ifaList) < 0) {
	BOOST_THROW_EXCEPTION(NetworkMonitorImplOsx::Error("getifaddrs() failed: "s + strerror(errno)));
	}
	}

	~IfAddrs()
	{
	if (m_ifaList != nullptr) {
	::freeifaddrs(m_ifaList);
	}
	}

	ifaddrs*
	get() const noexcept
	{
	return m_ifaList;
	}

	private:
	ifaddrs* m_ifaList = nullptr;
	};

	NetworkMonitorImplOsx::NetworkMonitorImplOsx(boost::asio::io_service& io)
	: m_scheduler(io)
	, m_cfLoopEvent(m_scheduler)
	, m_context{0, this, nullptr, nullptr, nullptr}
	, m_scStore(SCDynamicStoreCreate(nullptr, CFSTR("net.named-data.ndn-cxx.NetworkMonitor"),
	&NetworkMonitorImplOsx::onConfigChanged, &m_context))
	, m_loopSource(SCDynamicStoreCreateRunLoopSource(nullptr, m_scStore.get(), 0))
	, m_ioctlSocket(io, boost::asio::ip::udp::v4())
	{
	scheduleCfLoop();

	// Notifications from Darwin Notify Center:
	//
	// com.apple.system.config.network_change
	//
	CFNotificationCenterAddObserver(CFNotificationCenterGetDarwinNotifyCenter(),
	static_cast<void*>(this),
	&NetworkMonitorImplOsx::afterNotificationCenterEvent,
	CFSTR("com.apple.system.config.network_change"),
	nullptr, // object to observe
	CFNotificationSuspensionBehaviorDeliverImmediately);

	CFRunLoopAddSource(CFRunLoopGetCurrent(), m_loopSource.get(), kCFRunLoopDefaultMode);

	// Notifications from SystemConfiguration:
	//
	// State:/Network/Interface/.*/Link
	// State:/Network/Interface/.*/IPv4
	// State:/Network/Interface/.*/IPv6
	// State:/Network/Interface/.*/AirPort (not used)
	//
	// https://developer.apple.com/library/content/documentation/Networking/Conceptual/SystemConfigFrameworks/SC_UnderstandSchema/SC_UnderstandSchema.html
	//
	auto patterns = CFArrayCreateMutable(nullptr, 0, &kCFTypeArrayCallBacks);
	CFArrayAppendValue(patterns, CFSTR("State:/Network/Interface/.*/Link"));
	CFArrayAppendValue(patterns, CFSTR("State:/Network/Interface/.*/IPv4"));
	CFArrayAppendValue(patterns, CFSTR("State:/Network/Interface/.*/IPv6"));

	if (!SCDynamicStoreSetNotificationKeys(m_scStore.get(), nullptr, patterns)) {
	BOOST_THROW_EXCEPTION(Error("SCDynamicStoreSetNotificationKeys failed"));
	}

	io.post([this] { enumerateInterfaces(); });
	}

	NetworkMonitorImplOsx::~NetworkMonitorImplOsx()
	{
	CFRunLoopRemoveSource(CFRunLoopGetCurrent(), m_loopSource.get(), kCFRunLoopDefaultMode);

	CFNotificationCenterRemoveEveryObserver(CFNotificationCenterGetDarwinNotifyCenter(),
	static_cast<void*>(this));
	}

	shared_ptr<const NetworkInterface>
	NetworkMonitorImplOsx::getNetworkInterface(const std::string& ifname) const
	{
	auto it = m_interfaces.find(ifname);
	return it == m_interfaces.end() ? nullptr : it->second;
	}

	std::vector<shared_ptr<const NetworkInterface>>
	NetworkMonitorImplOsx::listNetworkInterfaces() const
	{
	std::vector<shared_ptr<const NetworkInterface>> v;
	v.reserve(m_interfaces.size());

	for (const auto& e : m_interfaces) {
	v.push_back(e.second);
	}
	return v;
	}

	void
	NetworkMonitorImplOsx::afterNotificationCenterEvent(CFNotificationCenterRef center,
	void* observer,
	CFStringRef name,
	const void* object,
	CFDictionaryRef userInfo)
	{
	static_cast<NetworkMonitorImplOsx*>(observer)->emitSignal(onNetworkStateChanged);
	}

	void
	NetworkMonitorImplOsx::scheduleCfLoop()
	{
	// poll each second for new events
	m_cfLoopEvent = m_scheduler.scheduleEvent(1_s, [this] {
	// this should dispatch ready events and exit
	CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0, true);
	scheduleCfLoop();
	});
	}

	void
	NetworkMonitorImplOsx::enumerateInterfaces()
	{
	IfAddrs ifaList;
	for (const auto& ifName : getInterfaceNames()) {
	addNewInterface(ifName, ifaList);
	}
	this->emitSignal(onEnumerationCompleted);
	}

	std::set<std::string>
	NetworkMonitorImplOsx::getInterfaceNames() const
	{
	CFReleaser<CFDictionaryRef> dict =
	(CFDictionaryRef)SCDynamicStoreCopyValue(m_scStore.get(), CFSTR("State:/Network/Interface"));
	if (dict.get() == nullptr) {
	return {};
	}

	CFArrayRef interfaces = (CFArrayRef)CFDictionaryGetValue(dict.get(), CFSTR("Interfaces"));
	if (interfaces == nullptr) {
	return {};
	}

	std::set<std::string> ifNames;
	size_t count = CFArrayGetCount(interfaces);
	for (size_t i = 0; i != count; ++i) {
	auto ifName = (CFStringRef)CFArrayGetValueAtIndex(interfaces, i);
	ifNames.insert(util::cfstring::toStdString(ifName));
	}
	return ifNames;
	}

	void
	NetworkMonitorImplOsx::addNewInterface(const std::string& ifName, const IfAddrs& ifaList)
	{
	shared_ptr<NetworkInterface> interface = makeNetworkInterface();
	interface->setName(ifName);
	interface->setState(getInterfaceState(*interface));
	updateInterfaceInfo(*interface, ifaList);

	if (interface->getType() == InterfaceType::UNKNOWN) {
	NDN_LOG_DEBUG("ignoring " << ifName << " due to unhandled interface type");
	return;
	}

	NDN_LOG_DEBUG("adding interface " << interface->getName());
	m_interfaces[interface->getName()] = interface;
	this->emitSignal(onInterfaceAdded, interface);
	}

	InterfaceState
	NetworkMonitorImplOsx::getInterfaceState(const NetworkInterface& netif) const
	{
	CFReleaser<CFStringRef> linkName =
	util::cfstring::fromStdString("State:/Network/Interface/" + netif.getName() + "/Link");

	CFReleaser<CFDictionaryRef> dict =
	(CFDictionaryRef)SCDynamicStoreCopyValue(m_scStore.get(), linkName.get());
	if (dict.get() == nullptr) {
	return InterfaceState::UNKNOWN;
	}

	CFBooleanRef isActive = (CFBooleanRef)CFDictionaryGetValue(dict.get(), CFSTR("Active"));
	if (isActive == nullptr) {
	return InterfaceState::UNKNOWN;
	}

	return CFBooleanGetValue(isActive) ? InterfaceState::RUNNING : InterfaceState::DOWN;
	}

	size_t
	NetworkMonitorImplOsx::getInterfaceMtu(const NetworkInterface& netif)
	{
	ifreq ifr{};
	std::strncpy(ifr.ifr_name, netif.getName().data(), sizeof(ifr.ifr_name) - 1);

	if (::ioctl(m_ioctlSocket.native_handle(), SIOCGIFMTU, &ifr) == 0) {
	return static_cast<size_t>(ifr.ifr_mtu);
	}

	NDN_LOG_WARN("failed to get MTU of " << netif.getName() << ": " << std::strerror(errno));
	return ethernet::MAX_DATA_LEN;
	}

	template<typename AddressBytes>
	static uint8_t
	computePrefixLength(const AddressBytes& mask)
	{
	uint8_t prefixLength = 0;
	for (auto byte : mask) {
	while (byte != 0) {
	++prefixLength;
	byte <<= 1;
	}
	}
	return prefixLength;
	}

	void
	NetworkMonitorImplOsx::updateInterfaceInfo(NetworkInterface& netif, const IfAddrs& ifaList)
	{
	BOOST_ASSERT(!netif.getName().empty());

	netif.setMtu(getInterfaceMtu(netif));

	for (ifaddrs* ifa = ifaList.get(); ifa != nullptr; ifa = ifa->ifa_next) {
	if (ifa->ifa_name != netif.getName())
	continue;

	netif.setFlags(ifa->ifa_flags);

	if (ifa->ifa_addr == nullptr)
	continue;

	namespace ip = boost::asio::ip;
	AddressFamily addrFamily = AddressFamily::UNSPECIFIED;
	ip::address ipAddr, broadcastAddr;
	uint8_t prefixLength = 0;

	switch (ifa->ifa_addr->sa_family) {
	case AF_INET: {
	addrFamily = AddressFamily::V4;

	const sockaddr_in* sin = reinterpret_cast<sockaddr_in*>(ifa->ifa_addr);
	ip::address_v4::bytes_type bytes;
	std::copy_n(reinterpret_cast<const unsigned char*>(&sin->sin_addr), bytes.size(), bytes.begin());
	ipAddr = ip::address_v4(bytes);

	const sockaddr_in* sinMask = reinterpret_cast<sockaddr_in*>(ifa->ifa_netmask);
	std::copy_n(reinterpret_cast<const unsigned char*>(&sinMask->sin_addr), bytes.size(), bytes.begin());
	prefixLength = computePrefixLength(bytes);
	break;
	}

	case AF_INET6: {
	addrFamily = AddressFamily::V6;

	const sockaddr_in6* sin6 = reinterpret_cast<sockaddr_in6*>(ifa->ifa_addr);
	ip::address_v6::bytes_type bytes;
	std::copy_n(reinterpret_cast<const unsigned char*>(&sin6->sin6_addr), bytes.size(), bytes.begin());
	ip::address_v6 v6Addr(bytes);
	if (v6Addr.is_link_local())
	v6Addr.scope_id(if_nametoindex(netif.getName().data()));
	ipAddr = v6Addr;

	const sockaddr_in6* sinMask = reinterpret_cast<sockaddr_in6*>(ifa->ifa_netmask);
	std::copy_n(reinterpret_cast<const unsigned char*>(&sinMask->sin6_addr), bytes.size(), bytes.begin());
	prefixLength = computePrefixLength(bytes);
	break;
	}

	case AF_LINK: {
	const sockaddr_dl* sdl = reinterpret_cast<sockaddr_dl*>(ifa->ifa_addr);
	netif.setIndex(sdl->sdl_index);

	if (sdl->sdl_type == IFT_ETHER && sdl->sdl_alen == ethernet::ADDR_LEN) {
	netif.setType(InterfaceType::ETHERNET);
	netif.setEthernetAddress(ethernet::Address(reinterpret_cast<uint8_t*>(LLADDR(sdl))));
	NDN_LOG_TRACE(netif.getName() << " has Ethernet address " << netif.getEthernetAddress());
	}
	else if (sdl->sdl_type == IFT_LOOP) {
	netif.setType(InterfaceType::LOOPBACK);
	}
	else {
	netif.setType(InterfaceType::UNKNOWN);
	}
	break;
	}
	}

	if (netif.canBroadcast()) {
	netif.setEthernetBroadcastAddress(ethernet::getBroadcastAddress());

	if (addrFamily == AddressFamily::V4 && ifa->ifa_broadaddr != nullptr) {
	const sockaddr_in* sin = reinterpret_cast<sockaddr_in*>(ifa->ifa_broadaddr);
	ip::address_v4::bytes_type bytes;
	std::copy_n(reinterpret_cast<const unsigned char*>(&sin->sin_addr), bytes.size(), bytes.begin());
	broadcastAddr = ip::address_v4(bytes);
	}
	}

	if (addrFamily == AddressFamily::UNSPECIFIED)
	continue;

	AddressScope scope = AddressScope::GLOBAL;
	if (ipAddr.is_loopback()) {
	scope = AddressScope::HOST;
	}
	else if ((ipAddr.is_v4() && (ipAddr.to_v4().to_ulong() & 0xFFFF0000) == 0xA9FE0000) \|\|
	(ipAddr.is_v6() && ipAddr.to_v6().is_link_local())) {
	scope = AddressScope::LINK;
	}

	netif.addNetworkAddress(NetworkAddress(addrFamily, ipAddr, broadcastAddr, prefixLength, scope, 0));
	}
	}

	void
	NetworkMonitorImplOsx::onConfigChanged(SCDynamicStoreRef m_scStore, CFArrayRef changedKeys, void* context)
	{
	static_cast<NetworkMonitorImplOsx*>(context)->onConfigChanged(changedKeys);
	}

	void
	NetworkMonitorImplOsx::onConfigChanged(CFArrayRef changedKeys)
	{
	IfAddrs ifaList;

	size_t count = CFArrayGetCount(changedKeys);
	for (size_t i = 0; i != count; ++i) {
	Name key(util::cfstring::toStdString((CFStringRef)CFArrayGetValueAtIndex(changedKeys, i)));
	std::string ifName = key.at(-2).toUri();

	auto ifIt = m_interfaces.find(ifName);
	if (ifIt == m_interfaces.end()) {
	addNewInterface(ifName, ifaList);
	return;
	}

	auto removeInterface = [&] {
	NDN_LOG_DEBUG("removing interface " << ifName);
	shared_ptr<NetworkInterface> removedNetif = ifIt->second;
	m_interfaces.erase(ifIt);
	this->emitSignal(onInterfaceRemoved, removedNetif);
	};

	NetworkInterface& netif = *ifIt->second;
	std::string changedItem = key.at(-1).toUri();
	if (changedItem == "Link") {
	auto newState = getInterfaceState(netif);
	if (newState == InterfaceState::UNKNOWN) {
	// check if it is really unknown or interface removed
	if (getInterfaceNames().count(ifName) == 0) {
	removeInterface();
	return;
	}
	}
	NDN_LOG_TRACE(ifName << " status changed from " << netif.getState() << " to " << newState);
	netif.setState(newState);
	}
	else if (changedItem == "IPv4" \|\| changedItem == "IPv6") {
	auto updatedNetif = makeNetworkInterface();
	updatedNetif->setName(ifName);
	updateInterfaceInfo(*updatedNetif, ifaList);
	if (updatedNetif->getType() == InterfaceType::UNKNOWN) {
	NDN_LOG_DEBUG(ifName << " type changed to unknown");
	removeInterface();
	return;
	}

	const auto& newAddrs = updatedNetif->getNetworkAddresses();
	const auto& oldAddrs = netif.getNetworkAddresses();
	std::set<NetworkAddress> added;
	std::set<NetworkAddress> removed;
	std::set_difference(newAddrs.begin(), newAddrs.end(),
	oldAddrs.begin(), oldAddrs.end(), std::inserter(added, added.end()));
	std::set_difference(oldAddrs.begin(), oldAddrs.end(),
	newAddrs.begin(), newAddrs.end(), std::inserter(removed, removed.end()));

	for (const auto& addr : removed) {
	netif.removeNetworkAddress(addr);
	}
	for (const auto& addr : added) {
	netif.addNetworkAddress(addr);
	}
	}
	}
	}

	} // namespace net
	} // namespace ndn