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

 /* -*- 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.
  *
  *
  * 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-config.hpp"

 #include "network-monitor-impl-osx.hpp"
 #include "../../name.hpp"
 #include "../../util/logger.hpp"
 #include "../network-address.hpp"

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

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

 namespace ndn {
 namespace net {

 using util::CFReleaser;

 NDN_LOG_INIT(ndn.NetworkMonitor);

 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_nullUdpSocket(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);

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

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

   // Notifications from SystemConfiguration:
   //
   // State:/Network/Interface/.*/Link
   // State:/Network/Interface/.*/IPv4
   // State:/Network/Interface/.*/IPv6
   // State:/Network/Global/DNS
   // State:/Network/Global/IPv4
   //
   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"));
   // CFArrayAppendValue(patterns, CFSTR("State:/Network/Global/DNS"));
   // CFArrayAppendValue(patterns, CFSTR("State:/Network/Global/IPv4"));

   SCDynamicStoreSetNotificationKeys(m_scStore.get(), nullptr, patterns);
 }

 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(time::seconds(1), [this] { pollCfLoop(); });
 }

 void
 NetworkMonitorImplOsx::pollCfLoop()
 {
   // this should dispatch ready events and exit
   CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0, true);

   scheduleCfLoop();
 }

 void
 NetworkMonitorImplOsx::addNewInterface(const std::string& ifName)
 {
   shared_ptr<NetworkInterface> interface = makeNetworkInterface();
   interface->setName(ifName);
   interface->setState(getInterfaceState(interface->getName()));
   updateInterfaceInfo(*interface);
   if (interface->getType() == InterfaceType::UNKNOWN) {
     NDN_LOG_DEBUG("ignoring " << ifName << " because it has unhandled interface type");
     return;
   }

   NDN_LOG_DEBUG("adding interface " << interface->getName());
   m_interfaces.insert(make_pair(interface->getName(), interface));
   this->emitSignal(onInterfaceAdded, interface);
 }

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

 static std::string
 convertToStdString(CFStringRef cfStr)
 {
   const char* cStr = CFStringGetCStringPtr(cfStr, kCFStringEncodingASCII);
   if (cStr != nullptr) {
     // fast path
     return cStr;
   }

   // reserve space for the string + null terminator
   std::string str(CFStringGetLength(cfStr) + 1, '\0');
   if (!CFStringGetCString(cfStr, &str.front(), str.size(), kCFStringEncodingASCII)) {
     BOOST_THROW_EXCEPTION(NetworkMonitorImplOsx::Error("CFString conversion failed"));
   }

   // drop the null terminator, std::string doesn't need it
   str.pop_back();
   return str;
 }

 std::set<std::string>
 NetworkMonitorImplOsx::getInterfaceNames()
 {
   CFReleaser<CFDictionaryRef> dict =
     (CFDictionaryRef)SCDynamicStoreCopyValue(m_scStore.get(), CFSTR("State:/Network/Interface"));
   CFArrayRef interfaces = (CFArrayRef)CFDictionaryGetValue(dict.get(), CFSTR("Interfaces"));

   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(convertToStdString(ifName));
   }
   return ifNames;
 }

 InterfaceState
 NetworkMonitorImplOsx::getInterfaceState(const std::string& ifName)
 {
   CFReleaser<CFStringRef> linkName =
     CFStringCreateWithCString(nullptr, ("State:/Network/Interface/" + ifName + "/Link").c_str(),
                               kCFStringEncodingASCII);

   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;
 }

 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)
 {
   ifaddrs* ifa_list = nullptr;
   if (::getifaddrs(&ifa_list) < 0) {
     BOOST_THROW_EXCEPTION(Error(std::string("getifaddrs() failed: ") + strerror(errno)));
   }

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

     netif.setFlags(ifa->ifa_flags);
     netif.setMtu(getInterfaceMtu(netif.getName()));

     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());
         ipAddr = ip::address_v6(bytes);

         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() << ": set 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);
         NDN_LOG_TRACE(netif.getName() << ": set IPv4 broadcast address " << broadcastAddr);
       }
     }

     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));
   }

   ::freeifaddrs(ifa_list);
 }

 size_t
 NetworkMonitorImplOsx::getInterfaceMtu(const std::string& ifName)
 {
   ifreq ifr{};
   std::strncpy(ifr.ifr_name, ifName.c_str(), sizeof(ifr.ifr_name) - 1);

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

   NDN_LOG_WARN("Failed to get interface MTU: " << std::strerror(errno));
   return ethernet::MAX_DATA_LEN;
 }

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

 void
 NetworkMonitorImplOsx::onConfigChanged(CFArrayRef changedKeys)
 {
   size_t count = CFArrayGetCount(changedKeys);
   for (size_t i = 0; i != count; ++i) {
     std::string keyName = convertToStdString((CFStringRef)CFArrayGetValueAtIndex(changedKeys, i));
     Name key(keyName);
     std::string ifName = key.at(-2).toUri();

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

     NetworkInterface& netif = *ifIt->second;

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

     if (key.at(-1).toUri() == "Link") {
       auto newState = getInterfaceState(ifName);

       if (newState == InterfaceState::UNKNOWN) {
         // check if it is really unknown or interface removed
         if (getInterfaceNames().count(ifName) == 0) {
           // newState = InterfaceState::DOWN;
           removeInterface();
           return;
         }
       }

       NDN_LOG_TRACE("Status of " << ifName << " changed from " << netif.getState() << " to " << newState);
       netif.setState(newState);
     }

     if (key.at(-1).toUri() == "IPv4" || key.at(-1).toUri() == "IPv6") {
       shared_ptr<NetworkInterface> updatedInterface = makeNetworkInterface();
       updatedInterface->setName(ifName);
       updateInterfaceInfo(*updatedInterface);
       if (updatedInterface->getType() == InterfaceType::UNKNOWN) {
         // somehow, type of interface changed to unknown
         NDN_LOG_DEBUG("Removing " << ifName << " because it changed to unhandled interface type");
         removeInterface();
         return;
       }

       const auto& newAddrs = updatedInterface->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) 2013-2017 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.
	*
	*
	* 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-config.hpp"

	#include "network-monitor-impl-osx.hpp"
	#include "../../name.hpp"
	#include "../../util/logger.hpp"
	#include "../network-address.hpp"

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

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

	namespace ndn {
	namespace net {

	using util::CFReleaser;

	NDN_LOG_INIT(ndn.NetworkMonitor);

	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_nullUdpSocket(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);

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

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

	// Notifications from SystemConfiguration:
	//
	// State:/Network/Interface/.*/Link
	// State:/Network/Interface/.*/IPv4
	// State:/Network/Interface/.*/IPv6
	// State:/Network/Global/DNS
	// State:/Network/Global/IPv4
	//
	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"));
	// CFArrayAppendValue(patterns, CFSTR("State:/Network/Global/DNS"));
	// CFArrayAppendValue(patterns, CFSTR("State:/Network/Global/IPv4"));

	SCDynamicStoreSetNotificationKeys(m_scStore.get(), nullptr, patterns);
	}

	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(time::seconds(1), [this] { pollCfLoop(); });
	}

	void
	NetworkMonitorImplOsx::pollCfLoop()
	{
	// this should dispatch ready events and exit
	CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0, true);

	scheduleCfLoop();
	}

	void
	NetworkMonitorImplOsx::addNewInterface(const std::string& ifName)
	{
	shared_ptr<NetworkInterface> interface = makeNetworkInterface();
	interface->setName(ifName);
	interface->setState(getInterfaceState(interface->getName()));
	updateInterfaceInfo(*interface);
	if (interface->getType() == InterfaceType::UNKNOWN) {
	NDN_LOG_DEBUG("ignoring " << ifName << " because it has unhandled interface type");
	return;
	}

	NDN_LOG_DEBUG("adding interface " << interface->getName());
	m_interfaces.insert(make_pair(interface->getName(), interface));
	this->emitSignal(onInterfaceAdded, interface);
	}

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

	static std::string
	convertToStdString(CFStringRef cfStr)
	{
	const char* cStr = CFStringGetCStringPtr(cfStr, kCFStringEncodingASCII);
	if (cStr != nullptr) {
	// fast path
	return cStr;
	}

	// reserve space for the string + null terminator
	std::string str(CFStringGetLength(cfStr) + 1, '\0');
	if (!CFStringGetCString(cfStr, &str.front(), str.size(), kCFStringEncodingASCII)) {
	BOOST_THROW_EXCEPTION(NetworkMonitorImplOsx::Error("CFString conversion failed"));
	}

	// drop the null terminator, std::string doesn't need it
	str.pop_back();
	return str;
	}

	std::set<std::string>
	NetworkMonitorImplOsx::getInterfaceNames()
	{
	CFReleaser<CFDictionaryRef> dict =
	(CFDictionaryRef)SCDynamicStoreCopyValue(m_scStore.get(), CFSTR("State:/Network/Interface"));
	CFArrayRef interfaces = (CFArrayRef)CFDictionaryGetValue(dict.get(), CFSTR("Interfaces"));

	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(convertToStdString(ifName));
	}
	return ifNames;
	}

	InterfaceState
	NetworkMonitorImplOsx::getInterfaceState(const std::string& ifName)
	{
	CFReleaser<CFStringRef> linkName =
	CFStringCreateWithCString(nullptr, ("State:/Network/Interface/" + ifName + "/Link").c_str(),
	kCFStringEncodingASCII);

	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;
	}

	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)
	{
	ifaddrs* ifa_list = nullptr;
	if (::getifaddrs(&ifa_list) < 0) {
	BOOST_THROW_EXCEPTION(Error(std::string("getifaddrs() failed: ") + strerror(errno)));
	}

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

	netif.setFlags(ifa->ifa_flags);
	netif.setMtu(getInterfaceMtu(netif.getName()));

	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());
	ipAddr = ip::address_v6(bytes);

	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() << ": set 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);
	NDN_LOG_TRACE(netif.getName() << ": set IPv4 broadcast address " << broadcastAddr);
	}
	}

	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));
	}

	::freeifaddrs(ifa_list);
	}

	size_t
	NetworkMonitorImplOsx::getInterfaceMtu(const std::string& ifName)
	{
	ifreq ifr{};
	std::strncpy(ifr.ifr_name, ifName.c_str(), sizeof(ifr.ifr_name) - 1);

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

	NDN_LOG_WARN("Failed to get interface MTU: " << std::strerror(errno));
	return ethernet::MAX_DATA_LEN;
	}

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

	void
	NetworkMonitorImplOsx::onConfigChanged(CFArrayRef changedKeys)
	{
	size_t count = CFArrayGetCount(changedKeys);
	for (size_t i = 0; i != count; ++i) {
	std::string keyName = convertToStdString((CFStringRef)CFArrayGetValueAtIndex(changedKeys, i));
	Name key(keyName);
	std::string ifName = key.at(-2).toUri();

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

	NetworkInterface& netif = *ifIt->second;

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

	if (key.at(-1).toUri() == "Link") {
	auto newState = getInterfaceState(ifName);

	if (newState == InterfaceState::UNKNOWN) {
	// check if it is really unknown or interface removed
	if (getInterfaceNames().count(ifName) == 0) {
	// newState = InterfaceState::DOWN;
	removeInterface();
	return;
	}
	}

	NDN_LOG_TRACE("Status of " << ifName << " changed from " << netif.getState() << " to " << newState);
	netif.setState(newState);
	}

	if (key.at(-1).toUri() == "IPv4" \|\| key.at(-1).toUri() == "IPv6") {
	shared_ptr<NetworkInterface> updatedInterface = makeNetworkInterface();
	updatedInterface->setName(ifName);
	updateInterfaceInfo(*updatedInterface);
	if (updatedInterface->getType() == InterfaceType::UNKNOWN) {
	// somehow, type of interface changed to unknown
	NDN_LOG_DEBUG("Removing " << ifName << " because it changed to unhandled interface type");
	removeInterface();
	return;
	}

	const auto& newAddrs = updatedInterface->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