daemon/face/udp-factory.cpp - NFD - Gitiles

 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
  * Copyright (c) 2014-2022,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
  *                           Washington University in St. Louis,
  *                           Beijing Institute of Technology,
  *                           The University of Memphis.
  *
  * This file is part of NFD (Named Data Networking Forwarding Daemon).
  * See AUTHORS.md for complete list of NFD authors and contributors.
  *
  * NFD is free software: you can redistribute it and/or modify it under the terms
  * of the GNU General Public License as published by the Free Software Foundation,
  * either version 3 of the License, or (at your option) any later version.
  *
  * NFD 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 General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License along with
  * NFD, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
  */

 #include "udp-factory.hpp"
 #include "generic-link-service.hpp"
 #include "multicast-udp-transport.hpp"
 #include "common/global.hpp"

 #include <boost/range/adaptor/map.hpp>
 #include <boost/range/algorithm/copy.hpp>

 namespace nfd {
 namespace face {

 namespace ip = boost::asio::ip;
 namespace net = ndn::net;

 NFD_LOG_INIT(UdpFactory);
 NFD_REGISTER_PROTOCOL_FACTORY(UdpFactory);

 const std::string&
 UdpFactory::getId() noexcept
 {
   static std::string id("udp");
   return id;
 }

 UdpFactory::UdpFactory(const CtorParams& params)
   : ProtocolFactory(params)
 {
   m_netifAddConn = netmon->onInterfaceAdded.connect([this] (const auto& netif) {
     this->applyMcastConfigToNetif(netif);
   });
 }

 void
 UdpFactory::doProcessConfig(OptionalConfigSection configSection,
                             FaceSystem::ConfigContext& context)
 {
   // udp
   // {
   //   listen yes
   //   port 6363
   //   enable_v4 yes
   //   enable_v6 yes
   //   idle_timeout 600
   //   unicast_mtu 8800
   //   mcast yes
   //   mcast_group 224.0.23.170
   //   mcast_port 56363
   //   mcast_group_v6 ff02::1234
   //   mcast_port_v6 56363
   //   mcast_ad_hoc no
   //   whitelist
   //   {
   //     *
   //   }
   //   blacklist
   //   {
   //   }
   // }

   m_wantCongestionMarking = context.generalConfig.wantCongestionMarking;

   bool wantListen = true;
   uint16_t port = 6363;
   bool enableV4 = false;
   bool enableV6 = false;
   uint32_t idleTimeout = 600;
   size_t unicastMtu = ndn::MAX_NDN_PACKET_SIZE;
   MulticastConfig mcastConfig;

   if (configSection) {
     // These default to 'yes' but only if face_system.udp section is present
     enableV4 = enableV6 = mcastConfig.isEnabled = true;

     for (const auto& pair : *configSection) {
       const std::string& key = pair.first;
       const ConfigSection& value = pair.second;

       if (key == "listen") {
         wantListen = ConfigFile::parseYesNo(pair, "face_system.udp");
       }
       else if (key == "port") {
         port = ConfigFile::parseNumber<uint16_t>(pair, "face_system.udp");
       }
       else if (key == "enable_v4") {
         enableV4 = ConfigFile::parseYesNo(pair, "face_system.udp");
       }
       else if (key == "enable_v6") {
         enableV6 = ConfigFile::parseYesNo(pair, "face_system.udp");
       }
       else if (key == "idle_timeout") {
         idleTimeout = ConfigFile::parseNumber<uint32_t>(pair, "face_system.udp");
       }
       else if (key == "unicast_mtu") {
         unicastMtu = ConfigFile::parseNumber<size_t>(pair, "face_system.udp");
         ConfigFile::checkRange(unicastMtu, static_cast<size_t>(MIN_MTU), ndn::MAX_NDN_PACKET_SIZE,
                                "unicast_mtu", "face_system.udp");
       }
       else if (key == "keep_alive_interval") {
         // ignored
       }
       else if (key == "mcast") {
         mcastConfig.isEnabled = ConfigFile::parseYesNo(pair, "face_system.udp");
       }
       else if (key == "mcast_group") {
         const std::string& valueStr = value.get_value<std::string>();
         boost::system::error_code ec;
         mcastConfig.group.address(ip::address_v4::from_string(valueStr, ec));
         if (ec) {
           NDN_THROW(ConfigFile::Error("face_system.udp.mcast_group: '" +
                                       valueStr + "' cannot be parsed as an IPv4 address"));
         }
         else if (!mcastConfig.group.address().is_multicast()) {
           NDN_THROW(ConfigFile::Error("face_system.udp.mcast_group: '" +
                                       valueStr + "' is not a multicast address"));
         }
       }
       else if (key == "mcast_port") {
         mcastConfig.group.port(ConfigFile::parseNumber<uint16_t>(pair, "face_system.udp"));
       }
       else if (key == "mcast_group_v6") {
         const std::string& valueStr = value.get_value<std::string>();
         boost::system::error_code ec;
         mcastConfig.groupV6.address(ip::address_v6::from_string(valueStr, ec));
         if (ec) {
           NDN_THROW(ConfigFile::Error("face_system.udp.mcast_group_v6: '" +
                                       valueStr + "' cannot be parsed as an IPv6 address"));
         }
         else if (!mcastConfig.groupV6.address().is_multicast()) {
           NDN_THROW(ConfigFile::Error("face_system.udp.mcast_group_v6: '" +
                                       valueStr + "' is not a multicast address"));
         }
       }
       else if (key == "mcast_port_v6") {
         mcastConfig.groupV6.port(ConfigFile::parseNumber<uint16_t>(pair, "face_system.udp"));
       }
       else if (key == "mcast_ad_hoc") {
         bool wantAdHoc = ConfigFile::parseYesNo(pair, "face_system.udp");
         mcastConfig.linkType = wantAdHoc ? ndn::nfd::LINK_TYPE_AD_HOC : ndn::nfd::LINK_TYPE_MULTI_ACCESS;
       }
       else if (key == "whitelist") {
         mcastConfig.netifPredicate.parseWhitelist(value);
       }
       else if (key == "blacklist") {
         mcastConfig.netifPredicate.parseBlacklist(value);
       }
       else {
         NDN_THROW(ConfigFile::Error("Unrecognized option face_system.udp." + key));
       }
     }

     if (!enableV4 && !enableV6 && !mcastConfig.isEnabled) {
       NDN_THROW(ConfigFile::Error(
         "IPv4 and IPv6 UDP channels and UDP multicast have been disabled. "
         "Remove face_system.udp section to disable UDP channels or enable at least one of them."));
     }
   }

   if (context.isDryRun) {
     return;
   }

   m_defaultUnicastMtu = unicastMtu;

   if (enableV4) {
     udp::Endpoint endpoint(ip::udp::v4(), port);
     shared_ptr<UdpChannel> v4Channel = this->createChannel(endpoint, time::seconds(idleTimeout));
     if (wantListen && !v4Channel->isListening()) {
       v4Channel->listen(this->addFace, nullptr);
     }
     providedSchemes.insert("udp");
     providedSchemes.insert("udp4");
   }
   else if (providedSchemes.count("udp4") > 0) {
     NFD_LOG_WARN("Cannot close udp4 channel after its creation");
   }

   if (enableV6) {
     udp::Endpoint endpoint(ip::udp::v6(), port);
     shared_ptr<UdpChannel> v6Channel = this->createChannel(endpoint, time::seconds(idleTimeout));
     if (wantListen && !v6Channel->isListening()) {
       v6Channel->listen(this->addFace, nullptr);
     }
     providedSchemes.insert("udp");
     providedSchemes.insert("udp6");
   }
   else if (providedSchemes.count("udp6") > 0) {
     NFD_LOG_WARN("Cannot close udp6 channel after its creation");
   }

   if (m_mcastConfig.isEnabled != mcastConfig.isEnabled) {
     if (mcastConfig.isEnabled) {
       NFD_LOG_INFO("enabling multicast on " << mcastConfig.group);
       NFD_LOG_INFO("enabling multicast on " << mcastConfig.groupV6);
     }
     else {
       NFD_LOG_INFO("disabling multicast");
     }
   }
   else if (mcastConfig.isEnabled) {
     if (m_mcastConfig.linkType != mcastConfig.linkType && !m_mcastFaces.empty()) {
       NFD_LOG_WARN("Cannot change ad hoc setting on existing faces");
     }
     if (m_mcastConfig.group != mcastConfig.group) {
       NFD_LOG_INFO("changing IPv4 multicast group from " << m_mcastConfig.group <<
                    " to " << mcastConfig.group);
     }
     if (m_mcastConfig.groupV6 != mcastConfig.groupV6) {
       NFD_LOG_INFO("changing IPv6 multicast group from " << m_mcastConfig.groupV6 <<
                    " to " << mcastConfig.groupV6);
     }
     if (m_mcastConfig.netifPredicate != mcastConfig.netifPredicate) {
       NFD_LOG_INFO("changing whitelist/blacklist");
     }
   }

   // Even if there's no configuration change, we still need to re-apply configuration because
   // netifs may have changed.
   m_mcastConfig = mcastConfig;
   this->applyMcastConfig(context);
 }

 void
 UdpFactory::doCreateFace(const CreateFaceRequest& req,
                          const FaceCreatedCallback& onCreated,
                          const FaceCreationFailedCallback& onFailure)
 {
   if (req.localUri) {
     NFD_LOG_TRACE("Cannot create unicast UDP face with LocalUri");
     onFailure(406, "Unicast UDP faces cannot be created with a LocalUri");
     return;
   }

   if (req.params.persistency == ndn::nfd::FACE_PERSISTENCY_ON_DEMAND) {
     NFD_LOG_TRACE("createFace does not support FACE_PERSISTENCY_ON_DEMAND");
     onFailure(406, "Outgoing UDP faces do not support on-demand persistency");
     return;
   }

   udp::Endpoint endpoint(ip::address::from_string(req.remoteUri.getHost()),
                          boost::lexical_cast<uint16_t>(req.remoteUri.getPort()));

   if (endpoint.address().is_multicast()) {
     NFD_LOG_TRACE("createFace does not support multicast faces");
     onFailure(406, "Cannot create multicast UDP faces");
     return;
   }

   if (req.params.wantLocalFields) {
     // UDP faces are never local
     NFD_LOG_TRACE("createFace cannot create non-local face with local fields enabled");
     onFailure(406, "Local fields can only be enabled on faces with local scope");
     return;
   }

   if (req.params.mtu && *req.params.mtu < MIN_MTU) {
     // The specified MTU must be greater than the minimum possible
     NFD_LOG_TRACE("createFace: override MTU cannot be less than " << MIN_MTU);
     onFailure(406, "Override MTU cannot be less than " + to_string(MIN_MTU));
     return;
   }

   // very simple logic for now
   for (const auto& i : m_channels) {
     if ((i.first.address().is_v4() && endpoint.address().is_v4()) ||
         (i.first.address().is_v6() && endpoint.address().is_v6())) {
       i.second->connect(endpoint, req.params, onCreated, onFailure);
       return;
     }
   }

   NFD_LOG_TRACE("No channels available to connect to " << endpoint);
   onFailure(504, "No channels available to connect");
 }

 shared_ptr<UdpChannel>
 UdpFactory::createChannel(const udp::Endpoint& localEndpoint,
                           time::nanoseconds idleTimeout)
 {
   auto it = m_channels.find(localEndpoint);
   if (it != m_channels.end())
     return it->second;

   // check if the endpoint is already used by a multicast face
   if (m_mcastFaces.find(localEndpoint) != m_mcastFaces.end()) {
     NDN_THROW(Error("Cannot create UDP channel on " + boost::lexical_cast<std::string>(localEndpoint) +
                     ", endpoint already allocated to a UDP multicast face"));
   }

   auto channel = std::make_shared<UdpChannel>(localEndpoint, idleTimeout,
                                               m_wantCongestionMarking, m_defaultUnicastMtu);
   m_channels[localEndpoint] = channel;
   return channel;
 }

 std::vector<shared_ptr<const Channel>>
 UdpFactory::doGetChannels() const
 {
   return getChannelsFromMap(m_channels);
 }

 shared_ptr<Face>
 UdpFactory::createMulticastFace(const shared_ptr<const net::NetworkInterface>& netif,
                                 const ip::address& localAddress,
                                 const udp::Endpoint& multicastEndpoint)
 {
   BOOST_ASSERT(multicastEndpoint.address().is_multicast());

   udp::Endpoint localEp(localAddress, multicastEndpoint.port());
   BOOST_ASSERT(localEp.protocol() == multicastEndpoint.protocol());

   auto mcastEp = multicastEndpoint;
   if (mcastEp.address().is_v6()) {
     // in IPv6, a scope id on the multicast address is always required
     auto mcastAddress = mcastEp.address().to_v6();
     mcastAddress.scope_id(netif->getIndex());
     mcastEp.address(mcastAddress);
   }

   // check if the local endpoint is already used by another multicast face
   auto it = m_mcastFaces.find(localEp);
   if (it != m_mcastFaces.end()) {
     if (it->second->getRemoteUri() == FaceUri(mcastEp))
       return it->second;
     else
       NDN_THROW(Error("Cannot create UDP multicast face on " + boost::lexical_cast<std::string>(localEp) +
                       ", endpoint already allocated to a different UDP multicast face"));
   }

   // check if the local endpoint is already used by a unicast channel
   if (m_channels.find(localEp) != m_channels.end()) {
     NDN_THROW(Error("Cannot create UDP multicast face on " + boost::lexical_cast<std::string>(localEp) +
                     ", endpoint already allocated to a UDP channel"));
   }

   ip::udp::socket rxSock(getGlobalIoService());
   MulticastUdpTransport::openRxSocket(rxSock, mcastEp, localAddress, netif);
   ip::udp::socket txSock(getGlobalIoService());
   MulticastUdpTransport::openTxSocket(txSock, udp::Endpoint(localAddress, 0), netif);

   GenericLinkService::Options options;
   options.allowCongestionMarking = m_wantCongestionMarking;
   auto linkService = make_unique<GenericLinkService>(options);
   auto transport = make_unique<MulticastUdpTransport>(mcastEp, std::move(rxSock), std::move(txSock),
                                                       m_mcastConfig.linkType);
   auto face = make_shared<Face>(std::move(linkService), std::move(transport));

   m_mcastFaces[localEp] = face;
   connectFaceClosedSignal(*face, [this, localEp] { m_mcastFaces.erase(localEp); });

   // Associate with the first available channel of the same protocol family
   auto channelIt = std::find_if(m_channels.begin(), m_channels.end(),
                                 [isV4 = localEp.address().is_v4()] (const auto& it) {
                                   return it.first.address().is_v4() == isV4;
                                 });
   face->setChannel(channelIt != m_channels.end() ? channelIt->second : nullptr);

   return face;
 }

 static std::optional<ip::address>
 pickAddress(const net::NetworkInterface& netif, net::AddressFamily af)
 {
   for (const auto& na : netif.getNetworkAddresses()) {
     if (na.getFamily() == af &&
         (na.getScope() == net::AddressScope::LINK || na.getScope() == net::AddressScope::GLOBAL)) {
       return na.getIp();
     }
   }
   return std::nullopt;
 }

 std::vector<shared_ptr<Face>>
 UdpFactory::applyMcastConfigToNetif(const shared_ptr<const net::NetworkInterface>& netif)
 {
   BOOST_ASSERT(netif != nullptr);

   if (!m_mcastConfig.isEnabled) {
     return {};
   }

   if (!netif->isUp()) {
     NFD_LOG_DEBUG("Not creating multicast faces on " << netif->getName() << ": netif is down");
     return {};
   }

   if (netif->isLoopback()) {
     NFD_LOG_DEBUG("Not creating multicast faces on " << netif->getName() << ": netif is loopback");
     return {};
   }

   if (!netif->canMulticast()) {
     NFD_LOG_DEBUG("Not creating multicast faces on " << netif->getName() << ": netif cannot multicast");
     return {};
   }

   if (!m_mcastConfig.netifPredicate(*netif)) {
     NFD_LOG_DEBUG("Not creating multicast faces on " << netif->getName() << ": rejected by whitelist/blacklist");
     return {};
   }

   std::vector<ip::address> addrs;
   for (auto af : {net::AddressFamily::V4, net::AddressFamily::V6}) {
     auto addr = pickAddress(*netif, af);
     if (addr)
       addrs.push_back(*addr);
   }

   if (addrs.empty()) {
     NFD_LOG_DEBUG("Not creating multicast faces on " << netif->getName() << ": no viable IP address");
     // keep an eye on new addresses
     m_netifConns[netif->getIndex()].addrAddConn =
       netif->onAddressAdded.connect([=] (auto&&...) { this->applyMcastConfigToNetif(netif); });
     return {};
   }

   NFD_LOG_DEBUG("Creating multicast faces on " << netif->getName());

   std::vector<shared_ptr<Face>> faces;
   for (const auto& addr : addrs) {
     auto face = this->createMulticastFace(netif, addr,
                                           addr.is_v4() ? m_mcastConfig.group : m_mcastConfig.groupV6);
     if (face->getId() == INVALID_FACEID) {
       // new face: register with forwarding
       this->addFace(face);
     }
     faces.push_back(std::move(face));
   }

   return faces;
 }

 void
 UdpFactory::applyMcastConfig(const FaceSystem::ConfigContext&)
 {
   // collect old faces
   std::set<shared_ptr<Face>> facesToClose;
   boost::copy(m_mcastFaces | boost::adaptors::map_values,
               std::inserter(facesToClose, facesToClose.end()));

   // create faces if requested by config
   for (const auto& netif : netmon->listNetworkInterfaces()) {
     auto facesToKeep = this->applyMcastConfigToNetif(netif);
     for (const auto& face : facesToKeep) {
       // don't destroy face
       facesToClose.erase(face);
     }
   }

   // destroy old faces that are not needed in new configuration
   for (const auto& face : facesToClose) {
     face->close();
   }
 }

 } // namespace face
 } // namespace nfd
	/* -- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -- */
	/*
	* Copyright (c) 2014-2022, Regents of the University of California,
	* Arizona Board of Regents,
	* Colorado State University,
	* University Pierre & Marie Curie, Sorbonne University,
	* Washington University in St. Louis,
	* Beijing Institute of Technology,
	* The University of Memphis.
	*
	* This file is part of NFD (Named Data Networking Forwarding Daemon).
	* See AUTHORS.md for complete list of NFD authors and contributors.
	*
	* NFD is free software: you can redistribute it and/or modify it under the terms
	* of the GNU General Public License as published by the Free Software Foundation,
	* either version 3 of the License, or (at your option) any later version.
	*
	* NFD 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 General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License along with
	* NFD, e.g., in COPYING.md file. If not, see <http://www.gnu.org/licenses/>.
	*/

	#include "udp-factory.hpp"
	#include "generic-link-service.hpp"
	#include "multicast-udp-transport.hpp"
	#include "common/global.hpp"

	#include <boost/range/adaptor/map.hpp>
	#include <boost/range/algorithm/copy.hpp>

	namespace nfd {
	namespace face {

	namespace ip = boost::asio::ip;
	namespace net = ndn::net;

	NFD_LOG_INIT(UdpFactory);
	NFD_REGISTER_PROTOCOL_FACTORY(UdpFactory);

	const std::string&
	UdpFactory::getId() noexcept
	{
	static std::string id("udp");
	return id;
	}

	UdpFactory::UdpFactory(const CtorParams& params)
	: ProtocolFactory(params)
	{
	m_netifAddConn = netmon->onInterfaceAdded.connect([this] (const auto& netif) {
	this->applyMcastConfigToNetif(netif);
	});
	}

	void
	UdpFactory::doProcessConfig(OptionalConfigSection configSection,
	FaceSystem::ConfigContext& context)
	{
	// udp
	// {
	// listen yes
	// port 6363
	// enable_v4 yes
	// enable_v6 yes
	// idle_timeout 600
	// unicast_mtu 8800
	// mcast yes
	// mcast_group 224.0.23.170
	// mcast_port 56363
	// mcast_group_v6 ff02::1234
	// mcast_port_v6 56363
	// mcast_ad_hoc no
	// whitelist
	// {
	// *
	// }
	// blacklist
	// {
	// }
	// }

	m_wantCongestionMarking = context.generalConfig.wantCongestionMarking;

	bool wantListen = true;
	uint16_t port = 6363;
	bool enableV4 = false;
	bool enableV6 = false;
	uint32_t idleTimeout = 600;
	size_t unicastMtu = ndn::MAX_NDN_PACKET_SIZE;
	MulticastConfig mcastConfig;

	if (configSection) {
	// These default to 'yes' but only if face_system.udp section is present
	enableV4 = enableV6 = mcastConfig.isEnabled = true;

	for (const auto& pair : *configSection) {
	const std::string& key = pair.first;
	const ConfigSection& value = pair.second;

	if (key == "listen") {
	wantListen = ConfigFile::parseYesNo(pair, "face_system.udp");
	}
	else if (key == "port") {
	port = ConfigFile::parseNumber<uint16_t>(pair, "face_system.udp");
	}
	else if (key == "enable_v4") {
	enableV4 = ConfigFile::parseYesNo(pair, "face_system.udp");
	}
	else if (key == "enable_v6") {
	enableV6 = ConfigFile::parseYesNo(pair, "face_system.udp");
	}
	else if (key == "idle_timeout") {
	idleTimeout = ConfigFile::parseNumber<uint32_t>(pair, "face_system.udp");
	}
	else if (key == "unicast_mtu") {
	unicastMtu = ConfigFile::parseNumber<size_t>(pair, "face_system.udp");
	ConfigFile::checkRange(unicastMtu, static_cast<size_t>(MIN_MTU), ndn::MAX_NDN_PACKET_SIZE,
	"unicast_mtu", "face_system.udp");
	}
	else if (key == "keep_alive_interval") {
	// ignored
	}
	else if (key == "mcast") {
	mcastConfig.isEnabled = ConfigFile::parseYesNo(pair, "face_system.udp");
	}
	else if (key == "mcast_group") {
	const std::string& valueStr = value.get_value<std::string>();
	boost::system::error_code ec;
	mcastConfig.group.address(ip::address_v4::from_string(valueStr, ec));
	if (ec) {
	NDN_THROW(ConfigFile::Error("face_system.udp.mcast_group: '" +
	valueStr + "' cannot be parsed as an IPv4 address"));
	}
	else if (!mcastConfig.group.address().is_multicast()) {
	NDN_THROW(ConfigFile::Error("face_system.udp.mcast_group: '" +
	valueStr + "' is not a multicast address"));
	}
	}
	else if (key == "mcast_port") {
	mcastConfig.group.port(ConfigFile::parseNumber<uint16_t>(pair, "face_system.udp"));
	}
	else if (key == "mcast_group_v6") {
	const std::string& valueStr = value.get_value<std::string>();
	boost::system::error_code ec;
	mcastConfig.groupV6.address(ip::address_v6::from_string(valueStr, ec));
	if (ec) {
	NDN_THROW(ConfigFile::Error("face_system.udp.mcast_group_v6: '" +
	valueStr + "' cannot be parsed as an IPv6 address"));
	}
	else if (!mcastConfig.groupV6.address().is_multicast()) {
	NDN_THROW(ConfigFile::Error("face_system.udp.mcast_group_v6: '" +
	valueStr + "' is not a multicast address"));
	}
	}
	else if (key == "mcast_port_v6") {
	mcastConfig.groupV6.port(ConfigFile::parseNumber<uint16_t>(pair, "face_system.udp"));
	}
	else if (key == "mcast_ad_hoc") {
	bool wantAdHoc = ConfigFile::parseYesNo(pair, "face_system.udp");
	mcastConfig.linkType = wantAdHoc ? ndn::nfd::LINK_TYPE_AD_HOC : ndn::nfd::LINK_TYPE_MULTI_ACCESS;
	}
	else if (key == "whitelist") {
	mcastConfig.netifPredicate.parseWhitelist(value);
	}
	else if (key == "blacklist") {
	mcastConfig.netifPredicate.parseBlacklist(value);
	}
	else {
	NDN_THROW(ConfigFile::Error("Unrecognized option face_system.udp." + key));
	}
	}

	if (!enableV4 && !enableV6 && !mcastConfig.isEnabled) {
	NDN_THROW(ConfigFile::Error(
	"IPv4 and IPv6 UDP channels and UDP multicast have been disabled. "
	"Remove face_system.udp section to disable UDP channels or enable at least one of them."));
	}
	}

	if (context.isDryRun) {
	return;
	}

	m_defaultUnicastMtu = unicastMtu;

	if (enableV4) {
	udp::Endpoint endpoint(ip::udp::v4(), port);
	shared_ptr<UdpChannel> v4Channel = this->createChannel(endpoint, time::seconds(idleTimeout));
	if (wantListen && !v4Channel->isListening()) {
	v4Channel->listen(this->addFace, nullptr);
	}
	providedSchemes.insert("udp");
	providedSchemes.insert("udp4");
	}
	else if (providedSchemes.count("udp4") > 0) {
	NFD_LOG_WARN("Cannot close udp4 channel after its creation");
	}

	if (enableV6) {
	udp::Endpoint endpoint(ip::udp::v6(), port);
	shared_ptr<UdpChannel> v6Channel = this->createChannel(endpoint, time::seconds(idleTimeout));
	if (wantListen && !v6Channel->isListening()) {
	v6Channel->listen(this->addFace, nullptr);
	}
	providedSchemes.insert("udp");
	providedSchemes.insert("udp6");
	}
	else if (providedSchemes.count("udp6") > 0) {
	NFD_LOG_WARN("Cannot close udp6 channel after its creation");
	}

	if (m_mcastConfig.isEnabled != mcastConfig.isEnabled) {
	if (mcastConfig.isEnabled) {
	NFD_LOG_INFO("enabling multicast on " << mcastConfig.group);
	NFD_LOG_INFO("enabling multicast on " << mcastConfig.groupV6);
	}
	else {
	NFD_LOG_INFO("disabling multicast");
	}
	}
	else if (mcastConfig.isEnabled) {
	if (m_mcastConfig.linkType != mcastConfig.linkType && !m_mcastFaces.empty()) {
	NFD_LOG_WARN("Cannot change ad hoc setting on existing faces");
	}
	if (m_mcastConfig.group != mcastConfig.group) {
	NFD_LOG_INFO("changing IPv4 multicast group from " << m_mcastConfig.group <<
	" to " << mcastConfig.group);
	}
	if (m_mcastConfig.groupV6 != mcastConfig.groupV6) {
	NFD_LOG_INFO("changing IPv6 multicast group from " << m_mcastConfig.groupV6 <<
	" to " << mcastConfig.groupV6);
	}
	if (m_mcastConfig.netifPredicate != mcastConfig.netifPredicate) {
	NFD_LOG_INFO("changing whitelist/blacklist");
	}
	}

	// Even if there's no configuration change, we still need to re-apply configuration because
	// netifs may have changed.
	m_mcastConfig = mcastConfig;
	this->applyMcastConfig(context);
	}

	void
	UdpFactory::doCreateFace(const CreateFaceRequest& req,
	const FaceCreatedCallback& onCreated,
	const FaceCreationFailedCallback& onFailure)
	{
	if (req.localUri) {
	NFD_LOG_TRACE("Cannot create unicast UDP face with LocalUri");
	onFailure(406, "Unicast UDP faces cannot be created with a LocalUri");
	return;
	}

	if (req.params.persistency == ndn::nfd::FACE_PERSISTENCY_ON_DEMAND) {
	NFD_LOG_TRACE("createFace does not support FACE_PERSISTENCY_ON_DEMAND");
	onFailure(406, "Outgoing UDP faces do not support on-demand persistency");
	return;
	}

	udp::Endpoint endpoint(ip::address::from_string(req.remoteUri.getHost()),
	boost::lexical_cast<uint16_t>(req.remoteUri.getPort()));

	if (endpoint.address().is_multicast()) {
	NFD_LOG_TRACE("createFace does not support multicast faces");
	onFailure(406, "Cannot create multicast UDP faces");
	return;
	}

	if (req.params.wantLocalFields) {
	// UDP faces are never local
	NFD_LOG_TRACE("createFace cannot create non-local face with local fields enabled");
	onFailure(406, "Local fields can only be enabled on faces with local scope");
	return;
	}

	if (req.params.mtu && *req.params.mtu < MIN_MTU) {
	// The specified MTU must be greater than the minimum possible
	NFD_LOG_TRACE("createFace: override MTU cannot be less than " << MIN_MTU);
	onFailure(406, "Override MTU cannot be less than " + to_string(MIN_MTU));
	return;
	}

	// very simple logic for now
	for (const auto& i : m_channels) {
	if ((i.first.address().is_v4() && endpoint.address().is_v4()) \|\|
	(i.first.address().is_v6() && endpoint.address().is_v6())) {
	i.second->connect(endpoint, req.params, onCreated, onFailure);
	return;
	}
	}

	NFD_LOG_TRACE("No channels available to connect to " << endpoint);
	onFailure(504, "No channels available to connect");
	}

	shared_ptr<UdpChannel>
	UdpFactory::createChannel(const udp::Endpoint& localEndpoint,
	time::nanoseconds idleTimeout)
	{
	auto it = m_channels.find(localEndpoint);
	if (it != m_channels.end())
	return it->second;

	// check if the endpoint is already used by a multicast face
	if (m_mcastFaces.find(localEndpoint) != m_mcastFaces.end()) {
	NDN_THROW(Error("Cannot create UDP channel on " + boost::lexical_cast<std::string>(localEndpoint) +
	", endpoint already allocated to a UDP multicast face"));
	}

	auto channel = std::make_shared<UdpChannel>(localEndpoint, idleTimeout,
	m_wantCongestionMarking, m_defaultUnicastMtu);
	m_channels[localEndpoint] = channel;
	return channel;
	}

	std::vector<shared_ptr<const Channel>>
	UdpFactory::doGetChannels() const
	{
	return getChannelsFromMap(m_channels);
	}

	shared_ptr<Face>
	UdpFactory::createMulticastFace(const shared_ptr<const net::NetworkInterface>& netif,
	const ip::address& localAddress,
	const udp::Endpoint& multicastEndpoint)
	{
	BOOST_ASSERT(multicastEndpoint.address().is_multicast());

	udp::Endpoint localEp(localAddress, multicastEndpoint.port());
	BOOST_ASSERT(localEp.protocol() == multicastEndpoint.protocol());

	auto mcastEp = multicastEndpoint;
	if (mcastEp.address().is_v6()) {
	// in IPv6, a scope id on the multicast address is always required
	auto mcastAddress = mcastEp.address().to_v6();
	mcastAddress.scope_id(netif->getIndex());
	mcastEp.address(mcastAddress);
	}

	// check if the local endpoint is already used by another multicast face
	auto it = m_mcastFaces.find(localEp);
	if (it != m_mcastFaces.end()) {
	if (it->second->getRemoteUri() == FaceUri(mcastEp))
	return it->second;
	else
	NDN_THROW(Error("Cannot create UDP multicast face on " + boost::lexical_cast<std::string>(localEp) +
	", endpoint already allocated to a different UDP multicast face"));
	}

	// check if the local endpoint is already used by a unicast channel
	if (m_channels.find(localEp) != m_channels.end()) {
	NDN_THROW(Error("Cannot create UDP multicast face on " + boost::lexical_cast<std::string>(localEp) +
	", endpoint already allocated to a UDP channel"));
	}

	ip::udp::socket rxSock(getGlobalIoService());
	MulticastUdpTransport::openRxSocket(rxSock, mcastEp, localAddress, netif);
	ip::udp::socket txSock(getGlobalIoService());
	MulticastUdpTransport::openTxSocket(txSock, udp::Endpoint(localAddress, 0), netif);

	GenericLinkService::Options options;
	options.allowCongestionMarking = m_wantCongestionMarking;
	auto linkService = make_unique<GenericLinkService>(options);
	auto transport = make_unique<MulticastUdpTransport>(mcastEp, std::move(rxSock), std::move(txSock),
	m_mcastConfig.linkType);
	auto face = make_shared<Face>(std::move(linkService), std::move(transport));

	m_mcastFaces[localEp] = face;
	connectFaceClosedSignal(*face, [this, localEp] { m_mcastFaces.erase(localEp); });

	// Associate with the first available channel of the same protocol family
	auto channelIt = std::find_if(m_channels.begin(), m_channels.end(),
	[isV4 = localEp.address().is_v4()] (const auto& it) {
	return it.first.address().is_v4() == isV4;
	});
	face->setChannel(channelIt != m_channels.end() ? channelIt->second : nullptr);

	return face;
	}

	static std::optional<ip::address>
	pickAddress(const net::NetworkInterface& netif, net::AddressFamily af)
	{
	for (const auto& na : netif.getNetworkAddresses()) {
	if (na.getFamily() == af &&
	(na.getScope() == net::AddressScope::LINK \|\| na.getScope() == net::AddressScope::GLOBAL)) {
	return na.getIp();
	}
	}
	return std::nullopt;
	}

	std::vector<shared_ptr<Face>>
	UdpFactory::applyMcastConfigToNetif(const shared_ptr<const net::NetworkInterface>& netif)
	{
	BOOST_ASSERT(netif != nullptr);

	if (!m_mcastConfig.isEnabled) {
	return {};
	}

	if (!netif->isUp()) {
	NFD_LOG_DEBUG("Not creating multicast faces on " << netif->getName() << ": netif is down");
	return {};
	}

	if (netif->isLoopback()) {
	NFD_LOG_DEBUG("Not creating multicast faces on " << netif->getName() << ": netif is loopback");
	return {};
	}

	if (!netif->canMulticast()) {
	NFD_LOG_DEBUG("Not creating multicast faces on " << netif->getName() << ": netif cannot multicast");
	return {};
	}

	if (!m_mcastConfig.netifPredicate(*netif)) {
	NFD_LOG_DEBUG("Not creating multicast faces on " << netif->getName() << ": rejected by whitelist/blacklist");
	return {};
	}

	std::vector<ip::address> addrs;
	for (auto af : {net::AddressFamily::V4, net::AddressFamily::V6}) {
	auto addr = pickAddress(*netif, af);
	if (addr)
	addrs.push_back(*addr);
	}

	if (addrs.empty()) {
	NFD_LOG_DEBUG("Not creating multicast faces on " << netif->getName() << ": no viable IP address");
	// keep an eye on new addresses
	m_netifConns[netif->getIndex()].addrAddConn =
	netif->onAddressAdded.connect([=] (auto&&...) { this->applyMcastConfigToNetif(netif); });
	return {};
	}

	NFD_LOG_DEBUG("Creating multicast faces on " << netif->getName());

	std::vector<shared_ptr<Face>> faces;
	for (const auto& addr : addrs) {
	auto face = this->createMulticastFace(netif, addr,
	addr.is_v4() ? m_mcastConfig.group : m_mcastConfig.groupV6);
	if (face->getId() == INVALID_FACEID) {
	// new face: register with forwarding
	this->addFace(face);
	}
	faces.push_back(std::move(face));
	}

	return faces;
	}

	void
	UdpFactory::applyMcastConfig(const FaceSystem::ConfigContext&)
	{
	// collect old faces
	std::set<shared_ptr<Face>> facesToClose;
	boost::copy(m_mcastFaces \| boost::adaptors::map_values,
	std::inserter(facesToClose, facesToClose.end()));

	// create faces if requested by config
	for (const auto& netif : netmon->listNetworkInterfaces()) {
	auto facesToKeep = this->applyMcastConfigToNetif(netif);
	for (const auto& face : facesToKeep) {
	// don't destroy face
	facesToClose.erase(face);
	}
	}

	// destroy old faces that are not needed in new configuration
	for (const auto& face : facesToClose) {
	face->close();
	}
	}

	} // namespace face
	} // namespace nfd