ZeroTierOne/node/IncomingPacket.cpp

/*
 * ZeroTier One - Global Peer to Peer Ethernet
 * Copyright (C) 2011-2014  ZeroTier Networks LLC
 *
 * This program 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.
 *
 * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * --
 *
 * ZeroTier may be used and distributed under the terms of the GPLv3, which
 * are available at: http://www.gnu.org/licenses/gpl-3.0.html
 *
 * If you would like to embed ZeroTier into a commercial application or
 * redistribute it in a modified binary form, please contact ZeroTier Networks
 * LLC. Start here: http://www.zerotier.com/
 */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include "../version.h"

#include "Constants.hpp"
#include "Defaults.hpp"
#include "RuntimeEnvironment.hpp"
#include "IncomingPacket.hpp"
#include "Topology.hpp"
#include "Switch.hpp"
#include "Peer.hpp"
#include "NodeConfig.hpp"
#include "Service.hpp"
#include "SoftwareUpdater.hpp"

namespace ZeroTier {

bool IncomingPacket::tryDecode(const RuntimeEnvironment *RR)
{
	try {
		if ((cipher() == ZT_PROTO_CIPHER_SUITE__C25519_POLY1305_NONE)&&(verb() == Packet::VERB_HELLO)) {
			// Unencrypted HELLOs are handled here since they are used to
			// populate our identity cache in the first place. _doHELLO() is special
			// in that it contains its own authentication logic.
			return _doHELLO(RR);
		}

		SharedPtr<Peer> peer = RR->topology->getPeer(source());
		if (peer) {
			if (!dearmor(peer->key())) {
				TRACE("dropped packet from %s(%s), MAC authentication failed (size: %u)",source().toString().c_str(),_remoteAddress.toString().c_str(),size());
				return true;
			}
			if (!uncompress()) {
				TRACE("dropped packet from %s(%s), compressed data invalid",source().toString().c_str(),_remoteAddress.toString().c_str());
				return true;
			}

			//TRACE("<< %s from %s(%s)",Packet::verbString(verb()),source().toString().c_str(),_remoteAddress.toString().c_str());

			switch(verb()) {
				//case Packet::VERB_NOP:
				default: // ignore unknown verbs, but if they pass auth check they are "received"
					peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),verb(),0,Packet::VERB_NOP,Utils::now());
					return true;
				case Packet::VERB_HELLO:                          return _doHELLO(RR);
				case Packet::VERB_ERROR:                          return _doERROR(RR,peer);
				case Packet::VERB_OK:                             return _doOK(RR,peer);
				case Packet::VERB_WHOIS:                          return _doWHOIS(RR,peer);
				case Packet::VERB_RENDEZVOUS:                     return _doRENDEZVOUS(RR,peer);
				case Packet::VERB_FRAME:                          return _doFRAME(RR,peer);
				case Packet::VERB_EXT_FRAME:                      return _doEXT_FRAME(RR,peer);
				case Packet::VERB_P5_MULTICAST_FRAME:             return _doP5_MULTICAST_FRAME(RR,peer);
				case Packet::VERB_MULTICAST_LIKE:                 return _doMULTICAST_LIKE(RR,peer);
				case Packet::VERB_NETWORK_MEMBERSHIP_CERTIFICATE: return _doNETWORK_MEMBERSHIP_CERTIFICATE(RR,peer);
				case Packet::VERB_NETWORK_CONFIG_REQUEST:         return _doNETWORK_CONFIG_REQUEST(RR,peer);
				case Packet::VERB_NETWORK_CONFIG_REFRESH:         return _doNETWORK_CONFIG_REFRESH(RR,peer);
				case Packet::VERB_MULTICAST_GATHER:               return _doMULTICAST_GATHER(RR,peer);
				case Packet::VERB_MULTICAST_FRAME:                return _doMULTICAST_FRAME(RR,peer);
			}
		} else {
			RR->sw->requestWhois(source());
			return false;
		}
	} catch ( ... ) {
		// Exceptions are more informatively caught in _do...() handlers but
		// this outer try/catch will catch anything else odd.
		TRACE("dropped ??? from %s(%s): unexpected exception in tryDecode()",source().toString().c_str(),_remoteAddress.toString().c_str());
		return true;
	}
}

bool IncomingPacket::_doERROR(const RuntimeEnvironment *RR,const SharedPtr<Peer> &peer)
{
	try {
		Packet::Verb inReVerb = (Packet::Verb)(*this)[ZT_PROTO_VERB_ERROR_IDX_IN_RE_VERB];
		uint64_t inRePacketId = at<uint64_t>(ZT_PROTO_VERB_ERROR_IDX_IN_RE_PACKET_ID);
		Packet::ErrorCode errorCode = (Packet::ErrorCode)(*this)[ZT_PROTO_VERB_ERROR_IDX_ERROR_CODE];

		//TRACE("ERROR %s from %s(%s) in-re %s",Packet::errorString(errorCode),source().toString().c_str(),_remoteAddress.toString().c_str(),Packet::verbString(inReVerb));

		switch(errorCode) {

			case Packet::ERROR_OBJ_NOT_FOUND:
				if (inReVerb == Packet::VERB_WHOIS) {
					if (RR->topology->isSupernode(source()))
						RR->sw->cancelWhoisRequest(Address(field(ZT_PROTO_VERB_ERROR_IDX_PAYLOAD,ZT_ADDRESS_LENGTH),ZT_ADDRESS_LENGTH));
				} else if (inReVerb == Packet::VERB_NETWORK_CONFIG_REQUEST) {
					SharedPtr<Network> network(RR->nc->network(at<uint64_t>(ZT_PROTO_VERB_ERROR_IDX_PAYLOAD)));
					if ((network)&&(network->controller() == source()))
						network->setNotFound();
				}
				break;

			case Packet::ERROR_IDENTITY_COLLISION:
				// TODO: if it comes from a supernode, regenerate a new identity
				// if (RR->topology->isSupernode(source())) {}
				break;

			case Packet::ERROR_NEED_MEMBERSHIP_CERTIFICATE: {
				SharedPtr<Network> network(RR->nc->network(at<uint64_t>(ZT_PROTO_VERB_ERROR_IDX_PAYLOAD)));
				if (network) {
					SharedPtr<NetworkConfig> nconf(network->config2());
					if (nconf) {
						Packet outp(peer->address(),RR->identity.address(),Packet::VERB_NETWORK_MEMBERSHIP_CERTIFICATE);
						nconf->com().serialize(outp);
						outp.armor(peer->key(),true);
						_fromSock->send(_remoteAddress,outp.data(),outp.size());
					}
				}
			}	break;

			case Packet::ERROR_NETWORK_ACCESS_DENIED_: {
				SharedPtr<Network> network(RR->nc->network(at<uint64_t>(ZT_PROTO_VERB_ERROR_IDX_PAYLOAD)));
				if ((network)&&(network->controller() == source()))
					network->setAccessDenied();
			}	break;

			case Packet::ERROR_UNWANTED_MULTICAST: {
				// TODO: unsubscribe
			}	break;

			default: break;
		}

		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_ERROR,inRePacketId,inReVerb,Utils::now());
	} catch (std::exception &ex) {
		TRACE("dropped ERROR from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),ex.what());
	} catch ( ... ) {
		TRACE("dropped ERROR from %s(%s): unexpected exception: (unknown)",source().toString().c_str(),_remoteAddress.toString().c_str());
	}
	return true;
}

bool IncomingPacket::_doHELLO(const RuntimeEnvironment *RR)
{
	try {
		unsigned int protoVersion = (*this)[ZT_PROTO_VERB_HELLO_IDX_PROTOCOL_VERSION];
		unsigned int vMajor = (*this)[ZT_PROTO_VERB_HELLO_IDX_MAJOR_VERSION];
		unsigned int vMinor = (*this)[ZT_PROTO_VERB_HELLO_IDX_MINOR_VERSION];
		unsigned int vRevision = at<uint16_t>(ZT_PROTO_VERB_HELLO_IDX_REVISION);
		uint64_t timestamp = at<uint64_t>(ZT_PROTO_VERB_HELLO_IDX_TIMESTAMP);
		Identity id(*this,ZT_PROTO_VERB_HELLO_IDX_IDENTITY);

		if (protoVersion < ZT_PROTO_VERSION_MIN) {
			TRACE("dropped HELLO from %s(%s): protocol version too old",source().toString().c_str(),_remoteAddress.toString().c_str());
			return true;
		}

		if (!id.locallyValidate()) {
			TRACE("dropped HELLO from %s(%s): identity invalid",source().toString().c_str(),_remoteAddress.toString().c_str());
			return true;
		}

		// Do we already have this peer?
		SharedPtr<Peer> peer(RR->topology->getPeer(id.address()));
		if (peer) {
			// Check to make sure this isn't a colliding identity (different key,
			// but same address). The odds are spectacularly low but it could happen.
			// Could also be a sign of someone doing something nasty.
			if (peer->identity() != id) {
				unsigned char key[ZT_PEER_SECRET_KEY_LENGTH];
				if (RR->identity.agree(id,key,ZT_PEER_SECRET_KEY_LENGTH)) {
					if (dearmor(key)) { // ensure packet is authentic, otherwise drop
						LOG("rejected HELLO from %s(%s): address already claimed",source().toString().c_str(),_remoteAddress.toString().c_str());
						Packet outp(source(),RR->identity.address(),Packet::VERB_ERROR);
						outp.append((unsigned char)Packet::VERB_HELLO);
						outp.append(packetId());
						outp.append((unsigned char)Packet::ERROR_IDENTITY_COLLISION);
						outp.armor(key,true);
						_fromSock->send(_remoteAddress,outp.data(),outp.size());
					} else {
						LOG("rejected HELLO from %s(%s): packet failed authentication",source().toString().c_str(),_remoteAddress.toString().c_str());
					}
				} else {
					LOG("rejected HELLO from %s(%s): key agreement failed",source().toString().c_str(),_remoteAddress.toString().c_str());
				}
				return true;
			} else if (!dearmor(peer->key())) {
				LOG("rejected HELLO from %s(%s): packet failed authentication",source().toString().c_str(),_remoteAddress.toString().c_str());
				return true;
			} // else continue and respond
		} else {
			// If we don't have a peer record on file, check the identity cache (if
			// we have one) to see if we have a cached identity. Then check that for
			// collision before adding a new peer.
			Identity alreadyHaveCachedId(RR->topology->getIdentity(id.address()));
			if ((alreadyHaveCachedId)&&(id != alreadyHaveCachedId)) {
				unsigned char key[ZT_PEER_SECRET_KEY_LENGTH];
				if (RR->identity.agree(id,key,ZT_PEER_SECRET_KEY_LENGTH)) {
					if (dearmor(key)) { // ensure packet is authentic, otherwise drop
						LOG("rejected HELLO from %s(%s): address already claimed",source().toString().c_str(),_remoteAddress.toString().c_str());
						Packet outp(source(),RR->identity.address(),Packet::VERB_ERROR);
						outp.append((unsigned char)Packet::VERB_HELLO);
						outp.append(packetId());
						outp.append((unsigned char)Packet::ERROR_IDENTITY_COLLISION);
						outp.armor(key,true);
						_fromSock->send(_remoteAddress,outp.data(),outp.size());
					} else {
						LOG("rejected HELLO from %s(%s): packet failed authentication",source().toString().c_str(),_remoteAddress.toString().c_str());
					}
				} else {
					LOG("rejected HELLO from %s(%s): key agreement failed",source().toString().c_str(),_remoteAddress.toString().c_str());
				}
				return true;
			} // else continue since identity is already known and matches

			// If this is a new peer, learn it
			SharedPtr<Peer> newPeer(new Peer(RR->identity,id));
			if (!dearmor(newPeer->key())) {
				LOG("rejected HELLO from %s(%s): packet failed authentication",source().toString().c_str(),_remoteAddress.toString().c_str());
				return true;
			}
			peer = RR->topology->addPeer(newPeer);
		}

		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_HELLO,0,Packet::VERB_NOP,Utils::now());
		peer->setRemoteVersion(protoVersion,vMajor,vMinor,vRevision);

		// If a supernode has a version higher than ours, this causes a software
		// update check to run now.
		if ((RR->updater)&&(RR->topology->isSupernode(peer->address())))
			RR->updater->sawRemoteVersion(vMajor,vMinor,vRevision);

		Packet outp(source(),RR->identity.address(),Packet::VERB_OK);
		outp.append((unsigned char)Packet::VERB_HELLO);
		outp.append(packetId());
		outp.append(timestamp);
		outp.append((unsigned char)ZT_PROTO_VERSION);
		outp.append((unsigned char)ZEROTIER_ONE_VERSION_MAJOR);
		outp.append((unsigned char)ZEROTIER_ONE_VERSION_MINOR);
		outp.append((uint16_t)ZEROTIER_ONE_VERSION_REVISION);
		outp.armor(peer->key(),true);
		_fromSock->send(_remoteAddress,outp.data(),outp.size());
	} catch (std::exception &ex) {
		TRACE("dropped HELLO from %s(%s): %s",source().toString().c_str(),_remoteAddress.toString().c_str(),ex.what());
	} catch ( ... ) {
		TRACE("dropped HELLO from %s(%s): unexpected exception",source().toString().c_str(),_remoteAddress.toString().c_str());
	}
	return true;
}

bool IncomingPacket::_doOK(const RuntimeEnvironment *RR,const SharedPtr<Peer> &peer)
{
	try {
		Packet::Verb inReVerb = (Packet::Verb)(*this)[ZT_PROTO_VERB_OK_IDX_IN_RE_VERB];
		uint64_t inRePacketId = at<uint64_t>(ZT_PROTO_VERB_OK_IDX_IN_RE_PACKET_ID);

		//TRACE("%s(%s): OK(%s)",source().toString().c_str(),_remoteAddress.toString().c_str(),Packet::verbString(inReVerb));

		switch(inReVerb) {

			case Packet::VERB_HELLO: {
				unsigned int latency = std::min((unsigned int)(Utils::now() - at<uint64_t>(ZT_PROTO_VERB_HELLO__OK__IDX_TIMESTAMP)),(unsigned int)0xffff);
				unsigned int vProto = (*this)[ZT_PROTO_VERB_HELLO__OK__IDX_PROTOCOL_VERSION];
				unsigned int vMajor = (*this)[ZT_PROTO_VERB_HELLO__OK__IDX_MAJOR_VERSION];
				unsigned int vMinor = (*this)[ZT_PROTO_VERB_HELLO__OK__IDX_MINOR_VERSION];
				unsigned int vRevision = at<uint16_t>(ZT_PROTO_VERB_HELLO__OK__IDX_REVISION);

				if (vProto < ZT_PROTO_VERSION_MIN) {
					TRACE("%s(%s): OK(HELLO) dropped, protocol version too old",source().toString().c_str(),_remoteAddress.toString().c_str());
					return true;
				}

				TRACE("%s(%s): OK(HELLO), version %u.%u.%u, latency %u",source().toString().c_str(),_remoteAddress.toString().c_str(),vMajor,vMinor,vRevision,latency);

				peer->addDirectLatencyMeasurment(latency);
				peer->setRemoteVersion(vProto,vMajor,vMinor,vRevision);

				// If a supernode has a version higher than ours, this causes a software
				// update check to run now. This might bum-rush download.zerotier.com, but
				// it's hosted on S3 so hopefully it can take it. This should cause updates
				// to propagate out very quickly.
				if ((RR->updater)&&(RR->topology->isSupernode(peer->address())))
					RR->updater->sawRemoteVersion(vMajor,vMinor,vRevision);
			}	break;

			case Packet::VERB_WHOIS: {
				// Right now only supernodes are allowed to send OK(WHOIS) to prevent
				// poisoning attacks. Further decentralization will require some other
				// kind of trust mechanism.
				if (RR->topology->isSupernode(source())) {
					Identity id(*this,ZT_PROTO_VERB_WHOIS__OK__IDX_IDENTITY);
					if (id.locallyValidate())
						RR->sw->doAnythingWaitingForPeer(RR->topology->addPeer(SharedPtr<Peer>(new Peer(RR->identity,id))));
				}
			} break;

			case Packet::VERB_NETWORK_CONFIG_REQUEST: {
				SharedPtr<Network> nw(RR->nc->network(at<uint64_t>(ZT_PROTO_VERB_NETWORK_CONFIG_REQUEST__OK__IDX_NETWORK_ID)));
				if ((nw)&&(nw->controller() == source())) {
					// OK(NETWORK_CONFIG_REQUEST) is only accepted from a network's
					// controller.
					unsigned int dictlen = at<uint16_t>(ZT_PROTO_VERB_NETWORK_CONFIG_REQUEST__OK__IDX_DICT_LEN);
					std::string dict((const char *)field(ZT_PROTO_VERB_NETWORK_CONFIG_REQUEST__OK__IDX_DICT,dictlen),dictlen);
					if (dict.length()) {
						nw->setConfiguration(Dictionary(dict));
						TRACE("got network configuration for network %.16llx from %s",(unsigned long long)nw->id(),source().toString().c_str());
					}
				}
			}	break;

			case Packet::VERB_MULTICAST_GATHER: {
				uint64_t nwid = at<uint64_t>(ZT_PROTO_VERB_MULTICAST_GATHER__OK__IDX_NETWORK_ID);
				MulticastGroup mg(MAC(field(ZT_PROTO_VERB_MULTICAST_GATHER__OK__IDX_MAC,6),6),at<uint32_t>(ZT_PROTO_VERB_MULTICAST_GATHER__OK__IDX_ADI));
				TRACE("%s(%s): OK(MULTICAST_GATHER) %.16llx/%s length %u",source().toString().c_str(),_remoteAddress.toString().c_str(),nwid,mg.toString().c_str(),size());
				_parseGatherResults(RR,peer,nwid,mg,ZT_PROTO_VERB_MULTICAST_GATHER__OK__IDX_GATHER_RESULTS);
			}	break;

			case Packet::VERB_MULTICAST_FRAME: {
				unsigned int flags = (*this)[ZT_PROTO_VERB_MULTICAST_FRAME__OK__IDX_FLAGS];
				uint64_t nwid = at<uint64_t>(ZT_PROTO_VERB_MULTICAST_FRAME__OK__IDX_NETWORK_ID);
				MulticastGroup mg(MAC(field(ZT_PROTO_VERB_MULTICAST_FRAME__OK__IDX_MAC,6),6),at<uint32_t>(ZT_PROTO_VERB_MULTICAST_FRAME__OK__IDX_ADI));

				TRACE("%s(%s): OK(MULTICAST_FRAME) %.16llx/%s flags %.2x",source().toString().c_str(),_remoteAddress.toString().c_str(),nwid,mg.toString().c_str(),flags);

				unsigned int offset = 0;

				if ((flags & 0x01) != 0) {
					// OK(MULTICAST_FRAME) includes certificate of membership update
					CertificateOfMembership com;
					offset += com.deserialize(*this,ZT_PROTO_VERB_MULTICAST_FRAME__OK__IDX_PAYLOAD);
					SharedPtr<Network> network(RR->nc->network(nwid));
					if ((network)&&(com.hasRequiredFields()))
						network->addMembershipCertificate(com,false);
				}

				if ((flags & 0x02) != 0) {
					// OK(MULTICAST_FRAME) includes implicit gather results
					_parseGatherResults(RR,peer,nwid,mg,offset + ZT_PROTO_VERB_MULTICAST_FRAME__OK__IDX_PAYLOAD);
				}
			}	break;

			default: break;
		}

		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_OK,inRePacketId,inReVerb,Utils::now());
	} catch (std::exception &ex) {
		TRACE("dropped OK from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),ex.what());
	} catch ( ... ) {
		TRACE("dropped OK from %s(%s): unexpected exception: (unknown)",source().toString().c_str(),_remoteAddress.toString().c_str());
	}
	return true;
}

bool IncomingPacket::_doWHOIS(const RuntimeEnvironment *RR,const SharedPtr<Peer> &peer)
{
	try {
		if (payloadLength() == ZT_ADDRESS_LENGTH) {
			Identity id(RR->topology->getIdentity(Address(payload(),ZT_ADDRESS_LENGTH)));
			if (id) {
				Packet outp(source(),RR->identity.address(),Packet::VERB_OK);
				outp.append((unsigned char)Packet::VERB_WHOIS);
				outp.append(packetId());
				id.serialize(outp,false);
				outp.armor(peer->key(),true);
				_fromSock->send(_remoteAddress,outp.data(),outp.size());
				//TRACE("sent WHOIS response to %s for %s",source().toString().c_str(),Address(payload(),ZT_ADDRESS_LENGTH).toString().c_str());
			} else {
				Packet outp(source(),RR->identity.address(),Packet::VERB_ERROR);
				outp.append((unsigned char)Packet::VERB_WHOIS);
				outp.append(packetId());
				outp.append((unsigned char)Packet::ERROR_OBJ_NOT_FOUND);
				outp.append(payload(),ZT_ADDRESS_LENGTH);
				outp.armor(peer->key(),true);
				_fromSock->send(_remoteAddress,outp.data(),outp.size());
				//TRACE("sent WHOIS ERROR to %s for %s (not found)",source().toString().c_str(),Address(payload(),ZT_ADDRESS_LENGTH).toString().c_str());
			}
		} else {
			TRACE("dropped WHOIS from %s(%s): missing or invalid address",source().toString().c_str(),_remoteAddress.toString().c_str());
		}

		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_WHOIS,0,Packet::VERB_NOP,Utils::now());
	} catch ( ... ) {
		TRACE("dropped WHOIS from %s(%s): unexpected exception",source().toString().c_str(),_remoteAddress.toString().c_str());
	}
	return true;
}

bool IncomingPacket::_doRENDEZVOUS(const RuntimeEnvironment *RR,const SharedPtr<Peer> &peer)
{
	try {
		/*
		 * At the moment, we only obey RENDEZVOUS if it comes from a designated
		 * supernode. If relay offloading is implemented to scale the net, this
		 * will need reconsideration.
		 *
		 * The reason is that RENDEZVOUS could technically be used to cause a
		 * peer to send a weird encrypted UDP packet to an arbitrary IP:port.
		 * The sender of RENDEZVOUS has no control over the content of this
		 * packet, but it's still maybe something we want to not allow just
		 * anyone to order due to possible DDOS or network forensic implications.
		 * So if we diversify relays, we'll need some way of deciding whether the
		 * sender is someone we should trust with a RENDEZVOUS hint.
		 */
		if (RR->topology->isSupernode(source())) {
			Address with(field(ZT_PROTO_VERB_RENDEZVOUS_IDX_ZTADDRESS,ZT_ADDRESS_LENGTH),ZT_ADDRESS_LENGTH);
			SharedPtr<Peer> withPeer(RR->topology->getPeer(with));
			if (withPeer) {
				unsigned int port = at<uint16_t>(ZT_PROTO_VERB_RENDEZVOUS_IDX_PORT);
				unsigned int addrlen = (*this)[ZT_PROTO_VERB_RENDEZVOUS_IDX_ADDRLEN];
				if ((port > 0)&&((addrlen == 4)||(addrlen == 16))) {
					InetAddress atAddr(field(ZT_PROTO_VERB_RENDEZVOUS_IDX_ADDRESS,addrlen),addrlen,port);
					TRACE("RENDEZVOUS from %s says %s might be at %s, starting NAT-t",source().toString().c_str(),with.toString().c_str(),atAddr.toString().c_str());
					peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_RENDEZVOUS,0,Packet::VERB_NOP,Utils::now());
					RR->sw->contact(withPeer,atAddr);
				} else {
					TRACE("dropped corrupt RENDEZVOUS from %s(%s) (bad address or port)",source().toString().c_str(),_remoteAddress.toString().c_str());
				}
			} else {
				TRACE("ignored RENDEZVOUS from %s(%s) to meet unknown peer %s",source().toString().c_str(),_remoteAddress.toString().c_str(),with.toString().c_str());
			}
		} else {
			TRACE("ignored RENDEZVOUS from %s(%s): source not supernode",source().toString().c_str(),_remoteAddress.toString().c_str());
		}
	} catch (std::exception &ex) {
		TRACE("dropped RENDEZVOUS from %s(%s): %s",source().toString().c_str(),_remoteAddress.toString().c_str(),ex.what());
	} catch ( ... ) {
		TRACE("dropped RENDEZVOUS from %s(%s): unexpected exception",source().toString().c_str(),_remoteAddress.toString().c_str());
	}
	return true;
}

bool IncomingPacket::_doFRAME(const RuntimeEnvironment *RR,const SharedPtr<Peer> &peer)
{
	try {
		SharedPtr<Network> network(RR->nc->network(at<uint64_t>(ZT_PROTO_VERB_FRAME_IDX_NETWORK_ID)));
		if (network) {
			if (size() > ZT_PROTO_VERB_FRAME_IDX_PAYLOAD) {
				if (!network->isAllowed(peer->address())) {
					TRACE("dropped FRAME from %s(%s): not a member of private network %.16llx",peer->address().toString().c_str(),_remoteAddress.toString().c_str(),(unsigned long long)network->id());
					_sendErrorNeedCertificate(RR,peer,network->id());
					return true;
				}

				unsigned int etherType = at<uint16_t>(ZT_PROTO_VERB_FRAME_IDX_ETHERTYPE);
				if (!network->config()->permitsEtherType(etherType)) {
					TRACE("dropped FRAME from %s(%s): ethertype %.4x not allowed on %.16llx",peer->address().toString().c_str(),_remoteAddress.toString().c_str(),(unsigned int)etherType,(unsigned long long)network->id());
					return true;
				}

				unsigned int payloadLen = size() - ZT_PROTO_VERB_FRAME_IDX_PAYLOAD;
				network->tapPut(MAC(peer->address(),network->id()),network->mac(),etherType,field(ZT_PROTO_VERB_FRAME_IDX_PAYLOAD,payloadLen),payloadLen);
			}

			peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_FRAME,0,Packet::VERB_NOP,Utils::now());
		} else {
			TRACE("dropped FRAME from %s(%s): we are not connected to network %.16llx",source().toString().c_str(),_remoteAddress.toString().c_str(),at<uint64_t>(ZT_PROTO_VERB_FRAME_IDX_NETWORK_ID));
		}
	} catch (std::exception &ex) {
		TRACE("dropped FRAME from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),ex.what());
	} catch ( ... ) {
		TRACE("dropped FRAME from %s(%s): unexpected exception: (unknown)",source().toString().c_str(),_remoteAddress.toString().c_str());
	}
	return true;
}

bool IncomingPacket::_doEXT_FRAME(const RuntimeEnvironment *RR,const SharedPtr<Peer> &peer)
{
	try {
		SharedPtr<Network> network(RR->nc->network(at<uint64_t>(ZT_PROTO_VERB_EXT_FRAME_IDX_NETWORK_ID)));
		if (network) {
			if (size() > ZT_PROTO_VERB_EXT_FRAME_IDX_PAYLOAD) {
				unsigned int flags = (*this)[ZT_PROTO_VERB_EXT_FRAME_IDX_FLAGS];

				unsigned int comLen = 0;
				if ((flags & 0x01) != 0) {
					CertificateOfMembership com;
					comLen = com.deserialize(*this,ZT_PROTO_VERB_EXT_FRAME_IDX_COM);
					if (com.hasRequiredFields())
						network->addMembershipCertificate(com,false);
				}

				if (!network->isAllowed(peer->address())) {
					TRACE("dropped EXT_FRAME from %s(%s): not a member of private network %.16llx",peer->address().toString().c_str(),_remoteAddress.toString().c_str(),network->id());
					_sendErrorNeedCertificate(RR,peer,network->id());
					return true;
				}

				// Everything after flags must be adjusted based on the length
				// of the certificate, if there was one...

				unsigned int etherType = at<uint16_t>(comLen + ZT_PROTO_VERB_EXT_FRAME_IDX_ETHERTYPE);
				if (!network->config()->permitsEtherType(etherType)) {
					TRACE("dropped EXT_FRAME from %s(%s): ethertype %.4x not allowed on network %.16llx",peer->address().toString().c_str(),_remoteAddress.toString().c_str(),(unsigned int)etherType,(unsigned long long)network->id());
					return true;
				}

				const MAC to(field(comLen + ZT_PROTO_VERB_EXT_FRAME_IDX_TO,ZT_PROTO_VERB_EXT_FRAME_LEN_TO),ZT_PROTO_VERB_EXT_FRAME_LEN_TO);
				const MAC from(field(comLen + ZT_PROTO_VERB_EXT_FRAME_IDX_FROM,ZT_PROTO_VERB_EXT_FRAME_LEN_FROM),ZT_PROTO_VERB_EXT_FRAME_LEN_FROM);

				if (to.isMulticast()) {
					TRACE("dropped EXT_FRAME from %s@%s(%s) to %s: destination is multicast, must use MULTICAST_FRAME",from.toString().c_str(),peer->address().toString().c_str(),_remoteAddress.toString().c_str(),to.toString().c_str());
					return true;
				}

				if ((!from)||(from.isMulticast())||(from == network->mac())) {
					TRACE("dropped EXT_FRAME from %s@%s(%s) to %s: invalid source MAC",from.toString().c_str(),peer->address().toString().c_str(),_remoteAddress.toString().c_str(),to.toString().c_str());
					return true;
				}

				if (from != MAC(peer->address(),network->id())) {
					if (network->permitsBridging(peer->address())) {
						network->learnBridgeRoute(from,peer->address());
					} else {
						TRACE("dropped EXT_FRAME from %s@%s(%s) to %s: sender not allowed to bridge into %.16llx",from.toString().c_str(),peer->address().toString().c_str(),_remoteAddress.toString().c_str(),to.toString().c_str(),network->id());
						return true;
					}
				}

				if (to != network->mac()) {
					if (!network->permitsBridging(RR->identity.address())) {
						TRACE("dropped EXT_FRAME from %s@%s(%s) to %s: I cannot bridge to %.16llx or bridging disabled on network",from.toString().c_str(),peer->address().toString().c_str(),_remoteAddress.toString().c_str(),to.toString().c_str(),network->id());
						return true;
					}
				}

				unsigned int payloadLen = size() - (comLen + ZT_PROTO_VERB_EXT_FRAME_IDX_PAYLOAD);
				if (payloadLen)
					network->tapPut(from,to,etherType,field(comLen + ZT_PROTO_VERB_EXT_FRAME_IDX_PAYLOAD,payloadLen),payloadLen);
			}

			peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_EXT_FRAME,0,Packet::VERB_NOP,Utils::now());
		} else {
			TRACE("dropped EXT_FRAME from %s(%s): we are not connected to network %.16llx",source().toString().c_str(),_remoteAddress.toString().c_str(),at<uint64_t>(ZT_PROTO_VERB_FRAME_IDX_NETWORK_ID));
		}
	} catch (std::exception &ex) {
		TRACE("dropped EXT_FRAME from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),ex.what());
	} catch ( ... ) {
		TRACE("dropped EXT_FRAME from %s(%s): unexpected exception: (unknown)",source().toString().c_str(),_remoteAddress.toString().c_str());
	}
	return true;
}

bool IncomingPacket::_doP5_MULTICAST_FRAME(const RuntimeEnvironment *RR,const SharedPtr<Peer> &peer)
{
	/* This handles the old deprecated "P5" multicast frame, and will
	 * go away once there are no longer nodes using this on the network.
	 * We handle these old nodes by accepting these as simple multicasts
	 * and if we are a supernode performing individual relaying of them
	 * to all older nodes that expect them. This won't be too expensive
	 * though since there aren't likely to be many older nodes left after
	 * we do a software update. */

	// Quick and dirty dedup -- this is all condemned code in any case
	static uint64_t p5MulticastDedupBuffer[1024];
	static unsigned long p5MulticastDedupBufferPtr = 0;
	static Mutex p5MulticastDedupBuffer_m;

	try {
		Address origin(Address(field(ZT_PROTO_VERB_P5_MULTICAST_FRAME_IDX_ORIGIN,ZT_PROTO_VERB_P5_MULTICAST_FRAME_LEN_ORIGIN),ZT_ADDRESS_LENGTH));
		const unsigned int flags = (*this)[ZT_PROTO_VERB_P5_MULTICAST_FRAME_IDX_FLAGS];
		const uint64_t nwid = at<uint64_t>(ZT_PROTO_VERB_P5_MULTICAST_FRAME_IDX_NETWORK_ID);
		const uint64_t guid = at<uint64_t>(ZT_PROTO_VERB_P5_MULTICAST_FRAME_IDX_GUID);
		const MAC sourceMac(field(ZT_PROTO_VERB_P5_MULTICAST_FRAME_IDX_SOURCE_MAC,ZT_PROTO_VERB_P5_MULTICAST_FRAME_LEN_SOURCE_MAC),ZT_PROTO_VERB_P5_MULTICAST_FRAME_LEN_SOURCE_MAC);
		const MulticastGroup dest(MAC(field(ZT_PROTO_VERB_P5_MULTICAST_FRAME_IDX_DEST_MAC,ZT_PROTO_VERB_P5_MULTICAST_FRAME_LEN_DEST_MAC),ZT_PROTO_VERB_P5_MULTICAST_FRAME_LEN_DEST_MAC),at<uint32_t>(ZT_PROTO_VERB_P5_MULTICAST_FRAME_IDX_DEST_ADI));
		const unsigned int etherType = at<uint16_t>(ZT_PROTO_VERB_P5_MULTICAST_FRAME_IDX_ETHERTYPE);
		const unsigned int frameLen = at<uint16_t>(ZT_PROTO_VERB_P5_MULTICAST_FRAME_IDX_FRAME_LEN);
		const unsigned char *const frame = field(ZT_PROTO_VERB_P5_MULTICAST_FRAME_IDX_FRAME,frameLen);
		const unsigned int signatureLen = at<uint16_t>(ZT_PROTO_VERB_P5_MULTICAST_FRAME_IDX_FRAME + frameLen);

		{
			Mutex::Lock _l(p5MulticastDedupBuffer_m);
			if (!p5MulticastDedupBufferPtr) {
				memset(p5MulticastDedupBuffer,0,sizeof(p5MulticastDedupBuffer));
			} else {
				for(unsigned int i=0;i<1024;++i) {
					if (p5MulticastDedupBuffer[i] == guid)
						return true;
				}
			}
			p5MulticastDedupBuffer[p5MulticastDedupBufferPtr++ % 1024] = guid;
		}

		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_P5_MULTICAST_FRAME,0,Packet::VERB_NOP,Utils::now());

		if (RR->topology->amSupernode()) {
			std::vector<Address> legacyPeers(RR->mc->getLegacySubscribers(nwid,dest));

			setAt(ZT_PROTO_VERB_P5_MULTICAST_FRAME_IDX_PROPAGATION_DEPTH,(uint16_t)0xffff);
			setSource(RR->identity.address());
			compress();

			unsigned int count = 0;
			for(std::vector<Address>::iterator lp(legacyPeers.begin());lp!=legacyPeers.end();++lp) {
				if ((*lp != origin)&&(*lp != source())) {
					newInitializationVector();
					setDestination(*lp);
					RR->sw->send(*this,true);
					if (++count >= 128) // harded-coded sanity limit for these legacy nodes
						break;
				}
			}

			return true;
		} else {
			SharedPtr<Network> network(RR->nc->network(nwid)); // will be NULL if not a member
			if (network) {
				if ((flags & ZT_PROTO_VERB_P5_MULTICAST_FRAME_FLAGS_HAS_MEMBERSHIP_CERTIFICATE)) {
					CertificateOfMembership com;
					com.deserialize(*this,ZT_PROTO_VERB_MULTICAST_FRAME_IDX_FRAME + frameLen + 2 + signatureLen);
					if (com.hasRequiredFields())
						network->addMembershipCertificate(com,false);
				}

				if (!network->isAllowed(origin)) {
					_sendErrorNeedCertificate(RR,peer,network->id());
					return true;
				}

				if (frameLen) {
					if (!dest.mac().isMulticast())
						return true;
					if ((!sourceMac)||(sourceMac.isMulticast())||(sourceMac == network->mac()))
						return true;
					if (sourceMac != MAC(origin,network->id())) {
						if (network->permitsBridging(origin)) {
							network->learnBridgeRoute(sourceMac,origin);
						} else return true;
					}

					network->tapPut(sourceMac,dest.mac(),etherType,frame,frameLen);
				}
			}
		}
	} catch (std::exception &ex) {
		TRACE("dropped P5_MULTICAST_FRAME from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),ex.what());
	} catch ( ... ) {
		TRACE("dropped P5_MULTICAST_FRAME from %s(%s): unexpected exception: (unknown)",source().toString().c_str(),_remoteAddress.toString().c_str());
	}

#if 0 // old code preserved below
	try {
		Address origin(Address(field(ZT_PROTO_VERB_MULTICAST_FRAME_IDX_ORIGIN,ZT_PROTO_VERB_MULTICAST_FRAME_LEN_ORIGIN),ZT_ADDRESS_LENGTH));
		SharedPtr<Peer> originPeer(RR->topology->getPeer(origin));
		if (!originPeer) {
			// We must have the origin's identity in order to authenticate a multicast
			RR->sw->requestWhois(origin);
			_step = DECODE_WAITING_FOR_MULTICAST_FRAME_ORIGINAL_SENDER_LOOKUP; // causes processing to come back here
			return false;
		}

		// These fields in the packet are changed by each forwarder
		unsigned int depth = at<uint16_t>(ZT_PROTO_VERB_MULTICAST_FRAME_IDX_PROPAGATION_DEPTH);
		unsigned char *const fifo = field(ZT_PROTO_VERB_MULTICAST_FRAME_IDX_PROPAGATION_FIFO,ZT_PROTO_VERB_MULTICAST_FRAME_LEN_PROPAGATION_FIFO);
		unsigned char *const bloom = field(ZT_PROTO_VERB_MULTICAST_FRAME_IDX_PROPAGATION_BLOOM,ZT_PROTO_VERB_MULTICAST_FRAME_LEN_PROPAGATION_BLOOM);

		// These fields don't -- they're signed by the original sender
		const unsigned int flags = (*this)[ZT_PROTO_VERB_MULTICAST_FRAME_IDX_FLAGS];
		const uint64_t nwid = at<uint64_t>(ZT_PROTO_VERB_MULTICAST_FRAME_IDX_NETWORK_ID);
		const uint16_t bloomNonce = at<uint16_t>(ZT_PROTO_VERB_MULTICAST_FRAME_IDX_PROPAGATION_BLOOM_NONCE);
		const unsigned int prefixBits = (*this)[ZT_PROTO_VERB_MULTICAST_FRAME_IDX_PROPAGATION_PREFIX_BITS];
		const unsigned int prefix = (*this)[ZT_PROTO_VERB_MULTICAST_FRAME_IDX_PROPAGATION_PREFIX];
		const uint64_t guid = at<uint64_t>(ZT_PROTO_VERB_MULTICAST_FRAME_IDX_GUID);
		const MAC sourceMac(field(ZT_PROTO_VERB_MULTICAST_FRAME_IDX_SOURCE_MAC,ZT_PROTO_VERB_MULTICAST_FRAME_LEN_SOURCE_MAC),ZT_PROTO_VERB_MULTICAST_FRAME_LEN_SOURCE_MAC);
		const MulticastGroup dest(MAC(field(ZT_PROTO_VERB_MULTICAST_FRAME_IDX_DEST_MAC,ZT_PROTO_VERB_MULTICAST_FRAME_LEN_DEST_MAC),ZT_PROTO_VERB_MULTICAST_FRAME_LEN_DEST_MAC),at<uint32_t>(ZT_PROTO_VERB_MULTICAST_FRAME_IDX_DEST_ADI));
		const unsigned int etherType = at<uint16_t>(ZT_PROTO_VERB_MULTICAST_FRAME_IDX_ETHERTYPE);
		const unsigned int frameLen = at<uint16_t>(ZT_PROTO_VERB_MULTICAST_FRAME_IDX_FRAME_LEN);
		const unsigned char *const frame = field(ZT_PROTO_VERB_MULTICAST_FRAME_IDX_FRAME,frameLen);
		const unsigned int signatureLen = at<uint16_t>(ZT_PROTO_VERB_MULTICAST_FRAME_IDX_FRAME + frameLen);
		const unsigned char *const signature = field(ZT_PROTO_VERB_MULTICAST_FRAME_IDX_FRAME + frameLen + 2,signatureLen);

		if ((!sourceMac)||(sourceMac.isMulticast())) {
			TRACE("dropped MULTICAST_FRAME from %s(%s): invalid source MAC %s",source().toString().c_str(),_remoteAddress.toString().c_str(),sourceMac.toString().c_str());
			return true;
		}

		SharedPtr<Network> network(RR->nc->network(nwid));
		SharedPtr<NetworkConfig> nconf;
		if (network)
			nconf = network->config2();

		/* Grab, verify, and learn certificate of network membership if any -- provided we are
		 * a member of this network. Note: we can do this before verification of the actual
		 * packet, since the certificate has its own separate signature. In other words a valid
		 * COM does not imply a valid multicast; they are two separate things. The ability to
		 * include the COM with the multicast is a performance optimization to allow peers to
		 * distribute their COM along with their packets instead of as a separate transaction.
		 * This causes network memberships to start working faster. */
		if (((flags & ZT_PROTO_VERB_MULTICAST_FRAME_FLAGS_HAS_MEMBERSHIP_CERTIFICATE))&&(network)) {
			CertificateOfMembership originCom(*this,ZT_PROTO_VERB_MULTICAST_FRAME_IDX_FRAME + frameLen + 2 + signatureLen);
			Address comSignedBy(originCom.signedBy());
			if ((originCom.networkId() == nwid)&&(comSignedBy == network->controller())) {
				SharedPtr<Peer> comSigningPeer(RR->topology->getPeer(comSignedBy));
				if (!comSigningPeer) {
					// Technically this should never happen because the COM should be signed by
					// the master for this network (in current usage) and we ought to already have
					// that cached. But handle it anyway.
					RR->sw->requestWhois(comSignedBy);
					_step = DECODE_WAITING_FOR_MULTICAST_FRAME_ORIGINAL_SENDER_LOOKUP; // causes processing to come back here
					return false;
				} else if (originCom.verify(comSigningPeer->identity())) {
					// The certificate is valid so learn it. As explained above this does not
					// imply validation of the multicast. That happens later. Look for a call
					// to network->isAllowed().
					network->addMembershipCertificate(originCom);
				} else {
					// Go ahead and drop the multicast though if the COM was invalid, since this
					// obviously signifies a problem.
					LOG("dropped MULTICAST_FRAME from %s(%s): included COM failed authentication check",source().toString().c_str(),_remoteAddress.toString().c_str());
					return true;
				}
			} else {
				// Go ahead and drop the multicast here too, since this also ought never to
				// happen and certainly indicates a problem.
				LOG("dropped MULTICAST_FRAME from %s(%s): included COM is not for this network",source().toString().c_str(),_remoteAddress.toString().c_str());
				return true;
			}
		}

		// Check the multicast frame's signature to verify that its original sender is
		// who it claims to be.
		const unsigned int signedPartLen = (ZT_PROTO_VERB_MULTICAST_FRAME_IDX_FRAME - ZT_PROTO_VERB_MULTICAST_FRAME_IDX__START_OF_SIGNED_PORTION) + frameLen;
		if (!originPeer->identity().verify(field(ZT_PROTO_VERB_MULTICAST_FRAME_IDX__START_OF_SIGNED_PORTION,signedPartLen),signedPartLen,signature,signatureLen)) {
			LOG("dropped MULTICAST_FRAME from %s(%s): failed signature verification, claims to be from %s",source().toString().c_str(),_remoteAddress.toString().c_str(),origin.toString().c_str());
			return true;
		}

		// Security check to prohibit multicasts that are really Ethernet unicasts...
		// otherwise people could do weird things like multicast out a TCP SYN.
		if (!dest.mac().isMulticast()) {
			LOG("dropped MULTICAST_FRAME from %s(%s): %s is not a multicast/broadcast address",source().toString().c_str(),_remoteAddress.toString().c_str(),dest.mac().toString().c_str());
			return true;
		}

		// At this point the frame is basically valid, so we can call it a receive
		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_MULTICAST_FRAME,0,Packet::VERB_NOP,Utils::now());

		// This gets updated later in most cases but start with the global limit.
		unsigned int maxDepth = ZT_MULTICAST_GLOBAL_MAX_DEPTH;

		if ((origin == RR->identity.address())||(RR->mc->deduplicate(nwid,guid))) {
			// This is a boomerang or a duplicate of a multicast we've already seen. Ordinary
			// nodes drop these, while supernodes will keep propagating them since they can
			// act as bridges between sparse multicast networks more than once.
			if (!RR->topology->amSupernode()) {
				TRACE("dropped MULTICAST_FRAME from %s(%s): duplicate",source().toString().c_str(),_remoteAddress.toString().c_str());
				return true;
			}
		} else {
			// If we are actually a member of this network (will just about always
			// be the case unless we're a supernode), check to see if we should
			// inject the packet. This also gives us an opportunity to check things
			// like multicast bandwidth constraints.
			if ((network)&&(nconf)) {
				// Learn real maxDepth from netconf
				maxDepth = std::min((unsigned int)ZT_MULTICAST_GLOBAL_MAX_DEPTH,nconf->multicastDepth());
				if (!maxDepth)
					maxDepth = ZT_MULTICAST_GLOBAL_MAX_DEPTH;

				if (!network->isAllowed(origin)) {
					// Papers, please...
					Packet outp(source(),RR->identity.address(),Packet::VERB_ERROR);
					outp.append((unsigned char)Packet::VERB_MULTICAST_FRAME);
					outp.append(packetId());
					outp.append((unsigned char)Packet::ERROR_NEED_MEMBERSHIP_CERTIFICATE);
					outp.append(nwid);
					outp.armor(peer->key(),true);
					_fromSock->send(_remoteAddress,outp.data(),outp.size());
					TRACE("dropped MULTICAST_FRAME from %s(%s) into %.16llx: sender %s not allowed or we don't have a certificate",source().toString().c_str(),_remoteAddress.toString().c_str(),nwid,origin.toString().c_str());
					return true;
				}

				if (MAC(origin,network->id()) != sourceMac) {
					if (!nconf->permitsBridging(origin)) {
						TRACE("dropped MULTICAST_FRAME from %s(%s) into %.16llx: source mac %s doesn't belong to %s, and bridging is not supported on network",source().toString().c_str(),_remoteAddress.toString().c_str(),nwid,sourceMac.toString().c_str(),origin.toString().c_str());
						return true;
					}
					network->learnBridgeRoute(sourceMac,origin);
				}

				if (!nconf->permitsEtherType(etherType)) {
					TRACE("dropped MULTICAST_FRAME from %s(%s) into %.16llx: ethertype %u is not allowed",source().toString().c_str(),nwid,_remoteAddress.toString().c_str(),etherType);
					return true;
				}

				if (!network->updateAndCheckMulticastBalance(origin,dest,frameLen)) {
					// Rate limits can only be checked by members of this network, but
					// there should be enough of them that over-limit multicasts get
					// their propagation aborted.
					TRACE("dropped MULTICAST_FRAME from %s(%s): rate limits exceeded for sender %s",source().toString().c_str(),_remoteAddress.toString().c_str(),origin.toString().c_str());
					return true;
				}

				network->tapPut(sourceMac,dest.mac(),etherType,frame,frameLen);
			}
		}

		// Depth of 0xffff means "do not forward." Check first since
		// incrementing this would integer overflow a 16-bit int.
		if (depth == 0xffff) {
			TRACE("not forwarding MULTICAST_FRAME from %s(%s): depth == 0xffff (do not forward)",source().toString().c_str(),_remoteAddress.toString().c_str());
			return true;
		}

		// Check if graph traversal depth has exceeded configured maximum.
		if (++depth > maxDepth) {
			TRACE("not forwarding MULTICAST_FRAME from %s(%s): max propagation depth reached",source().toString().c_str(),_remoteAddress.toString().c_str());
			return true;
		}

		// Update depth in packet with new incremented value
		setAt(ZT_PROTO_VERB_MULTICAST_FRAME_IDX_PROPAGATION_DEPTH,(uint16_t)depth);

		// New FIFO with room for one extra, since head will be next hop
		unsigned char newFifo[ZT_PROTO_VERB_MULTICAST_FRAME_LEN_PROPAGATION_FIFO + ZT_ADDRESS_LENGTH];
		unsigned char *newFifoPtr = newFifo;
		unsigned char *const newFifoEnd = newFifo + sizeof(newFifo);

		// Copy old FIFO into new buffer, terminating at first NULL address
		for(unsigned char *f=fifo,*const fifoEnd=(fifo + ZT_PROTO_VERB_MULTICAST_FRAME_LEN_PROPAGATION_FIFO);f!=fifoEnd;) {
			unsigned char *nf = newFifoPtr;
			unsigned char *e = nf + ZT_ADDRESS_LENGTH;
			unsigned char *ftmp = f;
			unsigned char zeroCheckMask = 0;
			while (nf != e)
				zeroCheckMask |= (*(nf++) = *(ftmp++));
			if (zeroCheckMask) {
				f = ftmp;
				newFifoPtr = nf;
			} else break;
		}

		// Add any other next hops we know about to FIFO
		Multicaster::AddToPropagationQueue appender(
			&newFifoPtr,
			newFifoEnd,
			bloom,
			bloomNonce,
			origin,
			prefixBits,
			prefix,
			RR->topology,
			Utils::now());
		if (nconf) {
			for(std::set<Address>::const_iterator ab(nconf->activeBridges().begin());ab!=nconf->activeBridges().end();++ab) {
				if (!appender(*ab))
					break;
			}
		}
		RR->mc->getNextHops(nwid,dest,appender);

		// Zero-terminate new FIFO if not completely full. We pad the remainder with
		// zeroes because this improves data compression ratios.
		while (newFifoPtr != newFifoEnd)
			*(newFifoPtr++) = (unsigned char)0;

		// First element in newFifo[] is next hop
		Address nextHop(newFifo,ZT_ADDRESS_LENGTH);
		if ((!nextHop)&&(!RR->topology->amSupernode())) {
			SharedPtr<Peer> supernode(RR->topology->getBestSupernode(&origin,1,true));
			if (supernode)
				nextHop = supernode->address();
		}
		if ((!nextHop)||(nextHop == RR->identity.address())) { // check against our addr is a sanity check
			//TRACE("not forwarding MULTICAST_FRAME from %s(%s): no next hop",source().toString().c_str(),_remoteAddress.toString().c_str());
			return true;
		}

		// The rest of newFifo[] goes back into the packet
		memcpy(fifo,newFifo + ZT_ADDRESS_LENGTH,ZT_PROTO_VERB_MULTICAST_FRAME_LEN_PROPAGATION_FIFO);

		// Send to next hop, reusing this packet as scratch space
		newInitializationVector();
		setDestination(nextHop);
		setSource(RR->identity.address());
		compress(); // note: bloom filters and empty FIFOs are highly compressable!
		RR->sw->send(*this,true);

		return true;
	} catch (std::exception &ex) {
		TRACE("dropped MULTICAST_FRAME from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),ex.what());
	} catch ( ... ) {
		TRACE("dropped MULTICAST_FRAME from %s(%s): unexpected exception: (unknown)",source().toString().c_str(),_remoteAddress.toString().c_str());
	}
#endif

	return true;
}

bool IncomingPacket::_doMULTICAST_LIKE(const RuntimeEnvironment *RR,const SharedPtr<Peer> &peer)
{
	try {
		uint64_t now = Utils::now();

		// Iterate through 18-byte network,MAC,ADI tuples
		for(unsigned int ptr=ZT_PACKET_IDX_PAYLOAD;ptr<size();ptr+=18)
			RR->mc->add(now,at<uint64_t>(ptr),MulticastGroup(MAC(field(ptr + 8,6),6),at<uint32_t>(ptr + 14)),Address(),peer->address());

		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_MULTICAST_LIKE,0,Packet::VERB_NOP,now);
	} catch (std::exception &ex) {
		TRACE("dropped MULTICAST_LIKE from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),ex.what());
	} catch ( ... ) {
		TRACE("dropped MULTICAST_LIKE from %s(%s): unexpected exception: (unknown)",source().toString().c_str(),_remoteAddress.toString().c_str());
	}
	return true;
}

bool IncomingPacket::_doNETWORK_MEMBERSHIP_CERTIFICATE(const RuntimeEnvironment *RR,const SharedPtr<Peer> &peer)
{
	try {
		CertificateOfMembership com;

		unsigned int ptr = ZT_PACKET_IDX_PAYLOAD;
		while (ptr < size()) {
			ptr += com.deserialize(*this,ptr);
			if (com.hasRequiredFields()) {
				SharedPtr<Network> network(RR->nc->network(com.networkId()));
				if (network)
					network->addMembershipCertificate(com,false);
			}
		}

		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_NETWORK_MEMBERSHIP_CERTIFICATE,0,Packet::VERB_NOP,Utils::now());
	} catch (std::exception &ex) {
		TRACE("dropped NETWORK_MEMBERSHIP_CERTIFICATE from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),ex.what());
	} catch ( ... ) {
		TRACE("dropped NETWORK_MEMBERSHIP_CERTIFICATE from %s(%s): unexpected exception: (unknown)",source().toString().c_str(),_remoteAddress.toString().c_str());
	}
	return true;
}

bool IncomingPacket::_doNETWORK_CONFIG_REQUEST(const RuntimeEnvironment *RR,const SharedPtr<Peer> &peer)
{
	try {
		uint64_t nwid = at<uint64_t>(ZT_PROTO_VERB_NETWORK_CONFIG_REQUEST_IDX_NETWORK_ID);

#ifndef __WINDOWS__
		if (RR->netconfService) {
			char tmp[128];
			unsigned int dictLen = at<uint16_t>(ZT_PROTO_VERB_NETWORK_CONFIG_REQUEST_IDX_DICT_LEN);

			Dictionary request;
			if (dictLen)
				request["meta"] = std::string((const char *)field(ZT_PROTO_VERB_NETWORK_CONFIG_REQUEST_IDX_DICT,dictLen),dictLen);
			request["type"] = "netconf-request";
			request["peerId"] = peer->identity().toString(false);
			Utils::snprintf(tmp,sizeof(tmp),"%.16llx",(unsigned long long)nwid);
			request["nwid"] = tmp;
			Utils::snprintf(tmp,sizeof(tmp),"%.16llx",(unsigned long long)packetId());
			request["requestId"] = tmp;
			if (!hops())
				request["from"] = _remoteAddress.toString();
			//TRACE("to netconf:\n%s",request.toString().c_str());
			RR->netconfService->send(request);
		} else {
#endif // !__WINDOWS__

			// Send unsupported operation if there is no netconf service
			// configured on this node (or if this is a Windows machine,
			// which doesn't support that at all).
			Packet outp(source(),RR->identity.address(),Packet::VERB_ERROR);
			outp.append((unsigned char)Packet::VERB_NETWORK_CONFIG_REQUEST);
			outp.append(packetId());
			outp.append((unsigned char)Packet::ERROR_UNSUPPORTED_OPERATION);
			outp.append(nwid);
			outp.armor(peer->key(),true);
			_fromSock->send(_remoteAddress,outp.data(),outp.size());

#ifndef __WINDOWS__
		}
#endif // !__WINDOWS__

		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_NETWORK_CONFIG_REQUEST,0,Packet::VERB_NOP,Utils::now());
	} catch (std::exception &exc) {
		TRACE("dropped NETWORK_CONFIG_REQUEST from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),exc.what());
	} catch ( ... ) {
		TRACE("dropped NETWORK_CONFIG_REQUEST from %s(%s): unexpected exception: (unknown)",source().toString().c_str(),_remoteAddress.toString().c_str());
	}
	return true;
}

bool IncomingPacket::_doNETWORK_CONFIG_REFRESH(const RuntimeEnvironment *RR,const SharedPtr<Peer> &peer)
{
	try {
		unsigned int ptr = ZT_PACKET_IDX_PAYLOAD;
		while ((ptr + sizeof(uint64_t)) <= size()) {
			uint64_t nwid = at<uint64_t>(ptr); ptr += sizeof(uint64_t);
			SharedPtr<Network> nw(RR->nc->network(nwid));
			if ((nw)&&(source() == nw->controller())) { // only respond to requests from controller
				TRACE("NETWORK_CONFIG_REFRESH from %s, refreshing network %.16llx",source().toString().c_str(),nwid);
				nw->requestConfiguration();
			}
		}
		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_NETWORK_CONFIG_REFRESH,0,Packet::VERB_NOP,Utils::now());
	} catch (std::exception &exc) {
		TRACE("dropped NETWORK_CONFIG_REFRESH from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),exc.what());
	} catch ( ... ) {
		TRACE("dropped NETWORK_CONFIG_REFRESH from %s(%s): unexpected exception: (unknown)",source().toString().c_str(),_remoteAddress.toString().c_str());
	}
	return true;
}

bool IncomingPacket::_doMULTICAST_GATHER(const RuntimeEnvironment *RR,const SharedPtr<Peer> &peer)
{
	try {
		uint64_t nwid = at<uint64_t>(ZT_PROTO_VERB_MULTICAST_GATHER_IDX_NETWORK_ID);
		MulticastGroup mg(MAC(field(ZT_PROTO_VERB_MULTICAST_GATHER_IDX_MAC,6),6),at<uint32_t>(ZT_PROTO_VERB_MULTICAST_GATHER_IDX_ADI));
		unsigned int gatherLimit = at<uint32_t>(ZT_PROTO_VERB_MULTICAST_GATHER_IDX_GATHER_LIMIT);

		//TRACE("<<MC %s(%s) GATHER up to %u in %.16llx/%s",source().toString().c_str(),_remoteAddress.toString().c_str(),gatherLimit,nwid,mg.toString().c_str());

		if (gatherLimit) {
			Packet outp(peer->address(),RR->identity.address(),Packet::VERB_OK);
			outp.append((unsigned char)Packet::VERB_MULTICAST_GATHER);
			outp.append(packetId());
			outp.append(nwid);
			mg.mac().appendTo(outp);
			outp.append((uint32_t)mg.adi());
			if (RR->mc->gather(peer->address(),nwid,mg,outp,gatherLimit)) {
				outp.armor(peer->key(),true);
				_fromSock->send(_remoteAddress,outp.data(),outp.size());
			}
		}

		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_MULTICAST_GATHER,0,Packet::VERB_NOP,Utils::now());
	} catch (std::exception &exc) {
		TRACE("dropped MULTICAST_GATHER from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),exc.what());
	} catch ( ... ) {
		TRACE("dropped MULTICAST_GATHER from %s(%s): unexpected exception: (unknown)",source().toString().c_str(),_remoteAddress.toString().c_str());
	}
	return true;
}

bool IncomingPacket::_doMULTICAST_FRAME(const RuntimeEnvironment *RR,const SharedPtr<Peer> &peer)
{
	try {
		uint64_t nwid = at<uint64_t>(ZT_PROTO_VERB_MULTICAST_FRAME_IDX_NETWORK_ID);
		unsigned int flags = (*this)[ZT_PROTO_VERB_MULTICAST_FRAME_IDX_FLAGS];

		SharedPtr<Network> network(RR->nc->network(nwid)); // will be NULL if not a member
		if (network) {
			// Offset -- size of optional fields added to position of later fields
			unsigned int offset = 0;

			if ((flags & 0x01) != 0) {
				CertificateOfMembership com;
				offset += com.deserialize(*this,ZT_PROTO_VERB_MULTICAST_FRAME_IDX_COM);
				if (com.hasRequiredFields())
					network->addMembershipCertificate(com,false);
			}

			// Check membership after we've read any included COM, since
			// that cert might be what we needed.
			if (!network->isAllowed(peer->address())) {
				TRACE("dropped MULTICAST_FRAME from %s(%s): not a member of private network %.16llx",peer->address().toString().c_str(),_remoteAddress.toString().c_str(),(unsigned long long)network->id());
				_sendErrorNeedCertificate(RR,peer,network->id());
				return true;
			}

			unsigned int gatherLimit = 0;
			if ((flags & 0x02) != 0) {
				gatherLimit = at<uint32_t>(offset + ZT_PROTO_VERB_MULTICAST_FRAME_IDX_GATHER_LIMIT);
				offset += 4;
			}

			MAC from;
			if ((flags & 0x04) != 0) {
				from.setTo(field(offset + ZT_PROTO_VERB_MULTICAST_FRAME_IDX_SOURCE_MAC,6),6);
				offset += 6;
			} else {
				from.fromAddress(peer->address(),nwid);
			}

			MulticastGroup to(MAC(field(offset + ZT_PROTO_VERB_MULTICAST_FRAME_IDX_DEST_MAC,6),6),at<uint32_t>(offset + ZT_PROTO_VERB_MULTICAST_FRAME_IDX_DEST_ADI));
			unsigned int etherType = at<uint16_t>(offset + ZT_PROTO_VERB_MULTICAST_FRAME_IDX_ETHERTYPE);
			unsigned int payloadLen = size() - (offset + ZT_PROTO_VERB_MULTICAST_FRAME_IDX_FRAME);

			//TRACE("<<MC FRAME %.16llx/%s from %s@%s flags %.2x length %u",nwid,to.toString().c_str(),from.toString().c_str(),peer->address().toString().c_str(),flags,payloadLen);

			if ((payloadLen > 0)&&(payloadLen <= ZT_IF_MTU)) {
				if (!to.mac().isMulticast()) {
					TRACE("dropped MULTICAST_FRAME from %s@%s(%s) to %s: destination is unicast, must use FRAME or EXT_FRAME",from.toString().c_str(),peer->address().toString().c_str(),_remoteAddress.toString().c_str(),to.toString().c_str());
					return true;
				}
				if ((!from)||(from.isMulticast())||(from == network->mac())) {
					TRACE("dropped MULTICAST_FRAME from %s@%s(%s) to %s: invalid source MAC",from.toString().c_str(),peer->address().toString().c_str(),_remoteAddress.toString().c_str(),to.toString().c_str());
					return true;
				}

				if (from != MAC(peer->address(),network->id())) {
					if (network->permitsBridging(peer->address())) {
						network->learnBridgeRoute(from,peer->address());
					} else {
						TRACE("dropped MULTICAST_FRAME from %s@%s(%s) to %s: sender not allowed to bridge into %.16llx",from.toString().c_str(),peer->address().toString().c_str(),_remoteAddress.toString().c_str(),to.toString().c_str(),network->id());
						return true;
					}
				}

				network->tapPut(from,to.mac(),etherType,field(offset + ZT_PROTO_VERB_MULTICAST_FRAME_IDX_FRAME,payloadLen),payloadLen);
			}

			if (gatherLimit) {
				Packet outp(source(),RR->identity.address(),Packet::VERB_OK);
				outp.append((unsigned char)Packet::VERB_MULTICAST_FRAME);
				outp.append(packetId());
				outp.append(nwid);
				to.mac().appendTo(outp);
				outp.append((uint32_t)to.adi());
				outp.append((unsigned char)0x02); // flag 0x02 = contains gather results
				if (RR->mc->gather(peer->address(),nwid,to,outp,gatherLimit)) {
					outp.armor(peer->key(),true);
					_fromSock->send(_remoteAddress,outp.data(),outp.size());
				}
			}
		} // else ignore -- not a member of this network

		peer->receive(RR,_fromSock,_remoteAddress,hops(),packetId(),Packet::VERB_MULTICAST_FRAME,0,Packet::VERB_NOP,Utils::now());
	} catch (std::exception &exc) {
		TRACE("dropped MULTICAST_FRAME from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),exc.what());
	} catch ( ... ) {
		TRACE("dropped MULTICAST_FRAME from %s(%s): unexpected exception: (unknown)",source().toString().c_str(),_remoteAddress.toString().c_str());
	}
	return true;
}

void IncomingPacket::_sendErrorNeedCertificate(const RuntimeEnvironment *RR,const SharedPtr<Peer> &peer,uint64_t nwid)
{
	Packet outp(source(),RR->identity.address(),Packet::VERB_ERROR);
	outp.append((unsigned char)verb());
	outp.append(packetId());
	outp.append((unsigned char)Packet::ERROR_NEED_MEMBERSHIP_CERTIFICATE);
	outp.append(nwid);
	outp.armor(peer->key(),true);
	_fromSock->send(_remoteAddress,outp.data(),outp.size());
}

void IncomingPacket::_parseGatherResults(const RuntimeEnvironment *RR,const SharedPtr<Peer> &peer,uint64_t nwid,const MulticastGroup &mg,unsigned int offset)
{
	//unsigned int totalKnown = at<uint32_t>(offset);
	unsigned int count = at<uint16_t>(offset + 4);
	const unsigned char *p = (const unsigned char *)data() + offset + 6;
	const unsigned char *e = (const unsigned char *)data() + size();
	Address atmp;
	uint64_t now = Utils::now();
	for(unsigned int i=0;i<count;++i) {
		const unsigned char *n = p + ZT_ADDRESS_LENGTH;
		if (n > e)
			break;
		atmp.setTo(p,ZT_ADDRESS_LENGTH);
		RR->mc->add(now,nwid,mg,peer->address(),atmp);
		p = n;
	}
}

} // namespace ZeroTier