/*
 * 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 <math.h>

#include "Constants.hpp"
#include "Network.hpp"
#include "RuntimeEnvironment.hpp"
#include "NodeConfig.hpp"
#include "Switch.hpp"
#include "Packet.hpp"
#include "Buffer.hpp"
#include "EthernetTap.hpp"
#include "EthernetTapFactory.hpp"
#include "RoutingTable.hpp"

#define ZT_NETWORK_CERT_WRITE_BUF_SIZE 131072

namespace ZeroTier {

const ZeroTier::MulticastGroup Network::BROADCAST(ZeroTier::MAC(0xff),0);

const char *Network::statusString(const Status s)
	throw()
{
	switch(s) {
		case NETWORK_INITIALIZING: return "INITIALIZING";
		case NETWORK_WAITING_FOR_FIRST_AUTOCONF: return "WAITING_FOR_FIRST_AUTOCONF";
		case NETWORK_OK: return "OK";
		case NETWORK_ACCESS_DENIED: return "ACCESS_DENIED";
		case NETWORK_NOT_FOUND: return "NOT_FOUND";
		case NETWORK_INITIALIZATION_FAILED: return "INITIALIZATION_FAILED";
		case NETWORK_NO_MORE_DEVICES: return "NO_MORE_DEVICES";
	}
	return "(invalid)";
}

Network::~Network()
{
	_lock.lock();
	if ((_setupThread)&&(!_destroyed)) {
		_lock.unlock();
		Thread::join(_setupThread);
	} else _lock.unlock();

	{
		Mutex::Lock _l(_lock);
		if (_tap)
			RR->tapFactory->close(_tap,_destroyed);
	}

	if (_destroyed) {
		Utils::rm(std::string(RR->homePath + ZT_PATH_SEPARATOR_S + "networks.d" + ZT_PATH_SEPARATOR_S + idString() + ".conf"));
		Utils::rm(std::string(RR->homePath + ZT_PATH_SEPARATOR_S + "networks.d" + ZT_PATH_SEPARATOR_S + idString() + ".mcerts"));
	} else {
		clean();
		_dumpMembershipCerts();
	}
}

SharedPtr<Network> Network::newInstance(const RuntimeEnvironment *renv,NodeConfig *nc,uint64_t id)
{
	SharedPtr<Network> nw(new Network());
	nw->_id = id;
	nw->_nc = nc;
	nw->_mac.fromAddress(renv->identity.address(),id);
	nw->RR = renv;
	nw->_tap = (EthernetTap *)0;
	nw->_enabled = true;
	nw->_lastConfigUpdate = 0;
	nw->_destroyed = false;
	nw->_netconfFailure = NETCONF_FAILURE_NONE;

	if (nw->controller() == renv->identity.address()) // TODO: fix Switch to allow packets to self
		throw std::runtime_error("cannot join a network for which I am the netconf master");

	try {
		nw->_restoreState();
		nw->requestConfiguration();
	} catch ( ... ) {
		nw->_lastConfigUpdate = 0; // call requestConfiguration() again
	}

	return nw;
}

// Function object used by rescanMulticastGroups()
class AnnounceMulticastGroupsToPeersWithActiveDirectPaths
{
public:
	AnnounceMulticastGroupsToPeersWithActiveDirectPaths(const RuntimeEnvironment *renv,Network *nw) :
		RR(renv),
		_now(Utils::now()),
		_network(nw),
		_supernodeAddresses(renv->topology->supernodeAddresses())
	{}

	inline void operator()(Topology &t,const SharedPtr<Peer> &p)
	{
		if ( ( (p->hasActiveDirectPath(_now)) && (_network->isAllowed(p->address())) ) || (std::find(_supernodeAddresses.begin(),_supernodeAddresses.end(),p->address()) != _supernodeAddresses.end()) ) {
			Packet outp(p->address(),RR->identity.address(),Packet::VERB_MULTICAST_LIKE);

			std::set<MulticastGroup> mgs(_network->multicastGroups());
			for(std::set<MulticastGroup>::iterator mg(mgs.begin());mg!=mgs.end();++mg) {
				if ((outp.size() + 18) > ZT_UDP_DEFAULT_PAYLOAD_MTU) {
					outp.armor(p->key(),true);
					p->send(RR,outp.data(),outp.size(),_now);
					outp.reset(p->address(),RR->identity.address(),Packet::VERB_MULTICAST_LIKE);
				}

				// network ID, MAC, ADI
				outp.append((uint64_t)_network->id());
				mg->mac().appendTo(outp);
				outp.append((uint32_t)mg->adi());
			}

			if (outp.size() > ZT_PROTO_MIN_PACKET_LENGTH) {
				outp.armor(p->key(),true);
				p->send(RR,outp.data(),outp.size(),_now);
			}
		}
	}

private:
	const RuntimeEnvironment *RR;
	uint64_t _now;
	Network *_network;
	std::vector<Address> _supernodeAddresses;
};

bool Network::rescanMulticastGroups()
{
	bool updated = false;

	{
		Mutex::Lock _l(_lock);
		EthernetTap *t = _tap;
		if (t) {
			// Grab current groups from the local tap
			updated = t->updateMulticastGroups(_myMulticastGroups);

			// Merge in learned groups from any hosts bridged in behind us
			for(std::map<MulticastGroup,uint64_t>::const_iterator mg(_multicastGroupsBehindMe.begin());mg!=_multicastGroupsBehindMe.end();++mg)
				_myMulticastGroups.insert(mg->first);

			// Add or remove BROADCAST group based on broadcast enabled netconf flag
			if ((_config)&&(_config->enableBroadcast())) {
				if (!_myMulticastGroups.count(BROADCAST)) {
					_myMulticastGroups.insert(BROADCAST);
					updated = true;
				}
			} else {
				if (_myMulticastGroups.count(BROADCAST)) {
					_myMulticastGroups.erase(BROADCAST);
					updated = true;
				}
			}
		}
	}

	if (updated) {
		AnnounceMulticastGroupsToPeersWithActiveDirectPaths afunc(RR,this);
		RR->topology->eachPeer<AnnounceMulticastGroupsToPeersWithActiveDirectPaths &>(afunc);
	}

	return updated;
}

bool Network::applyConfiguration(const SharedPtr<NetworkConfig> &conf)
{
	Mutex::Lock _l(_lock);

	if (_destroyed)
		return false;

	try {
		if ((conf->networkId() == _id)&&(conf->issuedTo() == RR->identity.address())) {
			std::vector<InetAddress> oldStaticIps;
			if (_config)
				oldStaticIps = _config->staticIps();

			_config = conf;

			_lastConfigUpdate = Utils::now();
			_netconfFailure = NETCONF_FAILURE_NONE;

			EthernetTap *t = _tap;
			if (t) {
				char fname[1024];
				_mkNetworkFriendlyName(fname,sizeof(fname));
				t->setFriendlyName(fname);

				// Remove previously configured static IPs that are gone
				for(std::vector<InetAddress>::const_iterator oldip(oldStaticIps.begin());oldip!=oldStaticIps.end();++oldip) {
					if (std::find(_config->staticIps().begin(),_config->staticIps().end(),*oldip) == _config->staticIps().end())
						t->removeIP(*oldip);
				}

				// Add new static IPs that were not in previous config
				for(std::vector<InetAddress>::const_iterator newip(_config->staticIps().begin());newip!=_config->staticIps().end();++newip) {
					if (std::find(oldStaticIps.begin(),oldStaticIps.end(),*newip) == oldStaticIps.end())
						t->addIP(*newip);
				}

#ifdef __APPLE__
				// Make sure there's an IPv6 link-local address on Macs if IPv6 is enabled
				// Other OSes don't need this -- Mac seems not to want to auto-assign
				// This might go away once we integrate properly w/Mac network setup stuff.
				if (_config->permitsEtherType(ZT_ETHERTYPE_IPV6)) {
					bool haveV6LinkLocal = false;
					std::set<InetAddress> ips(t->ips());
					for(std::set<InetAddress>::const_iterator i(ips.begin());i!=ips.end();++i) {
						if ((i->isV6())&&(i->isLinkLocal())) {
							haveV6LinkLocal = true;
							break;
						}
					}
					if (!haveV6LinkLocal)
						t->addIP(InetAddress::makeIpv6LinkLocal(_mac));
				}
#endif // __APPLE__

				// ... IPs that were never controlled by static assignment are left
				// alone, as these may be DHCP or user-configured.
			} else {
				if (!_setupThread)
					_setupThread = Thread::start<Network>(this);
			}

			return true;
		} else {
			LOG("ignored invalid configuration for network %.16llx (configuration contains mismatched network ID or issued-to address)",(unsigned long long)_id);
		}
	} catch (std::exception &exc) {
		LOG("ignored invalid configuration for network %.16llx (%s)",(unsigned long long)_id,exc.what());
	} catch ( ... ) {
		LOG("ignored invalid configuration for network %.16llx (unknown exception)",(unsigned long long)_id);
	}

	return false;
}

bool Network::setConfiguration(const Dictionary &conf,bool saveToDisk)
{
	try {
		SharedPtr<NetworkConfig> newConfig(new NetworkConfig(conf)); // throws if invalid
		if (applyConfiguration(newConfig)) {
			if (saveToDisk) {
				std::string confPath(RR->homePath + ZT_PATH_SEPARATOR_S + "networks.d" + ZT_PATH_SEPARATOR_S + idString() + ".conf");
				if (!Utils::writeFile(confPath.c_str(),conf.toString())) {
					LOG("error: unable to write network configuration file at: %s",confPath.c_str());
				} else {
					Utils::lockDownFile(confPath.c_str(),false);
				}
			}
			return true;
		}
	} catch ( ... ) {
		LOG("ignored invalid configuration for network %.16llx (dictionary decode failed)",(unsigned long long)_id);
	}
	return false;
}

void Network::requestConfiguration()
{
	if (_id == ZT_TEST_NETWORK_ID) // pseudo-network-ID, no netconf master
		return;

	if (controller() == RR->identity.address()) {
		// netconf master cannot be a member of its own nets
		LOG("unable to request network configuration for network %.16llx: I am the network master, cannot query self",(unsigned long long)_id);
		return;
	}

	TRACE("requesting netconf for network %.16llx from netconf master %s",(unsigned long long)_id,controller().toString().c_str());
	Packet outp(controller(),RR->identity.address(),Packet::VERB_NETWORK_CONFIG_REQUEST);
	outp.append((uint64_t)_id);
	outp.append((uint16_t)0); // no meta-data
	RR->sw->send(outp,true);
}

void Network::addMembershipCertificate(const CertificateOfMembership &cert,bool forceAccept)
{
	if (!cert) // sanity check
		return;

	if (!forceAccept) {
		if (cert.signedBy() != controller()) {
			LOG("rejected network membership certificate for %.16llx signed by %s: signer not a controller of this network",(unsigned long long)_id,cert.signedBy().toString().c_str());
			return;
		}

		SharedPtr<Peer> signer(RR->topology->getPeer(cert.signedBy()));

		if (!signer) {
			// This would be rather odd, since this is our netconf master... could happen
			// if we get packets before we've gotten config.
			RR->sw->requestWhois(cert.signedBy());
			return;
		}

		if (!cert.verify(signer->identity())) {
			LOG("rejected network membership certificate for %.16llx signed by %s: signature check failed",(unsigned long long)_id,cert.signedBy().toString().c_str());
			return;
		}
	}

	Mutex::Lock _l(_lock);

	CertificateOfMembership &old = _membershipCertificates[cert.issuedTo()];
	if (cert.timestamp() >= old.timestamp())
		old = cert;
}

bool Network::peerNeedsOurMembershipCertificate(const Address &to,uint64_t now)
{
	Mutex::Lock _l(_lock);
	if ((_config)&&(!_config->isPublic())&&(_config->com())) {
		uint64_t pushInterval = _config->com().timestampMaxDelta() / 2;
		if (pushInterval) {
			// Give a 1s margin around +/- 1/2 max delta to account for network latency
			if (pushInterval > 1000)
				pushInterval -= 1000;

			uint64_t &lastPushed = _lastPushedMembershipCertificate[to];
			if ((now - lastPushed) > pushInterval) {
				lastPushed = now;
				return true;
			}
		}
	}
	return false;
}

bool Network::isAllowed(const Address &peer) const
{
	try {
		Mutex::Lock _l(_lock);

		if (!_config)
			return false;
		if (_config->isPublic())
			return true;

		std::map<Address,CertificateOfMembership>::const_iterator pc(_membershipCertificates.find(peer));
		if (pc == _membershipCertificates.end())
			return false; // no certificate on file

		return _config->com().agreesWith(pc->second); // is other cert valid against ours?
	} catch (std::exception &exc) {
		TRACE("isAllowed() check failed for peer %s: unexpected exception: %s",peer.toString().c_str(),exc.what());
	} catch ( ... ) {
		TRACE("isAllowed() check failed for peer %s: unexpected exception: unknown exception",peer.toString().c_str());
	}
	return false; // default position on any failure
}

void Network::clean()
{
	uint64_t now = Utils::now();
	Mutex::Lock _l(_lock);

	if (_destroyed)
		return;

	if ((_config)&&(_config->isPublic())) {
		// Open (public) networks do not track certs or cert pushes at all.
		_membershipCertificates.clear();
		_lastPushedMembershipCertificate.clear();
	} else if (_config) {
		// Clean certificates that are no longer valid from the cache.
		for(std::map<Address,CertificateOfMembership>::iterator c=(_membershipCertificates.begin());c!=_membershipCertificates.end();) {
			if (_config->com().agreesWith(c->second))
				++c;
			else _membershipCertificates.erase(c++);
		}

		// Clean entries from the last pushed tracking map if they're so old as
		// to be no longer relevant.
		uint64_t forgetIfBefore = now - (_config->com().timestampMaxDelta() * 3ULL);
		for(std::map<Address,uint64_t>::iterator lp(_lastPushedMembershipCertificate.begin());lp!=_lastPushedMembershipCertificate.end();) {
			if (lp->second < forgetIfBefore)
				_lastPushedMembershipCertificate.erase(lp++);
			else ++lp;
		}
	}

	// Clean learned multicast groups if we haven't heard from them in a while
	for(std::map<MulticastGroup,uint64_t>::iterator mg(_multicastGroupsBehindMe.begin());mg!=_multicastGroupsBehindMe.end();) {
		if ((now - mg->second) > (ZT_MULTICAST_LIKE_EXPIRE * 2))
			_multicastGroupsBehindMe.erase(mg++);
		else ++mg;
	}
}

Network::Status Network::status() const
{
	Mutex::Lock _l(_lock);
	switch(_netconfFailure) {
		case NETCONF_FAILURE_ACCESS_DENIED:
			return NETWORK_ACCESS_DENIED;
		case NETCONF_FAILURE_NOT_FOUND:
			return NETWORK_NOT_FOUND;
		case NETCONF_FAILURE_NONE:
			return ((_lastConfigUpdate > 0) ? ((_tap) ? NETWORK_OK : NETWORK_INITIALIZING) : NETWORK_WAITING_FOR_FIRST_AUTOCONF);
		//case NETCONF_FAILURE_INIT_FAILED:
		default:
			return NETWORK_INITIALIZATION_FAILED;
	}
}

void Network::learnBridgeRoute(const MAC &mac,const Address &addr)
{
	Mutex::Lock _l(_lock);
	_remoteBridgeRoutes[mac] = addr;

	// If _remoteBridgeRoutes exceeds sanity limit, trim worst offenders until below -- denial of service circuit breaker
	while (_remoteBridgeRoutes.size() > ZT_MAX_BRIDGE_ROUTES) {
		std::map<Address,unsigned long> counts;
		Address maxAddr;
		unsigned long maxCount = 0;
		for(std::map<MAC,Address>::iterator br(_remoteBridgeRoutes.begin());br!=_remoteBridgeRoutes.end();++br) {
			unsigned long c = ++counts[br->second];
			if (c > maxCount) {
				maxCount = c;
				maxAddr = br->second;
			}
		}
		for(std::map<MAC,Address>::iterator br(_remoteBridgeRoutes.begin());br!=_remoteBridgeRoutes.end();) {
			if (br->second == maxAddr)
				_remoteBridgeRoutes.erase(br++);
			else ++br;
		}
	}
}

void Network::setEnabled(bool enabled)
{
	Mutex::Lock _l(_lock);
	_enabled = enabled;
	if (_tap)
		_tap->setEnabled(enabled);
}

void Network::destroy()
{
	Mutex::Lock _l(_lock);

	_enabled = false;
	_destroyed = true;

	if (_setupThread)
		Thread::join(_setupThread);
	_setupThread = Thread();

	if (_tap)
		RR->tapFactory->close(_tap,true);
	_tap = (EthernetTap *)0;
}

// Ethernet tap creation thread -- required on some platforms where tap
// creation may be time consuming (e.g. Windows). Thread exits after tap
// device setup.
void Network::threadMain()
	throw()
{
	char fname[1024],lcentry[128];
	Utils::snprintf(lcentry,sizeof(lcentry),"_dev_for_%.16llx",(unsigned long long)_id);

	EthernetTap *t = (EthernetTap *)0;
	try {
		std::string desiredDevice(_nc->getLocalConfig(lcentry));
		_mkNetworkFriendlyName(fname,sizeof(fname));

		t = RR->tapFactory->open(_mac,ZT_IF_MTU,ZT_DEFAULT_IF_METRIC,_id,(desiredDevice.length() > 0) ? desiredDevice.c_str() : (const char *)0,fname,_CBhandleTapData,this);

		std::string dn(t->deviceName());
		if ((dn.length())&&(dn != desiredDevice))
			_nc->putLocalConfig(lcentry,dn);
	} catch (std::exception &exc) {
		delete t;
		t = (EthernetTap *)0;
		LOG("network %.16llx failed to initialize: %s",_id,exc.what());
		_netconfFailure = NETCONF_FAILURE_INIT_FAILED;
	} catch ( ... ) {
		delete t;
		t = (EthernetTap *)0;
		LOG("network %.16llx failed to initialize: unknown error",_id);
		_netconfFailure = NETCONF_FAILURE_INIT_FAILED;
	}

	{
		Mutex::Lock _l(_lock);
		if (_tap) // the tap creation thread can technically be re-launched, though this isn't done right now
			RR->tapFactory->close(_tap,false);
		_tap = t;
		if (t) {
			if (_config) {
				for(std::vector<InetAddress>::const_iterator newip(_config->staticIps().begin());newip!=_config->staticIps().end();++newip)
					t->addIP(*newip);
			}
			t->setEnabled(_enabled);
		}
	}

	rescanMulticastGroups();
}

void Network::_CBhandleTapData(void *arg,const MAC &from,const MAC &to,unsigned int etherType,const Buffer<4096> &data)
{
	if ((!((Network *)arg)->_enabled)||(((Network *)arg)->status() != NETWORK_OK))
		return;

	const RuntimeEnvironment *RR = ((Network *)arg)->RR;
	if (RR->shutdownInProgress)
		return;

	try {
		RR->sw->onLocalEthernet(SharedPtr<Network>((Network *)arg),from,to,etherType,data);
	} catch (std::exception &exc) {
		TRACE("unexpected exception handling local packet: %s",exc.what());
	} catch ( ... ) {
		TRACE("unexpected exception handling local packet");
	}
}

void Network::_restoreState()
{
	Buffer<ZT_NETWORK_CERT_WRITE_BUF_SIZE> buf;

	std::string idstr(idString());
	std::string confPath(RR->homePath + ZT_PATH_SEPARATOR_S + "networks.d" + ZT_PATH_SEPARATOR_S + idstr + ".conf");
	std::string mcdbPath(RR->homePath + ZT_PATH_SEPARATOR_S + "networks.d" + ZT_PATH_SEPARATOR_S + idstr + ".mcerts");

	if (_id == ZT_TEST_NETWORK_ID) {
		applyConfiguration(NetworkConfig::createTestNetworkConfig(RR->identity.address()));

		// "Touch" path to this ID to remember test network membership
		FILE *tmp = fopen(confPath.c_str(),"w");
		if (tmp) fclose(tmp);
	} else {
		// Read configuration file containing last config from netconf master
		{
			std::string confs;
			if (Utils::readFile(confPath.c_str(),confs)) {
				try {
					if (confs.length())
						setConfiguration(Dictionary(confs),false);
				} catch ( ... ) {} // ignore invalid config on disk, we will re-request from netconf master
			} else {
				// "Touch" path to remember membership in lieu of real config from netconf master
				FILE *tmp = fopen(confPath.c_str(),"w");
				if (tmp) fclose(tmp);
			}
		}
	}

	{ // Read most recent membership cert dump if there is one
		Mutex::Lock _l(_lock);
		if ((_config)&&(!_config->isPublic())&&(Utils::fileExists(mcdbPath.c_str()))) {
			CertificateOfMembership com;

			_membershipCertificates.clear();

			FILE *mcdb = fopen(mcdbPath.c_str(),"rb");
			if (mcdb) {
				try {
					char magic[6];
					if ((fread(magic,6,1,mcdb) == 1)&&(!memcmp("ZTMCD0",magic,6))) {
						long rlen = 0;
						do {
							long rlen = (long)fread(const_cast<char *>(static_cast<const char *>(buf.data())) + buf.size(),1,ZT_NETWORK_CERT_WRITE_BUF_SIZE - buf.size(),mcdb);
							if (rlen < 0) rlen = 0;
							buf.setSize(buf.size() + (unsigned int)rlen);
							unsigned int ptr = 0;
							while ((ptr < (ZT_NETWORK_CERT_WRITE_BUF_SIZE / 2))&&(ptr < buf.size())) {
								ptr += com.deserialize(buf,ptr);
								if (com.issuedTo())
									_membershipCertificates[com.issuedTo()] = com;
							}
							buf.behead(ptr);
						} while (rlen > 0);
						fclose(mcdb);
					} else {
						fclose(mcdb);
						Utils::rm(mcdbPath);
					}
				} catch ( ... ) {
					// Membership cert dump file invalid. We'll re-learn them off the net.
					_membershipCertificates.clear();
					fclose(mcdb);
					Utils::rm(mcdbPath);
				}
			}
		}
	}
}

void Network::_dumpMembershipCerts()
{
	Buffer<ZT_NETWORK_CERT_WRITE_BUF_SIZE> buf;
	std::string mcdbPath(RR->homePath + ZT_PATH_SEPARATOR_S + "networks.d" + ZT_PATH_SEPARATOR_S + idString() + ".mcerts");
	Mutex::Lock _l(_lock);

	if (!_config)
		return;

	if ((!_id)||(_config->isPublic())) {
		Utils::rm(mcdbPath);
		return;
	}

	FILE *mcdb = fopen(mcdbPath.c_str(),"wb");
	if (!mcdb)
		return;

	if (fwrite("ZTMCD0",6,1,mcdb) != 1) {
		fclose(mcdb);
		Utils::rm(mcdbPath);
		return;
	}

	for(std::map<Address,CertificateOfMembership>::iterator c=(_membershipCertificates.begin());c!=_membershipCertificates.end();++c) {
		buf.clear();
		c->second.serialize(buf);
		if (buf.size() > 0) {
			if (fwrite(buf.data(),buf.size(),1,mcdb) != 1) {
				fclose(mcdb);
				Utils::rm(mcdbPath);
				return;
			}
		}
	}

	fclose(mcdb);
	Utils::lockDownFile(mcdbPath.c_str(),false);
}

} // namespace ZeroTier