/*
 * ZeroTier One - Global Peer to Peer Ethernet
 * Copyright (C) 2012-2013  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 <algorithm>

#include "Constants.hpp"
#include "RuntimeEnvironment.hpp"
#include "NodeConfig.hpp"
#include "Network.hpp"
#include "Switch.hpp"
#include "Packet.hpp"
#include "Utils.hpp"
#include "Buffer.hpp"

#define ZT_NETWORK_CERT_WRITE_BUF_SIZE 524288

namespace ZeroTier {

const Network::MulticastRates::Rate Network::MulticastRates::GLOBAL_DEFAULT_RATE(65535,65535,64);

const char *Network::statusString(const Status s)
	throw()
{
	switch(s) {
		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";
	}
	return "(invalid)";
}

Network::~Network()
{
	delete _tap;
	if (_destroyOnDelete) {
		Utils::rm(std::string(_r->homePath + ZT_PATH_SEPARATOR_S + "networks.d" + ZT_PATH_SEPARATOR_S + idString() + ".conf"));
		Utils::rm(std::string(_r->homePath + ZT_PATH_SEPARATOR_S + "networks.d" + ZT_PATH_SEPARATOR_S + idString() + ".mcerts"));
	} else {
		// Causes flush of membership certs to disk
		clean();
		_dumpMulticastCerts();
	}
}

SharedPtr<Network> Network::newInstance(const RuntimeEnvironment *renv,uint64_t id)
	throw(std::runtime_error)
{
	// Tag to identify tap device -- used on some OSes like Windows
	char tag[32];
	Utils::snprintf(tag,sizeof(tag),"%.16llx",(unsigned long long)id);

	// We construct Network via a static method to ensure that it is immediately
	// wrapped in a SharedPtr<>. Otherwise if there is traffic on the Ethernet
	// tap device, a SharedPtr<> wrap can occur in the Ethernet frame handler
	// that then causes the Network instance to be deleted before it is finished
	// being constructed. C++ edge cases, how I love thee.
	SharedPtr<Network> nw(new Network());
	nw->_ready = false; // disable handling of Ethernet frames during construct
	nw->_r = renv;
	nw->_tap = new EthernetTap(renv,tag,renv->identity.address().toMAC(),ZT_IF_MTU,&_CBhandleTapData,nw.ptr());
	nw->_isOpen = false;
	nw->_emulateArp = false;
	nw->_emulateNdp = false;
	nw->_multicastPrefixBits = ZT_DEFAULT_MULTICAST_PREFIX_BITS;
	nw->_multicastDepth = ZT_DEFAULT_MULTICAST_DEPTH;
	nw->_status = NETWORK_WAITING_FOR_FIRST_AUTOCONF;
	memset(nw->_etWhitelist,0,sizeof(nw->_etWhitelist));
	nw->_id = id;
	nw->_lastConfigUpdate = 0;
	nw->_destroyOnDelete = false;
	if (nw->controller() == renv->identity.address()) // netconf masters can't really join networks
		throw std::runtime_error("cannot join a network for which I am the netconf master");
	nw->_restoreState();
	nw->_ready = true; // enable handling of Ethernet frames
	nw->requestConfiguration();
	return nw;
}

void Network::setConfiguration(const Network::Config &conf,bool saveToDisk)
{
	Mutex::Lock _l(_lock);
	try {
		if (conf.networkId() == _id) { // sanity check
			_configuration = conf;

			// Grab some things from conf for faster lookup and memoize them
			_myCertificate = conf.certificateOfMembership();
			_mcRates = conf.multicastRates();
			_staticAddresses = conf.staticAddresses();
			_isOpen = conf.isOpen();
			_emulateArp = conf.emulateArp();
			_emulateNdp = conf.emulateNdp();
			_multicastPrefixBits = conf.multicastPrefixBits();
			_multicastDepth = conf.multicastDepth();

			_lastConfigUpdate = Utils::now();

			_tap->setIps(_staticAddresses);
			_tap->setDisplayName((std::string("ZeroTier One [") + conf.name() + "]").c_str());

			// Expand ethertype whitelist into fast-lookup bit field (more memoization)
			memset(_etWhitelist,0,sizeof(_etWhitelist));
			std::set<unsigned int> wl(conf.etherTypes());
			for(std::set<unsigned int>::const_iterator t(wl.begin());t!=wl.end();++t)
				_etWhitelist[*t / 8] |= (unsigned char)(1 << (*t % 8));

			_status = NETWORK_OK;

			if (saveToDisk) {
				std::string confPath(_r->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());
				}
			}
		}
	} catch ( ... ) {
		// If conf is invalid, reset everything
		_configuration = Config();

		_myCertificate = CertificateOfMembership();
		_mcRates = MulticastRates();
		_staticAddresses.clear();
		_isOpen = false;
		_emulateArp = false;
		_emulateNdp = false;
		_status = NETWORK_WAITING_FOR_FIRST_AUTOCONF;

		_lastConfigUpdate = 0;
		LOG("unexpected exception handling config for network %.16llx, retrying fetch...",(unsigned long long)_id);
	}
}

void Network::requestConfiguration()
{
	if (controller() == _r->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(),_r->identity.address(),Packet::VERB_NETWORK_CONFIG_REQUEST);
	outp.append((uint64_t)_id);
	outp.append((uint16_t)0); // no meta-data
	_r->sw->send(outp,true);
}

void Network::addMembershipCertificate(const CertificateOfMembership &cert)
{
	Mutex::Lock _l(_lock);

	// We go ahead and accept certs provisionally even if _isOpen is true, since
	// that might be changed in short order if the user is fiddling in the UI.
	// These will be purged on clean() for open networks eventually.

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

bool Network::isAllowed(const Address &peer) const
{
	// Exceptions can occur if we do not yet have *our* configuration.
	try {
		Mutex::Lock _l(_lock);
		if (_isOpen)
			return true; // network is public
		std::map<Address,CertificateOfMembership>::const_iterator pc(_membershipCertificates.find(peer));
		if (pc == _membershipCertificates.end())
			return false; // no certificate on file
		return _myCertificate.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()
{
	Mutex::Lock _l(_lock);
	uint64_t timestampMaxDelta = _myCertificate.timestampMaxDelta();
	if (_isOpen) {
		// Open (public) networks do not track certs or cert pushes at all.
		_membershipCertificates.clear();
		_lastPushedMembershipCertificate.clear();
	} else if (timestampMaxDelta) {
		// Clean certificates that are no longer valid from the cache.
		for(std::map<Address,CertificateOfMembership>::iterator c=(_membershipCertificates.begin());c!=_membershipCertificates.end();) {
			if (_myCertificate.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 = Utils::now() - (timestampMaxDelta * 3);
		for(std::map<Address,uint64_t>::iterator lp(_lastPushedMembershipCertificate.begin());lp!=_lastPushedMembershipCertificate.end();) {
			if (lp->second < forgetIfBefore)
				_lastPushedMembershipCertificate.erase(lp++);
			else ++lp;
		}
	}
}

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

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

	try {
		_r->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::_pushMembershipCertificate(const Address &peer,bool force,uint64_t now)
{
	uint64_t timestampMaxDelta = _myCertificate.timestampMaxDelta();
	if (!timestampMaxDelta)
		return; // still waiting on my own cert

	uint64_t &lastPushed = _lastPushedMembershipCertificate[peer];
	if ((force)||((now - lastPushed) > (timestampMaxDelta / 2))) {
		lastPushed = now;

		Packet outp(peer,_r->identity.address(),Packet::VERB_NETWORK_MEMBERSHIP_CERTIFICATE);
		_myCertificate.serialize(outp);
		_r->sw->send(outp,true);
	}
}

void Network::_restoreState()
{
	if (!_id)
		return; // sanity check

	Buffer<ZT_NETWORK_CERT_WRITE_BUF_SIZE> buf;

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

	// Read configuration file containing last config from netconf master
	{
		std::string confs;
		if (Utils::readFile(confPath.c_str(),confs)) {
			try {
				if (confs.length())
					setConfiguration(Config(confs),false);
			} catch ( ... ) {} // ignore invalid config on disk, we will re-request from netconf master
		} else {
			// If the conf file isn't present, "touch" it so we'll remember
			// the existence of this network.
			FILE *tmp = fopen(confPath.c_str(),"wb");
			if (tmp)
				fclose(tmp);
		}
	}

	// Read most recent multicast cert dump
	if ((!_isOpen)&&(Utils::fileExists(mcdbPath.c_str()))) {
		CertificateOfMembership com;
		Mutex::Lock _l(_lock);

		_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))) {
					for(;;) {
						long rlen = (long)fread(buf.data() + buf.size(),1,ZT_NETWORK_CERT_WRITE_BUF_SIZE - buf.size(),mcdb);
						if (rlen <= 0)
							break;
						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;
						}
						if (ptr) {
							memmove(buf.data(),buf.data() + ptr,buf.size() - ptr);
							buf.setSize(buf.size() - ptr);
						}
					}
					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::_dumpMulticastCerts()
{
	Buffer<ZT_NETWORK_CERT_WRITE_BUF_SIZE> buf;
	std::string mcdbPath(_r->homePath + ZT_PATH_SEPARATOR_S + "networks.d" + ZT_PATH_SEPARATOR_S + idString() + ".mcerts");
	Mutex::Lock _l(_lock);

	if ((!_id)||(_isOpen)) {
		Utils::rm(mcdbPath);
		return;
	}

	FILE *mcdb = fopen(mcdbPath.c_str(),"wb");
	if (!mcdb)
		return;
	if (fwrite("ZTMCD0",6,1,mcdb) != 1) {
		Utils::rm(mcdbPath);
		return;
	}

	for(std::map<Address,CertificateOfMembership>::iterator c=(_membershipCertificates.begin());c!=_membershipCertificates.end();++c) {
		try {
			c->second.serialize(buf);
			if (buf.size() >= (ZT_NETWORK_CERT_WRITE_BUF_SIZE / 2)) {
				if (fwrite(buf.data(),buf.size(),1,mcdb) != 1) {
					fclose(mcdb);
					Utils::rm(mcdbPath);
					return;
				}
				buf.clear();
			}
		} catch ( ... ) {
			// Sanity check... no cert will ever be big enough to overflow buf
			fclose(mcdb);
			Utils::rm(mcdbPath);
			return;
		}
	}

	if (buf.size()) {
		if (fwrite(buf.data(),buf.size(),1,mcdb) != 1) {
			fclose(mcdb);
			Utils::rm(mcdbPath);
			return;
		}
	}

	fclose(mcdb);
}

} // namespace ZeroTier