/*
 * Copyright (c)2013-2021 ZeroTier, Inc.
 *
 * Use of this software is governed by the Business Source License included
 * in the LICENSE.TXT file in the project's root directory.
 *
 * Change Date: 2026-01-01
 *
 * On the date above, in accordance with the Business Source License, use
 * of this software will be governed by version 2.0 of the Apache License.
 */
/****/

/**
 * @file
 *
 * Virtual Ethernet tap device and combined network stack driver
 */

#include "Constants.hpp"
#include "InetAddress.hpp"
#include "MAC.hpp"
#include "MulticastGroup.hpp"
#include "Mutex.hpp"
#include "OSUtils.hpp"
#include "lwip/etharp.h"
#include "lwip/ethip6.h"
#include "lwip/netif.h"
#include "lwip/sys.h"
#include "lwip/tcpip.h"
#include "netif/ethernet.h"

#ifdef LWIP_STATS
#include "lwip/stats.h"
#endif

#include "Events.hpp"
#include "VirtualTap.hpp"
#include "ZeroTierSockets.h"

#if defined(__WINDOWS__)
#include "Synchapi.h"

#include <time.h>
#endif

#define ZTS_TAP_THREAD_POLLING_INTERVAL 50
#define LWIP_DRIVER_LOOP_INTERVAL       250

namespace ZeroTier {

extern Events* zts_events;

/**
 * Virtual tap device. ZeroTier will create one per joined network. It will
 * then be destroyed upon leaving the network.
 */
VirtualTap::VirtualTap(
    const char* homePath,
    const MAC& mac,
    unsigned int mtu,
    unsigned int metric,
    uint64_t net_id,
    void (*handler)(
        void*,
        void*,
        uint64_t,
        const MAC&,
        const MAC&,
        unsigned int,
        unsigned int,
        const void*,
        unsigned int),
    void* arg)
    : _handler(handler)
    , _homePath(homePath)
    , _arg(arg)
    , _initialized(false)
    , _enabled(true)
    , _run(true)
    , _mac(mac)
    , _mtu(mtu)
    , _net_id(net_id)
    , _unixListenSocket((PhySocket*)0)
    , _phy(this, false, true)
{
	OSUtils::ztsnprintf(vtap_full_name, VTAP_NAME_LEN, "libzt-vtap-%llx", _net_id);
#ifndef __WINDOWS__
	::pipe(_shutdownSignalPipe);
#endif
	// Start virtual tap thread and stack I/O loops
	_thread = Thread::start(this);
}

VirtualTap::~VirtualTap()
{
	_run = false;
#ifndef __WINDOWS__
	::write(_shutdownSignalPipe[1], "\0", 1);
#endif
	_phy.whack();
	_lwip_remove_netif(netif4);
	netif4 = NULL;
	_lwip_remove_netif(netif6);
	netif6 = NULL;
	Thread::join(_thread);
#ifndef __WINDOWS__
	::close(_shutdownSignalPipe[0]);
	::close(_shutdownSignalPipe[1]);
#endif
}

void VirtualTap::lastConfigUpdate(uint64_t lastConfigUpdateTime)
{
	_lastConfigUpdateTime = lastConfigUpdateTime;
}

void VirtualTap::setEnabled(bool en)
{
	_enabled = en;
}

bool VirtualTap::enabled() const
{
	return _enabled;
}

void VirtualTap::setUserEventSystem(Events* events)
{
	_events = events;
}

bool VirtualTap::hasIpv4Addr()
{
	Mutex::Lock _l(_ips_m);
	std::vector<InetAddress>::iterator it(_ips.begin());
	while (it != _ips.end()) {
		if ((*it).isV4()) {
			return true;
		}
		++it;
	}
	return false;
}

bool VirtualTap::hasIpv6Addr()
{
	Mutex::Lock _l(_ips_m);
	std::vector<InetAddress>::iterator it(_ips.begin());
	while (it != _ips.end()) {
		if ((*it).isV6()) {
			return true;
		}
		++it;
	}
	return false;
}

bool VirtualTap::addIp(const InetAddress& ip)
{
	// TODO: Rewrite to allow for more addresses
	char ipbuf[128] = { 0 };
	/* Limit address assignments to one per type.
	This limitation can be removed if some changes
	are made in the netif driver. */
	if (ip.isV4() && hasIpv4Addr()) {
		ip.toString(ipbuf);
		// DEBUG_INFO("failed to add IP (%s), only one per type per netif
		// allowed\n", ipbuf);
		return false;
	}
	if (ip.isV6() && hasIpv6Addr()) {
		ip.toString(ipbuf);
		// DEBUG_INFO("failed to add IP (%s), only one per type per netif
		// allowed\n", ipbuf);
		return false;
	}

	Mutex::Lock _l(_ips_m);
	if (_ips.size() >= ZT_MAX_ZT_ASSIGNED_ADDRESSES) {
		return false;
	}
	if (std::find(_ips.begin(), _ips.end(), ip) == _ips.end()) {
		_lwip_init_interface((void*)this, ip);
		_ips.push_back(ip);
		std::sort(_ips.begin(), _ips.end());
	}
	return true;
}

bool VirtualTap::removeIp(const InetAddress& ip)
{
	Mutex::Lock _l(_ips_m);
	if (std::find(_ips.begin(), _ips.end(), ip) != _ips.end()) {
		std::vector<InetAddress>::iterator i(std::find(_ips.begin(), _ips.end(), ip));
		_lwip_remove_address_from_netif((void*)this, ip);
		_ips.erase(i);
	}
	return true;
}

std::vector<InetAddress> VirtualTap::ips() const
{
	Mutex::Lock _l(_ips_m);
	return _ips;
}

void VirtualTap::put(const MAC& from, const MAC& to, unsigned int etherType, const void* data, unsigned int len)
{
	if (len && _enabled) {
		_lwip_eth_rx(this, from, to, etherType, data, len);
	}
}

void VirtualTap::scanMulticastGroups(std::vector<MulticastGroup>& added, std::vector<MulticastGroup>& removed)
{
	std::vector<MulticastGroup> newGroups;
	Mutex::Lock _l(_multicastGroups_m);
	// TODO: get multicast subscriptions
	std::vector<InetAddress> allIps(ips());
	for (std::vector<InetAddress>::iterator ip(allIps.begin()); ip != allIps.end(); ++ip)
		newGroups.push_back(MulticastGroup::deriveMulticastGroupForAddressResolution(*ip));

	std::sort(newGroups.begin(), newGroups.end());

	for (std::vector<MulticastGroup>::iterator m(newGroups.begin()); m != newGroups.end(); ++m) {
		if (! std::binary_search(_multicastGroups.begin(), _multicastGroups.end(), *m))
			added.push_back(*m);
	}
	for (std::vector<MulticastGroup>::iterator m(_multicastGroups.begin()); m != _multicastGroups.end(); ++m) {
		if (! std::binary_search(newGroups.begin(), newGroups.end(), *m))
			removed.push_back(*m);
	}
	_multicastGroups.swap(newGroups);
}

void VirtualTap::setMtu(unsigned int mtu)
{
	_mtu = mtu;
}

void VirtualTap::threadMain() throw()
{
	fd_set readfds, nullfds;
	struct timeval tv;
	tv.tv_sec = 0;
	tv.tv_usec = 0;
	FD_ZERO(&readfds);
	FD_ZERO(&nullfds);
	int nfds = (int)std::max(_shutdownSignalPipe[0], 0) + 1;
#if defined(__linux__)
	pthread_setname_np(pthread_self(), vtap_full_name);
#endif
#if defined(__APPLE__)
	pthread_setname_np(vtap_full_name);
#endif
	while (true) {
		FD_SET(_shutdownSignalPipe[0], &readfds);
		select(nfds, &readfds, &nullfds, &nullfds, &tv);
		// writes to shutdown pipe terminate thread
		if (FD_ISSET(_shutdownSignalPipe[0], &readfds)) {
			break;
		}
#if defined(__WINDOWS__)
		Sleep(ZTS_TAP_THREAD_POLLING_INTERVAL);
#else
		struct timespec sleepValue = { 0 };
		sleepValue.tv_nsec = ZTS_TAP_THREAD_POLLING_INTERVAL * 500000;
		nanosleep(&sleepValue, NULL);
#endif
	}
}

void VirtualTap::phyOnDatagram(
    PhySocket* sock,
    void** uptr,
    const struct sockaddr* local_address,
    const struct sockaddr* from,
    void* data,
    unsigned long len)
{
	// Intentionally empty
}

void VirtualTap::phyOnTcpConnect(PhySocket* sock, void** uptr, bool success)
{
}

void VirtualTap::phyOnTcpAccept(
    PhySocket* sockL,
    PhySocket* sockN,
    void** uptrL,
    void** uptrN,
    const struct sockaddr* from)
{
}

void VirtualTap::phyOnTcpClose(PhySocket* sock, void** uptr)
{
}

void VirtualTap::phyOnTcpData(PhySocket* sock, void** uptr, void* data, unsigned long len)
{
}

void VirtualTap::phyOnTcpWritable(PhySocket* sock, void** uptr)
{
}

void VirtualTap::phyOnUnixClose(PhySocket* sock, void** uptr)
{
}

//----------------------------------------------------------------------------//
// Netif driver code for lwIP network stack                                   //
//----------------------------------------------------------------------------//

bool _has_exited = false;
bool _has_started = false;

// Used to generate enumerated lwIP interface names
int netifCount = 0;

// Lock to guard access to network stack state changes
Mutex stackLock;

// Callback for when the TCPIP thread has been successfully started
static void _tcpip_init_done(void* arg)
{
	sys_sem_t* sem;
	sem = (sys_sem_t*)arg;
	zts_events->setState(ZTS_STATE_STACK_RUNNING);
	_has_started = true;
	zts_events->enqueue(ZTS_EVENT_STACK_UP, NULL);
	sys_sem_signal(sem);
}

static void _main_lwip_driver_loop(void* arg)
{
#if defined(__linux__)
	pthread_setname_np(pthread_self(), ZTS_LWIP_THREAD_NAME);
#endif
#if defined(__APPLE__)
	pthread_setname_np(ZTS_LWIP_THREAD_NAME);
#endif
	sys_sem_t sem;
	LWIP_UNUSED_ARG(arg);
	if (sys_sem_new(&sem, 0) != ERR_OK) {
		// DEBUG_ERROR("failed to create semaphore");
	}
	tcpip_init(_tcpip_init_done, &sem);
	sys_sem_wait(&sem);
	// Main loop
	while (zts_events->getState(ZTS_STATE_STACK_RUNNING)) {
		zts_util_delay(LWIP_DRIVER_LOOP_INTERVAL);
	}
	_has_exited = true;
	zts_events->enqueue(ZTS_EVENT_STACK_DOWN, NULL);
}

bool _lwip_is_up()
{
	Mutex::Lock _l(stackLock);
	return zts_events->getState(ZTS_STATE_STACK_RUNNING);
}

void _lwip_driver_init()
{
	if (_lwip_is_up()) {
		return;
	}
	if (_has_exited) {
		return;
	}
	Mutex::Lock _l(stackLock);
#if defined(__WINDOWS__)
	sys_init();   // Required for win32 init of critical sections
#endif
	sys_thread_new(ZTS_LWIP_THREAD_NAME, _main_lwip_driver_loop, NULL, DEFAULT_THREAD_STACKSIZE, DEFAULT_THREAD_PRIO);
}

void _lwip_driver_shutdown()
{
	if (_has_exited) {
		return;
	}
	Mutex::Lock _l(stackLock);
	// Set flag to stop sending frames into the core
	zts_events->clrState(ZTS_STATE_STACK_RUNNING);
	// Wait until the main lwIP thread has exited
	if (_has_started) {
		while (! _has_exited) {
			zts_util_delay(LWIP_DRIVER_LOOP_INTERVAL);
		}
	}
}

void _lwip_remove_netif(void* netif)
{
	if (! netif) {
		return;
	}
	struct netif* n = (struct netif*)netif;
	LOCK_TCPIP_CORE();
	netif_remove(n);
	netif_set_down(n);
	netif_set_link_down(n);
	UNLOCK_TCPIP_CORE();
}

err_t _lwip_eth_tx(struct netif* n, struct pbuf* p)
{
	if (! n) {
		return ERR_IF;
	}
	struct pbuf* q;
	char buf[ZT_MAX_MTU + 32] = { 0 };
	char* bufptr;
	int totalLength = 0;

	VirtualTap* tap = (VirtualTap*)n->state;
	bufptr = buf;
	for (q = p; q != NULL; q = q->next) {
		memcpy(bufptr, q->payload, q->len);
		bufptr += q->len;
		totalLength += q->len;
	}
	struct eth_hdr* ethhdr;
	ethhdr = (struct eth_hdr*)buf;

	MAC src_mac;
	MAC dest_mac;
	src_mac.setTo(ethhdr->src.addr, 6);
	dest_mac.setTo(ethhdr->dest.addr, 6);

	char* data = buf + sizeof(struct eth_hdr);
	int len = totalLength - sizeof(struct eth_hdr);
	int proto = Utils::ntoh((uint16_t)ethhdr->type);
	tap->_handler(tap->_arg, NULL, tap->_net_id, src_mac, dest_mac, proto, 0, data, len);

	return ERR_OK;
}

void _lwip_eth_rx(
    VirtualTap* tap,
    const MAC& from,
    const MAC& to,
    unsigned int etherType,
    const void* data,
    unsigned int len)
{
#ifdef LWIP_STATS
	stats_display();
#endif
	if (! zts_events->getState(ZTS_STATE_STACK_RUNNING)) {
		return;
	}
	struct pbuf *p, *q;
	struct eth_hdr ethhdr;
	from.copyTo(ethhdr.src.addr, 6);
	to.copyTo(ethhdr.dest.addr, 6);
	ethhdr.type = Utils::hton((uint16_t)etherType);

	p = pbuf_alloc(PBUF_RAW, (uint16_t)len + sizeof(struct eth_hdr), PBUF_RAM);
	if (! p) {
		// DEBUG_ERROR("dropped packet: unable to allocate memory for
		// pbuf");
		return;
	}
	// First pbuf gets Ethernet header at start
	q = p;
	if (q->len < sizeof(ethhdr)) {
		pbuf_free(p);
		p = NULL;
		// DEBUG_ERROR("dropped packet: first pbuf smaller than Ethernet
		// header");
		return;
	}
	// Copy frame data into pbuf
	const char* dataptr = reinterpret_cast<const char*>(data);
	memcpy(q->payload, &ethhdr, sizeof(ethhdr));
	int remainingPayloadSpace = q->len - sizeof(ethhdr);
	memcpy((char*)q->payload + sizeof(ethhdr), dataptr, remainingPayloadSpace);
	dataptr += remainingPayloadSpace;
	// Remaining pbufs (if any) get rest of data
	while ((q = q->next)) {
		memcpy(q->payload, dataptr, q->len);
		dataptr += q->len;
	}
	// Feed packet into stack
	int err;

	if (Utils::ntoh(ethhdr.type) == 0x800 || Utils::ntoh(ethhdr.type) == 0x806) {
		if (tap->netif4) {
			if ((err = ((struct netif*)tap->netif4)->input(p, (struct netif*)tap->netif4)) != ERR_OK) {
				// DEBUG_ERROR("packet input error (%d)", err);
				pbuf_free(p);
			}
		}
	}
	if (Utils::ntoh(ethhdr.type) == 0x86DD) {
		if (tap->netif6) {
			if ((err = ((struct netif*)tap->netif6)->input(p, (struct netif*)tap->netif6)) != ERR_OK) {
				// DEBUG_ERROR("packet input error (%d)", err);
				pbuf_free(p);
			}
		}
	}
}

bool _lwip_is_netif_up(void* n)
{
	if (! n) {
		return false;
	}
	LOCK_TCPIP_CORE();
	bool result = netif_is_up((struct netif*)n);
	UNLOCK_TCPIP_CORE();
	return result;
}

static err_t _netif_init4(struct netif* n)
{
	if (! n || ! n->state) {
		return ERR_IF;
	}
	// Called from core, no need to lock
	VirtualTap* tap = (VirtualTap*)(n->state);
	n->hwaddr_len = 6;
	n->name[0] = '4';
	n->name[1] = 'a' + netifCount;
	n->linkoutput = _lwip_eth_tx;
	n->output = etharp_output;
	n->mtu = std::min(LWIP_MTU, (int)tap->_mtu);
	n->flags = NETIF_FLAG_BROADCAST | NETIF_FLAG_ETHARP | NETIF_FLAG_ETHERNET | NETIF_FLAG_IGMP | NETIF_FLAG_MLD6
	           | NETIF_FLAG_LINK_UP | NETIF_FLAG_UP;
	n->hwaddr_len = sizeof(n->hwaddr);
	tap->_mac.copyTo(n->hwaddr, n->hwaddr_len);
	return ERR_OK;
}

static err_t _netif_init6(struct netif* n)
{
	if (! n || ! n->state) {
		return ERR_IF;
	}
	n->hwaddr_len = sizeof(n->hwaddr);
	VirtualTap* tap = (VirtualTap*)(n->state);
	tap->_mac.copyTo(n->hwaddr, n->hwaddr_len);
	// Called from core, no need to lock
	n->hwaddr_len = 6;
	n->name[0] = '6';
	n->name[1] = 'a' + netifCount;
	n->linkoutput = _lwip_eth_tx;
	n->output_ip6 = ethip6_output;
	n->mtu = std::min(LWIP_MTU, (int)tap->_mtu);
	n->flags = NETIF_FLAG_BROADCAST | NETIF_FLAG_ETHARP | NETIF_FLAG_ETHERNET | NETIF_FLAG_IGMP | NETIF_FLAG_MLD6
	           | NETIF_FLAG_LINK_UP | NETIF_FLAG_UP;
	return ERR_OK;
}

void _lwip_init_interface(void* tapref, const InetAddress& ip)
{
	char macbuf[ZTS_MAC_ADDRSTRLEN] = { 0 };

	VirtualTap* vtap = (VirtualTap*)tapref;
	struct netif* n = NULL;
	bool isNewNetif = false;

	if (ip.isV4()) {
		if (vtap->netif4) {
			n = (struct netif*)vtap->netif4;
		}
		else {
			n = new struct netif;
			isNewNetif = true;
			netifCount++;
		}

		static ip4_addr_t ip4, netmask, gw;
		IP4_ADDR(&gw, 127, 0, 0, 1);
		ip4.addr = *((u32_t*)ip.rawIpData());
		netmask.addr = *((u32_t*)ip.netmask().rawIpData());
		LOCK_TCPIP_CORE();
		netif_add(n, &ip4, &netmask, &gw, (void*)vtap, _netif_init4, tcpip_input);
		vtap->netif4 = (void*)n;
		UNLOCK_TCPIP_CORE();
		snprintf(
		    macbuf,
		    ZTS_MAC_ADDRSTRLEN,
		    "%02x:%02x:%02x:%02x:%02x:%02x",
		    n->hwaddr[0],
		    n->hwaddr[1],
		    n->hwaddr[2],
		    n->hwaddr[3],
		    n->hwaddr[4],
		    n->hwaddr[5]);
	}
	if (ip.isV6()) {
		if (vtap->netif6) {
			n = (struct netif*)vtap->netif6;
		}
		else {
			n = new struct netif;
			isNewNetif = true;
			netifCount++;
		}
		static ip6_addr_t ip6;
		memcpy(&(ip6.addr), ip.rawIpData(), sizeof(ip6.addr));
		LOCK_TCPIP_CORE();
		if (isNewNetif) {
			vtap->netif6 = (void*)n;
			netif_add(n, NULL, NULL, NULL, (void*)vtap, _netif_init6, ethernet_input);
			n->ip6_autoconfig_enabled = 1;
			vtap->_mac.copyTo(n->hwaddr, n->hwaddr_len);
			netif_create_ip6_linklocal_address(n, 1);
			netif_set_link_up(n);
			netif_set_up(n);
			netif_set_default(n);
		}
		netif_add_ip6_address(n, &ip6, NULL);
		n->output_ip6 = ethip6_output;
		UNLOCK_TCPIP_CORE();
		snprintf(
		    macbuf,
		    ZTS_MAC_ADDRSTRLEN,
		    "%02x:%02x:%02x:%02x:%02x:%02x",
		    n->hwaddr[0],
		    n->hwaddr[1],
		    n->hwaddr[2],
		    n->hwaddr[3],
		    n->hwaddr[4],
		    n->hwaddr[5]);
	}
}

void _lwip_remove_address_from_netif(void* tapref, const InetAddress& ip)
{
	if (! tapref) {
		return;
	}
	VirtualTap* vtap = (VirtualTap*)tapref;
	struct netif* n = NULL;
	/* When true multi-homing is implemented this will need to
	be a bit more sophisticated */
	if (ip.isV4()) {
		if (vtap->netif4) {
			n = (struct netif*)vtap->netif4;
		}
	}
	if (ip.isV6()) {
		if (vtap->netif6) {
			n = (struct netif*)vtap->netif6;
		}
	}
	if (! n) {
		return;
	}
	_lwip_remove_netif(n);
}

}   // namespace ZeroTier