#include <sys/times.h>
#include <fcntl.h>
#include <unistd.h>
#include <iostream>
#include "ExtOsdep.hpp"
#include <list>
#include "../node/AtomicCounter.hpp"

#define ZT_TAP_BUF_SIZE 16384

namespace ZeroTier {

static int eodFd = -1;
static Mutex eodMutex;
static int eodMgmtFd = -1;

struct EodRoute {
	InetAddress target;
	InetAddress via;
	InetAddress src;
	std::string ifname;
};
static std::list<EodRoute> allRoutes;

template<typename T> static void __eodSend(const T &t) {
	write(eodFd, &t, sizeof(t));
}

static void strncpyx(char *dest, const char *src, size_t n) {
	strncpy(dest, src, n);
	if (n > 1) dest[n - 1] = 0;
}

static int __eodWait(unsigned char msg, unsigned char *d, unsigned l,
		unsigned maxl = 0, int *recvfd = nullptr) {
	if (!maxl) maxl = l;
	auto start = times(NULL);
	while (1) {
		msghdr mh;
		iovec iov;
		struct {
			size_t cmsg_len;
			int cmsg_level;
			int cmsg_type;
			int fd;
		} __attribute__((packed)) cmsg;
		memset(&mh, 0, sizeof(mh));
		mh.msg_iov = &iov;
		mh.msg_iovlen = 1;
		if (recvfd) {
			mh.msg_control = &cmsg;
			mh.msg_controllen = sizeof(cmsg);
		}
		iov.iov_base = d;
		iov.iov_len = maxl;

		int r = recvmsg(eodFd, &mh, MSG_TRUNC | MSG_CMSG_CLOEXEC);
		if (r > 0) {
			if (recvfd && mh.msg_controllen >= sizeof(cmsg)
				&& cmsg.cmsg_len == sizeof(cmsg)
				&& cmsg.cmsg_level == SOL_SOCKET
				&& cmsg.cmsg_type == SCM_RIGHTS) {
				*recvfd = cmsg.fd;
				fprintf(stderr, "eodWait: received fd %d\n", *recvfd);
			}

			if (d[0] != msg) {
				fprintf(stderr, "eodWait: wrong msg, expected %u got %u\n", msg, d[0]);
				return -1;
			}
			if ((unsigned)r < l || (unsigned)r > maxl) {
				fprintf(stderr, "eodWait: wrong len, expected %u got %d\n", l, r);
				return -1;
			}
			return r;
		}
		if (times(NULL) - start > 500) {
			fprintf(stderr, "eodWait: timeout\n");
			return -1;
		}
		usleep(100000);
	}
}

template<typename T> static bool __eodWait(unsigned msg, T &t) {
	return __eodWait(msg, (unsigned char *)&t, sizeof(T)) == (int)sizeof(T);
}

template<typename M, typename R> static bool __eodXchg(const M &m, unsigned rm, R &r) {
	__eodSend(m);
	return __eodWait(rm, r);
}

template<typename M, typename R> static bool eodXchg(const M &m, unsigned rm, R &r) {
	Mutex::Lock l(eodMutex);
	return __eodXchg(m, rm, r);
}

void ExtOsdep::init(int fd1, int fd2) {
	eodFd = fd1;
	eodMgmtFd = fd2;
	fcntl(eodMgmtFd,F_SETFL,O_NONBLOCK);
}

void ExtOsdep::started(int *f, void **cp) {
	*f = eodMgmtFd;
	*cp = (void *)eodMgmtFd;

	unsigned char msg = ZT_EOD_MSG_STARTED;
	Mutex::Lock l(eodMutex);
	__eodSend(msg);
}

static std::string mgmtrd;
static std::string mgmtwr;

bool ExtOsdep::mgmtWritable(void *cookie) {
	if (cookie != (void *)eodMgmtFd) return false;
	if (mgmtwr.size() == 0) return true;
	auto sz = write(eodMgmtFd, mgmtwr.data(), mgmtwr.size());
	if (sz <= 0) return false;
	mgmtwr.erase(mgmtwr.begin(), mgmtwr.begin() + sz);
	return mgmtwr.empty();
}

bool ExtOsdep::mgmtRecv(void *cookie, void *data, unsigned long len,
		std::function<unsigned (unsigned, const std::string &, const std::string &, std::string &)> cb) {
	if (cookie != (void *)eodMgmtFd) return false;
	mgmtrd.append((char *)data, len);
	while (1) {
		auto req = (zt_eod_mgmt_req *)mgmtrd.data();
		if (mgmtrd.size() < sizeof(*req)) break;
		unsigned reqsz = sizeof(*req) + req->pathlen + req->datalen;
		if (mgmtrd.size() < reqsz) break;

		std::string resp;
		char *p = (char *)req->data;
		zt_eod_mgmt_reply rep;
		rep.scode = cb(req->method, std::string(p, p + req->pathlen),
			std::string(p + req->pathlen, p + req->pathlen + req->datalen), resp);
		rep.datalen = resp.size();

		mgmtrd.erase(mgmtrd.begin(), mgmtrd.begin() + reqsz);

		mgmtwr.append((char *)&rep, sizeof(rep));
		mgmtwr.append(resp);

		auto sz = write(eodMgmtFd, mgmtwr.data(), mgmtwr.size());
		if (sz > 0) mgmtwr.erase(mgmtwr.begin(), mgmtwr.begin() + sz);
	}
	return !mgmtwr.empty();
}

void ExtOsdep::routeAddDel(bool add, const InetAddress &target, const InetAddress &via, const InetAddress &src, const char *ifname) {
	Mutex::Lock l(eodMutex);

	std::string ifn;
	if (ifname) ifn = ifname;
	if (add) {
		for (auto x = allRoutes.begin(); x != allRoutes.end(); ++x) {
			if (x->target == target && x->via == via
				&& x->src == src && x->ifname == ifn) return;
		}
		allRoutes.push_back({target, via, src, ifn});
	}
	else {
		bool found = false;
		for (auto x = allRoutes.begin(); x != allRoutes.end(); ++x) {
			if (x->target == target && x->via == via
				&& x->src == src && x->ifname == ifn) {
				allRoutes.erase(x);
				found = true;
				break;
			}
		}
		if (!found) return;
	}

	zt_eod_msg_route req;
	memset(&req, 0, sizeof(req));
	req.cmd = add ? ZT_EOD_MSG_ADDROUTE : ZT_EOD_MSG_DELROUTE;
	req.afi = target.isV4() ? 1 : 2;
	req.dstlen = target.netmaskBits();
	memcpy(req.dst, target.rawIpData(), target.isV4() ? 4 : 16);
	if (ifname) strncpyx(req.dev, ifname, sizeof(req.dev));
	if (via) memcpy(req.gw, via.rawIpData(), target.isV4() ? 4 : 16);
	if (src) memcpy(req.src, src.rawIpData(), target.isV4() ? 4 : 16);

	unsigned char resp;
	__eodXchg(req, add ? ZT_EOD_MSG_ADDROUTERESP : ZT_EOD_MSG_DELROUTERESP, resp);
}

bool ExtOsdep::getBindAddrs(std::map<InetAddress,std::string> &ret) {
	Mutex::Lock l(eodMutex);

	unsigned char req = ZT_EOD_MSG_GETBINDADDRS;
	__eodSend(req);

	zt_eod_msg_getbindaddrsresp *resp;
	unsigned char buf[ZT_EOD_MAXMSGSIZE];
	int r = __eodWait(ZT_EOD_MSG_GETBINDADDRSRESP, (unsigned char *)buf, sizeof(*resp), sizeof(buf));
	if (r < (int)sizeof(*resp)) return false;

	int c = (r - (int)sizeof(*resp)) / sizeof(resp->addrs[0]);
	resp = (zt_eod_msg_getbindaddrsresp *)buf;
	for (int i = 0; i < c; ++i) {
		ret[InetAddress(resp->addrs[i].data, resp->addrs[i].afi == 1 ? 4 : 16, resp->addrs[i].len)]
			= resp->addrs[i].ifname;
	}

	return resp->result;
}

ExtOsdepTap::ExtOsdepTap(
                const char *homePath,
                const MAC &mac,
                unsigned int mtu,
                unsigned int metric,
                uint64_t nwid,
                const char *friendlyName,
                void (*handler)(void *,void *,uint64_t,const MAC &,const MAC &,unsigned int,unsigned int,const void *,unsigned int),
                void *arg) :
        _handler(handler),
        _arg(arg),
        _nwid(nwid),
        _mac(mac),
        _homePath(homePath),
        _mtu(mtu),
        _fd(0),
        _enabled(true),
        _run(true)
 {
	zt_eod_msg_addtap req;
	req.cmd = ZT_EOD_MSG_ADDTAP;
	req.nwid = nwid;
	req.mtu = mtu;
	req.metric = metric;
	strncpyx(req.fname, friendlyName, sizeof(req.fname));
	mac.copyTo(req.mac, 6);

	zt_eod_msg_addtapresp resp;

	Mutex::Lock l(eodMutex);
	__eodSend(req);
	_fd = -1;
	if (__eodWait(ZT_EOD_MSG_ADDTAPRESP, (unsigned char *)&resp, sizeof(resp), sizeof(resp), &_fd) != sizeof(resp))
		throw std::runtime_error(std::string("could not create TAP"));

	_dev = resp.name;
	if (_dev.empty() || _fd < 0)
		throw std::runtime_error(std::string("could not create TAP"));

	fcntl(_fd,F_SETFL,O_NONBLOCK);

	// processing shamelessly copied from LinuxEthernetTap
        (void)::pipe(_shutdownSignalPipe);
        for(unsigned int t=0;t<2;++t) {
                _tapReaderThread[t] = std::thread([this, t]{
                        fd_set readfds,nullfds;
                        int n,nfds,r;
                        void *buf = nullptr;
                        std::vector<void *> buffers;

                        if (!_run)
                                return;

                        FD_ZERO(&readfds);
                        FD_ZERO(&nullfds);
                        nfds = (int)std::max(_shutdownSignalPipe[0],_fd) + 1;

                        r = 0;
                        for(;;) {
                                FD_SET(_shutdownSignalPipe[0],&readfds);
                                FD_SET(_fd,&readfds);
                                select(nfds,&readfds,&nullfds,&nullfds,(struct timeval *)0);

                                if (FD_ISSET(_shutdownSignalPipe[0],&readfds)) // writes to shutdown pipe terminate thread
                                        break;

                                if (FD_ISSET(_fd,&readfds)) {
                                        for(;;) { // read until there are no more packets, then return to outer select() loop
                                                if (!buf) {
                                                        // To reduce use of the mutex, we keep a local buffer vector and
                                                        // swap (which is a pointer swap) with the global one when it's
                                                        // empty. This retrieves a batch of buffers to use.
                                                        if (buffers.empty()) {
                                                                std::lock_guard<std::mutex> l(_buffers_l);
                                                                buffers.swap(_buffers);
                                                        }
                                                        if (buffers.empty()) {
                                                                buf = malloc(ZT_TAP_BUF_SIZE);
                                                                if (!buf)
                                                                        break;
                                                        } else {
                                                                buf = buffers.back();
                                                                buffers.pop_back();
                                                        }
                                                }

                                                n = (int)::read(_fd,reinterpret_cast<uint8_t *>(buf) + r,ZT_TAP_BUF_SIZE - r);
                                                if (n > 0) {
                                                        // Some tap drivers like to send the ethernet frame and the
                                                        // payload in two chunks, so handle that by accumulating
                                                        // data until we have at least a frame.
                                                        r += n;
                                                        if (r > 14) {
                                                                if (r > ((int)_mtu + 14)) // sanity check for weird TAP behavior on some platforms
                                                                        r = _mtu + 14;

                                                                if (_enabled && _tapqsize.load() < 1000) {
									++_tapqsize;
                                                                        _tapq.post(std::pair<void *,int>(buf,r));
                                                                        buf = nullptr;
                                                                }

                                                                r = 0;
                                                        }
                                                } else {
                                                        r = 0;
                                                        break;
                                                }
                                        }
                                }
                        }
                });
        }

        _tapProcessorThread = std::thread([this] {
                MAC to,from;
                std::pair<void *,int> qi;
                while (_tapq.get(qi)) {
			--_tapqsize;
                        uint8_t *const b = reinterpret_cast<uint8_t *>(qi.first);
                        if (b) {
                                to.setTo(b, 6);
                                from.setTo(b + 6, 6);
                                unsigned int etherType = Utils::ntoh(((const uint16_t *)b)[6]);
                                _handler(_arg, nullptr, _nwid, from, to, etherType, 0, (const void *)(b + 14),(unsigned int)(qi.second - 14));
                                {
                                        std::lock_guard<std::mutex> l(_buffers_l);
                                        if (_buffers.size() < 128)
                                                _buffers.push_back(qi.first);
                                        else free(qi.first);
                                }
                        } else break;
                }
        });
}

ExtOsdepTap::~ExtOsdepTap() {
        _run = false;

        (void)::write(_shutdownSignalPipe[1],"\0",1); // causes reader thread(s) to exit
        _tapq.post(std::pair<void *,int>(nullptr,0)); // causes processor thread to exit

        _tapReaderThread[0].join();
        _tapReaderThread[1].join();
        _tapProcessorThread.join();

        ::close(_fd);
        ::close(_shutdownSignalPipe[0]);
        ::close(_shutdownSignalPipe[1]);

        for(std::vector<void *>::iterator i(_buffers.begin());i!=_buffers.end();++i)
                free(*i);
        std::vector< std::pair<void *,int> > dv(_tapq.drain());
        for(std::vector< std::pair<void *,int> >::iterator i(dv.begin());i!=dv.end();++i) {
                if (i->first)
                        free(i->first);
        }

	zt_eod_msg_deltap req;
	req.cmd = ZT_EOD_MSG_DELTAP;
	strcpy(req.name, _dev.c_str());

	unsigned char resp;
	eodXchg(req, ZT_EOD_MSG_DELTAPRESP, resp);
}

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

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

void ExtOsdepTap::doRemoveIp(const InetAddress &ip) {
	zt_eod_msg_ip req;
	req.cmd = ZT_EOD_MSG_DELIP;
	strcpy(req.name, _dev.c_str());
	req.afi = ip.isV4() ? 1 : 2;
	req.len = ip.netmaskBits();
	memcpy(req.data, ip.rawIpData(), ip.isV4() ? 4 : 16);

	unsigned char resp;
	__eodXchg(req, ZT_EOD_MSG_DELIPRESP, resp);
}

bool ExtOsdepTap::addIp(const InetAddress &ip) {
	Mutex::Lock l(eodMutex);

        for(auto i = allIps.begin();i!=allIps.end();++i) {
		if (*i == ip) return true;
                if (i->ipsEqual(ip)) doRemoveIp(*i);
        }

	zt_eod_msg_ip req;
	req.cmd = ZT_EOD_MSG_ADDIP;
	strcpy(req.name, _dev.c_str());
	req.afi = ip.isV4() ? 1 : 2;
	req.len = ip.netmaskBits();
	memcpy(req.data, ip.rawIpData(), ip.isV4() ? 4 : 16);

	unsigned char resp;
	__eodXchg(req, ZT_EOD_MSG_ADDIPRESP, resp);

	allIps.push_back(ip);

	return true;
}
bool ExtOsdepTap::addIps(std::vector<InetAddress> ips) {
	return false;
}
bool ExtOsdepTap::removeIp(const InetAddress &ip) {
	Mutex::Lock l(eodMutex);
        for(auto i = allIps.begin();i!=allIps.end();++i) {
		if (*i == ip) {
			doRemoveIp(*i);
			return true;
		}
        }
	return false;
}
std::vector<InetAddress> ExtOsdepTap::ips() const {
	std::vector<InetAddress> ret;

	Mutex::Lock l(eodMutex);

	zt_eod_msg_getips req;
	req.cmd = ZT_EOD_MSG_GETIPS;
	strcpy(req.name, _dev.c_str());
	__eodSend(req);

	zt_eod_msg_getipsresp *resp;
	unsigned char buf[ZT_EOD_MAXMSGSIZE];
	int r = __eodWait(ZT_EOD_MSG_GETIPSRESP, (unsigned char *)buf, sizeof(*resp), sizeof(buf));
	if (r < (int)sizeof(*resp)) return ret;

	int c = (r - (int)sizeof(*resp)) / sizeof(resp->addrs[0]);
	resp = (zt_eod_msg_getipsresp *)buf;
	for (int i = 0; i < c; ++i) {
		ret.push_back(InetAddress(resp->addrs[i].data, resp->addrs[i].afi == 1 ? 4 : 16, resp->addrs[i].len));
	}

	return ret;
}
void ExtOsdepTap::put(const MAC &from,const MAC &to,unsigned int etherType,const void *data,unsigned int len) {
        char putBuf[ZT_MAX_MTU + 64];
        if ((_fd > 0)&&(len <= _mtu)&&(_enabled)) {
                to.copyTo(putBuf,6);
                from.copyTo(putBuf + 6,6);
                *((uint16_t *)(putBuf + 12)) = htons((uint16_t)etherType);
                memcpy(putBuf + 14,data,len);
                len += 14;
                (void)::write(_fd,putBuf,len);
        }
}
std::string ExtOsdepTap::deviceName() const {
	return _dev;
}
void ExtOsdepTap::setFriendlyName(const char *friendlyName) {}

void ExtOsdepTap::scanMulticastGroups(std::vector<MulticastGroup> &added,std::vector<MulticastGroup> &removed) {
        char *ptr,*ptr2;
        unsigned char mac[6];
        std::vector<MulticastGroup> newGroups;

        int fd = ::open("/proc/net/dev_mcast",O_RDONLY);
        if (fd > 0) {
                char buf[131072];
                int n = (int)::read(fd,buf,sizeof(buf));
                if ((n > 0)&&(n < (int)sizeof(buf))) {
                        buf[n] = (char)0;
                        for(char *l=strtok_r(buf,"\r\n",&ptr);(l);l=strtok_r((char *)0,"\r\n",&ptr)) {
                                int fno = 0;
                                char *devname = (char *)0;
                                char *mcastmac = (char *)0;
                                for(char *f=strtok_r(l," \t",&ptr2);(f);f=strtok_r((char *)0," \t",&ptr2)) {
                                        if (fno == 1)
                                                devname = f;
                                        else if (fno == 4)
                                                mcastmac = f;
                                        ++fno;
                                }
                                if ((devname)&&(!strcmp(devname,_dev.c_str()))&&(mcastmac)&&(Utils::unhex(mcastmac,mac,6) == 6))
                                        newGroups.push_back(MulticastGroup(MAC(mac,6),0));
                        }
                }
                ::close(fd);
        }

        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());
        newGroups.erase(std::unique(newGroups.begin(),newGroups.end()),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 ExtOsdepTap::setMtu(unsigned int mtu) {
	if (mtu == _mtu) return;
	_mtu = mtu;

	zt_eod_msg_setmtu req;
	req.cmd = ZT_EOD_MSG_SETMTU;
	strcpy(req.name, _dev.c_str());
	req.mtu = mtu;

	unsigned char resp;
	eodXchg(req, ZT_EOD_MSG_SETMTURESP, resp);
}

} // namespace ZeroTier