ZeroTierOne/osdep/LinuxNetLink.cpp

/*
 * Copyright (c)2019 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.
 */
/****/

#include "../node/Constants.hpp"

#include <cerrno>

//#define ZT_NETLINK_TRACE

#ifdef __LINUX__

#include "LinuxNetLink.hpp"

#include <unistd.h>
#include <linux/if_tun.h>

#ifndef IFNAMSIZ
#define IFNAMSIZ 16
#endif
const int ZT_RTE_METRIC = 5000;

namespace ZeroTier {

struct nl_route_req {
	struct nlmsghdr nl;
	struct rtmsg rt;
	char buf[8192];
};

struct nl_if_req {
	struct nlmsghdr nl;
	struct ifinfomsg ifa;
	char buf[8192];
};

struct nl_adr_req {
	struct nlmsghdr nl;
	struct ifaddrmsg ifa;
	char buf[8192];
};

LinuxNetLink::LinuxNetLink()
	: _t()
	, _running(false)
	, _seq(0)
	, _interfaces()
	, _if_m()
	, _fd(socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE))
	, _la({0})
{
	// set socket timeout to 1 sec so we're not permablocking recv() calls
	_setSocketTimeout(_fd, 1);

	_la.nl_family = AF_NETLINK;
	_la.nl_pid = 0; //getpid()+1;
	_la.nl_groups = RTMGRP_LINK|RTMGRP_IPV4_IFADDR|RTMGRP_IPV6_IFADDR|RTMGRP_IPV4_ROUTE|RTMGRP_IPV6_ROUTE|RTMGRP_NOTIFY;
	if (bind(_fd, (struct sockaddr*)&_la, sizeof(_la))) {
		fprintf(stderr, "Error connecting to RTNETLINK: %s\n", strerror(errno));
		::exit(1);
	}

	_requestIPv4Routes();
	_requestIPv6Routes();
	_requestInterfaceList();

	_running = true;
	_t = Thread::start(this);
}

LinuxNetLink::~LinuxNetLink()
{
	_running = false;
	Thread::join(_t);
	::close(_fd);
}

void LinuxNetLink::_setSocketTimeout(int fd, int seconds)
{
	struct timeval tv;
	tv.tv_sec = seconds;
	tv.tv_usec = 0;
	if(setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, (const char*)&tv, sizeof(tv)) != 0) {
#ifdef ZT_NETLINK_TRACE
		fprintf(stderr, "setsockopt failed: %s\n", strerror(errno));
#endif
	}
}

#define ZT_NL_BUF_SIZE 16384
int LinuxNetLink::_doRecv(int fd)
{
	char *buf = nullptr;
	if (posix_memalign((void **)&buf,16,ZT_NL_BUF_SIZE) != 0) {
		fprintf(stderr,"malloc failed!\n");
		::exit(1);
	}
	if (!buf) {
		fprintf(stderr,"malloc failed!\n");
		::exit(1);
	}

	char *p = NULL;
	struct nlmsghdr *nlp;
	int nll = 0;
	int rtn = 0;
	p = buf;

	for(;;) {
		rtn = recv(fd, p, ZT_NL_BUF_SIZE - nll, 0);

		if (rtn > 0) {
			nlp = (struct nlmsghdr *)p;

			if(nlp->nlmsg_type == NLMSG_ERROR && (nlp->nlmsg_flags & NLM_F_ACK) != NLM_F_ACK) {
				struct nlmsgerr *err = (struct nlmsgerr*)NLMSG_DATA(nlp);
				if (err->error != 0) {
#ifdef ZT_NETLINK_TRACE
					fprintf(stderr, "rtnetlink error: %s\n", strerror(-(err->error)));
#endif
				}
				p = buf;
				nll = 0;
				break;
			}

			if (nlp->nlmsg_type == NLMSG_NOOP) {
				break;
			}

			if( (nlp->nlmsg_flags & NLM_F_MULTI) == NLM_F_MULTI || (nlp->nlmsg_type == NLMSG_DONE))
			{
				if (nlp->nlmsg_type == NLMSG_DONE) {
					_processMessage(nlp, nll);
					p = buf;
					nll = 0;
					break;
				}
				p += rtn;
				nll += rtn;
			}

			if (nlp->nlmsg_type == NLMSG_OVERRUN) {
#ifdef ZT_NETLINK_TRACE
				fprintf(stderr, "NLMSG_OVERRUN: Data lost\n");
#endif
				p = buf;
				nll = 0;
				break;
			}

			nll += rtn;

			_processMessage(nlp, nll);

			p = buf;
			nll = 0;
			break;
		} else {
			break;
		}
	}

	free(buf);

	return rtn;
}

void LinuxNetLink::threadMain() throw()
{
	int rtn = 0;
	while(_running) {
		rtn = _doRecv(_fd);
		if (rtn <= 0) {
			Thread::sleep(250);
			continue;
		}
	}
}

void LinuxNetLink::_processMessage(struct nlmsghdr *nlp, int nll)
{
	for(; NLMSG_OK(nlp, nll); nlp=NLMSG_NEXT(nlp, nll))
	{
		switch(nlp->nlmsg_type)
		{
		case RTM_NEWLINK:
			_linkAdded(nlp);
			break;
		case RTM_DELLINK:
			_linkDeleted(nlp);
			break;
		case RTM_NEWADDR:
			_ipAddressAdded(nlp);
			break;
		case RTM_DELADDR:
			_ipAddressDeleted(nlp);
			break;
		case RTM_NEWROUTE:
			_routeAdded(nlp);
			break;
		case RTM_DELROUTE:
			_routeDeleted(nlp);
			break;
		default:
			break;
		}
	}
}

void LinuxNetLink::_ipAddressAdded(struct nlmsghdr *nlp)
{
#ifdef ZT_NETLINK_TRACE
	struct ifaddrmsg *ifap = (struct ifaddrmsg *)NLMSG_DATA(nlp);
	struct rtattr *rtap = (struct rtattr *)IFA_RTA(ifap);
	int ifal = IFA_PAYLOAD(nlp);

	char addr[40] = {0};
	char local[40] = {0};
	char label[40] = {0};
	char bcast[40] = {0};

	for(;RTA_OK(rtap, ifal); rtap=RTA_NEXT(rtap,ifal))
	{
		switch(rtap->rta_type) {
		case IFA_ADDRESS:
			inet_ntop(ifap->ifa_family, RTA_DATA(rtap), addr, 40);
			break;
		case IFA_LOCAL:
			inet_ntop(ifap->ifa_family, RTA_DATA(rtap), local, 40);
			break;
		case IFA_LABEL:
			memcpy(label, RTA_DATA(rtap), 40);
			break;
		case IFA_BROADCAST:
			inet_ntop(ifap->ifa_family, RTA_DATA(rtap), bcast, 40);
			break;
		}
	}

	fprintf(stderr,"Added IP Address %s local: %s label: %s broadcast: %s\n", addr, local, label, bcast);
#endif
}

void LinuxNetLink::_ipAddressDeleted(struct nlmsghdr *nlp)
{
#ifdef ZT_NETLINK_TRACE
	struct ifaddrmsg *ifap = (struct ifaddrmsg *)NLMSG_DATA(nlp);
	struct rtattr *rtap = (struct rtattr *)IFA_RTA(ifap);
	int ifal = IFA_PAYLOAD(nlp);

	char addr[40] = {0};
	char local[40] = {0};
	char label[40] = {0};
	char bcast[40] = {0};

	for(;RTA_OK(rtap, ifal); rtap=RTA_NEXT(rtap,ifal))
	{
		switch(rtap->rta_type) {
		case IFA_ADDRESS:
			inet_ntop(ifap->ifa_family, RTA_DATA(rtap), addr, 40);
			break;
		case IFA_LOCAL:
			inet_ntop(ifap->ifa_family, RTA_DATA(rtap), local, 40);
			break;
		case IFA_LABEL:
			memcpy(label, RTA_DATA(rtap), 40);
			break;
		case IFA_BROADCAST:
			inet_ntop(ifap->ifa_family, RTA_DATA(rtap), bcast, 40);
			break;
		}
	}

	fprintf(stderr, "Removed IP Address %s local: %s label: %s broadcast: %s\n", addr, local, label, bcast);
#endif
}

void LinuxNetLink::_routeAdded(struct nlmsghdr *nlp)
{
	char dsts[40] = {0};
	char gws[40] = {0};
	char srcs[40] = {0};
	char ifs[16] = {0};
	char ms[24] = {0};

	struct rtmsg *rtp = (struct rtmsg *)NLMSG_DATA(nlp);
	struct rtattr *rtap = (struct rtattr *)RTM_RTA(rtp);
	int rtl = RTM_PAYLOAD(nlp);

	Route r;
	bool wecare = false;

	for(;RTA_OK(rtap, rtl); rtap=RTA_NEXT(rtap, rtl))
	{
		switch(rtap->rta_type)
		{
		case RTA_DST:
			switch(rtp->rtm_family) {
				case AF_INET:
					inet_ntop(rtp->rtm_family, RTA_DATA(rtap), dsts, 24);
					r.target.set(RTA_DATA(rtap), 4, 0);
					wecare = true;
					break;
				case AF_INET6:
					inet_ntop(rtp->rtm_family, RTA_DATA(rtap), dsts, 24);
					r.target.set(RTA_DATA(rtap), 16, 0);
					wecare = true;
					break;
			}
			break;
		case RTA_SRC:
			switch(rtp->rtm_family) {
				case AF_INET:
					inet_ntop(rtp->rtm_family, RTA_DATA(rtap), srcs, 24);
					r.src.set(RTA_DATA(rtap), 4, 0);
					wecare = true;
					break;
				case AF_INET6:
					inet_ntop(rtp->rtm_family, RTA_DATA(rtap), srcs, 24);
					r.src.set(RTA_DATA(rtap), 16, 0);
					wecare = true;
					break;
			}
			break;
		case RTA_GATEWAY:
			switch(rtp->rtm_family) {
				case AF_INET:
					inet_ntop(rtp->rtm_family, RTA_DATA(rtap), gws, 24);
					r.via.set(RTA_DATA(rtap), 4, 0);
					wecare = true;
					break;
				case AF_INET6:
					inet_ntop(rtp->rtm_family, RTA_DATA(rtap), gws, 24);
					r.via.set(RTA_DATA(rtap), 16, 0);
					wecare = true;
					break;
			}
			break;
		case RTA_OIF:
			switch(rtp->rtm_family) {
				case AF_INET:
					r.ifidx = *((int*)RTA_DATA(rtap));
					wecare = true;
					break;
				case AF_INET6:
					r.ifidx = *((int*)RTA_DATA(rtap));
					wecare = true;
					break;
			}
			sprintf(ifs, "%d", *((int*)RTA_DATA(rtap)));
			break;
		}
	}

	if (wecare) {
		Mutex::Lock rl(_routes_m);
		_routes[r.target].insert(r);
	}

#ifdef ZT_NETLINK_TRACE
	sprintf(ms, "%d", rtp->rtm_dst_len);
	fprintf(stderr, "Route Added: dst %s/%s gw %s src %s if %s\n", dsts, ms, gws, srcs, ifs);
#endif
}

void LinuxNetLink::_routeDeleted(struct nlmsghdr *nlp)
{
	char dsts[40] = {0};
	char gws[40] = {0};
	char srcs[40] = {0};
	char ifs[16] = {0};
	char ms[24] = {0};

	struct rtmsg *rtp = (struct rtmsg *) NLMSG_DATA(nlp);
	struct rtattr *rtap = (struct rtattr *)RTM_RTA(rtp);
	int rtl = RTM_PAYLOAD(nlp);

	Route r;
	bool wecare = false;

	for(;RTA_OK(rtap, rtl); rtap=RTA_NEXT(rtap, rtl))
	{
		switch(rtap->rta_type)
		{
		case RTA_DST:
			switch(rtp->rtm_family) {
				case AF_INET:
					inet_ntop(rtp->rtm_family, RTA_DATA(rtap), dsts, 24);
					r.target.set(RTA_DATA(rtap), 4, 0);
					wecare = true;
					break;
				case AF_INET6:
					inet_ntop(rtp->rtm_family, RTA_DATA(rtap), dsts, 24);
					r.target.set(RTA_DATA(rtap), 16, 0);
					wecare = true;
					break;
			}
			break;
		case RTA_SRC:
			switch(rtp->rtm_family) {
				case AF_INET:
					inet_ntop(rtp->rtm_family, RTA_DATA(rtap), srcs, 24);
					r.src.set(RTA_DATA(rtap), 4, 0);
					wecare = true;
					break;
				case AF_INET6:
					inet_ntop(rtp->rtm_family, RTA_DATA(rtap), srcs, 24);
					r.src.set(RTA_DATA(rtap), 16, 0);
					wecare = true;
					break;
			}
			break;
		case RTA_GATEWAY:
			switch(rtp->rtm_family) {
				case AF_INET:
					inet_ntop(rtp->rtm_family, RTA_DATA(rtap), gws, 24);
					r.via.set(RTA_DATA(rtap), 4, 0);
					wecare = true;
					break;
				case AF_INET6:
					inet_ntop(rtp->rtm_family, RTA_DATA(rtap), gws, 24);
					r.via.set(RTA_DATA(rtap), 16, 0);
					wecare = true;
					break;
			}
			break;
		case RTA_OIF:
			switch(rtp->rtm_family) {
				case AF_INET:
					r.ifidx = *((int*)RTA_DATA(rtap));
					wecare = true;
					break;
				case AF_INET6:
					r.ifidx = *((int*)RTA_DATA(rtap));
					wecare = true;
					break;
			}
			sprintf(ifs, "%d", *((int*)RTA_DATA(rtap)));
			break;
		}
	}

	if (wecare) {
		Mutex::Lock rl(_routes_m);
		_routes[r.target].erase(r);
	}

#ifdef ZT_NETLINK_TRACE
	sprintf(ms, "%d", rtp->rtm_dst_len);
	fprintf(stderr, "Route Deleted: dst %s/%s gw %s src %s if %s\n", dsts, ms, gws, srcs, ifs);
#endif
}

void LinuxNetLink::_linkAdded(struct nlmsghdr *nlp)
{
	unsigned char mac_bin[6] = {0};
	unsigned int mtu = 0;
	char ifname[IFNAMSIZ] = {0};

	struct ifinfomsg *ifip = (struct ifinfomsg *)NLMSG_DATA(nlp);
	struct rtattr *rtap = (struct rtattr *)IFLA_RTA(ifip);
	int ifil = RTM_PAYLOAD(nlp);

	const char *ptr = (const char *)0;
	for(;RTA_OK(rtap, ifil);rtap=RTA_NEXT(rtap, ifil))
	{
		switch(rtap->rta_type) {
		case IFLA_ADDRESS:
			ptr = (const char *)RTA_DATA(rtap);
			memcpy(mac_bin, ptr, 6);
			break;
		case IFLA_IFNAME:
			ptr = (const char *)RTA_DATA(rtap);
			memcpy(ifname, ptr, strlen(ptr));
			break;
		case IFLA_MTU:
			memcpy(&mtu, RTA_DATA(rtap), sizeof(unsigned int));
			break;
		}
	}

	{
		Mutex::Lock l(_if_m);
		struct iface_entry &entry = _interfaces[ifip->ifi_index];
		entry.index = ifip->ifi_index;
		memcpy(entry.ifacename, ifname, sizeof(ifname));
		snprintf(entry.mac,sizeof(entry.mac),"%.02x:%.02x:%.02x:%.02x:%.02x:%.02x",(unsigned int)mac_bin[0],(unsigned int)mac_bin[1],(unsigned int)mac_bin[2],(unsigned int)mac_bin[3],(unsigned int)mac_bin[4],(unsigned int)mac_bin[5]);
		memcpy(entry.mac_bin, mac_bin, 6);
		entry.mtu = mtu;
	}
}

void LinuxNetLink::_linkDeleted(struct nlmsghdr *nlp)
{
	unsigned int mtu = 0;
	char ifname[40] = {0};

	struct ifinfomsg *ifip = (struct ifinfomsg *)NLMSG_DATA(nlp);
	struct rtattr *rtap = (struct rtattr *)IFLA_RTA(ifip);
	int ifil = RTM_PAYLOAD(nlp);

	const char *ptr = (const char *)0;
	for(;RTA_OK(rtap, ifil);rtap=RTA_NEXT(rtap, ifil))
	{
		switch(rtap->rta_type) {
		case IFLA_IFNAME:
			ptr = (const char*)RTA_DATA(rtap);
			memcpy(ifname, ptr, strlen(ptr));
			break;
		case IFLA_MTU:
			memcpy(&mtu, RTA_DATA(rtap), sizeof(unsigned int));
			break;
		}
	}

	{
		Mutex::Lock l(_if_m);
		if(_interfaces.contains(ifip->ifi_index)) {
			_interfaces.erase(ifip->ifi_index);
		}
	}
}

void LinuxNetLink::_requestIPv4Routes()
{
	int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
	if (fd == -1) {
		fprintf(stderr, "Error opening RTNETLINK socket: %s\n", strerror(errno));
		return;
	}

	_setSocketTimeout(fd);

	struct sockaddr_nl la;
	la.nl_family = AF_NETLINK;
	la.nl_pid = 0; //getpid();
	la.nl_groups = RTMGRP_IPV4_ROUTE;
	if(bind(fd, (struct sockaddr*)&la, sizeof(la))) {
		fprintf(stderr, "Error binding RTNETLINK (_requestIPv4Routes #1): %s\n", strerror(errno));
		close(fd);
		return;
	}

	struct nl_route_req req;
	bzero(&req, sizeof(req));
	req.nl.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg));
	req.nl.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
	req.nl.nlmsg_type = RTM_GETROUTE;
	req.nl.nlmsg_pid = 0;
	req.nl.nlmsg_seq = ++_seq;
	req.rt.rtm_family = AF_INET;
	req.rt.rtm_table = RT_TABLE_MAIN;

	struct sockaddr_nl pa;
	bzero(&pa, sizeof(pa));
	pa.nl_family = AF_NETLINK;

	struct msghdr msg;
	bzero(&msg, sizeof(msg));
	msg.msg_name = (void*)&pa;
	msg.msg_namelen = sizeof(pa);

	struct iovec iov;
	bzero(&iov, sizeof(iov));
	iov.iov_base = (void*)&req.nl;
	iov.iov_len = req.nl.nlmsg_len;
	msg.msg_iov = &iov;
	msg.msg_iovlen = 1;

	sendmsg(fd, &msg, 0);

	_doRecv(fd);

	close(fd);
}

void LinuxNetLink::_requestIPv6Routes()
{
	int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
	if (fd == -1) {
		fprintf(stderr, "Error opening RTNETLINK socket: %s\n", strerror(errno));
		return;
	}

	_setSocketTimeout(fd);

	struct sockaddr_nl la;
	la.nl_family = AF_NETLINK;
	la.nl_pid = 0; //getpid();
	la.nl_groups = RTMGRP_IPV6_ROUTE;
	if(bind(fd, (struct sockaddr*)&la, sizeof(struct sockaddr_nl))) {
		fprintf(stderr, "Error binding RTNETLINK (_requestIPv6Routes #1): %s\n", strerror(errno));
		close(fd);
		return;
	}

	struct nl_route_req req;
	bzero(&req, sizeof(req));
	req.nl.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg));
	req.nl.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
	req.nl.nlmsg_type = RTM_GETROUTE;
	req.nl.nlmsg_pid = 0;
	req.nl.nlmsg_seq = ++_seq;
	req.rt.rtm_family = AF_INET6;
	req.rt.rtm_table = RT_TABLE_MAIN;

	struct sockaddr_nl pa;
	bzero(&pa, sizeof(pa));
	pa.nl_family = AF_NETLINK;

	struct msghdr msg;
	bzero(&msg, sizeof(msg));
	msg.msg_name = (void*)&pa;
	msg.msg_namelen = sizeof(pa);

	struct iovec iov;
	bzero(&iov, sizeof(iov));
	iov.iov_base = (void*)&req.nl;
	iov.iov_len = req.nl.nlmsg_len;
	msg.msg_iov = &iov;
	msg.msg_iovlen = 1;

	sendmsg(fd, &msg, 0);

	_doRecv(fd);

	close(fd);
}

void LinuxNetLink::_requestInterfaceList()
{
	int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
	if (fd == -1) {
		fprintf(stderr, "Error opening RTNETLINK socket: %s\n", strerror(errno));
		return;
	}

	_setSocketTimeout(fd);

	struct sockaddr_nl la;
	la.nl_family = AF_NETLINK;
	la.nl_pid = 0; //getpid();
	la.nl_groups = RTMGRP_LINK;
	if(bind(fd, (struct sockaddr*)&la, sizeof(struct sockaddr_nl))) {
		fprintf(stderr, "Error binding RTNETLINK (_requestInterfaceList #1): %s\n", strerror(errno));
		close(fd);
		return;
	}

	struct nl_if_req req;
	bzero(&req, sizeof(req));
	req.nl.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
	req.nl.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
	req.nl.nlmsg_type = RTM_GETLINK;
	req.nl.nlmsg_pid = 0;
	req.nl.nlmsg_seq = ++_seq;
	req.ifa.ifi_family = AF_UNSPEC;

	struct sockaddr_nl pa;
	bzero(&pa, sizeof(pa));
	pa.nl_family = AF_NETLINK;

	struct msghdr msg;
	bzero(&msg, sizeof(msg));
	msg.msg_name = (void*)&pa;
	msg.msg_namelen = sizeof(pa);

	struct iovec iov;
	bzero(&iov, sizeof(iov));
	iov.iov_base = (void*)&req.nl;
	iov.iov_len = req.nl.nlmsg_len;
	msg.msg_iov = &iov;
	msg.msg_iovlen = 1;
	sendmsg(fd, &msg, 0);

	_doRecv(fd);

	close(fd);
}

void LinuxNetLink::addRoute(const InetAddress &target, const InetAddress &via, const InetAddress &src, const char *ifaceName)
{
	if (!target) return;

	int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
	if (fd == -1) {
		fprintf(stderr, "Error opening RTNETLINK socket: %s\n", strerror(errno));
		return;
	}

	_setSocketTimeout(fd);

	struct sockaddr_nl la;
	bzero(&la, sizeof(la));
	la.nl_family = AF_NETLINK;
	la.nl_pid = 0; //getpid();

	if(bind(fd, (struct sockaddr*)&la, sizeof(struct sockaddr_nl))) {
		fprintf(stderr, "Error binding RTNETLINK (addRoute #1): %s\n", strerror(errno));
		close(fd);
		return;
	}

#ifdef ZT_NETLINK_TRACE
	char  tmp[64];
	char tmp2[64];
	char tmp3[64];
	fprintf(stderr, "Adding Route. target: %s via: %s src: %s iface: %s\n", target.toString(tmp), via.toString(tmp2), src.toString(tmp3), ifaceName);
#endif

	int rtl = sizeof(struct rtmsg);
	struct nl_route_req req;
	bzero(&req, sizeof(req));

	struct rtattr *rtap = (struct rtattr *)req.buf;
	rtap->rta_type = RTA_DST;
	if (target.isV4()) {
		rtap->rta_len = RTA_LENGTH(sizeof(struct in_addr));
		memcpy(RTA_DATA(rtap), &((struct sockaddr_in*)&target)->sin_addr, sizeof(struct in_addr));
	} else {
		rtap->rta_len = RTA_LENGTH(sizeof(struct in6_addr));
		memcpy(RTA_DATA(rtap), &((struct sockaddr_in6*)&target)->sin6_addr, sizeof(struct in6_addr));
	}
	rtl += rtap->rta_len;

	if(via) {
		/*
		 *  Setting a metric keeps zerotier routes from taking priority over physical
		 *  At best the computer would use zerotier through the router instead of the LAN.
		 *  At worst it stops working at all.
		 *
		 *  default via 192.168.82.1 dev eth0 proto dhcp src 192.168.82.169 metric 202 
		 *  10.147.17.0/24 dev zt5u4uptmb proto kernel scope link src 10.147.17.94 
		 *  192.168.82.0/24 dev eth0 proto dhcp scope link src 192.168.82.169 metric 202 
		 *  192.168.82.0/24 via 10.147.17.1 dev zt5u4uptmb proto static metric 5000 
		 *  
		*/
		rtap = (struct rtattr*)(((char*)rtap) + rtap->rta_len);
		rtap->rta_type = RTA_PRIORITY;
		rtap->rta_len = RTA_LENGTH(sizeof(ZT_RTE_METRIC));
		memcpy(RTA_DATA(rtap), &ZT_RTE_METRIC, sizeof(ZT_RTE_METRIC));
		rtl += rtap->rta_len;

		rtap = (struct rtattr *)(((char*)rtap)+rtap->rta_len);
		rtap->rta_type = RTA_GATEWAY;
		if(via.isV4()) {
			rtap->rta_len = RTA_LENGTH(sizeof(struct in_addr));
			memcpy(RTA_DATA(rtap), &((struct sockaddr_in*)&via)->sin_addr, sizeof(struct in_addr));
		} else {
			rtap->rta_len = RTA_LENGTH(sizeof(struct in6_addr));
			memcpy(RTA_DATA(rtap), &((struct sockaddr_in6*)&via)->sin6_addr, sizeof(struct in6_addr));
		}
		rtl += rtap->rta_len;
	} else if (src) {
		rtap = (struct rtattr *)(((char*)rtap)+rtap->rta_len);
		rtap->rta_type = RTA_SRC;
		if(src.isV4()) {
			rtap->rta_len = RTA_LENGTH(sizeof(struct in_addr));
			memcpy(RTA_DATA(rtap), &((struct sockaddr_in*)&src)->sin_addr, sizeof(struct in_addr));

		} else {
			rtap->rta_len = RTA_LENGTH(sizeof(struct in6_addr));
			memcpy(RTA_DATA(rtap), &((struct sockaddr_in6*)&src)->sin6_addr, sizeof(struct in6_addr));
		}
		req.rt.rtm_src_len = src.netmaskBits();
	}

	if (ifaceName != NULL) {
		int interface_index = _indexForInterface(ifaceName);
		if (interface_index != -1) {
			rtap = (struct rtattr *) (((char*)rtap) + rtap->rta_len);
			rtap->rta_type = RTA_OIF;
			rtap->rta_len = RTA_LENGTH(sizeof(int));
			memcpy(RTA_DATA(rtap), &interface_index, sizeof(int));
			rtl += rtap->rta_len;
		}
	}

	req.nl.nlmsg_len = NLMSG_LENGTH(rtl);
	req.nl.nlmsg_flags = NLM_F_REQUEST | NLM_F_EXCL | NLM_F_CREATE | NLM_F_ACK;
	req.nl.nlmsg_type = RTM_NEWROUTE;
	req.nl.nlmsg_pid = 0;
	req.nl.nlmsg_seq = ++_seq;
	req.rt.rtm_family = target.ss_family;
	req.rt.rtm_table = RT_TABLE_MAIN;
	req.rt.rtm_protocol = RTPROT_STATIC;
	req.rt.rtm_scope = RT_SCOPE_UNIVERSE;
	req.rt.rtm_type = RTN_UNICAST;
	req.rt.rtm_dst_len = target.netmaskBits();
	req.rt.rtm_flags = 0;

	struct sockaddr_nl pa;
	bzero(&pa, sizeof(pa));
	pa.nl_family = AF_NETLINK;

	struct msghdr msg;
	bzero(&msg, sizeof(msg));
	msg.msg_name = (void*)&pa;
	msg.msg_namelen = sizeof(pa);

	struct iovec iov;
	bzero(&iov, sizeof(iov));
	iov.iov_base = (void*)&req.nl;
	iov.iov_len = req.nl.nlmsg_len;
	msg.msg_iov = &iov;
	msg.msg_iovlen = 1;
	sendmsg(fd, &msg, 0);

	_doRecv(fd);

	close(fd);
}

void LinuxNetLink::delRoute(const InetAddress &target, const InetAddress &via, const InetAddress &src, const char *ifaceName)
{
	if (!target) return;

	int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
	if (fd == -1) {
		fprintf(stderr, "Error opening RTNETLINK socket: %s\n", strerror(errno));
		return;
	}

	_setSocketTimeout(fd);

	struct sockaddr_nl la;
	la.nl_family = AF_NETLINK;
	la.nl_pid = 0; //getpid();

	if(bind(fd, (struct sockaddr*)&la, sizeof(struct sockaddr_nl))) {
		fprintf(stderr, "Error binding RTNETLINK (delRoute #1): %s\n", strerror(errno));
		close(fd);
		return;
	}

#ifdef ZT_NETLINK_TRACE
	char  tmp[64];
	char tmp2[64];
	char tmp3[64];
	fprintf(stderr, "Removing Route. target: %s via: %s src: %s iface: %s\n", target.toString(tmp), via.toString(tmp2), src.toString(tmp3), ifaceName);
#endif

	int rtl = sizeof(struct rtmsg);
	struct nl_route_req req;
	bzero(&req, sizeof(req));

	struct rtattr *rtap = (struct rtattr *)req.buf;
	rtap->rta_type = RTA_DST;
	if (target.isV4()) {
		rtap->rta_len = RTA_LENGTH(sizeof(struct in_addr));
		memcpy(RTA_DATA(rtap), &((struct sockaddr_in*)&target)->sin_addr, sizeof(struct in_addr));
	} else {
		rtap->rta_len = RTA_LENGTH(sizeof(struct in6_addr));
		memcpy(RTA_DATA(rtap), &((struct sockaddr_in6*)&target)->sin6_addr, sizeof(struct in6_addr));
	}
	rtl += rtap->rta_len;

	if(via) {
		rtap = (struct rtattr *)(((char*)rtap)+rtap->rta_len);
		rtap->rta_type = RTA_GATEWAY;
		if(via.isV4()) {
			rtap->rta_len = RTA_LENGTH(sizeof(struct in_addr));
			memcpy(RTA_DATA(rtap), &((struct sockaddr_in*)&via)->sin_addr, sizeof(struct in_addr));
		} else {
			rtap->rta_len = RTA_LENGTH(sizeof(struct in6_addr));
			memcpy(RTA_DATA(rtap), &((struct sockaddr_in6*)&via)->sin6_addr, sizeof(struct in6_addr));
		}
		rtl += rtap->rta_len;
	} else if (src) {
		rtap = (struct rtattr *)(((char*)rtap)+rtap->rta_len);
		rtap->rta_type = RTA_SRC;
		if(src.isV4()) {
			rtap->rta_len = RTA_LENGTH(sizeof(struct in_addr));
			memcpy(RTA_DATA(rtap), &((struct sockaddr_in*)&src)->sin_addr, sizeof(struct in_addr));

		} else {
			rtap->rta_len = RTA_LENGTH(sizeof(struct in6_addr));
			memcpy(RTA_DATA(rtap), &((struct sockaddr_in6*)&src)->sin6_addr, sizeof(struct in6_addr));
		}
		req.rt.rtm_src_len = src.netmaskBits();
	}

	if (ifaceName != NULL) {
		int interface_index = _indexForInterface(ifaceName);
		if (interface_index != -1) {
			rtap = (struct rtattr *) (((char*)rtap) + rtap->rta_len);
			rtap->rta_type = RTA_OIF;
			rtap->rta_len = RTA_LENGTH(sizeof(int));
			memcpy(RTA_DATA(rtap), &interface_index, sizeof(int));
			rtl += rtap->rta_len;
		}
	}

	req.nl.nlmsg_len = NLMSG_LENGTH(rtl);
	req.nl.nlmsg_flags = NLM_F_REQUEST;
	req.nl.nlmsg_type = RTM_DELROUTE;
	req.nl.nlmsg_pid = 0;
	req.nl.nlmsg_seq = ++_seq;
	req.rt.rtm_family = target.ss_family;
	req.rt.rtm_table = RT_TABLE_MAIN;
	req.rt.rtm_protocol = RTPROT_STATIC;
	req.rt.rtm_scope = RT_SCOPE_UNIVERSE;
	req.rt.rtm_type = RTN_UNICAST;
	req.rt.rtm_dst_len = target.netmaskBits();
	req.rt.rtm_flags = 0;

	struct sockaddr_nl pa;
	bzero(&pa, sizeof(pa));
	pa.nl_family = AF_NETLINK;

	struct msghdr msg;
	bzero(&msg, sizeof(msg));
	msg.msg_name = (void*)&pa;
	msg.msg_namelen = sizeof(pa);

	struct iovec iov;
	bzero(&iov, sizeof(iov));
	iov.iov_base = (void*)&req.nl;
	iov.iov_len = req.nl.nlmsg_len;
	msg.msg_iov = &iov;
	msg.msg_iovlen = 1;
	sendmsg(fd, &msg, 0);

	_doRecv(fd);

	close(fd);
}

void LinuxNetLink::addAddress(const InetAddress &addr, const char *iface)
{
	int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
	if (fd == -1) {
		fprintf(stderr, "Error opening RTNETLINK socket: %s\n", strerror(errno));
		return;
	}

	_setSocketTimeout(fd);

	struct sockaddr_nl la;
	memset(&la,0,sizeof(la));
	la.nl_family = AF_NETLINK;
	la.nl_pid = 0; //getpid();
	if (addr.isV4()) {
		la.nl_groups = RTMGRP_IPV4_IFADDR;
	} else {
		la.nl_groups = RTMGRP_IPV6_IFADDR;
	}

	if(bind(fd, (struct sockaddr*)&la, sizeof(struct sockaddr_nl))) {
		fprintf(stderr, "Error binding RTNETLINK (addAddress #1): %s\n", strerror(errno));
		close(fd);
		return;
	}

#ifdef ZT_NETLINK_TRACE
	char tmp[128];
	fprintf(stderr, "Adding IP address %s to interface %s\n", addr.toString(tmp), iface);
#endif

	int interface_index = _indexForInterface(iface);
	for (int reps = 0; interface_index == -1 && reps < 10; ++reps) {
		Thread::sleep(100);
		interface_index = _indexForInterface(iface);
	}

	if (interface_index == -1) {
		fprintf(stderr, "Unable to find index for interface %s\n", iface);
		close(fd);
		return;
	}

	int rtl = sizeof(struct ifaddrmsg);
	struct nl_adr_req req;
	bzero(&req, sizeof(struct nl_adr_req));

	struct rtattr *rtap = (struct rtattr *)req.buf;;
	if(addr.isV4()) {
		struct sockaddr_in *addr_v4 = (struct sockaddr_in*)&addr;
		rtap->rta_type = IFA_ADDRESS;
		rtap->rta_len = RTA_LENGTH(sizeof(struct in_addr));
		memcpy(RTA_DATA(rtap), &addr_v4->sin_addr, sizeof(struct in_addr));
		rtl += rtap->rta_len;

		rtap = (struct rtattr*)(((char*)rtap) + rtap->rta_len);
		rtap->rta_type = IFA_LOCAL;
		rtap->rta_len = RTA_LENGTH(sizeof(struct in_addr));
		memcpy(RTA_DATA(rtap), &addr_v4->sin_addr, sizeof(struct in_addr));
		rtl += rtap->rta_len;

		InetAddress broadcast = addr.broadcast();
		if(broadcast) {
			rtap = (struct rtattr*)(((char*)rtap)+rtap->rta_len);
			struct sockaddr_in *bcast = (struct sockaddr_in*)&broadcast;
			rtap->rta_type = IFA_BROADCAST;
			rtap->rta_len = RTA_LENGTH(sizeof(struct in_addr));
			memcpy(RTA_DATA(rtap), &bcast->sin_addr, sizeof(struct in_addr));
			rtl += rtap->rta_len;
		}
	} else { //V6
		rtap->rta_type = IFA_ADDRESS;
		struct sockaddr_in6 *addr_v6 = (struct sockaddr_in6*)&addr;
		rtap->rta_len = RTA_LENGTH(sizeof(struct in6_addr));
		memcpy(RTA_DATA(rtap), &addr_v6->sin6_addr, sizeof(struct in6_addr));
		rtl += rtap->rta_len;
	}

	if (iface) {
		rtap = (struct rtattr*)(((char*)rtap)+rtap->rta_len);
		rtap->rta_type = IFA_LABEL;
		rtap->rta_len = RTA_LENGTH(strlen(iface));
		memcpy(RTA_DATA(rtap), iface, strlen(iface));
		rtl += rtap->rta_len;
	}

	req.nl.nlmsg_len = NLMSG_LENGTH(rtl);
	req.nl.nlmsg_flags = NLM_F_REQUEST | NLM_F_CREATE | NLM_F_EXCL;
	req.nl.nlmsg_type = RTM_NEWADDR;
	req.nl.nlmsg_pid = 0;
	req.nl.nlmsg_seq = ++_seq;
	req.ifa.ifa_family = addr.ss_family;
	req.ifa.ifa_prefixlen = addr.port();
	req.ifa.ifa_flags = IFA_F_PERMANENT;
	req.ifa.ifa_scope = 0;
	req.ifa.ifa_index = interface_index;

	struct sockaddr_nl pa;
	bzero(&pa, sizeof(sockaddr_nl));
	pa.nl_family = AF_NETLINK;

	struct msghdr msg;
	bzero(&msg, sizeof(msg));
	msg.msg_name = (void*)&pa;
	msg.msg_namelen = sizeof(pa);

	struct iovec iov;
	iov.iov_base = (void*)&req.nl;
	iov.iov_len = req.nl.nlmsg_len;
	msg.msg_iov = &iov;
	msg.msg_iovlen = 1;
	sendmsg(fd, &msg, 0);

	_doRecv(fd);

	close(fd);
}

void LinuxNetLink::removeAddress(const InetAddress &addr, const char *iface)
{
	int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
	if (fd == -1) {
		fprintf(stderr, "Error opening RTNETLINK socket: %s\n", strerror(errno));
		return;
	}

	_setSocketTimeout(fd);

	struct sockaddr_nl la;
	la.nl_family = AF_NETLINK;
	la.nl_pid = 0; //getpid();
	if (addr.isV4()) {
		la.nl_groups = RTMGRP_IPV4_IFADDR;
	} else {
		la.nl_groups = RTMGRP_IPV6_IFADDR;
	}
	if(bind(fd, (struct sockaddr*)&la, sizeof(struct sockaddr_nl))) {
		fprintf(stderr, "Error binding RTNETLINK (removeAddress #1): %s\n", strerror(errno));
		close(fd);
		return;
	}

#ifdef ZT_NETLINK_TRACE
	char tmp[128];
	fprintf(stderr, "Removing IP address %s from interface %s\n", addr.toString(tmp), iface);
#endif

	int interface_index = _indexForInterface(iface);

	if (interface_index == -1) {
		fprintf(stderr, "Unable to find index for interface %s\n", iface);
		close(fd);
		return;
	}

	int rtl = sizeof(struct ifaddrmsg);
	struct nl_adr_req req;
	bzero(&req, sizeof(struct nl_adr_req));

	struct rtattr *rtap = (struct rtattr *)req.buf;
	if(addr.isV4()) {
		struct sockaddr_in *addr_v4 = (struct sockaddr_in*)&addr;
		rtap->rta_type = IFA_ADDRESS;
		rtap->rta_len = RTA_LENGTH(sizeof(struct in_addr));
		memcpy(RTA_DATA(rtap), &addr_v4->sin_addr, sizeof(struct in_addr));
		rtl += rtap->rta_len;

		rtap = (struct rtattr*)(((char*)rtap) + rtap->rta_len);
		rtap->rta_type = IFA_LOCAL;
		rtap->rta_len = RTA_LENGTH(sizeof(struct in_addr));
		memcpy(RTA_DATA(rtap), &addr_v4->sin_addr, sizeof(struct in_addr));
		rtl += rtap->rta_len;

		InetAddress broadcast = addr.broadcast();
		if(broadcast) {
			rtap = (struct rtattr*)(((char*)rtap)+rtap->rta_len);
			struct sockaddr_in *bcast = (struct sockaddr_in*)&broadcast;
			rtap->rta_type = IFA_BROADCAST;
			rtap->rta_len = RTA_LENGTH(sizeof(struct in_addr));
			memcpy(RTA_DATA(rtap), &bcast->sin_addr, sizeof(struct in_addr));
			rtl += rtap->rta_len;
		}
	} else { //V6
		rtap->rta_type = IFA_ADDRESS;
		struct sockaddr_in6 *addr_v6 = (struct sockaddr_in6*)&addr;
		rtap->rta_len = RTA_LENGTH(sizeof(struct in6_addr));
		memcpy(RTA_DATA(rtap), &addr_v6->sin6_addr, sizeof(struct in6_addr));
		rtl += rtap->rta_len;
	}

	if (iface) {
		rtap = (struct rtattr*)(((char*)rtap)+rtap->rta_len);
		rtap->rta_type = IFA_LABEL;
		rtap->rta_len = RTA_LENGTH(strlen(iface));
		memcpy(RTA_DATA(rtap), iface, strlen(iface));
		rtl += rtap->rta_len;
	}

	req.nl.nlmsg_len = NLMSG_LENGTH(rtl);
	req.nl.nlmsg_flags = NLM_F_REQUEST;
	req.nl.nlmsg_type = RTM_DELADDR;
	req.nl.nlmsg_pid = 0;
	req.nl.nlmsg_seq = ++_seq;
	req.ifa.ifa_family = addr.ss_family;
	req.ifa.ifa_prefixlen = addr.port();
	req.ifa.ifa_flags = IFA_F_PERMANENT;
	req.ifa.ifa_scope = 0;
	req.ifa.ifa_index = interface_index;

	struct sockaddr_nl pa;
	bzero(&pa, sizeof(sockaddr_nl));
	pa.nl_family = AF_NETLINK;

	struct msghdr msg;
	bzero(&msg, sizeof(msg));
	msg.msg_name = (void*)&pa;
	msg.msg_namelen = sizeof(pa);

	struct iovec iov;
	iov.iov_base = (void*)&req.nl;
	iov.iov_len = req.nl.nlmsg_len;
	msg.msg_iov = &iov;
	msg.msg_iovlen = 1;
	sendmsg(fd, &msg, 0);

	_doRecv(fd);

	close(fd);
}

bool LinuxNetLink::routeIsSet(const InetAddress &target, const InetAddress &via, const InetAddress &src, const char *ifname)
{
	Mutex::Lock rl(_routes_m);
	const std::set<LinuxNetLink::Route> &rs = _routes[target];
	for(std::set<LinuxNetLink::Route>::const_iterator ri(rs.begin());ri!=rs.end();++ri) {
		if ((ri->via == via)&&(ri->src == src)) {
			if (ifname) {
				Mutex::Lock ifl(_if_m);
				const iface_entry *ife = _interfaces.get(ri->ifidx);
				if ((ife)&&(!strncmp(ife->ifacename,ifname,IFNAMSIZ)))
					return true;
			} else {
				return true;
			}
		}
	}
	return false;
}

int LinuxNetLink::_indexForInterface(const char *iface)
{
	Mutex::Lock l(_if_m);
	int interface_index = -1;
	Hashtable<int, iface_entry>::Iterator iter(_interfaces);
	int *k = NULL;
	iface_entry *v = NULL;
	while(iter.next(k,v)) {
		if(strcmp(iface, v->ifacename) == 0) {
			interface_index = v->index;
			break;
		}
	}
	return interface_index;
}

} // namespace ZeroTier

#endif