ZeroTierOne/osnet/LinuxEthernetTap.cpp

420 lines
12 KiB
C++

/*
* 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 <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/wait.h>
#include <sys/select.h>
#include <netinet/in.h>
#include <net/if_arp.h>
#include <arpa/inet.h>
#include <linux/if.h>
#include <linux/if_tun.h>
#include <linux/if_addr.h>
#include <linux/if_ether.h>
#include <ifaddrs.h>
#include <string>
#include <map>
#include <set>
#include <algorithm>
#include "../node/Constants.hpp"
#include "../node/Utils.hpp"
#include "../node/Mutex.hpp"
#include "LinuxEthernetTap.hpp"
// ff:ff:ff:ff:ff:ff with no ADI
static const ZeroTier::MulticastGroup _blindWildcardMulticastGroup(ZeroTier::MAC(0xff),0);
namespace ZeroTier {
static Mutex __tapCreateLock;
LinuxEthernetTap::LinuxEthernetTap(
const MAC &mac,
unsigned int mtu,
unsigned int metric,
uint64_t nwid,
const char *desiredDevice,
const char *friendlyName,
void (*handler)(void *,const MAC &,const MAC &,unsigned int,const Buffer<4096> &),
void *arg) :
EthernetTap("LinuxEthernetTap",mac,mtu,metric),
_handler(handler),
_arg(arg),
_fd(0),
_enabled(true)
{
char procpath[128];
struct stat sbuf;
Mutex::Lock _l(__tapCreateLock); // create only one tap at a time, globally
if (mtu > 2800)
throw std::runtime_error("max tap MTU is 2800");
_fd = ::open("/dev/net/tun",O_RDWR);
if (_fd <= 0)
throw std::runtime_error(std::string("could not open TUN/TAP device: ") + strerror(errno));
struct ifreq ifr;
memset(&ifr,0,sizeof(ifr));
// Try to recall our last device name, or pick an unused one if that fails.
bool recalledDevice = false;
if ((desiredDevice)&&(desiredDevice[0])) {
Utils::scopy(ifr.ifr_name,sizeof(ifr.ifr_name),desiredDevice);
Utils::snprintf(procpath,sizeof(procpath),"/proc/sys/net/ipv4/conf/%s",ifr.ifr_name);
recalledDevice = (stat(procpath,&sbuf) != 0);
}
if (!recalledDevice) {
int devno = 0;
do {
Utils::snprintf(ifr.ifr_name,sizeof(ifr.ifr_name),"zt%d",devno++);
Utils::snprintf(procpath,sizeof(procpath),"/proc/sys/net/ipv4/conf/%s",ifr.ifr_name);
} while (stat(procpath,&sbuf) == 0); // try zt#++ until we find one that does not exist
}
ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
if (ioctl(_fd,TUNSETIFF,(void *)&ifr) < 0) {
::close(_fd);
throw std::runtime_error("unable to configure TUN/TAP device for TAP operation");
}
_dev = ifr.ifr_name;
::ioctl(_fd,TUNSETPERSIST,0); // valgrind may generate a false alarm here
// Open an arbitrary socket to talk to netlink
int sock = socket(AF_INET,SOCK_DGRAM,0);
if (sock <= 0) {
::close(_fd);
throw std::runtime_error("unable to open netlink socket");
}
// Set MAC address
ifr.ifr_ifru.ifru_hwaddr.sa_family = ARPHRD_ETHER;
mac.copyTo(ifr.ifr_ifru.ifru_hwaddr.sa_data,6);
if (ioctl(sock,SIOCSIFHWADDR,(void *)&ifr) < 0) {
::close(_fd);
::close(sock);
throw std::runtime_error("unable to configure TAP hardware (MAC) address");
return;
}
// Set MTU
ifr.ifr_ifru.ifru_mtu = (int)mtu;
if (ioctl(sock,SIOCSIFMTU,(void *)&ifr) < 0) {
::close(_fd);
::close(sock);
throw std::runtime_error("unable to configure TAP MTU");
}
if (fcntl(_fd,F_SETFL,fcntl(_fd,F_GETFL) & ~O_NONBLOCK) == -1) {
::close(_fd);
throw std::runtime_error("unable to set flags on file descriptor for TAP device");
}
/* Bring interface up */
if (ioctl(sock,SIOCGIFFLAGS,(void *)&ifr) < 0) {
::close(_fd);
::close(sock);
throw std::runtime_error("unable to get TAP interface flags");
}
ifr.ifr_flags |= IFF_UP;
if (ioctl(sock,SIOCSIFFLAGS,(void *)&ifr) < 0) {
::close(_fd);
::close(sock);
throw std::runtime_error("unable to set TAP interface flags");
}
::close(sock);
// Set close-on-exec so that devices cannot persist if we fork/exec for update
::fcntl(_fd,F_SETFD,fcntl(_fd,F_GETFD) | FD_CLOEXEC);
::pipe(_shutdownSignalPipe);
_thread = Thread::start(this);
}
LinuxEthernetTap::~LinuxEthernetTap()
{
::write(_shutdownSignalPipe[1],"\0",1); // causes thread to exit
Thread::join(_thread);
::close(_fd);
::close(_shutdownSignalPipe[0]);
::close(_shutdownSignalPipe[1]);
}
void LinuxEthernetTap::setEnabled(bool en)
{
_enabled = en;
// TODO: interface status change
}
bool LinuxEthernetTap::enabled() const
{
return _enabled;
}
static bool ___removeIp(const std::string &_dev,const InetAddress &ip)
{
long cpid = (long)vfork();
if (cpid == 0) {
Utils::redirectUnixOutputs("/dev/null",(const char *)0);
::execl("/sbin/ip","/sbin/ip","addr","del",ip.toString().c_str(),"dev",_dev.c_str(),(const char *)0);
::execl("/usr/sbin/ip","/usr/sbin/ip","addr","del",ip.toString().c_str(),"dev",_dev.c_str(),(const char *)0);
::_exit(-1);
} else {
int exitcode = -1;
::waitpid(cpid,&exitcode,0);
return (exitcode == 0);
}
}
bool LinuxEthernetTap::addIP(const InetAddress &ip)
{
if (!ip)
return false;
std::set<InetAddress> allIps(ips());
if (allIps.count(ip) > 0)
return true;
// Remove and reconfigure if address is the same but netmask is different
for(std::set<InetAddress>::iterator i(allIps.begin());i!=allIps.end();++i) {
if (i->ipsEqual(ip))
___removeIp(_dev,*i);
}
long cpid = (long)vfork();
if (cpid == 0) {
Utils::redirectUnixOutputs("/dev/null",(const char *)0);
if (ip.isV4()) {
::execl("/sbin/ip","/sbin/ip","addr","add",ip.toString().c_str(),"broadcast",ip.broadcast().toIpString().c_str(),"dev",_dev.c_str(),(const char *)0);
::execl("/usr/sbin/ip","/usr/sbin/ip","addr","add",ip.toString().c_str(),"broadcast",ip.broadcast().toIpString().c_str(),"dev",_dev.c_str(),(const char *)0);
} else {
::execl("/sbin/ip","/sbin/ip","addr","add",ip.toString().c_str(),"dev",_dev.c_str(),(const char *)0);
::execl("/usr/sbin/ip","/usr/sbin/ip","addr","add",ip.toString().c_str(),"dev",_dev.c_str(),(const char *)0);
}
::_exit(-1);
} else if (cpid > 0) {
int exitcode = -1;
::waitpid(cpid,&exitcode,0);
return (exitcode == 0);
}
return false;
}
bool LinuxEthernetTap::removeIP(const InetAddress &ip)
{
if (ips().count(ip) > 0) {
if (___removeIp(_dev,ip))
return true;
}
return false;
}
std::set<InetAddress> LinuxEthernetTap::ips() const
{
struct ifaddrs *ifa = (struct ifaddrs *)0;
if (getifaddrs(&ifa))
return std::set<InetAddress>();
std::set<InetAddress> r;
struct ifaddrs *p = ifa;
while (p) {
if ((!strcmp(p->ifa_name,_dev.c_str()))&&(p->ifa_addr)&&(p->ifa_netmask)&&(p->ifa_addr->sa_family == p->ifa_netmask->sa_family)) {
switch(p->ifa_addr->sa_family) {
case AF_INET: {
struct sockaddr_in *sin = (struct sockaddr_in *)p->ifa_addr;
struct sockaddr_in *nm = (struct sockaddr_in *)p->ifa_netmask;
r.insert(InetAddress(&(sin->sin_addr.s_addr),4,Utils::countBits((uint32_t)nm->sin_addr.s_addr)));
} break;
case AF_INET6: {
struct sockaddr_in6 *sin = (struct sockaddr_in6 *)p->ifa_addr;
struct sockaddr_in6 *nm = (struct sockaddr_in6 *)p->ifa_netmask;
uint32_t b[4];
memcpy(b,nm->sin6_addr.s6_addr,sizeof(b));
r.insert(InetAddress(sin->sin6_addr.s6_addr,16,Utils::countBits(b[0]) + Utils::countBits(b[1]) + Utils::countBits(b[2]) + Utils::countBits(b[3])));
} break;
}
}
p = p->ifa_next;
}
if (ifa)
freeifaddrs(ifa);
return r;
}
void LinuxEthernetTap::put(const MAC &from,const MAC &to,unsigned int etherType,const void *data,unsigned int len)
{
char putBuf[8194];
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;
::write(_fd,putBuf,len);
}
}
std::string LinuxEthernetTap::deviceName() const
{
return _dev;
}
void LinuxEthernetTap::setFriendlyName(const char *friendlyName)
{
}
bool LinuxEthernetTap::updateMulticastGroups(std::set<MulticastGroup> &groups)
{
char *ptr,*ptr2;
unsigned char mac[6];
std::set<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.insert(MulticastGroup(MAC(mac,6),0));
}
}
::close(fd);
}
{
std::set<InetAddress> allIps(ips());
for(std::set<InetAddress>::const_iterator i(allIps.begin());i!=allIps.end();++i)
newGroups.insert(MulticastGroup::deriveMulticastGroupForAddressResolution(*i));
}
bool changed = false;
for(std::set<MulticastGroup>::iterator mg(newGroups.begin());mg!=newGroups.end();++mg) {
if (!groups.count(*mg)) {
groups.insert(*mg);
changed = true;
}
}
for(std::set<MulticastGroup>::iterator mg(groups.begin());mg!=groups.end();) {
if ((!newGroups.count(*mg))&&(*mg != _blindWildcardMulticastGroup)) {
groups.erase(mg++);
changed = true;
} else ++mg;
}
return changed;
}
void LinuxEthernetTap::threadMain()
throw()
{
fd_set readfds,nullfds;
MAC to,from;
int n,nfds,r;
char getBuf[8194];
Buffer<4096> data;
// Wait for a moment after startup -- wait for Network to finish
// constructing itself.
Thread::sleep(500);
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)) {
n = (int)::read(_fd,getBuf + r,sizeof(getBuf) - r);
if (n < 0) {
if ((errno != EINTR)&&(errno != ETIMEDOUT))
break;
} else {
// 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) {
to.setTo(getBuf,6);
from.setTo(getBuf + 6,6);
unsigned int etherType = ntohs(((const uint16_t *)getBuf)[6]);
data.copyFrom(getBuf + 14,(unsigned int)r - 14);
_handler(_arg,from,to,etherType,data);
}
r = 0;
}
}
}
}
}
} // namespace ZeroTier