Squashed 'OpenVPN Adapter/Vendors/openvpn/' content from commit da99df6

git-subtree-dir: OpenVPN Adapter/Vendors/openvpn
git-subtree-split: da99df69492256d7a18bbea303ae98457782a4bf

openvpn/tun/linux/client/tuncli.hpp

@@ -0,0 +1,554 @@
+//    OpenVPN -- An application to securely tunnel IP networks
+//               over a single port, with support for SSL/TLS-based
+//               session authentication and key exchange,
+//               packet encryption, packet authentication, and
+//               packet compression.
+//
+//    Copyright (C) 2012-2017 OpenVPN Technologies, Inc.
+//
+//    This program is free software: you can redistribute it and/or modify
+//    it under the terms of the GNU General Public License Version 3
+//    as published by the Free Software Foundation.
+//
+//    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 in the COPYING file.
+//    If not, see <http://www.gnu.org/licenses/>.
+
+// Client tun interface for Linux.
+
+#ifndef OPENVPN_TUN_LINUX_CLIENT_TUNCLI_H
+#define OPENVPN_TUN_LINUX_CLIENT_TUNCLI_H
+
+#include <openvpn/common/exception.hpp>
+#include <openvpn/common/file.hpp>
+#include <openvpn/common/split.hpp>
+#include <openvpn/common/splitlines.hpp>
+#include <openvpn/common/hexstr.hpp>
+#include <openvpn/common/to_string.hpp>
+#include <openvpn/common/process.hpp>
+#include <openvpn/common/action.hpp>
+#include <openvpn/addr/route.hpp>
+#include <openvpn/tun/builder/capture.hpp>
+#include <openvpn/tun/linux/tun.hpp>
+#include <openvpn/tun/client/tunbase.hpp>
+#include <openvpn/tun/client/tunprop.hpp>
+
+namespace openvpn {
+  namespace TunLinux {
+
+    OPENVPN_EXCEPTION(tun_linux_error);
+
+    enum { // add_del_route flags
+      R_IPv6=(1<<0),
+      R_ADD_SYS=(1<<1),
+      R_ADD_DCO=(1<<2),
+      R_ADD_ALL=R_ADD_SYS|R_ADD_DCO,
+    };
+
+    inline IP::Addr cvt_pnr_ip_v4(const std::string& hexaddr)
+    {
+      BufferAllocated v(4, BufferAllocated::CONSTRUCT_ZERO);
+      parse_hex(v, hexaddr);
+      if (v.size() != 4)
+	throw tun_linux_error("bad hex address");
+      IPv4::Addr ret = IPv4::Addr::from_bytes(v.data());
+      return IP::Addr::from_ipv4(ret);
+    }
+
+    inline IP::Addr get_default_gateway_v4()
+    {
+      typedef std::vector<std::string> strvec;
+      const std::string proc_net_route = read_text_simple("/proc/net/route");
+      SplitLines in(proc_net_route, 0);
+      while (in(true))
+	{
+	  const std::string& line = in.line_ref();
+	  strvec v = Split::by_space<strvec, StandardLex, SpaceMatch, Split::NullLimit>(line);
+	  if (v.size() >= 8)
+	    {
+	      if (v[1] == "00000000" && v[7] == "00000000")
+		{
+		  const IP::Addr gw = cvt_pnr_ip_v4(v[2]);
+		  return gw;
+		}
+	    }
+	}
+      throw tun_linux_error("can't determine default gateway");
+    }
+
+    inline void add_del_route(const std::string& addr_str,
+			      const int prefix_len,
+			      const std::string& gateway_str,
+			      const unsigned int flags,
+			      std::vector<IP::Route>* rtvec,
+			      Action::Ptr& create,
+			      Action::Ptr& destroy)
+    {
+      if (flags & R_IPv6)
+	{
+	  const IPv6::Addr addr = IPv6::Addr::from_string(addr_str);
+	  const IPv6::Addr netmask = IPv6::Addr::netmask_from_prefix_len(prefix_len);
+	  const IPv6::Addr net = addr & netmask;
+
+	  if (flags & R_ADD_SYS)
+	    {
+	      // ip route add 2001:db8:1::/48 via 2001:db8:1::1
+	      Command::Ptr add(new Command);
+	      add->argv.push_back("/sbin/ip");
+	      add->argv.push_back("-6");
+	      add->argv.push_back("route");
+	      add->argv.push_back("add");
+	      add->argv.push_back(net.to_string() + '/' + openvpn::to_string(prefix_len));
+	      add->argv.push_back("via");
+	      add->argv.push_back(gateway_str);
+	      create = add;
+
+	      // for the destroy command, copy the add command but replace "add" with "delete"
+	      Command::Ptr del(add->copy());
+	      del->argv[3] = "del";
+	      destroy = del;
+	    }
+
+	  if (rtvec && (flags & R_ADD_DCO))
+	    rtvec->emplace_back(IP::Addr::from_ipv6(net), prefix_len);
+	}
+      else
+	{
+	  const IPv4::Addr addr = IPv4::Addr::from_string(addr_str);
+	  const IPv4::Addr netmask = IPv4::Addr::netmask_from_prefix_len(prefix_len);
+	  const IPv4::Addr net = addr & netmask;
+
+	  if (flags & R_ADD_SYS)
+	    {
+	      // ip route add 192.0.2.128/25 via 192.0.2.1
+	      Command::Ptr add(new Command);
+	      add->argv.push_back("/sbin/ip");
+	      add->argv.push_back("-4");
+	      add->argv.push_back("route");
+	      add->argv.push_back("add");
+	      add->argv.push_back(net.to_string() + '/' + openvpn::to_string(prefix_len));
+	      add->argv.push_back("via");
+	      add->argv.push_back(gateway_str);
+	      create = add;
+
+	      // for the destroy command, copy the add command but replace "add" with "delete"
+	      Command::Ptr del(add->copy());
+	      del->argv[3] = "del";
+	      destroy = del;
+	    }
+
+	  if (rtvec && (flags & R_ADD_DCO))
+	    rtvec->emplace_back(IP::Addr::from_ipv4(net), prefix_len);
+	}
+    }
+
+    inline void add_del_route(const std::string& addr_str,
+			      const int prefix_len,
+			      const std::string& gateway_str,
+			      const unsigned int flags,
+			      std::vector<IP::Route>* rtvec,
+			      ActionList& create,
+			      ActionList& destroy)
+    {
+      Action::Ptr c, d;
+      add_del_route(addr_str, prefix_len, gateway_str, flags, rtvec, c, d);
+      create.add(c);
+      destroy.add(d);
+    }
+
+    inline void iface_up(const std::string& iface_name,
+			     const int mtu,
+			     ActionList& create,
+			     ActionList& destroy)
+    {
+      {
+	Command::Ptr add(new Command);
+	add->argv.push_back("/sbin/ip");
+	add->argv.push_back("link");
+	add->argv.push_back("set");
+	add->argv.push_back(iface_name);
+	add->argv.push_back("up");
+	if (mtu > 0)
+	  {
+	    add->argv.push_back("mtu");
+	    add->argv.push_back(openvpn::to_string(mtu));
+	  }
+	create.add(add);
+
+	// for the destroy command, copy the add command but replace "up" with "down"
+	Command::Ptr del(add->copy());
+	del->argv[4] = "down";
+	destroy.add(del);
+      }
+    }
+
+    inline void iface_config(const std::string& iface_name,
+			     int unit,
+			     const TunBuilderCapture& pull,
+			     std::vector<IP::Route>* rtvec,
+			     ActionList& create,
+			     ActionList& destroy)
+    {
+      // set local4 and local6 to point to IPv4/6 route configurations
+      const TunBuilderCapture::RouteAddress* local4 = pull.vpn_ipv4();
+      const TunBuilderCapture::RouteAddress* local6 = pull.vpn_ipv6();
+
+      // Set IPv4 Interface
+      if (local4)
+	{
+	  Command::Ptr add(new Command);
+	  add->argv.push_back("/sbin/ip");
+	  add->argv.push_back("-4");
+	  add->argv.push_back("addr");
+	  add->argv.push_back("add");
+	  add->argv.push_back(local4->address + '/' + openvpn::to_string(local4->prefix_length));
+	  add->argv.push_back("broadcast");
+	  add->argv.push_back((IPv4::Addr::from_string(local4->address) | ~IPv4::Addr::netmask_from_prefix_len(local4->prefix_length)).to_string());
+	  add->argv.push_back("dev");
+	  add->argv.push_back(iface_name);
+	  if (unit >= 0)
+	    {
+	      add->argv.push_back("label");
+	      add->argv.push_back(iface_name + ':' + openvpn::to_string(unit));
+	    }
+	  create.add(add);
+
+	  // for the destroy command, copy the add command but replace "add" with "delete"
+	  Command::Ptr del(add->copy());
+	  del->argv[3] = "del";
+	  destroy.add(del);
+
+	  // add interface route to rtvec if defined
+	  add_del_route(local4->address, local4->prefix_length, local4->address, R_ADD_DCO, rtvec, create, destroy);
+	}
+
+      // Set IPv6 Interface
+      if (local6 && !pull.block_ipv6)
+	{
+	  Command::Ptr add(new Command);
+	  add->argv.push_back("/sbin/ip");
+	  add->argv.push_back("-6");
+	  add->argv.push_back("addr");
+	  add->argv.push_back("add");
+	  add->argv.push_back(local6->address + '/' + openvpn::to_string(local6->prefix_length));
+	  add->argv.push_back("dev");
+	  add->argv.push_back(iface_name);
+	  create.add(add);
+
+	  // for the destroy command, copy the add command but replace "add" with "delete"
+	  Command::Ptr del(add->copy());
+	  del->argv[3] = "del";
+	  destroy.add(del);
+
+	  // add interface route to rtvec if defined
+	  add_del_route(local6->address, local6->prefix_length, local6->address, R_ADD_DCO|R_IPv6, rtvec, create, destroy);
+	}
+    }
+
+    inline void tun_config(const std::string& iface_name,
+			   const TunBuilderCapture& pull,
+			   std::vector<IP::Route>* rtvec,
+			   ActionList& create,
+			   ActionList& destroy)
+    {
+      const IP::Addr gw4 = get_default_gateway_v4();
+
+      // set local4 and local6 to point to IPv4/6 route configurations
+      const TunBuilderCapture::RouteAddress* local4 = pull.vpn_ipv4();
+      const TunBuilderCapture::RouteAddress* local6 = pull.vpn_ipv6();
+
+      // configure interface
+      iface_up(iface_name, pull.mtu, create, destroy);
+      iface_config(iface_name, -1, pull, rtvec, create, destroy);
+
+      // Process Routes
+      {
+	for (const auto &route : pull.add_routes)
+	  {
+	    if (route.ipv6)
+	      {
+		if (!pull.block_ipv6)
+		  add_del_route(route.address, route.prefix_length, local6->gateway, R_ADD_ALL|R_IPv6, rtvec, create, destroy);
+	      }
+	    else
+	      {
+		if (local4 && !local4->gateway.empty())
+		  add_del_route(route.address, route.prefix_length, local4->gateway, R_ADD_ALL, rtvec, create, destroy);
+		else
+		  OPENVPN_LOG("ERROR: IPv4 route pushed without IPv4 ifconfig and/or route-gateway");
+	      }
+	  }
+      }
+
+      // Process exclude routes
+      {
+	for (const auto &route : pull.exclude_routes)
+	  {
+	    if (route.ipv6)
+	      {
+		OPENVPN_LOG("NOTE: exclude IPv6 routes not supported yet"); // fixme
+	      }
+	    else
+	      {
+		if (gw4.defined())
+		  add_del_route(route.address, route.prefix_length, gw4.to_string(), R_ADD_SYS, rtvec, create, destroy);
+		else
+		  OPENVPN_LOG("NOTE: cannot determine gateway for exclude IPv4 routes");
+	      }
+	  }
+      }
+
+      // Process IPv4 redirect-gateway
+      if (pull.reroute_gw.ipv4)
+	{
+	  // add bypass route
+	  if (!pull.remote_address.ipv6 && !(pull.reroute_gw.flags & RedirectGatewayFlags::RG_LOCAL))
+	    add_del_route(pull.remote_address.address, 32, gw4.to_string(), R_ADD_SYS, rtvec, create, destroy);
+
+	  add_del_route("0.0.0.0", 1, local4->gateway, R_ADD_ALL, rtvec, create, destroy);
+	  add_del_route("128.0.0.0", 1, local4->gateway, R_ADD_ALL, rtvec, create, destroy);
+	}
+
+      // Process IPv6 redirect-gateway
+      if (pull.reroute_gw.ipv6 && !pull.block_ipv6)
+	{
+	  add_del_route("0000::", 1, local6->gateway, R_ADD_ALL|R_IPv6, rtvec, create, destroy);
+	  add_del_route("8000::", 1, local6->gateway, R_ADD_ALL|R_IPv6, rtvec, create, destroy);
+	}
+
+      // fixme -- Process block-ipv6
+
+      // fixme -- Handle pushed DNS servers
+    }
+
+    class ClientConfig : public TunClientFactory
+    {
+    public:
+      typedef RCPtr<ClientConfig> Ptr;
+
+      std::string dev_name;
+      int txqueuelen = 200;
+
+      TunProp::Config tun_prop;
+
+      int n_parallel = 8;
+      Frame::Ptr frame;
+      SessionStats::Ptr stats;
+
+      void load(const OptionList& opt)
+      {
+	// set a default MTU
+	if (!tun_prop.mtu)
+	  tun_prop.mtu = 1500;
+
+	// parse "dev" option
+	if (dev_name.empty())
+	  {
+	    const Option* dev = opt.get_ptr("dev");
+	    if (dev)
+	      dev_name = dev->get(1, 64);
+	  }
+      }
+
+      static Ptr new_obj()
+      {
+	return new ClientConfig;
+      }
+
+      virtual TunClient::Ptr new_tun_client_obj(openvpn_io::io_context& io_context,
+						TunClientParent& parent,
+						TransportClient* transcli);
+    private:
+      ClientConfig() {}
+    };
+
+    class Client : public TunClient
+    {
+      friend class ClientConfig;  // calls constructor
+      friend class TunIO<Client*, PacketFrom, openvpn_io::posix::stream_descriptor>;  // calls tun_read_handler
+
+      typedef Tun<Client*> TunImpl;
+
+    public:
+      virtual void tun_start(const OptionList& opt, TransportClient& transcli, CryptoDCSettings&)
+      {
+	if (!impl)
+	  {
+	    halt = false;
+	    try {
+	      const IP::Addr server_addr = transcli.server_endpoint_addr();
+
+	      // notify parent
+	      parent.tun_pre_tun_config();
+
+	      // parse pushed options
+	      TunBuilderCapture::Ptr po(new TunBuilderCapture());
+	      TunProp::configure_builder(po.get(),
+					 state.get(),
+					 config->stats.get(),
+					 server_addr,
+					 config->tun_prop,
+					 opt,
+					 nullptr,
+					 false);
+
+	      OPENVPN_LOG("CAPTURED OPTIONS:" << std::endl << po->to_string());
+
+	      // configure tun/tap interface properties
+	      ActionList::Ptr add_cmds = new ActionList();
+	      remove_cmds.reset(new ActionList());
+
+	      // start tun
+	      impl.reset(new TunImpl(io_context,
+				     this,
+				     config->frame,
+				     config->stats,
+				     config->dev_name,
+				     config->tun_prop.layer,
+				     config->txqueuelen
+				     ));
+	      impl->start(config->n_parallel);
+
+	      // get the iface name
+	      state->iface_name = impl->name();
+
+	      // configure tun properties
+	      TunLinux::tun_config(state->iface_name, *po, nullptr, *add_cmds, *remove_cmds);
+
+	      // execute commands to bring up interface
+	      add_cmds->execute(std::cout);
+
+	      // signal that we are connected
+	      parent.tun_connected();
+	    }
+	    catch (const std::exception& e)
+	      {
+		stop();
+		parent.tun_error(Error::TUN_SETUP_FAILED, e.what());
+	      }
+	  }
+      }
+
+      virtual bool tun_send(BufferAllocated& buf)
+      {
+	return send(buf);
+      }
+
+      virtual std::string tun_name() const
+      {
+	if (impl)
+	  return impl->name();
+	else
+	  return "UNDEF_TUN";
+      }
+
+      virtual std::string vpn_ip4() const
+      {
+	if (state->vpn_ip4_addr.specified())
+	  return state->vpn_ip4_addr.to_string();
+	else
+	  return "";
+      }
+
+      virtual std::string vpn_ip6() const
+      {
+	if (state->vpn_ip6_addr.specified())
+	  return state->vpn_ip6_addr.to_string();
+	else
+	  return "";
+      }
+
+      virtual std::string vpn_gw4() const override
+      {
+	if (state->vpn_ip4_gw.specified())
+	  return state->vpn_ip4_gw.to_string();
+	else
+	  return "";
+      }
+
+      virtual std::string vpn_gw6() const override
+      {
+	if (state->vpn_ip6_gw.specified())
+	  return state->vpn_ip6_gw.to_string();
+	else
+	  return "";
+      }
+
+      virtual void set_disconnect()
+      {
+      }
+
+      virtual void stop() { stop_(); }
+      virtual ~Client() { stop_(); }
+
+    private:
+      Client(openvpn_io::io_context& io_context_arg,
+	     ClientConfig* config_arg,
+	     TunClientParent& parent_arg)
+	:  io_context(io_context_arg),
+	   config(config_arg),
+	   parent(parent_arg),
+	   state(new TunProp::State()),
+	   halt(false)
+      {
+      }
+
+      bool send(Buffer& buf)
+      {
+	if (impl)
+	  return impl->write(buf);
+	else
+	  return false;
+      }
+
+      void tun_read_handler(PacketFrom::SPtr& pfp) // called by TunImpl
+      {
+	parent.tun_recv(pfp->buf);
+      }
+
+      void tun_error_handler(const Error::Type errtype, // called by TunImpl
+			     const openvpn_io::error_code* error)
+      {
+      }
+
+      void stop_()
+      {
+	if (!halt)
+	  {
+	    halt = true;
+
+	    // remove added routes
+	    if (remove_cmds)
+	      remove_cmds->execute(std::cout);
+
+	    // stop tun
+	    if (impl)
+	      impl->stop();
+	  }
+      }
+
+      openvpn_io::io_context& io_context;
+      ClientConfig::Ptr config;
+      TunClientParent& parent;
+      TunImpl::Ptr impl;
+      TunProp::State::Ptr state;
+      ActionList::Ptr remove_cmds;
+      bool halt;
+    };
+
+    inline TunClient::Ptr ClientConfig::new_tun_client_obj(openvpn_io::io_context& io_context,
+							   TunClientParent& parent,
+							   TransportClient* transcli)
+    {
+      return TunClient::Ptr(new Client(io_context, this, parent));
+    }
+
+  }
+} // namespace openvpn
+
+#endif // OPENVPN_TUN_LINUX_CLIENT_TUNCLI_H

openvpn/tun/linux/tun.hpp

@@ -0,0 +1,162 @@
+//    OpenVPN -- An application to securely tunnel IP networks
+//               over a single port, with support for SSL/TLS-based
+//               session authentication and key exchange,
+//               packet encryption, packet authentication, and
+//               packet compression.
+//
+//    Copyright (C) 2012-2017 OpenVPN Technologies, Inc.
+//
+//    This program is free software: you can redistribute it and/or modify
+//    it under the terms of the GNU General Public License Version 3
+//    as published by the Free Software Foundation.
+//
+//    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 in the COPYING file.
+//    If not, see <http://www.gnu.org/licenses/>.
+
+// Low-level tun interface driver for Linux, client/server independent.
+
+#ifndef OPENVPN_TUN_LINUX_TUN_H
+#define OPENVPN_TUN_LINUX_TUN_H
+
+#include <sys/ioctl.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <net/if.h>
+#include <linux/if_tun.h>
+
+#include <string>
+#include <sstream>
+#include <memory>
+
+#include <openvpn/asio/asioerr.hpp>
+#include <openvpn/common/process.hpp>
+#include <openvpn/common/to_string.hpp>
+#include <openvpn/common/scoped_fd.hpp>
+#include <openvpn/tun/tunio.hpp>
+#include <openvpn/tun/layer.hpp>
+#include <openvpn/log/sessionstats.hpp>
+#include <openvpn/frame/frame.hpp>
+
+namespace openvpn {
+  namespace TunLinux {
+
+    struct PacketFrom
+    {
+      typedef std::unique_ptr<PacketFrom> SPtr;
+      BufferAllocated buf;
+    };
+
+    // exceptions
+    OPENVPN_EXCEPTION(tun_open_error);
+    OPENVPN_EXCEPTION(tun_layer_error);
+    OPENVPN_EXCEPTION(tun_ioctl_error);
+    OPENVPN_EXCEPTION(tun_fcntl_error);
+    OPENVPN_EXCEPTION(tun_name_error);
+    OPENVPN_EXCEPTION(tun_tx_queue_len_error);
+    OPENVPN_EXCEPTION(tun_ifconfig_error);
+
+    template <typename ReadHandler>
+    class Tun : public TunIO<ReadHandler, PacketFrom, openvpn_io::posix::stream_descriptor>
+    {
+      typedef TunIO<ReadHandler, PacketFrom, openvpn_io::posix::stream_descriptor> Base;
+
+    public:
+      typedef RCPtr<Tun> Ptr;
+
+      Tun(openvpn_io::io_context& io_context,
+	  ReadHandler read_handler_arg,
+	  const Frame::Ptr& frame_arg,
+	  const SessionStats::Ptr& stats_arg,
+	  const std::string& name,
+	  const Layer& layer,
+	  const int txqueuelen)
+	: Base(read_handler_arg, frame_arg, stats_arg)
+      {
+	static const char node[] = "/dev/net/tun";
+	ScopedFD fd(open(node, O_RDWR));
+	if (!fd.defined())
+	  OPENVPN_THROW(tun_open_error, "error opening tun device " << node << ": " << errinfo(errno));
+
+	struct ifreq ifr;
+	std::memset(&ifr, 0, sizeof(ifr));
+	ifr.ifr_flags = IFF_ONE_QUEUE;
+	ifr.ifr_flags |= IFF_NO_PI;
+	if (layer() == Layer::OSI_LAYER_3)
+	  ifr.ifr_flags |= IFF_TUN;
+	else if (layer() == Layer::OSI_LAYER_2)
+	  ifr.ifr_flags |= IFF_TAP;
+	else
+	  throw tun_layer_error("unknown OSI layer");
+
+	open_unit(name, ifr, fd);
+
+	if (fcntl (fd(), F_SETFL, O_NONBLOCK) < 0)
+	  throw tun_fcntl_error(errinfo(errno));
+
+	// Set the TX send queue size
+	if (txqueuelen)
+	  {
+	    struct ifreq netifr;
+	    ScopedFD ctl_fd(socket (AF_INET, SOCK_DGRAM, 0));
+
+	    if (ctl_fd.defined())
+	      {
+		std::memset(&netifr, 0, sizeof(netifr));
+		strcpy (netifr.ifr_name, ifr.ifr_name);
+		netifr.ifr_qlen = txqueuelen;
+		if (ioctl (ctl_fd(), SIOCSIFTXQLEN, (void *) &netifr) < 0)
+		  throw tun_tx_queue_len_error(errinfo(errno));
+	      }
+	    else
+	      throw tun_tx_queue_len_error(errinfo(errno));
+	  }
+
+	Base::name_ = ifr.ifr_name;
+	Base::stream = new openvpn_io::posix::stream_descriptor(io_context, fd.release());
+	OPENVPN_LOG_TUN(Base::name_ << " opened");
+      }
+
+      ~Tun() { Base::stop(); }
+
+    private:
+      static void open_unit(const std::string& name, struct ifreq& ifr, ScopedFD& fd)
+      {
+	if (!name.empty())
+	  {
+	    const int max_units = 256;
+	    for (int unit = 0; unit < max_units; ++unit)
+	      {
+		std::string n = name;
+		if (unit)
+		  n += openvpn::to_string(unit);
+		if (n.length() < IFNAMSIZ)
+		  ::strcpy (ifr.ifr_name, n.c_str());
+		else
+		  throw tun_name_error();
+		if (ioctl (fd(), TUNSETIFF, (void *) &ifr) == 0)
+		  return;
+	      }
+	    const int eno = errno;
+	    OPENVPN_THROW(tun_ioctl_error, "failed to open tun device '" << name << "' after trying " << max_units << " units : " << errinfo(eno));
+	  }
+	else
+	  {
+	    if (ioctl (fd(), TUNSETIFF, (void *) &ifr) < 0)
+	      {
+		const int eno = errno;
+		OPENVPN_THROW(tun_ioctl_error, "failed to open tun device '" << name << "' : " << errinfo(eno));
+	      }
+	  }
+      }
+    };
+
+  }
+} // namespace openvpn
+
+#endif // OPENVPN_TUN_LINUX_TUN_H