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tuncli.hpp
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tuncli.hpp
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// 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) 2012-2020 OpenVPN Inc.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero 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 Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program in the COPYING file.
// If not, see <http://www.gnu.org/licenses/>.
// Client tun interface for Windows
#ifndef OPENVPN_TUN_WIN_CLIENT_TUNCLI_H
#define OPENVPN_TUN_WIN_CLIENT_TUNCLI_H
#include <string>
#include <sstream>
#include <memory>
#include <openvpn/common/to_string.hpp>
#include <openvpn/asio/scoped_asio_stream.hpp>
#include <openvpn/common/cleanup.hpp>
#include <openvpn/time/asiotimer.hpp>
#include <openvpn/tun/client/tunbase.hpp>
#include <openvpn/tun/client/tunprop.hpp>
#include <openvpn/tun/client/dhcp_capture.hpp>
#include <openvpn/tun/persist/tunpersist.hpp>
#include <openvpn/tun/persist/tunwrapasio.hpp>
#include <openvpn/tun/tunio.hpp>
#include <openvpn/tun/win/client/clientconfig.hpp>
#include <openvpn/tun/win/client/tunsetup.hpp>
#include <openvpn/win/modname.hpp>
#include <openvpn/tun/win/client/wintun.hpp>
namespace openvpn {
namespace TunWin {
OPENVPN_EXCEPTION(tun_win_error);
// struct used to pass received tun packets
struct PacketFrom
{
typedef std::unique_ptr<PacketFrom> SPtr;
BufferAllocated buf;
};
// tun interface wrapper for Windows
template <typename ReadHandler, typename TunPersist>
class Tun : public TunIO<ReadHandler, PacketFrom, TunWrapAsioStream<TunPersist> >
{
typedef TunIO<ReadHandler, PacketFrom, TunWrapAsioStream<TunPersist> > Base;
public:
typedef RCPtr<Tun> Ptr;
Tun(const typename TunPersist::Ptr& tun_persist,
const std::string& name,
const bool retain_stream,
ReadHandler read_handler,
const Frame::Ptr& frame,
const SessionStats::Ptr& stats)
: Base(read_handler, frame, stats, Frame::READ_TUN)
{
Base::name_ = name;
Base::retain_stream = retain_stream;
Base::stream = new TunWrapAsioStream<TunPersist>(tun_persist);
}
};
class Client : public TunClient
{
friend class ClientConfig; // calls constructor
friend class TunIO<Client*, PacketFrom, TunWrapAsioStream<TunPersist> >; // calls tun_read_handler
typedef Tun<Client*, TunPersist> TunImpl;
public:
typedef RCPtr<Client> Ptr;
virtual void tun_start(const OptionList& opt, TransportClient& transcli, CryptoDCSettings&) override
{
if (!impl)
{
halt = false;
if (config->tun_persist)
tun_persist = config->tun_persist; // long-term persistent
else
tun_persist.reset(new TunPersist(false, false, nullptr)); // short-term
try {
const IP::Addr server_addr = transcli.server_endpoint_addr();
// Check if persisted tun session matches properties of to-be-created session
if (tun_persist->use_persisted_tun(server_addr, config->tun_prop, opt))
{
state = tun_persist->state().state;
OPENVPN_LOG("TunPersist: reused tun context");
}
else
{
// notify parent
parent.tun_pre_tun_config();
// close old TAP handle if persisted
tun_persist->close();
// 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());
// create new tun setup object
tun_setup = config->new_setup_obj(io_context);
// open/config TAP
HANDLE th;
{
std::ostringstream os;
auto os_print = Cleanup([&os](){ OPENVPN_LOG_STRING(os.str()); });
th = tun_setup->establish(*po, Win::module_name(), config->stop, os, NULL);
}
// create ASIO wrapper for HANDLE
TAPStream* ts = new TAPStream(io_context, th);
// persist tun settings state
if (tun_persist->persist_tun_state(ts, { state, nullptr }))
OPENVPN_LOG("TunPersist: saving tun context:" << std::endl << tun_persist->options());
// setup handler for external tun close
tun_setup->set_service_fail_handler([self=Ptr(this)]() {
if (!self->halt)
self->parent.tun_error(Error::TUN_IFACE_DISABLED, "service failure");
});
// enable tun_setup destructor
tun_persist->add_destructor(tun_setup);
// assert ownership over TAP device handle
tun_setup->confirm();
// if layer 2, set up to capture DHCP messages over the tunnel
if (config->tun_prop.layer() == Layer::OSI_LAYER_2)
dhcp_capture.reset(new DHCPCapture(po));
}
// configure tun interface packet forwarding
impl.reset(new TunImpl(tun_persist,
"TUN_WIN",
true,
this,
config->frame,
config->stats));
impl->start(config->n_parallel);
if (!dhcp_capture)
parent.tun_connected(); // signal that we are connected
}
catch (const std::exception& e)
{
if (tun_persist)
tun_persist->close();
stop();
Error::Type err = Error::TUN_SETUP_FAILED;
const ExceptionCode *ec = dynamic_cast<const ExceptionCode *>(&e);
if (ec && ec->code_defined())
err = ec->code();
parent.tun_error(err, e.what());
}
}
}
virtual bool tun_send(BufferAllocated& buf) override
{
return send(buf);
}
virtual std::string tun_name() const override
{
if (impl)
return impl->name();
else
return "UNDEF_TUN";
}
virtual std::string vpn_ip4() const override
{
if (state->vpn_ip4_addr.specified())
return state->vpn_ip4_addr.to_string();
else
return "";
}
virtual std::string vpn_ip6() const override
{
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() override
{
}
virtual void stop() override { 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()),
l2_timer(io_context_arg),
frame_context((*config_arg->frame)[Frame::READ_TUN]),
halt(false)
{
}
bool send(Buffer& buf)
{
if (impl)
{
if (dhcp_capture)
dhcp_inspect(buf);
return impl->write(buf);
}
else
return false;
#ifdef OPENVPN_DEBUG_TAPWIN
tap_process_logging();
#endif
}
void tun_read_handler(PacketFrom::SPtr& pfp) // called by TunImpl
{
parent.tun_recv(pfp->buf);
#ifdef OPENVPN_DEBUG_TAPWIN
tap_process_logging();
#endif
}
void tun_error_handler(const Error::Type errtype, // called by TunImpl
const openvpn_io::error_code* error)
{
if (errtype == Error::TUN_READ_ERROR && error && error->value() == 995)
parent.tun_error(Error::TUN_IFACE_DISABLED, "TAP adapter is disabled");
else
parent.tun_error(Error::TUN_ERROR, "TUN I/O error");
}
void stop_()
{
if (!halt)
{
halt = true;
l2_timer.cancel();
// stop tun
if (impl)
impl->stop();
tun_persist.reset();
}
}
HANDLE tap_handle()
{
if (tun_persist)
{
TAPStream* stream = tun_persist->obj();
if (stream)
return stream->native_handle();
}
return Win::Handle::undefined();
}
void tap_process_logging()
{
HANDLE h = tap_handle();
if (Win::Handle::defined(h))
Util::tap_process_logging(h);
}
void dhcp_inspect(Buffer& buf)
{
try {
if (dhcp_capture->mod_reply(buf))
{
OPENVPN_LOG("DHCP PROPS:" << std::endl << dhcp_capture->get_props().to_string());
layer_2_schedule_timer(1);
}
}
catch (const std::exception& e)
{
stop();
parent.tun_error(Error::TUN_SETUP_FAILED, std::string("L2 exception: ") + e.what());
}
}
void layer_2_schedule_timer(const unsigned int seconds)
{
l2_timer.expires_after(Time::Duration::seconds(seconds));
l2_timer.async_wait([self=Ptr(this)](const openvpn_io::error_code& error)
{
OPENVPN_ASYNC_HANDLER;
if (!error && !self->halt)
self->layer_2_timer_callback();
});
}
// Normally called once per second by l2_timer while we are waiting
// for layer 2 DHCP handshake to complete.
void layer_2_timer_callback()
{
try {
if (dhcp_capture && tun_setup)
{
if (tun_setup->l2_ready(dhcp_capture->get_props()))
{
std::ostringstream os;
tun_setup->l2_finish(dhcp_capture->get_props(), config->stop, os);
OPENVPN_LOG_STRING(os.str());
parent.tun_connected();
dhcp_capture.reset();
}
else
{
OPENVPN_LOG("L2: Waiting for DHCP handshake...");
layer_2_schedule_timer(1);
}
}
}
catch (const std::exception& e)
{
stop();
parent.tun_error(Error::TUN_SETUP_FAILED, std::string("L2 exception: ") + e.what());
}
}
openvpn_io::io_context& io_context;
TunPersist::Ptr tun_persist; // contains the TAP device HANDLE
ClientConfig::Ptr config;
TunClientParent& parent;
TunImpl::Ptr impl;
TunProp::State::Ptr state;
TunWin::SetupBase::Ptr tun_setup;
// Layer 2 DHCP stuff
std::unique_ptr<DHCPCapture> dhcp_capture;
AsioTimer l2_timer;
Frame::Context& frame_context;
bool halt;
};
inline TunClient::Ptr ClientConfig::new_tun_client_obj(openvpn_io::io_context& io_context,
TunClientParent& parent,
TransportClient* transcli)
{
if (wintun)
return TunClient::Ptr(new WintunClient(io_context, this, parent));
else
return TunClient::Ptr(new Client(io_context, this, parent));
}
}
} // namespace openvpn
#endif