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C++

// 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 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/>.
// TCP transport object specialized for client.
#ifndef OPENVPN_TRANSPORT_CLIENT_TCPCLI_H
#define OPENVPN_TRANSPORT_CLIENT_TCPCLI_H
#include <sstream>
#include <openvpn/io/io.hpp>
#include <openvpn/transport/tcplink.hpp>
#ifdef OPENVPN_TLS_LINK
#include <openvpn/transport/tlslink.hpp>
#endif
#include <openvpn/transport/client/transbase.hpp>
#include <openvpn/transport/socket_protect.hpp>
#include <openvpn/client/remotelist.hpp>
namespace openvpn {
namespace TCPTransport {
class ClientConfig : public TransportClientFactory
{
public:
typedef RCPtr<ClientConfig> Ptr;
RemoteList::Ptr remote_list;
size_t free_list_max_size;
Frame::Ptr frame;
SessionStats::Ptr stats;
SocketProtect* socket_protect;
#ifdef OPENVPN_TLS_LINK
bool use_tls = false;
std::string tls_ca;
#endif
#ifdef OPENVPN_GREMLIN
Gremlin::Config::Ptr gremlin_config;
#endif
static Ptr new_obj()
{
return new ClientConfig;
}
virtual TransportClient::Ptr new_transport_client_obj(openvpn_io::io_context& io_context,
TransportClientParent* parent);
private:
ClientConfig()
: free_list_max_size(8),
socket_protect(nullptr)
{}
};
class Client : public TransportClient, AsyncResolvableTCP
{
typedef RCPtr<Client> Ptr;
typedef Link<openvpn_io::ip::tcp, Client*, false> LinkImpl;
#ifdef OPENVPN_TLS_LINK
typedef TLSLink<openvpn_io::ip::tcp, Client*, false> LinkImplTLS;
#endif
friend class ClientConfig; // calls constructor
friend LinkImpl::Base; // calls tcp_read_handler
public:
void transport_start() override
{
if (!impl)
{
halt = false;
stop_requeueing = false;
if (config->remote_list->endpoint_available(&server_host,
&server_port,
&server_protocol))
{
start_connect_();
}
else
{
parent->transport_pre_resolve();
async_resolve_name(server_host, server_port);
}
}
}
bool transport_send_const(const Buffer& buf) override
{
return send_const(buf);
}
bool transport_send(BufferAllocated& buf) override
{
return send(buf);
}
bool transport_send_queue_empty() override
{
if (impl)
return impl->send_queue_empty();
else
return false;
}
bool transport_has_send_queue() override
{
return true;
}
unsigned int transport_send_queue_size() override
{
if (impl)
return impl->send_queue_size();
else
return 0;
}
void reset_align_adjust(const size_t align_adjust) override
{
if (impl)
impl->reset_align_adjust(align_adjust);
}
void server_endpoint_info(std::string& host, std::string& port, std::string& proto, std::string& ip_addr) const override
{
host = server_host;
port = server_port;
const IP::Addr addr = server_endpoint_addr();
proto = server_protocol.str();
ip_addr = addr.to_string();
}
IP::Addr server_endpoint_addr() const override
{
return IP::Addr::from_asio(server_endpoint.address());
}
Protocol transport_protocol() const override
{
return server_protocol;
}
void stop() override { stop_(); }
~Client() override { stop_(); }
private:
Client(openvpn_io::io_context& io_context_arg,
ClientConfig* config_arg,
TransportClientParent* parent_arg)
: AsyncResolvableTCP(io_context_arg),
io_context(io_context_arg),
socket(io_context_arg),
config(config_arg),
parent(parent_arg),
resolver(io_context_arg),
halt(false),
stop_requeueing(false)
{
}
void transport_reparent(TransportClientParent* parent_arg) override
{
parent = parent_arg;
}
void transport_stop_requeueing() override
{
stop_requeueing = true;
}
bool send_const(const Buffer& cbuf)
{
if (impl)
{
BufferAllocated buf(cbuf, 0);
return impl->send(buf);
}
else
return false;
}
bool send(BufferAllocated& buf)
{
if (impl)
return impl->send(buf);
else
return false;
}
void tcp_eof_handler() // called by LinkImpl::Base
{
config->stats->error(Error::NETWORK_EOF_ERROR);
tcp_error_handler("NETWORK_EOF_ERROR");
}
bool tcp_read_handler(BufferAllocated& buf) // called by LinkImpl::Base
{
parent->transport_recv(buf);
return !stop_requeueing;
}
void tcp_write_queue_needs_send() // called by LinkImpl::Base
{
parent->transport_needs_send();
}
void tcp_error_handler(const char *error) // called by LinkImpl::Base
{
std::ostringstream os;
os << "Transport error on '" << server_host << ": " << error;
stop();
parent->transport_error(Error::TRANSPORT_ERROR, os.str());
}
void stop_()
{
if (!halt)
{
halt = true;
if (impl)
impl->stop();
socket.close();
resolver.cancel();
async_resolve_cancel();
}
}
// do DNS resolve
void resolve_callback(const openvpn_io::error_code& error,
openvpn_io::ip::tcp::resolver::results_type results) override
{
if (!halt)
{
if (!error)
{
// save resolved endpoint list in remote_list
config->remote_list->set_endpoint_range(results);
start_connect_();
}
else
{
std::ostringstream os;
os << "DNS resolve error on '" << server_host << "' for " << server_protocol.str() << " session: " << error.message();
config->stats->error(Error::RESOLVE_ERROR);
stop();
parent->transport_error(Error::UNDEF, os.str());
}
}
}
// do TCP connect
void start_connect_()
{
config->remote_list->get_endpoint(server_endpoint);
OPENVPN_LOG("Contacting " << server_endpoint << " via "
<< server_protocol.str());
parent->transport_wait();
socket.open(server_endpoint.protocol());
if (config->socket_protect)
{
if (!config->socket_protect->socket_protect(socket.native_handle(), server_endpoint_addr()))
{
config->stats->error(Error::SOCKET_PROTECT_ERROR);
stop();
parent->transport_error(Error::UNDEF, "socket_protect error (" + std::string(server_protocol.str()) + ")");
return;
}
}
socket.set_option(openvpn_io::ip::tcp::no_delay(true));
socket.async_connect(server_endpoint, [self=Ptr(this)](const openvpn_io::error_code& error)
{
OPENVPN_ASYNC_HANDLER;
self->start_impl_(error);
});
}
// start I/O on TCP socket
void start_impl_(const openvpn_io::error_code& error)
{
if (!halt)
{
if (!error)
{
#ifdef OPENVPN_TLS_LINK
if (config->use_tls)
{
int flags = SSLConst::LOG_VERIFY_STATUS|SSLConst::ENABLE_CLIENT_SNI;
SSLLib::SSLAPI::Config::Ptr ssl_conf;
ssl_conf.reset(new SSLLib::SSLAPI::Config());
ssl_conf->set_mode(Mode(Mode::CLIENT));
ssl_conf->set_local_cert_enabled(false);
ssl_conf->set_frame(config->frame);
ssl_conf->set_rng(new SSLLib::RandomAPI(false));
if (!config->tls_ca.empty())
{
ssl_conf->load_ca(config->tls_ca, true);
}
else
{
flags |= SSLConst::NO_VERIFY_PEER;
}
ssl_conf->set_flags(flags);
ssl_factory = ssl_conf->new_factory();
impl.reset(new LinkImplTLS(this,
io_context,
socket,
0,
config->free_list_max_size,
config->frame,
config->stats,
ssl_factory));
}
else
#endif
impl.reset(new LinkImpl(this,
socket,
0, // send_queue_max_size is unlimited because we regulate size in cliproto.hpp
config->free_list_max_size,
(*config->frame)[Frame::READ_LINK_TCP],
config->stats));
#ifdef OPENVPN_GREMLIN
impl->gremlin_config(config->gremlin_config);
#endif
impl->start();
if (!parent->transport_is_openvpn_protocol())
impl->set_raw_mode(true);
parent->transport_connecting();
}
else
{
std::ostringstream os;
os << server_protocol.str() << " connect error on '" << server_host << ':' << server_port << "' (" << server_endpoint << "): " << error.message();
config->stats->error(Error::TCP_CONNECT_ERROR);
stop();
parent->transport_error(Error::UNDEF, os.str());
}
}
}
std::string server_host;
std::string server_port;
Protocol server_protocol;
openvpn_io::io_context& io_context;
openvpn_io::ip::tcp::socket socket;
ClientConfig::Ptr config;
TransportClientParent* parent;
LinkBase::Ptr impl;
openvpn_io::ip::tcp::resolver resolver;
LinkImpl::Base::protocol::endpoint server_endpoint;
bool halt;
bool stop_requeueing;
#ifdef OPENVPN_TLS_LINK
SSLFactoryAPI::Ptr ssl_factory;
#endif
};
inline TransportClient::Ptr ClientConfig::new_transport_client_obj(openvpn_io::io_context& io_context,
TransportClientParent* parent)
{
return TransportClient::Ptr(new Client(io_context, this, parent));
}
}
} // namespace openvpn
#endif