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udpcli.hpp
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udpcli.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/>.
// UDP transport object specialized for client.
#ifndef OPENVPN_TRANSPORT_CLIENT_UDPCLI_H
#define OPENVPN_TRANSPORT_CLIENT_UDPCLI_H
#include <sstream>
#include <openvpn/io/io.hpp>
#include <openvpn/common/bigmutex.hpp>
#include <openvpn/common/likely.hpp>
#include <openvpn/common/platform.hpp>
#include <openvpn/transport/udplink.hpp>
#include <openvpn/transport/client/transbase.hpp>
#include <openvpn/transport/socket_protect.hpp>
#include <openvpn/client/remotelist.hpp>
namespace openvpn {
namespace UDPTransport {
class ClientConfig : public TransportClientFactory
{
public:
typedef RCPtr<ClientConfig> Ptr;
RemoteList::Ptr remote_list;
bool server_addr_float;
bool synchronous_dns_lookup;
int n_parallel;
Frame::Ptr frame;
SessionStats::Ptr stats;
SocketProtect* socket_protect;
#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()
: server_addr_float(false),
synchronous_dns_lookup(false),
n_parallel(8),
socket_protect(nullptr)
{}
};
class Client : public TransportClient, AsyncResolvableUDP
{
typedef RCPtr<Client> Ptr;
friend class ClientConfig; // calls constructor
friend class Link<Client*>; // calls udp_read_handler
typedef Link<Client*> LinkImpl;
public:
void transport_start() override
{
if (!impl)
{
halt = false;
if (config->remote_list->endpoint_available(&server_host, &server_port, nullptr))
{
start_connect_();
}
else
{
parent->transport_pre_resolve();
if (config->synchronous_dns_lookup)
{
openvpn_io::error_code error;
openvpn_io::ip::udp::resolver::results_type results = resolver.resolve(server_host, server_port, error);
resolve_callback(error, results);
}
else
{
async_resolve_name(server_host, server_port);
}
}
}
}
bool transport_send_const(const Buffer& buf) override
{
return send(buf);
}
bool transport_send(BufferAllocated& buf) override
{
return send(buf);
}
bool transport_send_queue_empty() override // really only has meaning for TCP
{
return false;
}
bool transport_has_send_queue() override
{
return false;
}
void transport_stop_requeueing() override { }
unsigned int transport_send_queue_size() override
{
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 = "UDP";
proto += addr.version_string();
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
{
if (server_endpoint.address().is_v4())
return Protocol(Protocol::UDPv4);
else if (server_endpoint.address().is_v6())
return Protocol(Protocol::UDPv6);
else
return Protocol();
}
void stop() override { stop_(); }
~Client() override { stop_(); }
private:
Client(openvpn_io::io_context& io_context_arg,
ClientConfig* config_arg,
TransportClientParent* parent_arg)
: AsyncResolvableUDP(io_context_arg),
socket(io_context_arg),
config(config_arg),
parent(parent_arg),
resolver(io_context_arg),
halt(false)
{
}
void transport_reparent(TransportClientParent* parent_arg) override
{
parent = parent_arg;
}
bool send(const Buffer& buf)
{
if (impl)
{
const int err = impl->send(buf, nullptr);
if (unlikely(err))
{
// While UDP errors are generally ignored, certain
// errors should be forwarded up to the higher levels.
#ifdef OPENVPN_PLATFORM_IPHONE
if (err == EADDRNOTAVAIL)
{
stop();
parent->transport_error(Error::TRANSPORT_ERROR, "EADDRNOTAVAIL: Can't assign requested address");
}
#endif
return false;
}
else
return true;
}
else
return false;
}
void udp_read_handler(PacketFrom::SPtr& pfp) // called by LinkImpl
{
if (config->server_addr_float || pfp->sender_endpoint == server_endpoint)
parent->transport_recv(pfp->buf);
else
config->stats->error(Error::BAD_SRC_ADDR);
}
void stop_()
{
if (!halt)
{
halt = true;
if (impl)
impl->stop();
socket.close();
resolver.cancel();
async_resolve_cancel();
}
}
// called after DNS resolution has succeeded or failed
void resolve_callback(const openvpn_io::error_code& error,
openvpn_io::ip::udp::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 UDP session: " << error.message();
config->stats->error(Error::RESOLVE_ERROR);
stop();
parent->transport_error(Error::UNDEF, os.str());
}
}
}
// do UDP connect
void start_connect_()
{
config->remote_list->get_endpoint(server_endpoint);
OPENVPN_LOG("Contacting " << server_endpoint << " via UDP");
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 (UDP)");
return;
}
}
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 UDP socket
void start_impl_(const openvpn_io::error_code& error)
{
if (!halt)
{
if (!error)
{
impl.reset(new LinkImpl(this,
socket,
(*config->frame)[Frame::READ_LINK_UDP],
config->stats));
#ifdef OPENVPN_GREMLIN
impl->gremlin_config(config->gremlin_config);
#endif
impl->start(config->n_parallel);
parent->transport_connecting();
}
else
{
std::ostringstream os;
os << "UDP connect error on '" << server_host << ':' << server_port << "' (" << server_endpoint << "): " << error.message();
config->stats->error(Error::UDP_CONNECT_ERROR);
stop();
parent->transport_error(Error::UNDEF, os.str());
}
}
}
std::string server_host;
std::string server_port;
openvpn_io::ip::udp::socket socket;
ClientConfig::Ptr config;
TransportClientParent* parent;
LinkImpl::Ptr impl;
openvpn_io::ip::udp::resolver resolver;
UDPTransport::AsioEndpoint server_endpoint;
bool halt;
};
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