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/*
* This file is part of OpenTTD.
* OpenTTD 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, version 2.
* OpenTTD 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 OpenTTD. If not, see <http://www.gnu.org/licenses/>.
*/
/** @file network_stun.cpp STUN sending/receiving part of the network protocol. */
#include "../stdafx.h"
#include "../debug.h"
#include "network.h"
#include "network_coordinator.h"
#include "network_stun.h"
#include "../safeguards.h"
/** Connect to the STUN server. */
class NetworkStunConnecter : public TCPConnecter {
private:
ClientNetworkStunSocketHandler *stun_handler;
std::string token;
uint8 family;
public:
/**
* Initiate the connecting.
* @param stun_handler The handler for this request.
* @param connection_string The address of the server.
*/
NetworkStunConnecter(ClientNetworkStunSocketHandler *stun_handler, const std::string &connection_string, const std::string &token, uint8 family) :
TCPConnecter(connection_string, NETWORK_STUN_SERVER_PORT, NetworkAddress(), family),
stun_handler(stun_handler),
token(token),
family(family)
{
}
void OnFailure() override
{
this->stun_handler->connecter = nullptr;
/* Connection to STUN server failed. For example, the client doesn't
* support IPv6, which means it will fail that attempt. */
_network_coordinator_client.StunResult(this->token, this->family, false);
}
void OnConnect(SOCKET s) override
{
this->stun_handler->connecter = nullptr;
assert(this->stun_handler->sock == INVALID_SOCKET);
this->stun_handler->sock = s;
/* Store the local address; later connects will reuse it again.
* This is what makes STUN work for most NATs. */
this->stun_handler->local_addr = NetworkAddress::GetSockAddress(s);
/* We leave the connection open till the real connection is setup later. */
}
};
/**
* Connect to the STUN server over either IPv4 or IPv6.
* @param token The token as received from the Game Coordinator.
* @param family What IP family to use.
*/
void ClientNetworkStunSocketHandler::Connect(const std::string &token, uint8 family)
{
this->token = token;
this->family = family;
this->connecter = new NetworkStunConnecter(this, NetworkStunConnectionString(), token, family);
}
/**
* Send a STUN packet to the STUN server.
* @param token The token as received from the Game Coordinator.
* @param family What IP family this STUN request is for.
* @return The handler for this STUN request.
*/
std::unique_ptr<ClientNetworkStunSocketHandler> ClientNetworkStunSocketHandler::Stun(const std::string &token, uint8 family)
{
auto stun_handler = std::make_unique<ClientNetworkStunSocketHandler>();
stun_handler->Connect(token, family);
Packet *p = new Packet(PACKET_STUN_SERCLI_STUN);
p->Send_uint8(NETWORK_COORDINATOR_VERSION);
p->Send_string(token);
p->Send_uint8(family);
stun_handler->SendPacket(p);
return stun_handler;
}
NetworkRecvStatus ClientNetworkStunSocketHandler::CloseConnection(bool error)
{
NetworkStunSocketHandler::CloseConnection(error);
/* Also make sure any pending connecter is killed ASAP. */
if (this->connecter != nullptr) {
this->connecter->Kill();
this->connecter = nullptr;
}
return NETWORK_RECV_STATUS_OKAY;
}
ClientNetworkStunSocketHandler::~ClientNetworkStunSocketHandler()
{
if (this->connecter != nullptr) {
this->connecter->Kill();
this->connecter = nullptr;
}
}
/**
* Check whether we received/can send some data from/to the STUN server and
* when that's the case handle it appropriately.
*/
void ClientNetworkStunSocketHandler::SendReceive()
{
if (this->sock == INVALID_SOCKET) return;
/* We never attempt to receive anything on a STUN socket. After
* connecting a STUN connection, the local address will be reused to
* to establish the connection with the real server. If we would be to
* read this socket, some OSes get confused and deliver us packets meant
* for the real connection. It appears most OSes play best when we simply
* never attempt to read it to start with (and the packets will remain
* available on the other socket).
* Protocol-wise, the STUN server will never send any packet back anyway. */
this->CanSendReceive();
if (this->SendPackets() == SPS_ALL_SENT && !this->sent_result) {
/* We delay giving the GC the result this long, as to make sure we
* have sent the STUN packet first. This means the GC is more likely
* to have the result ready by the time our StunResult() packet
* arrives. */
this->sent_result = true;
_network_coordinator_client.StunResult(this->token, this->family, true);
}
}
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