src/network/network_udp.cpp

   1 /*
   2  * This file is part of OpenTTD.
   3  * 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.
   4  * 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.
   5  * 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/>.
   6  */
   7
   8 /**
   9  * @file network_udp.cpp This file handles the UDP related communication.
  10  *
  11  * This is the GameServer <-> GameClient
  12  * communication before the game is being joined.
  13  */
  14
  15 #include "../stdafx.h"
  16 #include "../timer/timer_game_calendar.h"
  17 #include "../map_func.h"
  18 #include "../debug.h"
  19 #include "core/network_game_info.h"
  20 #include "network_gamelist.h"
  21 #include "network_internal.h"
  22 #include "network_udp.h"
  23 #include "network.h"
  24 #include "../core/endian_func.hpp"
  25 #include "../company_base.h"
  26 #include "../rev.h"
  27 #include "../newgrf_text.h"
  28 #include "../strings_func.h"
  29 #include "table/strings.h"
  30
  31 #include "core/udp.h"
  32
  33 #include "../safeguards.h"
  34
  35 static bool _network_udp_server;         ///< Is the UDP server started?
  36 static uint16_t _network_udp_broadcast;    ///< Timeout for the UDP broadcasts.
  37
  38 /** Some information about a socket, which exists before the actual socket has been created to provide locking and the likes. */
  39 struct UDPSocket {
  40         const std::string name;                     ///< The name of the socket.
  41         NetworkUDPSocketHandler *socket;            ///< The actual socket, which may be nullptr when not initialized yet.
  42
  43         UDPSocket(const std::string &name) : name(name), socket(nullptr) {}
  44
  45         void CloseSocket()
  46         {
  47                 this->socket->CloseSocket();
  48                 delete this->socket;
  49                 this->socket = nullptr;
  50         }
  51
  52         void ReceivePackets()
  53         {
  54                 this->socket->ReceivePackets();
  55         }
  56 };
  57
  58 static UDPSocket _udp_client("Client"); ///< udp client socket
  59 static UDPSocket _udp_server("Server"); ///< udp server socket
  60
  61 ///*** Communication with clients (we are server) ***/
  62
  63 /** Helper class for handling all server side communication. */
  64 class ServerNetworkUDPSocketHandler : public NetworkUDPSocketHandler {
  65 protected:
  66         void Receive_CLIENT_FIND_SERVER(Packet &p, NetworkAddress &client_addr) override;
  67 public:
  68         /**
  69          * Create the socket.
  70          * @param addresses The addresses to bind on.
  71          */
  72         ServerNetworkUDPSocketHandler(NetworkAddressList *addresses) : NetworkUDPSocketHandler(addresses) {}
  73         virtual ~ServerNetworkUDPSocketHandler() = default;
  74 };
  75
  76 void ServerNetworkUDPSocketHandler::Receive_CLIENT_FIND_SERVER(Packet &, NetworkAddress &client_addr)
  77 {
  78         Packet packet(PACKET_UDP_SERVER_RESPONSE);
  79         this->SendPacket(packet, client_addr);
  80
  81         Debug(net, 7, "Queried from {}", client_addr.GetHostname());
  82 }
  83
  84 ///*** Communication with servers (we are client) ***/
  85
  86 /** Helper class for handling all client side communication. */
  87 class ClientNetworkUDPSocketHandler : public NetworkUDPSocketHandler {
  88 protected:
  89         void Receive_SERVER_RESPONSE(Packet &p, NetworkAddress &client_addr) override;
  90 public:
  91         virtual ~ClientNetworkUDPSocketHandler() = default;
  92 };
  93
  94 void ClientNetworkUDPSocketHandler::Receive_SERVER_RESPONSE(Packet &, NetworkAddress &client_addr)
  95 {
  96         Debug(net, 3, "Server response from {}", client_addr.GetAddressAsString());
  97
  98         NetworkAddServer(client_addr.GetAddressAsString(false), false, true);
  99 }
 100
 101 /** Broadcast to all ips */
 102 static void NetworkUDPBroadCast(NetworkUDPSocketHandler *socket)
 103 {
 104         for (NetworkAddress &addr : _broadcast_list) {
 105                 Debug(net, 5, "Broadcasting to {}", addr.GetHostname());
 106
 107                 Packet p(PACKET_UDP_CLIENT_FIND_SERVER);
 108                 socket->SendPacket(p, addr, true, true);
 109         }
 110 }
 111
 112 /** Find all servers */
 113 void NetworkUDPSearchGame()
 114 {
 115         /* We are still searching.. */
 116         if (_network_udp_broadcast > 0) return;
 117
 118         Debug(net, 3, "Searching server");
 119
 120         NetworkUDPBroadCast(_udp_client.socket);
 121         _network_udp_broadcast = 300; // Stay searching for 300 ticks
 122 }
 123
 124 /** Initialize the whole UDP bit. */
 125 void NetworkUDPInitialize()
 126 {
 127         /* If not closed, then do it. */
 128         if (_udp_server.socket != nullptr) NetworkUDPClose();
 129
 130         Debug(net, 3, "Initializing UDP listeners");
 131         assert(_udp_client.socket == nullptr && _udp_server.socket == nullptr);
 132
 133         _udp_client.socket = new ClientNetworkUDPSocketHandler();
 134
 135         NetworkAddressList server;
 136         GetBindAddresses(&server, _settings_client.network.server_port);
 137         _udp_server.socket = new ServerNetworkUDPSocketHandler(&server);
 138
 139         _network_udp_server = false;
 140         _network_udp_broadcast = 0;
 141 }
 142
 143 /** Start the listening of the UDP server component. */
 144 void NetworkUDPServerListen()
 145 {
 146         _network_udp_server = _udp_server.socket->Listen();
 147 }
 148
 149 /** Close all UDP related stuff. */
 150 void NetworkUDPClose()
 151 {
 152         _udp_client.CloseSocket();
 153         _udp_server.CloseSocket();
 154
 155         _network_udp_server = false;
 156         _network_udp_broadcast = 0;
 157         Debug(net, 5, "Closed UDP listeners");
 158 }
 159
 160 /** Receive the UDP packets. */
 161 void NetworkBackgroundUDPLoop()
 162 {
 163         if (_network_udp_server) {
 164                 _udp_server.ReceivePackets();
 165         } else {
 166                 _udp_client.ReceivePackets();
 167                 if (_network_udp_broadcast > 0) _network_udp_broadcast--;
 168         }
 169 }