4 * "ipx driver" for IPv4 multicasting
23 #include <arpa/inet.h>
24 #include <netinet/in.h>
25 #include <sys/socket.h>
27 #define closesocket(x) close(x)
31 #include "ipx_mcast4.h"
37 //#define IPX_MCAST4_DEBUG
39 extern unsigned char ipx_MyAddress[10];
41 #define UDP_BASEPORT 28342
42 #define PORTSHIFT_TOLERANCE 0x100
43 #define MAX_PACKETSIZE 8192
45 /* OUR port. Can be changed by "@X[+=]..." argument (X is the shift value)
47 static int baseport=UDP_BASEPORT;
49 static struct in_addr game_addr; // The game's multicast address
51 #define MSGHDR "IPX_mcast4: "
53 #ifdef IPX_MCAST4_DEBUG
54 static void msg(const char *fmt, ...)
58 fputs(MSGHDR, stdout);
68 #define FAIL(...) do{ nm_messagebox("Error", 1, "Ok", __VA_ARGS__); return -1; } while (0)
70 #ifdef IPX_MCAST4_DEBUG
71 /* Dump raw form of IP address/port by fancy output to user
73 static void dumpraddr(unsigned char *a)
77 printf("[%u.%u.%u.%u]", a[0], a[1], a[2], a[3]);
78 port=(signed short)ntohs(*(unsigned short *)(a+4));
79 if (port) printf(":%+d",port);
82 /* Like dumpraddr() but for structure "sockaddr_in"
84 static void dumpaddr(struct sockaddr_in *sin)
87 unsigned char qhbuf[8];
89 memcpy(qhbuf + 0, &sin->sin_addr, 4);
90 ports = htons(((short)ntohs(sin->sin_port)) - UDP_BASEPORT);
91 memcpy(qhbuf + 4, &ports, 2);
96 // The multicast address for Descent 2 game announcements.
97 // TODO: Pick a better address for this
98 #define DESCENT2_ANNOUNCE_ADDR inet_addr("239.255.1.2")
100 /* Open the socket and subscribe to the multicast session */
101 static int ipx_mcast4_OpenSocket(ipx_socket_t *sk, int port)
105 struct sockaddr_in sin;
108 if((sk->fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
111 FAIL("socket() creation failed on port %d: %m", port);
115 sin.sin_family = AF_INET;
116 sin.sin_addr.s_addr = htonl(INADDR_ANY);
117 sin.sin_port = htons(baseport);
118 if (bind(sk->fd, (struct sockaddr *)&sin, sizeof(sin)))
120 if (closesocket(sk->fd))
121 msg("closesocket() failed during error recovery: %m");
123 FAIL("bind() to UDP port %d failed: %m", baseport);
126 // Set the TTL so the packets can get out of the local network.
127 if (setsockopt(sk->fd, IPPROTO_IP, IP_MULTICAST_TTL, (const void *)&ttl, sizeof(ttl)) < 0)
128 FAIL("setsockopt() failed to set TTL to 128");
130 // Disable multicast loopback
132 if (setsockopt(sk->fd, IPPROTO_IP, IP_MULTICAST_LOOP, (const void *)&loop, sizeof(loop)) < 0)
133 FAIL("setsockopt() failed to disable multicast loopback: %m");
135 // Subscribe to the game announcement address
136 memset(&mreq, 0, sizeof(mreq));
137 mreq.imr_multiaddr.s_addr = DESCENT2_ANNOUNCE_ADDR;
138 mreq.imr_interface.s_addr = INADDR_ANY;
139 if (setsockopt(sk->fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, (const void *)&mreq, sizeof(mreq)) < 0)
140 FAIL("setsockopt() failed to subscribe to the game announcement multicast group");
142 // We're not subscribed to a game address yet
143 game_addr.s_addr = 0;
149 static void ipx_mcast4_CloseSocket(ipx_socket_t *sk)
151 if(closesocket(sk->fd) < 0)
156 static int ipx_mcast4_SendPacket(ipx_socket_t *sk, IPXPacket_t *IPXHeader, u_char *data, int dataLen)
158 struct sockaddr_in toaddr;
161 msg("SendPacket enter, dataLen=%d", dataLen);
163 if(dataLen < 0 || dataLen > MAX_PACKETSIZE)
166 toaddr.sin_family = AF_INET;
167 memcpy(&toaddr.sin_addr, IPXHeader->Destination.Node + 0, 4);
168 //toaddr.sin_port = htons(((short)ntohs(*(unsigned short *)(IPXHeader->Destination.Node + 4))) + UDP_BASEPORT);
169 // For now, just use the same port for everything
170 toaddr.sin_port = htons(UDP_BASEPORT);
172 // If it's the broadcast address, then we want to send it to the
173 // GAME ANNOUNCEMENT address.
174 // Data to be sent to the GAME has the destination already set by
175 // ipx_mcast4_SendGamePacket
176 if(toaddr.sin_addr.s_addr == INADDR_BROADCAST)
177 toaddr.sin_addr.s_addr = DESCENT2_ANNOUNCE_ADDR;
179 #ifdef IPX_MCAST4_DEBUG
180 printf(MSGHDR "sendto((%d),Node=[4] %02X %02X,Socket=%02X %02X,s_port=%u,",
182 IPXHeader->Destination.Node[4], IPXHeader->Destination.Node[5],
183 IPXHeader->Destination.Socket[0], IPXHeader->Destination.Socket[1],
184 ntohs(toaddr.sin_port));
189 i = (int)sendto(sk->fd, (const void *)data, dataLen, 0, (struct sockaddr *)&toaddr, sizeof(toaddr));
193 static int ipx_mcast4_ReceivePacket(ipx_socket_t *sk, char *outbuf, int outbufsize, struct ipx_recv_data *rd)
196 struct sockaddr_in fromaddr;
197 socklen_t fromaddrsize = sizeof(fromaddr);
199 if ((size = (int)recvfrom(sk->fd, outbuf, outbufsize, 0, (struct sockaddr*)&fromaddr, &fromaddrsize)) < 0)
202 #ifdef IPX_MCAST4_DEBUG
203 printf(MSGHDR "Got packet from ");
208 // We have the packet, now fill out the receive data.
209 memset(rd, 0, sizeof(*rd));
210 memcpy(rd->src_node, &fromaddr.sin_addr, 4);
211 // TODO: Include the port like in ipx_udp.c
217 /* Handle the netgame aux data
218 * Byte 0 is the protocol version number.
219 * Bytes 1-4 are the IPv4 multicast session to join, in network byte order.
221 static int ipx_mcast4_HandleNetgameAuxData(ipx_socket_t *sk, const u_char buf[NETGAME_AUX_SIZE])
223 // Extract the multicast session and subscribe to it. We should
224 // now be getting packets intended for the players of this game.
226 // Note that we stay subscribed to the game announcement session,
227 // so we can reply to game info requests
231 // Check the protocol version
232 if(buf[0] != IPX_MCAST4_VERSION)
234 FAIL("mcast4 protocol\nversion mismatch!\nGame version is %02x,\nour version is %02x", buf[0], IPX_MCAST4_VERSION);
237 // Get the multicast session
238 memcpy(&game_addr, buf + 1, sizeof(game_addr));
240 #ifdef IPX_MCAST4_DEBUG
242 struct sockaddr_in tmpaddr;
243 tmpaddr.sin_addr = game_addr;
244 tmpaddr.sin_port = 0;
246 printf("Handling netgame aux data: Subscribing to ");
252 // Set the TTL so the packets can get out of the local network.
253 if(setsockopt(sk->fd, IPPROTO_IP, IP_MULTICAST_TTL, (const void *)&ttl, sizeof(ttl)) < 0)
254 FAIL("setsockopt() failed to set TTL to 128");
256 memset(&mreq, 0, sizeof(mreq));
257 mreq.imr_multiaddr = game_addr;
258 mreq.imr_interface.s_addr = INADDR_ANY;
260 if(setsockopt(sk->fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, (const void *)&mreq, sizeof(mreq)) < 0)
261 FAIL("setsockopt() failed to subscribe to the game group");
266 /* Create the netgame aux data.
267 * Byte 0 is the protcol version number.
268 * Bytes 1-4 hold the IPv4 multicast session for the game.
270 static void ipx_mcast4_InitNetgameAuxData(ipx_socket_t *sk, u_char buf[NETGAME_AUX_SIZE])
273 Assert(game_addr.s_addr == 0);
275 // The first byte is the version number
276 buf[0] = IPX_MCAST4_VERSION;
278 // Generate a random session
279 // game_addr = inet_makeaddr(239*256 + 255, d_rand() % 0xFFFF);
280 sprintf(addr, "%i.%i.%i.%i", 239, 255, d_rand() % 0xFF, d_rand() % 0xFF);
281 game_addr.s_addr = inet_addr(addr);
282 memcpy(buf + 1, &game_addr, sizeof(game_addr));
284 // Since we're obviously the hosting machine, subscribe to this address
285 ipx_mcast4_HandleNetgameAuxData(sk, buf);
288 static void ipx_mcast4_HandleLeaveGame(ipx_socket_t *sk)
290 // We left the game, so unsubscribe from its multicast session
293 Assert(game_addr.s_addr != 0);
295 #ifdef IPX_MCAST4_DEBUG
296 printf("Unsubscribing from game's multicast group: ");
297 dumpraddr(&game_addr.s_addr);
301 mreq.imr_multiaddr = game_addr;
302 mreq.imr_interface.s_addr = INADDR_ANY;
303 if(setsockopt(sk->fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, (const void *)&mreq, sizeof(mreq)) < 0)
304 msg("setsockopt() failed unsubscribing from previous group!");
305 game_addr.s_addr = 0;
308 // Send a packet to every member of the game. We can just multicast it here.
309 static int ipx_mcast4_SendGamePacket(ipx_socket_t *sk, ubyte *data, int dataLen)
311 struct sockaddr_in toaddr;
314 memset(&toaddr, 0, sizeof(toaddr));
315 toaddr.sin_family = AF_INET;
316 toaddr.sin_addr = game_addr;
317 toaddr.sin_port = htons(UDP_BASEPORT);
319 msg("ipx_mcast4_SendGamePacket");
321 i = (int)sendto(sk->fd, (const void *)data, dataLen, 0, (struct sockaddr *)&toaddr, sizeof(toaddr));
326 // Pull this in from ipx_udp.c since it's the same for us.
327 extern int ipx_udp_GetMyAddress();
329 struct ipx_driver ipx_mcast4 = {
330 ipx_udp_GetMyAddress,
331 ipx_mcast4_OpenSocket,
332 ipx_mcast4_CloseSocket,
333 ipx_mcast4_SendPacket,
334 ipx_mcast4_ReceivePacket,
335 ipx_general_PacketReady,
336 ipx_mcast4_InitNetgameAuxData,
337 ipx_mcast4_HandleNetgameAuxData,
338 ipx_mcast4_HandleLeaveGame,
339 ipx_mcast4_SendGamePacket