4 * "ipx driver" for IPv4 multicasting
15 #include <arpa/inet.h>
16 #include <netinet/in.h>
19 #include <sys/socket.h>
25 #include "ipx_mcast4.h"
31 //#define IPX_MCAST4_DEBUG
33 extern unsigned char ipx_MyAddress[10];
35 #define UDP_BASEPORT 28342
36 #define PORTSHIFT_TOLERANCE 0x100
37 #define MAX_PACKETSIZE 8192
39 /* OUR port. Can be changed by "@X[+=]..." argument (X is the shift value)
41 static int baseport=UDP_BASEPORT;
43 static struct in_addr game_addr; // The game's multicast address
45 #define MSGHDR "IPX_mcast4: "
47 #ifdef IPX_MCAST4_DEBUG
48 static void msg(const char *fmt, ...)
52 fputs(MSGHDR, stdout);
62 #define FAIL(m...) do{ nm_messagebox("Error", 1, "Ok", ##m); return -1; } while (0)
64 #ifdef IPX_MCAST4_DEBUG
65 /* Dump raw form of IP address/port by fancy output to user
67 static void dumpraddr(unsigned char *a)
71 printf("[%u.%u.%u.%u]", a[0], a[1], a[2], a[3]);
72 port=(signed short)ntohs(*(unsigned short *)(a+4));
73 if (port) printf(":%+d",port);
76 /* Like dumpraddr() but for structure "sockaddr_in"
78 static void dumpaddr(struct sockaddr_in *sin)
81 unsigned char qhbuf[8];
83 memcpy(qhbuf + 0, &sin->sin_addr, 4);
84 ports = htons(((short)ntohs(sin->sin_port)) - UDP_BASEPORT);
85 memcpy(qhbuf + 4, &ports, 2);
90 // The multicast address for Descent 2 game announcements.
91 // TODO: Pick a better address for this
92 #define DESCENT2_ANNOUNCE_ADDR inet_addr("239.255.1.2")
94 /* Open the socket and subscribe to the multicast session */
95 static int ipx_mcast4_OpenSocket(ipx_socket_t *sk, int port)
99 struct sockaddr_in sin;
102 if((sk->fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
105 FAIL("socket() creation failed on port %d: %m", port);
109 sin.sin_family = AF_INET;
110 sin.sin_addr.s_addr = htonl(INADDR_ANY);
111 sin.sin_port = htons(baseport);
112 if (bind(sk->fd, (struct sockaddr *)&sin, sizeof(sin)))
115 msg("close() failed during error recovery: %m");
117 FAIL("bind() to UDP port %d failed: %m", baseport);
120 // Set the TTL so the packets can get out of the local network.
121 if(setsockopt(sk->fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)) < 0)
122 FAIL("setsockopt() failed to set TTL to 128");
124 // Disable multicast loopback
126 if(setsockopt(sk->fd, IPPROTO_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop)) < 0)
127 FAIL("setsockopt() failed to disable multicast loopback: %m");
129 // Subscribe to the game announcement address
130 memset(&mreq, 0, sizeof(mreq));
131 mreq.imr_multiaddr.s_addr = DESCENT2_ANNOUNCE_ADDR;
132 mreq.imr_interface.s_addr = INADDR_ANY;
133 if(setsockopt(sk->fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0)
134 FAIL("setsockopt() failed to subscribe to the game announcement multicast group");
136 // We're not subscribed to a game address yet
137 game_addr.s_addr = 0;
143 static void ipx_mcast4_CloseSocket(ipx_socket_t *sk)
145 if(close(sk->fd) < 0)
150 static int ipx_mcast4_SendPacket(ipx_socket_t *sk, IPXPacket_t *IPXHeader, u_char *data, int dataLen)
152 struct sockaddr_in toaddr;
155 msg("SendPacket enter, dataLen=%d", dataLen);
157 if(dataLen < 0 || dataLen > MAX_PACKETSIZE)
160 toaddr.sin_family = AF_INET;
161 memcpy(&toaddr.sin_addr, IPXHeader->Destination.Node + 0, 4);
162 //toaddr.sin_port = htons(((short)ntohs(*(unsigned short *)(IPXHeader->Destination.Node + 4))) + UDP_BASEPORT);
163 // For now, just use the same port for everything
164 toaddr.sin_port = htons(UDP_BASEPORT);
166 // If it's the broadcast address, then we want to send it to the
167 // GAME ANNOUNCEMENT address.
168 // Data to be sent to the GAME has the destination already set by
169 // ipx_mcast4_SendGamePacket
170 if(toaddr.sin_addr.s_addr == INADDR_BROADCAST)
171 toaddr.sin_addr.s_addr = DESCENT2_ANNOUNCE_ADDR;
173 #ifdef IPX_MCAST4_DEBUG
174 printf(MSGHDR "sendto((%d),Node=[4] %02X %02X,Socket=%02X %02X,s_port=%u,",
176 IPXHeader->Destination.Node[4], IPXHeader->Destination.Node[5],
177 IPXHeader->Destination.Socket[0], IPXHeader->Destination.Socket[1],
178 ntohs(toaddr.sin_port));
183 i = sendto(sk->fd, data, dataLen, 0, (struct sockaddr *)&toaddr, sizeof(toaddr));
187 static int ipx_mcast4_ReceivePacket(ipx_socket_t *sk, char *outbuf, int outbufsize, struct ipx_recv_data *rd)
190 struct sockaddr_in fromaddr;
191 uint fromaddrsize = sizeof(fromaddr);
193 if((size = recvfrom(sk->fd, outbuf, outbufsize, 0, (struct sockaddr*)&fromaddr, &fromaddrsize)) < 0)
196 #ifdef IPX_MCAST4_DEBUG
197 printf(MSGHDR "Got packet from ");
202 // We have the packet, now fill out the receive data.
203 memset(rd, 0, sizeof(*rd));
204 memcpy(rd->src_node, &fromaddr.sin_addr, 4);
205 // TODO: Include the port like in ipx_udp.c
211 /* Handle the netgame aux data
212 * Byte 0 is the protocol version number.
213 * Bytes 1-4 are the IPv4 multicast session to join, in network byte order.
215 static int ipx_mcast4_HandleNetgameAuxData(ipx_socket_t *sk, const u_char buf[NETGAME_AUX_SIZE])
217 // Extract the multicast session and subscribe to it. We should
218 // now be getting packets intended for the players of this game.
220 // Note that we stay subscribed to the game announcement session,
221 // so we can reply to game info requests
225 // Check the protocol version
226 if(buf[0] != IPX_MCAST4_VERSION)
228 FAIL("mcast4 protocol\nversion mismatch!\nGame version is %02x,\nour version is %02x", buf[0], IPX_MCAST4_VERSION);
231 // Get the multicast session
232 memcpy(&game_addr, buf + 1, sizeof(game_addr));
234 #ifdef IPX_MCAST4_DEBUG
236 struct sockaddr_in tmpaddr;
237 tmpaddr.sin_addr = game_addr;
238 tmpaddr.sin_port = 0;
240 printf("Handling netgame aux data: Subscribing to ");
246 // Set the TTL so the packets can get out of the local network.
247 if(setsockopt(sk->fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)) < 0)
248 FAIL("setsockopt() failed to set TTL to 128");
250 memset(&mreq, 0, sizeof(mreq));
251 mreq.imr_multiaddr = game_addr;
252 mreq.imr_interface.s_addr = INADDR_ANY;
254 if(setsockopt(sk->fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0)
255 FAIL("setsockopt() failed to subscribe to the game group");
260 /* Create the netgame aux data.
261 * Byte 0 is the protcol version number.
262 * Bytes 1-4 hold the IPv4 multicast session for the game.
264 static void ipx_mcast4_InitNetgameAuxData(ipx_socket_t *sk, u_char buf[NETGAME_AUX_SIZE])
266 Assert(game_addr.s_addr == 0);
268 // The first byte is the version number
269 buf[0] = IPX_MCAST4_VERSION;
271 // Generate a random session
272 game_addr = inet_makeaddr(239*256 + 255, d_rand() % 0xFFFF);
273 memcpy(buf + 1, &game_addr, sizeof(game_addr));
275 // Since we're obviously the hosting machine, subscribe to this address
276 ipx_mcast4_HandleNetgameAuxData(sk, buf);
279 static void ipx_mcast4_HandleLeaveGame(ipx_socket_t *sk)
281 // We left the game, so unsubscribe from its multicast session
284 Assert(game_addr.s_addr != 0);
286 #ifdef IPX_MCAST4_DEBUG
287 printf("Unsubscribing from game's multicast group: ");
288 dumpraddr(&game_addr.s_addr);
292 mreq.imr_multiaddr = game_addr;
293 mreq.imr_interface.s_addr = INADDR_ANY;
294 if(setsockopt(sk->fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq)) < 0)
295 msg("setsockopt() failed unsubscribing from previous group!");
296 game_addr.s_addr = 0;
299 // Send a packet to every member of the game. We can just multicast it here.
300 static int ipx_mcast4_SendGamePacket(ipx_socket_t *sk, ubyte *data, int dataLen)
302 struct sockaddr_in toaddr;
305 memset(&toaddr, 0, sizeof(toaddr));
306 toaddr.sin_addr = game_addr;
307 toaddr.sin_port = htons(UDP_BASEPORT);
309 msg("ipx_mcast4_SendGamePacket");
311 i = sendto(sk->fd, data, dataLen, 0, (struct sockaddr *)&toaddr, sizeof(toaddr));
316 // Pull this in from ipx_udp.c since it's the same for us.
317 extern int ipx_udp_GetMyAddress();
319 struct ipx_driver ipx_mcast4 = {
320 ipx_udp_GetMyAddress,
321 ipx_mcast4_OpenSocket,
322 ipx_mcast4_CloseSocket,
323 ipx_mcast4_SendPacket,
324 ipx_mcast4_ReceivePacket,
325 ipx_general_PacketReady,
326 ipx_mcast4_InitNetgameAuxData,
327 ipx_mcast4_HandleNetgameAuxData,
328 ipx_mcast4_HandleLeaveGame,
329 ipx_mcast4_SendGamePacket