1 /* $NetBSD: server.c,v 1.9 2021/10/29 11:40:23 nia Exp $ */
2 /*
3 * Copyright (c) 1983-2003, Regents of the University of California.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are
8 * met:
9 *
10 * + Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * + Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * + Neither the name of the University of California, San Francisco nor
16 * the names of its contributors may be used to endorse or promote
17 * products derived from this software without specific prior written
18 * permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
21 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
23 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
24 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
25 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
26 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
30 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 */
32
33 #include <sys/cdefs.h>
34 __RCSID("$NetBSD: server.c,v 1.9 2021/10/29 11:40:23 nia Exp $");
35
36 #include <sys/param.h>
37 #include <sys/stat.h>
38 #include <sys/time.h>
39 #include <sys/poll.h>
40 #include <ctype.h>
41 #include <err.h>
42 #include <errno.h>
43 #include <signal.h>
44 #include <stdlib.h>
45 #include <string.h>
46 #include <unistd.h>
47 #include <assert.h>
48 #include <ifaddrs.h>
49
50 #include "hunt_common.h"
51 #include "pathnames.h"
52 #include "hunt_private.h"
53
54 #ifdef INTERNET
55
56 /*
57 * Code for finding and talking to hunt daemons.
58 */
59
60 static struct sockaddr_in *daemons;
61 static unsigned int numdaemons, maxdaemons;
62
63 static struct sockaddr_in *broadcastaddrs;
64 static int numbroadcastaddrs;
65
66 static bool initial = true;
67 static struct in_addr local_address;
68 static const char *explicit_host;
69 static uint16_t port;
70
71 void
serverlist_setup(const char * explicit_host_arg,uint16_t port_arg)72 serverlist_setup(const char *explicit_host_arg, uint16_t port_arg)
73 {
74 char local_name[MAXHOSTNAMELEN + 1];
75 struct hostent *hp;
76
77 if (gethostname(local_name, sizeof(local_name)) < 0) {
78 leavex(1, "Sorry, I have no hostname.");
79 }
80 local_name[sizeof(local_name) - 1] = '\0';
81 if ((hp = gethostbyname(local_name)) == NULL) {
82 leavex(1, "Can't find myself.");
83 }
84 memcpy(&local_address, hp->h_addr, sizeof(local_address));
85
86 numdaemons = 0;
87 maxdaemons = 20;
88 daemons = NULL;
89 if (reallocarr(&daemons, maxdaemons, sizeof(daemons[0])) != 0)
90 leavex(1, "Out of memory.");
91
92 if (explicit_host_arg) {
93 explicit_host = explicit_host_arg;
94 }
95 port = port_arg;
96 }
97
98 static void
add_daemon_addr(const struct sockaddr_storage * addr,socklen_t addrlen,uint16_t port_num)99 add_daemon_addr(const struct sockaddr_storage *addr, socklen_t addrlen,
100 uint16_t port_num)
101 {
102 const struct sockaddr_in *sin;
103
104 if (addr->ss_family != AF_INET) {
105 return;
106 }
107 assert(addrlen == sizeof(struct sockaddr_in));
108 sin = (const struct sockaddr_in *)addr;
109
110 assert(numdaemons <= maxdaemons);
111 if (numdaemons == maxdaemons) {
112 maxdaemons += 20;
113 if (reallocarr(&daemons, maxdaemons, sizeof(daemons[0])) != 0)
114 leave(1, "realloc");
115 }
116
117 /*
118 * Note that we do *not* convert from network to host
119 * order since the port number we were sent *should*
120 * already be in network order.
121 *
122 * The result may be either the port number for the hunt
123 * socket or the port number for the stats socket... or the
124 * number of players connected and not a port number at all,
125 * depending on the packet type.
126 *
127 * For now at least it is ok to stuff it in here, because the
128 * usage of the various different packet types and the
129 * persistence of the results vs. the program exiting does not
130 * cause us to get confused. If the game is made more
131 * self-contained in the future we'll need to be more careful
132 * about this, especially if we make the caching of results
133 * less scattershot.
134 */
135 daemons[numdaemons] = *sin;
136 daemons[numdaemons].sin_port = port_num;
137 numdaemons++;
138 }
139
140 static bool
have_daemon_addr(const struct sockaddr_storage * addr,socklen_t addrlen)141 have_daemon_addr(const struct sockaddr_storage *addr, socklen_t addrlen)
142 {
143 unsigned j;
144 const struct sockaddr_in *sin;
145
146 if (addr->ss_family != AF_INET) {
147 return false;
148 }
149 assert(addrlen == sizeof(struct sockaddr_in));
150 sin = (const struct sockaddr_in *)addr;
151
152 for (j = 0; j < numdaemons; j++) {
153 if (sin->sin_addr.s_addr == daemons[j].sin_addr.s_addr) {
154 return true;
155 }
156 }
157 return false;
158 }
159
160 static void
getbroadcastaddrs(void)161 getbroadcastaddrs(void)
162 {
163 unsigned num, i;
164 struct ifaddrs *ifp, *ip;
165
166 broadcastaddrs = NULL;
167 numbroadcastaddrs = 0;
168
169 if (getifaddrs(&ifp) < 0) {
170 return;
171 }
172
173 num = 0;
174 for (ip = ifp; ip; ip = ip->ifa_next) {
175 if ((ip->ifa_addr->sa_family == AF_INET) &&
176 (ip->ifa_flags & IFF_BROADCAST)) {
177 num++;
178 }
179 }
180
181 broadcastaddrs = NULL;
182 if (reallocarr(&broadcastaddrs, num, sizeof(broadcastaddrs[0])) != 0)
183 leavex(1, "Out of memory");
184
185 i = 0;
186 for (ip = ifp; ip; ip = ip->ifa_next) {
187 if ((ip->ifa_addr->sa_family == AF_INET) &&
188 (ip->ifa_flags & IFF_BROADCAST)) {
189 memcpy(&broadcastaddrs[i], ip->ifa_broadaddr,
190 sizeof(broadcastaddrs[i]));
191 i++;
192 }
193 }
194 assert(i == num);
195 numbroadcastaddrs = num;
196
197 freeifaddrs(ifp);
198 }
199
200 static void
send_messages(int contactsock,unsigned short msg)201 send_messages(int contactsock, unsigned short msg)
202 {
203 struct sockaddr_in contactaddr;
204 struct hostent *hp;
205 uint16_t wiremsg;
206 int option;
207 int i;
208
209 memset(&contactaddr, 0, sizeof(contactaddr));
210 contactaddr.sin_family = SOCK_FAMILY;
211 contactaddr.sin_port = htons(port);
212
213 if (explicit_host != NULL) { /* explicit host given */
214 hp = gethostbyname(explicit_host);
215 if (hp == NULL) {
216 leavex(1, "%s: Unknown host", explicit_host);
217 }
218 memcpy(&contactaddr.sin_addr, hp->h_addr,
219 sizeof(contactaddr.sin_addr));
220 wiremsg = htons(msg);
221 (void) sendto(contactsock, &wiremsg, sizeof(wiremsg), 0,
222 (struct sockaddr *)&contactaddr,
223 sizeof(contactaddr));
224 return;
225 }
226
227 if (!initial) {
228 /* favor host of previous session by contacting it first */
229 contactaddr.sin_addr = Daemon.sin_addr;
230
231 /* Must be playing! */
232 assert(msg == C_PLAYER);
233 wiremsg = htons(msg);
234
235 (void) sendto(contactsock, &wiremsg, sizeof(wiremsg), 0,
236 (struct sockaddr *)&contactaddr, sizeof(contactaddr));
237 }
238
239 if (initial) {
240 getbroadcastaddrs();
241 }
242
243 #ifdef SO_BROADCAST
244 /* Sun's will broadcast even though this option can't be set */
245 option = 1;
246 if (setsockopt(contactsock, SOL_SOCKET, SO_BROADCAST,
247 &option, sizeof option) < 0) {
248 leave(1, "setsockopt broadcast");
249 /* NOTREACHED */
250 }
251 #endif
252
253 /* send broadcast packets on all interfaces */
254 wiremsg = htons(msg);
255 for (i = 0; i < numbroadcastaddrs; i++) {
256 contactaddr.sin_addr = broadcastaddrs[i].sin_addr;
257 if (sendto(contactsock, &wiremsg, sizeof(wiremsg), 0,
258 (struct sockaddr *)&contactaddr,
259 sizeof(contactaddr)) < 0) {
260 leave(1, "sendto");
261 }
262 }
263 contactaddr.sin_addr = local_address;
264 if (sendto(contactsock, &wiremsg, sizeof(wiremsg), 0,
265 (struct sockaddr *)&contactaddr, sizeof(contactaddr)) < 0) {
266 leave(1, "sendto");
267 }
268 }
269
270 static void
get_responses(int contactsock)271 get_responses(int contactsock)
272 {
273 struct pollfd set[1];
274 struct sockaddr_storage addr;
275 socklen_t addrlen;
276 int r;
277 uint16_t port_num;
278 ssize_t portlen;
279
280 /* forget all old responses */
281 numdaemons = 0;
282
283 errno = 0;
284 set[0].fd = contactsock;
285 set[0].events = POLLIN;
286 for (;;) {
287 r = poll(set, 1, 1000);
288 if (r < 0) {
289 if (errno == EINTR) {
290 continue;
291 }
292 leave(1, "poll");
293 }
294 if (r == 0) {
295 break;
296 }
297
298 addrlen = sizeof(addr);
299 portlen = recvfrom(contactsock, &port_num, sizeof(port_num), 0,
300 (struct sockaddr *)&addr, &addrlen);
301 if (portlen < 0) {
302 if (errno == EINTR) {
303 continue;
304 }
305 leave(1, "recvfrom");
306 }
307 if (portlen == 0) {
308 leavex(1, "recvfrom: Unexpected EOF");
309 }
310 if ((size_t)portlen != sizeof(port_num)) {
311 /* trash, ignore it */
312 continue;
313 }
314 if (have_daemon_addr(&addr, addrlen)) {
315 /* this shouldn't happen */
316 continue;
317 }
318
319 add_daemon_addr(&addr, addrlen, port_num);
320 }
321
322 initial = false;
323 }
324
325 void
serverlist_query(unsigned short msg)326 serverlist_query(unsigned short msg)
327 {
328 int contactsock;
329
330 if (!initial && explicit_host != NULL) {
331 /* already did the work, no point doing it again */
332 return;
333 }
334
335 contactsock = socket(SOCK_FAMILY, SOCK_DGRAM, 0);
336 if (contactsock < 0) {
337 leave(1, "socket system call failed");
338 }
339
340 send_messages(contactsock, msg);
341 get_responses(contactsock);
342
343 (void) close(contactsock);
344 }
345
346 unsigned
serverlist_num(void)347 serverlist_num(void)
348 {
349 return numdaemons;
350 }
351
352 const struct sockaddr_storage *
serverlist_gethost(unsigned i,socklen_t * len_ret)353 serverlist_gethost(unsigned i, socklen_t *len_ret)
354 {
355 struct sockaddr_in *ret;
356
357 assert(i < numdaemons);
358 ret = &daemons[i];
359 *len_ret = sizeof(*ret);
360 return (struct sockaddr_storage *)ret;
361 }
362
363 unsigned short
serverlist_getresponse(unsigned i)364 serverlist_getresponse(unsigned i)
365 {
366 assert(i < numdaemons);
367 return daemons[i].sin_port;
368 }
369
370 #endif /* INTERNET */
371