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1 | /* | |
2 | * A rewrite of Darren Reeds original res.c As there is nothing | |
3 | * left of Darrens original code, this is now licensed by the hybrid group. | |
4 | * (Well, some of the function names are the same, and bits of the structs..) | |
5 | * You can use it where it is useful, free even. Buy us a beer and stuff. | |
6 | * | |
7 | * The authors takes no responsibility for any damage or loss | |
8 | * of property which results from the use of this software. | |
9 | * | |
10 | * $Id: res.c 3301 2007-03-28 15:04:06Z jilles $ | |
11 | * from Hybrid Id: res.c 459 2006-02-12 22:21:37Z db $ | |
12 | * | |
13 | * July 1999 - Rewrote a bunch of stuff here. Change hostent builder code, | |
14 | * added callbacks and reference counting of returned hostents. | |
15 | * --Bleep (Thomas Helvey <tomh@inxpress.net>) | |
16 | * | |
17 | * This was all needlessly complicated for irc. Simplified. No more hostent | |
18 | * All we really care about is the IP -> hostname mappings. Thats all. | |
19 | * | |
20 | * Apr 28, 2003 --cryogen and Dianora | |
21 | * | |
22 | * DNS server flooding lessened, AAAA-or-A lookup removed, ip6.int support | |
23 | * removed, various robustness fixes | |
24 | * | |
25 | * 2006 --jilles and nenolod | |
26 | */ | |
27 | ||
28 | #include "stdinc.h" | |
29 | #include "ircd_defs.h" | |
30 | #include "common.h" | |
31 | #include "ircd.h" | |
32 | #include "res.h" | |
33 | #include "reslib.h" | |
34 | #include "match.h" | |
35 | #include "numeric.h" | |
36 | #include "client.h" /* SNO_* */ | |
37 | ||
38 | #if (CHAR_BIT != 8) | |
39 | #error this code needs to be able to address individual octets | |
40 | #endif | |
41 | ||
42 | static PF res_readreply; | |
43 | ||
44 | #define MAXPACKET 1024 /* rfc sez 512 but we expand names so ... */ | |
45 | #define RES_MAXALIASES 35 /* maximum aliases allowed */ | |
46 | #define RES_MAXADDRS 35 /* maximum addresses allowed */ | |
47 | #define AR_TTL 600 /* TTL in seconds for dns cache entries */ | |
48 | ||
49 | /* RFC 1104/1105 wasn't very helpful about what these fields | |
50 | * should be named, so for now, we'll just name them this way. | |
51 | * we probably should look at what named calls them or something. | |
52 | */ | |
53 | #define TYPE_SIZE (size_t)2 | |
54 | #define CLASS_SIZE (size_t)2 | |
55 | #define TTL_SIZE (size_t)4 | |
56 | #define RDLENGTH_SIZE (size_t)2 | |
57 | #define ANSWER_FIXED_SIZE (TYPE_SIZE + CLASS_SIZE + TTL_SIZE + RDLENGTH_SIZE) | |
58 | ||
59 | struct reslist | |
60 | { | |
61 | rb_dlink_node node; | |
62 | int id; | |
63 | time_t ttl; | |
64 | char type; | |
65 | char queryname[IRCD_RES_HOSTLEN + 1]; /* name currently being queried */ | |
66 | char retries; /* retry counter */ | |
67 | char sends; /* number of sends (>1 means resent) */ | |
68 | time_t sentat; | |
69 | time_t timeout; | |
70 | unsigned int lastns; /* index of last server sent to */ | |
71 | struct rb_sockaddr_storage addr; | |
72 | char *name; | |
73 | struct DNSQuery *query; /* query callback for this request */ | |
74 | }; | |
75 | ||
76 | static rb_fde_t *res_fd; | |
77 | static rb_dlink_list request_list = { NULL, NULL, 0 }; | |
78 | static int ns_timeout_count[IRCD_MAXNS]; | |
79 | ||
80 | static void rem_request(struct reslist *request); | |
81 | static struct reslist *make_request(struct DNSQuery *query); | |
82 | static void do_query_name(struct DNSQuery *query, const char *name, struct reslist *request, int); | |
83 | static void do_query_number(struct DNSQuery *query, const struct rb_sockaddr_storage *, | |
84 | struct reslist *request); | |
85 | static void query_name(struct reslist *request); | |
86 | static int send_res_msg(const char *buf, int len, int count); | |
87 | static void resend_query(struct reslist *request); | |
88 | static int check_question(struct reslist *request, HEADER * header, char *buf, char *eob); | |
89 | static int proc_answer(struct reslist *request, HEADER * header, char *, char *); | |
90 | static struct reslist *find_id(int id); | |
91 | static struct DNSReply *make_dnsreply(struct reslist *request); | |
92 | ||
93 | /* | |
94 | * int | |
95 | * res_ourserver(inp) | |
96 | * looks up "inp" in irc_nsaddr_list[] | |
97 | * returns: | |
98 | * 0 : not found | |
99 | * >0 : found | |
100 | * author: | |
101 | * paul vixie, 29may94 | |
102 | * revised for ircd, cryogen(stu) may03 | |
103 | */ | |
104 | static int res_ourserver(const struct rb_sockaddr_storage *inp) | |
105 | { | |
106 | #ifdef RB_IPV6 | |
107 | const struct sockaddr_in6 *v6; | |
108 | const struct sockaddr_in6 *v6in = (const struct sockaddr_in6 *)inp; | |
109 | #endif | |
110 | const struct sockaddr_in *v4; | |
111 | const struct sockaddr_in *v4in = (const struct sockaddr_in *)inp; | |
112 | int ns; | |
113 | ||
114 | for (ns = 0; ns < irc_nscount; ns++) | |
115 | { | |
116 | const struct rb_sockaddr_storage *srv = &irc_nsaddr_list[ns]; | |
117 | #ifdef RB_IPV6 | |
118 | v6 = (const struct sockaddr_in6 *)srv; | |
119 | #endif | |
120 | v4 = (const struct sockaddr_in *)srv; | |
121 | ||
122 | /* could probably just memcmp(srv, inp, srv.ss_len) here | |
123 | * but we'll air on the side of caution - stu | |
124 | */ | |
125 | switch (srv->ss_family) | |
126 | { | |
127 | #ifdef RB_IPV6 | |
128 | case AF_INET6: | |
129 | if (srv->ss_family == inp->ss_family) | |
130 | if (v6->sin6_port == v6in->sin6_port) | |
131 | if ((memcmp(&v6->sin6_addr.s6_addr, &v6in->sin6_addr.s6_addr, | |
132 | sizeof(struct in6_addr)) == 0) || | |
133 | (memcmp(&v6->sin6_addr.s6_addr, &in6addr_any, | |
134 | sizeof(struct in6_addr)) == 0)) | |
135 | { | |
136 | ns_timeout_count[ns] = 0; | |
137 | return 1; | |
138 | } | |
139 | break; | |
140 | #endif | |
141 | case AF_INET: | |
142 | if (srv->ss_family == inp->ss_family) | |
143 | if (v4->sin_port == v4in->sin_port) | |
144 | if ((v4->sin_addr.s_addr == INADDR_ANY) | |
145 | || (v4->sin_addr.s_addr == v4in->sin_addr.s_addr)) | |
146 | { | |
147 | ns_timeout_count[ns] = 0; | |
148 | return 1; | |
149 | } | |
150 | break; | |
151 | default: | |
152 | break; | |
153 | } | |
154 | } | |
155 | ||
156 | return 0; | |
157 | } | |
158 | ||
159 | /* | |
160 | * timeout_query_list - Remove queries from the list which have been | |
161 | * there too long without being resolved. | |
162 | */ | |
163 | static time_t timeout_query_list(time_t now) | |
164 | { | |
165 | rb_dlink_node *ptr; | |
166 | rb_dlink_node *next_ptr; | |
167 | struct reslist *request; | |
168 | time_t next_time = 0; | |
169 | time_t timeout = 0; | |
170 | ||
171 | RB_DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head) | |
172 | { | |
173 | request = ptr->data; | |
174 | timeout = request->sentat + request->timeout; | |
175 | ||
176 | if (now >= timeout) | |
177 | { | |
178 | if (--request->retries <= 0) | |
179 | { | |
180 | (*request->query->callback) (request->query->ptr, NULL); | |
181 | rem_request(request); | |
182 | continue; | |
183 | } | |
184 | else | |
185 | { | |
186 | ns_timeout_count[request->lastns]++; | |
187 | request->sentat = now; | |
188 | request->timeout += request->timeout; | |
189 | resend_query(request); | |
190 | } | |
191 | } | |
192 | ||
193 | if ((next_time == 0) || timeout < next_time) | |
194 | { | |
195 | next_time = timeout; | |
196 | } | |
197 | } | |
198 | ||
199 | return (next_time > now) ? next_time : (now + AR_TTL); | |
200 | } | |
201 | ||
202 | /* | |
203 | * timeout_resolver - check request list | |
204 | */ | |
205 | static void timeout_resolver(void *notused) | |
206 | { | |
207 | timeout_query_list(rb_current_time()); | |
208 | } | |
209 | ||
210 | static struct ev_entry *timeout_resolver_ev = NULL; | |
211 | ||
212 | /* | |
213 | * start_resolver - do everything we need to read the resolv.conf file | |
214 | * and initialize the resolver file descriptor if needed | |
215 | */ | |
216 | static void start_resolver(void) | |
217 | { | |
218 | int i; | |
219 | ||
220 | irc_res_init(); | |
221 | for (i = 0; i < irc_nscount; i++) | |
222 | ns_timeout_count[i] = 0; | |
223 | ||
224 | if (res_fd == NULL) | |
225 | { | |
226 | if ((res_fd = rb_socket(irc_nsaddr_list[0].ss_family, SOCK_DGRAM, 0, | |
227 | "UDP resolver socket")) == NULL) | |
228 | return; | |
229 | ||
230 | /* At the moment, the resolver FD data is global .. */ | |
231 | rb_setselect(res_fd, RB_SELECT_READ, res_readreply, NULL); | |
232 | timeout_resolver_ev = rb_event_add("timeout_resolver", timeout_resolver, NULL, 1); | |
233 | } | |
234 | } | |
235 | ||
236 | /* | |
237 | * init_resolver - initialize resolver and resolver library | |
238 | */ | |
239 | void init_resolver(void) | |
240 | { | |
241 | #ifdef HAVE_SRAND48 | |
242 | srand48(rb_current_time()); | |
243 | #endif | |
244 | start_resolver(); | |
245 | } | |
246 | ||
247 | /* | |
248 | * restart_resolver - reread resolv.conf, reopen socket | |
249 | */ | |
250 | void restart_resolver(void) | |
251 | { | |
252 | rb_close(res_fd); | |
253 | res_fd = NULL; | |
254 | rb_event_delete(timeout_resolver_ev); /* -ddosen */ | |
255 | start_resolver(); | |
256 | } | |
257 | ||
258 | /* | |
259 | * add_local_domain - Add the domain to hostname, if it is missing | |
260 | * (as suggested by eps@TOASTER.SFSU.EDU) | |
261 | */ | |
262 | void add_local_domain(char *hname, size_t size) | |
263 | { | |
264 | /* try to fix up unqualified names */ | |
265 | if (strchr(hname, '.') == NULL) | |
266 | { | |
267 | if (irc_domain[0]) | |
268 | { | |
269 | size_t len = strlen(hname); | |
270 | ||
271 | if ((strlen(irc_domain) + len + 2) < size) | |
272 | { | |
273 | hname[len++] = '.'; | |
274 | strcpy(hname + len, irc_domain); | |
275 | } | |
276 | } | |
277 | } | |
278 | } | |
279 | ||
280 | /* | |
281 | * rem_request - remove a request from the list. | |
282 | * This must also free any memory that has been allocated for | |
283 | * temporary storage of DNS results. | |
284 | */ | |
285 | static void rem_request(struct reslist *request) | |
286 | { | |
287 | rb_dlinkDelete(&request->node, &request_list); | |
288 | rb_free(request->name); | |
289 | rb_free(request); | |
290 | } | |
291 | ||
292 | /* | |
293 | * make_request - Create a DNS request record for the server. | |
294 | */ | |
295 | static struct reslist *make_request(struct DNSQuery *query) | |
296 | { | |
297 | struct reslist *request = rb_malloc(sizeof(struct reslist)); | |
298 | ||
299 | request->sentat = rb_current_time(); | |
300 | request->retries = 3; | |
301 | request->timeout = 4; /* start at 4 and exponential inc. */ | |
302 | request->query = query; | |
303 | ||
304 | rb_dlinkAdd(request, &request->node, &request_list); | |
305 | ||
306 | return request; | |
307 | } | |
308 | ||
309 | /* | |
310 | * delete_resolver_queries - cleanup outstanding queries | |
311 | * for which there no longer exist clients or conf lines. | |
312 | */ | |
313 | void delete_resolver_queries(const struct DNSQuery *query) | |
314 | { | |
315 | rb_dlink_node *ptr; | |
316 | rb_dlink_node *next_ptr; | |
317 | struct reslist *request; | |
318 | ||
319 | RB_DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head) | |
320 | { | |
321 | if ((request = ptr->data) != NULL) | |
322 | { | |
323 | if (query == request->query) | |
324 | rem_request(request); | |
325 | } | |
326 | } | |
327 | } | |
328 | ||
329 | /* | |
330 | * retryfreq - determine how many queries to wait before resending | |
331 | * if there have been that many consecutive timeouts | |
332 | */ | |
333 | static int retryfreq(int timeouts) | |
334 | { | |
335 | switch (timeouts) | |
336 | { | |
337 | case 1: | |
338 | return 3; | |
339 | case 2: | |
340 | return 9; | |
341 | case 3: | |
342 | return 27; | |
343 | case 4: | |
344 | return 81; | |
345 | default: | |
346 | return 243; | |
347 | } | |
348 | } | |
349 | ||
350 | /* | |
351 | * send_res_msg - sends msg to a nameserver. | |
352 | * This should reflect /etc/resolv.conf. | |
353 | * Returns number of nameserver successfully sent to | |
354 | * or -1 if no successful sends. | |
355 | */ | |
356 | static int send_res_msg(const char *msg, int len, int rcount) | |
357 | { | |
358 | int i; | |
359 | int ns; | |
360 | static int retrycnt; | |
361 | ||
362 | retrycnt++; | |
363 | /* First try a nameserver that seems to work. | |
364 | * Every once in a while, try a possibly broken one to check | |
365 | * if it is working again. | |
366 | */ | |
367 | for (i = 0; i < irc_nscount; i++) | |
368 | { | |
369 | ns = (i + rcount - 1) % irc_nscount; | |
370 | if (ns_timeout_count[ns] && retrycnt % retryfreq(ns_timeout_count[ns])) | |
371 | continue; | |
372 | if (sendto(rb_get_fd(res_fd), msg, len, 0, | |
373 | (struct sockaddr *)&(irc_nsaddr_list[ns]), | |
374 | GET_SS_LEN(&irc_nsaddr_list[ns])) == len) | |
375 | return ns; | |
376 | } | |
377 | ||
378 | /* No known working nameservers, try some broken one. */ | |
379 | for (i = 0; i < irc_nscount; i++) | |
380 | { | |
381 | ns = (i + rcount - 1) % irc_nscount; | |
382 | if (!ns_timeout_count[ns]) | |
383 | continue; | |
384 | if (sendto(rb_get_fd(res_fd), msg, len, 0, | |
385 | (struct sockaddr *)&(irc_nsaddr_list[ns]), | |
386 | GET_SS_LEN(&irc_nsaddr_list[ns])) == len) | |
387 | return ns; | |
388 | } | |
389 | ||
390 | return -1; | |
391 | } | |
392 | ||
393 | /* | |
394 | * find_id - find a dns request id (id is determined by dn_mkquery) | |
395 | */ | |
396 | static struct reslist *find_id(int id) | |
397 | { | |
398 | rb_dlink_node *ptr; | |
399 | struct reslist *request; | |
400 | ||
401 | RB_DLINK_FOREACH(ptr, request_list.head) | |
402 | { | |
403 | request = ptr->data; | |
404 | ||
405 | if (request->id == id) | |
406 | return (request); | |
407 | } | |
408 | ||
409 | return (NULL); | |
410 | } | |
411 | ||
412 | /* | |
413 | * gethost_byname_type - get host address from name | |
414 | * | |
415 | */ | |
416 | void gethost_byname_type(const char *name, struct DNSQuery *query, int type) | |
417 | { | |
418 | assert(name != 0); | |
419 | do_query_name(query, name, NULL, type); | |
420 | } | |
421 | ||
422 | /* | |
423 | * gethost_byaddr - get host name from address | |
424 | */ | |
425 | void gethost_byaddr(const struct rb_sockaddr_storage *addr, struct DNSQuery *query) | |
426 | { | |
427 | do_query_number(query, addr, NULL); | |
428 | } | |
429 | ||
430 | /* | |
431 | * do_query_name - nameserver lookup name | |
432 | */ | |
433 | static void do_query_name(struct DNSQuery *query, const char *name, struct reslist *request, | |
434 | int type) | |
435 | { | |
436 | char host_name[IRCD_RES_HOSTLEN + 1]; | |
437 | ||
438 | rb_strlcpy(host_name, name, IRCD_RES_HOSTLEN + 1); | |
439 | add_local_domain(host_name, IRCD_RES_HOSTLEN); | |
440 | ||
441 | if (request == NULL) | |
442 | { | |
443 | request = make_request(query); | |
444 | request->name = (char *)rb_malloc(strlen(host_name) + 1); | |
445 | strcpy(request->name, host_name); | |
446 | } | |
447 | ||
448 | rb_strlcpy(request->queryname, host_name, sizeof(request->queryname)); | |
449 | request->type = type; | |
450 | query_name(request); | |
451 | } | |
452 | ||
453 | /* | |
454 | * do_query_number - Use this to do reverse IP# lookups. | |
455 | */ | |
456 | static void do_query_number(struct DNSQuery *query, const struct rb_sockaddr_storage *addr, | |
457 | struct reslist *request) | |
458 | { | |
459 | const unsigned char *cp; | |
460 | ||
461 | if (request == NULL) | |
462 | { | |
463 | request = make_request(query); | |
464 | memcpy(&request->addr, addr, sizeof(struct rb_sockaddr_storage)); | |
465 | request->name = (char *)rb_malloc(IRCD_RES_HOSTLEN + 1); | |
466 | } | |
467 | ||
468 | if (addr->ss_family == AF_INET) | |
469 | { | |
470 | const struct sockaddr_in *v4 = (const struct sockaddr_in *)addr; | |
471 | cp = (const unsigned char *)&v4->sin_addr.s_addr; | |
472 | ||
473 | rb_sprintf(request->queryname, "%u.%u.%u.%u.in-addr.arpa", (unsigned int)(cp[3]), | |
474 | (unsigned int)(cp[2]), (unsigned int)(cp[1]), (unsigned int)(cp[0])); | |
475 | } | |
476 | #ifdef RB_IPV6 | |
477 | else if (addr->ss_family == AF_INET6) | |
478 | { | |
479 | const struct sockaddr_in6 *v6 = (const struct sockaddr_in6 *)addr; | |
480 | cp = (const unsigned char *)&v6->sin6_addr.s6_addr; | |
481 | ||
482 | (void)sprintf(request->queryname, "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x." | |
483 | "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.ip6.arpa", | |
484 | (unsigned int)(cp[15] & 0xf), (unsigned int)(cp[15] >> 4), | |
485 | (unsigned int)(cp[14] & 0xf), (unsigned int)(cp[14] >> 4), | |
486 | (unsigned int)(cp[13] & 0xf), (unsigned int)(cp[13] >> 4), | |
487 | (unsigned int)(cp[12] & 0xf), (unsigned int)(cp[12] >> 4), | |
488 | (unsigned int)(cp[11] & 0xf), (unsigned int)(cp[11] >> 4), | |
489 | (unsigned int)(cp[10] & 0xf), (unsigned int)(cp[10] >> 4), | |
490 | (unsigned int)(cp[9] & 0xf), (unsigned int)(cp[9] >> 4), | |
491 | (unsigned int)(cp[8] & 0xf), (unsigned int)(cp[8] >> 4), | |
492 | (unsigned int)(cp[7] & 0xf), (unsigned int)(cp[7] >> 4), | |
493 | (unsigned int)(cp[6] & 0xf), (unsigned int)(cp[6] >> 4), | |
494 | (unsigned int)(cp[5] & 0xf), (unsigned int)(cp[5] >> 4), | |
495 | (unsigned int)(cp[4] & 0xf), (unsigned int)(cp[4] >> 4), | |
496 | (unsigned int)(cp[3] & 0xf), (unsigned int)(cp[3] >> 4), | |
497 | (unsigned int)(cp[2] & 0xf), (unsigned int)(cp[2] >> 4), | |
498 | (unsigned int)(cp[1] & 0xf), (unsigned int)(cp[1] >> 4), | |
499 | (unsigned int)(cp[0] & 0xf), (unsigned int)(cp[0] >> 4)); | |
500 | } | |
501 | #endif | |
502 | ||
503 | request->type = T_PTR; | |
504 | query_name(request); | |
505 | } | |
506 | ||
507 | /* | |
508 | * query_name - generate a query based on class, type and name. | |
509 | */ | |
510 | static void query_name(struct reslist *request) | |
511 | { | |
512 | char buf[MAXPACKET]; | |
513 | int request_len = 0; | |
514 | int ns; | |
515 | ||
516 | memset(buf, 0, sizeof(buf)); | |
517 | ||
518 | if ((request_len = | |
519 | irc_res_mkquery(request->queryname, C_IN, request->type, (unsigned char *)buf, sizeof(buf))) > 0) | |
520 | { | |
521 | HEADER *header = (HEADER *) buf; | |
522 | #ifndef HAVE_LRAND48 | |
523 | int k = 0; | |
524 | struct timeval tv; | |
525 | #endif | |
526 | /* | |
527 | * generate an unique id | |
528 | * NOTE: we don't have to worry about converting this to and from | |
529 | * network byte order, the nameserver does not interpret this value | |
530 | * and returns it unchanged | |
531 | */ | |
532 | #ifdef HAVE_LRAND48 | |
533 | do | |
534 | { | |
535 | header->id = (header->id + lrand48()) & 0xffff; | |
536 | } while (find_id(header->id)); | |
537 | #else | |
538 | gettimeofday(&tv, NULL); | |
539 | do | |
540 | { | |
541 | header->id = (header->id + k + tv.tv_usec) & 0xffff; | |
542 | k++; | |
543 | } while (find_id(header->id)); | |
544 | #endif /* HAVE_LRAND48 */ | |
545 | request->id = header->id; | |
546 | ++request->sends; | |
547 | ||
548 | ns = send_res_msg(buf, request_len, request->sends); | |
549 | if (ns != -1) | |
550 | request->lastns = ns; | |
551 | } | |
552 | } | |
553 | ||
554 | static void resend_query(struct reslist *request) | |
555 | { | |
556 | switch (request->type) | |
557 | { | |
558 | case T_PTR: | |
559 | do_query_number(NULL, &request->addr, request); | |
560 | break; | |
561 | case T_A: | |
562 | #ifdef RB_IPV6 | |
563 | case T_AAAA: | |
564 | #endif | |
565 | do_query_name(NULL, request->name, request, request->type); | |
566 | break; | |
567 | default: | |
568 | break; | |
569 | } | |
570 | } | |
571 | ||
572 | /* | |
573 | * check_question - check if the reply really belongs to the | |
574 | * name we queried (to guard against late replies from previous | |
575 | * queries with the same id). | |
576 | */ | |
577 | static int check_question(struct reslist *request, HEADER * header, char *buf, char *eob) | |
578 | { | |
579 | char hostbuf[IRCD_RES_HOSTLEN + 1]; /* working buffer */ | |
580 | unsigned char *current; /* current position in buf */ | |
581 | int n; /* temp count */ | |
582 | ||
583 | current = (unsigned char *)buf + sizeof(HEADER); | |
584 | if (header->qdcount != 1) | |
585 | return 0; | |
586 | n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current, hostbuf, | |
587 | sizeof(hostbuf)); | |
588 | if (n <= 0) | |
589 | return 0; | |
590 | if (strcasecmp(hostbuf, request->queryname)) | |
591 | return 0; | |
592 | return 1; | |
593 | } | |
594 | ||
595 | /* | |
596 | * proc_answer - process name server reply | |
597 | */ | |
598 | static int proc_answer(struct reslist *request, HEADER * header, char *buf, char *eob) | |
599 | { | |
600 | char hostbuf[IRCD_RES_HOSTLEN + 100]; /* working buffer */ | |
601 | unsigned char *current; /* current position in buf */ | |
602 | int query_class; /* answer class */ | |
603 | int type; /* answer type */ | |
604 | int n; /* temp count */ | |
605 | int rd_length; | |
606 | struct sockaddr_in *v4; /* conversion */ | |
607 | #ifdef RB_IPV6 | |
608 | struct sockaddr_in6 *v6; | |
609 | #endif | |
610 | current = (unsigned char *)buf + sizeof(HEADER); | |
611 | ||
612 | for (; header->qdcount > 0; --header->qdcount) | |
613 | { | |
614 | if ((n = irc_dn_skipname(current, (unsigned char *)eob)) < 0) | |
615 | return 0; | |
616 | ||
617 | current += (size_t) n + QFIXEDSZ; | |
618 | } | |
619 | ||
620 | /* | |
621 | * process each answer sent to us blech. | |
622 | */ | |
623 | while (header->ancount > 0 && (char *)current < eob) | |
624 | { | |
625 | header->ancount--; | |
626 | ||
627 | n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current, hostbuf, | |
628 | sizeof(hostbuf)); | |
629 | ||
630 | if (n < 0) | |
631 | { | |
632 | /* | |
633 | * broken message | |
634 | */ | |
635 | return (0); | |
636 | } | |
637 | else if (n == 0) | |
638 | { | |
639 | /* | |
640 | * no more answers left | |
641 | */ | |
642 | return (0); | |
643 | } | |
644 | ||
645 | hostbuf[IRCD_RES_HOSTLEN] = '\0'; | |
646 | ||
647 | /* With Address arithmetic you have to be very anal | |
648 | * this code was not working on alpha due to that | |
649 | * (spotted by rodder/jailbird/dianora) | |
650 | */ | |
651 | current += (size_t) n; | |
652 | ||
653 | if (!(((char *)current + ANSWER_FIXED_SIZE) < eob)) | |
654 | break; | |
655 | ||
656 | type = irc_ns_get16(current); | |
657 | current += TYPE_SIZE; | |
658 | ||
659 | query_class = irc_ns_get16(current); | |
660 | current += CLASS_SIZE; | |
661 | ||
662 | request->ttl = irc_ns_get32(current); | |
663 | current += TTL_SIZE; | |
664 | ||
665 | rd_length = irc_ns_get16(current); | |
666 | current += RDLENGTH_SIZE; | |
667 | ||
668 | /* | |
669 | * Wait to set request->type until we verify this structure | |
670 | */ | |
671 | switch (type) | |
672 | { | |
673 | case T_A: | |
674 | if (request->type != T_A) | |
675 | return (0); | |
676 | ||
677 | /* | |
678 | * check for invalid rd_length or too many addresses | |
679 | */ | |
680 | if (rd_length != sizeof(struct in_addr)) | |
681 | return (0); | |
682 | v4 = (struct sockaddr_in *)&request->addr; | |
683 | SET_SS_LEN(&request->addr, sizeof(struct sockaddr_in)); | |
684 | v4->sin_family = AF_INET; | |
685 | memcpy(&v4->sin_addr, current, sizeof(struct in_addr)); | |
686 | return (1); | |
687 | break; | |
688 | #ifdef RB_IPV6 | |
689 | case T_AAAA: | |
690 | if (request->type != T_AAAA) | |
691 | return (0); | |
692 | if (rd_length != sizeof(struct in6_addr)) | |
693 | return (0); | |
694 | SET_SS_LEN(&request->addr, sizeof(struct sockaddr_in6)); | |
695 | v6 = (struct sockaddr_in6 *)&request->addr; | |
696 | v6->sin6_family = AF_INET6; | |
697 | memcpy(&v6->sin6_addr, current, sizeof(struct in6_addr)); | |
698 | return (1); | |
699 | break; | |
700 | #endif | |
701 | case T_PTR: | |
702 | if (request->type != T_PTR) | |
703 | return (0); | |
704 | n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current, | |
705 | hostbuf, sizeof(hostbuf)); | |
706 | if (n < 0) | |
707 | return (0); /* broken message */ | |
708 | else if (n == 0) | |
709 | return (0); /* no more answers left */ | |
710 | ||
711 | rb_strlcpy(request->name, hostbuf, IRCD_RES_HOSTLEN + 1); | |
712 | ||
713 | return (1); | |
714 | break; | |
715 | case T_CNAME: | |
716 | /* real answer will follow */ | |
717 | current += rd_length; | |
718 | break; | |
719 | ||
720 | default: | |
721 | /* XXX I'd rather just throw away the entire bogus thing | |
722 | * but its possible its just a broken nameserver with still | |
723 | * valid answers. But lets do some rudimentary logging for now... | |
724 | */ | |
725 | ilog(L_MAIN, "irc_res.c bogus type %d", type); | |
726 | break; | |
727 | } | |
728 | } | |
729 | ||
730 | return (1); | |
731 | } | |
732 | ||
733 | /* | |
734 | * res_read_single_reply - read a dns reply from the nameserver and process it. | |
735 | * Return value: 1 if a packet was read, 0 otherwise | |
736 | */ | |
737 | static int res_read_single_reply(rb_fde_t *F, void *data) | |
738 | { | |
739 | char buf[sizeof(HEADER) + MAXPACKET] | |
740 | /* Sparc and alpha need 16bit-alignment for accessing header->id | |
741 | * (which is uint16_t). Because of the header = (HEADER*) buf; | |
742 | * lateron, this is neeeded. --FaUl | |
743 | */ | |
744 | #if defined(__sparc__) || defined(__alpha__) | |
745 | __attribute__ ((aligned(16))) | |
746 | #endif | |
747 | ; | |
748 | HEADER *header; | |
749 | struct reslist *request = NULL; | |
750 | struct DNSReply *reply = NULL; | |
751 | int rc; | |
752 | int answer_count; | |
753 | socklen_t len = sizeof(struct rb_sockaddr_storage); | |
754 | struct rb_sockaddr_storage lsin; | |
755 | ||
756 | rc = recvfrom(rb_get_fd(F), buf, sizeof(buf), 0, (struct sockaddr *)&lsin, &len); | |
757 | ||
758 | /* No packet */ | |
759 | if (rc == 0 || rc == -1) | |
760 | return 0; | |
761 | ||
762 | /* Too small */ | |
763 | if (rc <= (int)(sizeof(HEADER))) | |
764 | return 1; | |
765 | ||
766 | /* | |
767 | * convert DNS reply reader from Network byte order to CPU byte order. | |
768 | */ | |
769 | header = (HEADER *) buf; | |
770 | header->ancount = ntohs(header->ancount); | |
771 | header->qdcount = ntohs(header->qdcount); | |
772 | header->nscount = ntohs(header->nscount); | |
773 | header->arcount = ntohs(header->arcount); | |
774 | ||
775 | /* | |
776 | * response for an id which we have already received an answer for | |
777 | * just ignore this response. | |
778 | */ | |
779 | if (0 == (request = find_id(header->id))) | |
780 | return 1; | |
781 | ||
782 | /* | |
783 | * check against possibly fake replies | |
784 | */ | |
785 | if (!res_ourserver(&lsin)) | |
786 | return 1; | |
787 | ||
788 | if (!check_question(request, header, buf, buf + rc)) | |
789 | return 1; | |
790 | ||
791 | if ((header->rcode != NO_ERRORS) || (header->ancount == 0)) | |
792 | { | |
793 | if (NXDOMAIN == header->rcode) | |
794 | { | |
795 | (*request->query->callback) (request->query->ptr, NULL); | |
796 | rem_request(request); | |
797 | } | |
798 | else | |
799 | { | |
800 | /* | |
801 | * If a bad error was returned, we stop here and dont send | |
802 | * send any more (no retries granted). | |
803 | */ | |
804 | (*request->query->callback) (request->query->ptr, NULL); | |
805 | rem_request(request); | |
806 | } | |
807 | return 1; | |
808 | } | |
809 | /* | |
810 | * If this fails there was an error decoding the received packet, | |
811 | * give up. -- jilles | |
812 | */ | |
813 | answer_count = proc_answer(request, header, buf, buf + rc); | |
814 | ||
815 | if (answer_count) | |
816 | { | |
817 | if (request->type == T_PTR) | |
818 | { | |
819 | if (request->name == NULL) | |
820 | { | |
821 | /* | |
822 | * got a PTR response with no name, something bogus is happening | |
823 | * don't bother trying again, the client address doesn't resolve | |
824 | */ | |
825 | (*request->query->callback) (request->query->ptr, reply); | |
826 | rem_request(request); | |
827 | return 1; | |
828 | } | |
829 | ||
830 | /* | |
831 | * Lookup the 'authoritative' name that we were given for the | |
832 | * ip#. | |
833 | * | |
834 | */ | |
835 | #ifdef RB_IPV6 | |
836 | if (request->addr.ss_family == AF_INET6) | |
837 | gethost_byname_type(request->name, request->query, T_AAAA); | |
838 | else | |
839 | #endif | |
840 | gethost_byname_type(request->name, request->query, T_A); | |
841 | rem_request(request); | |
842 | } | |
843 | else | |
844 | { | |
845 | /* | |
846 | * got a name and address response, client resolved | |
847 | */ | |
848 | reply = make_dnsreply(request); | |
849 | (*request->query->callback) (request->query->ptr, reply); | |
850 | rb_free(reply); | |
851 | rem_request(request); | |
852 | } | |
853 | } | |
854 | else | |
855 | { | |
856 | /* couldn't decode, give up -- jilles */ | |
857 | (*request->query->callback) (request->query->ptr, NULL); | |
858 | rem_request(request); | |
859 | } | |
860 | return 1; | |
861 | } | |
862 | ||
863 | static void res_readreply(rb_fde_t *F, void *data) | |
864 | { | |
865 | while (res_read_single_reply(F, data)) | |
866 | ; | |
867 | rb_setselect(F, RB_SELECT_READ, res_readreply, NULL); | |
868 | } | |
869 | ||
870 | static struct DNSReply *make_dnsreply(struct reslist *request) | |
871 | { | |
872 | struct DNSReply *cp; | |
873 | s_assert(request != 0); | |
874 | ||
875 | cp = (struct DNSReply *)rb_malloc(sizeof(struct DNSReply)); | |
876 | ||
877 | cp->h_name = request->name; | |
878 | memcpy(&cp->addr, &request->addr, sizeof(cp->addr)); | |
879 | return (cp); | |
880 | } | |
881 | ||
882 | void report_dns_servers(struct Client *source_p) | |
883 | { | |
884 | int i; | |
885 | char ipaddr[128]; | |
886 | ||
887 | for (i = 0; i < irc_nscount; i++) | |
888 | { | |
889 | if (!rb_inet_ntop_sock((struct sockaddr *)&(irc_nsaddr_list[i]), | |
890 | ipaddr, sizeof ipaddr)) | |
891 | rb_strlcpy(ipaddr, "?", sizeof ipaddr); | |
892 | sendto_one_numeric(source_p, RPL_STATSDEBUG, | |
893 | "A %s %d", ipaddr, ns_timeout_count[i]); | |
894 | } | |
895 | } |