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212380e3 | 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 | * | |
42bda3f3 | 10 | * $Id: res.c 3301 2007-03-28 15:04:06Z jilles $ |
212380e3 | 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" | |
212380e3 | 32 | #include "res.h" |
33 | #include "reslib.h" | |
13ae2f4b | 34 | #include "match.h" |
212380e3 | 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 | ||
212380e3 | 59 | struct reslist |
60 | { | |
af81d5a0 | 61 | rb_dlink_node node; |
212380e3 | 62 | int id; |
63 | int sent; /* number of requests sent */ | |
212380e3 | 64 | time_t ttl; |
65 | char type; | |
66 | char queryname[128]; /* name currently being queried */ | |
67 | char retries; /* retry counter */ | |
68 | char sends; /* number of sends (>1 means resent) */ | |
69 | char resend; /* send flag. 0 == dont resend */ | |
70 | time_t sentat; | |
71 | time_t timeout; | |
3ea5fee7 | 72 | struct rb_sockaddr_storage addr; |
212380e3 | 73 | char *name; |
74 | struct DNSQuery *query; /* query callback for this request */ | |
75 | }; | |
76 | ||
80e150e1 | 77 | static rb_fde_t *res_fd; |
af81d5a0 | 78 | static rb_dlink_list request_list = { NULL, NULL, 0 }; |
212380e3 | 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); | |
3ea5fee7 | 83 | static void do_query_number(struct DNSQuery *query, const struct rb_sockaddr_storage *, |
212380e3 | 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 | ||
212380e3 | 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 | */ | |
3ea5fee7 | 104 | static int res_ourserver(const struct rb_sockaddr_storage *inp) |
212380e3 | 105 | { |
2c2e0aa9 | 106 | #ifdef RB_IPV6 |
cda884c6 JT |
107 | const struct sockaddr_in6 *v6; |
108 | const struct sockaddr_in6 *v6in = (const struct sockaddr_in6 *)inp; | |
212380e3 | 109 | #endif |
cda884c6 JT |
110 | const struct sockaddr_in *v4; |
111 | const struct sockaddr_in *v4in = (const struct sockaddr_in *)inp; | |
212380e3 | 112 | int ns; |
113 | ||
114 | for (ns = 0; ns < irc_nscount; ns++) | |
115 | { | |
3ea5fee7 | 116 | const struct rb_sockaddr_storage *srv = &irc_nsaddr_list[ns]; |
2c2e0aa9 | 117 | #ifdef RB_IPV6 |
cda884c6 | 118 | v6 = (const struct sockaddr_in6 *)srv; |
212380e3 | 119 | #endif |
cda884c6 | 120 | v4 = (const struct sockaddr_in *)srv; |
212380e3 | 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 | { | |
2c2e0aa9 | 127 | #ifdef RB_IPV6 |
212380e3 | 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 | return 1; | |
136 | break; | |
137 | #endif | |
138 | case AF_INET: | |
139 | if (srv->ss_family == inp->ss_family) | |
140 | if (v4->sin_port == v4in->sin_port) | |
141 | if ((v4->sin_addr.s_addr == INADDR_ANY) | |
142 | || (v4->sin_addr.s_addr == v4in->sin_addr.s_addr)) | |
143 | return 1; | |
144 | break; | |
145 | default: | |
146 | break; | |
147 | } | |
148 | } | |
149 | ||
150 | return 0; | |
151 | } | |
152 | ||
153 | /* | |
154 | * timeout_query_list - Remove queries from the list which have been | |
155 | * there too long without being resolved. | |
156 | */ | |
157 | static time_t timeout_query_list(time_t now) | |
158 | { | |
af81d5a0 | 159 | rb_dlink_node *ptr; |
90a3c35b | 160 | rb_dlink_node *next_ptr; |
212380e3 | 161 | struct reslist *request; |
162 | time_t next_time = 0; | |
163 | time_t timeout = 0; | |
164 | ||
90a3c35b | 165 | RB_DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head) |
212380e3 | 166 | { |
167 | request = ptr->data; | |
168 | timeout = request->sentat + request->timeout; | |
169 | ||
170 | if (now >= timeout) | |
171 | { | |
172 | if (--request->retries <= 0) | |
173 | { | |
174 | (*request->query->callback) (request->query->ptr, NULL); | |
175 | rem_request(request); | |
176 | continue; | |
177 | } | |
178 | else | |
179 | { | |
180 | request->sentat = now; | |
181 | request->timeout += request->timeout; | |
182 | resend_query(request); | |
183 | } | |
184 | } | |
185 | ||
186 | if ((next_time == 0) || timeout < next_time) | |
187 | { | |
188 | next_time = timeout; | |
189 | } | |
190 | } | |
191 | ||
192 | return (next_time > now) ? next_time : (now + AR_TTL); | |
193 | } | |
194 | ||
195 | /* | |
196 | * timeout_resolver - check request list | |
197 | */ | |
198 | static void timeout_resolver(void *notused) | |
199 | { | |
9f6bbe3c | 200 | timeout_query_list(rb_current_time()); |
212380e3 | 201 | } |
202 | ||
80e150e1 WP |
203 | static struct ev_entry *timeout_resolver_ev = NULL; |
204 | ||
212380e3 | 205 | /* |
206 | * start_resolver - do everything we need to read the resolv.conf file | |
207 | * and initialize the resolver file descriptor if needed | |
208 | */ | |
209 | static void start_resolver(void) | |
210 | { | |
211 | irc_res_init(); | |
212 | ||
cda884c6 | 213 | if (res_fd == NULL) |
212380e3 | 214 | { |
38e6acdd | 215 | if ((res_fd = rb_socket(irc_nsaddr_list[0].ss_family, SOCK_DGRAM, 0, |
80e150e1 | 216 | "UDP resolver socket")) == NULL) |
212380e3 | 217 | return; |
218 | ||
219 | /* At the moment, the resolver FD data is global .. */ | |
80e150e1 WP |
220 | rb_setselect(res_fd, RB_SELECT_READ, res_readreply, NULL); |
221 | timeout_resolver_ev = rb_event_add("timeout_resolver", timeout_resolver, NULL, 1); | |
212380e3 | 222 | } |
223 | } | |
224 | ||
225 | /* | |
226 | * init_resolver - initialize resolver and resolver library | |
227 | */ | |
228 | void init_resolver(void) | |
229 | { | |
230 | #ifdef HAVE_SRAND48 | |
9f6bbe3c | 231 | srand48(rb_current_time()); |
212380e3 | 232 | #endif |
233 | start_resolver(); | |
234 | } | |
235 | ||
236 | /* | |
237 | * restart_resolver - reread resolv.conf, reopen socket | |
238 | */ | |
239 | void restart_resolver(void) | |
240 | { | |
38e6acdd | 241 | rb_close(res_fd); |
80e150e1 WP |
242 | res_fd = NULL; |
243 | rb_event_delete(timeout_resolver_ev); /* -ddosen */ | |
212380e3 | 244 | start_resolver(); |
245 | } | |
246 | ||
247 | /* | |
248 | * add_local_domain - Add the domain to hostname, if it is missing | |
249 | * (as suggested by eps@TOASTER.SFSU.EDU) | |
250 | */ | |
251 | void add_local_domain(char *hname, size_t size) | |
252 | { | |
253 | /* try to fix up unqualified names */ | |
254 | if (strchr(hname, '.') == NULL) | |
255 | { | |
256 | if (irc_domain[0]) | |
257 | { | |
258 | size_t len = strlen(hname); | |
259 | ||
260 | if ((strlen(irc_domain) + len + 2) < size) | |
261 | { | |
262 | hname[len++] = '.'; | |
263 | strcpy(hname + len, irc_domain); | |
264 | } | |
265 | } | |
266 | } | |
267 | } | |
268 | ||
269 | /* | |
270 | * rem_request - remove a request from the list. | |
271 | * This must also free any memory that has been allocated for | |
272 | * temporary storage of DNS results. | |
273 | */ | |
274 | static void rem_request(struct reslist *request) | |
275 | { | |
af81d5a0 | 276 | rb_dlinkDelete(&request->node, &request_list); |
90a3c35b VY |
277 | rb_free(request->name); |
278 | rb_free(request); | |
212380e3 | 279 | } |
280 | ||
281 | /* | |
282 | * make_request - Create a DNS request record for the server. | |
283 | */ | |
284 | static struct reslist *make_request(struct DNSQuery *query) | |
285 | { | |
8e43b0b4 | 286 | struct reslist *request = rb_malloc(sizeof(struct reslist)); |
212380e3 | 287 | |
9f6bbe3c | 288 | request->sentat = rb_current_time(); |
212380e3 | 289 | request->retries = 3; |
290 | request->resend = 1; | |
291 | request->timeout = 4; /* start at 4 and exponential inc. */ | |
292 | request->query = query; | |
212380e3 | 293 | |
af81d5a0 | 294 | rb_dlinkAdd(request, &request->node, &request_list); |
212380e3 | 295 | |
296 | return request; | |
297 | } | |
298 | ||
299 | /* | |
300 | * delete_resolver_queries - cleanup outstanding queries | |
301 | * for which there no longer exist clients or conf lines. | |
302 | */ | |
303 | void delete_resolver_queries(const struct DNSQuery *query) | |
304 | { | |
af81d5a0 | 305 | rb_dlink_node *ptr; |
90a3c35b | 306 | rb_dlink_node *next_ptr; |
212380e3 | 307 | struct reslist *request; |
308 | ||
90a3c35b | 309 | RB_DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head) |
212380e3 | 310 | { |
311 | if ((request = ptr->data) != NULL) | |
312 | { | |
313 | if (query == request->query) | |
314 | rem_request(request); | |
315 | } | |
316 | } | |
317 | } | |
318 | ||
319 | /* | |
320 | * send_res_msg - sends msg to all nameservers found in the "_res" structure. | |
321 | * This should reflect /etc/resolv.conf. We will get responses | |
322 | * which arent needed but is easier than checking to see if nameserver | |
323 | * isnt present. Returns number of messages successfully sent to | |
324 | * nameservers or -1 if no successful sends. | |
325 | */ | |
326 | static int send_res_msg(const char *msg, int len, int rcount) | |
327 | { | |
328 | int i; | |
329 | int sent = 0; | |
330 | int max_queries = IRCD_MIN(irc_nscount, rcount); | |
331 | ||
332 | /* RES_PRIMARY option is not implemented | |
333 | * if (res.options & RES_PRIMARY || 0 == max_queries) | |
334 | */ | |
335 | if (max_queries == 0) | |
336 | max_queries = 1; | |
337 | ||
42bda3f3 | 338 | for (i = 0; sent < max_queries && i < irc_nscount; i++) |
212380e3 | 339 | { |
80e150e1 | 340 | if (sendto(rb_get_fd(res_fd), msg, len, 0, |
212380e3 | 341 | (struct sockaddr *)&(irc_nsaddr_list[i]), |
80e150e1 | 342 | GET_SS_LEN(&irc_nsaddr_list[i])) == len) |
212380e3 | 343 | ++sent; |
344 | } | |
345 | ||
346 | return (sent); | |
347 | } | |
348 | ||
349 | /* | |
350 | * find_id - find a dns request id (id is determined by dn_mkquery) | |
351 | */ | |
352 | static struct reslist *find_id(int id) | |
353 | { | |
af81d5a0 | 354 | rb_dlink_node *ptr; |
212380e3 | 355 | struct reslist *request; |
356 | ||
8e69bb4e | 357 | RB_DLINK_FOREACH(ptr, request_list.head) |
212380e3 | 358 | { |
359 | request = ptr->data; | |
360 | ||
361 | if (request->id == id) | |
362 | return (request); | |
363 | } | |
364 | ||
365 | return (NULL); | |
366 | } | |
367 | ||
368 | /* | |
369 | * gethost_byname_type - get host address from name | |
370 | * | |
371 | */ | |
372 | void gethost_byname_type(const char *name, struct DNSQuery *query, int type) | |
373 | { | |
374 | assert(name != 0); | |
375 | do_query_name(query, name, NULL, type); | |
376 | } | |
377 | ||
378 | /* | |
379 | * gethost_byaddr - get host name from address | |
380 | */ | |
3ea5fee7 | 381 | void gethost_byaddr(const struct rb_sockaddr_storage *addr, struct DNSQuery *query) |
212380e3 | 382 | { |
383 | do_query_number(query, addr, NULL); | |
384 | } | |
385 | ||
386 | /* | |
387 | * do_query_name - nameserver lookup name | |
388 | */ | |
389 | static void do_query_name(struct DNSQuery *query, const char *name, struct reslist *request, | |
390 | int type) | |
391 | { | |
392 | char host_name[HOSTLEN + 1]; | |
393 | ||
907468c4 | 394 | rb_strlcpy(host_name, name, HOSTLEN + 1); |
212380e3 | 395 | add_local_domain(host_name, HOSTLEN); |
396 | ||
397 | if (request == NULL) | |
398 | { | |
399 | request = make_request(query); | |
8e43b0b4 | 400 | request->name = (char *)rb_malloc(strlen(host_name) + 1); |
212380e3 | 401 | strcpy(request->name, host_name); |
212380e3 | 402 | } |
403 | ||
907468c4 | 404 | rb_strlcpy(request->queryname, host_name, sizeof(request->queryname)); |
212380e3 | 405 | request->type = type; |
406 | query_name(request); | |
407 | } | |
408 | ||
409 | /* | |
410 | * do_query_number - Use this to do reverse IP# lookups. | |
411 | */ | |
3ea5fee7 | 412 | static void do_query_number(struct DNSQuery *query, const struct rb_sockaddr_storage *addr, |
212380e3 | 413 | struct reslist *request) |
414 | { | |
415 | const unsigned char *cp; | |
416 | ||
417 | if (request == NULL) | |
418 | { | |
419 | request = make_request(query); | |
3ea5fee7 | 420 | memcpy(&request->addr, addr, sizeof(struct rb_sockaddr_storage)); |
8e43b0b4 | 421 | request->name = (char *)rb_malloc(HOSTLEN + 1); |
212380e3 | 422 | } |
423 | ||
424 | if (addr->ss_family == AF_INET) | |
425 | { | |
cda884c6 | 426 | const struct sockaddr_in *v4 = (const struct sockaddr_in *)addr; |
212380e3 | 427 | cp = (const unsigned char *)&v4->sin_addr.s_addr; |
428 | ||
38e6acdd | 429 | rb_sprintf(request->queryname, "%u.%u.%u.%u.in-addr.arpa", (unsigned int)(cp[3]), |
212380e3 | 430 | (unsigned int)(cp[2]), (unsigned int)(cp[1]), (unsigned int)(cp[0])); |
431 | } | |
2c2e0aa9 | 432 | #ifdef RB_IPV6 |
212380e3 | 433 | else if (addr->ss_family == AF_INET6) |
434 | { | |
cda884c6 | 435 | const struct sockaddr_in6 *v6 = (const struct sockaddr_in6 *)addr; |
212380e3 | 436 | cp = (const unsigned char *)&v6->sin6_addr.s6_addr; |
437 | ||
438 | (void)sprintf(request->queryname, "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x." | |
439 | "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.ip6.arpa", | |
440 | (unsigned int)(cp[15] & 0xf), (unsigned int)(cp[15] >> 4), | |
441 | (unsigned int)(cp[14] & 0xf), (unsigned int)(cp[14] >> 4), | |
442 | (unsigned int)(cp[13] & 0xf), (unsigned int)(cp[13] >> 4), | |
443 | (unsigned int)(cp[12] & 0xf), (unsigned int)(cp[12] >> 4), | |
444 | (unsigned int)(cp[11] & 0xf), (unsigned int)(cp[11] >> 4), | |
445 | (unsigned int)(cp[10] & 0xf), (unsigned int)(cp[10] >> 4), | |
446 | (unsigned int)(cp[9] & 0xf), (unsigned int)(cp[9] >> 4), | |
447 | (unsigned int)(cp[8] & 0xf), (unsigned int)(cp[8] >> 4), | |
448 | (unsigned int)(cp[7] & 0xf), (unsigned int)(cp[7] >> 4), | |
449 | (unsigned int)(cp[6] & 0xf), (unsigned int)(cp[6] >> 4), | |
450 | (unsigned int)(cp[5] & 0xf), (unsigned int)(cp[5] >> 4), | |
451 | (unsigned int)(cp[4] & 0xf), (unsigned int)(cp[4] >> 4), | |
452 | (unsigned int)(cp[3] & 0xf), (unsigned int)(cp[3] >> 4), | |
453 | (unsigned int)(cp[2] & 0xf), (unsigned int)(cp[2] >> 4), | |
454 | (unsigned int)(cp[1] & 0xf), (unsigned int)(cp[1] >> 4), | |
455 | (unsigned int)(cp[0] & 0xf), (unsigned int)(cp[0] >> 4)); | |
456 | } | |
457 | #endif | |
458 | ||
459 | request->type = T_PTR; | |
460 | query_name(request); | |
461 | } | |
462 | ||
463 | /* | |
464 | * query_name - generate a query based on class, type and name. | |
465 | */ | |
466 | static void query_name(struct reslist *request) | |
467 | { | |
468 | char buf[MAXPACKET]; | |
469 | int request_len = 0; | |
470 | ||
471 | memset(buf, 0, sizeof(buf)); | |
472 | ||
473 | if ((request_len = | |
474 | irc_res_mkquery(request->queryname, C_IN, request->type, (unsigned char *)buf, sizeof(buf))) > 0) | |
475 | { | |
476 | HEADER *header = (HEADER *) buf; | |
477 | #ifndef HAVE_LRAND48 | |
478 | int k = 0; | |
479 | struct timeval tv; | |
480 | #endif | |
481 | /* | |
482 | * generate an unique id | |
483 | * NOTE: we don't have to worry about converting this to and from | |
484 | * network byte order, the nameserver does not interpret this value | |
485 | * and returns it unchanged | |
486 | */ | |
487 | #ifdef HAVE_LRAND48 | |
488 | do | |
489 | { | |
490 | header->id = (header->id + lrand48()) & 0xffff; | |
491 | } while (find_id(header->id)); | |
492 | #else | |
493 | gettimeofday(&tv, NULL); | |
494 | do | |
495 | { | |
496 | header->id = (header->id + k + tv.tv_usec) & 0xffff; | |
497 | k++; | |
498 | } while (find_id(header->id)); | |
499 | #endif /* HAVE_LRAND48 */ | |
500 | request->id = header->id; | |
501 | ++request->sends; | |
502 | ||
503 | request->sent += send_res_msg(buf, request_len, request->sends); | |
504 | } | |
505 | } | |
506 | ||
507 | static void resend_query(struct reslist *request) | |
508 | { | |
509 | if (request->resend == 0) | |
510 | return; | |
511 | ||
512 | switch (request->type) | |
513 | { | |
514 | case T_PTR: | |
515 | do_query_number(NULL, &request->addr, request); | |
516 | break; | |
517 | case T_A: | |
2c2e0aa9 | 518 | #ifdef RB_IPV6 |
212380e3 | 519 | case T_AAAA: |
520 | #endif | |
521 | do_query_name(NULL, request->name, request, request->type); | |
522 | break; | |
523 | default: | |
524 | break; | |
525 | } | |
526 | } | |
527 | ||
528 | /* | |
529 | * check_question - check if the reply really belongs to the | |
530 | * name we queried (to guard against late replies from previous | |
531 | * queries with the same id). | |
532 | */ | |
533 | static int check_question(struct reslist *request, HEADER * header, char *buf, char *eob) | |
534 | { | |
535 | char hostbuf[128]; /* working buffer */ | |
536 | unsigned char *current; /* current position in buf */ | |
537 | int n; /* temp count */ | |
538 | ||
539 | current = (unsigned char *)buf + sizeof(HEADER); | |
540 | if (header->qdcount != 1) | |
541 | return 0; | |
542 | n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current, hostbuf, | |
543 | sizeof(hostbuf)); | |
544 | if (n <= 0) | |
545 | return 0; | |
546 | if (strcasecmp(hostbuf, request->queryname)) | |
547 | return 0; | |
548 | return 1; | |
549 | } | |
550 | ||
551 | /* | |
552 | * proc_answer - process name server reply | |
553 | */ | |
554 | static int proc_answer(struct reslist *request, HEADER * header, char *buf, char *eob) | |
555 | { | |
556 | char hostbuf[HOSTLEN + 100]; /* working buffer */ | |
557 | unsigned char *current; /* current position in buf */ | |
558 | int query_class; /* answer class */ | |
559 | int type; /* answer type */ | |
560 | int n; /* temp count */ | |
561 | int rd_length; | |
562 | struct sockaddr_in *v4; /* conversion */ | |
2c2e0aa9 | 563 | #ifdef RB_IPV6 |
212380e3 | 564 | struct sockaddr_in6 *v6; |
565 | #endif | |
566 | current = (unsigned char *)buf + sizeof(HEADER); | |
567 | ||
568 | for (; header->qdcount > 0; --header->qdcount) | |
569 | { | |
570 | if ((n = irc_dn_skipname(current, (unsigned char *)eob)) < 0) | |
571 | return 0; | |
572 | ||
573 | current += (size_t) n + QFIXEDSZ; | |
574 | } | |
575 | ||
576 | /* | |
577 | * process each answer sent to us blech. | |
578 | */ | |
579 | while (header->ancount > 0 && (char *)current < eob) | |
580 | { | |
581 | header->ancount--; | |
582 | ||
583 | n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current, hostbuf, | |
584 | sizeof(hostbuf)); | |
585 | ||
586 | if (n < 0) | |
587 | { | |
588 | /* | |
589 | * broken message | |
590 | */ | |
591 | return (0); | |
592 | } | |
593 | else if (n == 0) | |
594 | { | |
595 | /* | |
596 | * no more answers left | |
597 | */ | |
598 | return (0); | |
599 | } | |
600 | ||
601 | hostbuf[HOSTLEN] = '\0'; | |
602 | ||
603 | /* With Address arithmetic you have to be very anal | |
604 | * this code was not working on alpha due to that | |
605 | * (spotted by rodder/jailbird/dianora) | |
606 | */ | |
607 | current += (size_t) n; | |
608 | ||
609 | if (!(((char *)current + ANSWER_FIXED_SIZE) < eob)) | |
610 | break; | |
611 | ||
612 | type = irc_ns_get16(current); | |
613 | current += TYPE_SIZE; | |
614 | ||
615 | query_class = irc_ns_get16(current); | |
616 | current += CLASS_SIZE; | |
617 | ||
618 | request->ttl = irc_ns_get32(current); | |
619 | current += TTL_SIZE; | |
620 | ||
621 | rd_length = irc_ns_get16(current); | |
622 | current += RDLENGTH_SIZE; | |
623 | ||
624 | /* | |
625 | * Wait to set request->type until we verify this structure | |
626 | */ | |
627 | switch (type) | |
628 | { | |
629 | case T_A: | |
630 | if (request->type != T_A) | |
631 | return (0); | |
632 | ||
633 | /* | |
634 | * check for invalid rd_length or too many addresses | |
635 | */ | |
636 | if (rd_length != sizeof(struct in_addr)) | |
637 | return (0); | |
638 | v4 = (struct sockaddr_in *)&request->addr; | |
80e150e1 | 639 | SET_SS_LEN(&request->addr, sizeof(struct sockaddr_in)); |
212380e3 | 640 | v4->sin_family = AF_INET; |
641 | memcpy(&v4->sin_addr, current, sizeof(struct in_addr)); | |
642 | return (1); | |
643 | break; | |
2c2e0aa9 | 644 | #ifdef RB_IPV6 |
212380e3 | 645 | case T_AAAA: |
646 | if (request->type != T_AAAA) | |
647 | return (0); | |
648 | if (rd_length != sizeof(struct in6_addr)) | |
649 | return (0); | |
80e150e1 | 650 | SET_SS_LEN(&request->addr, sizeof(struct sockaddr_in6)); |
212380e3 | 651 | v6 = (struct sockaddr_in6 *)&request->addr; |
652 | v6->sin6_family = AF_INET6; | |
653 | memcpy(&v6->sin6_addr, current, sizeof(struct in6_addr)); | |
654 | return (1); | |
655 | break; | |
656 | #endif | |
657 | case T_PTR: | |
658 | if (request->type != T_PTR) | |
659 | return (0); | |
660 | n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current, | |
661 | hostbuf, sizeof(hostbuf)); | |
662 | if (n < 0) | |
663 | return (0); /* broken message */ | |
664 | else if (n == 0) | |
665 | return (0); /* no more answers left */ | |
666 | ||
907468c4 | 667 | rb_strlcpy(request->name, hostbuf, HOSTLEN + 1); |
212380e3 | 668 | |
669 | return (1); | |
670 | break; | |
0accfaf3 JT |
671 | case T_CNAME: |
672 | /* real answer will follow */ | |
212380e3 | 673 | current += rd_length; |
674 | break; | |
675 | ||
676 | default: | |
677 | /* XXX I'd rather just throw away the entire bogus thing | |
678 | * but its possible its just a broken nameserver with still | |
679 | * valid answers. But lets do some rudimentary logging for now... | |
680 | */ | |
681 | ilog(L_MAIN, "irc_res.c bogus type %d", type); | |
682 | break; | |
683 | } | |
684 | } | |
685 | ||
686 | return (1); | |
687 | } | |
688 | ||
689 | /* | |
690 | * res_readreply - read a dns reply from the nameserver and process it. | |
691 | */ | |
80e150e1 | 692 | static void res_readreply(rb_fde_t *F, void *data) |
212380e3 | 693 | { |
694 | char buf[sizeof(HEADER) + MAXPACKET] | |
695 | /* Sparc and alpha need 16bit-alignment for accessing header->id | |
696 | * (which is uint16_t). Because of the header = (HEADER*) buf; | |
697 | * lateron, this is neeeded. --FaUl | |
698 | */ | |
699 | #if defined(__sparc__) || defined(__alpha__) | |
700 | __attribute__ ((aligned(16))) | |
701 | #endif | |
702 | ; | |
703 | HEADER *header; | |
704 | struct reslist *request = NULL; | |
705 | struct DNSReply *reply = NULL; | |
706 | int rc; | |
707 | int answer_count; | |
3ea5fee7 VY |
708 | socklen_t len = sizeof(struct rb_sockaddr_storage); |
709 | struct rb_sockaddr_storage lsin; | |
212380e3 | 710 | |
80e150e1 | 711 | rc = recvfrom(rb_get_fd(F), buf, sizeof(buf), 0, (struct sockaddr *)&lsin, &len); |
212380e3 | 712 | |
713 | /* Re-schedule a read *after* recvfrom, or we'll be registering | |
714 | * interest where it'll instantly be ready for read :-) -- adrian | |
715 | */ | |
80e150e1 | 716 | rb_setselect(F, RB_SELECT_READ, res_readreply, NULL); |
212380e3 | 717 | /* Better to cast the sizeof instead of rc */ |
718 | if (rc <= (int)(sizeof(HEADER))) | |
719 | return; | |
720 | ||
721 | /* | |
722 | * convert DNS reply reader from Network byte order to CPU byte order. | |
723 | */ | |
724 | header = (HEADER *) buf; | |
725 | header->ancount = ntohs(header->ancount); | |
726 | header->qdcount = ntohs(header->qdcount); | |
727 | header->nscount = ntohs(header->nscount); | |
728 | header->arcount = ntohs(header->arcount); | |
729 | ||
730 | /* | |
731 | * response for an id which we have already received an answer for | |
732 | * just ignore this response. | |
733 | */ | |
734 | if (0 == (request = find_id(header->id))) | |
735 | return; | |
736 | ||
737 | /* | |
738 | * check against possibly fake replies | |
739 | */ | |
740 | if (!res_ourserver(&lsin)) | |
741 | return; | |
742 | ||
743 | if (!check_question(request, header, buf, buf + rc)) | |
744 | return; | |
745 | ||
746 | if ((header->rcode != NO_ERRORS) || (header->ancount == 0)) | |
747 | { | |
748 | if (NXDOMAIN == header->rcode) | |
749 | { | |
750 | (*request->query->callback) (request->query->ptr, NULL); | |
751 | rem_request(request); | |
752 | } | |
753 | else | |
754 | { | |
755 | /* | |
756 | * If a bad error was returned, we stop here and dont send | |
757 | * send any more (no retries granted). | |
758 | */ | |
759 | (*request->query->callback) (request->query->ptr, NULL); | |
760 | rem_request(request); | |
761 | } | |
762 | return; | |
763 | } | |
764 | /* | |
765 | * If this fails there was an error decoding the received packet, | |
766 | * give up. -- jilles | |
767 | */ | |
768 | answer_count = proc_answer(request, header, buf, buf + rc); | |
769 | ||
770 | if (answer_count) | |
771 | { | |
772 | if (request->type == T_PTR) | |
773 | { | |
774 | if (request->name == NULL) | |
775 | { | |
776 | /* | |
777 | * got a PTR response with no name, something bogus is happening | |
778 | * don't bother trying again, the client address doesn't resolve | |
779 | */ | |
780 | (*request->query->callback) (request->query->ptr, reply); | |
781 | rem_request(request); | |
782 | return; | |
783 | } | |
784 | ||
785 | /* | |
786 | * Lookup the 'authoritative' name that we were given for the | |
787 | * ip#. | |
788 | * | |
789 | */ | |
2c2e0aa9 | 790 | #ifdef RB_IPV6 |
212380e3 | 791 | if (request->addr.ss_family == AF_INET6) |
792 | gethost_byname_type(request->name, request->query, T_AAAA); | |
793 | else | |
794 | #endif | |
795 | gethost_byname_type(request->name, request->query, T_A); | |
796 | rem_request(request); | |
797 | } | |
798 | else | |
799 | { | |
800 | /* | |
801 | * got a name and address response, client resolved | |
802 | */ | |
803 | reply = make_dnsreply(request); | |
804 | (*request->query->callback) (request->query->ptr, reply); | |
90a3c35b | 805 | rb_free(reply); |
212380e3 | 806 | rem_request(request); |
807 | } | |
808 | } | |
809 | else | |
810 | { | |
811 | /* couldn't decode, give up -- jilles */ | |
812 | (*request->query->callback) (request->query->ptr, NULL); | |
813 | rem_request(request); | |
814 | } | |
815 | } | |
816 | ||
817 | static struct DNSReply *make_dnsreply(struct reslist *request) | |
818 | { | |
819 | struct DNSReply *cp; | |
820 | s_assert(request != 0); | |
821 | ||
8e43b0b4 | 822 | cp = (struct DNSReply *)rb_malloc(sizeof(struct DNSReply)); |
212380e3 | 823 | |
824 | cp->h_name = request->name; | |
825 | memcpy(&cp->addr, &request->addr, sizeof(cp->addr)); | |
826 | return (cp); | |
827 | } | |
828 | ||
829 | void report_dns_servers(struct Client *source_p) | |
830 | { | |
831 | int i; | |
832 | char ipaddr[128]; | |
833 | ||
834 | for (i = 0; i < irc_nscount; i++) | |
835 | { | |
9879cd59 | 836 | if (!rb_inet_ntop_sock((struct sockaddr *)&(irc_nsaddr_list[i]), |
212380e3 | 837 | ipaddr, sizeof ipaddr)) |
907468c4 | 838 | rb_strlcpy(ipaddr, "?", sizeof ipaddr); |
212380e3 | 839 | sendto_one_numeric(source_p, RPL_STATSDEBUG, |
840 | "A %s", ipaddr); | |
841 | } | |
842 | } |