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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 | ||
59 | typedef enum | |
60 | { | |
61 | REQ_IDLE, /* We're doing not much at all */ | |
62 | REQ_PTR, /* Looking up a PTR */ | |
63 | REQ_A, /* Looking up an A or AAAA */ | |
64 | REQ_CNAME /* We got a CNAME in response, we better get a real answer next */ | |
65 | } request_state; | |
66 | ||
67 | struct reslist | |
68 | { | |
af81d5a0 | 69 | rb_dlink_node node; |
212380e3 | 70 | int id; |
71 | int sent; /* number of requests sent */ | |
72 | request_state state; /* State the resolver machine is in */ | |
73 | time_t ttl; | |
74 | char type; | |
75 | char queryname[128]; /* name currently being queried */ | |
76 | char retries; /* retry counter */ | |
77 | char sends; /* number of sends (>1 means resent) */ | |
78 | char resend; /* send flag. 0 == dont resend */ | |
79 | time_t sentat; | |
80 | time_t timeout; | |
3ea5fee7 | 81 | struct rb_sockaddr_storage addr; |
212380e3 | 82 | char *name; |
83 | struct DNSQuery *query; /* query callback for this request */ | |
84 | }; | |
85 | ||
80e150e1 | 86 | static rb_fde_t *res_fd; |
af81d5a0 | 87 | static rb_dlink_list request_list = { NULL, NULL, 0 }; |
212380e3 | 88 | |
89 | static void rem_request(struct reslist *request); | |
90 | static struct reslist *make_request(struct DNSQuery *query); | |
91 | static void do_query_name(struct DNSQuery *query, const char *name, struct reslist *request, int); | |
3ea5fee7 | 92 | static void do_query_number(struct DNSQuery *query, const struct rb_sockaddr_storage *, |
212380e3 | 93 | struct reslist *request); |
94 | static void query_name(struct reslist *request); | |
95 | static int send_res_msg(const char *buf, int len, int count); | |
96 | static void resend_query(struct reslist *request); | |
97 | static int check_question(struct reslist *request, HEADER * header, char *buf, char *eob); | |
98 | static int proc_answer(struct reslist *request, HEADER * header, char *, char *); | |
99 | static struct reslist *find_id(int id); | |
100 | static struct DNSReply *make_dnsreply(struct reslist *request); | |
101 | ||
212380e3 | 102 | extern char irc_domain[HOSTLEN + 1]; |
103 | ||
104 | ||
105 | /* | |
106 | * int | |
107 | * res_ourserver(inp) | |
108 | * looks up "inp" in irc_nsaddr_list[] | |
109 | * returns: | |
110 | * 0 : not found | |
111 | * >0 : found | |
112 | * author: | |
113 | * paul vixie, 29may94 | |
114 | * revised for ircd, cryogen(stu) may03 | |
115 | */ | |
3ea5fee7 | 116 | static int res_ourserver(const struct rb_sockaddr_storage *inp) |
212380e3 | 117 | { |
2c2e0aa9 | 118 | #ifdef RB_IPV6 |
cda884c6 JT |
119 | const struct sockaddr_in6 *v6; |
120 | const struct sockaddr_in6 *v6in = (const struct sockaddr_in6 *)inp; | |
212380e3 | 121 | #endif |
cda884c6 JT |
122 | const struct sockaddr_in *v4; |
123 | const struct sockaddr_in *v4in = (const struct sockaddr_in *)inp; | |
212380e3 | 124 | int ns; |
125 | ||
126 | for (ns = 0; ns < irc_nscount; ns++) | |
127 | { | |
3ea5fee7 | 128 | const struct rb_sockaddr_storage *srv = &irc_nsaddr_list[ns]; |
2c2e0aa9 | 129 | #ifdef RB_IPV6 |
cda884c6 | 130 | v6 = (const struct sockaddr_in6 *)srv; |
212380e3 | 131 | #endif |
cda884c6 | 132 | v4 = (const struct sockaddr_in *)srv; |
212380e3 | 133 | |
134 | /* could probably just memcmp(srv, inp, srv.ss_len) here | |
135 | * but we'll air on the side of caution - stu | |
136 | */ | |
137 | switch (srv->ss_family) | |
138 | { | |
2c2e0aa9 | 139 | #ifdef RB_IPV6 |
212380e3 | 140 | case AF_INET6: |
141 | if (srv->ss_family == inp->ss_family) | |
142 | if (v6->sin6_port == v6in->sin6_port) | |
143 | if ((memcmp(&v6->sin6_addr.s6_addr, &v6in->sin6_addr.s6_addr, | |
144 | sizeof(struct in6_addr)) == 0) || | |
145 | (memcmp(&v6->sin6_addr.s6_addr, &in6addr_any, | |
146 | sizeof(struct in6_addr)) == 0)) | |
147 | return 1; | |
148 | break; | |
149 | #endif | |
150 | case AF_INET: | |
151 | if (srv->ss_family == inp->ss_family) | |
152 | if (v4->sin_port == v4in->sin_port) | |
153 | if ((v4->sin_addr.s_addr == INADDR_ANY) | |
154 | || (v4->sin_addr.s_addr == v4in->sin_addr.s_addr)) | |
155 | return 1; | |
156 | break; | |
157 | default: | |
158 | break; | |
159 | } | |
160 | } | |
161 | ||
162 | return 0; | |
163 | } | |
164 | ||
165 | /* | |
166 | * timeout_query_list - Remove queries from the list which have been | |
167 | * there too long without being resolved. | |
168 | */ | |
169 | static time_t timeout_query_list(time_t now) | |
170 | { | |
af81d5a0 | 171 | rb_dlink_node *ptr; |
90a3c35b | 172 | rb_dlink_node *next_ptr; |
212380e3 | 173 | struct reslist *request; |
174 | time_t next_time = 0; | |
175 | time_t timeout = 0; | |
176 | ||
90a3c35b | 177 | RB_DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head) |
212380e3 | 178 | { |
179 | request = ptr->data; | |
180 | timeout = request->sentat + request->timeout; | |
181 | ||
182 | if (now >= timeout) | |
183 | { | |
184 | if (--request->retries <= 0) | |
185 | { | |
186 | (*request->query->callback) (request->query->ptr, NULL); | |
187 | rem_request(request); | |
188 | continue; | |
189 | } | |
190 | else | |
191 | { | |
192 | request->sentat = now; | |
193 | request->timeout += request->timeout; | |
194 | resend_query(request); | |
195 | } | |
196 | } | |
197 | ||
198 | if ((next_time == 0) || timeout < next_time) | |
199 | { | |
200 | next_time = timeout; | |
201 | } | |
202 | } | |
203 | ||
204 | return (next_time > now) ? next_time : (now + AR_TTL); | |
205 | } | |
206 | ||
207 | /* | |
208 | * timeout_resolver - check request list | |
209 | */ | |
210 | static void timeout_resolver(void *notused) | |
211 | { | |
9f6bbe3c | 212 | timeout_query_list(rb_current_time()); |
212380e3 | 213 | } |
214 | ||
80e150e1 WP |
215 | static struct ev_entry *timeout_resolver_ev = NULL; |
216 | ||
212380e3 | 217 | /* |
218 | * start_resolver - do everything we need to read the resolv.conf file | |
219 | * and initialize the resolver file descriptor if needed | |
220 | */ | |
221 | static void start_resolver(void) | |
222 | { | |
223 | irc_res_init(); | |
224 | ||
cda884c6 | 225 | if (res_fd == NULL) |
212380e3 | 226 | { |
38e6acdd | 227 | if ((res_fd = rb_socket(irc_nsaddr_list[0].ss_family, SOCK_DGRAM, 0, |
80e150e1 | 228 | "UDP resolver socket")) == NULL) |
212380e3 | 229 | return; |
230 | ||
231 | /* At the moment, the resolver FD data is global .. */ | |
80e150e1 WP |
232 | rb_setselect(res_fd, RB_SELECT_READ, res_readreply, NULL); |
233 | timeout_resolver_ev = rb_event_add("timeout_resolver", timeout_resolver, NULL, 1); | |
212380e3 | 234 | } |
235 | } | |
236 | ||
237 | /* | |
238 | * init_resolver - initialize resolver and resolver library | |
239 | */ | |
240 | void init_resolver(void) | |
241 | { | |
242 | #ifdef HAVE_SRAND48 | |
9f6bbe3c | 243 | srand48(rb_current_time()); |
212380e3 | 244 | #endif |
245 | start_resolver(); | |
246 | } | |
247 | ||
248 | /* | |
249 | * restart_resolver - reread resolv.conf, reopen socket | |
250 | */ | |
251 | void restart_resolver(void) | |
252 | { | |
38e6acdd | 253 | rb_close(res_fd); |
80e150e1 WP |
254 | res_fd = NULL; |
255 | rb_event_delete(timeout_resolver_ev); /* -ddosen */ | |
212380e3 | 256 | start_resolver(); |
257 | } | |
258 | ||
259 | /* | |
260 | * add_local_domain - Add the domain to hostname, if it is missing | |
261 | * (as suggested by eps@TOASTER.SFSU.EDU) | |
262 | */ | |
263 | void add_local_domain(char *hname, size_t size) | |
264 | { | |
265 | /* try to fix up unqualified names */ | |
266 | if (strchr(hname, '.') == NULL) | |
267 | { | |
268 | if (irc_domain[0]) | |
269 | { | |
270 | size_t len = strlen(hname); | |
271 | ||
272 | if ((strlen(irc_domain) + len + 2) < size) | |
273 | { | |
274 | hname[len++] = '.'; | |
275 | strcpy(hname + len, irc_domain); | |
276 | } | |
277 | } | |
278 | } | |
279 | } | |
280 | ||
281 | /* | |
282 | * rem_request - remove a request from the list. | |
283 | * This must also free any memory that has been allocated for | |
284 | * temporary storage of DNS results. | |
285 | */ | |
286 | static void rem_request(struct reslist *request) | |
287 | { | |
af81d5a0 | 288 | rb_dlinkDelete(&request->node, &request_list); |
90a3c35b VY |
289 | rb_free(request->name); |
290 | rb_free(request); | |
212380e3 | 291 | } |
292 | ||
293 | /* | |
294 | * make_request - Create a DNS request record for the server. | |
295 | */ | |
296 | static struct reslist *make_request(struct DNSQuery *query) | |
297 | { | |
8e43b0b4 | 298 | struct reslist *request = rb_malloc(sizeof(struct reslist)); |
212380e3 | 299 | |
9f6bbe3c | 300 | request->sentat = rb_current_time(); |
212380e3 | 301 | request->retries = 3; |
302 | request->resend = 1; | |
303 | request->timeout = 4; /* start at 4 and exponential inc. */ | |
304 | request->query = query; | |
305 | request->state = REQ_IDLE; | |
306 | ||
af81d5a0 | 307 | rb_dlinkAdd(request, &request->node, &request_list); |
212380e3 | 308 | |
309 | return request; | |
310 | } | |
311 | ||
312 | /* | |
313 | * delete_resolver_queries - cleanup outstanding queries | |
314 | * for which there no longer exist clients or conf lines. | |
315 | */ | |
316 | void delete_resolver_queries(const struct DNSQuery *query) | |
317 | { | |
af81d5a0 | 318 | rb_dlink_node *ptr; |
90a3c35b | 319 | rb_dlink_node *next_ptr; |
212380e3 | 320 | struct reslist *request; |
321 | ||
90a3c35b | 322 | RB_DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head) |
212380e3 | 323 | { |
324 | if ((request = ptr->data) != NULL) | |
325 | { | |
326 | if (query == request->query) | |
327 | rem_request(request); | |
328 | } | |
329 | } | |
330 | } | |
331 | ||
332 | /* | |
333 | * send_res_msg - sends msg to all nameservers found in the "_res" structure. | |
334 | * This should reflect /etc/resolv.conf. We will get responses | |
335 | * which arent needed but is easier than checking to see if nameserver | |
336 | * isnt present. Returns number of messages successfully sent to | |
337 | * nameservers or -1 if no successful sends. | |
338 | */ | |
339 | static int send_res_msg(const char *msg, int len, int rcount) | |
340 | { | |
341 | int i; | |
342 | int sent = 0; | |
343 | int max_queries = IRCD_MIN(irc_nscount, rcount); | |
344 | ||
345 | /* RES_PRIMARY option is not implemented | |
346 | * if (res.options & RES_PRIMARY || 0 == max_queries) | |
347 | */ | |
348 | if (max_queries == 0) | |
349 | max_queries = 1; | |
350 | ||
42bda3f3 | 351 | for (i = 0; sent < max_queries && i < irc_nscount; i++) |
212380e3 | 352 | { |
80e150e1 | 353 | if (sendto(rb_get_fd(res_fd), msg, len, 0, |
212380e3 | 354 | (struct sockaddr *)&(irc_nsaddr_list[i]), |
80e150e1 | 355 | GET_SS_LEN(&irc_nsaddr_list[i])) == len) |
212380e3 | 356 | ++sent; |
357 | } | |
358 | ||
359 | return (sent); | |
360 | } | |
361 | ||
362 | /* | |
363 | * find_id - find a dns request id (id is determined by dn_mkquery) | |
364 | */ | |
365 | static struct reslist *find_id(int id) | |
366 | { | |
af81d5a0 | 367 | rb_dlink_node *ptr; |
212380e3 | 368 | struct reslist *request; |
369 | ||
8e69bb4e | 370 | RB_DLINK_FOREACH(ptr, request_list.head) |
212380e3 | 371 | { |
372 | request = ptr->data; | |
373 | ||
374 | if (request->id == id) | |
375 | return (request); | |
376 | } | |
377 | ||
378 | return (NULL); | |
379 | } | |
380 | ||
381 | /* | |
382 | * gethost_byname_type - get host address from name | |
383 | * | |
384 | */ | |
385 | void gethost_byname_type(const char *name, struct DNSQuery *query, int type) | |
386 | { | |
387 | assert(name != 0); | |
388 | do_query_name(query, name, NULL, type); | |
389 | } | |
390 | ||
391 | /* | |
392 | * gethost_byaddr - get host name from address | |
393 | */ | |
3ea5fee7 | 394 | void gethost_byaddr(const struct rb_sockaddr_storage *addr, struct DNSQuery *query) |
212380e3 | 395 | { |
396 | do_query_number(query, addr, NULL); | |
397 | } | |
398 | ||
399 | /* | |
400 | * do_query_name - nameserver lookup name | |
401 | */ | |
402 | static void do_query_name(struct DNSQuery *query, const char *name, struct reslist *request, | |
403 | int type) | |
404 | { | |
405 | char host_name[HOSTLEN + 1]; | |
406 | ||
907468c4 | 407 | rb_strlcpy(host_name, name, HOSTLEN + 1); |
212380e3 | 408 | add_local_domain(host_name, HOSTLEN); |
409 | ||
410 | if (request == NULL) | |
411 | { | |
412 | request = make_request(query); | |
8e43b0b4 | 413 | request->name = (char *)rb_malloc(strlen(host_name) + 1); |
212380e3 | 414 | strcpy(request->name, host_name); |
415 | request->state = REQ_A; | |
416 | } | |
417 | ||
907468c4 | 418 | rb_strlcpy(request->queryname, host_name, sizeof(request->queryname)); |
212380e3 | 419 | request->type = type; |
420 | query_name(request); | |
421 | } | |
422 | ||
423 | /* | |
424 | * do_query_number - Use this to do reverse IP# lookups. | |
425 | */ | |
3ea5fee7 | 426 | static void do_query_number(struct DNSQuery *query, const struct rb_sockaddr_storage *addr, |
212380e3 | 427 | struct reslist *request) |
428 | { | |
429 | const unsigned char *cp; | |
430 | ||
431 | if (request == NULL) | |
432 | { | |
433 | request = make_request(query); | |
3ea5fee7 | 434 | memcpy(&request->addr, addr, sizeof(struct rb_sockaddr_storage)); |
8e43b0b4 | 435 | request->name = (char *)rb_malloc(HOSTLEN + 1); |
212380e3 | 436 | } |
437 | ||
438 | if (addr->ss_family == AF_INET) | |
439 | { | |
cda884c6 | 440 | const struct sockaddr_in *v4 = (const struct sockaddr_in *)addr; |
212380e3 | 441 | cp = (const unsigned char *)&v4->sin_addr.s_addr; |
442 | ||
38e6acdd | 443 | rb_sprintf(request->queryname, "%u.%u.%u.%u.in-addr.arpa", (unsigned int)(cp[3]), |
212380e3 | 444 | (unsigned int)(cp[2]), (unsigned int)(cp[1]), (unsigned int)(cp[0])); |
445 | } | |
2c2e0aa9 | 446 | #ifdef RB_IPV6 |
212380e3 | 447 | else if (addr->ss_family == AF_INET6) |
448 | { | |
cda884c6 | 449 | const struct sockaddr_in6 *v6 = (const struct sockaddr_in6 *)addr; |
212380e3 | 450 | cp = (const unsigned char *)&v6->sin6_addr.s6_addr; |
451 | ||
452 | (void)sprintf(request->queryname, "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x." | |
453 | "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.ip6.arpa", | |
454 | (unsigned int)(cp[15] & 0xf), (unsigned int)(cp[15] >> 4), | |
455 | (unsigned int)(cp[14] & 0xf), (unsigned int)(cp[14] >> 4), | |
456 | (unsigned int)(cp[13] & 0xf), (unsigned int)(cp[13] >> 4), | |
457 | (unsigned int)(cp[12] & 0xf), (unsigned int)(cp[12] >> 4), | |
458 | (unsigned int)(cp[11] & 0xf), (unsigned int)(cp[11] >> 4), | |
459 | (unsigned int)(cp[10] & 0xf), (unsigned int)(cp[10] >> 4), | |
460 | (unsigned int)(cp[9] & 0xf), (unsigned int)(cp[9] >> 4), | |
461 | (unsigned int)(cp[8] & 0xf), (unsigned int)(cp[8] >> 4), | |
462 | (unsigned int)(cp[7] & 0xf), (unsigned int)(cp[7] >> 4), | |
463 | (unsigned int)(cp[6] & 0xf), (unsigned int)(cp[6] >> 4), | |
464 | (unsigned int)(cp[5] & 0xf), (unsigned int)(cp[5] >> 4), | |
465 | (unsigned int)(cp[4] & 0xf), (unsigned int)(cp[4] >> 4), | |
466 | (unsigned int)(cp[3] & 0xf), (unsigned int)(cp[3] >> 4), | |
467 | (unsigned int)(cp[2] & 0xf), (unsigned int)(cp[2] >> 4), | |
468 | (unsigned int)(cp[1] & 0xf), (unsigned int)(cp[1] >> 4), | |
469 | (unsigned int)(cp[0] & 0xf), (unsigned int)(cp[0] >> 4)); | |
470 | } | |
471 | #endif | |
472 | ||
473 | request->type = T_PTR; | |
474 | query_name(request); | |
475 | } | |
476 | ||
477 | /* | |
478 | * query_name - generate a query based on class, type and name. | |
479 | */ | |
480 | static void query_name(struct reslist *request) | |
481 | { | |
482 | char buf[MAXPACKET]; | |
483 | int request_len = 0; | |
484 | ||
485 | memset(buf, 0, sizeof(buf)); | |
486 | ||
487 | if ((request_len = | |
488 | irc_res_mkquery(request->queryname, C_IN, request->type, (unsigned char *)buf, sizeof(buf))) > 0) | |
489 | { | |
490 | HEADER *header = (HEADER *) buf; | |
491 | #ifndef HAVE_LRAND48 | |
492 | int k = 0; | |
493 | struct timeval tv; | |
494 | #endif | |
495 | /* | |
496 | * generate an unique id | |
497 | * NOTE: we don't have to worry about converting this to and from | |
498 | * network byte order, the nameserver does not interpret this value | |
499 | * and returns it unchanged | |
500 | */ | |
501 | #ifdef HAVE_LRAND48 | |
502 | do | |
503 | { | |
504 | header->id = (header->id + lrand48()) & 0xffff; | |
505 | } while (find_id(header->id)); | |
506 | #else | |
507 | gettimeofday(&tv, NULL); | |
508 | do | |
509 | { | |
510 | header->id = (header->id + k + tv.tv_usec) & 0xffff; | |
511 | k++; | |
512 | } while (find_id(header->id)); | |
513 | #endif /* HAVE_LRAND48 */ | |
514 | request->id = header->id; | |
515 | ++request->sends; | |
516 | ||
517 | request->sent += send_res_msg(buf, request_len, request->sends); | |
518 | } | |
519 | } | |
520 | ||
521 | static void resend_query(struct reslist *request) | |
522 | { | |
523 | if (request->resend == 0) | |
524 | return; | |
525 | ||
526 | switch (request->type) | |
527 | { | |
528 | case T_PTR: | |
529 | do_query_number(NULL, &request->addr, request); | |
530 | break; | |
531 | case T_A: | |
2c2e0aa9 | 532 | #ifdef RB_IPV6 |
212380e3 | 533 | case T_AAAA: |
534 | #endif | |
535 | do_query_name(NULL, request->name, request, request->type); | |
536 | break; | |
537 | default: | |
538 | break; | |
539 | } | |
540 | } | |
541 | ||
542 | /* | |
543 | * check_question - check if the reply really belongs to the | |
544 | * name we queried (to guard against late replies from previous | |
545 | * queries with the same id). | |
546 | */ | |
547 | static int check_question(struct reslist *request, HEADER * header, char *buf, char *eob) | |
548 | { | |
549 | char hostbuf[128]; /* working buffer */ | |
550 | unsigned char *current; /* current position in buf */ | |
551 | int n; /* temp count */ | |
552 | ||
553 | current = (unsigned char *)buf + sizeof(HEADER); | |
554 | if (header->qdcount != 1) | |
555 | return 0; | |
556 | n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current, hostbuf, | |
557 | sizeof(hostbuf)); | |
558 | if (n <= 0) | |
559 | return 0; | |
560 | if (strcasecmp(hostbuf, request->queryname)) | |
561 | return 0; | |
562 | return 1; | |
563 | } | |
564 | ||
565 | /* | |
566 | * proc_answer - process name server reply | |
567 | */ | |
568 | static int proc_answer(struct reslist *request, HEADER * header, char *buf, char *eob) | |
569 | { | |
570 | char hostbuf[HOSTLEN + 100]; /* working buffer */ | |
571 | unsigned char *current; /* current position in buf */ | |
572 | int query_class; /* answer class */ | |
573 | int type; /* answer type */ | |
574 | int n; /* temp count */ | |
575 | int rd_length; | |
576 | struct sockaddr_in *v4; /* conversion */ | |
2c2e0aa9 | 577 | #ifdef RB_IPV6 |
212380e3 | 578 | struct sockaddr_in6 *v6; |
579 | #endif | |
580 | current = (unsigned char *)buf + sizeof(HEADER); | |
581 | ||
582 | for (; header->qdcount > 0; --header->qdcount) | |
583 | { | |
584 | if ((n = irc_dn_skipname(current, (unsigned char *)eob)) < 0) | |
585 | return 0; | |
586 | ||
587 | current += (size_t) n + QFIXEDSZ; | |
588 | } | |
589 | ||
590 | /* | |
591 | * process each answer sent to us blech. | |
592 | */ | |
593 | while (header->ancount > 0 && (char *)current < eob) | |
594 | { | |
595 | header->ancount--; | |
596 | ||
597 | n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current, hostbuf, | |
598 | sizeof(hostbuf)); | |
599 | ||
600 | if (n < 0) | |
601 | { | |
602 | /* | |
603 | * broken message | |
604 | */ | |
605 | return (0); | |
606 | } | |
607 | else if (n == 0) | |
608 | { | |
609 | /* | |
610 | * no more answers left | |
611 | */ | |
612 | return (0); | |
613 | } | |
614 | ||
615 | hostbuf[HOSTLEN] = '\0'; | |
616 | ||
617 | /* With Address arithmetic you have to be very anal | |
618 | * this code was not working on alpha due to that | |
619 | * (spotted by rodder/jailbird/dianora) | |
620 | */ | |
621 | current += (size_t) n; | |
622 | ||
623 | if (!(((char *)current + ANSWER_FIXED_SIZE) < eob)) | |
624 | break; | |
625 | ||
626 | type = irc_ns_get16(current); | |
627 | current += TYPE_SIZE; | |
628 | ||
629 | query_class = irc_ns_get16(current); | |
630 | current += CLASS_SIZE; | |
631 | ||
632 | request->ttl = irc_ns_get32(current); | |
633 | current += TTL_SIZE; | |
634 | ||
635 | rd_length = irc_ns_get16(current); | |
636 | current += RDLENGTH_SIZE; | |
637 | ||
638 | /* | |
639 | * Wait to set request->type until we verify this structure | |
640 | */ | |
641 | switch (type) | |
642 | { | |
643 | case T_A: | |
644 | if (request->type != T_A) | |
645 | return (0); | |
646 | ||
647 | /* | |
648 | * check for invalid rd_length or too many addresses | |
649 | */ | |
650 | if (rd_length != sizeof(struct in_addr)) | |
651 | return (0); | |
652 | v4 = (struct sockaddr_in *)&request->addr; | |
80e150e1 | 653 | SET_SS_LEN(&request->addr, sizeof(struct sockaddr_in)); |
212380e3 | 654 | v4->sin_family = AF_INET; |
655 | memcpy(&v4->sin_addr, current, sizeof(struct in_addr)); | |
656 | return (1); | |
657 | break; | |
2c2e0aa9 | 658 | #ifdef RB_IPV6 |
212380e3 | 659 | case T_AAAA: |
660 | if (request->type != T_AAAA) | |
661 | return (0); | |
662 | if (rd_length != sizeof(struct in6_addr)) | |
663 | return (0); | |
80e150e1 | 664 | SET_SS_LEN(&request->addr, sizeof(struct sockaddr_in6)); |
212380e3 | 665 | v6 = (struct sockaddr_in6 *)&request->addr; |
666 | v6->sin6_family = AF_INET6; | |
667 | memcpy(&v6->sin6_addr, current, sizeof(struct in6_addr)); | |
668 | return (1); | |
669 | break; | |
670 | #endif | |
671 | case T_PTR: | |
672 | if (request->type != T_PTR) | |
673 | return (0); | |
674 | n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current, | |
675 | hostbuf, sizeof(hostbuf)); | |
676 | if (n < 0) | |
677 | return (0); /* broken message */ | |
678 | else if (n == 0) | |
679 | return (0); /* no more answers left */ | |
680 | ||
907468c4 | 681 | rb_strlcpy(request->name, hostbuf, HOSTLEN + 1); |
212380e3 | 682 | |
683 | return (1); | |
684 | break; | |
685 | case T_CNAME: /* first check we already havent started looking | |
686 | into a cname */ | |
687 | if (request->type != T_PTR) | |
688 | return (0); | |
689 | ||
690 | if (request->state == REQ_CNAME) | |
691 | { | |
692 | n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, | |
693 | current, hostbuf, sizeof(hostbuf)); | |
694 | ||
695 | if (n < 0) | |
696 | return (0); | |
697 | return (1); | |
698 | } | |
699 | ||
700 | request->state = REQ_CNAME; | |
701 | current += rd_length; | |
702 | break; | |
703 | ||
704 | default: | |
705 | /* XXX I'd rather just throw away the entire bogus thing | |
706 | * but its possible its just a broken nameserver with still | |
707 | * valid answers. But lets do some rudimentary logging for now... | |
708 | */ | |
709 | ilog(L_MAIN, "irc_res.c bogus type %d", type); | |
710 | break; | |
711 | } | |
712 | } | |
713 | ||
714 | return (1); | |
715 | } | |
716 | ||
717 | /* | |
718 | * res_readreply - read a dns reply from the nameserver and process it. | |
719 | */ | |
80e150e1 | 720 | static void res_readreply(rb_fde_t *F, void *data) |
212380e3 | 721 | { |
722 | char buf[sizeof(HEADER) + MAXPACKET] | |
723 | /* Sparc and alpha need 16bit-alignment for accessing header->id | |
724 | * (which is uint16_t). Because of the header = (HEADER*) buf; | |
725 | * lateron, this is neeeded. --FaUl | |
726 | */ | |
727 | #if defined(__sparc__) || defined(__alpha__) | |
728 | __attribute__ ((aligned(16))) | |
729 | #endif | |
730 | ; | |
731 | HEADER *header; | |
732 | struct reslist *request = NULL; | |
733 | struct DNSReply *reply = NULL; | |
734 | int rc; | |
735 | int answer_count; | |
3ea5fee7 VY |
736 | socklen_t len = sizeof(struct rb_sockaddr_storage); |
737 | struct rb_sockaddr_storage lsin; | |
212380e3 | 738 | |
80e150e1 | 739 | rc = recvfrom(rb_get_fd(F), buf, sizeof(buf), 0, (struct sockaddr *)&lsin, &len); |
212380e3 | 740 | |
741 | /* Re-schedule a read *after* recvfrom, or we'll be registering | |
742 | * interest where it'll instantly be ready for read :-) -- adrian | |
743 | */ | |
80e150e1 | 744 | rb_setselect(F, RB_SELECT_READ, res_readreply, NULL); |
212380e3 | 745 | /* Better to cast the sizeof instead of rc */ |
746 | if (rc <= (int)(sizeof(HEADER))) | |
747 | return; | |
748 | ||
749 | /* | |
750 | * convert DNS reply reader from Network byte order to CPU byte order. | |
751 | */ | |
752 | header = (HEADER *) buf; | |
753 | header->ancount = ntohs(header->ancount); | |
754 | header->qdcount = ntohs(header->qdcount); | |
755 | header->nscount = ntohs(header->nscount); | |
756 | header->arcount = ntohs(header->arcount); | |
757 | ||
758 | /* | |
759 | * response for an id which we have already received an answer for | |
760 | * just ignore this response. | |
761 | */ | |
762 | if (0 == (request = find_id(header->id))) | |
763 | return; | |
764 | ||
765 | /* | |
766 | * check against possibly fake replies | |
767 | */ | |
768 | if (!res_ourserver(&lsin)) | |
769 | return; | |
770 | ||
771 | if (!check_question(request, header, buf, buf + rc)) | |
772 | return; | |
773 | ||
774 | if ((header->rcode != NO_ERRORS) || (header->ancount == 0)) | |
775 | { | |
776 | if (NXDOMAIN == header->rcode) | |
777 | { | |
778 | (*request->query->callback) (request->query->ptr, NULL); | |
779 | rem_request(request); | |
780 | } | |
781 | else | |
782 | { | |
783 | /* | |
784 | * If a bad error was returned, we stop here and dont send | |
785 | * send any more (no retries granted). | |
786 | */ | |
787 | (*request->query->callback) (request->query->ptr, NULL); | |
788 | rem_request(request); | |
789 | } | |
790 | return; | |
791 | } | |
792 | /* | |
793 | * If this fails there was an error decoding the received packet, | |
794 | * give up. -- jilles | |
795 | */ | |
796 | answer_count = proc_answer(request, header, buf, buf + rc); | |
797 | ||
798 | if (answer_count) | |
799 | { | |
800 | if (request->type == T_PTR) | |
801 | { | |
802 | if (request->name == NULL) | |
803 | { | |
804 | /* | |
805 | * got a PTR response with no name, something bogus is happening | |
806 | * don't bother trying again, the client address doesn't resolve | |
807 | */ | |
808 | (*request->query->callback) (request->query->ptr, reply); | |
809 | rem_request(request); | |
810 | return; | |
811 | } | |
812 | ||
813 | /* | |
814 | * Lookup the 'authoritative' name that we were given for the | |
815 | * ip#. | |
816 | * | |
817 | */ | |
2c2e0aa9 | 818 | #ifdef RB_IPV6 |
212380e3 | 819 | if (request->addr.ss_family == AF_INET6) |
820 | gethost_byname_type(request->name, request->query, T_AAAA); | |
821 | else | |
822 | #endif | |
823 | gethost_byname_type(request->name, request->query, T_A); | |
824 | rem_request(request); | |
825 | } | |
826 | else | |
827 | { | |
828 | /* | |
829 | * got a name and address response, client resolved | |
830 | */ | |
831 | reply = make_dnsreply(request); | |
832 | (*request->query->callback) (request->query->ptr, reply); | |
90a3c35b | 833 | rb_free(reply); |
212380e3 | 834 | rem_request(request); |
835 | } | |
836 | } | |
837 | else | |
838 | { | |
839 | /* couldn't decode, give up -- jilles */ | |
840 | (*request->query->callback) (request->query->ptr, NULL); | |
841 | rem_request(request); | |
842 | } | |
843 | } | |
844 | ||
845 | static struct DNSReply *make_dnsreply(struct reslist *request) | |
846 | { | |
847 | struct DNSReply *cp; | |
848 | s_assert(request != 0); | |
849 | ||
8e43b0b4 | 850 | cp = (struct DNSReply *)rb_malloc(sizeof(struct DNSReply)); |
212380e3 | 851 | |
852 | cp->h_name = request->name; | |
853 | memcpy(&cp->addr, &request->addr, sizeof(cp->addr)); | |
854 | return (cp); | |
855 | } | |
856 | ||
857 | void report_dns_servers(struct Client *source_p) | |
858 | { | |
859 | int i; | |
860 | char ipaddr[128]; | |
861 | ||
862 | for (i = 0; i < irc_nscount; i++) | |
863 | { | |
9879cd59 | 864 | if (!rb_inet_ntop_sock((struct sockaddr *)&(irc_nsaddr_list[i]), |
212380e3 | 865 | ipaddr, sizeof ipaddr)) |
907468c4 | 866 | rb_strlcpy(ipaddr, "?", sizeof ipaddr); |
212380e3 | 867 | sendto_one_numeric(source_p, RPL_STATSDEBUG, |
868 | "A %s", ipaddr); | |
869 | } | |
870 | } |