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Commit | Line | Data |
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212380e3 AC |
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 AC |
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 AC |
32 | #include "res.h" |
33 | #include "reslib.h" | |
212380e3 AC |
34 | #include "irc_string.h" |
35 | #include "sprintf_irc.h" | |
36 | #include "numeric.h" | |
37 | #include "client.h" /* SNO_* */ | |
38 | ||
39 | #if (CHAR_BIT != 8) | |
40 | #error this code needs to be able to address individual octets | |
41 | #endif | |
42 | ||
43 | static PF res_readreply; | |
44 | ||
45 | #define MAXPACKET 1024 /* rfc sez 512 but we expand names so ... */ | |
46 | #define RES_MAXALIASES 35 /* maximum aliases allowed */ | |
47 | #define RES_MAXADDRS 35 /* maximum addresses allowed */ | |
48 | #define AR_TTL 600 /* TTL in seconds for dns cache entries */ | |
49 | ||
50 | /* RFC 1104/1105 wasn't very helpful about what these fields | |
51 | * should be named, so for now, we'll just name them this way. | |
52 | * we probably should look at what named calls them or something. | |
53 | */ | |
54 | #define TYPE_SIZE (size_t)2 | |
55 | #define CLASS_SIZE (size_t)2 | |
56 | #define TTL_SIZE (size_t)4 | |
57 | #define RDLENGTH_SIZE (size_t)2 | |
58 | #define ANSWER_FIXED_SIZE (TYPE_SIZE + CLASS_SIZE + TTL_SIZE + RDLENGTH_SIZE) | |
59 | ||
60 | typedef enum | |
61 | { | |
62 | REQ_IDLE, /* We're doing not much at all */ | |
63 | REQ_PTR, /* Looking up a PTR */ | |
64 | REQ_A, /* Looking up an A or AAAA */ | |
65 | REQ_CNAME /* We got a CNAME in response, we better get a real answer next */ | |
66 | } request_state; | |
67 | ||
68 | struct reslist | |
69 | { | |
330fc5c1 | 70 | rb_dlink_node node; |
212380e3 AC |
71 | int id; |
72 | int sent; /* number of requests sent */ | |
73 | request_state state; /* State the resolver machine is in */ | |
74 | time_t ttl; | |
75 | char type; | |
76 | char queryname[128]; /* name currently being queried */ | |
77 | char retries; /* retry counter */ | |
78 | char sends; /* number of sends (>1 means resent) */ | |
79 | char resend; /* send flag. 0 == dont resend */ | |
80 | time_t sentat; | |
81 | time_t timeout; | |
e7046ee5 | 82 | struct rb_sockaddr_storage addr; |
212380e3 AC |
83 | char *name; |
84 | struct DNSQuery *query; /* query callback for this request */ | |
85 | }; | |
86 | ||
0f6d6f3d | 87 | static rb_fde_t *res_fd; |
330fc5c1 | 88 | static rb_dlink_list request_list = { NULL, NULL, 0 }; |
212380e3 AC |
89 | |
90 | static void rem_request(struct reslist *request); | |
91 | static struct reslist *make_request(struct DNSQuery *query); | |
92 | static void do_query_name(struct DNSQuery *query, const char *name, struct reslist *request, int); | |
e7046ee5 | 93 | static void do_query_number(struct DNSQuery *query, const struct rb_sockaddr_storage *, |
212380e3 AC |
94 | struct reslist *request); |
95 | static void query_name(struct reslist *request); | |
96 | static int send_res_msg(const char *buf, int len, int count); | |
97 | static void resend_query(struct reslist *request); | |
98 | static int check_question(struct reslist *request, HEADER * header, char *buf, char *eob); | |
99 | static int proc_answer(struct reslist *request, HEADER * header, char *, char *); | |
100 | static struct reslist *find_id(int id); | |
101 | static struct DNSReply *make_dnsreply(struct reslist *request); | |
102 | ||
e7046ee5 | 103 | extern struct rb_sockaddr_storage irc_nsaddr_list[IRCD_MAXNS]; |
212380e3 AC |
104 | extern int irc_nscount; |
105 | extern char irc_domain[HOSTLEN + 1]; | |
106 | ||
107 | ||
108 | /* | |
109 | * int | |
110 | * res_ourserver(inp) | |
111 | * looks up "inp" in irc_nsaddr_list[] | |
112 | * returns: | |
113 | * 0 : not found | |
114 | * >0 : found | |
115 | * author: | |
116 | * paul vixie, 29may94 | |
117 | * revised for ircd, cryogen(stu) may03 | |
118 | */ | |
e7046ee5 | 119 | static int res_ourserver(const struct rb_sockaddr_storage *inp) |
212380e3 | 120 | { |
ccda6e3f | 121 | #ifdef RB_IPV6 |
212380e3 AC |
122 | struct sockaddr_in6 *v6; |
123 | struct sockaddr_in6 *v6in = (struct sockaddr_in6 *)inp; | |
124 | #endif | |
125 | struct sockaddr_in *v4; | |
126 | struct sockaddr_in *v4in = (struct sockaddr_in *)inp; | |
127 | int ns; | |
128 | ||
129 | for (ns = 0; ns < irc_nscount; ns++) | |
130 | { | |
e7046ee5 | 131 | const struct rb_sockaddr_storage *srv = &irc_nsaddr_list[ns]; |
ccda6e3f | 132 | #ifdef RB_IPV6 |
212380e3 AC |
133 | v6 = (struct sockaddr_in6 *)srv; |
134 | #endif | |
135 | v4 = (struct sockaddr_in *)srv; | |
136 | ||
137 | /* could probably just memcmp(srv, inp, srv.ss_len) here | |
138 | * but we'll air on the side of caution - stu | |
139 | */ | |
140 | switch (srv->ss_family) | |
141 | { | |
ccda6e3f | 142 | #ifdef RB_IPV6 |
212380e3 AC |
143 | case AF_INET6: |
144 | if (srv->ss_family == inp->ss_family) | |
145 | if (v6->sin6_port == v6in->sin6_port) | |
146 | if ((memcmp(&v6->sin6_addr.s6_addr, &v6in->sin6_addr.s6_addr, | |
147 | sizeof(struct in6_addr)) == 0) || | |
148 | (memcmp(&v6->sin6_addr.s6_addr, &in6addr_any, | |
149 | sizeof(struct in6_addr)) == 0)) | |
150 | return 1; | |
151 | break; | |
152 | #endif | |
153 | case AF_INET: | |
154 | if (srv->ss_family == inp->ss_family) | |
155 | if (v4->sin_port == v4in->sin_port) | |
156 | if ((v4->sin_addr.s_addr == INADDR_ANY) | |
157 | || (v4->sin_addr.s_addr == v4in->sin_addr.s_addr)) | |
158 | return 1; | |
159 | break; | |
160 | default: | |
161 | break; | |
162 | } | |
163 | } | |
164 | ||
165 | return 0; | |
166 | } | |
167 | ||
168 | /* | |
169 | * timeout_query_list - Remove queries from the list which have been | |
170 | * there too long without being resolved. | |
171 | */ | |
172 | static time_t timeout_query_list(time_t now) | |
173 | { | |
330fc5c1 | 174 | rb_dlink_node *ptr; |
637c4932 | 175 | rb_dlink_node *next_ptr; |
212380e3 AC |
176 | struct reslist *request; |
177 | time_t next_time = 0; | |
178 | time_t timeout = 0; | |
179 | ||
637c4932 | 180 | RB_DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head) |
212380e3 AC |
181 | { |
182 | request = ptr->data; | |
183 | timeout = request->sentat + request->timeout; | |
184 | ||
185 | if (now >= timeout) | |
186 | { | |
187 | if (--request->retries <= 0) | |
188 | { | |
189 | (*request->query->callback) (request->query->ptr, NULL); | |
190 | rem_request(request); | |
191 | continue; | |
192 | } | |
193 | else | |
194 | { | |
195 | request->sentat = now; | |
196 | request->timeout += request->timeout; | |
197 | resend_query(request); | |
198 | } | |
199 | } | |
200 | ||
201 | if ((next_time == 0) || timeout < next_time) | |
202 | { | |
203 | next_time = timeout; | |
204 | } | |
205 | } | |
206 | ||
207 | return (next_time > now) ? next_time : (now + AR_TTL); | |
208 | } | |
209 | ||
210 | /* | |
211 | * timeout_resolver - check request list | |
212 | */ | |
213 | static void timeout_resolver(void *notused) | |
214 | { | |
e3354945 | 215 | timeout_query_list(rb_current_time()); |
212380e3 AC |
216 | } |
217 | ||
0f6d6f3d AC |
218 | static struct ev_entry *timeout_resolver_ev = NULL; |
219 | ||
212380e3 AC |
220 | /* |
221 | * start_resolver - do everything we need to read the resolv.conf file | |
222 | * and initialize the resolver file descriptor if needed | |
223 | */ | |
224 | static void start_resolver(void) | |
225 | { | |
226 | irc_res_init(); | |
227 | ||
228 | if (res_fd <= 0) /* there isn't any such thing as fd 0, that's just a myth. */ | |
229 | { | |
b2f0da88 | 230 | if ((res_fd = rb_socket(irc_nsaddr_list[0].ss_family, SOCK_DGRAM, 0, |
0f6d6f3d | 231 | "UDP resolver socket")) == NULL) |
212380e3 AC |
232 | return; |
233 | ||
234 | /* At the moment, the resolver FD data is global .. */ | |
0f6d6f3d AC |
235 | rb_setselect(res_fd, RB_SELECT_READ, res_readreply, NULL); |
236 | timeout_resolver_ev = rb_event_add("timeout_resolver", timeout_resolver, NULL, 1); | |
212380e3 AC |
237 | } |
238 | } | |
239 | ||
240 | /* | |
241 | * init_resolver - initialize resolver and resolver library | |
242 | */ | |
243 | void init_resolver(void) | |
244 | { | |
245 | #ifdef HAVE_SRAND48 | |
e3354945 | 246 | srand48(rb_current_time()); |
212380e3 AC |
247 | #endif |
248 | start_resolver(); | |
249 | } | |
250 | ||
251 | /* | |
252 | * restart_resolver - reread resolv.conf, reopen socket | |
253 | */ | |
254 | void restart_resolver(void) | |
255 | { | |
b2f0da88 | 256 | rb_close(res_fd); |
0f6d6f3d AC |
257 | res_fd = NULL; |
258 | rb_event_delete(timeout_resolver_ev); /* -ddosen */ | |
212380e3 AC |
259 | start_resolver(); |
260 | } | |
261 | ||
262 | /* | |
263 | * add_local_domain - Add the domain to hostname, if it is missing | |
264 | * (as suggested by eps@TOASTER.SFSU.EDU) | |
265 | */ | |
266 | void add_local_domain(char *hname, size_t size) | |
267 | { | |
268 | /* try to fix up unqualified names */ | |
269 | if (strchr(hname, '.') == NULL) | |
270 | { | |
271 | if (irc_domain[0]) | |
272 | { | |
273 | size_t len = strlen(hname); | |
274 | ||
275 | if ((strlen(irc_domain) + len + 2) < size) | |
276 | { | |
277 | hname[len++] = '.'; | |
278 | strcpy(hname + len, irc_domain); | |
279 | } | |
280 | } | |
281 | } | |
282 | } | |
283 | ||
284 | /* | |
285 | * rem_request - remove a request from the list. | |
286 | * This must also free any memory that has been allocated for | |
287 | * temporary storage of DNS results. | |
288 | */ | |
289 | static void rem_request(struct reslist *request) | |
290 | { | |
330fc5c1 | 291 | rb_dlinkDelete(&request->node, &request_list); |
637c4932 VY |
292 | rb_free(request->name); |
293 | rb_free(request); | |
212380e3 AC |
294 | } |
295 | ||
296 | /* | |
297 | * make_request - Create a DNS request record for the server. | |
298 | */ | |
299 | static struct reslist *make_request(struct DNSQuery *query) | |
300 | { | |
eddc2ab6 | 301 | struct reslist *request = rb_malloc(sizeof(struct reslist)); |
212380e3 | 302 | |
e3354945 | 303 | request->sentat = rb_current_time(); |
212380e3 AC |
304 | request->retries = 3; |
305 | request->resend = 1; | |
306 | request->timeout = 4; /* start at 4 and exponential inc. */ | |
307 | request->query = query; | |
308 | request->state = REQ_IDLE; | |
309 | ||
330fc5c1 | 310 | rb_dlinkAdd(request, &request->node, &request_list); |
212380e3 AC |
311 | |
312 | return request; | |
313 | } | |
314 | ||
315 | /* | |
316 | * delete_resolver_queries - cleanup outstanding queries | |
317 | * for which there no longer exist clients or conf lines. | |
318 | */ | |
319 | void delete_resolver_queries(const struct DNSQuery *query) | |
320 | { | |
330fc5c1 | 321 | rb_dlink_node *ptr; |
637c4932 | 322 | rb_dlink_node *next_ptr; |
212380e3 AC |
323 | struct reslist *request; |
324 | ||
637c4932 | 325 | RB_DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head) |
212380e3 AC |
326 | { |
327 | if ((request = ptr->data) != NULL) | |
328 | { | |
329 | if (query == request->query) | |
330 | rem_request(request); | |
331 | } | |
332 | } | |
333 | } | |
334 | ||
335 | /* | |
336 | * send_res_msg - sends msg to all nameservers found in the "_res" structure. | |
337 | * This should reflect /etc/resolv.conf. We will get responses | |
338 | * which arent needed but is easier than checking to see if nameserver | |
339 | * isnt present. Returns number of messages successfully sent to | |
340 | * nameservers or -1 if no successful sends. | |
341 | */ | |
342 | static int send_res_msg(const char *msg, int len, int rcount) | |
343 | { | |
344 | int i; | |
345 | int sent = 0; | |
346 | int max_queries = IRCD_MIN(irc_nscount, rcount); | |
347 | ||
348 | /* RES_PRIMARY option is not implemented | |
349 | * if (res.options & RES_PRIMARY || 0 == max_queries) | |
350 | */ | |
351 | if (max_queries == 0) | |
352 | max_queries = 1; | |
353 | ||
42bda3f3 | 354 | for (i = 0; sent < max_queries && i < irc_nscount; i++) |
212380e3 | 355 | { |
0f6d6f3d | 356 | if (sendto(rb_get_fd(res_fd), msg, len, 0, |
212380e3 | 357 | (struct sockaddr *)&(irc_nsaddr_list[i]), |
0f6d6f3d | 358 | GET_SS_LEN(&irc_nsaddr_list[i])) == len) |
212380e3 AC |
359 | ++sent; |
360 | } | |
361 | ||
362 | return (sent); | |
363 | } | |
364 | ||
365 | /* | |
366 | * find_id - find a dns request id (id is determined by dn_mkquery) | |
367 | */ | |
368 | static struct reslist *find_id(int id) | |
369 | { | |
330fc5c1 | 370 | rb_dlink_node *ptr; |
212380e3 AC |
371 | struct reslist *request; |
372 | ||
5cefa1d6 | 373 | RB_DLINK_FOREACH(ptr, request_list.head) |
212380e3 AC |
374 | { |
375 | request = ptr->data; | |
376 | ||
377 | if (request->id == id) | |
378 | return (request); | |
379 | } | |
380 | ||
381 | return (NULL); | |
382 | } | |
383 | ||
384 | /* | |
385 | * gethost_byname_type - get host address from name | |
386 | * | |
387 | */ | |
388 | void gethost_byname_type(const char *name, struct DNSQuery *query, int type) | |
389 | { | |
390 | assert(name != 0); | |
391 | do_query_name(query, name, NULL, type); | |
392 | } | |
393 | ||
394 | /* | |
395 | * gethost_byaddr - get host name from address | |
396 | */ | |
e7046ee5 | 397 | void gethost_byaddr(const struct rb_sockaddr_storage *addr, struct DNSQuery *query) |
212380e3 AC |
398 | { |
399 | do_query_number(query, addr, NULL); | |
400 | } | |
401 | ||
402 | /* | |
403 | * do_query_name - nameserver lookup name | |
404 | */ | |
405 | static void do_query_name(struct DNSQuery *query, const char *name, struct reslist *request, | |
406 | int type) | |
407 | { | |
408 | char host_name[HOSTLEN + 1]; | |
409 | ||
14e23b0e | 410 | strlcpy(host_name, name, HOSTLEN + 1); |
212380e3 AC |
411 | add_local_domain(host_name, HOSTLEN); |
412 | ||
413 | if (request == NULL) | |
414 | { | |
415 | request = make_request(query); | |
eddc2ab6 | 416 | request->name = (char *)rb_malloc(strlen(host_name) + 1); |
212380e3 AC |
417 | strcpy(request->name, host_name); |
418 | request->state = REQ_A; | |
419 | } | |
420 | ||
421 | strlcpy(request->queryname, host_name, sizeof(request->queryname)); | |
422 | request->type = type; | |
423 | query_name(request); | |
424 | } | |
425 | ||
426 | /* | |
427 | * do_query_number - Use this to do reverse IP# lookups. | |
428 | */ | |
e7046ee5 | 429 | static void do_query_number(struct DNSQuery *query, const struct rb_sockaddr_storage *addr, |
212380e3 AC |
430 | struct reslist *request) |
431 | { | |
432 | const unsigned char *cp; | |
433 | ||
434 | if (request == NULL) | |
435 | { | |
436 | request = make_request(query); | |
e7046ee5 | 437 | memcpy(&request->addr, addr, sizeof(struct rb_sockaddr_storage)); |
eddc2ab6 | 438 | request->name = (char *)rb_malloc(HOSTLEN + 1); |
212380e3 AC |
439 | } |
440 | ||
441 | if (addr->ss_family == AF_INET) | |
442 | { | |
443 | struct sockaddr_in *v4 = (struct sockaddr_in *)addr; | |
444 | cp = (const unsigned char *)&v4->sin_addr.s_addr; | |
445 | ||
b2f0da88 | 446 | rb_sprintf(request->queryname, "%u.%u.%u.%u.in-addr.arpa", (unsigned int)(cp[3]), |
212380e3 AC |
447 | (unsigned int)(cp[2]), (unsigned int)(cp[1]), (unsigned int)(cp[0])); |
448 | } | |
ccda6e3f | 449 | #ifdef RB_IPV6 |
212380e3 AC |
450 | else if (addr->ss_family == AF_INET6) |
451 | { | |
452 | struct sockaddr_in6 *v6 = (struct sockaddr_in6 *)addr; | |
453 | cp = (const unsigned char *)&v6->sin6_addr.s6_addr; | |
454 | ||
455 | (void)sprintf(request->queryname, "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x." | |
456 | "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.ip6.arpa", | |
457 | (unsigned int)(cp[15] & 0xf), (unsigned int)(cp[15] >> 4), | |
458 | (unsigned int)(cp[14] & 0xf), (unsigned int)(cp[14] >> 4), | |
459 | (unsigned int)(cp[13] & 0xf), (unsigned int)(cp[13] >> 4), | |
460 | (unsigned int)(cp[12] & 0xf), (unsigned int)(cp[12] >> 4), | |
461 | (unsigned int)(cp[11] & 0xf), (unsigned int)(cp[11] >> 4), | |
462 | (unsigned int)(cp[10] & 0xf), (unsigned int)(cp[10] >> 4), | |
463 | (unsigned int)(cp[9] & 0xf), (unsigned int)(cp[9] >> 4), | |
464 | (unsigned int)(cp[8] & 0xf), (unsigned int)(cp[8] >> 4), | |
465 | (unsigned int)(cp[7] & 0xf), (unsigned int)(cp[7] >> 4), | |
466 | (unsigned int)(cp[6] & 0xf), (unsigned int)(cp[6] >> 4), | |
467 | (unsigned int)(cp[5] & 0xf), (unsigned int)(cp[5] >> 4), | |
468 | (unsigned int)(cp[4] & 0xf), (unsigned int)(cp[4] >> 4), | |
469 | (unsigned int)(cp[3] & 0xf), (unsigned int)(cp[3] >> 4), | |
470 | (unsigned int)(cp[2] & 0xf), (unsigned int)(cp[2] >> 4), | |
471 | (unsigned int)(cp[1] & 0xf), (unsigned int)(cp[1] >> 4), | |
472 | (unsigned int)(cp[0] & 0xf), (unsigned int)(cp[0] >> 4)); | |
473 | } | |
474 | #endif | |
475 | ||
476 | request->type = T_PTR; | |
477 | query_name(request); | |
478 | } | |
479 | ||
480 | /* | |
481 | * query_name - generate a query based on class, type and name. | |
482 | */ | |
483 | static void query_name(struct reslist *request) | |
484 | { | |
485 | char buf[MAXPACKET]; | |
486 | int request_len = 0; | |
487 | ||
488 | memset(buf, 0, sizeof(buf)); | |
489 | ||
490 | if ((request_len = | |
491 | irc_res_mkquery(request->queryname, C_IN, request->type, (unsigned char *)buf, sizeof(buf))) > 0) | |
492 | { | |
493 | HEADER *header = (HEADER *) buf; | |
494 | #ifndef HAVE_LRAND48 | |
495 | int k = 0; | |
496 | struct timeval tv; | |
497 | #endif | |
498 | /* | |
499 | * generate an unique id | |
500 | * NOTE: we don't have to worry about converting this to and from | |
501 | * network byte order, the nameserver does not interpret this value | |
502 | * and returns it unchanged | |
503 | */ | |
504 | #ifdef HAVE_LRAND48 | |
505 | do | |
506 | { | |
507 | header->id = (header->id + lrand48()) & 0xffff; | |
508 | } while (find_id(header->id)); | |
509 | #else | |
510 | gettimeofday(&tv, NULL); | |
511 | do | |
512 | { | |
513 | header->id = (header->id + k + tv.tv_usec) & 0xffff; | |
514 | k++; | |
515 | } while (find_id(header->id)); | |
516 | #endif /* HAVE_LRAND48 */ | |
517 | request->id = header->id; | |
518 | ++request->sends; | |
519 | ||
520 | request->sent += send_res_msg(buf, request_len, request->sends); | |
521 | } | |
522 | } | |
523 | ||
524 | static void resend_query(struct reslist *request) | |
525 | { | |
526 | if (request->resend == 0) | |
527 | return; | |
528 | ||
529 | switch (request->type) | |
530 | { | |
531 | case T_PTR: | |
532 | do_query_number(NULL, &request->addr, request); | |
533 | break; | |
534 | case T_A: | |
ccda6e3f | 535 | #ifdef RB_IPV6 |
212380e3 AC |
536 | case T_AAAA: |
537 | #endif | |
538 | do_query_name(NULL, request->name, request, request->type); | |
539 | break; | |
540 | default: | |
541 | break; | |
542 | } | |
543 | } | |
544 | ||
545 | /* | |
546 | * check_question - check if the reply really belongs to the | |
547 | * name we queried (to guard against late replies from previous | |
548 | * queries with the same id). | |
549 | */ | |
550 | static int check_question(struct reslist *request, HEADER * header, char *buf, char *eob) | |
551 | { | |
552 | char hostbuf[128]; /* working buffer */ | |
553 | unsigned char *current; /* current position in buf */ | |
554 | int n; /* temp count */ | |
555 | ||
556 | current = (unsigned char *)buf + sizeof(HEADER); | |
557 | if (header->qdcount != 1) | |
558 | return 0; | |
559 | n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current, hostbuf, | |
560 | sizeof(hostbuf)); | |
561 | if (n <= 0) | |
562 | return 0; | |
563 | if (strcasecmp(hostbuf, request->queryname)) | |
564 | return 0; | |
565 | return 1; | |
566 | } | |
567 | ||
568 | /* | |
569 | * proc_answer - process name server reply | |
570 | */ | |
571 | static int proc_answer(struct reslist *request, HEADER * header, char *buf, char *eob) | |
572 | { | |
573 | char hostbuf[HOSTLEN + 100]; /* working buffer */ | |
574 | unsigned char *current; /* current position in buf */ | |
575 | int query_class; /* answer class */ | |
576 | int type; /* answer type */ | |
577 | int n; /* temp count */ | |
578 | int rd_length; | |
579 | struct sockaddr_in *v4; /* conversion */ | |
ccda6e3f | 580 | #ifdef RB_IPV6 |
212380e3 AC |
581 | struct sockaddr_in6 *v6; |
582 | #endif | |
583 | current = (unsigned char *)buf + sizeof(HEADER); | |
584 | ||
585 | for (; header->qdcount > 0; --header->qdcount) | |
586 | { | |
587 | if ((n = irc_dn_skipname(current, (unsigned char *)eob)) < 0) | |
588 | return 0; | |
589 | ||
590 | current += (size_t) n + QFIXEDSZ; | |
591 | } | |
592 | ||
593 | /* | |
594 | * process each answer sent to us blech. | |
595 | */ | |
596 | while (header->ancount > 0 && (char *)current < eob) | |
597 | { | |
598 | header->ancount--; | |
599 | ||
600 | n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current, hostbuf, | |
601 | sizeof(hostbuf)); | |
602 | ||
603 | if (n < 0) | |
604 | { | |
605 | /* | |
606 | * broken message | |
607 | */ | |
608 | return (0); | |
609 | } | |
610 | else if (n == 0) | |
611 | { | |
612 | /* | |
613 | * no more answers left | |
614 | */ | |
615 | return (0); | |
616 | } | |
617 | ||
618 | hostbuf[HOSTLEN] = '\0'; | |
619 | ||
620 | /* With Address arithmetic you have to be very anal | |
621 | * this code was not working on alpha due to that | |
622 | * (spotted by rodder/jailbird/dianora) | |
623 | */ | |
624 | current += (size_t) n; | |
625 | ||
626 | if (!(((char *)current + ANSWER_FIXED_SIZE) < eob)) | |
627 | break; | |
628 | ||
629 | type = irc_ns_get16(current); | |
630 | current += TYPE_SIZE; | |
631 | ||
632 | query_class = irc_ns_get16(current); | |
633 | current += CLASS_SIZE; | |
634 | ||
635 | request->ttl = irc_ns_get32(current); | |
636 | current += TTL_SIZE; | |
637 | ||
638 | rd_length = irc_ns_get16(current); | |
639 | current += RDLENGTH_SIZE; | |
640 | ||
641 | /* | |
642 | * Wait to set request->type until we verify this structure | |
643 | */ | |
644 | switch (type) | |
645 | { | |
646 | case T_A: | |
647 | if (request->type != T_A) | |
648 | return (0); | |
649 | ||
650 | /* | |
651 | * check for invalid rd_length or too many addresses | |
652 | */ | |
653 | if (rd_length != sizeof(struct in_addr)) | |
654 | return (0); | |
655 | v4 = (struct sockaddr_in *)&request->addr; | |
0f6d6f3d | 656 | SET_SS_LEN(&request->addr, sizeof(struct sockaddr_in)); |
212380e3 AC |
657 | v4->sin_family = AF_INET; |
658 | memcpy(&v4->sin_addr, current, sizeof(struct in_addr)); | |
659 | return (1); | |
660 | break; | |
ccda6e3f | 661 | #ifdef RB_IPV6 |
212380e3 AC |
662 | case T_AAAA: |
663 | if (request->type != T_AAAA) | |
664 | return (0); | |
665 | if (rd_length != sizeof(struct in6_addr)) | |
666 | return (0); | |
0f6d6f3d | 667 | SET_SS_LEN(&request->addr, sizeof(struct sockaddr_in6)); |
212380e3 AC |
668 | v6 = (struct sockaddr_in6 *)&request->addr; |
669 | v6->sin6_family = AF_INET6; | |
670 | memcpy(&v6->sin6_addr, current, sizeof(struct in6_addr)); | |
671 | return (1); | |
672 | break; | |
673 | #endif | |
674 | case T_PTR: | |
675 | if (request->type != T_PTR) | |
676 | return (0); | |
677 | n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current, | |
678 | hostbuf, sizeof(hostbuf)); | |
679 | if (n < 0) | |
680 | return (0); /* broken message */ | |
681 | else if (n == 0) | |
682 | return (0); /* no more answers left */ | |
683 | ||
14e23b0e | 684 | strlcpy(request->name, hostbuf, HOSTLEN + 1); |
212380e3 AC |
685 | |
686 | return (1); | |
687 | break; | |
688 | case T_CNAME: /* first check we already havent started looking | |
689 | into a cname */ | |
690 | if (request->type != T_PTR) | |
691 | return (0); | |
692 | ||
693 | if (request->state == REQ_CNAME) | |
694 | { | |
695 | n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, | |
696 | current, hostbuf, sizeof(hostbuf)); | |
697 | ||
698 | if (n < 0) | |
699 | return (0); | |
700 | return (1); | |
701 | } | |
702 | ||
703 | request->state = REQ_CNAME; | |
704 | current += rd_length; | |
705 | break; | |
706 | ||
707 | default: | |
708 | /* XXX I'd rather just throw away the entire bogus thing | |
709 | * but its possible its just a broken nameserver with still | |
710 | * valid answers. But lets do some rudimentary logging for now... | |
711 | */ | |
712 | ilog(L_MAIN, "irc_res.c bogus type %d", type); | |
713 | break; | |
714 | } | |
715 | } | |
716 | ||
717 | return (1); | |
718 | } | |
719 | ||
720 | /* | |
721 | * res_readreply - read a dns reply from the nameserver and process it. | |
722 | */ | |
0f6d6f3d | 723 | static void res_readreply(rb_fde_t *F, void *data) |
212380e3 AC |
724 | { |
725 | char buf[sizeof(HEADER) + MAXPACKET] | |
726 | /* Sparc and alpha need 16bit-alignment for accessing header->id | |
727 | * (which is uint16_t). Because of the header = (HEADER*) buf; | |
728 | * lateron, this is neeeded. --FaUl | |
729 | */ | |
730 | #if defined(__sparc__) || defined(__alpha__) | |
731 | __attribute__ ((aligned(16))) | |
732 | #endif | |
733 | ; | |
734 | HEADER *header; | |
735 | struct reslist *request = NULL; | |
736 | struct DNSReply *reply = NULL; | |
737 | int rc; | |
738 | int answer_count; | |
e7046ee5 VY |
739 | socklen_t len = sizeof(struct rb_sockaddr_storage); |
740 | struct rb_sockaddr_storage lsin; | |
212380e3 | 741 | |
0f6d6f3d | 742 | rc = recvfrom(rb_get_fd(F), buf, sizeof(buf), 0, (struct sockaddr *)&lsin, &len); |
212380e3 AC |
743 | |
744 | /* Re-schedule a read *after* recvfrom, or we'll be registering | |
745 | * interest where it'll instantly be ready for read :-) -- adrian | |
746 | */ | |
0f6d6f3d | 747 | rb_setselect(F, RB_SELECT_READ, res_readreply, NULL); |
212380e3 AC |
748 | /* Better to cast the sizeof instead of rc */ |
749 | if (rc <= (int)(sizeof(HEADER))) | |
750 | return; | |
751 | ||
752 | /* | |
753 | * convert DNS reply reader from Network byte order to CPU byte order. | |
754 | */ | |
755 | header = (HEADER *) buf; | |
756 | header->ancount = ntohs(header->ancount); | |
757 | header->qdcount = ntohs(header->qdcount); | |
758 | header->nscount = ntohs(header->nscount); | |
759 | header->arcount = ntohs(header->arcount); | |
760 | ||
761 | /* | |
762 | * response for an id which we have already received an answer for | |
763 | * just ignore this response. | |
764 | */ | |
765 | if (0 == (request = find_id(header->id))) | |
766 | return; | |
767 | ||
768 | /* | |
769 | * check against possibly fake replies | |
770 | */ | |
771 | if (!res_ourserver(&lsin)) | |
772 | return; | |
773 | ||
774 | if (!check_question(request, header, buf, buf + rc)) | |
775 | return; | |
776 | ||
777 | if ((header->rcode != NO_ERRORS) || (header->ancount == 0)) | |
778 | { | |
779 | if (NXDOMAIN == header->rcode) | |
780 | { | |
781 | (*request->query->callback) (request->query->ptr, NULL); | |
782 | rem_request(request); | |
783 | } | |
784 | else | |
785 | { | |
786 | /* | |
787 | * If a bad error was returned, we stop here and dont send | |
788 | * send any more (no retries granted). | |
789 | */ | |
790 | (*request->query->callback) (request->query->ptr, NULL); | |
791 | rem_request(request); | |
792 | } | |
793 | return; | |
794 | } | |
795 | /* | |
796 | * If this fails there was an error decoding the received packet, | |
797 | * give up. -- jilles | |
798 | */ | |
799 | answer_count = proc_answer(request, header, buf, buf + rc); | |
800 | ||
801 | if (answer_count) | |
802 | { | |
803 | if (request->type == T_PTR) | |
804 | { | |
805 | if (request->name == NULL) | |
806 | { | |
807 | /* | |
808 | * got a PTR response with no name, something bogus is happening | |
809 | * don't bother trying again, the client address doesn't resolve | |
810 | */ | |
811 | (*request->query->callback) (request->query->ptr, reply); | |
812 | rem_request(request); | |
813 | return; | |
814 | } | |
815 | ||
816 | /* | |
817 | * Lookup the 'authoritative' name that we were given for the | |
818 | * ip#. | |
819 | * | |
820 | */ | |
ccda6e3f | 821 | #ifdef RB_IPV6 |
212380e3 AC |
822 | if (request->addr.ss_family == AF_INET6) |
823 | gethost_byname_type(request->name, request->query, T_AAAA); | |
824 | else | |
825 | #endif | |
826 | gethost_byname_type(request->name, request->query, T_A); | |
827 | rem_request(request); | |
828 | } | |
829 | else | |
830 | { | |
831 | /* | |
832 | * got a name and address response, client resolved | |
833 | */ | |
834 | reply = make_dnsreply(request); | |
835 | (*request->query->callback) (request->query->ptr, reply); | |
637c4932 | 836 | rb_free(reply); |
212380e3 AC |
837 | rem_request(request); |
838 | } | |
839 | } | |
840 | else | |
841 | { | |
842 | /* couldn't decode, give up -- jilles */ | |
843 | (*request->query->callback) (request->query->ptr, NULL); | |
844 | rem_request(request); | |
845 | } | |
846 | } | |
847 | ||
848 | static struct DNSReply *make_dnsreply(struct reslist *request) | |
849 | { | |
850 | struct DNSReply *cp; | |
851 | s_assert(request != 0); | |
852 | ||
eddc2ab6 | 853 | cp = (struct DNSReply *)rb_malloc(sizeof(struct DNSReply)); |
212380e3 AC |
854 | |
855 | cp->h_name = request->name; | |
856 | memcpy(&cp->addr, &request->addr, sizeof(cp->addr)); | |
857 | return (cp); | |
858 | } | |
859 | ||
860 | void report_dns_servers(struct Client *source_p) | |
861 | { | |
862 | int i; | |
863 | char ipaddr[128]; | |
864 | ||
865 | for (i = 0; i < irc_nscount; i++) | |
866 | { | |
867 | if (!inetntop_sock((struct sockaddr *)&(irc_nsaddr_list[i]), | |
868 | ipaddr, sizeof ipaddr)) | |
869 | strlcpy(ipaddr, "?", sizeof ipaddr); | |
870 | sendto_one_numeric(source_p, RPL_STATSDEBUG, | |
871 | "A %s", ipaddr); | |
872 | } | |
873 | } |