/[svn]/ircd-hybrid-7.2/src/irc_res.c
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Contents of /ircd-hybrid-7.2/src/irc_res.c

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Revision 998 - (show annotations)
Sun Aug 23 12:43:17 2009 UTC (10 years, 3 months ago) by michael
File MIME type: text/x-chdr
File size: 23097 byte(s)
- change resolver/auth to use balloc memory pool
- ircd.c: init_resolver() has to be called *before* read_conf_files(), otherwise
  recvfrom() aborts with ENOTSOCK in case there are configured connect{} blocks
  with a host that needs to be resolved on the very first configuration read.

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 * $Id$
11 *
12 * July 1999 - Rewrote a bunch of stuff here. Change hostent builder code,
13 * added callbacks and reference counting of returned hostents.
14 * --Bleep (Thomas Helvey <tomh@inxpress.net>)
15 *
16 * This was all needlessly complicated for irc. Simplified. No more hostent
17 * All we really care about is the IP -> hostname mappings. Thats all.
18 *
19 * Apr 28, 2003 --cryogen and Dianora
20 */
21
22 #include "stdinc.h"
23 #include "tools.h"
24 #include "balloc.h"
25 #include "client.h"
26 #include "list.h"
27 #include "common.h"
28 #include "event.h"
29 #include "irc_string.h"
30 #include "sprintf_irc.h"
31 #include "ircd.h"
32 #include "numeric.h"
33 #include "restart.h"
34 #include "rng_mt.h"
35 #include "fdlist.h"
36 #include "fileio.h" /* for fbopen / fbclose / fbputs */
37 #include "s_bsd.h"
38 #include "s_log.h"
39 #include "send.h"
40 #include "memory.h"
41 #include "irc_res.h"
42 #include "irc_reslib.h"
43 #include "irc_getnameinfo.h"
44
45 #if (CHAR_BIT != 8)
46 #error this code needs to be able to address individual octets
47 #endif
48
49 static PF res_readreply;
50
51 #define MAXPACKET 1024 /* rfc sez 512 but we expand names so ... */
52 #define RES_MAXALIASES 35 /* maximum aliases allowed */
53 #define RES_MAXADDRS 35 /* maximum addresses allowed */
54 #define AR_TTL 600 /* TTL in seconds for dns cache entries */
55
56 /* RFC 1104/1105 wasn't very helpful about what these fields
57 * should be named, so for now, we'll just name them this way.
58 * we probably should look at what named calls them or something.
59 */
60 #define TYPE_SIZE (size_t)2
61 #define CLASS_SIZE (size_t)2
62 #define TTL_SIZE (size_t)4
63 #define RDLENGTH_SIZE (size_t)2
64 #define ANSWER_FIXED_SIZE (TYPE_SIZE + CLASS_SIZE + TTL_SIZE + RDLENGTH_SIZE)
65
66 typedef enum
67 {
68 REQ_IDLE, /* We're doing not much at all */
69 REQ_PTR, /* Looking up a PTR */
70 REQ_A, /* Looking up an A, possibly because AAAA failed */
71 #ifdef IPV6
72 REQ_AAAA, /* Looking up an AAAA */
73 #endif
74 REQ_CNAME /* We got a CNAME in response, we better get a real answer next */
75 } request_state;
76
77 struct reslist
78 {
79 dlink_node node;
80 int id;
81 int sent; /* number of requests sent */
82 request_state state; /* State the resolver machine is in */
83 time_t ttl;
84 char type;
85 char retries; /* retry counter */
86 char sends; /* number of sends (>1 means resent) */
87 char resend; /* send flag. 0 == dont resend */
88 time_t sentat;
89 time_t timeout;
90 struct irc_ssaddr addr;
91 char *name;
92 dns_callback_fnc callback;
93 void *callback_ctx;
94 };
95
96 static fde_t ResolverFileDescriptor;
97 static dlink_list request_list = { NULL, NULL, 0 };
98 static BlockHeap *dns_heap = NULL;
99
100 static void rem_request(struct reslist *request);
101 static struct reslist *make_request(dns_callback_fnc callback, void *);
102 static void do_query_name(dns_callback_fnc callback, void *,
103 const char *, struct reslist *, int);
104 static void do_query_number(dns_callback_fnc callback, void *ctx,
105 const struct irc_ssaddr *,
106 struct reslist *request);
107 static void query_name(const char *name, int query_class, int query_type,
108 struct reslist *request);
109 static int send_res_msg(const char *buf, int len, int count);
110 static void resend_query(struct reslist *request);
111 static int proc_answer(struct reslist *request, HEADER *header, char *, char *);
112 static struct reslist *find_id(int id);
113
114
115 /*
116 * int
117 * res_ourserver(inp)
118 * looks up "inp" in irc_nsaddr_list[]
119 * returns:
120 * 0 : not found
121 * >0 : found
122 * author:
123 * paul vixie, 29may94
124 * revised for ircd, cryogen(stu) may03
125 */
126 static int
127 res_ourserver(const struct irc_ssaddr *inp)
128 {
129 #ifdef IPV6
130 const struct sockaddr_in6 *v6;
131 const struct sockaddr_in6 *v6in = (const struct sockaddr_in6 *)inp;
132 #endif
133 const struct sockaddr_in *v4;
134 const struct sockaddr_in *v4in = (const struct sockaddr_in *)inp;
135 int ns;
136
137 for (ns = 0; ns < irc_nscount; ns++)
138 {
139 const struct irc_ssaddr *srv = &irc_nsaddr_list[ns];
140 #ifdef IPV6
141 v6 = (const struct sockaddr_in6 *)srv;
142 #endif
143 v4 = (const struct sockaddr_in *)srv;
144
145 /* could probably just memcmp(srv, inp, srv.ss_len) here
146 * but we'll air on the side of caution - stu
147 *
148 */
149 switch (srv->ss.ss_family)
150 {
151 #ifdef IPV6
152 case AF_INET6:
153 if (srv->ss.ss_family == inp->ss.ss_family)
154 if (v6->sin6_port == v6in->sin6_port)
155 if ((memcmp(&v6->sin6_addr.s6_addr, &v6in->sin6_addr.s6_addr,
156 sizeof(struct in6_addr)) == 0) ||
157 (memcmp(&v6->sin6_addr.s6_addr, &in6addr_any,
158 sizeof(struct in6_addr)) == 0))
159 return(1);
160 break;
161 #endif
162 case AF_INET:
163 if (srv->ss.ss_family == inp->ss.ss_family)
164 if (v4->sin_port == v4in->sin_port)
165 if ((v4->sin_addr.s_addr == INADDR_ANY) ||
166 (v4->sin_addr.s_addr == v4in->sin_addr.s_addr))
167 return(1);
168 break;
169 default:
170 break;
171 }
172 }
173
174 return(0);
175 }
176
177 /*
178 * timeout_query_list - Remove queries from the list which have been
179 * there too long without being resolved.
180 */
181 static time_t
182 timeout_query_list(time_t now)
183 {
184 dlink_node *ptr;
185 dlink_node *next_ptr;
186 struct reslist *request;
187 time_t next_time = 0;
188 time_t timeout = 0;
189
190 DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head)
191 {
192 request = ptr->data;
193 timeout = request->sentat + request->timeout;
194
195 if (now >= timeout)
196 {
197 if (--request->retries <= 0)
198 {
199 (*request->callback)(request->callback_ctx, NULL, NULL);
200 rem_request(request);
201 continue;
202 }
203 else
204 {
205 request->sentat = now;
206 request->timeout += request->timeout;
207 resend_query(request);
208 }
209 }
210
211 if ((next_time == 0) || timeout < next_time)
212 {
213 next_time = timeout;
214 }
215 }
216
217 return((next_time > now) ? next_time : (now + AR_TTL));
218 }
219
220 /*
221 * timeout_resolver - check request list
222 */
223 static void
224 timeout_resolver(void *notused)
225 {
226 timeout_query_list(CurrentTime);
227 }
228
229 /*
230 * start_resolver - do everything we need to read the resolv.conf file
231 * and initialize the resolver file descriptor if needed
232 */
233 static void
234 start_resolver(void)
235 {
236 irc_res_init();
237
238 if (!ResolverFileDescriptor.flags.open)
239 {
240 if (comm_open(&ResolverFileDescriptor, irc_nsaddr_list[0].ss.ss_family,
241 SOCK_DGRAM, 0, "Resolver socket") == -1)
242 return;
243
244 /* At the moment, the resolver FD data is global .. */
245 comm_setselect(&ResolverFileDescriptor, COMM_SELECT_READ,
246 res_readreply, NULL, 0);
247 eventAdd("timeout_resolver", timeout_resolver, NULL, 1);
248 }
249 }
250
251 /*
252 * init_resolver - initialize resolver and resolver library
253 */
254 void
255 init_resolver(void)
256 {
257 dns_heap = BlockHeapCreate("dns", sizeof(struct reslist), DNS_HEAP_SIZE);
258 memset(&ResolverFileDescriptor, 0, sizeof(fde_t));
259 start_resolver();
260 }
261
262 /*
263 * restart_resolver - reread resolv.conf, reopen socket
264 */
265 void
266 restart_resolver(void)
267 {
268 fd_close(&ResolverFileDescriptor);
269 eventDelete(timeout_resolver, NULL); /* -ddosen */
270 start_resolver();
271 }
272
273 /*
274 * rem_request - remove a request from the list.
275 * This must also free any memory that has been allocated for
276 * temporary storage of DNS results.
277 */
278 static void
279 rem_request(struct reslist *request)
280 {
281 dlinkDelete(&request->node, &request_list);
282
283 MyFree(request->name);
284 BlockHeapFree(dns_heap, request);
285 }
286
287 /*
288 * make_request - Create a DNS request record for the server.
289 */
290 static struct reslist *
291 make_request(dns_callback_fnc callback, void *ctx)
292 {
293 struct reslist *request = BlockHeapAlloc(dns_heap);
294
295 request->sentat = CurrentTime;
296 request->retries = 3;
297 request->resend = 1;
298 request->timeout = 4; /* start at 4 and exponential inc. */
299 request->state = REQ_IDLE;
300 request->callback = callback;
301 request->callback_ctx = ctx;
302
303 dlinkAdd(request, &request->node, &request_list);
304 return request;
305 }
306
307 /*
308 * delete_resolver_queries - cleanup outstanding queries
309 * for which there no longer exist clients or conf lines.
310 */
311 void
312 delete_resolver_queries(const void *vptr)
313 {
314 dlink_node *ptr = NULL, *next_ptr = NULL;
315
316 DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head)
317 {
318 struct reslist *request = ptr->data;
319
320 if (request->callback_ctx == vptr)
321 rem_request(request);
322 }
323 }
324
325 /*
326 * send_res_msg - sends msg to all nameservers found in the "_res" structure.
327 * This should reflect /etc/resolv.conf. We will get responses
328 * which arent needed but is easier than checking to see if nameserver
329 * isnt present. Returns number of messages successfully sent to
330 * nameservers or -1 if no successful sends.
331 */
332 static int
333 send_res_msg(const char *msg, int len, int rcount)
334 {
335 int i;
336 int sent = 0;
337 int max_queries = IRCD_MIN(irc_nscount, rcount);
338
339 /* RES_PRIMARY option is not implemented
340 * if (res.options & RES_PRIMARY || 0 == max_queries)
341 */
342 if (max_queries == 0)
343 max_queries = 1;
344
345 for (i = 0; i < max_queries; i++)
346 {
347 if (sendto(ResolverFileDescriptor.fd, msg, len, 0,
348 (struct sockaddr*)&(irc_nsaddr_list[i]),
349 irc_nsaddr_list[i].ss_len) == len)
350 ++sent;
351 }
352
353 return(sent);
354 }
355
356 /*
357 * find_id - find a dns request id (id is determined by dn_mkquery)
358 */
359 static struct reslist *
360 find_id(int id)
361 {
362 dlink_node *ptr;
363 struct reslist *request;
364
365 DLINK_FOREACH(ptr, request_list.head)
366 {
367 request = ptr->data;
368
369 if (request->id == id)
370 return(request);
371 }
372
373 return(NULL);
374 }
375
376 /*
377 * gethost_byname_type - get host address from name
378 *
379 */
380 void
381 gethost_byname_type(dns_callback_fnc callback, void *ctx, const char *name, int type)
382 {
383 assert(name != 0);
384 do_query_name(callback, ctx, name, NULL, type);
385 }
386
387 /*
388 * gethost_byname - wrapper for _type - send T_AAAA first if IPV6 supported
389 */
390 void
391 gethost_byname(dns_callback_fnc callback, void *ctx, const char *name)
392 {
393 #ifdef IPV6
394 gethost_byname_type(callback, ctx, name, T_AAAA);
395 #else
396 gethost_byname_type(callback, ctx, name, T_A);
397 #endif
398 }
399
400 /*
401 * gethost_byaddr - get host name from address
402 */
403 void
404 gethost_byaddr(dns_callback_fnc callback, void *ctx, const struct irc_ssaddr *addr)
405 {
406 do_query_number(callback, ctx, addr, NULL);
407 }
408
409 /*
410 * do_query_name - nameserver lookup name
411 */
412 static void
413 do_query_name(dns_callback_fnc callback, void *ctx, const char *name,
414 struct reslist *request, int type)
415 {
416 char host_name[HOSTLEN + 1];
417
418 strlcpy(host_name, name, sizeof(host_name));
419
420 if (request == NULL)
421 {
422 request = make_request(callback, ctx);
423 request->name = MyMalloc(strlen(host_name) + 1);
424 request->type = type;
425 strcpy(request->name, host_name);
426 #ifdef IPV6
427 if (type != T_A)
428 request->state = REQ_AAAA;
429 else
430 #endif
431 request->state = REQ_A;
432 }
433
434 request->type = type;
435 query_name(host_name, C_IN, type, request);
436 }
437
438 /*
439 * do_query_number - Use this to do reverse IP# lookups.
440 */
441 static void
442 do_query_number(dns_callback_fnc callback, void *ctx,
443 const struct irc_ssaddr *addr,
444 struct reslist *request)
445 {
446 char ipbuf[128];
447 const unsigned char *cp;
448
449 if (addr->ss.ss_family == AF_INET)
450 {
451 const struct sockaddr_in *v4 = (const struct sockaddr_in *)addr;
452 cp = (const unsigned char*)&v4->sin_addr.s_addr;
453
454 ircsprintf(ipbuf, "%u.%u.%u.%u.in-addr.arpa.",
455 (unsigned int)(cp[3]), (unsigned int)(cp[2]),
456 (unsigned int)(cp[1]), (unsigned int)(cp[0]));
457 }
458 #ifdef IPV6
459 else if (addr->ss.ss_family == AF_INET6)
460 {
461 const struct sockaddr_in6 *v6 = (const struct sockaddr_in6 *)addr;
462 cp = (const unsigned char *)&v6->sin6_addr.s6_addr;
463
464 sprintf(ipbuf, "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x."
465 "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.ip6.arpa.",
466 (unsigned int)(cp[15]&0xf), (unsigned int)(cp[15]>>4),
467 (unsigned int)(cp[14]&0xf), (unsigned int)(cp[14]>>4),
468 (unsigned int)(cp[13]&0xf), (unsigned int)(cp[13]>>4),
469 (unsigned int)(cp[12]&0xf), (unsigned int)(cp[12]>>4),
470 (unsigned int)(cp[11]&0xf), (unsigned int)(cp[11]>>4),
471 (unsigned int)(cp[10]&0xf), (unsigned int)(cp[10]>>4),
472 (unsigned int)(cp[9]&0xf), (unsigned int)(cp[9]>>4),
473 (unsigned int)(cp[8]&0xf), (unsigned int)(cp[8]>>4),
474 (unsigned int)(cp[7]&0xf), (unsigned int)(cp[7]>>4),
475 (unsigned int)(cp[6]&0xf), (unsigned int)(cp[6]>>4),
476 (unsigned int)(cp[5]&0xf), (unsigned int)(cp[5]>>4),
477 (unsigned int)(cp[4]&0xf), (unsigned int)(cp[4]>>4),
478 (unsigned int)(cp[3]&0xf), (unsigned int)(cp[3]>>4),
479 (unsigned int)(cp[2]&0xf), (unsigned int)(cp[2]>>4),
480 (unsigned int)(cp[1]&0xf), (unsigned int)(cp[1]>>4),
481 (unsigned int)(cp[0]&0xf), (unsigned int)(cp[0]>>4));
482 }
483 #endif
484 if (request == NULL)
485 {
486 request = make_request(callback, ctx);
487 request->type = T_PTR;
488 memcpy(&request->addr, addr, sizeof(struct irc_ssaddr));
489 request->name = MyMalloc(HOSTLEN + 1);
490 }
491
492 query_name(ipbuf, C_IN, T_PTR, request);
493 }
494
495 /*
496 * query_name - generate a query based on class, type and name.
497 */
498 static void
499 query_name(const char *name, int query_class, int type,
500 struct reslist *request)
501 {
502 char buf[MAXPACKET];
503 int request_len = 0;
504
505 memset(buf, 0, sizeof(buf));
506
507 if ((request_len = irc_res_mkquery(name, query_class, type,
508 (unsigned char *)buf, sizeof(buf))) > 0)
509 {
510 HEADER *header = (HEADER *)buf;
511
512 /*
513 * generate an unique id
514 * NOTE: we don't have to worry about converting this to and from
515 * network byte order, the nameserver does not interpret this value
516 * and returns it unchanged
517 */
518 do
519 header->id = (header->id + genrand_int32()) & 0xffff;
520 while (find_id(header->id));
521
522 request->id = header->id;
523 ++request->sends;
524
525 request->sent += send_res_msg(buf, request_len, request->sends);
526 }
527 }
528
529 static void
530 resend_query(struct reslist *request)
531 {
532 if (request->resend == 0)
533 return;
534
535 switch (request->type)
536 {
537 case T_PTR:
538 do_query_number(NULL, NULL, &request->addr, request);
539 break;
540 case T_A:
541 do_query_name(NULL, NULL, request->name, request, request->type);
542 break;
543 #ifdef IPV6
544 case T_AAAA:
545 /* didnt work, try A */
546 if (request->state == REQ_AAAA)
547 do_query_name(NULL, NULL, request->name, request, T_A);
548 #endif
549 default:
550 break;
551 }
552 }
553
554 /*
555 * proc_answer - process name server reply
556 */
557 static int
558 proc_answer(struct reslist *request, HEADER* header, char* buf, char* eob)
559 {
560 char hostbuf[HOSTLEN + 100]; /* working buffer */
561 unsigned char *current; /* current position in buf */
562 int query_class; /* answer class */
563 int type; /* answer type */
564 int n; /* temp count */
565 int rd_length;
566 struct sockaddr_in *v4; /* conversion */
567 #ifdef IPV6
568 struct sockaddr_in6 *v6;
569 #endif
570 current = (unsigned char *)buf + sizeof(HEADER);
571
572 for (; header->qdcount > 0; --header->qdcount)
573 {
574 if ((n = irc_dn_skipname(current, (unsigned char *)eob)) < 0)
575 break;
576
577 current += (size_t) n + QFIXEDSZ;
578 }
579
580 /*
581 * process each answer sent to us blech.
582 */
583 while (header->ancount > 0 && (char *)current < eob)
584 {
585 header->ancount--;
586
587 n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current,
588 hostbuf, sizeof(hostbuf));
589
590 if (n < 0)
591 {
592 /*
593 * broken message
594 */
595 return(0);
596 }
597 else if (n == 0)
598 {
599 /*
600 * no more answers left
601 */
602 return(0);
603 }
604
605 hostbuf[HOSTLEN] = '\0';
606
607 /* With Address arithmetic you have to be very anal
608 * this code was not working on alpha due to that
609 * (spotted by rodder/jailbird/dianora)
610 */
611 current += (size_t) n;
612
613 if (!(((char *)current + ANSWER_FIXED_SIZE) < eob))
614 break;
615
616 type = irc_ns_get16(current);
617 current += TYPE_SIZE;
618
619 query_class = irc_ns_get16(current);
620 current += CLASS_SIZE;
621
622 request->ttl = irc_ns_get32(current);
623 current += TTL_SIZE;
624
625 rd_length = irc_ns_get16(current);
626 current += RDLENGTH_SIZE;
627
628 /*
629 * Wait to set request->type until we verify this structure
630 */
631 switch (type)
632 {
633 case T_A:
634 if (request->type != T_A)
635 return(0);
636
637 /*
638 * check for invalid rd_length or too many addresses
639 */
640 if (rd_length != sizeof(struct in_addr))
641 return(0);
642 v4 = (struct sockaddr_in *)&request->addr;
643 request->addr.ss_len = sizeof(struct sockaddr_in);
644 v4->sin_family = AF_INET;
645 memcpy(&v4->sin_addr, current, sizeof(struct in_addr));
646 return(1);
647 break;
648 #ifdef IPV6
649 case T_AAAA:
650 if (request->type != T_AAAA)
651 return(0);
652 if (rd_length != sizeof(struct in6_addr))
653 return(0);
654 request->addr.ss_len = sizeof(struct sockaddr_in6);
655 v6 = (struct sockaddr_in6 *)&request->addr;
656 v6->sin6_family = AF_INET6;
657 memcpy(&v6->sin6_addr, current, sizeof(struct in6_addr));
658 return(1);
659 break;
660 #endif
661 case T_PTR:
662 if (request->type != T_PTR)
663 return(0);
664 n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob,
665 current, hostbuf, sizeof(hostbuf));
666 if (n < 0)
667 return(0); /* broken message */
668 else if (n == 0)
669 return(0); /* no more answers left */
670
671 strlcpy(request->name, hostbuf, HOSTLEN + 1);
672
673 return(1);
674 break;
675 case T_CNAME: /* first check we already havent started looking
676 into a cname */
677 if (request->type != T_PTR)
678 return(0);
679
680 if (request->state == REQ_CNAME)
681 {
682 n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob,
683 current, hostbuf, sizeof(hostbuf));
684
685 if (n < 0)
686 return(0);
687 return(1);
688 }
689
690 request->state = REQ_CNAME;
691 current += rd_length;
692 break;
693
694 default:
695 /* XXX I'd rather just throw away the entire bogus thing
696 * but its possible its just a broken nameserver with still
697 * valid answers. But lets do some rudimentary logging for now...
698 */
699 ilog(L_ERROR, "irc_res.c bogus type %d", type);
700 break;
701 }
702 }
703
704 return(1);
705 }
706
707 /*
708 * res_readreply - read a dns reply from the nameserver and process it.
709 */
710 static void
711 res_readreply(fde_t *fd, void *data)
712 {
713 char buf[sizeof(HEADER) + MAXPACKET]
714 /* Sparc and alpha need 16bit-alignment for accessing header->id
715 * (which is uint16_t). Because of the header = (HEADER*) buf;
716 * lateron, this is neeeded. --FaUl
717 */
718 #if defined(__sparc__) || defined(__alpha__)
719 __attribute__((aligned (16)))
720 #endif
721 ;
722 HEADER *header;
723 struct reslist *request = NULL;
724 int rc;
725 socklen_t len = sizeof(struct irc_ssaddr);
726 struct irc_ssaddr lsin;
727
728 rc = recvfrom(fd->fd, buf, sizeof(buf), 0, (struct sockaddr *)&lsin, &len);
729
730 /* Re-schedule a read *after* recvfrom, or we'll be registering
731 * interest where it'll instantly be ready for read :-) -- adrian
732 */
733 comm_setselect(fd, COMM_SELECT_READ, res_readreply, NULL, 0);
734
735 /* Better to cast the sizeof instead of rc */
736 if (rc <= (int)(sizeof(HEADER)))
737 return;
738
739 /*
740 * convert DNS reply reader from Network byte order to CPU byte order.
741 */
742 header = (HEADER *)buf;
743 header->ancount = ntohs(header->ancount);
744 header->qdcount = ntohs(header->qdcount);
745 header->nscount = ntohs(header->nscount);
746 header->arcount = ntohs(header->arcount);
747
748 /*
749 * check against possibly fake replies
750 */
751 if (!res_ourserver(&lsin))
752 return;
753
754 /*
755 * response for an id which we have already received an answer for
756 * just ignore this response.
757 */
758 if (!(request = find_id(header->id)))
759 return;
760
761 if ((header->rcode != NO_ERRORS) || (header->ancount == 0))
762 {
763 if (header->rcode == SERVFAIL || header->rcode == NXDOMAIN)
764 {
765 /*
766 * If a bad error was returned, stop here and don't
767 * send any more (no retries granted).
768 */
769 (*request->callback)(request->callback_ctx, NULL, NULL);
770 rem_request(request);
771 }
772 #ifdef IPV6
773 else
774 {
775 /*
776 * If we havent already tried this, and we're looking up AAAA, try A
777 * now
778 */
779 if (request->state == REQ_AAAA && request->type == T_AAAA)
780 {
781 request->timeout += 4;
782 resend_query(request);
783 }
784 }
785 #endif
786
787 return;
788 }
789
790 /*
791 * If this fails there was an error decoding the received packet,
792 * try it again and hope it works the next time.
793 */
794 if (proc_answer(request, header, buf, buf + rc))
795 {
796 if (request->type == T_PTR)
797 {
798 if (request->name == NULL)
799 {
800 /*
801 * got a PTR response with no name, something bogus is happening
802 * don't bother trying again, the client address doesn't resolve
803 */
804 (*request->callback)(request->callback_ctx, NULL, NULL);
805 rem_request(request);
806 return;
807 }
808
809 /*
810 * Lookup the 'authoritative' name that we were given for the
811 * ip#.
812 *
813 */
814 #ifdef IPV6
815 if (request->addr.ss.ss_family == AF_INET6)
816 gethost_byname_type(request->callback, request->callback_ctx, request->name, T_AAAA);
817 else
818 #endif
819 gethost_byname_type(request->callback, request->callback_ctx, request->name, T_A);
820 rem_request(request);
821 }
822 else
823 {
824 /*
825 * got a name and address response, client resolved
826 */
827 (*request->callback)(request->callback_ctx, &request->addr, request->name);
828 rem_request(request);
829 }
830 }
831 else if (!request->sent)
832 {
833 /* XXX - we got a response for a query we didn't send with a valid id?
834 * this should never happen, bail here and leave the client unresolved
835 */
836 assert(0);
837
838 /* XXX don't leak it */
839 rem_request(request);
840 }
841 }
842
843 void
844 report_dns_servers(struct Client *source_p)
845 {
846 int i;
847 char ipaddr[HOSTIPLEN + 1];
848
849 for (i = 0; i < irc_nscount; i++)
850 {
851 irc_getnameinfo((struct sockaddr *)&(irc_nsaddr_list[i]),
852 irc_nsaddr_list[i].ss_len, ipaddr,
853 sizeof(ipaddr), NULL, 0, NI_NUMERICHOST);
854 sendto_one(source_p, form_str(RPL_STATSALINE),
855 me.name, source_p->name, ipaddr);
856 }
857 }

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