/[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 986 - (show annotations)
Sat Aug 15 21:12:34 2009 UTC (10 years, 2 months ago) by michael
File MIME type: text/x-chdr
File size: 23739 byte(s)
- irc_res.c: fixed wide-spread off-by-one when copying hostnames

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 "client.h"
25 #include "list.h"
26 #include "common.h"
27 #include "event.h"
28 #include "irc_string.h"
29 #include "sprintf_irc.h"
30 #include "ircd.h"
31 #include "numeric.h"
32 #include "restart.h"
33 #include "rng_mt.h"
34 #include "fdlist.h"
35 #include "fileio.h" /* for fbopen / fbclose / fbputs */
36 #include "s_bsd.h"
37 #include "s_log.h"
38 #include "send.h"
39 #include "memory.h"
40 #include "irc_res.h"
41 #include "irc_reslib.h"
42 #include "irc_getnameinfo.h"
43
44 #if (CHAR_BIT != 8)
45 #error this code needs to be able to address individual octets
46 #endif
47
48 static PF res_readreply;
49
50 #define MAXPACKET 1024 /* rfc sez 512 but we expand names so ... */
51 #define RES_MAXALIASES 35 /* maximum aliases allowed */
52 #define RES_MAXADDRS 35 /* maximum addresses allowed */
53 #define AR_TTL 600 /* TTL in seconds for dns cache entries */
54
55 /* RFC 1104/1105 wasn't very helpful about what these fields
56 * should be named, so for now, we'll just name them this way.
57 * we probably should look at what named calls them or something.
58 */
59 #define TYPE_SIZE (size_t)2
60 #define CLASS_SIZE (size_t)2
61 #define TTL_SIZE (size_t)4
62 #define RDLENGTH_SIZE (size_t)2
63 #define ANSWER_FIXED_SIZE (TYPE_SIZE + CLASS_SIZE + TTL_SIZE + RDLENGTH_SIZE)
64
65 typedef enum
66 {
67 REQ_IDLE, /* We're doing not much at all */
68 REQ_PTR, /* Looking up a PTR */
69 REQ_A, /* Looking up an A, possibly because AAAA failed */
70 #ifdef IPV6
71 REQ_AAAA, /* Looking up an AAAA */
72 #endif
73 REQ_CNAME /* We got a CNAME in response, we better get a real answer next */
74 } request_state;
75
76 struct reslist
77 {
78 dlink_node node;
79 int id;
80 int sent; /* number of requests sent */
81 request_state state; /* State the resolver machine is in */
82 time_t ttl;
83 char type;
84 char retries; /* retry counter */
85 char sends; /* number of sends (>1 means resent) */
86 char resend; /* send flag. 0 == dont resend */
87 time_t sentat;
88 time_t timeout;
89 struct irc_ssaddr addr;
90 char *name;
91 struct DNSQuery *query; /* query callback for this request */
92 };
93
94 static fde_t ResolverFileDescriptor;
95 static dlink_list request_list = { NULL, NULL, 0 };
96
97 static void rem_request(struct reslist *request);
98 static struct reslist *make_request(struct DNSQuery *query);
99 static void do_query_name(struct DNSQuery *query,
100 const char* name, struct reslist *request, int);
101 static void do_query_number(struct DNSQuery *query,
102 const struct irc_ssaddr *,
103 struct reslist *request);
104 static void query_name(const char *name, int query_class, int query_type,
105 struct reslist *request);
106 static int send_res_msg(const char *buf, int len, int count);
107 static void resend_query(struct reslist *request);
108 static int proc_answer(struct reslist *request, HEADER *header, char *, char *);
109 static struct reslist *find_id(int id);
110 static struct DNSReply *make_dnsreply(struct reslist *request);
111
112 extern struct irc_ssaddr irc_nsaddr_list[IRCD_MAXNS];
113 extern int irc_nscount;
114 extern char irc_domain[HOSTLEN+1];
115
116
117 /*
118 * int
119 * res_ourserver(inp)
120 * looks up "inp" in irc_nsaddr_list[]
121 * returns:
122 * 0 : not found
123 * >0 : found
124 * author:
125 * paul vixie, 29may94
126 * revised for ircd, cryogen(stu) may03
127 */
128 static int
129 res_ourserver(const struct irc_ssaddr *inp)
130 {
131 #ifdef IPV6
132 struct sockaddr_in6 *v6;
133 struct sockaddr_in6 *v6in = (struct sockaddr_in6 *)inp;
134 #endif
135 struct sockaddr_in *v4;
136 struct sockaddr_in *v4in = (struct sockaddr_in *)inp;
137 int ns;
138
139 for (ns = 0; ns < irc_nscount; ns++)
140 {
141 const struct irc_ssaddr *srv = &irc_nsaddr_list[ns];
142 #ifdef IPV6
143 v6 = (struct sockaddr_in6 *)srv;
144 #endif
145 v4 = (struct sockaddr_in *)srv;
146
147 /* could probably just memcmp(srv, inp, srv.ss_len) here
148 * but we'll air on the side of caution - stu
149 *
150 */
151 switch (srv->ss.ss_family)
152 {
153 #ifdef IPV6
154 case AF_INET6:
155 if (srv->ss.ss_family == inp->ss.ss_family)
156 if (v6->sin6_port == v6in->sin6_port)
157 if ((memcmp(&v6->sin6_addr.s6_addr, &v6in->sin6_addr.s6_addr,
158 sizeof(struct in6_addr)) == 0) ||
159 (memcmp(&v6->sin6_addr.s6_addr, &in6addr_any,
160 sizeof(struct in6_addr)) == 0))
161 return(1);
162 break;
163 #endif
164 case AF_INET:
165 if (srv->ss.ss_family == inp->ss.ss_family)
166 if (v4->sin_port == v4in->sin_port)
167 if ((v4->sin_addr.s_addr == INADDR_ANY) ||
168 (v4->sin_addr.s_addr == v4in->sin_addr.s_addr))
169 return(1);
170 break;
171 default:
172 break;
173 }
174 }
175
176 return(0);
177 }
178
179 /*
180 * timeout_query_list - Remove queries from the list which have been
181 * there too long without being resolved.
182 */
183 static time_t
184 timeout_query_list(time_t now)
185 {
186 dlink_node *ptr;
187 dlink_node *next_ptr;
188 struct reslist *request;
189 time_t next_time = 0;
190 time_t timeout = 0;
191
192 DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head)
193 {
194 request = ptr->data;
195 timeout = request->sentat + request->timeout;
196
197 if (now >= timeout)
198 {
199 if (--request->retries <= 0)
200 {
201 (*request->query->callback)(request->query->ptr, NULL);
202 rem_request(request);
203 continue;
204 }
205 else
206 {
207 request->sentat = now;
208 request->timeout += request->timeout;
209 resend_query(request);
210 }
211 }
212
213 if ((next_time == 0) || timeout < next_time)
214 {
215 next_time = timeout;
216 }
217 }
218
219 return((next_time > now) ? next_time : (now + AR_TTL));
220 }
221
222 /*
223 * timeout_resolver - check request list
224 */
225 static void
226 timeout_resolver(void *notused)
227 {
228 timeout_query_list(CurrentTime);
229 }
230
231 /*
232 * start_resolver - do everything we need to read the resolv.conf file
233 * and initialize the resolver file descriptor if needed
234 */
235 static void
236 start_resolver(void)
237 {
238 irc_res_init();
239
240 if (!ResolverFileDescriptor.flags.open)
241 {
242 if (comm_open(&ResolverFileDescriptor, irc_nsaddr_list[0].ss.ss_family,
243 SOCK_DGRAM, 0, "Resolver socket") == -1)
244 return;
245
246 /* At the moment, the resolver FD data is global .. */
247 comm_setselect(&ResolverFileDescriptor, COMM_SELECT_READ,
248 res_readreply, NULL, 0);
249 eventAdd("timeout_resolver", timeout_resolver, NULL, 1);
250 }
251 }
252
253 /*
254 * init_resolver - initialize resolver and resolver library
255 */
256 void
257 init_resolver(void)
258 {
259 memset(&ResolverFileDescriptor, 0, sizeof(fde_t));
260 start_resolver();
261 }
262
263 /*
264 * restart_resolver - reread resolv.conf, reopen socket
265 */
266 void
267 restart_resolver(void)
268 {
269 fd_close(&ResolverFileDescriptor);
270 eventDelete(timeout_resolver, NULL); /* -ddosen */
271 start_resolver();
272 }
273
274 /*
275 * add_local_domain - Add the domain to hostname, if it is missing
276 * (as suggested by eps@TOASTER.SFSU.EDU)
277 */
278 void
279 add_local_domain(char *hname, size_t size)
280 {
281 /* try to fix up unqualified names
282 */
283 if (strchr(hname, '.') == NULL)
284 {
285 if (irc_domain[0])
286 {
287 size_t len = strlen(hname);
288
289 if ((strlen(irc_domain) + len + 2) < size)
290 {
291 hname[len++] = '.';
292 strcpy(hname + len, irc_domain);
293 }
294 }
295 }
296 }
297
298 /*
299 * rem_request - remove a request from the list.
300 * This must also free any memory that has been allocated for
301 * temporary storage of DNS results.
302 */
303 static void
304 rem_request(struct reslist *request)
305 {
306 dlinkDelete(&request->node, &request_list);
307 MyFree(request->name);
308 MyFree(request);
309 }
310
311 /*
312 * make_request - Create a DNS request record for the server.
313 */
314 static struct reslist *
315 make_request(struct DNSQuery* query)
316 {
317 struct reslist *request;
318
319 request = (struct reslist *)MyMalloc(sizeof(struct reslist));
320
321 request->sentat = CurrentTime;
322 request->retries = 3;
323 request->resend = 1;
324 request->timeout = 4; /* start at 4 and exponential inc. */
325 request->query = query;
326 request->state = REQ_IDLE;
327
328 dlinkAdd(request, &request->node, &request_list);
329 return(request);
330 }
331
332 /*
333 * delete_resolver_queries - cleanup outstanding queries
334 * for which there no longer exist clients or conf lines.
335 */
336 void
337 delete_resolver_queries(const struct DNSQuery *query)
338 {
339 dlink_node *ptr;
340 dlink_node *next_ptr;
341 struct reslist *request;
342
343 DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head)
344 {
345 if ((request = ptr->data) != NULL)
346 {
347 if (query == request->query)
348 rem_request(request);
349 }
350 }
351 }
352
353 /*
354 * send_res_msg - sends msg to all nameservers found in the "_res" structure.
355 * This should reflect /etc/resolv.conf. We will get responses
356 * which arent needed but is easier than checking to see if nameserver
357 * isnt present. Returns number of messages successfully sent to
358 * nameservers or -1 if no successful sends.
359 */
360 static int
361 send_res_msg(const char *msg, int len, int rcount)
362 {
363 int i;
364 int sent = 0;
365 int max_queries = IRCD_MIN(irc_nscount, rcount);
366
367 /* RES_PRIMARY option is not implemented
368 * if (res.options & RES_PRIMARY || 0 == max_queries)
369 */
370 if (max_queries == 0)
371 max_queries = 1;
372
373 for (i = 0; i < max_queries; i++)
374 {
375 if (sendto(ResolverFileDescriptor.fd, msg, len, 0,
376 (struct sockaddr*)&(irc_nsaddr_list[i]),
377 irc_nsaddr_list[i].ss_len) == len)
378 ++sent;
379 }
380
381 return(sent);
382 }
383
384 /*
385 * find_id - find a dns request id (id is determined by dn_mkquery)
386 */
387 static struct reslist *
388 find_id(int id)
389 {
390 dlink_node *ptr;
391 struct reslist *request;
392
393 DLINK_FOREACH(ptr, request_list.head)
394 {
395 request = ptr->data;
396
397 if (request->id == id)
398 return(request);
399 }
400
401 return(NULL);
402 }
403
404 /*
405 * gethost_byname_type - get host address from name
406 *
407 */
408 void
409 gethost_byname_type(const char *name, struct DNSQuery *query, int type)
410 {
411 assert(name != 0);
412 do_query_name(query, name, NULL, type);
413 }
414
415 /*
416 * gethost_byname - wrapper for _type - send T_AAAA first if IPV6 supported
417 */
418 void
419 gethost_byname(const char *name, struct DNSQuery *query)
420 {
421 #ifdef IPV6
422 gethost_byname_type(name, query, T_AAAA);
423 #else
424 gethost_byname_type(name, query, T_A);
425 #endif
426 }
427
428 /*
429 * gethost_byaddr - get host name from address
430 */
431 void
432 gethost_byaddr(const struct irc_ssaddr *addr, struct DNSQuery *query)
433 {
434 do_query_number(query, addr, NULL);
435 }
436
437 /*
438 * do_query_name - nameserver lookup name
439 */
440 static void
441 do_query_name(struct DNSQuery *query, const char *name,
442 struct reslist *request, int type)
443 {
444 char host_name[HOSTLEN + 1];
445
446 strlcpy(host_name, name, HOSTLEN + 1);
447 add_local_domain(host_name, HOSTLEN + 1);
448
449 if (request == NULL)
450 {
451 request = make_request(query);
452 request->name = MyMalloc(strlen(host_name) + 1);
453 request->type = type;
454 strcpy(request->name, host_name);
455 #ifdef IPV6
456 if (type != T_A)
457 request->state = REQ_AAAA;
458 else
459 #endif
460 request->state = REQ_A;
461 }
462
463 request->type = type;
464 query_name(host_name, C_IN, type, request);
465 }
466
467 /*
468 * do_query_number - Use this to do reverse IP# lookups.
469 */
470 static void
471 do_query_number(struct DNSQuery *query, const struct irc_ssaddr *addr,
472 struct reslist *request)
473 {
474 char ipbuf[128];
475 const unsigned char *cp;
476
477 if (addr->ss.ss_family == AF_INET)
478 {
479 struct sockaddr_in *v4 = (struct sockaddr_in *)addr;
480 cp = (const unsigned char*)&v4->sin_addr.s_addr;
481
482 ircsprintf(ipbuf, "%u.%u.%u.%u.in-addr.arpa.",
483 (unsigned int)(cp[3]), (unsigned int)(cp[2]),
484 (unsigned int)(cp[1]), (unsigned int)(cp[0]));
485 }
486 #ifdef IPV6
487 else if (addr->ss.ss_family == AF_INET6)
488 {
489 struct sockaddr_in6 *v6 = (struct sockaddr_in6 *)addr;
490 cp = (const unsigned char *)&v6->sin6_addr.s6_addr;
491
492 sprintf(ipbuf, "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x."
493 "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.ip6.arpa.",
494 (unsigned int)(cp[15]&0xf), (unsigned int)(cp[15]>>4),
495 (unsigned int)(cp[14]&0xf), (unsigned int)(cp[14]>>4),
496 (unsigned int)(cp[13]&0xf), (unsigned int)(cp[13]>>4),
497 (unsigned int)(cp[12]&0xf), (unsigned int)(cp[12]>>4),
498 (unsigned int)(cp[11]&0xf), (unsigned int)(cp[11]>>4),
499 (unsigned int)(cp[10]&0xf), (unsigned int)(cp[10]>>4),
500 (unsigned int)(cp[9]&0xf), (unsigned int)(cp[9]>>4),
501 (unsigned int)(cp[8]&0xf), (unsigned int)(cp[8]>>4),
502 (unsigned int)(cp[7]&0xf), (unsigned int)(cp[7]>>4),
503 (unsigned int)(cp[6]&0xf), (unsigned int)(cp[6]>>4),
504 (unsigned int)(cp[5]&0xf), (unsigned int)(cp[5]>>4),
505 (unsigned int)(cp[4]&0xf), (unsigned int)(cp[4]>>4),
506 (unsigned int)(cp[3]&0xf), (unsigned int)(cp[3]>>4),
507 (unsigned int)(cp[2]&0xf), (unsigned int)(cp[2]>>4),
508 (unsigned int)(cp[1]&0xf), (unsigned int)(cp[1]>>4),
509 (unsigned int)(cp[0]&0xf), (unsigned int)(cp[0]>>4));
510 }
511 #endif
512 if (request == NULL)
513 {
514 request = make_request(query);
515 request->type = T_PTR;
516 memcpy(&request->addr, addr, sizeof(struct irc_ssaddr));
517 request->name = MyMalloc(HOSTLEN + 1);
518 }
519
520 query_name(ipbuf, C_IN, T_PTR, request);
521 }
522
523 /*
524 * query_name - generate a query based on class, type and name.
525 */
526 static void
527 query_name(const char *name, int query_class, int type,
528 struct reslist *request)
529 {
530 char buf[MAXPACKET];
531 int request_len = 0;
532
533 memset(buf, 0, sizeof(buf));
534
535 if ((request_len = irc_res_mkquery(name, query_class, type,
536 (unsigned char *)buf, sizeof(buf))) > 0)
537 {
538 HEADER *header = (HEADER *)buf;
539
540 /*
541 * generate an unique id
542 * NOTE: we don't have to worry about converting this to and from
543 * network byte order, the nameserver does not interpret this value
544 * and returns it unchanged
545 */
546 do
547 header->id = (header->id + genrand_int32()) & 0xffff;
548 while (find_id(header->id));
549
550 request->id = header->id;
551 ++request->sends;
552
553 request->sent += send_res_msg(buf, request_len, request->sends);
554 }
555 }
556
557 static void
558 resend_query(struct reslist *request)
559 {
560 if (request->resend == 0)
561 return;
562
563 switch (request->type)
564 {
565 case T_PTR:
566 do_query_number(NULL, &request->addr, request);
567 break;
568 case T_A:
569 do_query_name(NULL, request->name, request, request->type);
570 break;
571 #ifdef IPV6
572 case T_AAAA:
573 /* didnt work, try A */
574 if (request->state == REQ_AAAA)
575 do_query_name(NULL, request->name, request, T_A);
576 #endif
577 default:
578 break;
579 }
580 }
581
582 /*
583 * proc_answer - process name server reply
584 */
585 static int
586 proc_answer(struct reslist *request, HEADER* header, char* buf, char* eob)
587 {
588 char hostbuf[HOSTLEN + 100]; /* working buffer */
589 unsigned char *current; /* current position in buf */
590 int query_class; /* answer class */
591 int type; /* answer type */
592 int n; /* temp count */
593 int rd_length;
594 struct sockaddr_in *v4; /* conversion */
595 #ifdef IPV6
596 struct sockaddr_in6 *v6;
597 #endif
598 current = (unsigned char *)buf + sizeof(HEADER);
599
600 for (; header->qdcount > 0; --header->qdcount)
601 {
602 if ((n = irc_dn_skipname(current, (unsigned char *)eob)) < 0)
603 break;
604
605 current += (size_t) n + QFIXEDSZ;
606 }
607
608 /*
609 * process each answer sent to us blech.
610 */
611 while (header->ancount > 0 && (char *)current < eob)
612 {
613 header->ancount--;
614
615 n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current,
616 hostbuf, sizeof(hostbuf));
617
618 if (n < 0)
619 {
620 /*
621 * broken message
622 */
623 return(0);
624 }
625 else if (n == 0)
626 {
627 /*
628 * no more answers left
629 */
630 return(0);
631 }
632
633 hostbuf[HOSTLEN] = '\0';
634
635 /* With Address arithmetic you have to be very anal
636 * this code was not working on alpha due to that
637 * (spotted by rodder/jailbird/dianora)
638 */
639 current += (size_t) n;
640
641 if (!(((char *)current + ANSWER_FIXED_SIZE) < eob))
642 break;
643
644 type = irc_ns_get16(current);
645 current += TYPE_SIZE;
646
647 query_class = irc_ns_get16(current);
648 current += CLASS_SIZE;
649
650 request->ttl = irc_ns_get32(current);
651 current += TTL_SIZE;
652
653 rd_length = irc_ns_get16(current);
654 current += RDLENGTH_SIZE;
655
656 /*
657 * Wait to set request->type until we verify this structure
658 */
659 switch (type)
660 {
661 case T_A:
662 if (request->type != T_A)
663 return(0);
664
665 /*
666 * check for invalid rd_length or too many addresses
667 */
668 if (rd_length != sizeof(struct in_addr))
669 return(0);
670 v4 = (struct sockaddr_in *)&request->addr;
671 request->addr.ss_len = sizeof(struct sockaddr_in);
672 v4->sin_family = AF_INET;
673 memcpy(&v4->sin_addr, current, sizeof(struct in_addr));
674 return(1);
675 break;
676 #ifdef IPV6
677 case T_AAAA:
678 if (request->type != T_AAAA)
679 return(0);
680 if (rd_length != sizeof(struct in6_addr))
681 return(0);
682 request->addr.ss_len = sizeof(struct sockaddr_in6);
683 v6 = (struct sockaddr_in6 *)&request->addr;
684 v6->sin6_family = AF_INET6;
685 memcpy(&v6->sin6_addr, current, sizeof(struct in6_addr));
686 return(1);
687 break;
688 #endif
689 case T_PTR:
690 if (request->type != T_PTR)
691 return(0);
692 n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob,
693 current, hostbuf, sizeof(hostbuf));
694 if (n < 0)
695 return(0); /* broken message */
696 else if (n == 0)
697 return(0); /* no more answers left */
698
699 strlcpy(request->name, hostbuf, HOSTLEN + 1);
700
701 return(1);
702 break;
703 case T_CNAME: /* first check we already havent started looking
704 into a cname */
705 if (request->type != T_PTR)
706 return(0);
707
708 if (request->state == REQ_CNAME)
709 {
710 n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob,
711 current, hostbuf, sizeof(hostbuf));
712
713 if (n < 0)
714 return(0);
715 return(1);
716 }
717
718 request->state = REQ_CNAME;
719 current += rd_length;
720 break;
721
722 default:
723 /* XXX I'd rather just throw away the entire bogus thing
724 * but its possible its just a broken nameserver with still
725 * valid answers. But lets do some rudimentary logging for now...
726 */
727 ilog(L_ERROR, "irc_res.c bogus type %d", type);
728 break;
729 }
730 }
731
732 return(1);
733 }
734
735 /*
736 * res_readreply - read a dns reply from the nameserver and process it.
737 */
738 static void
739 res_readreply(fde_t *fd, void *data)
740 {
741 char buf[sizeof(HEADER) + MAXPACKET]
742 /* Sparc and alpha need 16bit-alignment for accessing header->id
743 * (which is uint16_t). Because of the header = (HEADER*) buf;
744 * lateron, this is neeeded. --FaUl
745 */
746 #if defined(__sparc__) || defined(__alpha__)
747 __attribute__((aligned (16)))
748 #endif
749 ;
750 HEADER *header;
751 struct reslist *request = NULL;
752 struct DNSReply *reply = NULL;
753 int rc;
754 int answer_count;
755 socklen_t len = sizeof(struct irc_ssaddr);
756 struct irc_ssaddr lsin;
757
758 rc = recvfrom(fd->fd, buf, sizeof(buf), 0, (struct sockaddr *)&lsin, &len);
759
760 /* Re-schedule a read *after* recvfrom, or we'll be registering
761 * interest where it'll instantly be ready for read :-) -- adrian
762 */
763 comm_setselect(fd, COMM_SELECT_READ, res_readreply, NULL, 0);
764
765 /* Better to cast the sizeof instead of rc */
766 if (rc <= (int)(sizeof(HEADER)))
767 return;
768
769 /*
770 * convert DNS reply reader from Network byte order to CPU byte order.
771 */
772 header = (HEADER *)buf;
773 header->ancount = ntohs(header->ancount);
774 header->qdcount = ntohs(header->qdcount);
775 header->nscount = ntohs(header->nscount);
776 header->arcount = ntohs(header->arcount);
777
778 /*
779 * response for an id which we have already received an answer for
780 * just ignore this response.
781 */
782 if (0 == (request = find_id(header->id)))
783 return;
784
785 /*
786 * check against possibly fake replies
787 */
788 if (!res_ourserver(&lsin))
789 return;
790
791 if ((header->rcode != NO_ERRORS) || (header->ancount == 0))
792 {
793 if (header->rcode == SERVFAIL || header->rcode == NXDOMAIN)
794 {
795 /*
796 * If a bad error was returned, stop here and don't
797 * send any more (no retries granted).
798 */
799 (*request->query->callback)(request->query->ptr, NULL);
800 rem_request(request);
801 }
802 #ifdef IPV6
803 else
804 {
805 /*
806 * If we havent already tried this, and we're looking up AAAA, try A
807 * now
808 */
809 if (request->state == REQ_AAAA && request->type == T_AAAA)
810 {
811 request->timeout += 4;
812 resend_query(request);
813 }
814 }
815 #endif
816
817 return;
818 }
819
820 /*
821 * If this fails there was an error decoding the received packet,
822 * try it again and hope it works the next time.
823 */
824 answer_count = proc_answer(request, header, buf, buf + rc);
825
826 if (answer_count)
827 {
828 if (request->type == T_PTR)
829 {
830 if (request->name == NULL)
831 {
832 /*
833 * got a PTR response with no name, something bogus is happening
834 * don't bother trying again, the client address doesn't resolve
835 */
836 (*request->query->callback)(request->query->ptr, reply);
837 rem_request(request);
838 return;
839 }
840
841 /*
842 * Lookup the 'authoritative' name that we were given for the
843 * ip#.
844 *
845 */
846 #ifdef IPV6
847 if (request->addr.ss.ss_family == AF_INET6)
848 gethost_byname_type(request->name, request->query, T_AAAA);
849 else
850 #endif
851 gethost_byname_type(request->name, request->query, T_A);
852 rem_request(request);
853 }
854 else
855 {
856 /*
857 * got a name and address response, client resolved
858 */
859 reply = make_dnsreply(request);
860 (*request->query->callback)(request->query->ptr, reply);
861 MyFree(reply);
862 rem_request(request);
863 }
864 }
865 else if (!request->sent)
866 {
867 /* XXX - we got a response for a query we didn't send with a valid id?
868 * this should never happen, bail here and leave the client unresolved
869 */
870 assert(0);
871
872 /* XXX don't leak it */
873 rem_request(request);
874 }
875 }
876
877 static struct DNSReply *
878 make_dnsreply(struct reslist *request)
879 {
880 struct DNSReply *cp;
881 assert(request != 0);
882
883 cp = (struct DNSReply *)MyMalloc(sizeof(struct DNSReply));
884
885 cp->h_name = request->name;
886 memcpy(&cp->addr, &request->addr, sizeof(cp->addr));
887 return(cp);
888 }
889
890 void
891 report_dns_servers(struct Client *source_p)
892 {
893 int i;
894 char ipaddr[HOSTIPLEN];
895
896 for (i = 0; i < irc_nscount; i++)
897 {
898 irc_getnameinfo((struct sockaddr *)&(irc_nsaddr_list[i]),
899 irc_nsaddr_list[i].ss_len, ipaddr, HOSTIPLEN, NULL, 0,
900 NI_NUMERICHOST);
901 sendto_one(source_p, form_str(RPL_STATSALINE),
902 me.name, source_p->name, ipaddr);
903 }
904 }

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