/[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 169 - (show annotations)
Fri Oct 21 09:37:16 2005 UTC (14 years ago) by michael
File MIME type: text/x-chdr
File size: 24273 byte(s)
- Removed LocalUser.port
- Removed two extra memsets in make_request()

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 "fdlist.h"
34 #include "fileio.h" /* for fbopen / fbclose / fbputs */
35 #include "s_bsd.h"
36 #include "s_log.h"
37 #include "send.h"
38 #include "memory.h"
39 #include "irc_res.h"
40 #include "irc_reslib.h"
41 #include "irc_getnameinfo.h"
42
43 #if (CHAR_BIT != 8)
44 #error this code needs to be able to address individual octets
45 #endif
46
47 static PF res_readreply;
48
49 #define MAXPACKET 1024 /* rfc sez 512 but we expand names so ... */
50 #define RES_MAXALIASES 35 /* maximum aliases allowed */
51 #define RES_MAXADDRS 35 /* maximum addresses allowed */
52 #define AR_TTL 600 /* TTL in seconds for dns cache entries */
53
54 /* RFC 1104/1105 wasn't very helpful about what these fields
55 * should be named, so for now, we'll just name them this way.
56 * we probably should look at what named calls them or something.
57 */
58 #define TYPE_SIZE (size_t)2
59 #define CLASS_SIZE (size_t)2
60 #define TTL_SIZE (size_t)4
61 #define RDLENGTH_SIZE (size_t)2
62 #define ANSWER_FIXED_SIZE (TYPE_SIZE + CLASS_SIZE + TTL_SIZE + RDLENGTH_SIZE)
63
64 typedef enum
65 {
66 REQ_IDLE, /* We're doing not much at all */
67 REQ_PTR, /* Looking up a PTR */
68 REQ_A, /* Looking up an A, possibly because AAAA failed */
69 #ifdef IPV6
70 REQ_AAAA, /* Looking up an AAAA */
71 #endif
72 REQ_CNAME, /* We got a CNAME in response, we better get a real answer next */
73 REQ_INT /* ip6.arpa failed, falling back to ip6.int */
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 #ifdef HAVE_SRAND48
260 srand48(CurrentTime);
261 #endif
262 memset(&ResolverFileDescriptor, 0, sizeof(fde_t));
263 start_resolver();
264 }
265
266 /*
267 * restart_resolver - reread resolv.conf, reopen socket
268 */
269 void
270 restart_resolver(void)
271 {
272 fd_close(&ResolverFileDescriptor);
273 eventDelete(timeout_resolver, NULL); /* -ddosen */
274 start_resolver();
275 }
276
277 /*
278 * add_local_domain - Add the domain to hostname, if it is missing
279 * (as suggested by eps@TOASTER.SFSU.EDU)
280 */
281 void
282 add_local_domain(char *hname, size_t size)
283 {
284 /* try to fix up unqualified names
285 */
286 if (strchr(hname, '.') == NULL)
287 {
288 if (irc_domain[0])
289 {
290 size_t len = strlen(hname);
291
292 if ((strlen(irc_domain) + len + 2) < size)
293 {
294 hname[len++] = '.';
295 strcpy(hname + len, irc_domain);
296 }
297 }
298 }
299 }
300
301 /*
302 * rem_request - remove a request from the list.
303 * This must also free any memory that has been allocated for
304 * temporary storage of DNS results.
305 */
306 static void
307 rem_request(struct reslist *request)
308 {
309 dlinkDelete(&request->node, &request_list);
310 MyFree(request->name);
311 MyFree(request);
312 }
313
314 /*
315 * make_request - Create a DNS request record for the server.
316 */
317 static struct reslist *
318 make_request(struct DNSQuery* query)
319 {
320 struct reslist *request;
321
322 request = (struct reslist *)MyMalloc(sizeof(struct reslist));
323
324 request->sentat = CurrentTime;
325 request->retries = 3;
326 request->resend = 1;
327 request->timeout = 4; /* start at 4 and exponential inc. */
328 request->query = query;
329 request->state = REQ_IDLE;
330
331 dlinkAdd(request, &request->node, &request_list);
332 return(request);
333 }
334
335 /*
336 * delete_resolver_queries - cleanup outstanding queries
337 * for which there no longer exist clients or conf lines.
338 */
339 void
340 delete_resolver_queries(const struct DNSQuery *query)
341 {
342 dlink_node *ptr;
343 dlink_node *next_ptr;
344 struct reslist *request;
345
346 DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head)
347 {
348 if ((request = ptr->data) != NULL)
349 {
350 if (query == request->query)
351 rem_request(request);
352 }
353 }
354 }
355
356 /*
357 * send_res_msg - sends msg to all nameservers found in the "_res" structure.
358 * This should reflect /etc/resolv.conf. We will get responses
359 * which arent needed but is easier than checking to see if nameserver
360 * isnt present. Returns number of messages successfully sent to
361 * nameservers or -1 if no successful sends.
362 */
363 static int
364 send_res_msg(const char *msg, int len, int rcount)
365 {
366 int i;
367 int sent = 0;
368 int max_queries = IRCD_MIN(irc_nscount, rcount);
369
370 /* RES_PRIMARY option is not implemented
371 * if (res.options & RES_PRIMARY || 0 == max_queries)
372 */
373 if (max_queries == 0)
374 max_queries = 1;
375
376 for (i = 0; i < max_queries; i++)
377 {
378 if (sendto(ResolverFileDescriptor.fd, msg, len, 0,
379 (struct sockaddr*)&(irc_nsaddr_list[i]),
380 irc_nsaddr_list[i].ss_len) == len)
381 ++sent;
382 }
383
384 return(sent);
385 }
386
387 /*
388 * find_id - find a dns request id (id is determined by dn_mkquery)
389 */
390 static struct reslist *
391 find_id(int id)
392 {
393 dlink_node *ptr;
394 struct reslist *request;
395
396 DLINK_FOREACH(ptr, request_list.head)
397 {
398 request = ptr->data;
399
400 if (request->id == id)
401 return(request);
402 }
403
404 return(NULL);
405 }
406
407 /*
408 * gethost_byname_type - get host address from name
409 *
410 */
411 void
412 gethost_byname_type(const char *name, struct DNSQuery *query, int type)
413 {
414 assert(name != 0);
415 do_query_name(query, name, NULL, type);
416 }
417
418 /*
419 * gethost_byname - wrapper for _type - send T_AAAA first if IPV6 supported
420 */
421 void
422 gethost_byname(const char *name, struct DNSQuery *query)
423 {
424 #ifdef IPV6
425 gethost_byname_type(name, query, T_AAAA);
426 #else
427 gethost_byname_type(name, query, T_A);
428 #endif
429 }
430
431 /*
432 * gethost_byaddr - get host name from address
433 */
434 void
435 gethost_byaddr(const struct irc_ssaddr *addr, struct DNSQuery *query)
436 {
437 do_query_number(query, addr, NULL);
438 }
439
440 /*
441 * do_query_name - nameserver lookup name
442 */
443 static void
444 do_query_name(struct DNSQuery *query, const char *name,
445 struct reslist *request, int type)
446 {
447 char host_name[HOSTLEN + 1];
448
449 strlcpy(host_name, name, HOSTLEN);
450 add_local_domain(host_name, HOSTLEN);
451
452 if (request == NULL)
453 {
454 request = make_request(query);
455 request->name = (char *)MyMalloc(strlen(host_name) + 1);
456 request->type = type;
457 strcpy(request->name, host_name);
458 #ifdef IPV6
459 if (type == T_A)
460 request->state = REQ_A;
461 else
462 request->state = REQ_AAAA;
463 #else
464 request->state = REQ_A;
465 #endif
466 }
467
468 request->type = type;
469 query_name(host_name, C_IN, type, request);
470 }
471
472 /*
473 * do_query_number - Use this to do reverse IP# lookups.
474 */
475 static void
476 do_query_number(struct DNSQuery *query, const struct irc_ssaddr *addr,
477 struct reslist *request)
478 {
479 char ipbuf[128];
480 const unsigned char *cp;
481 #ifdef IPV6
482 const char *intarpa;
483 #endif
484 if (addr->ss.ss_family == AF_INET)
485 {
486 struct sockaddr_in *v4 = (struct sockaddr_in *)addr;
487 cp = (const unsigned char*)&v4->sin_addr.s_addr;
488
489 ircsprintf(ipbuf, "%u.%u.%u.%u.in-addr.arpa.",
490 (unsigned int)(cp[3]), (unsigned int)(cp[2]),
491 (unsigned int)(cp[1]), (unsigned int)(cp[0]));
492 }
493 #ifdef IPV6
494 else if (addr->ss.ss_family == AF_INET6)
495 {
496 struct sockaddr_in6 *v6 = (struct sockaddr_in6 *)addr;
497 cp = (const unsigned char *)&v6->sin6_addr.s6_addr;
498
499 if (request != NULL && request->state == REQ_INT)
500 intarpa = "int";
501 else
502 intarpa = "arpa";
503
504 (void)sprintf(ipbuf, "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x."
505 "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.ip6.%s.",
506 (unsigned int)(cp[15]&0xf), (unsigned int)(cp[15]>>4),
507 (unsigned int)(cp[14]&0xf), (unsigned int)(cp[14]>>4),
508 (unsigned int)(cp[13]&0xf), (unsigned int)(cp[13]>>4),
509 (unsigned int)(cp[12]&0xf), (unsigned int)(cp[12]>>4),
510 (unsigned int)(cp[11]&0xf), (unsigned int)(cp[11]>>4),
511 (unsigned int)(cp[10]&0xf), (unsigned int)(cp[10]>>4),
512 (unsigned int)(cp[9]&0xf), (unsigned int)(cp[9]>>4),
513 (unsigned int)(cp[8]&0xf), (unsigned int)(cp[8]>>4),
514 (unsigned int)(cp[7]&0xf), (unsigned int)(cp[7]>>4),
515 (unsigned int)(cp[6]&0xf), (unsigned int)(cp[6]>>4),
516 (unsigned int)(cp[5]&0xf), (unsigned int)(cp[5]>>4),
517 (unsigned int)(cp[4]&0xf), (unsigned int)(cp[4]>>4),
518 (unsigned int)(cp[3]&0xf), (unsigned int)(cp[3]>>4),
519 (unsigned int)(cp[2]&0xf), (unsigned int)(cp[2]>>4),
520 (unsigned int)(cp[1]&0xf), (unsigned int)(cp[1]>>4),
521 (unsigned int)(cp[0]&0xf), (unsigned int)(cp[0]>>4), intarpa);
522 }
523 #endif
524 if (request == NULL)
525 {
526 request = make_request(query);
527 request->type = T_PTR;
528 memcpy(&request->addr, addr, sizeof(struct irc_ssaddr));
529 request->name = (char *)MyMalloc(HOSTLEN + 1);
530 }
531
532 query_name(ipbuf, C_IN, T_PTR, request);
533 }
534
535 /*
536 * query_name - generate a query based on class, type and name.
537 */
538 static void
539 query_name(const char *name, int query_class, int type,
540 struct reslist *request)
541 {
542 char buf[MAXPACKET];
543 int request_len = 0;
544
545 memset(buf, 0, sizeof(buf));
546
547 if ((request_len = irc_res_mkquery(name, query_class, type,
548 (unsigned char *)buf, sizeof(buf))) > 0)
549 {
550 HEADER *header = (HEADER *)buf;
551 #ifndef HAVE_LRAND48
552 int k = 0;
553 struct timeval tv;
554 #endif
555 /*
556 * generate an unique id
557 * NOTE: we don't have to worry about converting this to and from
558 * network byte order, the nameserver does not interpret this value
559 * and returns it unchanged
560 */
561 #ifdef HAVE_LRAND48
562 do
563 {
564 header->id = (header->id + lrand48()) & 0xffff;
565 } while (find_id(header->id));
566 #else
567 gettimeofday(&tv, NULL);
568 do
569 {
570 header->id = (header->id + k + tv.tv_usec) & 0xffff;
571 k++;
572 } while (find_id(header->id));
573 #endif /* HAVE_LRAND48 */
574 request->id = header->id;
575 ++request->sends;
576
577 request->sent += send_res_msg(buf, request_len, request->sends);
578 }
579 }
580
581 static void
582 resend_query(struct reslist *request)
583 {
584 if (request->resend == 0)
585 return;
586
587 switch(request->type)
588 {
589 case T_PTR:
590 do_query_number(NULL, &request->addr, request);
591 break;
592 case T_A:
593 do_query_name(NULL, request->name, request, request->type);
594 break;
595 #ifdef IPV6
596 case T_AAAA:
597 /* didnt work, try A */
598 if (request->state == REQ_AAAA)
599 do_query_name(NULL, request->name, request, T_A);
600 #endif
601 default:
602 break;
603 }
604 }
605
606 /*
607 * proc_answer - process name server reply
608 */
609 static int
610 proc_answer(struct reslist *request, HEADER* header, char* buf, char* eob)
611 {
612 char hostbuf[HOSTLEN + 100]; /* working buffer */
613 unsigned char *current; /* current position in buf */
614 int query_class; /* answer class */
615 int type; /* answer type */
616 int n; /* temp count */
617 int rd_length;
618 struct sockaddr_in *v4; /* conversion */
619 #ifdef IPV6
620 struct sockaddr_in6 *v6;
621 #endif
622 current = (unsigned char *)buf + sizeof(HEADER);
623
624 for (; header->qdcount > 0; --header->qdcount)
625 {
626 if ((n = irc_dn_skipname(current, (unsigned char *)eob)) < 0)
627 break;
628
629 current += (size_t) n + QFIXEDSZ;
630 }
631
632 /*
633 * process each answer sent to us blech.
634 */
635 while (header->ancount > 0 && (char *)current < eob)
636 {
637 header->ancount--;
638
639 n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current,
640 hostbuf, sizeof(hostbuf));
641
642 if (n < 0)
643 {
644 /*
645 * broken message
646 */
647 return(0);
648 }
649 else if (n == 0)
650 {
651 /*
652 * no more answers left
653 */
654 return(0);
655 }
656
657 hostbuf[HOSTLEN] = '\0';
658
659 /* With Address arithmetic you have to be very anal
660 * this code was not working on alpha due to that
661 * (spotted by rodder/jailbird/dianora)
662 */
663 current += (size_t) n;
664
665 if (!(((char *)current + ANSWER_FIXED_SIZE) < eob))
666 break;
667
668 type = irc_ns_get16(current);
669 current += TYPE_SIZE;
670
671 query_class = irc_ns_get16(current);
672 current += CLASS_SIZE;
673
674 request->ttl = irc_ns_get32(current);
675 current += TTL_SIZE;
676
677 rd_length = irc_ns_get16(current);
678 current += RDLENGTH_SIZE;
679
680 /*
681 * Wait to set request->type until we verify this structure
682 */
683 switch (type)
684 {
685 case T_A:
686 if (request->type != T_A)
687 return(0);
688
689 /*
690 * check for invalid rd_length or too many addresses
691 */
692 if (rd_length != sizeof(struct in_addr))
693 return(0);
694 v4 = (struct sockaddr_in *)&request->addr;
695 request->addr.ss_len = sizeof(struct sockaddr_in);
696 v4->sin_family = AF_INET;
697 memcpy(&v4->sin_addr, current, sizeof(struct in_addr));
698 return(1);
699 break;
700 #ifdef IPV6
701 case T_AAAA:
702 if (request->type != T_AAAA)
703 return(0);
704 if (rd_length != sizeof(struct in6_addr))
705 return(0);
706 request->addr.ss_len = sizeof(struct sockaddr_in6);
707 v6 = (struct sockaddr_in6 *)&request->addr;
708 v6->sin6_family = AF_INET6;
709 memcpy(&v6->sin6_addr, current, sizeof(struct in6_addr));
710 return(1);
711 break;
712 #endif
713 case T_PTR:
714 if (request->type != T_PTR)
715 return(0);
716 n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob,
717 current, hostbuf, sizeof(hostbuf));
718 if (n < 0)
719 return(0); /* broken message */
720 else if (n == 0)
721 return(0); /* no more answers left */
722
723 strlcpy(request->name, hostbuf, HOSTLEN);
724
725 return(1);
726 break;
727 case T_CNAME: /* first check we already havent started looking
728 into a cname */
729 if (request->type != T_PTR)
730 return(0);
731
732 if (request->state == REQ_CNAME)
733 {
734 n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob,
735 current, hostbuf, sizeof(hostbuf));
736
737 if (n < 0)
738 return(0);
739 return(1);
740 }
741
742 request->state = REQ_CNAME;
743 current += rd_length;
744 break;
745
746 default:
747 /* XXX I'd rather just throw away the entire bogus thing
748 * but its possible its just a broken nameserver with still
749 * valid answers. But lets do some rudimentary logging for now...
750 */
751 ilog(L_ERROR, "irc_res.c bogus type %d", type);
752 break;
753 }
754 }
755
756 return(1);
757 }
758
759 /*
760 * res_readreply - read a dns reply from the nameserver and process it.
761 */
762 static void
763 res_readreply(fde_t *fd, void *data)
764 {
765 char buf[sizeof(HEADER) + MAXPACKET];
766 HEADER *header;
767 struct reslist *request = NULL;
768 struct DNSReply *reply = NULL;
769 int rc;
770 int answer_count;
771 socklen_t len = sizeof(struct irc_ssaddr);
772 struct irc_ssaddr lsin;
773
774 rc = recvfrom(fd->fd, buf, sizeof(buf), 0, (struct sockaddr *)&lsin, &len);
775
776 /* Re-schedule a read *after* recvfrom, or we'll be registering
777 * interest where it'll instantly be ready for read :-) -- adrian
778 */
779 comm_setselect(fd, COMM_SELECT_READ, res_readreply, NULL, 0);
780 /* Better to cast the sizeof instead of rc */
781 if (rc <= (int)(sizeof(HEADER)))
782 return;
783
784 /*
785 * convert DNS reply reader from Network byte order to CPU byte order.
786 */
787 header = (HEADER *)buf;
788 header->ancount = ntohs(header->ancount);
789 header->qdcount = ntohs(header->qdcount);
790 header->nscount = ntohs(header->nscount);
791 header->arcount = ntohs(header->arcount);
792
793 /*
794 * response for an id which we have already received an answer for
795 * just ignore this response.
796 */
797 if (0 == (request = find_id(header->id)))
798 return;
799
800 /*
801 * check against possibly fake replies
802 */
803 if (!res_ourserver(&lsin))
804 return;
805
806 if ((header->rcode != NO_ERRORS) || (header->ancount == 0))
807 {
808 if (SERVFAIL == header->rcode)
809 {
810 /*
811 * If a bad error was returned, we stop here and dont send
812 * send any more (no retries granted).
813 */
814 (*request->query->callback)(request->query->ptr, NULL);
815 rem_request(request);
816 }
817 else
818 {
819 /*
820 * If we havent already tried this, and we're looking up AAAA, try A
821 * now
822 */
823
824 #ifdef IPV6
825 if (request->state == REQ_AAAA && request->type == T_AAAA)
826 {
827 request->timeout += 4;
828 resend_query(request);
829 }
830 else if (request->type == T_PTR && request->state != REQ_INT &&
831 request->addr.ss.ss_family == AF_INET6)
832 {
833 request->state = REQ_INT;
834 request->timeout += 4;
835 request->retries--;
836 resend_query(request);
837 }
838 #endif
839 }
840
841 return;
842 }
843 /*
844 * If this fails there was an error decoding the received packet,
845 * try it again and hope it works the next time.
846 */
847 answer_count = proc_answer(request, header, buf, buf + rc);
848
849 if (answer_count)
850 {
851 if (request->type == T_PTR)
852 {
853 if (request->name == NULL)
854 {
855 /*
856 * got a PTR response with no name, something bogus is happening
857 * don't bother trying again, the client address doesn't resolve
858 */
859 (*request->query->callback)(request->query->ptr, reply);
860 rem_request(request);
861 return;
862 }
863
864 /*
865 * Lookup the 'authoritative' name that we were given for the
866 * ip#.
867 *
868 */
869 #ifdef IPV6
870 if (request->addr.ss.ss_family == AF_INET6)
871 gethost_byname_type(request->name, request->query, T_AAAA);
872 else
873 #endif
874 gethost_byname_type(request->name, request->query, T_A);
875 rem_request(request);
876 }
877 else
878 {
879 /*
880 * got a name and address response, client resolved
881 */
882 reply = make_dnsreply(request);
883 (*request->query->callback)(request->query->ptr, reply);
884 MyFree(reply);
885 rem_request(request);
886 }
887 }
888 else if (!request->sent)
889 {
890 /* XXX - we got a response for a query we didn't send with a valid id?
891 * this should never happen, bail here and leave the client unresolved
892 */
893 assert(0);
894
895 /* XXX don't leak it */
896 rem_request(request);
897 }
898 }
899
900 static struct DNSReply *
901 make_dnsreply(struct reslist *request)
902 {
903 struct DNSReply *cp;
904 assert(request != 0);
905
906 cp = (struct DNSReply *)MyMalloc(sizeof(struct DNSReply));
907
908 cp->h_name = request->name;
909 memcpy(&cp->addr, &request->addr, sizeof(cp->addr));
910 return(cp);
911 }
912
913 void
914 report_dns_servers(struct Client *source_p)
915 {
916 int i;
917 char ipaddr[HOSTIPLEN];
918
919 for (i = 0; i < irc_nscount; i++)
920 {
921 irc_getnameinfo((struct sockaddr *)&(irc_nsaddr_list[i]),
922 irc_nsaddr_list[i].ss_len, ipaddr, HOSTIPLEN, NULL, 0,
923 NI_NUMERICHOST);
924 sendto_one(source_p, form_str(RPL_STATSALINE),
925 me.name, source_p->name, ipaddr);
926 }
927 }

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