/[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 31 - (show annotations)
Sun Oct 2 20:34:05 2005 UTC (14 years, 2 months ago) by knight
Original Path: ircd-hybrid/src/irc_res.c
File MIME type: text/x-chdr
File size: 24420 byte(s)
- Fix svn:keywords

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 memset(request, 0, sizeof(struct reslist));
324
325 request->sentat = CurrentTime;
326 request->retries = 3;
327 request->resend = 1;
328 request->timeout = 4; /* start at 4 and exponential inc. */
329 memset(&request->addr, 0, sizeof(request->addr));
330 request->query = query;
331 request->state = REQ_IDLE;
332
333 dlinkAdd(request, &request->node, &request_list);
334 return(request);
335 }
336
337 /*
338 * delete_resolver_queries - cleanup outstanding queries
339 * for which there no longer exist clients or conf lines.
340 */
341 void
342 delete_resolver_queries(const struct DNSQuery *query)
343 {
344 dlink_node *ptr;
345 dlink_node *next_ptr;
346 struct reslist *request;
347
348 DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head)
349 {
350 if ((request = ptr->data) != NULL)
351 {
352 if (query == request->query)
353 rem_request(request);
354 }
355 }
356 }
357
358 /*
359 * send_res_msg - sends msg to all nameservers found in the "_res" structure.
360 * This should reflect /etc/resolv.conf. We will get responses
361 * which arent needed but is easier than checking to see if nameserver
362 * isnt present. Returns number of messages successfully sent to
363 * nameservers or -1 if no successful sends.
364 */
365 static int
366 send_res_msg(const char *msg, int len, int rcount)
367 {
368 int i;
369 int sent = 0;
370 int max_queries = IRCD_MIN(irc_nscount, rcount);
371
372 /* RES_PRIMARY option is not implemented
373 * if (res.options & RES_PRIMARY || 0 == max_queries)
374 */
375 if (max_queries == 0)
376 max_queries = 1;
377
378 for (i = 0; i < max_queries; i++)
379 {
380 if (sendto(ResolverFileDescriptor.fd, msg, len, 0,
381 (struct sockaddr*)&(irc_nsaddr_list[i]),
382 irc_nsaddr_list[i].ss_len) == len)
383 ++sent;
384 }
385
386 return(sent);
387 }
388
389 /*
390 * find_id - find a dns request id (id is determined by dn_mkquery)
391 */
392 static struct reslist *
393 find_id(int id)
394 {
395 dlink_node *ptr;
396 struct reslist *request;
397
398 DLINK_FOREACH(ptr, request_list.head)
399 {
400 request = ptr->data;
401
402 if (request->id == id)
403 return(request);
404 }
405
406 return(NULL);
407 }
408
409 /*
410 * gethost_byname_type - get host address from name
411 *
412 */
413 void
414 gethost_byname_type(const char *name, struct DNSQuery *query, int type)
415 {
416 assert(name != 0);
417 do_query_name(query, name, NULL, type);
418 }
419
420 /*
421 * gethost_byname - wrapper for _type - send T_AAAA first if IPV6 supported
422 */
423 void
424 gethost_byname(const char *name, struct DNSQuery *query)
425 {
426 #ifdef IPV6
427 gethost_byname_type(name, query, T_AAAA);
428 #else
429 gethost_byname_type(name, query, T_A);
430 #endif
431 }
432
433 /*
434 * gethost_byaddr - get host name from address
435 */
436 void
437 gethost_byaddr(const struct irc_ssaddr *addr, struct DNSQuery *query)
438 {
439 do_query_number(query, addr, NULL);
440 }
441
442 /*
443 * do_query_name - nameserver lookup name
444 */
445 static void
446 do_query_name(struct DNSQuery *query, const char *name,
447 struct reslist *request, int type)
448 {
449 char host_name[HOSTLEN + 1];
450
451 strlcpy(host_name, name, HOSTLEN);
452 add_local_domain(host_name, HOSTLEN);
453
454 if (request == NULL)
455 {
456 request = make_request(query);
457 request->name = (char *)MyMalloc(strlen(host_name) + 1);
458 request->type = type;
459 strcpy(request->name, host_name);
460 #ifdef IPV6
461 if (type == T_A)
462 request->state = REQ_A;
463 else
464 request->state = REQ_AAAA;
465 #else
466 request->state = REQ_A;
467 #endif
468 }
469
470 request->type = type;
471 query_name(host_name, C_IN, type, request);
472 }
473
474 /*
475 * do_query_number - Use this to do reverse IP# lookups.
476 */
477 static void
478 do_query_number(struct DNSQuery *query, const struct irc_ssaddr *addr,
479 struct reslist *request)
480 {
481 char ipbuf[128];
482 const unsigned char *cp;
483 #ifdef IPV6
484 const char *intarpa;
485 #endif
486 if (addr->ss.ss_family == AF_INET)
487 {
488 struct sockaddr_in *v4 = (struct sockaddr_in *)addr;
489 cp = (const unsigned char*)&v4->sin_addr.s_addr;
490
491 ircsprintf(ipbuf, "%u.%u.%u.%u.in-addr.arpa.",
492 (unsigned int)(cp[3]), (unsigned int)(cp[2]),
493 (unsigned int)(cp[1]), (unsigned int)(cp[0]));
494 }
495 #ifdef IPV6
496 else if (addr->ss.ss_family == AF_INET6)
497 {
498 struct sockaddr_in6 *v6 = (struct sockaddr_in6 *)addr;
499 cp = (const unsigned char *)&v6->sin6_addr.s6_addr;
500
501 if (request != NULL && request->state == REQ_INT)
502 intarpa = "int";
503 else
504 intarpa = "arpa";
505
506 (void)sprintf(ipbuf, "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x."
507 "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.ip6.%s.",
508 (unsigned int)(cp[15]&0xf), (unsigned int)(cp[15]>>4),
509 (unsigned int)(cp[14]&0xf), (unsigned int)(cp[14]>>4),
510 (unsigned int)(cp[13]&0xf), (unsigned int)(cp[13]>>4),
511 (unsigned int)(cp[12]&0xf), (unsigned int)(cp[12]>>4),
512 (unsigned int)(cp[11]&0xf), (unsigned int)(cp[11]>>4),
513 (unsigned int)(cp[10]&0xf), (unsigned int)(cp[10]>>4),
514 (unsigned int)(cp[9]&0xf), (unsigned int)(cp[9]>>4),
515 (unsigned int)(cp[8]&0xf), (unsigned int)(cp[8]>>4),
516 (unsigned int)(cp[7]&0xf), (unsigned int)(cp[7]>>4),
517 (unsigned int)(cp[6]&0xf), (unsigned int)(cp[6]>>4),
518 (unsigned int)(cp[5]&0xf), (unsigned int)(cp[5]>>4),
519 (unsigned int)(cp[4]&0xf), (unsigned int)(cp[4]>>4),
520 (unsigned int)(cp[3]&0xf), (unsigned int)(cp[3]>>4),
521 (unsigned int)(cp[2]&0xf), (unsigned int)(cp[2]>>4),
522 (unsigned int)(cp[1]&0xf), (unsigned int)(cp[1]>>4),
523 (unsigned int)(cp[0]&0xf), (unsigned int)(cp[0]>>4), intarpa);
524 }
525 #endif
526 if (request == NULL)
527 {
528 request = make_request(query);
529 request->type = T_PTR;
530 memcpy(&request->addr, addr, sizeof(struct irc_ssaddr));
531 request->name = (char *)MyMalloc(HOSTLEN + 1);
532 }
533
534 query_name(ipbuf, C_IN, T_PTR, request);
535 }
536
537 /*
538 * query_name - generate a query based on class, type and name.
539 */
540 static void
541 query_name(const char *name, int query_class, int type,
542 struct reslist *request)
543 {
544 char buf[MAXPACKET];
545 int request_len = 0;
546
547 memset(buf, 0, sizeof(buf));
548
549 if ((request_len = irc_res_mkquery(name, query_class, type,
550 (unsigned char *)buf, sizeof(buf))) > 0)
551 {
552 HEADER *header = (HEADER *)buf;
553 #ifndef HAVE_LRAND48
554 int k = 0;
555 struct timeval tv;
556 #endif
557 /*
558 * generate an unique id
559 * NOTE: we don't have to worry about converting this to and from
560 * network byte order, the nameserver does not interpret this value
561 * and returns it unchanged
562 */
563 #ifdef HAVE_LRAND48
564 do
565 {
566 header->id = (header->id + lrand48()) & 0xffff;
567 } while (find_id(header->id));
568 #else
569 gettimeofday(&tv, NULL);
570 do
571 {
572 header->id = (header->id + k + tv.tv_usec) & 0xffff;
573 k++;
574 } while (find_id(header->id));
575 #endif /* HAVE_LRAND48 */
576 request->id = header->id;
577 ++request->sends;
578
579 request->sent += send_res_msg(buf, request_len, request->sends);
580 }
581 }
582
583 static void
584 resend_query(struct reslist *request)
585 {
586 if (request->resend == 0)
587 return;
588
589 switch(request->type)
590 {
591 case T_PTR:
592 do_query_number(NULL, &request->addr, request);
593 break;
594 case T_A:
595 do_query_name(NULL, request->name, request, request->type);
596 break;
597 #ifdef IPV6
598 case T_AAAA:
599 /* didnt work, try A */
600 if (request->state == REQ_AAAA)
601 do_query_name(NULL, request->name, request, T_A);
602 #endif
603 default:
604 break;
605 }
606 }
607
608 /*
609 * proc_answer - process name server reply
610 */
611 static int
612 proc_answer(struct reslist *request, HEADER* header, char* buf, char* eob)
613 {
614 char hostbuf[HOSTLEN + 100]; /* working buffer */
615 unsigned char *current; /* current position in buf */
616 int query_class; /* answer class */
617 int type; /* answer type */
618 int n; /* temp count */
619 int rd_length;
620 struct sockaddr_in *v4; /* conversion */
621 #ifdef IPV6
622 struct sockaddr_in6 *v6;
623 #endif
624 current = (unsigned char *)buf + sizeof(HEADER);
625
626 for (; header->qdcount > 0; --header->qdcount)
627 {
628 if ((n = irc_dn_skipname(current, (unsigned char *)eob)) < 0)
629 break;
630
631 current += (size_t) n + QFIXEDSZ;
632 }
633
634 /*
635 * process each answer sent to us blech.
636 */
637 while (header->ancount > 0 && (char *)current < eob)
638 {
639 header->ancount--;
640
641 n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current,
642 hostbuf, sizeof(hostbuf));
643
644 if (n < 0)
645 {
646 /*
647 * broken message
648 */
649 return(0);
650 }
651 else if (n == 0)
652 {
653 /*
654 * no more answers left
655 */
656 return(0);
657 }
658
659 hostbuf[HOSTLEN] = '\0';
660
661 /* With Address arithmetic you have to be very anal
662 * this code was not working on alpha due to that
663 * (spotted by rodder/jailbird/dianora)
664 */
665 current += (size_t) n;
666
667 if (!(((char *)current + ANSWER_FIXED_SIZE) < eob))
668 break;
669
670 type = irc_ns_get16(current);
671 current += TYPE_SIZE;
672
673 query_class = irc_ns_get16(current);
674 current += CLASS_SIZE;
675
676 request->ttl = irc_ns_get32(current);
677 current += TTL_SIZE;
678
679 rd_length = irc_ns_get16(current);
680 current += RDLENGTH_SIZE;
681
682 /*
683 * Wait to set request->type until we verify this structure
684 */
685 switch (type)
686 {
687 case T_A:
688 if (request->type != T_A)
689 return(0);
690
691 /*
692 * check for invalid rd_length or too many addresses
693 */
694 if (rd_length != sizeof(struct in_addr))
695 return(0);
696 v4 = (struct sockaddr_in *)&request->addr;
697 request->addr.ss_len = sizeof(struct sockaddr_in);
698 v4->sin_family = AF_INET;
699 memcpy(&v4->sin_addr, current, sizeof(struct in_addr));
700 return(1);
701 break;
702 #ifdef IPV6
703 case T_AAAA:
704 if (request->type != T_AAAA)
705 return(0);
706 if (rd_length != sizeof(struct in6_addr))
707 return(0);
708 request->addr.ss_len = sizeof(struct sockaddr_in6);
709 v6 = (struct sockaddr_in6 *)&request->addr;
710 v6->sin6_family = AF_INET6;
711 memcpy(&v6->sin6_addr, current, sizeof(struct in6_addr));
712 return(1);
713 break;
714 #endif
715 case T_PTR:
716 if (request->type != T_PTR)
717 return(0);
718 n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob,
719 current, hostbuf, sizeof(hostbuf));
720 if (n < 0)
721 return(0); /* broken message */
722 else if (n == 0)
723 return(0); /* no more answers left */
724
725 strlcpy(request->name, hostbuf, HOSTLEN);
726
727 return(1);
728 break;
729 case T_CNAME: /* first check we already havent started looking
730 into a cname */
731 if (request->type != T_PTR)
732 return(0);
733
734 if (request->state == REQ_CNAME)
735 {
736 n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob,
737 current, hostbuf, sizeof(hostbuf));
738
739 if (n < 0)
740 return(0);
741 return(1);
742 }
743
744 request->state = REQ_CNAME;
745 current += rd_length;
746 break;
747
748 default:
749 /* XXX I'd rather just throw away the entire bogus thing
750 * but its possible its just a broken nameserver with still
751 * valid answers. But lets do some rudimentary logging for now...
752 */
753 ilog(L_ERROR, "irc_res.c bogus type %d", type);
754 break;
755 }
756 }
757
758 return(1);
759 }
760
761 /*
762 * res_readreply - read a dns reply from the nameserver and process it.
763 */
764 static void
765 res_readreply(fde_t *fd, void *data)
766 {
767 char buf[sizeof(HEADER) + MAXPACKET];
768 HEADER *header;
769 struct reslist *request = NULL;
770 struct DNSReply *reply = NULL;
771 int rc;
772 int answer_count;
773 socklen_t len = sizeof(struct irc_ssaddr);
774 struct irc_ssaddr lsin;
775
776 rc = recvfrom(fd->fd, buf, sizeof(buf), 0, (struct sockaddr *)&lsin, &len);
777
778 /* Re-schedule a read *after* recvfrom, or we'll be registering
779 * interest where it'll instantly be ready for read :-) -- adrian
780 */
781 comm_setselect(fd, COMM_SELECT_READ, res_readreply, NULL, 0);
782 /* Better to cast the sizeof instead of rc */
783 if (rc <= (int)(sizeof(HEADER)))
784 return;
785
786 /*
787 * convert DNS reply reader from Network byte order to CPU byte order.
788 */
789 header = (HEADER *)buf;
790 header->ancount = ntohs(header->ancount);
791 header->qdcount = ntohs(header->qdcount);
792 header->nscount = ntohs(header->nscount);
793 header->arcount = ntohs(header->arcount);
794
795 /*
796 * response for an id which we have already received an answer for
797 * just ignore this response.
798 */
799 if (0 == (request = find_id(header->id)))
800 return;
801
802 /*
803 * check against possibly fake replies
804 */
805 if (!res_ourserver(&lsin))
806 return;
807
808 if ((header->rcode != NO_ERRORS) || (header->ancount == 0))
809 {
810 if (SERVFAIL == header->rcode)
811 resend_query(request);
812 else
813 {
814 /*
815 * If we havent already tried this, and we're looking up AAAA, try A
816 * now
817 */
818
819 #ifdef IPV6
820 if (request->state == REQ_AAAA && request->type == T_AAAA)
821 {
822 request->timeout += 4;
823 resend_query(request);
824 }
825 else if (request->type == T_PTR && request->state != REQ_INT &&
826 request->addr.ss.ss_family == AF_INET6)
827 {
828 request->state = REQ_INT;
829 request->timeout += 4;
830 request->retries--;
831 resend_query(request);
832 }
833 else
834 #endif
835 {
836 /*
837 * If a bad error was returned, we stop here and dont send
838 * send any more (no retries granted).
839 */
840 (*request->query->callback)(request->query->ptr, NULL);
841 rem_request(request);
842 }
843 }
844
845 return;
846 }
847 /*
848 * If this fails there was an error decoding the received packet,
849 * try it again and hope it works the next time.
850 */
851 answer_count = proc_answer(request, header, buf, buf + rc);
852
853 if (answer_count)
854 {
855 if (request->type == T_PTR)
856 {
857 if (request->name == NULL)
858 {
859 /*
860 * got a PTR response with no name, something bogus is happening
861 * don't bother trying again, the client address doesn't resolve
862 */
863 (*request->query->callback)(request->query->ptr, reply);
864 rem_request(request);
865 return;
866 }
867
868 /*
869 * Lookup the 'authoritative' name that we were given for the
870 * ip#.
871 *
872 */
873 #ifdef IPV6
874 if (request->addr.ss.ss_family == AF_INET6)
875 gethost_byname_type(request->name, request->query, T_AAAA);
876 else
877 #endif
878 gethost_byname_type(request->name, request->query, T_A);
879 rem_request(request);
880 }
881 else
882 {
883 /*
884 * got a name and address response, client resolved
885 */
886 reply = make_dnsreply(request);
887 (*request->query->callback)(request->query->ptr, reply);
888 MyFree(reply);
889 rem_request(request);
890 }
891 }
892 else if (!request->sent)
893 {
894 /* XXX - we got a response for a query we didn't send with a valid id?
895 * this should never happen, bail here and leave the client unresolved
896 */
897 assert(0);
898
899 /* XXX don't leak it */
900 rem_request(request);
901 }
902 }
903
904 static struct DNSReply *
905 make_dnsreply(struct reslist *request)
906 {
907 struct DNSReply *cp;
908 assert(request != 0);
909
910 cp = (struct DNSReply *)MyMalloc(sizeof(struct DNSReply));
911
912 cp->h_name = request->name;
913 memcpy(&cp->addr, &request->addr, sizeof(cp->addr));
914 return(cp);
915 }
916
917 void
918 report_dns_servers(struct Client *source_p)
919 {
920 int i;
921 char ipaddr[HOSTIPLEN];
922
923 for (i = 0; i < irc_nscount; i++)
924 {
925 irc_getnameinfo((struct sockaddr *)&(irc_nsaddr_list[i]),
926 irc_nsaddr_list[i].ss_len, ipaddr, HOSTIPLEN, NULL, 0,
927 NI_NUMERICHOST);
928 sendto_one(source_p, form_str(RPL_STATSALINE),
929 me.name, source_p->name, ipaddr);
930 }
931 }

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