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Merge branch 'mobile-ra'
[people/ms/dnsmasq.git] / src / forward.c
1 /* dnsmasq is Copyright (c) 2000-2014 Simon Kelley
2
3 This program is free software; you can redistribute it and/or modify
4 it under the terms of the GNU General Public License as published by
5 the Free Software Foundation; version 2 dated June, 1991, or
6 (at your option) version 3 dated 29 June, 2007.
7
8 This program is distributed in the hope that it will be useful,
9 but WITHOUT ANY WARRANTY; without even the implied warranty of
10 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 GNU General Public License for more details.
12
13 You should have received a copy of the GNU General Public License
14 along with this program. If not, see <http://www.gnu.org/licenses/>.
15 */
16
17 #include "dnsmasq.h"
18
19 static struct frec *lookup_frec(unsigned short id, void *hash);
20 static struct frec *lookup_frec_by_sender(unsigned short id,
21 union mysockaddr *addr,
22 void *hash);
23 static unsigned short get_id(void);
24 static void free_frec(struct frec *f);
25 static struct randfd *allocate_rfd(int family);
26
27 #ifdef HAVE_DNSSEC
28 static int tcp_key_recurse(time_t now, int status, struct dns_header *header, size_t n,
29 int class, char *name, char *keyname, struct server *server, int *keycount);
30 static int do_check_sign(time_t now, struct dns_header *header, size_t plen, char *name, char *keyname, int class);
31 static int send_check_sign(time_t now, struct dns_header *header, size_t plen, char *name, char *keyname);
32 #endif
33
34
35 /* Send a UDP packet with its source address set as "source"
36 unless nowild is true, when we just send it with the kernel default */
37 int send_from(int fd, int nowild, char *packet, size_t len,
38 union mysockaddr *to, struct all_addr *source,
39 unsigned int iface)
40 {
41 struct msghdr msg;
42 struct iovec iov[1];
43 union {
44 struct cmsghdr align; /* this ensures alignment */
45 #if defined(HAVE_LINUX_NETWORK)
46 char control[CMSG_SPACE(sizeof(struct in_pktinfo))];
47 #elif defined(IP_SENDSRCADDR)
48 char control[CMSG_SPACE(sizeof(struct in_addr))];
49 #endif
50 #ifdef HAVE_IPV6
51 char control6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
52 #endif
53 } control_u;
54
55 iov[0].iov_base = packet;
56 iov[0].iov_len = len;
57
58 msg.msg_control = NULL;
59 msg.msg_controllen = 0;
60 msg.msg_flags = 0;
61 msg.msg_name = to;
62 msg.msg_namelen = sa_len(to);
63 msg.msg_iov = iov;
64 msg.msg_iovlen = 1;
65
66 if (!nowild)
67 {
68 struct cmsghdr *cmptr;
69 msg.msg_control = &control_u;
70 msg.msg_controllen = sizeof(control_u);
71 cmptr = CMSG_FIRSTHDR(&msg);
72
73 if (to->sa.sa_family == AF_INET)
74 {
75 #if defined(HAVE_LINUX_NETWORK)
76 struct in_pktinfo p;
77 p.ipi_ifindex = 0;
78 p.ipi_spec_dst = source->addr.addr4;
79 memcpy(CMSG_DATA(cmptr), &p, sizeof(p));
80 msg.msg_controllen = cmptr->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
81 cmptr->cmsg_level = IPPROTO_IP;
82 cmptr->cmsg_type = IP_PKTINFO;
83 #elif defined(IP_SENDSRCADDR)
84 memcpy(CMSG_DATA(cmptr), &(source->addr.addr4), sizeof(source->addr.addr4));
85 msg.msg_controllen = cmptr->cmsg_len = CMSG_LEN(sizeof(struct in_addr));
86 cmptr->cmsg_level = IPPROTO_IP;
87 cmptr->cmsg_type = IP_SENDSRCADDR;
88 #endif
89 }
90 else
91 #ifdef HAVE_IPV6
92 {
93 struct in6_pktinfo p;
94 p.ipi6_ifindex = iface; /* Need iface for IPv6 to handle link-local addrs */
95 p.ipi6_addr = source->addr.addr6;
96 memcpy(CMSG_DATA(cmptr), &p, sizeof(p));
97 msg.msg_controllen = cmptr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
98 cmptr->cmsg_type = daemon->v6pktinfo;
99 cmptr->cmsg_level = IPPROTO_IPV6;
100 }
101 #else
102 (void)iface; /* eliminate warning */
103 #endif
104 }
105
106 while (sendmsg(fd, &msg, 0) == -1)
107 {
108 if (retry_send())
109 continue;
110
111 /* If interface is still in DAD, EINVAL results - ignore that. */
112 if (errno == EINVAL)
113 break;
114
115 my_syslog(LOG_ERR, _("failed to send packet: %s"), strerror(errno));
116 return 0;
117 }
118
119 return 1;
120 }
121
122 static unsigned int search_servers(time_t now, struct all_addr **addrpp,
123 unsigned int qtype, char *qdomain, int *type, char **domain, int *norebind)
124
125 {
126 /* If the query ends in the domain in one of our servers, set
127 domain to point to that name. We find the largest match to allow both
128 domain.org and sub.domain.org to exist. */
129
130 unsigned int namelen = strlen(qdomain);
131 unsigned int matchlen = 0;
132 struct server *serv;
133 unsigned int flags = 0;
134
135 for (serv = daemon->servers; serv; serv=serv->next)
136 /* domain matches take priority over NODOTS matches */
137 if ((serv->flags & SERV_FOR_NODOTS) && *type != SERV_HAS_DOMAIN && !strchr(qdomain, '.') && namelen != 0)
138 {
139 unsigned int sflag = serv->addr.sa.sa_family == AF_INET ? F_IPV4 : F_IPV6;
140 *type = SERV_FOR_NODOTS;
141 if (serv->flags & SERV_NO_ADDR)
142 flags = F_NXDOMAIN;
143 else if (serv->flags & SERV_LITERAL_ADDRESS)
144 {
145 if (sflag & qtype)
146 {
147 flags = sflag;
148 if (serv->addr.sa.sa_family == AF_INET)
149 *addrpp = (struct all_addr *)&serv->addr.in.sin_addr;
150 #ifdef HAVE_IPV6
151 else
152 *addrpp = (struct all_addr *)&serv->addr.in6.sin6_addr;
153 #endif
154 }
155 else if (!flags || (flags & F_NXDOMAIN))
156 flags = F_NOERR;
157 }
158 }
159 else if (serv->flags & SERV_HAS_DOMAIN)
160 {
161 unsigned int domainlen = strlen(serv->domain);
162 char *matchstart = qdomain + namelen - domainlen;
163 if (namelen >= domainlen &&
164 hostname_isequal(matchstart, serv->domain) &&
165 (domainlen == 0 || namelen == domainlen || *(matchstart-1) == '.' ))
166 {
167 if (serv->flags & SERV_NO_REBIND)
168 *norebind = 1;
169 else
170 {
171 unsigned int sflag = serv->addr.sa.sa_family == AF_INET ? F_IPV4 : F_IPV6;
172 /* implement priority rules for --address and --server for same domain.
173 --address wins if the address is for the correct AF
174 --server wins otherwise. */
175 if (domainlen != 0 && domainlen == matchlen)
176 {
177 if ((serv->flags & SERV_LITERAL_ADDRESS))
178 {
179 if (!(sflag & qtype) && flags == 0)
180 continue;
181 }
182 else
183 {
184 if (flags & (F_IPV4 | F_IPV6))
185 continue;
186 }
187 }
188
189 if (domainlen >= matchlen)
190 {
191 *type = serv->flags & (SERV_HAS_DOMAIN | SERV_USE_RESOLV | SERV_NO_REBIND);
192 *domain = serv->domain;
193 matchlen = domainlen;
194 if (serv->flags & SERV_NO_ADDR)
195 flags = F_NXDOMAIN;
196 else if (serv->flags & SERV_LITERAL_ADDRESS)
197 {
198 if (sflag & qtype)
199 {
200 flags = sflag;
201 if (serv->addr.sa.sa_family == AF_INET)
202 *addrpp = (struct all_addr *)&serv->addr.in.sin_addr;
203 #ifdef HAVE_IPV6
204 else
205 *addrpp = (struct all_addr *)&serv->addr.in6.sin6_addr;
206 #endif
207 }
208 else if (!flags || (flags & F_NXDOMAIN))
209 flags = F_NOERR;
210 }
211 else
212 flags = 0;
213 }
214 }
215 }
216 }
217
218 if (flags == 0 && !(qtype & F_QUERY) &&
219 option_bool(OPT_NODOTS_LOCAL) && !strchr(qdomain, '.') && namelen != 0)
220 /* don't forward A or AAAA queries for simple names, except the empty name */
221 flags = F_NOERR;
222
223 if (flags == F_NXDOMAIN && check_for_local_domain(qdomain, now))
224 flags = F_NOERR;
225
226 if (flags)
227 {
228 int logflags = 0;
229
230 if (flags == F_NXDOMAIN || flags == F_NOERR)
231 logflags = F_NEG | qtype;
232
233 log_query(logflags | flags | F_CONFIG | F_FORWARD, qdomain, *addrpp, NULL);
234 }
235 else if ((*type) & SERV_USE_RESOLV)
236 {
237 *type = 0; /* use normal servers for this domain */
238 *domain = NULL;
239 }
240 return flags;
241 }
242
243 static int forward_query(int udpfd, union mysockaddr *udpaddr,
244 struct all_addr *dst_addr, unsigned int dst_iface,
245 struct dns_header *header, size_t plen, time_t now,
246 struct frec *forward, int ad_reqd, int do_bit)
247 {
248 char *domain = NULL;
249 int type = 0, norebind = 0;
250 struct all_addr *addrp = NULL;
251 unsigned int flags = 0;
252 struct server *start = NULL;
253 #ifdef HAVE_DNSSEC
254 void *hash = hash_questions(header, plen, daemon->namebuff);
255 #else
256 unsigned int crc = questions_crc(header, plen, daemon->namebuff);
257 void *hash = &crc;
258 #endif
259 unsigned int gotname = extract_request(header, plen, daemon->namebuff, NULL);
260
261 (void)do_bit;
262
263 /* may be no servers available. */
264 if (!daemon->servers)
265 forward = NULL;
266 else if (forward || (hash && (forward = lookup_frec_by_sender(ntohs(header->id), udpaddr, hash))))
267 {
268 #ifdef HAVE_DNSSEC
269 /* If we've already got an answer to this query, but we're awaiting keys for validation,
270 there's no point retrying the query, retry the key query instead...... */
271 if (forward->blocking_query)
272 {
273 int fd;
274
275 while (forward->blocking_query)
276 forward = forward->blocking_query;
277
278 blockdata_retrieve(forward->stash, forward->stash_len, (void *)header);
279 plen = forward->stash_len;
280
281 if (forward->sentto->addr.sa.sa_family == AF_INET)
282 log_query(F_DNSSEC | F_IPV4, "retry", (struct all_addr *)&forward->sentto->addr.in.sin_addr, "dnssec");
283 #ifdef HAVE_IPV6
284 else
285 log_query(F_DNSSEC | F_IPV6, "retry", (struct all_addr *)&forward->sentto->addr.in6.sin6_addr, "dnssec");
286 #endif
287
288 if (forward->sentto->sfd)
289 fd = forward->sentto->sfd->fd;
290 else
291 {
292 #ifdef HAVE_IPV6
293 if (forward->sentto->addr.sa.sa_family == AF_INET6)
294 fd = forward->rfd6->fd;
295 else
296 #endif
297 fd = forward->rfd4->fd;
298 }
299
300 while (sendto(fd, (char *)header, plen, 0,
301 &forward->sentto->addr.sa,
302 sa_len(&forward->sentto->addr)) == -1 && retry_send());
303
304 return 1;
305 }
306 #endif
307
308 /* retry on existing query, send to all available servers */
309 domain = forward->sentto->domain;
310 forward->sentto->failed_queries++;
311 if (!option_bool(OPT_ORDER))
312 {
313 forward->forwardall = 1;
314 daemon->last_server = NULL;
315 }
316 type = forward->sentto->flags & SERV_TYPE;
317 if (!(start = forward->sentto->next))
318 start = daemon->servers; /* at end of list, recycle */
319 header->id = htons(forward->new_id);
320 }
321 else
322 {
323 if (gotname)
324 flags = search_servers(now, &addrp, gotname, daemon->namebuff, &type, &domain, &norebind);
325
326 if (!flags && !(forward = get_new_frec(now, NULL, 0)))
327 /* table full - server failure. */
328 flags = F_NEG;
329
330 if (forward)
331 {
332 forward->source = *udpaddr;
333 forward->dest = *dst_addr;
334 forward->iface = dst_iface;
335 forward->orig_id = ntohs(header->id);
336 forward->new_id = get_id();
337 forward->fd = udpfd;
338 memcpy(forward->hash, hash, HASH_SIZE);
339 forward->forwardall = 0;
340 forward->flags = 0;
341 if (norebind)
342 forward->flags |= FREC_NOREBIND;
343 if (header->hb4 & HB4_CD)
344 forward->flags |= FREC_CHECKING_DISABLED;
345 if (ad_reqd)
346 forward->flags |= FREC_AD_QUESTION;
347 #ifdef HAVE_DNSSEC
348 forward->work_counter = DNSSEC_WORK;
349 if (do_bit)
350 forward->flags |= FREC_DO_QUESTION;
351 #endif
352
353 header->id = htons(forward->new_id);
354
355 /* In strict_order mode, always try servers in the order
356 specified in resolv.conf, if a domain is given
357 always try all the available servers,
358 otherwise, use the one last known to work. */
359
360 if (type == 0)
361 {
362 if (option_bool(OPT_ORDER))
363 start = daemon->servers;
364 else if (!(start = daemon->last_server) ||
365 daemon->forwardcount++ > FORWARD_TEST ||
366 difftime(now, daemon->forwardtime) > FORWARD_TIME)
367 {
368 start = daemon->servers;
369 forward->forwardall = 1;
370 daemon->forwardcount = 0;
371 daemon->forwardtime = now;
372 }
373 }
374 else
375 {
376 start = daemon->servers;
377 if (!option_bool(OPT_ORDER))
378 forward->forwardall = 1;
379 }
380 }
381 }
382
383 /* check for send errors here (no route to host)
384 if we fail to send to all nameservers, send back an error
385 packet straight away (helps modem users when offline) */
386
387 if (!flags && forward)
388 {
389 struct server *firstsentto = start;
390 int forwarded = 0;
391
392 if (option_bool(OPT_ADD_MAC))
393 plen = add_mac(header, plen, ((char *) header) + daemon->packet_buff_sz, &forward->source);
394
395 if (option_bool(OPT_CLIENT_SUBNET))
396 {
397 size_t new = add_source_addr(header, plen, ((char *) header) + daemon->packet_buff_sz, &forward->source);
398 if (new != plen)
399 {
400 plen = new;
401 forward->flags |= FREC_HAS_SUBNET;
402 }
403 }
404
405 #ifdef HAVE_DNSSEC
406 if (option_bool(OPT_DNSSEC_VALID))
407 {
408 size_t new_plen = add_do_bit(header, plen, ((char *) header) + daemon->packet_buff_sz);
409
410 /* For debugging, set Checking Disabled, otherwise, have the upstream check too,
411 this allows it to select auth servers when one is returning bad data. */
412 if (option_bool(OPT_DNSSEC_DEBUG))
413 header->hb4 |= HB4_CD;
414
415 if (new_plen != plen)
416 forward->flags |= FREC_ADDED_PHEADER;
417
418 plen = new_plen;
419 }
420 #endif
421
422 while (1)
423 {
424 /* only send to servers dealing with our domain.
425 domain may be NULL, in which case server->domain
426 must be NULL also. */
427
428 if (type == (start->flags & SERV_TYPE) &&
429 (type != SERV_HAS_DOMAIN || hostname_isequal(domain, start->domain)) &&
430 !(start->flags & SERV_LITERAL_ADDRESS))
431 {
432 int fd;
433
434 /* find server socket to use, may need to get random one. */
435 if (start->sfd)
436 fd = start->sfd->fd;
437 else
438 {
439 #ifdef HAVE_IPV6
440 if (start->addr.sa.sa_family == AF_INET6)
441 {
442 if (!forward->rfd6 &&
443 !(forward->rfd6 = allocate_rfd(AF_INET6)))
444 break;
445 daemon->rfd_save = forward->rfd6;
446 fd = forward->rfd6->fd;
447 }
448 else
449 #endif
450 {
451 if (!forward->rfd4 &&
452 !(forward->rfd4 = allocate_rfd(AF_INET)))
453 break;
454 daemon->rfd_save = forward->rfd4;
455 fd = forward->rfd4->fd;
456 }
457
458 #ifdef HAVE_CONNTRACK
459 /* Copy connection mark of incoming query to outgoing connection. */
460 if (option_bool(OPT_CONNTRACK))
461 {
462 unsigned int mark;
463 if (get_incoming_mark(&forward->source, &forward->dest, 0, &mark))
464 setsockopt(fd, SOL_SOCKET, SO_MARK, &mark, sizeof(unsigned int));
465 }
466 #endif
467 }
468
469 if (sendto(fd, (char *)header, plen, 0,
470 &start->addr.sa,
471 sa_len(&start->addr)) == -1)
472 {
473 if (retry_send())
474 continue;
475 }
476 else
477 {
478 /* Keep info in case we want to re-send this packet */
479 daemon->srv_save = start;
480 daemon->packet_len = plen;
481
482 if (!gotname)
483 strcpy(daemon->namebuff, "query");
484 if (start->addr.sa.sa_family == AF_INET)
485 log_query(F_SERVER | F_IPV4 | F_FORWARD, daemon->namebuff,
486 (struct all_addr *)&start->addr.in.sin_addr, NULL);
487 #ifdef HAVE_IPV6
488 else
489 log_query(F_SERVER | F_IPV6 | F_FORWARD, daemon->namebuff,
490 (struct all_addr *)&start->addr.in6.sin6_addr, NULL);
491 #endif
492 start->queries++;
493 forwarded = 1;
494 forward->sentto = start;
495 if (!forward->forwardall)
496 break;
497 forward->forwardall++;
498 }
499 }
500
501 if (!(start = start->next))
502 start = daemon->servers;
503
504 if (start == firstsentto)
505 break;
506 }
507
508 if (forwarded)
509 return 1;
510
511 /* could not send on, prepare to return */
512 header->id = htons(forward->orig_id);
513 free_frec(forward); /* cancel */
514 }
515
516 /* could not send on, return empty answer or address if known for whole domain */
517 if (udpfd != -1)
518 {
519 plen = setup_reply(header, plen, addrp, flags, daemon->local_ttl);
520 send_from(udpfd, option_bool(OPT_NOWILD) || option_bool(OPT_CLEVERBIND), (char *)header, plen, udpaddr, dst_addr, dst_iface);
521 }
522
523 return 0;
524 }
525
526 static size_t process_reply(struct dns_header *header, time_t now, struct server *server, size_t n, int check_rebind,
527 int no_cache, int cache_secure, int ad_reqd, int do_bit, int added_pheader, int check_subnet, union mysockaddr *query_source)
528 {
529 unsigned char *pheader, *sizep;
530 char **sets = 0;
531 int munged = 0, is_sign;
532 size_t plen;
533
534 (void)ad_reqd;
535 (void) do_bit;
536
537 #ifdef HAVE_IPSET
538 if (daemon->ipsets && extract_request(header, n, daemon->namebuff, NULL))
539 {
540 /* Similar algorithm to search_servers. */
541 struct ipsets *ipset_pos;
542 unsigned int namelen = strlen(daemon->namebuff);
543 unsigned int matchlen = 0;
544 for (ipset_pos = daemon->ipsets; ipset_pos; ipset_pos = ipset_pos->next)
545 {
546 unsigned int domainlen = strlen(ipset_pos->domain);
547 char *matchstart = daemon->namebuff + namelen - domainlen;
548 if (namelen >= domainlen && hostname_isequal(matchstart, ipset_pos->domain) &&
549 (domainlen == 0 || namelen == domainlen || *(matchstart - 1) == '.' ) &&
550 domainlen >= matchlen)
551 {
552 matchlen = domainlen;
553 sets = ipset_pos->sets;
554 }
555 }
556 }
557 #endif
558
559 /* If upstream is advertising a larger UDP packet size
560 than we allow, trim it so that we don't get overlarge
561 requests for the client. We can't do this for signed packets. */
562
563 if ((pheader = find_pseudoheader(header, n, &plen, &sizep, &is_sign)))
564 {
565 unsigned short udpsz;
566 unsigned char *psave = sizep;
567
568 GETSHORT(udpsz, sizep);
569
570 if (!is_sign && udpsz > daemon->edns_pktsz)
571 PUTSHORT(daemon->edns_pktsz, psave);
572
573 if (check_subnet && !check_source(header, plen, pheader, query_source))
574 {
575 my_syslog(LOG_WARNING, _("discarding DNS reply: subnet option mismatch"));
576 return 0;
577 }
578
579 if (added_pheader)
580 {
581 pheader = 0;
582 header->arcount = htons(0);
583 }
584 }
585
586 /* RFC 4035 sect 4.6 para 3 */
587 if (!is_sign && !option_bool(OPT_DNSSEC_PROXY))
588 header->hb4 &= ~HB4_AD;
589
590 if (OPCODE(header) != QUERY || (RCODE(header) != NOERROR && RCODE(header) != NXDOMAIN))
591 return resize_packet(header, n, pheader, plen);
592
593 /* Complain loudly if the upstream server is non-recursive. */
594 if (!(header->hb4 & HB4_RA) && RCODE(header) == NOERROR && ntohs(header->ancount) == 0 &&
595 server && !(server->flags & SERV_WARNED_RECURSIVE))
596 {
597 prettyprint_addr(&server->addr, daemon->namebuff);
598 my_syslog(LOG_WARNING, _("nameserver %s refused to do a recursive query"), daemon->namebuff);
599 if (!option_bool(OPT_LOG))
600 server->flags |= SERV_WARNED_RECURSIVE;
601 }
602
603 if (daemon->bogus_addr && RCODE(header) != NXDOMAIN &&
604 check_for_bogus_wildcard(header, n, daemon->namebuff, daemon->bogus_addr, now))
605 {
606 munged = 1;
607 SET_RCODE(header, NXDOMAIN);
608 header->hb3 &= ~HB3_AA;
609 cache_secure = 0;
610 }
611 else
612 {
613 int doctored = 0;
614
615 if (RCODE(header) == NXDOMAIN &&
616 extract_request(header, n, daemon->namebuff, NULL) &&
617 check_for_local_domain(daemon->namebuff, now))
618 {
619 /* if we forwarded a query for a locally known name (because it was for
620 an unknown type) and the answer is NXDOMAIN, convert that to NODATA,
621 since we know that the domain exists, even if upstream doesn't */
622 munged = 1;
623 header->hb3 |= HB3_AA;
624 SET_RCODE(header, NOERROR);
625 cache_secure = 0;
626 }
627
628 if (extract_addresses(header, n, daemon->namebuff, now, sets, is_sign, check_rebind, no_cache, cache_secure, &doctored))
629 {
630 my_syslog(LOG_WARNING, _("possible DNS-rebind attack detected: %s"), daemon->namebuff);
631 munged = 1;
632 cache_secure = 0;
633 }
634
635 if (doctored)
636 cache_secure = 0;
637 }
638
639 #ifdef HAVE_DNSSEC
640 if (no_cache && !(header->hb4 & HB4_CD))
641 {
642 if (!option_bool(OPT_DNSSEC_DEBUG))
643 {
644 /* Bogus reply, turn into SERVFAIL */
645 SET_RCODE(header, SERVFAIL);
646 munged = 1;
647 }
648 }
649
650 if (option_bool(OPT_DNSSEC_VALID))
651 header->hb4 &= ~HB4_AD;
652
653 if (!(header->hb4 & HB4_CD) && ad_reqd && cache_secure)
654 header->hb4 |= HB4_AD;
655
656 /* If the requestor didn't set the DO bit, don't return DNSSEC info. */
657 if (!do_bit)
658 n = filter_rrsigs(header, n);
659 #endif
660
661 /* do this after extract_addresses. Ensure NODATA reply and remove
662 nameserver info. */
663
664 if (munged)
665 {
666 header->ancount = htons(0);
667 header->nscount = htons(0);
668 header->arcount = htons(0);
669 }
670
671 /* the bogus-nxdomain stuff, doctor and NXDOMAIN->NODATA munging can all elide
672 sections of the packet. Find the new length here and put back pseudoheader
673 if it was removed. */
674 return resize_packet(header, n, pheader, plen);
675 }
676
677 /* sets new last_server */
678 void reply_query(int fd, int family, time_t now)
679 {
680 /* packet from peer server, extract data for cache, and send to
681 original requester */
682 struct dns_header *header;
683 union mysockaddr serveraddr;
684 struct frec *forward;
685 socklen_t addrlen = sizeof(serveraddr);
686 ssize_t n = recvfrom(fd, daemon->packet, daemon->packet_buff_sz, 0, &serveraddr.sa, &addrlen);
687 size_t nn;
688 struct server *server;
689 void *hash;
690 #ifndef HAVE_DNSSEC
691 unsigned int crc;
692 #endif
693
694 /* packet buffer overwritten */
695 daemon->srv_save = NULL;
696
697 /* Determine the address of the server replying so that we can mark that as good */
698 serveraddr.sa.sa_family = family;
699 #ifdef HAVE_IPV6
700 if (serveraddr.sa.sa_family == AF_INET6)
701 serveraddr.in6.sin6_flowinfo = 0;
702 #endif
703
704 header = (struct dns_header *)daemon->packet;
705
706 if (n < (int)sizeof(struct dns_header) || !(header->hb3 & HB3_QR))
707 return;
708
709 /* spoof check: answer must come from known server, */
710 for (server = daemon->servers; server; server = server->next)
711 if (!(server->flags & (SERV_LITERAL_ADDRESS | SERV_NO_ADDR)) &&
712 sockaddr_isequal(&server->addr, &serveraddr))
713 break;
714
715 if (!server)
716 return;
717
718 #ifdef HAVE_DNSSEC
719 hash = hash_questions(header, n, daemon->namebuff);
720 #else
721 hash = &crc;
722 crc = questions_crc(header, n, daemon->namebuff);
723 #endif
724
725 if (!(forward = lookup_frec(ntohs(header->id), hash)))
726 return;
727
728 if ((RCODE(header) == SERVFAIL || RCODE(header) == REFUSED) &&
729 !option_bool(OPT_ORDER) &&
730 forward->forwardall == 0)
731 /* for broken servers, attempt to send to another one. */
732 {
733 unsigned char *pheader;
734 size_t plen;
735 int is_sign;
736
737 /* recreate query from reply */
738 pheader = find_pseudoheader(header, (size_t)n, &plen, NULL, &is_sign);
739 if (!is_sign)
740 {
741 header->ancount = htons(0);
742 header->nscount = htons(0);
743 header->arcount = htons(0);
744 if ((nn = resize_packet(header, (size_t)n, pheader, plen)))
745 {
746 header->hb3 &= ~(HB3_QR | HB3_TC);
747 forward_query(-1, NULL, NULL, 0, header, nn, now, forward, 0, 0);
748 return;
749 }
750 }
751 }
752
753 server = forward->sentto;
754
755 if ((forward->sentto->flags & SERV_TYPE) == 0)
756 {
757 if (RCODE(header) == REFUSED)
758 server = NULL;
759 else
760 {
761 struct server *last_server;
762
763 /* find good server by address if possible, otherwise assume the last one we sent to */
764 for (last_server = daemon->servers; last_server; last_server = last_server->next)
765 if (!(last_server->flags & (SERV_LITERAL_ADDRESS | SERV_HAS_DOMAIN | SERV_FOR_NODOTS | SERV_NO_ADDR)) &&
766 sockaddr_isequal(&last_server->addr, &serveraddr))
767 {
768 server = last_server;
769 break;
770 }
771 }
772 if (!option_bool(OPT_ALL_SERVERS))
773 daemon->last_server = server;
774 }
775
776 /* If the answer is an error, keep the forward record in place in case
777 we get a good reply from another server. Kill it when we've
778 had replies from all to avoid filling the forwarding table when
779 everything is broken */
780 if (forward->forwardall == 0 || --forward->forwardall == 1 || RCODE(header) != SERVFAIL)
781 {
782 int check_rebind = 0, no_cache_dnssec = 0, cache_secure = 0;
783
784 if (option_bool(OPT_NO_REBIND))
785 check_rebind = !(forward->flags & FREC_NOREBIND);
786
787 /* Don't cache replies where DNSSEC validation was turned off, either
788 the upstream server told us so, or the original query specified it. */
789 if ((header->hb4 & HB4_CD) || (forward->flags & FREC_CHECKING_DISABLED))
790 no_cache_dnssec = 1;
791
792 #ifdef HAVE_DNSSEC
793 if (server && option_bool(OPT_DNSSEC_VALID) && !(forward->flags & FREC_CHECKING_DISABLED))
794 {
795 int status;
796
797 /* We've had a reply already, which we're validating. Ignore this duplicate */
798 if (forward->blocking_query)
799 return;
800
801 if (header->hb3 & HB3_TC)
802 {
803 /* Truncated answer can't be validated.
804 If this is an answer to a DNSSEC-generated query, we still
805 need to get the client to retry over TCP, so return
806 an answer with the TC bit set, even if the actual answer fits.
807 */
808 status = STAT_TRUNCATED;
809 }
810 else if (forward->flags & FREC_DNSKEY_QUERY)
811 status = dnssec_validate_by_ds(now, header, n, daemon->namebuff, daemon->keyname, forward->class);
812 else if (forward->flags & FREC_DS_QUERY)
813 {
814 status = dnssec_validate_ds(now, header, n, daemon->namebuff, daemon->keyname, forward->class);
815 if (status == STAT_NO_DS)
816 status = STAT_INSECURE;
817 }
818 else if (forward->flags & FREC_CHECK_NOSIGN)
819 status = do_check_sign(now, header, n, daemon->namebuff, daemon->keyname, forward->class);
820 else
821 {
822 status = dnssec_validate_reply(now, header, n, daemon->namebuff, daemon->keyname, &forward->class, NULL);
823 if (status == STAT_NO_SIG)
824 {
825 if (option_bool(OPT_DNSSEC_NO_SIGN))
826 status = send_check_sign(now, header, n, daemon->namebuff, daemon->keyname);
827 else
828 status = STAT_INSECURE;
829 }
830 }
831 /* Can't validate, as we're missing key data. Put this
832 answer aside, whilst we get that. */
833 if (status == STAT_NEED_DS || status == STAT_NEED_DS_NEG || status == STAT_NEED_KEY)
834 {
835 struct frec *new, *orig;
836
837 /* Free any saved query */
838 if (forward->stash)
839 blockdata_free(forward->stash);
840
841 /* Now save reply pending receipt of key data */
842 if (!(forward->stash = blockdata_alloc((char *)header, n)))
843 return;
844 forward->stash_len = n;
845
846 anotherkey:
847 /* Find the original query that started it all.... */
848 for (orig = forward; orig->dependent; orig = orig->dependent);
849
850 if (--orig->work_counter == 0 || !(new = get_new_frec(now, NULL, 1)))
851 status = STAT_INSECURE;
852 else
853 {
854 int fd;
855 struct frec *next = new->next;
856 *new = *forward; /* copy everything, then overwrite */
857 new->next = next;
858 new->blocking_query = NULL;
859 new->sentto = server;
860 new->rfd4 = NULL;
861 #ifdef HAVE_IPV6
862 new->rfd6 = NULL;
863 #endif
864 new->flags &= ~(FREC_DNSKEY_QUERY | FREC_DS_QUERY | FREC_CHECK_NOSIGN);
865
866 new->dependent = forward; /* to find query awaiting new one. */
867 forward->blocking_query = new; /* for garbage cleaning */
868 /* validate routines leave name of required record in daemon->keyname */
869 if (status == STAT_NEED_KEY)
870 {
871 new->flags |= FREC_DNSKEY_QUERY;
872 nn = dnssec_generate_query(header, ((char *) header) + daemon->packet_buff_sz,
873 daemon->keyname, forward->class, T_DNSKEY, &server->addr);
874 }
875 else
876 {
877 if (status == STAT_NEED_DS_NEG)
878 new->flags |= FREC_CHECK_NOSIGN;
879 else
880 new->flags |= FREC_DS_QUERY;
881 nn = dnssec_generate_query(header,((char *) header) + daemon->packet_buff_sz,
882 daemon->keyname, forward->class, T_DS, &server->addr);
883 }
884 if ((hash = hash_questions(header, nn, daemon->namebuff)))
885 memcpy(new->hash, hash, HASH_SIZE);
886 new->new_id = get_id();
887 header->id = htons(new->new_id);
888 /* Save query for retransmission */
889 new->stash = blockdata_alloc((char *)header, nn);
890 new->stash_len = nn;
891
892 /* Don't resend this. */
893 daemon->srv_save = NULL;
894
895 if (server->sfd)
896 fd = server->sfd->fd;
897 else
898 {
899 fd = -1;
900 #ifdef HAVE_IPV6
901 if (server->addr.sa.sa_family == AF_INET6)
902 {
903 if (new->rfd6 || (new->rfd6 = allocate_rfd(AF_INET6)))
904 fd = new->rfd6->fd;
905 }
906 else
907 #endif
908 {
909 if (new->rfd4 || (new->rfd4 = allocate_rfd(AF_INET)))
910 fd = new->rfd4->fd;
911 }
912 }
913
914 if (fd != -1)
915 {
916 while (sendto(fd, (char *)header, nn, 0, &server->addr.sa, sa_len(&server->addr)) == -1 && retry_send());
917 server->queries++;
918 }
919
920 return;
921 }
922 }
923
924 /* Ok, we reached far enough up the chain-of-trust that we can validate something.
925 Now wind back down, pulling back answers which wouldn't previously validate
926 and validate them with the new data. Note that if an answer needs multiple
927 keys to validate, we may find another key is needed, in which case we set off
928 down another branch of the tree. Once we get to the original answer
929 (FREC_DNSSEC_QUERY not set) and it validates, return it to the original requestor. */
930 while (forward->dependent)
931 {
932 struct frec *prev = forward->dependent;
933 free_frec(forward);
934 forward = prev;
935 forward->blocking_query = NULL; /* already gone */
936 blockdata_retrieve(forward->stash, forward->stash_len, (void *)header);
937 n = forward->stash_len;
938
939 if (status == STAT_SECURE)
940 {
941 if (forward->flags & FREC_DNSKEY_QUERY)
942 status = dnssec_validate_by_ds(now, header, n, daemon->namebuff, daemon->keyname, forward->class);
943 else if (forward->flags & FREC_DS_QUERY)
944 {
945 status = dnssec_validate_ds(now, header, n, daemon->namebuff, daemon->keyname, forward->class);
946 if (status == STAT_NO_DS)
947 status = STAT_INSECURE;
948 }
949 else if (forward->flags & FREC_CHECK_NOSIGN)
950 status = do_check_sign(now, header, n, daemon->namebuff, daemon->keyname, forward->class);
951 else
952 {
953 status = dnssec_validate_reply(now, header, n, daemon->namebuff, daemon->keyname, &forward->class, NULL);
954 if (status == STAT_NO_SIG)
955 {
956 if (option_bool(OPT_DNSSEC_NO_SIGN))
957 status = send_check_sign(now, header, n, daemon->namebuff, daemon->keyname);
958 else
959 status = STAT_INSECURE;
960 }
961 }
962
963 if (status == STAT_NEED_DS || status == STAT_NEED_DS_NEG || status == STAT_NEED_KEY)
964 goto anotherkey;
965 }
966 }
967
968 if (status == STAT_TRUNCATED)
969 header->hb3 |= HB3_TC;
970 else
971 {
972 char *result;
973
974 if (forward->work_counter == 0)
975 result = "ABANDONED";
976 else
977 result = (status == STAT_SECURE ? "SECURE" : (status == STAT_INSECURE ? "INSECURE" : "BOGUS"));
978
979 log_query(F_KEYTAG | F_SECSTAT, "result", NULL, result);
980 }
981
982 no_cache_dnssec = 0;
983
984 if (status == STAT_SECURE)
985 cache_secure = 1;
986 else if (status == STAT_BOGUS)
987 no_cache_dnssec = 1;
988 }
989 #endif
990
991 /* restore CD bit to the value in the query */
992 if (forward->flags & FREC_CHECKING_DISABLED)
993 header->hb4 |= HB4_CD;
994 else
995 header->hb4 &= ~HB4_CD;
996
997 if ((nn = process_reply(header, now, server, (size_t)n, check_rebind, no_cache_dnssec, cache_secure,
998 forward->flags & FREC_AD_QUESTION, forward->flags & FREC_DO_QUESTION,
999 forward->flags & FREC_ADDED_PHEADER, forward->flags & FREC_HAS_SUBNET, &forward->source)))
1000 {
1001 header->id = htons(forward->orig_id);
1002 header->hb4 |= HB4_RA; /* recursion if available */
1003 send_from(forward->fd, option_bool(OPT_NOWILD) || option_bool (OPT_CLEVERBIND), daemon->packet, nn,
1004 &forward->source, &forward->dest, forward->iface);
1005 }
1006 free_frec(forward); /* cancel */
1007 }
1008 }
1009
1010
1011 void receive_query(struct listener *listen, time_t now)
1012 {
1013 struct dns_header *header = (struct dns_header *)daemon->packet;
1014 union mysockaddr source_addr;
1015 unsigned short type;
1016 struct all_addr dst_addr;
1017 struct in_addr netmask, dst_addr_4;
1018 size_t m;
1019 ssize_t n;
1020 int if_index = 0, auth_dns = 0;
1021 #ifdef HAVE_AUTH
1022 int local_auth = 0;
1023 #endif
1024 struct iovec iov[1];
1025 struct msghdr msg;
1026 struct cmsghdr *cmptr;
1027 union {
1028 struct cmsghdr align; /* this ensures alignment */
1029 #ifdef HAVE_IPV6
1030 char control6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
1031 #endif
1032 #if defined(HAVE_LINUX_NETWORK)
1033 char control[CMSG_SPACE(sizeof(struct in_pktinfo))];
1034 #elif defined(IP_RECVDSTADDR) && defined(HAVE_SOLARIS_NETWORK)
1035 char control[CMSG_SPACE(sizeof(struct in_addr)) +
1036 CMSG_SPACE(sizeof(unsigned int))];
1037 #elif defined(IP_RECVDSTADDR)
1038 char control[CMSG_SPACE(sizeof(struct in_addr)) +
1039 CMSG_SPACE(sizeof(struct sockaddr_dl))];
1040 #endif
1041 } control_u;
1042 #ifdef HAVE_IPV6
1043 /* Can always get recvd interface for IPv6 */
1044 int check_dst = !option_bool(OPT_NOWILD) || listen->family == AF_INET6;
1045 #else
1046 int check_dst = !option_bool(OPT_NOWILD);
1047 #endif
1048
1049 /* packet buffer overwritten */
1050 daemon->srv_save = NULL;
1051
1052 dst_addr_4.s_addr = 0;
1053 netmask.s_addr = 0;
1054
1055 if (option_bool(OPT_NOWILD) && listen->iface)
1056 {
1057 auth_dns = listen->iface->dns_auth;
1058
1059 if (listen->family == AF_INET)
1060 {
1061 dst_addr_4 = listen->iface->addr.in.sin_addr;
1062 netmask = listen->iface->netmask;
1063 }
1064 }
1065
1066 iov[0].iov_base = daemon->packet;
1067 iov[0].iov_len = daemon->edns_pktsz;
1068
1069 msg.msg_control = control_u.control;
1070 msg.msg_controllen = sizeof(control_u);
1071 msg.msg_flags = 0;
1072 msg.msg_name = &source_addr;
1073 msg.msg_namelen = sizeof(source_addr);
1074 msg.msg_iov = iov;
1075 msg.msg_iovlen = 1;
1076
1077 if ((n = recvmsg(listen->fd, &msg, 0)) == -1)
1078 return;
1079
1080 if (n < (int)sizeof(struct dns_header) ||
1081 (msg.msg_flags & MSG_TRUNC) ||
1082 (header->hb3 & HB3_QR))
1083 return;
1084
1085 source_addr.sa.sa_family = listen->family;
1086
1087 if (listen->family == AF_INET)
1088 {
1089 /* Source-port == 0 is an error, we can't send back to that.
1090 http://www.ietf.org/mail-archive/web/dnsop/current/msg11441.html */
1091 if (source_addr.in.sin_port == 0)
1092 return;
1093 }
1094 #ifdef HAVE_IPV6
1095 else
1096 {
1097 /* Source-port == 0 is an error, we can't send back to that. */
1098 if (source_addr.in6.sin6_port == 0)
1099 return;
1100 source_addr.in6.sin6_flowinfo = 0;
1101 }
1102 #endif
1103
1104 /* We can be configured to only accept queries from at-most-one-hop-away addresses. */
1105 if (option_bool(OPT_LOCAL_SERVICE))
1106 {
1107 struct addrlist *addr;
1108 #ifdef HAVE_IPV6
1109 if (listen->family == AF_INET6)
1110 {
1111 for (addr = daemon->interface_addrs; addr; addr = addr->next)
1112 if ((addr->flags & ADDRLIST_IPV6) &&
1113 is_same_net6(&addr->addr.addr.addr6, &source_addr.in6.sin6_addr, addr->prefixlen))
1114 break;
1115 }
1116 else
1117 #endif
1118 {
1119 struct in_addr netmask;
1120 for (addr = daemon->interface_addrs; addr; addr = addr->next)
1121 {
1122 netmask.s_addr = 0xffffffff << (32 - addr->prefixlen);
1123 if (!(addr->flags & ADDRLIST_IPV6) &&
1124 is_same_net(addr->addr.addr.addr4, source_addr.in.sin_addr, netmask))
1125 break;
1126 }
1127 }
1128 if (!addr)
1129 {
1130 static int warned = 0;
1131 if (!warned)
1132 {
1133 my_syslog(LOG_WARNING, _("Ignoring query from non-local network"));
1134 warned = 1;
1135 }
1136 return;
1137 }
1138 }
1139
1140 if (check_dst)
1141 {
1142 struct ifreq ifr;
1143
1144 if (msg.msg_controllen < sizeof(struct cmsghdr))
1145 return;
1146
1147 #if defined(HAVE_LINUX_NETWORK)
1148 if (listen->family == AF_INET)
1149 for (cmptr = CMSG_FIRSTHDR(&msg); cmptr; cmptr = CMSG_NXTHDR(&msg, cmptr))
1150 if (cmptr->cmsg_level == IPPROTO_IP && cmptr->cmsg_type == IP_PKTINFO)
1151 {
1152 union {
1153 unsigned char *c;
1154 struct in_pktinfo *p;
1155 } p;
1156 p.c = CMSG_DATA(cmptr);
1157 dst_addr_4 = dst_addr.addr.addr4 = p.p->ipi_spec_dst;
1158 if_index = p.p->ipi_ifindex;
1159 }
1160 #elif defined(IP_RECVDSTADDR) && defined(IP_RECVIF)
1161 if (listen->family == AF_INET)
1162 {
1163 for (cmptr = CMSG_FIRSTHDR(&msg); cmptr; cmptr = CMSG_NXTHDR(&msg, cmptr))
1164 {
1165 union {
1166 unsigned char *c;
1167 unsigned int *i;
1168 struct in_addr *a;
1169 #ifndef HAVE_SOLARIS_NETWORK
1170 struct sockaddr_dl *s;
1171 #endif
1172 } p;
1173 p.c = CMSG_DATA(cmptr);
1174 if (cmptr->cmsg_level == IPPROTO_IP && cmptr->cmsg_type == IP_RECVDSTADDR)
1175 dst_addr_4 = dst_addr.addr.addr4 = *(p.a);
1176 else if (cmptr->cmsg_level == IPPROTO_IP && cmptr->cmsg_type == IP_RECVIF)
1177 #ifdef HAVE_SOLARIS_NETWORK
1178 if_index = *(p.i);
1179 #else
1180 if_index = p.s->sdl_index;
1181 #endif
1182 }
1183 }
1184 #endif
1185
1186 #ifdef HAVE_IPV6
1187 if (listen->family == AF_INET6)
1188 {
1189 for (cmptr = CMSG_FIRSTHDR(&msg); cmptr; cmptr = CMSG_NXTHDR(&msg, cmptr))
1190 if (cmptr->cmsg_level == IPPROTO_IPV6 && cmptr->cmsg_type == daemon->v6pktinfo)
1191 {
1192 union {
1193 unsigned char *c;
1194 struct in6_pktinfo *p;
1195 } p;
1196 p.c = CMSG_DATA(cmptr);
1197
1198 dst_addr.addr.addr6 = p.p->ipi6_addr;
1199 if_index = p.p->ipi6_ifindex;
1200 }
1201 }
1202 #endif
1203
1204 /* enforce available interface configuration */
1205
1206 if (!indextoname(listen->fd, if_index, ifr.ifr_name))
1207 return;
1208
1209 if (!iface_check(listen->family, &dst_addr, ifr.ifr_name, &auth_dns))
1210 {
1211 if (!option_bool(OPT_CLEVERBIND))
1212 enumerate_interfaces(0);
1213 if (!loopback_exception(listen->fd, listen->family, &dst_addr, ifr.ifr_name) &&
1214 !label_exception(if_index, listen->family, &dst_addr))
1215 return;
1216 }
1217
1218 if (listen->family == AF_INET && option_bool(OPT_LOCALISE))
1219 {
1220 struct irec *iface;
1221
1222 /* get the netmask of the interface whch has the address we were sent to.
1223 This is no neccessarily the interface we arrived on. */
1224
1225 for (iface = daemon->interfaces; iface; iface = iface->next)
1226 if (iface->addr.sa.sa_family == AF_INET &&
1227 iface->addr.in.sin_addr.s_addr == dst_addr_4.s_addr)
1228 break;
1229
1230 /* interface may be new */
1231 if (!iface && !option_bool(OPT_CLEVERBIND))
1232 enumerate_interfaces(0);
1233
1234 for (iface = daemon->interfaces; iface; iface = iface->next)
1235 if (iface->addr.sa.sa_family == AF_INET &&
1236 iface->addr.in.sin_addr.s_addr == dst_addr_4.s_addr)
1237 break;
1238
1239 /* If we failed, abandon localisation */
1240 if (iface)
1241 netmask = iface->netmask;
1242 else
1243 dst_addr_4.s_addr = 0;
1244 }
1245 }
1246
1247 if (extract_request(header, (size_t)n, daemon->namebuff, &type))
1248 {
1249 #ifdef HAVE_AUTH
1250 struct auth_zone *zone;
1251 #endif
1252 char *types = querystr(auth_dns ? "auth" : "query", type);
1253
1254 if (listen->family == AF_INET)
1255 log_query(F_QUERY | F_IPV4 | F_FORWARD, daemon->namebuff,
1256 (struct all_addr *)&source_addr.in.sin_addr, types);
1257 #ifdef HAVE_IPV6
1258 else
1259 log_query(F_QUERY | F_IPV6 | F_FORWARD, daemon->namebuff,
1260 (struct all_addr *)&source_addr.in6.sin6_addr, types);
1261 #endif
1262
1263 #ifdef HAVE_AUTH
1264 /* find queries for zones we're authoritative for, and answer them directly */
1265 if (!auth_dns)
1266 for (zone = daemon->auth_zones; zone; zone = zone->next)
1267 if (in_zone(zone, daemon->namebuff, NULL))
1268 {
1269 auth_dns = 1;
1270 local_auth = 1;
1271 break;
1272 }
1273 #endif
1274 }
1275
1276 #ifdef HAVE_AUTH
1277 if (auth_dns)
1278 {
1279 m = answer_auth(header, ((char *) header) + daemon->packet_buff_sz, (size_t)n, now, &source_addr, local_auth);
1280 if (m >= 1)
1281 {
1282 send_from(listen->fd, option_bool(OPT_NOWILD) || option_bool(OPT_CLEVERBIND),
1283 (char *)header, m, &source_addr, &dst_addr, if_index);
1284 daemon->auth_answer++;
1285 }
1286 }
1287 else
1288 #endif
1289 {
1290 int ad_reqd, do_bit;
1291 m = answer_request(header, ((char *) header) + daemon->packet_buff_sz, (size_t)n,
1292 dst_addr_4, netmask, now, &ad_reqd, &do_bit);
1293
1294 if (m >= 1)
1295 {
1296 send_from(listen->fd, option_bool(OPT_NOWILD) || option_bool(OPT_CLEVERBIND),
1297 (char *)header, m, &source_addr, &dst_addr, if_index);
1298 daemon->local_answer++;
1299 }
1300 else if (forward_query(listen->fd, &source_addr, &dst_addr, if_index,
1301 header, (size_t)n, now, NULL, ad_reqd, do_bit))
1302 daemon->queries_forwarded++;
1303 else
1304 daemon->local_answer++;
1305 }
1306 }
1307
1308 #ifdef HAVE_DNSSEC
1309
1310 /* UDP: we've got an unsigned answer, return STAT_INSECURE if we can prove there's no DS
1311 and therefore the answer shouldn't be signed, or STAT_BOGUS if it should be, or
1312 STAT_NEED_DS_NEG and keyname if we need to do the query. */
1313 static int send_check_sign(time_t now, struct dns_header *header, size_t plen, char *name, char *keyname)
1314 {
1315 struct crec *crecp;
1316 char *name_start = name;
1317 int status = dnssec_chase_cname(now, header, plen, name, keyname);
1318
1319 if (status != STAT_INSECURE)
1320 return status;
1321
1322 while (1)
1323 {
1324 crecp = cache_find_by_name(NULL, name_start, now, F_DS);
1325
1326 if (crecp && (crecp->flags & F_DNSSECOK))
1327 return (crecp->flags & F_NEG) ? STAT_INSECURE : STAT_BOGUS;
1328
1329 if (crecp && (crecp->flags & F_NEG) && (name_start = strchr(name_start, '.')))
1330 {
1331 name_start++; /* chop a label off and try again */
1332 continue;
1333 }
1334
1335 /* Reached the root */
1336 if (!name_start)
1337 return STAT_BOGUS;
1338
1339 strcpy(keyname, name_start);
1340 return STAT_NEED_DS_NEG;
1341 }
1342 }
1343
1344 /* Got answer to DS query from send_check_sign, check for proven non-existence, or make the next DS query to try. */
1345 static int do_check_sign(time_t now, struct dns_header *header, size_t plen, char *name, char *keyname, int class)
1346
1347 {
1348 char *name_start;
1349 unsigned char *p;
1350 int status;
1351
1352 /* In this case only, a SERVFAIL reply allows us to continue up the tree, looking for a
1353 suitable NSEC reply to DS queries. */
1354 if (RCODE(header) != SERVFAIL)
1355 {
1356 status = dnssec_validate_ds(now, header, plen, name, keyname, class);
1357
1358 if (status != STAT_INSECURE)
1359 {
1360 if (status == STAT_NO_DS)
1361 status = STAT_INSECURE;
1362 return status;
1363 }
1364 }
1365
1366 p = (unsigned char *)(header+1);
1367
1368 if (extract_name(header, plen, &p, name, 1, 4) &&
1369 (name_start = strchr(name, '.')))
1370 {
1371 name_start++; /* chop a label off and try again */
1372 strcpy(keyname, name_start);
1373 return STAT_NEED_DS_NEG;
1374 }
1375
1376 return STAT_BOGUS;
1377 }
1378
1379 /* Move toward the root, until we find a signed non-existance of a DS, in which case
1380 an unsigned answer is OK, or we find a signed DS, in which case there should be
1381 a signature, and the answer is BOGUS */
1382 static int tcp_check_for_unsigned_zone(time_t now, struct dns_header *header, size_t plen, int class, char *name,
1383 char *keyname, struct server *server, int *keycount)
1384 {
1385 size_t m;
1386 unsigned char *packet, *payload;
1387 u16 *length;
1388 unsigned char *p = (unsigned char *)(header+1);
1389 int status;
1390 char *name_start = name;
1391
1392 /* Get first insecure entry in CNAME chain */
1393 status = tcp_key_recurse(now, STAT_CHASE_CNAME, header, plen, class, name, keyname, server, keycount);
1394 if (status == STAT_BOGUS)
1395 return STAT_BOGUS;
1396
1397 if (!(packet = whine_malloc(65536 + MAXDNAME + RRFIXEDSZ + sizeof(u16))))
1398 return STAT_BOGUS;
1399
1400 payload = &packet[2];
1401 header = (struct dns_header *)payload;
1402 length = (u16 *)packet;
1403
1404 while (1)
1405 {
1406 unsigned char *newhash, hash[HASH_SIZE];
1407 unsigned char c1, c2;
1408 struct crec *crecp = cache_find_by_name(NULL, name_start, now, F_DS);
1409
1410 if (--(*keycount) == 0)
1411 {
1412 free(packet);
1413 return STAT_BOGUS;
1414 }
1415
1416 if (crecp && (crecp->flags & F_DNSSECOK))
1417 {
1418 free(packet);
1419 return (crecp->flags & F_NEG) ? STAT_INSECURE : STAT_BOGUS;
1420 }
1421
1422 /* If we have cached insecurely that a DS doesn't exist,
1423 ise that is a hit for where to start looking for the secure one */
1424 if (crecp && (crecp->flags & F_NEG) && (name_start = strchr(name_start, '.')))
1425 {
1426 name_start++; /* chop a label off and try again */
1427 continue;
1428 }
1429
1430 /* reached the root */
1431 if (!name_start)
1432 {
1433 free(packet);
1434 return STAT_BOGUS;
1435 }
1436
1437 m = dnssec_generate_query(header, ((char *) header) + 65536, name_start, class, T_DS, &server->addr);
1438
1439 /* We rely on the question section coming back unchanged, ensure it is with the hash. */
1440 if ((newhash = hash_questions(header, (unsigned int)m, name)))
1441 {
1442 memcpy(hash, newhash, HASH_SIZE);
1443
1444 *length = htons(m);
1445
1446 if (read_write(server->tcpfd, packet, m + sizeof(u16), 0) &&
1447 read_write(server->tcpfd, &c1, 1, 1) &&
1448 read_write(server->tcpfd, &c2, 1, 1) &&
1449 read_write(server->tcpfd, payload, (c1 << 8) | c2, 1))
1450 {
1451 m = (c1 << 8) | c2;
1452
1453 newhash = hash_questions(header, (unsigned int)m, name);
1454 if (newhash && memcmp(hash, newhash, HASH_SIZE) == 0)
1455 {
1456 /* In this case only, a SERVFAIL reply allows us to continue up the tree, looking for a
1457 suitable NSEC reply to DS queries. */
1458 if (RCODE(header) == SERVFAIL)
1459 status = STAT_INSECURE;
1460 else
1461 /* Note this trashes all three name workspaces */
1462 status = tcp_key_recurse(now, STAT_NEED_DS_NEG, header, m, class, name, keyname, server, keycount);
1463
1464 /* We've found a DS which proves the bit of the DNS where the
1465 original query is, is unsigned, so the answer is OK,
1466 if unvalidated. */
1467 if (status == STAT_NO_DS)
1468 {
1469 free(packet);
1470 return STAT_INSECURE;
1471 }
1472
1473 /* No DS, not got to DNSSEC-land yet, go up. */
1474 if (status == STAT_INSECURE)
1475 {
1476 p = (unsigned char *)(header+1);
1477
1478 if (extract_name(header, plen, &p, name, 1, 4) &&
1479 (name_start = strchr(name, '.')))
1480 {
1481 name_start++; /* chop a label off and try again */
1482 continue;
1483 }
1484 }
1485 }
1486 }
1487 }
1488
1489 free(packet);
1490
1491 return STAT_BOGUS;
1492 }
1493 }
1494
1495 static int tcp_key_recurse(time_t now, int status, struct dns_header *header, size_t n,
1496 int class, char *name, char *keyname, struct server *server, int *keycount)
1497 {
1498 /* Recurse up the key heirarchy */
1499 int new_status;
1500
1501 /* limit the amount of work we do, to avoid cycling forever on loops in the DNS */
1502 if (--(*keycount) == 0)
1503 return STAT_INSECURE;
1504
1505 if (status == STAT_NEED_KEY)
1506 new_status = dnssec_validate_by_ds(now, header, n, name, keyname, class);
1507 else if (status == STAT_NEED_DS || status == STAT_NEED_DS_NEG)
1508 {
1509 new_status = dnssec_validate_ds(now, header, n, name, keyname, class);
1510 if (status == STAT_NEED_DS && new_status == STAT_NO_DS)
1511 new_status = STAT_INSECURE;
1512 }
1513 else if (status == STAT_CHASE_CNAME)
1514 new_status = dnssec_chase_cname(now, header, n, name, keyname);
1515 else
1516 {
1517 new_status = dnssec_validate_reply(now, header, n, name, keyname, &class, NULL);
1518
1519 if (new_status == STAT_NO_SIG)
1520 {
1521 if (option_bool(OPT_DNSSEC_NO_SIGN))
1522 new_status = tcp_check_for_unsigned_zone(now, header, n, class, name, keyname, server, keycount);
1523 else
1524 new_status = STAT_INSECURE;
1525 }
1526 }
1527
1528 /* Can't validate because we need a key/DS whose name now in keyname.
1529 Make query for same, and recurse to validate */
1530 if (new_status == STAT_NEED_DS || new_status == STAT_NEED_KEY)
1531 {
1532 size_t m;
1533 unsigned char *packet = whine_malloc(65536 + MAXDNAME + RRFIXEDSZ + sizeof(u16));
1534 unsigned char *payload = &packet[2];
1535 struct dns_header *new_header = (struct dns_header *)payload;
1536 u16 *length = (u16 *)packet;
1537 unsigned char c1, c2;
1538
1539 if (!packet)
1540 return STAT_INSECURE;
1541
1542 another_tcp_key:
1543 m = dnssec_generate_query(new_header, ((char *) new_header) + 65536, keyname, class,
1544 new_status == STAT_NEED_KEY ? T_DNSKEY : T_DS, &server->addr);
1545
1546 *length = htons(m);
1547
1548 if (!read_write(server->tcpfd, packet, m + sizeof(u16), 0) ||
1549 !read_write(server->tcpfd, &c1, 1, 1) ||
1550 !read_write(server->tcpfd, &c2, 1, 1) ||
1551 !read_write(server->tcpfd, payload, (c1 << 8) | c2, 1))
1552 new_status = STAT_INSECURE;
1553 else
1554 {
1555 m = (c1 << 8) | c2;
1556
1557 new_status = tcp_key_recurse(now, new_status, new_header, m, class, name, keyname, server, keycount);
1558
1559 if (new_status == STAT_SECURE)
1560 {
1561 /* Reached a validated record, now try again at this level.
1562 Note that we may get ANOTHER NEED_* if an answer needs more than one key.
1563 If so, go round again. */
1564
1565 if (status == STAT_NEED_KEY)
1566 new_status = dnssec_validate_by_ds(now, header, n, name, keyname, class);
1567 else if (status == STAT_NEED_DS || status == STAT_NEED_DS_NEG)
1568 {
1569 new_status = dnssec_validate_ds(now, header, n, name, keyname, class);
1570 if (status == STAT_NEED_DS && new_status == STAT_NO_DS)
1571 new_status = STAT_INSECURE; /* Validated no DS */
1572 }
1573 else if (status == STAT_CHASE_CNAME)
1574 new_status = dnssec_chase_cname(now, header, n, name, keyname);
1575 else
1576 {
1577 new_status = dnssec_validate_reply(now, header, n, name, keyname, &class, NULL);
1578
1579 if (new_status == STAT_NO_SIG)
1580 {
1581 if (option_bool(OPT_DNSSEC_NO_SIGN))
1582 new_status = tcp_check_for_unsigned_zone(now, header, n, class, name, keyname, server, keycount);
1583 else
1584 new_status = STAT_INSECURE;
1585 }
1586 }
1587
1588 if (new_status == STAT_NEED_DS || new_status == STAT_NEED_KEY)
1589 goto another_tcp_key;
1590 }
1591 }
1592
1593 free(packet);
1594 }
1595 return new_status;
1596 }
1597 #endif
1598
1599
1600 /* The daemon forks before calling this: it should deal with one connection,
1601 blocking as neccessary, and then return. Note, need to be a bit careful
1602 about resources for debug mode, when the fork is suppressed: that's
1603 done by the caller. */
1604 unsigned char *tcp_request(int confd, time_t now,
1605 union mysockaddr *local_addr, struct in_addr netmask, int auth_dns)
1606 {
1607 size_t size = 0;
1608 int norebind = 0;
1609 #ifdef HAVE_AUTH
1610 int local_auth = 0;
1611 #endif
1612 int checking_disabled, ad_question, do_bit, added_pheader = 0;
1613 int check_subnet, no_cache_dnssec = 0, cache_secure = 0;
1614 size_t m;
1615 unsigned short qtype;
1616 unsigned int gotname;
1617 unsigned char c1, c2;
1618 /* Max TCP packet + slop + size */
1619 unsigned char *packet = whine_malloc(65536 + MAXDNAME + RRFIXEDSZ + sizeof(u16));
1620 unsigned char *payload = &packet[2];
1621 /* largest field in header is 16-bits, so this is still sufficiently aligned */
1622 struct dns_header *header = (struct dns_header *)payload;
1623 u16 *length = (u16 *)packet;
1624 struct server *last_server;
1625 struct in_addr dst_addr_4;
1626 union mysockaddr peer_addr;
1627 socklen_t peer_len = sizeof(union mysockaddr);
1628
1629 if (getpeername(confd, (struct sockaddr *)&peer_addr, &peer_len) == -1)
1630 return packet;
1631
1632 /* We can be configured to only accept queries from at-most-one-hop-away addresses. */
1633 if (option_bool(OPT_LOCAL_SERVICE))
1634 {
1635 struct addrlist *addr;
1636 #ifdef HAVE_IPV6
1637 if (peer_addr.sa.sa_family == AF_INET6)
1638 {
1639 for (addr = daemon->interface_addrs; addr; addr = addr->next)
1640 if ((addr->flags & ADDRLIST_IPV6) &&
1641 is_same_net6(&addr->addr.addr.addr6, &peer_addr.in6.sin6_addr, addr->prefixlen))
1642 break;
1643 }
1644 else
1645 #endif
1646 {
1647 struct in_addr netmask;
1648 for (addr = daemon->interface_addrs; addr; addr = addr->next)
1649 {
1650 netmask.s_addr = 0xffffffff << (32 - addr->prefixlen);
1651 if (!(addr->flags & ADDRLIST_IPV6) &&
1652 is_same_net(addr->addr.addr.addr4, peer_addr.in.sin_addr, netmask))
1653 break;
1654 }
1655 }
1656 if (!addr)
1657 {
1658 my_syslog(LOG_WARNING, _("Ignoring query from non-local network"));
1659 return packet;
1660 }
1661 }
1662
1663 while (1)
1664 {
1665 if (!packet ||
1666 !read_write(confd, &c1, 1, 1) || !read_write(confd, &c2, 1, 1) ||
1667 !(size = c1 << 8 | c2) ||
1668 !read_write(confd, payload, size, 1))
1669 return packet;
1670
1671 if (size < (int)sizeof(struct dns_header))
1672 continue;
1673
1674 check_subnet = 0;
1675
1676 /* save state of "cd" flag in query */
1677 if ((checking_disabled = header->hb4 & HB4_CD))
1678 no_cache_dnssec = 1;
1679
1680 if ((gotname = extract_request(header, (unsigned int)size, daemon->namebuff, &qtype)))
1681 {
1682 #ifdef HAVE_AUTH
1683 struct auth_zone *zone;
1684 #endif
1685 char *types = querystr(auth_dns ? "auth" : "query", qtype);
1686
1687 if (peer_addr.sa.sa_family == AF_INET)
1688 log_query(F_QUERY | F_IPV4 | F_FORWARD, daemon->namebuff,
1689 (struct all_addr *)&peer_addr.in.sin_addr, types);
1690 #ifdef HAVE_IPV6
1691 else
1692 log_query(F_QUERY | F_IPV6 | F_FORWARD, daemon->namebuff,
1693 (struct all_addr *)&peer_addr.in6.sin6_addr, types);
1694 #endif
1695
1696 #ifdef HAVE_AUTH
1697 /* find queries for zones we're authoritative for, and answer them directly */
1698 if (!auth_dns)
1699 for (zone = daemon->auth_zones; zone; zone = zone->next)
1700 if (in_zone(zone, daemon->namebuff, NULL))
1701 {
1702 auth_dns = 1;
1703 local_auth = 1;
1704 break;
1705 }
1706 #endif
1707 }
1708
1709 if (local_addr->sa.sa_family == AF_INET)
1710 dst_addr_4 = local_addr->in.sin_addr;
1711 else
1712 dst_addr_4.s_addr = 0;
1713
1714 #ifdef HAVE_AUTH
1715 if (auth_dns)
1716 m = answer_auth(header, ((char *) header) + 65536, (size_t)size, now, &peer_addr, local_auth);
1717 else
1718 #endif
1719 {
1720 /* m > 0 if answered from cache */
1721 m = answer_request(header, ((char *) header) + 65536, (size_t)size,
1722 dst_addr_4, netmask, now, &ad_question, &do_bit);
1723
1724 /* Do this by steam now we're not in the select() loop */
1725 check_log_writer(NULL);
1726
1727 if (m == 0)
1728 {
1729 unsigned int flags = 0;
1730 struct all_addr *addrp = NULL;
1731 int type = 0;
1732 char *domain = NULL;
1733
1734 if (option_bool(OPT_ADD_MAC))
1735 size = add_mac(header, size, ((char *) header) + 65536, &peer_addr);
1736
1737 if (option_bool(OPT_CLIENT_SUBNET))
1738 {
1739 size_t new = add_source_addr(header, size, ((char *) header) + 65536, &peer_addr);
1740 if (size != new)
1741 {
1742 size = new;
1743 check_subnet = 1;
1744 }
1745 }
1746
1747 if (gotname)
1748 flags = search_servers(now, &addrp, gotname, daemon->namebuff, &type, &domain, &norebind);
1749
1750 if (type != 0 || option_bool(OPT_ORDER) || !daemon->last_server)
1751 last_server = daemon->servers;
1752 else
1753 last_server = daemon->last_server;
1754
1755 if (!flags && last_server)
1756 {
1757 struct server *firstsendto = NULL;
1758 #ifdef HAVE_DNSSEC
1759 unsigned char *newhash, hash[HASH_SIZE];
1760 if ((newhash = hash_questions(header, (unsigned int)size, daemon->namebuff)))
1761 memcpy(hash, newhash, HASH_SIZE);
1762 else
1763 memset(hash, 0, HASH_SIZE);
1764 #else
1765 unsigned int crc = questions_crc(header, (unsigned int)size, daemon->namebuff);
1766 #endif
1767 /* Loop round available servers until we succeed in connecting to one.
1768 Note that this code subtley ensures that consecutive queries on this connection
1769 which can go to the same server, do so. */
1770 while (1)
1771 {
1772 if (!firstsendto)
1773 firstsendto = last_server;
1774 else
1775 {
1776 if (!(last_server = last_server->next))
1777 last_server = daemon->servers;
1778
1779 if (last_server == firstsendto)
1780 break;
1781 }
1782
1783 /* server for wrong domain */
1784 if (type != (last_server->flags & SERV_TYPE) ||
1785 (type == SERV_HAS_DOMAIN && !hostname_isequal(domain, last_server->domain)))
1786 continue;
1787
1788 if (last_server->tcpfd == -1)
1789 {
1790 if ((last_server->tcpfd = socket(last_server->addr.sa.sa_family, SOCK_STREAM, 0)) == -1)
1791 continue;
1792
1793 if ((!local_bind(last_server->tcpfd, &last_server->source_addr, last_server->interface, 1) ||
1794 connect(last_server->tcpfd, &last_server->addr.sa, sa_len(&last_server->addr)) == -1))
1795 {
1796 close(last_server->tcpfd);
1797 last_server->tcpfd = -1;
1798 continue;
1799 }
1800
1801 #ifdef HAVE_DNSSEC
1802 if (option_bool(OPT_DNSSEC_VALID))
1803 {
1804 size_t new_size = add_do_bit(header, size, ((char *) header) + 65536);
1805
1806 /* For debugging, set Checking Disabled, otherwise, have the upstream check too,
1807 this allows it to select auth servers when one is returning bad data. */
1808 if (option_bool(OPT_DNSSEC_DEBUG))
1809 header->hb4 |= HB4_CD;
1810
1811 if (size != new_size)
1812 added_pheader = 1;
1813
1814 size = new_size;
1815 }
1816 #endif
1817
1818 #ifdef HAVE_CONNTRACK
1819 /* Copy connection mark of incoming query to outgoing connection. */
1820 if (option_bool(OPT_CONNTRACK))
1821 {
1822 unsigned int mark;
1823 struct all_addr local;
1824 #ifdef HAVE_IPV6
1825 if (local_addr->sa.sa_family == AF_INET6)
1826 local.addr.addr6 = local_addr->in6.sin6_addr;
1827 else
1828 #endif
1829 local.addr.addr4 = local_addr->in.sin_addr;
1830
1831 if (get_incoming_mark(&peer_addr, &local, 1, &mark))
1832 setsockopt(last_server->tcpfd, SOL_SOCKET, SO_MARK, &mark, sizeof(unsigned int));
1833 }
1834 #endif
1835 }
1836
1837 *length = htons(size);
1838
1839 /* get query name again for logging - may have been overwritten */
1840 if (!(gotname = extract_request(header, (unsigned int)size, daemon->namebuff, &qtype)))
1841 strcpy(daemon->namebuff, "query");
1842
1843 if (!read_write(last_server->tcpfd, packet, size + sizeof(u16), 0) ||
1844 !read_write(last_server->tcpfd, &c1, 1, 1) ||
1845 !read_write(last_server->tcpfd, &c2, 1, 1) ||
1846 !read_write(last_server->tcpfd, payload, (c1 << 8) | c2, 1))
1847 {
1848 close(last_server->tcpfd);
1849 last_server->tcpfd = -1;
1850 continue;
1851 }
1852
1853 m = (c1 << 8) | c2;
1854
1855 if (last_server->addr.sa.sa_family == AF_INET)
1856 log_query(F_SERVER | F_IPV4 | F_FORWARD, daemon->namebuff,
1857 (struct all_addr *)&last_server->addr.in.sin_addr, NULL);
1858 #ifdef HAVE_IPV6
1859 else
1860 log_query(F_SERVER | F_IPV6 | F_FORWARD, daemon->namebuff,
1861 (struct all_addr *)&last_server->addr.in6.sin6_addr, NULL);
1862 #endif
1863
1864 #ifdef HAVE_DNSSEC
1865 if (option_bool(OPT_DNSSEC_VALID) && !checking_disabled)
1866 {
1867 int keycount = DNSSEC_WORK; /* Limit to number of DNSSEC questions, to catch loops and avoid filling cache. */
1868 int status = tcp_key_recurse(now, STAT_TRUNCATED, header, m, 0, daemon->namebuff, daemon->keyname, last_server, &keycount);
1869 char *result;
1870
1871 if (keycount == 0)
1872 result = "ABANDONED";
1873 else
1874 result = (status == STAT_SECURE ? "SECURE" : (status == STAT_INSECURE ? "INSECURE" : "BOGUS"));
1875
1876 log_query(F_KEYTAG | F_SECSTAT, "result", NULL, result);
1877
1878 if (status == STAT_BOGUS)
1879 no_cache_dnssec = 1;
1880
1881 if (status == STAT_SECURE)
1882 cache_secure = 1;
1883 }
1884 #endif
1885
1886 /* restore CD bit to the value in the query */
1887 if (checking_disabled)
1888 header->hb4 |= HB4_CD;
1889 else
1890 header->hb4 &= ~HB4_CD;
1891
1892 /* There's no point in updating the cache, since this process will exit and
1893 lose the information after a few queries. We make this call for the alias and
1894 bogus-nxdomain side-effects. */
1895 /* If the crc of the question section doesn't match the crc we sent, then
1896 someone might be attempting to insert bogus values into the cache by
1897 sending replies containing questions and bogus answers. */
1898 #ifdef HAVE_DNSSEC
1899 newhash = hash_questions(header, (unsigned int)m, daemon->namebuff);
1900 if (!newhash || memcmp(hash, newhash, HASH_SIZE) != 0)
1901 {
1902 m = 0;
1903 break;
1904 }
1905 #else
1906 if (crc != questions_crc(header, (unsigned int)m, daemon->namebuff))
1907 {
1908 m = 0;
1909 break;
1910 }
1911 #endif
1912
1913 m = process_reply(header, now, last_server, (unsigned int)m,
1914 option_bool(OPT_NO_REBIND) && !norebind, no_cache_dnssec,
1915 cache_secure, ad_question, do_bit, added_pheader, check_subnet, &peer_addr);
1916
1917 break;
1918 }
1919 }
1920
1921 /* In case of local answer or no connections made. */
1922 if (m == 0)
1923 m = setup_reply(header, (unsigned int)size, addrp, flags, daemon->local_ttl);
1924 }
1925 }
1926
1927 check_log_writer(NULL);
1928
1929 *length = htons(m);
1930
1931 if (m == 0 || !read_write(confd, packet, m + sizeof(u16), 0))
1932 return packet;
1933 }
1934 }
1935
1936 static struct frec *allocate_frec(time_t now)
1937 {
1938 struct frec *f;
1939
1940 if ((f = (struct frec *)whine_malloc(sizeof(struct frec))))
1941 {
1942 f->next = daemon->frec_list;
1943 f->time = now;
1944 f->sentto = NULL;
1945 f->rfd4 = NULL;
1946 f->flags = 0;
1947 #ifdef HAVE_IPV6
1948 f->rfd6 = NULL;
1949 #endif
1950 #ifdef HAVE_DNSSEC
1951 f->dependent = NULL;
1952 f->blocking_query = NULL;
1953 f->stash = NULL;
1954 #endif
1955 daemon->frec_list = f;
1956 }
1957
1958 return f;
1959 }
1960
1961 static struct randfd *allocate_rfd(int family)
1962 {
1963 static int finger = 0;
1964 int i;
1965
1966 /* limit the number of sockets we have open to avoid starvation of
1967 (eg) TFTP. Once we have a reasonable number, randomness should be OK */
1968
1969 for (i = 0; i < RANDOM_SOCKS; i++)
1970 if (daemon->randomsocks[i].refcount == 0)
1971 {
1972 if ((daemon->randomsocks[i].fd = random_sock(family)) == -1)
1973 break;
1974
1975 daemon->randomsocks[i].refcount = 1;
1976 daemon->randomsocks[i].family = family;
1977 return &daemon->randomsocks[i];
1978 }
1979
1980 /* No free ones or cannot get new socket, grab an existing one */
1981 for (i = 0; i < RANDOM_SOCKS; i++)
1982 {
1983 int j = (i+finger) % RANDOM_SOCKS;
1984 if (daemon->randomsocks[j].refcount != 0 &&
1985 daemon->randomsocks[j].family == family &&
1986 daemon->randomsocks[j].refcount != 0xffff)
1987 {
1988 finger = j;
1989 daemon->randomsocks[j].refcount++;
1990 return &daemon->randomsocks[j];
1991 }
1992 }
1993
1994 return NULL; /* doom */
1995 }
1996 static void free_frec(struct frec *f)
1997 {
1998 if (f->rfd4 && --(f->rfd4->refcount) == 0)
1999 close(f->rfd4->fd);
2000
2001 f->rfd4 = NULL;
2002 f->sentto = NULL;
2003 f->flags = 0;
2004
2005 #ifdef HAVE_IPV6
2006 if (f->rfd6 && --(f->rfd6->refcount) == 0)
2007 close(f->rfd6->fd);
2008
2009 f->rfd6 = NULL;
2010 #endif
2011
2012 #ifdef HAVE_DNSSEC
2013 if (f->stash)
2014 {
2015 blockdata_free(f->stash);
2016 f->stash = NULL;
2017 }
2018
2019 /* Anything we're waiting on is pointless now, too */
2020 if (f->blocking_query)
2021 free_frec(f->blocking_query);
2022 f->blocking_query = NULL;
2023 f->dependent = NULL;
2024 #endif
2025 }
2026
2027 /* if wait==NULL return a free or older than TIMEOUT record.
2028 else return *wait zero if one available, or *wait is delay to
2029 when the oldest in-use record will expire. Impose an absolute
2030 limit of 4*TIMEOUT before we wipe things (for random sockets).
2031 If force is set, always return a result, even if we have
2032 to allocate above the limit. */
2033 struct frec *get_new_frec(time_t now, int *wait, int force)
2034 {
2035 struct frec *f, *oldest, *target;
2036 int count;
2037
2038 if (wait)
2039 *wait = 0;
2040
2041 for (f = daemon->frec_list, oldest = NULL, target = NULL, count = 0; f; f = f->next, count++)
2042 if (!f->sentto)
2043 target = f;
2044 else
2045 {
2046 if (difftime(now, f->time) >= 4*TIMEOUT)
2047 {
2048 free_frec(f);
2049 target = f;
2050 }
2051
2052 if (!oldest || difftime(f->time, oldest->time) <= 0)
2053 oldest = f;
2054 }
2055
2056 if (target)
2057 {
2058 target->time = now;
2059 return target;
2060 }
2061
2062 /* can't find empty one, use oldest if there is one
2063 and it's older than timeout */
2064 if (oldest && ((int)difftime(now, oldest->time)) >= TIMEOUT)
2065 {
2066 /* keep stuff for twice timeout if we can by allocating a new
2067 record instead */
2068 if (difftime(now, oldest->time) < 2*TIMEOUT &&
2069 count <= daemon->ftabsize &&
2070 (f = allocate_frec(now)))
2071 return f;
2072
2073 if (!wait)
2074 {
2075 free_frec(oldest);
2076 oldest->time = now;
2077 }
2078 return oldest;
2079 }
2080
2081 /* none available, calculate time 'till oldest record expires */
2082 if (!force && count > daemon->ftabsize)
2083 {
2084 static time_t last_log = 0;
2085
2086 if (oldest && wait)
2087 *wait = oldest->time + (time_t)TIMEOUT - now;
2088
2089 if ((int)difftime(now, last_log) > 5)
2090 {
2091 last_log = now;
2092 my_syslog(LOG_WARNING, _("Maximum number of concurrent DNS queries reached (max: %d)"), daemon->ftabsize);
2093 }
2094
2095 return NULL;
2096 }
2097
2098 if (!(f = allocate_frec(now)) && wait)
2099 /* wait one second on malloc failure */
2100 *wait = 1;
2101
2102 return f; /* OK if malloc fails and this is NULL */
2103 }
2104
2105 /* crc is all-ones if not known. */
2106 static struct frec *lookup_frec(unsigned short id, void *hash)
2107 {
2108 struct frec *f;
2109
2110 for(f = daemon->frec_list; f; f = f->next)
2111 if (f->sentto && f->new_id == id &&
2112 (!hash || memcmp(hash, f->hash, HASH_SIZE) == 0))
2113 return f;
2114
2115 return NULL;
2116 }
2117
2118 static struct frec *lookup_frec_by_sender(unsigned short id,
2119 union mysockaddr *addr,
2120 void *hash)
2121 {
2122 struct frec *f;
2123
2124 for(f = daemon->frec_list; f; f = f->next)
2125 if (f->sentto &&
2126 f->orig_id == id &&
2127 memcmp(hash, f->hash, HASH_SIZE) == 0 &&
2128 sockaddr_isequal(&f->source, addr))
2129 return f;
2130
2131 return NULL;
2132 }
2133
2134 /* A server record is going away, remove references to it */
2135 void server_gone(struct server *server)
2136 {
2137 struct frec *f;
2138
2139 for (f = daemon->frec_list; f; f = f->next)
2140 if (f->sentto && f->sentto == server)
2141 free_frec(f);
2142
2143 if (daemon->last_server == server)
2144 daemon->last_server = NULL;
2145
2146 if (daemon->srv_save == server)
2147 daemon->srv_save = NULL;
2148 }
2149
2150 /* return unique random ids. */
2151 static unsigned short get_id(void)
2152 {
2153 unsigned short ret = 0;
2154
2155 do
2156 ret = rand16();
2157 while (lookup_frec(ret, NULL));
2158
2159 return ret;
2160 }
2161
2162
2163
2164
2165
Michael's tree of dnsmasq.