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1 | /* dnsmasq is Copyright (c) 2000-2013 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, unsigned int crc); | |
20 | static struct frec *lookup_frec_by_sender(unsigned short id, | |
21 | union mysockaddr *addr, | |
22 | unsigned int crc); | |
23 | static unsigned short get_id(unsigned int crc); | |
24 | static void free_frec(struct frec *f); | |
25 | static struct randfd *allocate_rfd(int family); | |
26 | ||
27 | /* Send a UDP packet with its source address set as "source" | |
28 | unless nowild is true, when we just send it with the kernel default */ | |
29 | int send_from(int fd, int nowild, char *packet, size_t len, | |
30 | union mysockaddr *to, struct all_addr *source, | |
31 | unsigned int iface) | |
32 | { | |
33 | struct msghdr msg; | |
34 | struct iovec iov[1]; | |
35 | union { | |
36 | struct cmsghdr align; /* this ensures alignment */ | |
37 | #if defined(HAVE_LINUX_NETWORK) | |
38 | char control[CMSG_SPACE(sizeof(struct in_pktinfo))]; | |
39 | #elif defined(IP_SENDSRCADDR) | |
40 | char control[CMSG_SPACE(sizeof(struct in_addr))]; | |
41 | #endif | |
42 | #ifdef HAVE_IPV6 | |
43 | char control6[CMSG_SPACE(sizeof(struct in6_pktinfo))]; | |
44 | #endif | |
45 | } control_u; | |
46 | ||
47 | iov[0].iov_base = packet; | |
48 | iov[0].iov_len = len; | |
49 | ||
50 | msg.msg_control = NULL; | |
51 | msg.msg_controllen = 0; | |
52 | msg.msg_flags = 0; | |
53 | msg.msg_name = to; | |
54 | msg.msg_namelen = sa_len(to); | |
55 | msg.msg_iov = iov; | |
56 | msg.msg_iovlen = 1; | |
57 | ||
58 | if (!nowild) | |
59 | { | |
60 | struct cmsghdr *cmptr; | |
61 | msg.msg_control = &control_u; | |
62 | msg.msg_controllen = sizeof(control_u); | |
63 | cmptr = CMSG_FIRSTHDR(&msg); | |
64 | ||
65 | if (to->sa.sa_family == AF_INET) | |
66 | { | |
67 | #if defined(HAVE_LINUX_NETWORK) | |
68 | struct in_pktinfo p; | |
69 | p.ipi_ifindex = 0; | |
70 | p.ipi_spec_dst = source->addr.addr4; | |
71 | memcpy(CMSG_DATA(cmptr), &p, sizeof(p)); | |
72 | msg.msg_controllen = cmptr->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo)); | |
73 | cmptr->cmsg_level = IPPROTO_IP; | |
74 | cmptr->cmsg_type = IP_PKTINFO; | |
75 | #elif defined(IP_SENDSRCADDR) | |
76 | memcpy(CMSG_DATA(cmptr), &(source->addr.addr4), sizeof(source->addr.addr4)); | |
77 | msg.msg_controllen = cmptr->cmsg_len = CMSG_LEN(sizeof(struct in_addr)); | |
78 | cmptr->cmsg_level = IPPROTO_IP; | |
79 | cmptr->cmsg_type = IP_SENDSRCADDR; | |
80 | #endif | |
81 | } | |
82 | else | |
83 | #ifdef HAVE_IPV6 | |
84 | { | |
85 | struct in6_pktinfo p; | |
86 | p.ipi6_ifindex = iface; /* Need iface for IPv6 to handle link-local addrs */ | |
87 | p.ipi6_addr = source->addr.addr6; | |
88 | memcpy(CMSG_DATA(cmptr), &p, sizeof(p)); | |
89 | msg.msg_controllen = cmptr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo)); | |
90 | cmptr->cmsg_type = daemon->v6pktinfo; | |
91 | cmptr->cmsg_level = IPPROTO_IPV6; | |
92 | } | |
93 | #else | |
94 | (void)iface; /* eliminate warning */ | |
95 | #endif | |
96 | } | |
97 | ||
98 | while (sendmsg(fd, &msg, 0) == -1) | |
99 | { | |
100 | if (retry_send()) | |
101 | continue; | |
102 | ||
103 | /* If interface is still in DAD, EINVAL results - ignore that. */ | |
104 | if (errno == EINVAL) | |
105 | break; | |
106 | ||
107 | my_syslog(LOG_ERR, _("failed to send packet: %s"), strerror(errno)); | |
108 | return 0; | |
109 | } | |
110 | ||
111 | return 1; | |
112 | } | |
113 | ||
114 | static unsigned int search_servers(time_t now, struct all_addr **addrpp, | |
115 | unsigned int qtype, char *qdomain, int *type, char **domain, int *norebind) | |
116 | ||
117 | { | |
118 | /* If the query ends in the domain in one of our servers, set | |
119 | domain to point to that name. We find the largest match to allow both | |
120 | domain.org and sub.domain.org to exist. */ | |
121 | ||
122 | unsigned int namelen = strlen(qdomain); | |
123 | unsigned int matchlen = 0; | |
124 | struct server *serv; | |
125 | unsigned int flags = 0; | |
126 | ||
127 | for (serv = daemon->servers; serv; serv=serv->next) | |
128 | /* domain matches take priority over NODOTS matches */ | |
129 | if ((serv->flags & SERV_FOR_NODOTS) && *type != SERV_HAS_DOMAIN && !strchr(qdomain, '.') && namelen != 0) | |
130 | { | |
131 | unsigned int sflag = serv->addr.sa.sa_family == AF_INET ? F_IPV4 : F_IPV6; | |
132 | *type = SERV_FOR_NODOTS; | |
133 | if (serv->flags & SERV_NO_ADDR) | |
134 | flags = F_NXDOMAIN; | |
135 | else if (serv->flags & SERV_LITERAL_ADDRESS) | |
136 | { | |
137 | if (sflag & qtype) | |
138 | { | |
139 | flags = sflag; | |
140 | if (serv->addr.sa.sa_family == AF_INET) | |
141 | *addrpp = (struct all_addr *)&serv->addr.in.sin_addr; | |
142 | #ifdef HAVE_IPV6 | |
143 | else | |
144 | *addrpp = (struct all_addr *)&serv->addr.in6.sin6_addr; | |
145 | #endif | |
146 | } | |
147 | else if (!flags || (flags & F_NXDOMAIN)) | |
148 | flags = F_NOERR; | |
149 | } | |
150 | } | |
151 | else if (serv->flags & SERV_HAS_DOMAIN) | |
152 | { | |
153 | unsigned int domainlen = strlen(serv->domain); | |
154 | char *matchstart = qdomain + namelen - domainlen; | |
155 | if (namelen >= domainlen && | |
156 | hostname_isequal(matchstart, serv->domain) && | |
157 | (domainlen == 0 || namelen == domainlen || *(matchstart-1) == '.' )) | |
158 | { | |
159 | if (serv->flags & SERV_NO_REBIND) | |
160 | *norebind = 1; | |
161 | else | |
162 | { | |
163 | unsigned int sflag = serv->addr.sa.sa_family == AF_INET ? F_IPV4 : F_IPV6; | |
164 | /* implement priority rules for --address and --server for same domain. | |
165 | --address wins if the address is for the correct AF | |
166 | --server wins otherwise. */ | |
167 | if (domainlen != 0 && domainlen == matchlen) | |
168 | { | |
169 | if ((serv->flags & SERV_LITERAL_ADDRESS)) | |
170 | { | |
171 | if (!(sflag & qtype) && flags == 0) | |
172 | continue; | |
173 | } | |
174 | else | |
175 | { | |
176 | if (flags & (F_IPV4 | F_IPV6)) | |
177 | continue; | |
178 | } | |
179 | } | |
180 | ||
181 | if (domainlen >= matchlen) | |
182 | { | |
183 | *type = serv->flags & (SERV_HAS_DOMAIN | SERV_USE_RESOLV | SERV_NO_REBIND); | |
184 | *domain = serv->domain; | |
185 | matchlen = domainlen; | |
186 | if (serv->flags & SERV_NO_ADDR) | |
187 | flags = F_NXDOMAIN; | |
188 | else if (serv->flags & SERV_LITERAL_ADDRESS) | |
189 | { | |
190 | if (sflag & qtype) | |
191 | { | |
192 | flags = sflag; | |
193 | if (serv->addr.sa.sa_family == AF_INET) | |
194 | *addrpp = (struct all_addr *)&serv->addr.in.sin_addr; | |
195 | #ifdef HAVE_IPV6 | |
196 | else | |
197 | *addrpp = (struct all_addr *)&serv->addr.in6.sin6_addr; | |
198 | #endif | |
199 | } | |
200 | else if (!flags || (flags & F_NXDOMAIN)) | |
201 | flags = F_NOERR; | |
202 | } | |
203 | else | |
204 | flags = 0; | |
205 | } | |
206 | } | |
207 | } | |
208 | } | |
209 | ||
210 | if (flags == 0 && !(qtype & F_QUERY) && | |
211 | option_bool(OPT_NODOTS_LOCAL) && !strchr(qdomain, '.') && namelen != 0) | |
212 | /* don't forward A or AAAA queries for simple names, except the empty name */ | |
213 | flags = F_NOERR; | |
214 | ||
215 | if (flags == F_NXDOMAIN && check_for_local_domain(qdomain, now)) | |
216 | flags = F_NOERR; | |
217 | ||
218 | if (flags) | |
219 | { | |
220 | int logflags = 0; | |
221 | ||
222 | if (flags == F_NXDOMAIN || flags == F_NOERR) | |
223 | logflags = F_NEG | qtype; | |
224 | ||
225 | log_query(logflags | flags | F_CONFIG | F_FORWARD, qdomain, *addrpp, NULL); | |
226 | } | |
227 | else if ((*type) & SERV_USE_RESOLV) | |
228 | { | |
229 | *type = 0; /* use normal servers for this domain */ | |
230 | *domain = NULL; | |
231 | } | |
232 | return flags; | |
233 | } | |
234 | ||
235 | static int forward_query(int udpfd, union mysockaddr *udpaddr, | |
236 | struct all_addr *dst_addr, unsigned int dst_iface, | |
237 | struct dns_header *header, size_t plen, time_t now, struct frec *forward) | |
238 | { | |
239 | char *domain = NULL; | |
240 | int type = 0, norebind = 0; | |
241 | struct all_addr *addrp = NULL; | |
242 | unsigned int crc = questions_crc(header, plen, daemon->namebuff); | |
243 | unsigned int flags = 0; | |
244 | unsigned int gotname = extract_request(header, plen, daemon->namebuff, NULL); | |
245 | struct server *start = NULL; | |
246 | ||
247 | /* RFC 4035: sect 4.6 para 2 */ | |
248 | header->hb4 &= ~HB4_AD; | |
249 | ||
250 | /* may be no servers available. */ | |
251 | if (!daemon->servers) | |
252 | forward = NULL; | |
253 | else if (forward || (forward = lookup_frec_by_sender(ntohs(header->id), udpaddr, crc))) | |
254 | { | |
255 | /* retry on existing query, send to all available servers */ | |
256 | domain = forward->sentto->domain; | |
257 | forward->sentto->failed_queries++; | |
258 | if (!option_bool(OPT_ORDER)) | |
259 | { | |
260 | forward->forwardall = 1; | |
261 | daemon->last_server = NULL; | |
262 | } | |
263 | type = forward->sentto->flags & SERV_TYPE; | |
264 | if (!(start = forward->sentto->next)) | |
265 | start = daemon->servers; /* at end of list, recycle */ | |
266 | header->id = htons(forward->new_id); | |
267 | } | |
268 | else | |
269 | { | |
270 | if (gotname) | |
271 | flags = search_servers(now, &addrp, gotname, daemon->namebuff, &type, &domain, &norebind); | |
272 | ||
273 | if (!flags && !(forward = get_new_frec(now, NULL))) | |
274 | /* table full - server failure. */ | |
275 | flags = F_NEG; | |
276 | ||
277 | if (forward) | |
278 | { | |
279 | forward->source = *udpaddr; | |
280 | forward->dest = *dst_addr; | |
281 | forward->iface = dst_iface; | |
282 | forward->orig_id = ntohs(header->id); | |
283 | forward->new_id = get_id(crc); | |
284 | forward->fd = udpfd; | |
285 | forward->crc = crc; | |
286 | forward->forwardall = 0; | |
287 | if (norebind) | |
288 | forward->flags |= FREC_NOREBIND; | |
289 | if (header->hb4 & HB4_CD) | |
290 | forward->flags |= FREC_CHECKING_DISABLED; | |
291 | ||
292 | header->id = htons(forward->new_id); | |
293 | ||
294 | /* In strict_order mode, always try servers in the order | |
295 | specified in resolv.conf, if a domain is given | |
296 | always try all the available servers, | |
297 | otherwise, use the one last known to work. */ | |
298 | ||
299 | if (type == 0) | |
300 | { | |
301 | if (option_bool(OPT_ORDER)) | |
302 | start = daemon->servers; | |
303 | else if (!(start = daemon->last_server) || | |
304 | daemon->forwardcount++ > FORWARD_TEST || | |
305 | difftime(now, daemon->forwardtime) > FORWARD_TIME) | |
306 | { | |
307 | start = daemon->servers; | |
308 | forward->forwardall = 1; | |
309 | daemon->forwardcount = 0; | |
310 | daemon->forwardtime = now; | |
311 | } | |
312 | } | |
313 | else | |
314 | { | |
315 | start = daemon->servers; | |
316 | if (!option_bool(OPT_ORDER)) | |
317 | forward->forwardall = 1; | |
318 | } | |
319 | } | |
320 | } | |
321 | ||
322 | /* check for send errors here (no route to host) | |
323 | if we fail to send to all nameservers, send back an error | |
324 | packet straight away (helps modem users when offline) */ | |
325 | ||
326 | if (!flags && forward) | |
327 | { | |
328 | struct server *firstsentto = start; | |
329 | int forwarded = 0; | |
330 | ||
331 | if (option_bool(OPT_ADD_MAC)) | |
332 | plen = add_mac(header, plen, ((char *) header) + PACKETSZ, &forward->source); | |
333 | ||
334 | while (1) | |
335 | { | |
336 | /* only send to servers dealing with our domain. | |
337 | domain may be NULL, in which case server->domain | |
338 | must be NULL also. */ | |
339 | ||
340 | if (type == (start->flags & SERV_TYPE) && | |
341 | (type != SERV_HAS_DOMAIN || hostname_isequal(domain, start->domain)) && | |
342 | !(start->flags & SERV_LITERAL_ADDRESS)) | |
343 | { | |
344 | int fd; | |
345 | ||
346 | /* find server socket to use, may need to get random one. */ | |
347 | if (start->sfd) | |
348 | fd = start->sfd->fd; | |
349 | else | |
350 | { | |
351 | #ifdef HAVE_IPV6 | |
352 | if (start->addr.sa.sa_family == AF_INET6) | |
353 | { | |
354 | if (!forward->rfd6 && | |
355 | !(forward->rfd6 = allocate_rfd(AF_INET6))) | |
356 | break; | |
357 | daemon->rfd_save = forward->rfd6; | |
358 | fd = forward->rfd6->fd; | |
359 | } | |
360 | else | |
361 | #endif | |
362 | { | |
363 | if (!forward->rfd4 && | |
364 | !(forward->rfd4 = allocate_rfd(AF_INET))) | |
365 | break; | |
366 | daemon->rfd_save = forward->rfd4; | |
367 | fd = forward->rfd4->fd; | |
368 | } | |
369 | ||
370 | #ifdef HAVE_CONNTRACK | |
371 | /* Copy connection mark of incoming query to outgoing connection. */ | |
372 | if (option_bool(OPT_CONNTRACK)) | |
373 | { | |
374 | unsigned int mark; | |
375 | if (get_incoming_mark(&forward->source, &forward->dest, 0, &mark)) | |
376 | setsockopt(fd, SOL_SOCKET, SO_MARK, &mark, sizeof(unsigned int)); | |
377 | } | |
378 | #endif | |
379 | } | |
380 | ||
381 | if (sendto(fd, (char *)header, plen, 0, | |
382 | &start->addr.sa, | |
383 | sa_len(&start->addr)) == -1) | |
384 | { | |
385 | if (retry_send()) | |
386 | continue; | |
387 | } | |
388 | else | |
389 | { | |
390 | /* Keep info in case we want to re-send this packet */ | |
391 | daemon->srv_save = start; | |
392 | daemon->packet_len = plen; | |
393 | ||
394 | if (!gotname) | |
395 | strcpy(daemon->namebuff, "query"); | |
396 | if (start->addr.sa.sa_family == AF_INET) | |
397 | log_query(F_SERVER | F_IPV4 | F_FORWARD, daemon->namebuff, | |
398 | (struct all_addr *)&start->addr.in.sin_addr, NULL); | |
399 | #ifdef HAVE_IPV6 | |
400 | else | |
401 | log_query(F_SERVER | F_IPV6 | F_FORWARD, daemon->namebuff, | |
402 | (struct all_addr *)&start->addr.in6.sin6_addr, NULL); | |
403 | #endif | |
404 | start->queries++; | |
405 | forwarded = 1; | |
406 | forward->sentto = start; | |
407 | if (!forward->forwardall) | |
408 | break; | |
409 | forward->forwardall++; | |
410 | } | |
411 | } | |
412 | ||
413 | if (!(start = start->next)) | |
414 | start = daemon->servers; | |
415 | ||
416 | if (start == firstsentto) | |
417 | break; | |
418 | } | |
419 | ||
420 | if (forwarded) | |
421 | return 1; | |
422 | ||
423 | /* could not send on, prepare to return */ | |
424 | header->id = htons(forward->orig_id); | |
425 | free_frec(forward); /* cancel */ | |
426 | } | |
427 | ||
428 | /* could not send on, return empty answer or address if known for whole domain */ | |
429 | if (udpfd != -1) | |
430 | { | |
431 | plen = setup_reply(header, plen, addrp, flags, daemon->local_ttl); | |
432 | send_from(udpfd, option_bool(OPT_NOWILD) || option_bool(OPT_CLEVERBIND), (char *)header, plen, udpaddr, dst_addr, dst_iface); | |
433 | } | |
434 | ||
435 | return 0; | |
436 | } | |
437 | ||
438 | static size_t process_reply(struct dns_header *header, time_t now, | |
439 | struct server *server, size_t n, int check_rebind, int checking_disabled) | |
440 | { | |
441 | unsigned char *pheader, *sizep; | |
442 | char **sets = 0; | |
443 | int munged = 0, is_sign; | |
444 | size_t plen; | |
445 | ||
446 | #ifdef HAVE_IPSET | |
447 | /* Similar algorithm to search_servers. */ | |
448 | struct ipsets *ipset_pos; | |
449 | unsigned int namelen = strlen(daemon->namebuff); | |
450 | unsigned int matchlen = 0; | |
451 | for (ipset_pos = daemon->ipsets; ipset_pos; ipset_pos = ipset_pos->next) | |
452 | { | |
453 | unsigned int domainlen = strlen(ipset_pos->domain); | |
454 | char *matchstart = daemon->namebuff + namelen - domainlen; | |
455 | if (namelen >= domainlen && hostname_isequal(matchstart, ipset_pos->domain) && | |
456 | (domainlen == 0 || namelen == domainlen || *(matchstart - 1) == '.' ) && | |
457 | domainlen >= matchlen) { | |
458 | matchlen = domainlen; | |
459 | sets = ipset_pos->sets; | |
460 | } | |
461 | } | |
462 | #endif | |
463 | ||
464 | /* If upstream is advertising a larger UDP packet size | |
465 | than we allow, trim it so that we don't get overlarge | |
466 | requests for the client. We can't do this for signed packets. */ | |
467 | ||
468 | if ((pheader = find_pseudoheader(header, n, &plen, &sizep, &is_sign)) && !is_sign) | |
469 | { | |
470 | unsigned short udpsz; | |
471 | unsigned char *psave = sizep; | |
472 | ||
473 | GETSHORT(udpsz, sizep); | |
474 | if (udpsz > daemon->edns_pktsz) | |
475 | PUTSHORT(daemon->edns_pktsz, psave); | |
476 | } | |
477 | ||
478 | /* RFC 4035 sect 4.6 para 3 */ | |
479 | if (!is_sign && !option_bool(OPT_DNSSEC)) | |
480 | header->hb4 &= ~HB4_AD; | |
481 | ||
482 | if (OPCODE(header) != QUERY || (RCODE(header) != NOERROR && RCODE(header) != NXDOMAIN)) | |
483 | return n; | |
484 | ||
485 | /* Complain loudly if the upstream server is non-recursive. */ | |
486 | if (!(header->hb4 & HB4_RA) && RCODE(header) == NOERROR && ntohs(header->ancount) == 0 && | |
487 | server && !(server->flags & SERV_WARNED_RECURSIVE)) | |
488 | { | |
489 | prettyprint_addr(&server->addr, daemon->namebuff); | |
490 | my_syslog(LOG_WARNING, _("nameserver %s refused to do a recursive query"), daemon->namebuff); | |
491 | if (!option_bool(OPT_LOG)) | |
492 | server->flags |= SERV_WARNED_RECURSIVE; | |
493 | } | |
494 | ||
495 | if (daemon->bogus_addr && RCODE(header) != NXDOMAIN && | |
496 | check_for_bogus_wildcard(header, n, daemon->namebuff, daemon->bogus_addr, now)) | |
497 | { | |
498 | munged = 1; | |
499 | SET_RCODE(header, NXDOMAIN); | |
500 | header->hb3 &= ~HB3_AA; | |
501 | } | |
502 | else | |
503 | { | |
504 | if (RCODE(header) == NXDOMAIN && | |
505 | extract_request(header, n, daemon->namebuff, NULL) && | |
506 | check_for_local_domain(daemon->namebuff, now)) | |
507 | { | |
508 | /* if we forwarded a query for a locally known name (because it was for | |
509 | an unknown type) and the answer is NXDOMAIN, convert that to NODATA, | |
510 | since we know that the domain exists, even if upstream doesn't */ | |
511 | munged = 1; | |
512 | header->hb3 |= HB3_AA; | |
513 | SET_RCODE(header, NOERROR); | |
514 | } | |
515 | ||
516 | if (extract_addresses(header, n, daemon->namebuff, now, sets, is_sign, check_rebind, checking_disabled)) | |
517 | { | |
518 | my_syslog(LOG_WARNING, _("possible DNS-rebind attack detected: %s"), daemon->namebuff); | |
519 | munged = 1; | |
520 | } | |
521 | } | |
522 | ||
523 | /* do this after extract_addresses. Ensure NODATA reply and remove | |
524 | nameserver info. */ | |
525 | ||
526 | if (munged) | |
527 | { | |
528 | header->ancount = htons(0); | |
529 | header->nscount = htons(0); | |
530 | header->arcount = htons(0); | |
531 | } | |
532 | ||
533 | /* the bogus-nxdomain stuff, doctor and NXDOMAIN->NODATA munging can all elide | |
534 | sections of the packet. Find the new length here and put back pseudoheader | |
535 | if it was removed. */ | |
536 | return resize_packet(header, n, pheader, plen); | |
537 | } | |
538 | ||
539 | /* sets new last_server */ | |
540 | void reply_query(int fd, int family, time_t now) | |
541 | { | |
542 | /* packet from peer server, extract data for cache, and send to | |
543 | original requester */ | |
544 | struct dns_header *header; | |
545 | union mysockaddr serveraddr; | |
546 | struct frec *forward; | |
547 | socklen_t addrlen = sizeof(serveraddr); | |
548 | ssize_t n = recvfrom(fd, daemon->packet, daemon->edns_pktsz, 0, &serveraddr.sa, &addrlen); | |
549 | size_t nn; | |
550 | struct server *server; | |
551 | ||
552 | /* packet buffer overwritten */ | |
553 | daemon->srv_save = NULL; | |
554 | ||
555 | /* Determine the address of the server replying so that we can mark that as good */ | |
556 | serveraddr.sa.sa_family = family; | |
557 | #ifdef HAVE_IPV6 | |
558 | if (serveraddr.sa.sa_family == AF_INET6) | |
559 | serveraddr.in6.sin6_flowinfo = 0; | |
560 | #endif | |
561 | ||
562 | /* spoof check: answer must come from known server, */ | |
563 | for (server = daemon->servers; server; server = server->next) | |
564 | if (!(server->flags & (SERV_LITERAL_ADDRESS | SERV_NO_ADDR)) && | |
565 | sockaddr_isequal(&server->addr, &serveraddr)) | |
566 | break; | |
567 | ||
568 | header = (struct dns_header *)daemon->packet; | |
569 | ||
570 | if (!server || | |
571 | n < (int)sizeof(struct dns_header) || !(header->hb3 & HB3_QR) || | |
572 | !(forward = lookup_frec(ntohs(header->id), questions_crc(header, n, daemon->namebuff)))) | |
573 | return; | |
574 | ||
575 | server = forward->sentto; | |
576 | ||
577 | if ((RCODE(header) == SERVFAIL || RCODE(header) == REFUSED) && | |
578 | !option_bool(OPT_ORDER) && | |
579 | forward->forwardall == 0) | |
580 | /* for broken servers, attempt to send to another one. */ | |
581 | { | |
582 | unsigned char *pheader; | |
583 | size_t plen; | |
584 | int is_sign; | |
585 | ||
586 | /* recreate query from reply */ | |
587 | pheader = find_pseudoheader(header, (size_t)n, &plen, NULL, &is_sign); | |
588 | if (!is_sign) | |
589 | { | |
590 | header->ancount = htons(0); | |
591 | header->nscount = htons(0); | |
592 | header->arcount = htons(0); | |
593 | if ((nn = resize_packet(header, (size_t)n, pheader, plen))) | |
594 | { | |
595 | header->hb3 &= ~(HB3_QR | HB3_TC); | |
596 | forward_query(-1, NULL, NULL, 0, header, nn, now, forward); | |
597 | return; | |
598 | } | |
599 | } | |
600 | } | |
601 | ||
602 | if ((forward->sentto->flags & SERV_TYPE) == 0) | |
603 | { | |
604 | if (RCODE(header) == SERVFAIL || RCODE(header) == REFUSED) | |
605 | server = NULL; | |
606 | else | |
607 | { | |
608 | struct server *last_server; | |
609 | ||
610 | /* find good server by address if possible, otherwise assume the last one we sent to */ | |
611 | for (last_server = daemon->servers; last_server; last_server = last_server->next) | |
612 | if (!(last_server->flags & (SERV_LITERAL_ADDRESS | SERV_HAS_DOMAIN | SERV_FOR_NODOTS | SERV_NO_ADDR)) && | |
613 | sockaddr_isequal(&last_server->addr, &serveraddr)) | |
614 | { | |
615 | server = last_server; | |
616 | break; | |
617 | } | |
618 | } | |
619 | if (!option_bool(OPT_ALL_SERVERS)) | |
620 | daemon->last_server = server; | |
621 | } | |
622 | ||
623 | /* If the answer is an error, keep the forward record in place in case | |
624 | we get a good reply from another server. Kill it when we've | |
625 | had replies from all to avoid filling the forwarding table when | |
626 | everything is broken */ | |
627 | if (forward->forwardall == 0 || --forward->forwardall == 1 || | |
628 | (RCODE(header) != REFUSED && RCODE(header) != SERVFAIL)) | |
629 | { | |
630 | int check_rebind = !(forward->flags & FREC_NOREBIND); | |
631 | ||
632 | if (!option_bool(OPT_NO_REBIND)) | |
633 | check_rebind = 0; | |
634 | ||
635 | if ((nn = process_reply(header, now, server, (size_t)n, check_rebind, forward->flags & FREC_CHECKING_DISABLED))) | |
636 | { | |
637 | header->id = htons(forward->orig_id); | |
638 | header->hb4 |= HB4_RA; /* recursion if available */ | |
639 | send_from(forward->fd, option_bool(OPT_NOWILD) || option_bool (OPT_CLEVERBIND), daemon->packet, nn, | |
640 | &forward->source, &forward->dest, forward->iface); | |
641 | } | |
642 | free_frec(forward); /* cancel */ | |
643 | } | |
644 | } | |
645 | ||
646 | ||
647 | void receive_query(struct listener *listen, time_t now) | |
648 | { | |
649 | struct dns_header *header = (struct dns_header *)daemon->packet; | |
650 | union mysockaddr source_addr; | |
651 | unsigned short type; | |
652 | struct all_addr dst_addr; | |
653 | struct in_addr netmask, dst_addr_4; | |
654 | size_t m; | |
655 | ssize_t n; | |
656 | int if_index = 0; | |
657 | int auth_dns = 0; | |
658 | struct iovec iov[1]; | |
659 | struct msghdr msg; | |
660 | struct cmsghdr *cmptr; | |
661 | union { | |
662 | struct cmsghdr align; /* this ensures alignment */ | |
663 | #ifdef HAVE_IPV6 | |
664 | char control6[CMSG_SPACE(sizeof(struct in6_pktinfo))]; | |
665 | #endif | |
666 | #if defined(HAVE_LINUX_NETWORK) | |
667 | char control[CMSG_SPACE(sizeof(struct in_pktinfo))]; | |
668 | #elif defined(IP_RECVDSTADDR) && defined(HAVE_SOLARIS_NETWORK) | |
669 | char control[CMSG_SPACE(sizeof(struct in_addr)) + | |
670 | CMSG_SPACE(sizeof(unsigned int))]; | |
671 | #elif defined(IP_RECVDSTADDR) | |
672 | char control[CMSG_SPACE(sizeof(struct in_addr)) + | |
673 | CMSG_SPACE(sizeof(struct sockaddr_dl))]; | |
674 | #endif | |
675 | } control_u; | |
676 | ||
677 | /* packet buffer overwritten */ | |
678 | daemon->srv_save = NULL; | |
679 | ||
680 | dst_addr_4.s_addr = 0; | |
681 | netmask.s_addr = 0; | |
682 | ||
683 | if (option_bool(OPT_NOWILD) && listen->iface) | |
684 | { | |
685 | auth_dns = listen->iface->dns_auth; | |
686 | ||
687 | if (listen->family == AF_INET) | |
688 | { | |
689 | dst_addr_4 = listen->iface->addr.in.sin_addr; | |
690 | netmask = listen->iface->netmask; | |
691 | } | |
692 | } | |
693 | ||
694 | iov[0].iov_base = daemon->packet; | |
695 | iov[0].iov_len = daemon->edns_pktsz; | |
696 | ||
697 | msg.msg_control = control_u.control; | |
698 | msg.msg_controllen = sizeof(control_u); | |
699 | msg.msg_flags = 0; | |
700 | msg.msg_name = &source_addr; | |
701 | msg.msg_namelen = sizeof(source_addr); | |
702 | msg.msg_iov = iov; | |
703 | msg.msg_iovlen = 1; | |
704 | ||
705 | if ((n = recvmsg(listen->fd, &msg, 0)) == -1) | |
706 | return; | |
707 | ||
708 | if (n < (int)sizeof(struct dns_header) || | |
709 | (msg.msg_flags & MSG_TRUNC) || | |
710 | (header->hb3 & HB3_QR)) | |
711 | return; | |
712 | ||
713 | source_addr.sa.sa_family = listen->family; | |
714 | #ifdef HAVE_IPV6 | |
715 | if (listen->family == AF_INET6) | |
716 | source_addr.in6.sin6_flowinfo = 0; | |
717 | #endif | |
718 | ||
719 | if (!option_bool(OPT_NOWILD)) | |
720 | { | |
721 | struct ifreq ifr; | |
722 | ||
723 | if (msg.msg_controllen < sizeof(struct cmsghdr)) | |
724 | return; | |
725 | ||
726 | #if defined(HAVE_LINUX_NETWORK) | |
727 | if (listen->family == AF_INET) | |
728 | for (cmptr = CMSG_FIRSTHDR(&msg); cmptr; cmptr = CMSG_NXTHDR(&msg, cmptr)) | |
729 | if (cmptr->cmsg_level == IPPROTO_IP && cmptr->cmsg_type == IP_PKTINFO) | |
730 | { | |
731 | union { | |
732 | unsigned char *c; | |
733 | struct in_pktinfo *p; | |
734 | } p; | |
735 | p.c = CMSG_DATA(cmptr); | |
736 | dst_addr_4 = dst_addr.addr.addr4 = p.p->ipi_spec_dst; | |
737 | if_index = p.p->ipi_ifindex; | |
738 | } | |
739 | #elif defined(IP_RECVDSTADDR) && defined(IP_RECVIF) | |
740 | if (listen->family == AF_INET) | |
741 | { | |
742 | for (cmptr = CMSG_FIRSTHDR(&msg); cmptr; cmptr = CMSG_NXTHDR(&msg, cmptr)) | |
743 | { | |
744 | union { | |
745 | unsigned char *c; | |
746 | unsigned int *i; | |
747 | struct in_addr *a; | |
748 | #ifndef HAVE_SOLARIS_NETWORK | |
749 | struct sockaddr_dl *s; | |
750 | #endif | |
751 | } p; | |
752 | p.c = CMSG_DATA(cmptr); | |
753 | if (cmptr->cmsg_level == IPPROTO_IP && cmptr->cmsg_type == IP_RECVDSTADDR) | |
754 | dst_addr_4 = dst_addr.addr.addr4 = *(p.a); | |
755 | else if (cmptr->cmsg_level == IPPROTO_IP && cmptr->cmsg_type == IP_RECVIF) | |
756 | #ifdef HAVE_SOLARIS_NETWORK | |
757 | if_index = *(p.i); | |
758 | #else | |
759 | if_index = p.s->sdl_index; | |
760 | #endif | |
761 | } | |
762 | } | |
763 | #endif | |
764 | ||
765 | #ifdef HAVE_IPV6 | |
766 | if (listen->family == AF_INET6) | |
767 | { | |
768 | for (cmptr = CMSG_FIRSTHDR(&msg); cmptr; cmptr = CMSG_NXTHDR(&msg, cmptr)) | |
769 | if (cmptr->cmsg_level == IPPROTO_IPV6 && cmptr->cmsg_type == daemon->v6pktinfo) | |
770 | { | |
771 | union { | |
772 | unsigned char *c; | |
773 | struct in6_pktinfo *p; | |
774 | } p; | |
775 | p.c = CMSG_DATA(cmptr); | |
776 | ||
777 | dst_addr.addr.addr6 = p.p->ipi6_addr; | |
778 | if_index = p.p->ipi6_ifindex; | |
779 | } | |
780 | } | |
781 | #endif | |
782 | ||
783 | /* enforce available interface configuration */ | |
784 | ||
785 | if (!indextoname(listen->fd, if_index, ifr.ifr_name)) | |
786 | return; | |
787 | ||
788 | if (!iface_check(listen->family, &dst_addr, ifr.ifr_name, &auth_dns)) | |
789 | { | |
790 | if (!option_bool(OPT_CLEVERBIND)) | |
791 | enumerate_interfaces(0); | |
792 | if (!loopback_exception(listen->fd, listen->family, &dst_addr, ifr.ifr_name) && | |
793 | !label_exception(if_index, listen->family, &dst_addr)) | |
794 | return; | |
795 | } | |
796 | ||
797 | if (listen->family == AF_INET && option_bool(OPT_LOCALISE)) | |
798 | { | |
799 | struct irec *iface; | |
800 | ||
801 | /* get the netmask of the interface whch has the address we were sent to. | |
802 | This is no neccessarily the interface we arrived on. */ | |
803 | ||
804 | for (iface = daemon->interfaces; iface; iface = iface->next) | |
805 | if (iface->addr.sa.sa_family == AF_INET && | |
806 | iface->addr.in.sin_addr.s_addr == dst_addr_4.s_addr) | |
807 | break; | |
808 | ||
809 | /* interface may be new */ | |
810 | if (!iface && !option_bool(OPT_CLEVERBIND)) | |
811 | enumerate_interfaces(0); | |
812 | ||
813 | for (iface = daemon->interfaces; iface; iface = iface->next) | |
814 | if (iface->addr.sa.sa_family == AF_INET && | |
815 | iface->addr.in.sin_addr.s_addr == dst_addr_4.s_addr) | |
816 | break; | |
817 | ||
818 | /* If we failed, abandon localisation */ | |
819 | if (iface) | |
820 | netmask = iface->netmask; | |
821 | else | |
822 | dst_addr_4.s_addr = 0; | |
823 | } | |
824 | } | |
825 | ||
826 | if (extract_request(header, (size_t)n, daemon->namebuff, &type)) | |
827 | { | |
828 | char types[20]; | |
829 | ||
830 | querystr(auth_dns ? "auth" : "query", types, type); | |
831 | ||
832 | if (listen->family == AF_INET) | |
833 | log_query(F_QUERY | F_IPV4 | F_FORWARD, daemon->namebuff, | |
834 | (struct all_addr *)&source_addr.in.sin_addr, types); | |
835 | #ifdef HAVE_IPV6 | |
836 | else | |
837 | log_query(F_QUERY | F_IPV6 | F_FORWARD, daemon->namebuff, | |
838 | (struct all_addr *)&source_addr.in6.sin6_addr, types); | |
839 | #endif | |
840 | } | |
841 | ||
842 | #ifdef HAVE_AUTH | |
843 | if (auth_dns) | |
844 | { | |
845 | m = answer_auth(header, ((char *) header) + PACKETSZ, (size_t)n, now, &source_addr); | |
846 | if (m >= 1) | |
847 | send_from(listen->fd, option_bool(OPT_NOWILD) || option_bool(OPT_CLEVERBIND), | |
848 | (char *)header, m, &source_addr, &dst_addr, if_index); | |
849 | } | |
850 | else | |
851 | #endif | |
852 | { | |
853 | m = answer_request(header, ((char *) header) + PACKETSZ, (size_t)n, | |
854 | dst_addr_4, netmask, now); | |
855 | ||
856 | if (m >= 1) | |
857 | { | |
858 | send_from(listen->fd, option_bool(OPT_NOWILD) || option_bool(OPT_CLEVERBIND), | |
859 | (char *)header, m, &source_addr, &dst_addr, if_index); | |
860 | daemon->local_answer++; | |
861 | } | |
862 | else if (forward_query(listen->fd, &source_addr, &dst_addr, if_index, | |
863 | header, (size_t)n, now, NULL)) | |
864 | daemon->queries_forwarded++; | |
865 | else | |
866 | daemon->local_answer++; | |
867 | } | |
868 | } | |
869 | ||
870 | /* The daemon forks before calling this: it should deal with one connection, | |
871 | blocking as neccessary, and then return. Note, need to be a bit careful | |
872 | about resources for debug mode, when the fork is suppressed: that's | |
873 | done by the caller. */ | |
874 | unsigned char *tcp_request(int confd, time_t now, | |
875 | union mysockaddr *local_addr, struct in_addr netmask, int auth_dns) | |
876 | { | |
877 | size_t size = 0; | |
878 | int norebind = 0; | |
879 | int checking_disabled; | |
880 | size_t m; | |
881 | unsigned short qtype; | |
882 | unsigned int gotname; | |
883 | unsigned char c1, c2; | |
884 | /* Max TCP packet + slop + size */ | |
885 | unsigned char *packet = whine_malloc(65536 + MAXDNAME + RRFIXEDSZ + sizeof(u16)); | |
886 | unsigned char *payload = &packet[2]; | |
887 | /* largest field in header is 16-bits, so this is still sufficiently aligned */ | |
888 | struct dns_header *header = (struct dns_header *)payload; | |
889 | u16 *length = (u16 *)packet; | |
890 | struct server *last_server; | |
891 | struct in_addr dst_addr_4; | |
892 | union mysockaddr peer_addr; | |
893 | socklen_t peer_len = sizeof(union mysockaddr); | |
894 | ||
895 | if (getpeername(confd, (struct sockaddr *)&peer_addr, &peer_len) == -1) | |
896 | return packet; | |
897 | ||
898 | while (1) | |
899 | { | |
900 | if (!packet || | |
901 | !read_write(confd, &c1, 1, 1) || !read_write(confd, &c2, 1, 1) || | |
902 | !(size = c1 << 8 | c2) || | |
903 | !read_write(confd, payload, size, 1)) | |
904 | return packet; | |
905 | ||
906 | if (size < (int)sizeof(struct dns_header)) | |
907 | continue; | |
908 | ||
909 | /* save state of "cd" flag in query */ | |
910 | checking_disabled = header->hb4 & HB4_CD; | |
911 | ||
912 | /* RFC 4035: sect 4.6 para 2 */ | |
913 | header->hb4 &= ~HB4_AD; | |
914 | ||
915 | if ((gotname = extract_request(header, (unsigned int)size, daemon->namebuff, &qtype))) | |
916 | { | |
917 | char types[20]; | |
918 | ||
919 | querystr(auth_dns ? "auth" : "query", types, qtype); | |
920 | ||
921 | if (peer_addr.sa.sa_family == AF_INET) | |
922 | log_query(F_QUERY | F_IPV4 | F_FORWARD, daemon->namebuff, | |
923 | (struct all_addr *)&peer_addr.in.sin_addr, types); | |
924 | #ifdef HAVE_IPV6 | |
925 | else | |
926 | log_query(F_QUERY | F_IPV6 | F_FORWARD, daemon->namebuff, | |
927 | (struct all_addr *)&peer_addr.in6.sin6_addr, types); | |
928 | #endif | |
929 | } | |
930 | ||
931 | if (local_addr->sa.sa_family == AF_INET) | |
932 | dst_addr_4 = local_addr->in.sin_addr; | |
933 | else | |
934 | dst_addr_4.s_addr = 0; | |
935 | ||
936 | #ifdef HAVE_AUTH | |
937 | if (auth_dns) | |
938 | m = answer_auth(header, ((char *) header) + 65536, (size_t)size, now, &peer_addr); | |
939 | else | |
940 | #endif | |
941 | { | |
942 | /* m > 0 if answered from cache */ | |
943 | m = answer_request(header, ((char *) header) + 65536, (size_t)size, | |
944 | dst_addr_4, netmask, now); | |
945 | ||
946 | /* Do this by steam now we're not in the select() loop */ | |
947 | check_log_writer(NULL); | |
948 | ||
949 | if (m == 0) | |
950 | { | |
951 | unsigned int flags = 0; | |
952 | struct all_addr *addrp = NULL; | |
953 | int type = 0; | |
954 | char *domain = NULL; | |
955 | ||
956 | if (option_bool(OPT_ADD_MAC)) | |
957 | size = add_mac(header, size, ((char *) header) + 65536, &peer_addr); | |
958 | ||
959 | if (gotname) | |
960 | flags = search_servers(now, &addrp, gotname, daemon->namebuff, &type, &domain, &norebind); | |
961 | ||
962 | if (type != 0 || option_bool(OPT_ORDER) || !daemon->last_server) | |
963 | last_server = daemon->servers; | |
964 | else | |
965 | last_server = daemon->last_server; | |
966 | ||
967 | if (!flags && last_server) | |
968 | { | |
969 | struct server *firstsendto = NULL; | |
970 | unsigned int crc = questions_crc(header, (unsigned int)size, daemon->namebuff); | |
971 | ||
972 | /* Loop round available servers until we succeed in connecting to one. | |
973 | Note that this code subtley ensures that consecutive queries on this connection | |
974 | which can go to the same server, do so. */ | |
975 | while (1) | |
976 | { | |
977 | if (!firstsendto) | |
978 | firstsendto = last_server; | |
979 | else | |
980 | { | |
981 | if (!(last_server = last_server->next)) | |
982 | last_server = daemon->servers; | |
983 | ||
984 | if (last_server == firstsendto) | |
985 | break; | |
986 | } | |
987 | ||
988 | /* server for wrong domain */ | |
989 | if (type != (last_server->flags & SERV_TYPE) || | |
990 | (type == SERV_HAS_DOMAIN && !hostname_isequal(domain, last_server->domain))) | |
991 | continue; | |
992 | ||
993 | if (last_server->tcpfd == -1) | |
994 | { | |
995 | if ((last_server->tcpfd = socket(last_server->addr.sa.sa_family, SOCK_STREAM, 0)) == -1) | |
996 | continue; | |
997 | ||
998 | if ((!local_bind(last_server->tcpfd, &last_server->source_addr, last_server->interface, 1) || | |
999 | connect(last_server->tcpfd, &last_server->addr.sa, sa_len(&last_server->addr)) == -1)) | |
1000 | { | |
1001 | close(last_server->tcpfd); | |
1002 | last_server->tcpfd = -1; | |
1003 | continue; | |
1004 | } | |
1005 | ||
1006 | #ifdef HAVE_CONNTRACK | |
1007 | /* Copy connection mark of incoming query to outgoing connection. */ | |
1008 | if (option_bool(OPT_CONNTRACK)) | |
1009 | { | |
1010 | unsigned int mark; | |
1011 | struct all_addr local; | |
1012 | #ifdef HAVE_IPV6 | |
1013 | if (local_addr->sa.sa_family == AF_INET6) | |
1014 | local.addr.addr6 = local_addr->in6.sin6_addr; | |
1015 | else | |
1016 | #endif | |
1017 | local.addr.addr4 = local_addr->in.sin_addr; | |
1018 | ||
1019 | if (get_incoming_mark(&peer_addr, &local, 1, &mark)) | |
1020 | setsockopt(last_server->tcpfd, SOL_SOCKET, SO_MARK, &mark, sizeof(unsigned int)); | |
1021 | } | |
1022 | #endif | |
1023 | } | |
1024 | ||
1025 | *length = htons(size); | |
1026 | ||
1027 | if (!read_write(last_server->tcpfd, packet, size + sizeof(u16), 0) || | |
1028 | !read_write(last_server->tcpfd, &c1, 1, 1) || | |
1029 | !read_write(last_server->tcpfd, &c2, 1, 1)) | |
1030 | { | |
1031 | close(last_server->tcpfd); | |
1032 | last_server->tcpfd = -1; | |
1033 | continue; | |
1034 | } | |
1035 | ||
1036 | m = (c1 << 8) | c2; | |
1037 | if (!read_write(last_server->tcpfd, payload, m, 1)) | |
1038 | return packet; | |
1039 | ||
1040 | if (!gotname) | |
1041 | strcpy(daemon->namebuff, "query"); | |
1042 | if (last_server->addr.sa.sa_family == AF_INET) | |
1043 | log_query(F_SERVER | F_IPV4 | F_FORWARD, daemon->namebuff, | |
1044 | (struct all_addr *)&last_server->addr.in.sin_addr, NULL); | |
1045 | #ifdef HAVE_IPV6 | |
1046 | else | |
1047 | log_query(F_SERVER | F_IPV6 | F_FORWARD, daemon->namebuff, | |
1048 | (struct all_addr *)&last_server->addr.in6.sin6_addr, NULL); | |
1049 | #endif | |
1050 | ||
1051 | /* There's no point in updating the cache, since this process will exit and | |
1052 | lose the information after a few queries. We make this call for the alias and | |
1053 | bogus-nxdomain side-effects. */ | |
1054 | /* If the crc of the question section doesn't match the crc we sent, then | |
1055 | someone might be attempting to insert bogus values into the cache by | |
1056 | sending replies containing questions and bogus answers. */ | |
1057 | if (crc == questions_crc(header, (unsigned int)m, daemon->namebuff)) | |
1058 | m = process_reply(header, now, last_server, (unsigned int)m, | |
1059 | option_bool(OPT_NO_REBIND) && !norebind, checking_disabled); | |
1060 | ||
1061 | break; | |
1062 | } | |
1063 | } | |
1064 | ||
1065 | /* In case of local answer or no connections made. */ | |
1066 | if (m == 0) | |
1067 | m = setup_reply(header, (unsigned int)size, addrp, flags, daemon->local_ttl); | |
1068 | } | |
1069 | } | |
1070 | ||
1071 | check_log_writer(NULL); | |
1072 | ||
1073 | *length = htons(m); | |
1074 | ||
1075 | if (m == 0 || !read_write(confd, packet, m + sizeof(u16), 0)) | |
1076 | return packet; | |
1077 | } | |
1078 | } | |
1079 | ||
1080 | static struct frec *allocate_frec(time_t now) | |
1081 | { | |
1082 | struct frec *f; | |
1083 | ||
1084 | if ((f = (struct frec *)whine_malloc(sizeof(struct frec)))) | |
1085 | { | |
1086 | f->next = daemon->frec_list; | |
1087 | f->time = now; | |
1088 | f->sentto = NULL; | |
1089 | f->rfd4 = NULL; | |
1090 | f->flags = 0; | |
1091 | #ifdef HAVE_IPV6 | |
1092 | f->rfd6 = NULL; | |
1093 | #endif | |
1094 | daemon->frec_list = f; | |
1095 | } | |
1096 | ||
1097 | return f; | |
1098 | } | |
1099 | ||
1100 | static struct randfd *allocate_rfd(int family) | |
1101 | { | |
1102 | static int finger = 0; | |
1103 | int i; | |
1104 | ||
1105 | /* limit the number of sockets we have open to avoid starvation of | |
1106 | (eg) TFTP. Once we have a reasonable number, randomness should be OK */ | |
1107 | ||
1108 | for (i = 0; i < RANDOM_SOCKS; i++) | |
1109 | if (daemon->randomsocks[i].refcount == 0) | |
1110 | { | |
1111 | if ((daemon->randomsocks[i].fd = random_sock(family)) == -1) | |
1112 | break; | |
1113 | ||
1114 | daemon->randomsocks[i].refcount = 1; | |
1115 | daemon->randomsocks[i].family = family; | |
1116 | return &daemon->randomsocks[i]; | |
1117 | } | |
1118 | ||
1119 | /* No free ones or cannot get new socket, grab an existing one */ | |
1120 | for (i = 0; i < RANDOM_SOCKS; i++) | |
1121 | { | |
1122 | int j = (i+finger) % RANDOM_SOCKS; | |
1123 | if (daemon->randomsocks[j].refcount != 0 && | |
1124 | daemon->randomsocks[j].family == family && | |
1125 | daemon->randomsocks[j].refcount != 0xffff) | |
1126 | { | |
1127 | finger = j; | |
1128 | daemon->randomsocks[j].refcount++; | |
1129 | return &daemon->randomsocks[j]; | |
1130 | } | |
1131 | } | |
1132 | ||
1133 | return NULL; /* doom */ | |
1134 | } | |
1135 | ||
1136 | static void free_frec(struct frec *f) | |
1137 | { | |
1138 | if (f->rfd4 && --(f->rfd4->refcount) == 0) | |
1139 | close(f->rfd4->fd); | |
1140 | ||
1141 | f->rfd4 = NULL; | |
1142 | f->sentto = NULL; | |
1143 | f->flags = 0; | |
1144 | ||
1145 | #ifdef HAVE_IPV6 | |
1146 | if (f->rfd6 && --(f->rfd6->refcount) == 0) | |
1147 | close(f->rfd6->fd); | |
1148 | ||
1149 | f->rfd6 = NULL; | |
1150 | #endif | |
1151 | } | |
1152 | ||
1153 | /* if wait==NULL return a free or older than TIMEOUT record. | |
1154 | else return *wait zero if one available, or *wait is delay to | |
1155 | when the oldest in-use record will expire. Impose an absolute | |
1156 | limit of 4*TIMEOUT before we wipe things (for random sockets) */ | |
1157 | struct frec *get_new_frec(time_t now, int *wait) | |
1158 | { | |
1159 | struct frec *f, *oldest, *target; | |
1160 | int count; | |
1161 | ||
1162 | if (wait) | |
1163 | *wait = 0; | |
1164 | ||
1165 | for (f = daemon->frec_list, oldest = NULL, target = NULL, count = 0; f; f = f->next, count++) | |
1166 | if (!f->sentto) | |
1167 | target = f; | |
1168 | else | |
1169 | { | |
1170 | if (difftime(now, f->time) >= 4*TIMEOUT) | |
1171 | { | |
1172 | free_frec(f); | |
1173 | target = f; | |
1174 | } | |
1175 | ||
1176 | if (!oldest || difftime(f->time, oldest->time) <= 0) | |
1177 | oldest = f; | |
1178 | } | |
1179 | ||
1180 | if (target) | |
1181 | { | |
1182 | target->time = now; | |
1183 | return target; | |
1184 | } | |
1185 | ||
1186 | /* can't find empty one, use oldest if there is one | |
1187 | and it's older than timeout */ | |
1188 | if (oldest && ((int)difftime(now, oldest->time)) >= TIMEOUT) | |
1189 | { | |
1190 | /* keep stuff for twice timeout if we can by allocating a new | |
1191 | record instead */ | |
1192 | if (difftime(now, oldest->time) < 2*TIMEOUT && | |
1193 | count <= daemon->ftabsize && | |
1194 | (f = allocate_frec(now))) | |
1195 | return f; | |
1196 | ||
1197 | if (!wait) | |
1198 | { | |
1199 | free_frec(oldest); | |
1200 | oldest->time = now; | |
1201 | } | |
1202 | return oldest; | |
1203 | } | |
1204 | ||
1205 | /* none available, calculate time 'till oldest record expires */ | |
1206 | if (count > daemon->ftabsize) | |
1207 | { | |
1208 | static time_t last_log = 0; | |
1209 | ||
1210 | if (oldest && wait) | |
1211 | *wait = oldest->time + (time_t)TIMEOUT - now; | |
1212 | ||
1213 | if ((int)difftime(now, last_log) > 5) | |
1214 | { | |
1215 | last_log = now; | |
1216 | my_syslog(LOG_WARNING, _("Maximum number of concurrent DNS queries reached (max: %d)"), daemon->ftabsize); | |
1217 | } | |
1218 | ||
1219 | return NULL; | |
1220 | } | |
1221 | ||
1222 | if (!(f = allocate_frec(now)) && wait) | |
1223 | /* wait one second on malloc failure */ | |
1224 | *wait = 1; | |
1225 | ||
1226 | return f; /* OK if malloc fails and this is NULL */ | |
1227 | } | |
1228 | ||
1229 | /* crc is all-ones if not known. */ | |
1230 | static struct frec *lookup_frec(unsigned short id, unsigned int crc) | |
1231 | { | |
1232 | struct frec *f; | |
1233 | ||
1234 | for(f = daemon->frec_list; f; f = f->next) | |
1235 | if (f->sentto && f->new_id == id && | |
1236 | (f->crc == crc || crc == 0xffffffff)) | |
1237 | return f; | |
1238 | ||
1239 | return NULL; | |
1240 | } | |
1241 | ||
1242 | static struct frec *lookup_frec_by_sender(unsigned short id, | |
1243 | union mysockaddr *addr, | |
1244 | unsigned int crc) | |
1245 | { | |
1246 | struct frec *f; | |
1247 | ||
1248 | for(f = daemon->frec_list; f; f = f->next) | |
1249 | if (f->sentto && | |
1250 | f->orig_id == id && | |
1251 | f->crc == crc && | |
1252 | sockaddr_isequal(&f->source, addr)) | |
1253 | return f; | |
1254 | ||
1255 | return NULL; | |
1256 | } | |
1257 | ||
1258 | /* A server record is going away, remove references to it */ | |
1259 | void server_gone(struct server *server) | |
1260 | { | |
1261 | struct frec *f; | |
1262 | ||
1263 | for (f = daemon->frec_list; f; f = f->next) | |
1264 | if (f->sentto && f->sentto == server) | |
1265 | free_frec(f); | |
1266 | ||
1267 | if (daemon->last_server == server) | |
1268 | daemon->last_server = NULL; | |
1269 | ||
1270 | if (daemon->srv_save == server) | |
1271 | daemon->srv_save = NULL; | |
1272 | } | |
1273 | ||
1274 | /* return unique random ids. */ | |
1275 | static unsigned short get_id(unsigned int crc) | |
1276 | { | |
1277 | unsigned short ret = 0; | |
1278 | ||
1279 | do | |
1280 | ret = rand16(); | |
1281 | while (lookup_frec(ret, crc)); | |
1282 | ||
1283 | return ret; | |
1284 | } | |
1285 | ||
1286 | ||
1287 | ||
1288 | ||
1289 |