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Commit | Line | Data |
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ed62c46b AC |
1 | /* |
2 | * A rewrite of Darren Reeds original res.c As there is nothing | |
3 | * left of Darrens original code, this is now licensed by the hybrid group. | |
4 | * (Well, some of the function names are the same, and bits of the structs..) | |
5 | * You can use it where it is useful, free even. Buy us a beer and stuff. | |
6 | * | |
7 | * The authors takes no responsibility for any damage or loss | |
8 | * of property which results from the use of this software. | |
9 | * | |
ed62c46b AC |
10 | * July 1999 - Rewrote a bunch of stuff here. Change hostent builder code, |
11 | * added callbacks and reference counting of returned hostents. | |
12 | * --Bleep (Thomas Helvey <tomh@inxpress.net>) | |
13 | * | |
14 | * This was all needlessly complicated for irc. Simplified. No more hostent | |
15 | * All we really care about is the IP -> hostname mappings. Thats all. | |
16 | * | |
17 | * Apr 28, 2003 --cryogen and Dianora | |
18 | * | |
19 | * DNS server flooding lessened, AAAA-or-A lookup removed, ip6.int support | |
20 | * removed, various robustness fixes | |
21 | * | |
22 | * 2006 --jilles and nenolod | |
23 | * | |
24 | * Resend queries to other servers if the DNS server replies with an error or | |
25 | * an invalid response. Also, avoid servers that return errors or invalid | |
26 | * responses. | |
27 | * | |
28 | * October 2012 --mr_flea | |
29 | * | |
30 | * ircd-ratbox changes for random IDs merged back in. | |
31 | * | |
32 | * January 2016 --kaniini | |
33 | */ | |
34 | ||
fe037171 | 35 | #include <rb_lib.h> |
ed62c46b AC |
36 | #include "setup.h" |
37 | #include "res.h" | |
38 | #include "reslib.h" | |
39 | ||
40 | #if (CHAR_BIT != 8) | |
41 | #error this code needs to be able to address individual octets | |
42 | #endif | |
43 | ||
44 | static PF res_readreply; | |
45 | ||
46 | #define MAXPACKET 1024 /* rfc sez 512 but we expand names so ... */ | |
ed62c46b AC |
47 | #define AR_TTL 600 /* TTL in seconds for dns cache entries */ |
48 | ||
49 | /* RFC 1104/1105 wasn't very helpful about what these fields | |
50 | * should be named, so for now, we'll just name them this way. | |
51 | * we probably should look at what named calls them or something. | |
52 | */ | |
53 | #define TYPE_SIZE (size_t)2 | |
54 | #define CLASS_SIZE (size_t)2 | |
55 | #define TTL_SIZE (size_t)4 | |
56 | #define RDLENGTH_SIZE (size_t)2 | |
57 | #define ANSWER_FIXED_SIZE (TYPE_SIZE + CLASS_SIZE + TTL_SIZE + RDLENGTH_SIZE) | |
58 | ||
59 | #ifdef RB_IPV6 | |
3f6cbacc | 60 | struct in6_addr ipv6_addr; |
ed62c46b | 61 | #endif |
3f6cbacc | 62 | struct in_addr ipv4_addr; |
ed62c46b AC |
63 | |
64 | struct reslist | |
65 | { | |
66 | rb_dlink_node node; | |
67 | int id; | |
68 | time_t ttl; | |
69 | char type; | |
70 | char queryname[IRCD_RES_HOSTLEN + 1]; /* name currently being queried */ | |
71 | char retries; /* retry counter */ | |
72 | char sends; /* number of sends (>1 means resent) */ | |
73 | time_t sentat; | |
74 | time_t timeout; | |
75 | int lastns; /* index of last server sent to */ | |
76 | struct rb_sockaddr_storage addr; | |
77 | char *name; | |
78 | struct DNSQuery *query; /* query callback for this request */ | |
79 | }; | |
80 | ||
81 | static rb_fde_t *res_fd; | |
82 | static rb_dlink_list request_list = { NULL, NULL, 0 }; | |
83 | static int ns_failure_count[IRCD_MAXNS]; /* timeouts and invalid/failed replies */ | |
84 | ||
85 | static void rem_request(struct reslist *request); | |
86 | static struct reslist *make_request(struct DNSQuery *query); | |
87 | static void gethost_byname_type_fqdn(const char *name, struct DNSQuery *query, | |
88 | int type); | |
89 | static void do_query_name(struct DNSQuery *query, const char *name, struct reslist *request, int); | |
90 | static void do_query_number(struct DNSQuery *query, const struct rb_sockaddr_storage *, | |
91 | struct reslist *request); | |
92 | static void query_name(struct reslist *request); | |
93 | static int send_res_msg(const char *buf, int len, int count); | |
94 | static void resend_query(struct reslist *request); | |
95 | static int check_question(struct reslist *request, HEADER * header, char *buf, char *eob); | |
96 | static int proc_answer(struct reslist *request, HEADER * header, char *, char *); | |
97 | static struct reslist *find_id(int id); | |
98 | static struct DNSReply *make_dnsreply(struct reslist *request); | |
ed62c46b AC |
99 | static uint16_t generate_random_id(void); |
100 | ||
ed62c46b AC |
101 | /* |
102 | * int | |
103 | * res_ourserver(inp) | |
104 | * looks up "inp" in irc_nsaddr_list[] | |
105 | * returns: | |
106 | * server ID or -1 for not found | |
107 | * author: | |
108 | * paul vixie, 29may94 | |
109 | * revised for ircd, cryogen(stu) may03 | |
110 | * slightly modified for charybdis, mr_flea oct12 | |
111 | */ | |
c99ae190 AC |
112 | static int |
113 | res_ourserver(const struct rb_sockaddr_storage *inp) | |
ed62c46b AC |
114 | { |
115 | #ifdef RB_IPV6 | |
116 | const struct sockaddr_in6 *v6; | |
117 | const struct sockaddr_in6 *v6in = (const struct sockaddr_in6 *)inp; | |
118 | #endif | |
119 | const struct sockaddr_in *v4; | |
120 | const struct sockaddr_in *v4in = (const struct sockaddr_in *)inp; | |
121 | int ns; | |
122 | ||
c99ae190 | 123 | for(ns = 0; ns < irc_nscount; ns++) |
ed62c46b AC |
124 | { |
125 | const struct rb_sockaddr_storage *srv = &irc_nsaddr_list[ns]; | |
ed62c46b AC |
126 | #ifdef RB_IPV6 |
127 | v6 = (const struct sockaddr_in6 *)srv; | |
128 | #endif | |
129 | v4 = (const struct sockaddr_in *)srv; | |
130 | ||
131 | /* could probably just memcmp(srv, inp, srv.ss_len) here | |
c99ae190 | 132 | * but we'll air on the side of caution - stu |
ed62c46b | 133 | */ |
c99ae190 | 134 | switch (GET_SS_FAMILY(srv)) |
ed62c46b AC |
135 | { |
136 | #ifdef RB_IPV6 | |
c99ae190 AC |
137 | case AF_INET6: |
138 | if(GET_SS_FAMILY(srv) == GET_SS_FAMILY(inp)) | |
139 | if(v6->sin6_port == v6in->sin6_port) | |
140 | if((memcmp(&v6->sin6_addr.s6_addr, &v6in->sin6_addr.s6_addr, | |
141 | sizeof(struct in6_addr)) == 0) || | |
142 | (memcmp(&v6->sin6_addr.s6_addr, &in6addr_any, | |
143 | sizeof(struct in6_addr)) == 0)) | |
144 | return 1; | |
145 | break; | |
ed62c46b | 146 | #endif |
c99ae190 AC |
147 | case AF_INET: |
148 | if(GET_SS_FAMILY(srv) == GET_SS_FAMILY(inp)) | |
149 | if(v4->sin_port == v4in->sin_port) | |
150 | if((v4->sin_addr.s_addr == INADDR_ANY) | |
151 | || (v4->sin_addr.s_addr == v4in->sin_addr.s_addr)) | |
152 | return 1; | |
153 | break; | |
154 | default: | |
155 | break; | |
ed62c46b AC |
156 | } |
157 | } | |
158 | ||
c99ae190 | 159 | return 0; |
ed62c46b AC |
160 | } |
161 | ||
162 | /* | |
163 | * timeout_query_list - Remove queries from the list which have been | |
164 | * there too long without being resolved. | |
165 | */ | |
166 | static time_t timeout_query_list(time_t now) | |
167 | { | |
168 | rb_dlink_node *ptr; | |
169 | rb_dlink_node *next_ptr; | |
170 | struct reslist *request; | |
171 | time_t next_time = 0; | |
172 | time_t timeout = 0; | |
173 | ||
174 | RB_DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head) | |
175 | { | |
176 | request = ptr->data; | |
177 | timeout = request->sentat + request->timeout; | |
178 | ||
179 | if (now >= timeout) | |
180 | { | |
181 | ns_failure_count[request->lastns]++; | |
182 | request->sentat = now; | |
183 | request->timeout += request->timeout; | |
184 | resend_query(request); | |
185 | } | |
186 | ||
187 | if ((next_time == 0) || timeout < next_time) | |
188 | { | |
189 | next_time = timeout; | |
190 | } | |
191 | } | |
192 | ||
193 | return (next_time > now) ? next_time : (now + AR_TTL); | |
194 | } | |
195 | ||
196 | /* | |
197 | * timeout_resolver - check request list | |
198 | */ | |
199 | static void timeout_resolver(void *notused) | |
200 | { | |
201 | timeout_query_list(rb_current_time()); | |
202 | } | |
203 | ||
204 | static struct ev_entry *timeout_resolver_ev = NULL; | |
205 | ||
206 | /* | |
207 | * start_resolver - do everything we need to read the resolv.conf file | |
208 | * and initialize the resolver file descriptor if needed | |
209 | */ | |
210 | static void start_resolver(void) | |
211 | { | |
212 | int i; | |
213 | ||
214 | irc_res_init(); | |
215 | for (i = 0; i < irc_nscount; i++) | |
216 | ns_failure_count[i] = 0; | |
217 | ||
218 | if (res_fd == NULL) | |
219 | { | |
c99ae190 | 220 | if ((res_fd = rb_socket(GET_SS_FAMILY(&irc_nsaddr_list[0]), SOCK_DGRAM, 0, |
ed62c46b AC |
221 | "UDP resolver socket")) == NULL) |
222 | return; | |
223 | ||
224 | /* At the moment, the resolver FD data is global .. */ | |
225 | rb_setselect(res_fd, RB_SELECT_READ, res_readreply, NULL); | |
226 | timeout_resolver_ev = rb_event_add("timeout_resolver", timeout_resolver, NULL, 1); | |
227 | } | |
228 | } | |
229 | ||
230 | /* | |
231 | * init_resolver - initialize resolver and resolver library | |
232 | */ | |
233 | void init_resolver(void) | |
234 | { | |
235 | #ifdef HAVE_SRAND48 | |
236 | srand48(rb_current_time()); | |
237 | #endif | |
238 | start_resolver(); | |
239 | } | |
240 | ||
241 | /* | |
242 | * restart_resolver - reread resolv.conf, reopen socket | |
243 | */ | |
244 | void restart_resolver(void) | |
245 | { | |
246 | rb_close(res_fd); | |
247 | res_fd = NULL; | |
248 | rb_event_delete(timeout_resolver_ev); /* -ddosen */ | |
249 | start_resolver(); | |
250 | } | |
251 | ||
252 | /* | |
253 | * add_local_domain - Add the domain to hostname, if it is missing | |
254 | * (as suggested by eps@TOASTER.SFSU.EDU) | |
255 | */ | |
856440bc | 256 | static void add_local_domain(char *hname, size_t size) |
ed62c46b AC |
257 | { |
258 | /* try to fix up unqualified names */ | |
259 | if (strchr(hname, '.') == NULL) | |
260 | { | |
261 | if (irc_domain[0]) | |
262 | { | |
263 | size_t len = strlen(hname); | |
264 | ||
265 | if ((strlen(irc_domain) + len + 2) < size) | |
266 | { | |
267 | hname[len++] = '.'; | |
268 | strcpy(hname + len, irc_domain); | |
269 | } | |
270 | } | |
271 | } | |
272 | } | |
273 | ||
274 | /* | |
275 | * rem_request - remove a request from the list. | |
276 | * This must also free any memory that has been allocated for | |
277 | * temporary storage of DNS results. | |
278 | */ | |
279 | static void rem_request(struct reslist *request) | |
280 | { | |
281 | rb_dlinkDelete(&request->node, &request_list); | |
282 | rb_free(request->name); | |
283 | rb_free(request); | |
284 | } | |
285 | ||
286 | /* | |
287 | * make_request - Create a DNS request record for the server. | |
288 | */ | |
289 | static struct reslist *make_request(struct DNSQuery *query) | |
290 | { | |
291 | struct reslist *request = rb_malloc(sizeof(struct reslist)); | |
292 | ||
293 | request->sentat = rb_current_time(); | |
294 | request->retries = 3; | |
295 | request->timeout = 4; /* start at 4 and exponential inc. */ | |
296 | request->query = query; | |
297 | ||
298 | /* | |
299 | * generate a unique id | |
300 | * NOTE: we don't have to worry about converting this to and from | |
301 | * network byte order, the nameserver does not interpret this value | |
302 | * and returns it unchanged | |
303 | * | |
304 | * we generate an id per request now (instead of per send) to allow | |
305 | * late replies to be used. | |
306 | */ | |
307 | request->id = generate_random_id(); | |
308 | ||
309 | rb_dlinkAdd(request, &request->node, &request_list); | |
310 | ||
311 | return request; | |
312 | } | |
313 | ||
314 | /* | |
315 | * retryfreq - determine how many queries to wait before resending | |
316 | * if there have been that many consecutive timeouts | |
fa2d5b83 EM |
317 | * |
318 | * This is a cubic backoff btw, if anyone didn't pick up on it. --Elizafox | |
ed62c46b AC |
319 | */ |
320 | static int retryfreq(int timeouts) | |
321 | { | |
322 | switch (timeouts) | |
323 | { | |
fa2d5b83 EM |
324 | case 1: |
325 | return 3; | |
326 | case 2: | |
327 | return 9; | |
328 | case 3: | |
329 | return 27; | |
330 | case 4: | |
331 | return 81; | |
332 | default: | |
333 | return 243; | |
ed62c46b AC |
334 | } |
335 | } | |
336 | ||
337 | /* | |
338 | * send_res_msg - sends msg to a nameserver. | |
339 | * This should reflect /etc/resolv.conf. | |
340 | * Returns number of nameserver successfully sent to | |
341 | * or -1 if no successful sends. | |
342 | */ | |
343 | static int send_res_msg(const char *msg, int len, int rcount) | |
344 | { | |
345 | int i; | |
346 | int ns; | |
347 | static int retrycnt; | |
348 | ||
349 | retrycnt++; | |
350 | /* First try a nameserver that seems to work. | |
351 | * Every once in a while, try a possibly broken one to check | |
352 | * if it is working again. | |
353 | */ | |
354 | for (i = 0; i < irc_nscount; i++) | |
355 | { | |
356 | ns = (i + rcount - 1) % irc_nscount; | |
357 | if (ns_failure_count[ns] && retrycnt % retryfreq(ns_failure_count[ns])) | |
358 | continue; | |
359 | if (sendto(rb_get_fd(res_fd), msg, len, 0, | |
360 | (struct sockaddr *)&(irc_nsaddr_list[ns]), | |
361 | GET_SS_LEN(&irc_nsaddr_list[ns])) == len) | |
362 | return ns; | |
363 | } | |
364 | ||
365 | /* No known working nameservers, try some broken one. */ | |
366 | for (i = 0; i < irc_nscount; i++) | |
367 | { | |
368 | ns = (i + rcount - 1) % irc_nscount; | |
369 | if (!ns_failure_count[ns]) | |
370 | continue; | |
371 | if (sendto(rb_get_fd(res_fd), msg, len, 0, | |
372 | (struct sockaddr *)&(irc_nsaddr_list[ns]), | |
373 | GET_SS_LEN(&irc_nsaddr_list[ns])) == len) | |
374 | return ns; | |
375 | } | |
376 | ||
377 | return -1; | |
378 | } | |
379 | ||
380 | /* | |
381 | * find_id - find a dns request id (id is determined by dn_mkquery) | |
382 | */ | |
383 | static struct reslist *find_id(int id) | |
384 | { | |
385 | rb_dlink_node *ptr; | |
386 | struct reslist *request; | |
387 | ||
388 | RB_DLINK_FOREACH(ptr, request_list.head) | |
389 | { | |
390 | request = ptr->data; | |
391 | ||
392 | if (request->id == id) | |
393 | return (request); | |
394 | } | |
395 | ||
396 | return (NULL); | |
397 | } | |
398 | ||
399 | static uint16_t | |
400 | generate_random_id(void) | |
401 | { | |
402 | uint16_t id; | |
403 | ||
404 | do | |
405 | { | |
406 | rb_get_random(&id, sizeof(id)); | |
407 | if(id == 0xffff) | |
408 | continue; | |
409 | } | |
410 | while(find_id(id)); | |
411 | return id; | |
412 | } | |
413 | ||
ed62c46b AC |
414 | /* |
415 | * gethost_byname_type - get host address from name, adding domain if needed | |
416 | */ | |
417 | void gethost_byname_type(const char *name, struct DNSQuery *query, int type) | |
418 | { | |
419 | char fqdn[IRCD_RES_HOSTLEN + 1]; | |
420 | assert(name != 0); | |
421 | ||
422 | rb_strlcpy(fqdn, name, sizeof fqdn); | |
423 | add_local_domain(fqdn, IRCD_RES_HOSTLEN); | |
424 | gethost_byname_type_fqdn(fqdn, query, type); | |
425 | } | |
426 | ||
427 | /* | |
428 | * gethost_byname_type_fqdn - get host address from fqdn | |
429 | */ | |
430 | static void gethost_byname_type_fqdn(const char *name, struct DNSQuery *query, | |
431 | int type) | |
432 | { | |
433 | assert(name != 0); | |
434 | do_query_name(query, name, NULL, type); | |
435 | } | |
436 | ||
437 | /* | |
438 | * gethost_byaddr - get host name from address | |
439 | */ | |
440 | void gethost_byaddr(const struct rb_sockaddr_storage *addr, struct DNSQuery *query) | |
441 | { | |
442 | do_query_number(query, addr, NULL); | |
443 | } | |
444 | ||
445 | /* | |
446 | * do_query_name - nameserver lookup name | |
447 | */ | |
448 | static void do_query_name(struct DNSQuery *query, const char *name, struct reslist *request, | |
449 | int type) | |
450 | { | |
451 | if (request == NULL) | |
452 | { | |
453 | request = make_request(query); | |
454 | request->name = rb_strdup(name); | |
455 | } | |
456 | ||
457 | rb_strlcpy(request->queryname, name, sizeof(request->queryname)); | |
458 | request->type = type; | |
459 | query_name(request); | |
460 | } | |
461 | ||
8ed8e5ca EM |
462 | /* Build an rDNS style query - if suffix is NULL, use the appropriate .arpa zone */ |
463 | void build_rdns(char *buf, size_t size, const struct rb_sockaddr_storage *addr, const char *suffix) | |
ed62c46b AC |
464 | { |
465 | const unsigned char *cp; | |
466 | ||
c99ae190 | 467 | if (GET_SS_FAMILY(addr) == AF_INET) |
ed62c46b AC |
468 | { |
469 | const struct sockaddr_in *v4 = (const struct sockaddr_in *)addr; | |
470 | cp = (const unsigned char *)&v4->sin_addr.s_addr; | |
471 | ||
8ed8e5ca EM |
472 | (void) snprintf(buf, size, "%u.%u.%u.%u.%s", |
473 | (unsigned int)(cp[3]), | |
474 | (unsigned int)(cp[2]), | |
475 | (unsigned int)(cp[1]), | |
476 | (unsigned int)(cp[0]), | |
477 | suffix == NULL ? "in-addr.arpa" : suffix); | |
ed62c46b AC |
478 | } |
479 | #ifdef RB_IPV6 | |
c99ae190 | 480 | else if (GET_SS_FAMILY(addr) == AF_INET6) |
ed62c46b AC |
481 | { |
482 | const struct sockaddr_in6 *v6 = (const struct sockaddr_in6 *)addr; | |
483 | cp = (const unsigned char *)&v6->sin6_addr.s6_addr; | |
484 | ||
d52762b2 EM |
485 | #define HI_NIBBLE(x) (unsigned int)((x) >> 4) |
486 | #define LO_NIBBLE(x) (unsigned int)((x) & 0xf) | |
487 | ||
8ed8e5ca EM |
488 | (void) snprintf(buf, size, |
489 | "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%s", | |
d52762b2 EM |
490 | LO_NIBBLE(cp[15]), HI_NIBBLE(cp[15]), |
491 | LO_NIBBLE(cp[14]), HI_NIBBLE(cp[14]), | |
492 | LO_NIBBLE(cp[13]), HI_NIBBLE(cp[13]), | |
493 | LO_NIBBLE(cp[12]), HI_NIBBLE(cp[12]), | |
494 | LO_NIBBLE(cp[11]), HI_NIBBLE(cp[11]), | |
495 | LO_NIBBLE(cp[10]), HI_NIBBLE(cp[10]), | |
496 | LO_NIBBLE(cp[9]), HI_NIBBLE(cp[9]), | |
497 | LO_NIBBLE(cp[8]), HI_NIBBLE(cp[8]), | |
498 | LO_NIBBLE(cp[7]), HI_NIBBLE(cp[7]), | |
499 | LO_NIBBLE(cp[6]), HI_NIBBLE(cp[6]), | |
500 | LO_NIBBLE(cp[5]), HI_NIBBLE(cp[5]), | |
501 | LO_NIBBLE(cp[4]), HI_NIBBLE(cp[4]), | |
502 | LO_NIBBLE(cp[3]), HI_NIBBLE(cp[3]), | |
503 | LO_NIBBLE(cp[2]), HI_NIBBLE(cp[2]), | |
504 | LO_NIBBLE(cp[1]), HI_NIBBLE(cp[1]), | |
505 | LO_NIBBLE(cp[0]), HI_NIBBLE(cp[0]), | |
8ed8e5ca | 506 | suffix == NULL ? "ip6.arpa" : suffix); |
ed62c46b | 507 | } |
d52762b2 EM |
508 | |
509 | #undef HI_NIBBLE | |
510 | #undef LO_NIBBLE | |
511 | ||
ed62c46b | 512 | #endif |
8ed8e5ca EM |
513 | } |
514 | ||
515 | /* | |
516 | * do_query_number - Use this to do reverse IP# lookups. | |
517 | */ | |
518 | static void do_query_number(struct DNSQuery *query, const struct rb_sockaddr_storage *addr, | |
519 | struct reslist *request) | |
520 | { | |
8ed8e5ca EM |
521 | if (request == NULL) |
522 | { | |
523 | request = make_request(query); | |
524 | memcpy(&request->addr, addr, sizeof(struct rb_sockaddr_storage)); | |
525 | request->name = (char *)rb_malloc(IRCD_RES_HOSTLEN + 1); | |
526 | } | |
527 | ||
528 | build_rdns(request->queryname, IRCD_RES_HOSTLEN + 1, addr, NULL); | |
ed62c46b AC |
529 | |
530 | request->type = T_PTR; | |
531 | query_name(request); | |
532 | } | |
533 | ||
534 | /* | |
535 | * query_name - generate a query based on class, type and name. | |
536 | */ | |
537 | static void query_name(struct reslist *request) | |
538 | { | |
539 | char buf[MAXPACKET]; | |
540 | int request_len = 0; | |
541 | int ns; | |
542 | ||
543 | memset(buf, 0, sizeof(buf)); | |
544 | ||
545 | if ((request_len = | |
546 | irc_res_mkquery(request->queryname, C_IN, request->type, (unsigned char *)buf, sizeof(buf))) > 0) | |
547 | { | |
548 | HEADER *header = (HEADER *)(void *)buf; | |
549 | header->id = request->id; | |
550 | ++request->sends; | |
551 | ||
552 | ns = send_res_msg(buf, request_len, request->sends); | |
553 | if (ns != -1) | |
554 | request->lastns = ns; | |
555 | } | |
556 | } | |
557 | ||
558 | static void resend_query(struct reslist *request) | |
559 | { | |
560 | if (--request->retries <= 0) | |
561 | { | |
562 | (*request->query->callback) (request->query->ptr, NULL); | |
563 | rem_request(request); | |
564 | return; | |
565 | } | |
566 | ||
567 | switch (request->type) | |
568 | { | |
fa2d5b83 EM |
569 | case T_PTR: |
570 | do_query_number(NULL, &request->addr, request); | |
571 | break; | |
572 | case T_A: | |
ed62c46b | 573 | #ifdef RB_IPV6 |
fa2d5b83 | 574 | case T_AAAA: |
ed62c46b | 575 | #endif |
fa2d5b83 EM |
576 | do_query_name(NULL, request->name, request, request->type); |
577 | break; | |
578 | default: | |
579 | break; | |
ed62c46b AC |
580 | } |
581 | } | |
582 | ||
583 | /* | |
584 | * check_question - check if the reply really belongs to the | |
585 | * name we queried (to guard against late replies from previous | |
586 | * queries with the same id). | |
587 | */ | |
588 | static int check_question(struct reslist *request, HEADER * header, char *buf, char *eob) | |
589 | { | |
590 | char hostbuf[IRCD_RES_HOSTLEN + 1]; /* working buffer */ | |
591 | unsigned char *current; /* current position in buf */ | |
592 | int n; /* temp count */ | |
593 | ||
594 | current = (unsigned char *)buf + sizeof(HEADER); | |
595 | if (header->qdcount != 1) | |
596 | return 0; | |
597 | n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current, hostbuf, | |
598 | sizeof(hostbuf)); | |
599 | if (n <= 0) | |
600 | return 0; | |
f956cb0f | 601 | if (rb_strcasecmp(hostbuf, request->queryname)) |
ed62c46b AC |
602 | return 0; |
603 | return 1; | |
604 | } | |
605 | ||
606 | /* | |
607 | * proc_answer - process name server reply | |
608 | */ | |
609 | static int proc_answer(struct reslist *request, HEADER * header, char *buf, char *eob) | |
610 | { | |
611 | char hostbuf[IRCD_RES_HOSTLEN + 100]; /* working buffer */ | |
612 | unsigned char *current; /* current position in buf */ | |
613 | int type; /* answer type */ | |
614 | int n; /* temp count */ | |
615 | int rd_length; | |
616 | struct sockaddr_in *v4; /* conversion */ | |
617 | #ifdef RB_IPV6 | |
618 | struct sockaddr_in6 *v6; | |
619 | #endif | |
620 | current = (unsigned char *)buf + sizeof(HEADER); | |
621 | ||
622 | for (; header->qdcount > 0; --header->qdcount) | |
623 | { | |
624 | if ((n = irc_dn_skipname(current, (unsigned char *)eob)) < 0) | |
625 | return 0; | |
626 | ||
627 | current += (size_t) n + QFIXEDSZ; | |
628 | } | |
629 | ||
630 | /* | |
631 | * process each answer sent to us blech. | |
632 | */ | |
633 | while (header->ancount > 0 && (char *)current < eob) | |
634 | { | |
635 | header->ancount--; | |
636 | ||
637 | n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current, hostbuf, | |
638 | sizeof(hostbuf)); | |
639 | ||
640 | if (n < 0) | |
641 | { | |
642 | /* | |
643 | * broken message | |
644 | */ | |
645 | return (0); | |
646 | } | |
647 | else if (n == 0) | |
648 | { | |
649 | /* | |
650 | * no more answers left | |
651 | */ | |
652 | return (0); | |
653 | } | |
654 | ||
655 | hostbuf[IRCD_RES_HOSTLEN] = '\0'; | |
656 | ||
657 | /* With Address arithmetic you have to be very anal | |
658 | * this code was not working on alpha due to that | |
659 | * (spotted by rodder/jailbird/dianora) | |
660 | */ | |
661 | current += (size_t) n; | |
662 | ||
663 | if (!(((char *)current + ANSWER_FIXED_SIZE) < eob)) | |
664 | break; | |
665 | ||
666 | type = irc_ns_get16(current); | |
667 | current += TYPE_SIZE; | |
668 | ||
669 | (void) irc_ns_get16(current); | |
670 | current += CLASS_SIZE; | |
671 | ||
672 | request->ttl = irc_ns_get32(current); | |
673 | current += TTL_SIZE; | |
674 | ||
675 | rd_length = irc_ns_get16(current); | |
676 | current += RDLENGTH_SIZE; | |
677 | ||
678 | /* | |
679 | * Wait to set request->type until we verify this structure | |
680 | */ | |
681 | switch (type) | |
682 | { | |
fa2d5b83 EM |
683 | case T_A: |
684 | if (request->type != T_A) | |
685 | return (0); | |
686 | ||
687 | /* | |
688 | * check for invalid rd_length or too many addresses | |
689 | */ | |
690 | if (rd_length != sizeof(struct in_addr)) | |
691 | return (0); | |
692 | v4 = (struct sockaddr_in *)&request->addr; | |
693 | SET_SS_LEN(&request->addr, sizeof(struct sockaddr_in)); | |
694 | v4->sin_family = AF_INET; | |
695 | memcpy(&v4->sin_addr, current, sizeof(struct in_addr)); | |
696 | return (1); | |
ed62c46b | 697 | #ifdef RB_IPV6 |
fa2d5b83 EM |
698 | case T_AAAA: |
699 | if (request->type != T_AAAA) | |
700 | return (0); | |
701 | if (rd_length != sizeof(struct in6_addr)) | |
702 | return (0); | |
703 | SET_SS_LEN(&request->addr, sizeof(struct sockaddr_in6)); | |
704 | v6 = (struct sockaddr_in6 *)&request->addr; | |
705 | v6->sin6_family = AF_INET6; | |
706 | memcpy(&v6->sin6_addr, current, sizeof(struct in6_addr)); | |
707 | return (1); | |
ed62c46b | 708 | #endif |
fa2d5b83 EM |
709 | case T_PTR: |
710 | if (request->type != T_PTR) | |
711 | return (0); | |
712 | n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current, | |
713 | hostbuf, sizeof(hostbuf)); | |
714 | if (n < 0) | |
715 | return (0); /* broken message */ | |
716 | else if (n == 0) | |
717 | return (0); /* no more answers left */ | |
718 | ||
719 | rb_strlcpy(request->name, hostbuf, IRCD_RES_HOSTLEN + 1); | |
720 | ||
721 | return (1); | |
fa2d5b83 EM |
722 | case T_CNAME: |
723 | /* real answer will follow */ | |
724 | current += rd_length; | |
725 | break; | |
726 | default: | |
727 | break; | |
ed62c46b AC |
728 | } |
729 | } | |
730 | ||
731 | return (1); | |
732 | } | |
733 | ||
734 | /* | |
735 | * res_read_single_reply - read a dns reply from the nameserver and process it. | |
736 | * Return value: 1 if a packet was read, 0 otherwise | |
737 | */ | |
738 | static int res_read_single_reply(rb_fde_t *F, void *data) | |
739 | { | |
740 | char buf[sizeof(HEADER) + MAXPACKET] | |
741 | /* Sparc and alpha need 16bit-alignment for accessing header->id | |
742 | * (which is uint16_t). Because of the header = (HEADER*) buf; | |
743 | * lateron, this is neeeded. --FaUl | |
744 | */ | |
745 | #if defined(__sparc__) || defined(__alpha__) | |
746 | __attribute__ ((aligned(16))) | |
747 | #endif | |
748 | ; | |
749 | HEADER *header; | |
750 | struct reslist *request = NULL; | |
751 | struct DNSReply *reply = NULL; | |
752 | int rc; | |
753 | int answer_count; | |
754 | socklen_t len = sizeof(struct rb_sockaddr_storage); | |
755 | struct rb_sockaddr_storage lsin; | |
756 | int ns; | |
757 | ||
758 | rc = recvfrom(rb_get_fd(F), buf, sizeof(buf), 0, (struct sockaddr *)&lsin, &len); | |
759 | ||
760 | /* No packet */ | |
761 | if (rc == 0 || rc == -1) | |
762 | return 0; | |
763 | ||
764 | /* Too small */ | |
765 | if (rc <= (int)(sizeof(HEADER))) | |
766 | return 1; | |
767 | ||
768 | /* | |
769 | * convert DNS reply reader from Network byte order to CPU byte order. | |
770 | */ | |
771 | header = (HEADER *)(void *)buf; | |
772 | header->ancount = ntohs(header->ancount); | |
773 | header->qdcount = ntohs(header->qdcount); | |
774 | header->nscount = ntohs(header->nscount); | |
775 | header->arcount = ntohs(header->arcount); | |
776 | ||
777 | /* | |
778 | * response for an id which we have already received an answer for | |
779 | * just ignore this response. | |
780 | */ | |
781 | if (0 == (request = find_id(header->id))) | |
782 | return 1; | |
783 | ||
784 | /* | |
785 | * check against possibly fake replies | |
786 | */ | |
787 | ns = res_ourserver(&lsin); | |
788 | if (ns == -1) | |
789 | return 1; | |
790 | ||
791 | if (ns != request->lastns) | |
792 | { | |
793 | /* | |
794 | * We'll accept the late reply, but penalize it a little more to make | |
795 | * sure a laggy server doesn't end up favored. | |
796 | */ | |
797 | ns_failure_count[ns] += 3; | |
798 | } | |
799 | ||
800 | ||
801 | if (!check_question(request, header, buf, buf + rc)) | |
802 | return 1; | |
803 | ||
804 | if ((header->rcode != NO_ERRORS) || (header->ancount == 0)) | |
805 | { | |
806 | /* | |
807 | * RFC 2136 states that in the event of a server returning SERVFAIL | |
808 | * or NOTIMP, the request should be resent to the next server. | |
809 | * Additionally, if the server refuses our query, resend it as well. | |
810 | * -- mr_flea | |
811 | */ | |
812 | if (SERVFAIL == header->rcode || NOTIMP == header->rcode || | |
813 | REFUSED == header->rcode) | |
814 | { | |
815 | ns_failure_count[ns]++; | |
816 | resend_query(request); | |
817 | } | |
818 | else | |
819 | { | |
820 | /* | |
821 | * Either a fatal error was returned or no answer. Cancel the | |
822 | * request. | |
823 | */ | |
824 | if (NXDOMAIN == header->rcode) | |
825 | { | |
826 | /* If the rcode is NXDOMAIN, treat it as a good response. */ | |
827 | ns_failure_count[ns] /= 4; | |
828 | } | |
829 | (*request->query->callback) (request->query->ptr, NULL); | |
830 | rem_request(request); | |
831 | } | |
832 | return 1; | |
833 | } | |
834 | /* | |
835 | * If this fails there was an error decoding the received packet. | |
836 | * -- jilles | |
837 | */ | |
838 | answer_count = proc_answer(request, header, buf, buf + rc); | |
839 | ||
840 | if (answer_count) | |
841 | { | |
842 | if (request->type == T_PTR) | |
843 | { | |
844 | if (request->name == NULL) | |
845 | { | |
846 | /* | |
847 | * Got a PTR response with no name, something strange is | |
848 | * happening. Try another DNS server. | |
849 | */ | |
850 | ns_failure_count[ns]++; | |
851 | resend_query(request); | |
852 | return 1; | |
853 | } | |
854 | ||
855 | /* | |
856 | * Lookup the 'authoritative' name that we were given for the | |
857 | * ip#. | |
858 | */ | |
859 | #ifdef RB_IPV6 | |
9783438e | 860 | if (GET_SS_FAMILY(&request->addr) == AF_INET6) |
ed62c46b AC |
861 | gethost_byname_type_fqdn(request->name, request->query, T_AAAA); |
862 | else | |
863 | #endif | |
864 | gethost_byname_type_fqdn(request->name, request->query, T_A); | |
865 | rem_request(request); | |
866 | } | |
867 | else | |
868 | { | |
869 | /* | |
870 | * got a name and address response, client resolved | |
871 | */ | |
872 | reply = make_dnsreply(request); | |
873 | (*request->query->callback) (request->query->ptr, reply); | |
874 | rb_free(reply); | |
875 | rem_request(request); | |
876 | } | |
877 | ||
878 | ns_failure_count[ns] /= 4; | |
879 | } | |
880 | else | |
881 | { | |
882 | /* Invalid or corrupt reply - try another resolver. */ | |
883 | ns_failure_count[ns]++; | |
884 | resend_query(request); | |
885 | } | |
886 | return 1; | |
887 | } | |
888 | ||
889 | static void | |
890 | res_readreply(rb_fde_t *F, void *data) | |
891 | { | |
892 | while (res_read_single_reply(F, data)) | |
893 | ; | |
894 | rb_setselect(F, RB_SELECT_READ, res_readreply, NULL); | |
895 | } | |
896 | ||
897 | static struct DNSReply * | |
898 | make_dnsreply(struct reslist *request) | |
899 | { | |
900 | struct DNSReply *cp; | |
901 | lrb_assert(request != 0); | |
902 | ||
903 | cp = (struct DNSReply *)rb_malloc(sizeof(struct DNSReply)); | |
904 | ||
905 | cp->h_name = request->name; | |
906 | memcpy(&cp->addr, &request->addr, sizeof(cp->addr)); | |
907 | return (cp); | |
908 | } |