1 |
/* |
2 |
* A rewrite of Darren Reeds original res.c As there is nothing |
3 |
* left of Darrens original code, this is now licensed by the hybrid group. |
4 |
* (Well, some of the function names are the same, and bits of the structs..) |
5 |
* You can use it where it is useful, free even. Buy us a beer and stuff. |
6 |
* |
7 |
* The authors takes no responsibility for any damage or loss |
8 |
* of property which results from the use of this software. |
9 |
* |
10 |
* $Id$ |
11 |
* |
12 |
* July 1999 - Rewrote a bunch of stuff here. Change hostent builder code, |
13 |
* added callbacks and reference counting of returned hostents. |
14 |
* --Bleep (Thomas Helvey <tomh@inxpress.net>) |
15 |
* |
16 |
* This was all needlessly complicated for irc. Simplified. No more hostent |
17 |
* All we really care about is the IP -> hostname mappings. Thats all. |
18 |
* |
19 |
* Apr 28, 2003 --cryogen and Dianora |
20 |
*/ |
21 |
|
22 |
#include "stdinc.h" |
23 |
#include "list.h" |
24 |
#include "balloc.h" |
25 |
#include "client.h" |
26 |
#include "event.h" |
27 |
#include "irc_string.h" |
28 |
#include "sprintf_irc.h" |
29 |
#include "ircd.h" |
30 |
#include "numeric.h" |
31 |
#include "rng_mt.h" |
32 |
#include "fdlist.h" |
33 |
#include "fileio.h" /* for fbopen / fbclose / fbputs */ |
34 |
#include "s_bsd.h" |
35 |
#include "s_log.h" |
36 |
#include "send.h" |
37 |
#include "memory.h" |
38 |
#include "irc_res.h" |
39 |
#include "irc_reslib.h" |
40 |
#include "irc_getnameinfo.h" |
41 |
#include "common.h" |
42 |
|
43 |
#if (CHAR_BIT != 8) |
44 |
#error this code needs to be able to address individual octets |
45 |
#endif |
46 |
|
47 |
static PF res_readreply; |
48 |
|
49 |
#define MAXPACKET 1024 /* rfc sez 512 but we expand names so ... */ |
50 |
#define RES_MAXALIASES 35 /* maximum aliases allowed */ |
51 |
#define RES_MAXADDRS 35 /* maximum addresses allowed */ |
52 |
#define AR_TTL 600 /* TTL in seconds for dns cache entries */ |
53 |
|
54 |
/* RFC 1104/1105 wasn't very helpful about what these fields |
55 |
* should be named, so for now, we'll just name them this way. |
56 |
* we probably should look at what named calls them or something. |
57 |
*/ |
58 |
#define TYPE_SIZE (size_t)2 |
59 |
#define CLASS_SIZE (size_t)2 |
60 |
#define TTL_SIZE (size_t)4 |
61 |
#define RDLENGTH_SIZE (size_t)2 |
62 |
#define ANSWER_FIXED_SIZE (TYPE_SIZE + CLASS_SIZE + TTL_SIZE + RDLENGTH_SIZE) |
63 |
|
64 |
typedef enum |
65 |
{ |
66 |
REQ_IDLE, /* We're doing not much at all */ |
67 |
REQ_PTR, /* Looking up a PTR */ |
68 |
REQ_A, /* Looking up an A, possibly because AAAA failed */ |
69 |
#ifdef IPV6 |
70 |
REQ_AAAA, /* Looking up an AAAA */ |
71 |
#endif |
72 |
REQ_CNAME /* We got a CNAME in response, we better get a real answer next */ |
73 |
} request_state; |
74 |
|
75 |
struct reslist |
76 |
{ |
77 |
dlink_node node; |
78 |
int id; |
79 |
int sent; /* number of requests sent */ |
80 |
request_state state; /* State the resolver machine is in */ |
81 |
time_t ttl; |
82 |
char type; |
83 |
char retries; /* retry counter */ |
84 |
char sends; /* number of sends (>1 means resent) */ |
85 |
char resend; /* send flag. 0 == dont resend */ |
86 |
time_t sentat; |
87 |
time_t timeout; |
88 |
struct irc_ssaddr addr; |
89 |
char *name; |
90 |
dns_callback_fnc callback; |
91 |
void *callback_ctx; |
92 |
}; |
93 |
|
94 |
static fde_t ResolverFileDescriptor; |
95 |
static dlink_list request_list = { NULL, NULL, 0 }; |
96 |
static BlockHeap *dns_heap = NULL; |
97 |
|
98 |
static void rem_request(struct reslist *request); |
99 |
static struct reslist *make_request(dns_callback_fnc callback, void *); |
100 |
static void do_query_name(dns_callback_fnc callback, void *, |
101 |
const char *, struct reslist *, int); |
102 |
static void do_query_number(dns_callback_fnc callback, void *ctx, |
103 |
const struct irc_ssaddr *, |
104 |
struct reslist *request); |
105 |
static void query_name(const char *name, int query_class, int query_type, |
106 |
struct reslist *request); |
107 |
static int send_res_msg(const char *buf, int len, int count); |
108 |
static void resend_query(struct reslist *request); |
109 |
static int proc_answer(struct reslist *request, HEADER *header, char *, char *); |
110 |
static struct reslist *find_id(int id); |
111 |
|
112 |
|
113 |
/* |
114 |
* int |
115 |
* res_ourserver(inp) |
116 |
* looks up "inp" in irc_nsaddr_list[] |
117 |
* returns: |
118 |
* 0 : not found |
119 |
* >0 : found |
120 |
* author: |
121 |
* paul vixie, 29may94 |
122 |
* revised for ircd, cryogen(stu) may03 |
123 |
*/ |
124 |
static int |
125 |
res_ourserver(const struct irc_ssaddr *inp) |
126 |
{ |
127 |
#ifdef IPV6 |
128 |
const struct sockaddr_in6 *v6; |
129 |
const struct sockaddr_in6 *v6in = (const struct sockaddr_in6 *)inp; |
130 |
#endif |
131 |
const struct sockaddr_in *v4; |
132 |
const struct sockaddr_in *v4in = (const struct sockaddr_in *)inp; |
133 |
int ns; |
134 |
|
135 |
for (ns = 0; ns < irc_nscount; ns++) |
136 |
{ |
137 |
const struct irc_ssaddr *srv = &irc_nsaddr_list[ns]; |
138 |
#ifdef IPV6 |
139 |
v6 = (const struct sockaddr_in6 *)srv; |
140 |
#endif |
141 |
v4 = (const struct sockaddr_in *)srv; |
142 |
|
143 |
/* could probably just memcmp(srv, inp, srv.ss_len) here |
144 |
* but we'll air on the side of caution - stu |
145 |
* |
146 |
*/ |
147 |
switch (srv->ss.ss_family) |
148 |
{ |
149 |
#ifdef IPV6 |
150 |
case AF_INET6: |
151 |
if (srv->ss.ss_family == inp->ss.ss_family) |
152 |
if (v6->sin6_port == v6in->sin6_port) |
153 |
if ((memcmp(&v6->sin6_addr.s6_addr, &v6in->sin6_addr.s6_addr, |
154 |
sizeof(struct in6_addr)) == 0) || |
155 |
(memcmp(&v6->sin6_addr.s6_addr, &in6addr_any, |
156 |
sizeof(struct in6_addr)) == 0)) |
157 |
return(1); |
158 |
break; |
159 |
#endif |
160 |
case AF_INET: |
161 |
if (srv->ss.ss_family == inp->ss.ss_family) |
162 |
if (v4->sin_port == v4in->sin_port) |
163 |
if ((v4->sin_addr.s_addr == INADDR_ANY) || |
164 |
(v4->sin_addr.s_addr == v4in->sin_addr.s_addr)) |
165 |
return(1); |
166 |
break; |
167 |
default: |
168 |
break; |
169 |
} |
170 |
} |
171 |
|
172 |
return(0); |
173 |
} |
174 |
|
175 |
/* |
176 |
* timeout_query_list - Remove queries from the list which have been |
177 |
* there too long without being resolved. |
178 |
*/ |
179 |
static time_t |
180 |
timeout_query_list(time_t now) |
181 |
{ |
182 |
dlink_node *ptr; |
183 |
dlink_node *next_ptr; |
184 |
struct reslist *request; |
185 |
time_t next_time = 0; |
186 |
time_t timeout = 0; |
187 |
|
188 |
DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head) |
189 |
{ |
190 |
request = ptr->data; |
191 |
timeout = request->sentat + request->timeout; |
192 |
|
193 |
if (now >= timeout) |
194 |
{ |
195 |
if (--request->retries <= 0) |
196 |
{ |
197 |
(*request->callback)(request->callback_ctx, NULL, NULL); |
198 |
rem_request(request); |
199 |
continue; |
200 |
} |
201 |
else |
202 |
{ |
203 |
request->sentat = now; |
204 |
request->timeout += request->timeout; |
205 |
resend_query(request); |
206 |
} |
207 |
} |
208 |
|
209 |
if ((next_time == 0) || timeout < next_time) |
210 |
{ |
211 |
next_time = timeout; |
212 |
} |
213 |
} |
214 |
|
215 |
return((next_time > now) ? next_time : (now + AR_TTL)); |
216 |
} |
217 |
|
218 |
/* |
219 |
* timeout_resolver - check request list |
220 |
*/ |
221 |
static void |
222 |
timeout_resolver(void *notused) |
223 |
{ |
224 |
timeout_query_list(CurrentTime); |
225 |
} |
226 |
|
227 |
/* |
228 |
* start_resolver - do everything we need to read the resolv.conf file |
229 |
* and initialize the resolver file descriptor if needed |
230 |
*/ |
231 |
static void |
232 |
start_resolver(void) |
233 |
{ |
234 |
irc_res_init(); |
235 |
|
236 |
if (!ResolverFileDescriptor.flags.open) |
237 |
{ |
238 |
if (comm_open(&ResolverFileDescriptor, irc_nsaddr_list[0].ss.ss_family, |
239 |
SOCK_DGRAM, 0, "Resolver socket") == -1) |
240 |
return; |
241 |
|
242 |
/* At the moment, the resolver FD data is global .. */ |
243 |
comm_setselect(&ResolverFileDescriptor, COMM_SELECT_READ, |
244 |
res_readreply, NULL, 0); |
245 |
eventAdd("timeout_resolver", timeout_resolver, NULL, 1); |
246 |
} |
247 |
} |
248 |
|
249 |
/* |
250 |
* init_resolver - initialize resolver and resolver library |
251 |
*/ |
252 |
void |
253 |
init_resolver(void) |
254 |
{ |
255 |
dns_heap = BlockHeapCreate("dns", sizeof(struct reslist), DNS_HEAP_SIZE); |
256 |
memset(&ResolverFileDescriptor, 0, sizeof(fde_t)); |
257 |
start_resolver(); |
258 |
} |
259 |
|
260 |
/* |
261 |
* restart_resolver - reread resolv.conf, reopen socket |
262 |
*/ |
263 |
void |
264 |
restart_resolver(void) |
265 |
{ |
266 |
fd_close(&ResolverFileDescriptor); |
267 |
eventDelete(timeout_resolver, NULL); /* -ddosen */ |
268 |
start_resolver(); |
269 |
} |
270 |
|
271 |
/* |
272 |
* rem_request - remove a request from the list. |
273 |
* This must also free any memory that has been allocated for |
274 |
* temporary storage of DNS results. |
275 |
*/ |
276 |
static void |
277 |
rem_request(struct reslist *request) |
278 |
{ |
279 |
dlinkDelete(&request->node, &request_list); |
280 |
|
281 |
MyFree(request->name); |
282 |
BlockHeapFree(dns_heap, request); |
283 |
} |
284 |
|
285 |
/* |
286 |
* make_request - Create a DNS request record for the server. |
287 |
*/ |
288 |
static struct reslist * |
289 |
make_request(dns_callback_fnc callback, void *ctx) |
290 |
{ |
291 |
struct reslist *request = BlockHeapAlloc(dns_heap); |
292 |
|
293 |
request->sentat = CurrentTime; |
294 |
request->retries = 3; |
295 |
request->resend = 1; |
296 |
request->timeout = 4; /* start at 4 and exponential inc. */ |
297 |
request->state = REQ_IDLE; |
298 |
request->callback = callback; |
299 |
request->callback_ctx = ctx; |
300 |
|
301 |
dlinkAdd(request, &request->node, &request_list); |
302 |
return request; |
303 |
} |
304 |
|
305 |
/* |
306 |
* delete_resolver_queries - cleanup outstanding queries |
307 |
* for which there no longer exist clients or conf lines. |
308 |
*/ |
309 |
void |
310 |
delete_resolver_queries(const void *vptr) |
311 |
{ |
312 |
dlink_node *ptr = NULL, *next_ptr = NULL; |
313 |
|
314 |
DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head) |
315 |
{ |
316 |
struct reslist *request = ptr->data; |
317 |
|
318 |
if (request->callback_ctx == vptr) |
319 |
rem_request(request); |
320 |
} |
321 |
} |
322 |
|
323 |
/* |
324 |
* send_res_msg - sends msg to all nameservers found in the "_res" structure. |
325 |
* This should reflect /etc/resolv.conf. We will get responses |
326 |
* which arent needed but is easier than checking to see if nameserver |
327 |
* isnt present. Returns number of messages successfully sent to |
328 |
* nameservers or -1 if no successful sends. |
329 |
*/ |
330 |
static int |
331 |
send_res_msg(const char *msg, int len, int rcount) |
332 |
{ |
333 |
int i; |
334 |
int sent = 0; |
335 |
int max_queries = IRCD_MIN(irc_nscount, rcount); |
336 |
|
337 |
/* RES_PRIMARY option is not implemented |
338 |
* if (res.options & RES_PRIMARY || 0 == max_queries) |
339 |
*/ |
340 |
if (max_queries == 0) |
341 |
max_queries = 1; |
342 |
|
343 |
for (i = 0; i < max_queries; i++) |
344 |
{ |
345 |
if (sendto(ResolverFileDescriptor.fd, msg, len, 0, |
346 |
(struct sockaddr*)&(irc_nsaddr_list[i]), |
347 |
irc_nsaddr_list[i].ss_len) == len) |
348 |
++sent; |
349 |
} |
350 |
|
351 |
return(sent); |
352 |
} |
353 |
|
354 |
/* |
355 |
* find_id - find a dns request id (id is determined by dn_mkquery) |
356 |
*/ |
357 |
static struct reslist * |
358 |
find_id(int id) |
359 |
{ |
360 |
dlink_node *ptr; |
361 |
struct reslist *request; |
362 |
|
363 |
DLINK_FOREACH(ptr, request_list.head) |
364 |
{ |
365 |
request = ptr->data; |
366 |
|
367 |
if (request->id == id) |
368 |
return(request); |
369 |
} |
370 |
|
371 |
return(NULL); |
372 |
} |
373 |
|
374 |
/* |
375 |
* gethost_byname_type - get host address from name |
376 |
* |
377 |
*/ |
378 |
void |
379 |
gethost_byname_type(dns_callback_fnc callback, void *ctx, const char *name, int type) |
380 |
{ |
381 |
assert(name != 0); |
382 |
do_query_name(callback, ctx, name, NULL, type); |
383 |
} |
384 |
|
385 |
/* |
386 |
* gethost_byname - wrapper for _type - send T_AAAA first if IPV6 supported |
387 |
*/ |
388 |
void |
389 |
gethost_byname(dns_callback_fnc callback, void *ctx, const char *name) |
390 |
{ |
391 |
#ifdef IPV6 |
392 |
gethost_byname_type(callback, ctx, name, T_AAAA); |
393 |
#else |
394 |
gethost_byname_type(callback, ctx, name, T_A); |
395 |
#endif |
396 |
} |
397 |
|
398 |
/* |
399 |
* gethost_byaddr - get host name from address |
400 |
*/ |
401 |
void |
402 |
gethost_byaddr(dns_callback_fnc callback, void *ctx, const struct irc_ssaddr *addr) |
403 |
{ |
404 |
do_query_number(callback, ctx, addr, NULL); |
405 |
} |
406 |
|
407 |
/* |
408 |
* do_query_name - nameserver lookup name |
409 |
*/ |
410 |
static void |
411 |
do_query_name(dns_callback_fnc callback, void *ctx, const char *name, |
412 |
struct reslist *request, int type) |
413 |
{ |
414 |
char host_name[HOSTLEN + 1]; |
415 |
|
416 |
strlcpy(host_name, name, sizeof(host_name)); |
417 |
|
418 |
if (request == NULL) |
419 |
{ |
420 |
request = make_request(callback, ctx); |
421 |
request->name = MyMalloc(strlen(host_name) + 1); |
422 |
request->type = type; |
423 |
strcpy(request->name, host_name); |
424 |
#ifdef IPV6 |
425 |
if (type != T_A) |
426 |
request->state = REQ_AAAA; |
427 |
else |
428 |
#endif |
429 |
request->state = REQ_A; |
430 |
} |
431 |
|
432 |
request->type = type; |
433 |
query_name(host_name, C_IN, type, request); |
434 |
} |
435 |
|
436 |
/* |
437 |
* do_query_number - Use this to do reverse IP# lookups. |
438 |
*/ |
439 |
static void |
440 |
do_query_number(dns_callback_fnc callback, void *ctx, |
441 |
const struct irc_ssaddr *addr, |
442 |
struct reslist *request) |
443 |
{ |
444 |
char ipbuf[128]; |
445 |
const unsigned char *cp; |
446 |
|
447 |
if (addr->ss.ss_family == AF_INET) |
448 |
{ |
449 |
const struct sockaddr_in *v4 = (const struct sockaddr_in *)addr; |
450 |
cp = (const unsigned char*)&v4->sin_addr.s_addr; |
451 |
|
452 |
ircsprintf(ipbuf, "%u.%u.%u.%u.in-addr.arpa.", |
453 |
(unsigned int)(cp[3]), (unsigned int)(cp[2]), |
454 |
(unsigned int)(cp[1]), (unsigned int)(cp[0])); |
455 |
} |
456 |
#ifdef IPV6 |
457 |
else if (addr->ss.ss_family == AF_INET6) |
458 |
{ |
459 |
const struct sockaddr_in6 *v6 = (const struct sockaddr_in6 *)addr; |
460 |
cp = (const unsigned char *)&v6->sin6_addr.s6_addr; |
461 |
|
462 |
sprintf(ipbuf, "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x." |
463 |
"%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.ip6.arpa.", |
464 |
(unsigned int)(cp[15]&0xf), (unsigned int)(cp[15]>>4), |
465 |
(unsigned int)(cp[14]&0xf), (unsigned int)(cp[14]>>4), |
466 |
(unsigned int)(cp[13]&0xf), (unsigned int)(cp[13]>>4), |
467 |
(unsigned int)(cp[12]&0xf), (unsigned int)(cp[12]>>4), |
468 |
(unsigned int)(cp[11]&0xf), (unsigned int)(cp[11]>>4), |
469 |
(unsigned int)(cp[10]&0xf), (unsigned int)(cp[10]>>4), |
470 |
(unsigned int)(cp[9]&0xf), (unsigned int)(cp[9]>>4), |
471 |
(unsigned int)(cp[8]&0xf), (unsigned int)(cp[8]>>4), |
472 |
(unsigned int)(cp[7]&0xf), (unsigned int)(cp[7]>>4), |
473 |
(unsigned int)(cp[6]&0xf), (unsigned int)(cp[6]>>4), |
474 |
(unsigned int)(cp[5]&0xf), (unsigned int)(cp[5]>>4), |
475 |
(unsigned int)(cp[4]&0xf), (unsigned int)(cp[4]>>4), |
476 |
(unsigned int)(cp[3]&0xf), (unsigned int)(cp[3]>>4), |
477 |
(unsigned int)(cp[2]&0xf), (unsigned int)(cp[2]>>4), |
478 |
(unsigned int)(cp[1]&0xf), (unsigned int)(cp[1]>>4), |
479 |
(unsigned int)(cp[0]&0xf), (unsigned int)(cp[0]>>4)); |
480 |
} |
481 |
#endif |
482 |
if (request == NULL) |
483 |
{ |
484 |
request = make_request(callback, ctx); |
485 |
request->type = T_PTR; |
486 |
memcpy(&request->addr, addr, sizeof(struct irc_ssaddr)); |
487 |
request->name = MyMalloc(HOSTLEN + 1); |
488 |
} |
489 |
|
490 |
query_name(ipbuf, C_IN, T_PTR, request); |
491 |
} |
492 |
|
493 |
/* |
494 |
* query_name - generate a query based on class, type and name. |
495 |
*/ |
496 |
static void |
497 |
query_name(const char *name, int query_class, int type, |
498 |
struct reslist *request) |
499 |
{ |
500 |
char buf[MAXPACKET]; |
501 |
int request_len = 0; |
502 |
|
503 |
memset(buf, 0, sizeof(buf)); |
504 |
|
505 |
if ((request_len = irc_res_mkquery(name, query_class, type, |
506 |
(unsigned char *)buf, sizeof(buf))) > 0) |
507 |
{ |
508 |
HEADER *header = (HEADER *)buf; |
509 |
|
510 |
/* |
511 |
* generate an unique id |
512 |
* NOTE: we don't have to worry about converting this to and from |
513 |
* network byte order, the nameserver does not interpret this value |
514 |
* and returns it unchanged |
515 |
*/ |
516 |
do |
517 |
header->id = (header->id + genrand_int32()) & 0xffff; |
518 |
while (find_id(header->id)); |
519 |
|
520 |
request->id = header->id; |
521 |
++request->sends; |
522 |
|
523 |
request->sent += send_res_msg(buf, request_len, request->sends); |
524 |
} |
525 |
} |
526 |
|
527 |
static void |
528 |
resend_query(struct reslist *request) |
529 |
{ |
530 |
if (request->resend == 0) |
531 |
return; |
532 |
|
533 |
switch (request->type) |
534 |
{ |
535 |
case T_PTR: |
536 |
do_query_number(NULL, NULL, &request->addr, request); |
537 |
break; |
538 |
case T_A: |
539 |
do_query_name(NULL, NULL, request->name, request, request->type); |
540 |
break; |
541 |
#ifdef IPV6 |
542 |
case T_AAAA: |
543 |
/* didnt work, try A */ |
544 |
if (request->state == REQ_AAAA) |
545 |
do_query_name(NULL, NULL, request->name, request, T_A); |
546 |
#endif |
547 |
default: |
548 |
break; |
549 |
} |
550 |
} |
551 |
|
552 |
/* |
553 |
* proc_answer - process name server reply |
554 |
*/ |
555 |
static int |
556 |
proc_answer(struct reslist *request, HEADER* header, char* buf, char* eob) |
557 |
{ |
558 |
char hostbuf[HOSTLEN + 100]; /* working buffer */ |
559 |
unsigned char *current; /* current position in buf */ |
560 |
int query_class; /* answer class */ |
561 |
int type; /* answer type */ |
562 |
int n; /* temp count */ |
563 |
int rd_length; |
564 |
struct sockaddr_in *v4; /* conversion */ |
565 |
#ifdef IPV6 |
566 |
struct sockaddr_in6 *v6; |
567 |
#endif |
568 |
current = (unsigned char *)buf + sizeof(HEADER); |
569 |
|
570 |
for (; header->qdcount > 0; --header->qdcount) |
571 |
{ |
572 |
if ((n = irc_dn_skipname(current, (unsigned char *)eob)) < 0) |
573 |
break; |
574 |
|
575 |
current += (size_t) n + QFIXEDSZ; |
576 |
} |
577 |
|
578 |
/* |
579 |
* process each answer sent to us blech. |
580 |
*/ |
581 |
while (header->ancount > 0 && (char *)current < eob) |
582 |
{ |
583 |
header->ancount--; |
584 |
|
585 |
n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current, |
586 |
hostbuf, sizeof(hostbuf)); |
587 |
|
588 |
if (n < 0) |
589 |
{ |
590 |
/* |
591 |
* broken message |
592 |
*/ |
593 |
return(0); |
594 |
} |
595 |
else if (n == 0) |
596 |
{ |
597 |
/* |
598 |
* no more answers left |
599 |
*/ |
600 |
return(0); |
601 |
} |
602 |
|
603 |
hostbuf[HOSTLEN] = '\0'; |
604 |
|
605 |
/* With Address arithmetic you have to be very anal |
606 |
* this code was not working on alpha due to that |
607 |
* (spotted by rodder/jailbird/dianora) |
608 |
*/ |
609 |
current += (size_t) n; |
610 |
|
611 |
if (!(((char *)current + ANSWER_FIXED_SIZE) < eob)) |
612 |
break; |
613 |
|
614 |
type = irc_ns_get16(current); |
615 |
current += TYPE_SIZE; |
616 |
|
617 |
query_class = irc_ns_get16(current); |
618 |
current += CLASS_SIZE; |
619 |
|
620 |
request->ttl = irc_ns_get32(current); |
621 |
current += TTL_SIZE; |
622 |
|
623 |
rd_length = irc_ns_get16(current); |
624 |
current += RDLENGTH_SIZE; |
625 |
|
626 |
/* |
627 |
* Wait to set request->type until we verify this structure |
628 |
*/ |
629 |
switch (type) |
630 |
{ |
631 |
case T_A: |
632 |
if (request->type != T_A) |
633 |
return(0); |
634 |
|
635 |
/* |
636 |
* check for invalid rd_length or too many addresses |
637 |
*/ |
638 |
if (rd_length != sizeof(struct in_addr)) |
639 |
return(0); |
640 |
v4 = (struct sockaddr_in *)&request->addr; |
641 |
request->addr.ss_len = sizeof(struct sockaddr_in); |
642 |
v4->sin_family = AF_INET; |
643 |
memcpy(&v4->sin_addr, current, sizeof(struct in_addr)); |
644 |
return(1); |
645 |
break; |
646 |
#ifdef IPV6 |
647 |
case T_AAAA: |
648 |
if (request->type != T_AAAA) |
649 |
return(0); |
650 |
if (rd_length != sizeof(struct in6_addr)) |
651 |
return(0); |
652 |
request->addr.ss_len = sizeof(struct sockaddr_in6); |
653 |
v6 = (struct sockaddr_in6 *)&request->addr; |
654 |
v6->sin6_family = AF_INET6; |
655 |
memcpy(&v6->sin6_addr, current, sizeof(struct in6_addr)); |
656 |
return(1); |
657 |
break; |
658 |
#endif |
659 |
case T_PTR: |
660 |
if (request->type != T_PTR) |
661 |
return(0); |
662 |
n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, |
663 |
current, hostbuf, sizeof(hostbuf)); |
664 |
if (n < 0) |
665 |
return(0); /* broken message */ |
666 |
else if (n == 0) |
667 |
return(0); /* no more answers left */ |
668 |
|
669 |
strlcpy(request->name, hostbuf, HOSTLEN + 1); |
670 |
|
671 |
return(1); |
672 |
break; |
673 |
case T_CNAME: /* first check we already havent started looking |
674 |
into a cname */ |
675 |
if (request->type != T_PTR) |
676 |
return(0); |
677 |
|
678 |
if (request->state == REQ_CNAME) |
679 |
{ |
680 |
n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, |
681 |
current, hostbuf, sizeof(hostbuf)); |
682 |
|
683 |
if (n < 0) |
684 |
return(0); |
685 |
return(1); |
686 |
} |
687 |
|
688 |
request->state = REQ_CNAME; |
689 |
current += rd_length; |
690 |
break; |
691 |
|
692 |
default: |
693 |
/* XXX I'd rather just throw away the entire bogus thing |
694 |
* but its possible its just a broken nameserver with still |
695 |
* valid answers. But lets do some rudimentary logging for now... |
696 |
*/ |
697 |
ilog(L_ERROR, "irc_res.c bogus type %d", type); |
698 |
break; |
699 |
} |
700 |
} |
701 |
|
702 |
return(1); |
703 |
} |
704 |
|
705 |
/* |
706 |
* res_readreply - read a dns reply from the nameserver and process it. |
707 |
*/ |
708 |
static void |
709 |
res_readreply(fde_t *fd, void *data) |
710 |
{ |
711 |
char buf[sizeof(HEADER) + MAXPACKET] |
712 |
/* Sparc and alpha need 16bit-alignment for accessing header->id |
713 |
* (which is uint16_t). Because of the header = (HEADER*) buf; |
714 |
* lateron, this is neeeded. --FaUl |
715 |
*/ |
716 |
#if defined(__sparc__) || defined(__alpha__) |
717 |
__attribute__((aligned (16))) |
718 |
#endif |
719 |
; |
720 |
HEADER *header; |
721 |
struct reslist *request = NULL; |
722 |
int rc; |
723 |
socklen_t len = sizeof(struct irc_ssaddr); |
724 |
struct irc_ssaddr lsin; |
725 |
|
726 |
rc = recvfrom(fd->fd, buf, sizeof(buf), 0, (struct sockaddr *)&lsin, &len); |
727 |
|
728 |
/* Re-schedule a read *after* recvfrom, or we'll be registering |
729 |
* interest where it'll instantly be ready for read :-) -- adrian |
730 |
*/ |
731 |
comm_setselect(fd, COMM_SELECT_READ, res_readreply, NULL, 0); |
732 |
|
733 |
/* Better to cast the sizeof instead of rc */ |
734 |
if (rc <= (int)(sizeof(HEADER))) |
735 |
return; |
736 |
|
737 |
/* |
738 |
* convert DNS reply reader from Network byte order to CPU byte order. |
739 |
*/ |
740 |
header = (HEADER *)buf; |
741 |
header->ancount = ntohs(header->ancount); |
742 |
header->qdcount = ntohs(header->qdcount); |
743 |
header->nscount = ntohs(header->nscount); |
744 |
header->arcount = ntohs(header->arcount); |
745 |
|
746 |
/* |
747 |
* check against possibly fake replies |
748 |
*/ |
749 |
if (!res_ourserver(&lsin)) |
750 |
return; |
751 |
|
752 |
/* |
753 |
* response for an id which we have already received an answer for |
754 |
* just ignore this response. |
755 |
*/ |
756 |
if (!(request = find_id(header->id))) |
757 |
return; |
758 |
|
759 |
if ((header->rcode != NO_ERRORS) || (header->ancount == 0)) |
760 |
{ |
761 |
if (header->rcode == SERVFAIL || header->rcode == NXDOMAIN) |
762 |
{ |
763 |
/* |
764 |
* If a bad error was returned, stop here and don't |
765 |
* send any more (no retries granted). |
766 |
*/ |
767 |
(*request->callback)(request->callback_ctx, NULL, NULL); |
768 |
rem_request(request); |
769 |
} |
770 |
#ifdef IPV6 |
771 |
else |
772 |
{ |
773 |
/* |
774 |
* If we havent already tried this, and we're looking up AAAA, try A |
775 |
* now |
776 |
*/ |
777 |
if (request->state == REQ_AAAA && request->type == T_AAAA) |
778 |
{ |
779 |
request->timeout += 4; |
780 |
resend_query(request); |
781 |
} |
782 |
} |
783 |
#endif |
784 |
|
785 |
return; |
786 |
} |
787 |
|
788 |
/* |
789 |
* If this fails there was an error decoding the received packet, |
790 |
* try it again and hope it works the next time. |
791 |
*/ |
792 |
if (proc_answer(request, header, buf, buf + rc)) |
793 |
{ |
794 |
if (request->type == T_PTR) |
795 |
{ |
796 |
if (request->name == NULL) |
797 |
{ |
798 |
/* |
799 |
* got a PTR response with no name, something bogus is happening |
800 |
* don't bother trying again, the client address doesn't resolve |
801 |
*/ |
802 |
(*request->callback)(request->callback_ctx, NULL, NULL); |
803 |
rem_request(request); |
804 |
return; |
805 |
} |
806 |
|
807 |
/* |
808 |
* Lookup the 'authoritative' name that we were given for the |
809 |
* ip#. |
810 |
* |
811 |
*/ |
812 |
#ifdef IPV6 |
813 |
if (request->addr.ss.ss_family == AF_INET6) |
814 |
gethost_byname_type(request->callback, request->callback_ctx, request->name, T_AAAA); |
815 |
else |
816 |
#endif |
817 |
gethost_byname_type(request->callback, request->callback_ctx, request->name, T_A); |
818 |
rem_request(request); |
819 |
} |
820 |
else |
821 |
{ |
822 |
/* |
823 |
* got a name and address response, client resolved |
824 |
*/ |
825 |
(*request->callback)(request->callback_ctx, &request->addr, request->name); |
826 |
rem_request(request); |
827 |
} |
828 |
} |
829 |
else if (!request->sent) |
830 |
{ |
831 |
/* XXX - we got a response for a query we didn't send with a valid id? |
832 |
* this should never happen, bail here and leave the client unresolved |
833 |
*/ |
834 |
assert(0); |
835 |
|
836 |
/* XXX don't leak it */ |
837 |
rem_request(request); |
838 |
} |
839 |
} |
840 |
|
841 |
void |
842 |
report_dns_servers(struct Client *source_p) |
843 |
{ |
844 |
int i; |
845 |
char ipaddr[HOSTIPLEN + 1]; |
846 |
|
847 |
for (i = 0; i < irc_nscount; i++) |
848 |
{ |
849 |
irc_getnameinfo((struct sockaddr *)&(irc_nsaddr_list[i]), |
850 |
irc_nsaddr_list[i].ss_len, ipaddr, |
851 |
sizeof(ipaddr), NULL, 0, NI_NUMERICHOST); |
852 |
sendto_one(source_p, form_str(RPL_STATSALINE), |
853 |
me.name, source_p->name, ipaddr); |
854 |
} |
855 |
} |