1 |
/* |
2 |
* A rewrite of Darren Reeds original res.c As there is nothing |
3 |
* left of Darrens original code, this is now licensed by the hybrid group. |
4 |
* (Well, some of the function names are the same, and bits of the structs..) |
5 |
* You can use it where it is useful, free even. Buy us a beer and stuff. |
6 |
* |
7 |
* The authors takes no responsibility for any damage or loss |
8 |
* of property which results from the use of this software. |
9 |
* |
10 |
* $Id$ |
11 |
* |
12 |
* July 1999 - Rewrote a bunch of stuff here. Change hostent builder code, |
13 |
* added callbacks and reference counting of returned hostents. |
14 |
* --Bleep (Thomas Helvey <tomh@inxpress.net>) |
15 |
* |
16 |
* This was all needlessly complicated for irc. Simplified. No more hostent |
17 |
* All we really care about is the IP -> hostname mappings. Thats all. |
18 |
* |
19 |
* Apr 28, 2003 --cryogen and Dianora |
20 |
*/ |
21 |
|
22 |
#include "stdinc.h" |
23 |
#include "tools.h" |
24 |
#include "client.h" |
25 |
#include "list.h" |
26 |
#include "common.h" |
27 |
#include "event.h" |
28 |
#include "irc_string.h" |
29 |
#include "sprintf_irc.h" |
30 |
#include "ircd.h" |
31 |
#include "numeric.h" |
32 |
#include "restart.h" |
33 |
#include "rng_mt.h" |
34 |
#include "fdlist.h" |
35 |
#include "fileio.h" /* for fbopen / fbclose / fbputs */ |
36 |
#include "s_bsd.h" |
37 |
#include "s_log.h" |
38 |
#include "send.h" |
39 |
#include "memory.h" |
40 |
#include "irc_res.h" |
41 |
#include "irc_reslib.h" |
42 |
#include "irc_getnameinfo.h" |
43 |
|
44 |
#if (CHAR_BIT != 8) |
45 |
#error this code needs to be able to address individual octets |
46 |
#endif |
47 |
|
48 |
static PF res_readreply; |
49 |
|
50 |
#define MAXPACKET 1024 /* rfc sez 512 but we expand names so ... */ |
51 |
#define RES_MAXALIASES 35 /* maximum aliases allowed */ |
52 |
#define RES_MAXADDRS 35 /* maximum addresses allowed */ |
53 |
#define AR_TTL 600 /* TTL in seconds for dns cache entries */ |
54 |
|
55 |
/* RFC 1104/1105 wasn't very helpful about what these fields |
56 |
* should be named, so for now, we'll just name them this way. |
57 |
* we probably should look at what named calls them or something. |
58 |
*/ |
59 |
#define TYPE_SIZE (size_t)2 |
60 |
#define CLASS_SIZE (size_t)2 |
61 |
#define TTL_SIZE (size_t)4 |
62 |
#define RDLENGTH_SIZE (size_t)2 |
63 |
#define ANSWER_FIXED_SIZE (TYPE_SIZE + CLASS_SIZE + TTL_SIZE + RDLENGTH_SIZE) |
64 |
|
65 |
typedef enum |
66 |
{ |
67 |
REQ_IDLE, /* We're doing not much at all */ |
68 |
REQ_PTR, /* Looking up a PTR */ |
69 |
REQ_A, /* Looking up an A, possibly because AAAA failed */ |
70 |
#ifdef IPV6 |
71 |
REQ_AAAA, /* Looking up an AAAA */ |
72 |
#endif |
73 |
REQ_CNAME /* We got a CNAME in response, we better get a real answer next */ |
74 |
} request_state; |
75 |
|
76 |
struct reslist |
77 |
{ |
78 |
dlink_node node; |
79 |
int id; |
80 |
int sent; /* number of requests sent */ |
81 |
request_state state; /* State the resolver machine is in */ |
82 |
time_t ttl; |
83 |
char type; |
84 |
char retries; /* retry counter */ |
85 |
char sends; /* number of sends (>1 means resent) */ |
86 |
char resend; /* send flag. 0 == dont resend */ |
87 |
time_t sentat; |
88 |
time_t timeout; |
89 |
struct irc_ssaddr addr; |
90 |
char *name; |
91 |
dns_callback_fnc callback; |
92 |
void *callback_ctx; |
93 |
}; |
94 |
|
95 |
static fde_t ResolverFileDescriptor; |
96 |
static dlink_list request_list = { NULL, NULL, 0 }; |
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 |
static struct DNSReply *make_dnsreply(struct reslist *request); |
112 |
|
113 |
extern struct irc_ssaddr irc_nsaddr_list[IRCD_MAXNS]; |
114 |
extern int irc_nscount; |
115 |
extern char irc_domain[HOSTLEN+1]; |
116 |
|
117 |
|
118 |
/* |
119 |
* int |
120 |
* res_ourserver(inp) |
121 |
* looks up "inp" in irc_nsaddr_list[] |
122 |
* returns: |
123 |
* 0 : not found |
124 |
* >0 : found |
125 |
* author: |
126 |
* paul vixie, 29may94 |
127 |
* revised for ircd, cryogen(stu) may03 |
128 |
*/ |
129 |
static int |
130 |
res_ourserver(const struct irc_ssaddr *inp) |
131 |
{ |
132 |
#ifdef IPV6 |
133 |
const struct sockaddr_in6 *v6; |
134 |
const struct sockaddr_in6 *v6in = (const struct sockaddr_in6 *)inp; |
135 |
#endif |
136 |
const struct sockaddr_in *v4; |
137 |
const struct sockaddr_in *v4in = (const struct sockaddr_in *)inp; |
138 |
int ns; |
139 |
|
140 |
for (ns = 0; ns < irc_nscount; ns++) |
141 |
{ |
142 |
const struct irc_ssaddr *srv = &irc_nsaddr_list[ns]; |
143 |
#ifdef IPV6 |
144 |
v6 = (const struct sockaddr_in6 *)srv; |
145 |
#endif |
146 |
v4 = (const struct sockaddr_in *)srv; |
147 |
|
148 |
/* could probably just memcmp(srv, inp, srv.ss_len) here |
149 |
* but we'll air on the side of caution - stu |
150 |
* |
151 |
*/ |
152 |
switch (srv->ss.ss_family) |
153 |
{ |
154 |
#ifdef IPV6 |
155 |
case AF_INET6: |
156 |
if (srv->ss.ss_family == inp->ss.ss_family) |
157 |
if (v6->sin6_port == v6in->sin6_port) |
158 |
if ((memcmp(&v6->sin6_addr.s6_addr, &v6in->sin6_addr.s6_addr, |
159 |
sizeof(struct in6_addr)) == 0) || |
160 |
(memcmp(&v6->sin6_addr.s6_addr, &in6addr_any, |
161 |
sizeof(struct in6_addr)) == 0)) |
162 |
return(1); |
163 |
break; |
164 |
#endif |
165 |
case AF_INET: |
166 |
if (srv->ss.ss_family == inp->ss.ss_family) |
167 |
if (v4->sin_port == v4in->sin_port) |
168 |
if ((v4->sin_addr.s_addr == INADDR_ANY) || |
169 |
(v4->sin_addr.s_addr == v4in->sin_addr.s_addr)) |
170 |
return(1); |
171 |
break; |
172 |
default: |
173 |
break; |
174 |
} |
175 |
} |
176 |
|
177 |
return(0); |
178 |
} |
179 |
|
180 |
/* |
181 |
* timeout_query_list - Remove queries from the list which have been |
182 |
* there too long without being resolved. |
183 |
*/ |
184 |
static time_t |
185 |
timeout_query_list(time_t now) |
186 |
{ |
187 |
dlink_node *ptr; |
188 |
dlink_node *next_ptr; |
189 |
struct reslist *request; |
190 |
time_t next_time = 0; |
191 |
time_t timeout = 0; |
192 |
|
193 |
DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head) |
194 |
{ |
195 |
request = ptr->data; |
196 |
timeout = request->sentat + request->timeout; |
197 |
|
198 |
if (now >= timeout) |
199 |
{ |
200 |
if (--request->retries <= 0) |
201 |
{ |
202 |
(*request->callback)(request->callback_ctx, NULL, NULL); |
203 |
rem_request(request); |
204 |
continue; |
205 |
} |
206 |
else |
207 |
{ |
208 |
request->sentat = now; |
209 |
request->timeout += request->timeout; |
210 |
resend_query(request); |
211 |
} |
212 |
} |
213 |
|
214 |
if ((next_time == 0) || timeout < next_time) |
215 |
{ |
216 |
next_time = timeout; |
217 |
} |
218 |
} |
219 |
|
220 |
return((next_time > now) ? next_time : (now + AR_TTL)); |
221 |
} |
222 |
|
223 |
/* |
224 |
* timeout_resolver - check request list |
225 |
*/ |
226 |
static void |
227 |
timeout_resolver(void *notused) |
228 |
{ |
229 |
timeout_query_list(CurrentTime); |
230 |
} |
231 |
|
232 |
/* |
233 |
* start_resolver - do everything we need to read the resolv.conf file |
234 |
* and initialize the resolver file descriptor if needed |
235 |
*/ |
236 |
static void |
237 |
start_resolver(void) |
238 |
{ |
239 |
irc_res_init(); |
240 |
|
241 |
if (!ResolverFileDescriptor.flags.open) |
242 |
{ |
243 |
if (comm_open(&ResolverFileDescriptor, irc_nsaddr_list[0].ss.ss_family, |
244 |
SOCK_DGRAM, 0, "Resolver socket") == -1) |
245 |
return; |
246 |
|
247 |
/* At the moment, the resolver FD data is global .. */ |
248 |
comm_setselect(&ResolverFileDescriptor, COMM_SELECT_READ, |
249 |
res_readreply, NULL, 0); |
250 |
eventAdd("timeout_resolver", timeout_resolver, NULL, 1); |
251 |
} |
252 |
} |
253 |
|
254 |
/* |
255 |
* init_resolver - initialize resolver and resolver library |
256 |
*/ |
257 |
void |
258 |
init_resolver(void) |
259 |
{ |
260 |
memset(&ResolverFileDescriptor, 0, sizeof(fde_t)); |
261 |
start_resolver(); |
262 |
} |
263 |
|
264 |
/* |
265 |
* restart_resolver - reread resolv.conf, reopen socket |
266 |
*/ |
267 |
void |
268 |
restart_resolver(void) |
269 |
{ |
270 |
fd_close(&ResolverFileDescriptor); |
271 |
eventDelete(timeout_resolver, NULL); /* -ddosen */ |
272 |
start_resolver(); |
273 |
} |
274 |
|
275 |
/* |
276 |
* add_local_domain - Add the domain to hostname, if it is missing |
277 |
* (as suggested by eps@TOASTER.SFSU.EDU) |
278 |
*/ |
279 |
void |
280 |
add_local_domain(char *hname, size_t size) |
281 |
{ |
282 |
/* try to fix up unqualified names |
283 |
*/ |
284 |
if (strchr(hname, '.') == NULL) |
285 |
{ |
286 |
if (irc_domain[0]) |
287 |
{ |
288 |
size_t len = strlen(hname); |
289 |
|
290 |
if ((strlen(irc_domain) + len + 2) < size) |
291 |
{ |
292 |
hname[len++] = '.'; |
293 |
strcpy(hname + len, irc_domain); |
294 |
} |
295 |
} |
296 |
} |
297 |
} |
298 |
|
299 |
/* |
300 |
* rem_request - remove a request from the list. |
301 |
* This must also free any memory that has been allocated for |
302 |
* temporary storage of DNS results. |
303 |
*/ |
304 |
static void |
305 |
rem_request(struct reslist *request) |
306 |
{ |
307 |
dlinkDelete(&request->node, &request_list); |
308 |
MyFree(request->name); |
309 |
MyFree(request); |
310 |
} |
311 |
|
312 |
/* |
313 |
* make_request - Create a DNS request record for the server. |
314 |
*/ |
315 |
static struct reslist * |
316 |
make_request(dns_callback_fnc callback, void *ctx) |
317 |
{ |
318 |
struct reslist *request; |
319 |
|
320 |
request = (struct reslist *)MyMalloc(sizeof(struct reslist)); |
321 |
|
322 |
request->sentat = CurrentTime; |
323 |
request->retries = 3; |
324 |
request->resend = 1; |
325 |
request->timeout = 4; /* start at 4 and exponential inc. */ |
326 |
request->state = REQ_IDLE; |
327 |
request->callback = callback; |
328 |
request->callback_ctx = ctx; |
329 |
|
330 |
dlinkAdd(request, &request->node, &request_list); |
331 |
return(request); |
332 |
} |
333 |
|
334 |
/* |
335 |
* delete_resolver_queries - cleanup outstanding queries |
336 |
* for which there no longer exist clients or conf lines. |
337 |
*/ |
338 |
void |
339 |
delete_resolver_queries(const void *vptr) |
340 |
{ |
341 |
dlink_node *ptr; |
342 |
dlink_node *next_ptr; |
343 |
struct reslist *request; |
344 |
|
345 |
DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head) |
346 |
{ |
347 |
if ((request = ptr->data) != NULL) |
348 |
{ |
349 |
if (request->callback_ctx == vptr) |
350 |
rem_request(request); |
351 |
} |
352 |
} |
353 |
} |
354 |
|
355 |
/* |
356 |
* send_res_msg - sends msg to all nameservers found in the "_res" structure. |
357 |
* This should reflect /etc/resolv.conf. We will get responses |
358 |
* which arent needed but is easier than checking to see if nameserver |
359 |
* isnt present. Returns number of messages successfully sent to |
360 |
* nameservers or -1 if no successful sends. |
361 |
*/ |
362 |
static int |
363 |
send_res_msg(const char *msg, int len, int rcount) |
364 |
{ |
365 |
int i; |
366 |
int sent = 0; |
367 |
int max_queries = IRCD_MIN(irc_nscount, rcount); |
368 |
|
369 |
/* RES_PRIMARY option is not implemented |
370 |
* if (res.options & RES_PRIMARY || 0 == max_queries) |
371 |
*/ |
372 |
if (max_queries == 0) |
373 |
max_queries = 1; |
374 |
|
375 |
for (i = 0; i < max_queries; i++) |
376 |
{ |
377 |
if (sendto(ResolverFileDescriptor.fd, msg, len, 0, |
378 |
(struct sockaddr*)&(irc_nsaddr_list[i]), |
379 |
irc_nsaddr_list[i].ss_len) == len) |
380 |
++sent; |
381 |
} |
382 |
|
383 |
return(sent); |
384 |
} |
385 |
|
386 |
/* |
387 |
* find_id - find a dns request id (id is determined by dn_mkquery) |
388 |
*/ |
389 |
static struct reslist * |
390 |
find_id(int id) |
391 |
{ |
392 |
dlink_node *ptr; |
393 |
struct reslist *request; |
394 |
|
395 |
DLINK_FOREACH(ptr, request_list.head) |
396 |
{ |
397 |
request = ptr->data; |
398 |
|
399 |
if (request->id == id) |
400 |
return(request); |
401 |
} |
402 |
|
403 |
return(NULL); |
404 |
} |
405 |
|
406 |
/* |
407 |
* gethost_byname_type - get host address from name |
408 |
* |
409 |
*/ |
410 |
void |
411 |
gethost_byname_type(dns_callback_fnc callback, void *ctx, const char *name, int type) |
412 |
{ |
413 |
assert(name != 0); |
414 |
do_query_name(callback, ctx, name, NULL, type); |
415 |
} |
416 |
|
417 |
/* |
418 |
* gethost_byname - wrapper for _type - send T_AAAA first if IPV6 supported |
419 |
*/ |
420 |
void |
421 |
gethost_byname(dns_callback_fnc callback, void *ctx, const char *name) |
422 |
{ |
423 |
#ifdef IPV6 |
424 |
gethost_byname_type(callback, ctx, name, T_AAAA); |
425 |
#else |
426 |
gethost_byname_type(callback, ctx, name, T_A); |
427 |
#endif |
428 |
} |
429 |
|
430 |
/* |
431 |
* gethost_byaddr - get host name from address |
432 |
*/ |
433 |
void |
434 |
gethost_byaddr(dns_callback_fnc callback, void *ctx, const struct irc_ssaddr *addr) |
435 |
{ |
436 |
do_query_number(callback, ctx, addr, NULL); |
437 |
} |
438 |
|
439 |
/* |
440 |
* do_query_name - nameserver lookup name |
441 |
*/ |
442 |
static void |
443 |
do_query_name(dns_callback_fnc callback, void *ctx, const char *name, |
444 |
struct reslist *request, int type) |
445 |
{ |
446 |
char host_name[HOSTLEN + 1]; |
447 |
|
448 |
strlcpy(host_name, name, HOSTLEN + 1); |
449 |
add_local_domain(host_name, HOSTLEN + 1); |
450 |
|
451 |
if (request == NULL) |
452 |
{ |
453 |
request = make_request(callback, ctx); |
454 |
request->name = MyMalloc(strlen(host_name) + 1); |
455 |
request->type = type; |
456 |
strcpy(request->name, host_name); |
457 |
#ifdef IPV6 |
458 |
if (type != T_A) |
459 |
request->state = REQ_AAAA; |
460 |
else |
461 |
#endif |
462 |
request->state = REQ_A; |
463 |
} |
464 |
|
465 |
request->type = type; |
466 |
query_name(host_name, C_IN, type, request); |
467 |
} |
468 |
|
469 |
/* |
470 |
* do_query_number - Use this to do reverse IP# lookups. |
471 |
*/ |
472 |
static void |
473 |
do_query_number(dns_callback_fnc callback, void *ctx, |
474 |
const struct irc_ssaddr *addr, |
475 |
struct reslist *request) |
476 |
{ |
477 |
char ipbuf[128]; |
478 |
const unsigned char *cp; |
479 |
|
480 |
if (addr->ss.ss_family == AF_INET) |
481 |
{ |
482 |
const struct sockaddr_in *v4 = (const struct sockaddr_in *)addr; |
483 |
cp = (const unsigned char*)&v4->sin_addr.s_addr; |
484 |
|
485 |
ircsprintf(ipbuf, "%u.%u.%u.%u.in-addr.arpa.", |
486 |
(unsigned int)(cp[3]), (unsigned int)(cp[2]), |
487 |
(unsigned int)(cp[1]), (unsigned int)(cp[0])); |
488 |
} |
489 |
#ifdef IPV6 |
490 |
else if (addr->ss.ss_family == AF_INET6) |
491 |
{ |
492 |
const struct sockaddr_in6 *v6 = (const struct sockaddr_in6 *)addr; |
493 |
cp = (const unsigned char *)&v6->sin6_addr.s6_addr; |
494 |
|
495 |
sprintf(ipbuf, "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x." |
496 |
"%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.ip6.arpa.", |
497 |
(unsigned int)(cp[15]&0xf), (unsigned int)(cp[15]>>4), |
498 |
(unsigned int)(cp[14]&0xf), (unsigned int)(cp[14]>>4), |
499 |
(unsigned int)(cp[13]&0xf), (unsigned int)(cp[13]>>4), |
500 |
(unsigned int)(cp[12]&0xf), (unsigned int)(cp[12]>>4), |
501 |
(unsigned int)(cp[11]&0xf), (unsigned int)(cp[11]>>4), |
502 |
(unsigned int)(cp[10]&0xf), (unsigned int)(cp[10]>>4), |
503 |
(unsigned int)(cp[9]&0xf), (unsigned int)(cp[9]>>4), |
504 |
(unsigned int)(cp[8]&0xf), (unsigned int)(cp[8]>>4), |
505 |
(unsigned int)(cp[7]&0xf), (unsigned int)(cp[7]>>4), |
506 |
(unsigned int)(cp[6]&0xf), (unsigned int)(cp[6]>>4), |
507 |
(unsigned int)(cp[5]&0xf), (unsigned int)(cp[5]>>4), |
508 |
(unsigned int)(cp[4]&0xf), (unsigned int)(cp[4]>>4), |
509 |
(unsigned int)(cp[3]&0xf), (unsigned int)(cp[3]>>4), |
510 |
(unsigned int)(cp[2]&0xf), (unsigned int)(cp[2]>>4), |
511 |
(unsigned int)(cp[1]&0xf), (unsigned int)(cp[1]>>4), |
512 |
(unsigned int)(cp[0]&0xf), (unsigned int)(cp[0]>>4)); |
513 |
} |
514 |
#endif |
515 |
if (request == NULL) |
516 |
{ |
517 |
request = make_request(callback, ctx); |
518 |
request->type = T_PTR; |
519 |
memcpy(&request->addr, addr, sizeof(struct irc_ssaddr)); |
520 |
request->name = MyMalloc(HOSTLEN + 1); |
521 |
} |
522 |
|
523 |
query_name(ipbuf, C_IN, T_PTR, request); |
524 |
} |
525 |
|
526 |
/* |
527 |
* query_name - generate a query based on class, type and name. |
528 |
*/ |
529 |
static void |
530 |
query_name(const char *name, int query_class, int type, |
531 |
struct reslist *request) |
532 |
{ |
533 |
char buf[MAXPACKET]; |
534 |
int request_len = 0; |
535 |
|
536 |
memset(buf, 0, sizeof(buf)); |
537 |
|
538 |
if ((request_len = irc_res_mkquery(name, query_class, type, |
539 |
(unsigned char *)buf, sizeof(buf))) > 0) |
540 |
{ |
541 |
HEADER *header = (HEADER *)buf; |
542 |
|
543 |
/* |
544 |
* generate an unique id |
545 |
* NOTE: we don't have to worry about converting this to and from |
546 |
* network byte order, the nameserver does not interpret this value |
547 |
* and returns it unchanged |
548 |
*/ |
549 |
do |
550 |
header->id = (header->id + genrand_int32()) & 0xffff; |
551 |
while (find_id(header->id)); |
552 |
|
553 |
request->id = header->id; |
554 |
++request->sends; |
555 |
|
556 |
request->sent += send_res_msg(buf, request_len, request->sends); |
557 |
} |
558 |
} |
559 |
|
560 |
static void |
561 |
resend_query(struct reslist *request) |
562 |
{ |
563 |
if (request->resend == 0) |
564 |
return; |
565 |
|
566 |
switch (request->type) |
567 |
{ |
568 |
case T_PTR: |
569 |
do_query_number(NULL, NULL, &request->addr, request); |
570 |
break; |
571 |
case T_A: |
572 |
do_query_name(NULL, NULL, request->name, request, request->type); |
573 |
break; |
574 |
#ifdef IPV6 |
575 |
case T_AAAA: |
576 |
/* didnt work, try A */ |
577 |
if (request->state == REQ_AAAA) |
578 |
do_query_name(NULL, NULL, request->name, request, T_A); |
579 |
#endif |
580 |
default: |
581 |
break; |
582 |
} |
583 |
} |
584 |
|
585 |
/* |
586 |
* proc_answer - process name server reply |
587 |
*/ |
588 |
static int |
589 |
proc_answer(struct reslist *request, HEADER* header, char* buf, char* eob) |
590 |
{ |
591 |
char hostbuf[HOSTLEN + 100]; /* working buffer */ |
592 |
unsigned char *current; /* current position in buf */ |
593 |
int query_class; /* answer class */ |
594 |
int type; /* answer type */ |
595 |
int n; /* temp count */ |
596 |
int rd_length; |
597 |
struct sockaddr_in *v4; /* conversion */ |
598 |
#ifdef IPV6 |
599 |
struct sockaddr_in6 *v6; |
600 |
#endif |
601 |
current = (unsigned char *)buf + sizeof(HEADER); |
602 |
|
603 |
for (; header->qdcount > 0; --header->qdcount) |
604 |
{ |
605 |
if ((n = irc_dn_skipname(current, (unsigned char *)eob)) < 0) |
606 |
break; |
607 |
|
608 |
current += (size_t) n + QFIXEDSZ; |
609 |
} |
610 |
|
611 |
/* |
612 |
* process each answer sent to us blech. |
613 |
*/ |
614 |
while (header->ancount > 0 && (char *)current < eob) |
615 |
{ |
616 |
header->ancount--; |
617 |
|
618 |
n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current, |
619 |
hostbuf, sizeof(hostbuf)); |
620 |
|
621 |
if (n < 0) |
622 |
{ |
623 |
/* |
624 |
* broken message |
625 |
*/ |
626 |
return(0); |
627 |
} |
628 |
else if (n == 0) |
629 |
{ |
630 |
/* |
631 |
* no more answers left |
632 |
*/ |
633 |
return(0); |
634 |
} |
635 |
|
636 |
hostbuf[HOSTLEN] = '\0'; |
637 |
|
638 |
/* With Address arithmetic you have to be very anal |
639 |
* this code was not working on alpha due to that |
640 |
* (spotted by rodder/jailbird/dianora) |
641 |
*/ |
642 |
current += (size_t) n; |
643 |
|
644 |
if (!(((char *)current + ANSWER_FIXED_SIZE) < eob)) |
645 |
break; |
646 |
|
647 |
type = irc_ns_get16(current); |
648 |
current += TYPE_SIZE; |
649 |
|
650 |
query_class = irc_ns_get16(current); |
651 |
current += CLASS_SIZE; |
652 |
|
653 |
request->ttl = irc_ns_get32(current); |
654 |
current += TTL_SIZE; |
655 |
|
656 |
rd_length = irc_ns_get16(current); |
657 |
current += RDLENGTH_SIZE; |
658 |
|
659 |
/* |
660 |
* Wait to set request->type until we verify this structure |
661 |
*/ |
662 |
switch (type) |
663 |
{ |
664 |
case T_A: |
665 |
if (request->type != T_A) |
666 |
return(0); |
667 |
|
668 |
/* |
669 |
* check for invalid rd_length or too many addresses |
670 |
*/ |
671 |
if (rd_length != sizeof(struct in_addr)) |
672 |
return(0); |
673 |
v4 = (struct sockaddr_in *)&request->addr; |
674 |
request->addr.ss_len = sizeof(struct sockaddr_in); |
675 |
v4->sin_family = AF_INET; |
676 |
memcpy(&v4->sin_addr, current, sizeof(struct in_addr)); |
677 |
return(1); |
678 |
break; |
679 |
#ifdef IPV6 |
680 |
case T_AAAA: |
681 |
if (request->type != T_AAAA) |
682 |
return(0); |
683 |
if (rd_length != sizeof(struct in6_addr)) |
684 |
return(0); |
685 |
request->addr.ss_len = sizeof(struct sockaddr_in6); |
686 |
v6 = (struct sockaddr_in6 *)&request->addr; |
687 |
v6->sin6_family = AF_INET6; |
688 |
memcpy(&v6->sin6_addr, current, sizeof(struct in6_addr)); |
689 |
return(1); |
690 |
break; |
691 |
#endif |
692 |
case T_PTR: |
693 |
if (request->type != T_PTR) |
694 |
return(0); |
695 |
n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, |
696 |
current, hostbuf, sizeof(hostbuf)); |
697 |
if (n < 0) |
698 |
return(0); /* broken message */ |
699 |
else if (n == 0) |
700 |
return(0); /* no more answers left */ |
701 |
|
702 |
strlcpy(request->name, hostbuf, HOSTLEN + 1); |
703 |
|
704 |
return(1); |
705 |
break; |
706 |
case T_CNAME: /* first check we already havent started looking |
707 |
into a cname */ |
708 |
if (request->type != T_PTR) |
709 |
return(0); |
710 |
|
711 |
if (request->state == REQ_CNAME) |
712 |
{ |
713 |
n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, |
714 |
current, hostbuf, sizeof(hostbuf)); |
715 |
|
716 |
if (n < 0) |
717 |
return(0); |
718 |
return(1); |
719 |
} |
720 |
|
721 |
request->state = REQ_CNAME; |
722 |
current += rd_length; |
723 |
break; |
724 |
|
725 |
default: |
726 |
/* XXX I'd rather just throw away the entire bogus thing |
727 |
* but its possible its just a broken nameserver with still |
728 |
* valid answers. But lets do some rudimentary logging for now... |
729 |
*/ |
730 |
ilog(L_ERROR, "irc_res.c bogus type %d", type); |
731 |
break; |
732 |
} |
733 |
} |
734 |
|
735 |
return(1); |
736 |
} |
737 |
|
738 |
/* |
739 |
* res_readreply - read a dns reply from the nameserver and process it. |
740 |
*/ |
741 |
static void |
742 |
res_readreply(fde_t *fd, void *data) |
743 |
{ |
744 |
char buf[sizeof(HEADER) + MAXPACKET] |
745 |
/* Sparc and alpha need 16bit-alignment for accessing header->id |
746 |
* (which is uint16_t). Because of the header = (HEADER*) buf; |
747 |
* lateron, this is neeeded. --FaUl |
748 |
*/ |
749 |
#if defined(__sparc__) || defined(__alpha__) |
750 |
__attribute__((aligned (16))) |
751 |
#endif |
752 |
; |
753 |
HEADER *header; |
754 |
struct reslist *request = NULL; |
755 |
int rc; |
756 |
int answer_count; |
757 |
socklen_t len = sizeof(struct irc_ssaddr); |
758 |
struct irc_ssaddr lsin; |
759 |
|
760 |
rc = recvfrom(fd->fd, buf, sizeof(buf), 0, (struct sockaddr *)&lsin, &len); |
761 |
|
762 |
/* Re-schedule a read *after* recvfrom, or we'll be registering |
763 |
* interest where it'll instantly be ready for read :-) -- adrian |
764 |
*/ |
765 |
comm_setselect(fd, COMM_SELECT_READ, res_readreply, NULL, 0); |
766 |
|
767 |
/* Better to cast the sizeof instead of rc */ |
768 |
if (rc <= (int)(sizeof(HEADER))) |
769 |
return; |
770 |
|
771 |
/* |
772 |
* convert DNS reply reader from Network byte order to CPU byte order. |
773 |
*/ |
774 |
header = (HEADER *)buf; |
775 |
header->ancount = ntohs(header->ancount); |
776 |
header->qdcount = ntohs(header->qdcount); |
777 |
header->nscount = ntohs(header->nscount); |
778 |
header->arcount = ntohs(header->arcount); |
779 |
|
780 |
/* |
781 |
* response for an id which we have already received an answer for |
782 |
* just ignore this response. |
783 |
*/ |
784 |
if (0 == (request = find_id(header->id))) |
785 |
return; |
786 |
|
787 |
/* |
788 |
* check against possibly fake replies |
789 |
*/ |
790 |
if (!res_ourserver(&lsin)) |
791 |
return; |
792 |
|
793 |
if ((header->rcode != NO_ERRORS) || (header->ancount == 0)) |
794 |
{ |
795 |
if (header->rcode == SERVFAIL || header->rcode == NXDOMAIN) |
796 |
{ |
797 |
/* |
798 |
* If a bad error was returned, stop here and don't |
799 |
* send any more (no retries granted). |
800 |
*/ |
801 |
(*request->callback)(request->callback_ctx, NULL, NULL); |
802 |
rem_request(request); |
803 |
} |
804 |
#ifdef IPV6 |
805 |
else |
806 |
{ |
807 |
/* |
808 |
* If we havent already tried this, and we're looking up AAAA, try A |
809 |
* now |
810 |
*/ |
811 |
if (request->state == REQ_AAAA && request->type == T_AAAA) |
812 |
{ |
813 |
request->timeout += 4; |
814 |
resend_query(request); |
815 |
} |
816 |
} |
817 |
#endif |
818 |
|
819 |
return; |
820 |
} |
821 |
|
822 |
/* |
823 |
* If this fails there was an error decoding the received packet, |
824 |
* try it again and hope it works the next time. |
825 |
*/ |
826 |
answer_count = proc_answer(request, header, buf, buf + rc); |
827 |
|
828 |
if (answer_count) |
829 |
{ |
830 |
if (request->type == T_PTR) |
831 |
{ |
832 |
if (request->name == NULL) |
833 |
{ |
834 |
/* |
835 |
* got a PTR response with no name, something bogus is happening |
836 |
* don't bother trying again, the client address doesn't resolve |
837 |
*/ |
838 |
(*request->callback)(request->callback_ctx, NULL, NULL); |
839 |
rem_request(request); |
840 |
return; |
841 |
} |
842 |
|
843 |
/* |
844 |
* Lookup the 'authoritative' name that we were given for the |
845 |
* ip#. |
846 |
* |
847 |
*/ |
848 |
#ifdef IPV6 |
849 |
if (request->addr.ss.ss_family == AF_INET6) |
850 |
gethost_byname_type(request->callback, request->callback_ctx, request->name, T_AAAA); |
851 |
else |
852 |
#endif |
853 |
gethost_byname_type(request->callback, request->callback_ctx, request->name, T_A); |
854 |
rem_request(request); |
855 |
} |
856 |
else |
857 |
{ |
858 |
/* |
859 |
* got a name and address response, client resolved |
860 |
*/ |
861 |
(*request->callback)(request->callback_ctx, &request->addr, request->name); |
862 |
rem_request(request); |
863 |
} |
864 |
} |
865 |
else if (!request->sent) |
866 |
{ |
867 |
/* XXX - we got a response for a query we didn't send with a valid id? |
868 |
* this should never happen, bail here and leave the client unresolved |
869 |
*/ |
870 |
assert(0); |
871 |
|
872 |
/* XXX don't leak it */ |
873 |
rem_request(request); |
874 |
} |
875 |
} |
876 |
|
877 |
void |
878 |
report_dns_servers(struct Client *source_p) |
879 |
{ |
880 |
int i; |
881 |
char ipaddr[HOSTIPLEN + 1]; |
882 |
|
883 |
for (i = 0; i < irc_nscount; i++) |
884 |
{ |
885 |
irc_getnameinfo((struct sockaddr *)&(irc_nsaddr_list[i]), |
886 |
irc_nsaddr_list[i].ss_len, ipaddr, |
887 |
sizeof(ipaddr), NULL, 0, NI_NUMERICHOST); |
888 |
sendto_one(source_p, form_str(RPL_STATSALINE), |
889 |
me.name, source_p->name, ipaddr); |
890 |
} |
891 |
} |