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 "common.h" |
24 |
#include "reslib.h" |
25 |
|
26 |
#if (CHAR_BIT != 8) |
27 |
#error this code needs to be able to address individual octets |
28 |
#endif |
29 |
|
30 |
static PF res_readreply; |
31 |
|
32 |
#define MAXPACKET 1024 /* rfc sez 512 but we expand names so ... */ |
33 |
#define RES_MAXALIASES 35 /* maximum aliases allowed */ |
34 |
#define RES_MAXADDRS 35 /* maximum addresses allowed */ |
35 |
#define AR_TTL 600 /* TTL in seconds for dns cache entries */ |
36 |
|
37 |
/* RFC 1104/1105 wasn't very helpful about what these fields |
38 |
* should be named, so for now, we'll just name them this way. |
39 |
* we probably should look at what named calls them or something. |
40 |
*/ |
41 |
#define TYPE_SIZE (size_t)2 |
42 |
#define CLASS_SIZE (size_t)2 |
43 |
#define TTL_SIZE (size_t)4 |
44 |
#define RDLENGTH_SIZE (size_t)2 |
45 |
#define ANSWER_FIXED_SIZE (TYPE_SIZE + CLASS_SIZE + TTL_SIZE + RDLENGTH_SIZE) |
46 |
|
47 |
typedef enum |
48 |
{ |
49 |
REQ_IDLE, /* We're doing not much at all */ |
50 |
REQ_PTR, /* Looking up a PTR */ |
51 |
REQ_A, /* Looking up an A, possibly because AAAA failed */ |
52 |
#ifdef IPV6 |
53 |
REQ_AAAA, /* Looking up an AAAA */ |
54 |
#endif |
55 |
REQ_CNAME, /* We got a CNAME in response, we better get a real answer next */ |
56 |
REQ_INT /* ip6.arpa failed, falling back to ip6.int */ |
57 |
} request_state; |
58 |
|
59 |
struct reslist |
60 |
{ |
61 |
dlink_node node; |
62 |
int id; |
63 |
int sent; /* number of requests sent */ |
64 |
request_state state; /* State the resolver machine is in */ |
65 |
time_t ttl; |
66 |
char type; |
67 |
char retries; /* retry counter */ |
68 |
char sends; /* number of sends (>1 means resent) */ |
69 |
char resend; /* send flag. 0 == dont resend */ |
70 |
time_t sentat; |
71 |
time_t timeout; |
72 |
struct irc_ssaddr addr; |
73 |
char *name; |
74 |
struct DNSQuery *query; /* query callback for this request */ |
75 |
}; |
76 |
|
77 |
static fde_t ResolverFileDescriptor; |
78 |
static dlink_list request_list = { NULL, NULL, 0 }; |
79 |
|
80 |
static void rem_request(struct reslist *request); |
81 |
static struct reslist *make_request(struct DNSQuery *query); |
82 |
static void do_query_name(struct DNSQuery *query, |
83 |
const char* name, struct reslist *request, int); |
84 |
static void do_query_number(struct DNSQuery *query, |
85 |
const struct irc_ssaddr *, |
86 |
struct reslist *request); |
87 |
static void query_name(const char *name, int query_class, int query_type, |
88 |
struct reslist *request); |
89 |
static int send_res_msg(const char *buf, int len, int count); |
90 |
static void resend_query(struct reslist *request); |
91 |
static int proc_answer(struct reslist *request, HEADER *header, char *, char *); |
92 |
static struct reslist *find_id(int id); |
93 |
static struct DNSReply *make_dnsreply(struct reslist *request); |
94 |
|
95 |
extern struct irc_ssaddr irc_nsaddr_list[IRCD_MAXNS]; |
96 |
extern int irc_nscount; |
97 |
extern char irc_domain[HOSTLEN+1]; |
98 |
|
99 |
|
100 |
/* |
101 |
* int |
102 |
* res_ourserver(inp) |
103 |
* looks up "inp" in irc_nsaddr_list[] |
104 |
* returns: |
105 |
* 0 : not found |
106 |
* >0 : found |
107 |
* author: |
108 |
* paul vixie, 29may94 |
109 |
* revised for ircd, cryogen(stu) may03 |
110 |
*/ |
111 |
static int |
112 |
res_ourserver(const struct irc_ssaddr *inp) |
113 |
{ |
114 |
#ifdef IPV6 |
115 |
struct sockaddr_in6 *v6; |
116 |
struct sockaddr_in6 *v6in = (struct sockaddr_in6 *)inp; |
117 |
#endif |
118 |
struct sockaddr_in *v4; |
119 |
struct sockaddr_in *v4in = (struct sockaddr_in *)inp; |
120 |
int ns; |
121 |
|
122 |
for (ns = 0; ns < irc_nscount; ns++) |
123 |
{ |
124 |
const struct irc_ssaddr *srv = &irc_nsaddr_list[ns]; |
125 |
#ifdef IPV6 |
126 |
v6 = (struct sockaddr_in6 *)srv; |
127 |
#endif |
128 |
v4 = (struct sockaddr_in *)srv; |
129 |
|
130 |
/* could probably just memcmp(srv, inp, srv.ss_len) here |
131 |
* but we'll air on the side of caution - stu |
132 |
* |
133 |
*/ |
134 |
switch (srv->ss.ss_family) |
135 |
{ |
136 |
#ifdef IPV6 |
137 |
case AF_INET6: |
138 |
if (srv->ss.ss_family == inp->ss.ss_family) |
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; |
146 |
#endif |
147 |
case AF_INET: |
148 |
if (srv->ss.ss_family == inp->ss.ss_family) |
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; |
156 |
} |
157 |
} |
158 |
|
159 |
return 0; |
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 |
167 |
timeout_query_list(time_t now) |
168 |
{ |
169 |
dlink_node *ptr; |
170 |
dlink_node *next_ptr; |
171 |
struct reslist *request; |
172 |
time_t next_time = 0; |
173 |
time_t timeout = 0; |
174 |
|
175 |
DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head) |
176 |
{ |
177 |
request = ptr->data; |
178 |
timeout = request->sentat + request->timeout; |
179 |
|
180 |
if (now >= timeout) |
181 |
{ |
182 |
if (--request->retries <= 0) |
183 |
{ |
184 |
(*request->query->callback)(request->query->ptr, NULL); |
185 |
rem_request(request); |
186 |
continue; |
187 |
} |
188 |
else |
189 |
{ |
190 |
request->sentat = now; |
191 |
request->timeout += request->timeout; |
192 |
resend_query(request); |
193 |
} |
194 |
} |
195 |
|
196 |
if ((next_time == 0) || timeout < next_time) |
197 |
{ |
198 |
next_time = timeout; |
199 |
} |
200 |
} |
201 |
|
202 |
return (next_time > now) ? next_time : (now + AR_TTL); |
203 |
} |
204 |
|
205 |
/* |
206 |
* timeout_resolver - check request list |
207 |
*/ |
208 |
static void |
209 |
timeout_resolver(void *notused) |
210 |
{ |
211 |
timeout_query_list(CurrentTime); |
212 |
} |
213 |
|
214 |
/* |
215 |
* start_resolver - do everything we need to read the resolv.conf file |
216 |
* and initialize the resolver file descriptor if needed |
217 |
*/ |
218 |
static void |
219 |
start_resolver(void) |
220 |
{ |
221 |
irc_res_init(); |
222 |
|
223 |
if (!ResolverFileDescriptor.flags.open) |
224 |
{ |
225 |
if (comm_open(&ResolverFileDescriptor, irc_nsaddr_list[0].ss.ss_family, |
226 |
SOCK_DGRAM, 0, "Resolver socket") == -1) |
227 |
return; |
228 |
|
229 |
/* At the moment, the resolver FD data is global .. */ |
230 |
comm_setselect(&ResolverFileDescriptor, COMM_SELECT_READ, |
231 |
res_readreply, NULL, 0); |
232 |
eventAdd("timeout_resolver", timeout_resolver, NULL, 1); |
233 |
} |
234 |
} |
235 |
|
236 |
/* |
237 |
* init_resolver - initialize resolver and resolver library |
238 |
*/ |
239 |
void |
240 |
init_resolver(void) |
241 |
{ |
242 |
#ifdef HAVE_SRAND48 |
243 |
srand48(CurrentTime); |
244 |
#endif |
245 |
memset(&ResolverFileDescriptor, 0, sizeof(fde_t)); |
246 |
start_resolver(); |
247 |
} |
248 |
|
249 |
/* |
250 |
* restart_resolver - reread resolv.conf, reopen socket |
251 |
*/ |
252 |
void |
253 |
restart_resolver(void) |
254 |
{ |
255 |
fd_close(&ResolverFileDescriptor); |
256 |
eventDelete(timeout_resolver, NULL); /* -ddosen */ |
257 |
start_resolver(); |
258 |
} |
259 |
|
260 |
/* |
261 |
* add_local_domain - Add the domain to hostname, if it is missing |
262 |
* (as suggested by eps@TOASTER.SFSU.EDU) |
263 |
*/ |
264 |
void |
265 |
add_local_domain(char *hname, size_t size) |
266 |
{ |
267 |
/* try to fix up unqualified names |
268 |
*/ |
269 |
if (strchr(hname, '.') == NULL) |
270 |
{ |
271 |
if (irc_domain[0]) |
272 |
{ |
273 |
size_t len = strlen(hname); |
274 |
|
275 |
if ((strlen(irc_domain) + len + 2) < size) |
276 |
{ |
277 |
hname[len++] = '.'; |
278 |
strcpy(hname + len, irc_domain); |
279 |
} |
280 |
} |
281 |
} |
282 |
} |
283 |
|
284 |
/* |
285 |
* rem_request - remove a request from the list. |
286 |
* This must also free any memory that has been allocated for |
287 |
* temporary storage of DNS results. |
288 |
*/ |
289 |
static void |
290 |
rem_request(struct reslist *request) |
291 |
{ |
292 |
dlinkDelete(&request->node, &request_list); |
293 |
MyFree(request->name); |
294 |
MyFree(request); |
295 |
} |
296 |
|
297 |
/* |
298 |
* make_request - Create a DNS request record for the server. |
299 |
*/ |
300 |
static struct reslist * |
301 |
make_request(struct DNSQuery *query) |
302 |
{ |
303 |
struct reslist *request = MyMalloc(sizeof(struct reslist)); |
304 |
|
305 |
request->sentat = CurrentTime; |
306 |
request->retries = 3; |
307 |
request->resend = 1; |
308 |
request->timeout = 4; /* start at 4 and exponential inc. */ |
309 |
request->query = query; |
310 |
request->state = REQ_IDLE; |
311 |
|
312 |
dlinkAdd(request, &request->node, &request_list); |
313 |
|
314 |
return request; |
315 |
} |
316 |
|
317 |
/* |
318 |
* delete_resolver_queries - cleanup outstanding queries |
319 |
* for which there no longer exist clients or conf lines. |
320 |
*/ |
321 |
void |
322 |
delete_resolver_queries(const struct DNSQuery *query) |
323 |
{ |
324 |
dlink_node *ptr; |
325 |
dlink_node *next_ptr; |
326 |
struct reslist *request; |
327 |
|
328 |
DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head) |
329 |
{ |
330 |
if ((request = ptr->data) != NULL) |
331 |
{ |
332 |
if (query == request->query) |
333 |
rem_request(request); |
334 |
} |
335 |
} |
336 |
} |
337 |
|
338 |
/* |
339 |
* send_res_msg - sends msg to all nameservers found in the "_res" structure. |
340 |
* This should reflect /etc/resolv.conf. We will get responses |
341 |
* which arent needed but is easier than checking to see if nameserver |
342 |
* isnt present. Returns number of messages successfully sent to |
343 |
* nameservers or -1 if no successful sends. |
344 |
*/ |
345 |
static int |
346 |
send_res_msg(const char *msg, int len, int rcount) |
347 |
{ |
348 |
int i; |
349 |
int sent = 0; |
350 |
int max_queries = IRCD_MIN(irc_nscount, rcount); |
351 |
|
352 |
/* RES_PRIMARY option is not implemented |
353 |
* if (res.options & RES_PRIMARY || 0 == max_queries) |
354 |
*/ |
355 |
if (max_queries == 0) |
356 |
max_queries = 1; |
357 |
|
358 |
for (i = 0; i < max_queries; i++) |
359 |
{ |
360 |
if (sendto(ResolverFileDescriptor.fd, msg, len, 0, |
361 |
(struct sockaddr*)&(irc_nsaddr_list[i]), |
362 |
irc_nsaddr_list[i].ss_len) == len) |
363 |
++sent; |
364 |
} |
365 |
|
366 |
return(sent); |
367 |
} |
368 |
|
369 |
/* |
370 |
* find_id - find a dns request id (id is determined by dn_mkquery) |
371 |
*/ |
372 |
static struct reslist * |
373 |
find_id(int id) |
374 |
{ |
375 |
dlink_node *ptr; |
376 |
struct reslist *request; |
377 |
|
378 |
DLINK_FOREACH(ptr, request_list.head) |
379 |
{ |
380 |
request = ptr->data; |
381 |
|
382 |
if (request->id == id) |
383 |
return(request); |
384 |
} |
385 |
|
386 |
return(NULL); |
387 |
} |
388 |
|
389 |
/* |
390 |
* gethost_byname_type - get host address from name |
391 |
* |
392 |
*/ |
393 |
void |
394 |
gethost_byname_type(const char *name, struct DNSQuery *query, int type) |
395 |
{ |
396 |
assert(name != 0); |
397 |
do_query_name(query, name, NULL, type); |
398 |
} |
399 |
|
400 |
/* |
401 |
* gethost_byname - wrapper for _type - send T_AAAA first if IPV6 supported |
402 |
*/ |
403 |
void |
404 |
gethost_byname(const char *name, struct DNSQuery *query) |
405 |
{ |
406 |
#ifdef IPV6 |
407 |
gethost_byname_type(name, query, T_AAAA); |
408 |
#else |
409 |
gethost_byname_type(name, query, T_A); |
410 |
#endif |
411 |
} |
412 |
|
413 |
/* |
414 |
* gethost_byaddr - get host name from address |
415 |
*/ |
416 |
void |
417 |
gethost_byaddr(const struct irc_ssaddr *addr, struct DNSQuery *query) |
418 |
{ |
419 |
do_query_number(query, addr, NULL); |
420 |
} |
421 |
|
422 |
/* |
423 |
* do_query_name - nameserver lookup name |
424 |
*/ |
425 |
static void |
426 |
do_query_name(struct DNSQuery *query, const char *name, |
427 |
struct reslist *request, int type) |
428 |
{ |
429 |
char host_name[HOSTLEN + 1]; |
430 |
|
431 |
strlcpy(host_name, name, HOSTLEN); |
432 |
add_local_domain(host_name, HOSTLEN); |
433 |
|
434 |
if (request == NULL) |
435 |
{ |
436 |
request = make_request(query); |
437 |
request->name = (char *)MyMalloc(strlen(host_name) + 1); |
438 |
request->type = type; |
439 |
strcpy(request->name, host_name); |
440 |
#ifdef IPV6 |
441 |
if (type == T_A) |
442 |
request->state = REQ_A; |
443 |
else |
444 |
request->state = REQ_AAAA; |
445 |
#else |
446 |
request->state = REQ_A; |
447 |
#endif |
448 |
} |
449 |
|
450 |
request->type = type; |
451 |
query_name(host_name, C_IN, type, request); |
452 |
} |
453 |
|
454 |
/* |
455 |
* do_query_number - Use this to do reverse IP# lookups. |
456 |
*/ |
457 |
static void |
458 |
do_query_number(struct DNSQuery *query, const struct irc_ssaddr *addr, |
459 |
struct reslist *request) |
460 |
{ |
461 |
char ipbuf[128]; |
462 |
const unsigned char *cp; |
463 |
#ifdef IPV6 |
464 |
const char *intarpa; |
465 |
#endif |
466 |
if (addr->ss.ss_family == AF_INET) |
467 |
{ |
468 |
struct sockaddr_in *v4 = (struct sockaddr_in *)addr; |
469 |
cp = (const unsigned char*)&v4->sin_addr.s_addr; |
470 |
|
471 |
ircsprintf(ipbuf, "%u.%u.%u.%u.in-addr.arpa.", |
472 |
(unsigned int)(cp[3]), (unsigned int)(cp[2]), |
473 |
(unsigned int)(cp[1]), (unsigned int)(cp[0])); |
474 |
} |
475 |
#ifdef IPV6 |
476 |
else if (addr->ss.ss_family == AF_INET6) |
477 |
{ |
478 |
struct sockaddr_in6 *v6 = (struct sockaddr_in6 *)addr; |
479 |
cp = (const unsigned char *)&v6->sin6_addr.s6_addr; |
480 |
|
481 |
if (request != NULL && request->state == REQ_INT) |
482 |
intarpa = "int"; |
483 |
else |
484 |
intarpa = "arpa"; |
485 |
|
486 |
(void)sprintf(ipbuf, "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x." |
487 |
"%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.ip6.%s.", |
488 |
(unsigned int)(cp[15]&0xf), (unsigned int)(cp[15]>>4), |
489 |
(unsigned int)(cp[14]&0xf), (unsigned int)(cp[14]>>4), |
490 |
(unsigned int)(cp[13]&0xf), (unsigned int)(cp[13]>>4), |
491 |
(unsigned int)(cp[12]&0xf), (unsigned int)(cp[12]>>4), |
492 |
(unsigned int)(cp[11]&0xf), (unsigned int)(cp[11]>>4), |
493 |
(unsigned int)(cp[10]&0xf), (unsigned int)(cp[10]>>4), |
494 |
(unsigned int)(cp[9]&0xf), (unsigned int)(cp[9]>>4), |
495 |
(unsigned int)(cp[8]&0xf), (unsigned int)(cp[8]>>4), |
496 |
(unsigned int)(cp[7]&0xf), (unsigned int)(cp[7]>>4), |
497 |
(unsigned int)(cp[6]&0xf), (unsigned int)(cp[6]>>4), |
498 |
(unsigned int)(cp[5]&0xf), (unsigned int)(cp[5]>>4), |
499 |
(unsigned int)(cp[4]&0xf), (unsigned int)(cp[4]>>4), |
500 |
(unsigned int)(cp[3]&0xf), (unsigned int)(cp[3]>>4), |
501 |
(unsigned int)(cp[2]&0xf), (unsigned int)(cp[2]>>4), |
502 |
(unsigned int)(cp[1]&0xf), (unsigned int)(cp[1]>>4), |
503 |
(unsigned int)(cp[0]&0xf), (unsigned int)(cp[0]>>4), intarpa); |
504 |
} |
505 |
#endif |
506 |
if (request == NULL) |
507 |
{ |
508 |
request = make_request(query); |
509 |
request->type = T_PTR; |
510 |
memcpy(&request->addr, addr, sizeof(struct irc_ssaddr)); |
511 |
request->name = (char *)MyMalloc(HOSTLEN + 1); |
512 |
} |
513 |
|
514 |
query_name(ipbuf, C_IN, T_PTR, request); |
515 |
} |
516 |
|
517 |
/* |
518 |
* query_name - generate a query based on class, type and name. |
519 |
*/ |
520 |
static void |
521 |
query_name(const char *name, int query_class, int type, |
522 |
struct reslist *request) |
523 |
{ |
524 |
char buf[MAXPACKET]; |
525 |
int request_len = 0; |
526 |
|
527 |
memset(buf, 0, sizeof(buf)); |
528 |
|
529 |
if ((request_len = irc_res_mkquery(name, query_class, type, |
530 |
(unsigned char *)buf, sizeof(buf))) > 0) |
531 |
{ |
532 |
HEADER *header = (HEADER *)buf; |
533 |
#ifndef HAVE_LRAND48 |
534 |
int k = 0; |
535 |
struct timeval tv; |
536 |
#endif |
537 |
/* |
538 |
* generate an unique id |
539 |
* NOTE: we don't have to worry about converting this to and from |
540 |
* network byte order, the nameserver does not interpret this value |
541 |
* and returns it unchanged |
542 |
*/ |
543 |
#ifdef HAVE_LRAND48 |
544 |
do |
545 |
{ |
546 |
header->id = (header->id + lrand48()) & 0xffff; |
547 |
} while (find_id(header->id)); |
548 |
#else |
549 |
gettimeofday(&tv, NULL); |
550 |
do |
551 |
{ |
552 |
header->id = (header->id + k + tv.tv_usec) & 0xffff; |
553 |
k++; |
554 |
} while (find_id(header->id)); |
555 |
#endif /* HAVE_LRAND48 */ |
556 |
request->id = header->id; |
557 |
++request->sends; |
558 |
|
559 |
request->sent += send_res_msg(buf, request_len, request->sends); |
560 |
} |
561 |
} |
562 |
|
563 |
static void |
564 |
resend_query(struct reslist *request) |
565 |
{ |
566 |
if (request->resend == 0) |
567 |
return; |
568 |
|
569 |
switch(request->type) |
570 |
{ |
571 |
case T_PTR: |
572 |
do_query_number(NULL, &request->addr, request); |
573 |
break; |
574 |
case T_A: |
575 |
do_query_name(NULL, request->name, request, request->type); |
576 |
break; |
577 |
#ifdef IPV6 |
578 |
case T_AAAA: |
579 |
/* didnt work, try A */ |
580 |
if (request->state == REQ_AAAA) |
581 |
do_query_name(NULL, request->name, request, T_A); |
582 |
#endif |
583 |
default: |
584 |
break; |
585 |
} |
586 |
} |
587 |
|
588 |
/* |
589 |
* proc_answer - process name server reply |
590 |
*/ |
591 |
static int |
592 |
proc_answer(struct reslist *request, HEADER* header, char* buf, char* eob) |
593 |
{ |
594 |
char hostbuf[HOSTLEN + 100]; /* working buffer */ |
595 |
unsigned char *current; /* current position in buf */ |
596 |
int query_class; /* answer class */ |
597 |
int type; /* answer type */ |
598 |
int n; /* temp count */ |
599 |
int rd_length; |
600 |
struct sockaddr_in *v4; /* conversion */ |
601 |
#ifdef IPV6 |
602 |
struct sockaddr_in6 *v6; |
603 |
#endif |
604 |
current = (unsigned char *)buf + sizeof(HEADER); |
605 |
|
606 |
for (; header->qdcount > 0; --header->qdcount) |
607 |
{ |
608 |
if ((n = irc_dn_skipname(current, (unsigned char *)eob)) < 0) |
609 |
break; |
610 |
|
611 |
current += (size_t) n + QFIXEDSZ; |
612 |
} |
613 |
|
614 |
/* |
615 |
* process each answer sent to us blech. |
616 |
*/ |
617 |
while (header->ancount > 0 && (char *)current < eob) |
618 |
{ |
619 |
header->ancount--; |
620 |
|
621 |
n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current, |
622 |
hostbuf, sizeof(hostbuf)); |
623 |
|
624 |
if (n < 0) |
625 |
{ |
626 |
/* |
627 |
* broken message |
628 |
*/ |
629 |
return(0); |
630 |
} |
631 |
else if (n == 0) |
632 |
{ |
633 |
/* |
634 |
* no more answers left |
635 |
*/ |
636 |
return(0); |
637 |
} |
638 |
|
639 |
hostbuf[HOSTLEN] = '\0'; |
640 |
|
641 |
/* With Address arithmetic you have to be very anal |
642 |
* this code was not working on alpha due to that |
643 |
* (spotted by rodder/jailbird/dianora) |
644 |
*/ |
645 |
current += (size_t) n; |
646 |
|
647 |
if (!(((char *)current + ANSWER_FIXED_SIZE) < eob)) |
648 |
break; |
649 |
|
650 |
type = irc_ns_get16(current); |
651 |
current += TYPE_SIZE; |
652 |
|
653 |
query_class = irc_ns_get16(current); |
654 |
current += CLASS_SIZE; |
655 |
|
656 |
request->ttl = irc_ns_get32(current); |
657 |
current += TTL_SIZE; |
658 |
|
659 |
rd_length = irc_ns_get16(current); |
660 |
current += RDLENGTH_SIZE; |
661 |
|
662 |
/* |
663 |
* Wait to set request->type until we verify this structure |
664 |
*/ |
665 |
switch (type) |
666 |
{ |
667 |
case T_A: |
668 |
if (request->type != T_A) |
669 |
return(0); |
670 |
|
671 |
/* |
672 |
* check for invalid rd_length or too many addresses |
673 |
*/ |
674 |
if (rd_length != sizeof(struct in_addr)) |
675 |
return(0); |
676 |
v4 = (struct sockaddr_in *)&request->addr; |
677 |
request->addr.ss_len = sizeof(struct sockaddr_in); |
678 |
v4->sin_family = AF_INET; |
679 |
memcpy(&v4->sin_addr, current, sizeof(struct in_addr)); |
680 |
return(1); |
681 |
break; |
682 |
#ifdef IPV6 |
683 |
case T_AAAA: |
684 |
if (request->type != T_AAAA) |
685 |
return(0); |
686 |
if (rd_length != sizeof(struct in6_addr)) |
687 |
return(0); |
688 |
request->addr.ss_len = sizeof(struct sockaddr_in6); |
689 |
v6 = (struct sockaddr_in6 *)&request->addr; |
690 |
v6->sin6_family = AF_INET6; |
691 |
memcpy(&v6->sin6_addr, current, sizeof(struct in6_addr)); |
692 |
return(1); |
693 |
break; |
694 |
#endif |
695 |
case T_PTR: |
696 |
if (request->type != T_PTR) |
697 |
return(0); |
698 |
n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, |
699 |
current, hostbuf, sizeof(hostbuf)); |
700 |
if (n < 0) |
701 |
return(0); /* broken message */ |
702 |
else if (n == 0) |
703 |
return(0); /* no more answers left */ |
704 |
|
705 |
strlcpy(request->name, hostbuf, HOSTLEN); |
706 |
|
707 |
return(1); |
708 |
break; |
709 |
case T_CNAME: /* first check we already havent started looking |
710 |
into a cname */ |
711 |
if (request->type != T_PTR) |
712 |
return(0); |
713 |
|
714 |
if (request->state == REQ_CNAME) |
715 |
{ |
716 |
n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, |
717 |
current, hostbuf, sizeof(hostbuf)); |
718 |
|
719 |
if (n < 0) |
720 |
return(0); |
721 |
return(1); |
722 |
} |
723 |
|
724 |
request->state = REQ_CNAME; |
725 |
current += rd_length; |
726 |
break; |
727 |
|
728 |
default: |
729 |
/* XXX I'd rather just throw away the entire bogus thing |
730 |
* but its possible its just a broken nameserver with still |
731 |
* valid answers. But lets do some rudimentary logging for now... |
732 |
*/ |
733 |
ilog(L_ERROR, "irc_res.c bogus type %d", type); |
734 |
break; |
735 |
} |
736 |
} |
737 |
|
738 |
return(1); |
739 |
} |
740 |
|
741 |
/* |
742 |
* res_readreply - read a dns reply from the nameserver and process it. |
743 |
*/ |
744 |
static void |
745 |
res_readreply(fde_t *fd, void *data) |
746 |
{ |
747 |
char buf[sizeof(HEADER) + MAXPACKET] |
748 |
/* Sparc and alpha need 16bit-alignment for accessing header->id |
749 |
* (which is uint16_t). Because of the header = (HEADER*) buf; |
750 |
* lateron, this is neeeded. --FaUl |
751 |
*/ |
752 |
#if defined(__sparc__) || defined(__alpha__) |
753 |
__attribute__((aligned (16))) |
754 |
#endif |
755 |
; |
756 |
HEADER *header; |
757 |
struct reslist *request = NULL; |
758 |
struct DNSReply *reply = NULL; |
759 |
int rc; |
760 |
int answer_count; |
761 |
socklen_t len = sizeof(struct irc_ssaddr); |
762 |
struct irc_ssaddr lsin; |
763 |
|
764 |
rc = recvfrom(fd->fd, buf, sizeof(buf), 0, (struct sockaddr *)&lsin, &len); |
765 |
|
766 |
/* Re-schedule a read *after* recvfrom, or we'll be registering |
767 |
* interest where it'll instantly be ready for read :-) -- adrian |
768 |
*/ |
769 |
comm_setselect(fd, COMM_SELECT_READ, res_readreply, NULL, 0); |
770 |
/* Better to cast the sizeof instead of rc */ |
771 |
if (rc <= (int)(sizeof(HEADER))) |
772 |
return; |
773 |
|
774 |
/* |
775 |
* convert DNS reply reader from Network byte order to CPU byte order. |
776 |
*/ |
777 |
header = (HEADER *)buf; |
778 |
header->ancount = ntohs(header->ancount); |
779 |
header->qdcount = ntohs(header->qdcount); |
780 |
header->nscount = ntohs(header->nscount); |
781 |
header->arcount = ntohs(header->arcount); |
782 |
|
783 |
/* |
784 |
* response for an id which we have already received an answer for |
785 |
* just ignore this response. |
786 |
*/ |
787 |
if (0 == (request = find_id(header->id))) |
788 |
return; |
789 |
|
790 |
/* |
791 |
* check against possibly fake replies |
792 |
*/ |
793 |
if (!res_ourserver(&lsin)) |
794 |
return; |
795 |
|
796 |
if ((header->rcode != NO_ERRORS) || (header->ancount == 0)) |
797 |
{ |
798 |
if ((SERVFAIL == header->rcode) || (NXDOMAIN == header->rcode)) |
799 |
{ |
800 |
/* |
801 |
* If a bad error was returned, we stop here and dont send |
802 |
* send any more (no retries granted). |
803 |
*/ |
804 |
(*request->query->callback)(request->query->ptr, NULL); |
805 |
rem_request(request); |
806 |
} |
807 |
else |
808 |
{ |
809 |
/* |
810 |
* If we havent already tried this, and we're looking up AAAA, try A |
811 |
* now |
812 |
*/ |
813 |
|
814 |
#ifdef IPV6 |
815 |
if (request->state == REQ_AAAA && request->type == T_AAAA) |
816 |
{ |
817 |
request->timeout += 4; |
818 |
resend_query(request); |
819 |
} |
820 |
else if (request->type == T_PTR && request->state != REQ_INT && |
821 |
request->addr.ss.ss_family == AF_INET6) |
822 |
{ |
823 |
request->state = REQ_INT; |
824 |
request->timeout += 4; |
825 |
request->retries--; |
826 |
resend_query(request); |
827 |
} |
828 |
#endif |
829 |
} |
830 |
|
831 |
return; |
832 |
} |
833 |
/* |
834 |
* If this fails there was an error decoding the received packet, |
835 |
* try it again and hope it works the next time. |
836 |
*/ |
837 |
answer_count = proc_answer(request, header, buf, buf + rc); |
838 |
|
839 |
if (answer_count) |
840 |
{ |
841 |
if (request->type == T_PTR) |
842 |
{ |
843 |
if (request->name == NULL) |
844 |
{ |
845 |
/* |
846 |
* got a PTR response with no name, something bogus is happening |
847 |
* don't bother trying again, the client address doesn't resolve |
848 |
*/ |
849 |
(*request->query->callback)(request->query->ptr, reply); |
850 |
rem_request(request); |
851 |
return; |
852 |
} |
853 |
|
854 |
/* |
855 |
* Lookup the 'authoritative' name that we were given for the |
856 |
* ip#. |
857 |
* |
858 |
*/ |
859 |
#ifdef IPV6 |
860 |
if (request->addr.ss.ss_family == AF_INET6) |
861 |
gethost_byname_type(request->name, request->query, T_AAAA); |
862 |
else |
863 |
#endif |
864 |
gethost_byname_type(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 |
MyFree(reply); |
875 |
rem_request(request); |
876 |
} |
877 |
} |
878 |
else if (!request->sent) |
879 |
{ |
880 |
/* XXX - we got a response for a query we didn't send with a valid id? |
881 |
* this should never happen, bail here and leave the client unresolved |
882 |
*/ |
883 |
assert(0); |
884 |
|
885 |
/* XXX don't leak it */ |
886 |
rem_request(request); |
887 |
} |
888 |
} |
889 |
|
890 |
static struct DNSReply * |
891 |
make_dnsreply(struct reslist *request) |
892 |
{ |
893 |
struct DNSReply *cp; |
894 |
assert(request != 0); |
895 |
|
896 |
cp = (struct DNSReply *)MyMalloc(sizeof(struct DNSReply)); |
897 |
|
898 |
cp->h_name = request->name; |
899 |
memcpy(&cp->addr, &request->addr, sizeof(cp->addr)); |
900 |
return(cp); |
901 |
} |