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 "fdlist.h" |
34 |
#include "fileio.h" /* for fbopen / fbclose / fbputs */ |
35 |
#include "s_bsd.h" |
36 |
#include "s_log.h" |
37 |
#include "send.h" |
38 |
#include "memory.h" |
39 |
#include "irc_res.h" |
40 |
#include "irc_reslib.h" |
41 |
#include "irc_getnameinfo.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 |
REQ_INT /* ip6.arpa failed, falling back to ip6.int */ |
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 |
struct DNSQuery *query; /* query callback for this request */ |
92 |
}; |
93 |
|
94 |
static fde_t ResolverFileDescriptor; |
95 |
static dlink_list request_list = { NULL, NULL, 0 }; |
96 |
|
97 |
static void rem_request(struct reslist *request); |
98 |
static struct reslist *make_request(struct DNSQuery *query); |
99 |
static void do_query_name(struct DNSQuery *query, |
100 |
const char* name, struct reslist *request, int); |
101 |
static void do_query_number(struct DNSQuery *query, |
102 |
const struct irc_ssaddr *, |
103 |
struct reslist *request); |
104 |
static void query_name(const char *name, int query_class, int query_type, |
105 |
struct reslist *request); |
106 |
static int send_res_msg(const char *buf, int len, int count); |
107 |
static void resend_query(struct reslist *request); |
108 |
static int proc_answer(struct reslist *request, HEADER *header, char *, char *); |
109 |
static struct reslist *find_id(int id); |
110 |
static struct DNSReply *make_dnsreply(struct reslist *request); |
111 |
|
112 |
extern struct irc_ssaddr irc_nsaddr_list[IRCD_MAXNS]; |
113 |
extern int irc_nscount; |
114 |
extern char irc_domain[HOSTLEN+1]; |
115 |
|
116 |
|
117 |
/* |
118 |
* int |
119 |
* res_ourserver(inp) |
120 |
* looks up "inp" in irc_nsaddr_list[] |
121 |
* returns: |
122 |
* 0 : not found |
123 |
* >0 : found |
124 |
* author: |
125 |
* paul vixie, 29may94 |
126 |
* revised for ircd, cryogen(stu) may03 |
127 |
*/ |
128 |
static int |
129 |
res_ourserver(const struct irc_ssaddr *inp) |
130 |
{ |
131 |
#ifdef IPV6 |
132 |
struct sockaddr_in6 *v6; |
133 |
struct sockaddr_in6 *v6in = (struct sockaddr_in6 *)inp; |
134 |
#endif |
135 |
struct sockaddr_in *v4; |
136 |
struct sockaddr_in *v4in = (struct sockaddr_in *)inp; |
137 |
int ns; |
138 |
|
139 |
for (ns = 0; ns < irc_nscount; ns++) |
140 |
{ |
141 |
const struct irc_ssaddr *srv = &irc_nsaddr_list[ns]; |
142 |
#ifdef IPV6 |
143 |
v6 = (struct sockaddr_in6 *)srv; |
144 |
#endif |
145 |
v4 = (struct sockaddr_in *)srv; |
146 |
|
147 |
/* could probably just memcmp(srv, inp, srv.ss_len) here |
148 |
* but we'll air on the side of caution - stu |
149 |
* |
150 |
*/ |
151 |
switch (srv->ss.ss_family) |
152 |
{ |
153 |
#ifdef IPV6 |
154 |
case AF_INET6: |
155 |
if (srv->ss.ss_family == inp->ss.ss_family) |
156 |
if (v6->sin6_port == v6in->sin6_port) |
157 |
if ((memcmp(&v6->sin6_addr.s6_addr, &v6in->sin6_addr.s6_addr, |
158 |
sizeof(struct in6_addr)) == 0) || |
159 |
(memcmp(&v6->sin6_addr.s6_addr, &in6addr_any, |
160 |
sizeof(struct in6_addr)) == 0)) |
161 |
return(1); |
162 |
break; |
163 |
#endif |
164 |
case AF_INET: |
165 |
if (srv->ss.ss_family == inp->ss.ss_family) |
166 |
if (v4->sin_port == v4in->sin_port) |
167 |
if ((v4->sin_addr.s_addr == INADDR_ANY) || |
168 |
(v4->sin_addr.s_addr == v4in->sin_addr.s_addr)) |
169 |
return(1); |
170 |
break; |
171 |
default: |
172 |
break; |
173 |
} |
174 |
} |
175 |
|
176 |
return(0); |
177 |
} |
178 |
|
179 |
/* |
180 |
* timeout_query_list - Remove queries from the list which have been |
181 |
* there too long without being resolved. |
182 |
*/ |
183 |
static time_t |
184 |
timeout_query_list(time_t now) |
185 |
{ |
186 |
dlink_node *ptr; |
187 |
dlink_node *next_ptr; |
188 |
struct reslist *request; |
189 |
time_t next_time = 0; |
190 |
time_t timeout = 0; |
191 |
|
192 |
DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head) |
193 |
{ |
194 |
request = ptr->data; |
195 |
timeout = request->sentat + request->timeout; |
196 |
|
197 |
if (now >= timeout) |
198 |
{ |
199 |
if (--request->retries <= 0) |
200 |
{ |
201 |
(*request->query->callback)(request->query->ptr, NULL); |
202 |
rem_request(request); |
203 |
continue; |
204 |
} |
205 |
else |
206 |
{ |
207 |
request->sentat = now; |
208 |
request->timeout += request->timeout; |
209 |
resend_query(request); |
210 |
} |
211 |
} |
212 |
|
213 |
if ((next_time == 0) || timeout < next_time) |
214 |
{ |
215 |
next_time = timeout; |
216 |
} |
217 |
} |
218 |
|
219 |
return((next_time > now) ? next_time : (now + AR_TTL)); |
220 |
} |
221 |
|
222 |
/* |
223 |
* timeout_resolver - check request list |
224 |
*/ |
225 |
static void |
226 |
timeout_resolver(void *notused) |
227 |
{ |
228 |
timeout_query_list(CurrentTime); |
229 |
} |
230 |
|
231 |
/* |
232 |
* start_resolver - do everything we need to read the resolv.conf file |
233 |
* and initialize the resolver file descriptor if needed |
234 |
*/ |
235 |
static void |
236 |
start_resolver(void) |
237 |
{ |
238 |
irc_res_init(); |
239 |
|
240 |
if (!ResolverFileDescriptor.flags.open) |
241 |
{ |
242 |
if (comm_open(&ResolverFileDescriptor, irc_nsaddr_list[0].ss.ss_family, |
243 |
SOCK_DGRAM, 0, "Resolver socket") == -1) |
244 |
return; |
245 |
|
246 |
/* At the moment, the resolver FD data is global .. */ |
247 |
comm_setselect(&ResolverFileDescriptor, COMM_SELECT_READ, |
248 |
res_readreply, NULL, 0); |
249 |
eventAdd("timeout_resolver", timeout_resolver, NULL, 1); |
250 |
} |
251 |
} |
252 |
|
253 |
/* |
254 |
* init_resolver - initialize resolver and resolver library |
255 |
*/ |
256 |
void |
257 |
init_resolver(void) |
258 |
{ |
259 |
#ifdef HAVE_SRAND48 |
260 |
srand48(CurrentTime); |
261 |
#endif |
262 |
memset(&ResolverFileDescriptor, 0, sizeof(fde_t)); |
263 |
start_resolver(); |
264 |
} |
265 |
|
266 |
/* |
267 |
* restart_resolver - reread resolv.conf, reopen socket |
268 |
*/ |
269 |
void |
270 |
restart_resolver(void) |
271 |
{ |
272 |
fd_close(&ResolverFileDescriptor); |
273 |
eventDelete(timeout_resolver, NULL); /* -ddosen */ |
274 |
start_resolver(); |
275 |
} |
276 |
|
277 |
/* |
278 |
* add_local_domain - Add the domain to hostname, if it is missing |
279 |
* (as suggested by eps@TOASTER.SFSU.EDU) |
280 |
*/ |
281 |
void |
282 |
add_local_domain(char *hname, size_t size) |
283 |
{ |
284 |
/* try to fix up unqualified names |
285 |
*/ |
286 |
if (strchr(hname, '.') == NULL) |
287 |
{ |
288 |
if (irc_domain[0]) |
289 |
{ |
290 |
size_t len = strlen(hname); |
291 |
|
292 |
if ((strlen(irc_domain) + len + 2) < size) |
293 |
{ |
294 |
hname[len++] = '.'; |
295 |
strcpy(hname + len, irc_domain); |
296 |
} |
297 |
} |
298 |
} |
299 |
} |
300 |
|
301 |
/* |
302 |
* rem_request - remove a request from the list. |
303 |
* This must also free any memory that has been allocated for |
304 |
* temporary storage of DNS results. |
305 |
*/ |
306 |
static void |
307 |
rem_request(struct reslist *request) |
308 |
{ |
309 |
dlinkDelete(&request->node, &request_list); |
310 |
MyFree(request->name); |
311 |
MyFree(request); |
312 |
} |
313 |
|
314 |
/* |
315 |
* make_request - Create a DNS request record for the server. |
316 |
*/ |
317 |
static struct reslist * |
318 |
make_request(struct DNSQuery* query) |
319 |
{ |
320 |
struct reslist *request; |
321 |
|
322 |
request = (struct reslist *)MyMalloc(sizeof(struct reslist)); |
323 |
memset(request, 0, sizeof(struct reslist)); |
324 |
|
325 |
request->sentat = CurrentTime; |
326 |
request->retries = 3; |
327 |
request->resend = 1; |
328 |
request->timeout = 4; /* start at 4 and exponential inc. */ |
329 |
memset(&request->addr, 0, sizeof(request->addr)); |
330 |
request->query = query; |
331 |
request->state = REQ_IDLE; |
332 |
|
333 |
dlinkAdd(request, &request->node, &request_list); |
334 |
return(request); |
335 |
} |
336 |
|
337 |
/* |
338 |
* delete_resolver_queries - cleanup outstanding queries |
339 |
* for which there no longer exist clients or conf lines. |
340 |
*/ |
341 |
void |
342 |
delete_resolver_queries(const struct DNSQuery *query) |
343 |
{ |
344 |
dlink_node *ptr; |
345 |
dlink_node *next_ptr; |
346 |
struct reslist *request; |
347 |
|
348 |
DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head) |
349 |
{ |
350 |
if ((request = ptr->data) != NULL) |
351 |
{ |
352 |
if (query == request->query) |
353 |
rem_request(request); |
354 |
} |
355 |
} |
356 |
} |
357 |
|
358 |
/* |
359 |
* send_res_msg - sends msg to all nameservers found in the "_res" structure. |
360 |
* This should reflect /etc/resolv.conf. We will get responses |
361 |
* which arent needed but is easier than checking to see if nameserver |
362 |
* isnt present. Returns number of messages successfully sent to |
363 |
* nameservers or -1 if no successful sends. |
364 |
*/ |
365 |
static int |
366 |
send_res_msg(const char *msg, int len, int rcount) |
367 |
{ |
368 |
int i; |
369 |
int sent = 0; |
370 |
int max_queries = IRCD_MIN(irc_nscount, rcount); |
371 |
|
372 |
/* RES_PRIMARY option is not implemented |
373 |
* if (res.options & RES_PRIMARY || 0 == max_queries) |
374 |
*/ |
375 |
if (max_queries == 0) |
376 |
max_queries = 1; |
377 |
|
378 |
for (i = 0; i < max_queries; i++) |
379 |
{ |
380 |
if (sendto(ResolverFileDescriptor.fd, msg, len, 0, |
381 |
(struct sockaddr*)&(irc_nsaddr_list[i]), |
382 |
irc_nsaddr_list[i].ss_len) == len) |
383 |
++sent; |
384 |
} |
385 |
|
386 |
return(sent); |
387 |
} |
388 |
|
389 |
/* |
390 |
* find_id - find a dns request id (id is determined by dn_mkquery) |
391 |
*/ |
392 |
static struct reslist * |
393 |
find_id(int id) |
394 |
{ |
395 |
dlink_node *ptr; |
396 |
struct reslist *request; |
397 |
|
398 |
DLINK_FOREACH(ptr, request_list.head) |
399 |
{ |
400 |
request = ptr->data; |
401 |
|
402 |
if (request->id == id) |
403 |
return(request); |
404 |
} |
405 |
|
406 |
return(NULL); |
407 |
} |
408 |
|
409 |
/* |
410 |
* gethost_byname_type - get host address from name |
411 |
* |
412 |
*/ |
413 |
void |
414 |
gethost_byname_type(const char *name, struct DNSQuery *query, int type) |
415 |
{ |
416 |
assert(name != 0); |
417 |
do_query_name(query, name, NULL, type); |
418 |
} |
419 |
|
420 |
/* |
421 |
* gethost_byname - wrapper for _type - send T_AAAA first if IPV6 supported |
422 |
*/ |
423 |
void |
424 |
gethost_byname(const char *name, struct DNSQuery *query) |
425 |
{ |
426 |
#ifdef IPV6 |
427 |
gethost_byname_type(name, query, T_AAAA); |
428 |
#else |
429 |
gethost_byname_type(name, query, T_A); |
430 |
#endif |
431 |
} |
432 |
|
433 |
/* |
434 |
* gethost_byaddr - get host name from address |
435 |
*/ |
436 |
void |
437 |
gethost_byaddr(const struct irc_ssaddr *addr, struct DNSQuery *query) |
438 |
{ |
439 |
do_query_number(query, addr, NULL); |
440 |
} |
441 |
|
442 |
/* |
443 |
* do_query_name - nameserver lookup name |
444 |
*/ |
445 |
static void |
446 |
do_query_name(struct DNSQuery *query, const char *name, |
447 |
struct reslist *request, int type) |
448 |
{ |
449 |
char host_name[HOSTLEN + 1]; |
450 |
|
451 |
strlcpy(host_name, name, HOSTLEN); |
452 |
add_local_domain(host_name, HOSTLEN); |
453 |
|
454 |
if (request == NULL) |
455 |
{ |
456 |
request = make_request(query); |
457 |
request->name = (char *)MyMalloc(strlen(host_name) + 1); |
458 |
request->type = type; |
459 |
strcpy(request->name, host_name); |
460 |
#ifdef IPV6 |
461 |
if (type == T_A) |
462 |
request->state = REQ_A; |
463 |
else |
464 |
request->state = REQ_AAAA; |
465 |
#else |
466 |
request->state = REQ_A; |
467 |
#endif |
468 |
} |
469 |
|
470 |
request->type = type; |
471 |
query_name(host_name, C_IN, type, request); |
472 |
} |
473 |
|
474 |
/* |
475 |
* do_query_number - Use this to do reverse IP# lookups. |
476 |
*/ |
477 |
static void |
478 |
do_query_number(struct DNSQuery *query, const struct irc_ssaddr *addr, |
479 |
struct reslist *request) |
480 |
{ |
481 |
char ipbuf[128]; |
482 |
const unsigned char *cp; |
483 |
#ifdef IPV6 |
484 |
const char *intarpa; |
485 |
#endif |
486 |
if (addr->ss.ss_family == AF_INET) |
487 |
{ |
488 |
struct sockaddr_in *v4 = (struct sockaddr_in *)addr; |
489 |
cp = (const unsigned char*)&v4->sin_addr.s_addr; |
490 |
|
491 |
ircsprintf(ipbuf, "%u.%u.%u.%u.in-addr.arpa.", |
492 |
(unsigned int)(cp[3]), (unsigned int)(cp[2]), |
493 |
(unsigned int)(cp[1]), (unsigned int)(cp[0])); |
494 |
} |
495 |
#ifdef IPV6 |
496 |
else if (addr->ss.ss_family == AF_INET6) |
497 |
{ |
498 |
struct sockaddr_in6 *v6 = (struct sockaddr_in6 *)addr; |
499 |
cp = (const unsigned char *)&v6->sin6_addr.s6_addr; |
500 |
|
501 |
if (request != NULL && request->state == REQ_INT) |
502 |
intarpa = "int"; |
503 |
else |
504 |
intarpa = "arpa"; |
505 |
|
506 |
(void)sprintf(ipbuf, "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x." |
507 |
"%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.ip6.%s.", |
508 |
(unsigned int)(cp[15]&0xf), (unsigned int)(cp[15]>>4), |
509 |
(unsigned int)(cp[14]&0xf), (unsigned int)(cp[14]>>4), |
510 |
(unsigned int)(cp[13]&0xf), (unsigned int)(cp[13]>>4), |
511 |
(unsigned int)(cp[12]&0xf), (unsigned int)(cp[12]>>4), |
512 |
(unsigned int)(cp[11]&0xf), (unsigned int)(cp[11]>>4), |
513 |
(unsigned int)(cp[10]&0xf), (unsigned int)(cp[10]>>4), |
514 |
(unsigned int)(cp[9]&0xf), (unsigned int)(cp[9]>>4), |
515 |
(unsigned int)(cp[8]&0xf), (unsigned int)(cp[8]>>4), |
516 |
(unsigned int)(cp[7]&0xf), (unsigned int)(cp[7]>>4), |
517 |
(unsigned int)(cp[6]&0xf), (unsigned int)(cp[6]>>4), |
518 |
(unsigned int)(cp[5]&0xf), (unsigned int)(cp[5]>>4), |
519 |
(unsigned int)(cp[4]&0xf), (unsigned int)(cp[4]>>4), |
520 |
(unsigned int)(cp[3]&0xf), (unsigned int)(cp[3]>>4), |
521 |
(unsigned int)(cp[2]&0xf), (unsigned int)(cp[2]>>4), |
522 |
(unsigned int)(cp[1]&0xf), (unsigned int)(cp[1]>>4), |
523 |
(unsigned int)(cp[0]&0xf), (unsigned int)(cp[0]>>4), intarpa); |
524 |
} |
525 |
#endif |
526 |
if (request == NULL) |
527 |
{ |
528 |
request = make_request(query); |
529 |
request->type = T_PTR; |
530 |
memcpy(&request->addr, addr, sizeof(struct irc_ssaddr)); |
531 |
request->name = (char *)MyMalloc(HOSTLEN + 1); |
532 |
} |
533 |
|
534 |
query_name(ipbuf, C_IN, T_PTR, request); |
535 |
} |
536 |
|
537 |
/* |
538 |
* query_name - generate a query based on class, type and name. |
539 |
*/ |
540 |
static void |
541 |
query_name(const char *name, int query_class, int type, |
542 |
struct reslist *request) |
543 |
{ |
544 |
char buf[MAXPACKET]; |
545 |
int request_len = 0; |
546 |
|
547 |
memset(buf, 0, sizeof(buf)); |
548 |
|
549 |
if ((request_len = irc_res_mkquery(name, query_class, type, |
550 |
(unsigned char *)buf, sizeof(buf))) > 0) |
551 |
{ |
552 |
HEADER *header = (HEADER *)buf; |
553 |
#ifndef HAVE_LRAND48 |
554 |
int k = 0; |
555 |
struct timeval tv; |
556 |
#endif |
557 |
/* |
558 |
* generate an unique id |
559 |
* NOTE: we don't have to worry about converting this to and from |
560 |
* network byte order, the nameserver does not interpret this value |
561 |
* and returns it unchanged |
562 |
*/ |
563 |
#ifdef HAVE_LRAND48 |
564 |
do |
565 |
{ |
566 |
header->id = (header->id + lrand48()) & 0xffff; |
567 |
} while (find_id(header->id)); |
568 |
#else |
569 |
gettimeofday(&tv, NULL); |
570 |
do |
571 |
{ |
572 |
header->id = (header->id + k + tv.tv_usec) & 0xffff; |
573 |
k++; |
574 |
} while (find_id(header->id)); |
575 |
#endif /* HAVE_LRAND48 */ |
576 |
request->id = header->id; |
577 |
++request->sends; |
578 |
|
579 |
request->sent += send_res_msg(buf, request_len, request->sends); |
580 |
} |
581 |
} |
582 |
|
583 |
static void |
584 |
resend_query(struct reslist *request) |
585 |
{ |
586 |
if (request->resend == 0) |
587 |
return; |
588 |
|
589 |
switch(request->type) |
590 |
{ |
591 |
case T_PTR: |
592 |
do_query_number(NULL, &request->addr, request); |
593 |
break; |
594 |
case T_A: |
595 |
do_query_name(NULL, request->name, request, request->type); |
596 |
break; |
597 |
#ifdef IPV6 |
598 |
case T_AAAA: |
599 |
/* didnt work, try A */ |
600 |
if (request->state == REQ_AAAA) |
601 |
do_query_name(NULL, request->name, request, T_A); |
602 |
#endif |
603 |
default: |
604 |
break; |
605 |
} |
606 |
} |
607 |
|
608 |
/* |
609 |
* proc_answer - process name server reply |
610 |
*/ |
611 |
static int |
612 |
proc_answer(struct reslist *request, HEADER* header, char* buf, char* eob) |
613 |
{ |
614 |
char hostbuf[HOSTLEN + 100]; /* working buffer */ |
615 |
unsigned char *current; /* current position in buf */ |
616 |
int query_class; /* answer class */ |
617 |
int type; /* answer type */ |
618 |
int n; /* temp count */ |
619 |
int rd_length; |
620 |
struct sockaddr_in *v4; /* conversion */ |
621 |
#ifdef IPV6 |
622 |
struct sockaddr_in6 *v6; |
623 |
#endif |
624 |
current = (unsigned char *)buf + sizeof(HEADER); |
625 |
|
626 |
for (; header->qdcount > 0; --header->qdcount) |
627 |
{ |
628 |
if ((n = irc_dn_skipname(current, (unsigned char *)eob)) < 0) |
629 |
break; |
630 |
|
631 |
current += (size_t) n + QFIXEDSZ; |
632 |
} |
633 |
|
634 |
/* |
635 |
* process each answer sent to us blech. |
636 |
*/ |
637 |
while (header->ancount > 0 && (char *)current < eob) |
638 |
{ |
639 |
header->ancount--; |
640 |
|
641 |
n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current, |
642 |
hostbuf, sizeof(hostbuf)); |
643 |
|
644 |
if (n < 0) |
645 |
{ |
646 |
/* |
647 |
* broken message |
648 |
*/ |
649 |
return(0); |
650 |
} |
651 |
else if (n == 0) |
652 |
{ |
653 |
/* |
654 |
* no more answers left |
655 |
*/ |
656 |
return(0); |
657 |
} |
658 |
|
659 |
hostbuf[HOSTLEN] = '\0'; |
660 |
|
661 |
/* With Address arithmetic you have to be very anal |
662 |
* this code was not working on alpha due to that |
663 |
* (spotted by rodder/jailbird/dianora) |
664 |
*/ |
665 |
current += (size_t) n; |
666 |
|
667 |
if (!(((char *)current + ANSWER_FIXED_SIZE) < eob)) |
668 |
break; |
669 |
|
670 |
type = irc_ns_get16(current); |
671 |
current += TYPE_SIZE; |
672 |
|
673 |
query_class = irc_ns_get16(current); |
674 |
current += CLASS_SIZE; |
675 |
|
676 |
request->ttl = irc_ns_get32(current); |
677 |
current += TTL_SIZE; |
678 |
|
679 |
rd_length = irc_ns_get16(current); |
680 |
current += RDLENGTH_SIZE; |
681 |
|
682 |
/* |
683 |
* Wait to set request->type until we verify this structure |
684 |
*/ |
685 |
switch (type) |
686 |
{ |
687 |
case T_A: |
688 |
if (request->type != T_A) |
689 |
return(0); |
690 |
|
691 |
/* |
692 |
* check for invalid rd_length or too many addresses |
693 |
*/ |
694 |
if (rd_length != sizeof(struct in_addr)) |
695 |
return(0); |
696 |
v4 = (struct sockaddr_in *)&request->addr; |
697 |
request->addr.ss_len = sizeof(struct sockaddr_in); |
698 |
v4->sin_family = AF_INET; |
699 |
memcpy(&v4->sin_addr, current, sizeof(struct in_addr)); |
700 |
return(1); |
701 |
break; |
702 |
#ifdef IPV6 |
703 |
case T_AAAA: |
704 |
if (request->type != T_AAAA) |
705 |
return(0); |
706 |
if (rd_length != sizeof(struct in6_addr)) |
707 |
return(0); |
708 |
request->addr.ss_len = sizeof(struct sockaddr_in6); |
709 |
v6 = (struct sockaddr_in6 *)&request->addr; |
710 |
v6->sin6_family = AF_INET6; |
711 |
memcpy(&v6->sin6_addr, current, sizeof(struct in6_addr)); |
712 |
return(1); |
713 |
break; |
714 |
#endif |
715 |
case T_PTR: |
716 |
if (request->type != T_PTR) |
717 |
return(0); |
718 |
n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, |
719 |
current, hostbuf, sizeof(hostbuf)); |
720 |
if (n < 0) |
721 |
return(0); /* broken message */ |
722 |
else if (n == 0) |
723 |
return(0); /* no more answers left */ |
724 |
|
725 |
strlcpy(request->name, hostbuf, HOSTLEN); |
726 |
|
727 |
return(1); |
728 |
break; |
729 |
case T_CNAME: /* first check we already havent started looking |
730 |
into a cname */ |
731 |
if (request->type != T_PTR) |
732 |
return(0); |
733 |
|
734 |
if (request->state == REQ_CNAME) |
735 |
{ |
736 |
n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, |
737 |
current, hostbuf, sizeof(hostbuf)); |
738 |
|
739 |
if (n < 0) |
740 |
return(0); |
741 |
return(1); |
742 |
} |
743 |
|
744 |
request->state = REQ_CNAME; |
745 |
current += rd_length; |
746 |
break; |
747 |
|
748 |
default: |
749 |
/* XXX I'd rather just throw away the entire bogus thing |
750 |
* but its possible its just a broken nameserver with still |
751 |
* valid answers. But lets do some rudimentary logging for now... |
752 |
*/ |
753 |
ilog(L_ERROR, "irc_res.c bogus type %d", type); |
754 |
break; |
755 |
} |
756 |
} |
757 |
|
758 |
return(1); |
759 |
} |
760 |
|
761 |
/* |
762 |
* res_readreply - read a dns reply from the nameserver and process it. |
763 |
*/ |
764 |
static void |
765 |
res_readreply(fde_t *fd, void *data) |
766 |
{ |
767 |
char buf[sizeof(HEADER) + MAXPACKET]; |
768 |
HEADER *header; |
769 |
struct reslist *request = NULL; |
770 |
struct DNSReply *reply = NULL; |
771 |
int rc; |
772 |
int answer_count; |
773 |
socklen_t len = sizeof(struct irc_ssaddr); |
774 |
struct irc_ssaddr lsin; |
775 |
|
776 |
rc = recvfrom(fd->fd, buf, sizeof(buf), 0, (struct sockaddr *)&lsin, &len); |
777 |
|
778 |
/* Re-schedule a read *after* recvfrom, or we'll be registering |
779 |
* interest where it'll instantly be ready for read :-) -- adrian |
780 |
*/ |
781 |
comm_setselect(fd, COMM_SELECT_READ, res_readreply, NULL, 0); |
782 |
/* Better to cast the sizeof instead of rc */ |
783 |
if (rc <= (int)(sizeof(HEADER))) |
784 |
return; |
785 |
|
786 |
/* |
787 |
* convert DNS reply reader from Network byte order to CPU byte order. |
788 |
*/ |
789 |
header = (HEADER *)buf; |
790 |
header->ancount = ntohs(header->ancount); |
791 |
header->qdcount = ntohs(header->qdcount); |
792 |
header->nscount = ntohs(header->nscount); |
793 |
header->arcount = ntohs(header->arcount); |
794 |
|
795 |
/* |
796 |
* response for an id which we have already received an answer for |
797 |
* just ignore this response. |
798 |
*/ |
799 |
if (0 == (request = find_id(header->id))) |
800 |
return; |
801 |
|
802 |
/* |
803 |
* check against possibly fake replies |
804 |
*/ |
805 |
if (!res_ourserver(&lsin)) |
806 |
return; |
807 |
|
808 |
if ((header->rcode != NO_ERRORS) || (header->ancount == 0)) |
809 |
{ |
810 |
if (SERVFAIL == header->rcode) |
811 |
resend_query(request); |
812 |
else |
813 |
{ |
814 |
/* |
815 |
* If we havent already tried this, and we're looking up AAAA, try A |
816 |
* now |
817 |
*/ |
818 |
|
819 |
#ifdef IPV6 |
820 |
if (request->state == REQ_AAAA && request->type == T_AAAA) |
821 |
{ |
822 |
request->timeout += 4; |
823 |
resend_query(request); |
824 |
} |
825 |
else if (request->type == T_PTR && request->state != REQ_INT && |
826 |
request->addr.ss.ss_family == AF_INET6) |
827 |
{ |
828 |
request->state = REQ_INT; |
829 |
request->timeout += 4; |
830 |
request->retries--; |
831 |
resend_query(request); |
832 |
} |
833 |
else |
834 |
#endif |
835 |
{ |
836 |
/* |
837 |
* If a bad error was returned, we stop here and dont send |
838 |
* send any more (no retries granted). |
839 |
*/ |
840 |
(*request->query->callback)(request->query->ptr, NULL); |
841 |
rem_request(request); |
842 |
} |
843 |
} |
844 |
|
845 |
return; |
846 |
} |
847 |
/* |
848 |
* If this fails there was an error decoding the received packet, |
849 |
* try it again and hope it works the next time. |
850 |
*/ |
851 |
answer_count = proc_answer(request, header, buf, buf + rc); |
852 |
|
853 |
if (answer_count) |
854 |
{ |
855 |
if (request->type == T_PTR) |
856 |
{ |
857 |
if (request->name == NULL) |
858 |
{ |
859 |
/* |
860 |
* got a PTR response with no name, something bogus is happening |
861 |
* don't bother trying again, the client address doesn't resolve |
862 |
*/ |
863 |
(*request->query->callback)(request->query->ptr, reply); |
864 |
rem_request(request); |
865 |
return; |
866 |
} |
867 |
|
868 |
/* |
869 |
* Lookup the 'authoritative' name that we were given for the |
870 |
* ip#. |
871 |
* |
872 |
*/ |
873 |
#ifdef IPV6 |
874 |
if (request->addr.ss.ss_family == AF_INET6) |
875 |
gethost_byname_type(request->name, request->query, T_AAAA); |
876 |
else |
877 |
#endif |
878 |
gethost_byname_type(request->name, request->query, T_A); |
879 |
rem_request(request); |
880 |
} |
881 |
else |
882 |
{ |
883 |
/* |
884 |
* got a name and address response, client resolved |
885 |
*/ |
886 |
reply = make_dnsreply(request); |
887 |
(*request->query->callback)(request->query->ptr, reply); |
888 |
MyFree(reply); |
889 |
rem_request(request); |
890 |
} |
891 |
} |
892 |
else if (!request->sent) |
893 |
{ |
894 |
/* XXX - we got a response for a query we didn't send with a valid id? |
895 |
* this should never happen, bail here and leave the client unresolved |
896 |
*/ |
897 |
assert(0); |
898 |
|
899 |
/* XXX don't leak it */ |
900 |
rem_request(request); |
901 |
} |
902 |
} |
903 |
|
904 |
static struct DNSReply * |
905 |
make_dnsreply(struct reslist *request) |
906 |
{ |
907 |
struct DNSReply *cp; |
908 |
assert(request != 0); |
909 |
|
910 |
cp = (struct DNSReply *)MyMalloc(sizeof(struct DNSReply)); |
911 |
|
912 |
cp->h_name = request->name; |
913 |
memcpy(&cp->addr, &request->addr, sizeof(cp->addr)); |
914 |
return(cp); |
915 |
} |
916 |
|
917 |
void |
918 |
report_dns_servers(struct Client *source_p) |
919 |
{ |
920 |
int i; |
921 |
char ipaddr[HOSTIPLEN]; |
922 |
|
923 |
for (i = 0; i < irc_nscount; i++) |
924 |
{ |
925 |
irc_getnameinfo((struct sockaddr *)&(irc_nsaddr_list[i]), |
926 |
irc_nsaddr_list[i].ss_len, ipaddr, HOSTIPLEN, NULL, 0, |
927 |
NI_NUMERICHOST); |
928 |
sendto_one(source_p, form_str(RPL_STATSALINE), |
929 |
me.name, source_p->name, ipaddr); |
930 |
} |
931 |
} |