/[svn]/ircd-hybrid-7.2/src/irc_res.c
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Annotation of /ircd-hybrid-7.2/src/irc_res.c

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Revision 998 - (hide annotations)
Sun Aug 23 12:43:17 2009 UTC (10 years, 1 month ago) by michael
File MIME type: text/x-chdr
File size: 23097 byte(s)
- change resolver/auth to use balloc memory pool
- ircd.c: init_resolver() has to be called *before* read_conf_files(), otherwise
  recvfrom() aborts with ENOTSOCK in case there are configured connect{} blocks
  with a host that needs to be resolved on the very first configuration read.

1 adx 30 /*
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 knight 31 * $Id$
11 adx 30 *
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 michael 998 #include "balloc.h"
25 adx 30 #include "client.h"
26     #include "list.h"
27     #include "common.h"
28     #include "event.h"
29     #include "irc_string.h"
30     #include "sprintf_irc.h"
31     #include "ircd.h"
32     #include "numeric.h"
33     #include "restart.h"
34 michael 982 #include "rng_mt.h"
35 adx 30 #include "fdlist.h"
36     #include "fileio.h" /* for fbopen / fbclose / fbputs */
37     #include "s_bsd.h"
38     #include "s_log.h"
39     #include "send.h"
40     #include "memory.h"
41     #include "irc_res.h"
42     #include "irc_reslib.h"
43     #include "irc_getnameinfo.h"
44    
45     #if (CHAR_BIT != 8)
46     #error this code needs to be able to address individual octets
47     #endif
48    
49     static PF res_readreply;
50    
51     #define MAXPACKET 1024 /* rfc sez 512 but we expand names so ... */
52     #define RES_MAXALIASES 35 /* maximum aliases allowed */
53     #define RES_MAXADDRS 35 /* maximum addresses allowed */
54     #define AR_TTL 600 /* TTL in seconds for dns cache entries */
55    
56     /* RFC 1104/1105 wasn't very helpful about what these fields
57     * should be named, so for now, we'll just name them this way.
58     * we probably should look at what named calls them or something.
59     */
60     #define TYPE_SIZE (size_t)2
61     #define CLASS_SIZE (size_t)2
62     #define TTL_SIZE (size_t)4
63     #define RDLENGTH_SIZE (size_t)2
64     #define ANSWER_FIXED_SIZE (TYPE_SIZE + CLASS_SIZE + TTL_SIZE + RDLENGTH_SIZE)
65    
66     typedef enum
67     {
68     REQ_IDLE, /* We're doing not much at all */
69     REQ_PTR, /* Looking up a PTR */
70     REQ_A, /* Looking up an A, possibly because AAAA failed */
71     #ifdef IPV6
72     REQ_AAAA, /* Looking up an AAAA */
73     #endif
74 michael 985 REQ_CNAME /* We got a CNAME in response, we better get a real answer next */
75 adx 30 } request_state;
76    
77     struct reslist
78     {
79     dlink_node node;
80     int id;
81     int sent; /* number of requests sent */
82     request_state state; /* State the resolver machine is in */
83     time_t ttl;
84     char type;
85     char retries; /* retry counter */
86     char sends; /* number of sends (>1 means resent) */
87     char resend; /* send flag. 0 == dont resend */
88     time_t sentat;
89     time_t timeout;
90     struct irc_ssaddr addr;
91     char *name;
92 michael 992 dns_callback_fnc callback;
93     void *callback_ctx;
94 adx 30 };
95    
96     static fde_t ResolverFileDescriptor;
97 michael 986 static dlink_list request_list = { NULL, NULL, 0 };
98 michael 998 static BlockHeap *dns_heap = NULL;
99 adx 30
100     static void rem_request(struct reslist *request);
101 michael 992 static struct reslist *make_request(dns_callback_fnc callback, void *);
102     static void do_query_name(dns_callback_fnc callback, void *,
103     const char *, struct reslist *, int);
104     static void do_query_number(dns_callback_fnc callback, void *ctx,
105 adx 30 const struct irc_ssaddr *,
106     struct reslist *request);
107     static void query_name(const char *name, int query_class, int query_type,
108     struct reslist *request);
109     static int send_res_msg(const char *buf, int len, int count);
110     static void resend_query(struct reslist *request);
111     static int proc_answer(struct reslist *request, HEADER *header, char *, char *);
112     static struct reslist *find_id(int id);
113    
114    
115     /*
116     * int
117     * res_ourserver(inp)
118     * looks up "inp" in irc_nsaddr_list[]
119     * returns:
120     * 0 : not found
121     * >0 : found
122     * author:
123     * paul vixie, 29may94
124     * revised for ircd, cryogen(stu) may03
125     */
126     static int
127     res_ourserver(const struct irc_ssaddr *inp)
128     {
129     #ifdef IPV6
130 michael 992 const struct sockaddr_in6 *v6;
131     const struct sockaddr_in6 *v6in = (const struct sockaddr_in6 *)inp;
132 adx 30 #endif
133 michael 992 const struct sockaddr_in *v4;
134     const struct sockaddr_in *v4in = (const struct sockaddr_in *)inp;
135 adx 30 int ns;
136    
137 michael 982 for (ns = 0; ns < irc_nscount; ns++)
138 adx 30 {
139     const struct irc_ssaddr *srv = &irc_nsaddr_list[ns];
140     #ifdef IPV6
141 michael 992 v6 = (const struct sockaddr_in6 *)srv;
142 adx 30 #endif
143 michael 992 v4 = (const struct sockaddr_in *)srv;
144 adx 30
145     /* could probably just memcmp(srv, inp, srv.ss_len) here
146     * but we'll air on the side of caution - stu
147     *
148     */
149     switch (srv->ss.ss_family)
150     {
151     #ifdef IPV6
152     case AF_INET6:
153     if (srv->ss.ss_family == inp->ss.ss_family)
154     if (v6->sin6_port == v6in->sin6_port)
155     if ((memcmp(&v6->sin6_addr.s6_addr, &v6in->sin6_addr.s6_addr,
156     sizeof(struct in6_addr)) == 0) ||
157     (memcmp(&v6->sin6_addr.s6_addr, &in6addr_any,
158     sizeof(struct in6_addr)) == 0))
159     return(1);
160     break;
161     #endif
162     case AF_INET:
163     if (srv->ss.ss_family == inp->ss.ss_family)
164     if (v4->sin_port == v4in->sin_port)
165     if ((v4->sin_addr.s_addr == INADDR_ANY) ||
166     (v4->sin_addr.s_addr == v4in->sin_addr.s_addr))
167     return(1);
168     break;
169     default:
170     break;
171     }
172     }
173    
174     return(0);
175     }
176    
177     /*
178     * timeout_query_list - Remove queries from the list which have been
179     * there too long without being resolved.
180     */
181     static time_t
182     timeout_query_list(time_t now)
183     {
184     dlink_node *ptr;
185     dlink_node *next_ptr;
186     struct reslist *request;
187     time_t next_time = 0;
188     time_t timeout = 0;
189    
190     DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head)
191     {
192     request = ptr->data;
193     timeout = request->sentat + request->timeout;
194    
195     if (now >= timeout)
196     {
197     if (--request->retries <= 0)
198     {
199 michael 992 (*request->callback)(request->callback_ctx, NULL, NULL);
200 adx 30 rem_request(request);
201     continue;
202     }
203     else
204     {
205     request->sentat = now;
206     request->timeout += request->timeout;
207     resend_query(request);
208     }
209     }
210    
211     if ((next_time == 0) || timeout < next_time)
212     {
213     next_time = timeout;
214     }
215     }
216    
217     return((next_time > now) ? next_time : (now + AR_TTL));
218     }
219    
220     /*
221     * timeout_resolver - check request list
222     */
223     static void
224     timeout_resolver(void *notused)
225     {
226     timeout_query_list(CurrentTime);
227     }
228    
229     /*
230     * start_resolver - do everything we need to read the resolv.conf file
231     * and initialize the resolver file descriptor if needed
232     */
233     static void
234     start_resolver(void)
235     {
236     irc_res_init();
237    
238     if (!ResolverFileDescriptor.flags.open)
239     {
240     if (comm_open(&ResolverFileDescriptor, irc_nsaddr_list[0].ss.ss_family,
241     SOCK_DGRAM, 0, "Resolver socket") == -1)
242     return;
243    
244     /* At the moment, the resolver FD data is global .. */
245     comm_setselect(&ResolverFileDescriptor, COMM_SELECT_READ,
246     res_readreply, NULL, 0);
247     eventAdd("timeout_resolver", timeout_resolver, NULL, 1);
248     }
249     }
250    
251     /*
252     * init_resolver - initialize resolver and resolver library
253     */
254     void
255     init_resolver(void)
256     {
257 michael 998 dns_heap = BlockHeapCreate("dns", sizeof(struct reslist), DNS_HEAP_SIZE);
258 adx 30 memset(&ResolverFileDescriptor, 0, sizeof(fde_t));
259     start_resolver();
260     }
261    
262     /*
263     * restart_resolver - reread resolv.conf, reopen socket
264     */
265     void
266     restart_resolver(void)
267     {
268     fd_close(&ResolverFileDescriptor);
269     eventDelete(timeout_resolver, NULL); /* -ddosen */
270     start_resolver();
271     }
272    
273     /*
274     * rem_request - remove a request from the list.
275     * This must also free any memory that has been allocated for
276     * temporary storage of DNS results.
277     */
278     static void
279     rem_request(struct reslist *request)
280     {
281     dlinkDelete(&request->node, &request_list);
282 michael 998
283 adx 30 MyFree(request->name);
284 michael 998 BlockHeapFree(dns_heap, request);
285 adx 30 }
286    
287     /*
288     * make_request - Create a DNS request record for the server.
289     */
290     static struct reslist *
291 michael 992 make_request(dns_callback_fnc callback, void *ctx)
292 adx 30 {
293 michael 998 struct reslist *request = BlockHeapAlloc(dns_heap);
294 adx 30
295 michael 992 request->sentat = CurrentTime;
296     request->retries = 3;
297     request->resend = 1;
298     request->timeout = 4; /* start at 4 and exponential inc. */
299     request->state = REQ_IDLE;
300     request->callback = callback;
301     request->callback_ctx = ctx;
302 adx 30
303     dlinkAdd(request, &request->node, &request_list);
304 michael 998 return request;
305 adx 30 }
306    
307     /*
308     * delete_resolver_queries - cleanup outstanding queries
309     * for which there no longer exist clients or conf lines.
310     */
311     void
312 michael 992 delete_resolver_queries(const void *vptr)
313 adx 30 {
314 michael 997 dlink_node *ptr = NULL, *next_ptr = NULL;
315 adx 30
316     DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head)
317     {
318 michael 997 struct reslist *request = ptr->data;
319    
320     if (request->callback_ctx == vptr)
321     rem_request(request);
322 adx 30 }
323     }
324    
325     /*
326     * send_res_msg - sends msg to all nameservers found in the "_res" structure.
327     * This should reflect /etc/resolv.conf. We will get responses
328     * which arent needed but is easier than checking to see if nameserver
329     * isnt present. Returns number of messages successfully sent to
330     * nameservers or -1 if no successful sends.
331     */
332     static int
333     send_res_msg(const char *msg, int len, int rcount)
334     {
335     int i;
336     int sent = 0;
337     int max_queries = IRCD_MIN(irc_nscount, rcount);
338    
339     /* RES_PRIMARY option is not implemented
340     * if (res.options & RES_PRIMARY || 0 == max_queries)
341     */
342     if (max_queries == 0)
343     max_queries = 1;
344    
345     for (i = 0; i < max_queries; i++)
346     {
347     if (sendto(ResolverFileDescriptor.fd, msg, len, 0,
348     (struct sockaddr*)&(irc_nsaddr_list[i]),
349     irc_nsaddr_list[i].ss_len) == len)
350     ++sent;
351     }
352    
353     return(sent);
354     }
355    
356     /*
357     * find_id - find a dns request id (id is determined by dn_mkquery)
358     */
359     static struct reslist *
360     find_id(int id)
361     {
362     dlink_node *ptr;
363     struct reslist *request;
364    
365     DLINK_FOREACH(ptr, request_list.head)
366     {
367     request = ptr->data;
368    
369     if (request->id == id)
370     return(request);
371     }
372    
373     return(NULL);
374     }
375    
376     /*
377     * gethost_byname_type - get host address from name
378     *
379     */
380     void
381 michael 992 gethost_byname_type(dns_callback_fnc callback, void *ctx, const char *name, int type)
382 adx 30 {
383     assert(name != 0);
384 michael 992 do_query_name(callback, ctx, name, NULL, type);
385 adx 30 }
386    
387     /*
388     * gethost_byname - wrapper for _type - send T_AAAA first if IPV6 supported
389     */
390     void
391 michael 992 gethost_byname(dns_callback_fnc callback, void *ctx, const char *name)
392 adx 30 {
393     #ifdef IPV6
394 michael 992 gethost_byname_type(callback, ctx, name, T_AAAA);
395 adx 30 #else
396 michael 992 gethost_byname_type(callback, ctx, name, T_A);
397 adx 30 #endif
398     }
399    
400     /*
401     * gethost_byaddr - get host name from address
402     */
403     void
404 michael 992 gethost_byaddr(dns_callback_fnc callback, void *ctx, const struct irc_ssaddr *addr)
405 adx 30 {
406 michael 992 do_query_number(callback, ctx, addr, NULL);
407 adx 30 }
408    
409     /*
410     * do_query_name - nameserver lookup name
411     */
412     static void
413 michael 992 do_query_name(dns_callback_fnc callback, void *ctx, const char *name,
414 adx 30 struct reslist *request, int type)
415     {
416     char host_name[HOSTLEN + 1];
417    
418 michael 998 strlcpy(host_name, name, sizeof(host_name));
419 adx 30
420     if (request == NULL)
421     {
422 michael 992 request = make_request(callback, ctx);
423 michael 986 request->name = MyMalloc(strlen(host_name) + 1);
424 adx 30 request->type = type;
425     strcpy(request->name, host_name);
426     #ifdef IPV6
427 michael 984 if (type != T_A)
428     request->state = REQ_AAAA;
429 adx 30 else
430 michael 984 #endif
431 adx 30 request->state = REQ_A;
432     }
433    
434     request->type = type;
435     query_name(host_name, C_IN, type, request);
436     }
437    
438     /*
439     * do_query_number - Use this to do reverse IP# lookups.
440     */
441     static void
442 michael 992 do_query_number(dns_callback_fnc callback, void *ctx,
443     const struct irc_ssaddr *addr,
444 adx 30 struct reslist *request)
445     {
446     char ipbuf[128];
447     const unsigned char *cp;
448 michael 985
449 adx 30 if (addr->ss.ss_family == AF_INET)
450     {
451 michael 992 const struct sockaddr_in *v4 = (const struct sockaddr_in *)addr;
452 adx 30 cp = (const unsigned char*)&v4->sin_addr.s_addr;
453    
454     ircsprintf(ipbuf, "%u.%u.%u.%u.in-addr.arpa.",
455     (unsigned int)(cp[3]), (unsigned int)(cp[2]),
456     (unsigned int)(cp[1]), (unsigned int)(cp[0]));
457     }
458     #ifdef IPV6
459     else if (addr->ss.ss_family == AF_INET6)
460     {
461 michael 992 const struct sockaddr_in6 *v6 = (const struct sockaddr_in6 *)addr;
462 adx 30 cp = (const unsigned char *)&v6->sin6_addr.s6_addr;
463    
464 michael 985 sprintf(ipbuf, "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x."
465     "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.ip6.arpa.",
466 adx 30 (unsigned int)(cp[15]&0xf), (unsigned int)(cp[15]>>4),
467     (unsigned int)(cp[14]&0xf), (unsigned int)(cp[14]>>4),
468     (unsigned int)(cp[13]&0xf), (unsigned int)(cp[13]>>4),
469     (unsigned int)(cp[12]&0xf), (unsigned int)(cp[12]>>4),
470     (unsigned int)(cp[11]&0xf), (unsigned int)(cp[11]>>4),
471     (unsigned int)(cp[10]&0xf), (unsigned int)(cp[10]>>4),
472     (unsigned int)(cp[9]&0xf), (unsigned int)(cp[9]>>4),
473     (unsigned int)(cp[8]&0xf), (unsigned int)(cp[8]>>4),
474     (unsigned int)(cp[7]&0xf), (unsigned int)(cp[7]>>4),
475     (unsigned int)(cp[6]&0xf), (unsigned int)(cp[6]>>4),
476     (unsigned int)(cp[5]&0xf), (unsigned int)(cp[5]>>4),
477     (unsigned int)(cp[4]&0xf), (unsigned int)(cp[4]>>4),
478     (unsigned int)(cp[3]&0xf), (unsigned int)(cp[3]>>4),
479     (unsigned int)(cp[2]&0xf), (unsigned int)(cp[2]>>4),
480     (unsigned int)(cp[1]&0xf), (unsigned int)(cp[1]>>4),
481 michael 985 (unsigned int)(cp[0]&0xf), (unsigned int)(cp[0]>>4));
482 adx 30 }
483     #endif
484     if (request == NULL)
485     {
486 michael 992 request = make_request(callback, ctx);
487 adx 30 request->type = T_PTR;
488     memcpy(&request->addr, addr, sizeof(struct irc_ssaddr));
489 michael 986 request->name = MyMalloc(HOSTLEN + 1);
490 adx 30 }
491    
492     query_name(ipbuf, C_IN, T_PTR, request);
493     }
494    
495     /*
496     * query_name - generate a query based on class, type and name.
497     */
498     static void
499     query_name(const char *name, int query_class, int type,
500     struct reslist *request)
501     {
502     char buf[MAXPACKET];
503     int request_len = 0;
504    
505     memset(buf, 0, sizeof(buf));
506    
507     if ((request_len = irc_res_mkquery(name, query_class, type,
508     (unsigned char *)buf, sizeof(buf))) > 0)
509     {
510     HEADER *header = (HEADER *)buf;
511 michael 982
512 adx 30 /*
513     * generate an unique id
514     * NOTE: we don't have to worry about converting this to and from
515     * network byte order, the nameserver does not interpret this value
516     * and returns it unchanged
517     */
518     do
519 michael 982 header->id = (header->id + genrand_int32()) & 0xffff;
520     while (find_id(header->id));
521    
522 adx 30 request->id = header->id;
523     ++request->sends;
524    
525     request->sent += send_res_msg(buf, request_len, request->sends);
526     }
527     }
528    
529     static void
530     resend_query(struct reslist *request)
531     {
532     if (request->resend == 0)
533     return;
534    
535 michael 982 switch (request->type)
536 adx 30 {
537     case T_PTR:
538 michael 992 do_query_number(NULL, NULL, &request->addr, request);
539 adx 30 break;
540     case T_A:
541 michael 992 do_query_name(NULL, NULL, request->name, request, request->type);
542 adx 30 break;
543     #ifdef IPV6
544     case T_AAAA:
545     /* didnt work, try A */
546     if (request->state == REQ_AAAA)
547 michael 992 do_query_name(NULL, NULL, request->name, request, T_A);
548 adx 30 #endif
549     default:
550     break;
551     }
552     }
553    
554     /*
555     * proc_answer - process name server reply
556     */
557     static int
558     proc_answer(struct reslist *request, HEADER* header, char* buf, char* eob)
559     {
560     char hostbuf[HOSTLEN + 100]; /* working buffer */
561     unsigned char *current; /* current position in buf */
562     int query_class; /* answer class */
563     int type; /* answer type */
564     int n; /* temp count */
565     int rd_length;
566     struct sockaddr_in *v4; /* conversion */
567     #ifdef IPV6
568     struct sockaddr_in6 *v6;
569     #endif
570     current = (unsigned char *)buf + sizeof(HEADER);
571    
572     for (; header->qdcount > 0; --header->qdcount)
573     {
574     if ((n = irc_dn_skipname(current, (unsigned char *)eob)) < 0)
575     break;
576    
577     current += (size_t) n + QFIXEDSZ;
578     }
579    
580     /*
581     * process each answer sent to us blech.
582     */
583     while (header->ancount > 0 && (char *)current < eob)
584     {
585     header->ancount--;
586    
587     n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current,
588     hostbuf, sizeof(hostbuf));
589    
590     if (n < 0)
591     {
592     /*
593     * broken message
594     */
595     return(0);
596     }
597     else if (n == 0)
598     {
599     /*
600     * no more answers left
601     */
602     return(0);
603     }
604    
605     hostbuf[HOSTLEN] = '\0';
606    
607     /* With Address arithmetic you have to be very anal
608     * this code was not working on alpha due to that
609     * (spotted by rodder/jailbird/dianora)
610     */
611     current += (size_t) n;
612    
613     if (!(((char *)current + ANSWER_FIXED_SIZE) < eob))
614     break;
615    
616     type = irc_ns_get16(current);
617     current += TYPE_SIZE;
618    
619     query_class = irc_ns_get16(current);
620     current += CLASS_SIZE;
621    
622     request->ttl = irc_ns_get32(current);
623     current += TTL_SIZE;
624    
625     rd_length = irc_ns_get16(current);
626     current += RDLENGTH_SIZE;
627    
628     /*
629     * Wait to set request->type until we verify this structure
630     */
631     switch (type)
632     {
633     case T_A:
634     if (request->type != T_A)
635     return(0);
636    
637     /*
638     * check for invalid rd_length or too many addresses
639     */
640     if (rd_length != sizeof(struct in_addr))
641     return(0);
642     v4 = (struct sockaddr_in *)&request->addr;
643     request->addr.ss_len = sizeof(struct sockaddr_in);
644     v4->sin_family = AF_INET;
645     memcpy(&v4->sin_addr, current, sizeof(struct in_addr));
646     return(1);
647     break;
648     #ifdef IPV6
649     case T_AAAA:
650     if (request->type != T_AAAA)
651     return(0);
652     if (rd_length != sizeof(struct in6_addr))
653     return(0);
654     request->addr.ss_len = sizeof(struct sockaddr_in6);
655     v6 = (struct sockaddr_in6 *)&request->addr;
656     v6->sin6_family = AF_INET6;
657     memcpy(&v6->sin6_addr, current, sizeof(struct in6_addr));
658     return(1);
659     break;
660     #endif
661     case T_PTR:
662     if (request->type != T_PTR)
663     return(0);
664     n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob,
665     current, hostbuf, sizeof(hostbuf));
666     if (n < 0)
667     return(0); /* broken message */
668     else if (n == 0)
669     return(0); /* no more answers left */
670    
671 michael 986 strlcpy(request->name, hostbuf, HOSTLEN + 1);
672 adx 30
673     return(1);
674     break;
675     case T_CNAME: /* first check we already havent started looking
676     into a cname */
677     if (request->type != T_PTR)
678     return(0);
679    
680     if (request->state == REQ_CNAME)
681     {
682     n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob,
683     current, hostbuf, sizeof(hostbuf));
684    
685     if (n < 0)
686     return(0);
687     return(1);
688     }
689    
690     request->state = REQ_CNAME;
691     current += rd_length;
692     break;
693    
694     default:
695     /* XXX I'd rather just throw away the entire bogus thing
696     * but its possible its just a broken nameserver with still
697     * valid answers. But lets do some rudimentary logging for now...
698     */
699     ilog(L_ERROR, "irc_res.c bogus type %d", type);
700     break;
701     }
702     }
703    
704     return(1);
705     }
706    
707     /*
708     * res_readreply - read a dns reply from the nameserver and process it.
709     */
710     static void
711     res_readreply(fde_t *fd, void *data)
712     {
713 adx 411 char buf[sizeof(HEADER) + MAXPACKET]
714     /* Sparc and alpha need 16bit-alignment for accessing header->id
715     * (which is uint16_t). Because of the header = (HEADER*) buf;
716     * lateron, this is neeeded. --FaUl
717     */
718     #if defined(__sparc__) || defined(__alpha__)
719     __attribute__((aligned (16)))
720     #endif
721     ;
722 adx 30 HEADER *header;
723     struct reslist *request = NULL;
724     int rc;
725     socklen_t len = sizeof(struct irc_ssaddr);
726     struct irc_ssaddr lsin;
727    
728     rc = recvfrom(fd->fd, buf, sizeof(buf), 0, (struct sockaddr *)&lsin, &len);
729    
730     /* Re-schedule a read *after* recvfrom, or we'll be registering
731     * interest where it'll instantly be ready for read :-) -- adrian
732     */
733     comm_setselect(fd, COMM_SELECT_READ, res_readreply, NULL, 0);
734 michael 984
735 adx 30 /* Better to cast the sizeof instead of rc */
736     if (rc <= (int)(sizeof(HEADER)))
737     return;
738    
739     /*
740     * convert DNS reply reader from Network byte order to CPU byte order.
741     */
742     header = (HEADER *)buf;
743     header->ancount = ntohs(header->ancount);
744     header->qdcount = ntohs(header->qdcount);
745     header->nscount = ntohs(header->nscount);
746     header->arcount = ntohs(header->arcount);
747    
748     /*
749 michael 994 * check against possibly fake replies
750 adx 30 */
751 michael 994 if (!res_ourserver(&lsin))
752 adx 30 return;
753    
754     /*
755 michael 994 * response for an id which we have already received an answer for
756     * just ignore this response.
757 adx 30 */
758 michael 994 if (!(request = find_id(header->id)))
759 adx 30 return;
760    
761     if ((header->rcode != NO_ERRORS) || (header->ancount == 0))
762     {
763 michael 984 if (header->rcode == SERVFAIL || header->rcode == NXDOMAIN)
764 db 155 {
765 michael 984 /*
766     * If a bad error was returned, stop here and don't
767     * send any more (no retries granted).
768     */
769 michael 992 (*request->callback)(request->callback_ctx, NULL, NULL);
770 michael 984 rem_request(request);
771     }
772     #ifdef IPV6
773     else
774     {
775 adx 30 /*
776     * If we havent already tried this, and we're looking up AAAA, try A
777     * now
778     */
779     if (request->state == REQ_AAAA && request->type == T_AAAA)
780     {
781     request->timeout += 4;
782     resend_query(request);
783     }
784 michael 984 }
785 adx 30 #endif
786 michael 984
787 db 468 return;
788 adx 30 }
789 michael 984
790 adx 30 /*
791     * If this fails there was an error decoding the received packet,
792     * try it again and hope it works the next time.
793     */
794 michael 994 if (proc_answer(request, header, buf, buf + rc))
795 adx 30 {
796     if (request->type == T_PTR)
797     {
798     if (request->name == NULL)
799     {
800     /*
801     * got a PTR response with no name, something bogus is happening
802     * don't bother trying again, the client address doesn't resolve
803     */
804 michael 992 (*request->callback)(request->callback_ctx, NULL, NULL);
805 adx 30 rem_request(request);
806     return;
807     }
808    
809     /*
810     * Lookup the 'authoritative' name that we were given for the
811     * ip#.
812     *
813     */
814     #ifdef IPV6
815     if (request->addr.ss.ss_family == AF_INET6)
816 michael 992 gethost_byname_type(request->callback, request->callback_ctx, request->name, T_AAAA);
817 adx 30 else
818     #endif
819 michael 992 gethost_byname_type(request->callback, request->callback_ctx, request->name, T_A);
820 adx 30 rem_request(request);
821     }
822     else
823     {
824     /*
825     * got a name and address response, client resolved
826     */
827 michael 992 (*request->callback)(request->callback_ctx, &request->addr, request->name);
828 adx 30 rem_request(request);
829     }
830     }
831     else if (!request->sent)
832     {
833     /* XXX - we got a response for a query we didn't send with a valid id?
834     * this should never happen, bail here and leave the client unresolved
835     */
836     assert(0);
837    
838     /* XXX don't leak it */
839     rem_request(request);
840     }
841     }
842    
843     void
844     report_dns_servers(struct Client *source_p)
845     {
846     int i;
847 michael 992 char ipaddr[HOSTIPLEN + 1];
848 adx 30
849     for (i = 0; i < irc_nscount; i++)
850     {
851     irc_getnameinfo((struct sockaddr *)&(irc_nsaddr_list[i]),
852 michael 992 irc_nsaddr_list[i].ss_len, ipaddr,
853     sizeof(ipaddr), NULL, 0, NI_NUMERICHOST);
854 adx 30 sendto_one(source_p, form_str(RPL_STATSALINE),
855     me.name, source_p->name, ipaddr);
856     }
857     }

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