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.
7 * The authors takes no responsibility for any damage or loss
8 * of property which results from the use of this software.
10 * $Id: res.c 3301 2007-03-28 15:04:06Z jilles $
11 * from Hybrid Id: res.c 459 2006-02-12 22:21:37Z db $
13 * July 1999 - Rewrote a bunch of stuff here. Change hostent builder code,
14 * added callbacks and reference counting of returned hostents.
15 * --Bleep (Thomas Helvey <tomh@inxpress.net>)
17 * This was all needlessly complicated for irc. Simplified. No more hostent
18 * All we really care about is the IP -> hostname mappings. Thats all.
20 * Apr 28, 2003 --cryogen and Dianora
22 * DNS server flooding lessened, AAAA-or-A lookup removed, ip6.int support
23 * removed, various robustness fixes
25 * 2006 --jilles and nenolod
29 #include "ircd_defs.h"
36 #include "client.h" /* SNO_* */
39 #error this code needs to be able to address individual octets
42 static PF res_readreply
;
44 #define MAXPACKET 1024 /* rfc sez 512 but we expand names so ... */
45 #define RES_MAXALIASES 35 /* maximum aliases allowed */
46 #define RES_MAXADDRS 35 /* maximum addresses allowed */
47 #define AR_TTL 600 /* TTL in seconds for dns cache entries */
49 /* RFC 1104/1105 wasn't very helpful about what these fields
50 * should be named, so for now, we'll just name them this way.
51 * we probably should look at what named calls them or something.
53 #define TYPE_SIZE (size_t)2
54 #define CLASS_SIZE (size_t)2
55 #define TTL_SIZE (size_t)4
56 #define RDLENGTH_SIZE (size_t)2
57 #define ANSWER_FIXED_SIZE (TYPE_SIZE + CLASS_SIZE + TTL_SIZE + RDLENGTH_SIZE)
61 REQ_IDLE
, /* We're doing not much at all */
62 REQ_PTR
, /* Looking up a PTR */
63 REQ_A
, /* Looking up an A or AAAA */
64 REQ_CNAME
/* We got a CNAME in response, we better get a real answer next */
71 int sent
; /* number of requests sent */
72 request_state state
; /* State the resolver machine is in */
75 char queryname
[128]; /* name currently being queried */
76 char retries
; /* retry counter */
77 char sends
; /* number of sends (>1 means resent) */
78 char resend
; /* send flag. 0 == dont resend */
81 struct rb_sockaddr_storage addr
;
83 struct DNSQuery
*query
; /* query callback for this request */
86 static rb_fde_t
*res_fd
;
87 static rb_dlink_list request_list
= { NULL
, NULL
, 0 };
89 static void rem_request(struct reslist
*request
);
90 static struct reslist
*make_request(struct DNSQuery
*query
);
91 static void do_query_name(struct DNSQuery
*query
, const char *name
, struct reslist
*request
, int);
92 static void do_query_number(struct DNSQuery
*query
, const struct rb_sockaddr_storage
*,
93 struct reslist
*request
);
94 static void query_name(struct reslist
*request
);
95 static int send_res_msg(const char *buf
, int len
, int count
);
96 static void resend_query(struct reslist
*request
);
97 static int check_question(struct reslist
*request
, HEADER
* header
, char *buf
, char *eob
);
98 static int proc_answer(struct reslist
*request
, HEADER
* header
, char *, char *);
99 static struct reslist
*find_id(int id
);
100 static struct DNSReply
*make_dnsreply(struct reslist
*request
);
105 * looks up "inp" in irc_nsaddr_list[]
110 * paul vixie, 29may94
111 * revised for ircd, cryogen(stu) may03
113 static int res_ourserver(const struct rb_sockaddr_storage
*inp
)
116 const struct sockaddr_in6
*v6
;
117 const struct sockaddr_in6
*v6in
= (const struct sockaddr_in6
*)inp
;
119 const struct sockaddr_in
*v4
;
120 const struct sockaddr_in
*v4in
= (const struct sockaddr_in
*)inp
;
123 for (ns
= 0; ns
< irc_nscount
; ns
++)
125 const struct rb_sockaddr_storage
*srv
= &irc_nsaddr_list
[ns
];
127 v6
= (const struct sockaddr_in6
*)srv
;
129 v4
= (const struct sockaddr_in
*)srv
;
131 /* could probably just memcmp(srv, inp, srv.ss_len) here
132 * but we'll air on the side of caution - stu
134 switch (srv
->ss_family
)
138 if (srv
->ss_family
== inp
->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))
148 if (srv
->ss_family
== inp
->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
))
163 * timeout_query_list - Remove queries from the list which have been
164 * there too long without being resolved.
166 static time_t timeout_query_list(time_t now
)
169 rb_dlink_node
*next_ptr
;
170 struct reslist
*request
;
171 time_t next_time
= 0;
174 RB_DLINK_FOREACH_SAFE(ptr
, next_ptr
, request_list
.head
)
177 timeout
= request
->sentat
+ request
->timeout
;
181 if (--request
->retries
<= 0)
183 (*request
->query
->callback
) (request
->query
->ptr
, NULL
);
184 rem_request(request
);
189 request
->sentat
= now
;
190 request
->timeout
+= request
->timeout
;
191 resend_query(request
);
195 if ((next_time
== 0) || timeout
< next_time
)
201 return (next_time
> now
) ? next_time
: (now
+ AR_TTL
);
205 * timeout_resolver - check request list
207 static void timeout_resolver(void *notused
)
209 timeout_query_list(rb_current_time());
212 static struct ev_entry
*timeout_resolver_ev
= NULL
;
215 * start_resolver - do everything we need to read the resolv.conf file
216 * and initialize the resolver file descriptor if needed
218 static void start_resolver(void)
224 if ((res_fd
= rb_socket(irc_nsaddr_list
[0].ss_family
, SOCK_DGRAM
, 0,
225 "UDP resolver socket")) == NULL
)
228 /* At the moment, the resolver FD data is global .. */
229 rb_setselect(res_fd
, RB_SELECT_READ
, res_readreply
, NULL
);
230 timeout_resolver_ev
= rb_event_add("timeout_resolver", timeout_resolver
, NULL
, 1);
235 * init_resolver - initialize resolver and resolver library
237 void init_resolver(void)
240 srand48(rb_current_time());
246 * restart_resolver - reread resolv.conf, reopen socket
248 void restart_resolver(void)
252 rb_event_delete(timeout_resolver_ev
); /* -ddosen */
257 * add_local_domain - Add the domain to hostname, if it is missing
258 * (as suggested by eps@TOASTER.SFSU.EDU)
260 void add_local_domain(char *hname
, size_t size
)
262 /* try to fix up unqualified names */
263 if (strchr(hname
, '.') == NULL
)
267 size_t len
= strlen(hname
);
269 if ((strlen(irc_domain
) + len
+ 2) < size
)
272 strcpy(hname
+ len
, irc_domain
);
279 * rem_request - remove a request from the list.
280 * This must also free any memory that has been allocated for
281 * temporary storage of DNS results.
283 static void rem_request(struct reslist
*request
)
285 rb_dlinkDelete(&request
->node
, &request_list
);
286 rb_free(request
->name
);
291 * make_request - Create a DNS request record for the server.
293 static struct reslist
*make_request(struct DNSQuery
*query
)
295 struct reslist
*request
= rb_malloc(sizeof(struct reslist
));
297 request
->sentat
= rb_current_time();
298 request
->retries
= 3;
300 request
->timeout
= 4; /* start at 4 and exponential inc. */
301 request
->query
= query
;
302 request
->state
= REQ_IDLE
;
304 rb_dlinkAdd(request
, &request
->node
, &request_list
);
310 * delete_resolver_queries - cleanup outstanding queries
311 * for which there no longer exist clients or conf lines.
313 void delete_resolver_queries(const struct DNSQuery
*query
)
316 rb_dlink_node
*next_ptr
;
317 struct reslist
*request
;
319 RB_DLINK_FOREACH_SAFE(ptr
, next_ptr
, request_list
.head
)
321 if ((request
= ptr
->data
) != NULL
)
323 if (query
== request
->query
)
324 rem_request(request
);
330 * send_res_msg - sends msg to all nameservers found in the "_res" structure.
331 * This should reflect /etc/resolv.conf. We will get responses
332 * which arent needed but is easier than checking to see if nameserver
333 * isnt present. Returns number of messages successfully sent to
334 * nameservers or -1 if no successful sends.
336 static int send_res_msg(const char *msg
, int len
, int rcount
)
340 int max_queries
= IRCD_MIN(irc_nscount
, rcount
);
342 /* RES_PRIMARY option is not implemented
343 * if (res.options & RES_PRIMARY || 0 == max_queries)
345 if (max_queries
== 0)
348 for (i
= 0; sent
< max_queries
&& i
< irc_nscount
; i
++)
350 if (sendto(rb_get_fd(res_fd
), msg
, len
, 0,
351 (struct sockaddr
*)&(irc_nsaddr_list
[i
]),
352 GET_SS_LEN(&irc_nsaddr_list
[i
])) == len
)
360 * find_id - find a dns request id (id is determined by dn_mkquery)
362 static struct reslist
*find_id(int id
)
365 struct reslist
*request
;
367 RB_DLINK_FOREACH(ptr
, request_list
.head
)
371 if (request
->id
== id
)
379 * gethost_byname_type - get host address from name
382 void gethost_byname_type(const char *name
, struct DNSQuery
*query
, int type
)
385 do_query_name(query
, name
, NULL
, type
);
389 * gethost_byaddr - get host name from address
391 void gethost_byaddr(const struct rb_sockaddr_storage
*addr
, struct DNSQuery
*query
)
393 do_query_number(query
, addr
, NULL
);
397 * do_query_name - nameserver lookup name
399 static void do_query_name(struct DNSQuery
*query
, const char *name
, struct reslist
*request
,
402 char host_name
[HOSTLEN
+ 1];
404 rb_strlcpy(host_name
, name
, HOSTLEN
+ 1);
405 add_local_domain(host_name
, HOSTLEN
);
409 request
= make_request(query
);
410 request
->name
= (char *)rb_malloc(strlen(host_name
) + 1);
411 strcpy(request
->name
, host_name
);
412 request
->state
= REQ_A
;
415 rb_strlcpy(request
->queryname
, host_name
, sizeof(request
->queryname
));
416 request
->type
= type
;
421 * do_query_number - Use this to do reverse IP# lookups.
423 static void do_query_number(struct DNSQuery
*query
, const struct rb_sockaddr_storage
*addr
,
424 struct reslist
*request
)
426 const unsigned char *cp
;
430 request
= make_request(query
);
431 memcpy(&request
->addr
, addr
, sizeof(struct rb_sockaddr_storage
));
432 request
->name
= (char *)rb_malloc(HOSTLEN
+ 1);
435 if (addr
->ss_family
== AF_INET
)
437 const struct sockaddr_in
*v4
= (const struct sockaddr_in
*)addr
;
438 cp
= (const unsigned char *)&v4
->sin_addr
.s_addr
;
440 rb_sprintf(request
->queryname
, "%u.%u.%u.%u.in-addr.arpa", (unsigned int)(cp
[3]),
441 (unsigned int)(cp
[2]), (unsigned int)(cp
[1]), (unsigned int)(cp
[0]));
444 else if (addr
->ss_family
== AF_INET6
)
446 const struct sockaddr_in6
*v6
= (const struct sockaddr_in6
*)addr
;
447 cp
= (const unsigned char *)&v6
->sin6_addr
.s6_addr
;
449 (void)sprintf(request
->queryname
, "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x."
450 "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.ip6.arpa",
451 (unsigned int)(cp
[15] & 0xf), (unsigned int)(cp
[15] >> 4),
452 (unsigned int)(cp
[14] & 0xf), (unsigned int)(cp
[14] >> 4),
453 (unsigned int)(cp
[13] & 0xf), (unsigned int)(cp
[13] >> 4),
454 (unsigned int)(cp
[12] & 0xf), (unsigned int)(cp
[12] >> 4),
455 (unsigned int)(cp
[11] & 0xf), (unsigned int)(cp
[11] >> 4),
456 (unsigned int)(cp
[10] & 0xf), (unsigned int)(cp
[10] >> 4),
457 (unsigned int)(cp
[9] & 0xf), (unsigned int)(cp
[9] >> 4),
458 (unsigned int)(cp
[8] & 0xf), (unsigned int)(cp
[8] >> 4),
459 (unsigned int)(cp
[7] & 0xf), (unsigned int)(cp
[7] >> 4),
460 (unsigned int)(cp
[6] & 0xf), (unsigned int)(cp
[6] >> 4),
461 (unsigned int)(cp
[5] & 0xf), (unsigned int)(cp
[5] >> 4),
462 (unsigned int)(cp
[4] & 0xf), (unsigned int)(cp
[4] >> 4),
463 (unsigned int)(cp
[3] & 0xf), (unsigned int)(cp
[3] >> 4),
464 (unsigned int)(cp
[2] & 0xf), (unsigned int)(cp
[2] >> 4),
465 (unsigned int)(cp
[1] & 0xf), (unsigned int)(cp
[1] >> 4),
466 (unsigned int)(cp
[0] & 0xf), (unsigned int)(cp
[0] >> 4));
470 request
->type
= T_PTR
;
475 * query_name - generate a query based on class, type and name.
477 static void query_name(struct reslist
*request
)
482 memset(buf
, 0, sizeof(buf
));
485 irc_res_mkquery(request
->queryname
, C_IN
, request
->type
, (unsigned char *)buf
, sizeof(buf
))) > 0)
487 HEADER
*header
= (HEADER
*) buf
;
493 * generate an unique id
494 * NOTE: we don't have to worry about converting this to and from
495 * network byte order, the nameserver does not interpret this value
496 * and returns it unchanged
501 header
->id
= (header
->id
+ lrand48()) & 0xffff;
502 } while (find_id(header
->id
));
504 gettimeofday(&tv
, NULL
);
507 header
->id
= (header
->id
+ k
+ tv
.tv_usec
) & 0xffff;
509 } while (find_id(header
->id
));
510 #endif /* HAVE_LRAND48 */
511 request
->id
= header
->id
;
514 request
->sent
+= send_res_msg(buf
, request_len
, request
->sends
);
518 static void resend_query(struct reslist
*request
)
520 if (request
->resend
== 0)
523 switch (request
->type
)
526 do_query_number(NULL
, &request
->addr
, request
);
532 do_query_name(NULL
, request
->name
, request
, request
->type
);
540 * check_question - check if the reply really belongs to the
541 * name we queried (to guard against late replies from previous
542 * queries with the same id).
544 static int check_question(struct reslist
*request
, HEADER
* header
, char *buf
, char *eob
)
546 char hostbuf
[128]; /* working buffer */
547 unsigned char *current
; /* current position in buf */
548 int n
; /* temp count */
550 current
= (unsigned char *)buf
+ sizeof(HEADER
);
551 if (header
->qdcount
!= 1)
553 n
= irc_dn_expand((unsigned char *)buf
, (unsigned char *)eob
, current
, hostbuf
,
557 if (strcasecmp(hostbuf
, request
->queryname
))
563 * proc_answer - process name server reply
565 static int proc_answer(struct reslist
*request
, HEADER
* header
, char *buf
, char *eob
)
567 char hostbuf
[HOSTLEN
+ 100]; /* working buffer */
568 unsigned char *current
; /* current position in buf */
569 int query_class
; /* answer class */
570 int type
; /* answer type */
571 int n
; /* temp count */
573 struct sockaddr_in
*v4
; /* conversion */
575 struct sockaddr_in6
*v6
;
577 current
= (unsigned char *)buf
+ sizeof(HEADER
);
579 for (; header
->qdcount
> 0; --header
->qdcount
)
581 if ((n
= irc_dn_skipname(current
, (unsigned char *)eob
)) < 0)
584 current
+= (size_t) n
+ QFIXEDSZ
;
588 * process each answer sent to us blech.
590 while (header
->ancount
> 0 && (char *)current
< eob
)
594 n
= irc_dn_expand((unsigned char *)buf
, (unsigned char *)eob
, current
, hostbuf
,
607 * no more answers left
612 hostbuf
[HOSTLEN
] = '\0';
614 /* With Address arithmetic you have to be very anal
615 * this code was not working on alpha due to that
616 * (spotted by rodder/jailbird/dianora)
618 current
+= (size_t) n
;
620 if (!(((char *)current
+ ANSWER_FIXED_SIZE
) < eob
))
623 type
= irc_ns_get16(current
);
624 current
+= TYPE_SIZE
;
626 query_class
= irc_ns_get16(current
);
627 current
+= CLASS_SIZE
;
629 request
->ttl
= irc_ns_get32(current
);
632 rd_length
= irc_ns_get16(current
);
633 current
+= RDLENGTH_SIZE
;
636 * Wait to set request->type until we verify this structure
641 if (request
->type
!= T_A
)
645 * check for invalid rd_length or too many addresses
647 if (rd_length
!= sizeof(struct in_addr
))
649 v4
= (struct sockaddr_in
*)&request
->addr
;
650 SET_SS_LEN(&request
->addr
, sizeof(struct sockaddr_in
));
651 v4
->sin_family
= AF_INET
;
652 memcpy(&v4
->sin_addr
, current
, sizeof(struct in_addr
));
657 if (request
->type
!= T_AAAA
)
659 if (rd_length
!= sizeof(struct in6_addr
))
661 SET_SS_LEN(&request
->addr
, sizeof(struct sockaddr_in6
));
662 v6
= (struct sockaddr_in6
*)&request
->addr
;
663 v6
->sin6_family
= AF_INET6
;
664 memcpy(&v6
->sin6_addr
, current
, sizeof(struct in6_addr
));
669 if (request
->type
!= T_PTR
)
671 n
= irc_dn_expand((unsigned char *)buf
, (unsigned char *)eob
, current
,
672 hostbuf
, sizeof(hostbuf
));
674 return (0); /* broken message */
676 return (0); /* no more answers left */
678 rb_strlcpy(request
->name
, hostbuf
, HOSTLEN
+ 1);
682 case T_CNAME
: /* first check we already havent started looking
684 if (request
->type
!= T_PTR
)
687 if (request
->state
== REQ_CNAME
)
689 n
= irc_dn_expand((unsigned char *)buf
, (unsigned char *)eob
,
690 current
, hostbuf
, sizeof(hostbuf
));
697 request
->state
= REQ_CNAME
;
698 current
+= rd_length
;
702 /* XXX I'd rather just throw away the entire bogus thing
703 * but its possible its just a broken nameserver with still
704 * valid answers. But lets do some rudimentary logging for now...
706 ilog(L_MAIN
, "irc_res.c bogus type %d", type
);
715 * res_readreply - read a dns reply from the nameserver and process it.
717 static void res_readreply(rb_fde_t
*F
, void *data
)
719 char buf
[sizeof(HEADER
) + MAXPACKET
]
720 /* Sparc and alpha need 16bit-alignment for accessing header->id
721 * (which is uint16_t). Because of the header = (HEADER*) buf;
722 * lateron, this is neeeded. --FaUl
724 #if defined(__sparc__) || defined(__alpha__)
725 __attribute__ ((aligned(16)))
729 struct reslist
*request
= NULL
;
730 struct DNSReply
*reply
= NULL
;
733 socklen_t len
= sizeof(struct rb_sockaddr_storage
);
734 struct rb_sockaddr_storage lsin
;
736 rc
= recvfrom(rb_get_fd(F
), buf
, sizeof(buf
), 0, (struct sockaddr
*)&lsin
, &len
);
738 /* Re-schedule a read *after* recvfrom, or we'll be registering
739 * interest where it'll instantly be ready for read :-) -- adrian
741 rb_setselect(F
, RB_SELECT_READ
, res_readreply
, NULL
);
742 /* Better to cast the sizeof instead of rc */
743 if (rc
<= (int)(sizeof(HEADER
)))
747 * convert DNS reply reader from Network byte order to CPU byte order.
749 header
= (HEADER
*) buf
;
750 header
->ancount
= ntohs(header
->ancount
);
751 header
->qdcount
= ntohs(header
->qdcount
);
752 header
->nscount
= ntohs(header
->nscount
);
753 header
->arcount
= ntohs(header
->arcount
);
756 * response for an id which we have already received an answer for
757 * just ignore this response.
759 if (0 == (request
= find_id(header
->id
)))
763 * check against possibly fake replies
765 if (!res_ourserver(&lsin
))
768 if (!check_question(request
, header
, buf
, buf
+ rc
))
771 if ((header
->rcode
!= NO_ERRORS
) || (header
->ancount
== 0))
773 if (NXDOMAIN
== header
->rcode
)
775 (*request
->query
->callback
) (request
->query
->ptr
, NULL
);
776 rem_request(request
);
781 * If a bad error was returned, we stop here and dont send
782 * send any more (no retries granted).
784 (*request
->query
->callback
) (request
->query
->ptr
, NULL
);
785 rem_request(request
);
790 * If this fails there was an error decoding the received packet,
793 answer_count
= proc_answer(request
, header
, buf
, buf
+ rc
);
797 if (request
->type
== T_PTR
)
799 if (request
->name
== NULL
)
802 * got a PTR response with no name, something bogus is happening
803 * don't bother trying again, the client address doesn't resolve
805 (*request
->query
->callback
) (request
->query
->ptr
, reply
);
806 rem_request(request
);
811 * Lookup the 'authoritative' name that we were given for the
816 if (request
->addr
.ss_family
== AF_INET6
)
817 gethost_byname_type(request
->name
, request
->query
, T_AAAA
);
820 gethost_byname_type(request
->name
, request
->query
, T_A
);
821 rem_request(request
);
826 * got a name and address response, client resolved
828 reply
= make_dnsreply(request
);
829 (*request
->query
->callback
) (request
->query
->ptr
, reply
);
831 rem_request(request
);
836 /* couldn't decode, give up -- jilles */
837 (*request
->query
->callback
) (request
->query
->ptr
, NULL
);
838 rem_request(request
);
842 static struct DNSReply
*make_dnsreply(struct reslist
*request
)
845 s_assert(request
!= 0);
847 cp
= (struct DNSReply
*)rb_malloc(sizeof(struct DNSReply
));
849 cp
->h_name
= request
->name
;
850 memcpy(&cp
->addr
, &request
->addr
, sizeof(cp
->addr
));
854 void report_dns_servers(struct Client
*source_p
)
859 for (i
= 0; i
< irc_nscount
; i
++)
861 if (!rb_inet_ntop_sock((struct sockaddr
*)&(irc_nsaddr_list
[i
]),
862 ipaddr
, sizeof ipaddr
))
863 rb_strlcpy(ipaddr
, "?", sizeof ipaddr
);
864 sendto_one_numeric(source_p
, RPL_STATSDEBUG
,