2 * src/res.c (C)opyright 1992 Darren Reed. All rights reserved.
3 * This file may not be distributed without the author's permission in any
4 * shape or form. The author takes no responsibility for any damage or loss
5 * of property which results from the use of this software.
9 * July 1999 - Rewrote a bunch of stuff here. Change hostent builder code,
10 * added callbacks and reference counting of returned hostents.
11 * --Bleep (Thomas Helvey <tomh@inxpress.net>)
16 #include "ircd_alloc.h"
18 #include "ircd_osdep.h"
19 #include "ircd_reply.h"
20 #include "ircd_string.h"
27 #include "sprintf_irc.h"
37 #include <sys/socket.h>
42 #include <arpa/nameser.h>
45 #include <arpa/inet.h>
49 #error this code needs to be able to address individual octets
53 * Some systems do not define INADDR_NONE (255.255.255.255)
54 * INADDR_NONE is actually a valid address, but it should never
55 * be returned from any nameserver.
56 * NOTE: The bit pattern for INADDR_NONE and INADDR_ANY (0.0.0.0) should be
57 * the same on all hosts so we shouldn't need to use htonl or ntohl to
58 * compare or set the values.
61 #define INADDR_NONE ((unsigned int) 0xffffffff)
64 #define MAXPACKET 1024 /* rfc sez 512 but we expand names so ... */
65 #define RES_MAXALIASES 35 /* maximum aliases allowed */
66 #define RES_MAXADDRS 35 /* maximum addresses allowed */
68 * OSF1 doesn't have RES_NOALIASES
71 #define RES_NOALIASES 0
75 * macros used to calulate offsets into fixed query buffer
77 #define ALIAS_BLEN ((RES_MAXALIASES + 1) * sizeof(char*))
78 #define ADDRS_BLEN ((RES_MAXADDRS + 1) * sizeof(struct in_addr*))
80 #define ADDRS_OFFSET (ALIAS_BLEN + ADDRS_BLEN)
81 #define ADDRS_DLEN (RES_MAXADDRS * sizeof(struct in_addr))
82 #define NAMES_OFFSET (ADDRS_OFFSET + ADDRS_DLEN)
83 #define MAXGETHOSTLEN (NAMES_OFFSET + MAXPACKET)
85 #define AR_TTL 600 /* TTL in seconds for dns cache entries */
88 * the following values should be prime
90 #define ARES_CACSIZE 307
94 * RFC 1104/1105 wasn't very helpful about what these fields
95 * should be named, so for now, we'll just name them this way.
96 * we probably should look at what named calls them or something.
101 #define RDLENGTH_SIZE 2
102 #define ANSWER_FIXED_SIZE (TYPE_SIZE + CLASS_SIZE + TTL_SIZE + RDLENGTH_SIZE)
105 * Building the Hostent
106 * The Hostent struct is arranged like this:
107 * +-------------------------------+
108 * Hostent: | struct hostent h |
109 * |-------------------------------|
111 * +-------------------------------+
115 * +-------------------------------+
116 * buf: | h_aliases pointer array | Max size: ALIAS_BLEN;
117 * | NULL | contains `char *'s
118 * |-------------------------------|
119 * | h_addr_list pointer array | Max size: ADDRS_BLEN;
120 * | NULL | contains `struct in_addr *'s
121 * |-------------------------------|
122 * | h_addr_list addresses | Max size: ADDRS_DLEN;
123 * | | contains `struct in_addr's
124 * |-------------------------------|
125 * | storage for hostname strings | Max size: ALIAS_DLEN;
126 * +-------------------------------+ contains `char's
128 * For requests the size of the h_aliases, and h_addr_list pointer
129 * array sizes are set to MAXALISES and MAXADDRS respectively, and
130 * buf is a fixed size with enough space to hold the largest expected
131 * reply from a nameserver, see RFC 1034 and RFC 1035.
132 * For cached entries the sizes are dependent on the actual number
133 * of aliases and addresses. If new aliases and addresses are found
134 * for cached entries, the buffer is grown and the new entries are added.
135 * The hostent struct is filled in with the addresses of the entries in
136 * the Hostent buf as follows:
137 * h_name - contains a pointer to the start of the hostname string area,
138 * or NULL if none is set. The h_name is followed by the
139 * aliases, in the storage for hostname strings area.
140 * h_aliases - contains a pointer to the start of h_aliases pointer array.
141 * This array contains pointers to the storage for hostname
142 * strings area and is terminated with a NULL. The first alias
143 * is stored directly after the h_name.
144 * h_addr_list - contains a pointer to the start of h_addr_list pointer array.
145 * This array contains pointers to in_addr structures in the
146 * h_addr_list addresses area and is terminated with a NULL.
148 * Filling the buffer this way allows for proper alignment of the h_addr_list
151 * This arrangement allows us to alias a Hostent struct pointer as a
152 * real struct hostent* without lying. It also allows us to change the
153 * values contained in the cached entries and requests without changing
154 * the actual hostent pointer, which is saved in a client struct and can't
155 * be changed without blowing things up or a lot more fiddling around.
156 * It also allows for defered allocation of the fixed size buffers until
157 * they are really needed.
158 * Nov. 17, 1997 --Bleep
162 struct hostent h; /* the hostent struct we are passing around */
163 char* buf; /* buffer for data pointed to from hostent */
167 struct ResRequest* next;
169 int sent; /* number of requests sent */
172 char retries; /* retry counter */
173 char sends; /* number of sends (>1 means resent) */
174 char resend; /* send flag. 0 == dont resend */
179 struct DNSQuery query; /* query callback for this request */
184 struct CacheEntry* hname_next;
185 struct CacheEntry* hnum_next;
186 struct CacheEntry* list_next;
190 struct DNSReply reply;
194 struct CacheEntry* num_list;
195 struct CacheEntry* name_list;
199 int ResolverFileDescriptor = -1; /* GLOBAL - used in s_bsd.c */
201 static time_t nextDNSCheck = 0;
202 static time_t nextCacheExpire = 1;
205 * Keep a spare file descriptor open. res_init calls fopen to read the
206 * resolv.conf file. If ircd is hogging all the file descriptors below 256,
207 * on systems with crippled FILE structures this will cause wierd bugs.
208 * This is definitely needed for Solaris which uses an unsigned char to
209 * hold the file descriptor. --Dianora
211 static int spare_fd = -1;
213 static int cachedCount = 0;
214 static struct CacheTable hashtable[ARES_CACSIZE];
215 static struct CacheEntry* cacheTop;
216 static struct ResRequest* requestListHead; /* head of resolver request list */
217 static struct ResRequest* requestListTail; /* tail of resolver request list */
220 static void add_request(struct ResRequest* request);
221 static void rem_request(struct ResRequest* request);
222 static struct ResRequest* make_request(const struct DNSQuery* query);
223 static void rem_cache(struct CacheEntry*);
224 static void do_query_name(const struct DNSQuery* query,
226 struct ResRequest* request);
227 static void do_query_number(const struct DNSQuery* query,
228 const struct in_addr*,
229 struct ResRequest* request);
230 static void query_name(const char* name,
233 struct ResRequest* request);
234 static void resend_query(struct ResRequest* request);
235 static struct CacheEntry* make_cache(struct ResRequest* request);
236 static struct CacheEntry* find_cache_name(const char* name);
237 static struct CacheEntry* find_cache_number(struct ResRequest* request,
239 static struct ResRequest* find_id(int);
241 static struct cacheinfo {
251 static struct resinfo {
265 * Disallow a hostname label to contain anything but a [-a-zA-Z0-9].
266 * It may not start or end on a '.'.
267 * A label may not end on a '-', the maximum length of a label is
269 * On top of that (which seems to be the RFC) we demand that the
270 * top domain does not contain any digits.
272 static const char* hostExpr = "([-0-9A-Za-z]*[0-9A-Za-z]\\.)+[A-Za-z]+";
273 static regex_t hostRegex;
276 * From bind 8.3, these aren't declared in earlier versions of bind
278 extern u_short _getshort(const u_char *);
279 extern u_int _getlong(const u_char *);
282 * res_isourserver(ina)
283 * looks up "ina" in _res.ns_addr_list[]
288 * paul vixie, 29may94
291 res_ourserver(const struct __res_state* statp, const struct sockaddr_in* inp)
293 struct sockaddr_in ina;
297 for (ns = 0; ns < statp->nscount; ns++) {
298 const struct sockaddr_in *srv = &statp->nsaddr_list[ns];
300 if (srv->sin_family == ina.sin_family &&
301 srv->sin_port == ina.sin_port &&
302 (srv->sin_addr.s_addr == INADDR_ANY ||
303 srv->sin_addr.s_addr == ina.sin_addr.s_addr))
310 * start_resolver - do everything we need to read the resolv.conf file
311 * and initialize the resolver file descriptor if needed
313 static void start_resolver(void)
315 Debug((DEBUG_DNS, "Resolver: start_resolver"));
317 * close the spare file descriptor so res_init can read resolv.conf
318 * successfully. Needed on Solaris
323 res_init(); /* res_init always returns 0 */
325 * make sure we have a valid file descriptor below 256 so we can
326 * do this again. Needed on Solaris
328 spare_fd = open("/dev/null",O_RDONLY,0);
329 if ((spare_fd < 0) || (spare_fd > 255)) {
331 sprintf_irc(sparemsg, "invalid spare_fd %d", spare_fd);
332 server_restart(sparemsg);
337 _res.nsaddr_list[0].sin_addr.s_addr = inet_addr("127.0.0.1");
339 _res.options |= RES_NOALIASES;
341 if (ResolverFileDescriptor < 0) {
342 ResolverFileDescriptor = socket(AF_INET, SOCK_DGRAM, 0);
343 if (-1 == ResolverFileDescriptor) {
344 report_error("Resolver: error creating socket for %s: %s",
348 if (!os_set_nonblocking(ResolverFileDescriptor))
349 report_error("Resolver: error setting non-blocking for %s: %s",
355 * init_resolver - initialize resolver and resolver library
357 int init_resolver(void)
359 Debug((DEBUG_DNS, "Resolver: init_resolver"));
361 srand48(CurrentTime);
363 memset(&cainfo, 0, sizeof(cainfo));
364 memset(hashtable, 0, sizeof(hashtable));
365 memset(&reinfo, 0, sizeof(reinfo));
367 requestListHead = requestListTail = 0;
371 if (regcomp(&hostRegex, hostExpr, REG_EXTENDED | REG_NOSUB)) {
372 ircd_log(L_CRIT, "Resolver: error compiling host expression %s", hostExpr);
376 Debug((DEBUG_DNS, "Resolver: fd %d errno: %d h_errno: %d: %s",
377 ResolverFileDescriptor, errno, h_errno,
378 (strerror(errno)) ? strerror(errno) : "Unknown"));
379 return ResolverFileDescriptor;
383 * restart_resolver - flush the cache, reread resolv.conf, reopen socket
385 void restart_resolver(void)
387 /* flush_cache(); flush the dns cache */
391 static int validate_hostent(const struct hostent* hp)
396 for (name = hp->h_name; name; name = hp->h_aliases[i++]) {
397 if (HOSTLEN < strlen(name) || 0 != regexec(&hostRegex, name, 0, 0, 0))
404 * add_request - place a new request in the request list
406 static void add_request(struct ResRequest* request)
408 assert(0 != request);
409 if (!requestListHead)
410 requestListHead = requestListTail = request;
412 requestListTail->next = request;
413 requestListTail = request;
415 request->next = NULL;
416 ++reinfo.re_requests;
420 * rem_request - remove a request from the list.
421 * This must also free any memory that has been allocated for
422 * temporary storage of DNS results.
424 static void rem_request(struct ResRequest* request)
426 struct ResRequest** current;
427 struct ResRequest* prev = NULL;
429 assert(0 != request);
430 for (current = &requestListHead; *current; ) {
431 if (*current == request) {
432 *current = request->next;
433 if (requestListTail == request)
434 requestListTail = prev;
438 current = &(*current)->next;
440 MyFree(request->he.buf);
441 MyFree(request->name);
446 * make_request - Create a DNS request record for the server.
448 static struct ResRequest* make_request(const struct DNSQuery* query)
450 struct ResRequest* request;
452 request = (struct ResRequest*) MyMalloc(sizeof(struct ResRequest));
453 memset(request, 0, sizeof(struct ResRequest));
455 request->sentat = CurrentTime;
456 request->retries = 3;
458 request->timeout = 5; /* start at 5 per RFC1123 */
459 request->addr.s_addr = INADDR_NONE;
460 request->he.h.h_addrtype = AF_INET;
461 request->he.h.h_length = sizeof(struct in_addr);
462 request->query.vptr = query->vptr;
463 request->query.callback = query->callback;
465 #if defined(NULL_POINTER_NOT_ZERO)
466 request->next = NULL;
467 request->he.buf = NULL;
468 request->he.h.h_name = NULL;
469 request->he.h.h_aliases = NULL;
470 request->he.h.h_addr_list = NULL;
472 add_request(request);
477 * timeout_query_list - Remove queries from the list which have been
478 * there too long without being resolved.
480 static time_t timeout_query_list(time_t now)
482 struct ResRequest* request;
483 struct ResRequest* next_request = 0;
484 time_t next_time = 0;
487 Debug((DEBUG_DNS, "Resolver: timeout_query_list at %s", myctime(now)));
488 for (request = requestListHead; request; request = next_request) {
489 next_request = request->next;
490 timeout = request->sentat + request->timeout;
492 if (--request->retries <= 0) {
493 ++reinfo.re_timeouts;
494 (*request->query.callback)(request->query.vptr, 0);
495 rem_request(request);
499 request->sentat = now;
500 request->timeout += request->timeout;
501 resend_query(request);
504 if (!next_time || timeout < next_time) {
508 return (next_time > now) ? next_time : (now + AR_TTL);
512 * expire_cache - removes entries from the cache which are older
513 * than their expiry times. returns the time at which the server
514 * should next poll the cache.
516 static time_t expire_cache(time_t now)
518 struct CacheEntry* cp;
519 struct CacheEntry* cp_next;
522 Debug((DEBUG_DNS, "Resolver: expire_cache at %s", myctime(now)));
523 for (cp = cacheTop; cp; cp = cp_next) {
524 cp_next = cp->list_next;
525 if (cp->expireat < now) {
529 else if (!expire || expire > cp->expireat)
530 expire = cp->expireat;
532 return (expire > now) ? expire : (now + AR_TTL);
536 * timeout_resolver - check request list and cache for expired entries
538 time_t timeout_resolver(time_t now)
540 if (nextDNSCheck < now)
541 nextDNSCheck = timeout_query_list(now);
542 if (nextCacheExpire < now)
543 nextCacheExpire = expire_cache(now);
544 return IRCD_MIN(nextDNSCheck, nextCacheExpire);
549 * delete_resolver_queries - cleanup outstanding queries
550 * for which there no longer exist clients or conf lines.
552 void delete_resolver_queries(const void* vptr)
554 struct ResRequest* request;
555 struct ResRequest* next_request;
557 for (request = requestListHead; request; request = next_request) {
558 next_request = request->next;
559 if (vptr == request->query.vptr)
560 rem_request(request);
565 * send_res_msg - sends msg to all nameservers found in the "_res" structure.
566 * This should reflect /etc/resolv.conf. We will get responses
567 * which arent needed but is easier than checking to see if nameserver
568 * isnt present. Returns number of messages successfully sent to
569 * nameservers or -1 if no successful sends.
571 static int send_res_msg(const u_char* msg, int len, int rcount)
575 int max_queries = IRCD_MIN(_res.nscount, rcount);
579 * RES_PRIMARY option is not implemented
580 * if (_res.options & RES_PRIMARY || 0 == max_queries)
582 if (0 == max_queries)
585 Debug((DEBUG_DNS, "Resolver: sendto %d", max_queries));
587 for (i = 0; i < max_queries; i++) {
588 if (sendto(ResolverFileDescriptor, msg, len, 0,
589 (struct sockaddr*) &(_res.nsaddr_list[i]),
590 sizeof(struct sockaddr_in)) == len) {
595 ircd_log(L_ERROR, "Resolver: send failed %s",
596 (strerror(errno)) ? strerror(errno) : "Unknown");
602 * find_id - find a dns request id (id is determined by dn_mkquery)
604 static struct ResRequest* find_id(int id)
606 struct ResRequest* request;
608 for (request = requestListHead; request; request = request->next) {
609 if (request->id == id)
616 * gethost_byname - get host address from name
618 struct DNSReply* gethost_byname(const char* name,
619 const struct DNSQuery* query)
621 struct CacheEntry* cp;
624 Debug((DEBUG_DNS, "Resolver: gethost_byname %s", name));
626 if ((cp = find_cache_name(name)))
629 do_query_name(query, name, NULL);
635 * gethost_byaddr - get host name from address
637 struct DNSReply* gethost_byaddr(const char* addr,
638 const struct DNSQuery* query)
640 struct CacheEntry *cp;
644 Debug((DEBUG_DNS, "Resolver: gethost_byaddr %s", ircd_ntoa(addr)));
647 if ((cp = find_cache_number(NULL, addr)))
650 do_query_number(query, (const struct in_addr*) addr, NULL);
656 * do_query_name - nameserver lookup name
658 static void do_query_name(const struct DNSQuery* query,
659 const char* name, struct ResRequest* request)
661 char hname[HOSTLEN + 1];
664 ircd_strncpy(hname, name, HOSTLEN);
665 hname[HOSTLEN] = '\0';
668 request = make_request(query);
670 request->name = (char*) MyMalloc(strlen(hname) + 1);
671 strcpy(request->name, hname);
673 query_name(hname, C_IN, T_A, request);
677 * do_query_number - Use this to do reverse IP# lookups.
679 static void do_query_number(const struct DNSQuery* query,
680 const struct in_addr* addr,
681 struct ResRequest* request)
684 const unsigned char* cp;
687 cp = (const unsigned char*) &addr->s_addr;
688 sprintf_irc(ipbuf, "%u.%u.%u.%u.in-addr.arpa.",
689 (unsigned int)(cp[3]), (unsigned int)(cp[2]),
690 (unsigned int)(cp[1]), (unsigned int)(cp[0]));
693 request = make_request(query);
694 request->type = T_PTR;
695 request->addr.s_addr = addr->s_addr;
697 query_name(ipbuf, C_IN, T_PTR, request);
701 * query_name - generate a query based on class, type and name.
703 static void query_name(const char* name, int query_class,
704 int type, struct ResRequest* request)
710 assert(0 != request);
712 Debug((DEBUG_DNS, "Resolver: query_name: %s %d %d", name, query_class, type));
713 memset(buf, 0, sizeof(buf));
714 if ((request_len = res_mkquery(QUERY, name, query_class, type,
715 0, 0, 0, (unsigned char*) buf, sizeof(buf))) > 0) {
716 HEADER* header = (HEADER*) buf;
722 * generate a unique id
723 * NOTE: we don't have to worry about converting this to and from
724 * network byte order, the nameserver does not interpret this value
725 * and returns it unchanged
729 header->id = (header->id + lrand48()) & 0xffff;
730 } while (find_id(header->id));
732 gettimeofday(&tv, NULL);
734 header->id = (header->id + k + tv.tv_usec) & 0xffff;
736 } while (find_id(header->id));
738 request->id = header->id;
740 Debug((DEBUG_DNS, "Resolver: query_name %d: %s %d %d", request->id,
741 name, query_class, type));
742 request->sent += send_res_msg((const unsigned char*) buf, request_len, request->sends);
746 static void resend_query(struct ResRequest* request)
748 assert(0 != request);
750 if (request->resend == 0)
753 switch(request->type) {
755 do_query_number(NULL, &request->addr, request);
758 do_query_name(NULL, request->name, request);
766 * proc_answer - process name server reply
767 * build a hostent struct in the passed request
769 static int proc_answer(struct ResRequest* request, HEADER* header,
770 u_char* buf, u_char* eob)
772 char hostbuf[HOSTLEN + 1]; /* working buffer */
773 u_char* current; /* current position in buf */
774 char** alias; /* alias list */
775 char** addr; /* address list */
776 char* name; /* pointer to name string */
777 char* address; /* pointer to address */
778 char* endp; /* end of our buffer */
779 int query_class; /* answer class */
780 int type; /* answer type */
781 int rd_length; /* record data length */
782 int answer_count = 0; /* answer counter */
783 int n; /* temp count */
784 int addr_count = 0; /* number of addresses in hostent */
785 int alias_count = 0; /* number of aliases in hostent */
786 struct hostent* hp; /* hostent getting filled */
788 assert(0 != request);
793 current = buf + sizeof(HEADER);
794 hp = &(request->he.h);
796 * lazy allocation of request->he.buf, we don't allocate a buffer
797 * unless there is something to put in it.
799 if (!request->he.buf) {
800 request->he.buf = (char*) MyMalloc(MAXGETHOSTLEN + 1);
801 request->he.buf[MAXGETHOSTLEN] = '\0';
803 * array of alias list pointers starts at beginning of buf
805 hp->h_aliases = (char**) request->he.buf;
806 hp->h_aliases[0] = NULL;
808 * array of address list pointers starts after alias list pointers
809 * the actual addresses follow the the address list pointers
811 hp->h_addr_list = (char**)(request->he.buf + ALIAS_BLEN);
813 * don't copy the host address to the beginning of h_addr_list
815 hp->h_addr_list[0] = NULL;
817 endp = request->he.buf + MAXGETHOSTLEN;
819 * find the end of the address list
821 addr = hp->h_addr_list;
827 * make address point to first available address slot
829 address = request->he.buf + ADDRS_OFFSET +
830 (sizeof(struct in_addr) * addr_count);
832 * find the end of the alias list
834 alias = hp->h_aliases;
840 * make name point to first available space in request->buf
842 if (alias_count > 0) {
843 name = hp->h_aliases[alias_count - 1];
844 name += (strlen(name) + 1);
847 name = hp->h_name + strlen(hp->h_name) + 1;
849 name = request->he.buf + ADDRS_OFFSET + ADDRS_DLEN;
854 while (header->qdcount-- > 0) {
855 if ((n = dn_skipname(current, eob)) < 0)
857 current += (n + QFIXEDSZ);
860 * process each answer sent to us blech.
862 while (header->ancount-- > 0 && current < eob && name < endp) {
863 n = dn_expand(buf, eob, current, hostbuf, sizeof(hostbuf));
866 * no more answers left
870 hostbuf[HOSTLEN] = '\0';
872 * With Address arithmetic you have to be very anal
873 * this code was not working on alpha due to that
874 * (spotted by rodder/jailbird/dianora)
876 current += (size_t) n;
878 if (!((current + ANSWER_FIXED_SIZE) < eob))
881 type = _getshort(current);
882 current += TYPE_SIZE;
884 query_class = _getshort(current);
885 current += CLASS_SIZE;
887 request->ttl = _getlong(current);
890 rd_length = _getshort(current);
891 current += RDLENGTH_SIZE;
894 * Wait to set request->type until we verify this structure
899 * check for invalid rd_length or too many addresses
901 if (rd_length != sizeof(struct in_addr))
903 if (++addr_count < RES_MAXADDRS) {
904 if (answer_count == 1)
905 hp->h_addrtype = (query_class == C_IN) ? AF_INET : AF_UNSPEC;
907 memcpy(address, current, sizeof(struct in_addr));
910 address += sizeof(struct in_addr);
913 strcpy(name, hostbuf);
915 name += strlen(name) + 1;
917 Debug((DEBUG_DNS, "Resolver: A %s for %s",
918 ircd_ntoa((char*) hp->h_addr_list[addr_count - 1]), hostbuf));
920 current += rd_length;
924 n = dn_expand(buf, eob, current, hostbuf, sizeof(hostbuf));
933 * no more answers left
938 * This comment is based on analysis by Shadowfax, Wohali and johan,
939 * not me. (Dianora) I am only commenting it.
941 * dn_expand is guaranteed to not return more than sizeof(hostbuf)
942 * but do all implementations of dn_expand also guarantee
943 * buffer is terminated with null byte? Lets not take chances.
946 hostbuf[HOSTLEN] = '\0';
947 current += (size_t) n;
949 Debug((DEBUG_DNS, "Resolver: PTR %s", hostbuf));
951 * copy the returned hostname into the host name
952 * ignore duplicate ptr records
955 strcpy(name, hostbuf);
957 name += strlen(name) + 1;
962 Debug((DEBUG_DNS, "Resolver: CNAME %s", hostbuf));
963 if (++alias_count < RES_MAXALIASES) {
964 ircd_strncpy(name, hostbuf, endp - name);
967 name += strlen(name) + 1;
969 current += rd_length;
973 Debug((DEBUG_DNS,"Resolver: proc_answer type: %d for: %s", type, hostbuf));
981 * resolver_read - read a dns reply from the nameserver and process it.
982 * return 0 if nothing was read from the socket, otherwise return 1
984 int resolver_read(void)
986 u_char buf[sizeof(HEADER) + MAXPACKET];
988 struct ResRequest* request = 0;
989 struct CacheEntry* cp = 0;
991 int answer_count = 0;
992 struct sockaddr_in sin;
994 Debug((DEBUG_DNS, "Resolver: read"));
995 if (IO_SUCCESS != os_recvfrom_nonb(ResolverFileDescriptor,
996 (char*) buf, sizeof(buf), &rc, &sin)) {
999 if (rc < sizeof(HEADER)) {
1000 Debug((DEBUG_DNS, "Resolver: short reply %d: %s", rc,
1001 (strerror(errno)) ? strerror(errno) : "Unknown"));
1005 * convert DNS reply reader from Network byte order to CPU byte order.
1007 header = (HEADER*) buf;
1008 /* header->id = ntohs(header->id); */
1009 header->ancount = ntohs(header->ancount);
1010 header->qdcount = ntohs(header->qdcount);
1011 header->nscount = ntohs(header->nscount);
1012 header->arcount = ntohs(header->arcount);
1013 ++reinfo.re_replies;
1015 * response for an id which we have already received an answer for
1016 * just ignore this response.
1018 if (0 == (request = find_id(header->id))) {
1019 Debug((DEBUG_DNS, "Resolver: can't find request id: %d", header->id));
1023 * check against possibly fake replies
1025 if (!res_ourserver(&_res, &sin)) {
1026 Debug((DEBUG_DNS, "Resolver: fake reply from: %s", (const char*) &sin.sin_addr));
1031 if ((header->rcode != NOERROR) || (header->ancount == 0)) {
1033 if (SERVFAIL == header->rcode)
1034 resend_query(request);
1037 * If a bad error was returned, we stop here and dont send
1038 * send any more (no retries granted).
1039 * Isomer: Perhaps we should return these error messages back to
1043 switch (header->rcode) {
1045 Debug((DEBUG_DNS, "Fatal DNS error: No Error"));
1048 Debug((DEBUG_DNS, "Fatal DNS error: Format Error"));
1051 Debug((DEBUG_DNS, "Fatal DNS error: Server Failure"));
1054 Debug((DEBUG_DNS, "DNS error: Non Existant Domain"));
1057 Debug((DEBUG_DNS, "Fatal DNS error: Not Implemented"));
1060 Debug((DEBUG_DNS, "Fatal DNS error: Query Refused"));
1063 Debug((DEBUG_DNS, "Unassigned fatal DNS error: %i", header->rcode));
1066 #endif /* DEBUGMODE */
1067 (*request->query.callback)(request->query.vptr, 0);
1068 rem_request(request);
1073 * If this fails there was an error decoding the received packet,
1074 * try it again and hope it works the next time.
1076 answer_count = proc_answer(request, header, buf, buf + rc);
1078 if (T_PTR == request->type) {
1079 struct DNSReply* reply = 0;
1080 if (0 == request->he.h.h_name) {
1082 * got a PTR response with no name, something bogus is happening
1083 * don't bother trying again, the client address doesn't resolve
1085 (*request->query.callback)(request->query.vptr, reply);
1086 rem_request(request);
1089 Debug((DEBUG_DNS, "relookup %s <-> %s",
1090 request->he.h.h_name, ircd_ntoa((char*) &request->addr)));
1092 * Lookup the 'authoritive' name that we were given for the
1093 * ip#. By using this call rather than regenerating the
1094 * type we automatically gain the use of the cache with no
1097 reply = gethost_byname(request->he.h.h_name, &request->query);
1099 (*request->query.callback)(request->query.vptr, reply);
1103 * If name wasn't found, a request has been queued and it will
1104 * be the last one queued. This is rather nasty way to keep
1105 * a host alias with the query. -avalon
1107 MyFree(requestListTail->he.buf);
1108 requestListTail->he.buf = request->he.buf;
1109 request->he.buf = 0;
1110 memcpy(&requestListTail->he.h, &request->he.h, sizeof(struct hostent));
1112 rem_request(request);
1116 * got a name and address response, client resolved
1117 * XXX - Bug found here by Dianora -
1118 * make_cache() occasionally returns a NULL pointer when a
1119 * PTR returned a CNAME, cp was not checked before so the
1120 * callback was being called with a value of 0x2C != NULL.
1122 struct DNSReply* reply = 0;
1123 if (validate_hostent(&request->he.h)) {
1124 if ((cp = make_cache(request)))
1127 (*request->query.callback)(request->query.vptr, reply);
1128 rem_request(request);
1131 else if (!request->sent) {
1133 * XXX - we got a response for a query we didn't send with a valid id?
1134 * this should never happen, bail here and leave the client unresolved
1136 (*request->query.callback)(request->query.vptr, 0);
1137 rem_request(request);
1143 * resolver_read_multiple - process up to count reads
1145 void resolver_read_multiple(int count)
1148 for ( ; i < count; ++i) {
1149 if (0 == resolver_read())
1154 static size_t calc_hostent_buffer_size(const struct hostent* hp)
1163 count += (strlen(hp->h_name) + 1);
1167 for (p = hp->h_aliases; *p; ++p)
1168 count += (strlen(*p) + 1 + sizeof(char*));
1170 * space for addresses
1172 for (p = hp->h_addr_list; *p; ++p)
1173 count += (hp->h_length + sizeof(char*));
1175 * space for 2 nulls to terminate h_aliases and h_addr_list
1177 count += (2 * sizeof(char*));
1183 * dup_hostent - Duplicate a hostent struct, allocate only enough memory for
1184 * the data we're putting in it.
1186 static void dup_hostent(struct Hostent* new_hp, struct hostent* hp)
1191 int alias_count = 0;
1193 size_t bytes_needed = 0;
1195 assert(0 != new_hp);
1198 /* how much buffer do we need? */
1199 bytes_needed += (strlen(hp->h_name) + 1);
1203 bytes_needed += (strlen(*pp++) + 1 + sizeof(char*));
1206 pp = hp->h_addr_list;
1208 bytes_needed += (hp->h_length + sizeof(char*));
1211 /* Reserve space for 2 nulls to terminate h_aliases and h_addr_list */
1212 bytes_needed += (2 * sizeof(char*));
1214 /* Allocate memory */
1215 new_hp->buf = (char*) MyMalloc(bytes_needed);
1217 new_hp->h.h_addrtype = hp->h_addrtype;
1218 new_hp->h.h_length = hp->h_length;
1220 /* first write the address list */
1221 pp = hp->h_addr_list;
1222 ap = new_hp->h.h_addr_list =
1223 (char**)(new_hp->buf + ((alias_count + 1) * sizeof(char*)));
1224 p = (char*)ap + ((addr_count + 1) * sizeof(char*));
1228 memcpy(p, *pp++, hp->h_length);
1232 /* next write the name */
1233 new_hp->h.h_name = p;
1234 strcpy(p, hp->h_name);
1235 p += (strlen(p) + 1);
1237 /* last write the alias list */
1239 ap = new_hp->h.h_aliases = (char**) new_hp->buf;
1243 p += (strlen(p) + 1);
1249 * update_hostent - Add records to a Hostent struct in place.
1251 static void update_hostent(struct Hostent* hp, char** addr, char** alias)
1256 int alias_count = 0;
1259 size_t bytes_needed = 0;
1261 if (!hp || !hp->buf)
1264 /* how much buffer do we need? */
1265 bytes_needed = strlen(hp->h.h_name) + 1;
1266 pp = hp->h.h_aliases;
1268 bytes_needed += (strlen(*pp++) + 1 + sizeof(char*));
1274 bytes_needed += (strlen(*pp++) + 1 + sizeof(char*));
1278 pp = hp->h.h_addr_list;
1280 bytes_needed += (hp->h.h_length + sizeof(char*));
1286 bytes_needed += (hp->h.h_length + sizeof(char*));
1290 /* Reserve space for 2 nulls to terminate h_aliases and h_addr_list */
1291 bytes_needed += 2 * sizeof(char*);
1293 /* Allocate memory */
1294 buf = (char*) MyMalloc(bytes_needed);
1297 /* first write the address list */
1298 pp = hp->h.h_addr_list;
1299 ap = hp->h.h_addr_list =
1300 (char**)(buf + ((alias_count + 1) * sizeof(char*)));
1301 p = (char*)ap + ((addr_count + 1) * sizeof(char*));
1303 memcpy(p, *pp++, hp->h.h_length);
1305 p += hp->h.h_length;
1309 memcpy(p, *addr++, hp->h.h_length);
1311 p += hp->h.h_length;
1316 /* next write the name */
1317 strcpy(p, hp->h.h_name);
1319 p += (strlen(p) + 1);
1321 /* last write the alias list */
1322 pp = hp->h.h_aliases;
1323 ap = hp->h.h_aliases = (char**) buf;
1327 p += (strlen(p) + 1);
1331 strcpy(p, *alias++);
1333 p += (strlen(p) + 1);
1337 /* release the old buffer */
1344 * hash_number - IP address hash function
1346 static int hash_number(const unsigned char* ip)
1348 /* could use loop but slower */
1350 const u_char* p = (const u_char*) ip;
1355 hashv += hashv + *p++;
1356 hashv += hashv + *p++;
1357 hashv += hashv + *p;
1358 hashv %= ARES_CACSIZE;
1363 * hash_name - hostname hash function
1365 static int hash_name(const char* name)
1367 unsigned int hashv = 0;
1368 const u_char* p = (const u_char*) name;
1372 for (; *p && *p != '.'; ++p)
1374 hashv %= ARES_CACSIZE;
1379 * add_to_cache - Add a new cache item to the queue and hash table.
1381 static struct CacheEntry* add_to_cache(struct CacheEntry* ocp)
1387 ocp->list_next = cacheTop;
1390 hashv = hash_name(ocp->he.h.h_name);
1392 ocp->hname_next = hashtable[hashv].name_list;
1393 hashtable[hashv].name_list = ocp;
1395 hashv = hash_number((const unsigned char*) ocp->he.h.h_addr);
1397 ocp->hnum_next = hashtable[hashv].num_list;
1398 hashtable[hashv].num_list = ocp;
1401 * LRU deletion of excessive cache entries.
1403 if (++cachedCount > MAXCACHED) {
1404 struct CacheEntry* cp;
1405 struct CacheEntry* cp_next;
1406 for (cp = ocp->list_next; cp; cp = cp_next) {
1407 cp_next = cp->list_next;
1416 * update_list - does not alter the cache structure passed. It is assumed that
1417 * it already contains the correct expire time, if it is a new entry. Old
1418 * entries have the expirey time updated.
1420 static void update_list(struct ResRequest* request, struct CacheEntry* cachep)
1423 struct CacheEntry** cpp;
1425 struct CacheEntry* cp = cachep;
1431 char* addrs[RES_MAXADDRS + 1];
1432 char* aliases[RES_MAXALIASES + 1];
1435 * search for the new cache item in the cache list by hostname.
1436 * If found, move the entry to the top of the list and return.
1438 ++cainfo.ca_updates;
1440 for (cpp = &cacheTop; *cpp; cpp = &((*cpp)->list_next)) {
1446 *cpp = cp->list_next;
1447 cp->list_next = cacheTop;
1454 * Compare the cache entry against the new record. Add any
1455 * previously missing names for this entry.
1459 for (i = 0, s = request->he.h.h_name; s; s = request->he.h.h_aliases[i++]) {
1460 for (j = 0, t = cp->he.h.h_name; t; t = cp->he.h.h_aliases[j++]) {
1461 if (0 == ircd_strcmp(t, s))
1470 * Do the same again for IP#'s.
1474 for (i = 0; (s = request->he.h.h_addr_list[i]); i++) {
1475 for (j = 0; (t = cp->he.h.h_addr_list[j]); j++) {
1476 if (!memcmp(t, s, sizeof(struct in_addr)))
1484 if (*addrs || *aliases)
1485 update_hostent(&cp->he, addrs, aliases);
1489 * find_cache_name - find name in nameserver cache
1491 static struct CacheEntry* find_cache_name(const char* name)
1493 struct CacheEntry* cp;
1499 hashv = hash_name(name);
1501 cp = hashtable[hashv].name_list;
1503 for (; cp; cp = cp->hname_next) {
1504 for (i = 0, s = cp->he.h.h_name; s; s = cp->he.h.h_aliases[i++]) {
1505 if (0 == ircd_strcmp(s, name)) {
1506 ++cainfo.ca_na_hits;
1512 for (cp = cacheTop; cp; cp = cp->list_next) {
1514 * if no aliases or the hash value matches, we've already
1515 * done this entry and all possiblilities concerning it.
1517 if (!cp->he.h.h_name || hashv == hash_name(cp->he.h.h_name))
1519 for (i = 0, s = cp->he.h.h_aliases[i]; s; s = cp->he.h.h_aliases[++i]) {
1520 if (0 == ircd_strcmp(name, s)) {
1521 ++cainfo.ca_na_hits;
1530 * find_cache_number - find a cache entry by ip# and update its expire time
1532 static struct CacheEntry* find_cache_number(struct ResRequest* request,
1535 struct CacheEntry* cp;
1540 hashv = hash_number((const unsigned char*) addr);
1541 cp = hashtable[hashv].num_list;
1543 for (; cp; cp = cp->hnum_next) {
1544 for (i = 0; cp->he.h.h_addr_list[i]; ++i) {
1545 if (!memcmp(cp->he.h.h_addr_list[i], addr, sizeof(struct in_addr))) {
1546 ++cainfo.ca_nu_hits;
1551 for (cp = cacheTop; cp; cp = cp->list_next) {
1553 * single address entry...would have been done by hashed
1555 * if the first IP# has the same hashnumber as the IP# we
1556 * are looking for, its been done already.
1558 if (!cp->he.h.h_addr_list[1] ||
1559 hashv == hash_number((const unsigned char*) cp->he.h.h_addr_list[0]))
1561 for (i = 1; cp->he.h.h_addr_list[i]; ++i) {
1562 if (!memcmp(cp->he.h.h_addr_list[i], addr, sizeof(struct in_addr))) {
1563 ++cainfo.ca_nu_hits;
1571 static struct CacheEntry* make_cache(struct ResRequest* request)
1573 struct CacheEntry* cp;
1576 assert(0 != request);
1578 hp = &request->he.h;
1580 * shouldn't happen but it just might...
1582 assert(0 != hp->h_name);
1583 assert(0 != hp->h_addr_list[0]);
1584 if (!hp->h_name || !hp->h_addr_list[0])
1587 * Make cache entry. First check to see if the cache already exists
1588 * and if so, return a pointer to it.
1590 for (i = 0; hp->h_addr_list[i]; ++i) {
1591 if ((cp = find_cache_number(request, hp->h_addr_list[i]))) {
1592 update_list(request, cp);
1597 * a matching entry wasnt found in the cache so go and make one up.
1599 cp = (struct CacheEntry*) MyMalloc(sizeof(struct CacheEntry));
1602 memset(cp, 0, sizeof(struct CacheEntry));
1603 dup_hostent(&cp->he, hp);
1604 cp->reply.hp = &cp->he.h;
1606 * hmmm... we could time out the cache after 10 minutes regardless
1607 * would that be reasonable since we don't save the reply?
1609 if (request->ttl < AR_TTL) {
1610 ++reinfo.re_shortttl;
1614 cp->ttl = request->ttl;
1615 cp->expireat = CurrentTime + cp->ttl;
1616 return add_to_cache(cp);
1620 * rem_cache - delete a cache entry from the cache structures
1621 * and lists and return all memory used for the cache back to the memory pool.
1623 static void rem_cache(struct CacheEntry* ocp)
1625 struct CacheEntry** cp;
1631 if (0 < ocp->reply.ref_count) {
1632 if (ocp->expireat < CurrentTime) {
1633 ocp->expireat = CurrentTime + AR_TTL;
1634 Debug((DEBUG_DNS, "Resolver: referenced cache entry not removed for: %s",
1640 * remove cache entry from linked list
1642 for (cp = &cacheTop; *cp; cp = &((*cp)->list_next)) {
1644 *cp = ocp->list_next;
1650 * remove cache entry from hashed name list
1652 assert(0 != hp->h_name);
1653 hashv = hash_name(hp->h_name);
1655 for (cp = &hashtable[hashv].name_list; *cp; cp = &((*cp)->hname_next)) {
1657 *cp = ocp->hname_next;
1662 * remove cache entry from hashed number list
1664 hashv = hash_number((const unsigned char*) hp->h_addr);
1667 for (cp = &hashtable[hashv].num_list; *cp; cp = &((*cp)->hnum_next)) {
1669 *cp = ocp->hnum_next;
1674 * free memory used to hold the various host names and the array
1675 * of alias pointers.
1677 MyFree(ocp->he.buf);
1683 void flush_resolver_cache(void)
1686 * stubbed - iterate cache and remove everything that isn't referenced
1691 * m_dns - dns status query
1693 int m_dns(struct Client *cptr, struct Client *sptr, int parc, char *parv[])
1695 #if !defined(NDEBUG)
1696 struct CacheEntry* cp;
1700 if (parv[1] && *parv[1] == 'l') {
1701 for(cp = cacheTop; cp; cp = cp->list_next) {
1703 sendcmdto_one(&me, CMD_NOTICE, sptr, "%C :Ex %d ttl %d host %s(%s)",
1704 sptr, cp->expireat - CurrentTime, cp->ttl,
1705 hp->h_name, ircd_ntoa(hp->h_addr));
1706 for (i = 0; hp->h_aliases[i]; i++)
1707 sendcmdto_one(&me, CMD_NOTICE, sptr, "%C : %s = %s (CN)", sptr,
1708 hp->h_name, hp->h_aliases[i]);
1709 for (i = 1; hp->h_addr_list[i]; i++)
1710 sendcmdto_one(&me, CMD_NOTICE, sptr, "%C : %s = %s (IP)", sptr,
1711 hp->h_name, ircd_ntoa(hp->h_addr_list[i]));
1715 if (parv[1] && *parv[1] == 'd') {
1716 sendcmdto_one(&me, CMD_NOTICE, sptr, "%C :ResolverFileDescriptor = %d",
1717 sptr, ResolverFileDescriptor);
1720 sendcmdto_one(&me, CMD_NOTICE, sptr,"%C :Ca %d Cd %d Ce %d Cl %d Ch %d:%d "
1722 cainfo.ca_adds, cainfo.ca_dels, cainfo.ca_expires,
1723 cainfo.ca_lookups, cainfo.ca_na_hits, cainfo.ca_nu_hits,
1726 sendcmdto_one(&me, CMD_NOTICE, sptr,"%C :Re %d Rl %d/%d Rp %d Rq %d",
1727 sptr, reinfo.re_errors, reinfo.re_nu_look,
1728 reinfo.re_na_look, reinfo.re_replies, reinfo.re_requests);
1729 sendcmdto_one(&me, CMD_NOTICE, sptr,"%C :Ru %d Rsh %d Rs %d(%d) Rt %d", sptr,
1730 reinfo.re_unkrep, reinfo.re_shortttl, reinfo.re_sent,
1731 reinfo.re_resends, reinfo.re_timeouts);
1736 size_t cres_mem(struct Client* sptr)
1738 struct CacheEntry* entry;
1739 struct ResRequest* request;
1740 size_t cache_mem = 0;
1741 size_t request_mem = 0;
1742 int cache_count = 0;
1743 int request_count = 0;
1745 for (entry = cacheTop; entry; entry = entry->list_next) {
1746 cache_mem += sizeof(struct CacheEntry);
1747 cache_mem += calc_hostent_buffer_size(&entry->he.h);
1750 for (request = requestListHead; request; request = request->next) {
1751 request_mem += sizeof(struct ResRequest);
1753 request_mem += strlen(request->name) + 1;
1754 if (request->he.buf)
1755 request_mem += MAXGETHOSTLEN + 1;
1759 if (cachedCount != cache_count) {
1760 send_reply(sptr, SND_EXPLICIT | RPL_STATSDEBUG,
1761 ":Resolver: cache count mismatch: %d != %d", cachedCount,
1763 assert(cachedCount == cache_count);
1765 send_reply(sptr, SND_EXPLICIT | RPL_STATSDEBUG,
1766 ":Resolver: cache %d(%d) requests %d(%d)", cache_count,
1767 cache_mem, request_count, request_mem);
1768 return cache_mem + request_mem;