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>
41 #include <arpa/nameser.h>
44 #include <arpa/inet.h>
48 #error this code needs to be able to address individual octets
52 * Some systems do not define INADDR_NONE (255.255.255.255)
53 * INADDR_NONE is actually a valid address, but it should never
54 * be returned from any nameserver.
55 * NOTE: The bit pattern for INADDR_NONE and INADDR_ANY (0.0.0.0) should be
56 * the same on all hosts so we shouldn't need to use htonl or ntohl to
57 * compare or set the values.
60 #define INADDR_NONE ((unsigned int) 0xffffffff)
63 #define MAXPACKET 1024 /* rfc sez 512 but we expand names so ... */
64 #define RES_MAXALIASES 35 /* maximum aliases allowed */
65 #define RES_MAXADDRS 35 /* maximum addresses allowed */
67 * OSF1 doesn't have RES_NOALIASES
70 #define RES_NOALIASES 0
74 * macros used to calulate offsets into fixed query buffer
76 #define ALIAS_BLEN ((RES_MAXALIASES + 1) * sizeof(char*))
77 #define ADDRS_BLEN ((RES_MAXADDRS + 1) * sizeof(struct in_addr*))
79 #define ADDRS_OFFSET (ALIAS_BLEN + ADDRS_BLEN)
80 #define ADDRS_DLEN (RES_MAXADDRS * sizeof(struct in_addr))
81 #define NAMES_OFFSET (ADDRS_OFFSET + ADDRS_DLEN)
82 #define MAXGETHOSTLEN (NAMES_OFFSET + MAXPACKET)
84 #define AR_TTL 600 /* TTL in seconds for dns cache entries */
87 * the following values should be prime
89 #define ARES_CACSIZE 307
93 * RFC 1104/1105 wasn't very helpful about what these fields
94 * should be named, so for now, we'll just name them this way.
95 * we probably should look at what named calls them or something.
100 #define RDLENGTH_SIZE 2
101 #define ANSWER_FIXED_SIZE (TYPE_SIZE + CLASS_SIZE + TTL_SIZE + RDLENGTH_SIZE)
104 * Building the Hostent
105 * The Hostent struct is arranged like this:
106 * +-------------------------------+
107 * Hostent: | struct hostent h |
108 * |-------------------------------|
110 * +-------------------------------+
114 * +-------------------------------+
115 * buf: | h_aliases pointer array | Max size: ALIAS_BLEN;
116 * | NULL | contains `char *'s
117 * |-------------------------------|
118 * | h_addr_list pointer array | Max size: ADDRS_BLEN;
119 * | NULL | contains `struct in_addr *'s
120 * |-------------------------------|
121 * | h_addr_list addresses | Max size: ADDRS_DLEN;
122 * | | contains `struct in_addr's
123 * |-------------------------------|
124 * | storage for hostname strings | Max size: ALIAS_DLEN;
125 * +-------------------------------+ contains `char's
127 * For requests the size of the h_aliases, and h_addr_list pointer
128 * array sizes are set to MAXALISES and MAXADDRS respectively, and
129 * buf is a fixed size with enough space to hold the largest expected
130 * reply from a nameserver, see RFC 1034 and RFC 1035.
131 * For cached entries the sizes are dependent on the actual number
132 * of aliases and addresses. If new aliases and addresses are found
133 * for cached entries, the buffer is grown and the new entries are added.
134 * The hostent struct is filled in with the addresses of the entries in
135 * the Hostent buf as follows:
136 * h_name - contains a pointer to the start of the hostname string area,
137 * or NULL if none is set. The h_name is followed by the
138 * aliases, in the storage for hostname strings area.
139 * h_aliases - contains a pointer to the start of h_aliases pointer array.
140 * This array contains pointers to the storage for hostname
141 * strings area and is terminated with a NULL. The first alias
142 * is stored directly after the h_name.
143 * h_addr_list - contains a pointer to the start of h_addr_list pointer array.
144 * This array contains pointers to in_addr structures in the
145 * h_addr_list addresses area and is terminated with a NULL.
147 * Filling the buffer this way allows for proper alignment of the h_addr_list
150 * This arrangement allows us to alias a Hostent struct pointer as a
151 * real struct hostent* without lying. It also allows us to change the
152 * values contained in the cached entries and requests without changing
153 * the actual hostent pointer, which is saved in a client struct and can't
154 * be changed without blowing things up or a lot more fiddling around.
155 * It also allows for defered allocation of the fixed size buffers until
156 * they are really needed.
157 * Nov. 17, 1997 --Bleep
160 typedef struct Hostent {
161 struct hostent h; /* the hostent struct we are passing around */
162 char* buf; /* buffer for data pointed to from hostent */
166 struct ResRequest* next;
168 int sent; /* number of requests sent */
171 char retries; /* retry counter */
172 char sends; /* number of sends (>1 means resent) */
173 char resend; /* send flag. 0 == dont resend */
178 struct DNSQuery query; /* query callback for this request */
183 struct CacheEntry* hname_next;
184 struct CacheEntry* hnum_next;
185 struct CacheEntry* list_next;
189 struct DNSReply reply;
193 struct CacheEntry* num_list;
194 struct CacheEntry* name_list;
198 int ResolverFileDescriptor = -1; /* GLOBAL - used in s_bsd.c */
200 static time_t nextDNSCheck = 0;
201 static time_t nextCacheExpire = 1;
204 * Keep a spare file descriptor open. res_init calls fopen to read the
205 * resolv.conf file. If ircd is hogging all the file descriptors below 256,
206 * on systems with crippled FILE structures this will cause wierd bugs.
207 * This is definitely needed for Solaris which uses an unsigned char to
208 * hold the file descriptor. --Dianora
210 static int spare_fd = -1;
212 static int cachedCount = 0;
213 static struct CacheTable hashtable[ARES_CACSIZE];
214 static struct CacheEntry* cacheTop;
215 static struct ResRequest* requestListHead; /* head of resolver request list */
216 static struct ResRequest* requestListTail; /* tail of resolver request list */
219 static void add_request(struct ResRequest* request);
220 static void rem_request(struct ResRequest* request);
221 static struct ResRequest* make_request(const struct DNSQuery* query);
222 static void rem_cache(struct CacheEntry*);
223 static void do_query_name(const struct DNSQuery* query,
225 struct ResRequest* request);
226 static void do_query_number(const struct DNSQuery* query,
227 const struct in_addr*,
228 struct ResRequest* request);
229 static void query_name(const char* name,
232 struct ResRequest* request);
233 static void resend_query(struct ResRequest* request);
234 static struct CacheEntry* make_cache(struct ResRequest* request);
235 static struct CacheEntry* find_cache_name(const char* name);
236 static struct CacheEntry* find_cache_number(struct ResRequest* request,
238 static struct ResRequest* find_id(int);
240 static struct cacheinfo {
250 static struct resinfo {
265 * From bind 8.3, these aren't declared in earlier versions of bind
267 extern u_short _getshort(const u_char *);
268 extern u_int _getlong(const u_char *);
271 * res_isourserver(ina)
272 * looks up "ina" in _res.ns_addr_list[]
277 * paul vixie, 29may94
280 res_ourserver(const struct __res_state* statp, const struct sockaddr_in *inp)
282 struct sockaddr_in ina;
286 for (ns = 0; ns < statp->nscount; ns++) {
287 const struct sockaddr_in *srv = &statp->nsaddr_list[ns];
289 if (srv->sin_family == ina.sin_family &&
290 srv->sin_port == ina.sin_port &&
291 (srv->sin_addr.s_addr == INADDR_ANY ||
292 srv->sin_addr.s_addr == ina.sin_addr.s_addr))
299 * start_resolver - do everything we need to read the resolv.conf file
300 * and initialize the resolver file descriptor if needed
302 static void start_resolver(void)
304 Debug((DEBUG_DNS, "Resolver: start_resolver"));
306 * close the spare file descriptor so res_init can read resolv.conf
307 * successfully. Needed on Solaris
312 res_init(); /* res_init always returns 0 */
314 * make sure we have a valid file descriptor below 256 so we can
315 * do this again. Needed on Solaris
317 spare_fd = open("/dev/null",O_RDONLY,0);
318 if ((spare_fd < 0) || (spare_fd > 255)) {
320 sprintf_irc(sparemsg, "invalid spare_fd %d", spare_fd);
321 server_restart(sparemsg);
326 _res.nsaddr_list[0].sin_addr.s_addr = inet_addr("127.0.0.1");
328 _res.options |= RES_NOALIASES;
330 if (ResolverFileDescriptor < 0) {
331 ResolverFileDescriptor = socket(AF_INET, SOCK_DGRAM, 0);
332 if (-1 == ResolverFileDescriptor) {
333 report_error("Resolver: error creating socket for %s: %s",
337 if (!os_set_nonblocking(ResolverFileDescriptor))
338 report_error("Resolver: error setting non-blocking for %s: %s",
344 * init_resolver - initialize resolver and resolver library
346 int init_resolver(void)
348 Debug((DEBUG_DNS, "Resolver: init_resolver"));
350 srand48(CurrentTime);
352 memset(&cainfo, 0, sizeof(cainfo));
353 memset(hashtable, 0, sizeof(hashtable));
354 memset(&reinfo, 0, sizeof(reinfo));
356 requestListHead = requestListTail = NULL;
360 Debug((DEBUG_DNS, "Resolver: fd %d errno: %d h_errno: %d: %s",
361 ResolverFileDescriptor, errno, h_errno,
362 (strerror(errno)) ? strerror(errno) : "Unknown"));
363 return ResolverFileDescriptor;
367 * restart_resolver - flush the cache, reread resolv.conf, reopen socket
369 void restart_resolver(void)
371 /* flush_cache(); flush the dns cache */
376 * add_request - place a new request in the request list
378 static void add_request(struct ResRequest* request)
380 assert(0 != request);
381 if (!requestListHead)
382 requestListHead = requestListTail = request;
384 requestListTail->next = request;
385 requestListTail = request;
387 request->next = NULL;
388 ++reinfo.re_requests;
392 * rem_request - remove a request from the list.
393 * This must also free any memory that has been allocated for
394 * temporary storage of DNS results.
396 static void rem_request(struct ResRequest* request)
398 struct ResRequest** current;
399 struct ResRequest* prev = NULL;
401 assert(0 != request);
402 for (current = &requestListHead; *current; ) {
403 if (*current == request) {
404 *current = request->next;
405 if (requestListTail == request)
406 requestListTail = prev;
410 current = &(*current)->next;
412 MyFree(request->he.buf);
413 MyFree(request->name);
418 * make_request - Create a DNS request record for the server.
420 static struct ResRequest* make_request(const struct DNSQuery* query)
422 struct ResRequest* request;
424 request = (struct ResRequest*) MyMalloc(sizeof(struct ResRequest));
425 memset(request, 0, sizeof(struct ResRequest));
427 request->sentat = CurrentTime;
428 request->retries = 3;
430 request->timeout = 5; /* start at 5 per RFC1123 */
431 request->addr.s_addr = INADDR_NONE;
432 request->he.h.h_addrtype = AF_INET;
433 request->he.h.h_length = sizeof(struct in_addr);
434 request->query.vptr = query->vptr;
435 request->query.callback = query->callback;
437 #if defined(NULL_POINTER_NOT_ZERO)
438 request->next = NULL;
439 request->he.buf = NULL;
440 request->he.h.h_name = NULL;
441 request->he.h.h_aliases = NULL;
442 request->he.h.h_addr_list = NULL;
444 add_request(request);
449 * timeout_query_list - Remove queries from the list which have been
450 * there too long without being resolved.
452 static time_t timeout_query_list(time_t now)
454 struct ResRequest* request;
455 struct ResRequest* next_request = 0;
456 time_t next_time = 0;
459 Debug((DEBUG_DNS, "Resolver: timeout_query_list at %s", myctime(now)));
460 for (request = requestListHead; request; request = next_request) {
461 next_request = request->next;
462 timeout = request->sentat + request->timeout;
464 if (--request->retries <= 0) {
465 ++reinfo.re_timeouts;
466 (*request->query.callback)(request->query.vptr, 0);
467 rem_request(request);
471 request->sentat = now;
472 request->timeout += request->timeout;
473 resend_query(request);
476 if (!next_time || timeout < next_time) {
480 return (next_time > now) ? next_time : (now + AR_TTL);
484 * expire_cache - removes entries from the cache which are older
485 * than their expiry times. returns the time at which the server
486 * should next poll the cache.
488 static time_t expire_cache(time_t now)
490 struct CacheEntry* cp;
491 struct CacheEntry* cp_next;
494 Debug((DEBUG_DNS, "Resolver: expire_cache at %s", myctime(now)));
495 for (cp = cacheTop; cp; cp = cp_next) {
496 cp_next = cp->list_next;
497 if (cp->expireat < now) {
501 else if (!expire || expire > cp->expireat)
502 expire = cp->expireat;
504 return (expire > now) ? expire : (now + AR_TTL);
508 * timeout_resolver - check request list and cache for expired entries
510 time_t timeout_resolver(time_t now)
512 if (nextDNSCheck < now)
513 nextDNSCheck = timeout_query_list(now);
514 if (nextCacheExpire < now)
515 nextCacheExpire = expire_cache(now);
516 return IRCD_MIN(nextDNSCheck, nextCacheExpire);
521 * delete_resolver_queries - cleanup outstanding queries
522 * for which there no longer exist clients or conf lines.
524 void delete_resolver_queries(const void* vptr)
526 struct ResRequest* request;
527 struct ResRequest* next_request;
529 for (request = requestListHead; request; request = next_request) {
530 next_request = request->next;
531 if (vptr == request->query.vptr)
532 rem_request(request);
537 * send_res_msg - sends msg to all nameservers found in the "_res" structure.
538 * This should reflect /etc/resolv.conf. We will get responses
539 * which arent needed but is easier than checking to see if nameserver
540 * isnt present. Returns number of messages successfully sent to
541 * nameservers or -1 if no successful sends.
543 static int send_res_msg(const u_char* msg, int len, int rcount)
547 int max_queries = IRCD_MIN(_res.nscount, rcount);
551 * RES_PRIMARY option is not implemented
552 * if (_res.options & RES_PRIMARY || 0 == max_queries)
554 if (0 == max_queries)
557 Debug((DEBUG_DNS, "Resolver: sendto %d", max_queries));
559 for (i = 0; i < max_queries; i++) {
560 if (sendto(ResolverFileDescriptor, msg, len, 0,
561 (struct sockaddr*) &(_res.nsaddr_list[i]),
562 sizeof(struct sockaddr_in)) == len) {
567 ircd_log(L_ERROR, "Resolver: send failed %s",
568 (strerror(errno)) ? strerror(errno) : "Unknown");
574 * find_id - find a dns request id (id is determined by dn_mkquery)
576 static struct ResRequest* find_id(int id)
578 struct ResRequest* request;
580 for (request = requestListHead; request; request = request->next) {
581 if (request->id == id)
588 * gethost_byname - get host address from name
590 struct DNSReply* gethost_byname(const char* name,
591 const struct DNSQuery* query)
593 struct CacheEntry* cp;
596 Debug((DEBUG_DNS, "Resolver: gethost_byname %s", name));
598 if ((cp = find_cache_name(name)))
601 do_query_name(query, name, NULL);
607 * gethost_byaddr - get host name from address
609 struct DNSReply* gethost_byaddr(const char* addr,
610 const struct DNSQuery* query)
612 struct CacheEntry *cp;
616 Debug((DEBUG_DNS, "Resolver: gethost_byaddr %s", ircd_ntoa(addr)));
619 if ((cp = find_cache_number(NULL, addr)))
622 do_query_number(query, (const struct in_addr*) addr, NULL);
628 * do_query_name - nameserver lookup name
630 static void do_query_name(const struct DNSQuery* query,
631 const char* name, struct ResRequest* request)
633 char hname[HOSTLEN + 1];
636 ircd_strncpy(hname, name, HOSTLEN);
637 hname[HOSTLEN] = '\0';
640 request = make_request(query);
642 request->name = (char*) MyMalloc(strlen(hname) + 1);
643 strcpy(request->name, hname);
645 query_name(hname, C_IN, T_A, request);
649 * do_query_number - Use this to do reverse IP# lookups.
651 static void do_query_number(const struct DNSQuery* query,
652 const struct in_addr* addr,
653 struct ResRequest* request)
656 const unsigned char* cp;
659 cp = (const unsigned char*) &addr->s_addr;
660 sprintf_irc(ipbuf, "%u.%u.%u.%u.in-addr.arpa.",
661 (unsigned int)(cp[3]), (unsigned int)(cp[2]),
662 (unsigned int)(cp[1]), (unsigned int)(cp[0]));
665 request = make_request(query);
666 request->type = T_PTR;
667 request->addr.s_addr = addr->s_addr;
669 query_name(ipbuf, C_IN, T_PTR, request);
673 * query_name - generate a query based on class, type and name.
675 static void query_name(const char* name, int query_class,
676 int type, struct ResRequest* request)
682 assert(0 != request);
684 Debug((DEBUG_DNS, "Resolver: query_name: %s %d %d", name, query_class, type));
685 memset(buf, 0, sizeof(buf));
686 if ((request_len = res_mkquery(QUERY, name, query_class, type,
687 0, 0, 0, (unsigned char*) buf, sizeof(buf))) > 0) {
688 HEADER* header = (HEADER*) buf;
694 * generate a unique id
695 * NOTE: we don't have to worry about converting this to and from
696 * network byte order, the nameserver does not interpret this value
697 * and returns it unchanged
701 header->id = (header->id + lrand48()) & 0xffff;
702 } while (find_id(header->id));
704 gettimeofday(&tv, NULL);
706 header->id = (header->id + k + tv.tv_usec) & 0xffff;
708 } while (find_id(header->id));
710 request->id = header->id;
712 Debug((DEBUG_DNS, "Resolver: query_name %d: %s %d %d", request->id,
713 name, query_class, type));
714 request->sent += send_res_msg((const unsigned char*) buf, request_len, request->sends);
718 static void resend_query(struct ResRequest* request)
720 assert(0 != request);
722 if (request->resend == 0)
725 switch(request->type) {
727 do_query_number(NULL, &request->addr, request);
730 do_query_name(NULL, request->name, request);
738 * proc_answer - process name server reply
739 * build a hostent struct in the passed request
741 static int proc_answer(struct ResRequest* request, HEADER* header,
742 u_char* buf, u_char* eob)
744 char hostbuf[HOSTLEN + 1]; /* working buffer */
745 u_char* current; /* current position in buf */
746 char** alias; /* alias list */
747 char** addr; /* address list */
748 char* name; /* pointer to name string */
749 char* address; /* pointer to address */
750 char* endp; /* end of our buffer */
751 int query_class; /* answer class */
752 int type; /* answer type */
753 int rd_length; /* record data length */
754 int answer_count = 0; /* answer counter */
755 int n; /* temp count */
756 int addr_count = 0; /* number of addresses in hostent */
757 int alias_count = 0; /* number of aliases in hostent */
758 struct hostent* hp; /* hostent getting filled */
760 assert(0 != request);
765 current = buf + sizeof(HEADER);
766 hp = &(request->he.h);
768 * lazy allocation of request->he.buf, we don't allocate a buffer
769 * unless there is something to put in it.
771 if (!request->he.buf) {
772 request->he.buf = (char*) MyMalloc(MAXGETHOSTLEN + 1);
773 request->he.buf[MAXGETHOSTLEN] = '\0';
775 * array of alias list pointers starts at beginning of buf
777 hp->h_aliases = (char**) request->he.buf;
778 hp->h_aliases[0] = NULL;
780 * array of address list pointers starts after alias list pointers
781 * the actual addresses follow the the address list pointers
783 hp->h_addr_list = (char**)(request->he.buf + ALIAS_BLEN);
785 * don't copy the host address to the beginning of h_addr_list
787 hp->h_addr_list[0] = NULL;
789 endp = request->he.buf + MAXGETHOSTLEN;
791 * find the end of the address list
793 addr = hp->h_addr_list;
799 * make address point to first available address slot
801 address = request->he.buf + ADDRS_OFFSET +
802 (sizeof(struct in_addr) * addr_count);
804 * find the end of the alias list
806 alias = hp->h_aliases;
812 * make name point to first available space in request->buf
814 if (alias_count > 0) {
815 name = hp->h_aliases[alias_count - 1];
816 name += (strlen(name) + 1);
819 name = hp->h_name + strlen(hp->h_name) + 1;
821 name = request->he.buf + ADDRS_OFFSET + ADDRS_DLEN;
826 while (header->qdcount-- > 0) {
827 if ((n = dn_skipname(current, eob)) < 0)
829 current += (n + QFIXEDSZ);
832 * process each answer sent to us blech.
834 while (header->ancount-- > 0 && current < eob && name < endp) {
835 n = dn_expand(buf, eob, current, hostbuf, sizeof(hostbuf));
838 * no more answers left
842 hostbuf[HOSTLEN] = '\0';
844 * With Address arithmetic you have to be very anal
845 * this code was not working on alpha due to that
846 * (spotted by rodder/jailbird/dianora)
848 current += (size_t) n;
850 if (!((current + ANSWER_FIXED_SIZE) < eob))
853 type = _getshort(current);
854 current += TYPE_SIZE;
856 query_class = _getshort(current);
857 current += CLASS_SIZE;
859 request->ttl = _getlong(current);
862 rd_length = _getshort(current);
863 current += RDLENGTH_SIZE;
866 * Wait to set request->type until we verify this structure
871 * check for invalid rd_length or too many addresses
873 if (rd_length != sizeof(struct in_addr))
875 if (++addr_count < RES_MAXADDRS) {
876 if (answer_count == 1)
877 hp->h_addrtype = (query_class == C_IN) ? AF_INET : AF_UNSPEC;
879 memcpy(address, current, sizeof(struct in_addr));
882 address += sizeof(struct in_addr);
885 strcpy(name, hostbuf);
887 name += strlen(name) + 1;
889 Debug((DEBUG_DNS, "Resolver: A %s for %s",
890 ircd_ntoa((char*) hp->h_addr_list[addr_count - 1]), hostbuf));
892 current += rd_length;
896 n = dn_expand(buf, eob, current, hostbuf, sizeof(hostbuf));
905 * no more answers left
910 * This comment is based on analysis by Shadowfax, Wohali and johan,
911 * not me. (Dianora) I am only commenting it.
913 * dn_expand is guaranteed to not return more than sizeof(hostbuf)
914 * but do all implementations of dn_expand also guarantee
915 * buffer is terminated with null byte? Lets not take chances.
918 hostbuf[HOSTLEN] = '\0';
919 current += (size_t) n;
921 Debug((DEBUG_DNS, "Resolver: PTR %s", hostbuf));
923 * copy the returned hostname into the host name
924 * ignore duplicate ptr records
927 strcpy(name, hostbuf);
929 name += strlen(name) + 1;
934 Debug((DEBUG_DNS, "Resolver: CNAME %s", hostbuf));
935 if (++alias_count < RES_MAXALIASES) {
936 ircd_strncpy(name, hostbuf, endp - name);
939 name += strlen(name) + 1;
941 current += rd_length;
945 Debug((DEBUG_DNS,"Resolver: proc_answer type: %d for: %s", type, hostbuf));
953 * resolver_read - read a dns reply from the nameserver and process it.
954 * return 0 if nothing was read from the socket, otherwise return 1
956 int resolver_read(void)
958 u_char buf[sizeof(HEADER) + MAXPACKET];
960 struct ResRequest* request = 0;
961 struct CacheEntry* cp = 0;
963 int answer_count = 0;
964 struct sockaddr_in sin;
966 Debug((DEBUG_DNS, "Resolver: read"));
967 if (IO_SUCCESS != os_recvfrom_nonb(ResolverFileDescriptor,
968 (char*) buf, sizeof(buf), &rc, &sin)) {
971 if (rc < sizeof(HEADER)) {
972 Debug((DEBUG_DNS, "Resolver: short reply %d: %s", rc,
973 (strerror(errno)) ? strerror(errno) : "Unknown"));
977 * convert DNS reply reader from Network byte order to CPU byte order.
979 header = (HEADER*) buf;
980 /* header->id = ntohs(header->id); */
981 header->ancount = ntohs(header->ancount);
982 header->qdcount = ntohs(header->qdcount);
983 header->nscount = ntohs(header->nscount);
984 header->arcount = ntohs(header->arcount);
987 * response for an id which we have already received an answer for
988 * just ignore this response.
990 if (0 == (request = find_id(header->id))) {
991 Debug((DEBUG_DNS, "Resolver: can't find request id: %d", header->id));
995 * check against possibly fake replies
997 if (!res_ourserver(&_res, &sin)) {
998 Debug((DEBUG_DNS, "Resolver: fake reply from: %s",
999 (const char*) &sin.sin_addr));
1004 if ((header->rcode != NOERROR) || (header->ancount == 0)) {
1006 if (SERVFAIL == header->rcode)
1007 resend_query(request);
1010 * If a bad error was returned, we stop here and dont send
1011 * send any more (no retries granted).
1012 * Isomer: Perhaps we should return these error messages back to
1016 switch (header->rcode) {
1018 Debug((DEBUG_DNS, "Fatal DNS error: No Error"));
1021 Debug((DEBUG_DNS, "Fatal DNS error: Format Error"));
1024 Debug((DEBUG_DNS, "Fatal DNS error: Server Failure"));
1027 Debug((DEBUG_DNS, "DNS error: Non Existant Domain"));
1030 Debug((DEBUG_DNS, "Fatal DNS error: Not Implemented"));
1033 Debug((DEBUG_DNS, "Fatal DNS error: Query Refused"));
1036 Debug((DEBUG_DNS, "Unassigned fatal DNS error: %i", header->rcode));
1039 #endif /* DEBUGMODE */
1040 (*request->query.callback)(request->query.vptr, 0);
1041 rem_request(request);
1046 * If this fails there was an error decoding the received packet,
1047 * try it again and hope it works the next time.
1049 answer_count = proc_answer(request, header, buf, buf + rc);
1051 if (T_PTR == request->type) {
1052 struct DNSReply* reply = NULL;
1053 if (0 == request->he.h.h_name) {
1055 * got a PTR response with no name, something bogus is happening
1056 * don't bother trying again, the client address doesn't resolve
1058 (*request->query.callback)(request->query.vptr, reply);
1059 rem_request(request);
1062 Debug((DEBUG_DNS, "relookup %s <-> %s",
1063 request->he.h.h_name, ircd_ntoa((char*) &request->addr)));
1065 * Lookup the 'authoritive' name that we were given for the
1066 * ip#. By using this call rather than regenerating the
1067 * type we automatically gain the use of the cache with no
1070 reply = gethost_byname(request->he.h.h_name, &request->query);
1073 * If name wasn't found, a request has been queued and it will
1074 * be the last one queued. This is rather nasty way to keep
1075 * a host alias with the query. -avalon
1077 MyFree(requestListTail->he.buf);
1078 requestListTail->he.buf = request->he.buf;
1079 request->he.buf = 0;
1080 memcpy(&requestListTail->he.h, &request->he.h, sizeof(struct hostent));
1083 (*request->query.callback)(request->query.vptr, reply);
1084 rem_request(request);
1088 * got a name and address response, client resolved
1089 * XXX - Bug found here by Dianora -
1090 * make_cache() occasionally returns a NULL pointer when a
1091 * PTR returned a CNAME, cp was not checked before so the
1092 * callback was being called with a value of 0x2C != NULL.
1094 cp = make_cache(request);
1095 (*request->query.callback)(request->query.vptr,
1096 (cp) ? &cp->reply : 0);
1097 rem_request(request);
1100 else if (!request->sent) {
1102 * XXX - we got a response for a query we didn't send with a valid id?
1103 * this should never happen, bail here and leave the client unresolved
1105 (*request->query.callback)(request->query.vptr, 0);
1106 rem_request(request);
1112 * resolver_read_multiple - process up to count reads
1114 void resolver_read_multiple(int count)
1117 for ( ; i < count; ++i) {
1118 if (0 == resolver_read())
1123 static size_t calc_hostent_buffer_size(const struct hostent* hp)
1132 count += (strlen(hp->h_name) + 1);
1136 for (p = hp->h_aliases; *p; ++p)
1137 count += (strlen(*p) + 1 + sizeof(char*));
1139 * space for addresses
1141 for (p = hp->h_addr_list; *p; ++p)
1142 count += (hp->h_length + sizeof(char*));
1144 * space for 2 nulls to terminate h_aliases and h_addr_list
1146 count += (2 * sizeof(char*));
1152 * dup_hostent - Duplicate a hostent struct, allocate only enough memory for
1153 * the data we're putting in it.
1155 static void dup_hostent(aHostent* new_hp, struct hostent* hp)
1160 int alias_count = 0;
1162 size_t bytes_needed = 0;
1164 assert(0 != new_hp);
1167 /* how much buffer do we need? */
1168 bytes_needed += (strlen(hp->h_name) + 1);
1172 bytes_needed += (strlen(*pp++) + 1 + sizeof(char*));
1175 pp = hp->h_addr_list;
1177 bytes_needed += (hp->h_length + sizeof(char*));
1180 /* Reserve space for 2 nulls to terminate h_aliases and h_addr_list */
1181 bytes_needed += (2 * sizeof(char*));
1183 /* Allocate memory */
1184 new_hp->buf = (char*) MyMalloc(bytes_needed);
1186 new_hp->h.h_addrtype = hp->h_addrtype;
1187 new_hp->h.h_length = hp->h_length;
1189 /* first write the address list */
1190 pp = hp->h_addr_list;
1191 ap = new_hp->h.h_addr_list =
1192 (char**)(new_hp->buf + ((alias_count + 1) * sizeof(char*)));
1193 p = (char*)ap + ((addr_count + 1) * sizeof(char*));
1197 memcpy(p, *pp++, hp->h_length);
1201 /* next write the name */
1202 new_hp->h.h_name = p;
1203 strcpy(p, hp->h_name);
1204 p += (strlen(p) + 1);
1206 /* last write the alias list */
1208 ap = new_hp->h.h_aliases = (char**) new_hp->buf;
1212 p += (strlen(p) + 1);
1218 * update_hostent - Add records to a Hostent struct in place.
1220 static void update_hostent(aHostent* hp, char** addr, char** alias)
1225 int alias_count = 0;
1228 size_t bytes_needed = 0;
1230 if (!hp || !hp->buf)
1233 /* how much buffer do we need? */
1234 bytes_needed = strlen(hp->h.h_name) + 1;
1235 pp = hp->h.h_aliases;
1237 bytes_needed += (strlen(*pp++) + 1 + sizeof(char*));
1243 bytes_needed += (strlen(*pp++) + 1 + sizeof(char*));
1247 pp = hp->h.h_addr_list;
1249 bytes_needed += (hp->h.h_length + sizeof(char*));
1255 bytes_needed += (hp->h.h_length + sizeof(char*));
1259 /* Reserve space for 2 nulls to terminate h_aliases and h_addr_list */
1260 bytes_needed += 2 * sizeof(char*);
1262 /* Allocate memory */
1263 buf = (char*) MyMalloc(bytes_needed);
1266 /* first write the address list */
1267 pp = hp->h.h_addr_list;
1268 ap = hp->h.h_addr_list =
1269 (char**)(buf + ((alias_count + 1) * sizeof(char*)));
1270 p = (char*)ap + ((addr_count + 1) * sizeof(char*));
1272 memcpy(p, *pp++, hp->h.h_length);
1274 p += hp->h.h_length;
1278 memcpy(p, *addr++, hp->h.h_length);
1280 p += hp->h.h_length;
1285 /* next write the name */
1286 strcpy(p, hp->h.h_name);
1288 p += (strlen(p) + 1);
1290 /* last write the alias list */
1291 pp = hp->h.h_aliases;
1292 ap = hp->h.h_aliases = (char**) buf;
1296 p += (strlen(p) + 1);
1300 strcpy(p, *alias++);
1302 p += (strlen(p) + 1);
1306 /* release the old buffer */
1313 * hash_number - IP address hash function
1315 static int hash_number(const unsigned char* ip)
1317 /* could use loop but slower */
1319 const u_char* p = (const u_char*) ip;
1324 hashv += hashv + *p++;
1325 hashv += hashv + *p++;
1326 hashv += hashv + *p;
1327 hashv %= ARES_CACSIZE;
1332 * hash_name - hostname hash function
1334 static int hash_name(const char* name)
1336 unsigned int hashv = 0;
1337 const u_char* p = (const u_char*) name;
1341 for (; *p && *p != '.'; ++p)
1343 hashv %= ARES_CACSIZE;
1348 * add_to_cache - Add a new cache item to the queue and hash table.
1350 static struct CacheEntry* add_to_cache(struct CacheEntry* ocp)
1356 ocp->list_next = cacheTop;
1359 hashv = hash_name(ocp->he.h.h_name);
1361 ocp->hname_next = hashtable[hashv].name_list;
1362 hashtable[hashv].name_list = ocp;
1364 hashv = hash_number((const unsigned char*) ocp->he.h.h_addr);
1366 ocp->hnum_next = hashtable[hashv].num_list;
1367 hashtable[hashv].num_list = ocp;
1370 * LRU deletion of excessive cache entries.
1372 if (++cachedCount > MAXCACHED) {
1373 struct CacheEntry* cp;
1374 struct CacheEntry* cp_next;
1375 for (cp = ocp->list_next; cp; cp = cp_next) {
1376 cp_next = cp->list_next;
1385 * update_list - does not alter the cache structure passed. It is assumed that
1386 * it already contains the correct expire time, if it is a new entry. Old
1387 * entries have the expirey time updated.
1389 static void update_list(struct ResRequest* request, struct CacheEntry* cachep)
1392 struct CacheEntry** cpp;
1394 struct CacheEntry* cp = cachep;
1400 char* addrs[RES_MAXADDRS + 1];
1401 char* aliases[RES_MAXALIASES + 1];
1404 * search for the new cache item in the cache list by hostname.
1405 * If found, move the entry to the top of the list and return.
1407 ++cainfo.ca_updates;
1409 for (cpp = &cacheTop; *cpp; cpp = &((*cpp)->list_next)) {
1415 *cpp = cp->list_next;
1416 cp->list_next = cacheTop;
1423 * Compare the cache entry against the new record. Add any
1424 * previously missing names for this entry.
1428 for (i = 0, s = request->he.h.h_name; s; s = request->he.h.h_aliases[i++]) {
1429 for (j = 0, t = cp->he.h.h_name; t; t = cp->he.h.h_aliases[j++]) {
1430 if (0 == ircd_strcmp(t, s))
1439 * Do the same again for IP#'s.
1443 for (i = 0; (s = request->he.h.h_addr_list[i]); i++) {
1444 for (j = 0; (t = cp->he.h.h_addr_list[j]); j++) {
1445 if (!memcmp(t, s, sizeof(struct in_addr)))
1453 if (*addrs || *aliases)
1454 update_hostent(&cp->he, addrs, aliases);
1458 * find_cache_name - find name in nameserver cache
1460 static struct CacheEntry* find_cache_name(const char* name)
1462 struct CacheEntry* cp;
1468 hashv = hash_name(name);
1470 cp = hashtable[hashv].name_list;
1472 for (; cp; cp = cp->hname_next) {
1473 for (i = 0, s = cp->he.h.h_name; s; s = cp->he.h.h_aliases[i++]) {
1474 if (0 == ircd_strcmp(s, name)) {
1475 ++cainfo.ca_na_hits;
1481 for (cp = cacheTop; cp; cp = cp->list_next) {
1483 * if no aliases or the hash value matches, we've already
1484 * done this entry and all possiblilities concerning it.
1486 if (!cp->he.h.h_name || hashv == hash_name(cp->he.h.h_name))
1488 for (i = 0, s = cp->he.h.h_aliases[i]; s; s = cp->he.h.h_aliases[++i]) {
1489 if (0 == ircd_strcmp(name, s)) {
1490 ++cainfo.ca_na_hits;
1499 * find_cache_number - find a cache entry by ip# and update its expire time
1501 static struct CacheEntry* find_cache_number(struct ResRequest* request,
1504 struct CacheEntry* cp;
1509 hashv = hash_number((const unsigned char*) addr);
1510 cp = hashtable[hashv].num_list;
1512 for (; cp; cp = cp->hnum_next) {
1513 for (i = 0; cp->he.h.h_addr_list[i]; ++i) {
1514 if (!memcmp(cp->he.h.h_addr_list[i], addr, sizeof(struct in_addr))) {
1515 ++cainfo.ca_nu_hits;
1520 for (cp = cacheTop; cp; cp = cp->list_next) {
1522 * single address entry...would have been done by hashed
1524 * if the first IP# has the same hashnumber as the IP# we
1525 * are looking for, its been done already.
1527 if (!cp->he.h.h_addr_list[1] ||
1528 hashv == hash_number((const unsigned char*) cp->he.h.h_addr_list[0]))
1530 for (i = 1; cp->he.h.h_addr_list[i]; ++i) {
1531 if (!memcmp(cp->he.h.h_addr_list[i], addr, sizeof(struct in_addr))) {
1532 ++cainfo.ca_nu_hits;
1540 static struct CacheEntry* make_cache(struct ResRequest* request)
1542 struct CacheEntry* cp;
1545 assert(0 != request);
1547 hp = &request->he.h;
1549 * shouldn't happen but it just might...
1551 assert(0 != hp->h_name);
1552 assert(0 != hp->h_addr_list[0]);
1553 if (!hp->h_name || !hp->h_addr_list[0])
1556 * Make cache entry. First check to see if the cache already exists
1557 * and if so, return a pointer to it.
1559 for (i = 0; hp->h_addr_list[i]; ++i) {
1560 if ((cp = find_cache_number(request, hp->h_addr_list[i]))) {
1561 update_list(request, cp);
1566 * a matching entry wasnt found in the cache so go and make one up.
1568 cp = (struct CacheEntry*) MyMalloc(sizeof(struct CacheEntry));
1571 memset(cp, 0, sizeof(struct CacheEntry));
1572 dup_hostent(&cp->he, hp);
1573 cp->reply.hp = &cp->he.h;
1575 * hmmm... we could time out the cache after 10 minutes regardless
1576 * would that be reasonable since we don't save the reply?
1578 if (request->ttl < AR_TTL) {
1579 ++reinfo.re_shortttl;
1583 cp->ttl = request->ttl;
1584 cp->expireat = CurrentTime + cp->ttl;
1585 return add_to_cache(cp);
1589 * rem_cache - delete a cache entry from the cache structures
1590 * and lists and return all memory used for the cache back to the memory pool.
1592 static void rem_cache(struct CacheEntry* ocp)
1594 struct CacheEntry** cp;
1600 if (0 < ocp->reply.ref_count) {
1601 if (ocp->expireat < CurrentTime) {
1602 ocp->expireat = CurrentTime + AR_TTL;
1603 Debug((DEBUG_DNS, "Resolver: referenced cache entry not removed for: %s",
1609 * remove cache entry from linked list
1611 for (cp = &cacheTop; *cp; cp = &((*cp)->list_next)) {
1613 *cp = ocp->list_next;
1619 * remove cache entry from hashed name list
1621 assert(0 != hp->h_name);
1622 hashv = hash_name(hp->h_name);
1624 for (cp = &hashtable[hashv].name_list; *cp; cp = &((*cp)->hname_next)) {
1626 *cp = ocp->hname_next;
1631 * remove cache entry from hashed number list
1633 hashv = hash_number((const unsigned char*) hp->h_addr);
1636 for (cp = &hashtable[hashv].num_list; *cp; cp = &((*cp)->hnum_next)) {
1638 *cp = ocp->hnum_next;
1643 * free memory used to hold the various host names and the array
1644 * of alias pointers.
1646 MyFree(ocp->he.buf);
1652 void flush_resolver_cache(void)
1655 * stubbed - iterate cache and remove everything that isn't referenced
1660 * m_dns - dns status query
1662 int m_dns(struct Client *cptr, struct Client *sptr, int parc, char *parv[])
1664 #if !defined(NDEBUG)
1665 struct CacheEntry* cp;
1669 if (parv[1] && *parv[1] == 'l') {
1670 for(cp = cacheTop; cp; cp = cp->list_next) {
1672 sendcmdto_one(&me, CMD_NOTICE, sptr, "%C :Ex %d ttl %d host %s(%s)",
1673 sptr, cp->expireat - CurrentTime, cp->ttl,
1674 hp->h_name, ircd_ntoa(hp->h_addr));
1675 for (i = 0; hp->h_aliases[i]; i++)
1676 sendcmdto_one(&me, CMD_NOTICE, sptr, "%C : %s = %s (CN)", sptr,
1677 hp->h_name, hp->h_aliases[i]);
1678 for (i = 1; hp->h_addr_list[i]; i++)
1679 sendcmdto_one(&me, CMD_NOTICE, sptr, "%C : %s = %s (IP)", sptr,
1680 hp->h_name, ircd_ntoa(hp->h_addr_list[i]));
1684 if (parv[1] && *parv[1] == 'd') {
1685 sendcmdto_one(&me, CMD_NOTICE, sptr, "%C :ResolverFileDescriptor = %d",
1686 sptr, ResolverFileDescriptor);
1689 sendcmdto_one(&me, CMD_NOTICE, sptr,"%C :Ca %d Cd %d Ce %d Cl %d Ch %d:%d "
1691 cainfo.ca_adds, cainfo.ca_dels, cainfo.ca_expires,
1692 cainfo.ca_lookups, cainfo.ca_na_hits, cainfo.ca_nu_hits,
1695 sendcmdto_one(&me, CMD_NOTICE, sptr,"%C :Re %d Rl %d/%d Rp %d Rq %d",
1696 sptr, reinfo.re_errors, reinfo.re_nu_look,
1697 reinfo.re_na_look, reinfo.re_replies, reinfo.re_requests);
1698 sendcmdto_one(&me, CMD_NOTICE, sptr,"%C :Ru %d Rsh %d Rs %d(%d) Rt %d", sptr,
1699 reinfo.re_unkrep, reinfo.re_shortttl, reinfo.re_sent,
1700 reinfo.re_resends, reinfo.re_timeouts);
1705 size_t cres_mem(struct Client* sptr)
1707 struct CacheEntry* entry;
1708 struct ResRequest* request;
1709 size_t cache_mem = 0;
1710 size_t request_mem = 0;
1711 int cache_count = 0;
1712 int request_count = 0;
1714 for (entry = cacheTop; entry; entry = entry->list_next) {
1715 cache_mem += sizeof(struct CacheEntry);
1716 cache_mem += calc_hostent_buffer_size(&entry->he.h);
1719 for (request = requestListHead; request; request = request->next) {
1720 request_mem += sizeof(struct ResRequest);
1722 request_mem += strlen(request->name) + 1;
1723 if (request->he.buf)
1724 request_mem += MAXGETHOSTLEN + 1;
1728 if (cachedCount != cache_count) {
1729 send_reply(sptr, SND_EXPLICIT | RPL_STATSDEBUG,
1730 ":Resolver: cache count mismatch: %d != %d", cachedCount,
1732 assert(cachedCount == cache_count);
1734 send_reply(sptr, SND_EXPLICIT | RPL_STATSDEBUG,
1735 ":Resolver: cache %d(%d) requests %d(%d)", cache_count,
1736 cache_mem, request_count, request_mem);
1737 return cache_mem + request_mem;