1 /* $Id: evdns.c 6979 2006-08-04 18:31:13Z nickm $ */
3 /* The original version of this module was written by Adam Langley; for
4 * a history of modifications, check out the subversion logs.
6 * When editing this module, try to keep it re-mergeable by Adam. Don't
7 * reformat the whitespace, add Tor dependencies, or so on.
10 * - Support IPv6 and PTR records.
11 * - Replace all externally visible magic numbers with #defined constants.
12 * - Write documentation for APIs of all external functions.
16 * Adam Langley <agl@imperialviolet.org>
17 * http://www.imperialviolet.org/eventdns.html
20 * This software is Public Domain. To view a copy of the public domain dedication,
21 * visit http://creativecommons.org/licenses/publicdomain/ or send a letter to
22 * Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA.
24 * I ask and expect, but do not require, that all derivative works contain an
25 * attribution similar to:
26 * Parts developed by Adam Langley <agl@imperialviolet.org>
28 * You may wish to replace the word "Parts" with something else depending on
29 * the amount of original code.
31 * (Derivative works does not include programs which link against, run or include
32 * the source verbatim in their source distributions)
37 #include <sys/types.h>
38 #include "event2/event-config.h"
40 #ifndef _FORTIFY_SOURCE
41 #define _FORTIFY_SOURCE 3
46 #ifdef _EVENT_HAVE_SYS_TIME_H
49 #ifdef _EVENT_HAVE_STDINT_H
55 #ifdef _EVENT_HAVE_UNISTD_H
66 #define _WIN32_IE 0x400
71 #include "event2/dns.h"
72 #include "event2/dns_struct.h"
73 #include "event2/dns_compat.h"
74 #include "event2/util.h"
75 #include "event2/event.h"
76 #include "event2/event_struct.h"
77 #include "event2/thread.h"
79 #include "event2/bufferevent.h"
80 #include "event2/bufferevent_struct.h"
81 #include "bufferevent-internal.h"
83 #include "defer-internal.h"
84 #include "log-internal.h"
85 #include "mm-internal.h"
86 #include "strlcpy-internal.h"
87 #include "ipv6-internal.h"
88 #include "util-internal.h"
89 #include "evthread-internal.h"
97 #include <sys/socket.h>
98 #include <netinet/in.h>
99 #include <arpa/inet.h>
102 #ifdef _EVENT_HAVE_NETINET_IN6_H
103 #include <netinet/in6.h>
106 #define EVDNS_LOG_DEBUG 0
107 #define EVDNS_LOG_WARN 1
108 #define EVDNS_LOG_MSG 2
110 #ifndef HOST_NAME_MAX
111 #define HOST_NAME_MAX 255
117 #define MIN(a,b) ((a)<(b)?(a):(b))
119 #define ASSERT_VALID_REQUEST(req) \
120 EVUTIL_ASSERT((req)->handle && (req)->handle->current_req == (req))
122 #define u64 ev_uint64_t
123 #define u32 ev_uint32_t
124 #define u16 ev_uint16_t
125 #define u8 ev_uint8_t
127 /* maximum number of addresses from a single packet */
128 /* that we bother recording */
129 #define MAX_V4_ADDRS 32
130 #define MAX_V6_ADDRS 32
133 #define TYPE_A EVDNS_TYPE_A
135 #define TYPE_PTR EVDNS_TYPE_PTR
136 #define TYPE_AAAA EVDNS_TYPE_AAAA
138 #define CLASS_INET EVDNS_CLASS_INET
140 /* Persistent handle. We keep this separate from 'struct request' since we
141 * need some object to last for as long as an evdns_request is outstanding so
142 * that it can be canceled, whereas a search request can lead to multiple
143 * 'struct request' instances being created over its lifetime. */
144 struct evdns_request {
145 struct request *current_req;
146 struct evdns_base *base;
148 int pending_cb; /* Waiting for its callback to be invoked; not
149 * owned by event base any more. */
151 /* elements used by the searching code */
153 struct search_state *search_state;
154 char *search_origname; /* needs to be free()ed */
159 u8 *request; /* the dns packet data */
160 u8 request_type; /* TYPE_PTR or TYPE_A or TYPE_AAAA */
161 unsigned int request_len;
163 int tx_count; /* the number of times that this packet has been sent */
164 void *user_pointer; /* the pointer given to us for this request */
165 evdns_callback_type user_callback;
166 struct nameserver *ns; /* the server which we last sent it */
168 /* these objects are kept in a circular list */
169 struct request *next, *prev;
171 struct event timeout_event;
173 u16 trans_id; /* the transaction id */
174 unsigned request_appended :1; /* true if the request pointer is data which follows this struct */
175 unsigned transmit_me :1; /* needs to be transmitted */
177 /* XXXX This is a horrible hack. */
178 char **put_cname_in_ptr; /* store the cname here if we get one. */
180 struct evdns_base *base;
182 struct evdns_request *handle;
187 unsigned int have_answer : 1;
191 u32 addresses[MAX_V4_ADDRS];
195 struct in6_addr addresses[MAX_V6_ADDRS];
198 char name[HOST_NAME_MAX];
204 evutil_socket_t socket; /* a connected UDP socket */
205 struct sockaddr_storage address;
206 ev_socklen_t addrlen;
207 int failed_times; /* number of times which we have given this server a chance */
208 int timedout; /* number of times in a row a request has timed out */
210 /* these objects are kept in a circular list */
211 struct nameserver *next, *prev;
212 struct event timeout_event; /* used to keep the timeout for */
213 /* when we next probe this server. */
214 /* Valid if state == 0 */
215 /* Outstanding probe request for this nameserver, if any */
216 struct evdns_request *probe_request;
217 char state; /* zero if we think that this server is down */
218 char choked; /* true if we have an EAGAIN from this server's socket */
219 char write_waiting; /* true if we are waiting for EV_WRITE events */
220 struct evdns_base *base;
224 /* Represents a local port where we're listening for DNS requests. Right now, */
225 /* only UDP is supported. */
226 struct evdns_server_port {
227 evutil_socket_t socket; /* socket we use to read queries and write replies. */
228 int refcnt; /* reference count. */
229 char choked; /* Are we currently blocked from writing? */
230 char closing; /* Are we trying to close this port, pending writes? */
231 evdns_request_callback_fn_type user_callback; /* Fn to handle requests */
232 void *user_data; /* Opaque pointer passed to user_callback */
233 struct event event; /* Read/write event */
234 /* circular list of replies that we want to write. */
235 struct server_request *pending_replies;
236 struct event_base *event_base;
238 #ifndef _EVENT_DISABLE_THREAD_SUPPORT
243 /* Represents part of a reply being built. (That is, a single RR.) */
244 struct server_reply_item {
245 struct server_reply_item *next; /* next item in sequence. */
246 char *name; /* name part of the RR */
247 u16 type; /* The RR type */
248 u16 class; /* The RR class (usually CLASS_INET) */
249 u32 ttl; /* The RR TTL */
250 char is_name; /* True iff data is a label */
251 u16 datalen; /* Length of data; -1 if data is a label */
252 void *data; /* The contents of the RR */
255 /* Represents a request that we've received as a DNS server, and holds */
256 /* the components of the reply as we're constructing it. */
257 struct server_request {
258 /* Pointers to the next and previous entries on the list of replies */
259 /* that we're waiting to write. Only set if we have tried to respond */
260 /* and gotten EAGAIN. */
261 struct server_request *next_pending;
262 struct server_request *prev_pending;
264 u16 trans_id; /* Transaction id. */
265 struct evdns_server_port *port; /* Which port received this request on? */
266 struct sockaddr_storage addr; /* Where to send the response */
267 ev_socklen_t addrlen; /* length of addr */
269 int n_answer; /* how many answer RRs have been set? */
270 int n_authority; /* how many authority RRs have been set? */
271 int n_additional; /* how many additional RRs have been set? */
273 struct server_reply_item *answer; /* linked list of answer RRs */
274 struct server_reply_item *authority; /* linked list of authority RRs */
275 struct server_reply_item *additional; /* linked list of additional RRs */
277 /* Constructed response. Only set once we're ready to send a reply. */
278 /* Once this is set, the RR fields are cleared, and no more should be set. */
282 /* Caller-visible fields: flags, questions. */
283 struct evdns_server_request base;
287 /* An array of n_req_heads circular lists for inflight requests.
288 * Each inflight request req is in req_heads[req->trans_id % n_req_heads].
290 struct request **req_heads;
291 /* A circular list of requests that we're waiting to send, but haven't
292 * sent yet because there are too many requests inflight */
293 struct request *req_waiting_head;
294 /* A circular list of nameservers. */
295 struct nameserver *server_head;
298 struct event_base *event_base;
300 /* The number of good nameservers that we have */
301 int global_good_nameservers;
303 /* inflight requests are contained in the req_head list */
304 /* and are actually going out across the network */
305 int global_requests_inflight;
306 /* requests which aren't inflight are in the waiting list */
307 /* and are counted here */
308 int global_requests_waiting;
310 int global_max_requests_inflight;
312 struct timeval global_timeout; /* 5 seconds by default */
313 int global_max_reissues; /* a reissue occurs when we get some errors from the server */
314 int global_max_retransmits; /* number of times we'll retransmit a request which timed out */
315 /* number of timeouts in a row before we consider this server to be down */
316 int global_max_nameserver_timeout;
317 /* true iff we will use the 0x20 hack to prevent poisoning attacks. */
318 int global_randomize_case;
320 /* The first time that a nameserver fails, how long do we wait before
321 * probing to see if it has returned? */
322 struct timeval global_nameserver_probe_initial_timeout;
324 /** Port to bind to for outgoing DNS packets. */
325 struct sockaddr_storage global_outgoing_address;
326 /** ev_socklen_t for global_outgoing_address. 0 if it isn't set. */
327 ev_socklen_t global_outgoing_addrlen;
329 struct timeval global_getaddrinfo_allow_skew;
331 int getaddrinfo_ipv4_timeouts;
332 int getaddrinfo_ipv6_timeouts;
333 int getaddrinfo_ipv4_answered;
334 int getaddrinfo_ipv6_answered;
336 struct search_state *global_search_state;
338 TAILQ_HEAD(hosts_list, hosts_entry) hostsdb;
340 #ifndef _EVENT_DISABLE_THREAD_SUPPORT
346 TAILQ_ENTRY(hosts_entry) next;
349 struct sockaddr_in sin;
350 struct sockaddr_in6 sin6;
356 static struct evdns_base *current_base = NULL;
359 evdns_get_global_base(void)
364 /* Given a pointer to an evdns_server_request, get the corresponding */
365 /* server_request. */
366 #define TO_SERVER_REQUEST(base_ptr) \
367 ((struct server_request*) \
368 (((char*)(base_ptr) - evutil_offsetof(struct server_request, base))))
370 #define REQ_HEAD(base, id) ((base)->req_heads[id % (base)->n_req_heads])
372 static struct nameserver *nameserver_pick(struct evdns_base *base);
373 static void evdns_request_insert(struct request *req, struct request **head);
374 static void evdns_request_remove(struct request *req, struct request **head);
375 static void nameserver_ready_callback(evutil_socket_t fd, short events, void *arg);
376 static int evdns_transmit(struct evdns_base *base);
377 static int evdns_request_transmit(struct request *req);
378 static void nameserver_send_probe(struct nameserver *const ns);
379 static void search_request_finished(struct evdns_request *const);
380 static int search_try_next(struct evdns_request *const req);
381 static struct request *search_request_new(struct evdns_base *base, struct evdns_request *handle, int type, const char *const name, int flags, evdns_callback_type user_callback, void *user_arg);
382 static void evdns_requests_pump_waiting_queue(struct evdns_base *base);
383 static u16 transaction_id_pick(struct evdns_base *base);
384 static struct request *request_new(struct evdns_base *base, struct evdns_request *handle, int type, const char *name, int flags, evdns_callback_type callback, void *ptr);
385 static void request_submit(struct request *const req);
387 static int server_request_free(struct server_request *req);
388 static void server_request_free_answers(struct server_request *req);
389 static void server_port_free(struct evdns_server_port *port);
390 static void server_port_ready_callback(evutil_socket_t fd, short events, void *arg);
391 static int evdns_base_resolv_conf_parse_impl(struct evdns_base *base, int flags, const char *const filename);
392 static int evdns_base_set_option_impl(struct evdns_base *base,
393 const char *option, const char *val, int flags);
394 static void evdns_base_free_and_unlock(struct evdns_base *base, int fail_requests);
396 static int strtoint(const char *const str);
398 #ifdef _EVENT_DISABLE_THREAD_SUPPORT
399 #define EVDNS_LOCK(base) _EVUTIL_NIL_STMT
400 #define EVDNS_UNLOCK(base) _EVUTIL_NIL_STMT
401 #define ASSERT_LOCKED(base) _EVUTIL_NIL_STMT
403 #define EVDNS_LOCK(base) \
404 EVLOCK_LOCK((base)->lock, 0)
405 #define EVDNS_UNLOCK(base) \
406 EVLOCK_UNLOCK((base)->lock, 0)
407 #define ASSERT_LOCKED(base) \
408 EVLOCK_ASSERT_LOCKED((base)->lock)
412 default_evdns_log_fn(int warning, const char *buf)
414 if (warning == EVDNS_LOG_WARN)
415 event_warnx("[evdns] %s", buf);
416 else if (warning == EVDNS_LOG_MSG)
417 event_msgx("[evdns] %s", buf);
419 event_debug(("[evdns] %s", buf));
422 static evdns_debug_log_fn_type evdns_log_fn = NULL;
425 evdns_set_log_fn(evdns_debug_log_fn_type fn)
431 #define EVDNS_LOG_CHECK __attribute__ ((format(printf, 2, 3)))
433 #define EVDNS_LOG_CHECK
436 static void _evdns_log(int warn, const char *fmt, ...) EVDNS_LOG_CHECK;
438 _evdns_log(int warn, const char *fmt, ...)
445 evutil_vsnprintf(buf, sizeof(buf), fmt, args);
448 if (warn == EVDNS_LOG_MSG)
449 warn = EVDNS_LOG_WARN;
450 evdns_log_fn(warn, buf);
452 default_evdns_log_fn(warn, buf);
457 #define log _evdns_log
459 /* This walks the list of inflight requests to find the */
460 /* one with a matching transaction id. Returns NULL on */
462 static struct request *
463 request_find_from_trans_id(struct evdns_base *base, u16 trans_id) {
464 struct request *req = REQ_HEAD(base, trans_id);
465 struct request *const started_at = req;
471 if (req->trans_id == trans_id) return req;
473 } while (req != started_at);
479 /* a libevent callback function which is called when a nameserver */
480 /* has gone down and we want to test if it has came back to life yet */
482 nameserver_prod_callback(evutil_socket_t fd, short events, void *arg) {
483 struct nameserver *const ns = (struct nameserver *) arg;
487 EVDNS_LOCK(ns->base);
488 nameserver_send_probe(ns);
489 EVDNS_UNLOCK(ns->base);
492 /* a libevent callback which is called when a nameserver probe (to see if */
493 /* it has come back to life) times out. We increment the count of failed_times */
494 /* and wait longer to send the next probe packet. */
496 nameserver_probe_failed(struct nameserver *const ns) {
497 struct timeval timeout;
500 ASSERT_LOCKED(ns->base);
501 (void) evtimer_del(&ns->timeout_event);
502 if (ns->state == 1) {
503 /* This can happen if the nameserver acts in a way which makes us mark */
504 /* it as bad and then starts sending good replies. */
508 #define MAX_PROBE_TIMEOUT 3600
509 #define TIMEOUT_BACKOFF_FACTOR 3
511 memcpy(&timeout, &ns->base->global_nameserver_probe_initial_timeout,
512 sizeof(struct timeval));
513 for (i=ns->failed_times; i > 0 && timeout.tv_sec < MAX_PROBE_TIMEOUT; --i) {
514 timeout.tv_sec *= TIMEOUT_BACKOFF_FACTOR;
515 timeout.tv_usec *= TIMEOUT_BACKOFF_FACTOR;
516 if (timeout.tv_usec > 1000000) {
517 timeout.tv_sec += timeout.tv_usec / 1000000;
518 timeout.tv_usec %= 1000000;
521 if (timeout.tv_sec > MAX_PROBE_TIMEOUT) {
522 timeout.tv_sec = MAX_PROBE_TIMEOUT;
528 if (evtimer_add(&ns->timeout_event, &timeout) < 0) {
531 "Error from libevent when adding timer event for %s",
532 evutil_format_sockaddr_port(
533 (struct sockaddr *)&ns->address,
534 addrbuf, sizeof(addrbuf)));
538 /* called when a nameserver has been deemed to have failed. For example, too */
539 /* many packets have timed out etc */
541 nameserver_failed(struct nameserver *const ns, const char *msg) {
542 struct request *req, *started_at;
543 struct evdns_base *base = ns->base;
548 /* if this nameserver has already been marked as failed */
549 /* then don't do anything */
550 if (!ns->state) return;
552 log(EVDNS_LOG_MSG, "Nameserver %s has failed: %s",
553 evutil_format_sockaddr_port(
554 (struct sockaddr *)&ns->address,
555 addrbuf, sizeof(addrbuf)),
558 base->global_good_nameservers--;
559 EVUTIL_ASSERT(base->global_good_nameservers >= 0);
560 if (base->global_good_nameservers == 0) {
561 log(EVDNS_LOG_MSG, "All nameservers have failed");
565 ns->failed_times = 1;
567 if (evtimer_add(&ns->timeout_event,
568 &base->global_nameserver_probe_initial_timeout) < 0) {
570 "Error from libevent when adding timer event for %s",
571 evutil_format_sockaddr_port(
572 (struct sockaddr *)&ns->address,
573 addrbuf, sizeof(addrbuf)));
577 /* walk the list of inflight requests to see if any can be reassigned to */
578 /* a different server. Requests in the waiting queue don't have a */
579 /* nameserver assigned yet */
581 /* if we don't have *any* good nameservers then there's no point */
582 /* trying to reassign requests to one */
583 if (!base->global_good_nameservers) return;
585 for (i = 0; i < base->n_req_heads; ++i) {
586 req = started_at = base->req_heads[i];
589 if (req->tx_count == 0 && req->ns == ns) {
590 /* still waiting to go out, can be moved */
591 /* to another server */
592 req->ns = nameserver_pick(base);
595 } while (req != started_at);
601 nameserver_up(struct nameserver *const ns)
604 ASSERT_LOCKED(ns->base);
605 if (ns->state) return;
606 log(EVDNS_LOG_MSG, "Nameserver %s is back up",
607 evutil_format_sockaddr_port(
608 (struct sockaddr *)&ns->address,
609 addrbuf, sizeof(addrbuf)));
610 evtimer_del(&ns->timeout_event);
611 if (ns->probe_request) {
612 evdns_cancel_request(ns->base, ns->probe_request);
613 ns->probe_request = NULL;
616 ns->failed_times = 0;
618 ns->base->global_good_nameservers++;
622 request_trans_id_set(struct request *const req, const u16 trans_id) {
623 req->trans_id = trans_id;
624 *((u16 *) req->request) = htons(trans_id);
627 /* Called to remove a request from a list and dealloc it. */
628 /* head is a pointer to the head of the list it should be */
629 /* removed from or NULL if the request isn't in a list. */
630 /* when free_handle is one, free the handle as well. */
632 request_finished(struct request *const req, struct request **head, int free_handle) {
633 struct evdns_base *base = req->base;
634 int was_inflight = (head != &base->req_waiting_head);
636 ASSERT_VALID_REQUEST(req);
639 evdns_request_remove(req, head);
641 log(EVDNS_LOG_DEBUG, "Removing timeout for request %p", req);
643 evtimer_del(&req->timeout_event);
644 base->global_requests_inflight--;
646 base->global_requests_waiting--;
649 if (!req->request_appended) {
650 /* need to free the request data on it's own */
651 mm_free(req->request);
653 /* the request data is appended onto the header */
654 /* so everything gets free()ed when we: */
658 EVUTIL_ASSERT(req->handle->current_req == req);
661 search_request_finished(req->handle);
662 req->handle->current_req = NULL;
663 if (! req->handle->pending_cb) {
664 /* If we're planning to run the callback,
665 * don't free the handle until later. */
666 mm_free(req->handle);
668 req->handle = NULL; /* If we have a bug, let's crash
671 req->handle->current_req = NULL;
677 evdns_requests_pump_waiting_queue(base);
681 /* This is called when a server returns a funny error code. */
682 /* We try the request again with another server. */
686 /* 1 failed/reissue is pointless */
688 request_reissue(struct request *req) {
689 const struct nameserver *const last_ns = req->ns;
690 ASSERT_LOCKED(req->base);
691 ASSERT_VALID_REQUEST(req);
692 /* the last nameserver should have been marked as failing */
693 /* by the caller of this function, therefore pick will try */
694 /* not to return it */
695 req->ns = nameserver_pick(req->base);
696 if (req->ns == last_ns) {
697 /* ... but pick did return it */
698 /* not a lot of point in trying again with the */
703 req->reissue_count++;
705 req->transmit_me = 1;
710 /* this function looks for space on the inflight queue and promotes */
711 /* requests from the waiting queue if it can. */
713 evdns_requests_pump_waiting_queue(struct evdns_base *base) {
715 while (base->global_requests_inflight < base->global_max_requests_inflight &&
716 base->global_requests_waiting) {
718 /* move a request from the waiting queue to the inflight queue */
719 EVUTIL_ASSERT(base->req_waiting_head);
720 req = base->req_waiting_head;
721 evdns_request_remove(req, &base->req_waiting_head);
723 base->global_requests_waiting--;
724 base->global_requests_inflight++;
726 req->ns = nameserver_pick(base);
727 request_trans_id_set(req, transaction_id_pick(base));
729 evdns_request_insert(req, &REQ_HEAD(base, req->trans_id));
730 evdns_request_transmit(req);
731 evdns_transmit(base);
735 /* TODO(nickm) document */
736 struct deferred_reply_callback {
737 struct deferred_cb deferred;
738 struct evdns_request *handle;
743 evdns_callback_type user_callback;
748 reply_run_callback(struct deferred_cb *d, void *user_pointer)
750 struct deferred_reply_callback *cb =
751 EVUTIL_UPCAST(d, struct deferred_reply_callback, deferred);
753 switch (cb->request_type) {
756 cb->user_callback(DNS_ERR_NONE, DNS_IPv4_A,
757 cb->reply.data.a.addrcount, cb->ttl,
758 cb->reply.data.a.addresses,
761 cb->user_callback(cb->err, 0, 0, 0, NULL, user_pointer);
764 if (cb->have_reply) {
765 char *name = cb->reply.data.ptr.name;
766 cb->user_callback(DNS_ERR_NONE, DNS_PTR, 1, cb->ttl,
767 &name, user_pointer);
769 cb->user_callback(cb->err, 0, 0, 0, NULL, user_pointer);
774 cb->user_callback(DNS_ERR_NONE, DNS_IPv6_AAAA,
775 cb->reply.data.aaaa.addrcount, cb->ttl,
776 cb->reply.data.aaaa.addresses,
779 cb->user_callback(cb->err, 0, 0, 0, NULL, user_pointer);
785 if (cb->handle && cb->handle->pending_cb) {
793 reply_schedule_callback(struct request *const req, u32 ttl, u32 err, struct reply *reply)
795 struct deferred_reply_callback *d = mm_calloc(1, sizeof(*d));
797 ASSERT_LOCKED(req->base);
799 d->request_type = req->request_type;
800 d->user_callback = req->user_callback;
805 memcpy(&d->reply, reply, sizeof(struct reply));
809 req->handle->pending_cb = 1;
810 d->handle = req->handle;
813 event_deferred_cb_init(&d->deferred, reply_run_callback,
815 event_deferred_cb_schedule(
816 event_base_get_deferred_cb_queue(req->base->event_base),
820 /* this processes a parsed reply packet */
822 reply_handle(struct request *const req, u16 flags, u32 ttl, struct reply *reply) {
825 static const int error_codes[] = {
826 DNS_ERR_FORMAT, DNS_ERR_SERVERFAILED, DNS_ERR_NOTEXIST,
827 DNS_ERR_NOTIMPL, DNS_ERR_REFUSED
830 ASSERT_LOCKED(req->base);
831 ASSERT_VALID_REQUEST(req);
833 if (flags & 0x020f || !reply || !reply->have_answer) {
834 /* there was an error */
835 if (flags & 0x0200) {
836 error = DNS_ERR_TRUNCATED;
838 u16 error_code = (flags & 0x000f) - 1;
839 if (error_code > 4) {
840 error = DNS_ERR_UNKNOWN;
842 error = error_codes[error_code];
847 case DNS_ERR_NOTIMPL:
848 case DNS_ERR_REFUSED:
849 /* we regard these errors as marking a bad nameserver */
850 if (req->reissue_count < req->base->global_max_reissues) {
852 evutil_snprintf(msg, sizeof(msg), "Bad response %d (%s)",
853 error, evdns_err_to_string(error));
854 nameserver_failed(req->ns, msg);
855 if (!request_reissue(req)) return;
858 case DNS_ERR_SERVERFAILED:
859 /* rcode 2 (servfailed) sometimes means "we
860 * are broken" and sometimes (with some binds)
861 * means "that request was very confusing."
862 * Treat this as a timeout, not a failure.
864 log(EVDNS_LOG_DEBUG, "Got a SERVERFAILED from nameserver"
865 "at %s; will allow the request to time out.",
866 evutil_format_sockaddr_port(
867 (struct sockaddr *)&req->ns->address,
868 addrbuf, sizeof(addrbuf)));
871 /* we got a good reply from the nameserver */
872 nameserver_up(req->ns);
875 if (req->handle->search_state &&
876 req->request_type != TYPE_PTR) {
877 /* if we have a list of domains to search in,
878 * try the next one */
879 if (!search_try_next(req->handle)) {
880 /* a new request was issued so this
881 * request is finished and */
882 /* the user callback will be made when
883 * that request (or a */
884 /* child of it) finishes. */
889 /* all else failed. Pass the failure up */
890 reply_schedule_callback(req, 0, error, NULL);
891 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1);
893 /* all ok, tell the user */
894 reply_schedule_callback(req, ttl, 0, reply);
895 if (req->handle == req->ns->probe_request)
896 req->ns->probe_request = NULL; /* Avoid double-free */
897 nameserver_up(req->ns);
898 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1);
903 name_parse(u8 *packet, int length, int *idx, char *name_out, int name_out_len) {
907 #define GET32(x) do { if (j + 4 > length) goto err; memcpy(&_t32, packet + j, 4); j += 4; x = ntohl(_t32); } while (0)
908 #define GET16(x) do { if (j + 2 > length) goto err; memcpy(&_t, packet + j, 2); j += 2; x = ntohs(_t); } while (0)
909 #define GET8(x) do { if (j >= length) goto err; x = packet[j++]; } while (0)
912 const char *const end = name_out + name_out_len;
914 /* Normally, names are a series of length prefixed strings terminated */
915 /* with a length of 0 (the lengths are u8's < 63). */
916 /* However, the length can start with a pair of 1 bits and that */
917 /* means that the next 14 bits are a pointer within the current */
922 if (j >= length) return -1;
924 if (!label_len) break;
925 if (label_len & 0xc0) {
928 if (name_end < 0) name_end = j;
929 j = (((int)label_len & 0x3f) << 8) + ptr_low;
930 /* Make sure that the target offset is in-bounds. */
931 if (j < 0 || j >= length) return -1;
932 /* If we've jumped more times than there are characters in the
933 * message, we must have a loop. */
934 if (++ptr_count > length) return -1;
937 if (label_len > 63) return -1;
938 if (cp != name_out) {
939 if (cp + 1 >= end) return -1;
942 if (cp + label_len >= end) return -1;
943 memcpy(cp, packet + j, label_len);
947 if (cp >= end) return -1;
958 /* parses a raw request from a nameserver */
960 reply_parse(struct evdns_base *base, u8 *packet, int length) {
961 int j = 0, k = 0; /* index into packet */
962 u16 _t; /* used by the macros */
963 u32 _t32; /* used by the macros */
964 char tmp_name[256], cmp_name[256]; /* used by the macros */
965 int name_matches = 0;
967 u16 trans_id, questions, answers, authority, additional, datalength;
969 u32 ttl, ttl_r = 0xffffffff;
971 struct request *req = NULL;
982 (void) authority; /* suppress "unused variable" warnings. */
983 (void) additional; /* suppress "unused variable" warnings. */
985 req = request_find_from_trans_id(base, trans_id);
987 EVUTIL_ASSERT(req->base == base);
989 memset(&reply, 0, sizeof(reply));
991 /* If it's not an answer, it doesn't correspond to any request. */
992 if (!(flags & 0x8000)) return -1; /* must be an answer */
993 if (flags & 0x020f) {
994 /* there was an error */
997 /* if (!answers) return; */ /* must have an answer of some form */
999 /* This macro skips a name in the DNS reply. */
1001 do { tmp_name[0] = '\0'; \
1002 if (name_parse(packet, length, &j, tmp_name, \
1003 sizeof(tmp_name))<0) \
1007 do { tmp_name[0] = '\0'; \
1008 cmp_name[0] = '\0'; \
1010 if (name_parse(packet, length, &j, tmp_name, \
1011 sizeof(tmp_name))<0) \
1013 if (name_parse(req->request, req->request_len, &k, \
1014 cmp_name, sizeof(cmp_name))<0) \
1016 if (base->global_randomize_case) { \
1017 if (strcmp(tmp_name, cmp_name) == 0) \
1020 if (evutil_ascii_strcasecmp(tmp_name, cmp_name) == 0) \
1025 reply.type = req->request_type;
1027 /* skip over each question in the reply */
1028 for (i = 0; i < questions; ++i) {
1029 /* the question looks like
1030 * <label:name><u16:type><u16:class>
1034 if (j >= length) goto err;
1040 /* now we have the answer section which looks like
1041 * <label:name><u16:type><u16:class><u32:ttl><u16:len><data...>
1044 for (i = 0; i < answers; ++i) {
1053 if (type == TYPE_A && class == CLASS_INET) {
1054 int addrcount, addrtocopy;
1055 if (req->request_type != TYPE_A) {
1056 j += datalength; continue;
1058 if ((datalength & 3) != 0) /* not an even number of As. */
1060 addrcount = datalength >> 2;
1061 addrtocopy = MIN(MAX_V4_ADDRS - reply.data.a.addrcount, (unsigned)addrcount);
1063 ttl_r = MIN(ttl_r, ttl);
1064 /* we only bother with the first four addresses. */
1065 if (j + 4*addrtocopy > length) goto err;
1066 memcpy(&reply.data.a.addresses[reply.data.a.addrcount],
1067 packet + j, 4*addrtocopy);
1069 reply.data.a.addrcount += addrtocopy;
1070 reply.have_answer = 1;
1071 if (reply.data.a.addrcount == MAX_V4_ADDRS) break;
1072 } else if (type == TYPE_PTR && class == CLASS_INET) {
1073 if (req->request_type != TYPE_PTR) {
1074 j += datalength; continue;
1076 if (name_parse(packet, length, &j, reply.data.ptr.name,
1077 sizeof(reply.data.ptr.name))<0)
1079 ttl_r = MIN(ttl_r, ttl);
1080 reply.have_answer = 1;
1082 } else if (type == TYPE_CNAME) {
1083 char cname[HOST_NAME_MAX];
1084 if (!req->put_cname_in_ptr || *req->put_cname_in_ptr) {
1085 j += datalength; continue;
1087 if (name_parse(packet, length, &j, cname,
1090 *req->put_cname_in_ptr = mm_strdup(cname);
1091 } else if (type == TYPE_AAAA && class == CLASS_INET) {
1092 int addrcount, addrtocopy;
1093 if (req->request_type != TYPE_AAAA) {
1094 j += datalength; continue;
1096 if ((datalength & 15) != 0) /* not an even number of AAAAs. */
1098 addrcount = datalength >> 4; /* each address is 16 bytes long */
1099 addrtocopy = MIN(MAX_V6_ADDRS - reply.data.aaaa.addrcount, (unsigned)addrcount);
1100 ttl_r = MIN(ttl_r, ttl);
1102 /* we only bother with the first four addresses. */
1103 if (j + 16*addrtocopy > length) goto err;
1104 memcpy(&reply.data.aaaa.addresses[reply.data.aaaa.addrcount],
1105 packet + j, 16*addrtocopy);
1106 reply.data.aaaa.addrcount += addrtocopy;
1108 reply.have_answer = 1;
1109 if (reply.data.aaaa.addrcount == MAX_V6_ADDRS) break;
1111 /* skip over any other type of resource */
1116 reply_handle(req, flags, ttl_r, &reply);
1120 reply_handle(req, flags, 0, NULL);
1124 /* Parse a raw request (packet,length) sent to a nameserver port (port) from */
1125 /* a DNS client (addr,addrlen), and if it's well-formed, call the corresponding */
1128 request_parse(u8 *packet, int length, struct evdns_server_port *port, struct sockaddr *addr, ev_socklen_t addrlen)
1130 int j = 0; /* index into packet */
1131 u16 _t; /* used by the macros */
1132 char tmp_name[256]; /* used by the macros */
1135 u16 trans_id, flags, questions, answers, authority, additional;
1136 struct server_request *server_req = NULL;
1138 ASSERT_LOCKED(port);
1140 /* Get the header fields */
1148 if (flags & 0x8000) return -1; /* Must not be an answer. */
1149 flags &= 0x0110; /* Only RD and CD get preserved. */
1151 server_req = mm_malloc(sizeof(struct server_request));
1152 if (server_req == NULL) return -1;
1153 memset(server_req, 0, sizeof(struct server_request));
1155 server_req->trans_id = trans_id;
1156 memcpy(&server_req->addr, addr, addrlen);
1157 server_req->addrlen = addrlen;
1159 server_req->base.flags = flags;
1160 server_req->base.nquestions = 0;
1161 server_req->base.questions = mm_calloc(sizeof(struct evdns_server_question *), questions);
1162 if (server_req->base.questions == NULL)
1165 for (i = 0; i < questions; ++i) {
1167 struct evdns_server_question *q;
1169 if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0)
1173 namelen = (int)strlen(tmp_name);
1174 q = mm_malloc(sizeof(struct evdns_server_question) + namelen);
1178 q->dns_question_class = class;
1179 memcpy(q->name, tmp_name, namelen+1);
1180 server_req->base.questions[server_req->base.nquestions++] = q;
1183 /* Ignore answers, authority, and additional. */
1185 server_req->port = port;
1188 /* Only standard queries are supported. */
1189 if (flags & 0x7800) {
1190 evdns_server_request_respond(&(server_req->base), DNS_ERR_NOTIMPL);
1194 port->user_callback(&(server_req->base), port->user_data);
1199 if (server_req->base.questions) {
1200 for (i = 0; i < server_req->base.nquestions; ++i)
1201 mm_free(server_req->base.questions[i]);
1202 mm_free(server_req->base.questions);
1204 mm_free(server_req);
1216 evdns_set_transaction_id_fn(ev_uint16_t (*fn)(void))
1221 evdns_set_random_bytes_fn(void (*fn)(char *, size_t))
1225 /* Try to choose a strong transaction id which isn't already in flight */
1227 transaction_id_pick(struct evdns_base *base) {
1228 ASSERT_LOCKED(base);
1231 evutil_secure_rng_get_bytes(&trans_id, sizeof(trans_id));
1233 if (trans_id == 0xffff) continue;
1234 /* now check to see if that id is already inflight */
1235 if (request_find_from_trans_id(base, trans_id) == NULL)
1240 /* choose a namesever to use. This function will try to ignore */
1241 /* nameservers which we think are down and load balance across the rest */
1242 /* by updating the server_head global each time. */
1243 static struct nameserver *
1244 nameserver_pick(struct evdns_base *base) {
1245 struct nameserver *started_at = base->server_head, *picked;
1246 ASSERT_LOCKED(base);
1247 if (!base->server_head) return NULL;
1249 /* if we don't have any good nameservers then there's no */
1250 /* point in trying to find one. */
1251 if (!base->global_good_nameservers) {
1252 base->server_head = base->server_head->next;
1253 return base->server_head;
1256 /* remember that nameservers are in a circular list */
1258 if (base->server_head->state) {
1259 /* we think this server is currently good */
1260 picked = base->server_head;
1261 base->server_head = base->server_head->next;
1265 base->server_head = base->server_head->next;
1266 if (base->server_head == started_at) {
1267 /* all the nameservers seem to be down */
1268 /* so we just return this one and hope for the */
1270 EVUTIL_ASSERT(base->global_good_nameservers == 0);
1271 picked = base->server_head;
1272 base->server_head = base->server_head->next;
1278 /* this is called when a namesever socket is ready for reading */
1280 nameserver_read(struct nameserver *ns) {
1281 struct sockaddr_storage ss;
1282 ev_socklen_t addrlen = sizeof(ss);
1285 ASSERT_LOCKED(ns->base);
1288 const int r = recvfrom(ns->socket, (void*)packet,
1290 (struct sockaddr*)&ss, &addrlen);
1292 int err = evutil_socket_geterror(ns->socket);
1293 if (EVUTIL_ERR_RW_RETRIABLE(err))
1295 nameserver_failed(ns,
1296 evutil_socket_error_to_string(err));
1299 if (evutil_sockaddr_cmp((struct sockaddr*)&ss,
1300 (struct sockaddr*)&ns->address, 0)) {
1301 log(EVDNS_LOG_WARN, "Address mismatch on received "
1302 "DNS packet. Apparent source was %s",
1303 evutil_format_sockaddr_port(
1304 (struct sockaddr *)&ss,
1305 addrbuf, sizeof(addrbuf)));
1310 reply_parse(ns->base, packet, r);
1314 /* Read a packet from a DNS client on a server port s, parse it, and */
1315 /* act accordingly. */
1317 server_port_read(struct evdns_server_port *s) {
1319 struct sockaddr_storage addr;
1320 ev_socklen_t addrlen;
1325 addrlen = sizeof(struct sockaddr_storage);
1326 r = recvfrom(s->socket, (void*)packet, sizeof(packet), 0,
1327 (struct sockaddr*) &addr, &addrlen);
1329 int err = evutil_socket_geterror(s->socket);
1330 if (EVUTIL_ERR_RW_RETRIABLE(err))
1333 "Error %s (%d) while reading request.",
1334 evutil_socket_error_to_string(err), err);
1337 request_parse(packet, r, s, (struct sockaddr*) &addr, addrlen);
1341 /* Try to write all pending replies on a given DNS server port. */
1343 server_port_flush(struct evdns_server_port *port)
1345 struct server_request *req = port->pending_replies;
1346 ASSERT_LOCKED(port);
1348 int r = sendto(port->socket, req->response, (int)req->response_len, 0,
1349 (struct sockaddr*) &req->addr, (ev_socklen_t)req->addrlen);
1351 int err = evutil_socket_geterror(port->socket);
1352 if (EVUTIL_ERR_RW_RETRIABLE(err))
1354 log(EVDNS_LOG_WARN, "Error %s (%d) while writing response to port; dropping", evutil_socket_error_to_string(err), err);
1356 if (server_request_free(req)) {
1357 /* we released the last reference to req->port. */
1360 EVUTIL_ASSERT(req != port->pending_replies);
1361 req = port->pending_replies;
1365 /* We have no more pending requests; stop listening for 'writeable' events. */
1366 (void) event_del(&port->event);
1367 event_assign(&port->event, port->event_base,
1368 port->socket, EV_READ | EV_PERSIST,
1369 server_port_ready_callback, port);
1371 if (event_add(&port->event, NULL) < 0) {
1372 log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server.");
1377 /* set if we are waiting for the ability to write to this server. */
1378 /* if waiting is true then we ask libevent for EV_WRITE events, otherwise */
1379 /* we stop these events. */
1381 nameserver_write_waiting(struct nameserver *ns, char waiting) {
1382 ASSERT_LOCKED(ns->base);
1383 if (ns->write_waiting == waiting) return;
1385 ns->write_waiting = waiting;
1386 (void) event_del(&ns->event);
1387 event_assign(&ns->event, ns->base->event_base,
1388 ns->socket, EV_READ | (waiting ? EV_WRITE : 0) | EV_PERSIST,
1389 nameserver_ready_callback, ns);
1390 if (event_add(&ns->event, NULL) < 0) {
1392 log(EVDNS_LOG_WARN, "Error from libevent when adding event for %s",
1393 evutil_format_sockaddr_port(
1394 (struct sockaddr *)&ns->address,
1395 addrbuf, sizeof(addrbuf)));
1400 /* a callback function. Called by libevent when the kernel says that */
1401 /* a nameserver socket is ready for writing or reading */
1403 nameserver_ready_callback(evutil_socket_t fd, short events, void *arg) {
1404 struct nameserver *ns = (struct nameserver *) arg;
1407 EVDNS_LOCK(ns->base);
1408 if (events & EV_WRITE) {
1410 if (!evdns_transmit(ns->base)) {
1411 nameserver_write_waiting(ns, 0);
1414 if (events & EV_READ) {
1415 nameserver_read(ns);
1417 EVDNS_UNLOCK(ns->base);
1420 /* a callback function. Called by libevent when the kernel says that */
1421 /* a server socket is ready for writing or reading. */
1423 server_port_ready_callback(evutil_socket_t fd, short events, void *arg) {
1424 struct evdns_server_port *port = (struct evdns_server_port *) arg;
1428 if (events & EV_WRITE) {
1430 server_port_flush(port);
1432 if (events & EV_READ) {
1433 server_port_read(port);
1438 /* This is an inefficient representation; only use it via the dnslabel_table_*
1439 * functions, so that is can be safely replaced with something smarter later. */
1440 #define MAX_LABELS 128
1441 /* Structures used to implement name compression */
1442 struct dnslabel_entry { char *v; off_t pos; };
1443 struct dnslabel_table {
1444 int n_labels; /* number of current entries */
1445 /* map from name to position in message */
1446 struct dnslabel_entry labels[MAX_LABELS];
1449 /* Initialize dnslabel_table. */
1451 dnslabel_table_init(struct dnslabel_table *table)
1453 table->n_labels = 0;
1456 /* Free all storage held by table, but not the table itself. */
1458 dnslabel_clear(struct dnslabel_table *table)
1461 for (i = 0; i < table->n_labels; ++i)
1462 mm_free(table->labels[i].v);
1463 table->n_labels = 0;
1466 /* return the position of the label in the current message, or -1 if the label */
1467 /* hasn't been used yet. */
1469 dnslabel_table_get_pos(const struct dnslabel_table *table, const char *label)
1472 for (i = 0; i < table->n_labels; ++i) {
1473 if (!strcmp(label, table->labels[i].v))
1474 return table->labels[i].pos;
1479 /* remember that we've used the label at position pos */
1481 dnslabel_table_add(struct dnslabel_table *table, const char *label, off_t pos)
1485 if (table->n_labels == MAX_LABELS)
1487 v = mm_strdup(label);
1490 p = table->n_labels++;
1491 table->labels[p].v = v;
1492 table->labels[p].pos = pos;
1497 /* Converts a string to a length-prefixed set of DNS labels, starting */
1498 /* at buf[j]. name and buf must not overlap. name_len should be the length */
1499 /* of name. table is optional, and is used for compression. */
1501 /* Input: abc.def */
1502 /* Output: <3>abc<3>def<0> */
1504 /* Returns the first index after the encoded name, or negative on error. */
1505 /* -1 label was > 63 bytes */
1506 /* -2 name too long to fit in buffer. */
1509 dnsname_to_labels(u8 *const buf, size_t buf_len, off_t j,
1510 const char *name, const size_t name_len,
1511 struct dnslabel_table *table) {
1512 const char *end = name + name_len;
1516 #define APPEND16(x) do { \
1517 if (j + 2 > (off_t)buf_len) \
1520 memcpy(buf + j, &_t, 2); \
1523 #define APPEND32(x) do { \
1524 if (j + 4 > (off_t)buf_len) \
1527 memcpy(buf + j, &_t32, 4); \
1531 if (name_len > 255) return -2;
1534 const char *const start = name;
1535 if (table && (ref = dnslabel_table_get_pos(table, name)) >= 0) {
1536 APPEND16(ref | 0xc000);
1539 name = strchr(name, '.');
1541 const size_t label_len = end - start;
1542 if (label_len > 63) return -1;
1543 if ((size_t)(j+label_len+1) > buf_len) return -2;
1544 if (table) dnslabel_table_add(table, start, j);
1545 buf[j++] = (ev_uint8_t)label_len;
1547 memcpy(buf + j, start, label_len);
1548 j += (int) label_len;
1551 /* append length of the label. */
1552 const size_t label_len = name - start;
1553 if (label_len > 63) return -1;
1554 if ((size_t)(j+label_len+1) > buf_len) return -2;
1555 if (table) dnslabel_table_add(table, start, j);
1556 buf[j++] = (ev_uint8_t)label_len;
1558 memcpy(buf + j, start, label_len);
1559 j += (int) label_len;
1560 /* hop over the '.' */
1565 /* the labels must be terminated by a 0. */
1566 /* It's possible that the name ended in a . */
1567 /* in which case the zero is already there */
1568 if (!j || buf[j-1]) buf[j++] = 0;
1574 /* Finds the length of a dns request for a DNS name of the given */
1575 /* length. The actual request may be smaller than the value returned */
1578 evdns_request_len(const size_t name_len) {
1579 return 96 + /* length of the DNS standard header */
1581 4; /* space for the resource type */
1584 /* build a dns request packet into buf. buf should be at least as long */
1585 /* as evdns_request_len told you it should be. */
1587 /* Returns the amount of space used. Negative on error. */
1589 evdns_request_data_build(const char *const name, const size_t name_len,
1590 const u16 trans_id, const u16 type, const u16 class,
1591 u8 *const buf, size_t buf_len) {
1592 off_t j = 0; /* current offset into buf */
1593 u16 _t; /* used by the macros */
1596 APPEND16(0x0100); /* standard query, recusion needed */
1597 APPEND16(1); /* one question */
1598 APPEND16(0); /* no answers */
1599 APPEND16(0); /* no authority */
1600 APPEND16(0); /* no additional */
1602 j = dnsname_to_labels(buf, buf_len, j, name, name_len, NULL);
1615 /* exported function */
1616 struct evdns_server_port *
1617 evdns_add_server_port_with_base(struct event_base *base, evutil_socket_t socket, int flags, evdns_request_callback_fn_type cb, void *user_data)
1619 struct evdns_server_port *port;
1621 return NULL; /* flags not yet implemented */
1622 if (!(port = mm_malloc(sizeof(struct evdns_server_port))))
1624 memset(port, 0, sizeof(struct evdns_server_port));
1627 port->socket = socket;
1631 port->user_callback = cb;
1632 port->user_data = user_data;
1633 port->pending_replies = NULL;
1634 port->event_base = base;
1636 event_assign(&port->event, port->event_base,
1637 port->socket, EV_READ | EV_PERSIST,
1638 server_port_ready_callback, port);
1639 if (event_add(&port->event, NULL) < 0) {
1643 EVTHREAD_ALLOC_LOCK(port->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
1647 struct evdns_server_port *
1648 evdns_add_server_port(evutil_socket_t socket, int flags, evdns_request_callback_fn_type cb, void *user_data)
1650 return evdns_add_server_port_with_base(NULL, socket, flags, cb, user_data);
1653 /* exported function */
1655 evdns_close_server_port(struct evdns_server_port *port)
1658 if (--port->refcnt == 0) {
1660 server_port_free(port);
1666 /* exported function */
1668 evdns_server_request_add_reply(struct evdns_server_request *_req, int section, const char *name, int type, int class, int ttl, int datalen, int is_name, const char *data)
1670 struct server_request *req = TO_SERVER_REQUEST(_req);
1671 struct server_reply_item **itemp, *item;
1675 EVDNS_LOCK(req->port);
1676 if (req->response) /* have we already answered? */
1680 case EVDNS_ANSWER_SECTION:
1681 itemp = &req->answer;
1682 countp = &req->n_answer;
1684 case EVDNS_AUTHORITY_SECTION:
1685 itemp = &req->authority;
1686 countp = &req->n_authority;
1688 case EVDNS_ADDITIONAL_SECTION:
1689 itemp = &req->additional;
1690 countp = &req->n_additional;
1696 itemp = &((*itemp)->next);
1698 item = mm_malloc(sizeof(struct server_reply_item));
1702 if (!(item->name = mm_strdup(name))) {
1707 item->dns_question_class = class;
1709 item->is_name = is_name != 0;
1713 if (item->is_name) {
1714 if (!(item->data = mm_strdup(data))) {
1715 mm_free(item->name);
1719 item->datalen = (u16)-1;
1721 if (!(item->data = mm_malloc(datalen))) {
1722 mm_free(item->name);
1726 item->datalen = datalen;
1727 memcpy(item->data, data, datalen);
1735 EVDNS_UNLOCK(req->port);
1739 /* exported function */
1741 evdns_server_request_add_a_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl)
1743 return evdns_server_request_add_reply(
1744 req, EVDNS_ANSWER_SECTION, name, TYPE_A, CLASS_INET,
1745 ttl, n*4, 0, addrs);
1748 /* exported function */
1750 evdns_server_request_add_aaaa_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl)
1752 return evdns_server_request_add_reply(
1753 req, EVDNS_ANSWER_SECTION, name, TYPE_AAAA, CLASS_INET,
1754 ttl, n*16, 0, addrs);
1757 /* exported function */
1759 evdns_server_request_add_ptr_reply(struct evdns_server_request *req, struct in_addr *in, const char *inaddr_name, const char *hostname, int ttl)
1763 if (in && inaddr_name)
1765 else if (!in && !inaddr_name)
1768 a = ntohl(in->s_addr);
1769 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa",
1770 (int)(u8)((a )&0xff),
1771 (int)(u8)((a>>8 )&0xff),
1772 (int)(u8)((a>>16)&0xff),
1773 (int)(u8)((a>>24)&0xff));
1776 return evdns_server_request_add_reply(
1777 req, EVDNS_ANSWER_SECTION, inaddr_name, TYPE_PTR, CLASS_INET,
1778 ttl, -1, 1, hostname);
1781 /* exported function */
1783 evdns_server_request_add_cname_reply(struct evdns_server_request *req, const char *name, const char *cname, int ttl)
1785 return evdns_server_request_add_reply(
1786 req, EVDNS_ANSWER_SECTION, name, TYPE_CNAME, CLASS_INET,
1790 /* exported function */
1792 evdns_server_request_set_flags(struct evdns_server_request *exreq, int flags)
1794 struct server_request *req = TO_SERVER_REQUEST(exreq);
1795 req->base.flags &= ~(EVDNS_FLAGS_AA|EVDNS_FLAGS_RD);
1796 req->base.flags |= flags;
1800 evdns_server_request_format_response(struct server_request *req, int err)
1802 unsigned char buf[1500];
1803 size_t buf_len = sizeof(buf);
1809 struct dnslabel_table table;
1811 if (err < 0 || err > 15) return -1;
1813 /* Set response bit and error code; copy OPCODE and RD fields from
1814 * question; copy RA and AA if set by caller. */
1815 flags = req->base.flags;
1816 flags |= (0x8000 | err);
1818 dnslabel_table_init(&table);
1819 APPEND16(req->trans_id);
1821 APPEND16(req->base.nquestions);
1822 APPEND16(req->n_answer);
1823 APPEND16(req->n_authority);
1824 APPEND16(req->n_additional);
1826 /* Add questions. */
1827 for (i=0; i < req->base.nquestions; ++i) {
1828 const char *s = req->base.questions[i]->name;
1829 j = dnsname_to_labels(buf, buf_len, j, s, strlen(s), &table);
1831 dnslabel_clear(&table);
1834 APPEND16(req->base.questions[i]->type);
1835 APPEND16(req->base.questions[i]->dns_question_class);
1838 /* Add answer, authority, and additional sections. */
1839 for (i=0; i<3; ++i) {
1840 struct server_reply_item *item;
1844 item = req->authority;
1846 item = req->additional;
1848 r = dnsname_to_labels(buf, buf_len, j, item->name, strlen(item->name), &table);
1853 APPEND16(item->type);
1854 APPEND16(item->dns_question_class);
1855 APPEND32(item->ttl);
1856 if (item->is_name) {
1857 off_t len_idx = j, name_start;
1860 r = dnsname_to_labels(buf, buf_len, j, item->data, strlen(item->data), &table);
1864 _t = htons( (short) (j-name_start) );
1865 memcpy(buf+len_idx, &_t, 2);
1867 APPEND16(item->datalen);
1868 if (j+item->datalen > (off_t)buf_len)
1870 memcpy(buf+j, item->data, item->datalen);
1880 buf[2] |= 0x02; /* set the truncated bit. */
1883 req->response_len = j;
1885 if (!(req->response = mm_malloc(req->response_len))) {
1886 server_request_free_answers(req);
1887 dnslabel_clear(&table);
1890 memcpy(req->response, buf, req->response_len);
1891 server_request_free_answers(req);
1892 dnslabel_clear(&table);
1896 /* exported function */
1898 evdns_server_request_respond(struct evdns_server_request *_req, int err)
1900 struct server_request *req = TO_SERVER_REQUEST(_req);
1901 struct evdns_server_port *port = req->port;
1905 if (!req->response) {
1906 if ((r = evdns_server_request_format_response(req, err))<0)
1910 r = sendto(port->socket, req->response, (int)req->response_len, 0,
1911 (struct sockaddr*) &req->addr, (ev_socklen_t)req->addrlen);
1913 int sock_err = evutil_socket_geterror(port->socket);
1914 if (EVUTIL_ERR_RW_RETRIABLE(sock_err))
1917 if (port->pending_replies) {
1918 req->prev_pending = port->pending_replies->prev_pending;
1919 req->next_pending = port->pending_replies;
1920 req->prev_pending->next_pending =
1921 req->next_pending->prev_pending = req;
1923 req->prev_pending = req->next_pending = req;
1924 port->pending_replies = req;
1927 (void) event_del(&port->event);
1928 event_assign(&port->event, port->event_base, port->socket, (port->closing?0:EV_READ) | EV_WRITE | EV_PERSIST, server_port_ready_callback, port);
1930 if (event_add(&port->event, NULL) < 0) {
1931 log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server");
1939 if (server_request_free(req)) {
1944 if (port->pending_replies)
1945 server_port_flush(port);
1953 /* Free all storage held by RRs in req. */
1955 server_request_free_answers(struct server_request *req)
1957 struct server_reply_item *victim, *next, **list;
1959 for (i = 0; i < 3; ++i) {
1961 list = &req->answer;
1963 list = &req->authority;
1965 list = &req->additional;
1969 next = victim->next;
1970 mm_free(victim->name);
1972 mm_free(victim->data);
1980 /* Free all storage held by req, and remove links to it. */
1981 /* return true iff we just wound up freeing the server_port. */
1983 server_request_free(struct server_request *req)
1985 int i, rc=1, lock=0;
1986 if (req->base.questions) {
1987 for (i = 0; i < req->base.nquestions; ++i)
1988 mm_free(req->base.questions[i]);
1989 mm_free(req->base.questions);
1993 EVDNS_LOCK(req->port);
1995 if (req->port->pending_replies == req) {
1996 if (req->next_pending)
1997 req->port->pending_replies = req->next_pending;
1999 req->port->pending_replies = NULL;
2001 rc = --req->port->refcnt;
2004 if (req->response) {
2005 mm_free(req->response);
2008 server_request_free_answers(req);
2010 if (req->next_pending && req->next_pending != req) {
2011 req->next_pending->prev_pending = req->prev_pending;
2012 req->prev_pending->next_pending = req->next_pending;
2016 EVDNS_UNLOCK(req->port); /* ????? nickm */
2017 server_port_free(req->port);
2022 EVDNS_UNLOCK(req->port);
2027 /* Free all storage held by an evdns_server_port. Only called when */
2029 server_port_free(struct evdns_server_port *port)
2031 EVUTIL_ASSERT(port);
2032 EVUTIL_ASSERT(!port->refcnt);
2033 EVUTIL_ASSERT(!port->pending_replies);
2034 if (port->socket > 0) {
2035 evutil_closesocket(port->socket);
2038 (void) event_del(&port->event);
2039 event_debug_unassign(&port->event);
2040 EVTHREAD_FREE_LOCK(port->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
2044 /* exported function */
2046 evdns_server_request_drop(struct evdns_server_request *_req)
2048 struct server_request *req = TO_SERVER_REQUEST(_req);
2049 server_request_free(req);
2053 /* exported function */
2055 evdns_server_request_get_requesting_addr(struct evdns_server_request *_req, struct sockaddr *sa, int addr_len)
2057 struct server_request *req = TO_SERVER_REQUEST(_req);
2058 if (addr_len < (int)req->addrlen)
2060 memcpy(sa, &(req->addr), req->addrlen);
2061 return req->addrlen;
2067 /* this is a libevent callback function which is called when a request */
2068 /* has timed out. */
2070 evdns_request_timeout_callback(evutil_socket_t fd, short events, void *arg) {
2071 struct request *const req = (struct request *) arg;
2072 #ifndef _EVENT_DISABLE_THREAD_SUPPORT
2073 struct evdns_base *base = req->base;
2078 log(EVDNS_LOG_DEBUG, "Request %p timed out", arg);
2081 req->ns->timedout++;
2082 if (req->ns->timedout > req->base->global_max_nameserver_timeout) {
2083 req->ns->timedout = 0;
2084 nameserver_failed(req->ns, "request timed out.");
2087 if (req->tx_count >= req->base->global_max_retransmits) {
2088 /* this request has failed */
2089 reply_schedule_callback(req, 0, DNS_ERR_TIMEOUT, NULL);
2090 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1);
2093 (void) evtimer_del(&req->timeout_event);
2094 evdns_request_transmit(req);
2099 /* try to send a request to a given server. */
2103 /* 1 temporary failure */
2104 /* 2 other failure */
2106 evdns_request_transmit_to(struct request *req, struct nameserver *server) {
2108 ASSERT_LOCKED(req->base);
2109 ASSERT_VALID_REQUEST(req);
2110 r = sendto(server->socket, (void*)req->request, req->request_len, 0,
2111 (struct sockaddr *)&server->address, server->addrlen);
2113 int err = evutil_socket_geterror(server->socket);
2114 if (EVUTIL_ERR_RW_RETRIABLE(err))
2116 nameserver_failed(req->ns, evutil_socket_error_to_string(err));
2118 } else if (r != (int)req->request_len) {
2119 return 1; /* short write */
2125 /* try to send a request, updating the fields of the request */
2132 evdns_request_transmit(struct request *req) {
2135 ASSERT_LOCKED(req->base);
2136 ASSERT_VALID_REQUEST(req);
2137 /* if we fail to send this packet then this flag marks it */
2138 /* for evdns_transmit */
2139 req->transmit_me = 1;
2140 EVUTIL_ASSERT(req->trans_id != 0xffff);
2142 if (req->ns->choked) {
2143 /* don't bother trying to write to a socket */
2144 /* which we have had EAGAIN from */
2148 r = evdns_request_transmit_to(req, req->ns);
2152 req->ns->choked = 1;
2153 nameserver_write_waiting(req->ns, 1);
2156 /* failed to transmit the request entirely. */
2158 /* fall through: we'll set a timeout, which will time out,
2159 * and make us retransmit the request anyway. */
2162 log(EVDNS_LOG_DEBUG,
2163 "Setting timeout for request %p", req);
2164 if (evtimer_add(&req->timeout_event, &req->base->global_timeout) < 0) {
2166 "Error from libevent when adding timer for request %p",
2171 req->transmit_me = 0;
2177 nameserver_probe_callback(int result, char type, int count, int ttl, void *addresses, void *arg) {
2178 struct nameserver *const ns = (struct nameserver *) arg;
2184 EVDNS_LOCK(ns->base);
2185 ns->probe_request = NULL;
2186 if (result == DNS_ERR_CANCEL) {
2187 /* We canceled this request because the nameserver came up
2188 * for some other reason. Do not change our opinion about
2189 * the nameserver. */
2190 } else if (result == DNS_ERR_NONE || result == DNS_ERR_NOTEXIST) {
2191 /* this is a good reply */
2194 nameserver_probe_failed(ns);
2196 EVDNS_UNLOCK(ns->base);
2200 nameserver_send_probe(struct nameserver *const ns) {
2201 struct evdns_request *handle;
2202 struct request *req;
2204 /* here we need to send a probe to a given nameserver */
2205 /* in the hope that it is up now. */
2207 ASSERT_LOCKED(ns->base);
2208 log(EVDNS_LOG_DEBUG, "Sending probe to %s",
2209 evutil_format_sockaddr_port(
2210 (struct sockaddr *)&ns->address,
2211 addrbuf, sizeof(addrbuf)));
2212 handle = mm_calloc(1, sizeof(*handle));
2213 if (!handle) return;
2214 req = request_new(ns->base, handle, TYPE_A, "google.com", DNS_QUERY_NO_SEARCH, nameserver_probe_callback, ns);
2216 ns->probe_request = handle;
2217 /* we force this into the inflight queue no matter what */
2218 request_trans_id_set(req, transaction_id_pick(ns->base));
2220 request_submit(req);
2224 /* 0 didn't try to transmit anything */
2225 /* 1 tried to transmit something */
2227 evdns_transmit(struct evdns_base *base) {
2228 char did_try_to_transmit = 0;
2231 ASSERT_LOCKED(base);
2232 for (i = 0; i < base->n_req_heads; ++i) {
2233 if (base->req_heads[i]) {
2234 struct request *const started_at = base->req_heads[i], *req = started_at;
2235 /* first transmit all the requests which are currently waiting */
2237 if (req->transmit_me) {
2238 did_try_to_transmit = 1;
2239 evdns_request_transmit(req);
2243 } while (req != started_at);
2247 return did_try_to_transmit;
2250 /* exported function */
2252 evdns_base_count_nameservers(struct evdns_base *base)
2254 const struct nameserver *server;
2258 server = base->server_head;
2263 server = server->next;
2264 } while (server != base->server_head);
2271 evdns_count_nameservers(void)
2273 return evdns_base_count_nameservers(current_base);
2276 /* exported function */
2278 evdns_base_clear_nameservers_and_suspend(struct evdns_base *base)
2280 struct nameserver *server, *started_at;
2284 server = base->server_head;
2285 started_at = base->server_head;
2291 struct nameserver *next = server->next;
2292 (void) event_del(&server->event);
2293 if (evtimer_initialized(&server->timeout_event))
2294 (void) evtimer_del(&server->timeout_event);
2295 if (server->socket >= 0)
2296 evutil_closesocket(server->socket);
2298 if (next == started_at)
2302 base->server_head = NULL;
2303 base->global_good_nameservers = 0;
2305 for (i = 0; i < base->n_req_heads; ++i) {
2306 struct request *req, *req_started_at;
2307 req = req_started_at = base->req_heads[i];
2309 struct request *next = req->next;
2310 req->tx_count = req->reissue_count = 0;
2312 /* ???? What to do about searches? */
2313 (void) evtimer_del(&req->timeout_event);
2315 req->transmit_me = 0;
2317 base->global_requests_waiting++;
2318 evdns_request_insert(req, &base->req_waiting_head);
2319 /* We want to insert these suspended elements at the front of
2320 * the waiting queue, since they were pending before any of
2321 * the waiting entries were added. This is a circular list,
2322 * so we can just shift the start back by one.*/
2323 base->req_waiting_head = base->req_waiting_head->prev;
2325 if (next == req_started_at)
2329 base->req_heads[i] = NULL;
2332 base->global_requests_inflight = 0;
2339 evdns_clear_nameservers_and_suspend(void)
2341 return evdns_base_clear_nameservers_and_suspend(current_base);
2345 /* exported function */
2347 evdns_base_resume(struct evdns_base *base)
2350 evdns_requests_pump_waiting_queue(base);
2358 return evdns_base_resume(current_base);
2362 _evdns_nameserver_add_impl(struct evdns_base *base, const struct sockaddr *address, int addrlen) {
2363 /* first check to see if we already have this nameserver */
2365 const struct nameserver *server = base->server_head, *const started_at = base->server_head;
2366 struct nameserver *ns;
2370 ASSERT_LOCKED(base);
2373 if (!evutil_sockaddr_cmp((struct sockaddr*)&server->address, address, 1)) return 3;
2374 server = server->next;
2375 } while (server != started_at);
2377 if (addrlen > (int)sizeof(ns->address)) {
2378 log(EVDNS_LOG_DEBUG, "Addrlen %d too long.", (int)addrlen);
2382 ns = (struct nameserver *) mm_malloc(sizeof(struct nameserver));
2385 memset(ns, 0, sizeof(struct nameserver));
2388 evtimer_assign(&ns->timeout_event, ns->base->event_base, nameserver_prod_callback, ns);
2390 ns->socket = socket(PF_INET, SOCK_DGRAM, 0);
2391 if (ns->socket < 0) { err = 1; goto out1; }
2392 evutil_make_socket_closeonexec(ns->socket);
2393 evutil_make_socket_nonblocking(ns->socket);
2395 if (base->global_outgoing_addrlen &&
2396 !evutil_sockaddr_is_loopback(address)) {
2397 if (bind(ns->socket,
2398 (struct sockaddr*)&base->global_outgoing_address,
2399 base->global_outgoing_addrlen) < 0) {
2400 log(EVDNS_LOG_WARN,"Couldn't bind to outgoing address");
2406 memcpy(&ns->address, address, addrlen);
2407 ns->addrlen = addrlen;
2409 event_assign(&ns->event, ns->base->event_base, ns->socket, EV_READ | EV_PERSIST, nameserver_ready_callback, ns);
2410 if (event_add(&ns->event, NULL) < 0) {
2415 log(EVDNS_LOG_DEBUG, "Added nameserver %s",
2416 evutil_format_sockaddr_port(address, addrbuf, sizeof(addrbuf)));
2418 /* insert this nameserver into the list of them */
2419 if (!base->server_head) {
2420 ns->next = ns->prev = ns;
2421 base->server_head = ns;
2423 ns->next = base->server_head->next;
2424 ns->prev = base->server_head;
2425 base->server_head->next = ns;
2426 if (base->server_head->prev == base->server_head) {
2427 base->server_head->prev = ns;
2431 base->global_good_nameservers++;
2436 evutil_closesocket(ns->socket);
2438 event_debug_unassign(&ns->event);
2440 log(EVDNS_LOG_WARN, "Unable to add nameserver %s: error %d",
2441 evutil_format_sockaddr_port(address, addrbuf, sizeof(addrbuf)), err);
2445 /* exported function */
2447 evdns_base_nameserver_add(struct evdns_base *base, unsigned long int address)
2449 struct sockaddr_in sin;
2451 sin.sin_addr.s_addr = address;
2452 sin.sin_port = htons(53);
2453 sin.sin_family = AF_INET;
2455 res = _evdns_nameserver_add_impl(base, (struct sockaddr*)&sin, sizeof(sin));
2461 evdns_nameserver_add(unsigned long int address) {
2463 current_base = evdns_base_new(NULL, 0);
2464 return evdns_base_nameserver_add(current_base, address);
2468 sockaddr_setport(struct sockaddr *sa, ev_uint16_t port)
2470 if (sa->sa_family == AF_INET) {
2471 ((struct sockaddr_in *)sa)->sin_port = htons(port);
2472 } else if (sa->sa_family == AF_INET6) {
2473 ((struct sockaddr_in6 *)sa)->sin6_port = htons(port);
2478 sockaddr_getport(struct sockaddr *sa)
2480 if (sa->sa_family == AF_INET) {
2481 return ntohs(((struct sockaddr_in *)sa)->sin_port);
2482 } else if (sa->sa_family == AF_INET6) {
2483 return ntohs(((struct sockaddr_in6 *)sa)->sin6_port);
2489 /* exported function */
2491 evdns_base_nameserver_ip_add(struct evdns_base *base, const char *ip_as_string) {
2492 struct sockaddr_storage ss;
2493 struct sockaddr *sa;
2494 int len = sizeof(ss);
2496 if (evutil_parse_sockaddr_port(ip_as_string, (struct sockaddr *)&ss,
2498 log(EVDNS_LOG_WARN, "Unable to parse nameserver address %s",
2502 sa = (struct sockaddr *) &ss;
2503 if (sockaddr_getport(sa) == 0)
2504 sockaddr_setport(sa, 53);
2507 res = _evdns_nameserver_add_impl(base, sa, len);
2513 evdns_nameserver_ip_add(const char *ip_as_string) {
2515 current_base = evdns_base_new(NULL, 0);
2516 return evdns_base_nameserver_ip_add(current_base, ip_as_string);
2520 evdns_base_nameserver_sockaddr_add(struct evdns_base *base,
2521 const struct sockaddr *sa, ev_socklen_t len, unsigned flags)
2524 EVUTIL_ASSERT(base);
2526 res = _evdns_nameserver_add_impl(base, sa, len);
2531 /* remove from the queue */
2533 evdns_request_remove(struct request *req, struct request **head)
2535 ASSERT_LOCKED(req->base);
2536 ASSERT_VALID_REQUEST(req);
2540 struct request *ptr;
2542 EVUTIL_ASSERT(*head != NULL);
2551 } while (ptr != *head);
2552 EVUTIL_ASSERT(found);
2554 EVUTIL_ASSERT(req->next);
2558 if (req->next == req) {
2559 /* only item in the list */
2562 req->next->prev = req->prev;
2563 req->prev->next = req->next;
2564 if (*head == req) *head = req->next;
2566 req->next = req->prev = NULL;
2569 /* insert into the tail of the queue */
2571 evdns_request_insert(struct request *req, struct request **head) {
2572 ASSERT_LOCKED(req->base);
2573 ASSERT_VALID_REQUEST(req);
2576 req->next = req->prev = req;
2580 req->prev = (*head)->prev;
2581 req->prev->next = req;
2583 (*head)->prev = req;
2587 string_num_dots(const char *s) {
2589 while ((s = strchr(s, '.'))) {
2596 static struct request *
2597 request_new(struct evdns_base *base, struct evdns_request *handle, int type,
2598 const char *name, int flags, evdns_callback_type callback,
2601 const char issuing_now =
2602 (base->global_requests_inflight < base->global_max_requests_inflight) ? 1 : 0;
2604 const size_t name_len = strlen(name);
2605 const size_t request_max_len = evdns_request_len(name_len);
2606 const u16 trans_id = issuing_now ? transaction_id_pick(base) : 0xffff;
2607 /* the request data is alloced in a single block with the header */
2608 struct request *const req =
2609 mm_malloc(sizeof(struct request) + request_max_len);
2614 ASSERT_LOCKED(base);
2616 if (!req) return NULL;
2618 if (name_len >= sizeof(namebuf)) {
2623 memset(req, 0, sizeof(struct request));
2626 evtimer_assign(&req->timeout_event, req->base->event_base, evdns_request_timeout_callback, req);
2628 if (base->global_randomize_case) {
2630 char randbits[(sizeof(namebuf)+7)/8];
2631 strlcpy(namebuf, name, sizeof(namebuf));
2632 evutil_secure_rng_get_bytes(randbits, (name_len+7)/8);
2633 for (i = 0; i < name_len; ++i) {
2634 if (EVUTIL_ISALPHA(namebuf[i])) {
2635 if ((randbits[i >> 3] & (1<<(i & 7))))
2638 namebuf[i] &= ~0x20;
2644 /* request data lives just after the header */
2645 req->request = ((u8 *) req) + sizeof(struct request);
2646 /* denotes that the request data shouldn't be free()ed */
2647 req->request_appended = 1;
2648 rlen = evdns_request_data_build(name, name_len, trans_id,
2649 type, CLASS_INET, req->request, request_max_len);
2653 req->request_len = rlen;
2654 req->trans_id = trans_id;
2656 req->request_type = type;
2657 req->user_pointer = user_ptr;
2658 req->user_callback = callback;
2659 req->ns = issuing_now ? nameserver_pick(base) : NULL;
2660 req->next = req->prev = NULL;
2661 req->handle = handle;
2663 handle->current_req = req;
2664 handle->base = base;
2674 request_submit(struct request *const req) {
2675 struct evdns_base *base = req->base;
2676 ASSERT_LOCKED(base);
2677 ASSERT_VALID_REQUEST(req);
2679 /* if it has a nameserver assigned then this is going */
2680 /* straight into the inflight queue */
2681 evdns_request_insert(req, &REQ_HEAD(base, req->trans_id));
2682 base->global_requests_inflight++;
2683 evdns_request_transmit(req);
2685 evdns_request_insert(req, &base->req_waiting_head);
2686 base->global_requests_waiting++;
2690 /* exported function */
2692 evdns_cancel_request(struct evdns_base *base, struct evdns_request *handle)
2694 struct request *req;
2697 /* This redundancy is silly; can we fix it? (Not for 2.0) XXXX */
2698 base = handle->base;
2699 if (!base && handle->current_req)
2700 base = handle->current_req->base;
2704 if (handle->pending_cb) {
2709 req = handle->current_req;
2710 ASSERT_VALID_REQUEST(req);
2712 reply_schedule_callback(req, 0, DNS_ERR_CANCEL, NULL);
2714 /* remove from inflight queue */
2715 request_finished(req, &REQ_HEAD(base, req->trans_id), 1);
2717 /* remove from global_waiting head */
2718 request_finished(req, &base->req_waiting_head, 1);
2723 /* exported function */
2724 struct evdns_request *
2725 evdns_base_resolve_ipv4(struct evdns_base *base, const char *name, int flags,
2726 evdns_callback_type callback, void *ptr) {
2727 struct evdns_request *handle;
2728 struct request *req;
2729 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name);
2730 handle = mm_calloc(1, sizeof(*handle));
2734 if (flags & DNS_QUERY_NO_SEARCH) {
2736 request_new(base, handle, TYPE_A, name, flags,
2739 request_submit(req);
2741 search_request_new(base, handle, TYPE_A, name, flags,
2744 if (handle->current_req == NULL) {
2752 int evdns_resolve_ipv4(const char *name, int flags,
2753 evdns_callback_type callback, void *ptr)
2755 return evdns_base_resolve_ipv4(current_base, name, flags, callback, ptr)
2760 /* exported function */
2761 struct evdns_request *
2762 evdns_base_resolve_ipv6(struct evdns_base *base,
2763 const char *name, int flags,
2764 evdns_callback_type callback, void *ptr)
2766 struct evdns_request *handle;
2767 struct request *req;
2768 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name);
2769 handle = mm_calloc(1, sizeof(*handle));
2773 if (flags & DNS_QUERY_NO_SEARCH) {
2774 req = request_new(base, handle, TYPE_AAAA, name, flags,
2777 request_submit(req);
2779 search_request_new(base, handle, TYPE_AAAA, name, flags,
2782 if (handle->current_req == NULL) {
2790 int evdns_resolve_ipv6(const char *name, int flags,
2791 evdns_callback_type callback, void *ptr) {
2792 return evdns_base_resolve_ipv6(current_base, name, flags, callback, ptr)
2796 struct evdns_request *
2797 evdns_base_resolve_reverse(struct evdns_base *base, const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) {
2799 struct evdns_request *handle;
2800 struct request *req;
2803 a = ntohl(in->s_addr);
2804 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa",
2805 (int)(u8)((a )&0xff),
2806 (int)(u8)((a>>8 )&0xff),
2807 (int)(u8)((a>>16)&0xff),
2808 (int)(u8)((a>>24)&0xff));
2809 handle = mm_calloc(1, sizeof(*handle));
2812 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf);
2814 req = request_new(base, handle, TYPE_PTR, buf, flags, callback, ptr);
2816 request_submit(req);
2817 if (handle->current_req == NULL) {
2825 int evdns_resolve_reverse(const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) {
2826 return evdns_base_resolve_reverse(current_base, in, flags, callback, ptr)
2830 struct evdns_request *
2831 evdns_base_resolve_reverse_ipv6(struct evdns_base *base, const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) {
2832 /* 32 nybbles, 32 periods, "ip6.arpa", NUL. */
2835 struct evdns_request *handle;
2836 struct request *req;
2840 for (i=15; i >= 0; --i) {
2841 u8 byte = in->s6_addr[i];
2842 *cp++ = "0123456789abcdef"[byte & 0x0f];
2844 *cp++ = "0123456789abcdef"[byte >> 4];
2847 EVUTIL_ASSERT(cp + strlen("ip6.arpa") < buf+sizeof(buf));
2848 memcpy(cp, "ip6.arpa", strlen("ip6.arpa")+1);
2849 handle = mm_calloc(1, sizeof(*handle));
2852 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf);
2854 req = request_new(base, handle, TYPE_PTR, buf, flags, callback, ptr);
2856 request_submit(req);
2857 if (handle->current_req == NULL) {
2865 int evdns_resolve_reverse_ipv6(const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) {
2866 return evdns_base_resolve_reverse_ipv6(current_base, in, flags, callback, ptr)
2870 /* ================================================================= */
2871 /* Search support */
2873 /* the libc resolver has support for searching a number of domains */
2874 /* to find a name. If nothing else then it takes the single domain */
2875 /* from the gethostname() call. */
2877 /* It can also be configured via the domain and search options in a */
2880 /* The ndots option controls how many dots it takes for the resolver */
2881 /* to decide that a name is non-local and so try a raw lookup first. */
2883 struct search_domain {
2885 struct search_domain *next;
2886 /* the text string is appended to this structure */
2889 struct search_state {
2893 struct search_domain *head;
2897 search_state_decref(struct search_state *const state) {
2900 if (!state->refcount) {
2901 struct search_domain *next, *dom;
2902 for (dom = state->head; dom; dom = next) {
2910 static struct search_state *
2911 search_state_new(void) {
2912 struct search_state *state = (struct search_state *) mm_malloc(sizeof(struct search_state));
2913 if (!state) return NULL;
2914 memset(state, 0, sizeof(struct search_state));
2915 state->refcount = 1;
2922 search_postfix_clear(struct evdns_base *base) {
2923 search_state_decref(base->global_search_state);
2925 base->global_search_state = search_state_new();
2928 /* exported function */
2930 evdns_base_search_clear(struct evdns_base *base)
2933 search_postfix_clear(base);
2938 evdns_search_clear(void) {
2939 evdns_base_search_clear(current_base);
2943 search_postfix_add(struct evdns_base *base, const char *domain) {
2945 struct search_domain *sdomain;
2946 while (domain[0] == '.') domain++;
2947 domain_len = strlen(domain);
2949 ASSERT_LOCKED(base);
2950 if (!base->global_search_state) base->global_search_state = search_state_new();
2951 if (!base->global_search_state) return;
2952 base->global_search_state->num_domains++;
2954 sdomain = (struct search_domain *) mm_malloc(sizeof(struct search_domain) + domain_len);
2955 if (!sdomain) return;
2956 memcpy( ((u8 *) sdomain) + sizeof(struct search_domain), domain, domain_len);
2957 sdomain->next = base->global_search_state->head;
2958 sdomain->len = (int) domain_len;
2960 base->global_search_state->head = sdomain;
2963 /* reverse the order of members in the postfix list. This is needed because, */
2964 /* when parsing resolv.conf we push elements in the wrong order */
2966 search_reverse(struct evdns_base *base) {
2967 struct search_domain *cur, *prev = NULL, *next;
2968 ASSERT_LOCKED(base);
2969 cur = base->global_search_state->head;
2977 base->global_search_state->head = prev;
2980 /* exported function */
2982 evdns_base_search_add(struct evdns_base *base, const char *domain) {
2984 search_postfix_add(base, domain);
2988 evdns_search_add(const char *domain) {
2989 evdns_base_search_add(current_base, domain);
2992 /* exported function */
2994 evdns_base_search_ndots_set(struct evdns_base *base, const int ndots) {
2996 if (!base->global_search_state) base->global_search_state = search_state_new();
2997 if (base->global_search_state)
2998 base->global_search_state->ndots = ndots;
3002 evdns_search_ndots_set(const int ndots) {
3003 evdns_base_search_ndots_set(current_base, ndots);
3007 search_set_from_hostname(struct evdns_base *base) {
3008 char hostname[HOST_NAME_MAX + 1], *domainname;
3010 ASSERT_LOCKED(base);
3011 search_postfix_clear(base);
3012 if (gethostname(hostname, sizeof(hostname))) return;
3013 domainname = strchr(hostname, '.');
3014 if (!domainname) return;
3015 search_postfix_add(base, domainname);
3018 /* warning: returns malloced string */
3020 search_make_new(const struct search_state *const state, int n, const char *const base_name) {
3021 const size_t base_len = strlen(base_name);
3022 const char need_to_append_dot = base_name[base_len - 1] == '.' ? 0 : 1;
3023 struct search_domain *dom;
3025 for (dom = state->head; dom; dom = dom->next) {
3027 /* this is the postfix we want */
3028 /* the actual postfix string is kept at the end of the structure */
3029 const u8 *const postfix = ((u8 *) dom) + sizeof(struct search_domain);
3030 const int postfix_len = dom->len;
3031 char *const newname = (char *) mm_malloc(base_len + need_to_append_dot + postfix_len + 1);
3032 if (!newname) return NULL;
3033 memcpy(newname, base_name, base_len);
3034 if (need_to_append_dot) newname[base_len] = '.';
3035 memcpy(newname + base_len + need_to_append_dot, postfix, postfix_len);
3036 newname[base_len + need_to_append_dot + postfix_len] = 0;
3041 /* we ran off the end of the list and still didn't find the requested string */
3043 return NULL; /* unreachable; stops warnings in some compilers. */
3046 static struct request *
3047 search_request_new(struct evdns_base *base, struct evdns_request *handle,
3048 int type, const char *const name, int flags,
3049 evdns_callback_type user_callback, void *user_arg) {
3050 ASSERT_LOCKED(base);
3051 EVUTIL_ASSERT(type == TYPE_A || type == TYPE_AAAA);
3052 EVUTIL_ASSERT(handle->current_req == NULL);
3053 if ( ((flags & DNS_QUERY_NO_SEARCH) == 0) &&
3054 base->global_search_state &&
3055 base->global_search_state->num_domains) {
3056 /* we have some domains to search */
3057 struct request *req;
3058 if (string_num_dots(name) >= base->global_search_state->ndots) {
3059 req = request_new(base, handle, type, name, flags, user_callback, user_arg);
3060 if (!req) return NULL;
3061 handle->search_index = -1;
3063 char *const new_name = search_make_new(base->global_search_state, 0, name);
3064 if (!new_name) return NULL;
3065 req = request_new(base, handle, type, new_name, flags, user_callback, user_arg);
3067 if (!req) return NULL;
3068 handle->search_index = 0;
3070 EVUTIL_ASSERT(handle->search_origname == NULL);
3071 handle->search_origname = mm_strdup(name);
3072 handle->search_state = base->global_search_state;
3073 handle->search_flags = flags;
3074 base->global_search_state->refcount++;
3075 request_submit(req);
3078 struct request *const req = request_new(base, handle, type, name, flags, user_callback, user_arg);
3079 if (!req) return NULL;
3080 request_submit(req);
3085 /* this is called when a request has failed to find a name. We need to check */
3086 /* if it is part of a search and, if so, try the next name in the list */
3088 /* 0 another request has been submitted */
3089 /* 1 no more requests needed */
3091 search_try_next(struct evdns_request *const handle) {
3092 struct request *req = handle->current_req;
3093 struct evdns_base *base = req->base;
3094 struct request *newreq;
3095 ASSERT_LOCKED(base);
3096 if (handle->search_state) {
3097 /* it is part of a search */
3099 handle->search_index++;
3100 if (handle->search_index >= handle->search_state->num_domains) {
3101 /* no more postfixes to try, however we may need to try */
3102 /* this name without a postfix */
3103 if (string_num_dots(handle->search_origname) < handle->search_state->ndots) {
3104 /* yep, we need to try it raw */
3105 newreq = request_new(base, NULL, req->request_type, handle->search_origname, handle->search_flags, req->user_callback, req->user_pointer);
3106 log(EVDNS_LOG_DEBUG, "Search: trying raw query %s", handle->search_origname);
3108 search_request_finished(handle);
3115 new_name = search_make_new(handle->search_state, handle->search_index, handle->search_origname);
3116 if (!new_name) return 1;
3117 log(EVDNS_LOG_DEBUG, "Search: now trying %s (%d)", new_name, handle->search_index);
3118 newreq = request_new(base, NULL, req->request_type, new_name, handle->search_flags, req->user_callback, req->user_pointer);
3120 if (!newreq) return 1;
3126 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 0);
3127 handle->current_req = newreq;
3128 newreq->handle = handle;
3129 request_submit(newreq);
3134 search_request_finished(struct evdns_request *const handle) {
3135 ASSERT_LOCKED(handle->current_req->base);
3136 if (handle->search_state) {
3137 search_state_decref(handle->search_state);
3138 handle->search_state = NULL;
3140 if (handle->search_origname) {
3141 mm_free(handle->search_origname);
3142 handle->search_origname = NULL;
3146 /* ================================================================= */
3147 /* Parsing resolv.conf files */
3150 evdns_resolv_set_defaults(struct evdns_base *base, int flags) {
3151 /* if the file isn't found then we assume a local resolver */
3152 ASSERT_LOCKED(base);
3153 if (flags & DNS_OPTION_SEARCH) search_set_from_hostname(base);
3154 if (flags & DNS_OPTION_NAMESERVERS) evdns_base_nameserver_ip_add(base,"127.0.0.1");
3157 #ifndef _EVENT_HAVE_STRTOK_R
3159 strtok_r(char *s, const char *delim, char **state) {
3161 start = cp = s ? s : *state;
3164 while (*cp && !strchr(delim, *cp))
3179 /* helper version of atoi which returns -1 on error */
3181 strtoint(const char *const str)
3184 const int r = strtol(str, &endptr, 10);
3185 if (*endptr) return -1;
3189 /* Parse a number of seconds into a timeval; return -1 on error. */
3191 strtotimeval(const char *const str, struct timeval *out)
3195 d = strtod(str, &endptr);
3196 if (*endptr) return -1;
3197 if (d < 0) return -1;
3198 out->tv_sec = (int) d;
3199 out->tv_usec = (int) ((d - (int) d)*1000000);
3200 if (out->tv_sec == 0 && out->tv_usec < 1000) /* less than 1 msec */
3205 /* helper version of atoi that returns -1 on error and clips to bounds. */
3207 strtoint_clipped(const char *const str, int min, int max)
3209 int r = strtoint(str);
3221 evdns_base_set_max_requests_inflight(struct evdns_base *base, int maxinflight)
3223 int old_n_heads = base->n_req_heads, n_heads;
3224 struct request **old_heads = base->req_heads, **new_heads, *req;
3227 ASSERT_LOCKED(base);
3228 if (maxinflight < 1)
3230 n_heads = (maxinflight+4) / 5;
3231 EVUTIL_ASSERT(n_heads > 0);
3232 new_heads = mm_calloc(n_heads, sizeof(struct request*));
3236 for (i = 0; i < old_n_heads; ++i) {
3237 while (old_heads[i]) {
3239 evdns_request_remove(req, &old_heads[i]);
3240 evdns_request_insert(req, &new_heads[req->trans_id % n_heads]);
3245 base->req_heads = new_heads;
3246 base->n_req_heads = n_heads;
3247 base->global_max_requests_inflight = maxinflight;
3251 /* exported function */
3253 evdns_base_set_option(struct evdns_base *base,
3254 const char *option, const char *val)
3258 res = evdns_base_set_option_impl(base, option, val, DNS_OPTIONS_ALL);
3264 str_matches_option(const char *s1, const char *optionname)
3266 /* Option names are given as "option:" We accept either 'option' in
3267 * s1, or 'option:randomjunk'. The latter form is to implement the
3268 * resolv.conf parser. */
3269 size_t optlen = strlen(optionname);
3270 size_t slen = strlen(s1);
3271 if (slen == optlen || slen == optlen - 1)
3272 return !strncmp(s1, optionname, slen);
3273 else if (slen > optlen)
3274 return !strncmp(s1, optionname, optlen);
3280 evdns_base_set_option_impl(struct evdns_base *base,
3281 const char *option, const char *val, int flags)
3283 ASSERT_LOCKED(base);
3284 if (str_matches_option(option, "ndots:")) {
3285 const int ndots = strtoint(val);
3286 if (ndots == -1) return -1;
3287 if (!(flags & DNS_OPTION_SEARCH)) return 0;
3288 log(EVDNS_LOG_DEBUG, "Setting ndots to %d", ndots);
3289 if (!base->global_search_state) base->global_search_state = search_state_new();
3290 if (!base->global_search_state) return -1;
3291 base->global_search_state->ndots = ndots;
3292 } else if (str_matches_option(option, "timeout:")) {
3294 if (strtotimeval(val, &tv) == -1) return -1;
3295 if (!(flags & DNS_OPTION_MISC)) return 0;
3296 log(EVDNS_LOG_DEBUG, "Setting timeout to %s", val);
3297 memcpy(&base->global_timeout, &tv, sizeof(struct timeval));
3298 } else if (str_matches_option(option, "getaddrinfo-allow-skew:")) {
3300 if (strtotimeval(val, &tv) == -1) return -1;
3301 if (!(flags & DNS_OPTION_MISC)) return 0;
3302 log(EVDNS_LOG_DEBUG, "Setting getaddrinfo-allow-skew to %s",
3304 memcpy(&base->global_getaddrinfo_allow_skew, &tv,
3305 sizeof(struct timeval));
3306 } else if (str_matches_option(option, "max-timeouts:")) {
3307 const int maxtimeout = strtoint_clipped(val, 1, 255);
3308 if (maxtimeout == -1) return -1;
3309 if (!(flags & DNS_OPTION_MISC)) return 0;
3310 log(EVDNS_LOG_DEBUG, "Setting maximum allowed timeouts to %d",
3312 base->global_max_nameserver_timeout = maxtimeout;
3313 } else if (str_matches_option(option, "max-inflight:")) {
3314 const int maxinflight = strtoint_clipped(val, 1, 65000);
3315 if (maxinflight == -1) return -1;
3316 if (!(flags & DNS_OPTION_MISC)) return 0;
3317 log(EVDNS_LOG_DEBUG, "Setting maximum inflight requests to %d",
3319 evdns_base_set_max_requests_inflight(base, maxinflight);
3320 } else if (str_matches_option(option, "attempts:")) {
3321 int retries = strtoint(val);
3322 if (retries == -1) return -1;
3323 if (retries > 255) retries = 255;
3324 if (!(flags & DNS_OPTION_MISC)) return 0;
3325 log(EVDNS_LOG_DEBUG, "Setting retries to %d", retries);
3326 base->global_max_retransmits = retries;
3327 } else if (str_matches_option(option, "randomize-case:")) {
3328 int randcase = strtoint(val);
3329 if (!(flags & DNS_OPTION_MISC)) return 0;
3330 base->global_randomize_case = randcase;
3331 } else if (str_matches_option(option, "bind-to:")) {
3332 /* XXX This only applies to successive nameservers, not
3333 * to already-configured ones. We might want to fix that. */
3334 int len = sizeof(base->global_outgoing_address);
3335 if (!(flags & DNS_OPTION_NAMESERVERS)) return 0;
3336 if (evutil_parse_sockaddr_port(val,
3337 (struct sockaddr*)&base->global_outgoing_address, &len))
3339 base->global_outgoing_addrlen = len;
3340 } else if (str_matches_option(option, "initial-probe-timeout:")) {
3342 if (strtotimeval(val, &tv) == -1) return -1;
3343 if (tv.tv_sec > 3600)
3345 if (!(flags & DNS_OPTION_MISC)) return 0;
3346 log(EVDNS_LOG_DEBUG, "Setting initial probe timeout to %s",
3348 memcpy(&base->global_nameserver_probe_initial_timeout, &tv,
3355 evdns_set_option(const char *option, const char *val, int flags)
3358 current_base = evdns_base_new(NULL, 0);
3359 return evdns_base_set_option(current_base, option, val);
3363 resolv_conf_parse_line(struct evdns_base *base, char *const start, int flags) {
3365 static const char *const delims = " \t";
3366 #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state)
3369 char *const first_token = strtok_r(start, delims, &strtok_state);
3370 ASSERT_LOCKED(base);
3371 if (!first_token) return;
3373 if (!strcmp(first_token, "nameserver") && (flags & DNS_OPTION_NAMESERVERS)) {
3374 const char *const nameserver = NEXT_TOKEN;
3377 evdns_base_nameserver_ip_add(base, nameserver);
3378 } else if (!strcmp(first_token, "domain") && (flags & DNS_OPTION_SEARCH)) {
3379 const char *const domain = NEXT_TOKEN;
3381 search_postfix_clear(base);
3382 search_postfix_add(base, domain);
3384 } else if (!strcmp(first_token, "search") && (flags & DNS_OPTION_SEARCH)) {
3386 search_postfix_clear(base);
3388 while ((domain = NEXT_TOKEN)) {
3389 search_postfix_add(base, domain);
3391 search_reverse(base);
3392 } else if (!strcmp(first_token, "options")) {
3394 while ((option = NEXT_TOKEN)) {
3395 const char *val = strchr(option, ':');
3396 evdns_base_set_option_impl(base, option, val ? val+1 : "", flags);
3402 /* exported function */
3405 /* 1 failed to open file */
3406 /* 2 failed to stat file */
3407 /* 3 file too large */
3408 /* 4 out of memory */
3409 /* 5 short read from file */
3411 evdns_base_resolv_conf_parse(struct evdns_base *base, int flags, const char *const filename) {
3414 res = evdns_base_resolv_conf_parse_impl(base, flags, filename);
3420 evdns_get_default_hosts_filename(void)
3423 /* Windows is a little coy about where it puts its configuration
3424 * files. Sure, they're _usually_ in C:\windows\system32, but
3425 * there's no reason in principle they couldn't be in
3426 * W:\hoboken chicken emergency\
3428 char path[MAX_PATH+1];
3429 static const char hostfile[] = "\\drivers\\etc\\hosts";
3433 if (! SHGetSpecialFolderPathA(NULL, path, CSIDL_SYSTEM, 0))
3435 len_out = strlen(path)+strlen(hostfile);
3436 path_out = mm_malloc(len_out+1);
3437 evutil_snprintf(path_out, len_out, "%s%s", path, hostfile);
3440 return mm_strdup("/etc/hosts");
3445 evdns_base_resolv_conf_parse_impl(struct evdns_base *base, int flags, const char *const filename) {
3451 log(EVDNS_LOG_DEBUG, "Parsing resolv.conf file %s", filename);
3453 if (flags & DNS_OPTION_HOSTSFILE) {
3454 char *fname = evdns_get_default_hosts_filename();
3455 evdns_base_load_hosts(base, fname);
3460 if ((err = evutil_read_file(filename, &resolv, &n, 0)) < 0) {
3463 evdns_resolv_set_defaults(base, flags);
3472 char *const newline = strchr(start, '\n');
3474 resolv_conf_parse_line(base, start, flags);
3478 resolv_conf_parse_line(base, start, flags);
3479 start = newline + 1;
3483 if (!base->server_head && (flags & DNS_OPTION_NAMESERVERS)) {
3484 /* no nameservers were configured. */
3485 evdns_base_nameserver_ip_add(base, "127.0.0.1");
3488 if (flags & DNS_OPTION_SEARCH && (!base->global_search_state || base->global_search_state->num_domains == 0)) {
3489 search_set_from_hostname(base);
3497 evdns_resolv_conf_parse(int flags, const char *const filename) {
3499 current_base = evdns_base_new(NULL, 0);
3500 return evdns_base_resolv_conf_parse(current_base, flags, filename);
3505 /* Add multiple nameservers from a space-or-comma-separated list. */
3507 evdns_nameserver_ip_add_line(struct evdns_base *base, const char *ips) {
3511 ASSERT_LOCKED(base);
3513 while (isspace(*ips) || *ips == ',' || *ips == '\t')
3516 while (isdigit(*ips) || *ips == '.' || *ips == ':' ||
3517 *ips=='[' || *ips==']')
3519 buf = mm_malloc(ips-addr+1);
3521 memcpy(buf, addr, ips-addr);
3522 buf[ips-addr] = '\0';
3523 r = evdns_base_nameserver_ip_add(base, buf);
3530 typedef DWORD(WINAPI *GetNetworkParams_fn_t)(FIXED_INFO *, DWORD*);
3532 /* Use the windows GetNetworkParams interface in iphlpapi.dll to */
3533 /* figure out what our nameservers are. */
3535 load_nameservers_with_getnetworkparams(struct evdns_base *base)
3537 /* Based on MSDN examples and inspection of c-ares code. */
3540 ULONG size = sizeof(FIXED_INFO);
3542 int status = 0, r, added_any;
3544 GetNetworkParams_fn_t fn;
3546 ASSERT_LOCKED(base);
3547 if (!(handle = evutil_load_windows_system_library(
3548 TEXT("iphlpapi.dll")))) {
3549 log(EVDNS_LOG_WARN, "Could not open iphlpapi.dll");
3553 if (!(fn = (GetNetworkParams_fn_t) GetProcAddress(handle, "GetNetworkParams"))) {
3554 log(EVDNS_LOG_WARN, "Could not get address of function.");
3559 buf = mm_malloc(size);
3560 if (!buf) { status = 4; goto done; }
3562 r = fn(fixed, &size);
3563 if (r != ERROR_SUCCESS && r != ERROR_BUFFER_OVERFLOW) {
3567 if (r != ERROR_SUCCESS) {
3569 buf = mm_malloc(size);
3570 if (!buf) { status = 4; goto done; }
3572 r = fn(fixed, &size);
3573 if (r != ERROR_SUCCESS) {
3574 log(EVDNS_LOG_DEBUG, "fn() failed.");
3580 EVUTIL_ASSERT(fixed);
3582 ns = &(fixed->DnsServerList);
3584 r = evdns_nameserver_ip_add_line(base, ns->IpAddress.String);
3586 log(EVDNS_LOG_DEBUG,"Could not add nameserver %s to list,error: %d",
3587 (ns->IpAddress.String),(int)GetLastError());
3591 log(EVDNS_LOG_DEBUG,"Successfully added %s as nameserver",ns->IpAddress.String);
3598 log(EVDNS_LOG_DEBUG, "No nameservers added.");
3609 FreeLibrary(handle);
3614 config_nameserver_from_reg_key(struct evdns_base *base, HKEY key, const TCHAR *subkey)
3617 DWORD bufsz = 0, type = 0;
3620 ASSERT_LOCKED(base);
3621 if (RegQueryValueEx(key, subkey, 0, &type, NULL, &bufsz)
3624 if (!(buf = mm_malloc(bufsz)))
3627 if (RegQueryValueEx(key, subkey, 0, &type, (LPBYTE)buf, &bufsz)
3628 == ERROR_SUCCESS && bufsz > 1) {
3629 status = evdns_nameserver_ip_add_line(base,buf);
3636 #define SERVICES_KEY TEXT("System\\CurrentControlSet\\Services\\")
3637 #define WIN_NS_9X_KEY SERVICES_KEY TEXT("VxD\\MSTCP")
3638 #define WIN_NS_NT_KEY SERVICES_KEY TEXT("Tcpip\\Parameters")
3641 load_nameservers_from_registry(struct evdns_base *base)
3645 #define TRY(k, name) \
3646 if (!found && config_nameserver_from_reg_key(base,k,TEXT(name)) == 0) { \
3647 log(EVDNS_LOG_DEBUG,"Found nameservers in %s/%s",#k,name); \
3649 } else if (!found) { \
3650 log(EVDNS_LOG_DEBUG,"Didn't find nameservers in %s/%s", \
3654 ASSERT_LOCKED(base);
3656 if (((int)GetVersion()) > 0) { /* NT */
3657 HKEY nt_key = 0, interfaces_key = 0;
3659 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0,
3660 KEY_READ, &nt_key) != ERROR_SUCCESS) {
3661 log(EVDNS_LOG_DEBUG,"Couldn't open nt key, %d",(int)GetLastError());
3664 r = RegOpenKeyEx(nt_key, TEXT("Interfaces"), 0,
3665 KEY_QUERY_VALUE|KEY_ENUMERATE_SUB_KEYS,
3667 if (r != ERROR_SUCCESS) {
3668 log(EVDNS_LOG_DEBUG,"Couldn't open interfaces key, %d",(int)GetLastError());
3671 TRY(nt_key, "NameServer");
3672 TRY(nt_key, "DhcpNameServer");
3673 TRY(interfaces_key, "NameServer");
3674 TRY(interfaces_key, "DhcpNameServer");
3675 RegCloseKey(interfaces_key);
3676 RegCloseKey(nt_key);
3679 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_9X_KEY, 0,
3680 KEY_READ, &win_key) != ERROR_SUCCESS) {
3681 log(EVDNS_LOG_DEBUG, "Couldn't open registry key, %d", (int)GetLastError());
3684 TRY(win_key, "NameServer");
3685 RegCloseKey(win_key);
3689 log(EVDNS_LOG_WARN,"Didn't find any nameservers.");
3692 return found ? 0 : -1;
3697 evdns_base_config_windows_nameservers(struct evdns_base *base)
3702 base = current_base;
3706 if (load_nameservers_with_getnetworkparams(base) == 0) {
3710 r = load_nameservers_from_registry(base);
3712 fname = evdns_get_default_hosts_filename();
3713 evdns_base_load_hosts(base, fname);
3722 evdns_config_windows_nameservers(void)
3724 if (!current_base) {
3725 current_base = evdns_base_new(NULL, 1);
3726 return current_base == NULL ? -1 : 0;
3728 return evdns_base_config_windows_nameservers(current_base);
3734 evdns_base_new(struct event_base *event_base, int initialize_nameservers)
3736 struct evdns_base *base;
3738 if (evutil_secure_rng_init() < 0) {
3739 log(EVDNS_LOG_WARN, "Unable to seed random number generator; "
3744 /* Give the evutil library a hook into its evdns-enabled
3745 * functionality. We can't just call evdns_getaddrinfo directly or
3746 * else libevent-core will depend on libevent-extras. */
3747 evutil_set_evdns_getaddrinfo_fn(evdns_getaddrinfo);
3749 base = mm_malloc(sizeof(struct evdns_base));
3752 memset(base, 0, sizeof(struct evdns_base));
3753 base->req_waiting_head = NULL;
3755 EVTHREAD_ALLOC_LOCK(base->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
3758 /* Set max requests inflight and allocate req_heads. */
3759 base->req_heads = NULL;
3761 evdns_base_set_max_requests_inflight(base, 64);
3763 base->server_head = NULL;
3764 base->event_base = event_base;
3765 base->global_good_nameservers = base->global_requests_inflight =
3766 base->global_requests_waiting = 0;
3768 base->global_timeout.tv_sec = 5;
3769 base->global_timeout.tv_usec = 0;
3770 base->global_max_reissues = 1;
3771 base->global_max_retransmits = 3;
3772 base->global_max_nameserver_timeout = 3;
3773 base->global_search_state = NULL;
3774 base->global_randomize_case = 1;
3775 base->global_getaddrinfo_allow_skew.tv_sec = 3;
3776 base->global_getaddrinfo_allow_skew.tv_usec = 0;
3777 base->global_nameserver_probe_initial_timeout.tv_sec = 10;
3778 base->global_nameserver_probe_initial_timeout.tv_usec = 0;
3780 TAILQ_INIT(&base->hostsdb);
3782 if (initialize_nameservers) {
3785 r = evdns_base_config_windows_nameservers(base);
3787 r = evdns_base_resolv_conf_parse(base, DNS_OPTIONS_ALL, "/etc/resolv.conf");
3790 evdns_base_free_and_unlock(base, 0);
3801 struct evdns_base *base = evdns_base_new(NULL, 1);
3803 current_base = base;
3811 evdns_err_to_string(int err)
3814 case DNS_ERR_NONE: return "no error";
3815 case DNS_ERR_FORMAT: return "misformatted query";
3816 case DNS_ERR_SERVERFAILED: return "server failed";
3817 case DNS_ERR_NOTEXIST: return "name does not exist";
3818 case DNS_ERR_NOTIMPL: return "query not implemented";
3819 case DNS_ERR_REFUSED: return "refused";
3821 case DNS_ERR_TRUNCATED: return "reply truncated or ill-formed";
3822 case DNS_ERR_UNKNOWN: return "unknown";
3823 case DNS_ERR_TIMEOUT: return "request timed out";
3824 case DNS_ERR_SHUTDOWN: return "dns subsystem shut down";
3825 case DNS_ERR_CANCEL: return "dns request canceled";
3826 default: return "[Unknown error code]";
3831 evdns_nameserver_free(struct nameserver *server)
3833 if (server->socket >= 0)
3834 evutil_closesocket(server->socket);
3835 (void) event_del(&server->event);
3836 event_debug_unassign(&server->event);
3837 if (server->state == 0)
3838 (void) event_del(&server->timeout_event);
3839 event_debug_unassign(&server->timeout_event);
3844 evdns_base_free_and_unlock(struct evdns_base *base, int fail_requests)
3846 struct nameserver *server, *server_next;
3847 struct search_domain *dom, *dom_next;
3850 /* Requires that we hold the lock. */
3852 /* TODO(nickm) we might need to refcount here. */
3854 for (i = 0; i < base->n_req_heads; ++i) {
3855 while (base->req_heads[i]) {
3857 reply_schedule_callback(base->req_heads[i], 0, DNS_ERR_SHUTDOWN, NULL);
3858 request_finished(base->req_heads[i], &REQ_HEAD(base, base->req_heads[i]->trans_id), 1);
3861 while (base->req_waiting_head) {
3863 reply_schedule_callback(base->req_waiting_head, 0, DNS_ERR_SHUTDOWN, NULL);
3864 request_finished(base->req_waiting_head, &base->req_waiting_head, 1);
3866 base->global_requests_inflight = base->global_requests_waiting = 0;
3868 for (server = base->server_head; server; server = server_next) {
3869 server_next = server->next;
3870 evdns_nameserver_free(server);
3871 if (server_next == base->server_head)
3874 base->server_head = NULL;
3875 base->global_good_nameservers = 0;
3877 if (base->global_search_state) {
3878 for (dom = base->global_search_state->head; dom; dom = dom_next) {
3879 dom_next = dom->next;
3882 mm_free(base->global_search_state);
3883 base->global_search_state = NULL;
3887 struct hosts_entry *victim;
3888 while ((victim = TAILQ_FIRST(&base->hostsdb))) {
3889 TAILQ_REMOVE(&base->hostsdb, victim, next);
3894 mm_free(base->req_heads);
3897 EVTHREAD_FREE_LOCK(base->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
3903 evdns_base_free(struct evdns_base *base, int fail_requests)
3906 evdns_base_free_and_unlock(base, fail_requests);
3910 evdns_shutdown(int fail_requests)
3913 struct evdns_base *b = current_base;
3914 current_base = NULL;
3915 evdns_base_free(b, fail_requests);
3917 evdns_log_fn = NULL;
3921 evdns_base_parse_hosts_line(struct evdns_base *base, char *line)
3924 static const char *const delims = " \t";
3925 char *const addr = strtok_r(line, delims, &strtok_state);
3926 char *hostname, *hash;
3927 struct sockaddr_storage ss;
3928 int socklen = sizeof(ss);
3929 ASSERT_LOCKED(base);
3931 #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state)
3933 if (!addr || *addr == '#')
3936 memset(&ss, 0, sizeof(ss));
3937 if (evutil_parse_sockaddr_port(addr, (struct sockaddr*)&ss, &socklen)<0)
3939 if (socklen > (int)sizeof(struct sockaddr_in6))
3942 if (sockaddr_getport((struct sockaddr*)&ss))
3945 while ((hostname = NEXT_TOKEN)) {
3946 struct hosts_entry *he;
3948 if ((hash = strchr(hostname, '#'))) {
3949 if (hash == hostname)
3954 namelen = strlen(hostname);
3956 he = mm_calloc(1, sizeof(struct hosts_entry)+namelen);
3959 EVUTIL_ASSERT(socklen <= (int)sizeof(he->addr));
3960 memcpy(&he->addr, &ss, socklen);
3961 memcpy(he->hostname, hostname, namelen+1);
3962 he->addrlen = socklen;
3964 TAILQ_INSERT_TAIL(&base->hostsdb, he, next);
3975 evdns_base_load_hosts_impl(struct evdns_base *base, const char *hosts_fname)
3977 char *str=NULL, *cp, *eol;
3981 ASSERT_LOCKED(base);
3983 if (hosts_fname == NULL ||
3984 (err = evutil_read_file(hosts_fname, &str, &len, 0)) < 0) {
3986 strlcpy(tmp, "127.0.0.1 localhost", sizeof(tmp));
3987 evdns_base_parse_hosts_line(base, tmp);
3988 strlcpy(tmp, "::1 localhost", sizeof(tmp));
3989 evdns_base_parse_hosts_line(base, tmp);
3990 return err ? -1 : 0;
3993 /* This will break early if there is a NUL in the hosts file.
3994 * Probably not a problem.*/
3997 eol = strchr(cp, '\n');
4001 evdns_base_parse_hosts_line(base, cp);
4004 evdns_base_parse_hosts_line(base, cp);
4014 evdns_base_load_hosts(struct evdns_base *base, const char *hosts_fname)
4018 base = current_base;
4020 res = evdns_base_load_hosts_impl(base, hosts_fname);
4025 /* A single request for a getaddrinfo, either v4 or v6. */
4026 struct getaddrinfo_subrequest {
4027 struct evdns_request *r;
4031 /* State data used to implement an in-progress getaddrinfo. */
4032 struct evdns_getaddrinfo_request {
4033 struct evdns_base *evdns_base;
4034 /* Copy of the modified 'hints' data that we'll use to build
4036 struct evutil_addrinfo hints;
4037 /* The callback to invoke when we're done */
4038 evdns_getaddrinfo_cb user_cb;
4039 /* User-supplied data to give to the callback. */
4041 /* The port to use when building sockaddrs. */
4043 /* The sub_request for an A record (if any) */
4044 struct getaddrinfo_subrequest ipv4_request;
4045 /* The sub_request for an AAAA record (if any) */
4046 struct getaddrinfo_subrequest ipv6_request;
4048 /* The cname result that we were told (if any) */
4051 /* If we have one request answered and one request still inflight,
4052 * then this field holds the answer from the first request... */
4053 struct evutil_addrinfo *pending_result;
4054 /* And this event is a timeout that will tell us to cancel the second
4055 * request if it's taking a long time. */
4056 struct event timeout;
4058 /* And this field holds the error code from the first request... */
4060 /* If this is set, the user canceled this request. */
4061 unsigned user_canceled : 1;
4062 /* If this is set, the user can no longer cancel this request; we're
4063 * just waiting for the free. */
4064 unsigned request_done : 1;
4067 /* Convert an evdns errors to the equivalent getaddrinfo error. */
4069 evdns_err_to_getaddrinfo_err(int e1)
4071 /* XXX Do this better! */
4072 if (e1 == DNS_ERR_NONE)
4074 else if (e1 == DNS_ERR_NOTEXIST)
4075 return EVUTIL_EAI_NONAME;
4077 return EVUTIL_EAI_FAIL;
4080 /* Return the more informative of two getaddrinfo errors. */
4082 getaddrinfo_merge_err(int e1, int e2)
4084 /* XXXX be cleverer here. */
4092 free_getaddrinfo_request(struct evdns_getaddrinfo_request *data)
4094 /* DO NOT CALL this if either of the requests is pending. Only once
4095 * both callbacks have been invoked is it safe to free the request */
4096 if (data->pending_result)
4097 evutil_freeaddrinfo(data->pending_result);
4098 if (data->cname_result)
4099 mm_free(data->cname_result);
4100 event_del(&data->timeout);
4106 add_cname_to_reply(struct evdns_getaddrinfo_request *data,
4107 struct evutil_addrinfo *ai)
4109 if (data->cname_result && ai) {
4110 ai->ai_canonname = data->cname_result;
4111 data->cname_result = NULL;
4115 /* Callback: invoked when one request in a mixed-format A/AAAA getaddrinfo
4116 * request has finished, but the other one took too long to answer. Pass
4117 * along the answer we got, and cancel the other request.
4120 evdns_getaddrinfo_timeout_cb(evutil_socket_t fd, short what, void *ptr)
4122 int v4_timedout = 0, v6_timedout = 0;
4123 struct evdns_getaddrinfo_request *data = ptr;
4125 /* Cancel any pending requests, and note which one */
4126 if (data->ipv4_request.r) {
4127 evdns_cancel_request(NULL, data->ipv4_request.r);
4129 EVDNS_LOCK(data->evdns_base);
4130 ++data->evdns_base->getaddrinfo_ipv4_timeouts;
4131 EVDNS_UNLOCK(data->evdns_base);
4133 if (data->ipv6_request.r) {
4134 evdns_cancel_request(NULL, data->ipv6_request.r);
4136 EVDNS_LOCK(data->evdns_base);
4137 ++data->evdns_base->getaddrinfo_ipv6_timeouts;
4138 EVDNS_UNLOCK(data->evdns_base);
4141 /* We only use this timeout callback when we have an answer for
4143 EVUTIL_ASSERT(!v4_timedout || !v6_timedout);
4145 /* Report the outcome of the other request that didn't time out. */
4146 if (data->pending_result) {
4147 add_cname_to_reply(data, data->pending_result);
4148 data->user_cb(0, data->pending_result, data->user_data);
4149 data->pending_result = NULL;
4151 int e = data->pending_error;
4153 e = EVUTIL_EAI_AGAIN;
4154 data->user_cb(e, NULL, data->user_data);
4157 if (!v4_timedout && !v6_timedout) {
4158 /* should be impossible? XXXX */
4159 free_getaddrinfo_request(data);
4164 evdns_getaddrinfo_set_timeout(struct evdns_base *evdns_base,
4165 struct evdns_getaddrinfo_request *data)
4167 return event_add(&data->timeout, &evdns_base->global_getaddrinfo_allow_skew);
4171 evdns_result_is_answer(int result)
4173 return (result != DNS_ERR_NOTIMPL && result != DNS_ERR_REFUSED &&
4174 result != DNS_ERR_SERVERFAILED && result != DNS_ERR_CANCEL);
4178 evdns_getaddrinfo_gotresolve(int result, char type, int count,
4179 int ttl, void *addresses, void *arg)
4182 struct getaddrinfo_subrequest *req = arg;
4183 struct getaddrinfo_subrequest *other_req;
4184 struct evdns_getaddrinfo_request *data;
4186 struct evutil_addrinfo *res;
4188 struct sockaddr_in sin;
4189 struct sockaddr_in6 sin6;
4190 struct sockaddr *sa;
4191 int socklen, addrlen;
4196 EVUTIL_ASSERT(req->type == DNS_IPv4_A || req->type == DNS_IPv6_AAAA);
4197 if (req->type == DNS_IPv4_A) {
4198 data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv4_request);
4199 other_req = &data->ipv6_request;
4201 data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv6_request);
4202 other_req = &data->ipv4_request;
4205 EVDNS_LOCK(data->evdns_base);
4206 if (evdns_result_is_answer(result)) {
4207 if (req->type == DNS_IPv4_A)
4208 ++data->evdns_base->getaddrinfo_ipv4_answered;
4210 ++data->evdns_base->getaddrinfo_ipv6_answered;
4212 user_canceled = data->user_canceled;
4213 if (other_req->r == NULL)
4214 data->request_done = 1;
4215 EVDNS_UNLOCK(data->evdns_base);
4219 if (result == DNS_ERR_CANCEL && ! user_canceled) {
4220 /* Internal cancel request from timeout or internal error.
4221 * we already answered the user. */
4222 if (other_req->r == NULL)
4223 free_getaddrinfo_request(data);
4227 if (result == DNS_ERR_NONE) {
4229 err = EVUTIL_EAI_NODATA;
4233 err = evdns_err_to_getaddrinfo_err(result);
4237 /* Looks like we got an error. */
4239 /* The other request is still working; maybe it will
4241 /* XXXX handle failure from set_timeout */
4242 evdns_getaddrinfo_set_timeout(data->evdns_base, data);
4243 data->pending_error = err;
4247 if (user_canceled) {
4248 data->user_cb(EVUTIL_EAI_CANCEL, NULL, data->user_data);
4249 } else if (data->pending_result) {
4250 /* If we have an answer waiting, and we weren't
4251 * canceled, ignore this error. */
4252 add_cname_to_reply(data, data->pending_result);
4253 data->user_cb(0, data->pending_result, data->user_data);
4254 data->pending_result = NULL;
4256 if (data->pending_error)
4257 err = getaddrinfo_merge_err(err,
4258 data->pending_error);
4259 data->user_cb(err, NULL, data->user_data);
4261 free_getaddrinfo_request(data);
4263 } else if (user_canceled) {
4265 /* The other request is still working; let it hit this
4266 * callback with EVUTIL_EAI_CANCEL callback and report
4270 data->user_cb(EVUTIL_EAI_CANCEL, NULL, data->user_data);
4271 free_getaddrinfo_request(data);
4275 /* Looks like we got some answers. We should turn them into addrinfos
4276 * and then either queue those or return them all. */
4277 EVUTIL_ASSERT(type == DNS_IPv4_A || type == DNS_IPv6_AAAA);
4279 if (type == DNS_IPv4_A) {
4280 memset(&sin, 0, sizeof(sin));
4281 sin.sin_family = AF_INET;
4282 sin.sin_port = htons(data->port);
4284 sa = (struct sockaddr *)&sin;
4285 socklen = sizeof(sin);
4287 addrp = &sin.sin_addr.s_addr;
4289 memset(&sin6, 0, sizeof(sin6));
4290 sin6.sin6_family = AF_INET6;
4291 sin6.sin6_port = htons(data->port);
4293 sa = (struct sockaddr *)&sin6;
4294 socklen = sizeof(sin6);
4296 addrp = &sin6.sin6_addr.s6_addr;
4300 for (i=0; i < count; ++i) {
4301 struct evutil_addrinfo *ai;
4302 memcpy(addrp, ((char*)addresses)+i*addrlen, addrlen);
4303 ai = evutil_new_addrinfo(sa, socklen, &data->hints);
4306 evdns_cancel_request(NULL, other_req->r);
4308 data->user_cb(EVUTIL_EAI_MEMORY, NULL, data->user_data);
4309 evutil_freeaddrinfo(res);
4311 if (other_req->r == NULL)
4312 free_getaddrinfo_request(data);
4315 res = evutil_addrinfo_append(res, ai);
4319 /* The other request is still in progress; wait for it */
4320 /* XXXX handle failure from set_timeout */
4321 evdns_getaddrinfo_set_timeout(data->evdns_base, data);
4322 data->pending_result = res;
4325 /* The other request is done or never started; append its
4326 * results (if any) and return them. */
4327 if (data->pending_result) {
4328 if (req->type == DNS_IPv4_A)
4329 res = evutil_addrinfo_append(res,
4330 data->pending_result);
4332 res = evutil_addrinfo_append(
4333 data->pending_result, res);
4334 data->pending_result = NULL;
4337 /* Call the user callback. */
4338 add_cname_to_reply(data, res);
4339 data->user_cb(0, res, data->user_data);
4342 free_getaddrinfo_request(data);
4346 static struct hosts_entry *
4347 find_hosts_entry(struct evdns_base *base, const char *hostname,
4348 struct hosts_entry *find_after)
4350 struct hosts_entry *e;
4353 e = TAILQ_NEXT(find_after, next);
4355 e = TAILQ_FIRST(&base->hostsdb);
4357 for (; e; e = TAILQ_NEXT(e, next)) {
4358 if (!evutil_ascii_strcasecmp(e->hostname, hostname))
4365 evdns_getaddrinfo_fromhosts(struct evdns_base *base,
4366 const char *nodename, struct evutil_addrinfo *hints, ev_uint16_t port,
4367 struct evutil_addrinfo **res)
4370 struct hosts_entry *e;
4371 struct evutil_addrinfo *ai=NULL;
4372 int f = hints->ai_family;
4375 for (e = find_hosts_entry(base, nodename, NULL); e;
4376 e = find_hosts_entry(base, nodename, e)) {
4377 struct evutil_addrinfo *ai_new;
4379 if ((e->addr.sa.sa_family == AF_INET && f == PF_INET6) ||
4380 (e->addr.sa.sa_family == AF_INET6 && f == PF_INET))
4382 ai_new = evutil_new_addrinfo(&e->addr.sa, e->addrlen, hints);
4387 sockaddr_setport(ai_new->ai_addr, port);
4388 ai = evutil_addrinfo_append(ai, ai_new);
4393 /* Note that we return an empty answer if we found entries for
4394 * this hostname but none were of the right address type. */
4399 evutil_freeaddrinfo(ai);
4404 struct evdns_getaddrinfo_request *
4405 evdns_getaddrinfo(struct evdns_base *dns_base,
4406 const char *nodename, const char *servname,
4407 const struct evutil_addrinfo *hints_in,
4408 evdns_getaddrinfo_cb cb, void *arg)
4410 struct evdns_getaddrinfo_request *data;
4411 struct evutil_addrinfo hints;
4412 struct evutil_addrinfo *res = NULL;
4418 dns_base = current_base;
4421 "Call to getaddrinfo_async with no "
4422 "evdns_base configured.");
4423 cb(EVUTIL_EAI_FAIL, NULL, arg); /* ??? better error? */
4428 /* If we _must_ answer this immediately, do so. */
4429 if ((hints_in && (hints_in->ai_flags & EVUTIL_AI_NUMERICHOST))) {
4431 err = evutil_getaddrinfo(nodename, servname, hints_in, &res);
4437 memcpy(&hints, hints_in, sizeof(hints));
4439 memset(&hints, 0, sizeof(hints));
4440 hints.ai_family = PF_UNSPEC;
4443 evutil_adjust_hints_for_addrconfig(&hints);
4445 /* Now try to see if we _can_ answer immediately. */
4446 /* (It would be nice to do this by calling getaddrinfo directly, with
4447 * AI_NUMERICHOST, on plaforms that have it, but we can't: there isn't
4448 * a reliable way to distinguish the "that wasn't a numeric host!" case
4449 * from any other EAI_NONAME cases.) */
4450 err = evutil_getaddrinfo_common(nodename, servname, &hints, &res, &port);
4451 if (err != EVUTIL_EAI_NEED_RESOLVE) {
4456 /* If there is an entry in the hosts file, we should give it now. */
4457 if (!evdns_getaddrinfo_fromhosts(dns_base, nodename, &hints, port, &res)) {
4462 /* Okay, things are serious now. We're going to need to actually
4465 data = mm_calloc(1,sizeof(struct evdns_getaddrinfo_request));
4467 cb(EVUTIL_EAI_MEMORY, NULL, arg);
4471 memcpy(&data->hints, &hints, sizeof(data->hints));
4472 data->port = (ev_uint16_t)port;
4473 data->ipv4_request.type = DNS_IPv4_A;
4474 data->ipv6_request.type = DNS_IPv6_AAAA;
4476 data->user_data = arg;
4477 data->evdns_base = dns_base;
4479 want_cname = (hints.ai_flags & EVUTIL_AI_CANONNAME);
4481 /* If we are asked for a PF_UNSPEC address, we launch two requests in
4482 * parallel: one for an A address and one for an AAAA address. We
4483 * can't send just one request, since many servers only answer one
4484 * question per DNS request.
4486 * Once we have the answer to one request, we allow for a short
4487 * timeout before we report it, to see if the other one arrives. If
4488 * they both show up in time, then we report both the answers.
4490 * If too many addresses of one type time out or fail, we should stop
4491 * launching those requests. (XXX we don't do that yet.)
4494 if (hints.ai_family != PF_INET6) {
4495 log(EVDNS_LOG_DEBUG, "Sending request for %s on ipv4 as %p",
4496 nodename, &data->ipv4_request);
4498 data->ipv4_request.r = evdns_base_resolve_ipv4(dns_base,
4499 nodename, 0, evdns_getaddrinfo_gotresolve,
4500 &data->ipv4_request);
4502 data->ipv4_request.r->current_req->put_cname_in_ptr =
4503 &data->cname_result;
4505 if (hints.ai_family != PF_INET) {
4506 log(EVDNS_LOG_DEBUG, "Sending request for %s on ipv6 as %p",
4507 nodename, &data->ipv6_request);
4509 data->ipv6_request.r = evdns_base_resolve_ipv6(dns_base,
4510 nodename, 0, evdns_getaddrinfo_gotresolve,
4511 &data->ipv6_request);
4513 data->ipv6_request.r->current_req->put_cname_in_ptr =
4514 &data->cname_result;
4517 evtimer_assign(&data->timeout, dns_base->event_base,
4518 evdns_getaddrinfo_timeout_cb, data);
4520 if (data->ipv4_request.r || data->ipv6_request.r) {
4524 cb(EVUTIL_EAI_FAIL, NULL, arg);
4530 evdns_getaddrinfo_cancel(struct evdns_getaddrinfo_request *data)
4532 EVDNS_LOCK(data->evdns_base);
4533 if (data->request_done) {
4534 EVDNS_UNLOCK(data->evdns_base);
4537 event_del(&data->timeout);
4538 data->user_canceled = 1;
4539 if (data->ipv4_request.r)
4540 evdns_cancel_request(data->evdns_base, data->ipv4_request.r);
4541 if (data->ipv6_request.r)
4542 evdns_cancel_request(data->evdns_base, data->ipv6_request.r);
4543 EVDNS_UNLOCK(data->evdns_base);