1 /* Copyright 2006-2007 Niels Provos
2 * Copyright 2007-2012 Nick Mathewson and Niels Provos
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * 3. The name of the author may not be used to endorse or promote products
13 * derived from this software without specific prior written permission.
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 /* Based on software by Adam Langly. Adam's original message:
30 * Adam Langley <agl@imperialviolet.org>
31 * http://www.imperialviolet.org/eventdns.html
34 * This software is Public Domain. To view a copy of the public domain dedication,
35 * visit http://creativecommons.org/licenses/publicdomain/ or send a letter to
36 * Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA.
38 * I ask and expect, but do not require, that all derivative works contain an
39 * attribution similar to:
40 * Parts developed by Adam Langley <agl@imperialviolet.org>
42 * You may wish to replace the word "Parts" with something else depending on
43 * the amount of original code.
45 * (Derivative works does not include programs which link against, run or include
46 * the source verbatim in their source distributions)
51 #include "event2/event-config.h"
52 #include "evconfig-private.h"
54 #include <sys/types.h>
56 #ifndef _FORTIFY_SOURCE
57 #define _FORTIFY_SOURCE 3
62 #ifdef EVENT__HAVE_SYS_TIME_H
65 #ifdef EVENT__HAVE_STDINT_H
71 #ifdef EVENT__HAVE_UNISTD_H
83 #define _WIN32_IE 0x400
88 #include "event2/dns.h"
89 #include "event2/dns_struct.h"
90 #include "event2/dns_compat.h"
91 #include "event2/util.h"
92 #include "event2/event.h"
93 #include "event2/event_struct.h"
94 #include "event2/thread.h"
96 #include "defer-internal.h"
97 #include "log-internal.h"
98 #include "mm-internal.h"
99 #include "strlcpy-internal.h"
100 #include "ipv6-internal.h"
101 #include "util-internal.h"
102 #include "evthread-internal.h"
105 #include <winsock2.h>
107 #include <iphlpapi.h>
110 #include <sys/socket.h>
111 #include <netinet/in.h>
112 #include <arpa/inet.h>
115 #ifdef EVENT__HAVE_NETINET_IN6_H
116 #include <netinet/in6.h>
119 #define EVDNS_LOG_DEBUG EVENT_LOG_DEBUG
120 #define EVDNS_LOG_WARN EVENT_LOG_WARN
121 #define EVDNS_LOG_MSG EVENT_LOG_MSG
123 #ifndef HOST_NAME_MAX
124 #define HOST_NAME_MAX 255
130 #define MIN(a,b) ((a)<(b)?(a):(b))
132 #define ASSERT_VALID_REQUEST(req) \
133 EVUTIL_ASSERT((req)->handle && (req)->handle->current_req == (req))
135 #define u64 ev_uint64_t
136 #define u32 ev_uint32_t
137 #define u16 ev_uint16_t
138 #define u8 ev_uint8_t
140 /* maximum number of addresses from a single packet */
141 /* that we bother recording */
142 #define MAX_V4_ADDRS 32
143 #define MAX_V6_ADDRS 32
146 #define TYPE_A EVDNS_TYPE_A
148 #define TYPE_PTR EVDNS_TYPE_PTR
149 #define TYPE_SOA EVDNS_TYPE_SOA
150 #define TYPE_AAAA EVDNS_TYPE_AAAA
152 #define CLASS_INET EVDNS_CLASS_INET
154 /* Persistent handle. We keep this separate from 'struct request' since we
155 * need some object to last for as long as an evdns_request is outstanding so
156 * that it can be canceled, whereas a search request can lead to multiple
157 * 'struct request' instances being created over its lifetime. */
158 struct evdns_request {
159 struct request *current_req;
160 struct evdns_base *base;
162 int pending_cb; /* Waiting for its callback to be invoked; not
163 * owned by event base any more. */
165 /* elements used by the searching code */
167 struct search_state *search_state;
168 char *search_origname; /* needs to be free()ed */
173 u8 *request; /* the dns packet data */
174 u8 request_type; /* TYPE_PTR or TYPE_A or TYPE_AAAA */
175 unsigned int request_len;
177 int tx_count; /* the number of times that this packet has been sent */
178 void *user_pointer; /* the pointer given to us for this request */
179 evdns_callback_type user_callback;
180 struct nameserver *ns; /* the server which we last sent it */
182 /* these objects are kept in a circular list */
183 /* XXX We could turn this into a CIRCLEQ. */
184 struct request *next, *prev;
186 struct event timeout_event;
188 u16 trans_id; /* the transaction id */
189 unsigned request_appended :1; /* true if the request pointer is data which follows this struct */
190 unsigned transmit_me :1; /* needs to be transmitted */
192 /* XXXX This is a horrible hack. */
193 char **put_cname_in_ptr; /* store the cname here if we get one. */
195 struct evdns_base *base;
197 struct evdns_request *handle;
202 unsigned int have_answer : 1;
206 u32 addresses[MAX_V4_ADDRS];
210 struct in6_addr addresses[MAX_V6_ADDRS];
213 char name[HOST_NAME_MAX];
219 evutil_socket_t socket; /* a connected UDP socket */
220 struct sockaddr_storage address;
221 ev_socklen_t addrlen;
222 int failed_times; /* number of times which we have given this server a chance */
223 int timedout; /* number of times in a row a request has timed out */
225 /* these objects are kept in a circular list */
226 struct nameserver *next, *prev;
227 struct event timeout_event; /* used to keep the timeout for */
228 /* when we next probe this server. */
229 /* Valid if state == 0 */
230 /* Outstanding probe request for this nameserver, if any */
231 struct evdns_request *probe_request;
232 char state; /* zero if we think that this server is down */
233 char choked; /* true if we have an EAGAIN from this server's socket */
234 char write_waiting; /* true if we are waiting for EV_WRITE events */
235 struct evdns_base *base;
237 /* Number of currently inflight requests: used
238 * to track when we should add/del the event. */
239 int requests_inflight;
243 /* Represents a local port where we're listening for DNS requests. Right now, */
244 /* only UDP is supported. */
245 struct evdns_server_port {
246 evutil_socket_t socket; /* socket we use to read queries and write replies. */
247 int refcnt; /* reference count. */
248 char choked; /* Are we currently blocked from writing? */
249 char closing; /* Are we trying to close this port, pending writes? */
250 evdns_request_callback_fn_type user_callback; /* Fn to handle requests */
251 void *user_data; /* Opaque pointer passed to user_callback */
252 struct event event; /* Read/write event */
253 /* circular list of replies that we want to write. */
254 struct server_request *pending_replies;
255 struct event_base *event_base;
257 #ifndef EVENT__DISABLE_THREAD_SUPPORT
262 /* Represents part of a reply being built. (That is, a single RR.) */
263 struct server_reply_item {
264 struct server_reply_item *next; /* next item in sequence. */
265 char *name; /* name part of the RR */
266 u16 type; /* The RR type */
267 u16 class; /* The RR class (usually CLASS_INET) */
268 u32 ttl; /* The RR TTL */
269 char is_name; /* True iff data is a label */
270 u16 datalen; /* Length of data; -1 if data is a label */
271 void *data; /* The contents of the RR */
274 /* Represents a request that we've received as a DNS server, and holds */
275 /* the components of the reply as we're constructing it. */
276 struct server_request {
277 /* Pointers to the next and previous entries on the list of replies */
278 /* that we're waiting to write. Only set if we have tried to respond */
279 /* and gotten EAGAIN. */
280 struct server_request *next_pending;
281 struct server_request *prev_pending;
283 u16 trans_id; /* Transaction id. */
284 struct evdns_server_port *port; /* Which port received this request on? */
285 struct sockaddr_storage addr; /* Where to send the response */
286 ev_socklen_t addrlen; /* length of addr */
288 int n_answer; /* how many answer RRs have been set? */
289 int n_authority; /* how many authority RRs have been set? */
290 int n_additional; /* how many additional RRs have been set? */
292 struct server_reply_item *answer; /* linked list of answer RRs */
293 struct server_reply_item *authority; /* linked list of authority RRs */
294 struct server_reply_item *additional; /* linked list of additional RRs */
296 /* Constructed response. Only set once we're ready to send a reply. */
297 /* Once this is set, the RR fields are cleared, and no more should be set. */
301 /* Caller-visible fields: flags, questions. */
302 struct evdns_server_request base;
306 /* An array of n_req_heads circular lists for inflight requests.
307 * Each inflight request req is in req_heads[req->trans_id % n_req_heads].
309 struct request **req_heads;
310 /* A circular list of requests that we're waiting to send, but haven't
311 * sent yet because there are too many requests inflight */
312 struct request *req_waiting_head;
313 /* A circular list of nameservers. */
314 struct nameserver *server_head;
317 struct event_base *event_base;
319 /* The number of good nameservers that we have */
320 int global_good_nameservers;
322 /* inflight requests are contained in the req_head list */
323 /* and are actually going out across the network */
324 int global_requests_inflight;
325 /* requests which aren't inflight are in the waiting list */
326 /* and are counted here */
327 int global_requests_waiting;
329 int global_max_requests_inflight;
331 struct timeval global_timeout; /* 5 seconds by default */
332 int global_max_reissues; /* a reissue occurs when we get some errors from the server */
333 int global_max_retransmits; /* number of times we'll retransmit a request which timed out */
334 /* number of timeouts in a row before we consider this server to be down */
335 int global_max_nameserver_timeout;
336 /* true iff we will use the 0x20 hack to prevent poisoning attacks. */
337 int global_randomize_case;
339 /* The first time that a nameserver fails, how long do we wait before
340 * probing to see if it has returned? */
341 struct timeval global_nameserver_probe_initial_timeout;
343 /** Port to bind to for outgoing DNS packets. */
344 struct sockaddr_storage global_outgoing_address;
345 /** ev_socklen_t for global_outgoing_address. 0 if it isn't set. */
346 ev_socklen_t global_outgoing_addrlen;
348 struct timeval global_getaddrinfo_allow_skew;
353 int getaddrinfo_ipv4_timeouts;
354 int getaddrinfo_ipv6_timeouts;
355 int getaddrinfo_ipv4_answered;
356 int getaddrinfo_ipv6_answered;
358 struct search_state *global_search_state;
360 TAILQ_HEAD(hosts_list, hosts_entry) hostsdb;
362 #ifndef EVENT__DISABLE_THREAD_SUPPORT
366 int disable_when_inactive;
370 TAILQ_ENTRY(hosts_entry) next;
373 struct sockaddr_in sin;
374 struct sockaddr_in6 sin6;
380 static struct evdns_base *current_base = NULL;
383 evdns_get_global_base(void)
388 /* Given a pointer to an evdns_server_request, get the corresponding */
389 /* server_request. */
390 #define TO_SERVER_REQUEST(base_ptr) \
391 ((struct server_request*) \
392 (((char*)(base_ptr) - evutil_offsetof(struct server_request, base))))
394 #define REQ_HEAD(base, id) ((base)->req_heads[id % (base)->n_req_heads])
396 static struct nameserver *nameserver_pick(struct evdns_base *base);
397 static void evdns_request_insert(struct request *req, struct request **head);
398 static void evdns_request_remove(struct request *req, struct request **head);
399 static void nameserver_ready_callback(evutil_socket_t fd, short events, void *arg);
400 static int evdns_transmit(struct evdns_base *base);
401 static int evdns_request_transmit(struct request *req);
402 static void nameserver_send_probe(struct nameserver *const ns);
403 static void search_request_finished(struct evdns_request *const);
404 static int search_try_next(struct evdns_request *const req);
405 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);
406 static void evdns_requests_pump_waiting_queue(struct evdns_base *base);
407 static u16 transaction_id_pick(struct evdns_base *base);
408 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);
409 static void request_submit(struct request *const req);
411 static int server_request_free(struct server_request *req);
412 static void server_request_free_answers(struct server_request *req);
413 static void server_port_free(struct evdns_server_port *port);
414 static void server_port_ready_callback(evutil_socket_t fd, short events, void *arg);
415 static int evdns_base_resolv_conf_parse_impl(struct evdns_base *base, int flags, const char *const filename);
416 static int evdns_base_set_option_impl(struct evdns_base *base,
417 const char *option, const char *val, int flags);
418 static void evdns_base_free_and_unlock(struct evdns_base *base, int fail_requests);
419 static void evdns_request_timeout_callback(evutil_socket_t fd, short events, void *arg);
421 static int strtoint(const char *const str);
423 #ifdef EVENT__DISABLE_THREAD_SUPPORT
424 #define EVDNS_LOCK(base) EVUTIL_NIL_STMT_
425 #define EVDNS_UNLOCK(base) EVUTIL_NIL_STMT_
426 #define ASSERT_LOCKED(base) EVUTIL_NIL_STMT_
428 #define EVDNS_LOCK(base) \
429 EVLOCK_LOCK((base)->lock, 0)
430 #define EVDNS_UNLOCK(base) \
431 EVLOCK_UNLOCK((base)->lock, 0)
432 #define ASSERT_LOCKED(base) \
433 EVLOCK_ASSERT_LOCKED((base)->lock)
436 static evdns_debug_log_fn_type evdns_log_fn = NULL;
439 evdns_set_log_fn(evdns_debug_log_fn_type fn)
445 #define EVDNS_LOG_CHECK __attribute__ ((format(printf, 2, 3)))
447 #define EVDNS_LOG_CHECK
450 static void evdns_log_(int severity, const char *fmt, ...) EVDNS_LOG_CHECK;
452 evdns_log_(int severity, const char *fmt, ...)
458 int is_warn = (severity == EVDNS_LOG_WARN);
459 evutil_vsnprintf(buf, sizeof(buf), fmt, args);
460 evdns_log_fn(is_warn, buf);
462 event_logv_(severity, NULL, fmt, args);
467 #define log evdns_log_
469 /* This walks the list of inflight requests to find the */
470 /* one with a matching transaction id. Returns NULL on */
472 static struct request *
473 request_find_from_trans_id(struct evdns_base *base, u16 trans_id) {
474 struct request *req = REQ_HEAD(base, trans_id);
475 struct request *const started_at = req;
481 if (req->trans_id == trans_id) return req;
483 } while (req != started_at);
489 /* a libevent callback function which is called when a nameserver */
490 /* has gone down and we want to test if it has came back to life yet */
492 nameserver_prod_callback(evutil_socket_t fd, short events, void *arg) {
493 struct nameserver *const ns = (struct nameserver *) arg;
497 EVDNS_LOCK(ns->base);
498 nameserver_send_probe(ns);
499 EVDNS_UNLOCK(ns->base);
502 /* a libevent callback which is called when a nameserver probe (to see if */
503 /* it has come back to life) times out. We increment the count of failed_times */
504 /* and wait longer to send the next probe packet. */
506 nameserver_probe_failed(struct nameserver *const ns) {
507 struct timeval timeout;
510 ASSERT_LOCKED(ns->base);
511 (void) evtimer_del(&ns->timeout_event);
512 if (ns->state == 1) {
513 /* This can happen if the nameserver acts in a way which makes us mark */
514 /* it as bad and then starts sending good replies. */
518 #define MAX_PROBE_TIMEOUT 3600
519 #define TIMEOUT_BACKOFF_FACTOR 3
521 memcpy(&timeout, &ns->base->global_nameserver_probe_initial_timeout,
522 sizeof(struct timeval));
523 for (i=ns->failed_times; i > 0 && timeout.tv_sec < MAX_PROBE_TIMEOUT; --i) {
524 timeout.tv_sec *= TIMEOUT_BACKOFF_FACTOR;
525 timeout.tv_usec *= TIMEOUT_BACKOFF_FACTOR;
526 if (timeout.tv_usec > 1000000) {
527 timeout.tv_sec += timeout.tv_usec / 1000000;
528 timeout.tv_usec %= 1000000;
531 if (timeout.tv_sec > MAX_PROBE_TIMEOUT) {
532 timeout.tv_sec = MAX_PROBE_TIMEOUT;
538 if (evtimer_add(&ns->timeout_event, &timeout) < 0) {
541 "Error from libevent when adding timer event for %s",
542 evutil_format_sockaddr_port_(
543 (struct sockaddr *)&ns->address,
544 addrbuf, sizeof(addrbuf)));
549 request_swap_ns(struct request *req, struct nameserver *ns) {
550 if (ns && req->ns != ns) {
551 EVUTIL_ASSERT(req->ns->requests_inflight > 0);
552 req->ns->requests_inflight--;
553 ns->requests_inflight++;
559 /* called when a nameserver has been deemed to have failed. For example, too */
560 /* many packets have timed out etc */
562 nameserver_failed(struct nameserver *const ns, const char *msg) {
563 struct request *req, *started_at;
564 struct evdns_base *base = ns->base;
569 /* if this nameserver has already been marked as failed */
570 /* then don't do anything */
571 if (!ns->state) return;
573 log(EVDNS_LOG_MSG, "Nameserver %s has failed: %s",
574 evutil_format_sockaddr_port_(
575 (struct sockaddr *)&ns->address,
576 addrbuf, sizeof(addrbuf)),
579 base->global_good_nameservers--;
580 EVUTIL_ASSERT(base->global_good_nameservers >= 0);
581 if (base->global_good_nameservers == 0) {
582 log(EVDNS_LOG_MSG, "All nameservers have failed");
586 ns->failed_times = 1;
588 if (evtimer_add(&ns->timeout_event,
589 &base->global_nameserver_probe_initial_timeout) < 0) {
591 "Error from libevent when adding timer event for %s",
592 evutil_format_sockaddr_port_(
593 (struct sockaddr *)&ns->address,
594 addrbuf, sizeof(addrbuf)));
598 /* walk the list of inflight requests to see if any can be reassigned to */
599 /* a different server. Requests in the waiting queue don't have a */
600 /* nameserver assigned yet */
602 /* if we don't have *any* good nameservers then there's no point */
603 /* trying to reassign requests to one */
604 if (!base->global_good_nameservers) return;
606 for (i = 0; i < base->n_req_heads; ++i) {
607 req = started_at = base->req_heads[i];
610 if (req->tx_count == 0 && req->ns == ns) {
611 /* still waiting to go out, can be moved */
612 /* to another server */
613 request_swap_ns(req, nameserver_pick(base));
616 } while (req != started_at);
622 nameserver_up(struct nameserver *const ns)
625 ASSERT_LOCKED(ns->base);
626 if (ns->state) return;
627 log(EVDNS_LOG_MSG, "Nameserver %s is back up",
628 evutil_format_sockaddr_port_(
629 (struct sockaddr *)&ns->address,
630 addrbuf, sizeof(addrbuf)));
631 evtimer_del(&ns->timeout_event);
632 if (ns->probe_request) {
633 evdns_cancel_request(ns->base, ns->probe_request);
634 ns->probe_request = NULL;
637 ns->failed_times = 0;
639 ns->base->global_good_nameservers++;
643 request_trans_id_set(struct request *const req, const u16 trans_id) {
644 req->trans_id = trans_id;
645 *((u16 *) req->request) = htons(trans_id);
648 /* Called to remove a request from a list and dealloc it. */
649 /* head is a pointer to the head of the list it should be */
650 /* removed from or NULL if the request isn't in a list. */
651 /* when free_handle is one, free the handle as well. */
653 request_finished(struct request *const req, struct request **head, int free_handle) {
654 struct evdns_base *base = req->base;
655 int was_inflight = (head != &base->req_waiting_head);
657 ASSERT_VALID_REQUEST(req);
660 evdns_request_remove(req, head);
662 log(EVDNS_LOG_DEBUG, "Removing timeout for request %p", req);
664 evtimer_del(&req->timeout_event);
665 base->global_requests_inflight--;
666 req->ns->requests_inflight--;
668 base->global_requests_waiting--;
670 /* it was initialized during request_new / evtimer_assign */
671 event_debug_unassign(&req->timeout_event);
674 req->ns->requests_inflight == 0 &&
675 req->base->disable_when_inactive) {
676 event_del(&req->ns->event);
677 evtimer_del(&req->ns->timeout_event);
680 if (!req->request_appended) {
681 /* need to free the request data on it's own */
682 mm_free(req->request);
684 /* the request data is appended onto the header */
685 /* so everything gets free()ed when we: */
689 EVUTIL_ASSERT(req->handle->current_req == req);
692 search_request_finished(req->handle);
693 req->handle->current_req = NULL;
694 if (! req->handle->pending_cb) {
695 /* If we're planning to run the callback,
696 * don't free the handle until later. */
697 mm_free(req->handle);
699 req->handle = NULL; /* If we have a bug, let's crash
702 req->handle->current_req = NULL;
708 evdns_requests_pump_waiting_queue(base);
712 /* This is called when a server returns a funny error code. */
713 /* We try the request again with another server. */
717 /* 1 failed/reissue is pointless */
719 request_reissue(struct request *req) {
720 const struct nameserver *const last_ns = req->ns;
721 ASSERT_LOCKED(req->base);
722 ASSERT_VALID_REQUEST(req);
723 /* the last nameserver should have been marked as failing */
724 /* by the caller of this function, therefore pick will try */
725 /* not to return it */
726 request_swap_ns(req, nameserver_pick(req->base));
727 if (req->ns == last_ns) {
728 /* ... but pick did return it */
729 /* not a lot of point in trying again with the */
734 req->reissue_count++;
736 req->transmit_me = 1;
741 /* this function looks for space on the inflight queue and promotes */
742 /* requests from the waiting queue if it can. */
745 /* add return code, see at nameserver_pick() and other functions. */
747 evdns_requests_pump_waiting_queue(struct evdns_base *base) {
749 while (base->global_requests_inflight < base->global_max_requests_inflight &&
750 base->global_requests_waiting) {
753 EVUTIL_ASSERT(base->req_waiting_head);
754 req = base->req_waiting_head;
756 req->ns = nameserver_pick(base);
760 /* move a request from the waiting queue to the inflight queue */
761 req->ns->requests_inflight++;
763 evdns_request_remove(req, &base->req_waiting_head);
765 base->global_requests_waiting--;
766 base->global_requests_inflight++;
768 request_trans_id_set(req, transaction_id_pick(base));
770 evdns_request_insert(req, &REQ_HEAD(base, req->trans_id));
771 evdns_request_transmit(req);
772 evdns_transmit(base);
776 /* TODO(nickm) document */
777 struct deferred_reply_callback {
778 struct event_callback deferred;
779 struct evdns_request *handle;
784 evdns_callback_type user_callback;
789 reply_run_callback(struct event_callback *d, void *user_pointer)
791 struct deferred_reply_callback *cb =
792 EVUTIL_UPCAST(d, struct deferred_reply_callback, deferred);
794 switch (cb->request_type) {
797 cb->user_callback(DNS_ERR_NONE, DNS_IPv4_A,
798 cb->reply.data.a.addrcount, cb->ttl,
799 cb->reply.data.a.addresses,
802 cb->user_callback(cb->err, 0, 0, cb->ttl, NULL, user_pointer);
805 if (cb->have_reply) {
806 char *name = cb->reply.data.ptr.name;
807 cb->user_callback(DNS_ERR_NONE, DNS_PTR, 1, cb->ttl,
808 &name, user_pointer);
810 cb->user_callback(cb->err, 0, 0, cb->ttl, NULL, user_pointer);
815 cb->user_callback(DNS_ERR_NONE, DNS_IPv6_AAAA,
816 cb->reply.data.aaaa.addrcount, cb->ttl,
817 cb->reply.data.aaaa.addresses,
820 cb->user_callback(cb->err, 0, 0, cb->ttl, NULL, user_pointer);
826 if (cb->handle && cb->handle->pending_cb) {
834 reply_schedule_callback(struct request *const req, u32 ttl, u32 err, struct reply *reply)
836 struct deferred_reply_callback *d = mm_calloc(1, sizeof(*d));
839 event_warn("%s: Couldn't allocate space for deferred callback.",
844 ASSERT_LOCKED(req->base);
846 d->request_type = req->request_type;
847 d->user_callback = req->user_callback;
852 memcpy(&d->reply, reply, sizeof(struct reply));
856 req->handle->pending_cb = 1;
857 d->handle = req->handle;
860 event_deferred_cb_init_(
862 event_get_priority(&req->timeout_event),
865 event_deferred_cb_schedule_(
866 req->base->event_base,
871 #define _QR_MASK 0x8000U
872 #define _OP_MASK 0x7800U
873 #define _AA_MASK 0x0400U
874 #define _TC_MASK 0x0200U
875 #define _RD_MASK 0x0100U
876 #define _RA_MASK 0x0080U
877 #define _Z_MASK 0x0040U
878 #define _AD_MASK 0x0020U
879 #define _CD_MASK 0x0010U
880 #define _RCODE_MASK 0x000fU
881 #define _Z_MASK_DEPRECATED 0x0070U
883 /* this processes a parsed reply packet */
885 reply_handle(struct request *const req, u16 flags, u32 ttl, struct reply *reply) {
888 static const int error_codes[] = {
889 DNS_ERR_FORMAT, DNS_ERR_SERVERFAILED, DNS_ERR_NOTEXIST,
890 DNS_ERR_NOTIMPL, DNS_ERR_REFUSED
893 ASSERT_LOCKED(req->base);
894 ASSERT_VALID_REQUEST(req);
896 if (flags & (_RCODE_MASK | _TC_MASK) || !reply || !reply->have_answer) {
897 /* there was an error */
898 if (flags & _TC_MASK) {
899 error = DNS_ERR_TRUNCATED;
900 } else if (flags & _RCODE_MASK) {
901 u16 error_code = (flags & _RCODE_MASK) - 1;
902 if (error_code > 4) {
903 error = DNS_ERR_UNKNOWN;
905 error = error_codes[error_code];
907 } else if (reply && !reply->have_answer) {
908 error = DNS_ERR_NODATA;
910 error = DNS_ERR_UNKNOWN;
914 case DNS_ERR_NOTIMPL:
915 case DNS_ERR_REFUSED:
916 /* we regard these errors as marking a bad nameserver */
917 if (req->reissue_count < req->base->global_max_reissues) {
919 evutil_snprintf(msg, sizeof(msg), "Bad response %d (%s)",
920 error, evdns_err_to_string(error));
921 nameserver_failed(req->ns, msg);
922 if (!request_reissue(req)) return;
925 case DNS_ERR_SERVERFAILED:
926 /* rcode 2 (servfailed) sometimes means "we
927 * are broken" and sometimes (with some binds)
928 * means "that request was very confusing."
929 * Treat this as a timeout, not a failure.
931 log(EVDNS_LOG_DEBUG, "Got a SERVERFAILED from nameserver"
932 "at %s; will allow the request to time out.",
933 evutil_format_sockaddr_port_(
934 (struct sockaddr *)&req->ns->address,
935 addrbuf, sizeof(addrbuf)));
936 /* Call the timeout function */
937 evdns_request_timeout_callback(0, 0, req);
940 /* we got a good reply from the nameserver: it is up. */
941 if (req->handle == req->ns->probe_request) {
942 /* Avoid double-free */
943 req->ns->probe_request = NULL;
946 nameserver_up(req->ns);
949 if (req->handle->search_state &&
950 req->request_type != TYPE_PTR) {
951 /* if we have a list of domains to search in,
952 * try the next one */
953 if (!search_try_next(req->handle)) {
954 /* a new request was issued so this
955 * request is finished and */
956 /* the user callback will be made when
957 * that request (or a */
958 /* child of it) finishes. */
963 /* all else failed. Pass the failure up */
964 reply_schedule_callback(req, ttl, error, NULL);
965 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1);
967 /* all ok, tell the user */
968 reply_schedule_callback(req, ttl, 0, reply);
969 if (req->handle == req->ns->probe_request)
970 req->ns->probe_request = NULL; /* Avoid double-free */
971 nameserver_up(req->ns);
972 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1);
977 name_parse(u8 *packet, int length, int *idx, char *name_out, int name_out_len) {
981 #define GET32(x) do { if (j + 4 > length) goto err; memcpy(&t32_, packet + j, 4); j += 4; x = ntohl(t32_); } while (0)
982 #define GET16(x) do { if (j + 2 > length) goto err; memcpy(&t_, packet + j, 2); j += 2; x = ntohs(t_); } while (0)
983 #define GET8(x) do { if (j >= length) goto err; x = packet[j++]; } while (0)
986 const char *const end = name_out + name_out_len;
988 /* Normally, names are a series of length prefixed strings terminated */
989 /* with a length of 0 (the lengths are u8's < 63). */
990 /* However, the length can start with a pair of 1 bits and that */
991 /* means that the next 14 bits are a pointer within the current */
997 if (!label_len) break;
998 if (label_len & 0xc0) {
1001 if (name_end < 0) name_end = j;
1002 j = (((int)label_len & 0x3f) << 8) + ptr_low;
1003 /* Make sure that the target offset is in-bounds. */
1004 if (j < 0 || j >= length) return -1;
1005 /* If we've jumped more times than there are characters in the
1006 * message, we must have a loop. */
1007 if (++ptr_count > length) return -1;
1010 if (label_len > 63) return -1;
1011 if (cp != name_out) {
1012 if (cp + 1 >= end) return -1;
1015 if (cp + label_len >= end) return -1;
1016 if (j + label_len > length) return -1;
1017 memcpy(cp, packet + j, label_len);
1021 if (cp >= end) return -1;
1032 /* parses a raw request from a nameserver */
1034 reply_parse(struct evdns_base *base, u8 *packet, int length) {
1035 int j = 0, k = 0; /* index into packet */
1036 u16 t_; /* used by the macros */
1037 u32 t32_; /* used by the macros */
1038 char tmp_name[256], cmp_name[256]; /* used by the macros */
1039 int name_matches = 0;
1041 u16 trans_id, questions, answers, authority, additional, datalength;
1043 u32 ttl, ttl_r = 0xffffffff;
1045 struct request *req = NULL;
1048 ASSERT_LOCKED(base);
1056 (void) authority; /* suppress "unused variable" warnings. */
1057 (void) additional; /* suppress "unused variable" warnings. */
1059 req = request_find_from_trans_id(base, trans_id);
1060 if (!req) return -1;
1061 EVUTIL_ASSERT(req->base == base);
1063 memset(&reply, 0, sizeof(reply));
1065 /* If it's not an answer, it doesn't correspond to any request. */
1066 if (!(flags & _QR_MASK)) return -1; /* must be an answer */
1067 if ((flags & (_RCODE_MASK|_TC_MASK)) && (flags & (_RCODE_MASK|_TC_MASK)) != DNS_ERR_NOTEXIST) {
1068 /* there was an error and it's not NXDOMAIN */
1071 /* if (!answers) return; */ /* must have an answer of some form */
1073 /* This macro skips a name in the DNS reply. */
1075 do { tmp_name[0] = '\0'; \
1076 if (name_parse(packet, length, &j, tmp_name, \
1077 sizeof(tmp_name))<0) \
1081 reply.type = req->request_type;
1083 /* skip over each question in the reply */
1084 for (i = 0; i < questions; ++i) {
1085 /* the question looks like
1086 * <label:name><u16:type><u16:class>
1091 if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name)) < 0)
1093 if (name_parse(req->request, req->request_len, &k,
1094 cmp_name, sizeof(cmp_name))<0)
1096 if (!base->global_randomize_case) {
1097 if (strcmp(tmp_name, cmp_name) == 0)
1100 if (evutil_ascii_strcasecmp(tmp_name, cmp_name) == 0)
1112 /* now we have the answer section which looks like
1113 * <label:name><u16:type><u16:class><u32:ttl><u16:len><data...>
1116 for (i = 0; i < answers; ++i) {
1125 if (type == TYPE_A && class == CLASS_INET) {
1126 int addrcount, addrtocopy;
1127 if (req->request_type != TYPE_A) {
1128 j += datalength; continue;
1130 if ((datalength & 3) != 0) /* not an even number of As. */
1132 addrcount = datalength >> 2;
1133 addrtocopy = MIN(MAX_V4_ADDRS - reply.data.a.addrcount, (unsigned)addrcount);
1135 ttl_r = MIN(ttl_r, ttl);
1136 /* we only bother with the first four addresses. */
1137 if (j + 4*addrtocopy > length) goto err;
1138 memcpy(&reply.data.a.addresses[reply.data.a.addrcount],
1139 packet + j, 4*addrtocopy);
1141 reply.data.a.addrcount += addrtocopy;
1142 reply.have_answer = 1;
1143 if (reply.data.a.addrcount == MAX_V4_ADDRS) break;
1144 } else if (type == TYPE_PTR && class == CLASS_INET) {
1145 if (req->request_type != TYPE_PTR) {
1146 j += datalength; continue;
1148 if (name_parse(packet, length, &j, reply.data.ptr.name,
1149 sizeof(reply.data.ptr.name))<0)
1151 ttl_r = MIN(ttl_r, ttl);
1152 reply.have_answer = 1;
1154 } else if (type == TYPE_CNAME) {
1155 char cname[HOST_NAME_MAX];
1156 if (!req->put_cname_in_ptr || *req->put_cname_in_ptr) {
1157 j += datalength; continue;
1159 if (name_parse(packet, length, &j, cname,
1162 *req->put_cname_in_ptr = mm_strdup(cname);
1163 } else if (type == TYPE_AAAA && class == CLASS_INET) {
1164 int addrcount, addrtocopy;
1165 if (req->request_type != TYPE_AAAA) {
1166 j += datalength; continue;
1168 if ((datalength & 15) != 0) /* not an even number of AAAAs. */
1170 addrcount = datalength >> 4; /* each address is 16 bytes long */
1171 addrtocopy = MIN(MAX_V6_ADDRS - reply.data.aaaa.addrcount, (unsigned)addrcount);
1172 ttl_r = MIN(ttl_r, ttl);
1174 /* we only bother with the first four addresses. */
1175 if (j + 16*addrtocopy > length) goto err;
1176 memcpy(&reply.data.aaaa.addresses[reply.data.aaaa.addrcount],
1177 packet + j, 16*addrtocopy);
1178 reply.data.aaaa.addrcount += addrtocopy;
1180 reply.have_answer = 1;
1181 if (reply.data.aaaa.addrcount == MAX_V6_ADDRS) break;
1183 /* skip over any other type of resource */
1188 if (!reply.have_answer) {
1189 for (i = 0; i < authority; ++i) {
1196 if (type == TYPE_SOA && class == CLASS_INET) {
1197 u32 serial, refresh, retry, expire, minimum;
1209 ttl_r = MIN(ttl_r, ttl);
1210 ttl_r = MIN(ttl_r, minimum);
1212 /* skip over any other type of resource */
1218 if (ttl_r == 0xffffffff)
1221 reply_handle(req, flags, ttl_r, &reply);
1225 reply_handle(req, flags, 0, NULL);
1229 /* Parse a raw request (packet,length) sent to a nameserver port (port) from */
1230 /* a DNS client (addr,addrlen), and if it's well-formed, call the corresponding */
1233 request_parse(u8 *packet, int length, struct evdns_server_port *port, struct sockaddr *addr, ev_socklen_t addrlen)
1235 int j = 0; /* index into packet */
1236 u16 t_; /* used by the macros */
1237 char tmp_name[256]; /* used by the macros */
1240 u16 trans_id, flags, questions, answers, authority, additional;
1241 struct server_request *server_req = NULL;
1243 ASSERT_LOCKED(port);
1245 /* Get the header fields */
1256 if (flags & _QR_MASK) return -1; /* Must not be an answer. */
1257 flags &= (_RD_MASK|_CD_MASK); /* Only RD and CD get preserved. */
1259 server_req = mm_malloc(sizeof(struct server_request));
1260 if (server_req == NULL) return -1;
1261 memset(server_req, 0, sizeof(struct server_request));
1263 server_req->trans_id = trans_id;
1264 memcpy(&server_req->addr, addr, addrlen);
1265 server_req->addrlen = addrlen;
1267 server_req->base.flags = flags;
1268 server_req->base.nquestions = 0;
1269 server_req->base.questions = mm_calloc(sizeof(struct evdns_server_question *), questions);
1270 if (server_req->base.questions == NULL)
1273 for (i = 0; i < questions; ++i) {
1275 struct evdns_server_question *q;
1277 if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0)
1281 namelen = (int)strlen(tmp_name);
1282 q = mm_malloc(sizeof(struct evdns_server_question) + namelen);
1286 q->dns_question_class = class;
1287 memcpy(q->name, tmp_name, namelen+1);
1288 server_req->base.questions[server_req->base.nquestions++] = q;
1291 /* Ignore answers, authority, and additional. */
1293 server_req->port = port;
1296 /* Only standard queries are supported. */
1297 if (flags & _OP_MASK) {
1298 evdns_server_request_respond(&(server_req->base), DNS_ERR_NOTIMPL);
1302 port->user_callback(&(server_req->base), port->user_data);
1306 if (server_req->base.questions) {
1307 for (i = 0; i < server_req->base.nquestions; ++i)
1308 mm_free(server_req->base.questions[i]);
1309 mm_free(server_req->base.questions);
1311 mm_free(server_req);
1322 evdns_set_transaction_id_fn(ev_uint16_t (*fn)(void))
1327 evdns_set_random_bytes_fn(void (*fn)(char *, size_t))
1331 /* Try to choose a strong transaction id which isn't already in flight */
1333 transaction_id_pick(struct evdns_base *base) {
1334 ASSERT_LOCKED(base);
1337 evutil_secure_rng_get_bytes(&trans_id, sizeof(trans_id));
1339 if (trans_id == 0xffff) continue;
1340 /* now check to see if that id is already inflight */
1341 if (request_find_from_trans_id(base, trans_id) == NULL)
1346 /* choose a namesever to use. This function will try to ignore */
1347 /* nameservers which we think are down and load balance across the rest */
1348 /* by updating the server_head global each time. */
1349 static struct nameserver *
1350 nameserver_pick(struct evdns_base *base) {
1351 struct nameserver *started_at = base->server_head, *picked;
1352 ASSERT_LOCKED(base);
1353 if (!base->server_head) return NULL;
1355 /* if we don't have any good nameservers then there's no */
1356 /* point in trying to find one. */
1357 if (!base->global_good_nameservers) {
1358 base->server_head = base->server_head->next;
1359 return base->server_head;
1362 /* remember that nameservers are in a circular list */
1364 if (base->server_head->state) {
1365 /* we think this server is currently good */
1366 picked = base->server_head;
1367 base->server_head = base->server_head->next;
1371 base->server_head = base->server_head->next;
1372 if (base->server_head == started_at) {
1373 /* all the nameservers seem to be down */
1374 /* so we just return this one and hope for the */
1376 EVUTIL_ASSERT(base->global_good_nameservers == 0);
1377 picked = base->server_head;
1378 base->server_head = base->server_head->next;
1384 /* this is called when a namesever socket is ready for reading */
1386 nameserver_read(struct nameserver *ns) {
1387 struct sockaddr_storage ss;
1388 ev_socklen_t addrlen = sizeof(ss);
1391 ASSERT_LOCKED(ns->base);
1394 const int r = recvfrom(ns->socket, (void*)packet,
1396 (struct sockaddr*)&ss, &addrlen);
1398 int err = evutil_socket_geterror(ns->socket);
1399 if (EVUTIL_ERR_RW_RETRIABLE(err))
1401 nameserver_failed(ns,
1402 evutil_socket_error_to_string(err));
1405 if (evutil_sockaddr_cmp((struct sockaddr*)&ss,
1406 (struct sockaddr*)&ns->address, 0)) {
1407 log(EVDNS_LOG_WARN, "Address mismatch on received "
1408 "DNS packet. Apparent source was %s",
1409 evutil_format_sockaddr_port_(
1410 (struct sockaddr *)&ss,
1411 addrbuf, sizeof(addrbuf)));
1416 reply_parse(ns->base, packet, r);
1420 /* Read a packet from a DNS client on a server port s, parse it, and */
1421 /* act accordingly. */
1423 server_port_read(struct evdns_server_port *s) {
1425 struct sockaddr_storage addr;
1426 ev_socklen_t addrlen;
1431 addrlen = sizeof(struct sockaddr_storage);
1432 r = recvfrom(s->socket, (void*)packet, sizeof(packet), 0,
1433 (struct sockaddr*) &addr, &addrlen);
1435 int err = evutil_socket_geterror(s->socket);
1436 if (EVUTIL_ERR_RW_RETRIABLE(err))
1439 "Error %s (%d) while reading request.",
1440 evutil_socket_error_to_string(err), err);
1443 request_parse(packet, r, s, (struct sockaddr*) &addr, addrlen);
1447 /* Try to write all pending replies on a given DNS server port. */
1449 server_port_flush(struct evdns_server_port *port)
1451 struct server_request *req = port->pending_replies;
1452 ASSERT_LOCKED(port);
1454 int r = sendto(port->socket, req->response, (int)req->response_len, 0,
1455 (struct sockaddr*) &req->addr, (ev_socklen_t)req->addrlen);
1457 int err = evutil_socket_geterror(port->socket);
1458 if (EVUTIL_ERR_RW_RETRIABLE(err))
1460 log(EVDNS_LOG_WARN, "Error %s (%d) while writing response to port; dropping", evutil_socket_error_to_string(err), err);
1462 if (server_request_free(req)) {
1463 /* we released the last reference to req->port. */
1466 EVUTIL_ASSERT(req != port->pending_replies);
1467 req = port->pending_replies;
1471 /* We have no more pending requests; stop listening for 'writeable' events. */
1472 (void) event_del(&port->event);
1473 event_assign(&port->event, port->event_base,
1474 port->socket, EV_READ | EV_PERSIST,
1475 server_port_ready_callback, port);
1477 if (event_add(&port->event, NULL) < 0) {
1478 log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server.");
1483 /* set if we are waiting for the ability to write to this server. */
1484 /* if waiting is true then we ask libevent for EV_WRITE events, otherwise */
1485 /* we stop these events. */
1487 nameserver_write_waiting(struct nameserver *ns, char waiting) {
1488 ASSERT_LOCKED(ns->base);
1489 if (ns->write_waiting == waiting) return;
1491 ns->write_waiting = waiting;
1492 (void) event_del(&ns->event);
1493 event_assign(&ns->event, ns->base->event_base,
1494 ns->socket, EV_READ | (waiting ? EV_WRITE : 0) | EV_PERSIST,
1495 nameserver_ready_callback, ns);
1496 if (event_add(&ns->event, NULL) < 0) {
1498 log(EVDNS_LOG_WARN, "Error from libevent when adding event for %s",
1499 evutil_format_sockaddr_port_(
1500 (struct sockaddr *)&ns->address,
1501 addrbuf, sizeof(addrbuf)));
1506 /* a callback function. Called by libevent when the kernel says that */
1507 /* a nameserver socket is ready for writing or reading */
1509 nameserver_ready_callback(evutil_socket_t fd, short events, void *arg) {
1510 struct nameserver *ns = (struct nameserver *) arg;
1513 EVDNS_LOCK(ns->base);
1514 if (events & EV_WRITE) {
1516 if (!evdns_transmit(ns->base)) {
1517 nameserver_write_waiting(ns, 0);
1520 if (events & EV_READ) {
1521 nameserver_read(ns);
1523 EVDNS_UNLOCK(ns->base);
1526 /* a callback function. Called by libevent when the kernel says that */
1527 /* a server socket is ready for writing or reading. */
1529 server_port_ready_callback(evutil_socket_t fd, short events, void *arg) {
1530 struct evdns_server_port *port = (struct evdns_server_port *) arg;
1534 if (events & EV_WRITE) {
1536 server_port_flush(port);
1538 if (events & EV_READ) {
1539 server_port_read(port);
1544 /* This is an inefficient representation; only use it via the dnslabel_table_*
1545 * functions, so that is can be safely replaced with something smarter later. */
1546 #define MAX_LABELS 128
1547 /* Structures used to implement name compression */
1548 struct dnslabel_entry { char *v; off_t pos; };
1549 struct dnslabel_table {
1550 int n_labels; /* number of current entries */
1551 /* map from name to position in message */
1552 struct dnslabel_entry labels[MAX_LABELS];
1555 /* Initialize dnslabel_table. */
1557 dnslabel_table_init(struct dnslabel_table *table)
1559 table->n_labels = 0;
1562 /* Free all storage held by table, but not the table itself. */
1564 dnslabel_clear(struct dnslabel_table *table)
1567 for (i = 0; i < table->n_labels; ++i)
1568 mm_free(table->labels[i].v);
1569 table->n_labels = 0;
1572 /* return the position of the label in the current message, or -1 if the label */
1573 /* hasn't been used yet. */
1575 dnslabel_table_get_pos(const struct dnslabel_table *table, const char *label)
1578 for (i = 0; i < table->n_labels; ++i) {
1579 if (!strcmp(label, table->labels[i].v))
1580 return table->labels[i].pos;
1585 /* remember that we've used the label at position pos */
1587 dnslabel_table_add(struct dnslabel_table *table, const char *label, off_t pos)
1591 if (table->n_labels == MAX_LABELS)
1593 v = mm_strdup(label);
1596 p = table->n_labels++;
1597 table->labels[p].v = v;
1598 table->labels[p].pos = pos;
1603 /* Converts a string to a length-prefixed set of DNS labels, starting */
1604 /* at buf[j]. name and buf must not overlap. name_len should be the length */
1605 /* of name. table is optional, and is used for compression. */
1607 /* Input: abc.def */
1608 /* Output: <3>abc<3>def<0> */
1610 /* Returns the first index after the encoded name, or negative on error. */
1611 /* -1 label was > 63 bytes */
1612 /* -2 name too long to fit in buffer. */
1615 dnsname_to_labels(u8 *const buf, size_t buf_len, off_t j,
1616 const char *name, const size_t name_len,
1617 struct dnslabel_table *table) {
1618 const char *end = name + name_len;
1622 #define APPEND16(x) do { \
1623 if (j + 2 > (off_t)buf_len) \
1626 memcpy(buf + j, &t_, 2); \
1629 #define APPEND32(x) do { \
1630 if (j + 4 > (off_t)buf_len) \
1633 memcpy(buf + j, &t32_, 4); \
1637 if (name_len > 255) return -2;
1640 const char *const start = name;
1641 if (table && (ref = dnslabel_table_get_pos(table, name)) >= 0) {
1642 APPEND16(ref | 0xc000);
1645 name = strchr(name, '.');
1647 const size_t label_len = end - start;
1648 if (label_len > 63) return -1;
1649 if ((size_t)(j+label_len+1) > buf_len) return -2;
1650 if (table) dnslabel_table_add(table, start, j);
1651 buf[j++] = (ev_uint8_t)label_len;
1653 memcpy(buf + j, start, label_len);
1654 j += (int) label_len;
1657 /* append length of the label. */
1658 const size_t label_len = name - start;
1659 if (label_len > 63) return -1;
1660 if ((size_t)(j+label_len+1) > buf_len) return -2;
1661 if (table) dnslabel_table_add(table, start, j);
1662 buf[j++] = (ev_uint8_t)label_len;
1664 memcpy(buf + j, start, label_len);
1665 j += (int) label_len;
1666 /* hop over the '.' */
1671 /* the labels must be terminated by a 0. */
1672 /* It's possible that the name ended in a . */
1673 /* in which case the zero is already there */
1674 if (!j || buf[j-1]) buf[j++] = 0;
1680 /* Finds the length of a dns request for a DNS name of the given */
1681 /* length. The actual request may be smaller than the value returned */
1684 evdns_request_len(const size_t name_len) {
1685 return 96 + /* length of the DNS standard header */
1687 4; /* space for the resource type */
1690 /* build a dns request packet into buf. buf should be at least as long */
1691 /* as evdns_request_len told you it should be. */
1693 /* Returns the amount of space used. Negative on error. */
1695 evdns_request_data_build(const char *const name, const size_t name_len,
1696 const u16 trans_id, const u16 type, const u16 class,
1697 u8 *const buf, size_t buf_len) {
1698 off_t j = 0; /* current offset into buf */
1699 u16 t_; /* used by the macros */
1702 APPEND16(0x0100); /* standard query, recusion needed */
1703 APPEND16(1); /* one question */
1704 APPEND16(0); /* no answers */
1705 APPEND16(0); /* no authority */
1706 APPEND16(0); /* no additional */
1708 j = dnsname_to_labels(buf, buf_len, j, name, name_len, NULL);
1721 /* exported function */
1722 struct evdns_server_port *
1723 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)
1725 struct evdns_server_port *port;
1727 return NULL; /* flags not yet implemented */
1728 if (!(port = mm_malloc(sizeof(struct evdns_server_port))))
1730 memset(port, 0, sizeof(struct evdns_server_port));
1733 port->socket = socket;
1737 port->user_callback = cb;
1738 port->user_data = user_data;
1739 port->pending_replies = NULL;
1740 port->event_base = base;
1742 event_assign(&port->event, port->event_base,
1743 port->socket, EV_READ | EV_PERSIST,
1744 server_port_ready_callback, port);
1745 if (event_add(&port->event, NULL) < 0) {
1749 EVTHREAD_ALLOC_LOCK(port->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
1753 struct evdns_server_port *
1754 evdns_add_server_port(evutil_socket_t socket, int flags, evdns_request_callback_fn_type cb, void *user_data)
1756 return evdns_add_server_port_with_base(NULL, socket, flags, cb, user_data);
1759 /* exported function */
1761 evdns_close_server_port(struct evdns_server_port *port)
1764 if (--port->refcnt == 0) {
1766 server_port_free(port);
1773 /* exported function */
1775 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)
1777 struct server_request *req = TO_SERVER_REQUEST(req_);
1778 struct server_reply_item **itemp, *item;
1782 EVDNS_LOCK(req->port);
1783 if (req->response) /* have we already answered? */
1787 case EVDNS_ANSWER_SECTION:
1788 itemp = &req->answer;
1789 countp = &req->n_answer;
1791 case EVDNS_AUTHORITY_SECTION:
1792 itemp = &req->authority;
1793 countp = &req->n_authority;
1795 case EVDNS_ADDITIONAL_SECTION:
1796 itemp = &req->additional;
1797 countp = &req->n_additional;
1803 itemp = &((*itemp)->next);
1805 item = mm_malloc(sizeof(struct server_reply_item));
1809 if (!(item->name = mm_strdup(name))) {
1814 item->dns_question_class = class;
1816 item->is_name = is_name != 0;
1820 if (item->is_name) {
1821 if (!(item->data = mm_strdup(data))) {
1822 mm_free(item->name);
1826 item->datalen = (u16)-1;
1828 if (!(item->data = mm_malloc(datalen))) {
1829 mm_free(item->name);
1833 item->datalen = datalen;
1834 memcpy(item->data, data, datalen);
1842 EVDNS_UNLOCK(req->port);
1846 /* exported function */
1848 evdns_server_request_add_a_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl)
1850 return evdns_server_request_add_reply(
1851 req, EVDNS_ANSWER_SECTION, name, TYPE_A, CLASS_INET,
1852 ttl, n*4, 0, addrs);
1855 /* exported function */
1857 evdns_server_request_add_aaaa_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl)
1859 return evdns_server_request_add_reply(
1860 req, EVDNS_ANSWER_SECTION, name, TYPE_AAAA, CLASS_INET,
1861 ttl, n*16, 0, addrs);
1864 /* exported function */
1866 evdns_server_request_add_ptr_reply(struct evdns_server_request *req, struct in_addr *in, const char *inaddr_name, const char *hostname, int ttl)
1870 if (in && inaddr_name)
1872 else if (!in && !inaddr_name)
1875 a = ntohl(in->s_addr);
1876 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa",
1877 (int)(u8)((a )&0xff),
1878 (int)(u8)((a>>8 )&0xff),
1879 (int)(u8)((a>>16)&0xff),
1880 (int)(u8)((a>>24)&0xff));
1883 return evdns_server_request_add_reply(
1884 req, EVDNS_ANSWER_SECTION, inaddr_name, TYPE_PTR, CLASS_INET,
1885 ttl, -1, 1, hostname);
1888 /* exported function */
1890 evdns_server_request_add_cname_reply(struct evdns_server_request *req, const char *name, const char *cname, int ttl)
1892 return evdns_server_request_add_reply(
1893 req, EVDNS_ANSWER_SECTION, name, TYPE_CNAME, CLASS_INET,
1897 /* exported function */
1899 evdns_server_request_set_flags(struct evdns_server_request *exreq, int flags)
1901 struct server_request *req = TO_SERVER_REQUEST(exreq);
1902 req->base.flags &= ~(EVDNS_FLAGS_AA|EVDNS_FLAGS_RD);
1903 req->base.flags |= flags;
1907 evdns_server_request_format_response(struct server_request *req, int err)
1909 unsigned char buf[1500];
1910 size_t buf_len = sizeof(buf);
1916 struct dnslabel_table table;
1918 if (err < 0 || err > 15) return -1;
1920 /* Set response bit and error code; copy OPCODE and RD fields from
1921 * question; copy RA and AA if set by caller. */
1922 flags = req->base.flags;
1923 flags |= (_QR_MASK | err);
1925 dnslabel_table_init(&table);
1926 APPEND16(req->trans_id);
1928 APPEND16(req->base.nquestions);
1929 APPEND16(req->n_answer);
1930 APPEND16(req->n_authority);
1931 APPEND16(req->n_additional);
1933 /* Add questions. */
1934 for (i=0; i < req->base.nquestions; ++i) {
1935 const char *s = req->base.questions[i]->name;
1936 j = dnsname_to_labels(buf, buf_len, j, s, strlen(s), &table);
1938 dnslabel_clear(&table);
1941 APPEND16(req->base.questions[i]->type);
1942 APPEND16(req->base.questions[i]->dns_question_class);
1945 /* Add answer, authority, and additional sections. */
1946 for (i=0; i<3; ++i) {
1947 struct server_reply_item *item;
1951 item = req->authority;
1953 item = req->additional;
1955 r = dnsname_to_labels(buf, buf_len, j, item->name, strlen(item->name), &table);
1960 APPEND16(item->type);
1961 APPEND16(item->dns_question_class);
1962 APPEND32(item->ttl);
1963 if (item->is_name) {
1964 off_t len_idx = j, name_start;
1967 r = dnsname_to_labels(buf, buf_len, j, item->data, strlen(item->data), &table);
1971 t_ = htons( (short) (j-name_start) );
1972 memcpy(buf+len_idx, &t_, 2);
1974 APPEND16(item->datalen);
1975 if (j+item->datalen > (off_t)buf_len)
1977 memcpy(buf+j, item->data, item->datalen);
1987 buf[2] |= 0x02; /* set the truncated bit. */
1990 req->response_len = j;
1992 if (!(req->response = mm_malloc(req->response_len))) {
1993 server_request_free_answers(req);
1994 dnslabel_clear(&table);
1997 memcpy(req->response, buf, req->response_len);
1998 server_request_free_answers(req);
1999 dnslabel_clear(&table);
2003 /* exported function */
2005 evdns_server_request_respond(struct evdns_server_request *req_, int err)
2007 struct server_request *req = TO_SERVER_REQUEST(req_);
2008 struct evdns_server_port *port = req->port;
2012 if (!req->response) {
2013 if ((r = evdns_server_request_format_response(req, err))<0)
2017 r = sendto(port->socket, req->response, (int)req->response_len, 0,
2018 (struct sockaddr*) &req->addr, (ev_socklen_t)req->addrlen);
2020 int sock_err = evutil_socket_geterror(port->socket);
2021 if (EVUTIL_ERR_RW_RETRIABLE(sock_err))
2024 if (port->pending_replies) {
2025 req->prev_pending = port->pending_replies->prev_pending;
2026 req->next_pending = port->pending_replies;
2027 req->prev_pending->next_pending =
2028 req->next_pending->prev_pending = req;
2030 req->prev_pending = req->next_pending = req;
2031 port->pending_replies = req;
2034 (void) event_del(&port->event);
2035 event_assign(&port->event, port->event_base, port->socket, (port->closing?0:EV_READ) | EV_WRITE | EV_PERSIST, server_port_ready_callback, port);
2037 if (event_add(&port->event, NULL) < 0) {
2038 log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server");
2046 if (server_request_free(req)) {
2051 if (port->pending_replies)
2052 server_port_flush(port);
2060 /* Free all storage held by RRs in req. */
2062 server_request_free_answers(struct server_request *req)
2064 struct server_reply_item *victim, *next, **list;
2066 for (i = 0; i < 3; ++i) {
2068 list = &req->answer;
2070 list = &req->authority;
2072 list = &req->additional;
2076 next = victim->next;
2077 mm_free(victim->name);
2079 mm_free(victim->data);
2087 /* Free all storage held by req, and remove links to it. */
2088 /* return true iff we just wound up freeing the server_port. */
2090 server_request_free(struct server_request *req)
2092 int i, rc=1, lock=0;
2093 if (req->base.questions) {
2094 for (i = 0; i < req->base.nquestions; ++i)
2095 mm_free(req->base.questions[i]);
2096 mm_free(req->base.questions);
2100 EVDNS_LOCK(req->port);
2102 if (req->port->pending_replies == req) {
2103 if (req->next_pending && req->next_pending != req)
2104 req->port->pending_replies = req->next_pending;
2106 req->port->pending_replies = NULL;
2108 rc = --req->port->refcnt;
2111 if (req->response) {
2112 mm_free(req->response);
2115 server_request_free_answers(req);
2117 if (req->next_pending && req->next_pending != req) {
2118 req->next_pending->prev_pending = req->prev_pending;
2119 req->prev_pending->next_pending = req->next_pending;
2123 EVDNS_UNLOCK(req->port); /* ????? nickm */
2124 server_port_free(req->port);
2129 EVDNS_UNLOCK(req->port);
2134 /* Free all storage held by an evdns_server_port. Only called when */
2136 server_port_free(struct evdns_server_port *port)
2138 EVUTIL_ASSERT(port);
2139 EVUTIL_ASSERT(!port->refcnt);
2140 EVUTIL_ASSERT(!port->pending_replies);
2141 if (port->socket > 0) {
2142 evutil_closesocket(port->socket);
2145 (void) event_del(&port->event);
2146 event_debug_unassign(&port->event);
2147 EVTHREAD_FREE_LOCK(port->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
2151 /* exported function */
2153 evdns_server_request_drop(struct evdns_server_request *req_)
2155 struct server_request *req = TO_SERVER_REQUEST(req_);
2156 server_request_free(req);
2160 /* exported function */
2162 evdns_server_request_get_requesting_addr(struct evdns_server_request *req_, struct sockaddr *sa, int addr_len)
2164 struct server_request *req = TO_SERVER_REQUEST(req_);
2165 if (addr_len < (int)req->addrlen)
2167 memcpy(sa, &(req->addr), req->addrlen);
2168 return req->addrlen;
2174 /* this is a libevent callback function which is called when a request */
2175 /* has timed out. */
2177 evdns_request_timeout_callback(evutil_socket_t fd, short events, void *arg) {
2178 struct request *const req = (struct request *) arg;
2179 struct evdns_base *base = req->base;
2184 log(EVDNS_LOG_DEBUG, "Request %p timed out", arg);
2187 if (req->tx_count >= req->base->global_max_retransmits) {
2188 struct nameserver *ns = req->ns;
2189 /* this request has failed */
2190 log(EVDNS_LOG_DEBUG, "Giving up on request %p; tx_count==%d",
2191 arg, req->tx_count);
2192 reply_schedule_callback(req, 0, DNS_ERR_TIMEOUT, NULL);
2194 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1);
2195 nameserver_failed(ns, "request timed out.");
2198 log(EVDNS_LOG_DEBUG, "Retransmitting request %p; tx_count==%d",
2199 arg, req->tx_count);
2200 (void) evtimer_del(&req->timeout_event);
2201 request_swap_ns(req, nameserver_pick(base));
2202 evdns_request_transmit(req);
2204 req->ns->timedout++;
2205 if (req->ns->timedout > req->base->global_max_nameserver_timeout) {
2206 req->ns->timedout = 0;
2207 nameserver_failed(req->ns, "request timed out.");
2214 /* try to send a request to a given server. */
2218 /* 1 temporary failure */
2219 /* 2 other failure */
2221 evdns_request_transmit_to(struct request *req, struct nameserver *server) {
2223 ASSERT_LOCKED(req->base);
2224 ASSERT_VALID_REQUEST(req);
2226 if (server->requests_inflight == 1 &&
2227 req->base->disable_when_inactive &&
2228 event_add(&server->event, NULL) < 0) {
2232 r = sendto(server->socket, (void*)req->request, req->request_len, 0,
2233 (struct sockaddr *)&server->address, server->addrlen);
2235 int err = evutil_socket_geterror(server->socket);
2236 if (EVUTIL_ERR_RW_RETRIABLE(err))
2238 nameserver_failed(req->ns, evutil_socket_error_to_string(err));
2240 } else if (r != (int)req->request_len) {
2241 return 1; /* short write */
2247 /* try to send a request, updating the fields of the request */
2254 evdns_request_transmit(struct request *req) {
2257 ASSERT_LOCKED(req->base);
2258 ASSERT_VALID_REQUEST(req);
2259 /* if we fail to send this packet then this flag marks it */
2260 /* for evdns_transmit */
2261 req->transmit_me = 1;
2262 EVUTIL_ASSERT(req->trans_id != 0xffff);
2266 /* unable to transmit request if no nameservers */
2270 if (req->ns->choked) {
2271 /* don't bother trying to write to a socket */
2272 /* which we have had EAGAIN from */
2276 r = evdns_request_transmit_to(req, req->ns);
2280 req->ns->choked = 1;
2281 nameserver_write_waiting(req->ns, 1);
2284 /* failed to transmit the request entirely. we can fallthrough since
2285 * we'll set a timeout, which will time out, and make us retransmit the
2286 * request anyway. */
2291 log(EVDNS_LOG_DEBUG,
2292 "Setting timeout for request %p, sent to nameserver %p", req, req->ns);
2293 if (evtimer_add(&req->timeout_event, &req->base->global_timeout) < 0) {
2295 "Error from libevent when adding timer for request %p",
2300 req->transmit_me = 0;
2306 nameserver_probe_callback(int result, char type, int count, int ttl, void *addresses, void *arg) {
2307 struct nameserver *const ns = (struct nameserver *) arg;
2313 if (result == DNS_ERR_CANCEL) {
2314 /* We canceled this request because the nameserver came up
2315 * for some other reason. Do not change our opinion about
2316 * the nameserver. */
2320 EVDNS_LOCK(ns->base);
2321 ns->probe_request = NULL;
2322 if (result == DNS_ERR_NONE || result == DNS_ERR_NOTEXIST) {
2323 /* this is a good reply */
2326 nameserver_probe_failed(ns);
2328 EVDNS_UNLOCK(ns->base);
2332 nameserver_send_probe(struct nameserver *const ns) {
2333 struct evdns_request *handle;
2334 struct request *req;
2336 /* here we need to send a probe to a given nameserver */
2337 /* in the hope that it is up now. */
2339 ASSERT_LOCKED(ns->base);
2340 log(EVDNS_LOG_DEBUG, "Sending probe to %s",
2341 evutil_format_sockaddr_port_(
2342 (struct sockaddr *)&ns->address,
2343 addrbuf, sizeof(addrbuf)));
2344 handle = mm_calloc(1, sizeof(*handle));
2345 if (!handle) return;
2346 req = request_new(ns->base, handle, TYPE_A, "google.com", DNS_QUERY_NO_SEARCH, nameserver_probe_callback, ns);
2351 ns->probe_request = handle;
2352 /* we force this into the inflight queue no matter what */
2353 request_trans_id_set(req, transaction_id_pick(ns->base));
2355 request_submit(req);
2359 /* 0 didn't try to transmit anything */
2360 /* 1 tried to transmit something */
2362 evdns_transmit(struct evdns_base *base) {
2363 char did_try_to_transmit = 0;
2366 ASSERT_LOCKED(base);
2367 for (i = 0; i < base->n_req_heads; ++i) {
2368 if (base->req_heads[i]) {
2369 struct request *const started_at = base->req_heads[i], *req = started_at;
2370 /* first transmit all the requests which are currently waiting */
2372 if (req->transmit_me) {
2373 did_try_to_transmit = 1;
2374 evdns_request_transmit(req);
2378 } while (req != started_at);
2382 return did_try_to_transmit;
2385 /* exported function */
2387 evdns_base_count_nameservers(struct evdns_base *base)
2389 const struct nameserver *server;
2393 server = base->server_head;
2398 server = server->next;
2399 } while (server != base->server_head);
2406 evdns_count_nameservers(void)
2408 return evdns_base_count_nameservers(current_base);
2411 /* exported function */
2413 evdns_base_clear_nameservers_and_suspend(struct evdns_base *base)
2415 struct nameserver *server, *started_at;
2419 server = base->server_head;
2420 started_at = base->server_head;
2426 struct nameserver *next = server->next;
2427 (void) event_del(&server->event);
2428 if (evtimer_initialized(&server->timeout_event))
2429 (void) evtimer_del(&server->timeout_event);
2430 if (server->probe_request) {
2431 evdns_cancel_request(server->base, server->probe_request);
2432 server->probe_request = NULL;
2434 if (server->socket >= 0)
2435 evutil_closesocket(server->socket);
2437 if (next == started_at)
2441 base->server_head = NULL;
2442 base->global_good_nameservers = 0;
2444 for (i = 0; i < base->n_req_heads; ++i) {
2445 struct request *req, *req_started_at;
2446 req = req_started_at = base->req_heads[i];
2448 struct request *next = req->next;
2449 req->tx_count = req->reissue_count = 0;
2451 /* ???? What to do about searches? */
2452 (void) evtimer_del(&req->timeout_event);
2454 req->transmit_me = 0;
2456 base->global_requests_waiting++;
2457 evdns_request_insert(req, &base->req_waiting_head);
2458 /* We want to insert these suspended elements at the front of
2459 * the waiting queue, since they were pending before any of
2460 * the waiting entries were added. This is a circular list,
2461 * so we can just shift the start back by one.*/
2462 base->req_waiting_head = base->req_waiting_head->prev;
2464 if (next == req_started_at)
2468 base->req_heads[i] = NULL;
2471 base->global_requests_inflight = 0;
2478 evdns_clear_nameservers_and_suspend(void)
2480 return evdns_base_clear_nameservers_and_suspend(current_base);
2484 /* exported function */
2486 evdns_base_resume(struct evdns_base *base)
2489 evdns_requests_pump_waiting_queue(base);
2498 return evdns_base_resume(current_base);
2502 evdns_nameserver_add_impl_(struct evdns_base *base, const struct sockaddr *address, int addrlen) {
2503 /* first check to see if we already have this nameserver */
2505 const struct nameserver *server = base->server_head, *const started_at = base->server_head;
2506 struct nameserver *ns;
2510 ASSERT_LOCKED(base);
2513 if (!evutil_sockaddr_cmp((struct sockaddr*)&server->address, address, 1)) return 3;
2514 server = server->next;
2515 } while (server != started_at);
2517 if (addrlen > (int)sizeof(ns->address)) {
2518 log(EVDNS_LOG_DEBUG, "Addrlen %d too long.", (int)addrlen);
2522 ns = (struct nameserver *) mm_malloc(sizeof(struct nameserver));
2525 memset(ns, 0, sizeof(struct nameserver));
2528 evtimer_assign(&ns->timeout_event, ns->base->event_base, nameserver_prod_callback, ns);
2530 ns->socket = evutil_socket_(address->sa_family,
2531 SOCK_DGRAM|EVUTIL_SOCK_NONBLOCK|EVUTIL_SOCK_CLOEXEC, 0);
2532 if (ns->socket < 0) { err = 1; goto out1; }
2534 if (base->global_outgoing_addrlen &&
2535 !evutil_sockaddr_is_loopback_(address)) {
2536 if (bind(ns->socket,
2537 (struct sockaddr*)&base->global_outgoing_address,
2538 base->global_outgoing_addrlen) < 0) {
2539 log(EVDNS_LOG_WARN,"Couldn't bind to outgoing address");
2545 if (base->so_rcvbuf) {
2546 if (setsockopt(ns->socket, SOL_SOCKET, SO_RCVBUF,
2547 (void *)&base->so_rcvbuf, sizeof(base->so_rcvbuf))) {
2548 log(EVDNS_LOG_WARN, "Couldn't set SO_RCVBUF to %i", base->so_rcvbuf);
2553 if (base->so_sndbuf) {
2554 if (setsockopt(ns->socket, SOL_SOCKET, SO_SNDBUF,
2555 (void *)&base->so_sndbuf, sizeof(base->so_sndbuf))) {
2556 log(EVDNS_LOG_WARN, "Couldn't set SO_SNDBUF to %i", base->so_sndbuf);
2562 memcpy(&ns->address, address, addrlen);
2563 ns->addrlen = addrlen;
2565 event_assign(&ns->event, ns->base->event_base, ns->socket,
2566 EV_READ | EV_PERSIST, nameserver_ready_callback, ns);
2567 if (!base->disable_when_inactive && event_add(&ns->event, NULL) < 0) {
2572 log(EVDNS_LOG_DEBUG, "Added nameserver %s as %p",
2573 evutil_format_sockaddr_port_(address, addrbuf, sizeof(addrbuf)), ns);
2575 /* insert this nameserver into the list of them */
2576 if (!base->server_head) {
2577 ns->next = ns->prev = ns;
2578 base->server_head = ns;
2580 ns->next = base->server_head->next;
2581 ns->prev = base->server_head;
2582 base->server_head->next = ns;
2583 ns->next->prev = ns;
2586 base->global_good_nameservers++;
2591 evutil_closesocket(ns->socket);
2593 event_debug_unassign(&ns->event);
2595 log(EVDNS_LOG_WARN, "Unable to add nameserver %s: error %d",
2596 evutil_format_sockaddr_port_(address, addrbuf, sizeof(addrbuf)), err);
2600 /* exported function */
2602 evdns_base_nameserver_add(struct evdns_base *base, unsigned long int address)
2604 struct sockaddr_in sin;
2606 memset(&sin, 0, sizeof(sin));
2607 sin.sin_addr.s_addr = address;
2608 sin.sin_port = htons(53);
2609 sin.sin_family = AF_INET;
2611 res = evdns_nameserver_add_impl_(base, (struct sockaddr*)&sin, sizeof(sin));
2617 evdns_nameserver_add(unsigned long int address) {
2619 current_base = evdns_base_new(NULL, 0);
2620 return evdns_base_nameserver_add(current_base, address);
2624 sockaddr_setport(struct sockaddr *sa, ev_uint16_t port)
2626 if (sa->sa_family == AF_INET) {
2627 ((struct sockaddr_in *)sa)->sin_port = htons(port);
2628 } else if (sa->sa_family == AF_INET6) {
2629 ((struct sockaddr_in6 *)sa)->sin6_port = htons(port);
2634 sockaddr_getport(struct sockaddr *sa)
2636 if (sa->sa_family == AF_INET) {
2637 return ntohs(((struct sockaddr_in *)sa)->sin_port);
2638 } else if (sa->sa_family == AF_INET6) {
2639 return ntohs(((struct sockaddr_in6 *)sa)->sin6_port);
2645 /* exported function */
2647 evdns_base_nameserver_ip_add(struct evdns_base *base, const char *ip_as_string) {
2648 struct sockaddr_storage ss;
2649 struct sockaddr *sa;
2650 int len = sizeof(ss);
2652 if (evutil_parse_sockaddr_port(ip_as_string, (struct sockaddr *)&ss,
2654 log(EVDNS_LOG_WARN, "Unable to parse nameserver address %s",
2658 sa = (struct sockaddr *) &ss;
2659 if (sockaddr_getport(sa) == 0)
2660 sockaddr_setport(sa, 53);
2663 res = evdns_nameserver_add_impl_(base, sa, len);
2669 evdns_nameserver_ip_add(const char *ip_as_string) {
2671 current_base = evdns_base_new(NULL, 0);
2672 return evdns_base_nameserver_ip_add(current_base, ip_as_string);
2676 evdns_base_nameserver_sockaddr_add(struct evdns_base *base,
2677 const struct sockaddr *sa, ev_socklen_t len, unsigned flags)
2680 EVUTIL_ASSERT(base);
2682 res = evdns_nameserver_add_impl_(base, sa, len);
2688 evdns_base_get_nameserver_addr(struct evdns_base *base, int idx,
2689 struct sockaddr *sa, ev_socklen_t len)
2693 struct nameserver *server;
2695 server = base->server_head;
2696 for (i = 0; i < idx && server; ++i, server = server->next) {
2697 if (server->next == base->server_head)
2703 if (server->addrlen > len) {
2704 result = (int) server->addrlen;
2708 memcpy(sa, &server->address, server->addrlen);
2709 result = (int) server->addrlen;
2715 /* remove from the queue */
2717 evdns_request_remove(struct request *req, struct request **head)
2719 ASSERT_LOCKED(req->base);
2720 ASSERT_VALID_REQUEST(req);
2724 struct request *ptr;
2726 EVUTIL_ASSERT(*head != NULL);
2735 } while (ptr != *head);
2736 EVUTIL_ASSERT(found);
2738 EVUTIL_ASSERT(req->next);
2742 if (req->next == req) {
2743 /* only item in the list */
2746 req->next->prev = req->prev;
2747 req->prev->next = req->next;
2748 if (*head == req) *head = req->next;
2750 req->next = req->prev = NULL;
2753 /* insert into the tail of the queue */
2755 evdns_request_insert(struct request *req, struct request **head) {
2756 ASSERT_LOCKED(req->base);
2757 ASSERT_VALID_REQUEST(req);
2760 req->next = req->prev = req;
2764 req->prev = (*head)->prev;
2765 req->prev->next = req;
2767 (*head)->prev = req;
2771 string_num_dots(const char *s) {
2773 while ((s = strchr(s, '.'))) {
2780 static struct request *
2781 request_new(struct evdns_base *base, struct evdns_request *handle, int type,
2782 const char *name, int flags, evdns_callback_type callback,
2785 const char issuing_now =
2786 (base->global_requests_inflight < base->global_max_requests_inflight) ? 1 : 0;
2788 const size_t name_len = strlen(name);
2789 const size_t request_max_len = evdns_request_len(name_len);
2790 const u16 trans_id = issuing_now ? transaction_id_pick(base) : 0xffff;
2791 /* the request data is alloced in a single block with the header */
2792 struct request *const req =
2793 mm_malloc(sizeof(struct request) + request_max_len);
2798 ASSERT_LOCKED(base);
2800 if (!req) return NULL;
2802 if (name_len >= sizeof(namebuf)) {
2807 memset(req, 0, sizeof(struct request));
2810 evtimer_assign(&req->timeout_event, req->base->event_base, evdns_request_timeout_callback, req);
2812 if (base->global_randomize_case) {
2814 char randbits[(sizeof(namebuf)+7)/8];
2815 strlcpy(namebuf, name, sizeof(namebuf));
2816 evutil_secure_rng_get_bytes(randbits, (name_len+7)/8);
2817 for (i = 0; i < name_len; ++i) {
2818 if (EVUTIL_ISALPHA_(namebuf[i])) {
2819 if ((randbits[i >> 3] & (1<<(i & 7))))
2822 namebuf[i] &= ~0x20;
2828 /* request data lives just after the header */
2829 req->request = ((u8 *) req) + sizeof(struct request);
2830 /* denotes that the request data shouldn't be free()ed */
2831 req->request_appended = 1;
2832 rlen = evdns_request_data_build(name, name_len, trans_id,
2833 type, CLASS_INET, req->request, request_max_len);
2837 req->request_len = rlen;
2838 req->trans_id = trans_id;
2840 req->request_type = type;
2841 req->user_pointer = user_ptr;
2842 req->user_callback = callback;
2843 req->ns = issuing_now ? nameserver_pick(base) : NULL;
2844 req->next = req->prev = NULL;
2845 req->handle = handle;
2847 handle->current_req = req;
2848 handle->base = base;
2858 request_submit(struct request *const req) {
2859 struct evdns_base *base = req->base;
2860 ASSERT_LOCKED(base);
2861 ASSERT_VALID_REQUEST(req);
2863 /* if it has a nameserver assigned then this is going */
2864 /* straight into the inflight queue */
2865 evdns_request_insert(req, &REQ_HEAD(base, req->trans_id));
2867 base->global_requests_inflight++;
2868 req->ns->requests_inflight++;
2870 evdns_request_transmit(req);
2872 evdns_request_insert(req, &base->req_waiting_head);
2873 base->global_requests_waiting++;
2877 /* exported function */
2879 evdns_cancel_request(struct evdns_base *base, struct evdns_request *handle)
2881 struct request *req;
2883 if (!handle->current_req)
2887 /* This redundancy is silly; can we fix it? (Not for 2.0) XXXX */
2888 base = handle->base;
2890 base = handle->current_req->base;
2894 if (handle->pending_cb) {
2899 req = handle->current_req;
2900 ASSERT_VALID_REQUEST(req);
2902 reply_schedule_callback(req, 0, DNS_ERR_CANCEL, NULL);
2904 /* remove from inflight queue */
2905 request_finished(req, &REQ_HEAD(base, req->trans_id), 1);
2907 /* remove from global_waiting head */
2908 request_finished(req, &base->req_waiting_head, 1);
2913 /* exported function */
2914 struct evdns_request *
2915 evdns_base_resolve_ipv4(struct evdns_base *base, const char *name, int flags,
2916 evdns_callback_type callback, void *ptr) {
2917 struct evdns_request *handle;
2918 struct request *req;
2919 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name);
2920 handle = mm_calloc(1, sizeof(*handle));
2924 if (flags & DNS_QUERY_NO_SEARCH) {
2926 request_new(base, handle, TYPE_A, name, flags,
2929 request_submit(req);
2931 search_request_new(base, handle, TYPE_A, name, flags,
2934 if (handle->current_req == NULL) {
2942 int evdns_resolve_ipv4(const char *name, int flags,
2943 evdns_callback_type callback, void *ptr)
2945 return evdns_base_resolve_ipv4(current_base, name, flags, callback, ptr)
2950 /* exported function */
2951 struct evdns_request *
2952 evdns_base_resolve_ipv6(struct evdns_base *base,
2953 const char *name, int flags,
2954 evdns_callback_type callback, void *ptr)
2956 struct evdns_request *handle;
2957 struct request *req;
2958 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name);
2959 handle = mm_calloc(1, sizeof(*handle));
2963 if (flags & DNS_QUERY_NO_SEARCH) {
2964 req = request_new(base, handle, TYPE_AAAA, name, flags,
2967 request_submit(req);
2969 search_request_new(base, handle, TYPE_AAAA, name, flags,
2972 if (handle->current_req == NULL) {
2980 int evdns_resolve_ipv6(const char *name, int flags,
2981 evdns_callback_type callback, void *ptr) {
2982 return evdns_base_resolve_ipv6(current_base, name, flags, callback, ptr)
2986 struct evdns_request *
2987 evdns_base_resolve_reverse(struct evdns_base *base, const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) {
2989 struct evdns_request *handle;
2990 struct request *req;
2993 a = ntohl(in->s_addr);
2994 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa",
2995 (int)(u8)((a )&0xff),
2996 (int)(u8)((a>>8 )&0xff),
2997 (int)(u8)((a>>16)&0xff),
2998 (int)(u8)((a>>24)&0xff));
2999 handle = mm_calloc(1, sizeof(*handle));
3002 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf);
3004 req = request_new(base, handle, TYPE_PTR, buf, flags, callback, ptr);
3006 request_submit(req);
3007 if (handle->current_req == NULL) {
3015 int evdns_resolve_reverse(const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) {
3016 return evdns_base_resolve_reverse(current_base, in, flags, callback, ptr)
3020 struct evdns_request *
3021 evdns_base_resolve_reverse_ipv6(struct evdns_base *base, const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) {
3022 /* 32 nybbles, 32 periods, "ip6.arpa", NUL. */
3025 struct evdns_request *handle;
3026 struct request *req;
3030 for (i=15; i >= 0; --i) {
3031 u8 byte = in->s6_addr[i];
3032 *cp++ = "0123456789abcdef"[byte & 0x0f];
3034 *cp++ = "0123456789abcdef"[byte >> 4];
3037 EVUTIL_ASSERT(cp + strlen("ip6.arpa") < buf+sizeof(buf));
3038 memcpy(cp, "ip6.arpa", strlen("ip6.arpa")+1);
3039 handle = mm_calloc(1, sizeof(*handle));
3042 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf);
3044 req = request_new(base, handle, TYPE_PTR, buf, flags, callback, ptr);
3046 request_submit(req);
3047 if (handle->current_req == NULL) {
3055 int evdns_resolve_reverse_ipv6(const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) {
3056 return evdns_base_resolve_reverse_ipv6(current_base, in, flags, callback, ptr)
3060 /* ================================================================= */
3061 /* Search support */
3063 /* the libc resolver has support for searching a number of domains */
3064 /* to find a name. If nothing else then it takes the single domain */
3065 /* from the gethostname() call. */
3067 /* It can also be configured via the domain and search options in a */
3070 /* The ndots option controls how many dots it takes for the resolver */
3071 /* to decide that a name is non-local and so try a raw lookup first. */
3073 struct search_domain {
3075 struct search_domain *next;
3076 /* the text string is appended to this structure */
3079 struct search_state {
3083 struct search_domain *head;
3087 search_state_decref(struct search_state *const state) {
3090 if (!state->refcount) {
3091 struct search_domain *next, *dom;
3092 for (dom = state->head; dom; dom = next) {
3100 static struct search_state *
3101 search_state_new(void) {
3102 struct search_state *state = (struct search_state *) mm_malloc(sizeof(struct search_state));
3103 if (!state) return NULL;
3104 memset(state, 0, sizeof(struct search_state));
3105 state->refcount = 1;
3112 search_postfix_clear(struct evdns_base *base) {
3113 search_state_decref(base->global_search_state);
3115 base->global_search_state = search_state_new();
3118 /* exported function */
3120 evdns_base_search_clear(struct evdns_base *base)
3123 search_postfix_clear(base);
3128 evdns_search_clear(void) {
3129 evdns_base_search_clear(current_base);
3133 search_postfix_add(struct evdns_base *base, const char *domain) {
3135 struct search_domain *sdomain;
3136 while (domain[0] == '.') domain++;
3137 domain_len = strlen(domain);
3139 ASSERT_LOCKED(base);
3140 if (!base->global_search_state) base->global_search_state = search_state_new();
3141 if (!base->global_search_state) return;
3142 base->global_search_state->num_domains++;
3144 sdomain = (struct search_domain *) mm_malloc(sizeof(struct search_domain) + domain_len);
3145 if (!sdomain) return;
3146 memcpy( ((u8 *) sdomain) + sizeof(struct search_domain), domain, domain_len);
3147 sdomain->next = base->global_search_state->head;
3148 sdomain->len = (int) domain_len;
3150 base->global_search_state->head = sdomain;
3153 /* reverse the order of members in the postfix list. This is needed because, */
3154 /* when parsing resolv.conf we push elements in the wrong order */
3156 search_reverse(struct evdns_base *base) {
3157 struct search_domain *cur, *prev = NULL, *next;
3158 ASSERT_LOCKED(base);
3159 cur = base->global_search_state->head;
3167 base->global_search_state->head = prev;
3170 /* exported function */
3172 evdns_base_search_add(struct evdns_base *base, const char *domain) {
3174 search_postfix_add(base, domain);
3178 evdns_search_add(const char *domain) {
3179 evdns_base_search_add(current_base, domain);
3182 /* exported function */
3184 evdns_base_search_ndots_set(struct evdns_base *base, const int ndots) {
3186 if (!base->global_search_state) base->global_search_state = search_state_new();
3187 if (base->global_search_state)
3188 base->global_search_state->ndots = ndots;
3192 evdns_search_ndots_set(const int ndots) {
3193 evdns_base_search_ndots_set(current_base, ndots);
3197 search_set_from_hostname(struct evdns_base *base) {
3198 char hostname[HOST_NAME_MAX + 1], *domainname;
3200 ASSERT_LOCKED(base);
3201 search_postfix_clear(base);
3202 if (gethostname(hostname, sizeof(hostname))) return;
3203 domainname = strchr(hostname, '.');
3204 if (!domainname) return;
3205 search_postfix_add(base, domainname);
3208 /* warning: returns malloced string */
3210 search_make_new(const struct search_state *const state, int n, const char *const base_name) {
3211 const size_t base_len = strlen(base_name);
3212 char need_to_append_dot;
3213 struct search_domain *dom;
3215 if (!base_len) return NULL;
3216 need_to_append_dot = base_name[base_len - 1] == '.' ? 0 : 1;
3218 for (dom = state->head; dom; dom = dom->next) {
3220 /* this is the postfix we want */
3221 /* the actual postfix string is kept at the end of the structure */
3222 const u8 *const postfix = ((u8 *) dom) + sizeof(struct search_domain);
3223 const int postfix_len = dom->len;
3224 char *const newname = (char *) mm_malloc(base_len + need_to_append_dot + postfix_len + 1);
3225 if (!newname) return NULL;
3226 memcpy(newname, base_name, base_len);
3227 if (need_to_append_dot) newname[base_len] = '.';
3228 memcpy(newname + base_len + need_to_append_dot, postfix, postfix_len);
3229 newname[base_len + need_to_append_dot + postfix_len] = 0;
3234 /* we ran off the end of the list and still didn't find the requested string */
3236 return NULL; /* unreachable; stops warnings in some compilers. */
3239 static struct request *
3240 search_request_new(struct evdns_base *base, struct evdns_request *handle,
3241 int type, const char *const name, int flags,
3242 evdns_callback_type user_callback, void *user_arg) {
3243 ASSERT_LOCKED(base);
3244 EVUTIL_ASSERT(type == TYPE_A || type == TYPE_AAAA);
3245 EVUTIL_ASSERT(handle->current_req == NULL);
3246 if ( ((flags & DNS_QUERY_NO_SEARCH) == 0) &&
3247 base->global_search_state &&
3248 base->global_search_state->num_domains) {
3249 /* we have some domains to search */
3250 struct request *req;
3251 if (string_num_dots(name) >= base->global_search_state->ndots) {
3252 req = request_new(base, handle, type, name, flags, user_callback, user_arg);
3253 if (!req) return NULL;
3254 handle->search_index = -1;
3256 char *const new_name = search_make_new(base->global_search_state, 0, name);
3257 if (!new_name) return NULL;
3258 req = request_new(base, handle, type, new_name, flags, user_callback, user_arg);
3260 if (!req) return NULL;
3261 handle->search_index = 0;
3263 EVUTIL_ASSERT(handle->search_origname == NULL);
3264 handle->search_origname = mm_strdup(name);
3265 if (handle->search_origname == NULL) {
3266 /* XXX Should we dealloc req? If yes, how? */
3271 handle->search_state = base->global_search_state;
3272 handle->search_flags = flags;
3273 base->global_search_state->refcount++;
3274 request_submit(req);
3277 struct request *const req = request_new(base, handle, type, name, flags, user_callback, user_arg);
3278 if (!req) return NULL;
3279 request_submit(req);
3284 /* this is called when a request has failed to find a name. We need to check */
3285 /* if it is part of a search and, if so, try the next name in the list */
3287 /* 0 another request has been submitted */
3288 /* 1 no more requests needed */
3290 search_try_next(struct evdns_request *const handle) {
3291 struct request *req = handle->current_req;
3292 struct evdns_base *base = req->base;
3293 struct request *newreq;
3294 ASSERT_LOCKED(base);
3295 if (handle->search_state) {
3296 /* it is part of a search */
3298 handle->search_index++;
3299 if (handle->search_index >= handle->search_state->num_domains) {
3300 /* no more postfixes to try, however we may need to try */
3301 /* this name without a postfix */
3302 if (string_num_dots(handle->search_origname) < handle->search_state->ndots) {
3303 /* yep, we need to try it raw */
3304 newreq = request_new(base, NULL, req->request_type, handle->search_origname, handle->search_flags, req->user_callback, req->user_pointer);
3305 log(EVDNS_LOG_DEBUG, "Search: trying raw query %s", handle->search_origname);
3307 search_request_finished(handle);
3314 new_name = search_make_new(handle->search_state, handle->search_index, handle->search_origname);
3315 if (!new_name) return 1;
3316 log(EVDNS_LOG_DEBUG, "Search: now trying %s (%d)", new_name, handle->search_index);
3317 newreq = request_new(base, NULL, req->request_type, new_name, handle->search_flags, req->user_callback, req->user_pointer);
3319 if (!newreq) return 1;
3325 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 0);
3326 handle->current_req = newreq;
3327 newreq->handle = handle;
3328 request_submit(newreq);
3333 search_request_finished(struct evdns_request *const handle) {
3334 ASSERT_LOCKED(handle->current_req->base);
3335 if (handle->search_state) {
3336 search_state_decref(handle->search_state);
3337 handle->search_state = NULL;
3339 if (handle->search_origname) {
3340 mm_free(handle->search_origname);
3341 handle->search_origname = NULL;
3345 /* ================================================================= */
3346 /* Parsing resolv.conf files */
3349 evdns_resolv_set_defaults(struct evdns_base *base, int flags) {
3350 int add_default = flags & DNS_OPTION_NAMESERVERS;
3351 if (flags & DNS_OPTION_NAMESERVERS_NO_DEFAULT)
3354 /* if the file isn't found then we assume a local resolver */
3355 ASSERT_LOCKED(base);
3356 if (flags & DNS_OPTION_SEARCH)
3357 search_set_from_hostname(base);
3359 evdns_base_nameserver_ip_add(base, "127.0.0.1");
3362 #ifndef EVENT__HAVE_STRTOK_R
3364 strtok_r(char *s, const char *delim, char **state) {
3366 start = cp = s ? s : *state;
3369 while (*cp && !strchr(delim, *cp))
3384 /* helper version of atoi which returns -1 on error */
3386 strtoint(const char *const str)
3389 const int r = strtol(str, &endptr, 10);
3390 if (*endptr) return -1;
3394 /* Parse a number of seconds into a timeval; return -1 on error. */
3396 evdns_strtotimeval(const char *const str, struct timeval *out)
3400 d = strtod(str, &endptr);
3401 if (*endptr) return -1;
3402 if (d < 0) return -1;
3403 out->tv_sec = (int) d;
3404 out->tv_usec = (int) ((d - (int) d)*1000000);
3405 if (out->tv_sec == 0 && out->tv_usec < 1000) /* less than 1 msec */
3410 /* helper version of atoi that returns -1 on error and clips to bounds. */
3412 strtoint_clipped(const char *const str, int min, int max)
3414 int r = strtoint(str);
3426 evdns_base_set_max_requests_inflight(struct evdns_base *base, int maxinflight)
3428 int old_n_heads = base->n_req_heads, n_heads;
3429 struct request **old_heads = base->req_heads, **new_heads, *req;
3432 ASSERT_LOCKED(base);
3433 if (maxinflight < 1)
3435 n_heads = (maxinflight+4) / 5;
3436 EVUTIL_ASSERT(n_heads > 0);
3437 new_heads = mm_calloc(n_heads, sizeof(struct request*));
3441 for (i = 0; i < old_n_heads; ++i) {
3442 while (old_heads[i]) {
3444 evdns_request_remove(req, &old_heads[i]);
3445 evdns_request_insert(req, &new_heads[req->trans_id % n_heads]);
3450 base->req_heads = new_heads;
3451 base->n_req_heads = n_heads;
3452 base->global_max_requests_inflight = maxinflight;
3456 /* exported function */
3458 evdns_base_set_option(struct evdns_base *base,
3459 const char *option, const char *val)
3463 res = evdns_base_set_option_impl(base, option, val, DNS_OPTIONS_ALL);
3469 str_matches_option(const char *s1, const char *optionname)
3471 /* Option names are given as "option:" We accept either 'option' in
3472 * s1, or 'option:randomjunk'. The latter form is to implement the
3473 * resolv.conf parser. */
3474 size_t optlen = strlen(optionname);
3475 size_t slen = strlen(s1);
3476 if (slen == optlen || slen == optlen - 1)
3477 return !strncmp(s1, optionname, slen);
3478 else if (slen > optlen)
3479 return !strncmp(s1, optionname, optlen);
3485 evdns_base_set_option_impl(struct evdns_base *base,
3486 const char *option, const char *val, int flags)
3488 ASSERT_LOCKED(base);
3489 if (str_matches_option(option, "ndots:")) {
3490 const int ndots = strtoint(val);
3491 if (ndots == -1) return -1;
3492 if (!(flags & DNS_OPTION_SEARCH)) return 0;
3493 log(EVDNS_LOG_DEBUG, "Setting ndots to %d", ndots);
3494 if (!base->global_search_state) base->global_search_state = search_state_new();
3495 if (!base->global_search_state) return -1;
3496 base->global_search_state->ndots = ndots;
3497 } else if (str_matches_option(option, "timeout:")) {
3499 if (evdns_strtotimeval(val, &tv) == -1) return -1;
3500 if (!(flags & DNS_OPTION_MISC)) return 0;
3501 log(EVDNS_LOG_DEBUG, "Setting timeout to %s", val);
3502 memcpy(&base->global_timeout, &tv, sizeof(struct timeval));
3503 } else if (str_matches_option(option, "getaddrinfo-allow-skew:")) {
3505 if (evdns_strtotimeval(val, &tv) == -1) return -1;
3506 if (!(flags & DNS_OPTION_MISC)) return 0;
3507 log(EVDNS_LOG_DEBUG, "Setting getaddrinfo-allow-skew to %s",
3509 memcpy(&base->global_getaddrinfo_allow_skew, &tv,
3510 sizeof(struct timeval));
3511 } else if (str_matches_option(option, "max-timeouts:")) {
3512 const int maxtimeout = strtoint_clipped(val, 1, 255);
3513 if (maxtimeout == -1) return -1;
3514 if (!(flags & DNS_OPTION_MISC)) return 0;
3515 log(EVDNS_LOG_DEBUG, "Setting maximum allowed timeouts to %d",
3517 base->global_max_nameserver_timeout = maxtimeout;
3518 } else if (str_matches_option(option, "max-inflight:")) {
3519 const int maxinflight = strtoint_clipped(val, 1, 65000);
3520 if (maxinflight == -1) return -1;
3521 if (!(flags & DNS_OPTION_MISC)) return 0;
3522 log(EVDNS_LOG_DEBUG, "Setting maximum inflight requests to %d",
3524 evdns_base_set_max_requests_inflight(base, maxinflight);
3525 } else if (str_matches_option(option, "attempts:")) {
3526 int retries = strtoint(val);
3527 if (retries == -1) return -1;
3528 if (retries > 255) retries = 255;
3529 if (!(flags & DNS_OPTION_MISC)) return 0;
3530 log(EVDNS_LOG_DEBUG, "Setting retries to %d", retries);
3531 base->global_max_retransmits = retries;
3532 } else if (str_matches_option(option, "randomize-case:")) {
3533 int randcase = strtoint(val);
3534 if (!(flags & DNS_OPTION_MISC)) return 0;
3535 base->global_randomize_case = randcase;
3536 } else if (str_matches_option(option, "bind-to:")) {
3537 /* XXX This only applies to successive nameservers, not
3538 * to already-configured ones. We might want to fix that. */
3539 int len = sizeof(base->global_outgoing_address);
3540 if (!(flags & DNS_OPTION_NAMESERVERS)) return 0;
3541 if (evutil_parse_sockaddr_port(val,
3542 (struct sockaddr*)&base->global_outgoing_address, &len))
3544 base->global_outgoing_addrlen = len;
3545 } else if (str_matches_option(option, "initial-probe-timeout:")) {
3547 if (evdns_strtotimeval(val, &tv) == -1) return -1;
3548 if (tv.tv_sec > 3600)
3550 if (!(flags & DNS_OPTION_MISC)) return 0;
3551 log(EVDNS_LOG_DEBUG, "Setting initial probe timeout to %s",
3553 memcpy(&base->global_nameserver_probe_initial_timeout, &tv,
3555 } else if (str_matches_option(option, "so-rcvbuf:")) {
3556 int buf = strtoint(val);
3557 if (!(flags & DNS_OPTION_MISC)) return 0;
3558 log(EVDNS_LOG_DEBUG, "Setting SO_RCVBUF to %s", val);
3559 base->so_rcvbuf = buf;
3560 } else if (str_matches_option(option, "so-sndbuf:")) {
3561 int buf = strtoint(val);
3562 if (!(flags & DNS_OPTION_MISC)) return 0;
3563 log(EVDNS_LOG_DEBUG, "Setting SO_SNDBUF to %s", val);
3564 base->so_sndbuf = buf;
3570 evdns_set_option(const char *option, const char *val, int flags)
3573 current_base = evdns_base_new(NULL, 0);
3574 return evdns_base_set_option(current_base, option, val);
3578 resolv_conf_parse_line(struct evdns_base *base, char *const start, int flags) {
3580 static const char *const delims = " \t";
3581 #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state)
3584 char *const first_token = strtok_r(start, delims, &strtok_state);
3585 ASSERT_LOCKED(base);
3586 if (!first_token) return;
3588 if (!strcmp(first_token, "nameserver") && (flags & DNS_OPTION_NAMESERVERS)) {
3589 const char *const nameserver = NEXT_TOKEN;
3592 evdns_base_nameserver_ip_add(base, nameserver);
3593 } else if (!strcmp(first_token, "domain") && (flags & DNS_OPTION_SEARCH)) {
3594 const char *const domain = NEXT_TOKEN;
3596 search_postfix_clear(base);
3597 search_postfix_add(base, domain);
3599 } else if (!strcmp(first_token, "search") && (flags & DNS_OPTION_SEARCH)) {
3601 search_postfix_clear(base);
3603 while ((domain = NEXT_TOKEN)) {
3604 search_postfix_add(base, domain);
3606 search_reverse(base);
3607 } else if (!strcmp(first_token, "options")) {
3609 while ((option = NEXT_TOKEN)) {
3610 const char *val = strchr(option, ':');
3611 evdns_base_set_option_impl(base, option, val ? val+1 : "", flags);
3617 /* exported function */
3620 /* 1 failed to open file */
3621 /* 2 failed to stat file */
3622 /* 3 file too large */
3623 /* 4 out of memory */
3624 /* 5 short read from file */
3626 evdns_base_resolv_conf_parse(struct evdns_base *base, int flags, const char *const filename) {
3629 res = evdns_base_resolv_conf_parse_impl(base, flags, filename);
3635 evdns_get_default_hosts_filename(void)
3638 /* Windows is a little coy about where it puts its configuration
3639 * files. Sure, they're _usually_ in C:\windows\system32, but
3640 * there's no reason in principle they couldn't be in
3641 * W:\hoboken chicken emergency\
3643 char path[MAX_PATH+1];
3644 static const char hostfile[] = "\\drivers\\etc\\hosts";
3648 if (! SHGetSpecialFolderPathA(NULL, path, CSIDL_SYSTEM, 0))
3650 len_out = strlen(path)+strlen(hostfile)+1;
3651 path_out = mm_malloc(len_out);
3652 evutil_snprintf(path_out, len_out, "%s%s", path, hostfile);
3655 return mm_strdup("/etc/hosts");
3660 evdns_base_resolv_conf_parse_impl(struct evdns_base *base, int flags, const char *const filename) {
3667 log(EVDNS_LOG_DEBUG, "Parsing resolv.conf file %s", filename);
3669 add_default = flags & DNS_OPTION_NAMESERVERS;
3670 if (flags & DNS_OPTION_NAMESERVERS_NO_DEFAULT)
3673 if (flags & DNS_OPTION_HOSTSFILE) {
3674 char *fname = evdns_get_default_hosts_filename();
3675 evdns_base_load_hosts(base, fname);
3681 evdns_resolv_set_defaults(base, flags);
3685 if ((err = evutil_read_file_(filename, &resolv, &n, 0)) < 0) {
3688 evdns_resolv_set_defaults(base, flags);
3697 char *const newline = strchr(start, '\n');
3699 resolv_conf_parse_line(base, start, flags);
3703 resolv_conf_parse_line(base, start, flags);
3704 start = newline + 1;
3708 if (!base->server_head && add_default) {
3709 /* no nameservers were configured. */
3710 evdns_base_nameserver_ip_add(base, "127.0.0.1");
3713 if (flags & DNS_OPTION_SEARCH && (!base->global_search_state || base->global_search_state->num_domains == 0)) {
3714 search_set_from_hostname(base);
3722 evdns_resolv_conf_parse(int flags, const char *const filename) {
3724 current_base = evdns_base_new(NULL, 0);
3725 return evdns_base_resolv_conf_parse(current_base, flags, filename);
3730 /* Add multiple nameservers from a space-or-comma-separated list. */
3732 evdns_nameserver_ip_add_line(struct evdns_base *base, const char *ips) {
3736 ASSERT_LOCKED(base);
3738 while (isspace(*ips) || *ips == ',' || *ips == '\t')
3741 while (isdigit(*ips) || *ips == '.' || *ips == ':' ||
3742 *ips=='[' || *ips==']')
3744 buf = mm_malloc(ips-addr+1);
3746 memcpy(buf, addr, ips-addr);
3747 buf[ips-addr] = '\0';
3748 r = evdns_base_nameserver_ip_add(base, buf);
3755 typedef DWORD(WINAPI *GetNetworkParams_fn_t)(FIXED_INFO *, DWORD*);
3757 /* Use the windows GetNetworkParams interface in iphlpapi.dll to */
3758 /* figure out what our nameservers are. */
3760 load_nameservers_with_getnetworkparams(struct evdns_base *base)
3762 /* Based on MSDN examples and inspection of c-ares code. */
3765 ULONG size = sizeof(FIXED_INFO);
3767 int status = 0, r, added_any;
3769 GetNetworkParams_fn_t fn;
3771 ASSERT_LOCKED(base);
3772 if (!(handle = evutil_load_windows_system_library_(
3773 TEXT("iphlpapi.dll")))) {
3774 log(EVDNS_LOG_WARN, "Could not open iphlpapi.dll");
3778 if (!(fn = (GetNetworkParams_fn_t) GetProcAddress(handle, "GetNetworkParams"))) {
3779 log(EVDNS_LOG_WARN, "Could not get address of function.");
3784 buf = mm_malloc(size);
3785 if (!buf) { status = 4; goto done; }
3787 r = fn(fixed, &size);
3788 if (r != ERROR_SUCCESS && r != ERROR_BUFFER_OVERFLOW) {
3792 if (r != ERROR_SUCCESS) {
3794 buf = mm_malloc(size);
3795 if (!buf) { status = 4; goto done; }
3797 r = fn(fixed, &size);
3798 if (r != ERROR_SUCCESS) {
3799 log(EVDNS_LOG_DEBUG, "fn() failed.");
3805 EVUTIL_ASSERT(fixed);
3807 ns = &(fixed->DnsServerList);
3809 r = evdns_nameserver_ip_add_line(base, ns->IpAddress.String);
3811 log(EVDNS_LOG_DEBUG,"Could not add nameserver %s to list,error: %d",
3812 (ns->IpAddress.String),(int)GetLastError());
3816 log(EVDNS_LOG_DEBUG,"Successfully added %s as nameserver",ns->IpAddress.String);
3823 log(EVDNS_LOG_DEBUG, "No nameservers added.");
3834 FreeLibrary(handle);
3839 config_nameserver_from_reg_key(struct evdns_base *base, HKEY key, const TCHAR *subkey)
3842 DWORD bufsz = 0, type = 0;
3845 ASSERT_LOCKED(base);
3846 if (RegQueryValueEx(key, subkey, 0, &type, NULL, &bufsz)
3849 if (!(buf = mm_malloc(bufsz)))
3852 if (RegQueryValueEx(key, subkey, 0, &type, (LPBYTE)buf, &bufsz)
3853 == ERROR_SUCCESS && bufsz > 1) {
3854 status = evdns_nameserver_ip_add_line(base,buf);
3861 #define SERVICES_KEY TEXT("System\\CurrentControlSet\\Services\\")
3862 #define WIN_NS_9X_KEY SERVICES_KEY TEXT("VxD\\MSTCP")
3863 #define WIN_NS_NT_KEY SERVICES_KEY TEXT("Tcpip\\Parameters")
3866 load_nameservers_from_registry(struct evdns_base *base)
3870 #define TRY(k, name) \
3871 if (!found && config_nameserver_from_reg_key(base,k,TEXT(name)) == 0) { \
3872 log(EVDNS_LOG_DEBUG,"Found nameservers in %s/%s",#k,name); \
3874 } else if (!found) { \
3875 log(EVDNS_LOG_DEBUG,"Didn't find nameservers in %s/%s", \
3879 ASSERT_LOCKED(base);
3881 if (((int)GetVersion()) > 0) { /* NT */
3882 HKEY nt_key = 0, interfaces_key = 0;
3884 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0,
3885 KEY_READ, &nt_key) != ERROR_SUCCESS) {
3886 log(EVDNS_LOG_DEBUG,"Couldn't open nt key, %d",(int)GetLastError());
3889 r = RegOpenKeyEx(nt_key, TEXT("Interfaces"), 0,
3890 KEY_QUERY_VALUE|KEY_ENUMERATE_SUB_KEYS,
3892 if (r != ERROR_SUCCESS) {
3893 log(EVDNS_LOG_DEBUG,"Couldn't open interfaces key, %d",(int)GetLastError());
3896 TRY(nt_key, "NameServer");
3897 TRY(nt_key, "DhcpNameServer");
3898 TRY(interfaces_key, "NameServer");
3899 TRY(interfaces_key, "DhcpNameServer");
3900 RegCloseKey(interfaces_key);
3901 RegCloseKey(nt_key);
3904 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_9X_KEY, 0,
3905 KEY_READ, &win_key) != ERROR_SUCCESS) {
3906 log(EVDNS_LOG_DEBUG, "Couldn't open registry key, %d", (int)GetLastError());
3909 TRY(win_key, "NameServer");
3910 RegCloseKey(win_key);
3914 log(EVDNS_LOG_WARN,"Didn't find any nameservers.");
3917 return found ? 0 : -1;
3922 evdns_base_config_windows_nameservers(struct evdns_base *base)
3927 base = current_base;
3931 fname = evdns_get_default_hosts_filename();
3932 log(EVDNS_LOG_DEBUG, "Loading hosts entries from %s", fname);
3933 evdns_base_load_hosts(base, fname);
3937 if (load_nameservers_with_getnetworkparams(base) == 0) {
3941 r = load_nameservers_from_registry(base);
3948 evdns_config_windows_nameservers(void)
3950 if (!current_base) {
3951 current_base = evdns_base_new(NULL, 1);
3952 return current_base == NULL ? -1 : 0;
3954 return evdns_base_config_windows_nameservers(current_base);
3960 evdns_base_new(struct event_base *event_base, int flags)
3962 struct evdns_base *base;
3964 if (evutil_secure_rng_init() < 0) {
3965 log(EVDNS_LOG_WARN, "Unable to seed random number generator; "
3970 /* Give the evutil library a hook into its evdns-enabled
3971 * functionality. We can't just call evdns_getaddrinfo directly or
3972 * else libevent-core will depend on libevent-extras. */
3973 evutil_set_evdns_getaddrinfo_fn_(evdns_getaddrinfo);
3974 evutil_set_evdns_getaddrinfo_cancel_fn_(evdns_getaddrinfo_cancel);
3976 base = mm_malloc(sizeof(struct evdns_base));
3979 memset(base, 0, sizeof(struct evdns_base));
3980 base->req_waiting_head = NULL;
3982 EVTHREAD_ALLOC_LOCK(base->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
3985 /* Set max requests inflight and allocate req_heads. */
3986 base->req_heads = NULL;
3988 evdns_base_set_max_requests_inflight(base, 64);
3990 base->server_head = NULL;
3991 base->event_base = event_base;
3992 base->global_good_nameservers = base->global_requests_inflight =
3993 base->global_requests_waiting = 0;
3995 base->global_timeout.tv_sec = 5;
3996 base->global_timeout.tv_usec = 0;
3997 base->global_max_reissues = 1;
3998 base->global_max_retransmits = 3;
3999 base->global_max_nameserver_timeout = 3;
4000 base->global_search_state = NULL;
4001 base->global_randomize_case = 1;
4002 base->global_getaddrinfo_allow_skew.tv_sec = 3;
4003 base->global_getaddrinfo_allow_skew.tv_usec = 0;
4004 base->global_nameserver_probe_initial_timeout.tv_sec = 10;
4005 base->global_nameserver_probe_initial_timeout.tv_usec = 0;
4007 TAILQ_INIT(&base->hostsdb);
4009 #define EVDNS_BASE_ALL_FLAGS ( \
4010 EVDNS_BASE_INITIALIZE_NAMESERVERS | \
4011 EVDNS_BASE_DISABLE_WHEN_INACTIVE | \
4012 EVDNS_BASE_NAMESERVERS_NO_DEFAULT | \
4015 if (flags & ~EVDNS_BASE_ALL_FLAGS) {
4016 flags = EVDNS_BASE_INITIALIZE_NAMESERVERS;
4018 "Unrecognized flag passed to evdns_base_new(). Assuming "
4019 "you meant EVDNS_BASE_INITIALIZE_NAMESERVERS.");
4021 #undef EVDNS_BASE_ALL_FLAGS
4023 if (flags & EVDNS_BASE_INITIALIZE_NAMESERVERS) {
4025 int opts = DNS_OPTIONS_ALL;
4026 if (flags & EVDNS_BASE_NAMESERVERS_NO_DEFAULT) {
4027 opts |= DNS_OPTION_NAMESERVERS_NO_DEFAULT;
4031 r = evdns_base_config_windows_nameservers(base);
4033 r = evdns_base_resolv_conf_parse(base, opts, "/etc/resolv.conf");
4036 evdns_base_free_and_unlock(base, 0);
4040 if (flags & EVDNS_BASE_DISABLE_WHEN_INACTIVE) {
4041 base->disable_when_inactive = 1;
4051 struct evdns_base *base = evdns_base_new(NULL, 1);
4053 current_base = base;
4061 evdns_err_to_string(int err)
4064 case DNS_ERR_NONE: return "no error";
4065 case DNS_ERR_FORMAT: return "misformatted query";
4066 case DNS_ERR_SERVERFAILED: return "server failed";
4067 case DNS_ERR_NOTEXIST: return "name does not exist";
4068 case DNS_ERR_NOTIMPL: return "query not implemented";
4069 case DNS_ERR_REFUSED: return "refused";
4071 case DNS_ERR_TRUNCATED: return "reply truncated or ill-formed";
4072 case DNS_ERR_UNKNOWN: return "unknown";
4073 case DNS_ERR_TIMEOUT: return "request timed out";
4074 case DNS_ERR_SHUTDOWN: return "dns subsystem shut down";
4075 case DNS_ERR_CANCEL: return "dns request canceled";
4076 case DNS_ERR_NODATA: return "no records in the reply";
4077 default: return "[Unknown error code]";
4082 evdns_nameserver_free(struct nameserver *server)
4084 if (server->socket >= 0)
4085 evutil_closesocket(server->socket);
4086 (void) event_del(&server->event);
4087 event_debug_unassign(&server->event);
4088 if (server->state == 0)
4089 (void) event_del(&server->timeout_event);
4090 if (server->probe_request) {
4091 evdns_cancel_request(server->base, server->probe_request);
4092 server->probe_request = NULL;
4094 event_debug_unassign(&server->timeout_event);
4099 evdns_base_free_and_unlock(struct evdns_base *base, int fail_requests)
4101 struct nameserver *server, *server_next;
4102 struct search_domain *dom, *dom_next;
4105 /* Requires that we hold the lock. */
4107 /* TODO(nickm) we might need to refcount here. */
4109 for (i = 0; i < base->n_req_heads; ++i) {
4110 while (base->req_heads[i]) {
4112 reply_schedule_callback(base->req_heads[i], 0, DNS_ERR_SHUTDOWN, NULL);
4113 request_finished(base->req_heads[i], &REQ_HEAD(base, base->req_heads[i]->trans_id), 1);
4116 while (base->req_waiting_head) {
4118 reply_schedule_callback(base->req_waiting_head, 0, DNS_ERR_SHUTDOWN, NULL);
4119 request_finished(base->req_waiting_head, &base->req_waiting_head, 1);
4121 base->global_requests_inflight = base->global_requests_waiting = 0;
4123 for (server = base->server_head; server; server = server_next) {
4124 server_next = server->next;
4125 /** already done something before */
4126 server->probe_request = NULL;
4127 evdns_nameserver_free(server);
4128 if (server_next == base->server_head)
4131 base->server_head = NULL;
4132 base->global_good_nameservers = 0;
4134 if (base->global_search_state) {
4135 for (dom = base->global_search_state->head; dom; dom = dom_next) {
4136 dom_next = dom->next;
4139 mm_free(base->global_search_state);
4140 base->global_search_state = NULL;
4144 struct hosts_entry *victim;
4145 while ((victim = TAILQ_FIRST(&base->hostsdb))) {
4146 TAILQ_REMOVE(&base->hostsdb, victim, next);
4151 mm_free(base->req_heads);
4154 EVTHREAD_FREE_LOCK(base->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
4160 evdns_base_free(struct evdns_base *base, int fail_requests)
4163 evdns_base_free_and_unlock(base, fail_requests);
4167 evdns_base_clear_host_addresses(struct evdns_base *base)
4169 struct hosts_entry *victim;
4171 while ((victim = TAILQ_FIRST(&base->hostsdb))) {
4172 TAILQ_REMOVE(&base->hostsdb, victim, next);
4179 evdns_shutdown(int fail_requests)
4182 struct evdns_base *b = current_base;
4183 current_base = NULL;
4184 evdns_base_free(b, fail_requests);
4186 evdns_log_fn = NULL;
4190 evdns_base_parse_hosts_line(struct evdns_base *base, char *line)
4193 static const char *const delims = " \t";
4194 char *const addr = strtok_r(line, delims, &strtok_state);
4195 char *hostname, *hash;
4196 struct sockaddr_storage ss;
4197 int socklen = sizeof(ss);
4198 ASSERT_LOCKED(base);
4200 #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state)
4202 if (!addr || *addr == '#')
4205 memset(&ss, 0, sizeof(ss));
4206 if (evutil_parse_sockaddr_port(addr, (struct sockaddr*)&ss, &socklen)<0)
4208 if (socklen > (int)sizeof(struct sockaddr_in6))
4211 if (sockaddr_getport((struct sockaddr*)&ss))
4214 while ((hostname = NEXT_TOKEN)) {
4215 struct hosts_entry *he;
4217 if ((hash = strchr(hostname, '#'))) {
4218 if (hash == hostname)
4223 namelen = strlen(hostname);
4225 he = mm_calloc(1, sizeof(struct hosts_entry)+namelen);
4228 EVUTIL_ASSERT(socklen <= (int)sizeof(he->addr));
4229 memcpy(&he->addr, &ss, socklen);
4230 memcpy(he->hostname, hostname, namelen+1);
4231 he->addrlen = socklen;
4233 TAILQ_INSERT_TAIL(&base->hostsdb, he, next);
4244 evdns_base_load_hosts_impl(struct evdns_base *base, const char *hosts_fname)
4246 char *str=NULL, *cp, *eol;
4250 ASSERT_LOCKED(base);
4252 if (hosts_fname == NULL ||
4253 (err = evutil_read_file_(hosts_fname, &str, &len, 0)) < 0) {
4255 strlcpy(tmp, "127.0.0.1 localhost", sizeof(tmp));
4256 evdns_base_parse_hosts_line(base, tmp);
4257 strlcpy(tmp, "::1 localhost", sizeof(tmp));
4258 evdns_base_parse_hosts_line(base, tmp);
4259 return err ? -1 : 0;
4262 /* This will break early if there is a NUL in the hosts file.
4263 * Probably not a problem.*/
4266 eol = strchr(cp, '\n');
4270 evdns_base_parse_hosts_line(base, cp);
4273 evdns_base_parse_hosts_line(base, cp);
4283 evdns_base_load_hosts(struct evdns_base *base, const char *hosts_fname)
4287 base = current_base;
4289 res = evdns_base_load_hosts_impl(base, hosts_fname);
4294 /* A single request for a getaddrinfo, either v4 or v6. */
4295 struct getaddrinfo_subrequest {
4296 struct evdns_request *r;
4300 /* State data used to implement an in-progress getaddrinfo. */
4301 struct evdns_getaddrinfo_request {
4302 struct evdns_base *evdns_base;
4303 /* Copy of the modified 'hints' data that we'll use to build
4305 struct evutil_addrinfo hints;
4306 /* The callback to invoke when we're done */
4307 evdns_getaddrinfo_cb user_cb;
4308 /* User-supplied data to give to the callback. */
4310 /* The port to use when building sockaddrs. */
4312 /* The sub_request for an A record (if any) */
4313 struct getaddrinfo_subrequest ipv4_request;
4314 /* The sub_request for an AAAA record (if any) */
4315 struct getaddrinfo_subrequest ipv6_request;
4317 /* The cname result that we were told (if any) */
4320 /* If we have one request answered and one request still inflight,
4321 * then this field holds the answer from the first request... */
4322 struct evutil_addrinfo *pending_result;
4323 /* And this event is a timeout that will tell us to cancel the second
4324 * request if it's taking a long time. */
4325 struct event timeout;
4327 /* And this field holds the error code from the first request... */
4329 /* If this is set, the user canceled this request. */
4330 unsigned user_canceled : 1;
4331 /* If this is set, the user can no longer cancel this request; we're
4332 * just waiting for the free. */
4333 unsigned request_done : 1;
4336 /* Convert an evdns errors to the equivalent getaddrinfo error. */
4338 evdns_err_to_getaddrinfo_err(int e1)
4340 /* XXX Do this better! */
4341 if (e1 == DNS_ERR_NONE)
4343 else if (e1 == DNS_ERR_NOTEXIST)
4344 return EVUTIL_EAI_NONAME;
4346 return EVUTIL_EAI_FAIL;
4349 /* Return the more informative of two getaddrinfo errors. */
4351 getaddrinfo_merge_err(int e1, int e2)
4353 /* XXXX be cleverer here. */
4361 free_getaddrinfo_request(struct evdns_getaddrinfo_request *data)
4363 /* DO NOT CALL this if either of the requests is pending. Only once
4364 * both callbacks have been invoked is it safe to free the request */
4365 if (data->pending_result)
4366 evutil_freeaddrinfo(data->pending_result);
4367 if (data->cname_result)
4368 mm_free(data->cname_result);
4369 event_del(&data->timeout);
4375 add_cname_to_reply(struct evdns_getaddrinfo_request *data,
4376 struct evutil_addrinfo *ai)
4378 if (data->cname_result && ai) {
4379 ai->ai_canonname = data->cname_result;
4380 data->cname_result = NULL;
4384 /* Callback: invoked when one request in a mixed-format A/AAAA getaddrinfo
4385 * request has finished, but the other one took too long to answer. Pass
4386 * along the answer we got, and cancel the other request.
4389 evdns_getaddrinfo_timeout_cb(evutil_socket_t fd, short what, void *ptr)
4391 int v4_timedout = 0, v6_timedout = 0;
4392 struct evdns_getaddrinfo_request *data = ptr;
4394 /* Cancel any pending requests, and note which one */
4395 if (data->ipv4_request.r) {
4396 /* XXXX This does nothing if the request's callback is already
4397 * running (pending_cb is set). */
4398 evdns_cancel_request(NULL, data->ipv4_request.r);
4400 EVDNS_LOCK(data->evdns_base);
4401 ++data->evdns_base->getaddrinfo_ipv4_timeouts;
4402 EVDNS_UNLOCK(data->evdns_base);
4404 if (data->ipv6_request.r) {
4405 /* XXXX This does nothing if the request's callback is already
4406 * running (pending_cb is set). */
4407 evdns_cancel_request(NULL, data->ipv6_request.r);
4409 EVDNS_LOCK(data->evdns_base);
4410 ++data->evdns_base->getaddrinfo_ipv6_timeouts;
4411 EVDNS_UNLOCK(data->evdns_base);
4414 /* We only use this timeout callback when we have an answer for
4416 EVUTIL_ASSERT(!v4_timedout || !v6_timedout);
4418 /* Report the outcome of the other request that didn't time out. */
4419 if (data->pending_result) {
4420 add_cname_to_reply(data, data->pending_result);
4421 data->user_cb(0, data->pending_result, data->user_data);
4422 data->pending_result = NULL;
4424 int e = data->pending_error;
4426 e = EVUTIL_EAI_AGAIN;
4427 data->user_cb(e, NULL, data->user_data);
4430 data->user_cb = NULL; /* prevent double-call if evdns callbacks are
4431 * in-progress. XXXX It would be better if this
4432 * weren't necessary. */
4434 if (!v4_timedout && !v6_timedout) {
4435 /* should be impossible? XXXX */
4436 free_getaddrinfo_request(data);
4441 evdns_getaddrinfo_set_timeout(struct evdns_base *evdns_base,
4442 struct evdns_getaddrinfo_request *data)
4444 return event_add(&data->timeout, &evdns_base->global_getaddrinfo_allow_skew);
4448 evdns_result_is_answer(int result)
4450 return (result != DNS_ERR_NOTIMPL && result != DNS_ERR_REFUSED &&
4451 result != DNS_ERR_SERVERFAILED && result != DNS_ERR_CANCEL);
4455 evdns_getaddrinfo_gotresolve(int result, char type, int count,
4456 int ttl, void *addresses, void *arg)
4459 struct getaddrinfo_subrequest *req = arg;
4460 struct getaddrinfo_subrequest *other_req;
4461 struct evdns_getaddrinfo_request *data;
4463 struct evutil_addrinfo *res;
4465 struct sockaddr_in sin;
4466 struct sockaddr_in6 sin6;
4467 struct sockaddr *sa;
4468 int socklen, addrlen;
4473 EVUTIL_ASSERT(req->type == DNS_IPv4_A || req->type == DNS_IPv6_AAAA);
4474 if (req->type == DNS_IPv4_A) {
4475 data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv4_request);
4476 other_req = &data->ipv6_request;
4478 data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv6_request);
4479 other_req = &data->ipv4_request;
4482 /** Called from evdns_base_free() with @fail_requests == 1 */
4483 if (result != DNS_ERR_SHUTDOWN) {
4484 EVDNS_LOCK(data->evdns_base);
4485 if (evdns_result_is_answer(result)) {
4486 if (req->type == DNS_IPv4_A)
4487 ++data->evdns_base->getaddrinfo_ipv4_answered;
4489 ++data->evdns_base->getaddrinfo_ipv6_answered;
4491 user_canceled = data->user_canceled;
4492 if (other_req->r == NULL)
4493 data->request_done = 1;
4494 EVDNS_UNLOCK(data->evdns_base);
4496 data->evdns_base = NULL;
4497 user_canceled = data->user_canceled;
4502 if (result == DNS_ERR_CANCEL && ! user_canceled) {
4503 /* Internal cancel request from timeout or internal error.
4504 * we already answered the user. */
4505 if (other_req->r == NULL)
4506 free_getaddrinfo_request(data);
4510 if (data->user_cb == NULL) {
4511 /* We already answered. XXXX This shouldn't be needed; see
4512 * comments in evdns_getaddrinfo_timeout_cb */
4513 free_getaddrinfo_request(data);
4517 if (result == DNS_ERR_NONE) {
4519 err = EVUTIL_EAI_NODATA;
4523 err = evdns_err_to_getaddrinfo_err(result);
4527 /* Looks like we got an error. */
4529 /* The other request is still working; maybe it will
4531 /* XXXX handle failure from set_timeout */
4532 if (result != DNS_ERR_SHUTDOWN) {
4533 evdns_getaddrinfo_set_timeout(data->evdns_base, data);
4535 data->pending_error = err;
4539 if (user_canceled) {
4540 data->user_cb(EVUTIL_EAI_CANCEL, NULL, data->user_data);
4541 } else if (data->pending_result) {
4542 /* If we have an answer waiting, and we weren't
4543 * canceled, ignore this error. */
4544 add_cname_to_reply(data, data->pending_result);
4545 data->user_cb(0, data->pending_result, data->user_data);
4546 data->pending_result = NULL;
4548 if (data->pending_error)
4549 err = getaddrinfo_merge_err(err,
4550 data->pending_error);
4551 data->user_cb(err, NULL, data->user_data);
4553 free_getaddrinfo_request(data);
4555 } else if (user_canceled) {
4557 /* The other request is still working; let it hit this
4558 * callback with EVUTIL_EAI_CANCEL callback and report
4562 data->user_cb(EVUTIL_EAI_CANCEL, NULL, data->user_data);
4563 free_getaddrinfo_request(data);
4567 /* Looks like we got some answers. We should turn them into addrinfos
4568 * and then either queue those or return them all. */
4569 EVUTIL_ASSERT(type == DNS_IPv4_A || type == DNS_IPv6_AAAA);
4571 if (type == DNS_IPv4_A) {
4572 memset(&sin, 0, sizeof(sin));
4573 sin.sin_family = AF_INET;
4574 sin.sin_port = htons(data->port);
4576 sa = (struct sockaddr *)&sin;
4577 socklen = sizeof(sin);
4579 addrp = &sin.sin_addr.s_addr;
4581 memset(&sin6, 0, sizeof(sin6));
4582 sin6.sin6_family = AF_INET6;
4583 sin6.sin6_port = htons(data->port);
4585 sa = (struct sockaddr *)&sin6;
4586 socklen = sizeof(sin6);
4588 addrp = &sin6.sin6_addr.s6_addr;
4592 for (i=0; i < count; ++i) {
4593 struct evutil_addrinfo *ai;
4594 memcpy(addrp, ((char*)addresses)+i*addrlen, addrlen);
4595 ai = evutil_new_addrinfo_(sa, socklen, &data->hints);
4598 evdns_cancel_request(NULL, other_req->r);
4600 data->user_cb(EVUTIL_EAI_MEMORY, NULL, data->user_data);
4602 evutil_freeaddrinfo(res);
4604 if (other_req->r == NULL)
4605 free_getaddrinfo_request(data);
4608 res = evutil_addrinfo_append_(res, ai);
4612 /* The other request is still in progress; wait for it */
4613 /* XXXX handle failure from set_timeout */
4614 evdns_getaddrinfo_set_timeout(data->evdns_base, data);
4615 data->pending_result = res;
4618 /* The other request is done or never started; append its
4619 * results (if any) and return them. */
4620 if (data->pending_result) {
4621 if (req->type == DNS_IPv4_A)
4622 res = evutil_addrinfo_append_(res,
4623 data->pending_result);
4625 res = evutil_addrinfo_append_(
4626 data->pending_result, res);
4627 data->pending_result = NULL;
4630 /* Call the user callback. */
4631 add_cname_to_reply(data, res);
4632 data->user_cb(0, res, data->user_data);
4635 free_getaddrinfo_request(data);
4639 static struct hosts_entry *
4640 find_hosts_entry(struct evdns_base *base, const char *hostname,
4641 struct hosts_entry *find_after)
4643 struct hosts_entry *e;
4646 e = TAILQ_NEXT(find_after, next);
4648 e = TAILQ_FIRST(&base->hostsdb);
4650 for (; e; e = TAILQ_NEXT(e, next)) {
4651 if (!evutil_ascii_strcasecmp(e->hostname, hostname))
4658 evdns_getaddrinfo_fromhosts(struct evdns_base *base,
4659 const char *nodename, struct evutil_addrinfo *hints, ev_uint16_t port,
4660 struct evutil_addrinfo **res)
4663 struct hosts_entry *e;
4664 struct evutil_addrinfo *ai=NULL;
4665 int f = hints->ai_family;
4668 for (e = find_hosts_entry(base, nodename, NULL); e;
4669 e = find_hosts_entry(base, nodename, e)) {
4670 struct evutil_addrinfo *ai_new;
4672 if ((e->addr.sa.sa_family == AF_INET && f == PF_INET6) ||
4673 (e->addr.sa.sa_family == AF_INET6 && f == PF_INET))
4675 ai_new = evutil_new_addrinfo_(&e->addr.sa, e->addrlen, hints);
4680 sockaddr_setport(ai_new->ai_addr, port);
4681 ai = evutil_addrinfo_append_(ai, ai_new);
4686 /* Note that we return an empty answer if we found entries for
4687 * this hostname but none were of the right address type. */
4692 evutil_freeaddrinfo(ai);
4697 struct evdns_getaddrinfo_request *
4698 evdns_getaddrinfo(struct evdns_base *dns_base,
4699 const char *nodename, const char *servname,
4700 const struct evutil_addrinfo *hints_in,
4701 evdns_getaddrinfo_cb cb, void *arg)
4703 struct evdns_getaddrinfo_request *data;
4704 struct evutil_addrinfo hints;
4705 struct evutil_addrinfo *res = NULL;
4712 dns_base = current_base;
4715 "Call to getaddrinfo_async with no "
4716 "evdns_base configured.");
4717 cb(EVUTIL_EAI_FAIL, NULL, arg); /* ??? better error? */
4722 /* If we _must_ answer this immediately, do so. */
4723 if ((hints_in && (hints_in->ai_flags & EVUTIL_AI_NUMERICHOST))) {
4725 err = evutil_getaddrinfo(nodename, servname, hints_in, &res);
4731 memcpy(&hints, hints_in, sizeof(hints));
4733 memset(&hints, 0, sizeof(hints));
4734 hints.ai_family = PF_UNSPEC;
4737 evutil_adjust_hints_for_addrconfig_(&hints);
4739 /* Now try to see if we _can_ answer immediately. */
4740 /* (It would be nice to do this by calling getaddrinfo directly, with
4741 * AI_NUMERICHOST, on plaforms that have it, but we can't: there isn't
4742 * a reliable way to distinguish the "that wasn't a numeric host!" case
4743 * from any other EAI_NONAME cases.) */
4744 err = evutil_getaddrinfo_common_(nodename, servname, &hints, &res, &port);
4745 if (err != EVUTIL_EAI_NEED_RESOLVE) {
4750 /* If there is an entry in the hosts file, we should give it now. */
4751 if (!evdns_getaddrinfo_fromhosts(dns_base, nodename, &hints, port, &res)) {
4756 /* Okay, things are serious now. We're going to need to actually
4759 data = mm_calloc(1,sizeof(struct evdns_getaddrinfo_request));
4761 cb(EVUTIL_EAI_MEMORY, NULL, arg);
4765 memcpy(&data->hints, &hints, sizeof(data->hints));
4766 data->port = (ev_uint16_t)port;
4767 data->ipv4_request.type = DNS_IPv4_A;
4768 data->ipv6_request.type = DNS_IPv6_AAAA;
4770 data->user_data = arg;
4771 data->evdns_base = dns_base;
4773 want_cname = (hints.ai_flags & EVUTIL_AI_CANONNAME);
4775 /* If we are asked for a PF_UNSPEC address, we launch two requests in
4776 * parallel: one for an A address and one for an AAAA address. We
4777 * can't send just one request, since many servers only answer one
4778 * question per DNS request.
4780 * Once we have the answer to one request, we allow for a short
4781 * timeout before we report it, to see if the other one arrives. If
4782 * they both show up in time, then we report both the answers.
4784 * If too many addresses of one type time out or fail, we should stop
4785 * launching those requests. (XXX we don't do that yet.)
4788 EVDNS_LOCK(dns_base);
4790 if (hints.ai_family != PF_INET6) {
4791 log(EVDNS_LOG_DEBUG, "Sending request for %s on ipv4 as %p",
4792 nodename, &data->ipv4_request);
4794 data->ipv4_request.r = evdns_base_resolve_ipv4(dns_base,
4795 nodename, 0, evdns_getaddrinfo_gotresolve,
4796 &data->ipv4_request);
4797 if (want_cname && data->ipv4_request.r)
4798 data->ipv4_request.r->current_req->put_cname_in_ptr =
4799 &data->cname_result;
4801 if (hints.ai_family != PF_INET) {
4802 log(EVDNS_LOG_DEBUG, "Sending request for %s on ipv6 as %p",
4803 nodename, &data->ipv6_request);
4805 data->ipv6_request.r = evdns_base_resolve_ipv6(dns_base,
4806 nodename, 0, evdns_getaddrinfo_gotresolve,
4807 &data->ipv6_request);
4808 if (want_cname && data->ipv6_request.r)
4809 data->ipv6_request.r->current_req->put_cname_in_ptr =
4810 &data->cname_result;
4813 evtimer_assign(&data->timeout, dns_base->event_base,
4814 evdns_getaddrinfo_timeout_cb, data);
4816 started = (data->ipv4_request.r || data->ipv6_request.r);
4818 EVDNS_UNLOCK(dns_base);
4824 cb(EVUTIL_EAI_FAIL, NULL, arg);
4830 evdns_getaddrinfo_cancel(struct evdns_getaddrinfo_request *data)
4832 EVDNS_LOCK(data->evdns_base);
4833 if (data->request_done) {
4834 EVDNS_UNLOCK(data->evdns_base);
4837 event_del(&data->timeout);
4838 data->user_canceled = 1;
4839 if (data->ipv4_request.r)
4840 evdns_cancel_request(data->evdns_base, data->ipv4_request.r);
4841 if (data->ipv6_request.r)
4842 evdns_cancel_request(data->evdns_base, data->ipv6_request.r);
4843 EVDNS_UNLOCK(data->evdns_base);