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 <sys/types.h>
52 #include "event2/event-config.h"
54 #ifndef _FORTIFY_SOURCE
55 #define _FORTIFY_SOURCE 3
60 #ifdef _EVENT_HAVE_SYS_TIME_H
63 #ifdef _EVENT_HAVE_STDINT_H
69 #ifdef _EVENT_HAVE_UNISTD_H
80 #define _WIN32_IE 0x400
85 #include "event2/dns.h"
86 #include "event2/dns_struct.h"
87 #include "event2/dns_compat.h"
88 #include "event2/util.h"
89 #include "event2/event.h"
90 #include "event2/event_struct.h"
91 #include "event2/thread.h"
93 #include "event2/bufferevent.h"
94 #include "event2/bufferevent_struct.h"
95 #include "bufferevent-internal.h"
97 #include "defer-internal.h"
98 #include "log-internal.h"
99 #include "mm-internal.h"
100 #include "strlcpy-internal.h"
101 #include "ipv6-internal.h"
102 #include "util-internal.h"
103 #include "evthread-internal.h"
106 #include <winsock2.h>
108 #include <iphlpapi.h>
111 #include <sys/socket.h>
112 #include <netinet/in.h>
113 #include <arpa/inet.h>
116 #ifdef _EVENT_HAVE_NETINET_IN6_H
117 #include <netinet/in6.h>
120 #define EVDNS_LOG_DEBUG 0
121 #define EVDNS_LOG_WARN 1
122 #define EVDNS_LOG_MSG 2
124 #ifndef HOST_NAME_MAX
125 #define HOST_NAME_MAX 255
131 #define MIN(a,b) ((a)<(b)?(a):(b))
133 #define ASSERT_VALID_REQUEST(req) \
134 EVUTIL_ASSERT((req)->handle && (req)->handle->current_req == (req))
136 #define u64 ev_uint64_t
137 #define u32 ev_uint32_t
138 #define u16 ev_uint16_t
139 #define u8 ev_uint8_t
141 /* maximum number of addresses from a single packet */
142 /* that we bother recording */
143 #define MAX_V4_ADDRS 32
144 #define MAX_V6_ADDRS 32
147 #define TYPE_A EVDNS_TYPE_A
149 #define TYPE_PTR EVDNS_TYPE_PTR
150 #define TYPE_SOA EVDNS_TYPE_SOA
151 #define TYPE_AAAA EVDNS_TYPE_AAAA
153 #define CLASS_INET EVDNS_CLASS_INET
155 /* Persistent handle. We keep this separate from 'struct request' since we
156 * need some object to last for as long as an evdns_request is outstanding so
157 * that it can be canceled, whereas a search request can lead to multiple
158 * 'struct request' instances being created over its lifetime. */
159 struct evdns_request {
160 struct request *current_req;
161 struct evdns_base *base;
163 int pending_cb; /* Waiting for its callback to be invoked; not
164 * owned by event base any more. */
166 /* elements used by the searching code */
168 struct search_state *search_state;
169 char *search_origname; /* needs to be free()ed */
174 u8 *request; /* the dns packet data */
175 u8 request_type; /* TYPE_PTR or TYPE_A or TYPE_AAAA */
176 unsigned int request_len;
178 int tx_count; /* the number of times that this packet has been sent */
179 void *user_pointer; /* the pointer given to us for this request */
180 evdns_callback_type user_callback;
181 struct nameserver *ns; /* the server which we last sent it */
183 /* these objects are kept in a circular list */
184 /* XXX We could turn this into a CIRCLEQ. */
185 struct request *next, *prev;
187 struct event timeout_event;
189 u16 trans_id; /* the transaction id */
190 unsigned request_appended :1; /* true if the request pointer is data which follows this struct */
191 unsigned transmit_me :1; /* needs to be transmitted */
193 /* XXXX This is a horrible hack. */
194 char **put_cname_in_ptr; /* store the cname here if we get one. */
196 struct evdns_base *base;
198 struct evdns_request *handle;
203 unsigned int have_answer : 1;
207 u32 addresses[MAX_V4_ADDRS];
211 struct in6_addr addresses[MAX_V6_ADDRS];
214 char name[HOST_NAME_MAX];
220 evutil_socket_t socket; /* a connected UDP socket */
221 struct sockaddr_storage address;
222 ev_socklen_t addrlen;
223 int failed_times; /* number of times which we have given this server a chance */
224 int timedout; /* number of times in a row a request has timed out */
226 /* these objects are kept in a circular list */
227 struct nameserver *next, *prev;
228 struct event timeout_event; /* used to keep the timeout for */
229 /* when we next probe this server. */
230 /* Valid if state == 0 */
231 /* Outstanding probe request for this nameserver, if any */
232 struct evdns_request *probe_request;
233 char state; /* zero if we think that this server is down */
234 char choked; /* true if we have an EAGAIN from this server's socket */
235 char write_waiting; /* true if we are waiting for EV_WRITE events */
236 struct evdns_base *base;
240 /* Represents a local port where we're listening for DNS requests. Right now, */
241 /* only UDP is supported. */
242 struct evdns_server_port {
243 evutil_socket_t socket; /* socket we use to read queries and write replies. */
244 int refcnt; /* reference count. */
245 char choked; /* Are we currently blocked from writing? */
246 char closing; /* Are we trying to close this port, pending writes? */
247 evdns_request_callback_fn_type user_callback; /* Fn to handle requests */
248 void *user_data; /* Opaque pointer passed to user_callback */
249 struct event event; /* Read/write event */
250 /* circular list of replies that we want to write. */
251 struct server_request *pending_replies;
252 struct event_base *event_base;
254 #ifndef _EVENT_DISABLE_THREAD_SUPPORT
259 /* Represents part of a reply being built. (That is, a single RR.) */
260 struct server_reply_item {
261 struct server_reply_item *next; /* next item in sequence. */
262 char *name; /* name part of the RR */
263 u16 type; /* The RR type */
264 u16 class; /* The RR class (usually CLASS_INET) */
265 u32 ttl; /* The RR TTL */
266 char is_name; /* True iff data is a label */
267 u16 datalen; /* Length of data; -1 if data is a label */
268 void *data; /* The contents of the RR */
271 /* Represents a request that we've received as a DNS server, and holds */
272 /* the components of the reply as we're constructing it. */
273 struct server_request {
274 /* Pointers to the next and previous entries on the list of replies */
275 /* that we're waiting to write. Only set if we have tried to respond */
276 /* and gotten EAGAIN. */
277 struct server_request *next_pending;
278 struct server_request *prev_pending;
280 u16 trans_id; /* Transaction id. */
281 struct evdns_server_port *port; /* Which port received this request on? */
282 struct sockaddr_storage addr; /* Where to send the response */
283 ev_socklen_t addrlen; /* length of addr */
285 int n_answer; /* how many answer RRs have been set? */
286 int n_authority; /* how many authority RRs have been set? */
287 int n_additional; /* how many additional RRs have been set? */
289 struct server_reply_item *answer; /* linked list of answer RRs */
290 struct server_reply_item *authority; /* linked list of authority RRs */
291 struct server_reply_item *additional; /* linked list of additional RRs */
293 /* Constructed response. Only set once we're ready to send a reply. */
294 /* Once this is set, the RR fields are cleared, and no more should be set. */
298 /* Caller-visible fields: flags, questions. */
299 struct evdns_server_request base;
303 /* An array of n_req_heads circular lists for inflight requests.
304 * Each inflight request req is in req_heads[req->trans_id % n_req_heads].
306 struct request **req_heads;
307 /* A circular list of requests that we're waiting to send, but haven't
308 * sent yet because there are too many requests inflight */
309 struct request *req_waiting_head;
310 /* A circular list of nameservers. */
311 struct nameserver *server_head;
314 struct event_base *event_base;
316 /* The number of good nameservers that we have */
317 int global_good_nameservers;
319 /* inflight requests are contained in the req_head list */
320 /* and are actually going out across the network */
321 int global_requests_inflight;
322 /* requests which aren't inflight are in the waiting list */
323 /* and are counted here */
324 int global_requests_waiting;
326 int global_max_requests_inflight;
328 struct timeval global_timeout; /* 5 seconds by default */
329 int global_max_reissues; /* a reissue occurs when we get some errors from the server */
330 int global_max_retransmits; /* number of times we'll retransmit a request which timed out */
331 /* number of timeouts in a row before we consider this server to be down */
332 int global_max_nameserver_timeout;
333 /* true iff we will use the 0x20 hack to prevent poisoning attacks. */
334 int global_randomize_case;
336 /* The first time that a nameserver fails, how long do we wait before
337 * probing to see if it has returned? */
338 struct timeval global_nameserver_probe_initial_timeout;
340 /** Port to bind to for outgoing DNS packets. */
341 struct sockaddr_storage global_outgoing_address;
342 /** ev_socklen_t for global_outgoing_address. 0 if it isn't set. */
343 ev_socklen_t global_outgoing_addrlen;
345 struct timeval global_getaddrinfo_allow_skew;
347 int getaddrinfo_ipv4_timeouts;
348 int getaddrinfo_ipv6_timeouts;
349 int getaddrinfo_ipv4_answered;
350 int getaddrinfo_ipv6_answered;
352 struct search_state *global_search_state;
354 TAILQ_HEAD(hosts_list, hosts_entry) hostsdb;
356 #ifndef _EVENT_DISABLE_THREAD_SUPPORT
362 TAILQ_ENTRY(hosts_entry) next;
365 struct sockaddr_in sin;
366 struct sockaddr_in6 sin6;
372 static struct evdns_base *current_base = NULL;
375 evdns_get_global_base(void)
380 /* Given a pointer to an evdns_server_request, get the corresponding */
381 /* server_request. */
382 #define TO_SERVER_REQUEST(base_ptr) \
383 ((struct server_request*) \
384 (((char*)(base_ptr) - evutil_offsetof(struct server_request, base))))
386 #define REQ_HEAD(base, id) ((base)->req_heads[id % (base)->n_req_heads])
388 static struct nameserver *nameserver_pick(struct evdns_base *base);
389 static void evdns_request_insert(struct request *req, struct request **head);
390 static void evdns_request_remove(struct request *req, struct request **head);
391 static void nameserver_ready_callback(evutil_socket_t fd, short events, void *arg);
392 static int evdns_transmit(struct evdns_base *base);
393 static int evdns_request_transmit(struct request *req);
394 static void nameserver_send_probe(struct nameserver *const ns);
395 static void search_request_finished(struct evdns_request *const);
396 static int search_try_next(struct evdns_request *const req);
397 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);
398 static void evdns_requests_pump_waiting_queue(struct evdns_base *base);
399 static u16 transaction_id_pick(struct evdns_base *base);
400 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);
401 static void request_submit(struct request *const req);
403 static int server_request_free(struct server_request *req);
404 static void server_request_free_answers(struct server_request *req);
405 static void server_port_free(struct evdns_server_port *port);
406 static void server_port_ready_callback(evutil_socket_t fd, short events, void *arg);
407 static int evdns_base_resolv_conf_parse_impl(struct evdns_base *base, int flags, const char *const filename);
408 static int evdns_base_set_option_impl(struct evdns_base *base,
409 const char *option, const char *val, int flags);
410 static void evdns_base_free_and_unlock(struct evdns_base *base, int fail_requests);
412 static int strtoint(const char *const str);
414 #ifdef _EVENT_DISABLE_THREAD_SUPPORT
415 #define EVDNS_LOCK(base) _EVUTIL_NIL_STMT
416 #define EVDNS_UNLOCK(base) _EVUTIL_NIL_STMT
417 #define ASSERT_LOCKED(base) _EVUTIL_NIL_STMT
419 #define EVDNS_LOCK(base) \
420 EVLOCK_LOCK((base)->lock, 0)
421 #define EVDNS_UNLOCK(base) \
422 EVLOCK_UNLOCK((base)->lock, 0)
423 #define ASSERT_LOCKED(base) \
424 EVLOCK_ASSERT_LOCKED((base)->lock)
428 default_evdns_log_fn(int warning, const char *buf)
430 if (warning == EVDNS_LOG_WARN)
431 event_warnx("[evdns] %s", buf);
432 else if (warning == EVDNS_LOG_MSG)
433 event_msgx("[evdns] %s", buf);
435 event_debug(("[evdns] %s", buf));
438 static evdns_debug_log_fn_type evdns_log_fn = NULL;
441 evdns_set_log_fn(evdns_debug_log_fn_type fn)
447 #define EVDNS_LOG_CHECK __attribute__ ((format(printf, 2, 3)))
449 #define EVDNS_LOG_CHECK
452 static void _evdns_log(int warn, const char *fmt, ...) EVDNS_LOG_CHECK;
454 _evdns_log(int warn, const char *fmt, ...)
461 evutil_vsnprintf(buf, sizeof(buf), fmt, args);
464 if (warn == EVDNS_LOG_MSG)
465 warn = EVDNS_LOG_WARN;
466 evdns_log_fn(warn, buf);
468 default_evdns_log_fn(warn, buf);
473 #define log _evdns_log
475 /* This walks the list of inflight requests to find the */
476 /* one with a matching transaction id. Returns NULL on */
478 static struct request *
479 request_find_from_trans_id(struct evdns_base *base, u16 trans_id) {
480 struct request *req = REQ_HEAD(base, trans_id);
481 struct request *const started_at = req;
487 if (req->trans_id == trans_id) return req;
489 } while (req != started_at);
495 /* a libevent callback function which is called when a nameserver */
496 /* has gone down and we want to test if it has came back to life yet */
498 nameserver_prod_callback(evutil_socket_t fd, short events, void *arg) {
499 struct nameserver *const ns = (struct nameserver *) arg;
503 EVDNS_LOCK(ns->base);
504 nameserver_send_probe(ns);
505 EVDNS_UNLOCK(ns->base);
508 /* a libevent callback which is called when a nameserver probe (to see if */
509 /* it has come back to life) times out. We increment the count of failed_times */
510 /* and wait longer to send the next probe packet. */
512 nameserver_probe_failed(struct nameserver *const ns) {
513 struct timeval timeout;
516 ASSERT_LOCKED(ns->base);
517 (void) evtimer_del(&ns->timeout_event);
518 if (ns->state == 1) {
519 /* This can happen if the nameserver acts in a way which makes us mark */
520 /* it as bad and then starts sending good replies. */
524 #define MAX_PROBE_TIMEOUT 3600
525 #define TIMEOUT_BACKOFF_FACTOR 3
527 memcpy(&timeout, &ns->base->global_nameserver_probe_initial_timeout,
528 sizeof(struct timeval));
529 for (i=ns->failed_times; i > 0 && timeout.tv_sec < MAX_PROBE_TIMEOUT; --i) {
530 timeout.tv_sec *= TIMEOUT_BACKOFF_FACTOR;
531 timeout.tv_usec *= TIMEOUT_BACKOFF_FACTOR;
532 if (timeout.tv_usec > 1000000) {
533 timeout.tv_sec += timeout.tv_usec / 1000000;
534 timeout.tv_usec %= 1000000;
537 if (timeout.tv_sec > MAX_PROBE_TIMEOUT) {
538 timeout.tv_sec = MAX_PROBE_TIMEOUT;
544 if (evtimer_add(&ns->timeout_event, &timeout) < 0) {
547 "Error from libevent when adding timer event for %s",
548 evutil_format_sockaddr_port(
549 (struct sockaddr *)&ns->address,
550 addrbuf, sizeof(addrbuf)));
554 /* called when a nameserver has been deemed to have failed. For example, too */
555 /* many packets have timed out etc */
557 nameserver_failed(struct nameserver *const ns, const char *msg) {
558 struct request *req, *started_at;
559 struct evdns_base *base = ns->base;
564 /* if this nameserver has already been marked as failed */
565 /* then don't do anything */
566 if (!ns->state) return;
568 log(EVDNS_LOG_MSG, "Nameserver %s has failed: %s",
569 evutil_format_sockaddr_port(
570 (struct sockaddr *)&ns->address,
571 addrbuf, sizeof(addrbuf)),
574 base->global_good_nameservers--;
575 EVUTIL_ASSERT(base->global_good_nameservers >= 0);
576 if (base->global_good_nameservers == 0) {
577 log(EVDNS_LOG_MSG, "All nameservers have failed");
581 ns->failed_times = 1;
583 if (evtimer_add(&ns->timeout_event,
584 &base->global_nameserver_probe_initial_timeout) < 0) {
586 "Error from libevent when adding timer event for %s",
587 evutil_format_sockaddr_port(
588 (struct sockaddr *)&ns->address,
589 addrbuf, sizeof(addrbuf)));
593 /* walk the list of inflight requests to see if any can be reassigned to */
594 /* a different server. Requests in the waiting queue don't have a */
595 /* nameserver assigned yet */
597 /* if we don't have *any* good nameservers then there's no point */
598 /* trying to reassign requests to one */
599 if (!base->global_good_nameservers) return;
601 for (i = 0; i < base->n_req_heads; ++i) {
602 req = started_at = base->req_heads[i];
605 if (req->tx_count == 0 && req->ns == ns) {
606 /* still waiting to go out, can be moved */
607 /* to another server */
608 req->ns = nameserver_pick(base);
611 } while (req != started_at);
617 nameserver_up(struct nameserver *const ns)
620 ASSERT_LOCKED(ns->base);
621 if (ns->state) return;
622 log(EVDNS_LOG_MSG, "Nameserver %s is back up",
623 evutil_format_sockaddr_port(
624 (struct sockaddr *)&ns->address,
625 addrbuf, sizeof(addrbuf)));
626 evtimer_del(&ns->timeout_event);
627 if (ns->probe_request) {
628 evdns_cancel_request(ns->base, ns->probe_request);
629 ns->probe_request = NULL;
632 ns->failed_times = 0;
634 ns->base->global_good_nameservers++;
638 request_trans_id_set(struct request *const req, const u16 trans_id) {
639 req->trans_id = trans_id;
640 *((u16 *) req->request) = htons(trans_id);
643 /* Called to remove a request from a list and dealloc it. */
644 /* head is a pointer to the head of the list it should be */
645 /* removed from or NULL if the request isn't in a list. */
646 /* when free_handle is one, free the handle as well. */
648 request_finished(struct request *const req, struct request **head, int free_handle) {
649 struct evdns_base *base = req->base;
650 int was_inflight = (head != &base->req_waiting_head);
652 ASSERT_VALID_REQUEST(req);
655 evdns_request_remove(req, head);
657 log(EVDNS_LOG_DEBUG, "Removing timeout for request %p", req);
659 evtimer_del(&req->timeout_event);
660 base->global_requests_inflight--;
662 base->global_requests_waiting--;
664 /* it was initialized during request_new / evtimer_assign */
665 event_debug_unassign(&req->timeout_event);
667 if (!req->request_appended) {
668 /* need to free the request data on it's own */
669 mm_free(req->request);
671 /* the request data is appended onto the header */
672 /* so everything gets free()ed when we: */
676 EVUTIL_ASSERT(req->handle->current_req == req);
679 search_request_finished(req->handle);
680 req->handle->current_req = NULL;
681 if (! req->handle->pending_cb) {
682 /* If we're planning to run the callback,
683 * don't free the handle until later. */
684 mm_free(req->handle);
686 req->handle = NULL; /* If we have a bug, let's crash
689 req->handle->current_req = NULL;
695 evdns_requests_pump_waiting_queue(base);
699 /* This is called when a server returns a funny error code. */
700 /* We try the request again with another server. */
704 /* 1 failed/reissue is pointless */
706 request_reissue(struct request *req) {
707 const struct nameserver *const last_ns = req->ns;
708 ASSERT_LOCKED(req->base);
709 ASSERT_VALID_REQUEST(req);
710 /* the last nameserver should have been marked as failing */
711 /* by the caller of this function, therefore pick will try */
712 /* not to return it */
713 req->ns = nameserver_pick(req->base);
714 if (req->ns == last_ns) {
715 /* ... but pick did return it */
716 /* not a lot of point in trying again with the */
721 req->reissue_count++;
723 req->transmit_me = 1;
728 /* this function looks for space on the inflight queue and promotes */
729 /* requests from the waiting queue if it can. */
731 evdns_requests_pump_waiting_queue(struct evdns_base *base) {
733 while (base->global_requests_inflight < base->global_max_requests_inflight &&
734 base->global_requests_waiting) {
736 /* move a request from the waiting queue to the inflight queue */
737 EVUTIL_ASSERT(base->req_waiting_head);
738 req = base->req_waiting_head;
739 evdns_request_remove(req, &base->req_waiting_head);
741 base->global_requests_waiting--;
742 base->global_requests_inflight++;
744 req->ns = nameserver_pick(base);
745 request_trans_id_set(req, transaction_id_pick(base));
747 evdns_request_insert(req, &REQ_HEAD(base, req->trans_id));
748 evdns_request_transmit(req);
749 evdns_transmit(base);
753 /* TODO(nickm) document */
754 struct deferred_reply_callback {
755 struct deferred_cb deferred;
756 struct evdns_request *handle;
761 evdns_callback_type user_callback;
766 reply_run_callback(struct deferred_cb *d, void *user_pointer)
768 struct deferred_reply_callback *cb =
769 EVUTIL_UPCAST(d, struct deferred_reply_callback, deferred);
771 switch (cb->request_type) {
774 cb->user_callback(DNS_ERR_NONE, DNS_IPv4_A,
775 cb->reply.data.a.addrcount, cb->ttl,
776 cb->reply.data.a.addresses,
779 cb->user_callback(cb->err, 0, 0, cb->ttl, NULL, user_pointer);
782 if (cb->have_reply) {
783 char *name = cb->reply.data.ptr.name;
784 cb->user_callback(DNS_ERR_NONE, DNS_PTR, 1, cb->ttl,
785 &name, user_pointer);
787 cb->user_callback(cb->err, 0, 0, cb->ttl, NULL, user_pointer);
792 cb->user_callback(DNS_ERR_NONE, DNS_IPv6_AAAA,
793 cb->reply.data.aaaa.addrcount, cb->ttl,
794 cb->reply.data.aaaa.addresses,
797 cb->user_callback(cb->err, 0, 0, cb->ttl, NULL, user_pointer);
803 if (cb->handle && cb->handle->pending_cb) {
811 reply_schedule_callback(struct request *const req, u32 ttl, u32 err, struct reply *reply)
813 struct deferred_reply_callback *d = mm_calloc(1, sizeof(*d));
816 event_warn("%s: Couldn't allocate space for deferred callback.",
821 ASSERT_LOCKED(req->base);
823 d->request_type = req->request_type;
824 d->user_callback = req->user_callback;
829 memcpy(&d->reply, reply, sizeof(struct reply));
833 req->handle->pending_cb = 1;
834 d->handle = req->handle;
837 event_deferred_cb_init(&d->deferred, reply_run_callback,
839 event_deferred_cb_schedule(
840 event_base_get_deferred_cb_queue(req->base->event_base),
844 /* this processes a parsed reply packet */
846 reply_handle(struct request *const req, u16 flags, u32 ttl, struct reply *reply) {
849 static const int error_codes[] = {
850 DNS_ERR_FORMAT, DNS_ERR_SERVERFAILED, DNS_ERR_NOTEXIST,
851 DNS_ERR_NOTIMPL, DNS_ERR_REFUSED
854 ASSERT_LOCKED(req->base);
855 ASSERT_VALID_REQUEST(req);
857 if (flags & 0x020f || !reply || !reply->have_answer) {
858 /* there was an error */
859 if (flags & 0x0200) {
860 error = DNS_ERR_TRUNCATED;
861 } else if (flags & 0x000f) {
862 u16 error_code = (flags & 0x000f) - 1;
863 if (error_code > 4) {
864 error = DNS_ERR_UNKNOWN;
866 error = error_codes[error_code];
868 } else if (reply && !reply->have_answer) {
869 error = DNS_ERR_NODATA;
871 error = DNS_ERR_UNKNOWN;
875 case DNS_ERR_NOTIMPL:
876 case DNS_ERR_REFUSED:
877 /* we regard these errors as marking a bad nameserver */
878 if (req->reissue_count < req->base->global_max_reissues) {
880 evutil_snprintf(msg, sizeof(msg), "Bad response %d (%s)",
881 error, evdns_err_to_string(error));
882 nameserver_failed(req->ns, msg);
883 if (!request_reissue(req)) return;
886 case DNS_ERR_SERVERFAILED:
887 /* rcode 2 (servfailed) sometimes means "we
888 * are broken" and sometimes (with some binds)
889 * means "that request was very confusing."
890 * Treat this as a timeout, not a failure.
892 log(EVDNS_LOG_DEBUG, "Got a SERVERFAILED from nameserver"
893 "at %s; will allow the request to time out.",
894 evutil_format_sockaddr_port(
895 (struct sockaddr *)&req->ns->address,
896 addrbuf, sizeof(addrbuf)));
899 /* we got a good reply from the nameserver: it is up. */
900 if (req->handle == req->ns->probe_request) {
901 /* Avoid double-free */
902 req->ns->probe_request = NULL;
905 nameserver_up(req->ns);
908 if (req->handle->search_state &&
909 req->request_type != TYPE_PTR) {
910 /* if we have a list of domains to search in,
911 * try the next one */
912 if (!search_try_next(req->handle)) {
913 /* a new request was issued so this
914 * request is finished and */
915 /* the user callback will be made when
916 * that request (or a */
917 /* child of it) finishes. */
922 /* all else failed. Pass the failure up */
923 reply_schedule_callback(req, ttl, error, NULL);
924 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1);
926 /* all ok, tell the user */
927 reply_schedule_callback(req, ttl, 0, reply);
928 if (req->handle == req->ns->probe_request)
929 req->ns->probe_request = NULL; /* Avoid double-free */
930 nameserver_up(req->ns);
931 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1);
936 name_parse(u8 *packet, int length, int *idx, char *name_out, int name_out_len) {
940 #define GET32(x) do { if (j + 4 > length) goto err; memcpy(&_t32, packet + j, 4); j += 4; x = ntohl(_t32); } while (0)
941 #define GET16(x) do { if (j + 2 > length) goto err; memcpy(&_t, packet + j, 2); j += 2; x = ntohs(_t); } while (0)
942 #define GET8(x) do { if (j >= length) goto err; x = packet[j++]; } while (0)
945 const char *const end = name_out + name_out_len;
947 /* Normally, names are a series of length prefixed strings terminated */
948 /* with a length of 0 (the lengths are u8's < 63). */
949 /* However, the length can start with a pair of 1 bits and that */
950 /* means that the next 14 bits are a pointer within the current */
955 if (j >= length) return -1;
957 if (!label_len) break;
958 if (label_len & 0xc0) {
961 if (name_end < 0) name_end = j;
962 j = (((int)label_len & 0x3f) << 8) + ptr_low;
963 /* Make sure that the target offset is in-bounds. */
964 if (j < 0 || j >= length) return -1;
965 /* If we've jumped more times than there are characters in the
966 * message, we must have a loop. */
967 if (++ptr_count > length) return -1;
970 if (label_len > 63) return -1;
971 if (cp != name_out) {
972 if (cp + 1 >= end) return -1;
975 if (cp + label_len >= end) return -1;
976 memcpy(cp, packet + j, label_len);
980 if (cp >= end) return -1;
991 /* parses a raw request from a nameserver */
993 reply_parse(struct evdns_base *base, u8 *packet, int length) {
994 int j = 0, k = 0; /* index into packet */
995 u16 _t; /* used by the macros */
996 u32 _t32; /* used by the macros */
997 char tmp_name[256], cmp_name[256]; /* used by the macros */
998 int name_matches = 0;
1000 u16 trans_id, questions, answers, authority, additional, datalength;
1002 u32 ttl, ttl_r = 0xffffffff;
1004 struct request *req = NULL;
1007 ASSERT_LOCKED(base);
1015 (void) authority; /* suppress "unused variable" warnings. */
1016 (void) additional; /* suppress "unused variable" warnings. */
1018 req = request_find_from_trans_id(base, trans_id);
1019 if (!req) return -1;
1020 EVUTIL_ASSERT(req->base == base);
1022 memset(&reply, 0, sizeof(reply));
1024 /* If it's not an answer, it doesn't correspond to any request. */
1025 if (!(flags & 0x8000)) return -1; /* must be an answer */
1026 if ((flags & 0x020f) && (flags & 0x020f) != DNS_ERR_NOTEXIST) {
1027 /* there was an error and it's not NXDOMAIN */
1030 /* if (!answers) return; */ /* must have an answer of some form */
1032 /* This macro skips a name in the DNS reply. */
1034 do { tmp_name[0] = '\0'; \
1035 if (name_parse(packet, length, &j, tmp_name, \
1036 sizeof(tmp_name))<0) \
1040 do { tmp_name[0] = '\0'; \
1041 cmp_name[0] = '\0'; \
1043 if (name_parse(packet, length, &j, tmp_name, \
1044 sizeof(tmp_name))<0) \
1046 if (name_parse(req->request, req->request_len, &k, \
1047 cmp_name, sizeof(cmp_name))<0) \
1049 if (base->global_randomize_case) { \
1050 if (strcmp(tmp_name, cmp_name) == 0) \
1053 if (evutil_ascii_strcasecmp(tmp_name, cmp_name) == 0) \
1058 reply.type = req->request_type;
1060 /* skip over each question in the reply */
1061 for (i = 0; i < questions; ++i) {
1062 /* the question looks like
1063 * <label:name><u16:type><u16:class>
1067 if (j > length) goto err;
1073 /* now we have the answer section which looks like
1074 * <label:name><u16:type><u16:class><u32:ttl><u16:len><data...>
1077 for (i = 0; i < answers; ++i) {
1086 if (type == TYPE_A && class == CLASS_INET) {
1087 int addrcount, addrtocopy;
1088 if (req->request_type != TYPE_A) {
1089 j += datalength; continue;
1091 if ((datalength & 3) != 0) /* not an even number of As. */
1093 addrcount = datalength >> 2;
1094 addrtocopy = MIN(MAX_V4_ADDRS - reply.data.a.addrcount, (unsigned)addrcount);
1096 ttl_r = MIN(ttl_r, ttl);
1097 /* we only bother with the first four addresses. */
1098 if (j + 4*addrtocopy > length) goto err;
1099 memcpy(&reply.data.a.addresses[reply.data.a.addrcount],
1100 packet + j, 4*addrtocopy);
1102 reply.data.a.addrcount += addrtocopy;
1103 reply.have_answer = 1;
1104 if (reply.data.a.addrcount == MAX_V4_ADDRS) break;
1105 } else if (type == TYPE_PTR && class == CLASS_INET) {
1106 if (req->request_type != TYPE_PTR) {
1107 j += datalength; continue;
1109 if (name_parse(packet, length, &j, reply.data.ptr.name,
1110 sizeof(reply.data.ptr.name))<0)
1112 ttl_r = MIN(ttl_r, ttl);
1113 reply.have_answer = 1;
1115 } else if (type == TYPE_CNAME) {
1116 char cname[HOST_NAME_MAX];
1117 if (!req->put_cname_in_ptr || *req->put_cname_in_ptr) {
1118 j += datalength; continue;
1120 if (name_parse(packet, length, &j, cname,
1123 *req->put_cname_in_ptr = mm_strdup(cname);
1124 } else if (type == TYPE_AAAA && class == CLASS_INET) {
1125 int addrcount, addrtocopy;
1126 if (req->request_type != TYPE_AAAA) {
1127 j += datalength; continue;
1129 if ((datalength & 15) != 0) /* not an even number of AAAAs. */
1131 addrcount = datalength >> 4; /* each address is 16 bytes long */
1132 addrtocopy = MIN(MAX_V6_ADDRS - reply.data.aaaa.addrcount, (unsigned)addrcount);
1133 ttl_r = MIN(ttl_r, ttl);
1135 /* we only bother with the first four addresses. */
1136 if (j + 16*addrtocopy > length) goto err;
1137 memcpy(&reply.data.aaaa.addresses[reply.data.aaaa.addrcount],
1138 packet + j, 16*addrtocopy);
1139 reply.data.aaaa.addrcount += addrtocopy;
1141 reply.have_answer = 1;
1142 if (reply.data.aaaa.addrcount == MAX_V6_ADDRS) break;
1144 /* skip over any other type of resource */
1149 if (!reply.have_answer) {
1150 for (i = 0; i < authority; ++i) {
1157 if (type == TYPE_SOA && class == CLASS_INET) {
1158 u32 serial, refresh, retry, expire, minimum;
1170 ttl_r = MIN(ttl_r, ttl);
1171 ttl_r = MIN(ttl_r, minimum);
1173 /* skip over any other type of resource */
1179 if (ttl_r == 0xffffffff)
1182 reply_handle(req, flags, ttl_r, &reply);
1186 reply_handle(req, flags, 0, NULL);
1190 /* Parse a raw request (packet,length) sent to a nameserver port (port) from */
1191 /* a DNS client (addr,addrlen), and if it's well-formed, call the corresponding */
1194 request_parse(u8 *packet, int length, struct evdns_server_port *port, struct sockaddr *addr, ev_socklen_t addrlen)
1196 int j = 0; /* index into packet */
1197 u16 _t; /* used by the macros */
1198 char tmp_name[256]; /* used by the macros */
1201 u16 trans_id, flags, questions, answers, authority, additional;
1202 struct server_request *server_req = NULL;
1204 ASSERT_LOCKED(port);
1206 /* Get the header fields */
1217 if (flags & 0x8000) return -1; /* Must not be an answer. */
1218 flags &= 0x0110; /* Only RD and CD get preserved. */
1220 server_req = mm_malloc(sizeof(struct server_request));
1221 if (server_req == NULL) return -1;
1222 memset(server_req, 0, sizeof(struct server_request));
1224 server_req->trans_id = trans_id;
1225 memcpy(&server_req->addr, addr, addrlen);
1226 server_req->addrlen = addrlen;
1228 server_req->base.flags = flags;
1229 server_req->base.nquestions = 0;
1230 server_req->base.questions = mm_calloc(sizeof(struct evdns_server_question *), questions);
1231 if (server_req->base.questions == NULL)
1234 for (i = 0; i < questions; ++i) {
1236 struct evdns_server_question *q;
1238 if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0)
1242 namelen = (int)strlen(tmp_name);
1243 q = mm_malloc(sizeof(struct evdns_server_question) + namelen);
1247 q->dns_question_class = class;
1248 memcpy(q->name, tmp_name, namelen+1);
1249 server_req->base.questions[server_req->base.nquestions++] = q;
1252 /* Ignore answers, authority, and additional. */
1254 server_req->port = port;
1257 /* Only standard queries are supported. */
1258 if (flags & 0x7800) {
1259 evdns_server_request_respond(&(server_req->base), DNS_ERR_NOTIMPL);
1263 port->user_callback(&(server_req->base), port->user_data);
1268 if (server_req->base.questions) {
1269 for (i = 0; i < server_req->base.nquestions; ++i)
1270 mm_free(server_req->base.questions[i]);
1271 mm_free(server_req->base.questions);
1273 mm_free(server_req);
1285 evdns_set_transaction_id_fn(ev_uint16_t (*fn)(void))
1290 evdns_set_random_bytes_fn(void (*fn)(char *, size_t))
1294 /* Try to choose a strong transaction id which isn't already in flight */
1296 transaction_id_pick(struct evdns_base *base) {
1297 ASSERT_LOCKED(base);
1300 evutil_secure_rng_get_bytes(&trans_id, sizeof(trans_id));
1302 if (trans_id == 0xffff) continue;
1303 /* now check to see if that id is already inflight */
1304 if (request_find_from_trans_id(base, trans_id) == NULL)
1309 /* choose a namesever to use. This function will try to ignore */
1310 /* nameservers which we think are down and load balance across the rest */
1311 /* by updating the server_head global each time. */
1312 static struct nameserver *
1313 nameserver_pick(struct evdns_base *base) {
1314 struct nameserver *started_at = base->server_head, *picked;
1315 ASSERT_LOCKED(base);
1316 if (!base->server_head) return NULL;
1318 /* if we don't have any good nameservers then there's no */
1319 /* point in trying to find one. */
1320 if (!base->global_good_nameservers) {
1321 base->server_head = base->server_head->next;
1322 return base->server_head;
1325 /* remember that nameservers are in a circular list */
1327 if (base->server_head->state) {
1328 /* we think this server is currently good */
1329 picked = base->server_head;
1330 base->server_head = base->server_head->next;
1334 base->server_head = base->server_head->next;
1335 if (base->server_head == started_at) {
1336 /* all the nameservers seem to be down */
1337 /* so we just return this one and hope for the */
1339 EVUTIL_ASSERT(base->global_good_nameservers == 0);
1340 picked = base->server_head;
1341 base->server_head = base->server_head->next;
1347 /* this is called when a namesever socket is ready for reading */
1349 nameserver_read(struct nameserver *ns) {
1350 struct sockaddr_storage ss;
1351 ev_socklen_t addrlen = sizeof(ss);
1354 ASSERT_LOCKED(ns->base);
1357 const int r = recvfrom(ns->socket, (void*)packet,
1359 (struct sockaddr*)&ss, &addrlen);
1361 int err = evutil_socket_geterror(ns->socket);
1362 if (EVUTIL_ERR_RW_RETRIABLE(err))
1364 nameserver_failed(ns,
1365 evutil_socket_error_to_string(err));
1368 if (evutil_sockaddr_cmp((struct sockaddr*)&ss,
1369 (struct sockaddr*)&ns->address, 0)) {
1370 log(EVDNS_LOG_WARN, "Address mismatch on received "
1371 "DNS packet. Apparent source was %s",
1372 evutil_format_sockaddr_port(
1373 (struct sockaddr *)&ss,
1374 addrbuf, sizeof(addrbuf)));
1379 reply_parse(ns->base, packet, r);
1383 /* Read a packet from a DNS client on a server port s, parse it, and */
1384 /* act accordingly. */
1386 server_port_read(struct evdns_server_port *s) {
1388 struct sockaddr_storage addr;
1389 ev_socklen_t addrlen;
1394 addrlen = sizeof(struct sockaddr_storage);
1395 r = recvfrom(s->socket, (void*)packet, sizeof(packet), 0,
1396 (struct sockaddr*) &addr, &addrlen);
1398 int err = evutil_socket_geterror(s->socket);
1399 if (EVUTIL_ERR_RW_RETRIABLE(err))
1402 "Error %s (%d) while reading request.",
1403 evutil_socket_error_to_string(err), err);
1406 request_parse(packet, r, s, (struct sockaddr*) &addr, addrlen);
1410 /* Try to write all pending replies on a given DNS server port. */
1412 server_port_flush(struct evdns_server_port *port)
1414 struct server_request *req = port->pending_replies;
1415 ASSERT_LOCKED(port);
1417 int r = sendto(port->socket, req->response, (int)req->response_len, 0,
1418 (struct sockaddr*) &req->addr, (ev_socklen_t)req->addrlen);
1420 int err = evutil_socket_geterror(port->socket);
1421 if (EVUTIL_ERR_RW_RETRIABLE(err))
1423 log(EVDNS_LOG_WARN, "Error %s (%d) while writing response to port; dropping", evutil_socket_error_to_string(err), err);
1425 if (server_request_free(req)) {
1426 /* we released the last reference to req->port. */
1429 EVUTIL_ASSERT(req != port->pending_replies);
1430 req = port->pending_replies;
1434 /* We have no more pending requests; stop listening for 'writeable' events. */
1435 (void) event_del(&port->event);
1436 event_assign(&port->event, port->event_base,
1437 port->socket, EV_READ | EV_PERSIST,
1438 server_port_ready_callback, port);
1440 if (event_add(&port->event, NULL) < 0) {
1441 log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server.");
1446 /* set if we are waiting for the ability to write to this server. */
1447 /* if waiting is true then we ask libevent for EV_WRITE events, otherwise */
1448 /* we stop these events. */
1450 nameserver_write_waiting(struct nameserver *ns, char waiting) {
1451 ASSERT_LOCKED(ns->base);
1452 if (ns->write_waiting == waiting) return;
1454 ns->write_waiting = waiting;
1455 (void) event_del(&ns->event);
1456 event_assign(&ns->event, ns->base->event_base,
1457 ns->socket, EV_READ | (waiting ? EV_WRITE : 0) | EV_PERSIST,
1458 nameserver_ready_callback, ns);
1459 if (event_add(&ns->event, NULL) < 0) {
1461 log(EVDNS_LOG_WARN, "Error from libevent when adding event for %s",
1462 evutil_format_sockaddr_port(
1463 (struct sockaddr *)&ns->address,
1464 addrbuf, sizeof(addrbuf)));
1469 /* a callback function. Called by libevent when the kernel says that */
1470 /* a nameserver socket is ready for writing or reading */
1472 nameserver_ready_callback(evutil_socket_t fd, short events, void *arg) {
1473 struct nameserver *ns = (struct nameserver *) arg;
1476 EVDNS_LOCK(ns->base);
1477 if (events & EV_WRITE) {
1479 if (!evdns_transmit(ns->base)) {
1480 nameserver_write_waiting(ns, 0);
1483 if (events & EV_READ) {
1484 nameserver_read(ns);
1486 EVDNS_UNLOCK(ns->base);
1489 /* a callback function. Called by libevent when the kernel says that */
1490 /* a server socket is ready for writing or reading. */
1492 server_port_ready_callback(evutil_socket_t fd, short events, void *arg) {
1493 struct evdns_server_port *port = (struct evdns_server_port *) arg;
1497 if (events & EV_WRITE) {
1499 server_port_flush(port);
1501 if (events & EV_READ) {
1502 server_port_read(port);
1507 /* This is an inefficient representation; only use it via the dnslabel_table_*
1508 * functions, so that is can be safely replaced with something smarter later. */
1509 #define MAX_LABELS 128
1510 /* Structures used to implement name compression */
1511 struct dnslabel_entry { char *v; off_t pos; };
1512 struct dnslabel_table {
1513 int n_labels; /* number of current entries */
1514 /* map from name to position in message */
1515 struct dnslabel_entry labels[MAX_LABELS];
1518 /* Initialize dnslabel_table. */
1520 dnslabel_table_init(struct dnslabel_table *table)
1522 table->n_labels = 0;
1525 /* Free all storage held by table, but not the table itself. */
1527 dnslabel_clear(struct dnslabel_table *table)
1530 for (i = 0; i < table->n_labels; ++i)
1531 mm_free(table->labels[i].v);
1532 table->n_labels = 0;
1535 /* return the position of the label in the current message, or -1 if the label */
1536 /* hasn't been used yet. */
1538 dnslabel_table_get_pos(const struct dnslabel_table *table, const char *label)
1541 for (i = 0; i < table->n_labels; ++i) {
1542 if (!strcmp(label, table->labels[i].v))
1543 return table->labels[i].pos;
1548 /* remember that we've used the label at position pos */
1550 dnslabel_table_add(struct dnslabel_table *table, const char *label, off_t pos)
1554 if (table->n_labels == MAX_LABELS)
1556 v = mm_strdup(label);
1559 p = table->n_labels++;
1560 table->labels[p].v = v;
1561 table->labels[p].pos = pos;
1566 /* Converts a string to a length-prefixed set of DNS labels, starting */
1567 /* at buf[j]. name and buf must not overlap. name_len should be the length */
1568 /* of name. table is optional, and is used for compression. */
1570 /* Input: abc.def */
1571 /* Output: <3>abc<3>def<0> */
1573 /* Returns the first index after the encoded name, or negative on error. */
1574 /* -1 label was > 63 bytes */
1575 /* -2 name too long to fit in buffer. */
1578 dnsname_to_labels(u8 *const buf, size_t buf_len, off_t j,
1579 const char *name, const size_t name_len,
1580 struct dnslabel_table *table) {
1581 const char *end = name + name_len;
1585 #define APPEND16(x) do { \
1586 if (j + 2 > (off_t)buf_len) \
1589 memcpy(buf + j, &_t, 2); \
1592 #define APPEND32(x) do { \
1593 if (j + 4 > (off_t)buf_len) \
1596 memcpy(buf + j, &_t32, 4); \
1600 if (name_len > 255) return -2;
1603 const char *const start = name;
1604 if (table && (ref = dnslabel_table_get_pos(table, name)) >= 0) {
1605 APPEND16(ref | 0xc000);
1608 name = strchr(name, '.');
1610 const size_t label_len = end - start;
1611 if (label_len > 63) return -1;
1612 if ((size_t)(j+label_len+1) > buf_len) return -2;
1613 if (table) dnslabel_table_add(table, start, j);
1614 buf[j++] = (ev_uint8_t)label_len;
1616 memcpy(buf + j, start, label_len);
1617 j += (int) label_len;
1620 /* append length of the label. */
1621 const size_t label_len = name - start;
1622 if (label_len > 63) return -1;
1623 if ((size_t)(j+label_len+1) > buf_len) return -2;
1624 if (table) dnslabel_table_add(table, start, j);
1625 buf[j++] = (ev_uint8_t)label_len;
1627 memcpy(buf + j, start, label_len);
1628 j += (int) label_len;
1629 /* hop over the '.' */
1634 /* the labels must be terminated by a 0. */
1635 /* It's possible that the name ended in a . */
1636 /* in which case the zero is already there */
1637 if (!j || buf[j-1]) buf[j++] = 0;
1643 /* Finds the length of a dns request for a DNS name of the given */
1644 /* length. The actual request may be smaller than the value returned */
1647 evdns_request_len(const size_t name_len) {
1648 return 96 + /* length of the DNS standard header */
1650 4; /* space for the resource type */
1653 /* build a dns request packet into buf. buf should be at least as long */
1654 /* as evdns_request_len told you it should be. */
1656 /* Returns the amount of space used. Negative on error. */
1658 evdns_request_data_build(const char *const name, const size_t name_len,
1659 const u16 trans_id, const u16 type, const u16 class,
1660 u8 *const buf, size_t buf_len) {
1661 off_t j = 0; /* current offset into buf */
1662 u16 _t; /* used by the macros */
1665 APPEND16(0x0100); /* standard query, recusion needed */
1666 APPEND16(1); /* one question */
1667 APPEND16(0); /* no answers */
1668 APPEND16(0); /* no authority */
1669 APPEND16(0); /* no additional */
1671 j = dnsname_to_labels(buf, buf_len, j, name, name_len, NULL);
1684 /* exported function */
1685 struct evdns_server_port *
1686 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)
1688 struct evdns_server_port *port;
1690 return NULL; /* flags not yet implemented */
1691 if (!(port = mm_malloc(sizeof(struct evdns_server_port))))
1693 memset(port, 0, sizeof(struct evdns_server_port));
1696 port->socket = socket;
1700 port->user_callback = cb;
1701 port->user_data = user_data;
1702 port->pending_replies = NULL;
1703 port->event_base = base;
1705 event_assign(&port->event, port->event_base,
1706 port->socket, EV_READ | EV_PERSIST,
1707 server_port_ready_callback, port);
1708 if (event_add(&port->event, NULL) < 0) {
1712 EVTHREAD_ALLOC_LOCK(port->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
1716 struct evdns_server_port *
1717 evdns_add_server_port(evutil_socket_t socket, int flags, evdns_request_callback_fn_type cb, void *user_data)
1719 return evdns_add_server_port_with_base(NULL, socket, flags, cb, user_data);
1722 /* exported function */
1724 evdns_close_server_port(struct evdns_server_port *port)
1727 if (--port->refcnt == 0) {
1729 server_port_free(port);
1735 /* exported function */
1737 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)
1739 struct server_request *req = TO_SERVER_REQUEST(_req);
1740 struct server_reply_item **itemp, *item;
1744 EVDNS_LOCK(req->port);
1745 if (req->response) /* have we already answered? */
1749 case EVDNS_ANSWER_SECTION:
1750 itemp = &req->answer;
1751 countp = &req->n_answer;
1753 case EVDNS_AUTHORITY_SECTION:
1754 itemp = &req->authority;
1755 countp = &req->n_authority;
1757 case EVDNS_ADDITIONAL_SECTION:
1758 itemp = &req->additional;
1759 countp = &req->n_additional;
1765 itemp = &((*itemp)->next);
1767 item = mm_malloc(sizeof(struct server_reply_item));
1771 if (!(item->name = mm_strdup(name))) {
1776 item->dns_question_class = class;
1778 item->is_name = is_name != 0;
1782 if (item->is_name) {
1783 if (!(item->data = mm_strdup(data))) {
1784 mm_free(item->name);
1788 item->datalen = (u16)-1;
1790 if (!(item->data = mm_malloc(datalen))) {
1791 mm_free(item->name);
1795 item->datalen = datalen;
1796 memcpy(item->data, data, datalen);
1804 EVDNS_UNLOCK(req->port);
1808 /* exported function */
1810 evdns_server_request_add_a_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl)
1812 return evdns_server_request_add_reply(
1813 req, EVDNS_ANSWER_SECTION, name, TYPE_A, CLASS_INET,
1814 ttl, n*4, 0, addrs);
1817 /* exported function */
1819 evdns_server_request_add_aaaa_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl)
1821 return evdns_server_request_add_reply(
1822 req, EVDNS_ANSWER_SECTION, name, TYPE_AAAA, CLASS_INET,
1823 ttl, n*16, 0, addrs);
1826 /* exported function */
1828 evdns_server_request_add_ptr_reply(struct evdns_server_request *req, struct in_addr *in, const char *inaddr_name, const char *hostname, int ttl)
1832 if (in && inaddr_name)
1834 else if (!in && !inaddr_name)
1837 a = ntohl(in->s_addr);
1838 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa",
1839 (int)(u8)((a )&0xff),
1840 (int)(u8)((a>>8 )&0xff),
1841 (int)(u8)((a>>16)&0xff),
1842 (int)(u8)((a>>24)&0xff));
1845 return evdns_server_request_add_reply(
1846 req, EVDNS_ANSWER_SECTION, inaddr_name, TYPE_PTR, CLASS_INET,
1847 ttl, -1, 1, hostname);
1850 /* exported function */
1852 evdns_server_request_add_cname_reply(struct evdns_server_request *req, const char *name, const char *cname, int ttl)
1854 return evdns_server_request_add_reply(
1855 req, EVDNS_ANSWER_SECTION, name, TYPE_CNAME, CLASS_INET,
1859 /* exported function */
1861 evdns_server_request_set_flags(struct evdns_server_request *exreq, int flags)
1863 struct server_request *req = TO_SERVER_REQUEST(exreq);
1864 req->base.flags &= ~(EVDNS_FLAGS_AA|EVDNS_FLAGS_RD);
1865 req->base.flags |= flags;
1869 evdns_server_request_format_response(struct server_request *req, int err)
1871 unsigned char buf[1500];
1872 size_t buf_len = sizeof(buf);
1878 struct dnslabel_table table;
1880 if (err < 0 || err > 15) return -1;
1882 /* Set response bit and error code; copy OPCODE and RD fields from
1883 * question; copy RA and AA if set by caller. */
1884 flags = req->base.flags;
1885 flags |= (0x8000 | err);
1887 dnslabel_table_init(&table);
1888 APPEND16(req->trans_id);
1890 APPEND16(req->base.nquestions);
1891 APPEND16(req->n_answer);
1892 APPEND16(req->n_authority);
1893 APPEND16(req->n_additional);
1895 /* Add questions. */
1896 for (i=0; i < req->base.nquestions; ++i) {
1897 const char *s = req->base.questions[i]->name;
1898 j = dnsname_to_labels(buf, buf_len, j, s, strlen(s), &table);
1900 dnslabel_clear(&table);
1903 APPEND16(req->base.questions[i]->type);
1904 APPEND16(req->base.questions[i]->dns_question_class);
1907 /* Add answer, authority, and additional sections. */
1908 for (i=0; i<3; ++i) {
1909 struct server_reply_item *item;
1913 item = req->authority;
1915 item = req->additional;
1917 r = dnsname_to_labels(buf, buf_len, j, item->name, strlen(item->name), &table);
1922 APPEND16(item->type);
1923 APPEND16(item->dns_question_class);
1924 APPEND32(item->ttl);
1925 if (item->is_name) {
1926 off_t len_idx = j, name_start;
1929 r = dnsname_to_labels(buf, buf_len, j, item->data, strlen(item->data), &table);
1933 _t = htons( (short) (j-name_start) );
1934 memcpy(buf+len_idx, &_t, 2);
1936 APPEND16(item->datalen);
1937 if (j+item->datalen > (off_t)buf_len)
1939 memcpy(buf+j, item->data, item->datalen);
1949 buf[2] |= 0x02; /* set the truncated bit. */
1952 req->response_len = j;
1954 if (!(req->response = mm_malloc(req->response_len))) {
1955 server_request_free_answers(req);
1956 dnslabel_clear(&table);
1959 memcpy(req->response, buf, req->response_len);
1960 server_request_free_answers(req);
1961 dnslabel_clear(&table);
1965 /* exported function */
1967 evdns_server_request_respond(struct evdns_server_request *_req, int err)
1969 struct server_request *req = TO_SERVER_REQUEST(_req);
1970 struct evdns_server_port *port = req->port;
1974 if (!req->response) {
1975 if ((r = evdns_server_request_format_response(req, err))<0)
1979 r = sendto(port->socket, req->response, (int)req->response_len, 0,
1980 (struct sockaddr*) &req->addr, (ev_socklen_t)req->addrlen);
1982 int sock_err = evutil_socket_geterror(port->socket);
1983 if (EVUTIL_ERR_RW_RETRIABLE(sock_err))
1986 if (port->pending_replies) {
1987 req->prev_pending = port->pending_replies->prev_pending;
1988 req->next_pending = port->pending_replies;
1989 req->prev_pending->next_pending =
1990 req->next_pending->prev_pending = req;
1992 req->prev_pending = req->next_pending = req;
1993 port->pending_replies = req;
1996 (void) event_del(&port->event);
1997 event_assign(&port->event, port->event_base, port->socket, (port->closing?0:EV_READ) | EV_WRITE | EV_PERSIST, server_port_ready_callback, port);
1999 if (event_add(&port->event, NULL) < 0) {
2000 log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server");
2008 if (server_request_free(req)) {
2013 if (port->pending_replies)
2014 server_port_flush(port);
2022 /* Free all storage held by RRs in req. */
2024 server_request_free_answers(struct server_request *req)
2026 struct server_reply_item *victim, *next, **list;
2028 for (i = 0; i < 3; ++i) {
2030 list = &req->answer;
2032 list = &req->authority;
2034 list = &req->additional;
2038 next = victim->next;
2039 mm_free(victim->name);
2041 mm_free(victim->data);
2049 /* Free all storage held by req, and remove links to it. */
2050 /* return true iff we just wound up freeing the server_port. */
2052 server_request_free(struct server_request *req)
2054 int i, rc=1, lock=0;
2055 if (req->base.questions) {
2056 for (i = 0; i < req->base.nquestions; ++i)
2057 mm_free(req->base.questions[i]);
2058 mm_free(req->base.questions);
2062 EVDNS_LOCK(req->port);
2064 if (req->port->pending_replies == req) {
2065 if (req->next_pending && req->next_pending != req)
2066 req->port->pending_replies = req->next_pending;
2068 req->port->pending_replies = NULL;
2070 rc = --req->port->refcnt;
2073 if (req->response) {
2074 mm_free(req->response);
2077 server_request_free_answers(req);
2079 if (req->next_pending && req->next_pending != req) {
2080 req->next_pending->prev_pending = req->prev_pending;
2081 req->prev_pending->next_pending = req->next_pending;
2085 EVDNS_UNLOCK(req->port); /* ????? nickm */
2086 server_port_free(req->port);
2091 EVDNS_UNLOCK(req->port);
2096 /* Free all storage held by an evdns_server_port. Only called when */
2098 server_port_free(struct evdns_server_port *port)
2100 EVUTIL_ASSERT(port);
2101 EVUTIL_ASSERT(!port->refcnt);
2102 EVUTIL_ASSERT(!port->pending_replies);
2103 if (port->socket > 0) {
2104 evutil_closesocket(port->socket);
2107 (void) event_del(&port->event);
2108 event_debug_unassign(&port->event);
2109 EVTHREAD_FREE_LOCK(port->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
2113 /* exported function */
2115 evdns_server_request_drop(struct evdns_server_request *_req)
2117 struct server_request *req = TO_SERVER_REQUEST(_req);
2118 server_request_free(req);
2122 /* exported function */
2124 evdns_server_request_get_requesting_addr(struct evdns_server_request *_req, struct sockaddr *sa, int addr_len)
2126 struct server_request *req = TO_SERVER_REQUEST(_req);
2127 if (addr_len < (int)req->addrlen)
2129 memcpy(sa, &(req->addr), req->addrlen);
2130 return req->addrlen;
2136 /* this is a libevent callback function which is called when a request */
2137 /* has timed out. */
2139 evdns_request_timeout_callback(evutil_socket_t fd, short events, void *arg) {
2140 struct request *const req = (struct request *) arg;
2141 #ifndef _EVENT_DISABLE_THREAD_SUPPORT
2142 struct evdns_base *base = req->base;
2147 log(EVDNS_LOG_DEBUG, "Request %p timed out", arg);
2150 req->ns->timedout++;
2151 if (req->ns->timedout > req->base->global_max_nameserver_timeout) {
2152 req->ns->timedout = 0;
2153 nameserver_failed(req->ns, "request timed out.");
2156 if (req->tx_count >= req->base->global_max_retransmits) {
2157 /* this request has failed */
2158 reply_schedule_callback(req, 0, DNS_ERR_TIMEOUT, NULL);
2159 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1);
2162 (void) evtimer_del(&req->timeout_event);
2163 evdns_request_transmit(req);
2168 /* try to send a request to a given server. */
2172 /* 1 temporary failure */
2173 /* 2 other failure */
2175 evdns_request_transmit_to(struct request *req, struct nameserver *server) {
2177 ASSERT_LOCKED(req->base);
2178 ASSERT_VALID_REQUEST(req);
2179 r = sendto(server->socket, (void*)req->request, req->request_len, 0,
2180 (struct sockaddr *)&server->address, server->addrlen);
2182 int err = evutil_socket_geterror(server->socket);
2183 if (EVUTIL_ERR_RW_RETRIABLE(err))
2185 nameserver_failed(req->ns, evutil_socket_error_to_string(err));
2187 } else if (r != (int)req->request_len) {
2188 return 1; /* short write */
2194 /* try to send a request, updating the fields of the request */
2201 evdns_request_transmit(struct request *req) {
2204 ASSERT_LOCKED(req->base);
2205 ASSERT_VALID_REQUEST(req);
2206 /* if we fail to send this packet then this flag marks it */
2207 /* for evdns_transmit */
2208 req->transmit_me = 1;
2209 EVUTIL_ASSERT(req->trans_id != 0xffff);
2211 if (req->ns->choked) {
2212 /* don't bother trying to write to a socket */
2213 /* which we have had EAGAIN from */
2217 r = evdns_request_transmit_to(req, req->ns);
2221 req->ns->choked = 1;
2222 nameserver_write_waiting(req->ns, 1);
2225 /* failed to transmit the request entirely. */
2227 /* fall through: we'll set a timeout, which will time out,
2228 * and make us retransmit the request anyway. */
2231 log(EVDNS_LOG_DEBUG,
2232 "Setting timeout for request %p", req);
2233 if (evtimer_add(&req->timeout_event, &req->base->global_timeout) < 0) {
2235 "Error from libevent when adding timer for request %p",
2240 req->transmit_me = 0;
2246 nameserver_probe_callback(int result, char type, int count, int ttl, void *addresses, void *arg) {
2247 struct nameserver *const ns = (struct nameserver *) arg;
2253 EVDNS_LOCK(ns->base);
2254 ns->probe_request = NULL;
2255 if (result == DNS_ERR_CANCEL) {
2256 /* We canceled this request because the nameserver came up
2257 * for some other reason. Do not change our opinion about
2258 * the nameserver. */
2259 } else if (result == DNS_ERR_NONE || result == DNS_ERR_NOTEXIST) {
2260 /* this is a good reply */
2263 nameserver_probe_failed(ns);
2265 EVDNS_UNLOCK(ns->base);
2269 nameserver_send_probe(struct nameserver *const ns) {
2270 struct evdns_request *handle;
2271 struct request *req;
2273 /* here we need to send a probe to a given nameserver */
2274 /* in the hope that it is up now. */
2276 ASSERT_LOCKED(ns->base);
2277 log(EVDNS_LOG_DEBUG, "Sending probe to %s",
2278 evutil_format_sockaddr_port(
2279 (struct sockaddr *)&ns->address,
2280 addrbuf, sizeof(addrbuf)));
2281 handle = mm_calloc(1, sizeof(*handle));
2282 if (!handle) return;
2283 req = request_new(ns->base, handle, TYPE_A, "google.com", DNS_QUERY_NO_SEARCH, nameserver_probe_callback, ns);
2285 ns->probe_request = handle;
2286 /* we force this into the inflight queue no matter what */
2287 request_trans_id_set(req, transaction_id_pick(ns->base));
2289 request_submit(req);
2293 /* 0 didn't try to transmit anything */
2294 /* 1 tried to transmit something */
2296 evdns_transmit(struct evdns_base *base) {
2297 char did_try_to_transmit = 0;
2300 ASSERT_LOCKED(base);
2301 for (i = 0; i < base->n_req_heads; ++i) {
2302 if (base->req_heads[i]) {
2303 struct request *const started_at = base->req_heads[i], *req = started_at;
2304 /* first transmit all the requests which are currently waiting */
2306 if (req->transmit_me) {
2307 did_try_to_transmit = 1;
2308 evdns_request_transmit(req);
2312 } while (req != started_at);
2316 return did_try_to_transmit;
2319 /* exported function */
2321 evdns_base_count_nameservers(struct evdns_base *base)
2323 const struct nameserver *server;
2327 server = base->server_head;
2332 server = server->next;
2333 } while (server != base->server_head);
2340 evdns_count_nameservers(void)
2342 return evdns_base_count_nameservers(current_base);
2345 /* exported function */
2347 evdns_base_clear_nameservers_and_suspend(struct evdns_base *base)
2349 struct nameserver *server, *started_at;
2353 server = base->server_head;
2354 started_at = base->server_head;
2360 struct nameserver *next = server->next;
2361 (void) event_del(&server->event);
2362 if (evtimer_initialized(&server->timeout_event))
2363 (void) evtimer_del(&server->timeout_event);
2364 if (server->socket >= 0)
2365 evutil_closesocket(server->socket);
2367 if (next == started_at)
2371 base->server_head = NULL;
2372 base->global_good_nameservers = 0;
2374 for (i = 0; i < base->n_req_heads; ++i) {
2375 struct request *req, *req_started_at;
2376 req = req_started_at = base->req_heads[i];
2378 struct request *next = req->next;
2379 req->tx_count = req->reissue_count = 0;
2381 /* ???? What to do about searches? */
2382 (void) evtimer_del(&req->timeout_event);
2384 req->transmit_me = 0;
2386 base->global_requests_waiting++;
2387 evdns_request_insert(req, &base->req_waiting_head);
2388 /* We want to insert these suspended elements at the front of
2389 * the waiting queue, since they were pending before any of
2390 * the waiting entries were added. This is a circular list,
2391 * so we can just shift the start back by one.*/
2392 base->req_waiting_head = base->req_waiting_head->prev;
2394 if (next == req_started_at)
2398 base->req_heads[i] = NULL;
2401 base->global_requests_inflight = 0;
2408 evdns_clear_nameservers_and_suspend(void)
2410 return evdns_base_clear_nameservers_and_suspend(current_base);
2414 /* exported function */
2416 evdns_base_resume(struct evdns_base *base)
2419 evdns_requests_pump_waiting_queue(base);
2427 return evdns_base_resume(current_base);
2431 _evdns_nameserver_add_impl(struct evdns_base *base, const struct sockaddr *address, int addrlen) {
2432 /* first check to see if we already have this nameserver */
2434 const struct nameserver *server = base->server_head, *const started_at = base->server_head;
2435 struct nameserver *ns;
2439 ASSERT_LOCKED(base);
2442 if (!evutil_sockaddr_cmp((struct sockaddr*)&server->address, address, 1)) return 3;
2443 server = server->next;
2444 } while (server != started_at);
2446 if (addrlen > (int)sizeof(ns->address)) {
2447 log(EVDNS_LOG_DEBUG, "Addrlen %d too long.", (int)addrlen);
2451 ns = (struct nameserver *) mm_malloc(sizeof(struct nameserver));
2454 memset(ns, 0, sizeof(struct nameserver));
2457 evtimer_assign(&ns->timeout_event, ns->base->event_base, nameserver_prod_callback, ns);
2459 ns->socket = socket(address->sa_family, SOCK_DGRAM, 0);
2460 if (ns->socket < 0) { err = 1; goto out1; }
2461 evutil_make_socket_closeonexec(ns->socket);
2462 evutil_make_socket_nonblocking(ns->socket);
2464 if (base->global_outgoing_addrlen &&
2465 !evutil_sockaddr_is_loopback(address)) {
2466 if (bind(ns->socket,
2467 (struct sockaddr*)&base->global_outgoing_address,
2468 base->global_outgoing_addrlen) < 0) {
2469 log(EVDNS_LOG_WARN,"Couldn't bind to outgoing address");
2475 memcpy(&ns->address, address, addrlen);
2476 ns->addrlen = addrlen;
2478 event_assign(&ns->event, ns->base->event_base, ns->socket, EV_READ | EV_PERSIST, nameserver_ready_callback, ns);
2479 if (event_add(&ns->event, NULL) < 0) {
2484 log(EVDNS_LOG_DEBUG, "Added nameserver %s",
2485 evutil_format_sockaddr_port(address, addrbuf, sizeof(addrbuf)));
2487 /* insert this nameserver into the list of them */
2488 if (!base->server_head) {
2489 ns->next = ns->prev = ns;
2490 base->server_head = ns;
2492 ns->next = base->server_head->next;
2493 ns->prev = base->server_head;
2494 base->server_head->next = ns;
2495 ns->next->prev = ns;
2498 base->global_good_nameservers++;
2503 evutil_closesocket(ns->socket);
2505 event_debug_unassign(&ns->event);
2507 log(EVDNS_LOG_WARN, "Unable to add nameserver %s: error %d",
2508 evutil_format_sockaddr_port(address, addrbuf, sizeof(addrbuf)), err);
2512 /* exported function */
2514 evdns_base_nameserver_add(struct evdns_base *base, unsigned long int address)
2516 struct sockaddr_in sin;
2518 sin.sin_addr.s_addr = address;
2519 sin.sin_port = htons(53);
2520 sin.sin_family = AF_INET;
2522 res = _evdns_nameserver_add_impl(base, (struct sockaddr*)&sin, sizeof(sin));
2528 evdns_nameserver_add(unsigned long int address) {
2530 current_base = evdns_base_new(NULL, 0);
2531 return evdns_base_nameserver_add(current_base, address);
2535 sockaddr_setport(struct sockaddr *sa, ev_uint16_t port)
2537 if (sa->sa_family == AF_INET) {
2538 ((struct sockaddr_in *)sa)->sin_port = htons(port);
2539 } else if (sa->sa_family == AF_INET6) {
2540 ((struct sockaddr_in6 *)sa)->sin6_port = htons(port);
2545 sockaddr_getport(struct sockaddr *sa)
2547 if (sa->sa_family == AF_INET) {
2548 return ntohs(((struct sockaddr_in *)sa)->sin_port);
2549 } else if (sa->sa_family == AF_INET6) {
2550 return ntohs(((struct sockaddr_in6 *)sa)->sin6_port);
2556 /* exported function */
2558 evdns_base_nameserver_ip_add(struct evdns_base *base, const char *ip_as_string) {
2559 struct sockaddr_storage ss;
2560 struct sockaddr *sa;
2561 int len = sizeof(ss);
2563 if (evutil_parse_sockaddr_port(ip_as_string, (struct sockaddr *)&ss,
2565 log(EVDNS_LOG_WARN, "Unable to parse nameserver address %s",
2569 sa = (struct sockaddr *) &ss;
2570 if (sockaddr_getport(sa) == 0)
2571 sockaddr_setport(sa, 53);
2574 res = _evdns_nameserver_add_impl(base, sa, len);
2580 evdns_nameserver_ip_add(const char *ip_as_string) {
2582 current_base = evdns_base_new(NULL, 0);
2583 return evdns_base_nameserver_ip_add(current_base, ip_as_string);
2587 evdns_base_nameserver_sockaddr_add(struct evdns_base *base,
2588 const struct sockaddr *sa, ev_socklen_t len, unsigned flags)
2591 EVUTIL_ASSERT(base);
2593 res = _evdns_nameserver_add_impl(base, sa, len);
2598 /* remove from the queue */
2600 evdns_request_remove(struct request *req, struct request **head)
2602 ASSERT_LOCKED(req->base);
2603 ASSERT_VALID_REQUEST(req);
2607 struct request *ptr;
2609 EVUTIL_ASSERT(*head != NULL);
2618 } while (ptr != *head);
2619 EVUTIL_ASSERT(found);
2621 EVUTIL_ASSERT(req->next);
2625 if (req->next == req) {
2626 /* only item in the list */
2629 req->next->prev = req->prev;
2630 req->prev->next = req->next;
2631 if (*head == req) *head = req->next;
2633 req->next = req->prev = NULL;
2636 /* insert into the tail of the queue */
2638 evdns_request_insert(struct request *req, struct request **head) {
2639 ASSERT_LOCKED(req->base);
2640 ASSERT_VALID_REQUEST(req);
2643 req->next = req->prev = req;
2647 req->prev = (*head)->prev;
2648 req->prev->next = req;
2650 (*head)->prev = req;
2654 string_num_dots(const char *s) {
2656 while ((s = strchr(s, '.'))) {
2663 static struct request *
2664 request_new(struct evdns_base *base, struct evdns_request *handle, int type,
2665 const char *name, int flags, evdns_callback_type callback,
2668 const char issuing_now =
2669 (base->global_requests_inflight < base->global_max_requests_inflight) ? 1 : 0;
2671 const size_t name_len = strlen(name);
2672 const size_t request_max_len = evdns_request_len(name_len);
2673 const u16 trans_id = issuing_now ? transaction_id_pick(base) : 0xffff;
2674 /* the request data is alloced in a single block with the header */
2675 struct request *const req =
2676 mm_malloc(sizeof(struct request) + request_max_len);
2681 ASSERT_LOCKED(base);
2683 if (!req) return NULL;
2685 if (name_len >= sizeof(namebuf)) {
2690 memset(req, 0, sizeof(struct request));
2693 evtimer_assign(&req->timeout_event, req->base->event_base, evdns_request_timeout_callback, req);
2695 if (base->global_randomize_case) {
2697 char randbits[(sizeof(namebuf)+7)/8];
2698 strlcpy(namebuf, name, sizeof(namebuf));
2699 evutil_secure_rng_get_bytes(randbits, (name_len+7)/8);
2700 for (i = 0; i < name_len; ++i) {
2701 if (EVUTIL_ISALPHA(namebuf[i])) {
2702 if ((randbits[i >> 3] & (1<<(i & 7))))
2705 namebuf[i] &= ~0x20;
2711 /* request data lives just after the header */
2712 req->request = ((u8 *) req) + sizeof(struct request);
2713 /* denotes that the request data shouldn't be free()ed */
2714 req->request_appended = 1;
2715 rlen = evdns_request_data_build(name, name_len, trans_id,
2716 type, CLASS_INET, req->request, request_max_len);
2720 req->request_len = rlen;
2721 req->trans_id = trans_id;
2723 req->request_type = type;
2724 req->user_pointer = user_ptr;
2725 req->user_callback = callback;
2726 req->ns = issuing_now ? nameserver_pick(base) : NULL;
2727 req->next = req->prev = NULL;
2728 req->handle = handle;
2730 handle->current_req = req;
2731 handle->base = base;
2741 request_submit(struct request *const req) {
2742 struct evdns_base *base = req->base;
2743 ASSERT_LOCKED(base);
2744 ASSERT_VALID_REQUEST(req);
2746 /* if it has a nameserver assigned then this is going */
2747 /* straight into the inflight queue */
2748 evdns_request_insert(req, &REQ_HEAD(base, req->trans_id));
2749 base->global_requests_inflight++;
2750 evdns_request_transmit(req);
2752 evdns_request_insert(req, &base->req_waiting_head);
2753 base->global_requests_waiting++;
2757 /* exported function */
2759 evdns_cancel_request(struct evdns_base *base, struct evdns_request *handle)
2761 struct request *req;
2763 if (!handle->current_req)
2767 /* This redundancy is silly; can we fix it? (Not for 2.0) XXXX */
2768 base = handle->base;
2770 base = handle->current_req->base;
2774 if (handle->pending_cb) {
2779 req = handle->current_req;
2780 ASSERT_VALID_REQUEST(req);
2782 reply_schedule_callback(req, 0, DNS_ERR_CANCEL, NULL);
2784 /* remove from inflight queue */
2785 request_finished(req, &REQ_HEAD(base, req->trans_id), 1);
2787 /* remove from global_waiting head */
2788 request_finished(req, &base->req_waiting_head, 1);
2793 /* exported function */
2794 struct evdns_request *
2795 evdns_base_resolve_ipv4(struct evdns_base *base, const char *name, int flags,
2796 evdns_callback_type callback, void *ptr) {
2797 struct evdns_request *handle;
2798 struct request *req;
2799 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name);
2800 handle = mm_calloc(1, sizeof(*handle));
2804 if (flags & DNS_QUERY_NO_SEARCH) {
2806 request_new(base, handle, TYPE_A, name, flags,
2809 request_submit(req);
2811 search_request_new(base, handle, TYPE_A, name, flags,
2814 if (handle->current_req == NULL) {
2822 int evdns_resolve_ipv4(const char *name, int flags,
2823 evdns_callback_type callback, void *ptr)
2825 return evdns_base_resolve_ipv4(current_base, name, flags, callback, ptr)
2830 /* exported function */
2831 struct evdns_request *
2832 evdns_base_resolve_ipv6(struct evdns_base *base,
2833 const char *name, int flags,
2834 evdns_callback_type callback, void *ptr)
2836 struct evdns_request *handle;
2837 struct request *req;
2838 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name);
2839 handle = mm_calloc(1, sizeof(*handle));
2843 if (flags & DNS_QUERY_NO_SEARCH) {
2844 req = request_new(base, handle, TYPE_AAAA, name, flags,
2847 request_submit(req);
2849 search_request_new(base, handle, TYPE_AAAA, name, flags,
2852 if (handle->current_req == NULL) {
2860 int evdns_resolve_ipv6(const char *name, int flags,
2861 evdns_callback_type callback, void *ptr) {
2862 return evdns_base_resolve_ipv6(current_base, name, flags, callback, ptr)
2866 struct evdns_request *
2867 evdns_base_resolve_reverse(struct evdns_base *base, const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) {
2869 struct evdns_request *handle;
2870 struct request *req;
2873 a = ntohl(in->s_addr);
2874 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa",
2875 (int)(u8)((a )&0xff),
2876 (int)(u8)((a>>8 )&0xff),
2877 (int)(u8)((a>>16)&0xff),
2878 (int)(u8)((a>>24)&0xff));
2879 handle = mm_calloc(1, sizeof(*handle));
2882 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf);
2884 req = request_new(base, handle, TYPE_PTR, buf, flags, callback, ptr);
2886 request_submit(req);
2887 if (handle->current_req == NULL) {
2895 int evdns_resolve_reverse(const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) {
2896 return evdns_base_resolve_reverse(current_base, in, flags, callback, ptr)
2900 struct evdns_request *
2901 evdns_base_resolve_reverse_ipv6(struct evdns_base *base, const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) {
2902 /* 32 nybbles, 32 periods, "ip6.arpa", NUL. */
2905 struct evdns_request *handle;
2906 struct request *req;
2910 for (i=15; i >= 0; --i) {
2911 u8 byte = in->s6_addr[i];
2912 *cp++ = "0123456789abcdef"[byte & 0x0f];
2914 *cp++ = "0123456789abcdef"[byte >> 4];
2917 EVUTIL_ASSERT(cp + strlen("ip6.arpa") < buf+sizeof(buf));
2918 memcpy(cp, "ip6.arpa", strlen("ip6.arpa")+1);
2919 handle = mm_calloc(1, sizeof(*handle));
2922 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf);
2924 req = request_new(base, handle, TYPE_PTR, buf, flags, callback, ptr);
2926 request_submit(req);
2927 if (handle->current_req == NULL) {
2935 int evdns_resolve_reverse_ipv6(const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) {
2936 return evdns_base_resolve_reverse_ipv6(current_base, in, flags, callback, ptr)
2940 /* ================================================================= */
2941 /* Search support */
2943 /* the libc resolver has support for searching a number of domains */
2944 /* to find a name. If nothing else then it takes the single domain */
2945 /* from the gethostname() call. */
2947 /* It can also be configured via the domain and search options in a */
2950 /* The ndots option controls how many dots it takes for the resolver */
2951 /* to decide that a name is non-local and so try a raw lookup first. */
2953 struct search_domain {
2955 struct search_domain *next;
2956 /* the text string is appended to this structure */
2959 struct search_state {
2963 struct search_domain *head;
2967 search_state_decref(struct search_state *const state) {
2970 if (!state->refcount) {
2971 struct search_domain *next, *dom;
2972 for (dom = state->head; dom; dom = next) {
2980 static struct search_state *
2981 search_state_new(void) {
2982 struct search_state *state = (struct search_state *) mm_malloc(sizeof(struct search_state));
2983 if (!state) return NULL;
2984 memset(state, 0, sizeof(struct search_state));
2985 state->refcount = 1;
2992 search_postfix_clear(struct evdns_base *base) {
2993 search_state_decref(base->global_search_state);
2995 base->global_search_state = search_state_new();
2998 /* exported function */
3000 evdns_base_search_clear(struct evdns_base *base)
3003 search_postfix_clear(base);
3008 evdns_search_clear(void) {
3009 evdns_base_search_clear(current_base);
3013 search_postfix_add(struct evdns_base *base, const char *domain) {
3015 struct search_domain *sdomain;
3016 while (domain[0] == '.') domain++;
3017 domain_len = strlen(domain);
3019 ASSERT_LOCKED(base);
3020 if (!base->global_search_state) base->global_search_state = search_state_new();
3021 if (!base->global_search_state) return;
3022 base->global_search_state->num_domains++;
3024 sdomain = (struct search_domain *) mm_malloc(sizeof(struct search_domain) + domain_len);
3025 if (!sdomain) return;
3026 memcpy( ((u8 *) sdomain) + sizeof(struct search_domain), domain, domain_len);
3027 sdomain->next = base->global_search_state->head;
3028 sdomain->len = (int) domain_len;
3030 base->global_search_state->head = sdomain;
3033 /* reverse the order of members in the postfix list. This is needed because, */
3034 /* when parsing resolv.conf we push elements in the wrong order */
3036 search_reverse(struct evdns_base *base) {
3037 struct search_domain *cur, *prev = NULL, *next;
3038 ASSERT_LOCKED(base);
3039 cur = base->global_search_state->head;
3047 base->global_search_state->head = prev;
3050 /* exported function */
3052 evdns_base_search_add(struct evdns_base *base, const char *domain) {
3054 search_postfix_add(base, domain);
3058 evdns_search_add(const char *domain) {
3059 evdns_base_search_add(current_base, domain);
3062 /* exported function */
3064 evdns_base_search_ndots_set(struct evdns_base *base, const int ndots) {
3066 if (!base->global_search_state) base->global_search_state = search_state_new();
3067 if (base->global_search_state)
3068 base->global_search_state->ndots = ndots;
3072 evdns_search_ndots_set(const int ndots) {
3073 evdns_base_search_ndots_set(current_base, ndots);
3077 search_set_from_hostname(struct evdns_base *base) {
3078 char hostname[HOST_NAME_MAX + 1], *domainname;
3080 ASSERT_LOCKED(base);
3081 search_postfix_clear(base);
3082 if (gethostname(hostname, sizeof(hostname))) return;
3083 domainname = strchr(hostname, '.');
3084 if (!domainname) return;
3085 search_postfix_add(base, domainname);
3088 /* warning: returns malloced string */
3090 search_make_new(const struct search_state *const state, int n, const char *const base_name) {
3091 const size_t base_len = strlen(base_name);
3092 const char need_to_append_dot = base_name[base_len - 1] == '.' ? 0 : 1;
3093 struct search_domain *dom;
3095 for (dom = state->head; dom; dom = dom->next) {
3097 /* this is the postfix we want */
3098 /* the actual postfix string is kept at the end of the structure */
3099 const u8 *const postfix = ((u8 *) dom) + sizeof(struct search_domain);
3100 const int postfix_len = dom->len;
3101 char *const newname = (char *) mm_malloc(base_len + need_to_append_dot + postfix_len + 1);
3102 if (!newname) return NULL;
3103 memcpy(newname, base_name, base_len);
3104 if (need_to_append_dot) newname[base_len] = '.';
3105 memcpy(newname + base_len + need_to_append_dot, postfix, postfix_len);
3106 newname[base_len + need_to_append_dot + postfix_len] = 0;
3111 /* we ran off the end of the list and still didn't find the requested string */
3113 return NULL; /* unreachable; stops warnings in some compilers. */
3116 static struct request *
3117 search_request_new(struct evdns_base *base, struct evdns_request *handle,
3118 int type, const char *const name, int flags,
3119 evdns_callback_type user_callback, void *user_arg) {
3120 ASSERT_LOCKED(base);
3121 EVUTIL_ASSERT(type == TYPE_A || type == TYPE_AAAA);
3122 EVUTIL_ASSERT(handle->current_req == NULL);
3123 if ( ((flags & DNS_QUERY_NO_SEARCH) == 0) &&
3124 base->global_search_state &&
3125 base->global_search_state->num_domains) {
3126 /* we have some domains to search */
3127 struct request *req;
3128 if (string_num_dots(name) >= base->global_search_state->ndots) {
3129 req = request_new(base, handle, type, name, flags, user_callback, user_arg);
3130 if (!req) return NULL;
3131 handle->search_index = -1;
3133 char *const new_name = search_make_new(base->global_search_state, 0, name);
3134 if (!new_name) return NULL;
3135 req = request_new(base, handle, type, new_name, flags, user_callback, user_arg);
3137 if (!req) return NULL;
3138 handle->search_index = 0;
3140 EVUTIL_ASSERT(handle->search_origname == NULL);
3141 handle->search_origname = mm_strdup(name);
3142 if (handle->search_origname == NULL) {
3143 /* XXX Should we dealloc req? If yes, how? */
3146 handle->search_state = base->global_search_state;
3147 handle->search_flags = flags;
3148 base->global_search_state->refcount++;
3149 request_submit(req);
3152 struct request *const req = request_new(base, handle, type, name, flags, user_callback, user_arg);
3153 if (!req) return NULL;
3154 request_submit(req);
3159 /* this is called when a request has failed to find a name. We need to check */
3160 /* if it is part of a search and, if so, try the next name in the list */
3162 /* 0 another request has been submitted */
3163 /* 1 no more requests needed */
3165 search_try_next(struct evdns_request *const handle) {
3166 struct request *req = handle->current_req;
3167 struct evdns_base *base = req->base;
3168 struct request *newreq;
3169 ASSERT_LOCKED(base);
3170 if (handle->search_state) {
3171 /* it is part of a search */
3173 handle->search_index++;
3174 if (handle->search_index >= handle->search_state->num_domains) {
3175 /* no more postfixes to try, however we may need to try */
3176 /* this name without a postfix */
3177 if (string_num_dots(handle->search_origname) < handle->search_state->ndots) {
3178 /* yep, we need to try it raw */
3179 newreq = request_new(base, NULL, req->request_type, handle->search_origname, handle->search_flags, req->user_callback, req->user_pointer);
3180 log(EVDNS_LOG_DEBUG, "Search: trying raw query %s", handle->search_origname);
3182 search_request_finished(handle);
3189 new_name = search_make_new(handle->search_state, handle->search_index, handle->search_origname);
3190 if (!new_name) return 1;
3191 log(EVDNS_LOG_DEBUG, "Search: now trying %s (%d)", new_name, handle->search_index);
3192 newreq = request_new(base, NULL, req->request_type, new_name, handle->search_flags, req->user_callback, req->user_pointer);
3194 if (!newreq) return 1;
3200 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 0);
3201 handle->current_req = newreq;
3202 newreq->handle = handle;
3203 request_submit(newreq);
3208 search_request_finished(struct evdns_request *const handle) {
3209 ASSERT_LOCKED(handle->current_req->base);
3210 if (handle->search_state) {
3211 search_state_decref(handle->search_state);
3212 handle->search_state = NULL;
3214 if (handle->search_origname) {
3215 mm_free(handle->search_origname);
3216 handle->search_origname = NULL;
3220 /* ================================================================= */
3221 /* Parsing resolv.conf files */
3224 evdns_resolv_set_defaults(struct evdns_base *base, int flags) {
3225 /* if the file isn't found then we assume a local resolver */
3226 ASSERT_LOCKED(base);
3227 if (flags & DNS_OPTION_SEARCH) search_set_from_hostname(base);
3228 if (flags & DNS_OPTION_NAMESERVERS) evdns_base_nameserver_ip_add(base,"127.0.0.1");
3231 #ifndef _EVENT_HAVE_STRTOK_R
3233 strtok_r(char *s, const char *delim, char **state) {
3235 start = cp = s ? s : *state;
3238 while (*cp && !strchr(delim, *cp))
3253 /* helper version of atoi which returns -1 on error */
3255 strtoint(const char *const str)
3258 const int r = strtol(str, &endptr, 10);
3259 if (*endptr) return -1;
3263 /* Parse a number of seconds into a timeval; return -1 on error. */
3265 strtotimeval(const char *const str, struct timeval *out)
3269 d = strtod(str, &endptr);
3270 if (*endptr) return -1;
3271 if (d < 0) return -1;
3272 out->tv_sec = (int) d;
3273 out->tv_usec = (int) ((d - (int) d)*1000000);
3274 if (out->tv_sec == 0 && out->tv_usec < 1000) /* less than 1 msec */
3279 /* helper version of atoi that returns -1 on error and clips to bounds. */
3281 strtoint_clipped(const char *const str, int min, int max)
3283 int r = strtoint(str);
3295 evdns_base_set_max_requests_inflight(struct evdns_base *base, int maxinflight)
3297 int old_n_heads = base->n_req_heads, n_heads;
3298 struct request **old_heads = base->req_heads, **new_heads, *req;
3301 ASSERT_LOCKED(base);
3302 if (maxinflight < 1)
3304 n_heads = (maxinflight+4) / 5;
3305 EVUTIL_ASSERT(n_heads > 0);
3306 new_heads = mm_calloc(n_heads, sizeof(struct request*));
3310 for (i = 0; i < old_n_heads; ++i) {
3311 while (old_heads[i]) {
3313 evdns_request_remove(req, &old_heads[i]);
3314 evdns_request_insert(req, &new_heads[req->trans_id % n_heads]);
3319 base->req_heads = new_heads;
3320 base->n_req_heads = n_heads;
3321 base->global_max_requests_inflight = maxinflight;
3325 /* exported function */
3327 evdns_base_set_option(struct evdns_base *base,
3328 const char *option, const char *val)
3332 res = evdns_base_set_option_impl(base, option, val, DNS_OPTIONS_ALL);
3338 str_matches_option(const char *s1, const char *optionname)
3340 /* Option names are given as "option:" We accept either 'option' in
3341 * s1, or 'option:randomjunk'. The latter form is to implement the
3342 * resolv.conf parser. */
3343 size_t optlen = strlen(optionname);
3344 size_t slen = strlen(s1);
3345 if (slen == optlen || slen == optlen - 1)
3346 return !strncmp(s1, optionname, slen);
3347 else if (slen > optlen)
3348 return !strncmp(s1, optionname, optlen);
3354 evdns_base_set_option_impl(struct evdns_base *base,
3355 const char *option, const char *val, int flags)
3357 ASSERT_LOCKED(base);
3358 if (str_matches_option(option, "ndots:")) {
3359 const int ndots = strtoint(val);
3360 if (ndots == -1) return -1;
3361 if (!(flags & DNS_OPTION_SEARCH)) return 0;
3362 log(EVDNS_LOG_DEBUG, "Setting ndots to %d", ndots);
3363 if (!base->global_search_state) base->global_search_state = search_state_new();
3364 if (!base->global_search_state) return -1;
3365 base->global_search_state->ndots = ndots;
3366 } else if (str_matches_option(option, "timeout:")) {
3368 if (strtotimeval(val, &tv) == -1) return -1;
3369 if (!(flags & DNS_OPTION_MISC)) return 0;
3370 log(EVDNS_LOG_DEBUG, "Setting timeout to %s", val);
3371 memcpy(&base->global_timeout, &tv, sizeof(struct timeval));
3372 } else if (str_matches_option(option, "getaddrinfo-allow-skew:")) {
3374 if (strtotimeval(val, &tv) == -1) return -1;
3375 if (!(flags & DNS_OPTION_MISC)) return 0;
3376 log(EVDNS_LOG_DEBUG, "Setting getaddrinfo-allow-skew to %s",
3378 memcpy(&base->global_getaddrinfo_allow_skew, &tv,
3379 sizeof(struct timeval));
3380 } else if (str_matches_option(option, "max-timeouts:")) {
3381 const int maxtimeout = strtoint_clipped(val, 1, 255);
3382 if (maxtimeout == -1) return -1;
3383 if (!(flags & DNS_OPTION_MISC)) return 0;
3384 log(EVDNS_LOG_DEBUG, "Setting maximum allowed timeouts to %d",
3386 base->global_max_nameserver_timeout = maxtimeout;
3387 } else if (str_matches_option(option, "max-inflight:")) {
3388 const int maxinflight = strtoint_clipped(val, 1, 65000);
3389 if (maxinflight == -1) return -1;
3390 if (!(flags & DNS_OPTION_MISC)) return 0;
3391 log(EVDNS_LOG_DEBUG, "Setting maximum inflight requests to %d",
3393 evdns_base_set_max_requests_inflight(base, maxinflight);
3394 } else if (str_matches_option(option, "attempts:")) {
3395 int retries = strtoint(val);
3396 if (retries == -1) return -1;
3397 if (retries > 255) retries = 255;
3398 if (!(flags & DNS_OPTION_MISC)) return 0;
3399 log(EVDNS_LOG_DEBUG, "Setting retries to %d", retries);
3400 base->global_max_retransmits = retries;
3401 } else if (str_matches_option(option, "randomize-case:")) {
3402 int randcase = strtoint(val);
3403 if (!(flags & DNS_OPTION_MISC)) return 0;
3404 base->global_randomize_case = randcase;
3405 } else if (str_matches_option(option, "bind-to:")) {
3406 /* XXX This only applies to successive nameservers, not
3407 * to already-configured ones. We might want to fix that. */
3408 int len = sizeof(base->global_outgoing_address);
3409 if (!(flags & DNS_OPTION_NAMESERVERS)) return 0;
3410 if (evutil_parse_sockaddr_port(val,
3411 (struct sockaddr*)&base->global_outgoing_address, &len))
3413 base->global_outgoing_addrlen = len;
3414 } else if (str_matches_option(option, "initial-probe-timeout:")) {
3416 if (strtotimeval(val, &tv) == -1) return -1;
3417 if (tv.tv_sec > 3600)
3419 if (!(flags & DNS_OPTION_MISC)) return 0;
3420 log(EVDNS_LOG_DEBUG, "Setting initial probe timeout to %s",
3422 memcpy(&base->global_nameserver_probe_initial_timeout, &tv,
3429 evdns_set_option(const char *option, const char *val, int flags)
3432 current_base = evdns_base_new(NULL, 0);
3433 return evdns_base_set_option(current_base, option, val);
3437 resolv_conf_parse_line(struct evdns_base *base, char *const start, int flags) {
3439 static const char *const delims = " \t";
3440 #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state)
3443 char *const first_token = strtok_r(start, delims, &strtok_state);
3444 ASSERT_LOCKED(base);
3445 if (!first_token) return;
3447 if (!strcmp(first_token, "nameserver") && (flags & DNS_OPTION_NAMESERVERS)) {
3448 const char *const nameserver = NEXT_TOKEN;
3451 evdns_base_nameserver_ip_add(base, nameserver);
3452 } else if (!strcmp(first_token, "domain") && (flags & DNS_OPTION_SEARCH)) {
3453 const char *const domain = NEXT_TOKEN;
3455 search_postfix_clear(base);
3456 search_postfix_add(base, domain);
3458 } else if (!strcmp(first_token, "search") && (flags & DNS_OPTION_SEARCH)) {
3460 search_postfix_clear(base);
3462 while ((domain = NEXT_TOKEN)) {
3463 search_postfix_add(base, domain);
3465 search_reverse(base);
3466 } else if (!strcmp(first_token, "options")) {
3468 while ((option = NEXT_TOKEN)) {
3469 const char *val = strchr(option, ':');
3470 evdns_base_set_option_impl(base, option, val ? val+1 : "", flags);
3476 /* exported function */
3479 /* 1 failed to open file */
3480 /* 2 failed to stat file */
3481 /* 3 file too large */
3482 /* 4 out of memory */
3483 /* 5 short read from file */
3485 evdns_base_resolv_conf_parse(struct evdns_base *base, int flags, const char *const filename) {
3488 res = evdns_base_resolv_conf_parse_impl(base, flags, filename);
3494 evdns_get_default_hosts_filename(void)
3497 /* Windows is a little coy about where it puts its configuration
3498 * files. Sure, they're _usually_ in C:\windows\system32, but
3499 * there's no reason in principle they couldn't be in
3500 * W:\hoboken chicken emergency\
3502 char path[MAX_PATH+1];
3503 static const char hostfile[] = "\\drivers\\etc\\hosts";
3507 if (! SHGetSpecialFolderPathA(NULL, path, CSIDL_SYSTEM, 0))
3509 len_out = strlen(path)+strlen(hostfile);
3510 path_out = mm_malloc(len_out+1);
3511 evutil_snprintf(path_out, len_out, "%s%s", path, hostfile);
3514 return mm_strdup("/etc/hosts");
3519 evdns_base_resolv_conf_parse_impl(struct evdns_base *base, int flags, const char *const filename) {
3525 log(EVDNS_LOG_DEBUG, "Parsing resolv.conf file %s", filename);
3527 if (flags & DNS_OPTION_HOSTSFILE) {
3528 char *fname = evdns_get_default_hosts_filename();
3529 evdns_base_load_hosts(base, fname);
3534 if ((err = evutil_read_file(filename, &resolv, &n, 0)) < 0) {
3537 evdns_resolv_set_defaults(base, flags);
3546 char *const newline = strchr(start, '\n');
3548 resolv_conf_parse_line(base, start, flags);
3552 resolv_conf_parse_line(base, start, flags);
3553 start = newline + 1;
3557 if (!base->server_head && (flags & DNS_OPTION_NAMESERVERS)) {
3558 /* no nameservers were configured. */
3559 evdns_base_nameserver_ip_add(base, "127.0.0.1");
3562 if (flags & DNS_OPTION_SEARCH && (!base->global_search_state || base->global_search_state->num_domains == 0)) {
3563 search_set_from_hostname(base);
3571 evdns_resolv_conf_parse(int flags, const char *const filename) {
3573 current_base = evdns_base_new(NULL, 0);
3574 return evdns_base_resolv_conf_parse(current_base, flags, filename);
3579 /* Add multiple nameservers from a space-or-comma-separated list. */
3581 evdns_nameserver_ip_add_line(struct evdns_base *base, const char *ips) {
3585 ASSERT_LOCKED(base);
3587 while (isspace(*ips) || *ips == ',' || *ips == '\t')
3590 while (isdigit(*ips) || *ips == '.' || *ips == ':' ||
3591 *ips=='[' || *ips==']')
3593 buf = mm_malloc(ips-addr+1);
3595 memcpy(buf, addr, ips-addr);
3596 buf[ips-addr] = '\0';
3597 r = evdns_base_nameserver_ip_add(base, buf);
3604 typedef DWORD(WINAPI *GetNetworkParams_fn_t)(FIXED_INFO *, DWORD*);
3606 /* Use the windows GetNetworkParams interface in iphlpapi.dll to */
3607 /* figure out what our nameservers are. */
3609 load_nameservers_with_getnetworkparams(struct evdns_base *base)
3611 /* Based on MSDN examples and inspection of c-ares code. */
3614 ULONG size = sizeof(FIXED_INFO);
3616 int status = 0, r, added_any;
3618 GetNetworkParams_fn_t fn;
3620 ASSERT_LOCKED(base);
3621 if (!(handle = evutil_load_windows_system_library(
3622 TEXT("iphlpapi.dll")))) {
3623 log(EVDNS_LOG_WARN, "Could not open iphlpapi.dll");
3627 if (!(fn = (GetNetworkParams_fn_t) GetProcAddress(handle, "GetNetworkParams"))) {
3628 log(EVDNS_LOG_WARN, "Could not get address of function.");
3633 buf = mm_malloc(size);
3634 if (!buf) { status = 4; goto done; }
3636 r = fn(fixed, &size);
3637 if (r != ERROR_SUCCESS && r != ERROR_BUFFER_OVERFLOW) {
3641 if (r != ERROR_SUCCESS) {
3643 buf = mm_malloc(size);
3644 if (!buf) { status = 4; goto done; }
3646 r = fn(fixed, &size);
3647 if (r != ERROR_SUCCESS) {
3648 log(EVDNS_LOG_DEBUG, "fn() failed.");
3654 EVUTIL_ASSERT(fixed);
3656 ns = &(fixed->DnsServerList);
3658 r = evdns_nameserver_ip_add_line(base, ns->IpAddress.String);
3660 log(EVDNS_LOG_DEBUG,"Could not add nameserver %s to list,error: %d",
3661 (ns->IpAddress.String),(int)GetLastError());
3665 log(EVDNS_LOG_DEBUG,"Successfully added %s as nameserver",ns->IpAddress.String);
3672 log(EVDNS_LOG_DEBUG, "No nameservers added.");
3683 FreeLibrary(handle);
3688 config_nameserver_from_reg_key(struct evdns_base *base, HKEY key, const TCHAR *subkey)
3691 DWORD bufsz = 0, type = 0;
3694 ASSERT_LOCKED(base);
3695 if (RegQueryValueEx(key, subkey, 0, &type, NULL, &bufsz)
3698 if (!(buf = mm_malloc(bufsz)))
3701 if (RegQueryValueEx(key, subkey, 0, &type, (LPBYTE)buf, &bufsz)
3702 == ERROR_SUCCESS && bufsz > 1) {
3703 status = evdns_nameserver_ip_add_line(base,buf);
3710 #define SERVICES_KEY TEXT("System\\CurrentControlSet\\Services\\")
3711 #define WIN_NS_9X_KEY SERVICES_KEY TEXT("VxD\\MSTCP")
3712 #define WIN_NS_NT_KEY SERVICES_KEY TEXT("Tcpip\\Parameters")
3715 load_nameservers_from_registry(struct evdns_base *base)
3719 #define TRY(k, name) \
3720 if (!found && config_nameserver_from_reg_key(base,k,TEXT(name)) == 0) { \
3721 log(EVDNS_LOG_DEBUG,"Found nameservers in %s/%s",#k,name); \
3723 } else if (!found) { \
3724 log(EVDNS_LOG_DEBUG,"Didn't find nameservers in %s/%s", \
3728 ASSERT_LOCKED(base);
3730 if (((int)GetVersion()) > 0) { /* NT */
3731 HKEY nt_key = 0, interfaces_key = 0;
3733 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0,
3734 KEY_READ, &nt_key) != ERROR_SUCCESS) {
3735 log(EVDNS_LOG_DEBUG,"Couldn't open nt key, %d",(int)GetLastError());
3738 r = RegOpenKeyEx(nt_key, TEXT("Interfaces"), 0,
3739 KEY_QUERY_VALUE|KEY_ENUMERATE_SUB_KEYS,
3741 if (r != ERROR_SUCCESS) {
3742 log(EVDNS_LOG_DEBUG,"Couldn't open interfaces key, %d",(int)GetLastError());
3745 TRY(nt_key, "NameServer");
3746 TRY(nt_key, "DhcpNameServer");
3747 TRY(interfaces_key, "NameServer");
3748 TRY(interfaces_key, "DhcpNameServer");
3749 RegCloseKey(interfaces_key);
3750 RegCloseKey(nt_key);
3753 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_9X_KEY, 0,
3754 KEY_READ, &win_key) != ERROR_SUCCESS) {
3755 log(EVDNS_LOG_DEBUG, "Couldn't open registry key, %d", (int)GetLastError());
3758 TRY(win_key, "NameServer");
3759 RegCloseKey(win_key);
3763 log(EVDNS_LOG_WARN,"Didn't find any nameservers.");
3766 return found ? 0 : -1;
3771 evdns_base_config_windows_nameservers(struct evdns_base *base)
3776 base = current_base;
3780 if (load_nameservers_with_getnetworkparams(base) == 0) {
3784 r = load_nameservers_from_registry(base);
3786 fname = evdns_get_default_hosts_filename();
3787 evdns_base_load_hosts(base, fname);
3796 evdns_config_windows_nameservers(void)
3798 if (!current_base) {
3799 current_base = evdns_base_new(NULL, 1);
3800 return current_base == NULL ? -1 : 0;
3802 return evdns_base_config_windows_nameservers(current_base);
3808 evdns_base_new(struct event_base *event_base, int initialize_nameservers)
3810 struct evdns_base *base;
3812 if (evutil_secure_rng_init() < 0) {
3813 log(EVDNS_LOG_WARN, "Unable to seed random number generator; "
3818 /* Give the evutil library a hook into its evdns-enabled
3819 * functionality. We can't just call evdns_getaddrinfo directly or
3820 * else libevent-core will depend on libevent-extras. */
3821 evutil_set_evdns_getaddrinfo_fn(evdns_getaddrinfo);
3823 base = mm_malloc(sizeof(struct evdns_base));
3826 memset(base, 0, sizeof(struct evdns_base));
3827 base->req_waiting_head = NULL;
3829 EVTHREAD_ALLOC_LOCK(base->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
3832 /* Set max requests inflight and allocate req_heads. */
3833 base->req_heads = NULL;
3835 evdns_base_set_max_requests_inflight(base, 64);
3837 base->server_head = NULL;
3838 base->event_base = event_base;
3839 base->global_good_nameservers = base->global_requests_inflight =
3840 base->global_requests_waiting = 0;
3842 base->global_timeout.tv_sec = 5;
3843 base->global_timeout.tv_usec = 0;
3844 base->global_max_reissues = 1;
3845 base->global_max_retransmits = 3;
3846 base->global_max_nameserver_timeout = 3;
3847 base->global_search_state = NULL;
3848 base->global_randomize_case = 1;
3849 base->global_getaddrinfo_allow_skew.tv_sec = 3;
3850 base->global_getaddrinfo_allow_skew.tv_usec = 0;
3851 base->global_nameserver_probe_initial_timeout.tv_sec = 10;
3852 base->global_nameserver_probe_initial_timeout.tv_usec = 0;
3854 TAILQ_INIT(&base->hostsdb);
3856 if (initialize_nameservers) {
3859 r = evdns_base_config_windows_nameservers(base);
3861 r = evdns_base_resolv_conf_parse(base, DNS_OPTIONS_ALL, "/etc/resolv.conf");
3864 evdns_base_free_and_unlock(base, 0);
3875 struct evdns_base *base = evdns_base_new(NULL, 1);
3877 current_base = base;
3885 evdns_err_to_string(int err)
3888 case DNS_ERR_NONE: return "no error";
3889 case DNS_ERR_FORMAT: return "misformatted query";
3890 case DNS_ERR_SERVERFAILED: return "server failed";
3891 case DNS_ERR_NOTEXIST: return "name does not exist";
3892 case DNS_ERR_NOTIMPL: return "query not implemented";
3893 case DNS_ERR_REFUSED: return "refused";
3895 case DNS_ERR_TRUNCATED: return "reply truncated or ill-formed";
3896 case DNS_ERR_UNKNOWN: return "unknown";
3897 case DNS_ERR_TIMEOUT: return "request timed out";
3898 case DNS_ERR_SHUTDOWN: return "dns subsystem shut down";
3899 case DNS_ERR_CANCEL: return "dns request canceled";
3900 case DNS_ERR_NODATA: return "no records in the reply";
3901 default: return "[Unknown error code]";
3906 evdns_nameserver_free(struct nameserver *server)
3908 if (server->socket >= 0)
3909 evutil_closesocket(server->socket);
3910 (void) event_del(&server->event);
3911 event_debug_unassign(&server->event);
3912 if (server->state == 0)
3913 (void) event_del(&server->timeout_event);
3914 event_debug_unassign(&server->timeout_event);
3919 evdns_base_free_and_unlock(struct evdns_base *base, int fail_requests)
3921 struct nameserver *server, *server_next;
3922 struct search_domain *dom, *dom_next;
3925 /* Requires that we hold the lock. */
3927 /* TODO(nickm) we might need to refcount here. */
3929 for (i = 0; i < base->n_req_heads; ++i) {
3930 while (base->req_heads[i]) {
3932 reply_schedule_callback(base->req_heads[i], 0, DNS_ERR_SHUTDOWN, NULL);
3933 request_finished(base->req_heads[i], &REQ_HEAD(base, base->req_heads[i]->trans_id), 1);
3936 while (base->req_waiting_head) {
3938 reply_schedule_callback(base->req_waiting_head, 0, DNS_ERR_SHUTDOWN, NULL);
3939 request_finished(base->req_waiting_head, &base->req_waiting_head, 1);
3941 base->global_requests_inflight = base->global_requests_waiting = 0;
3943 for (server = base->server_head; server; server = server_next) {
3944 server_next = server->next;
3945 evdns_nameserver_free(server);
3946 if (server_next == base->server_head)
3949 base->server_head = NULL;
3950 base->global_good_nameservers = 0;
3952 if (base->global_search_state) {
3953 for (dom = base->global_search_state->head; dom; dom = dom_next) {
3954 dom_next = dom->next;
3957 mm_free(base->global_search_state);
3958 base->global_search_state = NULL;
3962 struct hosts_entry *victim;
3963 while ((victim = TAILQ_FIRST(&base->hostsdb))) {
3964 TAILQ_REMOVE(&base->hostsdb, victim, next);
3969 mm_free(base->req_heads);
3972 EVTHREAD_FREE_LOCK(base->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
3978 evdns_base_free(struct evdns_base *base, int fail_requests)
3981 evdns_base_free_and_unlock(base, fail_requests);
3985 evdns_shutdown(int fail_requests)
3988 struct evdns_base *b = current_base;
3989 current_base = NULL;
3990 evdns_base_free(b, fail_requests);
3992 evdns_log_fn = NULL;
3996 evdns_base_parse_hosts_line(struct evdns_base *base, char *line)
3999 static const char *const delims = " \t";
4000 char *const addr = strtok_r(line, delims, &strtok_state);
4001 char *hostname, *hash;
4002 struct sockaddr_storage ss;
4003 int socklen = sizeof(ss);
4004 ASSERT_LOCKED(base);
4006 #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state)
4008 if (!addr || *addr == '#')
4011 memset(&ss, 0, sizeof(ss));
4012 if (evutil_parse_sockaddr_port(addr, (struct sockaddr*)&ss, &socklen)<0)
4014 if (socklen > (int)sizeof(struct sockaddr_in6))
4017 if (sockaddr_getport((struct sockaddr*)&ss))
4020 while ((hostname = NEXT_TOKEN)) {
4021 struct hosts_entry *he;
4023 if ((hash = strchr(hostname, '#'))) {
4024 if (hash == hostname)
4029 namelen = strlen(hostname);
4031 he = mm_calloc(1, sizeof(struct hosts_entry)+namelen);
4034 EVUTIL_ASSERT(socklen <= (int)sizeof(he->addr));
4035 memcpy(&he->addr, &ss, socklen);
4036 memcpy(he->hostname, hostname, namelen+1);
4037 he->addrlen = socklen;
4039 TAILQ_INSERT_TAIL(&base->hostsdb, he, next);
4050 evdns_base_load_hosts_impl(struct evdns_base *base, const char *hosts_fname)
4052 char *str=NULL, *cp, *eol;
4056 ASSERT_LOCKED(base);
4058 if (hosts_fname == NULL ||
4059 (err = evutil_read_file(hosts_fname, &str, &len, 0)) < 0) {
4061 strlcpy(tmp, "127.0.0.1 localhost", sizeof(tmp));
4062 evdns_base_parse_hosts_line(base, tmp);
4063 strlcpy(tmp, "::1 localhost", sizeof(tmp));
4064 evdns_base_parse_hosts_line(base, tmp);
4065 return err ? -1 : 0;
4068 /* This will break early if there is a NUL in the hosts file.
4069 * Probably not a problem.*/
4072 eol = strchr(cp, '\n');
4076 evdns_base_parse_hosts_line(base, cp);
4079 evdns_base_parse_hosts_line(base, cp);
4089 evdns_base_load_hosts(struct evdns_base *base, const char *hosts_fname)
4093 base = current_base;
4095 res = evdns_base_load_hosts_impl(base, hosts_fname);
4100 /* A single request for a getaddrinfo, either v4 or v6. */
4101 struct getaddrinfo_subrequest {
4102 struct evdns_request *r;
4106 /* State data used to implement an in-progress getaddrinfo. */
4107 struct evdns_getaddrinfo_request {
4108 struct evdns_base *evdns_base;
4109 /* Copy of the modified 'hints' data that we'll use to build
4111 struct evutil_addrinfo hints;
4112 /* The callback to invoke when we're done */
4113 evdns_getaddrinfo_cb user_cb;
4114 /* User-supplied data to give to the callback. */
4116 /* The port to use when building sockaddrs. */
4118 /* The sub_request for an A record (if any) */
4119 struct getaddrinfo_subrequest ipv4_request;
4120 /* The sub_request for an AAAA record (if any) */
4121 struct getaddrinfo_subrequest ipv6_request;
4123 /* The cname result that we were told (if any) */
4126 /* If we have one request answered and one request still inflight,
4127 * then this field holds the answer from the first request... */
4128 struct evutil_addrinfo *pending_result;
4129 /* And this event is a timeout that will tell us to cancel the second
4130 * request if it's taking a long time. */
4131 struct event timeout;
4133 /* And this field holds the error code from the first request... */
4135 /* If this is set, the user canceled this request. */
4136 unsigned user_canceled : 1;
4137 /* If this is set, the user can no longer cancel this request; we're
4138 * just waiting for the free. */
4139 unsigned request_done : 1;
4142 /* Convert an evdns errors to the equivalent getaddrinfo error. */
4144 evdns_err_to_getaddrinfo_err(int e1)
4146 /* XXX Do this better! */
4147 if (e1 == DNS_ERR_NONE)
4149 else if (e1 == DNS_ERR_NOTEXIST)
4150 return EVUTIL_EAI_NONAME;
4152 return EVUTIL_EAI_FAIL;
4155 /* Return the more informative of two getaddrinfo errors. */
4157 getaddrinfo_merge_err(int e1, int e2)
4159 /* XXXX be cleverer here. */
4167 free_getaddrinfo_request(struct evdns_getaddrinfo_request *data)
4169 /* DO NOT CALL this if either of the requests is pending. Only once
4170 * both callbacks have been invoked is it safe to free the request */
4171 if (data->pending_result)
4172 evutil_freeaddrinfo(data->pending_result);
4173 if (data->cname_result)
4174 mm_free(data->cname_result);
4175 event_del(&data->timeout);
4181 add_cname_to_reply(struct evdns_getaddrinfo_request *data,
4182 struct evutil_addrinfo *ai)
4184 if (data->cname_result && ai) {
4185 ai->ai_canonname = data->cname_result;
4186 data->cname_result = NULL;
4190 /* Callback: invoked when one request in a mixed-format A/AAAA getaddrinfo
4191 * request has finished, but the other one took too long to answer. Pass
4192 * along the answer we got, and cancel the other request.
4195 evdns_getaddrinfo_timeout_cb(evutil_socket_t fd, short what, void *ptr)
4197 int v4_timedout = 0, v6_timedout = 0;
4198 struct evdns_getaddrinfo_request *data = ptr;
4200 /* Cancel any pending requests, and note which one */
4201 if (data->ipv4_request.r) {
4202 evdns_cancel_request(NULL, data->ipv4_request.r);
4204 EVDNS_LOCK(data->evdns_base);
4205 ++data->evdns_base->getaddrinfo_ipv4_timeouts;
4206 EVDNS_UNLOCK(data->evdns_base);
4208 if (data->ipv6_request.r) {
4209 evdns_cancel_request(NULL, data->ipv6_request.r);
4211 EVDNS_LOCK(data->evdns_base);
4212 ++data->evdns_base->getaddrinfo_ipv6_timeouts;
4213 EVDNS_UNLOCK(data->evdns_base);
4216 /* We only use this timeout callback when we have an answer for
4218 EVUTIL_ASSERT(!v4_timedout || !v6_timedout);
4220 /* Report the outcome of the other request that didn't time out. */
4221 if (data->pending_result) {
4222 add_cname_to_reply(data, data->pending_result);
4223 data->user_cb(0, data->pending_result, data->user_data);
4224 data->pending_result = NULL;
4226 int e = data->pending_error;
4228 e = EVUTIL_EAI_AGAIN;
4229 data->user_cb(e, NULL, data->user_data);
4232 if (!v4_timedout && !v6_timedout) {
4233 /* should be impossible? XXXX */
4234 free_getaddrinfo_request(data);
4239 evdns_getaddrinfo_set_timeout(struct evdns_base *evdns_base,
4240 struct evdns_getaddrinfo_request *data)
4242 return event_add(&data->timeout, &evdns_base->global_getaddrinfo_allow_skew);
4246 evdns_result_is_answer(int result)
4248 return (result != DNS_ERR_NOTIMPL && result != DNS_ERR_REFUSED &&
4249 result != DNS_ERR_SERVERFAILED && result != DNS_ERR_CANCEL);
4253 evdns_getaddrinfo_gotresolve(int result, char type, int count,
4254 int ttl, void *addresses, void *arg)
4257 struct getaddrinfo_subrequest *req = arg;
4258 struct getaddrinfo_subrequest *other_req;
4259 struct evdns_getaddrinfo_request *data;
4261 struct evutil_addrinfo *res;
4263 struct sockaddr_in sin;
4264 struct sockaddr_in6 sin6;
4265 struct sockaddr *sa;
4266 int socklen, addrlen;
4271 EVUTIL_ASSERT(req->type == DNS_IPv4_A || req->type == DNS_IPv6_AAAA);
4272 if (req->type == DNS_IPv4_A) {
4273 data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv4_request);
4274 other_req = &data->ipv6_request;
4276 data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv6_request);
4277 other_req = &data->ipv4_request;
4280 EVDNS_LOCK(data->evdns_base);
4281 if (evdns_result_is_answer(result)) {
4282 if (req->type == DNS_IPv4_A)
4283 ++data->evdns_base->getaddrinfo_ipv4_answered;
4285 ++data->evdns_base->getaddrinfo_ipv6_answered;
4287 user_canceled = data->user_canceled;
4288 if (other_req->r == NULL)
4289 data->request_done = 1;
4290 EVDNS_UNLOCK(data->evdns_base);
4294 if (result == DNS_ERR_CANCEL && ! user_canceled) {
4295 /* Internal cancel request from timeout or internal error.
4296 * we already answered the user. */
4297 if (other_req->r == NULL)
4298 free_getaddrinfo_request(data);
4302 if (result == DNS_ERR_NONE) {
4304 err = EVUTIL_EAI_NODATA;
4308 err = evdns_err_to_getaddrinfo_err(result);
4312 /* Looks like we got an error. */
4314 /* The other request is still working; maybe it will
4316 /* XXXX handle failure from set_timeout */
4317 evdns_getaddrinfo_set_timeout(data->evdns_base, data);
4318 data->pending_error = err;
4322 if (user_canceled) {
4323 data->user_cb(EVUTIL_EAI_CANCEL, NULL, data->user_data);
4324 } else if (data->pending_result) {
4325 /* If we have an answer waiting, and we weren't
4326 * canceled, ignore this error. */
4327 add_cname_to_reply(data, data->pending_result);
4328 data->user_cb(0, data->pending_result, data->user_data);
4329 data->pending_result = NULL;
4331 if (data->pending_error)
4332 err = getaddrinfo_merge_err(err,
4333 data->pending_error);
4334 data->user_cb(err, NULL, data->user_data);
4336 free_getaddrinfo_request(data);
4338 } else if (user_canceled) {
4340 /* The other request is still working; let it hit this
4341 * callback with EVUTIL_EAI_CANCEL callback and report
4345 data->user_cb(EVUTIL_EAI_CANCEL, NULL, data->user_data);
4346 free_getaddrinfo_request(data);
4350 /* Looks like we got some answers. We should turn them into addrinfos
4351 * and then either queue those or return them all. */
4352 EVUTIL_ASSERT(type == DNS_IPv4_A || type == DNS_IPv6_AAAA);
4354 if (type == DNS_IPv4_A) {
4355 memset(&sin, 0, sizeof(sin));
4356 sin.sin_family = AF_INET;
4357 sin.sin_port = htons(data->port);
4359 sa = (struct sockaddr *)&sin;
4360 socklen = sizeof(sin);
4362 addrp = &sin.sin_addr.s_addr;
4364 memset(&sin6, 0, sizeof(sin6));
4365 sin6.sin6_family = AF_INET6;
4366 sin6.sin6_port = htons(data->port);
4368 sa = (struct sockaddr *)&sin6;
4369 socklen = sizeof(sin6);
4371 addrp = &sin6.sin6_addr.s6_addr;
4375 for (i=0; i < count; ++i) {
4376 struct evutil_addrinfo *ai;
4377 memcpy(addrp, ((char*)addresses)+i*addrlen, addrlen);
4378 ai = evutil_new_addrinfo(sa, socklen, &data->hints);
4381 evdns_cancel_request(NULL, other_req->r);
4383 data->user_cb(EVUTIL_EAI_MEMORY, NULL, data->user_data);
4385 evutil_freeaddrinfo(res);
4387 if (other_req->r == NULL)
4388 free_getaddrinfo_request(data);
4391 res = evutil_addrinfo_append(res, ai);
4395 /* The other request is still in progress; wait for it */
4396 /* XXXX handle failure from set_timeout */
4397 evdns_getaddrinfo_set_timeout(data->evdns_base, data);
4398 data->pending_result = res;
4401 /* The other request is done or never started; append its
4402 * results (if any) and return them. */
4403 if (data->pending_result) {
4404 if (req->type == DNS_IPv4_A)
4405 res = evutil_addrinfo_append(res,
4406 data->pending_result);
4408 res = evutil_addrinfo_append(
4409 data->pending_result, res);
4410 data->pending_result = NULL;
4413 /* Call the user callback. */
4414 add_cname_to_reply(data, res);
4415 data->user_cb(0, res, data->user_data);
4418 free_getaddrinfo_request(data);
4422 static struct hosts_entry *
4423 find_hosts_entry(struct evdns_base *base, const char *hostname,
4424 struct hosts_entry *find_after)
4426 struct hosts_entry *e;
4429 e = TAILQ_NEXT(find_after, next);
4431 e = TAILQ_FIRST(&base->hostsdb);
4433 for (; e; e = TAILQ_NEXT(e, next)) {
4434 if (!evutil_ascii_strcasecmp(e->hostname, hostname))
4441 evdns_getaddrinfo_fromhosts(struct evdns_base *base,
4442 const char *nodename, struct evutil_addrinfo *hints, ev_uint16_t port,
4443 struct evutil_addrinfo **res)
4446 struct hosts_entry *e;
4447 struct evutil_addrinfo *ai=NULL;
4448 int f = hints->ai_family;
4451 for (e = find_hosts_entry(base, nodename, NULL); e;
4452 e = find_hosts_entry(base, nodename, e)) {
4453 struct evutil_addrinfo *ai_new;
4455 if ((e->addr.sa.sa_family == AF_INET && f == PF_INET6) ||
4456 (e->addr.sa.sa_family == AF_INET6 && f == PF_INET))
4458 ai_new = evutil_new_addrinfo(&e->addr.sa, e->addrlen, hints);
4463 sockaddr_setport(ai_new->ai_addr, port);
4464 ai = evutil_addrinfo_append(ai, ai_new);
4469 /* Note that we return an empty answer if we found entries for
4470 * this hostname but none were of the right address type. */
4475 evutil_freeaddrinfo(ai);
4480 struct evdns_getaddrinfo_request *
4481 evdns_getaddrinfo(struct evdns_base *dns_base,
4482 const char *nodename, const char *servname,
4483 const struct evutil_addrinfo *hints_in,
4484 evdns_getaddrinfo_cb cb, void *arg)
4486 struct evdns_getaddrinfo_request *data;
4487 struct evutil_addrinfo hints;
4488 struct evutil_addrinfo *res = NULL;
4494 dns_base = current_base;
4497 "Call to getaddrinfo_async with no "
4498 "evdns_base configured.");
4499 cb(EVUTIL_EAI_FAIL, NULL, arg); /* ??? better error? */
4504 /* If we _must_ answer this immediately, do so. */
4505 if ((hints_in && (hints_in->ai_flags & EVUTIL_AI_NUMERICHOST))) {
4507 err = evutil_getaddrinfo(nodename, servname, hints_in, &res);
4513 memcpy(&hints, hints_in, sizeof(hints));
4515 memset(&hints, 0, sizeof(hints));
4516 hints.ai_family = PF_UNSPEC;
4519 evutil_adjust_hints_for_addrconfig(&hints);
4521 /* Now try to see if we _can_ answer immediately. */
4522 /* (It would be nice to do this by calling getaddrinfo directly, with
4523 * AI_NUMERICHOST, on plaforms that have it, but we can't: there isn't
4524 * a reliable way to distinguish the "that wasn't a numeric host!" case
4525 * from any other EAI_NONAME cases.) */
4526 err = evutil_getaddrinfo_common(nodename, servname, &hints, &res, &port);
4527 if (err != EVUTIL_EAI_NEED_RESOLVE) {
4532 /* If there is an entry in the hosts file, we should give it now. */
4533 if (!evdns_getaddrinfo_fromhosts(dns_base, nodename, &hints, port, &res)) {
4538 /* Okay, things are serious now. We're going to need to actually
4541 data = mm_calloc(1,sizeof(struct evdns_getaddrinfo_request));
4543 cb(EVUTIL_EAI_MEMORY, NULL, arg);
4547 memcpy(&data->hints, &hints, sizeof(data->hints));
4548 data->port = (ev_uint16_t)port;
4549 data->ipv4_request.type = DNS_IPv4_A;
4550 data->ipv6_request.type = DNS_IPv6_AAAA;
4552 data->user_data = arg;
4553 data->evdns_base = dns_base;
4555 want_cname = (hints.ai_flags & EVUTIL_AI_CANONNAME);
4557 /* If we are asked for a PF_UNSPEC address, we launch two requests in
4558 * parallel: one for an A address and one for an AAAA address. We
4559 * can't send just one request, since many servers only answer one
4560 * question per DNS request.
4562 * Once we have the answer to one request, we allow for a short
4563 * timeout before we report it, to see if the other one arrives. If
4564 * they both show up in time, then we report both the answers.
4566 * If too many addresses of one type time out or fail, we should stop
4567 * launching those requests. (XXX we don't do that yet.)
4570 if (hints.ai_family != PF_INET6) {
4571 log(EVDNS_LOG_DEBUG, "Sending request for %s on ipv4 as %p",
4572 nodename, &data->ipv4_request);
4574 data->ipv4_request.r = evdns_base_resolve_ipv4(dns_base,
4575 nodename, 0, evdns_getaddrinfo_gotresolve,
4576 &data->ipv4_request);
4578 data->ipv4_request.r->current_req->put_cname_in_ptr =
4579 &data->cname_result;
4581 if (hints.ai_family != PF_INET) {
4582 log(EVDNS_LOG_DEBUG, "Sending request for %s on ipv6 as %p",
4583 nodename, &data->ipv6_request);
4585 data->ipv6_request.r = evdns_base_resolve_ipv6(dns_base,
4586 nodename, 0, evdns_getaddrinfo_gotresolve,
4587 &data->ipv6_request);
4589 data->ipv6_request.r->current_req->put_cname_in_ptr =
4590 &data->cname_result;
4593 evtimer_assign(&data->timeout, dns_base->event_base,
4594 evdns_getaddrinfo_timeout_cb, data);
4596 if (data->ipv4_request.r || data->ipv6_request.r) {
4600 cb(EVUTIL_EAI_FAIL, NULL, arg);
4606 evdns_getaddrinfo_cancel(struct evdns_getaddrinfo_request *data)
4608 EVDNS_LOCK(data->evdns_base);
4609 if (data->request_done) {
4610 EVDNS_UNLOCK(data->evdns_base);
4613 event_del(&data->timeout);
4614 data->user_canceled = 1;
4615 if (data->ipv4_request.r)
4616 evdns_cancel_request(data->evdns_base, data->ipv4_request.r);
4617 if (data->ipv6_request.r)
4618 evdns_cancel_request(data->evdns_base, data->ipv6_request.r);
4619 EVDNS_UNLOCK(data->evdns_base);