1 /* $Id: evdns.c 6979 2006-08-04 18:31:13Z nickm $ */
3 /* The original version of this module was written by Adam Langley; for
4 * a history of modifications, check out the subversion logs.
6 * When editing this module, try to keep it re-mergeable by Adam. Don't
7 * reformat the whitespace, add Tor dependencies, or so on.
10 * - Support IPv6 and PTR records.
11 * - Replace all externally visible magic numbers with #defined constants.
12 * - Write documentation for APIs of all external functions.
16 * Adam Langley <agl@imperialviolet.org>
17 * http://www.imperialviolet.org/eventdns.html
20 * This software is Public Domain. To view a copy of the public domain dedication,
21 * visit http://creativecommons.org/licenses/publicdomain/ or send a letter to
22 * Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA.
24 * I ask and expect, but do not require, that all derivative works contain an
25 * attribution similar to:
26 * Parts developed by Adam Langley <agl@imperialviolet.org>
28 * You may wish to replace the word "Parts" with something else depending on
29 * the amount of original code.
31 * (Derivative works does not include programs which link against, run or include
32 * the source verbatim in their source distributions)
37 #include <sys/types.h>
38 #include "event2/event-config.h"
40 #ifndef _FORTIFY_SOURCE
41 #define _FORTIFY_SOURCE 3
46 #ifdef _EVENT_HAVE_SYS_TIME_H
49 #ifdef _EVENT_HAVE_STDINT_H
55 #ifdef _EVENT_HAVE_UNISTD_H
66 #define _WIN32_IE 0x400
71 #include "event2/dns.h"
72 #include "event2/dns_struct.h"
73 #include "event2/dns_compat.h"
74 #include "event2/util.h"
75 #include "event2/event.h"
76 #include "event2/event_struct.h"
77 #include "event2/thread.h"
79 #include "event2/bufferevent.h"
80 #include "event2/bufferevent_struct.h"
81 #include "bufferevent-internal.h"
83 #include "defer-internal.h"
84 #include "log-internal.h"
85 #include "mm-internal.h"
86 #include "strlcpy-internal.h"
87 #include "ipv6-internal.h"
88 #include "util-internal.h"
89 #include "evthread-internal.h"
97 #include <sys/socket.h>
98 #include <netinet/in.h>
99 #include <arpa/inet.h>
102 #ifdef _EVENT_HAVE_NETINET_IN6_H
103 #include <netinet/in6.h>
106 #define EVDNS_LOG_DEBUG 0
107 #define EVDNS_LOG_WARN 1
108 #define EVDNS_LOG_MSG 2
110 #ifndef HOST_NAME_MAX
111 #define HOST_NAME_MAX 255
117 #define MIN(a,b) ((a)<(b)?(a):(b))
119 #define ASSERT_VALID_REQUEST(req) \
120 EVUTIL_ASSERT((req)->handle && (req)->handle->current_req == (req))
122 #define u64 ev_uint64_t
123 #define u32 ev_uint32_t
124 #define u16 ev_uint16_t
125 #define u8 ev_uint8_t
127 /* maximum number of addresses from a single packet */
128 /* that we bother recording */
129 #define MAX_V4_ADDRS 32
130 #define MAX_V6_ADDRS 32
133 #define TYPE_A EVDNS_TYPE_A
135 #define TYPE_PTR EVDNS_TYPE_PTR
136 #define TYPE_AAAA EVDNS_TYPE_AAAA
138 #define CLASS_INET EVDNS_CLASS_INET
140 /* Persistent handle. We keep this separate from 'struct request' since we
141 * need some object to last for as long as an evdns_request is outstanding so
142 * that it can be canceled, whereas a search request can lead to multiple
143 * 'struct request' instances being created over its lifetime. */
144 struct evdns_request {
145 struct request *current_req;
146 struct evdns_base *base;
148 int pending_cb; /* Waiting for its callback to be invoked; not
149 * owned by event base any more. */
151 /* elements used by the searching code */
153 struct search_state *search_state;
154 char *search_origname; /* needs to be free()ed */
159 u8 *request; /* the dns packet data */
160 u8 request_type; /* TYPE_PTR or TYPE_A or TYPE_AAAA */
161 unsigned int request_len;
163 int tx_count; /* the number of times that this packet has been sent */
164 void *user_pointer; /* the pointer given to us for this request */
165 evdns_callback_type user_callback;
166 struct nameserver *ns; /* the server which we last sent it */
168 /* these objects are kept in a circular list */
169 struct request *next, *prev;
171 struct event timeout_event;
173 u16 trans_id; /* the transaction id */
174 unsigned request_appended :1; /* true if the request pointer is data which follows this struct */
175 unsigned transmit_me :1; /* needs to be transmitted */
177 /* XXXX This is a horrible hack. */
178 char **put_cname_in_ptr; /* store the cname here if we get one. */
180 struct evdns_base *base;
182 struct evdns_request *handle;
187 unsigned int have_answer : 1;
191 u32 addresses[MAX_V4_ADDRS];
195 struct in6_addr addresses[MAX_V6_ADDRS];
198 char name[HOST_NAME_MAX];
204 evutil_socket_t socket; /* a connected UDP socket */
205 struct sockaddr_storage address;
206 ev_socklen_t addrlen;
207 int failed_times; /* number of times which we have given this server a chance */
208 int timedout; /* number of times in a row a request has timed out */
210 /* these objects are kept in a circular list */
211 struct nameserver *next, *prev;
212 struct event timeout_event; /* used to keep the timeout for */
213 /* when we next probe this server. */
214 /* Valid if state == 0 */
215 /* Outstanding probe request for this nameserver, if any */
216 struct evdns_request *probe_request;
217 char state; /* zero if we think that this server is down */
218 char choked; /* true if we have an EAGAIN from this server's socket */
219 char write_waiting; /* true if we are waiting for EV_WRITE events */
220 struct evdns_base *base;
224 /* Represents a local port where we're listening for DNS requests. Right now, */
225 /* only UDP is supported. */
226 struct evdns_server_port {
227 evutil_socket_t socket; /* socket we use to read queries and write replies. */
228 int refcnt; /* reference count. */
229 char choked; /* Are we currently blocked from writing? */
230 char closing; /* Are we trying to close this port, pending writes? */
231 evdns_request_callback_fn_type user_callback; /* Fn to handle requests */
232 void *user_data; /* Opaque pointer passed to user_callback */
233 struct event event; /* Read/write event */
234 /* circular list of replies that we want to write. */
235 struct server_request *pending_replies;
236 struct event_base *event_base;
238 #ifndef _EVENT_DISABLE_THREAD_SUPPORT
243 /* Represents part of a reply being built. (That is, a single RR.) */
244 struct server_reply_item {
245 struct server_reply_item *next; /* next item in sequence. */
246 char *name; /* name part of the RR */
247 u16 type; /* The RR type */
248 u16 class; /* The RR class (usually CLASS_INET) */
249 u32 ttl; /* The RR TTL */
250 char is_name; /* True iff data is a label */
251 u16 datalen; /* Length of data; -1 if data is a label */
252 void *data; /* The contents of the RR */
255 /* Represents a request that we've received as a DNS server, and holds */
256 /* the components of the reply as we're constructing it. */
257 struct server_request {
258 /* Pointers to the next and previous entries on the list of replies */
259 /* that we're waiting to write. Only set if we have tried to respond */
260 /* and gotten EAGAIN. */
261 struct server_request *next_pending;
262 struct server_request *prev_pending;
264 u16 trans_id; /* Transaction id. */
265 struct evdns_server_port *port; /* Which port received this request on? */
266 struct sockaddr_storage addr; /* Where to send the response */
267 ev_socklen_t addrlen; /* length of addr */
269 int n_answer; /* how many answer RRs have been set? */
270 int n_authority; /* how many authority RRs have been set? */
271 int n_additional; /* how many additional RRs have been set? */
273 struct server_reply_item *answer; /* linked list of answer RRs */
274 struct server_reply_item *authority; /* linked list of authority RRs */
275 struct server_reply_item *additional; /* linked list of additional RRs */
277 /* Constructed response. Only set once we're ready to send a reply. */
278 /* Once this is set, the RR fields are cleared, and no more should be set. */
282 /* Caller-visible fields: flags, questions. */
283 struct evdns_server_request base;
287 /* An array of n_req_heads circular lists for inflight requests.
288 * Each inflight request req is in req_heads[req->trans_id % n_req_heads].
290 struct request **req_heads;
291 /* A circular list of requests that we're waiting to send, but haven't
292 * sent yet because there are too many requests inflight */
293 struct request *req_waiting_head;
294 /* A circular list of nameservers. */
295 struct nameserver *server_head;
298 struct event_base *event_base;
300 /* The number of good nameservers that we have */
301 int global_good_nameservers;
303 /* inflight requests are contained in the req_head list */
304 /* and are actually going out across the network */
305 int global_requests_inflight;
306 /* requests which aren't inflight are in the waiting list */
307 /* and are counted here */
308 int global_requests_waiting;
310 int global_max_requests_inflight;
312 struct timeval global_timeout; /* 5 seconds by default */
313 int global_max_reissues; /* a reissue occurs when we get some errors from the server */
314 int global_max_retransmits; /* number of times we'll retransmit a request which timed out */
315 /* number of timeouts in a row before we consider this server to be down */
316 int global_max_nameserver_timeout;
317 /* true iff we will use the 0x20 hack to prevent poisoning attacks. */
318 int global_randomize_case;
320 /* The first time that a nameserver fails, how long do we wait before
321 * probing to see if it has returned? */
322 struct timeval global_nameserver_probe_initial_timeout;
324 /** Port to bind to for outgoing DNS packets. */
325 struct sockaddr_storage global_outgoing_address;
326 /** ev_socklen_t for global_outgoing_address. 0 if it isn't set. */
327 ev_socklen_t global_outgoing_addrlen;
329 struct timeval global_getaddrinfo_allow_skew;
331 int getaddrinfo_ipv4_timeouts;
332 int getaddrinfo_ipv6_timeouts;
333 int getaddrinfo_ipv4_answered;
334 int getaddrinfo_ipv6_answered;
336 struct search_state *global_search_state;
338 TAILQ_HEAD(hosts_list, hosts_entry) hostsdb;
340 #ifndef _EVENT_DISABLE_THREAD_SUPPORT
346 TAILQ_ENTRY(hosts_entry) next;
349 struct sockaddr_in sin;
350 struct sockaddr_in6 sin6;
356 static struct evdns_base *current_base = NULL;
359 evdns_get_global_base(void)
364 /* Given a pointer to an evdns_server_request, get the corresponding */
365 /* server_request. */
366 #define TO_SERVER_REQUEST(base_ptr) \
367 ((struct server_request*) \
368 (((char*)(base_ptr) - evutil_offsetof(struct server_request, base))))
370 #define REQ_HEAD(base, id) ((base)->req_heads[id % (base)->n_req_heads])
372 static struct nameserver *nameserver_pick(struct evdns_base *base);
373 static void evdns_request_insert(struct request *req, struct request **head);
374 static void evdns_request_remove(struct request *req, struct request **head);
375 static void nameserver_ready_callback(evutil_socket_t fd, short events, void *arg);
376 static int evdns_transmit(struct evdns_base *base);
377 static int evdns_request_transmit(struct request *req);
378 static void nameserver_send_probe(struct nameserver *const ns);
379 static void search_request_finished(struct evdns_request *const);
380 static int search_try_next(struct evdns_request *const req);
381 static struct request *search_request_new(struct evdns_base *base, struct evdns_request *handle, int type, const char *const name, int flags, evdns_callback_type user_callback, void *user_arg);
382 static void evdns_requests_pump_waiting_queue(struct evdns_base *base);
383 static u16 transaction_id_pick(struct evdns_base *base);
384 static struct request *request_new(struct evdns_base *base, struct evdns_request *handle, int type, const char *name, int flags, evdns_callback_type callback, void *ptr);
385 static void request_submit(struct request *const req);
387 static int server_request_free(struct server_request *req);
388 static void server_request_free_answers(struct server_request *req);
389 static void server_port_free(struct evdns_server_port *port);
390 static void server_port_ready_callback(evutil_socket_t fd, short events, void *arg);
391 static int evdns_base_resolv_conf_parse_impl(struct evdns_base *base, int flags, const char *const filename);
392 static int evdns_base_set_option_impl(struct evdns_base *base,
393 const char *option, const char *val, int flags);
394 static void evdns_base_free_and_unlock(struct evdns_base *base, int fail_requests);
396 static int strtoint(const char *const str);
398 #ifdef _EVENT_DISABLE_THREAD_SUPPORT
399 #define EVDNS_LOCK(base) _EVUTIL_NIL_STMT
400 #define EVDNS_UNLOCK(base) _EVUTIL_NIL_STMT
401 #define ASSERT_LOCKED(base) _EVUTIL_NIL_STMT
403 #define EVDNS_LOCK(base) \
404 EVLOCK_LOCK((base)->lock, 0)
405 #define EVDNS_UNLOCK(base) \
406 EVLOCK_UNLOCK((base)->lock, 0)
407 #define ASSERT_LOCKED(base) \
408 EVLOCK_ASSERT_LOCKED((base)->lock)
412 default_evdns_log_fn(int warning, const char *buf)
414 if (warning == EVDNS_LOG_WARN)
415 event_warnx("[evdns] %s", buf);
416 else if (warning == EVDNS_LOG_MSG)
417 event_msgx("[evdns] %s", buf);
419 event_debug(("[evdns] %s", buf));
422 static evdns_debug_log_fn_type evdns_log_fn = NULL;
425 evdns_set_log_fn(evdns_debug_log_fn_type fn)
431 #define EVDNS_LOG_CHECK __attribute__ ((format(printf, 2, 3)))
433 #define EVDNS_LOG_CHECK
436 static void _evdns_log(int warn, const char *fmt, ...) EVDNS_LOG_CHECK;
438 _evdns_log(int warn, const char *fmt, ...)
445 evutil_vsnprintf(buf, sizeof(buf), fmt, args);
448 if (warn == EVDNS_LOG_MSG)
449 warn = EVDNS_LOG_WARN;
450 evdns_log_fn(warn, buf);
452 default_evdns_log_fn(warn, buf);
457 #define log _evdns_log
459 /* This walks the list of inflight requests to find the */
460 /* one with a matching transaction id. Returns NULL on */
462 static struct request *
463 request_find_from_trans_id(struct evdns_base *base, u16 trans_id) {
464 struct request *req = REQ_HEAD(base, trans_id);
465 struct request *const started_at = req;
471 if (req->trans_id == trans_id) return req;
473 } while (req != started_at);
479 /* a libevent callback function which is called when a nameserver */
480 /* has gone down and we want to test if it has came back to life yet */
482 nameserver_prod_callback(evutil_socket_t fd, short events, void *arg) {
483 struct nameserver *const ns = (struct nameserver *) arg;
487 EVDNS_LOCK(ns->base);
488 nameserver_send_probe(ns);
489 EVDNS_UNLOCK(ns->base);
492 /* a libevent callback which is called when a nameserver probe (to see if */
493 /* it has come back to life) times out. We increment the count of failed_times */
494 /* and wait longer to send the next probe packet. */
496 nameserver_probe_failed(struct nameserver *const ns) {
497 struct timeval timeout;
500 ASSERT_LOCKED(ns->base);
501 (void) evtimer_del(&ns->timeout_event);
502 if (ns->state == 1) {
503 /* This can happen if the nameserver acts in a way which makes us mark */
504 /* it as bad and then starts sending good replies. */
508 #define MAX_PROBE_TIMEOUT 3600
509 #define TIMEOUT_BACKOFF_FACTOR 3
511 memcpy(&timeout, &ns->base->global_nameserver_probe_initial_timeout,
512 sizeof(struct timeval));
513 for (i=ns->failed_times; i > 0 && timeout.tv_sec < MAX_PROBE_TIMEOUT; --i) {
514 timeout.tv_sec *= TIMEOUT_BACKOFF_FACTOR;
515 timeout.tv_usec *= TIMEOUT_BACKOFF_FACTOR;
516 if (timeout.tv_usec > 1000000) {
517 timeout.tv_sec += timeout.tv_usec / 1000000;
518 timeout.tv_usec %= 1000000;
521 if (timeout.tv_sec > MAX_PROBE_TIMEOUT) {
522 timeout.tv_sec = MAX_PROBE_TIMEOUT;
528 if (evtimer_add(&ns->timeout_event, &timeout) < 0) {
531 "Error from libevent when adding timer event for %s",
532 evutil_format_sockaddr_port(
533 (struct sockaddr *)&ns->address,
534 addrbuf, sizeof(addrbuf)));
538 /* called when a nameserver has been deemed to have failed. For example, too */
539 /* many packets have timed out etc */
541 nameserver_failed(struct nameserver *const ns, const char *msg) {
542 struct request *req, *started_at;
543 struct evdns_base *base = ns->base;
548 /* if this nameserver has already been marked as failed */
549 /* then don't do anything */
550 if (!ns->state) return;
552 log(EVDNS_LOG_MSG, "Nameserver %s has failed: %s",
553 evutil_format_sockaddr_port(
554 (struct sockaddr *)&ns->address,
555 addrbuf, sizeof(addrbuf)),
558 base->global_good_nameservers--;
559 EVUTIL_ASSERT(base->global_good_nameservers >= 0);
560 if (base->global_good_nameservers == 0) {
561 log(EVDNS_LOG_MSG, "All nameservers have failed");
565 ns->failed_times = 1;
567 if (evtimer_add(&ns->timeout_event,
568 &base->global_nameserver_probe_initial_timeout) < 0) {
570 "Error from libevent when adding timer event for %s",
571 evutil_format_sockaddr_port(
572 (struct sockaddr *)&ns->address,
573 addrbuf, sizeof(addrbuf)));
577 /* walk the list of inflight requests to see if any can be reassigned to */
578 /* a different server. Requests in the waiting queue don't have a */
579 /* nameserver assigned yet */
581 /* if we don't have *any* good nameservers then there's no point */
582 /* trying to reassign requests to one */
583 if (!base->global_good_nameservers) return;
585 for (i = 0; i < base->n_req_heads; ++i) {
586 req = started_at = base->req_heads[i];
589 if (req->tx_count == 0 && req->ns == ns) {
590 /* still waiting to go out, can be moved */
591 /* to another server */
592 req->ns = nameserver_pick(base);
595 } while (req != started_at);
601 nameserver_up(struct nameserver *const ns)
604 ASSERT_LOCKED(ns->base);
605 if (ns->state) return;
606 log(EVDNS_LOG_MSG, "Nameserver %s is back up",
607 evutil_format_sockaddr_port(
608 (struct sockaddr *)&ns->address,
609 addrbuf, sizeof(addrbuf)));
610 evtimer_del(&ns->timeout_event);
611 if (ns->probe_request) {
612 evdns_cancel_request(ns->base, ns->probe_request);
613 ns->probe_request = NULL;
616 ns->failed_times = 0;
618 ns->base->global_good_nameservers++;
622 request_trans_id_set(struct request *const req, const u16 trans_id) {
623 req->trans_id = trans_id;
624 *((u16 *) req->request) = htons(trans_id);
627 /* Called to remove a request from a list and dealloc it. */
628 /* head is a pointer to the head of the list it should be */
629 /* removed from or NULL if the request isn't in a list. */
630 /* when free_handle is one, free the handle as well. */
632 request_finished(struct request *const req, struct request **head, int free_handle) {
633 struct evdns_base *base = req->base;
634 int was_inflight = (head != &base->req_waiting_head);
636 ASSERT_VALID_REQUEST(req);
639 evdns_request_remove(req, head);
641 log(EVDNS_LOG_DEBUG, "Removing timeout for request %p", req);
643 evtimer_del(&req->timeout_event);
644 base->global_requests_inflight--;
646 base->global_requests_waiting--;
649 if (!req->request_appended) {
650 /* need to free the request data on it's own */
651 mm_free(req->request);
653 /* the request data is appended onto the header */
654 /* so everything gets free()ed when we: */
658 EVUTIL_ASSERT(req->handle->current_req == req);
661 search_request_finished(req->handle);
662 req->handle->current_req = NULL;
663 if (! req->handle->pending_cb) {
664 /* If we're planning to run the callback,
665 * don't free the handle until later. */
666 mm_free(req->handle);
668 req->handle = NULL; /* If we have a bug, let's crash
671 req->handle->current_req = NULL;
677 evdns_requests_pump_waiting_queue(base);
681 /* This is called when a server returns a funny error code. */
682 /* We try the request again with another server. */
686 /* 1 failed/reissue is pointless */
688 request_reissue(struct request *req) {
689 const struct nameserver *const last_ns = req->ns;
690 ASSERT_LOCKED(req->base);
691 ASSERT_VALID_REQUEST(req);
692 /* the last nameserver should have been marked as failing */
693 /* by the caller of this function, therefore pick will try */
694 /* not to return it */
695 req->ns = nameserver_pick(req->base);
696 if (req->ns == last_ns) {
697 /* ... but pick did return it */
698 /* not a lot of point in trying again with the */
703 req->reissue_count++;
705 req->transmit_me = 1;
710 /* this function looks for space on the inflight queue and promotes */
711 /* requests from the waiting queue if it can. */
713 evdns_requests_pump_waiting_queue(struct evdns_base *base) {
715 while (base->global_requests_inflight < base->global_max_requests_inflight &&
716 base->global_requests_waiting) {
718 /* move a request from the waiting queue to the inflight queue */
719 EVUTIL_ASSERT(base->req_waiting_head);
720 req = base->req_waiting_head;
721 evdns_request_remove(req, &base->req_waiting_head);
723 base->global_requests_waiting--;
724 base->global_requests_inflight++;
726 req->ns = nameserver_pick(base);
727 request_trans_id_set(req, transaction_id_pick(base));
729 evdns_request_insert(req, &REQ_HEAD(base, req->trans_id));
730 evdns_request_transmit(req);
731 evdns_transmit(base);
735 /* TODO(nickm) document */
736 struct deferred_reply_callback {
737 struct deferred_cb deferred;
738 struct evdns_request *handle;
743 evdns_callback_type user_callback;
748 reply_run_callback(struct deferred_cb *d, void *user_pointer)
750 struct deferred_reply_callback *cb =
751 EVUTIL_UPCAST(d, struct deferred_reply_callback, deferred);
753 switch (cb->request_type) {
756 cb->user_callback(DNS_ERR_NONE, DNS_IPv4_A,
757 cb->reply.data.a.addrcount, cb->ttl,
758 cb->reply.data.a.addresses,
761 cb->user_callback(cb->err, 0, 0, 0, NULL, user_pointer);
764 if (cb->have_reply) {
765 char *name = cb->reply.data.ptr.name;
766 cb->user_callback(DNS_ERR_NONE, DNS_PTR, 1, cb->ttl,
767 &name, user_pointer);
769 cb->user_callback(cb->err, 0, 0, 0, NULL, user_pointer);
774 cb->user_callback(DNS_ERR_NONE, DNS_IPv6_AAAA,
775 cb->reply.data.aaaa.addrcount, cb->ttl,
776 cb->reply.data.aaaa.addresses,
779 cb->user_callback(cb->err, 0, 0, 0, NULL, user_pointer);
785 if (cb->handle && cb->handle->pending_cb) {
793 reply_schedule_callback(struct request *const req, u32 ttl, u32 err, struct reply *reply)
795 struct deferred_reply_callback *d = mm_calloc(1, sizeof(*d));
798 event_warn("%s: Couldn't allocate space for deferred callback.",
803 ASSERT_LOCKED(req->base);
805 d->request_type = req->request_type;
806 d->user_callback = req->user_callback;
811 memcpy(&d->reply, reply, sizeof(struct reply));
815 req->handle->pending_cb = 1;
816 d->handle = req->handle;
819 event_deferred_cb_init(&d->deferred, reply_run_callback,
821 event_deferred_cb_schedule(
822 event_base_get_deferred_cb_queue(req->base->event_base),
826 /* this processes a parsed reply packet */
828 reply_handle(struct request *const req, u16 flags, u32 ttl, struct reply *reply) {
831 static const int error_codes[] = {
832 DNS_ERR_FORMAT, DNS_ERR_SERVERFAILED, DNS_ERR_NOTEXIST,
833 DNS_ERR_NOTIMPL, DNS_ERR_REFUSED
836 ASSERT_LOCKED(req->base);
837 ASSERT_VALID_REQUEST(req);
839 if (flags & 0x020f || !reply || !reply->have_answer) {
840 /* there was an error */
841 if (flags & 0x0200) {
842 error = DNS_ERR_TRUNCATED;
844 u16 error_code = (flags & 0x000f) - 1;
845 if (error_code > 4) {
846 error = DNS_ERR_UNKNOWN;
848 error = error_codes[error_code];
853 case DNS_ERR_NOTIMPL:
854 case DNS_ERR_REFUSED:
855 /* we regard these errors as marking a bad nameserver */
856 if (req->reissue_count < req->base->global_max_reissues) {
858 evutil_snprintf(msg, sizeof(msg), "Bad response %d (%s)",
859 error, evdns_err_to_string(error));
860 nameserver_failed(req->ns, msg);
861 if (!request_reissue(req)) return;
864 case DNS_ERR_SERVERFAILED:
865 /* rcode 2 (servfailed) sometimes means "we
866 * are broken" and sometimes (with some binds)
867 * means "that request was very confusing."
868 * Treat this as a timeout, not a failure.
870 log(EVDNS_LOG_DEBUG, "Got a SERVERFAILED from nameserver"
871 "at %s; will allow the request to time out.",
872 evutil_format_sockaddr_port(
873 (struct sockaddr *)&req->ns->address,
874 addrbuf, sizeof(addrbuf)));
877 /* we got a good reply from the nameserver */
878 nameserver_up(req->ns);
881 if (req->handle->search_state &&
882 req->request_type != TYPE_PTR) {
883 /* if we have a list of domains to search in,
884 * try the next one */
885 if (!search_try_next(req->handle)) {
886 /* a new request was issued so this
887 * request is finished and */
888 /* the user callback will be made when
889 * that request (or a */
890 /* child of it) finishes. */
895 /* all else failed. Pass the failure up */
896 reply_schedule_callback(req, 0, error, NULL);
897 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1);
899 /* all ok, tell the user */
900 reply_schedule_callback(req, ttl, 0, reply);
901 if (req->handle == req->ns->probe_request)
902 req->ns->probe_request = NULL; /* Avoid double-free */
903 nameserver_up(req->ns);
904 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1);
909 name_parse(u8 *packet, int length, int *idx, char *name_out, int name_out_len) {
913 #define GET32(x) do { if (j + 4 > length) goto err; memcpy(&_t32, packet + j, 4); j += 4; x = ntohl(_t32); } while (0)
914 #define GET16(x) do { if (j + 2 > length) goto err; memcpy(&_t, packet + j, 2); j += 2; x = ntohs(_t); } while (0)
915 #define GET8(x) do { if (j >= length) goto err; x = packet[j++]; } while (0)
918 const char *const end = name_out + name_out_len;
920 /* Normally, names are a series of length prefixed strings terminated */
921 /* with a length of 0 (the lengths are u8's < 63). */
922 /* However, the length can start with a pair of 1 bits and that */
923 /* means that the next 14 bits are a pointer within the current */
928 if (j >= length) return -1;
930 if (!label_len) break;
931 if (label_len & 0xc0) {
934 if (name_end < 0) name_end = j;
935 j = (((int)label_len & 0x3f) << 8) + ptr_low;
936 /* Make sure that the target offset is in-bounds. */
937 if (j < 0 || j >= length) return -1;
938 /* If we've jumped more times than there are characters in the
939 * message, we must have a loop. */
940 if (++ptr_count > length) return -1;
943 if (label_len > 63) return -1;
944 if (cp != name_out) {
945 if (cp + 1 >= end) return -1;
948 if (cp + label_len >= end) return -1;
949 memcpy(cp, packet + j, label_len);
953 if (cp >= end) return -1;
964 /* parses a raw request from a nameserver */
966 reply_parse(struct evdns_base *base, u8 *packet, int length) {
967 int j = 0, k = 0; /* index into packet */
968 u16 _t; /* used by the macros */
969 u32 _t32; /* used by the macros */
970 char tmp_name[256], cmp_name[256]; /* used by the macros */
971 int name_matches = 0;
973 u16 trans_id, questions, answers, authority, additional, datalength;
975 u32 ttl, ttl_r = 0xffffffff;
977 struct request *req = NULL;
988 (void) authority; /* suppress "unused variable" warnings. */
989 (void) additional; /* suppress "unused variable" warnings. */
991 req = request_find_from_trans_id(base, trans_id);
993 EVUTIL_ASSERT(req->base == base);
995 memset(&reply, 0, sizeof(reply));
997 /* If it's not an answer, it doesn't correspond to any request. */
998 if (!(flags & 0x8000)) return -1; /* must be an answer */
999 if (flags & 0x020f) {
1000 /* there was an error */
1003 /* if (!answers) return; */ /* must have an answer of some form */
1005 /* This macro skips a name in the DNS reply. */
1007 do { tmp_name[0] = '\0'; \
1008 if (name_parse(packet, length, &j, tmp_name, \
1009 sizeof(tmp_name))<0) \
1013 do { tmp_name[0] = '\0'; \
1014 cmp_name[0] = '\0'; \
1016 if (name_parse(packet, length, &j, tmp_name, \
1017 sizeof(tmp_name))<0) \
1019 if (name_parse(req->request, req->request_len, &k, \
1020 cmp_name, sizeof(cmp_name))<0) \
1022 if (base->global_randomize_case) { \
1023 if (strcmp(tmp_name, cmp_name) == 0) \
1026 if (evutil_ascii_strcasecmp(tmp_name, cmp_name) == 0) \
1031 reply.type = req->request_type;
1033 /* skip over each question in the reply */
1034 for (i = 0; i < questions; ++i) {
1035 /* the question looks like
1036 * <label:name><u16:type><u16:class>
1040 if (j >= length) goto err;
1046 /* now we have the answer section which looks like
1047 * <label:name><u16:type><u16:class><u32:ttl><u16:len><data...>
1050 for (i = 0; i < answers; ++i) {
1059 if (type == TYPE_A && class == CLASS_INET) {
1060 int addrcount, addrtocopy;
1061 if (req->request_type != TYPE_A) {
1062 j += datalength; continue;
1064 if ((datalength & 3) != 0) /* not an even number of As. */
1066 addrcount = datalength >> 2;
1067 addrtocopy = MIN(MAX_V4_ADDRS - reply.data.a.addrcount, (unsigned)addrcount);
1069 ttl_r = MIN(ttl_r, ttl);
1070 /* we only bother with the first four addresses. */
1071 if (j + 4*addrtocopy > length) goto err;
1072 memcpy(&reply.data.a.addresses[reply.data.a.addrcount],
1073 packet + j, 4*addrtocopy);
1075 reply.data.a.addrcount += addrtocopy;
1076 reply.have_answer = 1;
1077 if (reply.data.a.addrcount == MAX_V4_ADDRS) break;
1078 } else if (type == TYPE_PTR && class == CLASS_INET) {
1079 if (req->request_type != TYPE_PTR) {
1080 j += datalength; continue;
1082 if (name_parse(packet, length, &j, reply.data.ptr.name,
1083 sizeof(reply.data.ptr.name))<0)
1085 ttl_r = MIN(ttl_r, ttl);
1086 reply.have_answer = 1;
1088 } else if (type == TYPE_CNAME) {
1089 char cname[HOST_NAME_MAX];
1090 if (!req->put_cname_in_ptr || *req->put_cname_in_ptr) {
1091 j += datalength; continue;
1093 if (name_parse(packet, length, &j, cname,
1096 *req->put_cname_in_ptr = mm_strdup(cname);
1097 } else if (type == TYPE_AAAA && class == CLASS_INET) {
1098 int addrcount, addrtocopy;
1099 if (req->request_type != TYPE_AAAA) {
1100 j += datalength; continue;
1102 if ((datalength & 15) != 0) /* not an even number of AAAAs. */
1104 addrcount = datalength >> 4; /* each address is 16 bytes long */
1105 addrtocopy = MIN(MAX_V6_ADDRS - reply.data.aaaa.addrcount, (unsigned)addrcount);
1106 ttl_r = MIN(ttl_r, ttl);
1108 /* we only bother with the first four addresses. */
1109 if (j + 16*addrtocopy > length) goto err;
1110 memcpy(&reply.data.aaaa.addresses[reply.data.aaaa.addrcount],
1111 packet + j, 16*addrtocopy);
1112 reply.data.aaaa.addrcount += addrtocopy;
1114 reply.have_answer = 1;
1115 if (reply.data.aaaa.addrcount == MAX_V6_ADDRS) break;
1117 /* skip over any other type of resource */
1122 reply_handle(req, flags, ttl_r, &reply);
1126 reply_handle(req, flags, 0, NULL);
1130 /* Parse a raw request (packet,length) sent to a nameserver port (port) from */
1131 /* a DNS client (addr,addrlen), and if it's well-formed, call the corresponding */
1134 request_parse(u8 *packet, int length, struct evdns_server_port *port, struct sockaddr *addr, ev_socklen_t addrlen)
1136 int j = 0; /* index into packet */
1137 u16 _t; /* used by the macros */
1138 char tmp_name[256]; /* used by the macros */
1141 u16 trans_id, flags, questions, answers, authority, additional;
1142 struct server_request *server_req = NULL;
1144 ASSERT_LOCKED(port);
1146 /* Get the header fields */
1157 if (flags & 0x8000) return -1; /* Must not be an answer. */
1158 flags &= 0x0110; /* Only RD and CD get preserved. */
1160 server_req = mm_malloc(sizeof(struct server_request));
1161 if (server_req == NULL) return -1;
1162 memset(server_req, 0, sizeof(struct server_request));
1164 server_req->trans_id = trans_id;
1165 memcpy(&server_req->addr, addr, addrlen);
1166 server_req->addrlen = addrlen;
1168 server_req->base.flags = flags;
1169 server_req->base.nquestions = 0;
1170 server_req->base.questions = mm_calloc(sizeof(struct evdns_server_question *), questions);
1171 if (server_req->base.questions == NULL)
1174 for (i = 0; i < questions; ++i) {
1176 struct evdns_server_question *q;
1178 if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0)
1182 namelen = (int)strlen(tmp_name);
1183 q = mm_malloc(sizeof(struct evdns_server_question) + namelen);
1187 q->dns_question_class = class;
1188 memcpy(q->name, tmp_name, namelen+1);
1189 server_req->base.questions[server_req->base.nquestions++] = q;
1192 /* Ignore answers, authority, and additional. */
1194 server_req->port = port;
1197 /* Only standard queries are supported. */
1198 if (flags & 0x7800) {
1199 evdns_server_request_respond(&(server_req->base), DNS_ERR_NOTIMPL);
1203 port->user_callback(&(server_req->base), port->user_data);
1208 if (server_req->base.questions) {
1209 for (i = 0; i < server_req->base.nquestions; ++i)
1210 mm_free(server_req->base.questions[i]);
1211 mm_free(server_req->base.questions);
1213 mm_free(server_req);
1225 evdns_set_transaction_id_fn(ev_uint16_t (*fn)(void))
1230 evdns_set_random_bytes_fn(void (*fn)(char *, size_t))
1234 /* Try to choose a strong transaction id which isn't already in flight */
1236 transaction_id_pick(struct evdns_base *base) {
1237 ASSERT_LOCKED(base);
1240 evutil_secure_rng_get_bytes(&trans_id, sizeof(trans_id));
1242 if (trans_id == 0xffff) continue;
1243 /* now check to see if that id is already inflight */
1244 if (request_find_from_trans_id(base, trans_id) == NULL)
1249 /* choose a namesever to use. This function will try to ignore */
1250 /* nameservers which we think are down and load balance across the rest */
1251 /* by updating the server_head global each time. */
1252 static struct nameserver *
1253 nameserver_pick(struct evdns_base *base) {
1254 struct nameserver *started_at = base->server_head, *picked;
1255 ASSERT_LOCKED(base);
1256 if (!base->server_head) return NULL;
1258 /* if we don't have any good nameservers then there's no */
1259 /* point in trying to find one. */
1260 if (!base->global_good_nameservers) {
1261 base->server_head = base->server_head->next;
1262 return base->server_head;
1265 /* remember that nameservers are in a circular list */
1267 if (base->server_head->state) {
1268 /* we think this server is currently good */
1269 picked = base->server_head;
1270 base->server_head = base->server_head->next;
1274 base->server_head = base->server_head->next;
1275 if (base->server_head == started_at) {
1276 /* all the nameservers seem to be down */
1277 /* so we just return this one and hope for the */
1279 EVUTIL_ASSERT(base->global_good_nameservers == 0);
1280 picked = base->server_head;
1281 base->server_head = base->server_head->next;
1287 /* this is called when a namesever socket is ready for reading */
1289 nameserver_read(struct nameserver *ns) {
1290 struct sockaddr_storage ss;
1291 ev_socklen_t addrlen = sizeof(ss);
1294 ASSERT_LOCKED(ns->base);
1297 const int r = recvfrom(ns->socket, (void*)packet,
1299 (struct sockaddr*)&ss, &addrlen);
1301 int err = evutil_socket_geterror(ns->socket);
1302 if (EVUTIL_ERR_RW_RETRIABLE(err))
1304 nameserver_failed(ns,
1305 evutil_socket_error_to_string(err));
1308 if (evutil_sockaddr_cmp((struct sockaddr*)&ss,
1309 (struct sockaddr*)&ns->address, 0)) {
1310 log(EVDNS_LOG_WARN, "Address mismatch on received "
1311 "DNS packet. Apparent source was %s",
1312 evutil_format_sockaddr_port(
1313 (struct sockaddr *)&ss,
1314 addrbuf, sizeof(addrbuf)));
1319 reply_parse(ns->base, packet, r);
1323 /* Read a packet from a DNS client on a server port s, parse it, and */
1324 /* act accordingly. */
1326 server_port_read(struct evdns_server_port *s) {
1328 struct sockaddr_storage addr;
1329 ev_socklen_t addrlen;
1334 addrlen = sizeof(struct sockaddr_storage);
1335 r = recvfrom(s->socket, (void*)packet, sizeof(packet), 0,
1336 (struct sockaddr*) &addr, &addrlen);
1338 int err = evutil_socket_geterror(s->socket);
1339 if (EVUTIL_ERR_RW_RETRIABLE(err))
1342 "Error %s (%d) while reading request.",
1343 evutil_socket_error_to_string(err), err);
1346 request_parse(packet, r, s, (struct sockaddr*) &addr, addrlen);
1350 /* Try to write all pending replies on a given DNS server port. */
1352 server_port_flush(struct evdns_server_port *port)
1354 struct server_request *req = port->pending_replies;
1355 ASSERT_LOCKED(port);
1357 int r = sendto(port->socket, req->response, (int)req->response_len, 0,
1358 (struct sockaddr*) &req->addr, (ev_socklen_t)req->addrlen);
1360 int err = evutil_socket_geterror(port->socket);
1361 if (EVUTIL_ERR_RW_RETRIABLE(err))
1363 log(EVDNS_LOG_WARN, "Error %s (%d) while writing response to port; dropping", evutil_socket_error_to_string(err), err);
1365 if (server_request_free(req)) {
1366 /* we released the last reference to req->port. */
1369 EVUTIL_ASSERT(req != port->pending_replies);
1370 req = port->pending_replies;
1374 /* We have no more pending requests; stop listening for 'writeable' events. */
1375 (void) event_del(&port->event);
1376 event_assign(&port->event, port->event_base,
1377 port->socket, EV_READ | EV_PERSIST,
1378 server_port_ready_callback, port);
1380 if (event_add(&port->event, NULL) < 0) {
1381 log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server.");
1386 /* set if we are waiting for the ability to write to this server. */
1387 /* if waiting is true then we ask libevent for EV_WRITE events, otherwise */
1388 /* we stop these events. */
1390 nameserver_write_waiting(struct nameserver *ns, char waiting) {
1391 ASSERT_LOCKED(ns->base);
1392 if (ns->write_waiting == waiting) return;
1394 ns->write_waiting = waiting;
1395 (void) event_del(&ns->event);
1396 event_assign(&ns->event, ns->base->event_base,
1397 ns->socket, EV_READ | (waiting ? EV_WRITE : 0) | EV_PERSIST,
1398 nameserver_ready_callback, ns);
1399 if (event_add(&ns->event, NULL) < 0) {
1401 log(EVDNS_LOG_WARN, "Error from libevent when adding event for %s",
1402 evutil_format_sockaddr_port(
1403 (struct sockaddr *)&ns->address,
1404 addrbuf, sizeof(addrbuf)));
1409 /* a callback function. Called by libevent when the kernel says that */
1410 /* a nameserver socket is ready for writing or reading */
1412 nameserver_ready_callback(evutil_socket_t fd, short events, void *arg) {
1413 struct nameserver *ns = (struct nameserver *) arg;
1416 EVDNS_LOCK(ns->base);
1417 if (events & EV_WRITE) {
1419 if (!evdns_transmit(ns->base)) {
1420 nameserver_write_waiting(ns, 0);
1423 if (events & EV_READ) {
1424 nameserver_read(ns);
1426 EVDNS_UNLOCK(ns->base);
1429 /* a callback function. Called by libevent when the kernel says that */
1430 /* a server socket is ready for writing or reading. */
1432 server_port_ready_callback(evutil_socket_t fd, short events, void *arg) {
1433 struct evdns_server_port *port = (struct evdns_server_port *) arg;
1437 if (events & EV_WRITE) {
1439 server_port_flush(port);
1441 if (events & EV_READ) {
1442 server_port_read(port);
1447 /* This is an inefficient representation; only use it via the dnslabel_table_*
1448 * functions, so that is can be safely replaced with something smarter later. */
1449 #define MAX_LABELS 128
1450 /* Structures used to implement name compression */
1451 struct dnslabel_entry { char *v; off_t pos; };
1452 struct dnslabel_table {
1453 int n_labels; /* number of current entries */
1454 /* map from name to position in message */
1455 struct dnslabel_entry labels[MAX_LABELS];
1458 /* Initialize dnslabel_table. */
1460 dnslabel_table_init(struct dnslabel_table *table)
1462 table->n_labels = 0;
1465 /* Free all storage held by table, but not the table itself. */
1467 dnslabel_clear(struct dnslabel_table *table)
1470 for (i = 0; i < table->n_labels; ++i)
1471 mm_free(table->labels[i].v);
1472 table->n_labels = 0;
1475 /* return the position of the label in the current message, or -1 if the label */
1476 /* hasn't been used yet. */
1478 dnslabel_table_get_pos(const struct dnslabel_table *table, const char *label)
1481 for (i = 0; i < table->n_labels; ++i) {
1482 if (!strcmp(label, table->labels[i].v))
1483 return table->labels[i].pos;
1488 /* remember that we've used the label at position pos */
1490 dnslabel_table_add(struct dnslabel_table *table, const char *label, off_t pos)
1494 if (table->n_labels == MAX_LABELS)
1496 v = mm_strdup(label);
1499 p = table->n_labels++;
1500 table->labels[p].v = v;
1501 table->labels[p].pos = pos;
1506 /* Converts a string to a length-prefixed set of DNS labels, starting */
1507 /* at buf[j]. name and buf must not overlap. name_len should be the length */
1508 /* of name. table is optional, and is used for compression. */
1510 /* Input: abc.def */
1511 /* Output: <3>abc<3>def<0> */
1513 /* Returns the first index after the encoded name, or negative on error. */
1514 /* -1 label was > 63 bytes */
1515 /* -2 name too long to fit in buffer. */
1518 dnsname_to_labels(u8 *const buf, size_t buf_len, off_t j,
1519 const char *name, const size_t name_len,
1520 struct dnslabel_table *table) {
1521 const char *end = name + name_len;
1525 #define APPEND16(x) do { \
1526 if (j + 2 > (off_t)buf_len) \
1529 memcpy(buf + j, &_t, 2); \
1532 #define APPEND32(x) do { \
1533 if (j + 4 > (off_t)buf_len) \
1536 memcpy(buf + j, &_t32, 4); \
1540 if (name_len > 255) return -2;
1543 const char *const start = name;
1544 if (table && (ref = dnslabel_table_get_pos(table, name)) >= 0) {
1545 APPEND16(ref | 0xc000);
1548 name = strchr(name, '.');
1550 const size_t label_len = end - start;
1551 if (label_len > 63) return -1;
1552 if ((size_t)(j+label_len+1) > buf_len) return -2;
1553 if (table) dnslabel_table_add(table, start, j);
1554 buf[j++] = (ev_uint8_t)label_len;
1556 memcpy(buf + j, start, label_len);
1557 j += (int) label_len;
1560 /* append length of the label. */
1561 const size_t label_len = name - start;
1562 if (label_len > 63) return -1;
1563 if ((size_t)(j+label_len+1) > buf_len) return -2;
1564 if (table) dnslabel_table_add(table, start, j);
1565 buf[j++] = (ev_uint8_t)label_len;
1567 memcpy(buf + j, start, label_len);
1568 j += (int) label_len;
1569 /* hop over the '.' */
1574 /* the labels must be terminated by a 0. */
1575 /* It's possible that the name ended in a . */
1576 /* in which case the zero is already there */
1577 if (!j || buf[j-1]) buf[j++] = 0;
1583 /* Finds the length of a dns request for a DNS name of the given */
1584 /* length. The actual request may be smaller than the value returned */
1587 evdns_request_len(const size_t name_len) {
1588 return 96 + /* length of the DNS standard header */
1590 4; /* space for the resource type */
1593 /* build a dns request packet into buf. buf should be at least as long */
1594 /* as evdns_request_len told you it should be. */
1596 /* Returns the amount of space used. Negative on error. */
1598 evdns_request_data_build(const char *const name, const size_t name_len,
1599 const u16 trans_id, const u16 type, const u16 class,
1600 u8 *const buf, size_t buf_len) {
1601 off_t j = 0; /* current offset into buf */
1602 u16 _t; /* used by the macros */
1605 APPEND16(0x0100); /* standard query, recusion needed */
1606 APPEND16(1); /* one question */
1607 APPEND16(0); /* no answers */
1608 APPEND16(0); /* no authority */
1609 APPEND16(0); /* no additional */
1611 j = dnsname_to_labels(buf, buf_len, j, name, name_len, NULL);
1624 /* exported function */
1625 struct evdns_server_port *
1626 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)
1628 struct evdns_server_port *port;
1630 return NULL; /* flags not yet implemented */
1631 if (!(port = mm_malloc(sizeof(struct evdns_server_port))))
1633 memset(port, 0, sizeof(struct evdns_server_port));
1636 port->socket = socket;
1640 port->user_callback = cb;
1641 port->user_data = user_data;
1642 port->pending_replies = NULL;
1643 port->event_base = base;
1645 event_assign(&port->event, port->event_base,
1646 port->socket, EV_READ | EV_PERSIST,
1647 server_port_ready_callback, port);
1648 if (event_add(&port->event, NULL) < 0) {
1652 EVTHREAD_ALLOC_LOCK(port->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
1656 struct evdns_server_port *
1657 evdns_add_server_port(evutil_socket_t socket, int flags, evdns_request_callback_fn_type cb, void *user_data)
1659 return evdns_add_server_port_with_base(NULL, socket, flags, cb, user_data);
1662 /* exported function */
1664 evdns_close_server_port(struct evdns_server_port *port)
1667 if (--port->refcnt == 0) {
1669 server_port_free(port);
1675 /* exported function */
1677 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)
1679 struct server_request *req = TO_SERVER_REQUEST(_req);
1680 struct server_reply_item **itemp, *item;
1684 EVDNS_LOCK(req->port);
1685 if (req->response) /* have we already answered? */
1689 case EVDNS_ANSWER_SECTION:
1690 itemp = &req->answer;
1691 countp = &req->n_answer;
1693 case EVDNS_AUTHORITY_SECTION:
1694 itemp = &req->authority;
1695 countp = &req->n_authority;
1697 case EVDNS_ADDITIONAL_SECTION:
1698 itemp = &req->additional;
1699 countp = &req->n_additional;
1705 itemp = &((*itemp)->next);
1707 item = mm_malloc(sizeof(struct server_reply_item));
1711 if (!(item->name = mm_strdup(name))) {
1716 item->dns_question_class = class;
1718 item->is_name = is_name != 0;
1722 if (item->is_name) {
1723 if (!(item->data = mm_strdup(data))) {
1724 mm_free(item->name);
1728 item->datalen = (u16)-1;
1730 if (!(item->data = mm_malloc(datalen))) {
1731 mm_free(item->name);
1735 item->datalen = datalen;
1736 memcpy(item->data, data, datalen);
1744 EVDNS_UNLOCK(req->port);
1748 /* exported function */
1750 evdns_server_request_add_a_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl)
1752 return evdns_server_request_add_reply(
1753 req, EVDNS_ANSWER_SECTION, name, TYPE_A, CLASS_INET,
1754 ttl, n*4, 0, addrs);
1757 /* exported function */
1759 evdns_server_request_add_aaaa_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl)
1761 return evdns_server_request_add_reply(
1762 req, EVDNS_ANSWER_SECTION, name, TYPE_AAAA, CLASS_INET,
1763 ttl, n*16, 0, addrs);
1766 /* exported function */
1768 evdns_server_request_add_ptr_reply(struct evdns_server_request *req, struct in_addr *in, const char *inaddr_name, const char *hostname, int ttl)
1772 if (in && inaddr_name)
1774 else if (!in && !inaddr_name)
1777 a = ntohl(in->s_addr);
1778 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa",
1779 (int)(u8)((a )&0xff),
1780 (int)(u8)((a>>8 )&0xff),
1781 (int)(u8)((a>>16)&0xff),
1782 (int)(u8)((a>>24)&0xff));
1785 return evdns_server_request_add_reply(
1786 req, EVDNS_ANSWER_SECTION, inaddr_name, TYPE_PTR, CLASS_INET,
1787 ttl, -1, 1, hostname);
1790 /* exported function */
1792 evdns_server_request_add_cname_reply(struct evdns_server_request *req, const char *name, const char *cname, int ttl)
1794 return evdns_server_request_add_reply(
1795 req, EVDNS_ANSWER_SECTION, name, TYPE_CNAME, CLASS_INET,
1799 /* exported function */
1801 evdns_server_request_set_flags(struct evdns_server_request *exreq, int flags)
1803 struct server_request *req = TO_SERVER_REQUEST(exreq);
1804 req->base.flags &= ~(EVDNS_FLAGS_AA|EVDNS_FLAGS_RD);
1805 req->base.flags |= flags;
1809 evdns_server_request_format_response(struct server_request *req, int err)
1811 unsigned char buf[1500];
1812 size_t buf_len = sizeof(buf);
1818 struct dnslabel_table table;
1820 if (err < 0 || err > 15) return -1;
1822 /* Set response bit and error code; copy OPCODE and RD fields from
1823 * question; copy RA and AA if set by caller. */
1824 flags = req->base.flags;
1825 flags |= (0x8000 | err);
1827 dnslabel_table_init(&table);
1828 APPEND16(req->trans_id);
1830 APPEND16(req->base.nquestions);
1831 APPEND16(req->n_answer);
1832 APPEND16(req->n_authority);
1833 APPEND16(req->n_additional);
1835 /* Add questions. */
1836 for (i=0; i < req->base.nquestions; ++i) {
1837 const char *s = req->base.questions[i]->name;
1838 j = dnsname_to_labels(buf, buf_len, j, s, strlen(s), &table);
1840 dnslabel_clear(&table);
1843 APPEND16(req->base.questions[i]->type);
1844 APPEND16(req->base.questions[i]->dns_question_class);
1847 /* Add answer, authority, and additional sections. */
1848 for (i=0; i<3; ++i) {
1849 struct server_reply_item *item;
1853 item = req->authority;
1855 item = req->additional;
1857 r = dnsname_to_labels(buf, buf_len, j, item->name, strlen(item->name), &table);
1862 APPEND16(item->type);
1863 APPEND16(item->dns_question_class);
1864 APPEND32(item->ttl);
1865 if (item->is_name) {
1866 off_t len_idx = j, name_start;
1869 r = dnsname_to_labels(buf, buf_len, j, item->data, strlen(item->data), &table);
1873 _t = htons( (short) (j-name_start) );
1874 memcpy(buf+len_idx, &_t, 2);
1876 APPEND16(item->datalen);
1877 if (j+item->datalen > (off_t)buf_len)
1879 memcpy(buf+j, item->data, item->datalen);
1889 buf[2] |= 0x02; /* set the truncated bit. */
1892 req->response_len = j;
1894 if (!(req->response = mm_malloc(req->response_len))) {
1895 server_request_free_answers(req);
1896 dnslabel_clear(&table);
1899 memcpy(req->response, buf, req->response_len);
1900 server_request_free_answers(req);
1901 dnslabel_clear(&table);
1905 /* exported function */
1907 evdns_server_request_respond(struct evdns_server_request *_req, int err)
1909 struct server_request *req = TO_SERVER_REQUEST(_req);
1910 struct evdns_server_port *port = req->port;
1914 if (!req->response) {
1915 if ((r = evdns_server_request_format_response(req, err))<0)
1919 r = sendto(port->socket, req->response, (int)req->response_len, 0,
1920 (struct sockaddr*) &req->addr, (ev_socklen_t)req->addrlen);
1922 int sock_err = evutil_socket_geterror(port->socket);
1923 if (EVUTIL_ERR_RW_RETRIABLE(sock_err))
1926 if (port->pending_replies) {
1927 req->prev_pending = port->pending_replies->prev_pending;
1928 req->next_pending = port->pending_replies;
1929 req->prev_pending->next_pending =
1930 req->next_pending->prev_pending = req;
1932 req->prev_pending = req->next_pending = req;
1933 port->pending_replies = req;
1936 (void) event_del(&port->event);
1937 event_assign(&port->event, port->event_base, port->socket, (port->closing?0:EV_READ) | EV_WRITE | EV_PERSIST, server_port_ready_callback, port);
1939 if (event_add(&port->event, NULL) < 0) {
1940 log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server");
1948 if (server_request_free(req)) {
1953 if (port->pending_replies)
1954 server_port_flush(port);
1962 /* Free all storage held by RRs in req. */
1964 server_request_free_answers(struct server_request *req)
1966 struct server_reply_item *victim, *next, **list;
1968 for (i = 0; i < 3; ++i) {
1970 list = &req->answer;
1972 list = &req->authority;
1974 list = &req->additional;
1978 next = victim->next;
1979 mm_free(victim->name);
1981 mm_free(victim->data);
1989 /* Free all storage held by req, and remove links to it. */
1990 /* return true iff we just wound up freeing the server_port. */
1992 server_request_free(struct server_request *req)
1994 int i, rc=1, lock=0;
1995 if (req->base.questions) {
1996 for (i = 0; i < req->base.nquestions; ++i)
1997 mm_free(req->base.questions[i]);
1998 mm_free(req->base.questions);
2002 EVDNS_LOCK(req->port);
2004 if (req->port->pending_replies == req) {
2005 if (req->next_pending && req->next_pending != req)
2006 req->port->pending_replies = req->next_pending;
2008 req->port->pending_replies = NULL;
2010 rc = --req->port->refcnt;
2013 if (req->response) {
2014 mm_free(req->response);
2017 server_request_free_answers(req);
2019 if (req->next_pending && req->next_pending != req) {
2020 req->next_pending->prev_pending = req->prev_pending;
2021 req->prev_pending->next_pending = req->next_pending;
2025 EVDNS_UNLOCK(req->port); /* ????? nickm */
2026 server_port_free(req->port);
2031 EVDNS_UNLOCK(req->port);
2036 /* Free all storage held by an evdns_server_port. Only called when */
2038 server_port_free(struct evdns_server_port *port)
2040 EVUTIL_ASSERT(port);
2041 EVUTIL_ASSERT(!port->refcnt);
2042 EVUTIL_ASSERT(!port->pending_replies);
2043 if (port->socket > 0) {
2044 evutil_closesocket(port->socket);
2047 (void) event_del(&port->event);
2048 event_debug_unassign(&port->event);
2049 EVTHREAD_FREE_LOCK(port->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
2053 /* exported function */
2055 evdns_server_request_drop(struct evdns_server_request *_req)
2057 struct server_request *req = TO_SERVER_REQUEST(_req);
2058 server_request_free(req);
2062 /* exported function */
2064 evdns_server_request_get_requesting_addr(struct evdns_server_request *_req, struct sockaddr *sa, int addr_len)
2066 struct server_request *req = TO_SERVER_REQUEST(_req);
2067 if (addr_len < (int)req->addrlen)
2069 memcpy(sa, &(req->addr), req->addrlen);
2070 return req->addrlen;
2076 /* this is a libevent callback function which is called when a request */
2077 /* has timed out. */
2079 evdns_request_timeout_callback(evutil_socket_t fd, short events, void *arg) {
2080 struct request *const req = (struct request *) arg;
2081 #ifndef _EVENT_DISABLE_THREAD_SUPPORT
2082 struct evdns_base *base = req->base;
2087 log(EVDNS_LOG_DEBUG, "Request %p timed out", arg);
2090 req->ns->timedout++;
2091 if (req->ns->timedout > req->base->global_max_nameserver_timeout) {
2092 req->ns->timedout = 0;
2093 nameserver_failed(req->ns, "request timed out.");
2096 if (req->tx_count >= req->base->global_max_retransmits) {
2097 /* this request has failed */
2098 reply_schedule_callback(req, 0, DNS_ERR_TIMEOUT, NULL);
2099 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1);
2102 (void) evtimer_del(&req->timeout_event);
2103 evdns_request_transmit(req);
2108 /* try to send a request to a given server. */
2112 /* 1 temporary failure */
2113 /* 2 other failure */
2115 evdns_request_transmit_to(struct request *req, struct nameserver *server) {
2117 ASSERT_LOCKED(req->base);
2118 ASSERT_VALID_REQUEST(req);
2119 r = sendto(server->socket, (void*)req->request, req->request_len, 0,
2120 (struct sockaddr *)&server->address, server->addrlen);
2122 int err = evutil_socket_geterror(server->socket);
2123 if (EVUTIL_ERR_RW_RETRIABLE(err))
2125 nameserver_failed(req->ns, evutil_socket_error_to_string(err));
2127 } else if (r != (int)req->request_len) {
2128 return 1; /* short write */
2134 /* try to send a request, updating the fields of the request */
2141 evdns_request_transmit(struct request *req) {
2144 ASSERT_LOCKED(req->base);
2145 ASSERT_VALID_REQUEST(req);
2146 /* if we fail to send this packet then this flag marks it */
2147 /* for evdns_transmit */
2148 req->transmit_me = 1;
2149 EVUTIL_ASSERT(req->trans_id != 0xffff);
2151 if (req->ns->choked) {
2152 /* don't bother trying to write to a socket */
2153 /* which we have had EAGAIN from */
2157 r = evdns_request_transmit_to(req, req->ns);
2161 req->ns->choked = 1;
2162 nameserver_write_waiting(req->ns, 1);
2165 /* failed to transmit the request entirely. */
2167 /* fall through: we'll set a timeout, which will time out,
2168 * and make us retransmit the request anyway. */
2171 log(EVDNS_LOG_DEBUG,
2172 "Setting timeout for request %p", req);
2173 if (evtimer_add(&req->timeout_event, &req->base->global_timeout) < 0) {
2175 "Error from libevent when adding timer for request %p",
2180 req->transmit_me = 0;
2186 nameserver_probe_callback(int result, char type, int count, int ttl, void *addresses, void *arg) {
2187 struct nameserver *const ns = (struct nameserver *) arg;
2193 EVDNS_LOCK(ns->base);
2194 ns->probe_request = NULL;
2195 if (result == DNS_ERR_CANCEL) {
2196 /* We canceled this request because the nameserver came up
2197 * for some other reason. Do not change our opinion about
2198 * the nameserver. */
2199 } else if (result == DNS_ERR_NONE || result == DNS_ERR_NOTEXIST) {
2200 /* this is a good reply */
2203 nameserver_probe_failed(ns);
2205 EVDNS_UNLOCK(ns->base);
2209 nameserver_send_probe(struct nameserver *const ns) {
2210 struct evdns_request *handle;
2211 struct request *req;
2213 /* here we need to send a probe to a given nameserver */
2214 /* in the hope that it is up now. */
2216 ASSERT_LOCKED(ns->base);
2217 log(EVDNS_LOG_DEBUG, "Sending probe to %s",
2218 evutil_format_sockaddr_port(
2219 (struct sockaddr *)&ns->address,
2220 addrbuf, sizeof(addrbuf)));
2221 handle = mm_calloc(1, sizeof(*handle));
2222 if (!handle) return;
2223 req = request_new(ns->base, handle, TYPE_A, "google.com", DNS_QUERY_NO_SEARCH, nameserver_probe_callback, ns);
2225 ns->probe_request = handle;
2226 /* we force this into the inflight queue no matter what */
2227 request_trans_id_set(req, transaction_id_pick(ns->base));
2229 request_submit(req);
2233 /* 0 didn't try to transmit anything */
2234 /* 1 tried to transmit something */
2236 evdns_transmit(struct evdns_base *base) {
2237 char did_try_to_transmit = 0;
2240 ASSERT_LOCKED(base);
2241 for (i = 0; i < base->n_req_heads; ++i) {
2242 if (base->req_heads[i]) {
2243 struct request *const started_at = base->req_heads[i], *req = started_at;
2244 /* first transmit all the requests which are currently waiting */
2246 if (req->transmit_me) {
2247 did_try_to_transmit = 1;
2248 evdns_request_transmit(req);
2252 } while (req != started_at);
2256 return did_try_to_transmit;
2259 /* exported function */
2261 evdns_base_count_nameservers(struct evdns_base *base)
2263 const struct nameserver *server;
2267 server = base->server_head;
2272 server = server->next;
2273 } while (server != base->server_head);
2280 evdns_count_nameservers(void)
2282 return evdns_base_count_nameservers(current_base);
2285 /* exported function */
2287 evdns_base_clear_nameservers_and_suspend(struct evdns_base *base)
2289 struct nameserver *server, *started_at;
2293 server = base->server_head;
2294 started_at = base->server_head;
2300 struct nameserver *next = server->next;
2301 (void) event_del(&server->event);
2302 if (evtimer_initialized(&server->timeout_event))
2303 (void) evtimer_del(&server->timeout_event);
2304 if (server->socket >= 0)
2305 evutil_closesocket(server->socket);
2307 if (next == started_at)
2311 base->server_head = NULL;
2312 base->global_good_nameservers = 0;
2314 for (i = 0; i < base->n_req_heads; ++i) {
2315 struct request *req, *req_started_at;
2316 req = req_started_at = base->req_heads[i];
2318 struct request *next = req->next;
2319 req->tx_count = req->reissue_count = 0;
2321 /* ???? What to do about searches? */
2322 (void) evtimer_del(&req->timeout_event);
2324 req->transmit_me = 0;
2326 base->global_requests_waiting++;
2327 evdns_request_insert(req, &base->req_waiting_head);
2328 /* We want to insert these suspended elements at the front of
2329 * the waiting queue, since they were pending before any of
2330 * the waiting entries were added. This is a circular list,
2331 * so we can just shift the start back by one.*/
2332 base->req_waiting_head = base->req_waiting_head->prev;
2334 if (next == req_started_at)
2338 base->req_heads[i] = NULL;
2341 base->global_requests_inflight = 0;
2348 evdns_clear_nameservers_and_suspend(void)
2350 return evdns_base_clear_nameservers_and_suspend(current_base);
2354 /* exported function */
2356 evdns_base_resume(struct evdns_base *base)
2359 evdns_requests_pump_waiting_queue(base);
2367 return evdns_base_resume(current_base);
2371 _evdns_nameserver_add_impl(struct evdns_base *base, const struct sockaddr *address, int addrlen) {
2372 /* first check to see if we already have this nameserver */
2374 const struct nameserver *server = base->server_head, *const started_at = base->server_head;
2375 struct nameserver *ns;
2379 ASSERT_LOCKED(base);
2382 if (!evutil_sockaddr_cmp((struct sockaddr*)&server->address, address, 1)) return 3;
2383 server = server->next;
2384 } while (server != started_at);
2386 if (addrlen > (int)sizeof(ns->address)) {
2387 log(EVDNS_LOG_DEBUG, "Addrlen %d too long.", (int)addrlen);
2391 ns = (struct nameserver *) mm_malloc(sizeof(struct nameserver));
2394 memset(ns, 0, sizeof(struct nameserver));
2397 evtimer_assign(&ns->timeout_event, ns->base->event_base, nameserver_prod_callback, ns);
2399 ns->socket = socket(address->sa_family, SOCK_DGRAM, 0);
2400 if (ns->socket < 0) { err = 1; goto out1; }
2401 evutil_make_socket_closeonexec(ns->socket);
2402 evutil_make_socket_nonblocking(ns->socket);
2404 if (base->global_outgoing_addrlen &&
2405 !evutil_sockaddr_is_loopback(address)) {
2406 if (bind(ns->socket,
2407 (struct sockaddr*)&base->global_outgoing_address,
2408 base->global_outgoing_addrlen) < 0) {
2409 log(EVDNS_LOG_WARN,"Couldn't bind to outgoing address");
2415 memcpy(&ns->address, address, addrlen);
2416 ns->addrlen = addrlen;
2418 event_assign(&ns->event, ns->base->event_base, ns->socket, EV_READ | EV_PERSIST, nameserver_ready_callback, ns);
2419 if (event_add(&ns->event, NULL) < 0) {
2424 log(EVDNS_LOG_DEBUG, "Added nameserver %s",
2425 evutil_format_sockaddr_port(address, addrbuf, sizeof(addrbuf)));
2427 /* insert this nameserver into the list of them */
2428 if (!base->server_head) {
2429 ns->next = ns->prev = ns;
2430 base->server_head = ns;
2432 ns->next = base->server_head->next;
2433 ns->prev = base->server_head;
2434 base->server_head->next = ns;
2435 if (base->server_head->prev == base->server_head) {
2436 base->server_head->prev = ns;
2440 base->global_good_nameservers++;
2445 evutil_closesocket(ns->socket);
2447 event_debug_unassign(&ns->event);
2449 log(EVDNS_LOG_WARN, "Unable to add nameserver %s: error %d",
2450 evutil_format_sockaddr_port(address, addrbuf, sizeof(addrbuf)), err);
2454 /* exported function */
2456 evdns_base_nameserver_add(struct evdns_base *base, unsigned long int address)
2458 struct sockaddr_in sin;
2460 sin.sin_addr.s_addr = address;
2461 sin.sin_port = htons(53);
2462 sin.sin_family = AF_INET;
2464 res = _evdns_nameserver_add_impl(base, (struct sockaddr*)&sin, sizeof(sin));
2470 evdns_nameserver_add(unsigned long int address) {
2472 current_base = evdns_base_new(NULL, 0);
2473 return evdns_base_nameserver_add(current_base, address);
2477 sockaddr_setport(struct sockaddr *sa, ev_uint16_t port)
2479 if (sa->sa_family == AF_INET) {
2480 ((struct sockaddr_in *)sa)->sin_port = htons(port);
2481 } else if (sa->sa_family == AF_INET6) {
2482 ((struct sockaddr_in6 *)sa)->sin6_port = htons(port);
2487 sockaddr_getport(struct sockaddr *sa)
2489 if (sa->sa_family == AF_INET) {
2490 return ntohs(((struct sockaddr_in *)sa)->sin_port);
2491 } else if (sa->sa_family == AF_INET6) {
2492 return ntohs(((struct sockaddr_in6 *)sa)->sin6_port);
2498 /* exported function */
2500 evdns_base_nameserver_ip_add(struct evdns_base *base, const char *ip_as_string) {
2501 struct sockaddr_storage ss;
2502 struct sockaddr *sa;
2503 int len = sizeof(ss);
2505 if (evutil_parse_sockaddr_port(ip_as_string, (struct sockaddr *)&ss,
2507 log(EVDNS_LOG_WARN, "Unable to parse nameserver address %s",
2511 sa = (struct sockaddr *) &ss;
2512 if (sockaddr_getport(sa) == 0)
2513 sockaddr_setport(sa, 53);
2516 res = _evdns_nameserver_add_impl(base, sa, len);
2522 evdns_nameserver_ip_add(const char *ip_as_string) {
2524 current_base = evdns_base_new(NULL, 0);
2525 return evdns_base_nameserver_ip_add(current_base, ip_as_string);
2529 evdns_base_nameserver_sockaddr_add(struct evdns_base *base,
2530 const struct sockaddr *sa, ev_socklen_t len, unsigned flags)
2533 EVUTIL_ASSERT(base);
2535 res = _evdns_nameserver_add_impl(base, sa, len);
2540 /* remove from the queue */
2542 evdns_request_remove(struct request *req, struct request **head)
2544 ASSERT_LOCKED(req->base);
2545 ASSERT_VALID_REQUEST(req);
2549 struct request *ptr;
2551 EVUTIL_ASSERT(*head != NULL);
2560 } while (ptr != *head);
2561 EVUTIL_ASSERT(found);
2563 EVUTIL_ASSERT(req->next);
2567 if (req->next == req) {
2568 /* only item in the list */
2571 req->next->prev = req->prev;
2572 req->prev->next = req->next;
2573 if (*head == req) *head = req->next;
2575 req->next = req->prev = NULL;
2578 /* insert into the tail of the queue */
2580 evdns_request_insert(struct request *req, struct request **head) {
2581 ASSERT_LOCKED(req->base);
2582 ASSERT_VALID_REQUEST(req);
2585 req->next = req->prev = req;
2589 req->prev = (*head)->prev;
2590 req->prev->next = req;
2592 (*head)->prev = req;
2596 string_num_dots(const char *s) {
2598 while ((s = strchr(s, '.'))) {
2605 static struct request *
2606 request_new(struct evdns_base *base, struct evdns_request *handle, int type,
2607 const char *name, int flags, evdns_callback_type callback,
2610 const char issuing_now =
2611 (base->global_requests_inflight < base->global_max_requests_inflight) ? 1 : 0;
2613 const size_t name_len = strlen(name);
2614 const size_t request_max_len = evdns_request_len(name_len);
2615 const u16 trans_id = issuing_now ? transaction_id_pick(base) : 0xffff;
2616 /* the request data is alloced in a single block with the header */
2617 struct request *const req =
2618 mm_malloc(sizeof(struct request) + request_max_len);
2623 ASSERT_LOCKED(base);
2625 if (!req) return NULL;
2627 if (name_len >= sizeof(namebuf)) {
2632 memset(req, 0, sizeof(struct request));
2635 evtimer_assign(&req->timeout_event, req->base->event_base, evdns_request_timeout_callback, req);
2637 if (base->global_randomize_case) {
2639 char randbits[(sizeof(namebuf)+7)/8];
2640 strlcpy(namebuf, name, sizeof(namebuf));
2641 evutil_secure_rng_get_bytes(randbits, (name_len+7)/8);
2642 for (i = 0; i < name_len; ++i) {
2643 if (EVUTIL_ISALPHA(namebuf[i])) {
2644 if ((randbits[i >> 3] & (1<<(i & 7))))
2647 namebuf[i] &= ~0x20;
2653 /* request data lives just after the header */
2654 req->request = ((u8 *) req) + sizeof(struct request);
2655 /* denotes that the request data shouldn't be free()ed */
2656 req->request_appended = 1;
2657 rlen = evdns_request_data_build(name, name_len, trans_id,
2658 type, CLASS_INET, req->request, request_max_len);
2662 req->request_len = rlen;
2663 req->trans_id = trans_id;
2665 req->request_type = type;
2666 req->user_pointer = user_ptr;
2667 req->user_callback = callback;
2668 req->ns = issuing_now ? nameserver_pick(base) : NULL;
2669 req->next = req->prev = NULL;
2670 req->handle = handle;
2672 handle->current_req = req;
2673 handle->base = base;
2683 request_submit(struct request *const req) {
2684 struct evdns_base *base = req->base;
2685 ASSERT_LOCKED(base);
2686 ASSERT_VALID_REQUEST(req);
2688 /* if it has a nameserver assigned then this is going */
2689 /* straight into the inflight queue */
2690 evdns_request_insert(req, &REQ_HEAD(base, req->trans_id));
2691 base->global_requests_inflight++;
2692 evdns_request_transmit(req);
2694 evdns_request_insert(req, &base->req_waiting_head);
2695 base->global_requests_waiting++;
2699 /* exported function */
2701 evdns_cancel_request(struct evdns_base *base, struct evdns_request *handle)
2703 struct request *req;
2705 if (!handle->current_req)
2709 /* This redundancy is silly; can we fix it? (Not for 2.0) XXXX */
2710 base = handle->base;
2712 base = handle->current_req->base;
2716 if (handle->pending_cb) {
2721 req = handle->current_req;
2722 ASSERT_VALID_REQUEST(req);
2724 reply_schedule_callback(req, 0, DNS_ERR_CANCEL, NULL);
2726 /* remove from inflight queue */
2727 request_finished(req, &REQ_HEAD(base, req->trans_id), 1);
2729 /* remove from global_waiting head */
2730 request_finished(req, &base->req_waiting_head, 1);
2735 /* exported function */
2736 struct evdns_request *
2737 evdns_base_resolve_ipv4(struct evdns_base *base, const char *name, int flags,
2738 evdns_callback_type callback, void *ptr) {
2739 struct evdns_request *handle;
2740 struct request *req;
2741 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name);
2742 handle = mm_calloc(1, sizeof(*handle));
2746 if (flags & DNS_QUERY_NO_SEARCH) {
2748 request_new(base, handle, TYPE_A, name, flags,
2751 request_submit(req);
2753 search_request_new(base, handle, TYPE_A, name, flags,
2756 if (handle->current_req == NULL) {
2764 int evdns_resolve_ipv4(const char *name, int flags,
2765 evdns_callback_type callback, void *ptr)
2767 return evdns_base_resolve_ipv4(current_base, name, flags, callback, ptr)
2772 /* exported function */
2773 struct evdns_request *
2774 evdns_base_resolve_ipv6(struct evdns_base *base,
2775 const char *name, int flags,
2776 evdns_callback_type callback, void *ptr)
2778 struct evdns_request *handle;
2779 struct request *req;
2780 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name);
2781 handle = mm_calloc(1, sizeof(*handle));
2785 if (flags & DNS_QUERY_NO_SEARCH) {
2786 req = request_new(base, handle, TYPE_AAAA, name, flags,
2789 request_submit(req);
2791 search_request_new(base, handle, TYPE_AAAA, name, flags,
2794 if (handle->current_req == NULL) {
2802 int evdns_resolve_ipv6(const char *name, int flags,
2803 evdns_callback_type callback, void *ptr) {
2804 return evdns_base_resolve_ipv6(current_base, name, flags, callback, ptr)
2808 struct evdns_request *
2809 evdns_base_resolve_reverse(struct evdns_base *base, const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) {
2811 struct evdns_request *handle;
2812 struct request *req;
2815 a = ntohl(in->s_addr);
2816 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa",
2817 (int)(u8)((a )&0xff),
2818 (int)(u8)((a>>8 )&0xff),
2819 (int)(u8)((a>>16)&0xff),
2820 (int)(u8)((a>>24)&0xff));
2821 handle = mm_calloc(1, sizeof(*handle));
2824 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf);
2826 req = request_new(base, handle, TYPE_PTR, buf, flags, callback, ptr);
2828 request_submit(req);
2829 if (handle->current_req == NULL) {
2837 int evdns_resolve_reverse(const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) {
2838 return evdns_base_resolve_reverse(current_base, in, flags, callback, ptr)
2842 struct evdns_request *
2843 evdns_base_resolve_reverse_ipv6(struct evdns_base *base, const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) {
2844 /* 32 nybbles, 32 periods, "ip6.arpa", NUL. */
2847 struct evdns_request *handle;
2848 struct request *req;
2852 for (i=15; i >= 0; --i) {
2853 u8 byte = in->s6_addr[i];
2854 *cp++ = "0123456789abcdef"[byte & 0x0f];
2856 *cp++ = "0123456789abcdef"[byte >> 4];
2859 EVUTIL_ASSERT(cp + strlen("ip6.arpa") < buf+sizeof(buf));
2860 memcpy(cp, "ip6.arpa", strlen("ip6.arpa")+1);
2861 handle = mm_calloc(1, sizeof(*handle));
2864 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf);
2866 req = request_new(base, handle, TYPE_PTR, buf, flags, callback, ptr);
2868 request_submit(req);
2869 if (handle->current_req == NULL) {
2877 int evdns_resolve_reverse_ipv6(const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) {
2878 return evdns_base_resolve_reverse_ipv6(current_base, in, flags, callback, ptr)
2882 /* ================================================================= */
2883 /* Search support */
2885 /* the libc resolver has support for searching a number of domains */
2886 /* to find a name. If nothing else then it takes the single domain */
2887 /* from the gethostname() call. */
2889 /* It can also be configured via the domain and search options in a */
2892 /* The ndots option controls how many dots it takes for the resolver */
2893 /* to decide that a name is non-local and so try a raw lookup first. */
2895 struct search_domain {
2897 struct search_domain *next;
2898 /* the text string is appended to this structure */
2901 struct search_state {
2905 struct search_domain *head;
2909 search_state_decref(struct search_state *const state) {
2912 if (!state->refcount) {
2913 struct search_domain *next, *dom;
2914 for (dom = state->head; dom; dom = next) {
2922 static struct search_state *
2923 search_state_new(void) {
2924 struct search_state *state = (struct search_state *) mm_malloc(sizeof(struct search_state));
2925 if (!state) return NULL;
2926 memset(state, 0, sizeof(struct search_state));
2927 state->refcount = 1;
2934 search_postfix_clear(struct evdns_base *base) {
2935 search_state_decref(base->global_search_state);
2937 base->global_search_state = search_state_new();
2940 /* exported function */
2942 evdns_base_search_clear(struct evdns_base *base)
2945 search_postfix_clear(base);
2950 evdns_search_clear(void) {
2951 evdns_base_search_clear(current_base);
2955 search_postfix_add(struct evdns_base *base, const char *domain) {
2957 struct search_domain *sdomain;
2958 while (domain[0] == '.') domain++;
2959 domain_len = strlen(domain);
2961 ASSERT_LOCKED(base);
2962 if (!base->global_search_state) base->global_search_state = search_state_new();
2963 if (!base->global_search_state) return;
2964 base->global_search_state->num_domains++;
2966 sdomain = (struct search_domain *) mm_malloc(sizeof(struct search_domain) + domain_len);
2967 if (!sdomain) return;
2968 memcpy( ((u8 *) sdomain) + sizeof(struct search_domain), domain, domain_len);
2969 sdomain->next = base->global_search_state->head;
2970 sdomain->len = (int) domain_len;
2972 base->global_search_state->head = sdomain;
2975 /* reverse the order of members in the postfix list. This is needed because, */
2976 /* when parsing resolv.conf we push elements in the wrong order */
2978 search_reverse(struct evdns_base *base) {
2979 struct search_domain *cur, *prev = NULL, *next;
2980 ASSERT_LOCKED(base);
2981 cur = base->global_search_state->head;
2989 base->global_search_state->head = prev;
2992 /* exported function */
2994 evdns_base_search_add(struct evdns_base *base, const char *domain) {
2996 search_postfix_add(base, domain);
3000 evdns_search_add(const char *domain) {
3001 evdns_base_search_add(current_base, domain);
3004 /* exported function */
3006 evdns_base_search_ndots_set(struct evdns_base *base, const int ndots) {
3008 if (!base->global_search_state) base->global_search_state = search_state_new();
3009 if (base->global_search_state)
3010 base->global_search_state->ndots = ndots;
3014 evdns_search_ndots_set(const int ndots) {
3015 evdns_base_search_ndots_set(current_base, ndots);
3019 search_set_from_hostname(struct evdns_base *base) {
3020 char hostname[HOST_NAME_MAX + 1], *domainname;
3022 ASSERT_LOCKED(base);
3023 search_postfix_clear(base);
3024 if (gethostname(hostname, sizeof(hostname))) return;
3025 domainname = strchr(hostname, '.');
3026 if (!domainname) return;
3027 search_postfix_add(base, domainname);
3030 /* warning: returns malloced string */
3032 search_make_new(const struct search_state *const state, int n, const char *const base_name) {
3033 const size_t base_len = strlen(base_name);
3034 const char need_to_append_dot = base_name[base_len - 1] == '.' ? 0 : 1;
3035 struct search_domain *dom;
3037 for (dom = state->head; dom; dom = dom->next) {
3039 /* this is the postfix we want */
3040 /* the actual postfix string is kept at the end of the structure */
3041 const u8 *const postfix = ((u8 *) dom) + sizeof(struct search_domain);
3042 const int postfix_len = dom->len;
3043 char *const newname = (char *) mm_malloc(base_len + need_to_append_dot + postfix_len + 1);
3044 if (!newname) return NULL;
3045 memcpy(newname, base_name, base_len);
3046 if (need_to_append_dot) newname[base_len] = '.';
3047 memcpy(newname + base_len + need_to_append_dot, postfix, postfix_len);
3048 newname[base_len + need_to_append_dot + postfix_len] = 0;
3053 /* we ran off the end of the list and still didn't find the requested string */
3055 return NULL; /* unreachable; stops warnings in some compilers. */
3058 static struct request *
3059 search_request_new(struct evdns_base *base, struct evdns_request *handle,
3060 int type, const char *const name, int flags,
3061 evdns_callback_type user_callback, void *user_arg) {
3062 ASSERT_LOCKED(base);
3063 EVUTIL_ASSERT(type == TYPE_A || type == TYPE_AAAA);
3064 EVUTIL_ASSERT(handle->current_req == NULL);
3065 if ( ((flags & DNS_QUERY_NO_SEARCH) == 0) &&
3066 base->global_search_state &&
3067 base->global_search_state->num_domains) {
3068 /* we have some domains to search */
3069 struct request *req;
3070 if (string_num_dots(name) >= base->global_search_state->ndots) {
3071 req = request_new(base, handle, type, name, flags, user_callback, user_arg);
3072 if (!req) return NULL;
3073 handle->search_index = -1;
3075 char *const new_name = search_make_new(base->global_search_state, 0, name);
3076 if (!new_name) return NULL;
3077 req = request_new(base, handle, type, new_name, flags, user_callback, user_arg);
3079 if (!req) return NULL;
3080 handle->search_index = 0;
3082 EVUTIL_ASSERT(handle->search_origname == NULL);
3083 handle->search_origname = mm_strdup(name);
3084 if (handle->search_origname == NULL) {
3085 /* XXX Should we dealloc req? If yes, how? */
3088 handle->search_state = base->global_search_state;
3089 handle->search_flags = flags;
3090 base->global_search_state->refcount++;
3091 request_submit(req);
3094 struct request *const req = request_new(base, handle, type, name, flags, user_callback, user_arg);
3095 if (!req) return NULL;
3096 request_submit(req);
3101 /* this is called when a request has failed to find a name. We need to check */
3102 /* if it is part of a search and, if so, try the next name in the list */
3104 /* 0 another request has been submitted */
3105 /* 1 no more requests needed */
3107 search_try_next(struct evdns_request *const handle) {
3108 struct request *req = handle->current_req;
3109 struct evdns_base *base = req->base;
3110 struct request *newreq;
3111 ASSERT_LOCKED(base);
3112 if (handle->search_state) {
3113 /* it is part of a search */
3115 handle->search_index++;
3116 if (handle->search_index >= handle->search_state->num_domains) {
3117 /* no more postfixes to try, however we may need to try */
3118 /* this name without a postfix */
3119 if (string_num_dots(handle->search_origname) < handle->search_state->ndots) {
3120 /* yep, we need to try it raw */
3121 newreq = request_new(base, NULL, req->request_type, handle->search_origname, handle->search_flags, req->user_callback, req->user_pointer);
3122 log(EVDNS_LOG_DEBUG, "Search: trying raw query %s", handle->search_origname);
3124 search_request_finished(handle);
3131 new_name = search_make_new(handle->search_state, handle->search_index, handle->search_origname);
3132 if (!new_name) return 1;
3133 log(EVDNS_LOG_DEBUG, "Search: now trying %s (%d)", new_name, handle->search_index);
3134 newreq = request_new(base, NULL, req->request_type, new_name, handle->search_flags, req->user_callback, req->user_pointer);
3136 if (!newreq) return 1;
3142 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 0);
3143 handle->current_req = newreq;
3144 newreq->handle = handle;
3145 request_submit(newreq);
3150 search_request_finished(struct evdns_request *const handle) {
3151 ASSERT_LOCKED(handle->current_req->base);
3152 if (handle->search_state) {
3153 search_state_decref(handle->search_state);
3154 handle->search_state = NULL;
3156 if (handle->search_origname) {
3157 mm_free(handle->search_origname);
3158 handle->search_origname = NULL;
3162 /* ================================================================= */
3163 /* Parsing resolv.conf files */
3166 evdns_resolv_set_defaults(struct evdns_base *base, int flags) {
3167 /* if the file isn't found then we assume a local resolver */
3168 ASSERT_LOCKED(base);
3169 if (flags & DNS_OPTION_SEARCH) search_set_from_hostname(base);
3170 if (flags & DNS_OPTION_NAMESERVERS) evdns_base_nameserver_ip_add(base,"127.0.0.1");
3173 #ifndef _EVENT_HAVE_STRTOK_R
3175 strtok_r(char *s, const char *delim, char **state) {
3177 start = cp = s ? s : *state;
3180 while (*cp && !strchr(delim, *cp))
3195 /* helper version of atoi which returns -1 on error */
3197 strtoint(const char *const str)
3200 const int r = strtol(str, &endptr, 10);
3201 if (*endptr) return -1;
3205 /* Parse a number of seconds into a timeval; return -1 on error. */
3207 strtotimeval(const char *const str, struct timeval *out)
3211 d = strtod(str, &endptr);
3212 if (*endptr) return -1;
3213 if (d < 0) return -1;
3214 out->tv_sec = (int) d;
3215 out->tv_usec = (int) ((d - (int) d)*1000000);
3216 if (out->tv_sec == 0 && out->tv_usec < 1000) /* less than 1 msec */
3221 /* helper version of atoi that returns -1 on error and clips to bounds. */
3223 strtoint_clipped(const char *const str, int min, int max)
3225 int r = strtoint(str);
3237 evdns_base_set_max_requests_inflight(struct evdns_base *base, int maxinflight)
3239 int old_n_heads = base->n_req_heads, n_heads;
3240 struct request **old_heads = base->req_heads, **new_heads, *req;
3243 ASSERT_LOCKED(base);
3244 if (maxinflight < 1)
3246 n_heads = (maxinflight+4) / 5;
3247 EVUTIL_ASSERT(n_heads > 0);
3248 new_heads = mm_calloc(n_heads, sizeof(struct request*));
3252 for (i = 0; i < old_n_heads; ++i) {
3253 while (old_heads[i]) {
3255 evdns_request_remove(req, &old_heads[i]);
3256 evdns_request_insert(req, &new_heads[req->trans_id % n_heads]);
3261 base->req_heads = new_heads;
3262 base->n_req_heads = n_heads;
3263 base->global_max_requests_inflight = maxinflight;
3267 /* exported function */
3269 evdns_base_set_option(struct evdns_base *base,
3270 const char *option, const char *val)
3274 res = evdns_base_set_option_impl(base, option, val, DNS_OPTIONS_ALL);
3280 str_matches_option(const char *s1, const char *optionname)
3282 /* Option names are given as "option:" We accept either 'option' in
3283 * s1, or 'option:randomjunk'. The latter form is to implement the
3284 * resolv.conf parser. */
3285 size_t optlen = strlen(optionname);
3286 size_t slen = strlen(s1);
3287 if (slen == optlen || slen == optlen - 1)
3288 return !strncmp(s1, optionname, slen);
3289 else if (slen > optlen)
3290 return !strncmp(s1, optionname, optlen);
3296 evdns_base_set_option_impl(struct evdns_base *base,
3297 const char *option, const char *val, int flags)
3299 ASSERT_LOCKED(base);
3300 if (str_matches_option(option, "ndots:")) {
3301 const int ndots = strtoint(val);
3302 if (ndots == -1) return -1;
3303 if (!(flags & DNS_OPTION_SEARCH)) return 0;
3304 log(EVDNS_LOG_DEBUG, "Setting ndots to %d", ndots);
3305 if (!base->global_search_state) base->global_search_state = search_state_new();
3306 if (!base->global_search_state) return -1;
3307 base->global_search_state->ndots = ndots;
3308 } else if (str_matches_option(option, "timeout:")) {
3310 if (strtotimeval(val, &tv) == -1) return -1;
3311 if (!(flags & DNS_OPTION_MISC)) return 0;
3312 log(EVDNS_LOG_DEBUG, "Setting timeout to %s", val);
3313 memcpy(&base->global_timeout, &tv, sizeof(struct timeval));
3314 } else if (str_matches_option(option, "getaddrinfo-allow-skew:")) {
3316 if (strtotimeval(val, &tv) == -1) return -1;
3317 if (!(flags & DNS_OPTION_MISC)) return 0;
3318 log(EVDNS_LOG_DEBUG, "Setting getaddrinfo-allow-skew to %s",
3320 memcpy(&base->global_getaddrinfo_allow_skew, &tv,
3321 sizeof(struct timeval));
3322 } else if (str_matches_option(option, "max-timeouts:")) {
3323 const int maxtimeout = strtoint_clipped(val, 1, 255);
3324 if (maxtimeout == -1) return -1;
3325 if (!(flags & DNS_OPTION_MISC)) return 0;
3326 log(EVDNS_LOG_DEBUG, "Setting maximum allowed timeouts to %d",
3328 base->global_max_nameserver_timeout = maxtimeout;
3329 } else if (str_matches_option(option, "max-inflight:")) {
3330 const int maxinflight = strtoint_clipped(val, 1, 65000);
3331 if (maxinflight == -1) return -1;
3332 if (!(flags & DNS_OPTION_MISC)) return 0;
3333 log(EVDNS_LOG_DEBUG, "Setting maximum inflight requests to %d",
3335 evdns_base_set_max_requests_inflight(base, maxinflight);
3336 } else if (str_matches_option(option, "attempts:")) {
3337 int retries = strtoint(val);
3338 if (retries == -1) return -1;
3339 if (retries > 255) retries = 255;
3340 if (!(flags & DNS_OPTION_MISC)) return 0;
3341 log(EVDNS_LOG_DEBUG, "Setting retries to %d", retries);
3342 base->global_max_retransmits = retries;
3343 } else if (str_matches_option(option, "randomize-case:")) {
3344 int randcase = strtoint(val);
3345 if (!(flags & DNS_OPTION_MISC)) return 0;
3346 base->global_randomize_case = randcase;
3347 } else if (str_matches_option(option, "bind-to:")) {
3348 /* XXX This only applies to successive nameservers, not
3349 * to already-configured ones. We might want to fix that. */
3350 int len = sizeof(base->global_outgoing_address);
3351 if (!(flags & DNS_OPTION_NAMESERVERS)) return 0;
3352 if (evutil_parse_sockaddr_port(val,
3353 (struct sockaddr*)&base->global_outgoing_address, &len))
3355 base->global_outgoing_addrlen = len;
3356 } else if (str_matches_option(option, "initial-probe-timeout:")) {
3358 if (strtotimeval(val, &tv) == -1) return -1;
3359 if (tv.tv_sec > 3600)
3361 if (!(flags & DNS_OPTION_MISC)) return 0;
3362 log(EVDNS_LOG_DEBUG, "Setting initial probe timeout to %s",
3364 memcpy(&base->global_nameserver_probe_initial_timeout, &tv,
3371 evdns_set_option(const char *option, const char *val, int flags)
3374 current_base = evdns_base_new(NULL, 0);
3375 return evdns_base_set_option(current_base, option, val);
3379 resolv_conf_parse_line(struct evdns_base *base, char *const start, int flags) {
3381 static const char *const delims = " \t";
3382 #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state)
3385 char *const first_token = strtok_r(start, delims, &strtok_state);
3386 ASSERT_LOCKED(base);
3387 if (!first_token) return;
3389 if (!strcmp(first_token, "nameserver") && (flags & DNS_OPTION_NAMESERVERS)) {
3390 const char *const nameserver = NEXT_TOKEN;
3393 evdns_base_nameserver_ip_add(base, nameserver);
3394 } else if (!strcmp(first_token, "domain") && (flags & DNS_OPTION_SEARCH)) {
3395 const char *const domain = NEXT_TOKEN;
3397 search_postfix_clear(base);
3398 search_postfix_add(base, domain);
3400 } else if (!strcmp(first_token, "search") && (flags & DNS_OPTION_SEARCH)) {
3402 search_postfix_clear(base);
3404 while ((domain = NEXT_TOKEN)) {
3405 search_postfix_add(base, domain);
3407 search_reverse(base);
3408 } else if (!strcmp(first_token, "options")) {
3410 while ((option = NEXT_TOKEN)) {
3411 const char *val = strchr(option, ':');
3412 evdns_base_set_option_impl(base, option, val ? val+1 : "", flags);
3418 /* exported function */
3421 /* 1 failed to open file */
3422 /* 2 failed to stat file */
3423 /* 3 file too large */
3424 /* 4 out of memory */
3425 /* 5 short read from file */
3427 evdns_base_resolv_conf_parse(struct evdns_base *base, int flags, const char *const filename) {
3430 res = evdns_base_resolv_conf_parse_impl(base, flags, filename);
3436 evdns_get_default_hosts_filename(void)
3439 /* Windows is a little coy about where it puts its configuration
3440 * files. Sure, they're _usually_ in C:\windows\system32, but
3441 * there's no reason in principle they couldn't be in
3442 * W:\hoboken chicken emergency\
3444 char path[MAX_PATH+1];
3445 static const char hostfile[] = "\\drivers\\etc\\hosts";
3449 if (! SHGetSpecialFolderPathA(NULL, path, CSIDL_SYSTEM, 0))
3451 len_out = strlen(path)+strlen(hostfile);
3452 path_out = mm_malloc(len_out+1);
3453 evutil_snprintf(path_out, len_out, "%s%s", path, hostfile);
3456 return mm_strdup("/etc/hosts");
3461 evdns_base_resolv_conf_parse_impl(struct evdns_base *base, int flags, const char *const filename) {
3467 log(EVDNS_LOG_DEBUG, "Parsing resolv.conf file %s", filename);
3469 if (flags & DNS_OPTION_HOSTSFILE) {
3470 char *fname = evdns_get_default_hosts_filename();
3471 evdns_base_load_hosts(base, fname);
3476 if ((err = evutil_read_file(filename, &resolv, &n, 0)) < 0) {
3479 evdns_resolv_set_defaults(base, flags);
3488 char *const newline = strchr(start, '\n');
3490 resolv_conf_parse_line(base, start, flags);
3494 resolv_conf_parse_line(base, start, flags);
3495 start = newline + 1;
3499 if (!base->server_head && (flags & DNS_OPTION_NAMESERVERS)) {
3500 /* no nameservers were configured. */
3501 evdns_base_nameserver_ip_add(base, "127.0.0.1");
3504 if (flags & DNS_OPTION_SEARCH && (!base->global_search_state || base->global_search_state->num_domains == 0)) {
3505 search_set_from_hostname(base);
3513 evdns_resolv_conf_parse(int flags, const char *const filename) {
3515 current_base = evdns_base_new(NULL, 0);
3516 return evdns_base_resolv_conf_parse(current_base, flags, filename);
3521 /* Add multiple nameservers from a space-or-comma-separated list. */
3523 evdns_nameserver_ip_add_line(struct evdns_base *base, const char *ips) {
3527 ASSERT_LOCKED(base);
3529 while (isspace(*ips) || *ips == ',' || *ips == '\t')
3532 while (isdigit(*ips) || *ips == '.' || *ips == ':' ||
3533 *ips=='[' || *ips==']')
3535 buf = mm_malloc(ips-addr+1);
3537 memcpy(buf, addr, ips-addr);
3538 buf[ips-addr] = '\0';
3539 r = evdns_base_nameserver_ip_add(base, buf);
3546 typedef DWORD(WINAPI *GetNetworkParams_fn_t)(FIXED_INFO *, DWORD*);
3548 /* Use the windows GetNetworkParams interface in iphlpapi.dll to */
3549 /* figure out what our nameservers are. */
3551 load_nameservers_with_getnetworkparams(struct evdns_base *base)
3553 /* Based on MSDN examples and inspection of c-ares code. */
3556 ULONG size = sizeof(FIXED_INFO);
3558 int status = 0, r, added_any;
3560 GetNetworkParams_fn_t fn;
3562 ASSERT_LOCKED(base);
3563 if (!(handle = evutil_load_windows_system_library(
3564 TEXT("iphlpapi.dll")))) {
3565 log(EVDNS_LOG_WARN, "Could not open iphlpapi.dll");
3569 if (!(fn = (GetNetworkParams_fn_t) GetProcAddress(handle, "GetNetworkParams"))) {
3570 log(EVDNS_LOG_WARN, "Could not get address of function.");
3575 buf = mm_malloc(size);
3576 if (!buf) { status = 4; goto done; }
3578 r = fn(fixed, &size);
3579 if (r != ERROR_SUCCESS && r != ERROR_BUFFER_OVERFLOW) {
3583 if (r != ERROR_SUCCESS) {
3585 buf = mm_malloc(size);
3586 if (!buf) { status = 4; goto done; }
3588 r = fn(fixed, &size);
3589 if (r != ERROR_SUCCESS) {
3590 log(EVDNS_LOG_DEBUG, "fn() failed.");
3596 EVUTIL_ASSERT(fixed);
3598 ns = &(fixed->DnsServerList);
3600 r = evdns_nameserver_ip_add_line(base, ns->IpAddress.String);
3602 log(EVDNS_LOG_DEBUG,"Could not add nameserver %s to list,error: %d",
3603 (ns->IpAddress.String),(int)GetLastError());
3607 log(EVDNS_LOG_DEBUG,"Successfully added %s as nameserver",ns->IpAddress.String);
3614 log(EVDNS_LOG_DEBUG, "No nameservers added.");
3625 FreeLibrary(handle);
3630 config_nameserver_from_reg_key(struct evdns_base *base, HKEY key, const TCHAR *subkey)
3633 DWORD bufsz = 0, type = 0;
3636 ASSERT_LOCKED(base);
3637 if (RegQueryValueEx(key, subkey, 0, &type, NULL, &bufsz)
3640 if (!(buf = mm_malloc(bufsz)))
3643 if (RegQueryValueEx(key, subkey, 0, &type, (LPBYTE)buf, &bufsz)
3644 == ERROR_SUCCESS && bufsz > 1) {
3645 status = evdns_nameserver_ip_add_line(base,buf);
3652 #define SERVICES_KEY TEXT("System\\CurrentControlSet\\Services\\")
3653 #define WIN_NS_9X_KEY SERVICES_KEY TEXT("VxD\\MSTCP")
3654 #define WIN_NS_NT_KEY SERVICES_KEY TEXT("Tcpip\\Parameters")
3657 load_nameservers_from_registry(struct evdns_base *base)
3661 #define TRY(k, name) \
3662 if (!found && config_nameserver_from_reg_key(base,k,TEXT(name)) == 0) { \
3663 log(EVDNS_LOG_DEBUG,"Found nameservers in %s/%s",#k,name); \
3665 } else if (!found) { \
3666 log(EVDNS_LOG_DEBUG,"Didn't find nameservers in %s/%s", \
3670 ASSERT_LOCKED(base);
3672 if (((int)GetVersion()) > 0) { /* NT */
3673 HKEY nt_key = 0, interfaces_key = 0;
3675 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0,
3676 KEY_READ, &nt_key) != ERROR_SUCCESS) {
3677 log(EVDNS_LOG_DEBUG,"Couldn't open nt key, %d",(int)GetLastError());
3680 r = RegOpenKeyEx(nt_key, TEXT("Interfaces"), 0,
3681 KEY_QUERY_VALUE|KEY_ENUMERATE_SUB_KEYS,
3683 if (r != ERROR_SUCCESS) {
3684 log(EVDNS_LOG_DEBUG,"Couldn't open interfaces key, %d",(int)GetLastError());
3687 TRY(nt_key, "NameServer");
3688 TRY(nt_key, "DhcpNameServer");
3689 TRY(interfaces_key, "NameServer");
3690 TRY(interfaces_key, "DhcpNameServer");
3691 RegCloseKey(interfaces_key);
3692 RegCloseKey(nt_key);
3695 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_9X_KEY, 0,
3696 KEY_READ, &win_key) != ERROR_SUCCESS) {
3697 log(EVDNS_LOG_DEBUG, "Couldn't open registry key, %d", (int)GetLastError());
3700 TRY(win_key, "NameServer");
3701 RegCloseKey(win_key);
3705 log(EVDNS_LOG_WARN,"Didn't find any nameservers.");
3708 return found ? 0 : -1;
3713 evdns_base_config_windows_nameservers(struct evdns_base *base)
3718 base = current_base;
3722 if (load_nameservers_with_getnetworkparams(base) == 0) {
3726 r = load_nameservers_from_registry(base);
3728 fname = evdns_get_default_hosts_filename();
3729 evdns_base_load_hosts(base, fname);
3738 evdns_config_windows_nameservers(void)
3740 if (!current_base) {
3741 current_base = evdns_base_new(NULL, 1);
3742 return current_base == NULL ? -1 : 0;
3744 return evdns_base_config_windows_nameservers(current_base);
3750 evdns_base_new(struct event_base *event_base, int initialize_nameservers)
3752 struct evdns_base *base;
3754 if (evutil_secure_rng_init() < 0) {
3755 log(EVDNS_LOG_WARN, "Unable to seed random number generator; "
3760 /* Give the evutil library a hook into its evdns-enabled
3761 * functionality. We can't just call evdns_getaddrinfo directly or
3762 * else libevent-core will depend on libevent-extras. */
3763 evutil_set_evdns_getaddrinfo_fn(evdns_getaddrinfo);
3765 base = mm_malloc(sizeof(struct evdns_base));
3768 memset(base, 0, sizeof(struct evdns_base));
3769 base->req_waiting_head = NULL;
3771 EVTHREAD_ALLOC_LOCK(base->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
3774 /* Set max requests inflight and allocate req_heads. */
3775 base->req_heads = NULL;
3777 evdns_base_set_max_requests_inflight(base, 64);
3779 base->server_head = NULL;
3780 base->event_base = event_base;
3781 base->global_good_nameservers = base->global_requests_inflight =
3782 base->global_requests_waiting = 0;
3784 base->global_timeout.tv_sec = 5;
3785 base->global_timeout.tv_usec = 0;
3786 base->global_max_reissues = 1;
3787 base->global_max_retransmits = 3;
3788 base->global_max_nameserver_timeout = 3;
3789 base->global_search_state = NULL;
3790 base->global_randomize_case = 1;
3791 base->global_getaddrinfo_allow_skew.tv_sec = 3;
3792 base->global_getaddrinfo_allow_skew.tv_usec = 0;
3793 base->global_nameserver_probe_initial_timeout.tv_sec = 10;
3794 base->global_nameserver_probe_initial_timeout.tv_usec = 0;
3796 TAILQ_INIT(&base->hostsdb);
3798 if (initialize_nameservers) {
3801 r = evdns_base_config_windows_nameservers(base);
3803 r = evdns_base_resolv_conf_parse(base, DNS_OPTIONS_ALL, "/etc/resolv.conf");
3806 evdns_base_free_and_unlock(base, 0);
3817 struct evdns_base *base = evdns_base_new(NULL, 1);
3819 current_base = base;
3827 evdns_err_to_string(int err)
3830 case DNS_ERR_NONE: return "no error";
3831 case DNS_ERR_FORMAT: return "misformatted query";
3832 case DNS_ERR_SERVERFAILED: return "server failed";
3833 case DNS_ERR_NOTEXIST: return "name does not exist";
3834 case DNS_ERR_NOTIMPL: return "query not implemented";
3835 case DNS_ERR_REFUSED: return "refused";
3837 case DNS_ERR_TRUNCATED: return "reply truncated or ill-formed";
3838 case DNS_ERR_UNKNOWN: return "unknown";
3839 case DNS_ERR_TIMEOUT: return "request timed out";
3840 case DNS_ERR_SHUTDOWN: return "dns subsystem shut down";
3841 case DNS_ERR_CANCEL: return "dns request canceled";
3842 default: return "[Unknown error code]";
3847 evdns_nameserver_free(struct nameserver *server)
3849 if (server->socket >= 0)
3850 evutil_closesocket(server->socket);
3851 (void) event_del(&server->event);
3852 event_debug_unassign(&server->event);
3853 if (server->state == 0)
3854 (void) event_del(&server->timeout_event);
3855 event_debug_unassign(&server->timeout_event);
3860 evdns_base_free_and_unlock(struct evdns_base *base, int fail_requests)
3862 struct nameserver *server, *server_next;
3863 struct search_domain *dom, *dom_next;
3866 /* Requires that we hold the lock. */
3868 /* TODO(nickm) we might need to refcount here. */
3870 for (i = 0; i < base->n_req_heads; ++i) {
3871 while (base->req_heads[i]) {
3873 reply_schedule_callback(base->req_heads[i], 0, DNS_ERR_SHUTDOWN, NULL);
3874 request_finished(base->req_heads[i], &REQ_HEAD(base, base->req_heads[i]->trans_id), 1);
3877 while (base->req_waiting_head) {
3879 reply_schedule_callback(base->req_waiting_head, 0, DNS_ERR_SHUTDOWN, NULL);
3880 request_finished(base->req_waiting_head, &base->req_waiting_head, 1);
3882 base->global_requests_inflight = base->global_requests_waiting = 0;
3884 for (server = base->server_head; server; server = server_next) {
3885 server_next = server->next;
3886 evdns_nameserver_free(server);
3887 if (server_next == base->server_head)
3890 base->server_head = NULL;
3891 base->global_good_nameservers = 0;
3893 if (base->global_search_state) {
3894 for (dom = base->global_search_state->head; dom; dom = dom_next) {
3895 dom_next = dom->next;
3898 mm_free(base->global_search_state);
3899 base->global_search_state = NULL;
3903 struct hosts_entry *victim;
3904 while ((victim = TAILQ_FIRST(&base->hostsdb))) {
3905 TAILQ_REMOVE(&base->hostsdb, victim, next);
3910 mm_free(base->req_heads);
3913 EVTHREAD_FREE_LOCK(base->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
3919 evdns_base_free(struct evdns_base *base, int fail_requests)
3922 evdns_base_free_and_unlock(base, fail_requests);
3926 evdns_shutdown(int fail_requests)
3929 struct evdns_base *b = current_base;
3930 current_base = NULL;
3931 evdns_base_free(b, fail_requests);
3933 evdns_log_fn = NULL;
3937 evdns_base_parse_hosts_line(struct evdns_base *base, char *line)
3940 static const char *const delims = " \t";
3941 char *const addr = strtok_r(line, delims, &strtok_state);
3942 char *hostname, *hash;
3943 struct sockaddr_storage ss;
3944 int socklen = sizeof(ss);
3945 ASSERT_LOCKED(base);
3947 #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state)
3949 if (!addr || *addr == '#')
3952 memset(&ss, 0, sizeof(ss));
3953 if (evutil_parse_sockaddr_port(addr, (struct sockaddr*)&ss, &socklen)<0)
3955 if (socklen > (int)sizeof(struct sockaddr_in6))
3958 if (sockaddr_getport((struct sockaddr*)&ss))
3961 while ((hostname = NEXT_TOKEN)) {
3962 struct hosts_entry *he;
3964 if ((hash = strchr(hostname, '#'))) {
3965 if (hash == hostname)
3970 namelen = strlen(hostname);
3972 he = mm_calloc(1, sizeof(struct hosts_entry)+namelen);
3975 EVUTIL_ASSERT(socklen <= (int)sizeof(he->addr));
3976 memcpy(&he->addr, &ss, socklen);
3977 memcpy(he->hostname, hostname, namelen+1);
3978 he->addrlen = socklen;
3980 TAILQ_INSERT_TAIL(&base->hostsdb, he, next);
3991 evdns_base_load_hosts_impl(struct evdns_base *base, const char *hosts_fname)
3993 char *str=NULL, *cp, *eol;
3997 ASSERT_LOCKED(base);
3999 if (hosts_fname == NULL ||
4000 (err = evutil_read_file(hosts_fname, &str, &len, 0)) < 0) {
4002 strlcpy(tmp, "127.0.0.1 localhost", sizeof(tmp));
4003 evdns_base_parse_hosts_line(base, tmp);
4004 strlcpy(tmp, "::1 localhost", sizeof(tmp));
4005 evdns_base_parse_hosts_line(base, tmp);
4006 return err ? -1 : 0;
4009 /* This will break early if there is a NUL in the hosts file.
4010 * Probably not a problem.*/
4013 eol = strchr(cp, '\n');
4017 evdns_base_parse_hosts_line(base, cp);
4020 evdns_base_parse_hosts_line(base, cp);
4030 evdns_base_load_hosts(struct evdns_base *base, const char *hosts_fname)
4034 base = current_base;
4036 res = evdns_base_load_hosts_impl(base, hosts_fname);
4041 /* A single request for a getaddrinfo, either v4 or v6. */
4042 struct getaddrinfo_subrequest {
4043 struct evdns_request *r;
4047 /* State data used to implement an in-progress getaddrinfo. */
4048 struct evdns_getaddrinfo_request {
4049 struct evdns_base *evdns_base;
4050 /* Copy of the modified 'hints' data that we'll use to build
4052 struct evutil_addrinfo hints;
4053 /* The callback to invoke when we're done */
4054 evdns_getaddrinfo_cb user_cb;
4055 /* User-supplied data to give to the callback. */
4057 /* The port to use when building sockaddrs. */
4059 /* The sub_request for an A record (if any) */
4060 struct getaddrinfo_subrequest ipv4_request;
4061 /* The sub_request for an AAAA record (if any) */
4062 struct getaddrinfo_subrequest ipv6_request;
4064 /* The cname result that we were told (if any) */
4067 /* If we have one request answered and one request still inflight,
4068 * then this field holds the answer from the first request... */
4069 struct evutil_addrinfo *pending_result;
4070 /* And this event is a timeout that will tell us to cancel the second
4071 * request if it's taking a long time. */
4072 struct event timeout;
4074 /* And this field holds the error code from the first request... */
4076 /* If this is set, the user canceled this request. */
4077 unsigned user_canceled : 1;
4078 /* If this is set, the user can no longer cancel this request; we're
4079 * just waiting for the free. */
4080 unsigned request_done : 1;
4083 /* Convert an evdns errors to the equivalent getaddrinfo error. */
4085 evdns_err_to_getaddrinfo_err(int e1)
4087 /* XXX Do this better! */
4088 if (e1 == DNS_ERR_NONE)
4090 else if (e1 == DNS_ERR_NOTEXIST)
4091 return EVUTIL_EAI_NONAME;
4093 return EVUTIL_EAI_FAIL;
4096 /* Return the more informative of two getaddrinfo errors. */
4098 getaddrinfo_merge_err(int e1, int e2)
4100 /* XXXX be cleverer here. */
4108 free_getaddrinfo_request(struct evdns_getaddrinfo_request *data)
4110 /* DO NOT CALL this if either of the requests is pending. Only once
4111 * both callbacks have been invoked is it safe to free the request */
4112 if (data->pending_result)
4113 evutil_freeaddrinfo(data->pending_result);
4114 if (data->cname_result)
4115 mm_free(data->cname_result);
4116 event_del(&data->timeout);
4122 add_cname_to_reply(struct evdns_getaddrinfo_request *data,
4123 struct evutil_addrinfo *ai)
4125 if (data->cname_result && ai) {
4126 ai->ai_canonname = data->cname_result;
4127 data->cname_result = NULL;
4131 /* Callback: invoked when one request in a mixed-format A/AAAA getaddrinfo
4132 * request has finished, but the other one took too long to answer. Pass
4133 * along the answer we got, and cancel the other request.
4136 evdns_getaddrinfo_timeout_cb(evutil_socket_t fd, short what, void *ptr)
4138 int v4_timedout = 0, v6_timedout = 0;
4139 struct evdns_getaddrinfo_request *data = ptr;
4141 /* Cancel any pending requests, and note which one */
4142 if (data->ipv4_request.r) {
4143 evdns_cancel_request(NULL, data->ipv4_request.r);
4145 EVDNS_LOCK(data->evdns_base);
4146 ++data->evdns_base->getaddrinfo_ipv4_timeouts;
4147 EVDNS_UNLOCK(data->evdns_base);
4149 if (data->ipv6_request.r) {
4150 evdns_cancel_request(NULL, data->ipv6_request.r);
4152 EVDNS_LOCK(data->evdns_base);
4153 ++data->evdns_base->getaddrinfo_ipv6_timeouts;
4154 EVDNS_UNLOCK(data->evdns_base);
4157 /* We only use this timeout callback when we have an answer for
4159 EVUTIL_ASSERT(!v4_timedout || !v6_timedout);
4161 /* Report the outcome of the other request that didn't time out. */
4162 if (data->pending_result) {
4163 add_cname_to_reply(data, data->pending_result);
4164 data->user_cb(0, data->pending_result, data->user_data);
4165 data->pending_result = NULL;
4167 int e = data->pending_error;
4169 e = EVUTIL_EAI_AGAIN;
4170 data->user_cb(e, NULL, data->user_data);
4173 if (!v4_timedout && !v6_timedout) {
4174 /* should be impossible? XXXX */
4175 free_getaddrinfo_request(data);
4180 evdns_getaddrinfo_set_timeout(struct evdns_base *evdns_base,
4181 struct evdns_getaddrinfo_request *data)
4183 return event_add(&data->timeout, &evdns_base->global_getaddrinfo_allow_skew);
4187 evdns_result_is_answer(int result)
4189 return (result != DNS_ERR_NOTIMPL && result != DNS_ERR_REFUSED &&
4190 result != DNS_ERR_SERVERFAILED && result != DNS_ERR_CANCEL);
4194 evdns_getaddrinfo_gotresolve(int result, char type, int count,
4195 int ttl, void *addresses, void *arg)
4198 struct getaddrinfo_subrequest *req = arg;
4199 struct getaddrinfo_subrequest *other_req;
4200 struct evdns_getaddrinfo_request *data;
4202 struct evutil_addrinfo *res;
4204 struct sockaddr_in sin;
4205 struct sockaddr_in6 sin6;
4206 struct sockaddr *sa;
4207 int socklen, addrlen;
4212 EVUTIL_ASSERT(req->type == DNS_IPv4_A || req->type == DNS_IPv6_AAAA);
4213 if (req->type == DNS_IPv4_A) {
4214 data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv4_request);
4215 other_req = &data->ipv6_request;
4217 data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv6_request);
4218 other_req = &data->ipv4_request;
4221 EVDNS_LOCK(data->evdns_base);
4222 if (evdns_result_is_answer(result)) {
4223 if (req->type == DNS_IPv4_A)
4224 ++data->evdns_base->getaddrinfo_ipv4_answered;
4226 ++data->evdns_base->getaddrinfo_ipv6_answered;
4228 user_canceled = data->user_canceled;
4229 if (other_req->r == NULL)
4230 data->request_done = 1;
4231 EVDNS_UNLOCK(data->evdns_base);
4235 if (result == DNS_ERR_CANCEL && ! user_canceled) {
4236 /* Internal cancel request from timeout or internal error.
4237 * we already answered the user. */
4238 if (other_req->r == NULL)
4239 free_getaddrinfo_request(data);
4243 if (result == DNS_ERR_NONE) {
4245 err = EVUTIL_EAI_NODATA;
4249 err = evdns_err_to_getaddrinfo_err(result);
4253 /* Looks like we got an error. */
4255 /* The other request is still working; maybe it will
4257 /* XXXX handle failure from set_timeout */
4258 evdns_getaddrinfo_set_timeout(data->evdns_base, data);
4259 data->pending_error = err;
4263 if (user_canceled) {
4264 data->user_cb(EVUTIL_EAI_CANCEL, NULL, data->user_data);
4265 } else if (data->pending_result) {
4266 /* If we have an answer waiting, and we weren't
4267 * canceled, ignore this error. */
4268 add_cname_to_reply(data, data->pending_result);
4269 data->user_cb(0, data->pending_result, data->user_data);
4270 data->pending_result = NULL;
4272 if (data->pending_error)
4273 err = getaddrinfo_merge_err(err,
4274 data->pending_error);
4275 data->user_cb(err, NULL, data->user_data);
4277 free_getaddrinfo_request(data);
4279 } else if (user_canceled) {
4281 /* The other request is still working; let it hit this
4282 * callback with EVUTIL_EAI_CANCEL callback and report
4286 data->user_cb(EVUTIL_EAI_CANCEL, NULL, data->user_data);
4287 free_getaddrinfo_request(data);
4291 /* Looks like we got some answers. We should turn them into addrinfos
4292 * and then either queue those or return them all. */
4293 EVUTIL_ASSERT(type == DNS_IPv4_A || type == DNS_IPv6_AAAA);
4295 if (type == DNS_IPv4_A) {
4296 memset(&sin, 0, sizeof(sin));
4297 sin.sin_family = AF_INET;
4298 sin.sin_port = htons(data->port);
4300 sa = (struct sockaddr *)&sin;
4301 socklen = sizeof(sin);
4303 addrp = &sin.sin_addr.s_addr;
4305 memset(&sin6, 0, sizeof(sin6));
4306 sin6.sin6_family = AF_INET6;
4307 sin6.sin6_port = htons(data->port);
4309 sa = (struct sockaddr *)&sin6;
4310 socklen = sizeof(sin6);
4312 addrp = &sin6.sin6_addr.s6_addr;
4316 for (i=0; i < count; ++i) {
4317 struct evutil_addrinfo *ai;
4318 memcpy(addrp, ((char*)addresses)+i*addrlen, addrlen);
4319 ai = evutil_new_addrinfo(sa, socklen, &data->hints);
4322 evdns_cancel_request(NULL, other_req->r);
4324 data->user_cb(EVUTIL_EAI_MEMORY, NULL, data->user_data);
4326 evutil_freeaddrinfo(res);
4328 if (other_req->r == NULL)
4329 free_getaddrinfo_request(data);
4332 res = evutil_addrinfo_append(res, ai);
4336 /* The other request is still in progress; wait for it */
4337 /* XXXX handle failure from set_timeout */
4338 evdns_getaddrinfo_set_timeout(data->evdns_base, data);
4339 data->pending_result = res;
4342 /* The other request is done or never started; append its
4343 * results (if any) and return them. */
4344 if (data->pending_result) {
4345 if (req->type == DNS_IPv4_A)
4346 res = evutil_addrinfo_append(res,
4347 data->pending_result);
4349 res = evutil_addrinfo_append(
4350 data->pending_result, res);
4351 data->pending_result = NULL;
4354 /* Call the user callback. */
4355 add_cname_to_reply(data, res);
4356 data->user_cb(0, res, data->user_data);
4359 free_getaddrinfo_request(data);
4363 static struct hosts_entry *
4364 find_hosts_entry(struct evdns_base *base, const char *hostname,
4365 struct hosts_entry *find_after)
4367 struct hosts_entry *e;
4370 e = TAILQ_NEXT(find_after, next);
4372 e = TAILQ_FIRST(&base->hostsdb);
4374 for (; e; e = TAILQ_NEXT(e, next)) {
4375 if (!evutil_ascii_strcasecmp(e->hostname, hostname))
4382 evdns_getaddrinfo_fromhosts(struct evdns_base *base,
4383 const char *nodename, struct evutil_addrinfo *hints, ev_uint16_t port,
4384 struct evutil_addrinfo **res)
4387 struct hosts_entry *e;
4388 struct evutil_addrinfo *ai=NULL;
4389 int f = hints->ai_family;
4392 for (e = find_hosts_entry(base, nodename, NULL); e;
4393 e = find_hosts_entry(base, nodename, e)) {
4394 struct evutil_addrinfo *ai_new;
4396 if ((e->addr.sa.sa_family == AF_INET && f == PF_INET6) ||
4397 (e->addr.sa.sa_family == AF_INET6 && f == PF_INET))
4399 ai_new = evutil_new_addrinfo(&e->addr.sa, e->addrlen, hints);
4404 sockaddr_setport(ai_new->ai_addr, port);
4405 ai = evutil_addrinfo_append(ai, ai_new);
4410 /* Note that we return an empty answer if we found entries for
4411 * this hostname but none were of the right address type. */
4416 evutil_freeaddrinfo(ai);
4421 struct evdns_getaddrinfo_request *
4422 evdns_getaddrinfo(struct evdns_base *dns_base,
4423 const char *nodename, const char *servname,
4424 const struct evutil_addrinfo *hints_in,
4425 evdns_getaddrinfo_cb cb, void *arg)
4427 struct evdns_getaddrinfo_request *data;
4428 struct evutil_addrinfo hints;
4429 struct evutil_addrinfo *res = NULL;
4435 dns_base = current_base;
4438 "Call to getaddrinfo_async with no "
4439 "evdns_base configured.");
4440 cb(EVUTIL_EAI_FAIL, NULL, arg); /* ??? better error? */
4445 /* If we _must_ answer this immediately, do so. */
4446 if ((hints_in && (hints_in->ai_flags & EVUTIL_AI_NUMERICHOST))) {
4448 err = evutil_getaddrinfo(nodename, servname, hints_in, &res);
4454 memcpy(&hints, hints_in, sizeof(hints));
4456 memset(&hints, 0, sizeof(hints));
4457 hints.ai_family = PF_UNSPEC;
4460 evutil_adjust_hints_for_addrconfig(&hints);
4462 /* Now try to see if we _can_ answer immediately. */
4463 /* (It would be nice to do this by calling getaddrinfo directly, with
4464 * AI_NUMERICHOST, on plaforms that have it, but we can't: there isn't
4465 * a reliable way to distinguish the "that wasn't a numeric host!" case
4466 * from any other EAI_NONAME cases.) */
4467 err = evutil_getaddrinfo_common(nodename, servname, &hints, &res, &port);
4468 if (err != EVUTIL_EAI_NEED_RESOLVE) {
4473 /* If there is an entry in the hosts file, we should give it now. */
4474 if (!evdns_getaddrinfo_fromhosts(dns_base, nodename, &hints, port, &res)) {
4479 /* Okay, things are serious now. We're going to need to actually
4482 data = mm_calloc(1,sizeof(struct evdns_getaddrinfo_request));
4484 cb(EVUTIL_EAI_MEMORY, NULL, arg);
4488 memcpy(&data->hints, &hints, sizeof(data->hints));
4489 data->port = (ev_uint16_t)port;
4490 data->ipv4_request.type = DNS_IPv4_A;
4491 data->ipv6_request.type = DNS_IPv6_AAAA;
4493 data->user_data = arg;
4494 data->evdns_base = dns_base;
4496 want_cname = (hints.ai_flags & EVUTIL_AI_CANONNAME);
4498 /* If we are asked for a PF_UNSPEC address, we launch two requests in
4499 * parallel: one for an A address and one for an AAAA address. We
4500 * can't send just one request, since many servers only answer one
4501 * question per DNS request.
4503 * Once we have the answer to one request, we allow for a short
4504 * timeout before we report it, to see if the other one arrives. If
4505 * they both show up in time, then we report both the answers.
4507 * If too many addresses of one type time out or fail, we should stop
4508 * launching those requests. (XXX we don't do that yet.)
4511 if (hints.ai_family != PF_INET6) {
4512 log(EVDNS_LOG_DEBUG, "Sending request for %s on ipv4 as %p",
4513 nodename, &data->ipv4_request);
4515 data->ipv4_request.r = evdns_base_resolve_ipv4(dns_base,
4516 nodename, 0, evdns_getaddrinfo_gotresolve,
4517 &data->ipv4_request);
4519 data->ipv4_request.r->current_req->put_cname_in_ptr =
4520 &data->cname_result;
4522 if (hints.ai_family != PF_INET) {
4523 log(EVDNS_LOG_DEBUG, "Sending request for %s on ipv6 as %p",
4524 nodename, &data->ipv6_request);
4526 data->ipv6_request.r = evdns_base_resolve_ipv6(dns_base,
4527 nodename, 0, evdns_getaddrinfo_gotresolve,
4528 &data->ipv6_request);
4530 data->ipv6_request.r->current_req->put_cname_in_ptr =
4531 &data->cname_result;
4534 evtimer_assign(&data->timeout, dns_base->event_base,
4535 evdns_getaddrinfo_timeout_cb, data);
4537 if (data->ipv4_request.r || data->ipv6_request.r) {
4541 cb(EVUTIL_EAI_FAIL, NULL, arg);
4547 evdns_getaddrinfo_cancel(struct evdns_getaddrinfo_request *data)
4549 EVDNS_LOCK(data->evdns_base);
4550 if (data->request_done) {
4551 EVDNS_UNLOCK(data->evdns_base);
4554 event_del(&data->timeout);
4555 data->user_canceled = 1;
4556 if (data->ipv4_request.r)
4557 evdns_cancel_request(data->evdns_base, data->ipv4_request.r);
4558 if (data->ipv6_request.r)
4559 evdns_cancel_request(data->evdns_base, data->ipv6_request.r);
4560 EVDNS_UNLOCK(data->evdns_base);