Remove building with NOCRYPTO option
[minix.git] / external / bsd / libevent / dist / evdns.c
blob77192a45151952155ca200391a0ba57d73e33a5c
1 /* $NetBSD: evdns.c,v 1.3 2015/01/29 07:26:02 spz Exp $ */
2 /* Copyright 2006-2007 Niels Provos
3 * Copyright 2007-2012 Nick Mathewson and Niels Provos
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. The name of the author may not be used to endorse or promote products
14 * derived from this software without specific prior written permission.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 /* Based on software by Adam Langly. Adam's original message:
30 * Async DNS Library
31 * Adam Langley <agl@imperialviolet.org>
32 * http://www.imperialviolet.org/eventdns.html
33 * Public Domain code
35 * This software is Public Domain. To view a copy of the public domain dedication,
36 * visit http://creativecommons.org/licenses/publicdomain/ or send a letter to
37 * Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA.
39 * I ask and expect, but do not require, that all derivative works contain an
40 * attribution similar to:
41 * Parts developed by Adam Langley <agl@imperialviolet.org>
43 * You may wish to replace the word "Parts" with something else depending on
44 * the amount of original code.
46 * (Derivative works does not include programs which link against, run or include
47 * the source verbatim in their source distributions)
49 * Version: 0.1b
52 #include <sys/types.h>
53 #include "event2/event-config.h"
54 #include <sys/cdefs.h>
55 __RCSID("$NetBSD: evdns.c,v 1.3 2015/01/29 07:26:02 spz Exp $");
57 #ifndef _FORTIFY_SOURCE
58 #define _FORTIFY_SOURCE 3
59 #endif
61 #include <string.h>
62 #include <fcntl.h>
63 #ifdef _EVENT_HAVE_SYS_TIME_H
64 #include <sys/time.h>
65 #endif
66 #ifdef _EVENT_HAVE_STDINT_H
67 #include <stdint.h>
68 #endif
69 #include <stdlib.h>
70 #include <string.h>
71 #include <errno.h>
72 #ifdef _EVENT_HAVE_UNISTD_H
73 #include <unistd.h>
74 #endif
75 #include <limits.h>
76 #include <sys/stat.h>
77 #include <stdio.h>
78 #include <stdarg.h>
79 #ifdef WIN32
80 #include <winsock2.h>
81 #include <ws2tcpip.h>
82 #ifndef _WIN32_IE
83 #define _WIN32_IE 0x400
84 #endif
85 #include <shlobj.h>
86 #endif
88 #include "event2/dns.h"
89 #include "event2/dns_struct.h"
90 #include "event2/dns_compat.h"
91 #include "event2/util.h"
92 #include "event2/event.h"
93 #include "event2/event_struct.h"
94 #include "event2/thread.h"
96 #include "event2/bufferevent.h"
97 #include "event2/bufferevent_struct.h"
98 #include "bufferevent-internal.h"
100 #include "defer-internal.h"
101 #include "log-internal.h"
102 #include "mm-internal.h"
103 #include "strlcpy-internal.h"
104 #include "ipv6-internal.h"
105 #include "util-internal.h"
106 #include "evthread-internal.h"
107 #ifdef WIN32
108 #include <ctype.h>
109 #include <winsock2.h>
110 #include <windows.h>
111 #include <iphlpapi.h>
112 #include <io.h>
113 #else
114 #include <sys/socket.h>
115 #include <netinet/in.h>
116 #include <arpa/inet.h>
117 #endif
119 #ifdef _EVENT_HAVE_NETINET_IN6_H
120 #include <netinet/in6.h>
121 #endif
123 #define EVDNS_LOG_DEBUG 0
124 #define EVDNS_LOG_WARN 1
125 #define EVDNS_LOG_MSG 2
127 #ifndef HOST_NAME_MAX
128 #define HOST_NAME_MAX 255
129 #endif
131 #include <stdio.h>
133 #undef MIN
134 #define MIN(a,b) ((a)<(b)?(a):(b))
136 #define ASSERT_VALID_REQUEST(req) \
137 EVUTIL_ASSERT((req)->handle && (req)->handle->current_req == (req))
139 #define u64 ev_uint64_t
140 #define u32 ev_uint32_t
141 #define u16 ev_uint16_t
142 #define u8 ev_uint8_t
144 /* maximum number of addresses from a single packet */
145 /* that we bother recording */
146 #define MAX_V4_ADDRS 32
147 #define MAX_V6_ADDRS 32
150 #define TYPE_A EVDNS_TYPE_A
151 #define TYPE_CNAME 5
152 #define TYPE_PTR EVDNS_TYPE_PTR
153 #define TYPE_SOA EVDNS_TYPE_SOA
154 #define TYPE_AAAA EVDNS_TYPE_AAAA
156 #define CLASS_INET EVDNS_CLASS_INET
158 /* Persistent handle. We keep this separate from 'struct request' since we
159 * need some object to last for as long as an evdns_request is outstanding so
160 * that it can be canceled, whereas a search request can lead to multiple
161 * 'struct request' instances being created over its lifetime. */
162 struct evdns_request {
163 struct request *current_req;
164 struct evdns_base *base;
166 int pending_cb; /* Waiting for its callback to be invoked; not
167 * owned by event base any more. */
169 /* elements used by the searching code */
170 int search_index;
171 struct search_state *search_state;
172 char *search_origname; /* needs to be free()ed */
173 int search_flags;
176 struct request {
177 u8 *request; /* the dns packet data */
178 u8 request_type; /* TYPE_PTR or TYPE_A or TYPE_AAAA */
179 unsigned int request_len;
180 int reissue_count;
181 int tx_count; /* the number of times that this packet has been sent */
182 void *user_pointer; /* the pointer given to us for this request */
183 evdns_callback_type user_callback;
184 struct nameserver *ns; /* the server which we last sent it */
186 /* these objects are kept in a circular list */
187 /* XXX We could turn this into a CIRCLEQ. */
188 struct request *next, *prev;
190 struct event timeout_event;
192 u16 trans_id; /* the transaction id */
193 unsigned request_appended :1; /* true if the request pointer is data which follows this struct */
194 unsigned transmit_me :1; /* needs to be transmitted */
196 /* XXXX This is a horrible hack. */
197 char **put_cname_in_ptr; /* store the cname here if we get one. */
199 struct evdns_base *base;
201 struct evdns_request *handle;
204 struct reply {
205 unsigned int type;
206 unsigned int have_answer : 1;
207 union {
208 struct {
209 u32 addrcount;
210 u32 addresses[MAX_V4_ADDRS];
211 } a;
212 struct {
213 u32 addrcount;
214 struct in6_addr addresses[MAX_V6_ADDRS];
215 } aaaa;
216 struct {
217 char name[HOST_NAME_MAX];
218 } ptr;
219 } data;
222 struct nameserver {
223 evutil_socket_t socket; /* a connected UDP socket */
224 struct sockaddr_storage address;
225 ev_socklen_t addrlen;
226 int failed_times; /* number of times which we have given this server a chance */
227 int timedout; /* number of times in a row a request has timed out */
228 struct event event;
229 /* these objects are kept in a circular list */
230 struct nameserver *next, *prev;
231 struct event timeout_event; /* used to keep the timeout for */
232 /* when we next probe this server. */
233 /* Valid if state == 0 */
234 /* Outstanding probe request for this nameserver, if any */
235 struct evdns_request *probe_request;
236 char state; /* zero if we think that this server is down */
237 char choked; /* true if we have an EAGAIN from this server's socket */
238 char write_waiting; /* true if we are waiting for EV_WRITE events */
239 struct evdns_base *base;
243 /* Represents a local port where we're listening for DNS requests. Right now, */
244 /* only UDP is supported. */
245 struct evdns_server_port {
246 evutil_socket_t socket; /* socket we use to read queries and write replies. */
247 int refcnt; /* reference count. */
248 char choked; /* Are we currently blocked from writing? */
249 char closing; /* Are we trying to close this port, pending writes? */
250 evdns_request_callback_fn_type user_callback; /* Fn to handle requests */
251 void *user_data; /* Opaque pointer passed to user_callback */
252 struct event event; /* Read/write event */
253 /* circular list of replies that we want to write. */
254 struct server_request *pending_replies;
255 struct event_base *event_base;
257 #ifndef _EVENT_DISABLE_THREAD_SUPPORT
258 void *lock;
259 #endif
262 /* Represents part of a reply being built. (That is, a single RR.) */
263 struct server_reply_item {
264 struct server_reply_item *next; /* next item in sequence. */
265 char *name; /* name part of the RR */
266 u16 type; /* The RR type */
267 u16 class; /* The RR class (usually CLASS_INET) */
268 u32 ttl; /* The RR TTL */
269 char is_name; /* True iff data is a label */
270 u16 datalen; /* Length of data; -1 if data is a label */
271 void *data; /* The contents of the RR */
274 /* Represents a request that we've received as a DNS server, and holds */
275 /* the components of the reply as we're constructing it. */
276 struct server_request {
277 /* Pointers to the next and previous entries on the list of replies */
278 /* that we're waiting to write. Only set if we have tried to respond */
279 /* and gotten EAGAIN. */
280 struct server_request *next_pending;
281 struct server_request *prev_pending;
283 u16 trans_id; /* Transaction id. */
284 struct evdns_server_port *port; /* Which port received this request on? */
285 struct sockaddr_storage addr; /* Where to send the response */
286 ev_socklen_t addrlen; /* length of addr */
288 int n_answer; /* how many answer RRs have been set? */
289 int n_authority; /* how many authority RRs have been set? */
290 int n_additional; /* how many additional RRs have been set? */
292 struct server_reply_item *answer; /* linked list of answer RRs */
293 struct server_reply_item *authority; /* linked list of authority RRs */
294 struct server_reply_item *additional; /* linked list of additional RRs */
296 /* Constructed response. Only set once we're ready to send a reply. */
297 /* Once this is set, the RR fields are cleared, and no more should be set. */
298 char *response;
299 size_t response_len;
301 /* Caller-visible fields: flags, questions. */
302 struct evdns_server_request base;
305 struct evdns_base {
306 /* An array of n_req_heads circular lists for inflight requests.
307 * Each inflight request req is in req_heads[req->trans_id % n_req_heads].
309 struct request **req_heads;
310 /* A circular list of requests that we're waiting to send, but haven't
311 * sent yet because there are too many requests inflight */
312 struct request *req_waiting_head;
313 /* A circular list of nameservers. */
314 struct nameserver *server_head;
315 int n_req_heads;
317 struct event_base *event_base;
319 /* The number of good nameservers that we have */
320 int global_good_nameservers;
322 /* inflight requests are contained in the req_head list */
323 /* and are actually going out across the network */
324 int global_requests_inflight;
325 /* requests which aren't inflight are in the waiting list */
326 /* and are counted here */
327 int global_requests_waiting;
329 int global_max_requests_inflight;
331 struct timeval global_timeout; /* 5 seconds by default */
332 int global_max_reissues; /* a reissue occurs when we get some errors from the server */
333 int global_max_retransmits; /* number of times we'll retransmit a request which timed out */
334 /* number of timeouts in a row before we consider this server to be down */
335 int global_max_nameserver_timeout;
336 /* true iff we will use the 0x20 hack to prevent poisoning attacks. */
337 int global_randomize_case;
339 /* The first time that a nameserver fails, how long do we wait before
340 * probing to see if it has returned? */
341 struct timeval global_nameserver_probe_initial_timeout;
343 /** Port to bind to for outgoing DNS packets. */
344 struct sockaddr_storage global_outgoing_address;
345 /** ev_socklen_t for global_outgoing_address. 0 if it isn't set. */
346 ev_socklen_t global_outgoing_addrlen;
348 struct timeval global_getaddrinfo_allow_skew;
350 int getaddrinfo_ipv4_timeouts;
351 int getaddrinfo_ipv6_timeouts;
352 int getaddrinfo_ipv4_answered;
353 int getaddrinfo_ipv6_answered;
355 struct search_state *global_search_state;
357 TAILQ_HEAD(hosts_list, hosts_entry) hostsdb;
359 #ifndef _EVENT_DISABLE_THREAD_SUPPORT
360 void *lock;
361 #endif
364 struct hosts_entry {
365 TAILQ_ENTRY(hosts_entry) next;
366 union {
367 struct sockaddr sa;
368 struct sockaddr_in sin;
369 struct sockaddr_in6 sin6;
370 } addr;
371 int addrlen;
372 char hostname[1];
375 static struct evdns_base *current_base = NULL;
377 struct evdns_base *
378 evdns_get_global_base(void)
380 return current_base;
383 /* Given a pointer to an evdns_server_request, get the corresponding */
384 /* server_request. */
385 #define TO_SERVER_REQUEST(base_ptr) \
386 ((struct server_request*) \
387 (((char*)(base_ptr) - evutil_offsetof(struct server_request, base))))
389 #define REQ_HEAD(base, id) ((base)->req_heads[id % (base)->n_req_heads])
391 static struct nameserver *nameserver_pick(struct evdns_base *base);
392 static void evdns_request_insert(struct request *req, struct request **head);
393 static void evdns_request_remove(struct request *req, struct request **head);
394 static void nameserver_ready_callback(evutil_socket_t fd, short events, void *arg);
395 static int evdns_transmit(struct evdns_base *base);
396 static int evdns_request_transmit(struct request *req);
397 static void nameserver_send_probe(struct nameserver *const ns);
398 static void search_request_finished(struct evdns_request *const);
399 static int search_try_next(struct evdns_request *const req);
400 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);
401 static void evdns_requests_pump_waiting_queue(struct evdns_base *base);
402 static u16 transaction_id_pick(struct evdns_base *base);
403 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);
404 static void request_submit(struct request *const req);
406 static int server_request_free(struct server_request *req);
407 static void server_request_free_answers(struct server_request *req);
408 static void server_port_free(struct evdns_server_port *port);
409 static void server_port_ready_callback(evutil_socket_t fd, short events, void *arg);
410 static int evdns_base_resolv_conf_parse_impl(struct evdns_base *base, int flags, const char *const filename);
411 static int evdns_base_set_option_impl(struct evdns_base *base,
412 const char *option, const char *val, int flags);
413 static void evdns_base_free_and_unlock(struct evdns_base *base, int fail_requests);
415 static int strtoint(const char *const str);
417 #ifdef _EVENT_DISABLE_THREAD_SUPPORT
418 #define EVDNS_LOCK(base) _EVUTIL_NIL_STMT
419 #define EVDNS_UNLOCK(base) _EVUTIL_NIL_STMT
420 #define ASSERT_LOCKED(base) _EVUTIL_NIL_STMT
421 #else
422 #define EVDNS_LOCK(base) \
423 EVLOCK_LOCK((base)->lock, 0)
424 #define EVDNS_UNLOCK(base) \
425 EVLOCK_UNLOCK((base)->lock, 0)
426 #define ASSERT_LOCKED(base) \
427 EVLOCK_ASSERT_LOCKED((base)->lock)
428 #endif
430 static void
431 default_evdns_log_fn(int warning, const char *buf)
433 if (warning == EVDNS_LOG_WARN)
434 event_warnx("[evdns] %s", buf);
435 else if (warning == EVDNS_LOG_MSG)
436 event_msgx("[evdns] %s", buf);
437 else
438 event_debug(("[evdns] %s", buf));
441 static evdns_debug_log_fn_type evdns_log_fn = NULL;
443 void
444 evdns_set_log_fn(evdns_debug_log_fn_type fn)
446 evdns_log_fn = fn;
449 #ifdef __GNUC__
450 #define EVDNS_LOG_CHECK __attribute__ ((format(printf, 2, 3)))
451 #else
452 #define EVDNS_LOG_CHECK
453 #endif
455 static void _evdns_log(int warn, const char *fmt, ...) EVDNS_LOG_CHECK;
456 static void
457 _evdns_log(int warn, const char *fmt, ...)
459 va_list args;
460 char buf[512];
461 if (!evdns_log_fn)
462 return;
463 va_start(args,fmt);
464 evutil_vsnprintf(buf, sizeof(buf), fmt, args);
465 va_end(args);
466 if (evdns_log_fn) {
467 if (warn == EVDNS_LOG_MSG)
468 warn = EVDNS_LOG_WARN;
469 evdns_log_fn(warn, buf);
470 } else {
471 default_evdns_log_fn(warn, buf);
476 #define log _evdns_log
478 /* This walks the list of inflight requests to find the */
479 /* one with a matching transaction id. Returns NULL on */
480 /* failure */
481 static struct request *
482 request_find_from_trans_id(struct evdns_base *base, u16 trans_id) {
483 struct request *req = REQ_HEAD(base, trans_id);
484 struct request *const started_at = req;
486 ASSERT_LOCKED(base);
488 if (req) {
489 do {
490 if (req->trans_id == trans_id) return req;
491 req = req->next;
492 } while (req != started_at);
495 return NULL;
498 /* a libevent callback function which is called when a nameserver */
499 /* has gone down and we want to test if it has came back to life yet */
500 static void
501 nameserver_prod_callback(evutil_socket_t fd, short events, void *arg) {
502 struct nameserver *const ns = (struct nameserver *) arg;
503 (void)fd;
504 (void)events;
506 EVDNS_LOCK(ns->base);
507 nameserver_send_probe(ns);
508 EVDNS_UNLOCK(ns->base);
511 /* a libevent callback which is called when a nameserver probe (to see if */
512 /* it has come back to life) times out. We increment the count of failed_times */
513 /* and wait longer to send the next probe packet. */
514 static void
515 nameserver_probe_failed(struct nameserver *const ns) {
516 struct timeval timeout;
517 int i;
519 ASSERT_LOCKED(ns->base);
520 (void) evtimer_del(&ns->timeout_event);
521 if (ns->state == 1) {
522 /* This can happen if the nameserver acts in a way which makes us mark */
523 /* it as bad and then starts sending good replies. */
524 return;
527 #define MAX_PROBE_TIMEOUT 3600
528 #define TIMEOUT_BACKOFF_FACTOR 3
530 memcpy(&timeout, &ns->base->global_nameserver_probe_initial_timeout,
531 sizeof(struct timeval));
532 for (i=ns->failed_times; i > 0 && timeout.tv_sec < MAX_PROBE_TIMEOUT; --i) {
533 timeout.tv_sec *= TIMEOUT_BACKOFF_FACTOR;
534 timeout.tv_usec *= TIMEOUT_BACKOFF_FACTOR;
535 if (timeout.tv_usec > 1000000) {
536 timeout.tv_sec += timeout.tv_usec / 1000000;
537 timeout.tv_usec %= 1000000;
540 if (timeout.tv_sec > MAX_PROBE_TIMEOUT) {
541 timeout.tv_sec = MAX_PROBE_TIMEOUT;
542 timeout.tv_usec = 0;
545 ns->failed_times++;
547 if (evtimer_add(&ns->timeout_event, &timeout) < 0) {
548 char addrbuf[128];
549 log(EVDNS_LOG_WARN,
550 "Error from libevent when adding timer event for %s",
551 evutil_format_sockaddr_port(
552 (struct sockaddr *)&ns->address,
553 addrbuf, sizeof(addrbuf)));
557 /* called when a nameserver has been deemed to have failed. For example, too */
558 /* many packets have timed out etc */
559 static void
560 nameserver_failed(struct nameserver *const ns, const char *msg) {
561 struct request *req, *started_at;
562 struct evdns_base *base = ns->base;
563 int i;
564 char addrbuf[128];
566 ASSERT_LOCKED(base);
567 /* if this nameserver has already been marked as failed */
568 /* then don't do anything */
569 if (!ns->state) return;
571 log(EVDNS_LOG_MSG, "Nameserver %s has failed: %s",
572 evutil_format_sockaddr_port(
573 (struct sockaddr *)&ns->address,
574 addrbuf, sizeof(addrbuf)),
575 msg);
577 base->global_good_nameservers--;
578 EVUTIL_ASSERT(base->global_good_nameservers >= 0);
579 if (base->global_good_nameservers == 0) {
580 log(EVDNS_LOG_MSG, "All nameservers have failed");
583 ns->state = 0;
584 ns->failed_times = 1;
586 if (evtimer_add(&ns->timeout_event,
587 &base->global_nameserver_probe_initial_timeout) < 0) {
588 log(EVDNS_LOG_WARN,
589 "Error from libevent when adding timer event for %s",
590 evutil_format_sockaddr_port(
591 (struct sockaddr *)&ns->address,
592 addrbuf, sizeof(addrbuf)));
593 /* ???? Do more? */
596 /* walk the list of inflight requests to see if any can be reassigned to */
597 /* a different server. Requests in the waiting queue don't have a */
598 /* nameserver assigned yet */
600 /* if we don't have *any* good nameservers then there's no point */
601 /* trying to reassign requests to one */
602 if (!base->global_good_nameservers) return;
604 for (i = 0; i < base->n_req_heads; ++i) {
605 req = started_at = base->req_heads[i];
606 if (req) {
607 do {
608 if (req->tx_count == 0 && req->ns == ns) {
609 /* still waiting to go out, can be moved */
610 /* to another server */
611 req->ns = nameserver_pick(base);
613 req = req->next;
614 } while (req != started_at);
619 static void
620 nameserver_up(struct nameserver *const ns)
622 char addrbuf[128];
623 ASSERT_LOCKED(ns->base);
624 if (ns->state) return;
625 log(EVDNS_LOG_MSG, "Nameserver %s is back up",
626 evutil_format_sockaddr_port(
627 (struct sockaddr *)&ns->address,
628 addrbuf, sizeof(addrbuf)));
629 evtimer_del(&ns->timeout_event);
630 if (ns->probe_request) {
631 evdns_cancel_request(ns->base, ns->probe_request);
632 ns->probe_request = NULL;
634 ns->state = 1;
635 ns->failed_times = 0;
636 ns->timedout = 0;
637 ns->base->global_good_nameservers++;
640 static void
641 request_trans_id_set(struct request *const req, const u16 trans_id) {
642 req->trans_id = trans_id;
643 *((u16 *) req->request) = htons(trans_id);
646 /* Called to remove a request from a list and dealloc it. */
647 /* head is a pointer to the head of the list it should be */
648 /* removed from or NULL if the request isn't in a list. */
649 /* when free_handle is one, free the handle as well. */
650 static void
651 request_finished(struct request *const req, struct request **head, int free_handle) {
652 struct evdns_base *base = req->base;
653 int was_inflight = (head != &base->req_waiting_head);
654 EVDNS_LOCK(base);
655 ASSERT_VALID_REQUEST(req);
657 if (head)
658 evdns_request_remove(req, head);
660 log(EVDNS_LOG_DEBUG, "Removing timeout for request %p", req);
661 if (was_inflight) {
662 evtimer_del(&req->timeout_event);
663 base->global_requests_inflight--;
664 } else {
665 base->global_requests_waiting--;
667 /* it was initialized during request_new / evtimer_assign */
668 event_debug_unassign(&req->timeout_event);
670 if (!req->request_appended) {
671 /* need to free the request data on it's own */
672 mm_free(req->request);
673 } else {
674 /* the request data is appended onto the header */
675 /* so everything gets free()ed when we: */
678 if (req->handle) {
679 EVUTIL_ASSERT(req->handle->current_req == req);
681 if (free_handle) {
682 search_request_finished(req->handle);
683 req->handle->current_req = NULL;
684 if (! req->handle->pending_cb) {
685 /* If we're planning to run the callback,
686 * don't free the handle until later. */
687 mm_free(req->handle);
689 req->handle = NULL; /* If we have a bug, let's crash
690 * early */
691 } else {
692 req->handle->current_req = NULL;
696 mm_free(req);
698 evdns_requests_pump_waiting_queue(base);
699 EVDNS_UNLOCK(base);
702 /* This is called when a server returns a funny error code. */
703 /* We try the request again with another server. */
704 /* */
705 /* return: */
706 /* 0 ok */
707 /* 1 failed/reissue is pointless */
708 static int
709 request_reissue(struct request *req) {
710 const struct nameserver *const last_ns = req->ns;
711 ASSERT_LOCKED(req->base);
712 ASSERT_VALID_REQUEST(req);
713 /* the last nameserver should have been marked as failing */
714 /* by the caller of this function, therefore pick will try */
715 /* not to return it */
716 req->ns = nameserver_pick(req->base);
717 if (req->ns == last_ns) {
718 /* ... but pick did return it */
719 /* not a lot of point in trying again with the */
720 /* same server */
721 return 1;
724 req->reissue_count++;
725 req->tx_count = 0;
726 req->transmit_me = 1;
728 return 0;
731 /* this function looks for space on the inflight queue and promotes */
732 /* requests from the waiting queue if it can. */
733 /* */
734 /* TODO: */
735 /* add return code, see at nameserver_pick() and other functions. */
736 static void
737 evdns_requests_pump_waiting_queue(struct evdns_base *base) {
738 ASSERT_LOCKED(base);
739 while (base->global_requests_inflight < base->global_max_requests_inflight &&
740 base->global_requests_waiting) {
741 struct request *req;
743 EVUTIL_ASSERT(base->req_waiting_head);
744 req = base->req_waiting_head;
746 req->ns = nameserver_pick(base);
747 if (!req->ns)
748 return;
750 /* move a request from the waiting queue to the inflight queue */
751 evdns_request_remove(req, &base->req_waiting_head);
753 base->global_requests_waiting--;
754 base->global_requests_inflight++;
756 request_trans_id_set(req, transaction_id_pick(base));
758 evdns_request_insert(req, &REQ_HEAD(base, req->trans_id));
759 evdns_request_transmit(req);
760 evdns_transmit(base);
764 /* TODO(nickm) document */
765 struct deferred_reply_callback {
766 struct deferred_cb deferred;
767 struct evdns_request *handle;
768 u8 request_type;
769 u8 have_reply;
770 u32 ttl;
771 u32 err;
772 evdns_callback_type user_callback;
773 struct reply reply;
776 static void
777 reply_run_callback(struct deferred_cb *d, void *user_pointer)
779 struct deferred_reply_callback *cb =
780 EVUTIL_UPCAST(d, struct deferred_reply_callback, deferred);
782 switch (cb->request_type) {
783 case TYPE_A:
784 if (cb->have_reply)
785 cb->user_callback(DNS_ERR_NONE, DNS_IPv4_A,
786 cb->reply.data.a.addrcount, cb->ttl,
787 cb->reply.data.a.addresses,
788 user_pointer);
789 else
790 cb->user_callback(cb->err, 0, 0, cb->ttl, NULL, user_pointer);
791 break;
792 case TYPE_PTR:
793 if (cb->have_reply) {
794 char *name = cb->reply.data.ptr.name;
795 cb->user_callback(DNS_ERR_NONE, DNS_PTR, 1, cb->ttl,
796 &name, user_pointer);
797 } else {
798 cb->user_callback(cb->err, 0, 0, cb->ttl, NULL, user_pointer);
800 break;
801 case TYPE_AAAA:
802 if (cb->have_reply)
803 cb->user_callback(DNS_ERR_NONE, DNS_IPv6_AAAA,
804 cb->reply.data.aaaa.addrcount, cb->ttl,
805 cb->reply.data.aaaa.addresses,
806 user_pointer);
807 else
808 cb->user_callback(cb->err, 0, 0, cb->ttl, NULL, user_pointer);
809 break;
810 default:
811 EVUTIL_ASSERT(0);
814 if (cb->handle && cb->handle->pending_cb) {
815 mm_free(cb->handle);
818 mm_free(cb);
821 static void
822 reply_schedule_callback(struct request *const req, u32 ttl, u32 err, struct reply *reply)
824 struct deferred_reply_callback *d = mm_calloc(1, sizeof(*d));
826 if (!d) {
827 event_warn("%s: Couldn't allocate space for deferred callback.",
828 __func__);
829 return;
832 ASSERT_LOCKED(req->base);
834 d->request_type = req->request_type;
835 d->user_callback = req->user_callback;
836 d->ttl = ttl;
837 d->err = err;
838 if (reply) {
839 d->have_reply = 1;
840 memcpy(&d->reply, reply, sizeof(struct reply));
843 if (req->handle) {
844 req->handle->pending_cb = 1;
845 d->handle = req->handle;
848 event_deferred_cb_init(&d->deferred, reply_run_callback,
849 req->user_pointer);
850 event_deferred_cb_schedule(
851 event_base_get_deferred_cb_queue(req->base->event_base),
852 &d->deferred);
855 /* this processes a parsed reply packet */
856 static void
857 reply_handle(struct request *const req, u16 flags, u32 ttl, struct reply *reply) {
858 int error;
859 char addrbuf[128];
860 static const int error_codes[] = {
861 DNS_ERR_FORMAT, DNS_ERR_SERVERFAILED, DNS_ERR_NOTEXIST,
862 DNS_ERR_NOTIMPL, DNS_ERR_REFUSED
865 ASSERT_LOCKED(req->base);
866 ASSERT_VALID_REQUEST(req);
868 if (flags & 0x020f || !reply || !reply->have_answer) {
869 /* there was an error */
870 if (flags & 0x0200) {
871 error = DNS_ERR_TRUNCATED;
872 } else if (flags & 0x000f) {
873 u16 error_code = (flags & 0x000f) - 1;
874 if (error_code > 4) {
875 error = DNS_ERR_UNKNOWN;
876 } else {
877 error = error_codes[error_code];
879 } else if (reply && !reply->have_answer) {
880 error = DNS_ERR_NODATA;
881 } else {
882 error = DNS_ERR_UNKNOWN;
885 switch (error) {
886 case DNS_ERR_NOTIMPL:
887 case DNS_ERR_REFUSED:
888 /* we regard these errors as marking a bad nameserver */
889 if (req->reissue_count < req->base->global_max_reissues) {
890 char msg[64];
891 evutil_snprintf(msg, sizeof(msg), "Bad response %d (%s)",
892 error, evdns_err_to_string(error));
893 nameserver_failed(req->ns, msg);
894 if (!request_reissue(req)) return;
896 break;
897 case DNS_ERR_SERVERFAILED:
898 /* rcode 2 (servfailed) sometimes means "we
899 * are broken" and sometimes (with some binds)
900 * means "that request was very confusing."
901 * Treat this as a timeout, not a failure.
903 log(EVDNS_LOG_DEBUG, "Got a SERVERFAILED from nameserver"
904 "at %s; will allow the request to time out.",
905 evutil_format_sockaddr_port(
906 (struct sockaddr *)&req->ns->address,
907 addrbuf, sizeof(addrbuf)));
908 break;
909 default:
910 /* we got a good reply from the nameserver: it is up. */
911 if (req->handle == req->ns->probe_request) {
912 /* Avoid double-free */
913 req->ns->probe_request = NULL;
916 nameserver_up(req->ns);
919 if (req->handle->search_state &&
920 req->request_type != TYPE_PTR) {
921 /* if we have a list of domains to search in,
922 * try the next one */
923 if (!search_try_next(req->handle)) {
924 /* a new request was issued so this
925 * request is finished and */
926 /* the user callback will be made when
927 * that request (or a */
928 /* child of it) finishes. */
929 return;
933 /* all else failed. Pass the failure up */
934 reply_schedule_callback(req, ttl, error, NULL);
935 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1);
936 } else {
937 /* all ok, tell the user */
938 reply_schedule_callback(req, ttl, 0, reply);
939 if (req->handle == req->ns->probe_request)
940 req->ns->probe_request = NULL; /* Avoid double-free */
941 nameserver_up(req->ns);
942 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1);
946 static int
947 name_parse(u8 *packet, int length, int *idx, char *name_out, int name_out_len) {
948 int name_end = -1;
949 int j = *idx;
950 int ptr_count = 0;
951 #define GET32(x) do { if (j + 4 > length) goto err; memcpy(&_t32, packet + j, 4); j += 4; x = ntohl(_t32); } while (/*CONSTCOND*/0)
952 #define GET16(x) do { if (j + 2 > length) goto err; memcpy(&_t, packet + j, 2); j += 2; x = ntohs(_t); } while (/*CONSTCOND*/0)
953 #define GET8(x) do { if (j >= length) goto err; x = packet[j++]; } while (/*CONSTCOND*/0)
955 char *cp = name_out;
956 const char *const end = name_out + name_out_len;
958 /* Normally, names are a series of length prefixed strings terminated */
959 /* with a length of 0 (the lengths are u8's < 63). */
960 /* However, the length can start with a pair of 1 bits and that */
961 /* means that the next 14 bits are a pointer within the current */
962 /* packet. */
964 for (;;) {
965 u8 label_len;
966 if (j >= length) return -1;
967 GET8(label_len);
968 if (!label_len) break;
969 if (label_len & 0xc0) {
970 u8 ptr_low;
971 GET8(ptr_low);
972 if (name_end < 0) name_end = j;
973 j = (((int)label_len & 0x3f) << 8) + ptr_low;
974 /* Make sure that the target offset is in-bounds. */
975 if (j < 0 || j >= length) return -1;
976 /* If we've jumped more times than there are characters in the
977 * message, we must have a loop. */
978 if (++ptr_count > length) return -1;
979 continue;
981 if (label_len > 63) return -1;
982 if (cp != name_out) {
983 if (cp + 1 >= end) return -1;
984 *cp++ = '.';
986 if (cp + label_len >= end) return -1;
987 memcpy(cp, packet + j, label_len);
988 cp += label_len;
989 j += label_len;
991 if (cp >= end) return -1;
992 *cp = '\0';
993 if (name_end < 0)
994 *idx = j;
995 else
996 *idx = name_end;
997 return 0;
998 err:
999 return -1;
1002 /* parses a raw request from a nameserver */
1003 static int
1004 reply_parse(struct evdns_base *base, u8 *packet, int length) {
1005 int j = 0, k = 0; /* index into packet */
1006 u16 _t; /* used by the macros */
1007 u32 _t32; /* used by the macros */
1008 char tmp_name[256], cmp_name[256]; /* used by the macros */
1009 int name_matches = 0;
1011 u16 trans_id, questions, answers, authority, additional, datalength;
1012 u16 flags = 0;
1013 u32 ttl, ttl_r = 0xffffffff;
1014 struct reply reply;
1015 struct request *req = NULL;
1016 unsigned int i;
1018 ASSERT_LOCKED(base);
1020 GET16(trans_id);
1021 GET16(flags);
1022 GET16(questions);
1023 GET16(answers);
1024 GET16(authority);
1025 GET16(additional);
1026 (void) authority; /* suppress "unused variable" warnings. */
1027 (void) additional; /* suppress "unused variable" warnings. */
1029 req = request_find_from_trans_id(base, trans_id);
1030 if (!req) return -1;
1031 EVUTIL_ASSERT(req->base == base);
1033 memset(&reply, 0, sizeof(reply));
1035 /* If it's not an answer, it doesn't correspond to any request. */
1036 if (!(flags & 0x8000)) return -1; /* must be an answer */
1037 if ((flags & 0x020f) && (flags & 0x020f) != DNS_ERR_NOTEXIST) {
1038 /* there was an error and it's not NXDOMAIN */
1039 goto err;
1041 /* if (!answers) return; */ /* must have an answer of some form */
1043 /* This macro skips a name in the DNS reply. */
1044 #define SKIP_NAME \
1045 do { tmp_name[0] = '\0'; \
1046 if (name_parse(packet, length, &j, tmp_name, \
1047 sizeof(tmp_name))<0) \
1048 goto err; \
1049 } while (/*CONSTCOND*/0)
1050 #define TEST_NAME \
1051 do { tmp_name[0] = '\0'; \
1052 cmp_name[0] = '\0'; \
1053 k = j; \
1054 if (name_parse(packet, length, &j, tmp_name, \
1055 sizeof(tmp_name))<0) \
1056 goto err; \
1057 if (name_parse(req->request, req->request_len, &k, \
1058 cmp_name, sizeof(cmp_name))<0) \
1059 goto err; \
1060 if (base->global_randomize_case) { \
1061 if (strcmp(tmp_name, cmp_name) == 0) \
1062 name_matches = 1; \
1063 } else { \
1064 if (evutil_ascii_strcasecmp(tmp_name, cmp_name) == 0) \
1065 name_matches = 1; \
1067 } while (/*CONSTCOND*/0)
1069 reply.type = req->request_type;
1071 /* skip over each question in the reply */
1072 for (i = 0; i < questions; ++i) {
1073 /* the question looks like
1074 * <label:name><u16:type><u16:class>
1076 TEST_NAME;
1077 j += 4;
1078 if (j > length) goto err;
1081 if (!name_matches)
1082 goto err;
1084 /* now we have the answer section which looks like
1085 * <label:name><u16:type><u16:class><u32:ttl><u16:len><data...>
1088 for (i = 0; i < answers; ++i) {
1089 u16 type, class;
1091 SKIP_NAME;
1092 GET16(type);
1093 GET16(class);
1094 GET32(ttl);
1095 GET16(datalength);
1097 if (type == TYPE_A && class == CLASS_INET) {
1098 int addrcount, addrtocopy;
1099 if (req->request_type != TYPE_A) {
1100 j += datalength; continue;
1102 if ((datalength & 3) != 0) /* not an even number of As. */
1103 goto err;
1104 addrcount = datalength >> 2;
1105 addrtocopy = MIN(MAX_V4_ADDRS - reply.data.a.addrcount, (unsigned)addrcount);
1107 ttl_r = MIN(ttl_r, ttl);
1108 /* we only bother with the first four addresses. */
1109 if (j + 4*addrtocopy > length) goto err;
1110 memcpy(&reply.data.a.addresses[reply.data.a.addrcount],
1111 packet + j, 4*addrtocopy);
1112 j += 4*addrtocopy;
1113 reply.data.a.addrcount += addrtocopy;
1114 reply.have_answer = 1;
1115 if (reply.data.a.addrcount == MAX_V4_ADDRS) break;
1116 } else if (type == TYPE_PTR && class == CLASS_INET) {
1117 if (req->request_type != TYPE_PTR) {
1118 j += datalength; continue;
1120 if (name_parse(packet, length, &j, reply.data.ptr.name,
1121 sizeof(reply.data.ptr.name))<0)
1122 goto err;
1123 ttl_r = MIN(ttl_r, ttl);
1124 reply.have_answer = 1;
1125 break;
1126 } else if (type == TYPE_CNAME) {
1127 char cname[HOST_NAME_MAX];
1128 if (!req->put_cname_in_ptr || *req->put_cname_in_ptr) {
1129 j += datalength; continue;
1131 if (name_parse(packet, length, &j, cname,
1132 sizeof(cname))<0)
1133 goto err;
1134 *req->put_cname_in_ptr = mm_strdup(cname);
1135 } else if (type == TYPE_AAAA && class == CLASS_INET) {
1136 int addrcount, addrtocopy;
1137 if (req->request_type != TYPE_AAAA) {
1138 j += datalength; continue;
1140 if ((datalength & 15) != 0) /* not an even number of AAAAs. */
1141 goto err;
1142 addrcount = datalength >> 4; /* each address is 16 bytes long */
1143 addrtocopy = MIN(MAX_V6_ADDRS - reply.data.aaaa.addrcount, (unsigned)addrcount);
1144 ttl_r = MIN(ttl_r, ttl);
1146 /* we only bother with the first four addresses. */
1147 if (j + 16*addrtocopy > length) goto err;
1148 memcpy(&reply.data.aaaa.addresses[reply.data.aaaa.addrcount],
1149 packet + j, 16*addrtocopy);
1150 reply.data.aaaa.addrcount += addrtocopy;
1151 j += 16*addrtocopy;
1152 reply.have_answer = 1;
1153 if (reply.data.aaaa.addrcount == MAX_V6_ADDRS) break;
1154 } else {
1155 /* skip over any other type of resource */
1156 j += datalength;
1160 if (!reply.have_answer) {
1161 for (i = 0; i < authority; ++i) {
1162 u16 type, class;
1163 SKIP_NAME;
1164 GET16(type);
1165 GET16(class);
1166 GET32(ttl);
1167 GET16(datalength);
1168 if (type == TYPE_SOA && class == CLASS_INET) {
1169 u32 serial, refresh, retry, expire, minimum;
1170 SKIP_NAME;
1171 SKIP_NAME;
1172 GET32(serial);
1173 GET32(refresh);
1174 GET32(retry);
1175 GET32(expire);
1176 GET32(minimum);
1177 (void)expire;
1178 (void)retry;
1179 (void)refresh;
1180 (void)serial;
1181 ttl_r = MIN(ttl_r, ttl);
1182 ttl_r = MIN(ttl_r, minimum);
1183 } else {
1184 /* skip over any other type of resource */
1185 j += datalength;
1190 if (ttl_r == 0xffffffff)
1191 ttl_r = 0;
1193 reply_handle(req, flags, ttl_r, &reply);
1194 return 0;
1195 err:
1196 if (req)
1197 reply_handle(req, flags, 0, NULL);
1198 return -1;
1201 /* Parse a raw request (packet,length) sent to a nameserver port (port) from */
1202 /* a DNS client (addr,addrlen), and if it's well-formed, call the corresponding */
1203 /* callback. */
1204 static int
1205 request_parse(u8 *packet, int length, struct evdns_server_port *port, struct sockaddr *addr, ev_socklen_t addrlen)
1207 int j = 0; /* index into packet */
1208 u16 _t; /* used by the macros */
1209 char tmp_name[256]; /* used by the macros */
1211 int i;
1212 u16 trans_id, flags, questions, answers, authority, additional;
1213 struct server_request *server_req = NULL;
1215 ASSERT_LOCKED(port);
1217 /* Get the header fields */
1218 GET16(trans_id);
1219 GET16(flags);
1220 GET16(questions);
1221 GET16(answers);
1222 GET16(authority);
1223 GET16(additional);
1224 (void)answers;
1225 (void)additional;
1226 (void)authority;
1228 if (flags & 0x8000) return -1; /* Must not be an answer. */
1229 flags &= 0x0110; /* Only RD and CD get preserved. */
1231 server_req = mm_malloc(sizeof(struct server_request));
1232 if (server_req == NULL) return -1;
1233 memset(server_req, 0, sizeof(struct server_request));
1235 server_req->trans_id = trans_id;
1236 memcpy(&server_req->addr, addr, addrlen);
1237 server_req->addrlen = addrlen;
1239 server_req->base.flags = flags;
1240 server_req->base.nquestions = 0;
1241 server_req->base.questions = mm_calloc(sizeof(struct evdns_server_question *), questions);
1242 if (server_req->base.questions == NULL)
1243 goto err;
1245 for (i = 0; i < questions; ++i) {
1246 u16 type, class;
1247 struct evdns_server_question *q;
1248 int namelen;
1249 if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0)
1250 goto err;
1251 GET16(type);
1252 GET16(class);
1253 namelen = (int)strlen(tmp_name);
1254 q = mm_malloc(sizeof(struct evdns_server_question) + namelen);
1255 if (!q)
1256 goto err;
1257 q->type = type;
1258 q->dns_question_class = class;
1259 memcpy(q->name, tmp_name, namelen+1);
1260 server_req->base.questions[server_req->base.nquestions++] = q;
1263 /* Ignore answers, authority, and additional. */
1265 server_req->port = port;
1266 port->refcnt++;
1268 /* Only standard queries are supported. */
1269 if (flags & 0x7800) {
1270 evdns_server_request_respond(&(server_req->base), DNS_ERR_NOTIMPL);
1271 return -1;
1274 port->user_callback(&(server_req->base), port->user_data);
1276 return 0;
1277 err:
1278 if (server_req) {
1279 if (server_req->base.questions) {
1280 for (i = 0; i < server_req->base.nquestions; ++i)
1281 mm_free(server_req->base.questions[i]);
1282 mm_free(server_req->base.questions);
1284 mm_free(server_req);
1286 return -1;
1288 #undef SKIP_NAME
1289 #undef GET32
1290 #undef GET16
1291 #undef GET8
1295 void
1296 evdns_set_transaction_id_fn(ev_uint16_t (*fn)(void))
1300 void
1301 evdns_set_random_bytes_fn(void (*fn)(char *, size_t))
1305 /* Try to choose a strong transaction id which isn't already in flight */
1306 static u16
1307 transaction_id_pick(struct evdns_base *base) {
1308 ASSERT_LOCKED(base);
1309 for (;;) {
1310 u16 trans_id;
1311 evutil_secure_rng_get_bytes(&trans_id, sizeof(trans_id));
1313 if (trans_id == 0xffff) continue;
1314 /* now check to see if that id is already inflight */
1315 if (request_find_from_trans_id(base, trans_id) == NULL)
1316 return trans_id;
1320 /* choose a namesever to use. This function will try to ignore */
1321 /* nameservers which we think are down and load balance across the rest */
1322 /* by updating the server_head global each time. */
1323 static struct nameserver *
1324 nameserver_pick(struct evdns_base *base) {
1325 struct nameserver *started_at = base->server_head, *picked;
1326 ASSERT_LOCKED(base);
1327 if (!base->server_head) return NULL;
1329 /* if we don't have any good nameservers then there's no */
1330 /* point in trying to find one. */
1331 if (!base->global_good_nameservers) {
1332 base->server_head = base->server_head->next;
1333 return base->server_head;
1336 /* remember that nameservers are in a circular list */
1337 for (;;) {
1338 if (base->server_head->state) {
1339 /* we think this server is currently good */
1340 picked = base->server_head;
1341 base->server_head = base->server_head->next;
1342 return picked;
1345 base->server_head = base->server_head->next;
1346 if (base->server_head == started_at) {
1347 /* all the nameservers seem to be down */
1348 /* so we just return this one and hope for the */
1349 /* best */
1350 EVUTIL_ASSERT(base->global_good_nameservers == 0);
1351 picked = base->server_head;
1352 base->server_head = base->server_head->next;
1353 return picked;
1358 /* this is called when a namesever socket is ready for reading */
1359 static void
1360 nameserver_read(struct nameserver *ns) {
1361 struct sockaddr_storage ss;
1362 ev_socklen_t addrlen = sizeof(ss);
1363 u8 packet[1500];
1364 char addrbuf[128];
1365 ASSERT_LOCKED(ns->base);
1367 for (;;) {
1368 const int r = recvfrom(ns->socket, (void*)packet,
1369 sizeof(packet), 0,
1370 (struct sockaddr*)&ss, &addrlen);
1371 if (r < 0) {
1372 int err = evutil_socket_geterror(ns->socket);
1373 if (EVUTIL_ERR_RW_RETRIABLE(err))
1374 return;
1375 nameserver_failed(ns,
1376 evutil_socket_error_to_string(err));
1377 return;
1379 if (evutil_sockaddr_cmp((struct sockaddr*)&ss,
1380 (struct sockaddr*)&ns->address, 0)) {
1381 log(EVDNS_LOG_WARN, "Address mismatch on received "
1382 "DNS packet. Apparent source was %s",
1383 evutil_format_sockaddr_port(
1384 (struct sockaddr *)&ss,
1385 addrbuf, sizeof(addrbuf)));
1386 return;
1389 ns->timedout = 0;
1390 reply_parse(ns->base, packet, r);
1394 /* Read a packet from a DNS client on a server port s, parse it, and */
1395 /* act accordingly. */
1396 static void
1397 server_port_read(struct evdns_server_port *s) {
1398 u8 packet[1500];
1399 struct sockaddr_storage addr;
1400 ev_socklen_t addrlen;
1401 int r;
1402 ASSERT_LOCKED(s);
1404 for (;;) {
1405 addrlen = sizeof(struct sockaddr_storage);
1406 r = recvfrom(s->socket, (void*)packet, sizeof(packet), 0,
1407 (struct sockaddr*) &addr, &addrlen);
1408 if (r < 0) {
1409 int err = evutil_socket_geterror(s->socket);
1410 if (EVUTIL_ERR_RW_RETRIABLE(err))
1411 return;
1412 log(EVDNS_LOG_WARN,
1413 "Error %s (%d) while reading request.",
1414 evutil_socket_error_to_string(err), err);
1415 return;
1417 request_parse(packet, r, s, (struct sockaddr*) &addr, addrlen);
1421 /* Try to write all pending replies on a given DNS server port. */
1422 static void
1423 server_port_flush(struct evdns_server_port *port)
1425 struct server_request *req = port->pending_replies;
1426 ASSERT_LOCKED(port);
1427 while (req) {
1428 int r = sendto(port->socket, req->response, (int)req->response_len, 0,
1429 (struct sockaddr*) &req->addr, (ev_socklen_t)req->addrlen);
1430 if (r < 0) {
1431 int err = evutil_socket_geterror(port->socket);
1432 if (EVUTIL_ERR_RW_RETRIABLE(err))
1433 return;
1434 log(EVDNS_LOG_WARN, "Error %s (%d) while writing response to port; dropping", evutil_socket_error_to_string(err), err);
1436 if (server_request_free(req)) {
1437 /* we released the last reference to req->port. */
1438 return;
1439 } else {
1440 EVUTIL_ASSERT(req != port->pending_replies);
1441 req = port->pending_replies;
1445 /* We have no more pending requests; stop listening for 'writeable' events. */
1446 (void) event_del(&port->event);
1447 event_assign(&port->event, port->event_base,
1448 port->socket, EV_READ | EV_PERSIST,
1449 server_port_ready_callback, port);
1451 if (event_add(&port->event, NULL) < 0) {
1452 log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server.");
1453 /* ???? Do more? */
1457 /* set if we are waiting for the ability to write to this server. */
1458 /* if waiting is true then we ask libevent for EV_WRITE events, otherwise */
1459 /* we stop these events. */
1460 static void
1461 nameserver_write_waiting(struct nameserver *ns, char waiting) {
1462 ASSERT_LOCKED(ns->base);
1463 if (ns->write_waiting == waiting) return;
1465 ns->write_waiting = waiting;
1466 (void) event_del(&ns->event);
1467 event_assign(&ns->event, ns->base->event_base,
1468 ns->socket, EV_READ | (waiting ? EV_WRITE : 0) | EV_PERSIST,
1469 nameserver_ready_callback, ns);
1470 if (event_add(&ns->event, NULL) < 0) {
1471 char addrbuf[128];
1472 log(EVDNS_LOG_WARN, "Error from libevent when adding event for %s",
1473 evutil_format_sockaddr_port(
1474 (struct sockaddr *)&ns->address,
1475 addrbuf, sizeof(addrbuf)));
1476 /* ???? Do more? */
1480 /* a callback function. Called by libevent when the kernel says that */
1481 /* a nameserver socket is ready for writing or reading */
1482 static void
1483 nameserver_ready_callback(evutil_socket_t fd, short events, void *arg) {
1484 struct nameserver *ns = (struct nameserver *) arg;
1485 (void)fd;
1487 EVDNS_LOCK(ns->base);
1488 if (events & EV_WRITE) {
1489 ns->choked = 0;
1490 if (!evdns_transmit(ns->base)) {
1491 nameserver_write_waiting(ns, 0);
1494 if (events & EV_READ) {
1495 nameserver_read(ns);
1497 EVDNS_UNLOCK(ns->base);
1500 /* a callback function. Called by libevent when the kernel says that */
1501 /* a server socket is ready for writing or reading. */
1502 static void
1503 server_port_ready_callback(evutil_socket_t fd, short events, void *arg) {
1504 struct evdns_server_port *port = (struct evdns_server_port *) arg;
1505 (void) fd;
1507 EVDNS_LOCK(port);
1508 if (events & EV_WRITE) {
1509 port->choked = 0;
1510 server_port_flush(port);
1512 if (events & EV_READ) {
1513 server_port_read(port);
1515 EVDNS_UNLOCK(port);
1518 /* This is an inefficient representation; only use it via the dnslabel_table_*
1519 * functions, so that is can be safely replaced with something smarter later. */
1520 #define MAX_LABELS 128
1521 /* Structures used to implement name compression */
1522 struct dnslabel_entry { char *v; off_t pos; };
1523 struct dnslabel_table {
1524 int n_labels; /* number of current entries */
1525 /* map from name to position in message */
1526 struct dnslabel_entry labels[MAX_LABELS];
1529 /* Initialize dnslabel_table. */
1530 static void
1531 dnslabel_table_init(struct dnslabel_table *table)
1533 table->n_labels = 0;
1536 /* Free all storage held by table, but not the table itself. */
1537 static void
1538 dnslabel_clear(struct dnslabel_table *table)
1540 int i;
1541 for (i = 0; i < table->n_labels; ++i)
1542 mm_free(table->labels[i].v);
1543 table->n_labels = 0;
1546 /* return the position of the label in the current message, or -1 if the label */
1547 /* hasn't been used yet. */
1548 static int
1549 dnslabel_table_get_pos(const struct dnslabel_table *table, const char *label)
1551 int i;
1552 for (i = 0; i < table->n_labels; ++i) {
1553 if (!strcmp(label, table->labels[i].v))
1554 return table->labels[i].pos;
1556 return -1;
1559 /* remember that we've used the label at position pos */
1560 static int
1561 dnslabel_table_add(struct dnslabel_table *table, const char *label, off_t pos)
1563 char *v;
1564 int p;
1565 if (table->n_labels == MAX_LABELS)
1566 return (-1);
1567 v = mm_strdup(label);
1568 if (v == NULL)
1569 return (-1);
1570 p = table->n_labels++;
1571 table->labels[p].v = v;
1572 table->labels[p].pos = pos;
1574 return (0);
1577 /* Converts a string to a length-prefixed set of DNS labels, starting */
1578 /* at buf[j]. name and buf must not overlap. name_len should be the length */
1579 /* of name. table is optional, and is used for compression. */
1580 /* */
1581 /* Input: abc.def */
1582 /* Output: <3>abc<3>def<0> */
1583 /* */
1584 /* Returns the first index after the encoded name, or negative on error. */
1585 /* -1 label was > 63 bytes */
1586 /* -2 name too long to fit in buffer. */
1587 /* */
1588 static off_t
1589 dnsname_to_labels(u8 *const buf, size_t buf_len, off_t j,
1590 const char *name, const size_t name_len,
1591 struct dnslabel_table *table) {
1592 const char *end = name + name_len;
1593 int ref = 0;
1594 u16 _t;
1596 #define APPEND16(x) do { \
1597 if (j + 2 > (off_t)buf_len) \
1598 goto overflow; \
1599 _t = htons(x); \
1600 memcpy(buf + j, &_t, 2); \
1601 j += 2; \
1602 } while (/*CONSTCOND*/0)
1603 #define APPEND32(x) do { \
1604 if (j + 4 > (off_t)buf_len) \
1605 goto overflow; \
1606 _t32 = htonl(x); \
1607 memcpy(buf + j, &_t32, 4); \
1608 j += 4; \
1609 } while (/*CONSTCOND*/0)
1611 if (name_len > 255) return -2;
1613 for (;;) {
1614 const char *const start = name;
1615 if (table && (ref = dnslabel_table_get_pos(table, name)) >= 0) {
1616 APPEND16(ref | 0xc000);
1617 return j;
1619 name = strchr(name, '.');
1620 if (!name) {
1621 const size_t label_len = end - start;
1622 if (label_len > 63) return -1;
1623 if ((size_t)(j+label_len+1) > buf_len) return -2;
1624 if (table) dnslabel_table_add(table, start, j);
1625 buf[j++] = (ev_uint8_t)label_len;
1627 memcpy(buf + j, start, label_len);
1628 j += (int) label_len;
1629 break;
1630 } else {
1631 /* append length of the label. */
1632 const size_t label_len = name - start;
1633 if (label_len > 63) return -1;
1634 if ((size_t)(j+label_len+1) > buf_len) return -2;
1635 if (table) dnslabel_table_add(table, start, j);
1636 buf[j++] = (ev_uint8_t)label_len;
1638 memcpy(buf + j, start, label_len);
1639 j += (int) label_len;
1640 /* hop over the '.' */
1641 name++;
1645 /* the labels must be terminated by a 0. */
1646 /* It's possible that the name ended in a . */
1647 /* in which case the zero is already there */
1648 if (!j || buf[j-1]) buf[j++] = 0;
1649 return j;
1650 overflow:
1651 return (-2);
1654 /* Finds the length of a dns request for a DNS name of the given */
1655 /* length. The actual request may be smaller than the value returned */
1656 /* here */
1657 static size_t
1658 evdns_request_len(const size_t name_len) {
1659 return 96 + /* length of the DNS standard header */
1660 name_len + 2 +
1661 4; /* space for the resource type */
1664 /* build a dns request packet into buf. buf should be at least as long */
1665 /* as evdns_request_len told you it should be. */
1666 /* */
1667 /* Returns the amount of space used. Negative on error. */
1668 static int
1669 evdns_request_data_build(const char *const name, const size_t name_len,
1670 const u16 trans_id, const u16 type, const u16 class,
1671 u8 *const buf, size_t buf_len) {
1672 off_t j = 0; /* current offset into buf */
1673 u16 _t; /* used by the macros */
1675 APPEND16(trans_id);
1676 APPEND16(0x0100); /* standard query, recusion needed */
1677 APPEND16(1); /* one question */
1678 APPEND16(0); /* no answers */
1679 APPEND16(0); /* no authority */
1680 APPEND16(0); /* no additional */
1682 j = dnsname_to_labels(buf, buf_len, j, name, name_len, NULL);
1683 if (j < 0) {
1684 return (int)j;
1687 APPEND16(type);
1688 APPEND16(class);
1690 return (int)j;
1691 overflow:
1692 return (-1);
1695 /* exported function */
1696 struct evdns_server_port *
1697 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)
1699 struct evdns_server_port *port;
1700 if (flags)
1701 return NULL; /* flags not yet implemented */
1702 if (!(port = mm_malloc(sizeof(struct evdns_server_port))))
1703 return NULL;
1704 memset(port, 0, sizeof(struct evdns_server_port));
1707 port->socket = socket;
1708 port->refcnt = 1;
1709 port->choked = 0;
1710 port->closing = 0;
1711 port->user_callback = cb;
1712 port->user_data = user_data;
1713 port->pending_replies = NULL;
1714 port->event_base = base;
1716 event_assign(&port->event, port->event_base,
1717 port->socket, EV_READ | EV_PERSIST,
1718 server_port_ready_callback, port);
1719 if (event_add(&port->event, NULL) < 0) {
1720 mm_free(port);
1721 return NULL;
1723 EVTHREAD_ALLOC_LOCK(port->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
1724 return port;
1727 struct evdns_server_port *
1728 evdns_add_server_port(evutil_socket_t socket, int flags, evdns_request_callback_fn_type cb, void *user_data)
1730 return evdns_add_server_port_with_base(NULL, socket, flags, cb, user_data);
1733 /* exported function */
1734 void
1735 evdns_close_server_port(struct evdns_server_port *port)
1737 EVDNS_LOCK(port);
1738 if (--port->refcnt == 0) {
1739 EVDNS_UNLOCK(port);
1740 server_port_free(port);
1741 } else {
1742 port->closing = 1;
1746 /* exported function */
1748 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)
1750 struct server_request *req = TO_SERVER_REQUEST(_req);
1751 struct server_reply_item **itemp, *item;
1752 int *countp;
1753 int result = -1;
1755 EVDNS_LOCK(req->port);
1756 if (req->response) /* have we already answered? */
1757 goto done;
1759 switch (section) {
1760 case EVDNS_ANSWER_SECTION:
1761 itemp = &req->answer;
1762 countp = &req->n_answer;
1763 break;
1764 case EVDNS_AUTHORITY_SECTION:
1765 itemp = &req->authority;
1766 countp = &req->n_authority;
1767 break;
1768 case EVDNS_ADDITIONAL_SECTION:
1769 itemp = &req->additional;
1770 countp = &req->n_additional;
1771 break;
1772 default:
1773 goto done;
1775 while (*itemp) {
1776 itemp = &((*itemp)->next);
1778 item = mm_malloc(sizeof(struct server_reply_item));
1779 if (!item)
1780 goto done;
1781 item->next = NULL;
1782 if (!(item->name = mm_strdup(name))) {
1783 mm_free(item);
1784 goto done;
1786 item->type = type;
1787 item->dns_question_class = class;
1788 item->ttl = ttl;
1789 item->is_name = is_name != 0;
1790 item->datalen = 0;
1791 item->data = NULL;
1792 if (data) {
1793 if (item->is_name) {
1794 if (!(item->data = mm_strdup(data))) {
1795 mm_free(item->name);
1796 mm_free(item);
1797 goto done;
1799 item->datalen = (u16)-1;
1800 } else {
1801 if (!(item->data = mm_malloc(datalen))) {
1802 mm_free(item->name);
1803 mm_free(item);
1804 goto done;
1806 item->datalen = datalen;
1807 memcpy(item->data, data, datalen);
1811 *itemp = item;
1812 ++(*countp);
1813 result = 0;
1814 done:
1815 EVDNS_UNLOCK(req->port);
1816 return result;
1819 /* exported function */
1821 evdns_server_request_add_a_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl)
1823 return evdns_server_request_add_reply(
1824 req, EVDNS_ANSWER_SECTION, name, TYPE_A, CLASS_INET,
1825 ttl, n*4, 0, addrs);
1828 /* exported function */
1830 evdns_server_request_add_aaaa_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl)
1832 return evdns_server_request_add_reply(
1833 req, EVDNS_ANSWER_SECTION, name, TYPE_AAAA, CLASS_INET,
1834 ttl, n*16, 0, addrs);
1837 /* exported function */
1839 evdns_server_request_add_ptr_reply(struct evdns_server_request *req, struct in_addr *in, const char *inaddr_name, const char *hostname, int ttl)
1841 u32 a;
1842 char buf[32];
1843 if (in && inaddr_name)
1844 return -1;
1845 else if (!in && !inaddr_name)
1846 return -1;
1847 if (in) {
1848 a = ntohl(in->s_addr);
1849 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa",
1850 (int)(u8)((a )&0xff),
1851 (int)(u8)((a>>8 )&0xff),
1852 (int)(u8)((a>>16)&0xff),
1853 (int)(u8)((a>>24)&0xff));
1854 inaddr_name = buf;
1856 return evdns_server_request_add_reply(
1857 req, EVDNS_ANSWER_SECTION, inaddr_name, TYPE_PTR, CLASS_INET,
1858 ttl, -1, 1, hostname);
1861 /* exported function */
1863 evdns_server_request_add_cname_reply(struct evdns_server_request *req, const char *name, const char *cname, int ttl)
1865 return evdns_server_request_add_reply(
1866 req, EVDNS_ANSWER_SECTION, name, TYPE_CNAME, CLASS_INET,
1867 ttl, -1, 1, cname);
1870 /* exported function */
1871 void
1872 evdns_server_request_set_flags(struct evdns_server_request *exreq, int flags)
1874 struct server_request *req = TO_SERVER_REQUEST(exreq);
1875 req->base.flags &= ~(EVDNS_FLAGS_AA|EVDNS_FLAGS_RD);
1876 req->base.flags |= flags;
1879 static int
1880 evdns_server_request_format_response(struct server_request *req, int err)
1882 unsigned char buf[1500];
1883 size_t buf_len = sizeof(buf);
1884 off_t j = 0, r;
1885 u16 _t;
1886 u32 _t32;
1887 int i;
1888 u16 flags;
1889 struct dnslabel_table table;
1891 if (err < 0 || err > 15) return -1;
1893 /* Set response bit and error code; copy OPCODE and RD fields from
1894 * question; copy RA and AA if set by caller. */
1895 flags = req->base.flags;
1896 flags |= (0x8000 | err);
1898 dnslabel_table_init(&table);
1899 APPEND16(req->trans_id);
1900 APPEND16(flags);
1901 APPEND16(req->base.nquestions);
1902 APPEND16(req->n_answer);
1903 APPEND16(req->n_authority);
1904 APPEND16(req->n_additional);
1906 /* Add questions. */
1907 for (i=0; i < req->base.nquestions; ++i) {
1908 const char *s = req->base.questions[i]->name;
1909 j = dnsname_to_labels(buf, buf_len, j, s, strlen(s), &table);
1910 if (j < 0) {
1911 dnslabel_clear(&table);
1912 return (int) j;
1914 APPEND16(req->base.questions[i]->type);
1915 APPEND16(req->base.questions[i]->dns_question_class);
1918 /* Add answer, authority, and additional sections. */
1919 for (i=0; i<3; ++i) {
1920 struct server_reply_item *item;
1921 if (i==0)
1922 item = req->answer;
1923 else if (i==1)
1924 item = req->authority;
1925 else
1926 item = req->additional;
1927 while (item) {
1928 r = dnsname_to_labels(buf, buf_len, j, item->name, strlen(item->name), &table);
1929 if (r < 0)
1930 goto overflow;
1931 j = r;
1933 APPEND16(item->type);
1934 APPEND16(item->dns_question_class);
1935 APPEND32(item->ttl);
1936 if (item->is_name) {
1937 off_t len_idx = j, name_start;
1938 j += 2;
1939 name_start = j;
1940 r = dnsname_to_labels(buf, buf_len, j, item->data, strlen(item->data), &table);
1941 if (r < 0)
1942 goto overflow;
1943 j = r;
1944 _t = htons( (short) (j-name_start) );
1945 memcpy(buf+len_idx, &_t, 2);
1946 } else {
1947 APPEND16(item->datalen);
1948 if (j+item->datalen > (off_t)buf_len)
1949 goto overflow;
1950 memcpy(buf+j, item->data, item->datalen);
1951 j += item->datalen;
1953 item = item->next;
1957 if (j > 512) {
1958 overflow:
1959 j = 512;
1960 buf[2] |= 0x02; /* set the truncated bit. */
1963 req->response_len = j;
1965 if (!(req->response = mm_malloc(req->response_len))) {
1966 server_request_free_answers(req);
1967 dnslabel_clear(&table);
1968 return (-1);
1970 memcpy(req->response, buf, req->response_len);
1971 server_request_free_answers(req);
1972 dnslabel_clear(&table);
1973 return (0);
1976 /* exported function */
1978 evdns_server_request_respond(struct evdns_server_request *_req, int err)
1980 struct server_request *req = TO_SERVER_REQUEST(_req);
1981 struct evdns_server_port *port = req->port;
1982 int r = -1;
1984 EVDNS_LOCK(port);
1985 if (!req->response) {
1986 if ((r = evdns_server_request_format_response(req, err))<0)
1987 goto done;
1990 r = sendto(port->socket, req->response, (int)req->response_len, 0,
1991 (struct sockaddr*) &req->addr, (ev_socklen_t)req->addrlen);
1992 if (r<0) {
1993 int sock_err = evutil_socket_geterror(port->socket);
1994 if (EVUTIL_ERR_RW_RETRIABLE(sock_err))
1995 goto done;
1997 if (port->pending_replies) {
1998 req->prev_pending = port->pending_replies->prev_pending;
1999 req->next_pending = port->pending_replies;
2000 req->prev_pending->next_pending =
2001 req->next_pending->prev_pending = req;
2002 } else {
2003 req->prev_pending = req->next_pending = req;
2004 port->pending_replies = req;
2005 port->choked = 1;
2007 (void) event_del(&port->event);
2008 event_assign(&port->event, port->event_base, port->socket, (port->closing?0:EV_READ) | EV_WRITE | EV_PERSIST, server_port_ready_callback, port);
2010 if (event_add(&port->event, NULL) < 0) {
2011 log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server");
2016 r = 1;
2017 goto done;
2019 if (server_request_free(req)) {
2020 r = 0;
2021 goto done;
2024 if (port->pending_replies)
2025 server_port_flush(port);
2027 r = 0;
2028 done:
2029 EVDNS_UNLOCK(port);
2030 return r;
2033 /* Free all storage held by RRs in req. */
2034 static void
2035 server_request_free_answers(struct server_request *req)
2037 struct server_reply_item *victim, *next, **list;
2038 int i;
2039 for (i = 0; i < 3; ++i) {
2040 if (i==0)
2041 list = &req->answer;
2042 else if (i==1)
2043 list = &req->authority;
2044 else
2045 list = &req->additional;
2047 victim = *list;
2048 while (victim) {
2049 next = victim->next;
2050 mm_free(victim->name);
2051 if (victim->data)
2052 mm_free(victim->data);
2053 mm_free(victim);
2054 victim = next;
2056 *list = NULL;
2060 /* Free all storage held by req, and remove links to it. */
2061 /* return true iff we just wound up freeing the server_port. */
2062 static int
2063 server_request_free(struct server_request *req)
2065 int i, rc=1, lock=0;
2066 if (req->base.questions) {
2067 for (i = 0; i < req->base.nquestions; ++i)
2068 mm_free(req->base.questions[i]);
2069 mm_free(req->base.questions);
2072 if (req->port) {
2073 EVDNS_LOCK(req->port);
2074 lock=1;
2075 if (req->port->pending_replies == req) {
2076 if (req->next_pending && req->next_pending != req)
2077 req->port->pending_replies = req->next_pending;
2078 else
2079 req->port->pending_replies = NULL;
2081 rc = --req->port->refcnt;
2084 if (req->response) {
2085 mm_free(req->response);
2088 server_request_free_answers(req);
2090 if (req->next_pending && req->next_pending != req) {
2091 req->next_pending->prev_pending = req->prev_pending;
2092 req->prev_pending->next_pending = req->next_pending;
2095 if (rc == 0) {
2096 EVDNS_UNLOCK(req->port); /* ????? nickm */
2097 server_port_free(req->port);
2098 mm_free(req);
2099 return (1);
2101 if (lock)
2102 EVDNS_UNLOCK(req->port);
2103 mm_free(req);
2104 return (0);
2107 /* Free all storage held by an evdns_server_port. Only called when */
2108 static void
2109 server_port_free(struct evdns_server_port *port)
2111 EVUTIL_ASSERT(port);
2112 EVUTIL_ASSERT(!port->refcnt);
2113 EVUTIL_ASSERT(!port->pending_replies);
2114 if (port->socket > 0) {
2115 evutil_closesocket(port->socket);
2116 port->socket = -1;
2118 (void) event_del(&port->event);
2119 event_debug_unassign(&port->event);
2120 EVTHREAD_FREE_LOCK(port->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
2121 mm_free(port);
2124 /* exported function */
2126 evdns_server_request_drop(struct evdns_server_request *_req)
2128 struct server_request *req = TO_SERVER_REQUEST(_req);
2129 server_request_free(req);
2130 return 0;
2133 /* exported function */
2135 evdns_server_request_get_requesting_addr(struct evdns_server_request *_req, struct sockaddr *sa, int addr_len)
2137 struct server_request *req = TO_SERVER_REQUEST(_req);
2138 if (addr_len < (int)req->addrlen)
2139 return -1;
2140 memcpy(sa, &(req->addr), req->addrlen);
2141 return req->addrlen;
2144 #undef APPEND16
2145 #undef APPEND32
2147 /* this is a libevent callback function which is called when a request */
2148 /* has timed out. */
2149 static void
2150 evdns_request_timeout_callback(evutil_socket_t fd, short events, void *arg) {
2151 struct request *const req = (struct request *) arg;
2152 struct evdns_base *base = req->base;
2154 (void) fd;
2155 (void) events;
2157 log(EVDNS_LOG_DEBUG, "Request %p timed out", arg);
2158 EVDNS_LOCK(base);
2160 req->ns->timedout++;
2161 if (req->ns->timedout > req->base->global_max_nameserver_timeout) {
2162 req->ns->timedout = 0;
2163 nameserver_failed(req->ns, "request timed out.");
2166 if (req->tx_count >= req->base->global_max_retransmits) {
2167 /* this request has failed */
2168 log(EVDNS_LOG_DEBUG, "Giving up on request %p; tx_count==%d",
2169 arg, req->tx_count);
2170 reply_schedule_callback(req, 0, DNS_ERR_TIMEOUT, NULL);
2171 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1);
2172 } else {
2173 /* retransmit it */
2174 struct nameserver *new_ns;
2175 log(EVDNS_LOG_DEBUG, "Retransmitting request %p; tx_count==%d",
2176 arg, req->tx_count);
2177 (void) evtimer_del(&req->timeout_event);
2178 new_ns = nameserver_pick(base);
2179 if (new_ns)
2180 req->ns = new_ns;
2181 evdns_request_transmit(req);
2183 EVDNS_UNLOCK(base);
2186 /* try to send a request to a given server. */
2187 /* */
2188 /* return: */
2189 /* 0 ok */
2190 /* 1 temporary failure */
2191 /* 2 other failure */
2192 static int
2193 evdns_request_transmit_to(struct request *req, struct nameserver *server) {
2194 int r;
2195 ASSERT_LOCKED(req->base);
2196 ASSERT_VALID_REQUEST(req);
2197 r = sendto(server->socket, (void*)req->request, req->request_len, 0,
2198 (struct sockaddr *)&server->address, server->addrlen);
2199 if (r < 0) {
2200 int err = evutil_socket_geterror(server->socket);
2201 if (EVUTIL_ERR_RW_RETRIABLE(err))
2202 return 1;
2203 nameserver_failed(req->ns, evutil_socket_error_to_string(err));
2204 return 2;
2205 } else if (r != (int)req->request_len) {
2206 return 1; /* short write */
2207 } else {
2208 return 0;
2212 /* try to send a request, updating the fields of the request */
2213 /* as needed */
2214 /* */
2215 /* return: */
2216 /* 0 ok */
2217 /* 1 failed */
2218 static int
2219 evdns_request_transmit(struct request *req) {
2220 int retcode = 0, r;
2222 ASSERT_LOCKED(req->base);
2223 ASSERT_VALID_REQUEST(req);
2224 /* if we fail to send this packet then this flag marks it */
2225 /* for evdns_transmit */
2226 req->transmit_me = 1;
2227 EVUTIL_ASSERT(req->trans_id != 0xffff);
2229 if (!req->ns)
2231 /* unable to transmit request if no nameservers */
2232 return 1;
2235 if (req->ns->choked) {
2236 /* don't bother trying to write to a socket */
2237 /* which we have had EAGAIN from */
2238 return 1;
2241 r = evdns_request_transmit_to(req, req->ns);
2242 switch (r) {
2243 case 1:
2244 /* temp failure */
2245 req->ns->choked = 1;
2246 nameserver_write_waiting(req->ns, 1);
2247 return 1;
2248 case 2:
2249 /* failed to transmit the request entirely. */
2250 retcode = 1;
2251 /* fall through: we'll set a timeout, which will time out,
2252 * and make us retransmit the request anyway. */
2253 default:
2254 /* all ok */
2255 log(EVDNS_LOG_DEBUG,
2256 "Setting timeout for request %p, sent to nameserver %p", req, req->ns);
2257 if (evtimer_add(&req->timeout_event, &req->base->global_timeout) < 0) {
2258 log(EVDNS_LOG_WARN,
2259 "Error from libevent when adding timer for request %p",
2260 req);
2261 /* ???? Do more? */
2263 req->tx_count++;
2264 req->transmit_me = 0;
2265 return retcode;
2269 static void
2270 nameserver_probe_callback(int result, char type, int count, int ttl, void *addresses, void *arg) {
2271 struct nameserver *const ns = (struct nameserver *) arg;
2272 (void) type;
2273 (void) count;
2274 (void) ttl;
2275 (void) addresses;
2277 if (result == DNS_ERR_CANCEL) {
2278 /* We canceled this request because the nameserver came up
2279 * for some other reason. Do not change our opinion about
2280 * the nameserver. */
2281 return;
2284 EVDNS_LOCK(ns->base);
2285 ns->probe_request = NULL;
2286 if (result == DNS_ERR_NONE || result == DNS_ERR_NOTEXIST) {
2287 /* this is a good reply */
2288 nameserver_up(ns);
2289 } else {
2290 nameserver_probe_failed(ns);
2292 EVDNS_UNLOCK(ns->base);
2295 static void
2296 nameserver_send_probe(struct nameserver *const ns) {
2297 struct evdns_request *handle;
2298 struct request *req;
2299 char addrbuf[128];
2300 /* here we need to send a probe to a given nameserver */
2301 /* in the hope that it is up now. */
2303 ASSERT_LOCKED(ns->base);
2304 log(EVDNS_LOG_DEBUG, "Sending probe to %s",
2305 evutil_format_sockaddr_port(
2306 (struct sockaddr *)&ns->address,
2307 addrbuf, sizeof(addrbuf)));
2308 handle = mm_calloc(1, sizeof(*handle));
2309 if (!handle) return;
2310 req = request_new(ns->base, handle, TYPE_A, "google.com", DNS_QUERY_NO_SEARCH, nameserver_probe_callback, ns);
2311 if (!req) {
2312 mm_free(handle);
2313 return;
2315 ns->probe_request = handle;
2316 /* we force this into the inflight queue no matter what */
2317 request_trans_id_set(req, transaction_id_pick(ns->base));
2318 req->ns = ns;
2319 request_submit(req);
2322 /* returns: */
2323 /* 0 didn't try to transmit anything */
2324 /* 1 tried to transmit something */
2325 static int
2326 evdns_transmit(struct evdns_base *base) {
2327 char did_try_to_transmit = 0;
2328 int i;
2330 ASSERT_LOCKED(base);
2331 for (i = 0; i < base->n_req_heads; ++i) {
2332 if (base->req_heads[i]) {
2333 struct request *const started_at = base->req_heads[i], *req = started_at;
2334 /* first transmit all the requests which are currently waiting */
2335 do {
2336 if (req->transmit_me) {
2337 did_try_to_transmit = 1;
2338 evdns_request_transmit(req);
2341 req = req->next;
2342 } while (req != started_at);
2346 return did_try_to_transmit;
2349 /* exported function */
2351 evdns_base_count_nameservers(struct evdns_base *base)
2353 const struct nameserver *server;
2354 int n = 0;
2356 EVDNS_LOCK(base);
2357 server = base->server_head;
2358 if (!server)
2359 goto done;
2360 do {
2361 ++n;
2362 server = server->next;
2363 } while (server != base->server_head);
2364 done:
2365 EVDNS_UNLOCK(base);
2366 return n;
2370 evdns_count_nameservers(void)
2372 return evdns_base_count_nameservers(current_base);
2375 /* exported function */
2377 evdns_base_clear_nameservers_and_suspend(struct evdns_base *base)
2379 struct nameserver *server, *started_at;
2380 int i;
2382 EVDNS_LOCK(base);
2383 server = base->server_head;
2384 started_at = base->server_head;
2385 if (!server) {
2386 EVDNS_UNLOCK(base);
2387 return 0;
2389 while (1) {
2390 struct nameserver *next = server->next;
2391 (void) event_del(&server->event);
2392 if (evtimer_initialized(&server->timeout_event))
2393 (void) evtimer_del(&server->timeout_event);
2394 if (server->probe_request) {
2395 evdns_cancel_request(server->base, server->probe_request);
2396 server->probe_request = NULL;
2398 if (server->socket >= 0)
2399 evutil_closesocket(server->socket);
2400 mm_free(server);
2401 if (next == started_at)
2402 break;
2403 server = next;
2405 base->server_head = NULL;
2406 base->global_good_nameservers = 0;
2408 for (i = 0; i < base->n_req_heads; ++i) {
2409 struct request *req, *req_started_at;
2410 req = req_started_at = base->req_heads[i];
2411 while (req) {
2412 struct request *next = req->next;
2413 req->tx_count = req->reissue_count = 0;
2414 req->ns = NULL;
2415 /* ???? What to do about searches? */
2416 (void) evtimer_del(&req->timeout_event);
2417 req->trans_id = 0;
2418 req->transmit_me = 0;
2420 base->global_requests_waiting++;
2421 evdns_request_insert(req, &base->req_waiting_head);
2422 /* We want to insert these suspended elements at the front of
2423 * the waiting queue, since they were pending before any of
2424 * the waiting entries were added. This is a circular list,
2425 * so we can just shift the start back by one.*/
2426 base->req_waiting_head = base->req_waiting_head->prev;
2428 if (next == req_started_at)
2429 break;
2430 req = next;
2432 base->req_heads[i] = NULL;
2435 base->global_requests_inflight = 0;
2437 EVDNS_UNLOCK(base);
2438 return 0;
2442 evdns_clear_nameservers_and_suspend(void)
2444 return evdns_base_clear_nameservers_and_suspend(current_base);
2448 /* exported function */
2450 evdns_base_resume(struct evdns_base *base)
2452 EVDNS_LOCK(base);
2453 evdns_requests_pump_waiting_queue(base);
2454 EVDNS_UNLOCK(base);
2456 return 0;
2460 evdns_resume(void)
2462 return evdns_base_resume(current_base);
2465 static int
2466 _evdns_nameserver_add_impl(struct evdns_base *base, const struct sockaddr *address, int addrlen) {
2467 /* first check to see if we already have this nameserver */
2469 const struct nameserver *server = base->server_head, *const started_at = base->server_head;
2470 struct nameserver *ns;
2471 int err = 0;
2472 char addrbuf[128];
2474 ASSERT_LOCKED(base);
2475 if (server) {
2476 do {
2477 if (!evutil_sockaddr_cmp((const struct sockaddr*)&server->address, address, 1)) return 3;
2478 server = server->next;
2479 } while (server != started_at);
2481 if (addrlen > (int)sizeof(ns->address)) {
2482 log(EVDNS_LOG_DEBUG, "Addrlen %d too long.", (int)addrlen);
2483 return 2;
2486 ns = (struct nameserver *) mm_malloc(sizeof(struct nameserver));
2487 if (!ns) return -1;
2489 memset(ns, 0, sizeof(struct nameserver));
2490 ns->base = base;
2492 evtimer_assign(&ns->timeout_event, ns->base->event_base, nameserver_prod_callback, ns);
2494 ns->socket = socket(address->sa_family, SOCK_DGRAM, 0);
2495 if (ns->socket < 0) { err = 1; goto out1; }
2496 evutil_make_socket_closeonexec(ns->socket);
2497 evutil_make_socket_nonblocking(ns->socket);
2499 if (base->global_outgoing_addrlen &&
2500 !evutil_sockaddr_is_loopback(address)) {
2501 if (bind(ns->socket,
2502 (struct sockaddr*)&base->global_outgoing_address,
2503 base->global_outgoing_addrlen) < 0) {
2504 log(EVDNS_LOG_WARN,"Couldn't bind to outgoing address");
2505 err = 2;
2506 goto out2;
2510 memcpy(&ns->address, address, addrlen);
2511 ns->addrlen = addrlen;
2512 ns->state = 1;
2513 event_assign(&ns->event, ns->base->event_base, ns->socket, EV_READ | EV_PERSIST, nameserver_ready_callback, ns);
2514 if (event_add(&ns->event, NULL) < 0) {
2515 err = 2;
2516 goto out2;
2519 log(EVDNS_LOG_DEBUG, "Added nameserver %s as %p",
2520 evutil_format_sockaddr_port(address, addrbuf, sizeof(addrbuf)), ns);
2522 /* insert this nameserver into the list of them */
2523 if (!base->server_head) {
2524 ns->next = ns->prev = ns;
2525 base->server_head = ns;
2526 } else {
2527 ns->next = base->server_head->next;
2528 ns->prev = base->server_head;
2529 base->server_head->next = ns;
2530 ns->next->prev = ns;
2533 base->global_good_nameservers++;
2535 return 0;
2537 out2:
2538 evutil_closesocket(ns->socket);
2539 out1:
2540 event_debug_unassign(&ns->event);
2541 mm_free(ns);
2542 log(EVDNS_LOG_WARN, "Unable to add nameserver %s: error %d",
2543 evutil_format_sockaddr_port(address, addrbuf, sizeof(addrbuf)), err);
2544 return err;
2547 /* exported function */
2549 evdns_base_nameserver_add(struct evdns_base *base, unsigned long int address)
2551 struct sockaddr_in sin;
2552 int res;
2553 memset(&sin, 0, sizeof(sin));
2554 sin.sin_addr.s_addr = address;
2555 sin.sin_port = htons(53);
2556 sin.sin_family = AF_INET;
2557 EVDNS_LOCK(base);
2558 res = _evdns_nameserver_add_impl(base, (struct sockaddr*)&sin, sizeof(sin));
2559 EVDNS_UNLOCK(base);
2560 return res;
2564 evdns_nameserver_add(unsigned long int address) {
2565 if (!current_base)
2566 current_base = evdns_base_new(NULL, 0);
2567 return evdns_base_nameserver_add(current_base, address);
2570 static void
2571 sockaddr_setport(struct sockaddr *sa, ev_uint16_t port)
2573 if (sa->sa_family == AF_INET) {
2574 ((struct sockaddr_in *)sa)->sin_port = htons(port);
2575 } else if (sa->sa_family == AF_INET6) {
2576 ((struct sockaddr_in6 *)sa)->sin6_port = htons(port);
2580 static ev_uint16_t
2581 sockaddr_getport(struct sockaddr *sa)
2583 if (sa->sa_family == AF_INET) {
2584 return ntohs(((struct sockaddr_in *)sa)->sin_port);
2585 } else if (sa->sa_family == AF_INET6) {
2586 return ntohs(((struct sockaddr_in6 *)sa)->sin6_port);
2587 } else {
2588 return 0;
2592 /* exported function */
2594 evdns_base_nameserver_ip_add(struct evdns_base *base, const char *ip_as_string) {
2595 struct sockaddr_storage ss;
2596 struct sockaddr *sa;
2597 int len = sizeof(ss);
2598 int res;
2599 if (evutil_parse_sockaddr_port(ip_as_string, (struct sockaddr *)&ss,
2600 &len)) {
2601 log(EVDNS_LOG_WARN, "Unable to parse nameserver address %s",
2602 ip_as_string);
2603 return 4;
2605 sa = (struct sockaddr *) &ss;
2606 if (sockaddr_getport(sa) == 0)
2607 sockaddr_setport(sa, 53);
2609 EVDNS_LOCK(base);
2610 res = _evdns_nameserver_add_impl(base, sa, len);
2611 EVDNS_UNLOCK(base);
2612 return res;
2616 evdns_nameserver_ip_add(const char *ip_as_string) {
2617 if (!current_base)
2618 current_base = evdns_base_new(NULL, 0);
2619 return evdns_base_nameserver_ip_add(current_base, ip_as_string);
2623 evdns_base_nameserver_sockaddr_add(struct evdns_base *base,
2624 const struct sockaddr *sa, ev_socklen_t len, unsigned flags)
2626 int res;
2627 EVUTIL_ASSERT(base);
2628 EVDNS_LOCK(base);
2629 res = _evdns_nameserver_add_impl(base, sa, len);
2630 EVDNS_UNLOCK(base);
2631 return res;
2634 /* remove from the queue */
2635 static void
2636 evdns_request_remove(struct request *req, struct request **head)
2638 ASSERT_LOCKED(req->base);
2639 ASSERT_VALID_REQUEST(req);
2641 #if 0
2643 struct request *ptr;
2644 int found = 0;
2645 EVUTIL_ASSERT(*head != NULL);
2647 ptr = *head;
2648 do {
2649 if (ptr == req) {
2650 found = 1;
2651 break;
2653 ptr = ptr->next;
2654 } while (ptr != *head);
2655 EVUTIL_ASSERT(found);
2657 EVUTIL_ASSERT(req->next);
2659 #endif
2661 if (req->next == req) {
2662 /* only item in the list */
2663 *head = NULL;
2664 } else {
2665 req->next->prev = req->prev;
2666 req->prev->next = req->next;
2667 if (*head == req) *head = req->next;
2669 req->next = req->prev = NULL;
2672 /* insert into the tail of the queue */
2673 static void
2674 evdns_request_insert(struct request *req, struct request **head) {
2675 ASSERT_LOCKED(req->base);
2676 ASSERT_VALID_REQUEST(req);
2677 if (!*head) {
2678 *head = req;
2679 req->next = req->prev = req;
2680 return;
2683 req->prev = (*head)->prev;
2684 req->prev->next = req;
2685 req->next = *head;
2686 (*head)->prev = req;
2689 static int
2690 string_num_dots(const char *s) {
2691 int count = 0;
2692 while ((s = strchr(s, '.'))) {
2693 s++;
2694 count++;
2696 return count;
2699 static struct request *
2700 request_new(struct evdns_base *base, struct evdns_request *handle, int type,
2701 const char *name, int flags, evdns_callback_type callback,
2702 void *user_ptr) {
2704 const char issuing_now =
2705 (base->global_requests_inflight < base->global_max_requests_inflight) ? 1 : 0;
2707 const size_t name_len = strlen(name);
2708 const size_t request_max_len = evdns_request_len(name_len);
2709 const u16 trans_id = issuing_now ? transaction_id_pick(base) : 0xffff;
2710 /* the request data is alloced in a single block with the header */
2711 struct request *const req =
2712 mm_malloc(sizeof(struct request) + request_max_len);
2713 int rlen;
2714 char namebuf[256];
2715 (void) flags;
2717 ASSERT_LOCKED(base);
2719 if (!req) return NULL;
2721 if (name_len >= sizeof(namebuf)) {
2722 mm_free(req);
2723 return NULL;
2726 memset(req, 0, sizeof(struct request));
2727 req->base = base;
2729 evtimer_assign(&req->timeout_event, req->base->event_base, evdns_request_timeout_callback, req);
2731 if (base->global_randomize_case) {
2732 unsigned i;
2733 char randbits[(sizeof(namebuf)+7)/8];
2734 strlcpy(namebuf, name, sizeof(namebuf));
2735 evutil_secure_rng_get_bytes(randbits, (name_len+7)/8);
2736 for (i = 0; i < name_len; ++i) {
2737 if (EVUTIL_ISALPHA(namebuf[i])) {
2738 if ((randbits[i >> 3] & (1<<(i & 7))))
2739 namebuf[i] |= 0x20;
2740 else
2741 namebuf[i] &= ~0x20;
2744 name = namebuf;
2747 /* request data lives just after the header */
2748 req->request = ((u8 *) req) + sizeof(struct request);
2749 /* denotes that the request data shouldn't be free()ed */
2750 req->request_appended = 1;
2751 rlen = evdns_request_data_build(name, name_len, trans_id,
2752 type, CLASS_INET, req->request, request_max_len);
2753 if (rlen < 0)
2754 goto err1;
2756 req->request_len = rlen;
2757 req->trans_id = trans_id;
2758 req->tx_count = 0;
2759 req->request_type = type;
2760 req->user_pointer = user_ptr;
2761 req->user_callback = callback;
2762 req->ns = issuing_now ? nameserver_pick(base) : NULL;
2763 req->next = req->prev = NULL;
2764 req->handle = handle;
2765 if (handle) {
2766 handle->current_req = req;
2767 handle->base = base;
2770 return req;
2771 err1:
2772 mm_free(req);
2773 return NULL;
2776 static void
2777 request_submit(struct request *const req) {
2778 struct evdns_base *base = req->base;
2779 ASSERT_LOCKED(base);
2780 ASSERT_VALID_REQUEST(req);
2781 if (req->ns) {
2782 /* if it has a nameserver assigned then this is going */
2783 /* straight into the inflight queue */
2784 evdns_request_insert(req, &REQ_HEAD(base, req->trans_id));
2785 base->global_requests_inflight++;
2786 evdns_request_transmit(req);
2787 } else {
2788 evdns_request_insert(req, &base->req_waiting_head);
2789 base->global_requests_waiting++;
2793 /* exported function */
2794 void
2795 evdns_cancel_request(struct evdns_base *base, struct evdns_request *handle)
2797 struct request *req;
2799 if (!handle->current_req)
2800 return;
2802 if (!base) {
2803 /* This redundancy is silly; can we fix it? (Not for 2.0) XXXX */
2804 base = handle->base;
2805 if (!base)
2806 base = handle->current_req->base;
2809 EVDNS_LOCK(base);
2810 if (handle->pending_cb) {
2811 EVDNS_UNLOCK(base);
2812 return;
2815 req = handle->current_req;
2816 ASSERT_VALID_REQUEST(req);
2818 reply_schedule_callback(req, 0, DNS_ERR_CANCEL, NULL);
2819 if (req->ns) {
2820 /* remove from inflight queue */
2821 request_finished(req, &REQ_HEAD(base, req->trans_id), 1);
2822 } else {
2823 /* remove from global_waiting head */
2824 request_finished(req, &base->req_waiting_head, 1);
2826 EVDNS_UNLOCK(base);
2829 /* exported function */
2830 struct evdns_request *
2831 evdns_base_resolve_ipv4(struct evdns_base *base, const char *name, int flags,
2832 evdns_callback_type callback, void *ptr) {
2833 struct evdns_request *handle;
2834 struct request *req;
2835 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name);
2836 handle = mm_calloc(1, sizeof(*handle));
2837 if (handle == NULL)
2838 return NULL;
2839 EVDNS_LOCK(base);
2840 if (flags & DNS_QUERY_NO_SEARCH) {
2841 req =
2842 request_new(base, handle, TYPE_A, name, flags,
2843 callback, ptr);
2844 if (req)
2845 request_submit(req);
2846 } else {
2847 search_request_new(base, handle, TYPE_A, name, flags,
2848 callback, ptr);
2850 if (handle->current_req == NULL) {
2851 mm_free(handle);
2852 handle = NULL;
2854 EVDNS_UNLOCK(base);
2855 return handle;
2858 int evdns_resolve_ipv4(const char *name, int flags,
2859 evdns_callback_type callback, void *ptr)
2861 return evdns_base_resolve_ipv4(current_base, name, flags, callback, ptr)
2862 ? 0 : -1;
2866 /* exported function */
2867 struct evdns_request *
2868 evdns_base_resolve_ipv6(struct evdns_base *base,
2869 const char *name, int flags,
2870 evdns_callback_type callback, void *ptr)
2872 struct evdns_request *handle;
2873 struct request *req;
2874 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name);
2875 handle = mm_calloc(1, sizeof(*handle));
2876 if (handle == NULL)
2877 return NULL;
2878 EVDNS_LOCK(base);
2879 if (flags & DNS_QUERY_NO_SEARCH) {
2880 req = request_new(base, handle, TYPE_AAAA, name, flags,
2881 callback, ptr);
2882 if (req)
2883 request_submit(req);
2884 } else {
2885 search_request_new(base, handle, TYPE_AAAA, name, flags,
2886 callback, ptr);
2888 if (handle->current_req == NULL) {
2889 mm_free(handle);
2890 handle = NULL;
2892 EVDNS_UNLOCK(base);
2893 return handle;
2896 int evdns_resolve_ipv6(const char *name, int flags,
2897 evdns_callback_type callback, void *ptr) {
2898 return evdns_base_resolve_ipv6(current_base, name, flags, callback, ptr)
2899 ? 0 : -1;
2902 struct evdns_request *
2903 evdns_base_resolve_reverse(struct evdns_base *base, const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) {
2904 char buf[32];
2905 struct evdns_request *handle;
2906 struct request *req;
2907 u32 a;
2908 EVUTIL_ASSERT(in);
2909 a = ntohl(in->s_addr);
2910 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa",
2911 (int)(u8)((a )&0xff),
2912 (int)(u8)((a>>8 )&0xff),
2913 (int)(u8)((a>>16)&0xff),
2914 (int)(u8)((a>>24)&0xff));
2915 handle = mm_calloc(1, sizeof(*handle));
2916 if (handle == NULL)
2917 return NULL;
2918 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf);
2919 EVDNS_LOCK(base);
2920 req = request_new(base, handle, TYPE_PTR, buf, flags, callback, ptr);
2921 if (req)
2922 request_submit(req);
2923 if (handle->current_req == NULL) {
2924 mm_free(handle);
2925 handle = NULL;
2927 EVDNS_UNLOCK(base);
2928 return (handle);
2931 int evdns_resolve_reverse(const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) {
2932 return evdns_base_resolve_reverse(current_base, in, flags, callback, ptr)
2933 ? 0 : -1;
2936 struct evdns_request *
2937 evdns_base_resolve_reverse_ipv6(struct evdns_base *base, const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) {
2938 /* 32 nybbles, 32 periods, "ip6.arpa", NUL. */
2939 char buf[73];
2940 char *cp;
2941 struct evdns_request *handle;
2942 struct request *req;
2943 int i;
2944 EVUTIL_ASSERT(in);
2945 cp = buf;
2946 for (i=15; i >= 0; --i) {
2947 u8 byte = in->s6_addr[i];
2948 *cp++ = "0123456789abcdef"[byte & 0x0f];
2949 *cp++ = '.';
2950 *cp++ = "0123456789abcdef"[byte >> 4];
2951 *cp++ = '.';
2953 EVUTIL_ASSERT(cp + strlen("ip6.arpa") < buf+sizeof(buf));
2954 memcpy(cp, "ip6.arpa", strlen("ip6.arpa")+1);
2955 handle = mm_calloc(1, sizeof(*handle));
2956 if (handle == NULL)
2957 return NULL;
2958 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf);
2959 EVDNS_LOCK(base);
2960 req = request_new(base, handle, TYPE_PTR, buf, flags, callback, ptr);
2961 if (req)
2962 request_submit(req);
2963 if (handle->current_req == NULL) {
2964 mm_free(handle);
2965 handle = NULL;
2967 EVDNS_UNLOCK(base);
2968 return (handle);
2971 int evdns_resolve_reverse_ipv6(const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) {
2972 return evdns_base_resolve_reverse_ipv6(current_base, in, flags, callback, ptr)
2973 ? 0 : -1;
2976 /* ================================================================= */
2977 /* Search support */
2978 /* */
2979 /* the libc resolver has support for searching a number of domains */
2980 /* to find a name. If nothing else then it takes the single domain */
2981 /* from the gethostname() call. */
2982 /* */
2983 /* It can also be configured via the domain and search options in a */
2984 /* resolv.conf. */
2985 /* */
2986 /* The ndots option controls how many dots it takes for the resolver */
2987 /* to decide that a name is non-local and so try a raw lookup first. */
2989 struct search_domain {
2990 int len;
2991 struct search_domain *next;
2992 /* the text string is appended to this structure */
2995 struct search_state {
2996 int refcount;
2997 int ndots;
2998 int num_domains;
2999 struct search_domain *head;
3002 static void
3003 search_state_decref(struct search_state *const state) {
3004 if (!state) return;
3005 state->refcount--;
3006 if (!state->refcount) {
3007 struct search_domain *next, *dom;
3008 for (dom = state->head; dom; dom = next) {
3009 next = dom->next;
3010 mm_free(dom);
3012 mm_free(state);
3016 static struct search_state *
3017 search_state_new(void) {
3018 struct search_state *state = (struct search_state *) mm_malloc(sizeof(struct search_state));
3019 if (!state) return NULL;
3020 memset(state, 0, sizeof(struct search_state));
3021 state->refcount = 1;
3022 state->ndots = 1;
3024 return state;
3027 static void
3028 search_postfix_clear(struct evdns_base *base) {
3029 search_state_decref(base->global_search_state);
3031 base->global_search_state = search_state_new();
3034 /* exported function */
3035 void
3036 evdns_base_search_clear(struct evdns_base *base)
3038 EVDNS_LOCK(base);
3039 search_postfix_clear(base);
3040 EVDNS_UNLOCK(base);
3043 void
3044 evdns_search_clear(void) {
3045 evdns_base_search_clear(current_base);
3048 static void
3049 search_postfix_add(struct evdns_base *base, const char *domain) {
3050 size_t domain_len;
3051 struct search_domain *sdomain;
3052 while (domain[0] == '.') domain++;
3053 domain_len = strlen(domain);
3055 ASSERT_LOCKED(base);
3056 if (!base->global_search_state) base->global_search_state = search_state_new();
3057 if (!base->global_search_state) return;
3058 base->global_search_state->num_domains++;
3060 sdomain = (struct search_domain *) mm_malloc(sizeof(struct search_domain) + domain_len);
3061 if (!sdomain) return;
3062 memcpy( ((u8 *) sdomain) + sizeof(struct search_domain), domain, domain_len);
3063 sdomain->next = base->global_search_state->head;
3064 sdomain->len = (int) domain_len;
3066 base->global_search_state->head = sdomain;
3069 /* reverse the order of members in the postfix list. This is needed because, */
3070 /* when parsing resolv.conf we push elements in the wrong order */
3071 static void
3072 search_reverse(struct evdns_base *base) {
3073 struct search_domain *cur, *prev = NULL, *next;
3074 ASSERT_LOCKED(base);
3075 cur = base->global_search_state->head;
3076 while (cur) {
3077 next = cur->next;
3078 cur->next = prev;
3079 prev = cur;
3080 cur = next;
3083 base->global_search_state->head = prev;
3086 /* exported function */
3087 void
3088 evdns_base_search_add(struct evdns_base *base, const char *domain) {
3089 EVDNS_LOCK(base);
3090 search_postfix_add(base, domain);
3091 EVDNS_UNLOCK(base);
3093 void
3094 evdns_search_add(const char *domain) {
3095 evdns_base_search_add(current_base, domain);
3098 /* exported function */
3099 void
3100 evdns_base_search_ndots_set(struct evdns_base *base, const int ndots) {
3101 EVDNS_LOCK(base);
3102 if (!base->global_search_state) base->global_search_state = search_state_new();
3103 if (base->global_search_state)
3104 base->global_search_state->ndots = ndots;
3105 EVDNS_UNLOCK(base);
3107 void
3108 evdns_search_ndots_set(const int ndots) {
3109 evdns_base_search_ndots_set(current_base, ndots);
3112 static void
3113 search_set_from_hostname(struct evdns_base *base) {
3114 char hostname[HOST_NAME_MAX + 1], *domainname;
3116 ASSERT_LOCKED(base);
3117 search_postfix_clear(base);
3118 if (gethostname(hostname, sizeof(hostname))) return;
3119 domainname = strchr(hostname, '.');
3120 if (!domainname) return;
3121 search_postfix_add(base, domainname);
3124 /* warning: returns malloced string */
3125 static char *
3126 search_make_new(const struct search_state *const state, int n, const char *const base_name) {
3127 const size_t base_len = strlen(base_name);
3128 const char need_to_append_dot = base_name[base_len - 1] == '.' ? 0 : 1;
3129 struct search_domain *dom;
3131 for (dom = state->head; dom; dom = dom->next) {
3132 if (!n--) {
3133 /* this is the postfix we want */
3134 /* the actual postfix string is kept at the end of the structure */
3135 const u8 *const postfix = ((u8 *) dom) + sizeof(struct search_domain);
3136 const int postfix_len = dom->len;
3137 char *const newname = (char *) mm_malloc(base_len + need_to_append_dot + postfix_len + 1);
3138 if (!newname) return NULL;
3139 memcpy(newname, base_name, base_len);
3140 if (need_to_append_dot) newname[base_len] = '.';
3141 memcpy(newname + base_len + need_to_append_dot, postfix, postfix_len);
3142 newname[base_len + need_to_append_dot + postfix_len] = 0;
3143 return newname;
3147 /* we ran off the end of the list and still didn't find the requested string */
3148 EVUTIL_ASSERT(0);
3149 return NULL; /* unreachable; stops warnings in some compilers. */
3152 static struct request *
3153 search_request_new(struct evdns_base *base, struct evdns_request *handle,
3154 int type, const char *const name, int flags,
3155 evdns_callback_type user_callback, void *user_arg) {
3156 ASSERT_LOCKED(base);
3157 EVUTIL_ASSERT(type == TYPE_A || type == TYPE_AAAA);
3158 EVUTIL_ASSERT(handle->current_req == NULL);
3159 if ( ((flags & DNS_QUERY_NO_SEARCH) == 0) &&
3160 base->global_search_state &&
3161 base->global_search_state->num_domains) {
3162 /* we have some domains to search */
3163 struct request *req;
3164 if (string_num_dots(name) >= base->global_search_state->ndots) {
3165 req = request_new(base, handle, type, name, flags, user_callback, user_arg);
3166 if (!req) return NULL;
3167 handle->search_index = -1;
3168 } else {
3169 char *const new_name = search_make_new(base->global_search_state, 0, name);
3170 if (!new_name) return NULL;
3171 req = request_new(base, handle, type, new_name, flags, user_callback, user_arg);
3172 mm_free(new_name);
3173 if (!req) return NULL;
3174 handle->search_index = 0;
3176 EVUTIL_ASSERT(handle->search_origname == NULL);
3177 handle->search_origname = mm_strdup(name);
3178 if (handle->search_origname == NULL) {
3179 /* XXX Should we dealloc req? If yes, how? */
3180 if (req)
3181 mm_free(req);
3182 return NULL;
3184 handle->search_state = base->global_search_state;
3185 handle->search_flags = flags;
3186 base->global_search_state->refcount++;
3187 request_submit(req);
3188 return req;
3189 } else {
3190 struct request *const req = request_new(base, handle, type, name, flags, user_callback, user_arg);
3191 if (!req) return NULL;
3192 request_submit(req);
3193 return req;
3197 /* this is called when a request has failed to find a name. We need to check */
3198 /* if it is part of a search and, if so, try the next name in the list */
3199 /* returns: */
3200 /* 0 another request has been submitted */
3201 /* 1 no more requests needed */
3202 static int
3203 search_try_next(struct evdns_request *const handle) {
3204 struct request *req = handle->current_req;
3205 struct evdns_base *base = req->base;
3206 struct request *newreq;
3207 ASSERT_LOCKED(base);
3208 if (handle->search_state) {
3209 /* it is part of a search */
3210 char *new_name;
3211 handle->search_index++;
3212 if (handle->search_index >= handle->search_state->num_domains) {
3213 /* no more postfixes to try, however we may need to try */
3214 /* this name without a postfix */
3215 if (string_num_dots(handle->search_origname) < handle->search_state->ndots) {
3216 /* yep, we need to try it raw */
3217 newreq = request_new(base, NULL, req->request_type, handle->search_origname, handle->search_flags, req->user_callback, req->user_pointer);
3218 log(EVDNS_LOG_DEBUG, "Search: trying raw query %s", handle->search_origname);
3219 if (newreq) {
3220 search_request_finished(handle);
3221 goto submit_next;
3224 return 1;
3227 new_name = search_make_new(handle->search_state, handle->search_index, handle->search_origname);
3228 if (!new_name) return 1;
3229 log(EVDNS_LOG_DEBUG, "Search: now trying %s (%d)", new_name, handle->search_index);
3230 newreq = request_new(base, NULL, req->request_type, new_name, handle->search_flags, req->user_callback, req->user_pointer);
3231 mm_free(new_name);
3232 if (!newreq) return 1;
3233 goto submit_next;
3235 return 1;
3237 submit_next:
3238 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 0);
3239 handle->current_req = newreq;
3240 newreq->handle = handle;
3241 request_submit(newreq);
3242 return 0;
3245 static void
3246 search_request_finished(struct evdns_request *const handle) {
3247 ASSERT_LOCKED(handle->current_req->base);
3248 if (handle->search_state) {
3249 search_state_decref(handle->search_state);
3250 handle->search_state = NULL;
3252 if (handle->search_origname) {
3253 mm_free(handle->search_origname);
3254 handle->search_origname = NULL;
3258 /* ================================================================= */
3259 /* Parsing resolv.conf files */
3261 static void
3262 evdns_resolv_set_defaults(struct evdns_base *base, int flags) {
3263 /* if the file isn't found then we assume a local resolver */
3264 ASSERT_LOCKED(base);
3265 if (flags & DNS_OPTION_SEARCH) search_set_from_hostname(base);
3266 if (flags & DNS_OPTION_NAMESERVERS) evdns_base_nameserver_ip_add(base,"127.0.0.1");
3269 #ifndef _EVENT_HAVE_STRTOK_R
3270 static char *
3271 strtok_r(char *s, const char *delim, char **state) {
3272 char *cp, *start;
3273 start = cp = s ? s : *state;
3274 if (!cp)
3275 return NULL;
3276 while (*cp && !strchr(delim, *cp))
3277 ++cp;
3278 if (!*cp) {
3279 if (cp == start)
3280 return NULL;
3281 *state = NULL;
3282 return start;
3283 } else {
3284 *cp++ = '\0';
3285 *state = cp;
3286 return start;
3289 #endif
3291 /* helper version of atoi which returns -1 on error */
3292 static int
3293 strtoint(const char *const str)
3295 char *endptr;
3296 const int r = strtol(str, &endptr, 10);
3297 if (*endptr) return -1;
3298 return r;
3301 /* Parse a number of seconds into a timeval; return -1 on error. */
3302 static int
3303 strtotimeval(const char *const str, struct timeval *out)
3305 double d;
3306 char *endptr;
3307 d = strtod(str, &endptr);
3308 if (*endptr) return -1;
3309 if (d < 0) return -1;
3310 out->tv_sec = (int) d;
3311 out->tv_usec = (int) ((d - (int) d)*1000000);
3312 if (out->tv_sec == 0 && out->tv_usec < 1000) /* less than 1 msec */
3313 return -1;
3314 return 0;
3317 /* helper version of atoi that returns -1 on error and clips to bounds. */
3318 static int
3319 strtoint_clipped(const char *const str, int min, int max)
3321 int r = strtoint(str);
3322 if (r == -1)
3323 return r;
3324 else if (r<min)
3325 return min;
3326 else if (r>max)
3327 return max;
3328 else
3329 return r;
3332 static int
3333 evdns_base_set_max_requests_inflight(struct evdns_base *base, int maxinflight)
3335 int old_n_heads = base->n_req_heads, n_heads;
3336 struct request **old_heads = base->req_heads, **new_heads, *req;
3337 int i;
3339 ASSERT_LOCKED(base);
3340 if (maxinflight < 1)
3341 maxinflight = 1;
3342 n_heads = (maxinflight+4) / 5;
3343 EVUTIL_ASSERT(n_heads > 0);
3344 new_heads = mm_calloc(n_heads, sizeof(struct request*));
3345 if (!new_heads)
3346 return (-1);
3347 if (old_heads) {
3348 for (i = 0; i < old_n_heads; ++i) {
3349 while (old_heads[i]) {
3350 req = old_heads[i];
3351 evdns_request_remove(req, &old_heads[i]);
3352 evdns_request_insert(req, &new_heads[req->trans_id % n_heads]);
3355 mm_free(old_heads);
3357 base->req_heads = new_heads;
3358 base->n_req_heads = n_heads;
3359 base->global_max_requests_inflight = maxinflight;
3360 return (0);
3363 /* exported function */
3365 evdns_base_set_option(struct evdns_base *base,
3366 const char *option, const char *val)
3368 int res;
3369 EVDNS_LOCK(base);
3370 res = evdns_base_set_option_impl(base, option, val, DNS_OPTIONS_ALL);
3371 EVDNS_UNLOCK(base);
3372 return res;
3375 static inline int
3376 str_matches_option(const char *s1, const char *optionname)
3378 /* Option names are given as "option:" We accept either 'option' in
3379 * s1, or 'option:randomjunk'. The latter form is to implement the
3380 * resolv.conf parser. */
3381 size_t optlen = strlen(optionname);
3382 size_t slen = strlen(s1);
3383 if (slen == optlen || slen == optlen - 1)
3384 return !strncmp(s1, optionname, slen);
3385 else if (slen > optlen)
3386 return !strncmp(s1, optionname, optlen);
3387 else
3388 return 0;
3391 static int
3392 evdns_base_set_option_impl(struct evdns_base *base,
3393 const char *option, const char *val, int flags)
3395 ASSERT_LOCKED(base);
3396 if (str_matches_option(option, "ndots:")) {
3397 const int ndots = strtoint(val);
3398 if (ndots == -1) return -1;
3399 if (!(flags & DNS_OPTION_SEARCH)) return 0;
3400 log(EVDNS_LOG_DEBUG, "Setting ndots to %d", ndots);
3401 if (!base->global_search_state) base->global_search_state = search_state_new();
3402 if (!base->global_search_state) return -1;
3403 base->global_search_state->ndots = ndots;
3404 } else if (str_matches_option(option, "timeout:")) {
3405 struct timeval tv;
3406 if (strtotimeval(val, &tv) == -1) return -1;
3407 if (!(flags & DNS_OPTION_MISC)) return 0;
3408 log(EVDNS_LOG_DEBUG, "Setting timeout to %s", val);
3409 memcpy(&base->global_timeout, &tv, sizeof(struct timeval));
3410 } else if (str_matches_option(option, "getaddrinfo-allow-skew:")) {
3411 struct timeval tv;
3412 if (strtotimeval(val, &tv) == -1) return -1;
3413 if (!(flags & DNS_OPTION_MISC)) return 0;
3414 log(EVDNS_LOG_DEBUG, "Setting getaddrinfo-allow-skew to %s",
3415 val);
3416 memcpy(&base->global_getaddrinfo_allow_skew, &tv,
3417 sizeof(struct timeval));
3418 } else if (str_matches_option(option, "max-timeouts:")) {
3419 const int maxtimeout = strtoint_clipped(val, 1, 255);
3420 if (maxtimeout == -1) return -1;
3421 if (!(flags & DNS_OPTION_MISC)) return 0;
3422 log(EVDNS_LOG_DEBUG, "Setting maximum allowed timeouts to %d",
3423 maxtimeout);
3424 base->global_max_nameserver_timeout = maxtimeout;
3425 } else if (str_matches_option(option, "max-inflight:")) {
3426 const int maxinflight = strtoint_clipped(val, 1, 65000);
3427 if (maxinflight == -1) return -1;
3428 if (!(flags & DNS_OPTION_MISC)) return 0;
3429 log(EVDNS_LOG_DEBUG, "Setting maximum inflight requests to %d",
3430 maxinflight);
3431 evdns_base_set_max_requests_inflight(base, maxinflight);
3432 } else if (str_matches_option(option, "attempts:")) {
3433 int retries = strtoint(val);
3434 if (retries == -1) return -1;
3435 if (retries > 255) retries = 255;
3436 if (!(flags & DNS_OPTION_MISC)) return 0;
3437 log(EVDNS_LOG_DEBUG, "Setting retries to %d", retries);
3438 base->global_max_retransmits = retries;
3439 } else if (str_matches_option(option, "randomize-case:")) {
3440 int randcase = strtoint(val);
3441 if (!(flags & DNS_OPTION_MISC)) return 0;
3442 base->global_randomize_case = randcase;
3443 } else if (str_matches_option(option, "bind-to:")) {
3444 /* XXX This only applies to successive nameservers, not
3445 * to already-configured ones. We might want to fix that. */
3446 int len = sizeof(base->global_outgoing_address);
3447 if (!(flags & DNS_OPTION_NAMESERVERS)) return 0;
3448 if (evutil_parse_sockaddr_port(val,
3449 (struct sockaddr*)&base->global_outgoing_address, &len))
3450 return -1;
3451 base->global_outgoing_addrlen = len;
3452 } else if (str_matches_option(option, "initial-probe-timeout:")) {
3453 struct timeval tv;
3454 if (strtotimeval(val, &tv) == -1) return -1;
3455 if (tv.tv_sec > 3600)
3456 tv.tv_sec = 3600;
3457 if (!(flags & DNS_OPTION_MISC)) return 0;
3458 log(EVDNS_LOG_DEBUG, "Setting initial probe timeout to %s",
3459 val);
3460 memcpy(&base->global_nameserver_probe_initial_timeout, &tv,
3461 sizeof(tv));
3463 return 0;
3467 evdns_set_option(const char *option, const char *val, int flags)
3469 if (!current_base)
3470 current_base = evdns_base_new(NULL, 0);
3471 return evdns_base_set_option(current_base, option, val);
3474 static void
3475 resolv_conf_parse_line(struct evdns_base *base, char *const start, int flags) {
3476 char *strtok_state;
3477 static const char *const delims = " \t";
3478 #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state)
3481 char *const first_token = strtok_r(start, delims, &strtok_state);
3482 ASSERT_LOCKED(base);
3483 if (!first_token) return;
3485 if (!strcmp(first_token, "nameserver") && (flags & DNS_OPTION_NAMESERVERS)) {
3486 const char *const nameserver = NEXT_TOKEN;
3488 if (nameserver)
3489 evdns_base_nameserver_ip_add(base, nameserver);
3490 } else if (!strcmp(first_token, "domain") && (flags & DNS_OPTION_SEARCH)) {
3491 const char *const domain = NEXT_TOKEN;
3492 if (domain) {
3493 search_postfix_clear(base);
3494 search_postfix_add(base, domain);
3496 } else if (!strcmp(first_token, "search") && (flags & DNS_OPTION_SEARCH)) {
3497 const char *domain;
3498 search_postfix_clear(base);
3500 while ((domain = NEXT_TOKEN)) {
3501 search_postfix_add(base, domain);
3503 search_reverse(base);
3504 } else if (!strcmp(first_token, "options")) {
3505 const char *option;
3506 while ((option = NEXT_TOKEN)) {
3507 const char *val = strchr(option, ':');
3508 evdns_base_set_option_impl(base, option, val ? val+1 : "", flags);
3511 #undef NEXT_TOKEN
3514 /* exported function */
3515 /* returns: */
3516 /* 0 no errors */
3517 /* 1 failed to open file */
3518 /* 2 failed to stat file */
3519 /* 3 file too large */
3520 /* 4 out of memory */
3521 /* 5 short read from file */
3523 evdns_base_resolv_conf_parse(struct evdns_base *base, int flags, const char *const filename) {
3524 int res;
3525 EVDNS_LOCK(base);
3526 res = evdns_base_resolv_conf_parse_impl(base, flags, filename);
3527 EVDNS_UNLOCK(base);
3528 return res;
3531 static char *
3532 evdns_get_default_hosts_filename(void)
3534 #ifdef WIN32
3535 /* Windows is a little coy about where it puts its configuration
3536 * files. Sure, they're _usually_ in C:\windows\system32, but
3537 * there's no reason in principle they couldn't be in
3538 * W:\hoboken chicken emergency\
3540 char path[MAX_PATH+1];
3541 static const char hostfile[] = "\\drivers\\etc\\hosts";
3542 char *path_out;
3543 size_t len_out;
3545 if (! SHGetSpecialFolderPathA(NULL, path, CSIDL_SYSTEM, 0))
3546 return NULL;
3547 len_out = strlen(path)+strlen(hostfile);
3548 path_out = mm_malloc(len_out+1);
3549 evutil_snprintf(path_out, len_out, "%s%s", path, hostfile);
3550 return path_out;
3551 #else
3552 return mm_strdup("/etc/hosts");
3553 #endif
3556 static int
3557 evdns_base_resolv_conf_parse_impl(struct evdns_base *base, int flags, const char *const filename) {
3558 size_t n;
3559 char *resolv;
3560 char *start;
3561 int err = 0;
3563 log(EVDNS_LOG_DEBUG, "Parsing resolv.conf file %s", filename);
3565 if (flags & DNS_OPTION_HOSTSFILE) {
3566 char *fname = evdns_get_default_hosts_filename();
3567 evdns_base_load_hosts(base, fname);
3568 if (fname)
3569 mm_free(fname);
3572 if ((err = evutil_read_file(filename, &resolv, &n, 0)) < 0) {
3573 if (err == -1) {
3574 /* No file. */
3575 evdns_resolv_set_defaults(base, flags);
3576 return 1;
3577 } else {
3578 return 2;
3582 start = resolv;
3583 for (;;) {
3584 char *const newline = strchr(start, '\n');
3585 if (!newline) {
3586 resolv_conf_parse_line(base, start, flags);
3587 break;
3588 } else {
3589 *newline = 0;
3590 resolv_conf_parse_line(base, start, flags);
3591 start = newline + 1;
3595 if (!base->server_head && (flags & DNS_OPTION_NAMESERVERS)) {
3596 /* no nameservers were configured. */
3597 evdns_base_nameserver_ip_add(base, "127.0.0.1");
3598 err = 6;
3600 if (flags & DNS_OPTION_SEARCH && (!base->global_search_state || base->global_search_state->num_domains == 0)) {
3601 search_set_from_hostname(base);
3604 mm_free(resolv);
3605 return err;
3609 evdns_resolv_conf_parse(int flags, const char *const filename) {
3610 if (!current_base)
3611 current_base = evdns_base_new(NULL, 0);
3612 return evdns_base_resolv_conf_parse(current_base, flags, filename);
3616 #ifdef WIN32
3617 /* Add multiple nameservers from a space-or-comma-separated list. */
3618 static int
3619 evdns_nameserver_ip_add_line(struct evdns_base *base, const char *ips) {
3620 const char *addr;
3621 char *buf;
3622 int r;
3623 ASSERT_LOCKED(base);
3624 while (*ips) {
3625 while (isspace(*ips) || *ips == ',' || *ips == '\t')
3626 ++ips;
3627 addr = ips;
3628 while (isdigit(*ips) || *ips == '.' || *ips == ':' ||
3629 *ips=='[' || *ips==']')
3630 ++ips;
3631 buf = mm_malloc(ips-addr+1);
3632 if (!buf) return 4;
3633 memcpy(buf, addr, ips-addr);
3634 buf[ips-addr] = '\0';
3635 r = evdns_base_nameserver_ip_add(base, buf);
3636 mm_free(buf);
3637 if (r) return r;
3639 return 0;
3642 typedef DWORD(WINAPI *GetNetworkParams_fn_t)(FIXED_INFO *, DWORD*);
3644 /* Use the windows GetNetworkParams interface in iphlpapi.dll to */
3645 /* figure out what our nameservers are. */
3646 static int
3647 load_nameservers_with_getnetworkparams(struct evdns_base *base)
3649 /* Based on MSDN examples and inspection of c-ares code. */
3650 FIXED_INFO *fixed;
3651 HMODULE handle = 0;
3652 ULONG size = sizeof(FIXED_INFO);
3653 void *buf = NULL;
3654 int status = 0, r, added_any;
3655 IP_ADDR_STRING *ns;
3656 GetNetworkParams_fn_t fn;
3658 ASSERT_LOCKED(base);
3659 if (!(handle = evutil_load_windows_system_library(
3660 TEXT("iphlpapi.dll")))) {
3661 log(EVDNS_LOG_WARN, "Could not open iphlpapi.dll");
3662 status = -1;
3663 goto done;
3665 if (!(fn = (GetNetworkParams_fn_t) GetProcAddress(handle, "GetNetworkParams"))) {
3666 log(EVDNS_LOG_WARN, "Could not get address of function.");
3667 status = -1;
3668 goto done;
3671 buf = mm_malloc(size);
3672 if (!buf) { status = 4; goto done; }
3673 fixed = buf;
3674 r = fn(fixed, &size);
3675 if (r != ERROR_SUCCESS && r != ERROR_BUFFER_OVERFLOW) {
3676 status = -1;
3677 goto done;
3679 if (r != ERROR_SUCCESS) {
3680 mm_free(buf);
3681 buf = mm_malloc(size);
3682 if (!buf) { status = 4; goto done; }
3683 fixed = buf;
3684 r = fn(fixed, &size);
3685 if (r != ERROR_SUCCESS) {
3686 log(EVDNS_LOG_DEBUG, "fn() failed.");
3687 status = -1;
3688 goto done;
3692 EVUTIL_ASSERT(fixed);
3693 added_any = 0;
3694 ns = &(fixed->DnsServerList);
3695 while (ns) {
3696 r = evdns_nameserver_ip_add_line(base, ns->IpAddress.String);
3697 if (r) {
3698 log(EVDNS_LOG_DEBUG,"Could not add nameserver %s to list,error: %d",
3699 (ns->IpAddress.String),(int)GetLastError());
3700 status = r;
3701 } else {
3702 ++added_any;
3703 log(EVDNS_LOG_DEBUG,"Successfully added %s as nameserver",ns->IpAddress.String);
3706 ns = ns->Next;
3709 if (!added_any) {
3710 log(EVDNS_LOG_DEBUG, "No nameservers added.");
3711 if (status == 0)
3712 status = -1;
3713 } else {
3714 status = 0;
3717 done:
3718 if (buf)
3719 mm_free(buf);
3720 if (handle)
3721 FreeLibrary(handle);
3722 return status;
3725 static int
3726 config_nameserver_from_reg_key(struct evdns_base *base, HKEY key, const TCHAR *subkey)
3728 char *buf;
3729 DWORD bufsz = 0, type = 0;
3730 int status = 0;
3732 ASSERT_LOCKED(base);
3733 if (RegQueryValueEx(key, subkey, 0, &type, NULL, &bufsz)
3734 != ERROR_MORE_DATA)
3735 return -1;
3736 if (!(buf = mm_malloc(bufsz)))
3737 return -1;
3739 if (RegQueryValueEx(key, subkey, 0, &type, (LPBYTE)buf, &bufsz)
3740 == ERROR_SUCCESS && bufsz > 1) {
3741 status = evdns_nameserver_ip_add_line(base,buf);
3744 mm_free(buf);
3745 return status;
3748 #define SERVICES_KEY TEXT("System\\CurrentControlSet\\Services\\")
3749 #define WIN_NS_9X_KEY SERVICES_KEY TEXT("VxD\\MSTCP")
3750 #define WIN_NS_NT_KEY SERVICES_KEY TEXT("Tcpip\\Parameters")
3752 static int
3753 load_nameservers_from_registry(struct evdns_base *base)
3755 int found = 0;
3756 int r;
3757 #define TRY(k, name) \
3758 if (!found && config_nameserver_from_reg_key(base,k,TEXT(name)) == 0) { \
3759 log(EVDNS_LOG_DEBUG,"Found nameservers in %s/%s",#k,name); \
3760 found = 1; \
3761 } else if (!found) { \
3762 log(EVDNS_LOG_DEBUG,"Didn't find nameservers in %s/%s", \
3763 #k,#name); \
3766 ASSERT_LOCKED(base);
3768 if (((int)GetVersion()) > 0) { /* NT */
3769 HKEY nt_key = 0, interfaces_key = 0;
3771 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0,
3772 KEY_READ, &nt_key) != ERROR_SUCCESS) {
3773 log(EVDNS_LOG_DEBUG,"Couldn't open nt key, %d",(int)GetLastError());
3774 return -1;
3776 r = RegOpenKeyEx(nt_key, TEXT("Interfaces"), 0,
3777 KEY_QUERY_VALUE|KEY_ENUMERATE_SUB_KEYS,
3778 &interfaces_key);
3779 if (r != ERROR_SUCCESS) {
3780 log(EVDNS_LOG_DEBUG,"Couldn't open interfaces key, %d",(int)GetLastError());
3781 return -1;
3783 TRY(nt_key, "NameServer");
3784 TRY(nt_key, "DhcpNameServer");
3785 TRY(interfaces_key, "NameServer");
3786 TRY(interfaces_key, "DhcpNameServer");
3787 RegCloseKey(interfaces_key);
3788 RegCloseKey(nt_key);
3789 } else {
3790 HKEY win_key = 0;
3791 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_9X_KEY, 0,
3792 KEY_READ, &win_key) != ERROR_SUCCESS) {
3793 log(EVDNS_LOG_DEBUG, "Couldn't open registry key, %d", (int)GetLastError());
3794 return -1;
3796 TRY(win_key, "NameServer");
3797 RegCloseKey(win_key);
3800 if (found == 0) {
3801 log(EVDNS_LOG_WARN,"Didn't find any nameservers.");
3804 return found ? 0 : -1;
3805 #undef TRY
3809 evdns_base_config_windows_nameservers(struct evdns_base *base)
3811 int r;
3812 char *fname;
3813 if (base == NULL)
3814 base = current_base;
3815 if (base == NULL)
3816 return -1;
3817 EVDNS_LOCK(base);
3818 if (load_nameservers_with_getnetworkparams(base) == 0) {
3819 EVDNS_UNLOCK(base);
3820 return 0;
3822 r = load_nameservers_from_registry(base);
3824 fname = evdns_get_default_hosts_filename();
3825 evdns_base_load_hosts(base, fname);
3826 if (fname)
3827 mm_free(fname);
3829 EVDNS_UNLOCK(base);
3830 return r;
3834 evdns_config_windows_nameservers(void)
3836 if (!current_base) {
3837 current_base = evdns_base_new(NULL, 1);
3838 return current_base == NULL ? -1 : 0;
3839 } else {
3840 return evdns_base_config_windows_nameservers(current_base);
3843 #endif
3845 struct evdns_base *
3846 evdns_base_new(struct event_base *event_base, int initialize_nameservers)
3848 struct evdns_base *base;
3850 if (evutil_secure_rng_init() < 0) {
3851 log(EVDNS_LOG_WARN, "Unable to seed random number generator; "
3852 "DNS can't run.");
3853 return NULL;
3856 /* Give the evutil library a hook into its evdns-enabled
3857 * functionality. We can't just call evdns_getaddrinfo directly or
3858 * else libevent-core will depend on libevent-extras. */
3859 evutil_set_evdns_getaddrinfo_fn(evdns_getaddrinfo);
3861 base = mm_malloc(sizeof(struct evdns_base));
3862 if (base == NULL)
3863 return (NULL);
3864 memset(base, 0, sizeof(struct evdns_base));
3865 base->req_waiting_head = NULL;
3867 EVTHREAD_ALLOC_LOCK(base->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
3868 EVDNS_LOCK(base);
3870 /* Set max requests inflight and allocate req_heads. */
3871 base->req_heads = NULL;
3873 evdns_base_set_max_requests_inflight(base, 64);
3875 base->server_head = NULL;
3876 base->event_base = event_base;
3877 base->global_good_nameservers = base->global_requests_inflight =
3878 base->global_requests_waiting = 0;
3880 base->global_timeout.tv_sec = 5;
3881 base->global_timeout.tv_usec = 0;
3882 base->global_max_reissues = 1;
3883 base->global_max_retransmits = 3;
3884 base->global_max_nameserver_timeout = 3;
3885 base->global_search_state = NULL;
3886 base->global_randomize_case = 1;
3887 base->global_getaddrinfo_allow_skew.tv_sec = 3;
3888 base->global_getaddrinfo_allow_skew.tv_usec = 0;
3889 base->global_nameserver_probe_initial_timeout.tv_sec = 10;
3890 base->global_nameserver_probe_initial_timeout.tv_usec = 0;
3892 TAILQ_INIT(&base->hostsdb);
3894 if (initialize_nameservers) {
3895 int r;
3896 #ifdef WIN32
3897 r = evdns_base_config_windows_nameservers(base);
3898 #else
3899 r = evdns_base_resolv_conf_parse(base, DNS_OPTIONS_ALL, "/etc/resolv.conf");
3900 #endif
3901 if (r == -1) {
3902 evdns_base_free_and_unlock(base, 0);
3903 return NULL;
3906 EVDNS_UNLOCK(base);
3907 return base;
3911 evdns_init(void)
3913 struct evdns_base *base = evdns_base_new(NULL, 1);
3914 if (base) {
3915 current_base = base;
3916 return 0;
3917 } else {
3918 return -1;
3922 const char *
3923 evdns_err_to_string(int err)
3925 switch (err) {
3926 case DNS_ERR_NONE: return "no error";
3927 case DNS_ERR_FORMAT: return "misformatted query";
3928 case DNS_ERR_SERVERFAILED: return "server failed";
3929 case DNS_ERR_NOTEXIST: return "name does not exist";
3930 case DNS_ERR_NOTIMPL: return "query not implemented";
3931 case DNS_ERR_REFUSED: return "refused";
3933 case DNS_ERR_TRUNCATED: return "reply truncated or ill-formed";
3934 case DNS_ERR_UNKNOWN: return "unknown";
3935 case DNS_ERR_TIMEOUT: return "request timed out";
3936 case DNS_ERR_SHUTDOWN: return "dns subsystem shut down";
3937 case DNS_ERR_CANCEL: return "dns request canceled";
3938 case DNS_ERR_NODATA: return "no records in the reply";
3939 default: return "[Unknown error code]";
3943 static void
3944 evdns_nameserver_free(struct nameserver *server)
3946 if (server->socket >= 0)
3947 evutil_closesocket(server->socket);
3948 (void) event_del(&server->event);
3949 event_debug_unassign(&server->event);
3950 if (server->state == 0)
3951 (void) event_del(&server->timeout_event);
3952 if (server->probe_request) {
3953 evdns_cancel_request(server->base, server->probe_request);
3954 server->probe_request = NULL;
3956 event_debug_unassign(&server->timeout_event);
3957 mm_free(server);
3960 static void
3961 evdns_base_free_and_unlock(struct evdns_base *base, int fail_requests)
3963 struct nameserver *server, *server_next;
3964 struct search_domain *dom, *dom_next;
3965 int i;
3967 /* Requires that we hold the lock. */
3969 /* TODO(nickm) we might need to refcount here. */
3971 for (server = base->server_head; server; server = server_next) {
3972 server_next = server->next;
3973 evdns_nameserver_free(server);
3974 if (server_next == base->server_head)
3975 break;
3977 base->server_head = NULL;
3978 base->global_good_nameservers = 0;
3980 for (i = 0; i < base->n_req_heads; ++i) {
3981 while (base->req_heads[i]) {
3982 if (fail_requests)
3983 reply_schedule_callback(base->req_heads[i], 0, DNS_ERR_SHUTDOWN, NULL);
3984 request_finished(base->req_heads[i], &REQ_HEAD(base, base->req_heads[i]->trans_id), 1);
3987 while (base->req_waiting_head) {
3988 if (fail_requests)
3989 reply_schedule_callback(base->req_waiting_head, 0, DNS_ERR_SHUTDOWN, NULL);
3990 request_finished(base->req_waiting_head, &base->req_waiting_head, 1);
3992 base->global_requests_inflight = base->global_requests_waiting = 0;
3995 if (base->global_search_state) {
3996 for (dom = base->global_search_state->head; dom; dom = dom_next) {
3997 dom_next = dom->next;
3998 mm_free(dom);
4000 mm_free(base->global_search_state);
4001 base->global_search_state = NULL;
4005 struct hosts_entry *victim;
4006 while ((victim = TAILQ_FIRST(&base->hostsdb))) {
4007 TAILQ_REMOVE(&base->hostsdb, victim, next);
4008 mm_free(victim);
4012 mm_free(base->req_heads);
4014 EVDNS_UNLOCK(base);
4015 EVTHREAD_FREE_LOCK(base->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
4017 mm_free(base);
4020 void
4021 evdns_base_free(struct evdns_base *base, int fail_requests)
4023 EVDNS_LOCK(base);
4024 evdns_base_free_and_unlock(base, fail_requests);
4027 void
4028 evdns_shutdown(int fail_requests)
4030 if (current_base) {
4031 struct evdns_base *b = current_base;
4032 current_base = NULL;
4033 evdns_base_free(b, fail_requests);
4035 evdns_log_fn = NULL;
4038 static int
4039 evdns_base_parse_hosts_line(struct evdns_base *base, char *line)
4041 char *strtok_state;
4042 static const char *const delims = " \t";
4043 char *const addr = strtok_r(line, delims, &strtok_state);
4044 char *hostname, *hash;
4045 struct sockaddr_storage ss;
4046 int socklen = sizeof(ss);
4047 ASSERT_LOCKED(base);
4049 #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state)
4051 if (!addr || *addr == '#')
4052 return 0;
4054 memset(&ss, 0, sizeof(ss));
4055 if (evutil_parse_sockaddr_port(addr, (struct sockaddr*)&ss, &socklen)<0)
4056 return -1;
4057 if (socklen > (int)sizeof(struct sockaddr_in6))
4058 return -1;
4060 if (sockaddr_getport((struct sockaddr*)&ss))
4061 return -1;
4063 while ((hostname = NEXT_TOKEN)) {
4064 struct hosts_entry *he;
4065 size_t namelen;
4066 if ((hash = strchr(hostname, '#'))) {
4067 if (hash == hostname)
4068 return 0;
4069 *hash = '\0';
4072 namelen = strlen(hostname);
4074 he = mm_calloc(1, sizeof(struct hosts_entry)+namelen);
4075 if (!he)
4076 return -1;
4077 EVUTIL_ASSERT(socklen <= (int)sizeof(he->addr));
4078 memcpy(&he->addr, &ss, socklen);
4079 memcpy(he->hostname, hostname, namelen+1);
4080 he->addrlen = socklen;
4082 TAILQ_INSERT_TAIL(&base->hostsdb, he, next);
4084 if (hash)
4085 return 0;
4088 return 0;
4089 #undef NEXT_TOKEN
4092 static int
4093 evdns_base_load_hosts_impl(struct evdns_base *base, const char *hosts_fname)
4095 char *str=NULL, *cp, *eol;
4096 size_t len;
4097 int err=0;
4099 ASSERT_LOCKED(base);
4101 if (hosts_fname == NULL ||
4102 (err = evutil_read_file(hosts_fname, &str, &len, 0)) < 0) {
4103 char tmp[64];
4104 strlcpy(tmp, "127.0.0.1 localhost", sizeof(tmp));
4105 evdns_base_parse_hosts_line(base, tmp);
4106 strlcpy(tmp, "::1 localhost", sizeof(tmp));
4107 evdns_base_parse_hosts_line(base, tmp);
4108 return err ? -1 : 0;
4111 /* This will break early if there is a NUL in the hosts file.
4112 * Probably not a problem.*/
4113 cp = str;
4114 for (;;) {
4115 eol = strchr(cp, '\n');
4117 if (eol) {
4118 *eol = '\0';
4119 evdns_base_parse_hosts_line(base, cp);
4120 cp = eol+1;
4121 } else {
4122 evdns_base_parse_hosts_line(base, cp);
4123 break;
4127 mm_free(str);
4128 return 0;
4132 evdns_base_load_hosts(struct evdns_base *base, const char *hosts_fname)
4134 int res;
4135 if (!base)
4136 base = current_base;
4137 EVDNS_LOCK(base);
4138 res = evdns_base_load_hosts_impl(base, hosts_fname);
4139 EVDNS_UNLOCK(base);
4140 return res;
4143 /* A single request for a getaddrinfo, either v4 or v6. */
4144 struct getaddrinfo_subrequest {
4145 struct evdns_request *r;
4146 ev_uint32_t type;
4149 /* State data used to implement an in-progress getaddrinfo. */
4150 struct evdns_getaddrinfo_request {
4151 struct evdns_base *evdns_base;
4152 /* Copy of the modified 'hints' data that we'll use to build
4153 * answers. */
4154 struct evutil_addrinfo hints;
4155 /* The callback to invoke when we're done */
4156 evdns_getaddrinfo_cb user_cb;
4157 /* User-supplied data to give to the callback. */
4158 void *user_data;
4159 /* The port to use when building sockaddrs. */
4160 ev_uint16_t port;
4161 /* The sub_request for an A record (if any) */
4162 struct getaddrinfo_subrequest ipv4_request;
4163 /* The sub_request for an AAAA record (if any) */
4164 struct getaddrinfo_subrequest ipv6_request;
4166 /* The cname result that we were told (if any) */
4167 char *cname_result;
4169 /* If we have one request answered and one request still inflight,
4170 * then this field holds the answer from the first request... */
4171 struct evutil_addrinfo *pending_result;
4172 /* And this event is a timeout that will tell us to cancel the second
4173 * request if it's taking a long time. */
4174 struct event timeout;
4176 /* And this field holds the error code from the first request... */
4177 int pending_error;
4178 /* If this is set, the user canceled this request. */
4179 unsigned user_canceled : 1;
4180 /* If this is set, the user can no longer cancel this request; we're
4181 * just waiting for the free. */
4182 unsigned request_done : 1;
4185 /* Convert an evdns errors to the equivalent getaddrinfo error. */
4186 static int
4187 evdns_err_to_getaddrinfo_err(int e1)
4189 /* XXX Do this better! */
4190 if (e1 == DNS_ERR_NONE)
4191 return 0;
4192 else if (e1 == DNS_ERR_NOTEXIST)
4193 return EVUTIL_EAI_NONAME;
4194 else
4195 return EVUTIL_EAI_FAIL;
4198 /* Return the more informative of two getaddrinfo errors. */
4199 static int
4200 getaddrinfo_merge_err(int e1, int e2)
4202 /* XXXX be cleverer here. */
4203 if (e1 == 0)
4204 return e2;
4205 else
4206 return e1;
4209 static void
4210 free_getaddrinfo_request(struct evdns_getaddrinfo_request *data)
4212 /* DO NOT CALL this if either of the requests is pending. Only once
4213 * both callbacks have been invoked is it safe to free the request */
4214 if (data->pending_result)
4215 evutil_freeaddrinfo(data->pending_result);
4216 if (data->cname_result)
4217 mm_free(data->cname_result);
4218 event_del(&data->timeout);
4219 mm_free(data);
4220 return;
4223 static void
4224 add_cname_to_reply(struct evdns_getaddrinfo_request *data,
4225 struct evutil_addrinfo *ai)
4227 if (data->cname_result && ai) {
4228 ai->ai_canonname = data->cname_result;
4229 data->cname_result = NULL;
4233 /* Callback: invoked when one request in a mixed-format A/AAAA getaddrinfo
4234 * request has finished, but the other one took too long to answer. Pass
4235 * along the answer we got, and cancel the other request.
4237 static void
4238 evdns_getaddrinfo_timeout_cb(evutil_socket_t fd, short what, void *ptr)
4240 int v4_timedout = 0, v6_timedout = 0;
4241 struct evdns_getaddrinfo_request *data = ptr;
4243 /* Cancel any pending requests, and note which one */
4244 if (data->ipv4_request.r) {
4245 /* XXXX This does nothing if the request's callback is already
4246 * running (pending_cb is set). */
4247 evdns_cancel_request(NULL, data->ipv4_request.r);
4248 v4_timedout = 1;
4249 EVDNS_LOCK(data->evdns_base);
4250 ++data->evdns_base->getaddrinfo_ipv4_timeouts;
4251 EVDNS_UNLOCK(data->evdns_base);
4253 if (data->ipv6_request.r) {
4254 /* XXXX This does nothing if the request's callback is already
4255 * running (pending_cb is set). */
4256 evdns_cancel_request(NULL, data->ipv6_request.r);
4257 v6_timedout = 1;
4258 EVDNS_LOCK(data->evdns_base);
4259 ++data->evdns_base->getaddrinfo_ipv6_timeouts;
4260 EVDNS_UNLOCK(data->evdns_base);
4263 /* We only use this timeout callback when we have an answer for
4264 * one address. */
4265 EVUTIL_ASSERT(!v4_timedout || !v6_timedout);
4267 /* Report the outcome of the other request that didn't time out. */
4268 if (data->pending_result) {
4269 add_cname_to_reply(data, data->pending_result);
4270 data->user_cb(0, data->pending_result, data->user_data);
4271 data->pending_result = NULL;
4272 } else {
4273 int e = data->pending_error;
4274 if (!e)
4275 e = EVUTIL_EAI_AGAIN;
4276 data->user_cb(e, NULL, data->user_data);
4279 data->user_cb = NULL; /* prevent double-call if evdns callbacks are
4280 * in-progress. XXXX It would be better if this
4281 * weren't necessary. */
4283 if (!v4_timedout && !v6_timedout) {
4284 /* should be impossible? XXXX */
4285 free_getaddrinfo_request(data);
4289 static int
4290 evdns_getaddrinfo_set_timeout(struct evdns_base *evdns_base,
4291 struct evdns_getaddrinfo_request *data)
4293 return event_add(&data->timeout, &evdns_base->global_getaddrinfo_allow_skew);
4296 static inline int
4297 evdns_result_is_answer(int result)
4299 return (result != DNS_ERR_NOTIMPL && result != DNS_ERR_REFUSED &&
4300 result != DNS_ERR_SERVERFAILED && result != DNS_ERR_CANCEL);
4303 static void
4304 evdns_getaddrinfo_gotresolve(int result, char type, int count,
4305 int ttl, void *addresses, void *arg)
4307 int i;
4308 struct getaddrinfo_subrequest *req = arg;
4309 struct getaddrinfo_subrequest *other_req;
4310 struct evdns_getaddrinfo_request *data;
4312 struct evutil_addrinfo *res;
4314 struct sockaddr_in sin;
4315 struct sockaddr_in6 sin6;
4316 struct sockaddr *sa;
4317 int socklen, addrlen;
4318 void *addrp;
4319 int err;
4320 int user_canceled;
4322 EVUTIL_ASSERT(req->type == DNS_IPv4_A || req->type == DNS_IPv6_AAAA);
4323 if (req->type == DNS_IPv4_A) {
4324 data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv4_request);
4325 other_req = &data->ipv6_request;
4326 } else {
4327 data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv6_request);
4328 other_req = &data->ipv4_request;
4331 EVDNS_LOCK(data->evdns_base);
4332 if (evdns_result_is_answer(result)) {
4333 if (req->type == DNS_IPv4_A)
4334 ++data->evdns_base->getaddrinfo_ipv4_answered;
4335 else
4336 ++data->evdns_base->getaddrinfo_ipv6_answered;
4338 user_canceled = data->user_canceled;
4339 if (other_req->r == NULL)
4340 data->request_done = 1;
4341 EVDNS_UNLOCK(data->evdns_base);
4343 req->r = NULL;
4345 if (result == DNS_ERR_CANCEL && ! user_canceled) {
4346 /* Internal cancel request from timeout or internal error.
4347 * we already answered the user. */
4348 if (other_req->r == NULL)
4349 free_getaddrinfo_request(data);
4350 return;
4353 if (data->user_cb == NULL) {
4354 /* We already answered. XXXX This shouldn't be needed; see
4355 * comments in evdns_getaddrinfo_timeout_cb */
4356 free_getaddrinfo_request(data);
4357 return;
4360 if (result == DNS_ERR_NONE) {
4361 if (count == 0)
4362 err = EVUTIL_EAI_NODATA;
4363 else
4364 err = 0;
4365 } else {
4366 err = evdns_err_to_getaddrinfo_err(result);
4369 if (err) {
4370 /* Looks like we got an error. */
4371 if (other_req->r) {
4372 /* The other request is still working; maybe it will
4373 * succeed. */
4374 /* XXXX handle failure from set_timeout */
4375 evdns_getaddrinfo_set_timeout(data->evdns_base, data);
4376 data->pending_error = err;
4377 return;
4380 if (user_canceled) {
4381 data->user_cb(EVUTIL_EAI_CANCEL, NULL, data->user_data);
4382 } else if (data->pending_result) {
4383 /* If we have an answer waiting, and we weren't
4384 * canceled, ignore this error. */
4385 add_cname_to_reply(data, data->pending_result);
4386 data->user_cb(0, data->pending_result, data->user_data);
4387 data->pending_result = NULL;
4388 } else {
4389 if (data->pending_error)
4390 err = getaddrinfo_merge_err(err,
4391 data->pending_error);
4392 data->user_cb(err, NULL, data->user_data);
4394 free_getaddrinfo_request(data);
4395 return;
4396 } else if (user_canceled) {
4397 if (other_req->r) {
4398 /* The other request is still working; let it hit this
4399 * callback with EVUTIL_EAI_CANCEL callback and report
4400 * the failure. */
4401 return;
4403 data->user_cb(EVUTIL_EAI_CANCEL, NULL, data->user_data);
4404 free_getaddrinfo_request(data);
4405 return;
4408 /* Looks like we got some answers. We should turn them into addrinfos
4409 * and then either queue those or return them all. */
4410 EVUTIL_ASSERT(type == DNS_IPv4_A || type == DNS_IPv6_AAAA);
4412 if (type == DNS_IPv4_A) {
4413 memset(&sin, 0, sizeof(sin));
4414 sin.sin_family = AF_INET;
4415 sin.sin_port = htons(data->port);
4417 sa = (struct sockaddr *)&sin;
4418 socklen = sizeof(sin);
4419 addrlen = 4;
4420 addrp = &sin.sin_addr.s_addr;
4421 } else {
4422 memset(&sin6, 0, sizeof(sin6));
4423 sin6.sin6_family = AF_INET6;
4424 sin6.sin6_port = htons(data->port);
4426 sa = (struct sockaddr *)&sin6;
4427 socklen = sizeof(sin6);
4428 addrlen = 16;
4429 addrp = &sin6.sin6_addr.s6_addr;
4432 res = NULL;
4433 for (i=0; i < count; ++i) {
4434 struct evutil_addrinfo *ai;
4435 memcpy(addrp, ((char*)addresses)+i*addrlen, addrlen);
4436 ai = evutil_new_addrinfo(sa, socklen, &data->hints);
4437 if (!ai) {
4438 if (other_req->r) {
4439 evdns_cancel_request(NULL, other_req->r);
4441 data->user_cb(EVUTIL_EAI_MEMORY, NULL, data->user_data);
4442 if (res)
4443 evutil_freeaddrinfo(res);
4445 if (other_req->r == NULL)
4446 free_getaddrinfo_request(data);
4447 return;
4449 res = evutil_addrinfo_append(res, ai);
4452 if (other_req->r) {
4453 /* The other request is still in progress; wait for it */
4454 /* XXXX handle failure from set_timeout */
4455 evdns_getaddrinfo_set_timeout(data->evdns_base, data);
4456 data->pending_result = res;
4457 return;
4458 } else {
4459 /* The other request is done or never started; append its
4460 * results (if any) and return them. */
4461 if (data->pending_result) {
4462 if (req->type == DNS_IPv4_A)
4463 res = evutil_addrinfo_append(res,
4464 data->pending_result);
4465 else
4466 res = evutil_addrinfo_append(
4467 data->pending_result, res);
4468 data->pending_result = NULL;
4471 /* Call the user callback. */
4472 add_cname_to_reply(data, res);
4473 data->user_cb(0, res, data->user_data);
4475 /* Free data. */
4476 free_getaddrinfo_request(data);
4480 static struct hosts_entry *
4481 find_hosts_entry(struct evdns_base *base, const char *hostname,
4482 struct hosts_entry *find_after)
4484 struct hosts_entry *e;
4486 if (find_after)
4487 e = TAILQ_NEXT(find_after, next);
4488 else
4489 e = TAILQ_FIRST(&base->hostsdb);
4491 for (; e; e = TAILQ_NEXT(e, next)) {
4492 if (!evutil_ascii_strcasecmp(e->hostname, hostname))
4493 return e;
4495 return NULL;
4498 static int
4499 evdns_getaddrinfo_fromhosts(struct evdns_base *base,
4500 const char *nodename, struct evutil_addrinfo *hints, ev_uint16_t port,
4501 struct evutil_addrinfo **res)
4503 int n_found = 0;
4504 struct hosts_entry *e;
4505 struct evutil_addrinfo *ai=NULL;
4506 int f = hints->ai_family;
4508 EVDNS_LOCK(base);
4509 for (e = find_hosts_entry(base, nodename, NULL); e;
4510 e = find_hosts_entry(base, nodename, e)) {
4511 struct evutil_addrinfo *ai_new;
4512 ++n_found;
4513 if ((e->addr.sa.sa_family == AF_INET && f == PF_INET6) ||
4514 (e->addr.sa.sa_family == AF_INET6 && f == PF_INET))
4515 continue;
4516 ai_new = evutil_new_addrinfo(&e->addr.sa, e->addrlen, hints);
4517 if (!ai_new) {
4518 n_found = 0;
4519 goto out;
4521 sockaddr_setport(ai_new->ai_addr, port);
4522 ai = evutil_addrinfo_append(ai, ai_new);
4524 EVDNS_UNLOCK(base);
4525 out:
4526 if (n_found) {
4527 /* Note that we return an empty answer if we found entries for
4528 * this hostname but none were of the right address type. */
4529 *res = ai;
4530 return 0;
4531 } else {
4532 if (ai)
4533 evutil_freeaddrinfo(ai);
4534 return -1;
4538 struct evdns_getaddrinfo_request *
4539 evdns_getaddrinfo(struct evdns_base *dns_base,
4540 const char *nodename, const char *servname,
4541 const struct evutil_addrinfo *hints_in,
4542 evdns_getaddrinfo_cb cb, void *arg)
4544 struct evdns_getaddrinfo_request *data;
4545 struct evutil_addrinfo hints;
4546 struct evutil_addrinfo *res = NULL;
4547 int err;
4548 int port = 0;
4549 int want_cname = 0;
4551 if (!dns_base) {
4552 dns_base = current_base;
4553 if (!dns_base) {
4554 log(EVDNS_LOG_WARN,
4555 "Call to getaddrinfo_async with no "
4556 "evdns_base configured.");
4557 cb(EVUTIL_EAI_FAIL, NULL, arg); /* ??? better error? */
4558 return NULL;
4562 /* If we _must_ answer this immediately, do so. */
4563 if ((hints_in && (hints_in->ai_flags & EVUTIL_AI_NUMERICHOST))) {
4564 res = NULL;
4565 err = evutil_getaddrinfo(nodename, servname, hints_in, &res);
4566 cb(err, res, arg);
4567 return NULL;
4570 if (hints_in) {
4571 memcpy(&hints, hints_in, sizeof(hints));
4572 } else {
4573 memset(&hints, 0, sizeof(hints));
4574 hints.ai_family = PF_UNSPEC;
4577 evutil_adjust_hints_for_addrconfig(&hints);
4579 /* Now try to see if we _can_ answer immediately. */
4580 /* (It would be nice to do this by calling getaddrinfo directly, with
4581 * AI_NUMERICHOST, on plaforms that have it, but we can't: there isn't
4582 * a reliable way to distinguish the "that wasn't a numeric host!" case
4583 * from any other EAI_NONAME cases.) */
4584 err = evutil_getaddrinfo_common(nodename, servname, &hints, &res, &port);
4585 if (err != EVUTIL_EAI_NEED_RESOLVE) {
4586 cb(err, res, arg);
4587 return NULL;
4590 /* If there is an entry in the hosts file, we should give it now. */
4591 if (!evdns_getaddrinfo_fromhosts(dns_base, nodename, &hints, port, &res)) {
4592 cb(0, res, arg);
4593 return NULL;
4596 /* Okay, things are serious now. We're going to need to actually
4597 * launch a request.
4599 data = mm_calloc(1,sizeof(struct evdns_getaddrinfo_request));
4600 if (!data) {
4601 cb(EVUTIL_EAI_MEMORY, NULL, arg);
4602 return NULL;
4605 memcpy(&data->hints, &hints, sizeof(data->hints));
4606 data->port = (ev_uint16_t)port;
4607 data->ipv4_request.type = DNS_IPv4_A;
4608 data->ipv6_request.type = DNS_IPv6_AAAA;
4609 data->user_cb = cb;
4610 data->user_data = arg;
4611 data->evdns_base = dns_base;
4613 want_cname = (hints.ai_flags & EVUTIL_AI_CANONNAME);
4615 /* If we are asked for a PF_UNSPEC address, we launch two requests in
4616 * parallel: one for an A address and one for an AAAA address. We
4617 * can't send just one request, since many servers only answer one
4618 * question per DNS request.
4620 * Once we have the answer to one request, we allow for a short
4621 * timeout before we report it, to see if the other one arrives. If
4622 * they both show up in time, then we report both the answers.
4624 * If too many addresses of one type time out or fail, we should stop
4625 * launching those requests. (XXX we don't do that yet.)
4628 if (hints.ai_family != PF_INET6) {
4629 log(EVDNS_LOG_DEBUG, "Sending request for %s on ipv4 as %p",
4630 nodename, &data->ipv4_request);
4632 data->ipv4_request.r = evdns_base_resolve_ipv4(dns_base,
4633 nodename, 0, evdns_getaddrinfo_gotresolve,
4634 &data->ipv4_request);
4635 if (want_cname)
4636 data->ipv4_request.r->current_req->put_cname_in_ptr =
4637 &data->cname_result;
4639 if (hints.ai_family != PF_INET) {
4640 log(EVDNS_LOG_DEBUG, "Sending request for %s on ipv6 as %p",
4641 nodename, &data->ipv6_request);
4643 data->ipv6_request.r = evdns_base_resolve_ipv6(dns_base,
4644 nodename, 0, evdns_getaddrinfo_gotresolve,
4645 &data->ipv6_request);
4646 if (want_cname)
4647 data->ipv6_request.r->current_req->put_cname_in_ptr =
4648 &data->cname_result;
4651 evtimer_assign(&data->timeout, dns_base->event_base,
4652 evdns_getaddrinfo_timeout_cb, data);
4654 if (data->ipv4_request.r || data->ipv6_request.r) {
4655 return data;
4656 } else {
4657 mm_free(data);
4658 cb(EVUTIL_EAI_FAIL, NULL, arg);
4659 return NULL;
4663 void
4664 evdns_getaddrinfo_cancel(struct evdns_getaddrinfo_request *data)
4666 EVDNS_LOCK(data->evdns_base);
4667 if (data->request_done) {
4668 EVDNS_UNLOCK(data->evdns_base);
4669 return;
4671 event_del(&data->timeout);
4672 data->user_canceled = 1;
4673 if (data->ipv4_request.r)
4674 evdns_cancel_request(data->evdns_base, data->ipv4_request.r);
4675 if (data->ipv6_request.r)
4676 evdns_cancel_request(data->evdns_base, data->ipv6_request.r);
4677 EVDNS_UNLOCK(data->evdns_base);